WO2018188027A1 - Control method and control system for multi-speed multi-power electric motor - Google Patents

Abstract

Disclosed are a control method and a control system for a multi-speed multi-power electric motor. The control method comprises: connecting a first contactor, driving a first winding and detecting the rotational speed of the first winding, and when the rotational speed reaches a pre-set rotational speed and a frequency converter stops output, disconnecting the first contactor; after the first contactor is completely disconnected, connecting a second contactor, so that the frequency converter is connected to a second winding by means of the second contactor; after the second contactor is completely connected, driving the second winding by the frequency converter, and tracking a phase current and a phase voltage of the second winding to acquire the motor speed and the phase of the second winding; smoothly controlling the second winding by the frequency converter; after the rotational speed of the second winding reaches an industrial frequency, carrying out phase locking on an input voltage and an output voltage of the frequency converter, and when the frequency converter stops output after phase locking, disconnecting the second contactor; and after the second contactor is completely disconnected, connecting a third contactor, and smoothly switching the second winding to operate at a power frequency. A heavy impact current cannot be generated during switching.

Description

Multi-speed multi-power motor control method and control system

[Technical Field]

The present invention relates to the field of electronic technologies, and in particular, to a multi-speed multi-power motor control method and control system.

【Background technique】

In many equipment, such as the boring machine in oilfield equipment, the frictional resistance of the equipment is very high when starting, and it is necessary to provide sufficient starting torque to make the equipment work. When the system is started, the device can operate according to the inertia, and the sliding friction of the device is small. At this time, only a small torque is needed to maintain the operation of the device. For ordinary motors, the output torque corresponds to the output power. Therefore, selecting a large torque motor means that the power of the motor should also be amplified. However, after the equipment is started, only a small power motor can be used to maintain operation, and high power is selected. The motor means an increase in energy consumption.

In order to solve the above problems, the motor manufacturer has designed a multi-winding motor that can realize multi-speed and multi-power operation. At start-up, select the low speed high torque winding to increase the starting torque. After starting, switch to high speed and low torque winding. After reaching the power frequency, switch to power frequency operation.

For this new type of motor, the contactor has been used to directly convert the individual windings. However, since the current impact is large when the contactor is switched, it is necessary to select a contactor whose capacity is much larger than the normal use capacity. But even then, the damage rate of the contactor is still high.

[Summary of the Invention]

Based on this, it is necessary to provide a multi-speed multi-power motor control method and control system with a lower contactor damage rate.

A multi-speed multi-power motor control method, the multi-speed multi-power motor comprising at least a first winding, a second winding, a first contactor, a second contactor and a third contactor, the control method comprising:

Pulling the first contactor to make the frequency converter conduct through the first contactor and the first winding;

The frequency converter drives the first winding and detects the first winding speed. When the first winding speed reaches a predetermined speed, the frequency converter stops outputting, and then disconnects the first contactor;

After detecting that the first contactor is completely disconnected, the second contactor is sucked, and the frequency converter is electrically connected to the second winding through the second contactor;

After detecting that the second contactor is fully attracted, the frequency converter drives the second winding and tracks the phase current and the phase voltage of the second winding, and obtains the second winding according to the phase current and the phase voltage of the second winding. Motor speed and phase;

Performing a smooth control of the second winding according to the motor speed and phase inverter of the second winding;

Detecting the working frequency of the second winding, when the working frequency of the second winding reaches the power frequency, phase-locking the input voltage and the output voltage of the frequency converter, and after the phase is locked, the frequency converter stops outputting, and then disconnects the second contactor;

After detecting that the second contactor is completely disconnected, the third contactor is attracted, and the second winding is smoothly switched to a power frequency operation.

A multi-speed multi-power motor control system, the multi-speed multi-power motor comprising at least a first winding and a second winding, the control system comprising:

The first contactor has one end connected to the other end of the inverter output end connected to the first winding;

a second contactor, one end connected to the other end of the inverter output end connected to the second winding;

a third contactor, one end connected to the three-phase voltage input end and the other end connected to the second winding;

The frequency converter is configured to pull the first contactor to make the frequency converter conduct the first winding through the first contactor; drive the first winding and detect the first winding speed, and stop when the first winding speed reaches the predetermined speed The inverter outputs, and then disconnects the first contactor; when detecting that the first contactor is completely disconnected, the second contactor is sucked to make the inverter pass through the second contactor and the second winding; when detecting After the second contactor is fully engaged, driving the second winding and tracking the phase current and the phase voltage of the second winding, and obtaining the motor speed and phase corresponding to the second winding according to the phase current and the phase voltage of the second winding; Describe the motor speed and phase of the second winding, so that the frequency converter smoothly controls the second winding; detects the working frequency of the second winding, and phase locks the input voltage and the output voltage of the frequency converter when the working frequency of the second winding reaches the power frequency. When the phase is locked, the inverter stops outputting, and then the second contactor is disconnected; when the second contactor is completely disconnected, the third contactor is sucked, and the second winding is smoothly switched to the industrial frequency .

In the above multi-speed multi-power motor control method and control system, after the inverter sends a contactor pull-in or off signal, the contactor feedback signal is detected in real time. If the feedback signal indicates that the contactor has not been pulled or disconnected at this time, the next control action is temporarily stopped. When it is detected that the contactor feedback signal indicates that the contact has been reliably pulled or disconnected, the next step is to drive the motor or switch the contactor, so that no large inrush current is generated, and the inverter is not damaged or the inverter is tripped. The frequency converter is smoothly switched to the second winding through the speed tracking module, and the second winding is smoothly switched from the frequency converter to the power frequency operation by phase locking the input voltage and the output voltage of the frequency converter, and the current impact is small in the switching project.

[Description of the Drawings]

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the embodiments or the description of the prior art will be briefly described below. Obviously, the drawings in the following description are only It is a certain embodiment of the present invention, and those skilled in the art can obtain drawings of other embodiments according to the drawings without any creative work.

1 is a flow chart of a multi-speed multi-power motor control method in an embodiment;

2 is a schematic diagram of shaping an original sine wave signal into a square wave signal in an embodiment;

3 is a current waveform of a motor in direct start rotation in an embodiment;

4 is a current and voltage waveform when a rotating motor is started by using a speed tracking function in an embodiment;

FIG. 5 is a waveform diagram of a frequency-cutting cut-off frequency when no phase detection is performed in an embodiment; FIG.

6 is an embodiment of the phase-inverted frequency-cutting power frequency waveform;

7 is a flow chart of a multi-speed multi-power motor control method in another embodiment;

8 is a structural block diagram of a multi-speed multi-power motor control system in an embodiment;

9 is a partial circuit diagram of a speed tracking module in an embodiment;

Figure 10 is a block diagram showing another structure of a multi-speed multi-power motor control system in an embodiment.

 【detailed description】

In order to facilitate the understanding of the present invention, the present invention will be described more fully hereinafter with reference to the accompanying drawings. Preferred embodiments of the invention are shown in the drawings. However, the invention may be embodied in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided so that the understanding of the present disclosure will be more fully understood.

Referring to FIG. 1, a flowchart of a multi-speed multi-power motor control method, the multi-speed multi-power motor includes at least a first winding, a second winding, a first contactor, a second contactor and a third contactor, and the control method includes The following steps S110 to S170.

Step S110: Pulling the first contactor to make the inverter pass through the first contactor and the first winding.

The frequency converter first controls the action of the first relay, controls the first contactor to be turned on and on, and connects the output end of the frequency converter to the first winding.

Step S120: The frequency converter drives the first winding and detects the first winding speed. When the first winding speed reaches the predetermined speed, the inverter stops outputting, and then the first contactor is disconnected.

The frequency converter detects the first winding speed through the speed detecting module. When the predetermined speed is reached, the second winding of the first winding is switched. The switching process first stops the output of the frequency converter, and then disconnects the first contactor. The nameplate parameters of the multi-speed multi-power motor can be input into the motor parameter module of the inverter first, which can be input through the inverter's own operation panel; the stator resistance corresponding to each motor speed of the motor is obtained by the parameter self-tuning function built in the inverter. , rotor resistance, leakage inductance, mutual inductance, no-load current and other parameters. Referred to as the first group of parameters, the second group of parameters. The first set of parameters corresponds to the first winding, and the second set of parameters corresponds to the second winding. The rated speed of the first winding is obtained according to the first set of parameters. The predetermined rotational speed may be equal to the rated rotational speed of the first winding, or may be less than the rated rotational speed of the first winding as needed. Step S130: After detecting that the first contactor is completely disconnected, the second contactor is sucked, and the frequency converter is turned on by the second contactor and the second winding.

The frequency converter controls the action of the second relay to control the second contactor to be turned on and off, and the output end of the frequency converter is connected to the second winding.

Step S140: After detecting that the second contactor is fully engaged, the inverter drives the second winding and tracks the phase current and the phase voltage of the second winding, and obtains the motor speed of the second winding according to the phase current and the phase voltage of the second winding. With phase.

Wherein, when the frequency converter drives the second winding, the speed tracking module is started, and the speed tracking module tracks the phase current and the phase voltage of the second winding. Specifically, the speed tracking module calculates a first phase voltage and a second phase voltage of the three-phase voltage of the second winding to obtain a first determination voltage, and the rotation speed tracking module compares the second phase voltage of the three-phase voltage of the second winding The third phase voltage is calculated to obtain a second determination voltage.

Forming the first determining voltage and the second determining voltage into a square wave, and when the square wave of the first determining voltage shaping is at the rising edge of the voltage, if the square wave voltage after the second determining voltage shaping is at a low level, the motor rotates The direction is the first direction, otherwise the motor rotation direction is the second direction opposite to the first direction. The first direction may be a counterclockwise direction, and the second direction may be a clockwise direction. Of course, the first direction may be a clockwise direction, and the second direction may be a counterclockwise direction.

The first phase voltage and the second phase voltage of the three-phase voltage in the second winding form a first set of phase voltages, a second phase voltage, and a third phase voltage to form a second set of phase voltages, the first set of phase voltages or a second The phase voltages are subjected to two sets of differential proportional operations to obtain two unequal first base voltages and second base voltages, wherein the first base voltage is smaller than the second base voltage; the first base voltage is sampled and the maximum value of the sampled values is obtained. If the maximum value of the sampled value is less than the preset threshold, the second base voltage is the first determination voltage or the second determination voltage, otherwise the first base voltage is the first determination voltage or the second determination voltage. The preset threshold is a voltage value, which is mainly used to distinguish between a large voltage and a small voltage, and can be obtained by a rated voltage of 1/3 to 1/4 of the driver. Of course, in order to distinguish between a large voltage and a small voltage, other values can be set.

Further, obtaining the maximum value of the sampled value may be obtained by the following method: the first base voltage is determined from the negative to positive change, and the magnitude of the first basic voltage is determined, and the larger first basic voltage in each comparison is set as the sampling. The maximum value of the value until the first base voltage is negative.

Further, the first determination voltage may be subjected to low-pass filtering and/or zero-bias processing to be an AD voltage having a small amplification factor. The second determination voltage may be subjected to low-pass filtering and/or zero-bias processing to an AD voltage having a large amplification factor.

Referring to FIG. 2, the line voltage of the second winding is shaped into a square wave, and the square wave frequency is calculated to obtain the rotation frequency of the motor at this time. Obtaining the rotation frequency of the motor at this time also obtains the rotation speed of the motor at this time. The line voltage may be the first determination voltage or the second determination voltage.

Step S150: Smoothly controlling the second winding according to the motor speed and phase inverter of the second winding.

Obtaining the motor speed and phase of the second winding, and then allowing the inverter to smoothly control the second winding can effectively reduce the current surge. See Figure 3, where the L3 curve is the current waveform of the motor in the direct start rotation, which can be seen in the switching process. There are obvious fluctuations in the medium. See Figure 4, using the speed tracking function to start the current and voltage waveforms of the rotating motor, where L1 is the line voltage waveform and L2 is the current waveform of the motor. Comparing Figure 3, the current fluctuation during the conversion process can be clearly seen. It has been reduced a lot.

Step S160: detecting the working frequency of the second winding. When the working frequency of the second winding reaches the power frequency, the input voltage and the output voltage of the inverter are phase-locked. When the phase is locked, the inverter stops outputting, and then the second contactor is disconnected. .

The rotational speed and operating frequency of the second winding can be calculated from the second set of parameters. Further, when the inverter stops outputting after the phase is locked, the operating frequency of the second winding can be slightly larger than the power frequency, so that the operating frequency of the second winding is lowered after the inverter stops outputting, and then matched with the power frequency.

The phase locking of the input voltage and the output voltage of the frequency converter comprises: obtaining the input voltages Ur, Us and Ut of the frequency converter; projecting the three-phase input voltages Ur, Us and Ut into the two-phase stationary coordinate system by coordinate changes to obtain Ud, Uq; Obtaining the angle θ1 of the synthesized voltage vector with respect to the coordinate system according to Uq, Ud; obtaining the inverter output voltages Ur', Us' and Ut'; projecting the three-phase output voltages Ur', Us' and Ut' by coordinate changes to Two-phase stationary coordinate system acquires Ud', Uq'; obtains an angle θ2 of the composite voltage vector with respect to the coordinate system according to Uq', Ud'; phase lock according to the difference between the angle θ1 and the angle θ2, the phase lock includes The input voltage angle θ1 and the output voltage angle θ2 are substituted into the phase-locked loop module, and the output PWM wave of the inverter is controlled by the phase-locked loop module, so that the output voltage angle θ2 approaches the input voltage angle θ1. If the angle θ1 is equal to or nearly equal to the angle θ2, the phase lock is considered.

Step S170: After detecting that the second contactor is completely disconnected, the third contactor is sucked, and the second winding is smoothly switched to the power frequency operation.

Due to the PWM wave output mode, the inverter has high harmonics and high frequency noise at the output voltage. The inverter drives the motor. When the load has a power generation state, the inverter needs to be equipped with a brake unit and a braking resistor. This is not the case for direct grid-connected motors. However, to switch the motor driven by the inverter to the grid, in order to avoid the current surge during switching, it is necessary to control the frequency and phase of the inverter output voltage when switching.

Referring to Figure 5, the frequency-cutting power frequency waveform is not added when phase detection is used, where L7 is the motor current waveform, L8 is the grid voltage waveform, and L9 is the motor line voltage waveform. It can be seen that when switching the power frequency, the motor current is very large. fluctuation. Referring to Figure 6, the frequency-cutting power-frequency waveform is added when phase detection is added, where L4 is the motor current waveform, L5 is the grid voltage waveform, and L6 is the motor line voltage waveform. It can be seen that the motor current fluctuation is significantly smaller when switching the power frequency. .

Since the contactor has conduction and turn-off time, and the contactor turn-on/turn-off time of different loads is different, if the contactor turn-on and turn-off time are not considered, it will cause a great deal when the contactor is turned on and off. Current surges may damage the drive or the motor and may also cause trip protection. If the inverter has voltage and frequency output during the conduction process of the contactor, it is equivalent to directly connecting the motor when the inverter is running. If the inverter has already issued a large output voltage and frequency, a large inrush current will be generated. It is possible to damage the inverter or trip the inverter for protection. If the contactor is switched during the contactor shut-off process, such as when the KM2 is disconnected, during the KM3 pull-in process, if the KM2 has not been reliably disconnected, the KM3 has been pulled in, which is equivalent to directly inputting the input grid voltage to the inverter output. On the side, it may cause damage to the inverter. In this embodiment, after the inverter issues a contactor pull-in/off signal, the contactor feedback signal is detected in real time to accurately know the current state of the contactor. If the feedback signal indicates that the contactor has not been engaged/disconnected at this time, the next control action is temporarily stopped. When it is detected that the contactor feedback signal indicates that the contact has been reliably pulled/disconnected, the next step is to drive the motor or switch the contactor.

In one embodiment, after the first contactor is disconnected, the timing module is turned on, and if the preset time of the timing module is up and the first contactor is not completely disconnected, a fault alarm is issued; after the second contactor is disconnected, the fault is turned on. The timing module issues a fault alarm if the preset time of the timing module is up and the second contactor is not completely disconnected.

Referring to Figure 7, a flow chart of another multi-speed multi-power motor control method.

Obtain the nameplate parameters of the multi-speed multi-power motor.

Parameters such as stator resistance, rotor resistance, leakage inductance, mutual inductance, and no-load current corresponding to each motor speed of the motor are obtained by the parameter self-tuning function built in the inverter. Referred to as the first group of parameters, the second group of parameters.

The frequency converter controls the action of the first relay, controls the first contactor to be turned on and off, and connects the output end of the frequency converter to the first winding.

Determine whether the first contactor is fully engaged, if the first winding is turned on completely; if not fully closed, the timing function is turned on, and the first contactor prompts the fault alarm if it is not fully engaged, and the timing time has not expired. Control the first contactor to pull in.

The first winding speed is detected. When the first winding speed reaches the predetermined speed, the inverter controls the first relay to control, and the first contactor is controlled to be disconnected; if not, the detection is continued.

Judging whether the first contactor is completely disconnected, if the second contactor is closed, if it is completely disconnected; if it is not completely disconnected, the timing function is turned on, and the first contactor prompts the fault alarm if it is not completely disconnected, timing The time has not reached the control of the first contactor.

Determine whether the second contactor is fully engaged, if the second winding is turned on completely; if not fully closed, the timing function is turned on, and the first contactor prompts the fault alarm if it is not fully engaged, and the timing time has not expired. Control the first contactor to pull in.

The working frequency of the second winding is detected, and the second contactor is controlled to be disconnected when the power frequency is reached, and the detection is continued if it is not reached.

Judging whether the second contactor is completely disconnected, if the third contactor is completely disconnected, the second winding is smoothly switched to the power frequency operation; if not completely disconnected, the timing function is turned on, the timing is up, the first contactor If it is not completely disconnected, it will prompt a fault alarm, and the timing time has not reached the control of the second contactor.

The method in the above embodiment can control the two-speed dual-power motor. The specific steps are as described above, and the multi-speed multi-power motor such as the three-speed three-power motor and the four-speed four-power motor can be controlled in the same manner.

Referring to FIG. 8, the multi-speed multi-power motor in the multi-speed multi-power motor control system includes at least a first winding 210 and a second winding 220. The control system includes:

The first contactor KM1, one end is connected to the output end of the frequency converter 100 and the other end is connected to the first winding 210;

The second contactor KM2, one end is connected to the output end of the frequency converter 100 and the other end is connected to the second winding 220;

The third contactor KM3, one end connected to the three-phase voltage input end and the other end connected to the second winding 220;

The frequency converter 100 is configured to draw the first contactor KM1 at a predetermined rotation speed, so that the frequency converter is electrically connected to the first winding 210 through the first contactor KM1; drive the first winding 210 and detect the rotation speed of the first winding 210, when the first When the rotation speed of the winding 210 reaches the predetermined rotation speed, the output of the frequency converter 100 is stopped, and then the first contactor KM1 is disconnected; when the first contactor KM1 is completely disconnected, the second contactor KM2 is sucked, and the frequency converter 100 is passed. The second contactor KM2 is electrically connected to the second winding 220; when it is detected that the second contactor KM2 is fully attracted, the second winding 220 is driven and the phase current and the phase voltage of the second winding 220 are tracked according to the second winding 220 The phase current and the phase voltage obtain the motor rotation speed and phase corresponding to the second winding 220; according to the motor rotation speed and phase of the second winding 220, the frequency converter 100 smoothly controls the second winding 220; and detects the operating frequency of the second winding 220, when When the two windings 220 reach the power frequency, the input voltage and the output voltage of the inverter 100 are phase-locked. When the phase is locked, the inverter 100 stops outputting, and then the second contactor KM2 is disconnected; when the second contactor KM2 is detected completely Broken After the third contactor KM3 pull the smooth handover to the second winding 220 frequency operation. The frequency converter is also used to obtain the three-phase input voltages Ur, Us and Ut of the frequency converter; the three-phase input voltages Ur, Us and Ut are projected to the two-phase stationary coordinate system by coordinate changes to obtain the two-phase voltage Ud, Uq; The voltages Uq, Ud calculate the angle θ1 of the combined voltage vector with respect to the coordinate system; acquire the three-phase output voltages Ur', Us' and Ut' of the frequency converter; project the three-phase output voltages Ur', Us' and Ut' by coordinate changes Obtain two-phase voltages Ud', Uq' from the two-phase stationary coordinate system; obtain the angle θ2 of the composite voltage vector with respect to the coordinate system according to the two-phase voltages Uq', Ud'; according to the difference between the angle θ1 and the angle θ2 Phase locking is performed, and the phase lock is considered if the difference between the angle θ1 and the angle θ2 is less than the preset difference.

Among them, the nameplate parameter of the multi-speed multi-power motor can be input into the motor parameter module of the inverter first, which can be input through the inverter's own operation panel; the parameter self-tuning function built in the inverter respectively obtains the corresponding speed of the motor. Stator resistance, rotor resistance, leakage inductance, mutual inductance, no-load current and other parameters. Referred to as the first group of parameters, the second group of parameters. The first set of parameters corresponds to the first winding, and the second set of parameters corresponds to the second winding. The rated speed of the first winding is obtained according to the first set of parameters. The predetermined rotational speed may be equal to the rated rotational speed of the first winding, or may be less than the rated rotational speed of the first winding as needed. It is also possible to calculate the rotational speed and operating frequency of the second winding based on the second set of parameters. When the inverter stops output after phase lock, the operating frequency of the second winding can be slightly larger than the power frequency, so that the operating frequency of the second winding is reduced after the inverter stops outputting, and then matched with the power frequency.

The frequency converter includes a phase lock module, and the phase lock module is configured to obtain an input voltage angle θ1 and an output voltage angle θ2, and control an output PWM wave of the frequency converter such that the output voltage angle θ2 approaches the input voltage angle θ1.

In one embodiment, the frequency converter further includes a speed tracking module, the speed tracking module is configured to track the phase current and the phase voltage of the second winding, and the speed tracking module is simultaneously activated when the frequency converter drives the second winding.

Specifically, the rotation speed tracking module includes a first rotation speed tracking unit and a second rotation speed tracking unit, and the first input end and the second input end of the first rotation speed tracking unit respectively correspond to the three-phase voltage first phase voltage and the three-phase voltage second phase a voltage connection, the output end of the first speed tracking unit is connected to the digital signal processor, and the third input end and the fourth input end of the second speed tracking unit are respectively connected to the second phase voltage and the third phase voltage of the three-phase voltage, The output of the second rotational speed tracking unit is coupled to the digital signal processor.

Referring to FIG. 9, the first speed tracking unit includes a first operational amplifier IC1 and a second operational amplifier IC2;

The inverting input terminal of the first operational amplifier IC1 is connected to the three-phase voltage first phase voltage through the resistor R1, and the non-inverting input terminal of the first operational amplifier IC1 is connected to the three-phase voltage second phase voltage through the resistor R2, and the first operational amplifier IC1 is in phase. The input terminal is also grounded through a resistor R5. The output end of the first operational amplifier IC1 is connected to the inverting input end of the first operational amplifier IC1 through a resistor R4. The output end of the first operational amplifier IC1 is connected to one end of the resistor R11, and the other end of the resistor R11 is passed through a resistor. R12 is connected to the power supply end, and the other end of the resistor R11 is also connected to the digital signal processor;

The inverting input terminal of the second operational amplifier IC2 is connected to the inverting input terminal of the first operational amplifier IC1, the non-inverting input terminal of the second operational amplifier IC2 is connected to the non-inverting input terminal of the first operational amplifier IC1, and the non-inverting input of the second operational amplifier IC2 The terminal is also grounded through a resistor R7, and the output end of the second operational amplifier IC2 is connected to the inverting input terminal of the second operational amplifier IC2 through a resistor R6, the output end of the second operational amplifier IC2 is connected to one end of the resistor R13, and the other end of the resistor R13 is passed through a resistor R14. Connected to the power supply end, the other end of the resistor R13 is also connected to the digital signal processor;

The resistance of the resistor R6 is greater than the resistance of the resistor R4. The power supply terminal can be 3.3V or other voltages such as 5V.

The resistance of the resistor R6 can be ten times the resistance of the resistor R4. Of course, the resistance of the resistor R6 can also be set to five times, eight times, twenty times, and the like of the resistance of the resistor R4 as needed.

The other end of the resistor R11 is connected to the two clamp diodes D4 and connected to the digital signal processor; one of the two clamp diodes D4 is connected to the anode and the negative pole is connected to the other end of the resistor R11, and the other diode is connected to the negative terminal of the power supply terminal. . The other end of the resistor R13 is connected to the two clamp diodes D5 and connected to the digital signal processor; one of the two clamp diodes D5 is connected to the anode and the negative pole is connected to the other end of the resistor R13, and the other diode is connected to the power supply terminal and the positive terminal is connected to the other end of the resistor R13. . The output of the first operational amplifier IC1 processes the output voltage through R11 and R12 and the power supply terminal to a positive voltage suitable for DSP processing. After passing through two clamp diodes D4, it is directly sent to the AD port UVad1 of the digital signal processor DSP. Similarly, the output of the first operational amplifier IC2 is processed by the R13 and R14 and the power supply terminal to be processed by the digital signal processor DSP. Positive voltage. After passing through two clamp diodes D5, it is directly sent to the AD port UVad2 of the digital signal processor DSP.

The frequency converter 100 further includes a first relay for controlling the opening and closing of the first contactor KM1, a second relay for controlling the opening and closing of the second contactor KM2, and a third control for controlling the opening and closing of the third contactor KM3. Relay. The frequency converter 100 also includes an input for obtaining a contactor feedback signal, the number of which is set according to the number of contactors.

The motor in the system adopts multi-speed multi-power motor, which can input the parameters of multiple sets of motors, such as three groups and four groups, which provides possibility for different power motor switching of different speeds; it can provide large torque start; it can automatically judge the load condition. Turns into energy-saving mode when light load; has speed tracking function, can automatically recognize motor speed; has industrial frequency conversion switching module, can detect the phase and frequency of motor phase voltage and phase current, and simultaneously detect the phase angle and phase of the power grid, smooth the device Switch to grid operation.

In the above embodiment, the first phase voltage of the three-phase voltage is the U-phase voltage, the second phase voltage is the V-phase voltage, and the third phase voltage is the W-phase voltage. Of course, you can also set it as needed.

Referring to Figure 10, another multi-speed multi-power motor control system. The main difference from the previous embodiment is that the motor is a three-speed three-power motor, and one end of the third contactor KM3 is connected to the other end of the grid and connected to the third winding 230.

The technical features of the above-described embodiments may be arbitrarily combined. For the sake of brevity of description, all possible combinations of the technical features in the above embodiments are not described. However, as long as there is no contradiction between the combinations of these technical features, All should be considered as the scope of this manual.

The above-described embodiments are merely illustrative of several embodiments of the present invention, and the description thereof is more specific and detailed, but is not to be construed as limiting the scope of the invention. It should be noted that a number of variations and modifications may be made by those skilled in the art without departing from the spirit and scope of the invention. Therefore, the scope of the invention should be determined by the appended claims.

Claims (20)

1. A multi-speed multi-power motor control method, the multi-speed multi-power motor comprising at least a first winding, a second winding, a first contactor, a second contactor and a third contactor, wherein the control method include:

   The predetermined speed is used to pull the first contactor to make the frequency converter conduct the first winding through the first contactor;

   The frequency converter drives the first winding and detects the first winding speed. When the first winding speed reaches a predetermined speed, the frequency converter stops outputting, and then disconnects the first contactor;

   After detecting that the first contactor is completely disconnected, the second contactor is sucked, and the frequency converter is electrically connected to the second winding through the second contactor;

   After detecting that the second contactor is fully attracted, the frequency converter drives the second winding and tracks the phase current and the phase voltage of the second winding, and obtains the second winding according to the phase current and the phase voltage of the second winding. Motor speed and phase;

   Performing a smooth control of the second winding according to the motor speed and phase inverter of the second winding;

   Detecting the working frequency of the second winding, when the working frequency of the second winding reaches the power frequency, phase-locking the input voltage and the output voltage of the frequency converter, and after the phase is locked, the frequency converter stops outputting, and then disconnects the second contactor;

   After detecting that the second contactor is completely disconnected, the third contactor is attracted, and the second winding is smoothly switched to a power frequency operation.
2. The multi-speed multi-power motor control method according to claim 1, wherein the phase locking of the input voltage and the output voltage of the frequency converter comprises:

   Obtain the three-phase input voltages Ur, Us and Ut of the inverter;

   Projecting the three-phase input voltages Ur, Us, and Ut to a two-phase stationary coordinate system by coordinate changes to obtain two-phase voltages Ud, Uq;

   Obtaining an angle θ1 of the synthesized voltage vector with respect to the coordinate system according to the two-phase voltages Uq, Ud;

   Obtain the three-phase output voltages Ur', Us' and Ut' of the inverter;

   Projecting the three-phase output voltages Ur', Us' and Ut' to the two-phase stationary coordinate system by coordinate changes to obtain two-phase voltages Ud', Uq';

   Obtaining an angle θ2 of the synthesized voltage vector with respect to the coordinate system according to the two-phase voltages Uq', Ud';

   The phase is locked according to the difference between the angle θ1 and the angle θ2, and the phase lock is considered if the difference between the angle θ1 and the angle θ2 is less than the preset difference.
3. The multi-speed multi-power motor control method according to claim 2, wherein the phase locking according to the difference between the angle θ1 and the angle θ2 comprises:

   The input voltage angle θ1 and the output voltage angle θ2 are substituted into the phase-locked loop module, and the output PWM wave of the inverter is controlled by the phase-locked loop module, so that the output voltage angle θ2 approaches the input voltage angle θ1.
4. A multi-speed multi-power motor control method according to claim 1, wherein

   When the inverter drives the second winding, the speed tracking module is started, and the speed tracking module tracks the phase current and the phase voltage of the second winding.
5. A multi-speed multi-power motor control method according to claim 4, wherein

   The speed tracking module calculates a first phase voltage and a second phase voltage of the three-phase voltage of the second winding to obtain a first determination voltage, and the speed tracking module sets a second phase voltage of the three-phase voltage of the second winding And calculating a second phase voltage to obtain a second determination voltage;

   Forming the first determining voltage and the second determining voltage into a square wave, and when the square wave of the first determining voltage shaping is at the rising edge of the voltage, if the square wave voltage after the second determining voltage shaping is at a low level, the motor rotates The direction is the first direction, otherwise the motor rotation direction is the second direction opposite to the first direction.
6. A multi-speed multi-power motor control method according to claim 5, wherein

   The first phase voltage and the second phase voltage of the three-phase voltage in the second winding form a first set of phase voltages, a second phase voltage, and a third phase voltage to form a second set of phase voltages, the first set of phase voltages or a second The phase voltages are subjected to two sets of differential ratio operations to obtain two unequal first base voltages and second base voltages, wherein the first base voltage is less than the second base voltage;

   Sampling the first base voltage and obtaining a maximum value of the sampled value. If the maximum value of the sampled value is less than a preset threshold, the second base voltage is the first determining voltage or the second determining voltage, otherwise the first basic voltage is the first A judgment voltage or a second judgment voltage.
7. The multi-speed multi-power motor control method according to claim 6, wherein the maximum value of the acquired sampling value comprises:

   The first base voltage determines the magnitude of each of the first base voltages from a negative positive change, and sets a larger first base voltage in each comparison to a maximum value of the sampled values until the first base voltage becomes negative.
8. The multi-speed multi-power motor control method according to claim 5, wherein the first determination voltage and the second determination voltage are subjected to low-pass filtering and/or zero-bias processing.
9. The multi-speed multi-power motor control method according to claim 4, wherein the line voltage of the second winding is shaped into a square wave, and the square wave frequency is calculated to obtain the rotation frequency of the motor at this time.
10. The multi-speed multi-power motor control method according to claim 1, wherein after the first contactor is disconnected, the timing module is turned on, if the preset time of the timing module is up and the first contactor is not completely Disconnected to issue a fault alarm;

    After the second contactor is disconnected, the timing module is turned on, and if the preset time of the timing module is up and the second contactor is not completely disconnected, a fault alarm is issued.
11. A multi-speed multi-power motor control system, the multi-speed multi-power motor comprising at least a first winding and a second winding, wherein the control system comprises:

    The first contactor has one end connected to the other end of the inverter output end connected to the first winding;

    a second contactor, one end connected to the other end of the inverter output end connected to the second winding;

    a third contactor, one end connected to the three-phase voltage input end and the other end connected to the second winding;

    The frequency converter is configured to draw the first contactor at a predetermined speed, so that the frequency converter is electrically connected to the first winding through the first contactor; driving the first winding and detecting the first winding speed, when the first winding speed reaches a predetermined speed Stop the inverter output, and then disconnect the first contactor; when it is detected that the first contactor is completely disconnected, the second contactor is attracted to make the inverter pass through the second contactor and the second winding; After detecting that the second contactor is fully engaged, driving the second winding and tracking the phase current and the phase voltage of the second winding, and obtaining the motor rotation speed and phase corresponding to the second winding according to the phase current and the phase voltage of the second winding; According to the motor speed and phase of the second winding, the frequency converter smoothly controls the second winding; detects the working frequency of the second winding, and when the second winding reaches the power frequency, phase locks the input voltage and the output voltage of the frequency converter, When the phase is locked, the inverter stops outputting, and then the second contactor is disconnected; when the second contactor is completely disconnected, the third contactor is sucked, and the second winding is smoothly switched to the industrial frequency .
12. The multi-speed multi-power motor control system according to claim 11, wherein the frequency converter is further configured to acquire three-phase input voltages Ur, Us, and Ut of the inverter; and input three-phase input voltages Ur, Us by coordinate changes. And Ut projection to the two-phase stationary coordinate system to obtain the two-phase voltage Ud, Uq; obtaining the angle θ1 of the composite voltage vector with respect to the coordinate system according to the two-phase voltage Uq, Ud; obtaining the three-phase output voltage Ur', Us' of the inverter And Ut'; projecting the three-phase output voltages Ur', Us' and Ut' to the two-phase stationary coordinate system by coordinate changes to obtain the two-phase voltages Ud', Uq'; obtaining the synthesized voltage according to the two-phase voltages Uq', Ud' The angle θ2 of the vector with respect to the coordinate system; phase locking according to the difference between the angle θ1 and the angle θ2, and the phase lock is considered if the difference between the angle θ1 and the angle θ2 is less than the preset difference.
13. The multi-speed multi-power motor control system according to claim 12, wherein the frequency converter comprises a phase lock module, and the phase lock module is configured to acquire an input voltage angle θ1 and an output voltage angle θ2, and control The output PWM wave of the inverter makes the output voltage angle θ2 approach the input voltage angle θ1.
14. The multi-speed multi-power motor control system according to claim 11, wherein the frequency converter further comprises a speed tracking module, wherein the speed tracking module is configured to track a phase current and a phase voltage of the second winding, the frequency conversion The speed tracking module is simultaneously activated when the second winding is driven.
15. The multi-speed multi-power motor control system according to claim 14, wherein the rotation speed tracking module comprises a first rotation speed tracking unit and a second rotation speed tracking unit, the first input end of the first rotation speed tracking unit and The second input end is respectively connected to the first phase voltage and the second phase voltage of the three-phase voltage, the output end of the first rotational speed tracking unit is connected to the digital signal processor, and the third input end of the second rotational speed tracking unit And the fourth input terminal is respectively connected to the second phase voltage and the third phase voltage of the three-phase voltage, and the output end of the second rotational speed tracking unit is connected to the digital signal processor.
16. The multi-speed multi-power motor control system according to claim 15, wherein the first rotational speed tracking unit comprises a first operational amplifier and a second operational amplifier;

    The inverting input end of the first operational amplifier is connected to the three-phase voltage first phase voltage through a resistor R1, and the non-inverting input end of the first operational amplifier is connected to the three-phase voltage second phase voltage through the resistor R2, the first operation The non-inverting input terminal is also grounded through a resistor R5, and the output end of the first operational amplifier is connected to the first operational amplifier inverting input terminal through a resistor R4, and the output end of the first operational amplifier is connected to one end of the resistor R11, and the resistor R11 The other end is connected to the power supply terminal through a resistor R12, and the other end of the resistor R11 is also connected to the digital signal processor;

    The inverting input end of the second operational amplifier is connected to the inverting input end of the first operational amplifier, the non-inverting input end of the second operational amplifier is connected to the non-inverting input end of the first operational amplifier, and the in-phase input of the second operational amplifier The input terminal is also grounded through a resistor R7, and the output terminal of the second operational amplifier is connected to the inverting input terminal of the second operational amplifier through a resistor R6. The output end of the second operational amplifier is connected to one end of the resistor R13, and the other end of the resistor R13 is passed. The resistor R14 is connected to the power supply end, and the other end of the resistor R13 is also connected to the digital signal processor;

    The resistance of the resistor R6 is greater than the resistance of the resistor R4.
17. The multi-speed multi-power motor control system according to claim 16, wherein the resistance of the resistor R6 is ten times the resistance of the resistor R4.
18. The multi-speed multi-power motor control system according to claim 16, wherein the other end of the resistor R11 is connected to the two clamp diodes and connected to the digital signal processor; one of the two clamp diodes is positive The grounding negative pole is connected to the other end of the resistor R11, and the other diode negative pole is connected to the power supply terminal positive pole connected to the other end of the resistor R11;

    The other end of the resistor R13 is connected to the two clamp diodes and connected to the digital signal processor; one of the two clamp diodes is connected to the anode and the negative pole is connected to the other end of the resistor R13, and the other diode is connected to the power supply terminal and the positive pole is connected to the resistor R13. another side.
19. The multi-speed multi-power motor control system according to claim 11, wherein the frequency converter further comprises:

    a first timer for opening after opening the first contactor;

    a second timer for opening after opening the second contactor;

    The frequency converter is also used to issue a fault alarm when the first timer preset time is up and the first contactor is not completely disconnected; it is also used when the second timer preset time is up and the second contactor is not completely disconnected. Call the police.
20. The multi-speed multi-power motor control system according to claim 11, wherein the frequency converter further comprises a first relay for controlling the first contactor to open and close, and a second contactor for controlling the opening and closing of the contactor. The second relay and the third relay that controls the third contactor to open and close.