CN1586672A - Power supersonic transducer exciting circuit - Google Patents

Abstract

A power ultrasonic transducer excitation circuit used in the technical field of biomedical engineering, the output ends of the first signal generating circuit and the second signal generating circuit are respectively connected to the input ends of the gate, and the control end of the gate receives Frequency selection signal, its output terminal is connected to the first input terminal of the signal modulation circuit, its third input terminal accepts the signal from the protection circuit, its output terminal is connected to the input terminal of the driving circuit, and the driving circuit’s The output end is connected to the signal input end of the series resonant power amplifier circuit, the feed input end of the series resonant power amplifier circuit is connected to the voltage output end of the multi-stage DC power supply, and the protection signal is output to the protection circuit, and its signal output end is directly Connect with a power ultrasonic transducer to excite it to emit ultrasonic waves. The invention has simple circuit, convenient debugging, controllable amplitude and duty cycle of output signal, high transmission efficiency and safe circuit operation.

Description

Power Ultrasonic Transducer Excitation Circuit

technical field

The invention relates to an excitation circuit used in medical equipment in the technical field of biomedical engineering, in particular to an excitation circuit for a power ultrasonic transducer of a malignant tumor ultrasonic thermotherapy system.

Background technique

Ultrasonic hyperthermia can treat both superficial tumors and deep tumors. It is safe and controllable, has good curative effect, and has no side effects. It has obvious complementary and sensitizing effects with radiotherapy and chemotherapy. Hyperthermia combined with radiotherapy or chemotherapy can achieve comprehensive treatment. The curative effect will be significantly improved; in addition, ultrasonic hyperthermia has no ionization, non-ionizing radiation and electromagnetic radiation, neither will it cause any damage to medical personnel, nor will it pollute the environment. Therefore, ultrasonic hyperthermia is a new and powerful anti-cancer means. In recent years, breakthroughs have been made in high-intensity focused ultrasound (HIFU) as a representative of high-dose, ie, damaging dose treatment methods, and the ultrasonic treatment equipment has also been greatly developed. Numerous ultrasonic therapy equipment cannot be separated from the power ultrasonic transducer excitation circuit, it must be able to provide appropriate voltage and current according to the treatment needs, that is, appropriate power, and most importantly, it must be controllable, that is, it must be able to follow the treatment The progress adjusts the voltage, current and duty cycle of its output accordingly.

After searching the documents of the prior art, it is found that the Chinese patent authorization announcement number is CN1111074C, and the patent name is: high-power ultrasonic transducer array driving circuit. Although it is innovative, it has overcome some shortcomings of other similar circuits. But its "power drive unit is a push-pull Class C circuit composed of identical two-arm circuits", using a transformer output. Cause its complex circuit, the required feed power supply voltage is high, the efficiency is low and so on.

Contents of the invention

The purpose of the present invention is to overcome the deficiencies of the prior art, and provide a power ultrasonic transducer excitation circuit, which can be used in a malignant tumor ultrasonic hyperthermia system. The amplitude and duty cycle can be controlled, the work efficiency and transmission efficiency are very high, the circuit operation is safe, the control is flexible and convenient, and the price is high.

The present invention is realized through the following technical proposals. The present invention consists of a first signal generating circuit, a second signal generating circuit, a gate, a signal modulation circuit, a driving circuit, a series resonant power amplifier circuit, a multi-stage DC power supply and a protection circuit. It is composed of a unit circuit, the output ends of the first signal generating circuit and the second signal generating circuit are respectively connected to the input end of the gate, and the control end of the gate receives the frequency selection signal, which comes from the ultrasonic hyperthermia system for malignant tumors. Intelligent monitoring subsystem, the intelligent monitoring subsystem is another subsystem of the ultrasonic hyperthermia system for malignant tumors. The command center for the normal and reasonable operation and intelligent control of each part of the hyperthermia system, the selection of the operating frequency of the excitation circuit of the power ultrasonic transducer; the step-by-step adjustment of the feeding power supply voltage, fine control of the ultrasonic power output according to the PWM signal, etc. etc. are all monitored by it, its output terminal is connected to the first input terminal of the signal modulation circuit, the second input terminal of the signal modulation circuit accepts the pulse width modulation PWM signal from the intelligent monitoring subsystem, and its third The input end accepts the signal from the protection circuit, its output end is connected to the input end of the drive circuit, the output end of the drive circuit is connected to the signal input end of the series resonant power amplifier circuit, and the feed input end of the series resonant power amplifier circuit It is connected to the voltage output terminal of the multi-level DC power supply, and it also receives the frequency selection signal from the intelligent monitoring subsystem, and outputs a protection signal to the protection circuit. Its signal output terminal is directly connected to the power ultrasonic transducer to excite it Ultrasonic waves are emitted, and the three voltage control terminals of the multi-level DC power supply receive parallel control signals from the intelligent monitoring subsystem.

The series resonant power amplifying circuit adopts a tuned amplifying circuit program, uses a VMOS field effect transistor as a power amplifying device, and works in a critical class-C state.

In the series resonant power amplifying circuit, the gate of the VMOS field effect transistor MOSFET-IRF460 is driven by a signal from the drive circuit, the matching resistor R1 is connected between the gate and the source, the source is grounded, and the drain passes through L1, The Γ-type filter circuit composed of C1 and C2 is connected to the voltage output terminal of the multi-stage DC power supply, and the capacitor C3 for eliminating clutter is connected in parallel between the drain and the source, and the drain is also connected to the coupling capacitor C4, and the other of C4 One end is connected to the resonant inductor L2 or L3 through the contact J1A of the relay J1, the other end of L2 is connected to the resonant capacitor C5, the other end of C5 is grounded, the other end of L3 is connected to the resonant capacitor C6, and the other end of C6 is grounded. The power ultrasonic transducer is connected to the resonant capacitor C5 or C6 through the contact J1B of the relay J1. L2, C5 and the power ultrasonic transducer form a series resonant network with a resonant frequency of F1. L3, C6 and the power ultrasonic transducer A series resonant network with resonant frequency F2 is formed. The coupling capacitor C4 and the resonant capacitors C5 and C6 are composed of multiple capacitors connected in parallel. The resonant inductors L2 and L3 are composed of multiple inductors connected in parallel. One end of the induction coil L4 and L5 is grounded, and the other One end is respectively connected to the charging capacitor C7 through the detection diode D1 or D2, one end of the charging capacitor C7 is grounded, and the other end is connected to the protection circuit.

The present invention abandons the push-pull power amplifying circuit of the prior art, not only omits the heavy and complicated power output transformer in its structure and uses half of the power amplifying devices, but also the circuit becomes very simple; its feed The power supply (multi-level DC power supply) becomes light and compact due to the greatly reduced voltage; its signal modulation circuit and drive circuit also become very simple because they only need to output a fixed-amplitude signal. The invention adds a protection circuit which is not available in the prior art, and the circuit is very simple, but the effect is remarkable.

Therefore, the excitation circuit of the power ultrasonic transducer of the present invention can: (1) the good frequency selection characteristics of the series resonant power amplifier circuit can convert the square wave excitation signal into a sine wave output signal of the same frequency, and its resonance characteristics can make the output The amplitude of the sine wave signal is much higher than its drain feed voltage, unlike the traditional power amplifier circuit, the output signal amplitude is always lower than the drain feed voltage, unless it uses a step-up transformer output. (2) The output power of the series resonant power amplifier circuit The voltage amplitude of the excitation signal of the ultrasonic transducer directly depends on the output voltage of the multi-stage DC power supply, which also determines the ultrasonic power output by the ultrasonic transducer. With the help of the signal modulation circuit, the duty ratio of the excitation signal of the power ultrasonic transducer output by the series resonant power amplifier circuit can be changed, so that the output ultrasonic power can be precisely controlled. The former is determined by the voltage selection, the latter is determined by the PWM signal, both of which come from the intelligent monitoring subsystem. (3) The series resonant network in the series resonant power amplifier circuit can also match its output impedance with the input impedance of the power ultrasonic transducer, so as to obtain the highest transmission efficiency. It is especially important that when the two are seriously mismatched It can also send a mismatch signal, and automatically shut down the operation of the circuit through the protection circuit and signal modulation circuit to ensure safety.

The excitation circuit of the power ultrasonic transducer designed by the present invention is novel in thinking, simple in circuit, convenient in debugging, the amplitude of the output excitation voltage can be several times that of the feed voltage, the amplitude and duty cycle of the output signal can be controlled, and the waveform distortion is small. Not only the working efficiency of the circuit itself is high, but also the transmission efficiency with the ultrasonic transducer is also high, the circuit is safe in operation, flexible and convenient in control, and has broad application prospects and market potential.

Description of drawings

Fig. 1 is a system composition diagram of the present invention.

FIG. 2 is an electrical schematic diagram of the series resonant power amplifier circuit of the present invention.

Detailed ways

Embodiments of the present invention are described in further detail below in conjunction with the accompanying drawings:

As shown in Figure 1, the present invention is made up of each unit circuit of first signal generation circuit, second signal generation circuit, gate, signal modulation circuit, drive circuit, series resonant power amplifier circuit, multistage DC power supply and protection circuit. The output terminals of the first signal generating circuit and the second signal generating circuit are respectively connected to the input terminals of the pass gate. Its output is connected to the first input of the signal modulation circuit. The second input terminal of the signal modulation circuit accepts the pulse width modulation PWM signal from the intelligent monitoring subsystem, the third input terminal accepts the signal from the protection circuit, and its output terminal is connected to the input terminal of the driving circuit. The output end of the drive circuit is connected to the signal input end of the series resonant power amplifier circuit. The feed input terminal of the series resonant power amplifier circuit is connected to the voltage output terminal of the multi-stage DC power supply. It also receives the frequency selection signal from the intelligent monitoring subsystem and outputs a mismatch signal to the protection circuit. Its signal output terminal directly Connect with a power ultrasonic transducer to excite it to emit ultrasonic waves. The three voltage control terminals of the multi-level DC power supply receive parallel control signals from the intelligent monitoring subsystem.

The first signal generating circuit and the second signal generating circuit respectively generate continuous square wave signals with frequencies F1 and F2. In the embodiment, F1=1MHz and F2=3.3MHz. The gate adopts multi-stage AND gate circuit, and outputs a continuous square wave signal with frequency F1 or F2 under the control of the frequency selection signal from the intelligent monitoring subsystem. The signal modulation circuit is essentially a three-AND gate, and the three input signals are: a continuous square wave signal with a frequency of F1 or F2; a PWM signal from an intelligent monitoring subsystem and a level control signal from a protection circuit. Under normal circumstances, its output is a series of square waves modulated by PWM signals. When the output impedance of the series resonant power amplifier circuit is seriously mismatched with the input impedance of the power ultrasonic transducer, the protection circuit outputs a low-level control signal, which will The output of the signal modulation circuit is locked at a high level, the operation of the circuit is automatically closed and a mismatch alarm signal is issued. The driving circuit adopts P-channel and N-channel field effect transistors. In this embodiment, the former is IRF640 and the latter is a complementary amplifier circuit composed of IRF9540 to ensure sufficient driving current to drive the series resonance power amplifying circuit.

As shown in Figure 2, the series resonant power amplifier circuit uses a tuned amplifier circuit program, uses a VMOS field effect transistor as a power amplifier device, works in a critical class C state, and uses LC series resonance as the output, and the load, that is, the power ultrasonic transducer is connected in parallel On the resonant capacitor, the drain is fed by a multistage DC supply. The specific circuit is: the gate of the VMOS field effect transistor MOSFET-IRF460 is driven by the signal from the drive circuit, the matching resistor R1 is connected between the gate and the source in parallel, the source is grounded, and the drain is connected by L1, C1, The Γ-type filter circuit composed of C2 is connected to the voltage output terminal of the multi-stage DC power supply, and the capacitor C3 for eliminating clutter is connected in parallel between the drain and the source, and the drain is also connected to the coupling capacitor C4. The other end of C4 is connected to the resonant inductor L2 or L3 through the contact J1A of the relay J1, the other end of L2 is connected to the resonant capacitor C5, the other end of C5 is grounded, the other end of L3 is connected to the resonant capacitor C6, and the other end of C6 One end is grounded. The load, that is, the power ultrasonic transducer is connected to the resonant capacitor C5 or C6 through the contact J1B of the relay J1. L2, C5 and the power ultrasonic transducer form a series resonant network with a resonant frequency of F1, and L3, C6 and the power ultrasonic transducer form a series resonant network with a resonant frequency of F2. The coupling capacitor C4 and the resonant capacitors C5 and C6 can be composed of multiple capacitors connected in parallel. In the embodiment, C4 is composed of 4 capacitors with the same capacitance in parallel, C5 is composed of 5 capacitors with the same capacitance in parallel, and C6 is composed of 4 capacitors. Capacitors with the same capacitance are connected in parallel. The resonant inductors L2 and L3 can also be composed of multiple inductors connected in parallel. In an embodiment, both L2 and L3 are composed of two inductors with different inductances connected in parallel, one of which is a variable inductor with adjustable inductance. One end of the induction coil L4, L5 is grounded, and their other ends are respectively connected to the charging capacitor C7 via the detection diode D1 or D2. One end of the charging capacitor C7 is grounded, and the other end is connected to the protection circuit.

The invention utilizes the good frequency selection characteristics of the series resonant power amplifier circuit to convert the square wave excitation signal into a sine wave output signal of the same frequency, and its resonance characteristics can make the amplitude of the output sine wave signal much higher than its drain feed voltage At the same time, the series resonant network composed of resonant capacitor, resonant inductance and power ultrasonic transducer can also match the output impedance of the series resonant power amplifier circuit with the input impedance of the ultrasonic transducer, thereby obtaining the highest transmission efficiency, especially The important thing is that when there is a serious mismatch between the two, the induced voltage generated on the induction coil is enough to activate the protection circuit, automatically shut down the operation of the circuit, and send a mismatch alarm signal to ensure safety. On the other hand, because the VMOS field effect transistor MOSFET-IRF460 works in the critical C-class state, the power loss of the tube itself is almost zero, so the work efficiency is very high. The output amplitude of the series resonant power amplifier circuit directly depends on its drain feed voltage, that is, the output voltage of the multi-level DC power supply, which also determines the ultrasonic power output by the ultrasonic transducer. At the same time, because the series resonant power amplifier circuit works in the critical class C state, the duty cycle of its output signal can be easily changed by means of the signal modulation circuit, so that the ultrasonic power output by the power ultrasonic transducer can be accurately controlled. The former is determined by the voltage selection, the latter is determined by the PWM signal, both of which come from the intelligent monitoring subsystem.

The multi-stage DC power supply is a switching power supply capable of outputting different voltages. In the embodiment, its output voltage ranges from 24 to 45V in 8 steps; it is controlled by an intelligent monitoring subsystem.

The protection circuit is an RS flip-flop whose output state depends on the mismatch signal from the series resonant power amplifier circuit.

Claims (7)

1. power ultrasonic transducer exciting circuit; it is characterized in that: by first signal generating circuit; secondary signal generation circuit; storbing gate; signal modulation circuit; drive circuit; the series resonance power amplification circuit; each element circuit of multistage dc source and holding circuit constitutes; the outfan of first signal generating circuit and secondary signal generation circuit is linked into the input of storbing gate respectively; the control end of storbing gate is accepted frequency and is selected signal; this signal is from the Intellectualized monitoring subsystem of malignant tumor ultrasound thermal therapy system; its outfan is linked into first input of signal modulation circuit; second input of signal modulation circuit accepted the pulse width modulation (PWM) signal from the Intellectualized monitoring subsystem; its the 3rd input accepts self-protection circuit's signal; its outfan is linked into the input of drive circuit; the outfan of drive circuit is linked into the signal input part of series resonance power amplification circuit; the feed input of series resonance power amplification circuit is connected with the voltage output end of multistage dc source; it also accepts to select signal from the frequency of Intellectualized monitoring subsystem; to holding circuit output protection signal; its signal output part directly is connected with power ultrasonic transducer; encourage it to send ultrasound wave, three voltage controling ends of multistage dc source are accepted the parallel control signal from the Intellectualized monitoring subsystem.

2. power ultrasonic transducer exciting circuit as claimed in claim 1 is characterized in that, described series resonance power amplification circuit is used the tuning amplification circuit formula, uses VMOS field effect transistor rate of doing work amplifying device, is operated in critical C class state.

3. as claim 1 or 2 described power ultrasonic transducer exciting circuits; it is characterized in that; described series resonance power amplification circuit; the signal of the self-driven circuit of grid origin of VMOS field effect transistor MOSFET-IRF460 drives; build-out resistor R1 is attempted by between grid and the source electrode; source ground; drain electrode is passed through by L1; C1; the Γ type filter circuit that C2 forms and the voltage output end of multistage dc source join; the capacitor C 3 of eliminating clutter is attempted by between drain electrode and the source electrode; drain electrode also links to each other with coupling capacitor C 4; the other end of C4 links to each other with resonant inductance L2 or L3 through the contact J1A of relay J 1; the other end of L2 and resonant capacitance C5 join; the other end ground connection of C5; the other end of L3 and resonant capacitance C6 join; the other end ground connection of C6; power ultrasonic transducer is attempted by on resonant capacitance C5 or the C6 through the contact J1B of relay J 1; L2; it is the series resonance network of F1 that C5 and power ultrasonic transducer constitute resonant frequency; L3; it is the series resonance network of F2 that C6 and power ultrasonic transducer constitute resonant frequency; coupling capacitor C 4 and resonance capacitor C 5; C6 is composed in parallel by a plurality of electric capacity; resonant inductance L2; L3 is composed in parallel by a plurality of inductance; induction coil L4; the end ground connection of L5; their other end is connected with charging capacitor C7 through detector diode D1 or D2 respectively; the end ground connection of charging capacitor C7, the other end is received holding circuit.

4. power ultrasonic transducer exciting circuit as claimed in claim 1 is characterized in that, described first signal generating circuit, secondary signal generation circuit produce the continuous square-wave signal that frequency is F1, F2 respectively.

5. power ultrasonic transducer exciting circuit as claimed in claim 1 is characterized in that described storbing gate adopts multistage AND circuit, and output frequency is the continuous square-wave signal of F1 or F2 under the signal controlling selecting from the frequency of Intellectualized monitoring subsystem.

6. power ultrasonic transducer exciting circuit as claimed in claim 1 is characterized in that, described signal modulation circuit is one three and door, and three input signals are respectively: frequency is the continuous square-wave signal of F1 or F2; From the pwm signal of Intellectualized monitoring subsystem and the level controling signal that comes the self-protection circuit.

7. power ultrasonic transducer exciting circuit as claimed in claim 1; it is characterized in that; described signal modulation circuit; its output under normal circumstances is a string by the synthetic square wave of pwm signal; when the serious mismatch of input impedance of the output impedance of series resonance power amplification circuit and power ultrasonic transducer; holding circuit output low level control signal is locked in high level with the output of signal modulation circuit, and the operation of auto shut off circuit is also sent the mismatch alarm signal.

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