CN214755608U

CN214755608U - Battery cell charging and discharging device

Info

Publication number: CN214755608U
Application number: CN202120690153.9U
Authority: CN
Inventors: 戴志成; 邓志江; 林氦
Original assignee: Shaoxing Technology Venture Capital Co ltd; Shaoxing Microelectronics Research Center Of Zhejiang University; Zhejiang University ZJU
Current assignee: Shaoxing Technology Venture Capital Co ltd; Shaoxing Microelectronics Research Center Of Zhejiang University; Zhejiang University ZJU
Priority date: 2021-04-06
Filing date: 2021-04-06
Publication date: 2021-11-16
Anticipated expiration: 2031-04-06

Abstract

The invention relates to a battery unit charging and discharging device, and relates to the field of power supply. An alternating current is converted into a stable direct current on a direct current bus through an AC/DC isolation conversion module, and the direct current bus is connected to a non-isolated bidirectional DC/DC converter and a power multi-level adjustable discharge device. , The non-isolated bidirectional DC/DC converter can convert the DC bus voltage into a wide range of controllable DC voltage to charge battery cells of different voltage levels, and can also be used for battery cell discharge, by converting excess battery energy to the DC bus, and then Dissipated by the power multi-level adjustable discharge device at different power levels, the non-isolated bidirectional DC/DC converter can increase or decrease the voltage of its second terminal to the target battery voltage, and make the voltage control accuracy of the second terminal within At the same time, it is compatible with different types of battery cell voltages, adapting to a very wide voltage range, instead of using different types of charging and discharging devices separately, so that the design is simple and the compatibility is good.

Description

Battery unit charging and discharging device

Technical Field

The invention relates to the field of power supplies, in particular to a battery unit charging and discharging device.

Background

The large-scale series-parallel battery module is an indispensable system component in a plurality of current electrical fields, such as an energy supply unit of an electric automobile or an energy storage unit of a photovoltaic inversion system. Generally, a battery module (module) is formed by connecting a plurality of battery cells (cells) in series and parallel, and then an energy storage or power supply battery pack (package) is formed by connecting a plurality of battery modules in series and parallel to serve as an energy storage unit or an energy supply unit.

When one of the battery modules in the battery pack is damaged or has a larger voltage difference than other battery modules connected into the battery pack, a new battery module needs to be replaced into the battery pack. The new battery module needs to be consistent with the voltage of the battery module which is not replaced, or the voltage difference is controlled within a small range, such as within dozens of millivolts, so that the risk in the installation process can be reduced and the service life of the battery can be ensured. However, since the voltage ranges of the battery modules of different types are different greatly, in order to satisfy the larger voltage range, different charging and discharging devices need to be selected according to different battery modules during charging and discharging, so that the design difficulty is increased, and the compatibility of the charging and discharging devices is reduced.

Therefore, there is a need for a battery module charging/discharging device with an extremely wide voltage range, which increases the compatibility of the battery module charging/discharging device and reduces the design difficulty of the battery module charging/discharging device.

Disclosure of Invention

The invention provides a battery unit charging and discharging device, comprising: the AC/DC isolation conversion module has an input end for receiving alternating current and an output end connected with a direct current bus and is used for converting the alternating current into direct current bus voltage and providing electrical isolation between the output end and the input end; a non-isolated bidirectional DC/DC converter having a first end connected to the DC bus and a second end connected to a battery unit, for converting the DC bus voltage at the first end to a target battery voltage at the second end to charge the battery unit, or converting the battery voltage of the battery unit to the DC bus voltage at the first end; the power multistage adjustable discharge device is connected between the direct current bus and the ground end and has different discharge power grades; and a control module connected to the power multistage adjustable discharge device, the AC/DC isolation conversion module and the non-isolation bidirectional DC/DC converter for outputting control signals to the switch in the power multistage adjustable discharge device, the switch in the AC/DC isolation conversion module and the switch in the non-isolation bidirectional DC/DC converter to control the battery unit charge/discharge device to operate in a charge mode or a discharge mode, in the charge mode, the switch in the AC/DC isolation conversion module and the switch in the non-isolation bidirectional DC/DC converter operate to convert the AC power to a target battery voltage to charge the battery unit, in the discharge mode, the switch in the non-isolation bidirectional DC/DC converter and the switch in the power multistage adjustable discharge device operate to discharge the battery unit, and in the discharge mode, the control module controls the switch in the power multistage adjustable discharging device to work so that the power multistage adjustable discharging device can work at different discharging power levels according to the discharging power required by the battery unit.

Further, the power multistage adjustable discharge device includes: at least one of the switch discharging branch circuit comprises a resistor R and a switch S which are connected in series to form a switch discharging branch circuit, and a non-isolated unidirectional DC/DC converter and a converter discharging branch circuit formed by connecting the resistor in series, wherein the first end of the switch discharging branch circuit and the first end of the converter discharging branch circuit are both connected with the direct current bus, and the second end of the switch discharging branch circuit and the second end of the converter discharging branch circuit are both grounded.

Furthermore, the control module controls the output voltage of the non-isolated unidirectional DC/DC converter in the discharging branch of the converter and the number of the switched-on switch discharging branches according to the discharging power required by the battery unit, so that the power multistage adjustable discharging device works at a desired discharging power level.

Furthermore, the on or off of the switch discharging branch is realized by controlling the on or off of a switch in the switch discharging branch through the control module.

Furthermore, the resistance values in the switch discharging branch and the converter discharging branch are the same.

Furthermore, the control module comprises a control chip, a sampling circuit, a driving control circuit, a logic control circuit and a communication circuit, wherein the sampling circuit samples signals of the working states of the AC/DC isolation conversion module, the non-isolation bidirectional DC/DC converter and the power multistage adjustable discharge device and outputs a working state signal S1 of the AC/DC isolation conversion module, a working state signal S2 of the non-isolation bidirectional DC/DC converter and a working state signal S3 of the power multistage adjustable discharge device to the control chip, the communication circuit is connected with external communication equipment, the control chip obtains a target voltage value of the battery unit from the external communication equipment through the communication circuit, and the control chip controls the device to be charged and discharged according to the working state signal S1 of the AC/DC isolation conversion module, the working state signal S2 of the non-isolation bidirectional DC/DC converter, the working state signal S3 of the power multistage adjustable discharge device and the target voltage value of the battery unit The method is used for operating in a charging mode or a discharging mode, and controlling the discharging power level of the power multistage adjustable discharging device in the discharging mode.

Furthermore, when the terminal voltage of the battery unit is lower than the target voltage value, the control chip outputs a logic control signal to the logic control circuit according to the working state signal S1 of the AC/DC isolation conversion module, the working state signal S2 of the non-isolation bidirectional DC/DC converter, the working state signal S3 of the power multistage adjustable discharge device and the target voltage value of the battery unit, and the logic control circuit controls the AC/DC isolation conversion module and the non-isolation bidirectional DC/DC converter to work so that the battery unit charge-discharge device works in a charging mode, and outputs a switch control signal C1 of the AC/DC isolation conversion module and a switch control signal C2 of the non-isolation bidirectional DC/DC converter to the driving control circuit so that the switches in the AC/DC isolation conversion module and the non-isolation bidirectional DC/DC converter are driven to work so that the battery unit works in a boost charging mode or a buck charging mode, and the AC/DC isolation conversion module converts the AC into stable DC bus voltage, and the non-isolation bidirectional DC/DC converter converts the DC bus voltage into a target voltage value of the battery unit to charge the battery unit.

Furthermore, when the voltage at the end of the battery unit is higher than the target voltage value, the control chip outputs a logic control signal to the logic control circuit according to the working state signal S1 of the AC/DC isolation conversion module, the working state signal S2 of the non-isolated bidirectional DC/DC converter, the working state signal S3 of the power multistage adjustable discharge device, and the target voltage value of the battery unit, and the logic control circuit controls the non-isolated bidirectional DC/DC converter and the power multistage adjustable discharge device to operate so that the battery unit charge/discharge device operates in the discharge mode, and outputs the switch control signal C2 of the non-isolated bidirectional DC/DC converter and the switch control signal C3 of the power multistage adjustable discharge device to the driving control circuit, so as to drive and control the non-isolated bidirectional DC/DC converter to operate in the boost discharge mode or the buck discharge mode, when the voltage of the direct current bus is smaller than the voltage of the battery unit, the non-isolated bidirectional DC/DC converter works in a boosting discharge mode, and when the voltage of the direct current bus is larger than the voltage of the battery unit, the non-isolated bidirectional DC/DC converter works in a reducing discharge mode, the control module obtains an expected discharge power grade according to a target voltage value of the battery unit and outputs a control signal of the power multistage adjustable discharge device, and the drive control circuit drives and controls the number of the conducted switch discharge branches and controls the output voltage of the non-isolated unidirectional DC/DC converter in the converter discharge branches.

Furthermore, the control module further comprises a protection circuit for protecting the battery unit charging and discharging device according to the working state signal S1 of the AC/DC isolation conversion module, the working state signal S2 of the non-isolation bidirectional DC/DC converter and the working state signal S3 of the power multistage adjustable discharging device.

Further, the rated value of the direct current bus voltage is 48V.

Drawings

Fig. 1 is a schematic diagram of a battery cell charging and discharging device according to an embodiment of the invention.

Fig. 2 is a schematic circuit diagram of a battery unit charging/discharging device according to an embodiment of the invention when the battery unit charging/discharging device operates in a charging mode.

Fig. 3 is a schematic circuit diagram of a battery cell charging/discharging device according to an embodiment of the invention when the battery cell charging/discharging device operates in a discharging mode.

Fig. 4 is a schematic diagram of a power multi-stage adjustable discharging device according to an embodiment of the invention.

Fig. 5 is a circuit block diagram of a control module according to an embodiment of the invention.

Detailed Description

The technical solutions in the present invention will be described clearly and completely with reference to the accompanying drawings, and it should be understood that the described embodiments are some, but not all embodiments of the present invention. All other embodiments, which can be obtained by a person skilled in the art without any inventive step based on the embodiments of the present invention, are within the scope of the present invention.

It is to be understood that the present invention may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. In the drawings, the size and relative sizes of layers and regions may be exaggerated for clarity, and the same reference numerals denote the same elements throughout. It will be understood that when an element or layer is referred to as being "on" …, "adjacent to …," "connected to" or "coupled to" other elements or layers, it can be directly on, adjacent to, connected to or coupled to the other elements or layers or intervening elements or layers may be present. In contrast, when an element is referred to as being "directly on …," "directly adjacent to …," "directly connected to" or "directly coupled to" other elements or layers, there are no intervening elements or layers present. It will be understood that, although the terms first, second, third, etc. may be used to describe various elements, components, regions, layers and/or sections, these elements, components, regions, layers and/or sections should not be limited by these terms. These terms are only used to distinguish one element, component, region, layer or section from another element, component, region, layer or section. Thus, a first element, component, region, layer or section discussed below could be termed a second element, component, region, layer or section without departing from the teachings of the present invention.

Spatial relationship terms such as "under …", "under …", "below", "under …", "above …", "above", and the like, may be used herein for ease of description to describe the relationship of one element or feature to another element or feature as illustrated in the figures. It will be understood that the spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, then elements or features described as "below" or "beneath" other elements or features would then be oriented "above" the other elements or features. Thus, the exemplary terms "below …" and "below …" can encompass both an orientation of up and down. The device may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatial descriptors used herein interpreted accordingly.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and/or "comprising," when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. As used herein, the term "and/or" includes any and all combinations of the associated listed items.

In an embodiment of the present invention, a battery cell charging and discharging device is provided, please refer to fig. 1, which shows a schematic diagram of a battery cell charging and discharging device according to an embodiment of the present invention, including: an AC/DC isolation and transformation module 210, an input end of which receives AC power, and an output end of which is connected to a DC bus (DCBUS), and is configured to transform the AC power into a DC bus voltage Vbus and provide electrical isolation between the output end and the input end; a non-isolated bidirectional DC/DC converter 250 having a first end connected to the DC bus (DCBUS) and a second end connected to the battery unit 230, for converting the DC bus voltage Vbus at the first end into a target battery voltage at the second end to charge the battery unit 230, or converting the battery voltage of the battery unit 230 into the DC bus voltage Vbus at the first end; a power multi-stage adjustable discharge device 220 connected between the dc bus (DCBUS) and the ground GND and having different discharge power levels; and a control module 260, the control module 260 being connected to the power multistage adjustable discharging device 220, the AC/DC isolation conversion module 210 and the non-isolation bidirectional DC/DC converter 250, and being configured to output control signals to the switch in the power multistage adjustable discharging device 220, the switch in the AC/DC isolation conversion module 210 and the switch in the non-isolation bidirectional DC/DC converter 250, so as to control the battery unit charging and discharging device to operate in a charging mode or a discharging mode, in the charging mode, the switch in the AC/DC isolation conversion module 210 and the switch in the non-isolation bidirectional DC/DC converter 250 operate to convert the alternating current into a target battery voltage to charge the battery unit 230, in the discharging mode, the switch in the non-isolation bidirectional DC/DC converter 250 and the switch in the power multistage adjustable discharging device 220 operate to discharge the battery unit 230, and in the discharging mode, the control module 260 controls the switches in the power multi-stage adjustable discharging device 220 to operate at different discharging power levels according to the discharging power required by the battery unit 230.

Thus, the AC power is converted into a stable DC power on the DC bus by the AC/DC isolation conversion module 210, the DC bus is connected to the non-isolated bidirectional DC/DC converter 250 and the power multistage adjustable discharge device 220, the non-isolated bidirectional DC/DC converter 250 can convert the DC bus voltage into a wide range of controllable DC voltages to charge the battery cells of different voltage classes, and can also be used for discharging the battery cells, the voltage at the second end of the non-isolated bidirectional DC/DC converter 250 can be increased or decreased to the target battery voltage by converting the excess battery energy into the DC bus and then discharged and consumed by the power multistage adjustable discharge device 220, and the voltage control accuracy at the second end is in the order of tens of millivolts, while the non-isolated bidirectional DC/DC converter 250 is compatible with the battery cell voltages of different models, and is adaptable to an extremely wide voltage range without separately using the charging and discharging devices of different models, the design is simple and the compatibility is good.

As described above, since the AC/DC isolation conversion module 210 performs the function of electrical isolation between the input terminal and the output terminal, and performs the preliminary voltage regulation function to provide a stable DC bus voltage, the subsequent non-isolated bidirectional DC/DC converter 250 can achieve a wider voltage regulation range.

In one embodiment, the battery unit 230 may be a battery module or a battery cell (cell).

The AC/DC isolation conversion module 210 is an isolation type energy conversion module, and converts an alternating current into a stable direct current. In one embodiment, when the battery cell needs to be charged, the AC/DC isolation transformation module 210 transforms the 220V or 110V AC voltage into a stable DC voltage with a rated voltage of 48V under the control of the control module 260. Because the isolation of transformer wherein, guaranteed the security of 48V low pressure side, rated voltage 48V's direct current output voltage belongs to the standard output voltage in communication power field simultaneously, for the general module of industry, with low costs, stability is high, and reduces the design degree of difficulty.

Please refer to the schematic circuit diagram of the battery unit charging/discharging device shown in fig. 2 when it works in the charging mode. In the charging mode, the switches in the AC/DC isolation conversion module 210 and the switches in the non-isolation bidirectional DC/DC converter 250 operate to convert the alternating current into the target battery voltage to charge the battery unit 230, and more specifically, the AC/DC isolation conversion module 210 converts the alternating current voltage of 220V or 110V into the stable direct current bus voltage under the control of the control module 260, and the non-isolation bidirectional DC/DC converter 250 converts the direct current bus voltage into the target battery voltage under the control of the control module 260 to charge the battery unit. Further, the non-isolated bidirectional DC/DC converter 250 converts the DC bus voltage into the target battery voltage to charge the battery cell under the control of the control module 260 in two cases: when the cell voltage is lower than the DC bus voltage, the non-isolated bi-directional DC/DC converter 250 operates in a charging buck mode to reduce the DC bus voltage to the target cell voltage for charging the cell; when the cell voltage is higher than the DC bus voltage, the non-isolated bi-directional DC/DC converter 250 operates in a boost mode of charging to boost the DC bus voltage to the target cell voltage for charging the cell.

Please refer to a circuit diagram of the battery cell charging/discharging device shown in fig. 3 when the battery cell charging/discharging device operates in a discharging mode. In the discharging mode, the switch in the non-isolated bidirectional DC/DC converter 250 and the switch in the power multistage adjustable discharging device 220 operate to discharge the battery unit 230, and more specifically, the non-isolated bidirectional DC/DC converter 250 converts the battery voltage into the DC bus voltage under the control of the control module 260 and inputs the DC bus voltage into the power multistage adjustable discharging device 220 for discharging. Further, the non-isolated bidirectional DC/DC converter 250 converts the battery voltage into the DC bus voltage under the control of the control module 260 into two cases: when the cell voltage is lower than the DC bus voltage, the non-isolated bi-directional DC/DC converter 250 operates in a discharging boost mode to boost the cell voltage to the DC bus voltage; when the cell voltage is higher than the DC bus voltage, the non-isolated bi-directional DC/DC converter 250 operates in a discharging step-down mode to reduce the cell voltage to the DC bus voltage.

Please refer to fig. 4, which is a schematic diagram of a power multi-stage adjustable discharging device. The power multistage adjustable discharging device 220 includes: at least one switch discharge branch 222 comprising a resistor R (e.g., resistor R1 … … Rn) and a switch S (e.g., switch S1 … … Sn) connected in series, anNon-isolated unidirectional DC/DC converter 2211 and resistor R_DCThe converter discharging branch 221 is formed by connecting the converter discharging branch 221 in series, the first end of the switch discharging branch 222 and the first end of the converter discharging branch 221 are both connected to the Direct Current Bus (DCBUS), and the second end of the switch discharging branch 222 and the second end of the converter discharging branch 221 are both grounded, so that a parallel discharging structure is formed. The more specific details of the control module 260 controlling the switch in the power multistage adjustable discharging device 220 to operate at different discharging power levels according to the discharging power required by the battery unit 230 are: the control module 260 controls the output voltage of the non-isolated unidirectional DC/DC converter 2211 in the converter discharging branch 221 and the number of the switched discharging branches 222 to be turned on according to the discharging power required by the battery unit 230, so that the power multi-stage adjustable discharging device 220 operates at a desired discharging power level. In one embodiment, the switching on or off of the switch discharging branch 222 is implemented by the control module 260 controlling the switch therein to be turned on or off.

As described above, the main function of the multi-stage adjustable discharging device 220 is to dissipate energy of the DC bus voltage output by the non-isolated bidirectional DC/DC converter 250, which may be referred to as a load device. Specifically, taking 4 load modules included in the converter as an example, as shown in fig. 4, 3 switch discharging branches 222 and 1 converter discharging branch 221 constitute 4 load modules. In one embodiment, the resistance value in each discharging branch is the same, so that the discharging power of the 3 switching discharging branches 222 in fig. 4 is consistent since the voltages input to the discharging branches are consistent, and the switching duty cycle in the non-isolated unidirectional DC/DC converter 2211 in the converter discharging branch 221 is controlled to change the discharging power of the converter discharging branch 221. In one embodiment, the resistance values in the discharge branches may also be different, so that different discharge branches have different discharge powers. Taking the same resistance value in each discharging branch as an example, 4 discharging branches shown in fig. 4 are combined into 4 stages during discharging. Specifically, the following settings can be set: when the required discharging power is smaller than 1/4 of the rated discharging power, the control module 260 controls to turn on only one switch in the switch discharging branch 222, the control module 260 controls the non-isolated unidirectional DC/DC converter 2211 to output different voltages to the resistive load in the converter discharging branch 221, and since the resistive load impedance in the non-isolated unidirectional DC/DC converter is not changed, an adjustable output current is obtained; when the required discharge power is greater than the rated discharge power of 1/4 and less than the rated discharge power of 1/2, the control module 260 controls to turn on the switches in the two switch discharge branches 222, the two switch discharge branches 222 that are turned on at this time bear the rated discharge power of 1/4, and the other discharge power is regulated by the non-isolated unidirectional DC/DC converter 2211; when the required discharge power is greater than the rated discharge power of 1/2 and less than the rated discharge power of 3/4, the control module 260 controls to turn on the switches in the three switch discharge branches 222, the three switch discharge branches 222 that are turned on at this time bear the rated discharge power of 1/4, and the other discharge power is regulated by the non-isolated unidirectional DC/DC converter 2211; when the required discharging power is greater than the rated discharging power of 3/4 and less than the rated discharging power, the control module 260 controls to turn on the switches in the three switch discharging branches 222, at this time, the three turned-on switch discharging branches 222 respectively bear the rated discharging power of 1/4, and the other discharging power is adjusted by the non-isolated unidirectional DC/DC converter 2211; when the required discharge power is greater than the rated power by a certain range, the non-isolated bidirectional DC/DC converter 250 adjusts (usually, trims) the DC bus voltage to be slightly greater than the rated DC bus voltage (e.g., 48V) to increase the discharge power borne in each discharge branch, thereby obtaining the discharge power greater than the rated power. In fact, to obtain rated discharge power due to the influence of switching loss in the discharge branch, the 48V bus voltage must be properly increased, that is, the dc bus voltage is greater than 48V (e.g., slightly greater than 48V).

In an embodiment, the specific structure of the non-isolated unidirectional DC/DC converter 2211 is not limited in the present invention, as long as the conversion from DC power to DC power can be realized.

Please refer to fig. 5, which is a block diagram of a control module. The control module 260 includes a control chip 261, a sampling circuit 262, a driving control circuit 263, a logic control circuit 264 and a communication circuit 265, the sampling circuit 262 samples the working status signals of the AC/DC isolated conversion module 210, the non-isolated bidirectional DC/DC converter 250 and the power multistage adjustable discharge device 220 to output the working status signal S1 of the AC/DC isolated conversion module 210, the working status signal S2 of the non-isolated bidirectional DC/DC converter 250 and the working status signal S3 of the power multistage adjustable discharge device 220 to the control chip 261, the communication circuit 265 is connected to an external communication device 267, the control chip 261 obtains the target voltage value of the battery unit 230 from the external communication device 267 through the communication circuit 265, and the control chip 261 obtains the target voltage value of the battery unit 230 according to the working status signal S1 of the AC/DC isolated conversion module 210 and the working status signal S2 of the non-isolated bidirectional DC/DC converter 250, The operating state signal S3 of the power multi-stage adjustable discharging device 220 and the target voltage value of the battery unit 230 control the charging and discharging device to operate in the charging mode or the discharging mode, and control the discharging power level of the power multi-stage adjustable discharging device 220 in the discharging mode.

Specifically, when the terminal voltage of the battery cell 230 is lower than the target voltage value, the battery cell 230 needs to be charged. Then the alternating current is connected, the control module 260 obtains power supply, the external communication device 267 and the communication circuit 265 establish communication, so that the control chip 261 obtains the target voltage value of the battery unit 230, the control chip 261 outputs a logic control signal to the logic control circuit 264 according to the working state signal S1 of the AC/DC isolation transformation module 210, the working state signal S2 of the non-isolation bidirectional DC/DC converter 250, the working state signal S3 of the power multi-stage adjustable discharge device 220 and the target voltage value of the battery unit 230, and the logic control circuit 264 controls the AC/DC isolation transformation module 210 and the non-isolation bidirectional DC/DC converter 250 to work, so that the battery unit charge and discharge device works in a charge mode, and outputs a switch control signal C1 of the AC/DC isolation transformation module 210 and a switch control signal C2 of the non-isolation bidirectional DC/DC converter 250 to the driving control circuit 263, the switches in the AC/DC isolation conversion module 210 and the non-isolation bidirectional DC/DC converter 250 are driven and controlled to operate in a boost charging mode or a buck charging mode, the AC/DC isolation conversion module 210 converts the alternating current into a stable direct current bus voltage Vbus, the non-isolation bidirectional DC/DC converter 250 converts the direct current bus voltage Vbus into a target voltage value of the battery unit 230 to charge the battery unit, in the process, the switch of the power multistage adjustable discharge device 220 does not operate, the energy is transmitted from the alternating current to the battery unit, and the electric energy of the power grid is converted into the chemical energy of the battery for storage. More specifically, in the charging mode, the non-isolated bidirectional DC/DC converter 250 operates in a step-up mode or a step-down mode, and when the DC bus voltage Vbus is less than the target voltage value of the battery cell 230, the non-isolated bidirectional DC/DC converter 250 operates in the step-up mode, and when the DC bus voltage Vbus is greater than the target voltage value of the battery cell 230, the non-isolated bidirectional DC/DC converter 250 operates in the step-down mode.

Specifically, when the terminal voltage of the battery cell 230 is higher than the target voltage value, it is necessary to discharge the battery cell 230. Then the alternating current is connected, the control module 260 obtains power supply, the external communication device 267 and the communication circuit 265 establish communication, so that the control chip 261 obtains the target voltage value of the battery unit 230, the control chip 261 outputs a logic control signal to the logic control circuit 264 according to the working state signal S1 of the AC/DC isolation conversion module 210, the working state signal S2 of the non-isolated bidirectional DC/DC converter 250, the working state signal S3 of the power multistage adjustable discharge device 220 and the target voltage value of the battery unit 230, and the logic control circuit 264 controls the non-isolated bidirectional DC/DC converter 250 and the power multistage adjustable discharge device 220 to work, so that the battery unit charge and discharge device works in a discharge mode, and outputs a switch control signal C2 of the non-isolated bidirectional DC/DC converter 250 and a switch control signal C3 of the power multistage adjustable discharge device 220 to the driving control circuit 263, the drive control circuit 263 drives and controls the number of the conducting switch discharge branches 222 and the output voltage of the non-isolated unidirectional DC/DC converter 2211 in the converter discharge branch 221, wherein the non-isolated bidirectional DC/DC converter 250 operates in a boost discharge mode or a buck discharge mode, when the direct current bus voltage Vbus is smaller than the voltage of the battery unit 230, the non-isolated bidirectional DC/DC converter 250 operates in the boost discharge mode, and when the direct current bus voltage Vbus is larger than the voltage of the battery unit 230, the non-isolated bidirectional DC/DC converter 250 operates in the buck discharge mode, and the control module obtains a desired discharge power level according to a target voltage value of the battery unit 230 and outputs a control signal of the power multi-level adjustable discharge device 220. In the process, the AC/DC isolation conversion module 210 only accesses the alternating current to supply power to the control chip, and does not perform energy conversion, and the energy is transferred from the battery unit to the power multistage adjustable discharge device 220 for discharging.

In an embodiment, the operation state signal S1 of the AC/DC isolation conversion module 210 includes an input side voltage, a current signal, and an output side voltage, and a current signal of the AC/DC isolation conversion module 210, and the operation state signal S2 of the same non-isolated bidirectional DC/DC converter 250 includes an input side voltage, a current signal, and an output side voltage, and a current signal of the non-isolated bidirectional DC/DC converter 250, and the operation state signal S3 of the power multi-stage adjustable discharging device 220 includes a control signal of a switch in the power multi-stage adjustable discharging device 220, and an output voltage of the non-isolated unidirectional DC/DC converter 2211.

In an embodiment, the control signal C1 of the AC/DC isolation conversion module 210 includes a duty cycle of a switch in the AC/DC isolation conversion module 210, the control signal C2 of the non-isolated bidirectional DC/DC converter 250 includes a duty cycle of a switch in the non-isolated bidirectional DC/DC converter 250, and the control signal C3 of the power multi-stage adjustable discharging device 220 includes a duty cycle of a switch in the non-isolated unidirectional DC/DC converter 2211 in the power multi-stage adjustable discharging device 220 and an on or off signal of a switch in the switch discharging branch 222.

In one embodiment, the AC power is converted to a supply voltage for the control module 260 by an auxiliary power supply 268.

In an embodiment, the control module 260 further includes a protection circuit 266 for protecting the battery cell charging/discharging device, such as overvoltage protection, overcurrent protection, etc., according to the operating state signal S1 of the AC/DC isolation transformation module 210, the operating state signal S2 of the non-isolated bidirectional DC/DC converter 250, and the operating state signal S3 of the power multi-stage adjustable discharging device 220.

The battery unit charging and discharging device has a large output voltage adjustable range, can be compatible with battery modules with different voltages from several volts to hundreds of volts, and has an obvious charging voltage range advantage compared with a charging device of a single-model battery module. In addition, since the non-isolated bidirectional DC/DC converter 250 is a non-isolated system, the battery voltage sampling signal at the output side thereof has no isolation delay, and thus has a faster control response speed. The output voltage of the non-isolated bi-directional DC/DC converter 250 can be controlled within the range of the required accuracy of the set voltage by using a high-accuracy operational amplifier.

Finally, it should be noted that: the above embodiments are only used to illustrate the technical solution of the present invention, and not to limit the same; while the invention has been described in detail and with reference to the foregoing embodiments, it will be understood by those skilled in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some or all of the technical features may be equivalently replaced; and the modifications or the substitutions do not make the essence of the corresponding technical solutions depart from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A battery cell charging/discharging device, comprising:

the AC/DC isolation conversion module has an input end for receiving alternating current and an output end connected with a direct current bus and is used for converting the alternating current into direct current bus voltage and providing electrical isolation between the output end and the input end;

a non-isolated bidirectional DC/DC converter having a first end connected to the DC bus and a second end connected to a battery unit, for converting the DC bus voltage at the first end to a target battery voltage at the second end to charge the battery unit, or converting the battery voltage of the battery unit to the DC bus voltage at the first end;

the power multistage adjustable discharge device is connected between the direct current bus and the ground end and has different discharge power grades; and

a control module, connected to the power multistage adjustable discharge device, the AC/DC isolation conversion module and the non-isolation bidirectional DC/DC converter, for outputting control signals to the switch in the power multistage adjustable discharge device, the switch in the AC/DC isolation conversion module and the switch in the non-isolation bidirectional DC/DC converter, so as to control the battery unit charge/discharge device to operate in a charge mode or a discharge mode, in the charge mode, the switch in the AC/DC isolation conversion module and the switch in the non-isolation bidirectional DC/DC converter operate to convert the AC power into a target battery voltage to charge the battery unit, in the discharge mode, the switch in the non-isolation bidirectional DC/DC converter and the switch in the power multistage adjustable discharge device operate to discharge the battery unit, and in the discharge mode, the control module controls the switch in the power multistage adjustable discharge device to operate according to the requirements of the battery unit Operating at different discharge power levels.

2. The battery cell charge and discharge device according to claim 1, wherein the power multistage adjustable discharge device comprises: at least one of the switch discharging branch circuit comprises a resistor R and a switch S which are connected in series to form a switch discharging branch circuit, and a non-isolated unidirectional DC/DC converter and a converter discharging branch circuit formed by connecting the resistor in series, wherein the first end of the switch discharging branch circuit and the first end of the converter discharging branch circuit are both connected with the direct current bus, and the second end of the switch discharging branch circuit and the second end of the converter discharging branch circuit are both grounded.

3. The battery unit charging and discharging device according to claim 2, wherein the control module controls the output voltage of the non-isolated unidirectional DC/DC converter in the converter discharging branch and the number of switched-on switch discharging branches according to the discharging power required by the battery unit so that the power multi-stage adjustable discharging device operates at a desired discharging power level.

4. The battery unit charging and discharging device according to claim 3, wherein the on or off of the switch discharging branch is realized by the control module controlling the on or off of the switch in the switch discharging branch.

5. The battery cell charging and discharging device according to claim 2, wherein resistance values in the switch discharging branch and the converter discharging branch are the same.

6. The battery charging and discharging device according to claim 2, wherein the control module comprises a control chip, a sampling circuit, a driving control circuit, a logic control circuit and a communication circuit, the sampling circuit samples the operating status signals of the AC/DC isolation conversion module, the non-isolation bidirectional DC/DC converter and the power multistage adjustable discharging device to output an operating status signal S1 of the AC/DC isolation conversion module, an operating status signal S2 of the non-isolation bidirectional DC/DC converter and an operating status signal S3 of the power multistage adjustable discharging device to the control chip, the communication circuit is connected to an external communication device, the control chip obtains the target voltage value of the battery unit from the external communication device through the communication circuit, and the control chip obtains the target voltage value of the battery unit according to the operating status signals S1 of the AC/DC isolation conversion module and the operating status signal S2 of the non-isolation bidirectional DC/DC converter, The working state signal S3 of the power multistage adjustable discharging device and the target voltage value of the battery unit control the charging and discharging device to work in a charging mode or a discharging mode, and control the discharging power level of the power multistage adjustable discharging device in the discharging mode.

7. The device as claimed in claim 6, wherein when the terminal voltage of the battery cell is lower than the target voltage value, the control chip outputs a logic control signal to the logic control circuit according to the operation status signal S1 of the AC/DC isolation transformation module, the operation status signal S2 of the non-isolated bidirectional DC/DC converter, the operation status signal S3 of the power multistage adjustable discharge device, and the target voltage value of the battery cell, and the logic control circuit controls the operation of the AC/DC isolation transformation module and the non-isolated bidirectional DC/DC converter to operate the battery cell charge/discharge device in the charge mode, and outputs the switch control signal C1 of the AC/DC isolation transformation module and the switch control signal C2 of the non-isolated bidirectional DC/DC converter to the driving control circuit to drive and control the switches in the AC/DC isolation transformation module and the non-isolated bidirectional DC/DC converter to operate in the charge mode And the non-isolated bidirectional DC/DC converter converts the direct-current bus voltage into a target voltage value of the battery unit so as to charge the battery unit.

8. The battery charging/discharging device of claim 6, wherein when the terminal voltage of the battery cell is higher than the target voltage, the control chip outputs a logic control signal to the logic control circuit according to the operation status signal S1 of the AC/DC isolation conversion module, the operation status signal S2 of the non-isolated bidirectional DC/DC converter, the operation status signal S3 of the multistage power adjustable discharging device, and the target voltage of the battery cell, and the logic control circuit controls the non-isolated bidirectional DC/DC converter and the multistage power adjustable discharging device to operate so that the battery charging/discharging device operates in the discharging mode, and outputs the switch control signal C2 of the non-isolated bidirectional DC/DC converter and the switch control signal C3 of the multistage power adjustable discharging device to the driving control circuit to drive and control the non-isolated bidirectional DC/DC converter to operate in the voltage boosting discharging mode or the voltage reducing discharging mode, when the voltage of the direct current bus is smaller than the voltage of the battery unit, the non-isolated bidirectional DC/DC converter works in a boosting discharge mode, and when the voltage of the direct current bus is larger than the voltage of the battery unit, the non-isolated bidirectional DC/DC converter works in a reducing discharge mode, the control module obtains an expected discharge power grade according to a target voltage value of the battery unit and outputs a control signal of the power multistage adjustable discharge device, and the drive control circuit drives and controls the number of the conducted switch discharge branches and controls the output voltage of the non-isolated unidirectional DC/DC converter in the converter discharge branches.

9. The battery cell charging and discharging device according to claim 6, wherein the control module further comprises a protection circuit for protecting the battery cell charging and discharging device according to the operation status signal S1 of the AC/DC isolation transformation module, the operation status signal S2 of the non-isolated bidirectional DC/DC converter, and the operation status signal S3 of the power multi-stage adjustable discharging device.

10. The battery cell charge and discharge device according to claim 1, wherein the rated value of the dc bus voltage is 48V.