Circulation current suppression circuit for parallel battery packs

Abstract

The present invention proposes a circulation suppression circuit for a parallel battery pack, which belongs to the field of battery protection technology. The circulation suppression module is designed so that the circulation suppression module simultaneously generates an enable signal, a first determination signal, and a second determination signal to drive a controller to adjust the battery terminal voltage of the parallel battery pack, thereby suppressing the circulation between the parallel battery packs. The circulation suppression module of the present invention generates both an enable signal and a first determination signal and a second determination signal based on the terminal voltage of two batteries, and simultaneously realizes the dual functions of controller enablement and charge and discharge determination of two batteries, simplifies the circuit structure, and reduces the circuit volume and cost.

Description

Technical Field

[0001] The invention belongs to the technical field of battery protection, and in particular relates to a circulating current suppression circuit for a parallel storage battery group. Background Art

[0002] Batteries have become a commonly used power supply system at present. However, the capacity of a single battery is limited and cannot meet the power demand of the load. The use of parallel battery groups can provide a larger power supply current for the load. However, even if two batteries of exactly the same model and specification are connected in parallel, there will be differences in the internal resistance, electromotive force, capacity, and electrochemical reaction degree between the batteries during use. In particular, when the electromotive force of the two parallel battery groups is very different, it will cause a circulation current between the parallel battery groups, accelerate battery aging, waste electricity, and even cause the battery to heat up and ignite. Therefore, it is necessary to suppress the circulation of the parallel battery group.

[0003] In the prior art, some charge and discharge circuits are set to control the charge and discharge of different batteries to ensure the balance of the battery terminal voltage to reduce the circulating current. Some use energy dissipation circuits to amplify batteries with more remaining capacity or higher terminal voltage to reduce the circulating current. Some use self-equalizing circuits to keep the voltage between batteries relatively balanced to reduce the circulating current. However, no matter which method is used to reduce the circulating current, it is necessary to detect the voltage or capacity of the battery, and then perform the corresponding charge and discharge or equalizing control, so it is necessary to be equipped with a detection or control chip or a corresponding module; the control unit for realizing charge and discharge control or equalizing may also need to be equipped with an enable circuit to start the control unit through an enable signal to achieve energy saving. The above-mentioned detection, control and enabling steps require many chips or modules. The current single chip or module cannot realize multiple functions such as detection, control and enabling. It is necessary to configure a separate detection module, enable module and control module for the circulating current suppression circuit, resulting in a large circuit volume, high cost and complex structure. Summary of the invention

[0004] The object of the present invention is to provide a circulating current suppression circuit for parallel battery groups, which is designed so that the circulating current suppression module generates an enable signal, a first determination signal and a second determination signal at the same time, so as to drive a controller to adjust the battery terminal voltage of the parallel battery group, thereby suppressing the circulating current between the parallel battery groups. The circulating current suppression module of the present invention generates both an enable signal and a first determination signal and a second determination signal based on the terminal voltage of the two batteries, and simultaneously realizes the dual functions of controller enablement and charge and discharge determination of the two batteries, simplifies the circuit structure, and reduces the circuit volume and cost.

[0005] In order to achieve the above-mentioned purpose, the present invention adopts the following technical scheme: a circulating current suppression circuit of a parallel battery pack includes two batteries connected in parallel, the negative poles of each battery are connected to each other as a negative power supply terminal, the positive pole of each battery is connected to a DC / DC unit, and the output ends of the two DC / DC units are connected, and also includes a controller and a circulating current suppression module, the circulating current suppression module is used to generate an enable signal EN, a first determination signal OUT1 and a second determination signal OUT2 according to the terminal voltages VB1 and VB2 of the two batteries connected in parallel, the controller receives the enable signal EN, the first determination signal OUT1 and the second determination signal OUT2 generated by the circulating current suppression module, and generates control signals of the two DC / DC units according to the enable signal EN, the first determination signal OUT1 and the second determination signal OUT2, and the circulating current suppression of the parallel battery pack is realized by controlling the two DC / DC units.

[0006] Both DC / DC units are buck-boost circuits, which include switches S1, S2, S3, S4 and an inductor L1. A common point of one end of the switch S1 and one end of S2 connected in series is connected to one end of the inductor L1, and the other end of the inductor L1 is connected to a common point of one end of the switch S3 and one end of S4 connected in series. The other end of the switch S1 is the input end of the buck-boost circuit, the other ends of the switches S2 and S3 are grounded, and the other end of the switch S4 is the input end of the buck-boost circuit.

[0007] The output end of one DC / DC unit is connected to the anode of the first diode, the output end of the other DC / DC unit is connected to the anode of the second diode, the cathode of the first diode is connected to the cathode of the second diode and the anode of the third diode, and the cathode of the third diode is the positive power supply terminal.

[0008] In the circulating current suppression module, the power supply VDD1 is connected to one end of the resistor R13, the other end of the resistor R13 is connected to one end of the switch tube Q11, the other end of the switch tube Q11 is connected to one end of the resistor R14, the other end of the resistor R14 is grounded, and one end of the resistor R14 generates an enable signal EN; the positive electrode VB1 of a battery is connected to one end of the resistor R11, the other end of the resistor R11 is connected to one end of the resistor R12, the other end of the resistor R12 is connected to the positive electrode VB2 of another battery, the other end of the resistor R11 is also connected to the negative input end of the operational amplifier OPAMP1, and the positive input end of the operational amplifier OPAMP1 is connected to the positive input end of the operational amplifier OPAMP1. The other end of the resistor R13 is connected, and the output end of the operational amplifier OPAMP1 is connected to the control end of the switch tube Q11 through the resistor R15; the positive input end of the amplifier AMP1 is connected to one end of the resistor R11 and one end of the switch tube Q12, the negative input end of the amplifier AMP1 is connected to the other end of the resistor R11, the output end of the amplifier AMP1 is connected to the control end of the switch tube Q12, the other end of the switch tube Q12 is connected to one end of the switch tube M3 and the control end of the switch tube M3, the other end of the switch tube M3 is connected to one end of the switch tube M4, the other end of the switch tube M4 is grounded, the power supply VDD2 is connected to one end of the switch tube M1, and the switch The other end of the switch tube M1 is connected to one end of the switch tube M2, the other end of the switch tube M2 is connected to one end of the resistor RO1, the other end of the resistor RO1 is grounded, the control end of the switch tube M1 is connected to the control end of the switch tube M3, the control end of the switch tube M2 is connected to one end of the switch tube M2 and the control end of the switch tube M4, and one end of the resistor RO1 generates a first determination signal OUT1; the positive input end of the amplifier AMP2 is connected to the other end of the resistor R12 and one end of the switch tube Q13, the negative input end of the amplifier AMP2 is connected to one end of the resistor R12, and the output end of the amplifier AMP2 is connected to the control end of the switch tube Q13. The other end of the switch tube Q13 is connected to one end of the switch tube M7 and the control end of the switch tube M7, the other end of the switch tube M7 is connected to one end of the switch tube M8, the other end of the switch tube M8 is grounded, the power supply VDD3 is connected to one end of the switch tube M5, the other end of the switch tube M5 is connected to one end of the switch tube M6, the other end of the switch tube M6 is connected to one end of the resistor RO2, the other end of the resistor RO2 is grounded, the control end of the switch tube M5 is connected to the control end of the switch tube M7, the control end of the switch tube M6 is connected to one end of the switch tube M6 and the control end of the switch tube M8, and one end of the resistor RO2 generates a second determination signal OUT2.

[0009] The controller includes a reference voltage generating circuit RG and a lookup table LUT, wherein the reference voltage generating circuit RG is used to generate a reference voltage, and the lookup table LUT is used to generate control signals of two DC / DC units according to the states of the first determination signal OUT1 and the second determination signal OUT2, and the controller is used to control the voltage increase or decrease of the positive electrode voltages of the two batteries according to the reference voltage and the control signals of the two DC / DC units after receiving the enable signal EN. The reference voltage is the average value of the positive electrode voltages of the two batteries.

[0010] The beneficial technical effect of the present invention compared with the prior art is: a circulating current suppression module is designed to simultaneously generate an enable signal, a first determination signal and a second determination signal to drive a controller to adjust the battery terminal voltage of the parallel battery group, thereby suppressing the circulating current between the parallel battery groups. The above-mentioned circulating current suppression module realizes the dual functions of controller enabling and charge and discharge determination of two batteries, simplifies the circuit structure, and reduces the circuit volume and cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] In order to more clearly illustrate the implementation methods of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for the implementation methods or the description of the prior art. Obviously, the drawings in the following description are only exemplary, and for ordinary technicians in this field, other implementation drawings can be derived from the provided drawings without creative work.

[0012] Figure 1 A circuit diagram of a circulating current suppression circuit for a parallel battery pack of the present invention;

[0013] Figure 2 is a structural diagram of a DC / DC unit of the present invention;

[0014] Figure 3 It is a structural diagram of the circulation suppression module of the present invention. DETAILED DESCRIPTION

[0015] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0016] The following first describes the concepts involved in the present application in conjunction with the accompanying drawings. It should be noted that the following description of each concept is only to make the content of the present application easier to understand, and does not limit the scope of protection of the present application; at the same time, the embodiments and features in the embodiments of the present application can be combined with each other in the absence of conflict. The present application will be described in detail with reference to the accompanying drawings and in conjunction with the embodiments.

[0017] In conjunction with the instruction manual Figure 1 The circulating current suppression circuit of the parallel battery pack disclosed in the present invention comprises two batteries connected in parallel, the negative poles of each battery are connected to each other as the negative power supply terminal, the positive pole of each battery is connected to a DC / DC unit, the output terminals of the two DC / DC units are connected, and the circulating current suppression circuit also comprises a controller and a circulating current suppression module, the circulating current suppression module is used to generate an enable signal EN, a first determination signal OUT1 and a second determination signal OUT2 according to the terminal voltages VB1 and VB2 of the two batteries connected in parallel, the controller receives the enable signal EN, the first determination signal OUT1 and the second determination signal OUT2 generated by the circulating current suppression module, and generates control signals of the two DC / DC units according to the enable signal EN, the first determination signal OUT1 and the second determination signal OUT2, and realizes the circulating current suppression of the parallel battery pack by controlling the two DC / DC units.

[0018] Continue to refer to the instruction manual Figure 1 The circulating current suppression circuit of the parallel battery pack of the present invention may also include a first diode D1, a second diode D2 and a third diode D3, the output end of the first DC / DC unit is connected to the anode of the first diode D1, the output end of the second DC / DC unit is connected to the anode of the second diode D2, the cathode of the first diode D1 is connected to the cathode of the second diode D2 and the anode of the third diode D3, and the cathode of the third diode D3 is the positive power supply terminal. The first diode D1, the second diode D2 and the third diode D3 can provide a protective effect against reverse current.

[0019] The first DC / DC unit and the second DC / DC unit of the present invention adopt the method described in the appendix of the specification. Figure 2The buck-boost circuit shown includes switches S1, S2, S3, S4 and an inductor L1. The common point of one end of the switch S1 and one end of S2 connected in series is connected to one end of the inductor L1, and the other end of the inductor L1 is connected to the common point of one end of the switch S3 and one end of S4 connected in series; the other end of the switch S1 is the input end of the buck-boost circuit, the other ends of the switches S2 and S3 are grounded, and the other end of the switch S4 is the output end of the DC / DC unit. When the input voltage needs to be boosted, the switches S1 and S2 are controlled to be turned on, and the inductor L1, the switches S3 and S4 are used to boost the voltage; when the input voltage needs to be stepped down, the switches S3 and S4 are controlled to be turned on, and the inductor L1, the switches S1 and S2 are used to step down the voltage. The ratio of boost or step down can be controlled by controlling the duty cycle of the corresponding switches. Of course, a step-up circuit and a step-down circuit may be provided separately to regulate the battery terminal voltage.

[0020] In conjunction with the instruction manual Figure 3The specific structure of the circulating current suppression module of the present invention is as follows: the power supply VDD1 is connected to one end of the resistor R13, the other end of the resistor R13 is connected to one end of the switch tube Q11, the other end of the switch tube Q11 is connected to one end of the resistor R14, the other end of the resistor R14 is grounded, and one end of the resistor R14 generates an enable signal EN; the positive electrode VB1 of a battery is connected to one end of the resistor R11, the other end of the resistor R11 is connected to one end of the resistor R12, the other end of the resistor R12 is connected to the positive electrode VB2 of another battery, and the other end of the resistor R11 is also connected to the negative input end of the operational amplifier OPAMP1, and the operational amplifier OPAMP The positive input end of the amplifier AMP1 is connected to the other end of the resistor R13, and the output end of the operational amplifier OPAMP1 is connected to the control end of the switch tube Q11 through the resistor R15; the positive input end of the amplifier AMP1 is connected to one end of the resistor R11 and one end of the switch tube Q12, the negative input end of the amplifier AMP1 is connected to the other end of the resistor R11, the output end of the amplifier AMP1 is connected to the control end of the switch tube Q12, the other end of the switch tube Q12 is connected to one end of the switch tube M3 and the control end of the switch tube M3, the other end of the switch tube M3 is connected to one end of the switch tube M4, the other end of the switch tube M4 is grounded, and the power supply VDD2 is connected to the The first determination signal OUT1 is generated at one end of the switch tube M1, the other end of the switch tube M2 is connected to one end of the switch tube M2, the other end of the switch tube M2 is connected to one end of the resistor RO1, the other end of the resistor RO1 is grounded, the control end of the switch tube M1 is connected to the control end of the switch tube M3, the control end of the switch tube M2 is connected to one end of the switch tube M2 and the control end of the switch tube M4, and one end of the resistor RO1 generates a first determination signal OUT1; the positive input end of the amplifier AMP2 is connected to the other end of the resistor R12 and one end of the switch tube Q13, the negative input end of the amplifier AMP2 is connected to one end of the resistor R12, and the output end of the amplifier AMP2 is connected to the control end of the switch tube Q13 The other end of the switch tube Q13 is connected to one end of the switch tube M7 and the control end of the switch tube M7, the other end of the switch tube M7 is connected to one end of the switch tube M8, the other end of the switch tube M8 is grounded, the power supply VDD3 is connected to one end of the switch tube M5, the other end of the switch tube M5 is connected to one end of the switch tube M6, the other end of the switch tube M6 is connected to one end of the resistor RO2, the other end of the resistor RO2 is grounded, the control end of the switch tube M5 is connected to the control end of the switch tube M7, the control end of the switch tube M6 is connected to one end of the switch tube M6 and the control end of the switch tube M8, and one end of the resistor RO2 generates a second determination signal OUT2.

[0021] The following is a brief description of the working process of the circulating current suppression module of the present invention to generate the enable signal EN, the first determination signal OUT1 and the second determination signal OUT2: when the difference between the terminal voltages VB1 and VB2 of the two batteries is relatively large, the resistors R11 and R12 act as voltage-dividing resistors to generate a voltage at their common end which is input to the negative input end of the operational amplifier OPAMP1. By setting the resistors R11, R12, R13 and VDD1, the output end of the operational amplifier OPAMP1 can be flipped, and the switch tube Q11 is controlled to be disconnected, thereby reducing the current i11 on the path where the power supply VDD1, the resistor R13, the switch tube Q11 and the resistor R14 are located, and the voltage on the resistor R14 is flipped from a high level to a low level, thereby generating a low-level enable signal EN. Through the amplifiers AMP1 and AMP2, the current flow between the two batteries can be detected, thereby generating determination signals OUT1 and OUT2. Taking the battery terminal voltage VB1 as greater than VB2 as an example, the current flow between the two batteries is from VB1 to VB2, the amplifier AMP1 outputs a high level and the amplifier AMP2 outputs a low level, the switch tube Q12 is turned on and Q13 is turned off, and the current flowing through the switch tube Q12 generates a high level on the resistor RO1 through the current symmetry circuit, that is, OUT1 is high and OUT2 is low, that is, when the battery terminal voltage VB1 is greater than VB2, OUT1 is high and OUT2 is low, when the battery terminal voltage VB1 is less than VB2, OUT2 is high and OUT1 is low, thereby determining the high and low of the two battery terminal voltages through the level signals of the first determination signal OUT1 and the second determination signal OUT2, and then performing corresponding buck-boost control. The current symmetry circuit is set here to improve the stability of the current output, thereby ensuring the stability of the first determination signal OUT1 and the second determination signal OUT2.

[0022] The controller in the present invention includes a reference voltage generating circuit and a lookup table LUT, wherein the lookup table LUT is used to generate control signals CTR1 and CTR2 of two DC / DC units according to the states of a first determination signal OUT1 and a second determination signal OUT2, that is, when OUT1 is at a high level and OUT2 is at a low level, it is necessary to reduce the battery terminal voltage VB1 and raise the battery terminal voltage VB2, and the DC / DC unit corresponding to the battery with a control terminal voltage of VB1 is controlled by CTR1 and CTR2 to perform a step-down operation, and the DC / DC unit corresponding to the battery with a control terminal voltage of VB2 is controlled to perform a step-up operation; when OUT2 is at a high level and OUT1 is at a low level, it is necessary to reduce the battery terminal voltage VB2 and raise the battery terminal voltage VB1, and the DC / DC unit corresponding to the battery with a control terminal voltage of VB1 is controlled by CTR1 and CTR2 to perform a step-up operation, and the DC / DC unit corresponding to the battery with a control terminal voltage of VB2 is controlled to perform a step-down operation.

[0023] The reference voltage generating circuit is used to generate a reference voltage to provide a reference voltage for the two DC / DC units, and the reference voltage is the average of the positive voltages of the two batteries. It is understandable that the reference voltage can also be set to other voltages within the normal working voltage range of the battery.

[0024] The embodiments and / or implementation methods described above are only used to illustrate the preferred embodiments and / or implementation methods for realizing the technology of the present invention, and are not intended to limit the implementation methods of the technology of the present invention in any form. Any technical personnel in this field may make slight changes or modifications to other equivalent embodiments without departing from the scope of the technical means disclosed in the content of the present invention, but they should still be regarded as technologies or embodiments that are essentially the same as the present invention.

[0025] This article uses specific examples to illustrate the principles and implementation methods of this application. The description of the above embodiments is only used to help understand the method and its core ideas of this application. The above is only the preferred implementation method of this application. It should be pointed out that due to the limitations of textual expression and the objective existence of infinite specific structures, ordinary technicians in this technical field can make several improvements, modifications or changes without departing from the principles of this application, and can also combine the above technical features in an appropriate manner; these improvements, modifications, changes or combinations, or the direct application of the concept and technical solution of the invention to other occasions without improvement, should be regarded as the scope of protection of this application.

Claims

1. A circulating current suppression circuit of a parallel battery pack, comprising two batteries connected in parallel, wherein the negative poles of each battery are connected to each other as a negative power supply terminal, the positive pole of each battery is connected to a DC / DC unit, and the output terminals of the two DC / DC units are connected, characterized in that: It also includes a controller and a circulating current suppression module, wherein the circulating current suppression module is used to generate an enable signal EN, a first determination signal OUT1 and a second determination signal OUT2 according to the terminal voltages VB1 and VB2 of the two batteries connected in parallel, and the controller receives the enable signal EN, the first determination signal OUT1 and the second determination signal OUT2 generated by the circulating current suppression module, and generates control signals of two DC / DC units according to the enable signal EN, the first determination signal OUT1 and the second determination signal OUT2, so as to realize the circulating current suppression of the parallel battery group by controlling the two DC / DC units; In the circulating current suppression module, the power supply VDD1 is connected to one end of the resistor R13, the other end of the resistor R13 is connected to one end of the switch tube Q11, the other end of the switch tube Q11 is connected to one end of the resistor R14, the other end of the resistor R14 is grounded, and an enable signal EN is generated at one end of the resistor R14; A positive electrode VB1 of a battery is connected to one end of a resistor R11, the other end of the resistor R11 is connected to one end of a resistor R12, the other end of the resistor R12 is connected to a positive electrode VB2 of another battery, the other end of the resistor R11 is also connected to a negative input end of an operational amplifier OPAMP1, the positive input end of the operational amplifier OPAMP1 is connected to the other end of the resistor R13, and the output end of the operational amplifier OPAMP1 is connected to a control end of a switch tube Q11 through a resistor R15; The positive input end of the amplifier AMP1 is connected to one end of the resistor R11 and one end of the switch tube Q12, the negative input end of the amplifier AMP1 is connected to the other end of the resistor R11, the output end of the amplifier AMP1 is connected to the control end of the switch tube Q12, the other end of the switch tube Q12 is connected to one end of the switch tube M3 and the control end of the switch tube M3, the other end of the switch tube M3 is connected to one end of the switch tube M4, the other end of the switch tube M4 is grounded, the power supply VDD2 is connected to one end of the switch tube M1, the other end of the switch tube M1 is connected to one end of the switch tube M2, the other end of the switch tube M2 is connected to one end of the resistor RO1, the other end of the resistor RO1 is grounded, the control end of the switch tube M1 is connected to the control end of the switch tube M3, the control end of the switch tube M2 is connected to one end of the switch tube M2 and the control end of the switch tube M4, and one end of the resistor RO1 generates a first determination signal OUT1; The positive input end of the amplifier AMP2 is connected to the other end of the resistor R12 and one end of the switch tube Q13, the negative input end of the amplifier AMP2 is connected to one end of the resistor R12, the output end of the amplifier AMP2 is connected to the control end of the switch tube Q13, the other end of the switch tube Q13 is connected to one end of the switch tube M7 and the control end of the switch tube M7, the other end of the switch tube M7 is connected to one end of the switch tube M8, the other end of the switch tube M8 is grounded, the power supply VDD3 is connected to one end of the switch tube M5, the other end of the switch tube M5 is connected to one end of the switch tube M6, the other end of the switch tube M6 is connected to one end of the resistor RO2, the other end of the resistor RO2 is grounded, the control end of the switch tube M5 is connected to the control end of the switch tube M7, the control end of the switch tube M6 is connected to one end of the switch tube M6 and the control end of the switch tube M8, and one end of the resistor RO2 generates a second determination signal OUT2.

2. The circulating current suppression circuit of the parallel battery pack as claimed in claim 1, characterized in that: The two DC / DC units are both buck-boost circuits, which include switches S1, S2, S3, S4 and an inductor L1. A common point of one end of the switch S1 and one end of S2 connected in series is connected to one end of the inductor L1, and the other end of the inductor L1 is connected to a common point of one end of the switch S3 and one end of S4 connected in series. The other end of the switch S1 is the input end of the buck-boost circuit, the other ends of the switches S2 and S3 are grounded, and the other end of the switch S4 is the input end of the buck-boost circuit.

3. The circulating current suppression circuit of the parallel battery pack as claimed in claim 1, characterized in that: The output end of one DC / DC unit is connected to the anode of the first diode, the output end of the other DC / DC unit is connected to the anode of the second diode, the cathode of the first diode is connected to the cathode of the second diode and the anode of the third diode, and the cathode of the third diode serves as the positive power supply end.

4. The circulating current suppression circuit of the parallel battery pack as claimed in claim 1, characterized in that: The controller includes a reference voltage generating circuit RG and a lookup table LUT, wherein the reference voltage generating circuit RG is used to generate a reference voltage, and the lookup table LUT is used to generate control signals of two DC / DC units according to the states of a first determination signal OUT1 and a second determination signal OUT2. After receiving the enable signal EN, the controller is used to control the voltage increase or decrease of the positive electrode voltage of the two batteries according to the reference voltage and the control signals of the two DC / DC units.

5. The circulating current suppression circuit of the parallel battery pack as claimed in claim 4, characterized in that: The reference voltage is an average value of the positive electrode voltages of the two batteries.

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