Driving circuit and BMS

Abstract

The utility model discloses a drive circuit and a BMS. The drive circuit comprises a first switch tube, a second switch tube, a diode, a first resistor, a second resistor and a third resistor. Wherein the first end of the first switch tube is connected with the first end of the first resistor and then used for inputting bias voltage, the control end of the first switch tube and the second end of the first resistor are connected with the first end of the second resistor, and the second end of the first switch tube is connected with the anode of the diode. The cathode of the diode is connected in series with a third resistor and then is used for being connected to the grid electrodes of the two tubes of the certain pair of field effect tubes, the second end of the second resistor is connected with the first end of the second switch tube, and the second end of the second switch tube is used for being connected with the ground end. The control end of the second switch tube is used for being electrically connected to the controller. According to the utility model, the cost and loss of the driving circuit can be obviously saved.

Description

TECHNICAL FIELD

[0001] The utility model relates to battery management technical field, especially drive circuit and BMS. BACKGROUND

[0002] Battery management system (BMS) is currently applied very widely, especially in energy storage, formation, power battery and other application occasions have great demand, and currently BMS mainly includes three modules: equalization module, battery string, BMU, and the development path of equalization module has turned to isolated active equalization (high efficiency, high cost) from resistance passive equalization (low efficiency, low cost) and non-isolated active equalization (high efficiency, high cost) development.And isolated active equalization is preferred by major BMS manufacturers with the scheme of single equalization module plus matrix switch with optimal cost and high efficiency.But the power supply and driving mode of matrix switch have not had an optimal scheme, and the high cost, low reliability of driving circuit and the problem of causing poor battery string balancing degree have been difficult problems for major manufacturers to solve.

[0003] Typical as Figure 1 As shown in the figure, it is the typical application diagram of the special driving chip EMB1428 of TI's matrix switch, and the official website of the driving chip quotes US$9.591 yuan, which is high in price, and the fundamental reason for its high unit price is the isolation floating drive mode.

[0004] There are also many BMS systems in the industry that use non-isolated circuit power supply for matrix switch on the battery string side, as shown in Figure 2 In the scheme, boost power supply scheme is adopted on the battery side, and the standby power consumption of the supply loop and the isolation driving IC exists for a long time, so the current flowing through the single battery in the driving part of the battery string is uneven, as shown in the figure, the driving power supply current flowing through the single battery bat1 = Ic2+Ic3+Ic4+Ic5+Ic6, and the driving power supply current flowing through the single battery bat5 is only Ic6, and the problem of unequal current flowing through the battery string single cell will directly lead to the voltage imbalance of the single cell in the battery string, and further affect the charge and discharge time, capacity, life and reliability of the battery.The overall power supply cost is also high when the isolation circuit is powered by the battery string side.In short, the power supply of the matrix switch on the battery side is not an optimal scheme.

[0005] As analyzed above, the driving circuit of the BMS matrix switch in the industry currently has certain defects, and a scheme with simpler driving, higher reliability and lower cost is extremely needed. UTILITY MODEL CONTENTS

[0006] In view of this, the technical problem to be solved by the utility model is to provide a driving circuit and BMS, which aims to overcome at least one defect in the prior art.

[0007] As a first aspect of the present application, the technical solutions of the embodiments of the driving circuit are as follows:

[0008] A driving circuit applied to a BMS, the BMS comprising a matrix switch and a controller, the matrix switch comprising a plurality of pairs of field effect tubes; the connection relationship of each pair of field effect tubes is that the sources of the two tubes are connected together, the drain of one of the tubes is used to connect a battery end, the drain of the other tube is used to connect an input end of the BMS, and the gates of the two tubes are connected together; the controller controls a certain pair of field effect tubes to be turned on or turned off at the same time through the driving circuit; wherein the driving circuit comprises:

[0009] a first switch tube, a second switch tube, a diode, a first resistor, a second resistor and a third resistor; wherein the first end of the first switch tube and the first end of the first resistor are connected to input a bias voltage, the control end of the first switch tube, the second end of the first resistor and the first end of the second resistor are connected, the second end of the first switch tube is connected to the anode of the diode, the cathode of the diode is connected in series with the third resistor and used to connect to the gates of the two tubes of the certain pair of field effect tubes, the second end of the second resistor is connected to the first end of the second switch tube, the second end of the second switch tube is used to connect to a ground end, and the control end of the second switch tube is used to electrically connect to the controller.

[0010] Further, the driving circuit further comprises a fourth resistor, which is used to connect between the gate connection point and the source connection point of the two tubes of the certain pair of field effect tubes.

[0011] Preferably, the first switch tube is a PNP type triode or a P type field effect tube.

[0012] Preferably, the second switch tube is a field effect tube, a triode or an IGBT, which is used to control the turn-on and turn-off of the first switch tube.

[0013] Further, the bias voltage is greater than the input positive end voltage of the BMS; when the other drain of the certain pair of field effect tubes is connected to the input positive end of the BMS, the driving voltage provided by the driving circuit between the gate and the source of the certain pair of field effect tubes when the certain pair of field effect tubes is turned on is equal to a first voltage plus or minus a set deviation value; when the other drain of the certain pair of field effect tubes is connected to the input negative end of the BMS, the driving voltage provided by the driving circuit between the gate and the source of the certain pair of field effect tubes when the certain pair of field effect tubes is turned on is equal to a second voltage plus or minus a set deviation value.

[0014] Wherein: the first voltage=(bias voltage-BMS input positive terminal voltage) * fourth resistance value / (third resistance value+fourth resistance value); the second voltage=bias voltage* fourth resistance value / (third resistance value+fourth resistance value); the set deviation value refers to the sum of the on voltage drop generated by the first switch tube, the diode and the certain pair of field effect tubes.

[0015] As a second aspect of the application, the embodiment of the BMS provided in the technical scheme is as follows:

[0016] A BMS, comprising a matrix switch and a controller, the matrix switch comprising N pairs of field effect tubes, N being a natural number greater than or equal to 2; the connection relationship of each pair of field effect tubes is that the sources of the two tubes are connected together, the drain of one of the tubes is used to connect the battery end, the drain of the other tube is used to connect the input end of the BMS, and the gates of the two tubes are connected together.

[0017] Wherein: the BMS further comprises N driving circuits according to any one of the first aspect, each driving circuit being electrically connected to the gates of the two tubes of a certain pair of field effect tubes corresponding to N, and the controller controls the pair of field effect tubes connected by each driving circuit to be turned on or turned off at the same time.

[0018] Further, the BMS further comprises a first gating switch and a second gating switch, the drains of the other tubes of each odd pair of field effect tubes being connected together through the first gating switch tube to connect the input positive end or the input negative end of the BMS, and the drains of the other tubes of each even pair of field effect tubes being connected together through the second gating switch tube of the BMS to connect the input positive end or the input negative end.

[0019] The mode of the BMS matrix switch being turned on or turned off by the drive generated by the controller through the driving circuit can significantly save the cost and loss of the driving circuit, and the BMS has the beneficial effects that:

[0020] 1. The driving circuit for the BMS matrix switch in the embodiment of the utility model can realize the on or off control of the matrix switch only by two switch tubes, a diode and a plurality of resistors, has small board area, low cost, simple control and high reliability.

[0021] 2. The driving circuit for the BMS matrix switch in the utility model does not need an additional power supply circuit, the driving current only flows through the input end of the BMS when the matrix switch is turned on, only the weak leakage current flows through the battery side after the first switch tube is turned off when the matrix switch is turned off, and the influence on the battery string balance is very small. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1The typical application schematic diagram of the existing matrix switch driving chip;

[0023] Figure 2 The application schematic diagram of the existing matrix switch driving relying on the battery side power supply;

[0024] Figure 3 The principle diagram of the driving circuit of the first embodiment of the utility model;

[0025] Figure 4 The specific principle diagram of the BMS of the second embodiment of the utility model. DETAILED DESCRIPTION

[0026] In order to make the above object, characteristics and advantages of the utility model more apparent, easy to understand, the specific embodiment of the utility model is described in detail below with the drawings, obviously, the described embodiment is a part of the embodiment of the utility model, rather than all the embodiments. Based on the embodiment in the application, all other embodiments obtained by the person skilled in the art without making creative labor should belong to the protection scope of the application.

[0027] It should be noted that the terms "include" and "have" and any variations thereof described in the specification and claims of the application are intended to cover the non-exclusive inclusion, for example, the inclusion of a series of components, unit circuits or control sequences does not have to be limited to those components, unit circuits or control sequences clearly listed, but can include components, unit circuits or control sequences not clearly listed or inherent to these circuits.

[0028] In addition, the embodiments in the application and the features in the embodiments can be combined with each other without conflict.

[0029] It should be understood that, in the specification and claims, when describing that an element is "connected" to another element, the element can be "directly connected" to the other element, or "connected" to the other element through a third element; when describing that a step is connected to another step, the step can be directly connected to the other step, or connected to the other step through a third step.

[0030] First embodiment

[0031] The embodiment provides a kind of driving circuit, as shown in Figure 3 The principle diagram of the driving circuit of the first embodiment of the utility model, for controlling the conduction and turn-off of a pair of field effect tubes SW1-a and SW1-b in BMS matrix switch by controller, the source of the pair of field effect tubes is connected together, one drain is used to connect battery end, another drain is used to connect input end, gate is connected together, for realizing the simultaneous opening or simultaneous turn-off of two tubes, wherein, driving circuit includes:

[0032] a bias voltage Vcc, a first switch tube Q1, a second switch tube K1, a diode D1, a first resistor R1, a second resistor R2 and a third resistor R3. The first end of the first switch tube Q1 and the first end of the first resistor R1 are connected to the bias voltage Vcc, the control end of the first switch tube Q1 and the second end of the first resistor R1 are connected to the first end of the second resistor R2, the second end of the first switch tube Q1 is connected to the anode of the diode D1, the cathode of the diode D1 is connected to the gate of a certain pair of field effect tubes SW1-a and SW1-b in series with the third resistor R3, the second end of the second resistor R2 is connected to the first end of the second switch tube K1, the second end of the second switch tube K1 is connected to the ground end of the bias voltage Vcc, and the control end of the second switch tube K1 is electrically connected to the controller.

[0033] The controller controls the turn-on or turn-off of the field effect tubes SW1-a and SW1-b through the driving circuit.

[0034] The driving circuit for the BMS matrix switch in the embodiment only needs one PNP transistor or PMOS tube, one small switch tube, one diode and several resistors to realize the turn-on or turn-off control of the matrix switch, has small board area, low cost, simple control and high reliability.

[0035] The driving circuit for the BMS matrix switch in the embodiment does not need an additional power supply circuit, the driving current only flows through the input end of the BMS when the matrix switch is turned on, and only the weak leakage current flows through the battery side after the first switch tube is turned off when the matrix switch is turned off, which has little effect on the balance of the battery string.

[0036] Further, the driving circuit further comprises a fourth resistor R4 connected between the gate connection point and the source connection point of the field effect tubes SW1-a and SW1-b.

[0037] Preferably, the first switch tube Q1 is a PNP transistor or a P-type field effect tube.

[0038] Preferably, the second switch tube K1 is a field effect tube, a transistor or an IGBT, used for controlling the turn-on and turn-off of the first switch tube Q1.

[0039] Preferably, the bias voltage Vcc is greater than the BMS input positive terminal voltage Vin. When the field effect tube SW1-a drain is connected to the BMS input positive terminal, the driving voltage of the field effect tubes SW1-a and SW1-b when turned on is equal to the first voltage plus or minus a set deviation value, the first voltage=(bias voltage-BMS input positive terminal voltage)×fourth resistance value / (third resistance value+fourth resistance value), and the set deviation value refers to the sum of the turn-on voltage drops of the first switch tube Q1, diode D1, field effect tubes SW1-a and SW1-b; when the field effect tube SW1-a drain is connected to the input negative terminal, the driving voltage of the field effect tubes SW1-a and SW1-b when turned on is equal to the second voltage plus or minus a set deviation value, the second voltage=bias voltage×fourth resistance value / (third resistance value+fourth resistance value), and the set deviation value also refers to the sum of the turn-on voltage drops of the first switch tube Q1, diode D1, field effect tubes SW1-a and SW1-b.

[0040] Second embodiment

[0041] The embodiment provides a BMS, which comprises a matrix switch and a controller, the matrix switch comprises N pairs of field effect tubes, N is a natural number greater than or equal to 2; the connection relationship of each pair of field effect tubes is that the sources of the two tubes are connected together, the drain of one tube is used for connecting a battery end, the drain of the other tube is used for connecting a BMS input end, and the gates of the two tubes are connected together.

[0042] The BMS further comprises N driving circuits in any one of the first embodiments, M is a natural number less than or equal to N, each driving circuit is connected to the gates of two tubes of a pair of field effect tubes, and the controller controls the pair of field effect tubes connected by each driving circuit to be turned on or turned off at the same time.

[0043] Figure 4 The BMS is a specific schematic diagram of the second embodiment of the utility model, and the diagram shows a circuit schematic diagram when the Mth battery in a BMS system battery string is charged and discharged. The diagram comprises:

[0044] A battery string composed of a battery bat1, a battery bat2,..., a battery bat (M-1), a battery batM, a battery bat (M-1),..., and a battery bat (N-1) in series.

[0045] The matrix switch pairs formed by the field effect tube SW1, the field effect tube SW2, …, the field effect tube SWM, the field effect tube SW(M+1), …, the field effect tube SWN. Each pair of matrix switch pairs is composed of an a field effect tube and a b field effect tube connected back to back. The source electrodes of each pair of a field effect tube and b field effect tube are connected together. The gate electrodes of each pair of a field effect tube and b field effect tube are connected together and then a resistor R4 is connected in series to the source electrode. The drain electrode of each b field effect tube is used to connect the corresponding battery end.

[0046] The drain electrode of the field effect tube SW1-b is connected to the negative end of the battery bat1, the drain electrode of the field effect tube SW2-b is connected to the negative end of the battery bat2, …, the drain electrode of the field effect tube SW(N-1)-b is connected to the negative end of the battery bat(N-1), and the drain electrode of the field effect tube SWN-b is connected to the positive end of the battery bat(N-1).

[0047] The drain electrodes of the odd-numbered a field effect tubes are connected to the A end, and the drain electrodes of the even-numbered a field effect tubes are connected to the B end.

[0048] Further comprising:

[0049] The gating switch S1, the gating switch S2, the input end, the controller, and the driving circuit 1, the driving circuit 2, …, the driving circuit M, the driving circuit (M+1), and the driving circuit N. One end of the gating switch S1 is connected to the A end, and the other end can select the input positive end Vin or the input negative end GND. One end of the gating switch S2 is connected to the B end, and the other end can select the input positive end Vin or the input negative end GND.

[0050] When the odd-numbered batteries need to be recharged and discharged, the other end of S1 is selected to the input negative end GND, and the other end of S2 is selected to the input positive end Vin. When the even-numbered batteries need to be recharged and discharged, the other end of S1 is selected to the input positive end Vin, and the other end of S2 is selected to the input negative end GND.

[0051] When the battery batM needs to be charged and discharged, the controller opens the corresponding matrix switch pair SWM-a / b and the matrix switch pair SW(M+1)-a / b through the driving circuit M and the driving circuit (M+1), and closes the corresponding matrix switch pair through other driving circuits to prevent short circuit of the battery string.

[0052] The following focuses on the complete working condition of charging / discharging the odd-numbered battery batM. The working steps and principles are as follows:

[0053] I. Gating switch configuration and opening of corresponding matrix switch:

[0054] 1、The controller controls the other end of the gating switch S1 to be gated to the input negative terminal GND, and the controller controls the other end of the gating switch S2 to be gated to the input positive terminal Vin.

[0055] 2、The controller outputs high-level driving signals GM, G(M+1), and other driving signals are low level. At this time, the switch tubes KM, KM+1 are turned on. The bias voltage Vcc, RM1 / / QM-eb, RM2, KM, the gating switch S1 and GND are connected in series to form a driving circuit, a driving current is generated between the emitter and the base of the transistor QM, the emitter and the collector of the transistor QM are saturated and turned on, and further, the bias voltage Vcc, the transistor QM-ec, the diode DM, the resistor RM3, the resistor RM4, the body diode of the field effect tube SWM-a, the gating switch S1 and GND form a driving circuit. By setting appropriate resistors RM3 and RM4, the voltage across the resistor RM4 is greater than the driving voltage of the field effect tube SWM-a, and then the field effect tubes SWM-a and SWM-b are turned on. The bias voltage Vcc, R(M+1)1 / / QM+1-eb, R(M+1)2, KM+1, the gating switch S1 and GND are connected in series to form a driving circuit, a driving current is generated between the emitter and the base of the transistor QM+1, the emitter and the collector of the transistor QM+1 are saturated and turned on, and further, the bias voltage Vcc, the transistor QM+1-ec, the diode DM+1, the resistor R(M+1)3, the resistor R(M+1)4, the body diode of the field effect tube SW(M+1)-a, the gating switch S2, the input Vin positive terminal, the input capacitor Cin and GND form a driving circuit. By setting appropriate resistors R(M+1)3 and R(M+1)4, the voltage across the resistor R(M+1)4 is greater than the driving voltage of the field effect tube SW(M+1)-a, and then the field effect tubes SW(M+1)-a and SW(M+1)-b are turned on.

[0056] II. Complete the charging / discharging process of the battery batM according to the requirements.

[0057] III. Gating switch reset and corresponding matrix switch off:

[0058] 1、The controller outputs low-level driving signals GM, G(M+1), and other driving signals remain low level. At this time, the switch tubes KM1, KM+1 are turned off, the driving current between the emitter and the base of the transistors QM1 and QM+1 is reduced to 0A, the emitter and the collector of the transistors QM1 and QM+1 are turned off, and the driving voltage between the gate and the source of the field effect tubes SWM-a / b and SW(M+1)-a / b is discharged to below the off voltage through the resistors RM4 and R(M+1)4, so that the field effect tubes SWM-a / b and SW(M+1)-a / b are turned off.

[0059] 2, the controller controls the other end of the gating switch S1 and the gating switch S2 to be gated to the input negative terminal GND.

[0060] When charging and discharging other single batteries in the BMS battery string, the corresponding operation is carried out according to the above three steps, and details are not repeated.

[0061] From the above working principle, when charging / discharging the battery batM in the second step, QM, QM+1, DM, DM+1, SWM-a and SW(M+1)-a are saturated and ignored, and the voltages of the key points are as follows:

[0062] The driving voltage of SWM-a / b is approximately Vcc*RM4 / (RM3+RM4);

[0063] The driving voltage of SW(M+1)-a / b is approximately (Vcc-Vin)*R(M+1)4 / (R(M+1)3+R(M+1)4);

[0064] The voltage between the triode Q1-ce is approximately -V bat1 -V bat2 -……-V bat(M-1) -Vcc, the diode D1 is positively biased and conducts;

[0065] The voltage between the triode QN-ce is approximately 0V, and the diode D1 is reverse-biased and cut off, and the cut-off voltage is V batM +V bat(M+1) +……+V bat(N+1) -Vcc;

[0066] Therefore, when selecting materials, the withstand voltage of the triode and the diode needs to be greater than the total voltage of the battery string + Vcc, so as to ensure the reliability of the driving circuit.

[0067] As can be seen from the embodiment, the switch tubes K1-KN are common ground, and the required driving current is extremely small, so the cost of the controller can be significantly reduced. The withstand voltage of the triodes Q1-QN and the diodes D1-DN is slightly higher, but the cost is extremely low. The BMS matrix switch as a whole adopts a non-isolated driving scheme, which can also significantly reduce the cost. When turned off, only the triode and the field effect tube drain current flows through the battery string, so the influence on the balancing degree of the battery string is extremely small.

[0068] The above is only a preferred embodiment of the present application. The above preferred embodiment should not be regarded as limiting the present application. For ordinary skilled persons in the art, without departing from the spirit and scope of the present application, a number of equivalent transformations, improvements and refinements can be made, and these equivalent transformations, improvements and refinements should also be regarded as the protection scope of the present application, which will not be repeated in the embodiments, and the protection scope of the present application should be limited by the scope defined by the claims.

Claims

1. A driving circuit applied to a BMS, the BMS comprising a matrix switch and a controller, the matrix switch comprising a plurality of pairs of field effect tubes, the connection relationship of each pair of field effect tubes being that the sources of the two tubes are connected together, the drain of one of the tubes is used to connect a battery end, the drain of the other tube is used to connect an input end of the BMS, and the gates of the two tubes are connected together, the controller controls a pair of field effect tubes to be turned on or turned off at the same time through the driving circuit, characterized in that, The drive circuit comprises: The first switch tube, the second switch tube, the diode, the first resistor, the second resistor and the third resistor; wherein the first end of the first switch tube and the first end of the first resistor are connected to input a bias voltage, the control end of the first switch tube, the second end of the first resistor and the first end of the second resistor are connected, the second end of the first switch tube is connected with the anode of the diode, the cathode of the diode is connected with the third resistor in series and then is connected to the gate of the two tubes of the certain pair of field effect tubes, the second end of the second resistor is connected with the first end of the second switch tube, the second end of the second switch tube is connected to the ground, and the control end of the second switch tube is connected to the controller.

2. The drive circuit of claim 1, wherein: The drive circuit further comprises a fourth resistor, which is connected between the gate connection point and the source connection point of the two tubes of the certain pair of field effect tubes.

3. The drive circuit of claim 1, wherein: The first switch tube is a PNP type triode or a P type field effect tube.

4. The drive circuit of claim 1, wherein: The second switch tube is a field effect tube, a triode or an IGBT, which is used to control the turn-on and turn-off of the first switch tube.

5. The drive circuit of claim 1, wherein: The bias voltage is greater than the BMS input positive end voltage; when the other drain of the certain pair of field effect tubes is connected to the input positive end of the BMS, the drive voltage provided by the drive circuit between the gate and the source of the certain pair of field effect tubes when the certain pair of field effect tubes is turned on is equal to the first voltage plus or minus a set deviation value; when the other drain of the certain pair of field effect tubes is connected to the input negative end of the BMS, the drive voltage provided by the drive circuit between the gate and the source of the certain pair of field effect tubes when the certain pair of field effect tubes is turned on is equal to the second voltage plus or minus a set deviation value; Wherein: the first voltage = (bias voltage - BMS input positive end voltage) * fourth resistor resistance value / (third resistor resistance value + fourth resistor resistance value); the second voltage = bias voltage * fourth resistor resistance value / (third resistor resistance value + fourth resistor resistance value); the set deviation value refers to the sum of the turn-on voltage drops generated by the first switch tube, the diode and the certain pair of field effect tubes.

6. A BMS comprising a matrix switch and a controller, the matrix switch comprising N pairs of field effect tubes, N being a natural number greater than or equal to 2; the connection relationship of each pair of field effect tubes is that the sources of the two tubes are connected together, the drain of one tube is used to connect a battery end, the drain of the other tube is used to connect the input end of the BMS, and the gates of the two tubes are connected together. characterized in that The BMS further comprises N drive circuits according to any one of claims 1 to 5, each drive circuit being electrically connected to the gates of the two tubes of the corresponding certain pair of field effect tubes, and the controller controls the corresponding certain pair of field effect tubes to be turned on or turned off at the same time through each drive circuit.

7. The BMS of claim 6, wherein: The BMS further comprises a first gating switch and a second gating switch, the other drains of each odd pair of field effect tubes are connected together and then connected to the input positive end or the input negative end of the BMS through the first gating switch, and the other drains of each even pair of field effect tubes are connected together and then connected to the input positive end or the input negative end of the BMS through the second gating switch.

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