A circuit for automatically switching polarity of single cells in a series battery pack

Abstract

The present invention discloses a circuit for automatically switching polarity of a single cell in a series battery pack, comprising a single cell, both ends of the single cell are electrically connected to an automatic switch switching circuit, both ends of the single cell are electrically connected to a DMOS automatic polarity switching circuit through respective automatic switch switching circuits, and the DMOS automatic polarity switching circuit is electrically connected to a supercapacitor. The present invention adds a group of automatic polarity switching circuits composed of DMOS between the supercapacitor and the node of the series battery pack, reduces the number of lines between the supercapacitor and the node of the series battery pack, and only half of the original number of lines is needed to achieve the same effect, greatly reducing the cost and the complexity of the lines, simplifying the control program logic, and improving the safety, reliability and flexibility of the balanced charging and discharging of the series battery pack.

Description

Technical Field

[0001] The invention belongs to the technical field of power conversion and relates to an automatic polarity switching circuit for single cells in a series battery pack. Background Art

[0002] Nowadays, new energy vehicles are becoming more and more popular, but new energy vehicles themselves also have some problems. One of the major problems of new energy vehicles is the problem of battery charging balance. The battery of new energy vehicles is composed of multiple series battery packs in parallel. When charging and discharging single cells in a series battery pack, the nodes between the series batteries need to be connected to a common supercapacitor for energy balance. For each node, one is the positive pole and the other is the negative pole for two adjacent single cells. In order to ensure that the polarity of the two ends of the supercapacitor is not wrong when each battery is charged and discharged, conventional circuits often use battery lines that are twice the number of battery cells for multiple switching, which greatly increases the cost and circuit complexity, and is too cumbersome to write the control program logic. Summary of the invention

[0003] The purpose of the present invention is to provide a circuit for automatically switching the polarity of single cells in a series battery pack, which solves the problems of complex battery circuits and cumbersome control program logic writing in the prior art for batteries of new energy vehicles.

[0004] The technical solution adopted by the present invention is a circuit for automatically switching the polarity of a single cell in a series battery pack, comprising a single cell, both ends of the single cell are electrically connected to an automatic switch switching circuit, both ends of the single cell are electrically connected to a DMOS automatic polarity switching circuit through their own automatic switch switching circuits, and the DMOS automatic polarity switching circuit is electrically connected to a supercapacitor.

[0005] The present invention is also characterized in that:

[0006] The automatic switch switching circuit includes a resistor and an optocoupler relay. The two-end circuit BT0 of the single battery is connected to the collector of the phototransistor in the optocoupler relay U0, the emitter of the phototransistor in the optocoupler relay U0 is connected to the CAP A port, the IO port S0 pin of the control chip is connected to the cathode of the light-emitting diode in the optocoupler relay U0, and the 3.3V power supply is connected to the anode of the light-emitting diode in the optocoupler relay U0 through the current limiting resistor R1. The remaining circuits are connected in sequence in the above manner; BT0, BT2, BT4, BT6, BT8, BT10, and BT12 are connected in parallel to the CAP A terminal through the optocoupler relays U0, U2, U4, U6, U8, U10, and U12, and BT1, BT3, BT5, BT7, BT9, and BT11 are connected in parallel to the CAP B terminal through the optocoupler relays U1, U3, U5, U7, U9, and U11.

[0007] The control end of the optical coupler relay is electrically connected to the control chip.

[0008] The control program of the control chip is implemented in the following steps:

[0009] Step 1, check the power of each single battery;

[0010] Step 2: Select the single battery that needs to be charged and discharged according to the result of step 1;

[0011] Step 3: Switch the single cell battery according to the result of step 2.

[0012] The DMOS automatic polarity switching circuit includes four dual-channel MOS tubes, one pair of which is a P-channel dual-channel DMOS-P tube Q1 and Q2, and the other pair is an N-channel dual-channel DMOS-N tube Q3 and Q4, the CAP A end is connected to Pin_1 of Q1, connected to Pin_2Pin_4 of Q2 through R5, connected to Pin_2Pin_4 of Q3 through R2, connected to Pin_1Pin_3 of Q3 through R4, connected to Pin_1Pin_3 of Q4 through R7, connected to Pin_2Pin_4 of Q4 through R8, and connected to Pin_7Pin_8 of Q4; CAP The B end is connected to Pin_2Pin_4 of Q1 through R1, connected to Pin_1 of Q2, connected to Pin_7Pin_8 of Q3, connected to Pin_1Pin_3 of Q3 through R3, connected to Pin_2Pin_4 of Q3 through R4, connected to Pin_2Pin_4 of Q4 through R6, and connected to Pin_1Pin_3 of Q4 through R8; Q1 is connected to Pin_5, Pin_6, Pin_7, and Pin_8 of Q2, Pin_3 of Q1 and Q2 is connected in parallel to PE A end, and Pin_5Pin_6 of Q3 and Q4 is connected in parallel to PE B end.

[0013] The beneficial effects of the present invention are:

[0014] 1. The present invention adds a group of automatic polarity switching circuits composed of DMOS between the nodes of the supercapacitor and the series battery pack, which reduces the number of lines between the supercapacitor and the nodes of the series battery pack. Only half of the original number of lines is needed to achieve the same effect, and the polarity discrimination and switching functions in both directions of battery discharge and charging are automatically realized.

[0015] 2. The present invention greatly reduces the cost and circuit complexity, simplifies the control program logic, and improves the safety, reliability and flexibility of balanced charging and discharging of series-connected battery packs. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1This is an example diagram of a single cell automatic switch circuit in a series battery pack of the present invention, which is applied to a 12-cell single cell group;

[0017] Figure 2 This is an example diagram of an automatic polarity switching circuit during charging and discharging of a single cell polarity automatic switching circuit in a series battery pack of the present invention;

[0018] Figure 3 This is an example diagram of a polarity automatic switching circuit for a single cell in a series battery pack of the present invention, in which the CAP A terminal is a positive electrode and the CAPB terminal is a negative electrode during discharge;

[0019] Figure 4 This is an example of a circuit diagram of automatic polarity switching of a single cell in a series battery pack of the present invention. The A end of the CAP is the positive electrode and the CAPB end is the negative electrode when charging.

[0020] Figure 5 This is an example diagram of a polarity automatic switching circuit for a single cell in a series battery pack of the present invention, in which the CAP A terminal is a negative electrode and the CAPB terminal is a positive electrode during discharge;

[0021] Figure 6 The present invention is a circuit diagram showing an automatic polarity switching circuit when charging, in which the CAP A terminal is a negative electrode and the CAPB terminal is a positive electrode in an automatic polarity switching circuit of a single cell in a series battery pack. DETAILED DESCRIPTION

[0022] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments.

[0023] A single cell polarity automatic switching circuit in a series battery pack includes a single cell, both ends of the single cell are electrically connected to an automatic switch switching circuit, both ends of the single cell are electrically connected to a DMOS automatic polarity switching circuit through their own automatic switch switching circuits, and the DMOS automatic polarity switching circuit is electrically connected to a super capacitor.

[0024] like Figure 1As shown, the automatic switch switching circuit includes a resistor and a photocoupler relay, the two-end circuit BT0 of the single battery is connected to the collector of the phototransistor in the photocoupler relay U0, the emitter of the phototransistor in the photocoupler relay U0 is connected to the CAP A port, the IO port S0 pin of the control chip is connected to the cathode of the light-emitting diode in the photocoupler relay U0, the 3.3V power supply is connected to the anode of the light-emitting diode in the photocoupler relay U0 through the current limiting resistor R1, and the remaining circuits are connected in sequence according to the above method; BT0, BT2, BT4, BT6, BT8, BT10, BT12 are connected to the CAP A terminal in parallel through the photocoupler relays U0, U2, U4, U6, U8, U10, U12, and BT1, BT3, BT5, BT7, BT9, BT11 are connected to the CAP B terminal in parallel through the photocoupler relays U1, U3, U5, U7, U9, U11.

[0025] The control end of the optical coupler relay is electrically connected to the control chip.

[0026] The control program of the control chip is implemented in the following steps:

[0027] Step 1, check the power of each single battery;

[0028] Step 2: Select the single battery that needs to be charged and discharged according to the result of step 1;

[0029] Step 3: Switch the single cell battery according to the result of step 2.

[0030] like Figure 1 As shown, the working principle of the automatic switch switching circuit is: when the single battery is charged and discharged, only the two end circuits of one single battery are connected to the DMOS automatic polarity switching circuit each time. When the IO port sends a low level signal to the control end of the optocoupler relay, the phototransistor of the optocoupler relay is turned on, so that the single battery is connected to the automatic polarity switching circuit.

[0031] like Figure 2 As shown, the DMOS automatic polarity switching circuit includes four dual-channel MOS tubes, one pair of which is a P-channel dual-channel DMOS-P tube Q1 and Q2, and the other pair is an N-channel dual-channel DMOS-N tube Q3 and Q4, and the resistor in the DMOS automatic polarity switching circuit plays the role of a strong pull resistor. The resistor connected to the gate of the P-channel dual-channel DMOS-P tube plays the role of a pull-down resistor so that the gate connected to the input power supply can be at a low potential, so that the P-channel dual-channel DMOS-P tube is smoothly turned on, and the resistor connected to the gate of the N-channel dual-channel DMOS-N tube plays the role of a pull-up resistor so that the gate connected to the input power supply can be at a high potential, so that the N-channel dual-channel DMOS-N tube is smoothly turned on.

[0032] CAP A end is connected to Pin_1 of Q1, connected to Pin_2Pin_4 of Q2 through R5, connected to Pin_2Pin_4 of Q3 through R2, connected to Pin_1Pin_3 of Q3 through R4, connected to Pin_1Pin_3 of Q4 through R7, connected to Pin_2Pin_4 of Q4 through R8, and connected to Pin_7Pin_8 of Q4; CAP The B end is connected to Pin_2Pin_4 of Q1 through R1, connected to Pin_1 of Q2, connected to Pin_7Pin_8 of Q3, connected to Pin_1Pin_3 of Q3 through R3, connected to Pin_2Pin_4 of Q3 through R4, connected to Pin_2Pin_4 of Q4 through R6, and connected to Pin_1Pin_3 of Q4 through R8; Q1 is connected to Pin_5, Pin_6, Pin_7, and Pin_8 of Q2, Pin_3 of Q1 and Q2 is connected in parallel to PE A end, and Pin_5Pin_6 of Q3 and Q4 is connected in parallel to PE B end.

[0033] The present invention discloses a circuit for automatically switching the polarity of a single cell in a series battery pack, and its working principle is as follows:

[0034] 1. When the single battery is discharged

[0035] (1) Figure 3 As shown, if the CAP A end is the positive electrode and the CAP B end is the negative electrode, a negative voltage difference is generated between Pin_2 and Pin_1 of the DMOS-P tube Q1, so that the left MOS tube is turned on to output Pin_8, and the negative voltage difference between Pin_4 and Pin_5 makes the right MOS tube turned on to output Pin_3, and CAP A is connected to the positive electrode of the supercapacitor via the DMOS-P tube Q1 and PE A; Pin_2 and Pin_8 of the DMOS-N tube Q3 generate a positive voltage difference, so that the left MOS tube is turned on to output Pin_1, and a positive voltage difference is generated between Pin_4 and Pin_3, so that the right MOS tube is turned on to output Pin_5, and CAP B is connected to the negative electrode of the supercapacitor via the DMOS-N tube Q3 and PE B.

[0036] (2) Figure 5As shown, if the CAP A terminal is the negative electrode and the CAP B terminal is the positive electrode, a positive voltage difference is generated between Pin_2 and Pin_8 of the DMOS-N tube Q4 to turn on the left MOS tube Pin_1 output, and a positive voltage difference is generated between Pin_3 and Pin_4 to turn on the right MOS tube CAP A through the DMOS-N tube Q4 and PE B to connect to the negative electrode of the super capacitor; a negative voltage difference is generated between Pin_2 and Pin_1 pins of the DMOS-P tube Q2 to turn on the left MOS tube Pin_8 output, and a negative voltage difference is generated between Pin_4 and Pin_5 to turn on the right MOS tube Pin_3 output, and CAP B is connected to the positive electrode of the super capacitor through the DMOS-P tube Q2 and PE A.

[0037] Combining the above two situations (1) and (2), no matter whether CAP A and CAP B are positive or negative, the positive and negative polarities of the supercapacitors connected at both ends are fixed.

[0038] 2. When the single battery is charging

[0039] (1) Figure 4 As shown, if CAP A is the positive electrode and CAP B is the negative electrode, a negative voltage difference is generated between Pin_3 and Pin_4 of the DMOS-P tube Q1, so that the right MOS tube is turned on to output Pin_5, and a negative voltage difference is generated between Pin_2 and Pin_8, so that the left MOS tube is turned on to output Pin_1, and the positive electrode of the super capacitor is connected to CAP A via PE A and the DMOS-P tube Q1; a positive voltage difference is generated between Pin_4 and Pin_5 of the DMOS-N tube Q3, so that the right MOS tube is turned on to output Pin_3, and a positive voltage difference is generated between the Pin_2 and Pin_1 pins, so that the left MOS tube is turned on to output Pin_8, and the negative electrode of the super capacitor is connected to CAP B via PE B and the DMOS-N tube Q3.

[0040] (2) Figure 6 As shown, if CAP A is the negative electrode and CAP B is the positive electrode, a negative voltage difference is generated between Pin_3 and Pin_4 of the DMOS-P tube Q2, so that the right MOS tube is turned on to output Pin_5, and a negative voltage difference is generated between Pin_2 and Pin_8, so that the European MOS tube is turned on to output Pin_1, and the positive electrode of the super capacitor is connected to CAP B via PE A and the DMOS-P tube Q3; a positive voltage difference is generated between Pin_4 and Pin_5 of the DMOS-N tube Q4, so that the right MOS tube is turned on to output Pin_3, and a positive voltage difference is generated between Pin_2 and Pin_1, so that the left MOS tube is turned on to output Pin_8, and the negative electrode of the super capacitor is connected to CAP A via PE B and the DMOS-N tube Q4.

[0041] The invention discloses an automatic polarity switching circuit for single cells in a series battery pack, which has the advantages that a group of automatic polarity switching circuits composed of DMOS is added between a supercapacitor and a node of the series battery pack, thereby reducing the number of lines between the supercapacitor and the node of the series battery pack, and only half of the original number of lines is needed to achieve the same effect, which greatly reduces the cost and complexity of the lines, simplifies the control program logic, and improves the safety, reliability and flexibility of balanced charging and discharging of the series battery pack.

Claims

1. A circuit for automatically switching polarity of single cells in a series battery pack, characterized in that: It comprises n series-connected single cells, n+1 automatic switch switching circuits, a DMOS automatic polarity switching circuit and a super capacitor, wherein both ends of each single cell are electrically connected to the automatic switch switching circuit, and both ends of the single cell are electrically connected to the DMOS automatic polarity switching circuit through their respective automatic switch switching circuits, and the DMOS automatic polarity switching circuit is electrically connected to the super capacitor; Each of the automatic switch switching circuits includes a current limiting resistor and a photocoupler relay, and the control end of the photocoupler relay is electrically connected to a control chip; the positive terminal BT0 of the first single battery is connected to the collector of the phototransistor in the first photocoupler relay U0, and the emitter of the phototransistor in the photocoupler relay U0 is connected to the CAP A port, the IO port S0 pin of the control chip is connected to the cathode of the light-emitting diode in the photocoupler relay U0, and the 3.3V power supply is connected to the anode of the light-emitting diode in the photocoupler relay U0 through the first current limiting resistor, and the negative terminal of the first single battery, that is, the positive terminal BT1 of the second single battery, is connected to the collector of the phototransistor in the second photocoupler relay U1, and the emitter of the phototransistor in the photocoupler relay U1 is connected to the CAP B port, the control chip IO port S1 pin is connected to the cathode of the light-emitting diode in the optocoupler relay U1, and the 3.3V power supply is connected to the anode of the light-emitting diode in the optocoupler relay U1 through the second current-limiting resistor; the remaining lines are connected in sequence in the above manner: BT0, BT2, BT4, BT6, BT8, BT10, BT12... are connected to the CAPA end through the optocoupler relays U0, U2, U4, U6, U8, U10, U12... respectively, and BT1, BT3, BT5, BT7, BT9, BT11... are connected to the CAP B end through the optocoupler relays U1, U3, U5, U7, U9, U11... respectively; The DMOS automatic polarity switching circuit includes four dual-channel MOS tubes, one pair of which is a P-channel dual-channel DMOS-P tube Q1 and Q2, and the other pair is an N-channel dual-channel DMOS-N tube Q3 and Q4, CAP A end is connected to Pin_1 of Q1, CAP A end is connected to Pin_2 and Pin_4 of Q2 through a resistor R5, CAP A end is connected to Pin_2 and Pin_4 of Q3 through a resistor R2, CAP A end is connected to Pin_1 and Pin_3 of Q3 through a resistor R2 and a resistor R4, CAP A end is connected to Pin_1 and Pin_3 of Q4 through a resistor R7, CAP A end is connected to Pin_2 and Pin_4 of Q4 through a resistor R7 and a resistor R8, and CAP A end is connected to Pin_7 and Pin_8 of Q4; CAP B end is connected to Pin_2 and Pin_4 of Q1 through a resistor R1, CAP The B end is connected to Pin_1 of Q2, the CAP B end is connected to Pin_7 and Pin_8 of Q3, the CAP B end is connected to Pin_1 and Pin_3 of Q3 through resistor R3, the CAP B end is connected to Pin_2 and Pin_4 of Q3 through resistor R3 and resistor R4, the CAP B end is connected to Pin_2 and Pin_4 of Q4 through resistor R6, and the CAP B end is connected to Pin_1 and Pin_3 of Q4 through resistor R6 and resistor R8; Pin_5, Pin_6, Pin_7 and Pin_8 of Q1 are connected, Pin_5, Pin_6, Pin_7 and Pin_8 of Q2 are connected, Pin_3 of Q1 and Pin_3 of Q2 are both connected to the PE A end, Pin_5 and Pin_6 of Q3 and Pin_5 and Pin_6 of Q4 are both connected to the PE B end; the PE A end and the PE B end are respectively connected to the two ends of the supercapacitor; Among them, Q1 and Q2 include two PMOS tubes connected in reverse series, whose Pin_1 and Pin_3 are the drains of the two PMOS tubes respectively, Pin_2 and Pin_4 are the gates of the two PMOS tubes respectively, and Pin_5 and Pin_8 are the sources of the two PMOS tubes respectively; Q3 and Q4 include two NMOS tubes connected in reverse series, whose Pin_1 and Pin_3 are the sources of the two NMOS tubes respectively, Pin_2 and Pin_4 are the gates of the two PMOS tubes respectively, and Pin_5 and Pin_8 are the drains of the two PMOS tubes respectively.

2. The automatic polarity switching circuit of a single cell in a series battery pack according to claim 1, characterized in that: The control program of the control chip specifically implements battery pack balancing according to the following steps: Step 1, check the power of each single battery; Step 2: Select the single battery that needs to be charged and discharged according to the result of step 1; Step 3: Switch the single cell battery according to the result of step 2.

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