WO2018099324A1

WO2018099324A1 - Power battery overcharge protection circuit and device, and battery management system

Info

Publication number: WO2018099324A1
Application number: PCT/CN2017/112800
Authority: WO
Inventors: 谢哲锋; 陈武; 蒋步洪
Original assignee: 比亚迪股份有限公司
Priority date: 2016-11-30
Filing date: 2017-11-24
Publication date: 2018-06-07
Also published as: CN206432702U

Abstract

A power battery overcharge protection circuit and device, and a battery management system. The overcharge protection circuit comprises: a voltage detection circuit (10), used for detecting the voltage of a power battery; a temperature compensation circuit (20), separately connected to the voltage detection circuit and the power battery and used for carrying out temperature compensation on voltage detection circuit; a control circuit (30), connected to an output end of the voltage detection circuit and used for controlling a charging control loop to enter a disconnected state when the voltage of the power battery is greater than a preset voltage threshold, for implementing overcharge protection on the power battery. The circuit is able to directly control an operation of a charging control loop when the voltage of a power battery is greater than a preset voltage threshold, without involving software logical determination, and can also compensate a temperature drift of the voltage detection circuit by means of the temperature compensation circuit, thereby improving the speediness, accuracy, and reliability of overcharge protection.

Description

Overcharge protection circuit, device and battery management system for power battery

Cross-reference to related applications

The present application is based on a Chinese patent application filed on Nov. 30, 2016, the entire disclosure of which is hereby incorporated by reference.

Technical field

The present invention relates to the field of charging technologies, and in particular, to an overcharge protection circuit for a power battery, an overcharge protection device for a power battery, a battery management system, and an electric vehicle.

Background technique

At present, the overcharge protection function of the power battery is mainly integrated in the battery management system. The system collects the voltage of the power battery in real time, and performs software judgment on the collected voltage. When the voltage reaches the overcharge protection point, the system issues an instruction to control the corresponding The protection relay operates to realize the overcharge protection function of the power battery. Although the system can achieve overcharge protection of the power battery, it is mainly realized by software.

In addition, when the voltage of the power battery is collected, since the components in the voltage collecting circuit change with the temperature, the overcharge protection points of the power battery are different at different temperatures, so it is impossible to accurately determine whether the power battery has occurred. Charge.

Summary of the invention

The object of the present invention is to at least solve one of the above technical drawbacks.

To this end, the first object of the present invention is to provide an overcharge protection circuit for a power battery, which can directly control the operation of the charge control loop when the voltage of the power battery is greater than a preset voltage threshold, without software logic determination, and The temperature drift of the voltage detection circuit is also compensated by the temperature compensation circuit, thereby improving the speed, accuracy and reliability of the overcharge protection.

A second object of the present invention is to provide an overcharge protection device for a power battery.

A third object of the present invention is to provide a battery management system.

A fourth object of the present invention is to provide an electric vehicle.

In order to achieve the above object, an overcharge protection circuit for a power battery according to the first aspect of the present invention includes: a voltage detection circuit for detecting a voltage of the power battery; a temperature compensation circuit, the temperature a compensation circuit is respectively connected to the voltage detecting circuit and the power battery, wherein the temperature compensation circuit is configured to perform temperature compensation on the voltage detecting circuit; and the control circuit is connected to an output end of the voltage detecting circuit The control circuit is configured to control the charging control loop to be in an off state when the voltage of the power battery is greater than a preset voltage threshold. The power battery is overcharged.

According to the overcharge protection circuit of the power battery of the present invention, the voltage of the power battery is detected by the voltage detection circuit, and the voltage detection circuit is temperature compensated by the temperature compensation circuit, and the control circuit controls the charging when the voltage of the power battery is greater than the preset voltage threshold. The control loop is disconnected to overcharge the power battery. The circuit can directly control the charging control loop when the voltage of the power battery is greater than the preset voltage threshold, without software logic judgment, and compensate the temperature drift of the voltage detecting circuit by the temperature compensation circuit, thereby improving the rapidity of the overcharge protection. , accuracy and reliability.

Specifically, the voltage detecting circuit includes: a Zener tube, a cathode of the Zener tube is connected to a positive pole of the power battery through the temperature compensation circuit; a first optocoupler, the first of the first optocoupler The input end is connected to the anode of the Zener tube, the second input end of the first optocoupler is connected to the negative pole of the power battery; the first resistor, one end of the first resistor and the first optocoupler The first output is connected to the other end, the other end of the first resistor is connected to the preset power source; the second resistor is connected to the second output end of the first optocoupler, the second The other end of the resistor is grounded, and a first node is connected between one end of the second resistor and the second output end of the first optocoupler, and the first node is connected to the control circuit.

Further, the temperature compensation circuit includes: a first PTC (Positive Temperature Coefficient) module, one end of the first PTC module is connected to the cathode of the Zener tube, and the other of the first PTC module One end is connected to the positive pole of the power battery.

Specifically, the voltage detecting circuit includes: a first comparator, a third resistor, a fourth resistor, and a second optocoupler, wherein a positive input end of the first comparator is connected to an anode of the power battery, The output end of the first comparator is connected to the first preset power source through a third resistor; one end of the fourth resistor is connected to the first preset power source, and the other end of the fourth resistor is connected to the first a negative input end of the comparator is connected, and the other end of the fourth resistor is further connected to a negative pole of the power battery through the temperature compensation circuit; a first input end of the second optocoupler and the first comparator The second input end of the second optocoupler is connected to the first ground end, the first output end of the second optocoupler is connected to the second preset power source, and the second optocoupler is connected The two outputs are connected to the control circuit.

Further, the temperature compensation circuit includes: a second PTC module, one end of the second PTC module is respectively connected to the other end of the fourth resistor, and the negative input end of the first comparator, the second The other end of the PTC module is connected to the negative pole of the power battery.

Specifically, the control circuit includes: a first MOS transistor, a second MOS transistor, a third MOS transistor, a fifth resistor, a sixth resistor, a first capacitor, and a first relay, wherein the gate of the first MOS transistor a pole connected to an output end of the voltage detecting circuit, a source of the first MOS transistor being grounded; a gate of the second MOS transistor being connected to a drain of the first MOS transistor, the second MOS transistor The gate is also connected to the preset power source through a fifth resistor, the source of the second MOS transistor is connected to the ground; the gate of the third MOS transistor is connected to the drain of the second MOS transistor, The gate of the third MOS transistor is also passed through the sixth electricity The resistor is connected to the preset power source, the source of the third MOS transistor is connected to the ground, and the source of the third MOS transistor is further connected to the gate of the third MOS transistor through a first capacitor; One end of the coil of the first relay is connected to the drain of the third MOS tube, and the other end of the coil of the first relay is connected to the preset power source, and one end of the normally open contact of the first relay Connected to the gate of the second MOS transistor, the other end of the normally open contact of the first relay is connected to the ground, and both ends of the normally closed contact of the first relay are connected to the charging control loop in.

Further, the temperature compensation circuit further includes: a third PTC module, one end of the third PTC module is connected to the other end of the first resistor, and the other end of the third PTC module is connected to the preset power source Connected.

Specifically, the control circuit includes: a seventh resistor, one end of the seventh resistor is connected to an output end of the voltage detecting circuit; a fourth MOS transistor, a gate of the fourth MOS transistor, and the seventh The other end of the resistor is connected, the source of the fourth MOS transistor is connected to the second ground, the drain of the fourth MOS transistor is connected to one end of the seventh resistor; the second relay, the second relay One end of the coil is respectively connected to a drain of the fourth MOS transistor, one end of the seventh resistor, and one end of a normally open contact of the second relay, and the other end of the coil of the second relay is respectively The second predetermined power source is connected to the other end of the normally open contact of the second relay, and both ends of the normally closed contact of the second relay are connected in the charging control loop.

In order to achieve the above object, a second aspect of the present invention provides an overcharge protection device for a power battery, comprising the overcharge protection circuit of the power battery proposed by the first aspect of the present invention.

According to the overcharge protection device of the power battery of the present invention, the overcharge protection circuit can directly control the operation of the charge control loop when the voltage of the power battery is greater than the preset voltage threshold, without software logic determination, and through the temperature compensation circuit Compensation for temperature drift of the voltage detection circuit improves the speed, accuracy and reliability of overcharge protection.

In order to achieve the above object, a third aspect of the present invention provides a battery management system including the overcharge protection device for the power battery of the second aspect of the present invention.

According to the battery management system of the present invention, the overcharge protection device of the power battery can directly control the charging control loop when the voltage of the power battery is greater than the preset voltage threshold, without software logic judgment, and through the temperature compensation circuit The temperature drift of the voltage detection circuit is compensated, which improves the speed, accuracy and reliability of the overcharge protection.

In order to achieve the above object, a fourth aspect of the invention provides an electric vehicle comprising the overcharge protection device of the power battery of the second aspect of the invention.

According to the electric vehicle of the present invention, the overcharge protection device of the power battery can directly control the charging control loop when the voltage of the power battery is greater than the preset voltage threshold, without software logic judgment, and the voltage is compensated by the temperature compensation circuit. The temperature drift of the detection circuit is compensated, which improves the speed, accuracy and reliability of the overcharge protection.

The additional aspects and advantages of the invention will be set forth in part in the description which follows.

DRAWINGS

The above and/or additional aspects and advantages of the present invention will become apparent and readily understood from

1 is a block diagram of an overcharge protection circuit of a power battery according to an embodiment of the present invention;

2 is a circuit diagram of an overcharge protection circuit of a power battery according to a first embodiment of the present invention;

3 is a circuit diagram of an overcharge protection circuit of a power battery according to a second embodiment of the present invention;

4 is a circuit diagram of an overcharge protection circuit of a power battery according to a third embodiment of the present invention;

Figure 5 is a circuit diagram of an overcharge protection circuit of a power battery according to a fourth embodiment of the present invention;

6 is a schematic diagram of an overcharge protection device for a power battery according to an embodiment of the present invention;

7 is a schematic diagram of a battery management system in accordance with one embodiment of the present invention.

detailed description

The embodiments of the present invention are described in detail below, and the examples of the embodiments are illustrated in the drawings, wherein the same or similar reference numerals are used to refer to the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the drawings are intended to be illustrative of the invention and are not to be construed as limiting.

The overcharge protection circuit of the power battery, the overcharge protection device of the power battery, the battery management system, and the electric vehicle according to the embodiment of the present invention are described below with reference to the accompanying drawings.

1 is a block diagram of an overcharge protection circuit of a power battery in accordance with an embodiment of the present invention. As shown in FIG. 1, the overcharge protection circuit of the power battery includes a voltage detection circuit 10, a temperature compensation circuit 20, and a control circuit 30.

The voltage detecting circuit 10 is configured to detect the voltage of the power battery Battery. The temperature compensation circuit 20 is connected to the voltage detection circuit 10 and the power battery Battery, respectively, and the temperature compensation circuit 20 is used for temperature compensation of the voltage detection circuit 10. The control circuit 30 is connected to the output end of the voltage detecting circuit 10. The control circuit 30 is configured to control the charging control circuit to be in an off state when the voltage of the battery Battery is greater than a preset voltage threshold to overcharge the power battery.

According to an embodiment of the present invention, as shown in FIG. 2, the voltage detecting circuit 10 may include a Zener diode D1, a first photocoupler U1, a first resistor R1, and a second resistor R2. The cathode of the Zener diode D1 is connected to the anode of the power battery Battery through the temperature compensation circuit 20. The first input end of the first optocoupler U1 is connected to the anode of the Zener diode D1, and the second input end of the first optocoupler U1 is connected to the negative pole of the battery Battery. One end of the first resistor R1 is connected to the first output end of the first photocoupler U1, and the other end of the first resistor R1 is connected to the preset power source VCC. One end of the second resistor R2 is connected to the second output end of the first photocoupler U1, the other end of the second resistor R2 is grounded to GND, and one end of the second resistor R2 is between the second output end of the first photocoupler U1 and the second output end of the first photocoupler U1. The first node J1, the first node J1 is connected to the control circuit 30.

Further, as shown in FIG. 2, the temperature compensation circuit 20 may include a first PTC module PTC1, one end of the first PTC module PTC1 is connected to the cathode of the Zener diode D1, and the other end of the first PTC module PTC1 is connected to the battery of the power battery Battery. Positive phase even.

In the embodiment of the present invention, the first PTC module PTC1 may also be disposed between the second input end of the first photocoupler U1 and the negative pole of the power battery Battery, and the specific setting position may be set according to actual conditions, and the first PTC The module PTC1 may be composed of one or more PTC resistors, or may be composed of a common resistor and a PTC resistor. The PTC resistor may be a positive temperature coefficient thermistor, and may be set according to actual conditions.

Specifically, as shown in FIG. 2, the Zener diode D1 and the first photocoupler U1 have a temperature drift phenomenon, which is greatly affected by temperature. When the input voltage of the front end of the first optocoupler U1 is the same, the conduction voltage drop of the Zener diode D1 and the first optocoupler U1 will increase relative to the normal temperature or high temperature environment in a low temperature environment, and therefore, the first optocoupler U1 flows. The current value at the front end will be lower than the current value at normal temperature or high temperature.

If the front end of the first optocoupler U1 adopts a common resistor R, the current value flowing through the front end of the first optocoupler U1 is IF1=(UB-UD1-U12)/R, where UB is the voltage of the battery of the power battery, and UD1 is the voltage regulator. The conduction voltage drop of the tube D1, U12 is the conduction voltage drop of the first photocoupler U1. In the low temperature environment, the conduction voltage drop UD1 of the Zener diode D1 will rise, and the conduction voltage drop U12 of the first photocoupler U1 will also rise, and the resistance of the ordinary resistor R in the low temperature environment changes very much. It is small or almost constant. Therefore, in the case where the voltage UB of the power battery Battery is constant, the current value IF1 flowing through the front end of the first photocoupler U1 is lowered.

If the ordinary resistor R is replaced by the first PTC module PTC1 (in the embodiment, a single PTC resistor is taken as an example), the current value IF2=(UB-UD1-U12)/RPTC1 flowing through the front end of the first photocoupler U1, wherein RPTC1 is the resistance of the first PTC module PTC1. In the low temperature environment, although the conduction voltage drop UD1 of the Zener diode D1 and the conduction voltage drop U12 of the first photocoupler U1 are both increased, the resistance value RPTC1 of the first PTC module PTC1 is lowered in a low temperature environment. Therefore, the current value IF2>IF1 of the front end of the first photocoupler U1 realizes temperature compensation of the front end of the first photocoupler U1 in a low temperature environment.

In a high temperature environment, the conduction voltage drop of the Zener diode D1 and the first photocoupler U1 becomes smaller, that is, both UD1 and U12 are lowered, and the resistance of the ordinary resistor R in a high temperature environment changes little or almost unchanged. In the case where the voltage UB of the power battery Battery is constant, the current value IF1 flowing through the front end of the first photocoupler U1 rises. If the ordinary resistor R is replaced by the first PTC module PTC1, in the high temperature environment, although the conduction voltage drop UD1 of the Zener diode D1 and the conduction voltage drop U12 of the first photocoupler U1 are both lowered, the first PTC The resistance value RPTC1 of the module PTC1 rises in a high temperature environment. Therefore, the current value IF2 < IF1 of the front end of the first photocoupler U1 realizes temperature compensation of the front end of the first photocoupler U1 in a high temperature environment.

Therefore, in the case where the voltage UB of the battery of the power battery is constant, even if the ambient temperature changes, the current value of the front end of the first photocoupler U1 changes little due to the action of the first PTC module PTC1, thereby realizing the optocoupler. The temperature compensation of the voltage regulator tube improves the detection accuracy of the voltage detection circuit, thereby improving the accuracy and reliability of the overcharge protection of the power battery. Moreover, in a high temperature environment, the resistance of the first PTC module PTC1 will become larger, and the voltage of the battery of the power battery needs to be correspondingly increased to allow current to flow through the front end of the first photocoupler U1, thereby being able to satisfy the battery of the high temperature environment. The charging voltage is increased; in a low temperature environment, the resistance of the first PTC module PTC1 becomes smaller, moving When the voltage of the battery of the battery is relatively small, a current flows through the front end of the first photocoupler U1, so that the charging voltage of the battery of the power battery can be reduced in a low temperature environment. Therefore, the temperature compensation of the first PTC module PTC1 can adjust the overcharge voltage protection point of the power battery, and further improve the accuracy and reliability of the power battery overcharge protection.

According to an embodiment of the present invention, as shown in FIG. 3, the control circuit 30 may include a first MOS transistor Q1, a second MOS transistor Q2, a third MOS transistor Q3, a fifth resistor R5, a sixth resistor R6, and a first capacitor. C1 and the first relay K1. The gate of the first MOS transistor Q1 is connected to the output terminal of the voltage detecting circuit 10, and the source of the first MOS transistor Q1 is connected to the ground GND. The gate of the second MOS transistor Q2 is connected to the drain of the first MOS transistor Q1, the gate of the second MOS transistor Q2 is also connected to the preset power supply VCC through the fifth resistor R5, and the source of the second MOS transistor Q2 is grounded to GND. . The gate of the third MOS transistor Q3 is connected to the drain of the second MOS transistor Q2, the gate of the third MOS transistor Q3 is also connected to the preset power supply VCC through the sixth resistor R6, and the source of the third MOS transistor Q3 is grounded to GND. The source of the third MOS transistor Q3 is also connected to the gate of the third MOS transistor Q3 through the first capacitor C1. One end of the coil K1M of the first relay K1 is connected to the drain of the third MOS transistor Q3, and the other end of the coil K1M of the first relay K1 is connected to the preset power source VCC, and one end of the normally open contact K11 of the first relay K1 is The gate of the second MOS transistor Q2 is connected, the other end of the normally open contact K11 of the first relay K1 is grounded to GND, and both ends of the normally closed contact K12 of the first relay K1 are connected in the charge control loop.

Further, as shown in FIG. 3, the temperature compensation circuit 20 further includes a third PTC module PTC3, one end of the third PTC module PTC3 is connected to the other end of the first resistor R1, and the other end of the third PTC module PTC3 is connected to the preset power source. VCC is connected.

In the embodiment of the present invention, the third PTC module PTC3 may also be disposed between the second output end of the first photocoupler U1 and the ground, and the specific setting position may be set according to actual conditions, and the third PTC module PTC3 may be configured by One or more PTC resistors may be composed of a common resistor and a PTC resistor, and may be set according to actual conditions.

Specifically, as shown in FIG. 3, the voltage UF at the back end of the first photocoupler U1 has a linear relationship with the front end current IF, that is, UF=β*IF, where β is a coefficient, and therefore, whether the control circuit 30 can work or not There is a proportional relationship between the voltage UB of the power battery Battery. In addition, since the control circuit 30 is composed of a MOS transistor and other components, the MOS transistor has a temperature drift phenomenon.

If the back end of the first photocoupler U1 uses a common resistor R, the gate-source voltage of the first MOS transistor Q1

Due to the temperature drift phenomenon of the first MOS transistor Q1 in a low temperature environment, the gate-source voltage Ugs of the first MOS transistor Q1 will rise, and the resistance change of the ordinary resistor R in a low-temperature environment is small or almost constant, so In order to make the first MOS transistor turn on, only β*IF is reduced, that is, only the voltage UB of the battery of the power battery is reduced.

If the ordinary resistor R is replaced by the third PTC module PTC3 (in the embodiment, a single PTC resistor is taken as an example), the gate-source voltage of the first MOS transistor Q1

Wherein, RPTC3 is the resistance of the third PTC module PTC3. In the case of low temperature, since the resistance value RPTC3 of the third PTC module PTC3 is lowered, the gate-source voltage Ugs of the first MOS transistor Q1 is correspondingly increased, so that a UB value consistent with the normal temperature appears to drive the first A MOS transistor Q1 is turned on, thereby realizing compensation for temperature drift caused by the first MOS transistor Q1 in a low temperature environment.

In a high temperature environment, the gate-source voltage Ugs of the first MOS transistor Q1 is lowered. If the back end of the first optocoupler U1 uses a common resistor R, then

It can be seen that when β*IF is smaller than the value at normal temperature, that is, the voltage UB of the battery of the power battery is lower than the voltage at normal temperature, the first MOS transistor Q1 is driven to be turned on. If the ordinary resistor R is replaced by the third PTC module PTC3, in the high temperature environment, since the resistance value RPTC3 of the third PTC module PTC3 rises, the gate-source voltage Ugs of the first MOS transistor Q1 is correspondingly lowered, thus A UB value consistent with the normal temperature occurs, thereby compensating for the temperature drift caused by the first MOS transistor Q1 in a high temperature environment.

In summary, the temperature compensating circuit 20 composed of the first PTC module PTC1 and the third PTC module PTC3 can well solve the voltage stabilizing tube D1, the first optocoupler U1 and the first MOS tube in the voltage detecting circuit 10 and the control circuit 30. The temperature drift problem caused by Q1, so as to realize the automatic adjustment of the voltage threshold of the power battery under different temperature environments, that is, in different temperature environments, only the voltage UB of the power battery Battery reaches the corresponding voltage threshold, the first MOS tube Q1 It will be turned on, so that the first relay K1 operates, which improves the stability of the circuit. In addition, by the temperature compensation of the voltage detecting circuit 10, the charging characteristics of the power battery under different environmental temperatures can also be satisfied, that is, in the low temperature environment, the power battery charging cut-off charging to the full state voltage will be correspondingly lower; in the high temperature environment, the power The battery is turned off to full state voltage will be higher.

In addition, as shown in FIG. 3, when the voltage UB of the power battery Battery reaches the corresponding voltage threshold, the first MOS transistor Q1 is turned on, the second MOS transistor Q2 is turned off, and the third MOS transistor Q3 is turned on, and the first relay K1 is turned on. The coil K1M is energized, the normally closed contact K12 of the first relay K1 is disconnected, and the charging control loop is in an off state, thereby preventing the power battery from being overcharged, and at the same time, the normally open contact K11 of the first relay K1 is closed due to After the normally open contact K11 is closed, the gate voltage of the second MOS transistor Q2 is always zero, and the second MOS transistor Q2 is always in the off state, so that the third MOS transistor Q3 is always in the on state, and the first relay K1 is The coil K1M is always in the power-on state, thereby realizing the self-locking function of the control circuit, effectively preventing the power battery from automatically reducing to the corresponding voltage threshold without the current, and the relay is normally open. The point is broken, the normally closed contact is closed, and the risk of overcharging occurs again.

Therefore, the overcharge protection circuit of the power battery according to the present invention can not only effectively prevent the power battery from being overcharged, but also can effectively prevent the overcharge problem of the power battery by the self-locking function of the control circuit, thereby greatly improving the power battery. Service life.

Further, according to an embodiment of the present invention, as shown in FIG. 3, the power battery overcharge protection circuit may further include a filter delay circuit 40, and the output end of the voltage detection circuit 10 passes through the filter delay circuit 40 and the control circuit. 30 connected, used to filter out the boundary interference signal.

Specifically, as shown in FIG. 3, the filter delay circuit 40 may include an eighth resistor R8 and a second capacitor C2. The one end of the eighth resistor R8 is connected to the output end of the voltage detecting circuit 10. One end of the second capacitor C2 is connected to the other end of the eighth resistor R8, the other end of the second capacitor R2 is grounded to GND, and one end of the second capacitor C2 is between the other end of the eighth resistor R8. There is a second node J2, and the second node J2 is connected to the control circuit 30. The RC filter circuit formed by the eighth resistor R8 and the second capacitor C2 filters out the boundary interference signal, which can effectively improve the stability of the circuit.

According to another embodiment of the present invention, as shown in FIG. 4, the voltage detecting circuit 10 includes a first comparator P1, a third resistor R3, a fourth resistor R4, and a second photocoupler U2. The positive input end of the first comparator P1 is connected to the positive pole of the battery Battery, and the output end of the first comparator P1 is connected to the first preset power source VCC1 through the third resistor R3, and one end of the fourth resistor R4 is first The preset power supply VCC1 is connected, the other end of the fourth resistor R4 is connected to the negative input end of the first comparator P1, and the other end of the fourth resistor R4 is also connected to the negative pole of the power battery Battery through the temperature compensation circuit 20. The first input end of the second optocoupler U2 is connected to the output end of the first comparator P1, the second input end of the second optocoupler U2 is connected to the first ground end GND1, and the first output end of the second optocoupler U2 is The second preset power source VCC2 is connected, and the second output end of the second photocoupler U2 is connected to the control circuit 30.

Further, as shown in FIG. 4, the temperature compensation circuit 20 includes a second PTC module PTC2, one end of which is connected to the other end of the fourth resistor R4 and the negative input end of the first comparator P1, respectively. The other end of the PTC module PTC2 is connected to the negative pole of the battery of the power battery. The second PTC module PTC2 may be composed of one or more PTC resistors, or may be composed of a common resistor and a PTC resistor, and may be set according to actual conditions.

Specifically, as shown in FIG. 4, the fourth resistor R4 and the second PTC module PTC2 are connected in series, and the first reference voltage is obtained by dividing the second PTC module PTC2. When the first preset power source VCC1 is constant, in the high temperature environment, the resistance value of the second PTC module PTC2 will become larger, and the first reference voltage will be correspondingly higher, thereby being able to satisfy the increase of the charging voltage of the battery of the power battery under the high temperature environment. In the low temperature environment, the resistance of the second PTC module PTC2 will become smaller, and the first reference voltage will be correspondingly smaller, thereby being able to satisfy the situation in which the charging voltage of the battery of the power battery is lowered in a low temperature environment. Therefore, by the temperature compensation of the PTC module in the temperature compensation circuit 20, the first reference voltage can be matched with the overcharge voltage protection point corresponding to the actual power battery at the current ambient temperature, thereby improving the detection accuracy of the voltage detection circuit. In turn, the accuracy and reliability of the overcharge protection of the power battery can be improved. In addition, the PTC module may be disposed at the first input end or the second input end of the second optocoupler U2 to perform temperature compensation on the second optocoupler, which is not detailed herein.

According to an embodiment of the present invention, as shown in FIG. 5, the control circuit 30 may include a seventh resistor R7, a fourth MOS transistor Q4, and a second relay K2. Wherein, one end of the seventh resistor R7 is connected to the output end of the voltage detecting circuit 10, the gate of the fourth MOS transistor Q4 is connected to the other end of the seventh resistor R7, and the source of the fourth MOS transistor Q4 and the second ground GND2 Connected, the drain of the fourth MOS transistor is connected to one end of the seventh resistor R7. One end of the coil K2M of the second relay K2 is connected to the drain of the fourth MOS transistor Q4, one end of the seventh resistor R7, and one end of the normally open contact K21 of the second relay K2, and the other end of the coil K2M of the second relay K2 Connected to the other end of the normally open contact K21 of the second preset power source VCC2 and the second relay K2, both ends of the normally closed contact K22 of the second relay K2 are connected in the charge control loop.

Specifically, as shown in FIG. 5, the positive input end of the first comparator P1 is connected to the positive pole of the battery Battery to detect the voltage of the battery of the power battery in real time, while the negative input of the first comparator P1 obtains the first reference. Voltage.

During the battery charging process of the power battery, when the power battery Battery does not overcharge, the voltage of the positive input terminal of the first comparator P1 is lower than the voltage of the negative input terminal, and the first comparator P1 outputs a low level signal, and the second optical coupler There is no current flowing through the front end of the U2. At this time, the voltage of the second preset power supply VCC2 is mainly applied between the first output end and the second output end of the second photocoupler U2, and the fourth MOS transistor Q4 is in the off state. No current flows through the coil K2M of the relay K2, the second relay K2 does not work, the charging control circuit is in a closed state, and the battery of the power battery is normally charged.

When the power battery Battery is overcharged, the voltage of the positive input terminal of the first comparator P1 is higher than the voltage of the negative input terminal, and the first comparator P1 outputs a high level signal. Under the action of the high level, the second photocoupler U2 is driven, the voltage between the first output end and the second output end of the second photocoupler U2 is almost zero, and the voltage of the second preset power source VCC2 is all applied On one end of the seventh resistor R7, at this time, the fourth MOS transistor Q4 is in an on state, a current flows through the coil K2M of the second relay K2, the normally closed contact K21 of the second relay K2 is turned off, and the charging control circuit is disconnected. On, the battery of the power battery stops charging, thereby achieving overcharge protection of the power battery. At the same time, the normally open contact K21 of the second relay K2 is closed, because one end of the normally open contact K21 of the second relay K2 and the second optical coupler U2 The second output end is connected, and the other end is connected to the second preset power source VCC2. Therefore, after the normally open contact K21 is closed, the current of the second preset power source VCC2 flows to the second photocoupler U2 through the normally open contact K21. The second output end, so that even if no current flows through the front end of the second photocoupler U2, the fourth MOS transistor Q4 is still in a conducting state, thereby realizing the self-locking function of the control circuit, effectively preventing the power battery from reaching full charge, without In the case of current, the voltage of the power battery is automatically After falling off the first reference voltage, the normally open contact of the relay is opened, the normally closed contact is closed, and the risk of overcharging occurs again. In addition, a PTC module may be disposed at the first output end or the second output end of the second photocoupler U2 to perform temperature compensation on the fourth MOS transistor Q4, which is not detailed herein.

Further, as shown in FIG. 5, the above-mentioned overcharge protection circuit of the power battery may further include a filter circuit 50 composed of a ninth resistor R9 and a third capacitor C3, wherein one end of the ninth resistor R9 and the fourth MOS transistor The gate of Q4 is connected, the other end of the ninth resistor R9 is connected to the source of the fourth MOS transistor Q4, and the third capacitor C3 is connected in parallel with the ninth resistor R9 to eliminate external interference, so that the control of the circuit is more stable.

Further, as shown in FIG. 4 and FIG. 5, the overcharge protection circuit of the power battery may further include a DC/DC isolated power supply module 60, and the DC/DC isolated power supply module 60 is configured to convert the second preset power supply VCC2. It is a first preset power source VCC1, and isolates the first preset power source VCC1 and the second preset power source VCC2.

Specifically, the main function of the DC/DC isolated power module 60 is to supply power to the first comparator P1 and the third resistor R3, while providing a first reference voltage for the negative input terminal of the first comparator P1, and also for the power battery. The high voltage zone and the low voltage zone of the control circuit are isolated to further improve the safety of the system.

In addition, it should be noted that, in practical applications, the first relay K1 and the second relay K2 may be replaced by other methods, for example, a normally-on relay and a normally-closed relay may be connected in series, or a single-pole double-throw relay may be used. Specifically, it can be selected according to the actual situation. From the perspective of safety and the area of the PCB board occupied, it is preferred to employ a relay having a set of independent normally open contacts and a set of normally closed contacts as shown in FIGS. 3 and 5.

Moreover, the circuits shown in FIG. 3 and FIG. 5 are only examples, and the circuit shown in FIG. 3 and FIG. 5 can also be simply replaced and modified. For example, the control circuit in FIG. 3 can be applied to FIG. 5. And setting the PTC module at the first output end of the second optocoupler of FIG. 5 for temperature compensation, or applying the control circuit shown in FIG. 5 to FIG. 3, how the specific circuit is replaced or deformed, here is not Make restrictions.

In summary, according to the overcharge protection circuit of the power battery of the present invention, the voltage of the power battery is detected by the voltage detection circuit, and the voltage detection circuit is temperature compensated by the temperature compensation circuit, and the voltage of the control circuit in the power battery is greater than the preset. When the voltage threshold is used, the charging control loop is controlled to overcharge the power battery, so that the power battery can be overcharged without software logic, and the temperature compensation circuit compensates for the temperature drift of the voltage detection circuit. The fastness, accuracy and reliability of the overcharge protection, and the self-locking function of the control circuit, effectively prevent the repeated overcharging of the power battery and improve the service life of the power battery.

6 is a schematic diagram of an overcharge protection device for a power battery according to an embodiment of the present invention. As shown in FIG. 6, the overcharge protection device 200 of the power battery includes the overcharge protection circuit 100 of the power battery described above.

Specifically, as shown in FIG. 6, the overcharge protection circuit 100 and the protection relay Kb described above may be integrated in the overcharge protection device 200, and the device may be connected in series in the power battery pack 300. The battery voltage is detected by the overcharge protection circuit 100. When the battery voltage exceeds the protection threshold of the hardware circuit design, the protection relay Kb is directly disconnected, thereby achieving overcharge protection for the power battery pack 300. Moreover, the entire overcharge protection is realized by the hardware circuit, no software is needed for judgment, and has a temperature compensation function, which effectively improves the speed, accuracy and reliability of the overcharge protection.

Therefore, the overcharge protection device of the power battery of the present invention can directly drive the protection relay when the voltage of the power battery is greater than the preset voltage threshold by the above-mentioned overcharge protection circuit, without software logic judgment, and through the temperature compensation circuit Compensation for temperature drift of the voltage detection circuit improves the speed, accuracy and reliability of overcharge protection.

7 is a schematic diagram of a battery management system in accordance with one embodiment of the present invention. As shown in FIG. 7, the battery management system 400 can include the power battery overcharge protection device 200 described above.

Specifically, as shown in FIG. 7 , the power battery pack 300 can be overcharged by the existing battery management system 400 together with the overcharge protection device 200 described above, wherein the existing battery management system 400 can be used as the first The primary safety protection system uses the overcharge protection device 200 of the embodiment of the present invention as a second-level safety protection system, thereby further reducing the risk of overcharging of the power battery pack 300.

Specifically, as shown in FIG. 7, the overcharge protection device 200 can be integrated in the interior of the power battery pack 300, and the voltage across the battery can be directly obtained through the overcharge protection circuit 100. When the voltage across the battery exceeds the protection of the hardware circuit setting. At the threshold, the protection relay Kb is directly disconnected, thereby disconnecting the entire power charging circuit, thereby effectively avoiding the risk of battery overcharging due to failure of the battery management system.

Therefore, the battery management system of the present invention can directly drive the protection relay when the voltage of the power battery is greater than the preset voltage threshold by the overcharge protection device of the power battery, without software logic determination, and temperature The compensation circuit compensates for the temperature drift of the voltage detection circuit, improving the speed, accuracy and reliability of the overcharge protection.

Further, an embodiment of the present invention also proposes an electric vehicle including the above-described power battery overcharge protection device.

In the electric vehicle of the present invention, the overcharge protection device of the power battery can directly control the charging control loop when the voltage of the power battery is greater than the preset voltage threshold, without software logic judgment, and the voltage detection by the temperature compensation circuit The temperature drift of the circuit is compensated, which improves the speed, accuracy and reliability of overcharge protection.

In the description of the present invention, it is to be understood that the terms "first" and "second" are used for descriptive purposes only and are not to be construed as indicating or implying a relative importance or implicitly indicating the number of technical features indicated. Thus, features defining "first" or "second" may include at least one of the features, either explicitly or implicitly. In the description of the present invention, the meaning of "a plurality" is at least two, such as two, three, etc., unless specifically defined otherwise.

In the present invention, the terms "installation", "connected", "connected", "fixed" and the like shall be understood broadly, and may be either a fixed connection or a detachable connection, unless explicitly stated and defined otherwise. , or integrated; can be mechanical or electrical connection; can be directly connected, or indirectly connected through an intermediate medium, can be the internal communication of two elements or the interaction of two elements, unless otherwise specified Limited. For those skilled in the art, the specific meanings of the above terms in the present invention can be understood on a case-by-case basis.

In the description of the present specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" and the like means a specific feature described in connection with the embodiment or example. A structure, material or feature is included in at least one embodiment or example of the invention. In the present specification, the schematic representation of the above terms is not necessarily directed to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in a suitable manner in any one or more embodiments or examples. In addition, various embodiments or examples described in the specification, as well as features of various embodiments or examples, may be combined and combined. Although the embodiments of the present invention have been shown and described, it is understood that the above-described embodiments are illustrative and are not to be construed as limiting the scope of the invention. The embodiments are subject to variations, modifications, substitutions and variations.

Claims

An overcharge protection circuit for a power battery, comprising:

a voltage detecting circuit, wherein the voltage detecting circuit is configured to detect a voltage of the power battery;

a temperature compensation circuit, wherein the temperature compensation circuit is respectively connected to the voltage detection circuit and the power battery, and the temperature compensation circuit is configured to perform temperature compensation on the voltage detection circuit;

a control circuit, the control circuit is connected to an output end of the voltage detecting circuit, and the control circuit is configured to control the charging control loop to be in an off state when the voltage of the power battery is greater than a preset voltage threshold, The power battery is overcharged.
The overcharge protection circuit of claim 1 wherein said voltage detection circuit comprises:

a Zener tube, the cathode of the Zener tube is connected to the anode of the power battery through the temperature compensation circuit;

a first optocoupler, a first input end of the first optocoupler is connected to an anode of the voltage regulator tube, and a second input end of the first optocoupler is connected to a negative pole of the power battery;

a first resistor, one end of the first resistor is connected to the first output end of the first optocoupler, and the other end of the first resistor is connected to a preset power source;

a second resistor, one end of the second resistor is connected to the second output end of the first optocoupler, the other end of the second resistor is grounded, and one end of the second resistor is coupled to the first optocoupler There is a first node between the second outputs, and the first node is connected to the control circuit.
The overcharge protection circuit of claim 2, wherein the temperature compensation circuit comprises:

The first PTC module has one end connected to the cathode of the Zener tube and the other end of the first PTC module connected to the anode of the power battery.
The overcharge protection circuit of claim 1 , wherein the voltage detection circuit comprises: a first comparator, a third resistor, a fourth resistor, and a second photocoupler, wherein

The positive input end of the first comparator is connected to the positive pole of the power battery, and the output end of the first comparator is connected to the first preset power source through a third resistor;

One end of the fourth resistor is connected to the first preset power source, the other end of the fourth resistor is connected to a negative input end of the first comparator, and the other end of the fourth resistor is further a temperature compensation circuit is connected to the negative pole of the power battery;

a first input end of the second optocoupler is connected to an output end of the first comparator, a second input end of the second optocoupler is connected to a first ground end, and a first end of the second optocoupler The output terminal is connected to the second preset power source, and the second output terminal of the second photocoupler is connected to the control circuit.
The overcharge protection circuit of claim 4, wherein the temperature compensation circuit comprises:

a second PTC module, one end of the second PTC module is respectively connected to the other end of the fourth resistor, the negative input end of the first comparator, and the other end of the second PTC module is connected to the power battery The negative poles are connected.
The overcharge protection circuit according to claim 2 or 3, wherein the control circuit comprises: a first MOS transistor, a second MOS transistor, a third MOS transistor, a fifth resistor, a sixth resistor, and a first capacitor And a first relay, wherein a gate of the first MOS transistor is connected to an output end of the voltage detecting circuit, and a source of the first MOS transistor is grounded;

a gate of the second MOS transistor is connected to a drain of the first MOS transistor, and a gate of the second MOS transistor is further connected to a preset power source through a fifth resistor, a source of the second MOS transistor Pick up the ground;

a gate of the third MOS transistor is connected to a drain of the second MOS transistor, and a gate of the third MOS transistor is further connected to the preset power source through a sixth resistor, the third MOS transistor The source is connected to the ground, and the source of the third MOS transistor is further connected to the gate of the third MOS transistor through a first capacitor;

One end of the coil of the first relay is connected to the drain of the third MOS tube, and the other end of the coil of the first relay is connected to the preset power source, the normally open contact of the first relay One end is connected to the gate of the second MOS tube, the other end of the normally open contact of the first relay is connected to the ground, and both ends of the normally closed contact of the first relay are connected to the charging control In the loop.
The overcharge protection circuit of claim 6, wherein the temperature compensation circuit further comprises:

a third PTC module, one end of the third PTC module is connected to the other end of the first resistor, and the other end of the third PTC module is connected to the preset power source.
The overcharge protection circuit according to claim 4 or 5, wherein the control circuit comprises:

a seventh resistor, one end of the seventh resistor is connected to an output end of the voltage detecting circuit;

a fourth MOS transistor, a gate of the fourth MOS transistor is connected to the other end of the seventh resistor, a source of the fourth MOS transistor is connected to a second ground, and a drain of the fourth MOS transistor Connected to one end of the seventh resistor;

a second relay, one end of the coil of the second relay is respectively connected to a drain of the fourth MOS transistor, one end of the seventh resistor, and one end of a normally open contact of the second relay, respectively The other ends of the coils of the two relays are respectively connected to the second preset power source and the other end of the normally open contact of the second relay, and both ends of the normally closed contact of the second relay are connected to the charging control loop in.
An overcharge protection device for a power battery, characterized by comprising an overcharge protection circuit for a power battery according to any one of claims 1-8.
A battery management system comprising the overcharge protection device of the power battery according to claim 9.
An electric vehicle characterized by comprising the overcharge protection device of the power battery according to claim 9.