WO2017201957A1

WO2017201957A1 - Protective device and method for bms power source loop, and electric vehicle

Info

Publication number: WO2017201957A1
Application number: PCT/CN2016/103125
Authority: WO
Inventors: 曹东林; 代康伟; 唐磊
Original assignee: 北京新能源汽车股份有限公司
Priority date: 2016-05-24
Filing date: 2016-10-24
Publication date: 2017-11-30
Also published as: CN105870885A; CN105870885B

Abstract

Disclosed are a protective device and method for a BMS power source loop, and an electric vehicle. The device comprises: a PTC thermistor (10), wherein the PTC thermistor is connected in series in a BMS power source loop; a controllable switch (20), wherein the controllable switch is connected in series in the BMS power source loop; a temperature detection unit (30), wherein the temperature detection unit is used for detecting the temperature at a position where the PTC thermistor is located; and a safety auxiliary control unit (40), wherein the safety auxiliary control unit is respectively connected to the controllable switch and the temperature detection unit, and when determining that the temperature at the position where the PTC thermistor is located is greater than or equal to a pre-set temperature, the safety auxiliary control unit controls the disconnection of the controllable switch, so as to cut off the BMS power source loop. The protective device of the BMS power source loop can significantly improve the safety and reliability of the BMS power source loop.

Description

BMS power circuit protection device, method and electric vehicle

Cross-reference to related applications

The present application claims the priority of the Chinese Patent Application No. "201610349006.9", filed on May 24, 2016 by the Beijing New Energy Automobile Co., Ltd., entitled "BMS Power Circuit Protection Device, Method, and Electric Vehicle."

Technical field

The present invention relates to the field of electric vehicle technology, and in particular, to a protection device for a BMS power circuit, a method for protecting a BMS power circuit, and an electric vehicle.

Background technique

Most of the vehicle energy systems for electric vehicles are lithium-ion battery systems. Lithium-ion batteries have the advantages of long service life, high monomer energy and flexible combination. However, due to their high energy and poor stability, the requirements for safety in monitoring and management are relatively high. Therefore, BMS (Battery Management System) occupies a very important position in electric vehicles.

Among them, the short circuit condition of the BMS power supply circuit occurs. For this reason, a PTC (Positive Temperature Coefficient) thermistor is often connected to the BMS power supply circuit. As shown in Fig. 1, when the temperature T exceeds a certain value T1, when between T1 and T2, the resistance R of the PTC thermistor increases stepwise with increasing temperature, so that a short circuit occurs. The PTC thermistor can act as a current limiter.

However, if the actual current of the PTC thermistor exceeds its rated current for a long time, it will reduce the service life of the PTC thermistor, and may even invalidate the PTC thermistor in an unrecoverable high resistance state. That is, the current limiting effect on the BMS power circuit is lost. Therefore, the safety of the current BMS power supply circuit needs to be improved.

Summary of the invention

The present invention aims to solve at least one of the technical problems in the above-mentioned techniques to some extent. To this end, an object of the present invention is to provide a protection device for a BMS power supply loop, which can greatly improve the safety and reliability of the BMS power supply loop.

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

A third object of the present invention is to provide a method of protecting a BMS power supply loop.

In order to achieve the above object, a first aspect of the present invention provides a protection device for a BMS power supply loop, in which a first DC/DC converter is disposed in the BMS power supply loop, and the first DC/DC converter is used to The input first direct current is converted into a second direct current to supply the BMS, and the protection device comprises: a PTC thermistor, the PTC a thermistor is connected in series in the BMS power circuit; a controllable switch, the controllable switch is connected in series in the BMS power circuit; a temperature detecting unit, the temperature detecting unit is configured to detect the PTC thermistor a temperature at a location; a safety assist control unit, the safety assist control unit being respectively connected to the controllable switch and the temperature detecting unit, wherein the safety assist control unit determines a position of the PTC thermistor The controllable switch is turned off when the temperature is greater than or equal to the preset temperature to cut off the BMS power circuit.

The protection device of the BMS power supply circuit according to the embodiment of the present invention detects the temperature of the position of the PTC thermistor, and controls the controllable switch to open to cut off the power supply circuit when the temperature is too high, and on the other hand, an overcurrent occurs. The BMS power supply circuit is directly protected, and on the other hand, the PTC thermistor is prevented from being overcurrent for a long period of time, the service life of the PTC thermistor can be prolonged, and the reliability of the PTC thermistor function can be improved. This greatly improves the safety of the BMS power circuit.

In addition, the protection device of the BMS power supply loop proposed according to the above embodiment of the present invention may further have the following additional technical features:

Specifically, the first direct current includes a positive output terminal and a negative output terminal, and the PTC thermistor is connected between the positive output terminal and the first input end of the first DC/DC converter.

According to an embodiment of the invention, the protection device of the BMS power circuit further includes a transient suppression diode, the transient suppression diode being connected in parallel between the positive output terminal and the negative output terminal, the transient A suppression diode is used to prevent the PTC thermistor from being short-circuited by a breakdown.

According to an embodiment of the invention, the controllable switch is a relay, and a switch of the relay is connected between the negative output terminal and a second input end of the first DC/DC converter, the relay The control coil in the middle is controlled by the safety assist control unit.

According to an embodiment of the present invention, the protection device of the BMS power circuit further includes a second DC/DC converter, and the first input end of the second DC/DC converter is connected to the positive output terminal. a second input end of the second DC/DC converter is connected to the negative output terminal, and a first output end and a second output end of the second DC/DC converter are respectively connected to the safety assist control unit, The second DC/DC converter is configured to convert the first direct current to a third direct current to supply the safety assist control unit, wherein a voltage of the third direct current is less than a voltage of the first direct current.

According to an embodiment of the invention, the temperature detecting unit comprises: an NTC (Negative Temperature Coefficient) thermistor, one end of the NTC thermistor is grounded, and the NTC thermistor is used for detecting a temperature at a PCB (Printed Circuit Board) board on which the PTC thermistor is located; a voltage dividing resistor connected to the other end of the NTC thermistor, the partial pressure The other end of the resistor is connected to the first output of the second DC/DC converter, the node between the voltage dividing resistor and the other end of the NTC thermistor and the AD of the safety assist control unit The sampling ends are connected.

In order to achieve the above object, an embodiment of the second aspect of the present invention provides an electric vehicle, and an electric vehicle according to an embodiment of the present invention includes a protection device for a BMS power supply loop proposed by the above embodiment of the present invention.

According to the electric vehicle of the embodiment of the invention, on the one hand, the BMS power supply circuit can be directly protected when an overcurrent occurs, and on the other hand, the PTC thermistor in the BMS power supply circuit can be prevented from being overcurrent for a long time, which can be extended. The life of the PTC thermistor and the reliability of the PTC thermistor function greatly improve the safety of the BMS power circuit.

In order to achieve the above object, a third aspect of the present invention provides a method for protecting a BMS power supply loop, wherein the BMS power supply circuit is provided with a first DC/DC converter, a PTC thermistor, and a controllable switch. The first DC/DC converter is configured to convert the input first direct current into the second direct current to supply the BMS, and the protection method includes the steps of: detecting a temperature at a position where the PTC thermistor is located; Whether the temperature of the position where the PTC thermistor is located is greater than or equal to a preset temperature; if the temperature of the position where the PTC thermistor is located is greater than or equal to the preset temperature, determining that the PTC thermistor is in an open circuit a state and controlling the controllable switch to open to shut off the BMS power circuit.

According to the protection method of the BMS power supply loop according to the embodiment of the present invention, by detecting the temperature of the position of the PTC thermistor, when the temperature is too high, the controllable switch is turned off to cut off the power supply circuit, and on the other hand, an overcurrent may occur. The BMS power supply circuit is directly protected, and on the other hand, the PTC thermistor is prevented from being overcurrent for a long period of time, the service life of the PTC thermistor can be prolonged, and the reliability of the PTC thermistor function can be improved. This greatly improves the safety of the BMS power circuit.

In addition, the protection method of the BMS power supply loop proposed according to the above embodiment of the present invention may further have the following additional technical features:

According to an embodiment of the invention, the first direct current comprises a positive output and a negative output, the PTC thermistor being connected at the positive output and the first input of the first DC/DC converter Between the terminals, and a transient suppression diode is further connected between the positive output terminal and the negative output terminal, and the transient suppression diode is used to prevent the PTC thermistor from being short-circuited by a breakdown.

Further, when the PTC thermistor is in an open state or in a short circuit state, an alarm prompt is also issued.

DRAWINGS

Figure 1 is a schematic diagram showing the resistance characteristics of a PTC thermistor;

2 is a circuit diagram of a BMS power supply loop in accordance with one embodiment of the present invention;

3 is a circuit diagram of a BMS power supply circuit in accordance with another embodiment of the present invention;

4 is a flow chart of a method of protecting a BMS power supply loop in accordance with an 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 protection device, method and electric vehicle of the BMS power supply loop of the embodiment of the present invention will be described below with reference to the accompanying drawings.

2 is a circuit diagram of a BMS power supply loop in accordance with one embodiment of the present invention.

As shown in FIG. 2, a first DC/DC converter may be disposed in the BMS power supply circuit, and the first DC/DC converter is configured to convert the input first direct current into the second direct current to supply the BMS. The protection device of the BMS power supply loop of the embodiment of the invention comprises: a PTC thermistor 10, a controllable switch 20, a temperature detecting unit 30 and a safety assist control unit 40.

Wherein, the PTC thermistor 10 is connected in series in the BMS power supply loop, the controllable switch 20 is connected in series in the BMS power supply loop, and the temperature detecting unit 30 is configured to detect the temperature of the position of the PTC thermistor, and the safety assist control unit 40 respectively Connected to the controllable switch 20 and the temperature detecting unit 30, the safety assist control unit 40 controls the controllable switch 20 to open when the temperature of the position where the PTC thermistor 10 is located is greater than or equal to the preset temperature to cut off the BMS power circuit.

3 is a circuit diagram of a BMS power supply circuit according to another embodiment of the present invention. As shown in FIG. 3, the first direct current includes a positive output terminal and a negative output terminal, and the voltage can be 12V, and the PTC thermistor 10 can be connected to the positive electrode. The output is between the first input of the first DC/DC converter.

In an embodiment of the invention, the controllable switch 20 can be a relay, and the switch in the relay can be connected between the negative output terminal and the second input end of the first DC/DC converter, and the control coil in the relay can be The safety assist control unit 40 is connected and I/O control is performed by the safety assist control unit 40.

As shown in FIG. 3, the protection device of the BMS power supply loop of the embodiment of the present invention may further include a second DC/DC converter, and the first input end of the second DC/DC converter is connected to the positive output terminal, and the second DC/ The second input end of the DC converter is connected to the negative output terminal, and the first output end and the second output end of the second DC/DC converter are respectively connected to the safety assist control unit 40, and the second DC/DC converter is used for A direct current is converted to a third direct current to supply a safety assist control unit, wherein the voltage of the third direct current is less than the voltage of the first direct current. In one embodiment of the invention, the second DC/DC converter can convert the first direct current of 12V to the third direct current of 3.3V to supply the safety assist control unit 40. To ensure circuit safety, a fuse Fuse can also be connected in series between the first input of the second DC/DC converter and the positive output of the first direct current.

In an embodiment of the present invention, the temperature detecting unit 30 may include an NTC thermistor and a voltage dividing resistor R0. One end of the NTC thermistor is grounded, and the NTC thermistor is used to detect the PCB where the PTC thermistor 10 is located. The temperature at the board, the voltage dividing resistor R0 is connected to the other end of the NTC thermistor, and the other end of the voltage dividing resistor R0 is connected to the first output of the second DC/DC converter, and the voltage dividing resistor R0 and NTC are connected. A node between the other end of the resistor is connected to the AD sampling end of the safety assist control unit 40.

Therefore, the safety assist control unit 40 can determine the resistance change of the NTC thermistor according to the electrical signal acquired by the AD sampling end, and then can acquire the PTC thermistor 10 in combination with the temperature characteristic of the NTC thermistor. The temperature of the location. It should be understood that when the actual current of the PTC thermistor 10 is large, the temperature at the position where the PTC thermistor 10 is placed rises, and the temperature at the position where the PTC thermistor 10 is placed rises to a preset temperature. At the time, if the circuit continues to be energized and the temperature continues to rise, it is highly probable that the PTC thermistor 10 will fail in an unrecoverable high resistance state. When the temperature of the position where the PTC thermistor 10 is located is determined to be greater than or equal to the preset temperature, the safety assist control unit 40 can control the relay switch to be turned off through the I/O control port, thereby cutting off the BMS power supply circuit. In an embodiment of the invention, the specific value of the preset temperature can be obtained experimentally.

In addition, as shown in FIG. 3, the protection device of the BMS power circuit of the embodiment of the present invention may further include a transient suppression diode TVS, and the transient suppression diode TVS is connected in parallel between the positive output terminal and the negative output terminal of the first direct current. The state suppression diode TVS can be used to prevent the PTC thermistor 10 from being short-circuited by a breakdown. Thereby, the breakdown failure of the PTC thermistor 10 due to power surges, large pulses, electrostatic discharge, and switching power supply noise occurring in the circuit can be prevented, and the reliability of the PTC thermistor 10 is further improved.

The PTC thermistor 10 can be equivalent to being in an open state when exhibiting an unrecoverable high resistance state, and can be equivalent to being in a short circuit state when being broken down, and the PTC thermistor 10 will fail in both of the above states. In the embodiment of the present invention, if the PTC thermistor 10 is in an open state or in a short circuit state due to failure of protection of the protection device, an alarm prompt may be issued by the alarm device to issue a reminder when the PTC thermistor 10 fails.

Corresponding to the above embodiment, the present invention also proposes an electric vehicle.

The electric vehicle of the embodiment of the present invention includes the protection device of the BMS power supply circuit according to the above-mentioned embodiments of the present invention. For the specific implementation manners, reference may be made to the foregoing embodiments. To avoid redundancy, details are not described herein.

Corresponding to the above embodiments, the present invention also provides a method for protecting a BMS power supply loop.

Wherein, as shown in FIG. 2, a first DC/DC converter, a PTC thermistor and a BMS power supply circuit are disposed. A controllable switch, the first DC/DC converter is configured to convert the input first direct current into a second direct current to supply the BMS.

As shown in FIG. 4, a method for protecting a BMS power supply loop according to an embodiment of the present invention includes the following steps:

S401. Detect a temperature at a position where the PTC thermistor is located.

In one embodiment of the present invention, as shown in FIG. 3, the temperature at which the PTC thermistor is located can be detected by the NTC thermistor and the voltage dividing resistor R0. Specifically, one end of the NTC thermistor can be grounded, the voltage dividing resistor R0 is connected to the other end of the NTC thermistor, and the other end of the voltage dividing resistor R0 is connected to the first output end of the second DC/DC converter. The node between the voltage dividing resistor R0 and the other end of the NTC thermistor is connected to the AD sampling end of the safety assist control unit. Therefore, the safety assist control unit can determine the resistance change of the NTC thermistor according to the electrical signal acquired by the AD sampling end, and then combine the temperature characteristics of the NTC thermistor to obtain the position of the PTC thermistor. temperature.

S402. Determine whether the temperature of the position where the PTC thermistor is located is greater than or equal to a preset temperature.

S403. If the temperature of the PTC thermistor is greater than or equal to the preset temperature, determine that the PTC thermistor is in an open state, and control the controllable switch to open to cut off the BMS power circuit.

It should be understood that when the actual current of the PTC thermistor is large, the temperature at which the PTC thermistor is placed will rise, when the temperature at the position of the PTC thermistor rises to a preset temperature, if As the circuit continues to energize and the temperature continues to rise, it is highly probable that the PTC thermistor will fail in an unrecoverable, high-impedance state. When the safety assist control unit determines that the temperature of the PTC thermistor is greater than or equal to the preset temperature, the relay switch can be turned off by the I/O control port, thereby cutting off the BMS power supply loop. In an embodiment of the invention, the specific value of the preset temperature can be obtained experimentally.

In addition, as shown in FIG. 3, the first direct current may include a positive output terminal and a negative output terminal, and the PTC thermistor is connected between the positive output terminal and the first input end of the first DC/DC converter, and the positive output is A transient suppression diode is also connected between the terminal and the negative output terminal, and the transient suppression diode is used to prevent the PTC thermistor from being short-circuited by a breakdown. Therefore, the PTC thermistor can be prevented from being broken by the power surge, large pulse, electrostatic discharge, and switching power supply noise occurring in the circuit, thereby further improving the reliability of the PTC thermistor.

The PTC thermistor can be equivalent to being in an open state when exhibiting an unrecoverable high-impedance state, and can be equivalent to being in a short-circuit state when being broken down, and the PTC thermistor fails in both of the above states. In an embodiment of the invention, if the PTC thermistor is in an open state or in a short circuit condition due to protection failure of the protection device, an alarm prompt may be issued to alert when the PTC thermistor fails.

According to the protection method of the BMS power supply loop according to the embodiment of the present invention, by detecting the temperature of the position of the PTC thermistor, when the temperature is too high, the controllable switch is turned off to cut off the power supply circuit, and on the other hand, an overcurrent may occur. The BMS power supply circuit is directly protected, and on the other hand, the PTC thermistor is prevented from being overcurrent for a long period of time, the service life of the PTC thermistor can be prolonged, and the reliability of the PTC thermistor function can be improved. Thus large Greatly improve the safety of the BMS power circuit.

In the description of the present invention, it is to be understood that the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", " Rear, Left, Right, Vertical, Horizontal, Top, Bottom, Inner, Out, Clockwise, Counterclockwise, Axial The orientation or positional relationship of the "radial", "circumferential" and the like is based on the orientation or positional relationship shown in the drawings, and is merely for the convenience of describing the present invention and simplifying the description, and does not indicate or imply the indicated device or The elements must have a particular orientation, are constructed and operated in a particular orientation and are therefore not to be construed as limiting.

Moreover, 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" and "second" may include one or more of the features either explicitly or implicitly. In the description of the present invention, the meaning of "a plurality" is two or more unless specifically and 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 connection, or can be electrical connection; can be directly connected, or can be indirectly connected through an intermediate medium, can be the internal communication of two elements or the interaction of two elements. 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 present invention, the first feature "on" or "under" the second feature may be a direct contact of the first and second features, or the first and second features may be indirectly through an intermediate medium, unless otherwise explicitly stated and defined. contact. Moreover, the first feature "above", "above" and "above" the second feature may be that the first feature is directly above or above the second feature, or merely that the first feature level is higher than the second feature. The first feature "below", "below" and "below" the second feature may be that the first feature is directly below or obliquely below the second feature, or merely that the first feature level is less than the second feature.

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

A protection device for a BMS power supply loop, wherein a first DC/DC converter is provided in the BMS power supply loop, and the first DC/DC converter is configured to convert the input first direct current into a second direct current To supply the BMS, the protection device includes:

a PTC thermistor, the PTC thermistor being connected in series in the BMS power circuit;

a controllable switch, the controllable switch being connected in series in the BMS power circuit;

a temperature detecting unit, configured to detect a temperature at a position where the PTC thermistor is located;

a safety assist control unit, wherein the safety assist control unit is respectively connected to the controllable switch and the temperature detecting unit, and the safety assist control unit determines that the temperature of the PTC thermistor is greater than or equal to a preset The controllable switch is turned off at temperature to shut off the BMS power circuit.
The protection device for a BMS power supply circuit according to claim 1, wherein said first direct current comprises a positive output terminal and a negative output terminal, said PTC thermistor being connected to said positive output terminal and said first Between the first input of a DC/DC converter.
A protection device for a BMS power supply circuit according to claim 2, further comprising a transient suppression diode, said transient suppression diode being connected in parallel between said positive output terminal and said negative output terminal, said instant The state suppression diode is used to prevent the PTC thermistor from being short-circuited by a breakdown.
A protection device for a BMS power supply circuit according to claim 2, wherein said controllable switch is a relay, and a switch of said relay is connected to said negative output terminal and said first DC/DC converter Between the second inputs, the control coils in the relay are controlled by the safety assist control unit.
The protection device for a BMS power supply circuit according to claim 2, further comprising a second DC/DC converter, wherein the first input end of the second DC/DC converter is connected to the positive output terminal, a second input end of the second DC/DC converter is connected to the negative output terminal, and a first output end and a second output end of the second DC/DC converter are respectively connected to the safety auxiliary control unit The second DC/DC converter is configured to convert the first direct current to a third direct current to supply the safety assist control unit, wherein a voltage of the third direct current is less than a voltage of the first direct current.
The protection device for a BMS power supply circuit according to claim 5, wherein the temperature detecting unit comprises:

An NTC thermistor, one end of the NTC thermistor is grounded, and the NTC thermistor is used to detect a temperature at a PCB board where the PTC thermistor is located;

a voltage dividing resistor connected to the other end of the NTC thermistor, the other end of the voltage dividing resistor being connected to the first output end of the second DC/DC converter, the minute Piezoresistor and the NTC thermistor A node between the other end is connected to the AD sampling end of the safety assist control unit.
An electric vehicle characterized by comprising the protection device of the BMS power supply circuit according to any one of claims 1-6.
A method for protecting a BMS power supply loop is characterized in that: a first DC/DC converter, a PTC thermistor and a controllable switch are disposed in the BMS power supply loop, and the first DC/DC converter is used for The input first direct current is converted into a second direct current to supply the BMS, and the protection method includes the following steps:

Detecting a temperature at which the PTC thermistor is located;

Determining whether a temperature at a position where the PTC thermistor is located is greater than or equal to a preset temperature;

If the temperature of the position where the PTC thermistor is located is greater than or equal to the preset temperature, determining that the PTC thermistor is in an open state, and controlling the controllable switch to open to cut off the BMS power circuit .
The method for protecting a BMS power supply circuit according to claim 8, wherein the first direct current comprises a positive output terminal and a negative output terminal, and the PTC thermistor is connected to the positive output terminal and the first a transient suppression diode is further connected between the first input end of a DC/DC converter and between the positive output terminal and the negative output terminal, and the transient suppression diode is used to prevent the PTC thermistor The device was shorted by a breakdown.
The method for protecting a BMS power supply circuit according to claim 9, wherein an alarm is issued when the PTC thermistor is in an open state or in a short circuit state.