WO2013174276A1

WO2013174276A1 - Power system of electric vehicle and electric vehicle comprising the same

Info

Publication number: WO2013174276A1
Application number: PCT/CN2013/076109
Authority: WO
Inventors: Xingchi WU; Hongjun Wang; Shibin Xie
Original assignee: BYD Co Ltd; Shenzhen BYD Auto R&D Co Ltd
Current assignee: BYD Co Ltd; Shenzhen BYD Auto R&D Co Ltd
Priority date: 2012-05-22
Filing date: 2013-05-22
Publication date: 2013-11-28
Anticipated expiration: 2014-11-22

Description

POWER SYSTEM OF ELECTRIC VEHICLE AND ELECTRIC VEHICLE COMPRISING

THE SAME

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to, and benefits of the following applications:

(1) Chinese Patent Application Serial No. 201220232299.X, filed with the State Intellectual Property Office of P. R. C. on May 22, 2012;

(2) Chinese Patent Application Serial No. 201210160500.2, filed with the State Intellectual Property Office of P. R. C. on May 22, 2012;

(3) Chinese Patent Application Serial No. 201220232031.6, filed with the State Intellectual

Property Office of P. R. C. on May 22, 2012; and

(4) Chinese Patent Application Serial No. 201210160622.1, filed with the State Intellectual Property Office of P. R. C. on May 22, 2012.

The entire contents of the above applications are incorporated herein by reference.

FIELD

Exemplary embodiments of the present disclosure relate generally to a power system, and more particularly, to a power system of an electric vehicle and an electric vehicle comprising the power system.

BACKGROUND

Generally, the work temperature of the lithium ion battery is generally within a range from - 20°C to 55°C, and the battery is not allowed to be charged at a low temperature. Under a low temperature condition, the battery in the electric vehicle may have the following problems: the lithium ions may be deposited easily at the negative electrode and lose the electric activity at the low temperature, and therefore, if the battery in the electric vehicle is usually used at the low temperature, the life of the battery may be shortened and a safety problem may be caused accordingly; when the lithium ion battery is charged, the lithium ions may be deposited easily at the negative electrode to become dead ions and thus the capacity of the battery may be decreased, and moreover, the deposited ions grow larger and larger during the continuous use, thus leading to a potential danger such as an internal short circuit; the discharge capability of the battery is limited. The method for heating a battery is a very important technology in the electric vehicle field. A heating strategy of the battery and the performance of the battery heater influence the comfort, operation stability and safety of the vehicle directly. With the development of the science technology, the new energy vehicle especially the electric vehicle enters into a family as the means of transport. The performance requirement especially the comfort requirement of the user for the vehicle is higher and higher, which requires that the vehicle must adapt to different running requirements. But currently most electric vehicles can not satisfy the requirements. Especially in winter, the temperature is low so that the capability of the battery, no matter the discharge capability or the battery capacity, may be decreased or even the battery can not be used.

SUMMARY

According to a first aspect of the present disclosure, a power system of an electric vehicle is provided. The power system comprises: a battery group; a battery heater, connected with the battery group and configured to charge and discharge the battery group to heat the battery group; a battery management device, connected with the battery group and the battery heater respectively, and configured to control the battery heater to heat the battery group; an electric distribution box, connected with the battery group, connected in parallel with the battery heater, and configured to distribute a voltage output by the battery group; a motor; a motor controller, connected with the motor and the electric distribution box respectively and configured to supply power to the motor according to a control command and a voltage distributed by the electric distribution box; and an isolation inductor, having a first terminal connected with the electric distribution box, and a second terminal connected with the battery group.

With the power system according to embodiments of the present disclosure, the battery heater is capable of charging or discharging the battery group to heat the battery group, and thus an internal resistor of the battery itself may be heated so that the battery group may be heated. Without any external power supply, the electricity for heating is totally supplied by the battery group, and therefore a higher heating efficiency, a lower cost and a better utility may be obtained.

In one embodiment of the present disclosure, the isolation inductor is disposed outside the battery heater, and the electric distribution device is connected in parallel with the battery heater, thus efficiently reducing the influence of the battery heater on the electric distribution device and other power consumption equipments of the electric vehicle. In addition, because there is no power cable connected between the electric distribution device and the battery heater (i.e., the battery group is connected with four power cables, the battery group is connected with the electric distribution device via two power cables, and the battery group is connected with the battery heater via the other two power cables), the influence of the battery heater on the electric distribution device can be reduced. Due to the parallel connection between the battery heater and the electric distribution device, when the motor is working but the battery heater is not working, a switch may be provided to prevent a current from flowing through the battery heater.

In another embodiment of the present disclosure, the isolation inductor is disposed inside the battery heater. Thus, the heating circuit may not be influenced by the load circuit, and the assembly and disassembly of the battery heater may be facilitated while the operation of the heating circuit is ensured. In case the environmental temperature is very high, the battery heater may be removed for reducing a manufacture cost.

According to a second aspect of the present disclosure, an electric vehicle comprising the above power system is provided. The electric vehicle can normally run in a cold region and the battery group can be heated while the electric vehicle is running, thus ensuring a safe and smooth running.

BRIEF DESCRIPTION OF THE DRAWINGS

Having thus described exemplary embodiments of the present disclosure in general terms, reference will now be made to the accompanying drawings, which are not necessarily drawn to scale.

Fig. 1 illustrates a schematic diagram of a power system of an electric vehicle according to an exemplary embodiment;

Fig. 2 illustrates an electric connection diagram of a power system of an electric vehicle according to an exemplary embodiment;

Fig. 3 illustrates an electric connection diagram of a power system of an electric vehicle according to an exemplary embodiment;

Fig. 4 illustrates a schematic diagram of an electric distribution device in a power system of an electric vehicle according to an exemplary embodiment;

Fig. 5 illustrates a schematic diagram of a power system of an electric vehicle according to another exemplary embodiment; Fig. 6 illustrates an electric connection diagram of a power system of an electric vehicle according to another exemplary embodiment; and

Fig. 7 illustrates an electric connection diagram of a power system of an electric vehicle according to another exemplary embodiment.

DETAILED DESCRIPTION

Reference will now be made in detail to exemplary embodiments, examples of which are illustrated in the accompanying drawings. It is readily appreciated by those having ordinary skill in the art that the presently claimed subject matter may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein.

In the description, relative terms such as "longitudinal", "lateral", "lower", "upper", "front",

"rear", "left", "right", "horizontal", "vertical", "above", "below", "up", "top", "bottom" "external",

"internal " as well as derivative thereof (e.g., "horizontally", "downwardly", "upwardly", etc.) should be construed to refer to the orientation as then described or as shown in the drawings under discussion. These relative terms are for convenience of description and do not require that the present disclosure be constructed or operated in a particular orientation.

In the description, terms concerning attachments, coupling and the like, such as "connected" and "interconnected", refer to a relationship in which structures are secured or attached to one another through mechanical or electrical connection, or directly or indirectly through intervening structures, unless expressly described otherwise. Specific implications of the above phraseology and terminology may be understood by those skilled in the art according to specific situations.

Referring to Fig. 1, in some embodiments of the present disclosure, a power system of an electric vehicle comprises: a battery group 101, a battery heater 102, a battery management device

103, an electric distribution box 104, a motor 105, a motor controller 106 and an isolation inductor L2. In one embodiment of the present disclosure, the battery group 101 may be a power battery group, or any other battery capable of providing power to the electric vehicle, without particular limits. The battery heater 102 is connected with the battery group 101 and configured to charge and discharge the battery group 101 to heat the battery group 101.

In one embodiment of the present disclosure, the battery management device 103 is connected with the battery heater 102 and the battery group 101 respectively to control the battery heater 102 to heat the battery group 101. Alternatively, the battery management device 103 is connected with the battery heater 102 via a CAN cable 107 and connected with the battery group 101 via a sampling cable 108 to sample the temperature and voltage of each battery and the output current of the battery group 101. In addition, the battery management device 103 is also configured to judge the current status of the electric vehicle, to calculate the residual electric quantity of the battery group 101, and to send the control signals to the relevant electric devices via the CAN cable 107 so as to manage the relevant devices (for example, the battery group 101). Specifically, the battery management device 103 is configured to control the battery heater 102 to heat the battery group 101 when the temperature of the battery group 101 is lower than a first preset temperature threshold and the residual electric quantity of the battery group 101 is larger than a preset electric quantity threshold.

As shown in Fig. 1, the isolation inductor L2 has a first terminal connected with the battery group 101 and a second terminal connected with the electric distribution device 104, and the isolation inductor L2 is disposed inside the battery heater 102.

With the power system according to embodiments of the present disclosure, the battery heater 102 is capable of charging or discharging the battery group 101 to heat the battery group 101, and thus an internal resistor of the battery itself may be heated so that the battery group 101 may be heated. Without any external power supply, the electricity for heating is totally supplied by the battery group 101, and therefore a higher heating efficiency, a lower cost and a better utility may be obtained. In addition, since the isolation inductor L2 is disposed inside the battery heater 102, the heating circuit may not be influenced by the load circuit, and the assembly and disassembly of the battery heater 102 may be facilitated while the operation of the heating circuit is ensured. In case the environmental temperature is very high, the battery heater 102 may be removed for reducing a manufacture cost.

In one embodiment of the present disclosure, the electric distribution box 104 is a high voltage device for turning on and off the large current. As shown in Fig. 3, the electric distribution device 104 is connected in parallel with the battery heater 102. A voltage output by the battery group 101 is distributed by the battery management device 103 by sending a control signal to the electric distribution box 104.

In one embodiment of the present disclosure, the motor controller 106 is connected with the motor 105 and the electric distribute box 104 respectively, and comprises a first input terminal, a second input terminal and a pre-charging capacitor C2 connected between the first input terminal and the second input terminal. The motor controller 106 is configured to supply power to the motor 105 according to a control command and a voltage distributed to the motor controller 106 by the electric distribution box 104. Specifically, the motor controller 106 converts the DC supplied by the battery group 101 into the three-phase AC required by the motor 105 to supply power to the motor 105 by the internal driving circuit of the motor controller 106.

In one embodiment of the present disclosure, the battery management device 103 is configured to control the power system to operate in a running heating mode or a parking heating mode. The motor controller 106 controls the motor to operate under a limited power according to a signal sent by the battery management device 103 when the power system operates in the running heating mode. The battery heater 102 performs a failure self-test and sends a result to the battery management device 103, and the battery management device 103 is configured to inhibit the battery group 101 from being heated or charged and inhibit the electric vehicle from being driven when the result shows that there is a failure in the battery heater 102.

The running heating mode means that besides the battery group 101 being heated by the battery heater 102, other high voltage power consumption equipments of the electric vehicle such as the motor and the air conditioner may work simultaneously under a limited power. Accordingly, the parking heating mode means that except the battery group 101 being heated by the battery heater 102, the other high voltage power consumption equipments of the electric vehicle such as the motor and the air conditioner do not work. The running electric quantity threshold is a first predetermined residual electric quantity of the battery group when the electric vehicle is allowed to enter in the running heating mode, and the parking electric quantity threshold is a second predetermined residual electric quantity of the battery when the electric vehicle is allowed to enter in the parking heating mode.

In one embodiment of the present disclosure, the isolation inductor L2 is connected between the battery group 101 and the electric distribution box 104, and the inductance of the isolation inductor L2 matches with the capacitance of the pre-charging capacitor C2. In one embodiment of the present disclosure, the inductance L of the isolation inductor L2 may be determined according to the formula

_wh_ere T is an equivalent load work cycle of the motor 105 and C is the capacitance of the pre-charging capacitor C2. With the isolation inductor L2, the load circuit is prevented from influencing the heating circuit, thus ensuring a normal operation of the heating circuit. The battery heater 102 needs to control the IGBT module and switch on/off the first switch module 301 or the second switch module 302. Assuming that a switching frequency of the first switch module 301 or the second switch module 302 is t, in order to reduce the influence of the battery heater 102 on the motor controller 106, it may be assumed that a cycle of a circuit comprising the isolation inductor L2 and the pre-charging capacitor C2 is T. In one embodiment, T >10t, thus meeting the design requirements. Therefore, as used herein, the expression "T is an equivalent load work cycle of the motor 105" means that T is the cycle of the circuit comprising the isolation inductor L2 and the pre-charging capacitor C2.

In one embodiment of the present disclosure, as shown in Fig. 3, the battery heater 102 comprises a heating assembly 1021 and a housing 1022. The heating assembly 1021 is connected with the battery group 101 and configured to charge and discharge the battery group 101 to heat the battery group 101. The housing 1022 is configured to contain the heating assembly 1021 and the isolation inductor L2.

In one embodiment of the present disclosure, as shown in Fig. 3, the heating assembly 1021 may comprise: a first switch module 301 , a first capacitor CI, a first inductor LI and a second switch module 302. A first terminal of the first switch module 301 is connected with a first electrode of the battery group 101 and the isolation inductor L2 respectively. A first terminal of the first capacitor CI is connected with a second terminal of the first switch module 301 , and a second terminal of the first capacitor CI is connected with a second electrode of the battery group 101. A first terminal of the first inductor LI is connected with a node between the first switch module 301 and the first capacitor CI. A first terminal of the second switch module 302 is connected with a second terminal of the first inductor LI, a second terminal of the second switch module 302 is connected with the second electrode of the battery group 101. The control terminal of the first switch module 301 and the control terminal of the second switch module 302 are connected with the battery management device 103. The battery management device 103 sends a heating signal to the control terminal of the first switch module 301 and the control terminal of the second switch module 302 to control the first switch module 301 and the second switch module 302 to turn on in turn. When the first switch module 301 is on, the second switch module 302 is off, and when the second switch module 302 is on, the first switch module 301 is off.

Referring to Fig. 2, the ESR is an equivalent resistor of the battery group 101, the ESL is an equivalent inductor of the battery group 101 , and E is a battery group. L2 is an isolation inductor and is configured to isolate the battery heater Part 2 from the motor equivalent load circuit Part 5. Therefore, the reversed voltage of the battery group 101 is absorbed by the isolation inductor L2 and may not be applied to the load follow-up. C2 is a direct current bus capacitor of the motor controller 106, i.e., a pre-charging capacitor; and R is the equivalent load of the motor 105. When the battery heater 102 works, an internal switch module thereof turns on or off in a certain timing sequence.

Referring to Fig. 2, according to one embodiment of the present disclosure, the switch module (e.g., the first switch module 301 or the second switch module 302) may be an insulated gate bipolar transistor (IGBT). Those skilled in the art will understand that, any other device which is capable of achieving the same effect (connecting and disconnecting the circuit) falls into the scope of the present disclosure. When the battery heater starts to work, the internal elements of the battery heater such as inductor, capacitor are in an initial status and do not store any energy. The work procedure of the battery heater 102 will be described below. When an IGBT1 is on and an IGBT2 is off, the battery package E charges the first capacitor CI by the charging loop "E-ESR- ESL-D1-C1-E". After the battery package E has charged the first capacitor CI for a time, the voltage of the first capacitor CI is equal to the voltage of the battery package E. But because there is an inductive element in the battery heater, the first capacitor CI continues being charged so that the voltage of the first capacitor CI is higher than that of the battery package. When the charge current is zero, the first capacitor CI begins to discharge by the discharging loop "C1-D1-ESL- ESR-E-C1" until the discharge current is zero. When the IGBT1 is off and the IGBT2 is on, the first capacitor CI continues discharging by the discharging loop "C1-D2-L1-IGBT2-C1". Because there is the first inductor LI, the first capacitor CI continues to discharge so that the voltage of the first capacitor CI is lower than that of the battery package E. Above process is thus repeated. In that way, the battery heater 102 charges or discharges the battery group 101 to heat the battery group 101, and thus an internal resistor of the battery itself may be heated so that the battery group 101 may be heated. Without any external power supply, the electricity for heating is totally supplied by the battery group 101, thus reducing the manufacture cost and achieving the large- scale production.

In one embodiment of the present disclosure , the isolation inductor L2 may prevent the pre- charging capacitor C2 from charging the first capacitor CI through the first switch module 301 so that the current waveform of the first capacitor CI may be controlled and thus the characteristics of the heating circuit may be controlled. Therefore, the circuit may run normally. As a result, when the motor 105 and the battery heater 102 operate simultaneously, the isolation inductor L2 may be needed.

In one embodiment of the present disclosure, the battery heater 102 further comprises a power connector configured to connect and fasten a power cable 109. The power connector needs to satisfy the requirement of the anti-vortex. When the battery heater 102 works, the frequency of the current is changed very quickly, which leads to very quick increase in the temperature of the magnetic material in the power connector, so the magnetic permeability of the power connector must be low.

In one embodiment of the present disclosure, the battery heater 102 further comprises four power connectors, in which two power connectors are connected with the battery group 101 via the power cable 109 and the other two power connectors are connected with the electric distribution box 104 via the power cable 109. In one embodiment of the present disclosure, the power connectors are used in the head end and the tail end of a high voltage cable. The battery heater 102 is connected with the electric distribution device 104 via a power cable. As shown in Fig. 3, the heating assembly 1021 of the battery heater 102 is connected in parallel with the electric distribution device 104.

Alternatively, the battery heater 102 further comprises a low voltage connector, which is connected and communicates with the external system. The low voltage connector comprises a CAN cable 107 configured to connect to the battery management device 103, a self-test signal cable and a failure signal cable.

In one embodiment of the present disclosure, the isolation inductor L2 is disposed inside the battery heater 102, so that the electric distribution box 104 may be connected directly to the battery group 101. In that way, the structure of the power system is further simplified. As shown in Fig. 3, in one embodiment of the present disclosure, the battery heater 102 comprises the isolation inductor L2, the fuse 401 and a power supply for the battery heater 102. When the battery group 101 does not need to be heated, the battery heater 102 may be removed, so that the electric distribution box 104 may be connected directly to the battery group 101. The electric vehicle does not need any battery heater 102 in the high temperature area but needs the battery heater 102 in the low temperature area. Therefore, if the electric vehicle needs to be modified to adapt to different areas, the modification may be small, thus greatly reducing the cost and broadening the application scope. As shown in Fig. 6, in another embodiment of the present embodiment, the isolation inductor L2 is disposed outside the battery heater 102, and the electric distribution device 104 is connected in parallel with the battery heater 102. In that way, the electric distribution device 104 and other power consumption equipments in the electric vehicle may be prevented from being influenced by the battery heater 102. Alternatively, the isolation inductor L2 is disposed inside the electric distribution device 104. In other words, the isolation inductor L2 is connected with the electric distribution device 104 via a cable, and disposed inside a shell of the electric distribution device 104.

In one embodiment of the present disclosure, the battery heater 102 further comprises a low voltage connector, which is connected and communicates with the external system. The low voltage connector comprises a CAN cable 107 configured to connect to the battery management device 103, a self-test signal cable and a failure signal cable.

In one embodiment of the present disclosure, the battery group 101 is connected with the battery heater 102 and the electric distribution device 104 via four power cables respectively. The battery heater 102, the electric distribution box 104 and the battery group 101 each comprise a power connector configured to fasten and connect the power cables.

In one embodiment of the present disclosure, the battery group 101 further comprises four power connectors, in which two power connectors are connected with the battery heater 102 via the power cable 109 and the other two power connectors are connected with the electric distribution box 104 via the power cable 109. In one embodiment of the present disclosure, the power connectors are used in the head end and the tail end of a high voltage cable. The battery heater 102 is connected in parallel with the electric distribution device 104.

Because the battery heater 102 is connected in parallel with the electric distribution box 104, the current can be controlled by a switch not to flow through the battery heater 102 when the motor 105 is working while the battery heater 102 stops working. In that way, the electric distribution device 104 may be prevented from being influenced by the battery heater 102 during the operation process of the motor 105.

In one embodiment of the present disclosure, the power system of the electric vehicle further comprises a relay 501 connected between the battery group 101 and the electric distribution box 104, and configured to select whether the isolation inductor L2 is connected into the circuit. Specifically, when the battery heater 102 works, the isolation inductor L2 may be connected into the circuit by the relay 501, and when the battery heater 102 stops working, the isolation inductor L2 may be disconnected from the circuit. In one embodiment, the isolation inductor L2 is disposed inside the electric distribution box 104, so that the influence of the battery heater 102 on the electric distribution box 104 may be greatly reduced.

In one embodiment of the present disclosure, as shown in Fig. 1 and Fig. 5, the power system of the electric vehicle further comprises a cooling assembly 110 configured to cool the battery heater 102, i.e., to cool the first switch module 301 and the second switch module 302.

In one embodiment of the present disclosure, the cooling assembly 110 comprises: a wind channel arranged in the battery heater 102; and a fan arranged at one end of the wind channel. The fan is used to dissipate heat for the battery heater 102.

In another embodiment of the present disclosure, the cooling assembly 110 comprises: a coolant channel arranged in the battery heater 102; a coolant inlet (not shown) and a coolant outlet (no shown) arranged in the battery heater 102 respectively. The heat dissipation effect and the sealing performance of the battery heater may be improved by using the coolant to cool the battery heater.

Referring to Fig. 4, the electric distribution box 104 may further comprise: a primary contactor 601 and a pre-contactor 602. The primary contactor 601 is configured to distribute the voltage output by the battery group 101 to a power consumption equipment, such as the motor 105 of the electric vehicle. The pre-contactor 602 is connected with the first input terminal 603 or the second input terminal 604 of the motor controller 106, and configured to charge the pre-charging capacitor C2 under the control of the battery management device 103 before the motor controller 106 controls the motor 105 to start. In this embodiment, the pre-contactor 602 is connected with the first input terminal 603 of the motor controller 106.

A process for operating the power system of the electric vehicle will be described in details below.

After the electric vehicle is powered on, the battery management device 103 starts to work and detects the average temperature of the battery group 101, a residual electric quantity of the battery group 101, and the on/off condition of the primary contactor in the electric distribution box 104. The battery management device 103 samples the temperature of each single battery in the battery group 101 and calculates the average temperature of the battery group 101. If the average temperature of the battery group 101 is lower than a first preset temperature threshold and the residual electric quantity of the battery group 101 is larger than a preset electric quantity threshold, and the heating button is pressed and held for a preset time, then the battery management device 103 sends a control command to the battery heater 102 via a CAN cable 107, allowing the electric vehicle to be heated and driven. In one embodiment of the present disclosure, the first preset temperature threshold may be about -10°C, and the preset electric quantity threshold may be about 30% of the total electric quantity of the battery group 101. Before the electric vehicle starts a running heating process, i.e., before the motor 105 starts to work, the battery management device 103 sends a control signal to the electric distribution box 104 to control the pre-contactor to be switched on, thus allowing the battery group 101 to charge the pre-charging contactor C2, and when the voltage of the pre-charging contactor C2 almost reaches the voltage of the battery group 101, the motor 105 is allowed to start working. The battery management device 103 is capable of controlling the power system to work in the parking heating mode or in the running heating mode according to the driving condition of the electric vehicle. When the electric vehicle is running, the battery management device 103 sends a charging signal to control the motor 105 to operate under a limited power. When the temperature of the battery group 101 reaches a required temperature, the battery management device 103 controls the battery heater 102 to stop heating the battery group 101.

With the power system of the electric vehicle of the present disclosure, by using the battery group 101 to discharge with large current and by the heating of the internal resistor of the battery group 101, the battery group 101 may be heated. Without any external power supply, the electricity for heating is totally provided by the battery group 101. A heating management may be performed for the battery group 101 by the battery management device 103 and the battery heater 102, which may greatly reduce the restriction on the use of the electric vehicle at the low temperature and satisfy the requirement of running and charging at the low temperature, that is, the battery group 101 may be heated while the electric vehicle may run under a limited power. Moreover, the power system of the electric vehicle heats the battery group 101 directly, and therefore, a higher heating efficiency, a lower cost and a better utility may be achieved.

According to an embodiment of the present disclosure, an electric vehicle is provided. The electric vehicle comprises the power system of the electric vehicle mentioned above. The electric vehicle may run in a low temperature environment, and the electric vehicle may run while the battery group may be heated, thus ensuring a safe and smooth running. In the preceding specification, the subject matter has been described with reference to specific exemplary embodiments. It will, however, be evident that various modifications and changes may be made without departing from the broader spirit and scope of the claimed subject matter as set forth in the claims that follow. The specification and drawings are accordingly to be regarded as illustrative rather than restrictive. Other embodiments may be apparent to those skilled in the art from consideration of the specification and practice of the embodiments disclosed herein.

Claims

WHAT IS CLAIMED IS:

1. A power system of an electric vehicle, comprising:

a battery group;

a battery heater, connected with the battery group and configured to charge and discharge the battery group to heat the battery group;

a battery management device, connected with the battery group and the battery heater respectively, and configured to control the battery heater to heat the battery group;

an electric distribution box, connected with the battery group, connected in parallel with the battery heater, and configured to distribute a voltage output by the battery group;

a motor;

a motor controller, connected with the motor and the electric distribution box respectively and configured to supply power to the motor according to a control command and a voltage distributed by the electric distribution box; and

an isolation inductor, having a first terminal connected with the electric distribution box, and a second terminal connected with the battery group.

2. The power system of claim 1, wherein the battery management device is configured to control the battery heater to heat the battery group when a temperature of the battery group is lower than a first preset temperature threshold and a residual electric quantity of the battery group is larger than a preset electric quantity threshold.

3. The power system of claim 1, wherein the isolation inductor is disposed outside the battery heater.

4. The power system of claim 3, wherein the battery heater comprises:

a first switch module, a first terminal of the first switch module connected with a first electrode of the battery group;

a first capacitor, a first terminal of the first capacitor connected with a second terminal of the first switch module, and a second terminal of the first capacitor connected with a second electrode of the battery group;

a first inductor, a first terminal of the first inductor connected with a node between the first switch module and the first capacitor; and

a second switch module, a first terminal of the second switch module connected with a second terminal of the first inductor, and a second terminal of the second switch module connected with the second electrode of the battery group,

wherein a control terminal of the first switch module and a control terminal of the second switch module are connected with the battery management device.

5. The power system of claim 3, further comprising:

a relay, connected between the battery group and the electric distribution box, and configured to: connect the isolation inductor into a circuit when the battery heater is heating the battery group, and disconnect the isolation inductor from the circuit when the battery heater stops working.

6. The power system of claim 3, wherein the battery group is connected with the battery heater and the electric distribution box via power cables respectively.

7. The power system of claim 1, wherein the isolation inductor is disposed inside the battery heater.

8. The power system of claim 7, wherein the battery heater comprises:

a heating assembly, and

a housing configured to contain the heating assembly and the isolation inductor.

9. The power system of claim 8, wherein the battery heater comprises:

10. The power system of claim 7, wherein the battery heater and the electric distribution box are connected with each other in series.

11. The power system of claim 6 or 10, wherein the battery heater, the electric distribution box and the battery group each comprise a power connector configured to fasten and connect the power cables.

12. The power system of claim 4 or 9, wherein the battery management device sends a heating signal to the control terminal of the first switch module and the control terminal of the second switch module to control the first switch module and the second switch module to turn on in turn so as to generate a charge current and a discharge current in turn, in which the first switch module is on when the second switch module is off, and the first switch module is off when the second switch module is on.

13. The power system of claim 1, wherein the motor controller comprises:

a first input terminal;

a second input terminal; and

a pre-charging capacitor, connected between the first input terminal and the second input terminal, in which an inductance of the isolation inductor matches with a capacitance of the pre- charging capacitor

14. The power system of claim 13, wherein the inductance L of the isolation inductor is determined by a formula:

where T is an equivalent load work cycle of the motor and C is the capacitance of the pre- charging capacitor.

15. The power system of claim 2, wherein the battery management device is configured to allow the power system to operate in a running heating mode or a parking heating mode.

16. The power system of claim 15, wherein the motor controller is configured to control the motor to operate under a limited power according to a signal sent by the battery management device when the power system operates in the running heating mode.

17. The power system of claim 1, further comprising:

a cooling assembly, configured to cool the battery heater.

18. The power system of claim 1, wherein the electric vehicle comprises a pure electric vehicle and a hybrid electric vehicle.

19. An electric vehicle comprising a power system of any one of claims 1-18.