CN209982383U - Drive circuit and electric vehicle drive system - Google Patents

Abstract

The present application provides a drive circuit and an electric vehicle drive system. The drive circuit includes a power supply unit and an inverter circuit. The power supply unit includes three battery packs. One end of each battery pack is independent of each other. The other end of each battery pack is collinear with the other ends of the other two battery packs. The inverter circuit includes three bridge arms. One potential point of the three bridge arms is collinear. The collinear potential point is connected to one end of the battery pack which is collinear. Another potential point of each of the bridge arms is connected to one end of a battery pack which is independent of each other. The three battery packs are independent of each other, and the three bridge arms are independent of each other, so that the driving circuit has more degrees of freedom. The driving circuit can realize the heating function, the fast charging function and the balancing function of the battery without adding other devices.

Description

Drive circuit and electric vehicle drive system

technical field

The present application relates to the field of new energy vehicles, in particular to a drive circuit and an electric vehicle drive system.

Background technique

Currently, the energy storage device of an electric vehicle can be a lithium-ion battery. The power plant of an electric vehicle can use a three-phase synchronous motor or a three-phase asynchronous motor. The nominal voltage of a single-cell lithium-ion battery is generally less than 5V. By connecting one or more batteries in parallel, dozens or hundreds of batteries are connected in series to form a battery pack with a voltage of tens to hundreds of volts for driving vehicles. The busbar voltage range of passenger cars is 275V-550V, and the busbar voltage range of commercial vehicles is 450V-820V.

The traditional scheme of driving a motor with a battery pack is as follows: a single battery pack connected in series and parallel as a whole is connected to the DC high-voltage bus, and the DC power of the battery is converted into AC power through a three-phase full-bridge inverter circuit, and the three-phase AC power is used to drive the three-phase motor. The traditional battery pack-driven motor solution has a single function and cannot operate under the battery pack failure.

Utility model content

Based on this, it is necessary to provide a drive circuit and an electric vehicle drive system in order to solve the problem that the traditional battery pack driving motor solution has a single function and cannot realize the operation under the battery pack failure.

A drive circuit, comprising:

a power supply unit, including a first battery pack, a second battery pack, and a third battery pack; and

an inverter circuit, including a first bridge arm, a second bridge arm and a third bridge arm;

The first electrode of the first battery pack is connected to the busbar of the upper bridge arm of the first bridge arm, the first electrode of the second battery pack is connected to the busbar of the upper bridge arm of the second bridge arm, and the The first electrode of the third battery pack is connected to the busbar of the upper bridge arm of the third bridge arm;

The second electrode of the first battery, the second electrode of the second battery, and the second electrode of the third battery are collinear to form a first end;

The lower bridge arm of the first bridge arm, the lower bridge arm of the second bridge arm, and the lower bridge arm of the third bridge arm are collinear to form a second end;

The first end is connected to the second end bus bar.

In one of the embodiments, each battery pack in the power supply unit includes a battery unit and a first bypass switch, and a battery unit and a first bypass switch are connected in series.

In one embodiment, each battery cell includes:

a plurality of battery cells, the number of the battery cells in one of the battery cells is the same as the number of the battery cells in the other two battery cells;

The connection manner of the battery cells in one of the battery units is the same as the connection manner of the battery cells in the other two battery units.

In one of the embodiments, the battery cells in the one battery unit are connected in a manner of connecting a plurality of the battery cells in series, a plurality of the battery cells in parallel and then in series, a plurality of the battery cells in parallel, or One of a plurality of the battery cells connected in series and then connected in parallel.

In one embodiment, it also includes:

The second bypass switch is electrically connected between the first end and the second end.

In one embodiment, the second bypass switch is one of an electromagnetic relay, an insulated gate bipolar transistor or a metal-oxide semiconductor field effect transistor.

In one of the embodiments, each bridge arm in the inverter circuit includes:

two series-connected power switch devices, the collector terminal of one of the two series-connected power switch devices is connected to the positive bus bar of one battery pack;

The emitter terminal of the other power switching device in the two series-connected power switching devices is connected to the negative bus bar of one battery pack.

An electric vehicle drive system, comprising:

The drive circuit as described in any one of the above embodiments;

a battery management circuit electrically connected to the drive circuit; and

The first controller is electrically connected to the driving circuit.

In one embodiment, the battery management circuit includes:

a detection circuit electrically connected to the power supply unit; and

The second controller is electrically connected with the power supply unit.

In one embodiment, the detection circuit includes a voltage detection unit, a current detection unit and a temperature detection unit, and the voltage detection unit, the current detection unit and the temperature detection unit are respectively electrically connected to the power supply unit.

The present application provides a drive circuit and an electric vehicle drive system. The drive circuit includes a power supply unit and an inverter circuit. The power supply unit includes three battery packs. One end of each battery pack is independent of each other. The other end of each battery pack is collinear with the other ends of the other two battery packs. The inverter circuit includes three bridge arms. One potential point of the three bridge arms is collinear. The collinear potential point is connected to one end of the battery pack which is collinear. Another potential point of each of the bridge arms is connected to one end of a battery pack which is independent of each other. The three battery packs are independent of each other, and the three bridge arms are independent of each other, so that the driving circuit has more degrees of freedom. The driving circuit can realize the operation under the failure of the battery, the heating function, the fast charging function and the equalizing function without adding other devices.

Description of drawings

FIG. 1 is a diagram of a driving circuit provided by an embodiment of the present application;

FIG. 2 is a diagram of a driving circuit provided by an embodiment of the present application;

3 is a voltage space vector diagram of a driving circuit provided by an embodiment of the present application;

FIG. 4 is a diagram of an electric vehicle drive system provided by an embodiment of the present application;

FIG. 5 is a diagram of an electric vehicle drive system provided by an embodiment of the present application;

6 is a flowchart of a method for driving an electric vehicle provided by an embodiment of the present application;

7 is a flowchart of a method for heating an electric vehicle battery provided by an embodiment of the present application;

FIG. 8 is a current and voltage state diagram provided by an embodiment of the present application;

FIG. 9 is a flowchart of a method for fast charging and equalization of an electric vehicle provided by an embodiment of the present application;

FIG. 10 is a current change diagram during charging provided by an embodiment of the present application;

FIG. 11 is an electric vehicle charging topology diagram according to an embodiment of the present application.

Main component reference number description

The driving circuit 100 The second bridge arm 22 The first controller 50

Power supply unit 10 Third bridge arm 23 Distributor 60

The first battery pack 11 The second terminal 201 The first charging switch 61

Second battery pack 12 Power switching device 211 Second charging switch 62

The third battery pack 13 The three-phase motor 30 The third charging switch 63

First terminal 101 Electric vehicle drive system 200 Fourth charging switch 64

battery unit 110 battery management circuit 40 fifth charging switch 65

Cell 111 Detection circuit 41 Sixth charging switch 66

The first bypass switch 120 The voltage detection unit 411 The charging interface 70

The second bypass switch 130 The current detection unit 412 The first charging gun port 71

Inverter circuit 20 Temperature monitoring unit 413 Second charging gun 72

The first bridge arm 21 The second controller 42 The third charging gun port 73

Detailed ways

In order to make the above objects, features and advantages of the present application more clearly understood, the specific embodiments of the present application will be described in detail below with reference to the accompanying drawings. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present application. However, the present application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without departing from the connotation of the present application. Therefore, the present application is not limited by the specific implementation disclosed below.

It should be noted that when an element is referred to as being "disposed on" another element, it can be directly on the other element or intervening elements may also be present. When an element is referred to as being "connected" to another element, it can be directly connected to the other element or intervening elements may also be present.

Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the technical field to which this application belongs. The terms used herein in the specification of the application are for the purpose of describing specific embodiments only, and are not intended to limit the application. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.

Referring to FIG. 1 , an embodiment of the present application provides a driving circuit 100 . The driving circuit 100 includes a power supply unit 10 and an inverter circuit 20 .

The power supply unit 10 includes a first battery pack 11 , a second battery pack 12 and a third battery pack 13 . The inverter circuit 20 includes a first bridge arm 21 , a second bridge arm 22 and a third bridge arm 23 . The first electrode of the first battery pack 11 is connected to the bus bar of the upper bridge arm of the first bridge arm 21 . The first electrode of the second battery pack 12 is connected to the bus bar of the upper bridge arm of the second bridge arm 22 . The first electrode of the third battery pack 13 is connected to the bus bar of the upper bridge arm of the third bridge arm 23 . The second electrode of the first battery pack 11 , the second electrode of the second battery pack 12 , and the second electrode of the third battery pack 13 are collinear to form the first end 101 . The lower bridge arm of the first bridge arm 21 , the lower bridge arm of the second bridge arm 22 and the lower bridge arm of the third bridge arm 23 are collinear to form the second end 201 . The first end 101 is bus-connected with the second end 201 . The first battery pack 11 has an equivalent resistance R1. The second battery pack 12 has an equivalent resistance R2. The third battery pack 13 has an equivalent resistance R3.

In this embodiment, the power supply unit 10 includes three battery packs. One end of each battery pack is independent of each other. The other end of each battery pack is collinear with the other ends of the other two battery packs. The inverter circuit 20 includes three bridge arms. One potential point of the three bridge arms is collinear. The collinear potential point is connected to one end of the battery pack which is collinear. Another potential point of each of the bridge arms is connected to one end of a battery pack which is independent of each other. The three battery packs are independent of each other, and the three bridge arms are independent of each other, so that the driving circuit 100 has more degrees of freedom. The driving circuit 100 can realize the heating function, fast charging function and equalizing function of the battery without adding other devices.

Referring to FIG. 2 , in one embodiment, each battery pack in the power supply unit 10 includes a battery unit 110 and a first bypass switch 120 .

One of the battery cells 110 and one of the first bypass switches 120 are connected in series. The power supply unit 10 includes a plurality of battery cells 111 . The models and nominal capacities of the plurality of cells 111 may be the same. The plurality of battery cells 111 may be equally divided into three groups. The plurality of cells 111 in each group are connected to each other to form a battery unit 110 . The connection manner of the battery cells 111 in one of the battery cells 110 is the same as the connection manner of the battery cells 111 in the other two battery cells 110 . The connection mode is one of a plurality of the battery cells 111 in series, a plurality of the battery cells 111 in parallel and then in series, a plurality of the battery cells 111 in parallel, or a plurality of the battery cells 111 in series and then in parallel.

The first bypass switch 120 may be a relay. The first bypass switch 120 may also be a switch circuit in which a relay is connected in parallel with a series-connected precharge relay and a precharge group. The first bypass switch 120 is one of an electromagnetic relay, an insulated gate bipolar transistor or a metal-oxide semiconductor field effect transistor.

In this embodiment, each battery pack is connected to a first bypass switch 120, which can implement independent control of each battery pack. When one of the battery packs fails, the faulty battery pack can be isolated from the normal battery pack by disconnecting the first bypass switch 120 connected to the faulty battery pack. The isolation of the faulty battery pack from the normal battery pack avoids the problem that the entire power supply unit 10 cannot work due to the failure of one battery pack.

In one embodiment, the driving circuit 100 further includes a second bypass switch 130 .

The second bypass switch 130 is electrically connected between the first terminal 101 and the second terminal 201 . The second bypass switch 130 may be a relay. The second bypass switch 130 may also be a switch circuit in which a relay is connected in parallel with a series-connected precharge relay and a precharge group. The second bypass switch 130 is one of an electromagnetic relay, an insulated gate bipolar transistor or a metal-oxide semiconductor field effect transistor. By disconnecting the second bypass switch 130 , the purpose of disconnecting the power supply unit 10 and the inverter circuit 20 can be achieved.

In one embodiment, each bridge arm in the inverter circuit 20 includes two power switching devices 211 connected in series.

The collector terminal of one power switching device 211 in the two series-connected power switching devices 211 is connected to the positive bus bar of a battery pack. The emitter terminal of the other power switching device 211 in the two series-connected power switching devices 211 is connected to the negative bus bar of one battery pack. One power switch device 211 of each bridge arm may constitute the upper bridge arm of one bridge arm. The other power switch device 211 of each bridge arm may constitute the lower bridge arm of one bridge arm. The bridge arm may be an insulated gate bipolar transistor. The three-phase output ends of the inverter circuit 20 are respectively connected to the three-phase bus bars W, U, and V of the three-phase motor 30 . The three-phase motor 30 may be a three-phase synchronous motor. The three-phase motor 30 may also be a three-phase asynchronous motor.

When the load current of the first battery pack 11 is I ₁ , the load current of the second battery pack 12 is I ₂ , and the load current of the third battery pack 13 is I ₃ , the voltages of the three-phase independent bridge arms are u ₁ , u ₂ , u ₃ . The u ₁ , the u ₂ and the u ₃ satisfy the following formula:

u ₁ =E ₁ -I ₁ R ₁

u ₂ =E ₂ -I ₂ R ₂

u ₃ =E ₃ -I ₃ R ₃ formula group (1)

During the control process, only one switch of each bridge of the inverter circuit 20 is turned on at any time. The state of the inverter circuit 20 can be represented by a three-dimensional vector. The conduction of the lower bridge arm of the first bridge arm 21, the conduction of the lower bridge arm of the second bridge arm 22, and the conduction of the upper bridge arm of the third bridge arm 23 are denoted as U ₁ (001). And so on to get U ₀ (000), U ₁ (001), U ₂ (010), U ₃ (011), U ₄ (100), U ₅ (101), U ₆ (110), U ₇ ( 111). Since the voltages of the three bridge arms of the inverter circuit 20 are independent of each other, the voltage vector table of the drive circuit 100 in different bridge arms switching states is shown in Table 1 below.

Table 1 The voltage vector table of the driving circuit under different switching states of the bridge arms

In the voltage space vector diagram in this embodiment, the eight bridge arm switching states correspond to six voltage output space vectors, a null space vector U ₀ , and a space vector U ₇ generated due to the difference space vector of each battery pack. The fundamental vector U ₄ (100) is only affected by the voltage u ₁ , the fundamental vector U ₂ (010) is only affected by the voltage u ₂ , and the fundamental vector U ₁ (001) is only affected by the voltage u ₃ ; the fundamental vector U ₆ (110) Affected by the voltages u ₁ , u ₂ , the fundamental vector U ₃ (011) is affected by the voltages u ₂ , u ₃ , and the fundamental vector U ₅ (101) is affected by the voltages u ₁ , u ₃ .

When the magnitude of the vector U ₆ (110) is greater than the magnitude of the vector U ₄ (100) and the target driving voltage vector of the electric vehicle needs to be synthesized, in order to ensure that the electric vehicle performs balanced driving, that is, to ensure that the electric vehicle starts at the same time The battery power can be balanced, and the action time of the basic voltage vector U ₆ (110) synthesizing the target driving vector can be extended. That is, when it is necessary to synthesize the target driving voltage vector of the electric vehicle, the sub-battery group with higher power can output more energy. When the magnitude of the vector U ₆ (110) is greater than the magnitude of the vector U ₄ (100), and the electric vehicle target braking voltage vector needs to be synthesized, the action time of the basic voltage vector U ₄ (100) to synthesize the target driving vector can be extended, that is, When synthesizing the EV target braking voltage vector. Allows sub-battery packs that are currently less charged to absorb more energy. When the electric vehicle has a serious fault that the first battery pack 11 fails, the basic vectors U ₂ (010), U ₁ (001), U ₃ (011), and U ₀ (000) are not affected. The target vector can be continuously synthesized through a combination of power device switches in U ₂ (010), U ₁ (001), U ₃ (011) or U ₀ (000) to ensure that the power of the electric vehicle is not interrupted and has the ability to limp home. Function. When power balance between the battery groups is required, the space vector U ₇ can be used to charge and discharge, so as to balance the power among the battery groups.

Referring to FIG. 4 , an embodiment of the present application provides an electric vehicle drive system 200 . The electric vehicle drive system 200 includes a drive circuit 100 , a battery management circuit 40 and a first controller 50 .

The battery management circuit 40 is electrically connected to the driving circuit 100 . The first controller 50 is electrically connected to the driving circuit 100 . The driving manner of the driving circuit 100 in this embodiment is similar to the driving manner of the driving circuit 100 in the above-mentioned embodiments, and details are not described herein again. The battery management circuit 40 is used to detect the state of charge of the power supply unit 10 and the working state of the power supply unit 10 . The battery management circuit 40 is also used to manage and control the power supply unit 10 . For example, the battery management circuit 40 can control the opening and closing of the first bypass switch 120 and the second bypass switch 130 in the power supply unit 10 . The first controller 50 is configured to control the inverter circuit 20 to turn on the combination of the power switch devices 211 in a fixed manner. The battery management circuit 40 and the first controller 50 are connected through an isolated signal circuit.

In this embodiment, the electric vehicle drive system 200 includes a drive circuit 100 , a battery management circuit 40 and a first controller 50 . The power supply unit 10 in the drive circuit 100 includes three battery packs. One end of each battery pack is independent of each other. The other end of each battery pack is collinear with the other ends of the other two battery packs. The inverter circuit 20 includes three bridge arms. One potential point of the three bridge arms is collinear. The collinear potential point is connected to one end of the battery pack which is collinear. Another potential point of each of the bridge arms is connected to one end of a battery pack which is independent of each other. The three battery packs are independent of each other, and the three bridge arms are independent of each other, so that the driving circuit 100 has more degrees of freedom. The electric vehicle drive system 200 can realize the heating function, fast charging function and equalization function of the electric vehicle battery without adding other components.

Referring to FIG. 5 , in one embodiment, the electric vehicle has a control center. The battery management circuit 40 includes a detection circuit 41 and a second controller 42 .

The detection circuit 41 includes a voltage detection unit 411 , a current detection unit 412 and a temperature detection unit 413 . The voltage detection unit 411 , the current detection unit 412 and the temperature detection unit 413 are respectively electrically connected to the power supply unit 10 . . The second controller 42 is electrically connected to the power supply unit 10 .

The detection circuit 41 reports the detected voltage, current and temperature signals to the control center of the electric vehicle. The control center controls the driving, braking, heating and equalization of the driving circuit 100 through the first controller 50 and the second controller 42 according to the received signal.

Referring to FIG. 6 , an embodiment of the present application provides a method for driving an electric vehicle based on the above-mentioned electric vehicle driving system 200 . The electric vehicle drive system 200 according to any one of the above embodiments is used to realize the electric vehicle drive method, and the drive method includes:

S10, the battery management circuit 40 detects whether the power supply unit 10 is in a normal power supply state.

In step S10, the first battery pack 11 has an equivalent resistance R1. The second battery pack 12 has an equivalent resistance R2. The third battery pack 13 has an equivalent resistance R3. The power supply unit 10 includes a plurality of battery cells 111 . The models and nominal capacities of the plurality of cells 111 may be the same. The plurality of battery cells 111 may be equally divided into three groups. The plurality of cells 111 in each group are connected to each other to form a battery unit 110 . The connection method of the battery cells 111 in one of the battery cells 110 is the same as the connection method of the battery cells 111 in the other two battery cells 110 . The connection mode is one of a plurality of the battery cells 111 in series, a plurality of the battery cells 111 in parallel and then in series, a plurality of the battery cells 111 in parallel, or a plurality of the battery cells 111 in series and then in parallel.

S20, if the first battery pack 11, the second battery pack 12 and the third battery pack 13 are all in a normal power supply state, the battery management circuit 40 sequentially detects the first battery pack 11, all the The state of charge of the second battery pack 12 and the third battery pack 13 is used to determine the highest-charge battery pack and the lowest-charge battery pack.

In step S20, the battery management circuit 40 includes a detection circuit and a judgment unit. The detection circuit is used to detect the voltage, current, power and temperature of each battery pack.

S30, when the electric vehicle is in a starting state or in a running state, the first controller 50 controls the conduction time of the upper bridge arm of the bridge arm connected to the battery pack with the highest power level to be longer than that with the battery pack with the lowest power level The conduction time of the upper bridge arm of the connected bridge arm is used to control the time that the output power of the highest-capacity battery pack is greater than the time that the lowest-capacity battery pack outputs power, thereby synthesizing the driving voltage to ensure that the electric vehicle performs balanced driving .

In step S30, when the magnitude of the vector U ₆ (110) is greater than the magnitude of the vector U ₄ (100) and it is necessary to synthesize the target driving voltage vector of the electric vehicle, the function of the basic voltage vector U ₆ (110) to synthesize the target driving vector can be extended. time.

In this embodiment, the electric vehicle drive system 200 is used to implement the electric vehicle drive method. The electric vehicle driving method can ensure that the electric power of the three battery packs in the power supply unit 10 can be balanced during the starting or running of the electric vehicle.

In one embodiment, in S10, the step of detecting whether the power supply unit 10 is in a normal power supply state by the battery management circuit 40 includes:

The battery management circuit 40 detects and determines whether the output voltage of the power supply unit 10 is greater than or equal to the fault threshold voltage. If the output voltage is greater than or equal to the fault threshold voltage, the power supply unit 10 is in a normal power supply state. The fault threshold voltage may be the fault threshold voltage stored in the battery management circuit 40 .

In another embodiment, in S10, the battery management circuit 40 detects whether the power supply unit 10 is in a normal power supply state, and the power supply unit 10 includes a first battery pack 11, a second battery pack 12 and a third battery Steps for group 13 include:

The battery management circuit 40 detects and determines whether the cell temperature of the power supply unit 10 is lower than the failure threshold temperature. If the cell temperature is lower than the fault threshold temperature, the power supply unit 10 is in a normal power supply state. The fault threshold temperature may be the fault threshold temperature stored in the battery management circuit 40 .

In this embodiment, when the power supply unit 10 fails, the output voltage, the output current and the temperature of the cell may be changed. Therefore, by detecting the output voltage of the power supply unit 10 or by detecting the cell temperature of the power supply unit 10, it can be detected whether the power supply unit 10 is in a normal power supply state. It can also be detected whether the power supply unit 10 is in a normal power supply state by detecting the output current of the power supply unit 10 .

In one embodiment, the method further includes:

If the output voltage is less than the fault threshold voltage, or the cell temperature is greater than or equal to the fault threshold temperature, the power supply unit 10 is in an abnormal power supply state. When the power supply unit 10 is in an abnormal power supply state, the battery management circuit 40 determines whether each battery pack is in a normal power supply state by detecting the output voltage of each battery pack or the temperature of each battery pack. When a battery pack is in an abnormal power supply state, the normal power supply batteries are controlled to be combined into a driving voltage, so as to ensure that the electric vehicle has a limp home function.

In an optional embodiment, when the electric vehicle has a serious fault such as the failure of the first battery pack 11, the basic vectors U ₂ (010), U ₁ (001), U ₃ (011), and U ₀ (000) do not Affected. The target vector can be continuously synthesized through a switch combination of U ₂ (010), U ₁ (001), U ₃ (011) or U ₀ (000) to ensure that the power of the electric vehicle is not interrupted, and it has the function of limp home.

In this embodiment, when a serious fault occurs in the electric vehicle power system (for example, a battery pack fails), the target driving/braking voltage vector can be synthesized by using the basic voltage vector that is not affected by the fault to ensure that the power of the electric vehicle is not interrupted , and has the function of limp home.

In one embodiment, the method further includes:

When the highest battery pack and the lowest battery pack are determined, and the electric vehicle is in a braking state. The first controller 50 controls the conduction time of the upper bridge arm of the bridge arm connected to the highest-capacity battery pack to be less than or equal to the conduction time of the upper bridge arm of the bridge arm connected to the lowest-capacity battery pack. The first controller 50 is configured to control the battery pack with the lowest power to absorb power for a time longer than the battery pack with the highest power to absorb power, thereby ensuring that the electric vehicle performs balanced braking.

In an alternative embodiment, the magnitude of vector U ₆ (110) is greater than the magnitude of vector U ₄ (100). When it is necessary to synthesize the target braking voltage vector of the electric vehicle, the action time of the synthetic target braking vector of the basic voltage vector U ₄ (100) can be extended. That is, when synthesizing the target braking voltage vector of the electric vehicle, the sub-battery group with lower current capacity can absorb more energy.

In this embodiment, when synthesizing the target braking voltage vector of the electric vehicle, the action time of the basic voltage vector with a smaller amplitude is increased, so that the sub-battery pack with a lower current capacity can be made to ensure the braking of the electric vehicle. absorb more energy.

Referring to FIG. 7 , an embodiment of the present application provides a method for heating an electric vehicle battery. The electric vehicle battery heating method is implemented by using the electric vehicle drive system 200 .

The electric vehicle drive system 200 includes a drive circuit 100 , a battery management circuit 40 electrically connected to the drive circuit 100 , and a first controller 50 electrically connected to the drive circuit 100 .

The driving circuit 100 includes a power supply unit 10 , an inverter circuit 20 and a three-phase motor 30 connected by a bus bar. The power supply unit 10 includes three battery packs. The inverter circuit 20 includes three bridge arms. The positive pole of each battery pack is connected to the busbar of the upper bridge arm of one bridge arm. After the negative poles of the three battery packs are collinear, they are connected to the busbars of the lower bridge arms of the three bridge arms. Each phase bus of the three-phase motor 30 is connected to an output end of the bridge arm.

The battery heating method includes:

Before the electric vehicle starts, the battery management circuit 40 determines whether the electric vehicle needs to be heated for the battery. When it is confirmed that the electric vehicle needs to be heated by the battery, the inverter circuit 20 is controlled by the first controller 50, so that the power supply unit 10 charges the three-phase motor 30, and the three-phase motor 30 Store power.

When the power in the three-phase motor 30 reaches the storage threshold, the inverter circuit 20 is controlled by the first controller 50, so that the three-phase motor 30 charges the power supply unit 10, and the power supply The unit 10 polarizes itself during charging and discharging, thereby achieving a controllable temperature rise of each battery pack in the power supply unit 10 .

The battery heating method includes the mutual transfer of energy between any two of the battery packs. The battery heating method further includes mutual transfer of energy among the three battery packs. During the energy transfer process, the energy stored by the battery pack in the coils of the three-phase motor is not dissipated. The energy stored by the battery pack in the coils of the three-phase motor 30 can be transferred to another of the battery packs. That is, the power output by the power supply unit 10 is only consumed on the wire group, and the rest of the power is returned to the power supply unit 10 . During the energy transfer process of the power supply unit 10, due to the polarization of the battery pack itself, heat is generated inside the battery cells, and the heat can be used to heat the battery.

In order to realize the above energy transfer, the power switching device 211 is turned on and off successively. The switching states of the power switching device 211 are in the aforementioned switching states U0 (000), U1 (001), U2 (010), U3 (011), U4 (100), U5 (101), U6 (110), U7 (111) ) to switch. The switching method may be four switch states, step1, step2, step3, and step4, which are switched according to time sequence to form a cycle. The loop may be step1→step2→step3→step4→step1. The cycle may also be step1→step4→step3→step2→step1. The basic approach of the four switch state combinations can be shown in Table 2.

Table 2 Basic ways of four switch state combinations

The switching method can realize energy transfer through one of the above-mentioned basic ways. The switching method can also be a combination of two or more of the above-mentioned basic approaches. The combinatorial approach of the elementary pathways involves direct switching of a certain step in one elementary pathway to a step of the same switch state in another pathway. In an optional embodiment, the combination method of the basic pathways may be U ₄ →U ₆ →U ₂ →U ₀ →U ₄ . Figure 8 is a current-voltage state diagram under this switch combination. In FIG. 8 , by controlling the switching combination and switching time of the inverter circuit 20 , a square line voltage can be applied to the inductance of the three-phase motor 30 . The line current at the line voltage is in the form of an approximately triangular wave.

In an optional embodiment, each battery pack adopts battery technical parameters: voltage 400V, capacity 42Ah, energy 16.8kWh, weight 67kg, specific heat capacity 1300J/(kg*°C), internal resistance 132mΩ (25°C) 396mΩ (0°C) ) 1188mΩ(-20℃). The three-phase motor 30 adopts motor technical parameters rated power 60kW, rated DC bus voltage 400V, rated current 115A, peak current 230A, line resistance 15.4mΩ, line inductance 1.44mH.

Under the above technical parameters, the battery heating temperature rise rate by the battery heating method is 14.4°C/min (-20°C), 4.8°C/min (0°C), and 1.6°C/min (25°C).

In this embodiment, the battery heating method controls the opening and closing of the three bridge arms of the inverter circuit 20 through the first controller 50 to complete the repeated driving and braking of the three-phase motor 30 . The repeated driving and braking of the three-phase motor 30 realizes the energy output and energy recovery of the power supply unit 10 . Furthermore, the power supply unit 10 is polarized by itself, so that the temperature of the battery of the power supply unit 10 can be controlled in a controlled manner. The maximum operating current of the power switching device 211 in the inverter circuit 20 and the maximum operating current of the three-phase motor 30 are relatively high. The battery heating method can realize high-power heating and effectively improve the heating efficiency. The power switching device 211 serves as a control element, and the three-phase motor 30 serves as an energy storage element. There is no need to add special heating elements during battery heating, thus reducing electric vehicle powertrain costs.

In one of the embodiments, after it is confirmed that the electric vehicle needs to be heated by the battery, the inverter circuit 20 is controlled by the first controller 50, so that the power supply unit 10 supplies the three-phase motor to the electric vehicle. 30 is charged, and the steps of storing electricity in the three-phase motor 30 include:

The upper bridge arm of at least one bridge arm in the inverter circuit 20 is controlled to be turned on by the first controller 50 . And control the lower bridge arm of at least one bridge arm of the remaining bridge arms of the inverter circuit 20 to conduct through the first controller 50, so that the battery pack connected to the bridge arm that is connected to the upper bridge arm is turned on. The three-phase motor 30 is charged. In this embodiment, at least one battery pack in the power supply unit 10 is discharged through the inverter circuit 20 .

In one of the embodiments, when the electricity in the three-phase motor 30 reaches a storage threshold, the inverter circuit 20 is controlled by the first controller 50, so that the three-phase motor 30 turns to the The power supply unit 10 is charged, and the power supply unit 10 is polarized during the charging and discharging process, so that the step of realizing the controllable temperature rise of each battery pack in the power supply unit 10 includes:

The upper bridge arm of at least one bridge arm in the inverter circuit 20 is controlled to be turned on by the first controller 50 . And control the lower bridge arm of at least one bridge arm of the remaining bridge arms of the inverter circuit 20 to conduct through the first controller 50, so that the three-phase motor 30 is connected to the bridge that is connected to the upper bridge arm. The battery pack connected to the arm is charged. In this embodiment, at least one battery pack in the power supply unit 10 is charged by the three-phase motor 30 through the inverter circuit 20 .

In one of the embodiments, when the electricity in the three-phase motor 30 reaches a storage threshold, the inverter circuit 20 is controlled by the first controller 50, so that the three-phase motor 30 turns to the The power supply unit 10 is charged, and the power supply unit 10 is polarized during the charging and discharging process, so that the step of realizing the controllable temperature rise of each battery pack in the power supply unit 10 includes:

The first controller 50 controls the upper bridge arm of the bridge arm connected to the discharged battery pack to be disconnected, and the lower bridge arm of the bridge arm connected to the discharged battery pack to be turned on. And control the upper bridge arm of at least one bridge arm of the remaining bridge arms of the inverter circuit 20 to conduct through the first controller 50, so that the three-phase motor 30 is connected to the upper bridge arm. The battery pack connected to the bridge arm is charged. In this embodiment, the inverter circuit 20 realizes the charging of the three-phase motor 30 to at least one battery pack in the power supply unit 10 other than the discharging battery pack.

In one of the embodiments, when the electricity in the three-phase motor 30 reaches a storage threshold, the inverter circuit 20 is controlled by the first controller 50, so that the three-phase motor 30 turns to the The power supply unit 10 is charged, and the power supply unit 10 is polarized during the charging and discharging process, so that the step of realizing the controllable temperature rise of each battery pack in the power supply unit 10 includes:

The upper bridge arm of the bridge arm connected to the discharged battery pack is controlled to be turned on by the first controller 50 , and at least one bridge arm of the remaining bridge arms of the inverter circuit 20 is controlled by the first controller 50 to be turned on. The lower bridge arm is turned on, so that the three-phase motor 30 charges the discharged battery pack. In this embodiment, through the inverter circuit 20, the three-phase motor 30 is implemented to charge the discharged battery pack.

In one of the embodiments, after it is confirmed that the electric vehicle needs to be heated by the battery, the inverter circuit 20 is controlled by the first controller 50, so that the power supply unit 10 supplies the three-phase motor to the electric vehicle. 30 is charged, and the step of storing the electricity of the three-phase motor 30 further includes:

The battery management circuit 40 sequentially detects the state of charge of the three battery packs, and determines the battery pack with the highest power level and the battery pack with the lowest power level. The first controller 50 controls the conduction of the upper bridge arm of the bridge arm connected to the battery pack with the highest capacity, and controls the conduction of the lower bridge arm of at least one bridge arm of the remaining bridge arms of the inverter circuit 20 so that the battery pack with the highest power can charge the three-phase motor 30 . In this embodiment, the inverter circuit 20 realizes the discharge of the battery pack with the highest capacity in the power supply unit 10 . The battery heating method also achieves power balance among the battery packs while heating the battery packs.

In one of the embodiments, when the electricity in the three-phase motor 30 reaches a storage threshold, the inverter circuit 20 is controlled by the first controller 50, so that the three-phase motor 30 turns to the The power supply unit 10 is charged, and the power supply unit 10 is polarized during the charging and discharging process, so that the step of realizing the controllable temperature rise of each battery pack in the power supply unit 10 includes:

After the three-phase motor 30 is charged, the first controller 50 controls the upper bridge arm of the bridge arm connected to the battery pack with the lowest power to conduct, and controls the remaining bridge arms of the inverter circuit 20 The lower bridge arm of at least one bridge arm is turned on, so that the three-phase motor 30 charges the battery pack with the lowest power. In this embodiment, the inverter circuit 20 realizes the charging of the three-phase motor 30 to the battery pack with the lowest power in the power supply unit 10 . The battery heating method also achieves power balance among the battery packs while heating the battery packs.

In one embodiment, before the electric vehicle is started, the step of judging whether the electric vehicle needs to be heated by the battery management circuit 40 includes:

Whether the temperature of the cells of the power supply unit 10 is lower than the driving threshold temperature is detected by the battery management circuit 40 . When the temperature of the battery cell is lower than the driving threshold temperature, it is confirmed that the electric vehicle needs to perform battery heating. When the cell temperature is greater than or equal to the driving threshold temperature, the electric vehicle starts normally.

In one of the embodiments, when the electricity in the three-phase motor 30 reaches a storage threshold, the inverter circuit 20 is controlled by the first controller 50, so that the three-phase motor 30 turns to the The power supply unit 10 is charged, and the power supply unit 10 is polarized during the charging and discharging process, so that the step of realizing the controllable temperature rise of each battery pack in the power supply unit 10 further includes:

Whether the temperature of the cells of the power supply unit 10 is lower than the driving threshold temperature is detected by the battery management circuit 40 . When the temperature of the battery cell is lower than the driving threshold temperature, it is confirmed that the electric vehicle needs to continue heating the battery. When the cell temperature is greater than or equal to the driving threshold temperature, the electric vehicle starts normally.

Referring to FIG. 9 , an embodiment of the present application provides an electric vehicle control method based on the above electric vehicle drive system. The electric vehicle control method includes first realizing high-power charging of the electric vehicle, which is compatible with existing basic charging facilities and on-board devices, through a charging topology circuit. After charging is complete, detect the difference in charge between each battery pack. If there is no power difference between the battery packs or the power difference between the battery packs is less than or equal to the power balance threshold, the electric vehicle can directly wait for the driver to start to enter the normal driving mode. If the power difference between the battery packs is greater than the power balance threshold, power balance needs to be performed.

When the electric vehicle completes charging or is in use, the battery management circuit 40 sequentially detects the state of charge of the three battery packs, and determines the battery pack with the highest power level and the battery pack with the lowest power level. It is judged by the battery management circuit 40 whether the power difference between the highest power battery pack and the lowest power battery pack is greater than a power balance threshold. If the power difference is greater than the power balance threshold, the power of each battery pack in the power supply unit 10 is balanced by a parking balance method or a driving balance method, so that the power difference is less than or equal to the power balance threshold. The battery leveling threshold is stored in the storage unit of the battery management circuit 40 .

In this embodiment, the control method uses the battery management circuit 40 to determine the battery pack with the highest capacity and the battery pack with the lowest capacity. In the control method, the battery management circuit 40 is used to determine whether power balance needs to be performed. When power balance needs to be performed, the power of the electric vehicle is balanced by a parking balance method or a driving balance method. Both the parking balance method and the driving balance method control the opening and closing of the three bridge arms of the inverter circuit 20 through the first controller 50 to realize the energy output and energy between the three battery packs. Recycling, avoiding the problem of wasting energy. The control method does not need to add special energy storage components in the equalization process, thereby reducing the cost of the electric vehicle power system.

The battery balancing method further includes detecting whether there is time to perform balancing under parking conditions. If there is no time to perform the power balance under the parking condition, the electric vehicle directly waits for starting. If there is time to perform the power balancing under parking, the parking balancing current I ₀ needs to be calculated. If the parking balancing current I ₀ is less than the allowable current threshold I _max in the driving circuit 100 , a short inductance is used. Connect the balance. If the balancing current I ₀ under parking is greater than the allowable current threshold I _max in the driving circuit 100 , power transfer balancing is adopted.

The battery balancing method in the parking situation is used when the electric vehicle has sufficient parking time. The calculation formula of the equilibrium current I ₀ under parking is:

I ₀ =(E _max -E _min )/R _total formula (2)

Wherein, E _max and E _min are the initial open circuit voltage of the battery pack with the highest capacity and the initial open circuit voltage of the battery pack with the lowest capacity, respectively; R _total is the resistance of the battery pack with the highest capacity, the battery pack with the lowest capacity The sum of the resistance, the wire resistance and the wire resistance of the three-phase motor (30).

The inductance short-circuit equalization method includes directly closing the power switching device 211 of the upper bridge arm of the bridge arm connected to the battery pack to be equalized. At this time, the battery pack with the highest capacity is discharged, and the current flows through the power switching device 211 of the upper arm of the bridge arm and the inductance of the three-phase motor 30 to charge the battery pack with the lowest capacity. With the equalization process, the current is gradually reduced to achieve equalization of the cells. The charging process satisfies the equation:

为开路电压随电量变化的变化速率。Among them, E _max E _min are respectively the initial open circuit voltage of the battery pack with the highest capacity and the initial open circuit voltage of the battery pack with the lowest capacity. e _max (t) and e _min (t) are the real-time open-circuit voltage of the battery pack with the highest capacity and the real-time open-circuit voltage of the battery pack with the lowest capacity, respectively. i(t) is the real-time current. R _total is the sum of the highest battery pack resistance, the lowest battery pack resistance, the wire resistance, and the motor wire resistance. L is the loop inductance.

is the rate of change of the open-circuit voltage with the change in power.

In one case of this embodiment, the electric vehicle has sufficient parking time, and the equilibrium current I ₀ under parking is less than the current threshold I _max allowed in the driving circuit 100 . The inductance short-circuit equalization method needs to equalize the difference in power between the first battery pack 11 and the second battery pack 12 . During the equalization process, the upper bridge arm of the first bridge arm 21 and the upper bridge arm of the second bridge arm 22 can be directly closed. At this time, the first battery pack 11 with high voltage is discharged, and current flows through the upper bridge arm of the first bridge arm 21 and the upper bridge arm of the second bridge arm 22 and the three-phase motor 30 , and flows to the three-phase motor 30 . The second battery pack 12 with a low voltage is charged. The current change during the charging process is shown in FIG. 10 .

The power transfer equalization includes closing the upper bridge arm of the bridge arm connected to the battery pack with high power and the lower bridge arm of the bridge arm connected to the battery pack with low power. At this time, the high-power battery pack charges the three-phase motor 30 . Before the inductor current reaches the maximum allowable current, the upper bridge arm of the bridge arm connected to the battery pack with high power is turned off, and the lower bridge arm of the bridge arm connected to the battery pack with high power is closed. The lower bridge arm of the bridge arm connected to the battery pack with low power is turned off, and the upper bridge arm of the bridge arm connected to the battery pack with low power level is closed. At this time, the three-phase motor 30 charges the low-power battery pack. After the inductive discharge is completed, the upper arm of the three-phase motor 30 connected to the battery pack with low power is turned off, and the lower arm of the three-phase motor 30 connected to the battery pack with low power is closed. The above steps are continuously repeated until the power difference between the high-power battery pack and the low-power battery pack is less than or equal to the power balance threshold.

The method for balancing the battery pack under driving/braking conditions includes synthesizing a target driving voltage vector from the basic voltage space vector shown in FIG. 3 through a vector control method. When synthesizing the target driving voltage vector of the electric vehicle, the action time of the basic voltage vector with a larger amplitude is increased, that is, the sub-battery group with a higher current capacity can output more energy. When synthesizing the target braking voltage vector of the electric vehicle, the action time of the basic voltage vector with a smaller amplitude is increased, that is, the sub-battery group with a lower current capacity can absorb more energy. The above driving process is repeated continuously until the power difference between the high-power battery pack and the low-power battery pack is less than or equal to the power balance threshold. After that, the electric vehicle enters the normal drive/brake mode.

When the electric vehicle does not perform the parking equalization or the parking equalization is completed, the electric vehicle waits to start. After the electric vehicle is started, it is necessary to judge whether the driving balance needs to be performed according to the difference in electric power between the battery packs. The driving balance is performed if the power difference is greater than a power balance threshold. The driving balance further includes a drive process balance and a discharge process balance. The electric vehicle enters a normal driving mode until it is determined that the difference in electric power is less than or equal to the electric power balancing threshold.

An embodiment of the present application provides a method for charging an electric vehicle. The charging circuit topology used in the charging process of the electric vehicle is shown in FIG. 11 .

The circuit topology includes a power supply unit 10 , a distributor 60 and a charging interface 70 .

The power supply unit 10 includes a first battery pack 11 , a second battery pack 12 and a third battery pack 13 . The power distributor 60 includes a first charging switch 61 , a second charging switch 62 , a third charging switch 63 , a fourth charging switch 64 , a fifth charging switch 65 and a sixth charging switch 66 . The positive pole of the first battery pack 11 is connected to one end of the bus bar of the first charging switch 61 . The positive pole of the second battery pack 12 is connected to one end of the bus bar of the second charging switch 62 . The positive pole of the third battery pack 13 is connected to one end of the bus bar of the third charging switch 63 . The negative electrode of the first battery pack 11 , the negative electrode of the second battery pack 12 and the negative electrode of the third battery pack 13 are collinear to form the first end 101 . The first terminal 101 is respectively connected to a bus bar of one terminal of the fourth charging switch 64 , one terminal of the fifth charging switch 65 and one terminal of the sixth charging switch 66 . The charging interface 70 includes a first charging gun port 71 , a second charging gun port 72 and a third charging gun port 73 . The other end of the first charging switch 61 is connected to the positive pole of the first charging gun port 71 . The other end of the second charging switch 62 is connected to the positive pole of the second charging gun port 72 . The other end of the third charging switch 63 is connected to the positive pole of the third charging gun port 73 . The other end of the fourth charging switch 64 is connected to the negative electrode of the first charging gun port 71 . The other end of the fifth charging switch 65 is connected to the negative electrode of the second charging gun port 72 . The other end of the sixth charging switch 66 is connected to the negative pole of the third charging gun port 73 .

The electric vehicle charging method includes connecting the first charging gun port 71 , the second charging gun port 72 and the third charging gun port 73 to three charging guns. The charging guns may be three charging guns provided by a single charging pile. The charging gun may also be three charging piles provided by a plurality of charging piles. After the three charging gun ports are connected, the first controller 50 controls the first charging switch 61 and the fourth charging switch 64 to close. The battery management circuit 40 establishes communication with the control system of the charging device connected to the first charging gun port 71 . After the information exchange is completed, the first bypass switch 120 and the second bypass switch 130 corresponding to the first battery pack 11 are closed to charge the first battery pack 11 . The first controller 50 controls the second charging switch 62 and the fifth charging switch 65 to be closed. The battery management circuit 40 establishes communication with the control system of the charging device connected to the second charging gun port 72 . After the information exchange is completed, the first bypass switch 120 and the second bypass switch 130 corresponding to the second battery pack 12 are closed to charge the second battery pack 12 . The first controller 50 controls the third charging switch 63 and the sixth charging switch 66 to be closed. The battery management circuit 40 establishes communication with the control system of the charging device connected to the third charging gun port 73 . After the information exchange is completed, the first bypass switch 120 and the second bypass switch 130 corresponding to the third battery pack 13 are closed to charge the third battery pack 13 .

The present application realizes the function of three charging guns charging the battery pack at the same time through the above-mentioned topology structure and control method. The charging method avoids the limitation of the current-carrying capacity during single-gun high-power charging, improves the total charging current of the battery pack, and realizes compatibility with existing charging facilities and the voltage level of on-board components.

The technical features of the above-described embodiments can be combined arbitrarily. For the sake of brevity, all possible combinations of the technical features in the above-described embodiments are not described. However, as long as there is no contradiction between the combinations of these technical features, All should be regarded as the scope described in this specification.

The above-mentioned embodiments only represent several embodiments of the present application, and the descriptions thereof are relatively specific and detailed, but should not be construed as a limitation on the scope of the patent application. It should be pointed out that for those skilled in the art, without departing from the concept of the present application, several modifications and improvements can be made, which all belong to the protection scope of the present application. Therefore, the scope of protection of the patent of the present application shall be subject to the appended claims.

Claims (10)

1. A drive circuit (100), characterized in that, comprising: a power supply unit (10) comprising a first battery pack (11), a second battery pack (12) and a third battery pack (13); and an inverter circuit (20), comprising a first bridge arm (21), a second bridge arm (22) and a third bridge arm (23); The first electrode of the first battery pack (11) is connected to the busbar of the upper bridge arm of the first bridge arm (21), and the first electrode of the second battery pack (12) is connected to the second bridge arm (22) is connected to the busbar of the upper bridge arm, and the first electrode of the third battery pack (13) is connected to the busbar of the upper bridge arm of the third bridge arm (23); The second electrode of the first battery pack (11), the second electrode of the second battery pack (12) and the second electrode of the third battery pack (13) are collinear to form a first end (101) ); The lower bridge arm of the first bridge arm (21), the lower bridge arm of the second bridge arm (22) and the lower bridge arm of the third bridge arm (23) are collinear to form a second end (201) ); The first end (101) is bus-connected with the second end (201). 2. The drive circuit (100) according to claim 1, wherein each battery pack in the power supply unit (10) comprises a battery unit (110) and a first bypass switch (120), One of the battery cells (110) and one of the first bypass switches (120) are connected in series. 3. The drive circuit (100) according to claim 2, wherein each battery unit (110) comprises: a plurality of battery cells (111), the number of the battery cells (111) in one of the battery cells (110) is the same as the number of the battery cells (111) in the other two battery cells (110); The connection manner of the battery cells (111) in one of the battery units (110) is the same as the connection manner of the battery cells (111) in the other two battery units (110). 4. The drive circuit (100) according to claim 3, characterized in that, the battery cells in the one battery unit are connected in a manner that a plurality of the battery cells (111) are connected in series, and a plurality of the battery cells (111) are connected in series. The battery cells (111) are connected in parallel and then connected in series, a plurality of the battery cells (111) are connected in parallel, or a plurality of the battery cells (111) are connected in series and then connected in parallel. 5. The drive circuit (100) according to claim 1, further comprising: A second bypass switch (130) is electrically connected between the first end (101) and the second end (201). 6. The drive circuit (100) according to claim 5, wherein the second bypass switch (130) is an electromagnetic relay, an insulated gate bipolar transistor or a metal-oxide semiconductor field effect transistor. A sort of. 7. The drive circuit (100) according to claim 1, wherein each bridge arm in the inverter circuit (20) comprises: two series-connected power switching devices (211), wherein the collector terminal of one power switching device (211) in the two series-connected power switching devices (211) is connected to the positive bus bar of one battery pack; The emitter terminal of another power switching device (211) in the two series-connected power switching devices (211) is connected to the negative bus bar of one battery pack. 8. An electric vehicle drive system (200), characterized in that, comprising: The drive circuit (100) of any one of claims 1-7; a battery management circuit (40) electrically connected to the drive circuit (100); and The first controller (50) is electrically connected to the driving circuit (100). 9. The electric vehicle drive system (200) according to claim 8, wherein the battery management circuit (40) comprises: a detection circuit (41), electrically connected to the power supply unit (10); and A second controller (42) is electrically connected to the power supply unit (10). 10. The electric vehicle drive system (200) according to claim 9, wherein the detection circuit (41) comprises a voltage detection unit (411), a current detection unit (412) and a temperature detection unit (413), The voltage detection unit (411), the current detection unit (412) and the temperature detection unit (413) are respectively electrically connected to the power supply unit (10).

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