Motor brake control method and device, electric drive system and vehicle

Abstract

The application relates to the technical field of new energy vehicles, and discloses a motor braking control method and device, an electric drive system and a vehicle, wherein the method comprises the following steps: acquiring braking demand power of the vehicle; and controlling cross-axis current and direct-axis current of the motor according to the braking demand power of the vehicle, so that the motor recovers kinetic energy of the vehicle and converts the kinetic energy into heat energy. According to the above technical solution disclosed in the application, the cross-axis current and the direct-axis current of the motor are controlled according to the braking demand power of the vehicle, so that the motor recovers the kinetic energy of the vehicle and converts the kinetic energy into heat energy, the mode of recovering the kinetic energy of the motor is no longer limited to converting into electric energy and feeding back to a power battery, the mode of recovering the kinetic energy of the motor is expanded, and the flexibility and diversity of recovering the kinetic energy of the vehicle during motor braking are improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of new energy vehicles, in particular to a motor braking control method and device, an electric drive system and a vehicle. BACKGROUND

[0002] Compared with traditional fuel vehicles, new energy vehicles use a motor as a power source, and in addition to being able to select to use a mechanical braking system to provide braking force, the motor can also be selected to brake.

[0003] At present, when the motor is used for braking, the motor outputs braking torque. In the process of the motor outputting braking torque, the kinetic energy of the vehicle is converted into electric energy by the motor and fed back to the power battery. However, the current motor energy recovery method is relatively single.

[0004] To sum up, how to expand the motor energy recovery method is a technical problem to be solved by the technical personnel in the field at present. SUMMARY

[0005] Therefore, the purpose of the present application is to provide a motor braking control method and device, an electric drive system and a vehicle, which can reduce the loss of vehicle kinetic energy and improve the utilization rate of vehicle kinetic energy.

[0006] In order to achieve the above purpose, the present application provides the following technical solutions:

[0007] A motor braking control method comprises: acquiring braking demand power of a vehicle; controlling quadrature axis current and direct axis current of the motor according to the braking demand power of the vehicle, so that the motor recovers kinetic energy of the vehicle and converts it into heat energy.

[0008] A motor braking control device comprises: a first acquisition module configured to acquire braking demand power of a vehicle; and a control module configured to control quadrature axis current and direct axis current of the motor according to the braking demand power of the vehicle, so that the motor recovers kinetic energy of the vehicle and converts it into heat energy.

[0009] An electric drive system comprises a VCU, a motor controller connected to the VCU, and a motor connected to the motor controller, wherein: the VCU is configured to acquire braking demand power of a vehicle, and control quadrature axis current and direct axis current of the motor through the motor controller according to the braking demand power of the vehicle, so that the motor recovers kinetic energy of the vehicle and converts it into heat energy.

[0010] A vehicle comprises an electric drive system as described in any of the above, and is configured to implement the steps of the motor braking control method as described in any of the above.

[0011] The application provides a motor braking control method and device, an electric drive system and a vehicle.

[0012] Additional aspects and advantages will be set forth in part in the description which follows, and in part will become apparent to those skilled in the art upon examination of the following and / or can be learned by practice of the application. BRIEF DESCRIPTION OF DRAWINGS

[0013] Figure 1 A flow chart of a motor braking control method provided by an embodiment of the application;

[0014] Figure 2 A flow chart of a motor braking control method provided by an embodiment of the application;

[0015] Figure 3 A flow chart of a motor braking control method provided by an embodiment of the application;

[0016] Figure 4 A flow chart of a motor braking control method provided by an embodiment of the application;

[0017] Figure 5 A flow chart of a motor braking control method provided by an embodiment of the application;

[0018] Figure 6 A structure schematic diagram of a motor control device provided by an embodiment of the application;

[0019] Figure 7 A structure schematic diagram of a motor control device provided by an embodiment of the application;

[0020] Figure 8 A structure schematic diagram of a motor control device provided by an embodiment of the application;

[0021] Figure 9 A structure schematic diagram of a motor control device provided by an embodiment of the application; DETAILED DESCRIPTION

[0022] Compared with a traditional fuel vehicle, a new energy vehicle uses a motor as a power source, and can choose to use the motor to brake during braking. At present, when the motor is used to brake, the motor outputs a braking torque. During the process of the motor outputting the braking torque, the kinetic energy of the vehicle is converted into electric energy by the motor and fed back to the power battery. However, the current motor energy recovery mode is relatively single.

[0023] Therefore, the application provides a motor braking control method and device, an electric drive system and a vehicle, which are used to expand the motor energy recovery mode, so as to improve the flexibility and diversity of motor energy recovery during motor braking.

[0024] The embodiments of the application are described in detail below, examples of which are shown in the drawings, wherein the same or similar notations represent the same or similar elements or elements with the same or similar functions throughout. The embodiments described below by referring to the drawings are exemplary and are intended to explain the application, and cannot be understood as a limitation of the application.

[0025] Referring to Figure 1 which shows a flowchart of a motor braking control method provided by an embodiment of the application, the motor braking control method provided by an embodiment of the application can include:

[0026] S11: Obtain the braking demand power of the vehicle.

[0027] It should be noted that the execution subject of the motor braking control method provided by the embodiments of the application can be an electric drive system, a motor braking control device or a vehicle, etc., and the application is described by taking the electric drive system as an example.

[0028] When the vehicle is braking, the electric drive system can obtain the braking demand power of the vehicle. The electric drive system can directly obtain the braking demand power of the vehicle, or can collect the depth of the depressed brake pedal and the current vehicle speed information, and calculate the braking demand power of the vehicle according to the depth of the depressed brake pedal and the current vehicle speed information (the braking demand power of the vehicle is the braking power required by the vehicle during braking, that is, the braking power corresponding to the kinetic energy to be recovered by the vehicle), etc.

[0029] It should be noted that the electric drive system can execute step S11 in real time or at a fixed time interval (the size of the fixed time interval can be set according to experience or requirements, etc.), so as to obtain the braking demand power of the vehicle in time, thereby facilitating dynamic motor braking control according to the braking demand power of the vehicle, and improving the performance of motor braking control.

[0030] S12: Control the quadrature axis current and the direct axis current of the motor according to the braking demand power of the vehicle, so that the motor recovers the kinetic energy of the vehicle and converts it into heat energy.

[0031] On the basis of step S11, the electric drive system can control the quadrature axis current and the direct axis current of the motor according to the braking demand power of the vehicle, so that the motor recovers the kinetic energy of the vehicle and converts it into heat energy, so that the motor is no longer limited to outputting braking torque when participating in braking of the vehicle, but can control the quadrature axis current and the direct axis current of the motor to make the motor recover the kinetic energy of the vehicle and convert it into heat energy, expanding the recovery mode of the kinetic energy of the motor during braking. Illustratively, the motor can be completely converted into heat energy after recovering the kinetic energy of the vehicle. Alternatively, the motor can not only be converted into heat energy after recovering the kinetic energy of the vehicle, but also be converted into electric energy and fed back to the power battery in the vehicle.

[0032] Compared with the prior art of converting kinetic energy into electric energy and feeding it back to the power battery by allowing the motor to output braking torque during braking, the above technical solution disclosed by the embodiments of the present application controls the quadrature axis current and the direct axis current of the motor according to the braking demand power of the vehicle to make the motor recover the kinetic energy of the vehicle and convert it into heat energy, so that the mode of recovering kinetic energy by the motor is no longer limited to converting it into electric energy and feeding it back to the power battery, thereby expanding the mode of recovering kinetic energy by the motor and improving the flexibility and diversity of recovering kinetic energy of the vehicle during motor braking.

[0033] The motor braking control method provided by the embodiments of the present application can further include: obtaining the battery allowed feedback power and the heating demand power of the vehicle when obtaining the braking demand power of the vehicle.

[0034] Controlling the quadrature axis current and the direct axis current of the motor according to the braking demand power of the vehicle to make the motor recover the kinetic energy of the vehicle and convert it into heat energy includes: controlling the quadrature axis current and the direct axis current of the motor according to the braking demand power of the vehicle, the battery allowed feedback power and the heating demand power of the vehicle to make the motor operate in a low efficiency area to recover the kinetic energy of the vehicle and convert it into electric energy for charging the power battery in the vehicle and heat energy for heating the system in the vehicle that has a heating demand.

[0035] In the embodiments of the present application, the battery allowed feedback power can be obtained at the same time as the braking demand power of the vehicle is obtained. The battery allowed feedback power is the maximum power allowed to be fed back by the power battery at the corresponding moment. For the battery allowed feedback power, this parameter can be directly obtained (for example, directly obtained from the BMS (Battery Management System, battery management system)), or the maximum feedback current and the maximum feedback voltage allowed by the power battery can be obtained from the BMS, and the battery allowed feedback power is calculated according to the maximum feedback current and the maximum feedback voltage allowed by the power battery.

[0036] In addition, it can also be determined whether the vehicle has a heating demand at the same time, for example, by determining whether the ambient temperature is lower than a preset temperature to determine whether the vehicle has a heating demand, by determining whether a heating instruction of a target system (i.e., a system in the vehicle that has a heating demand) is obtained to determine whether the vehicle has a heating demand, or by determining whether a heating demand power is received to determine whether there is a heating demand, etc. If it is determined that the vehicle has a heating demand, the braking demand power of the vehicle, the allowable feedback power of the battery, and the heating demand power of the vehicle can be obtained at the same time, and specifically, the heating demand power of the vehicle can be obtained from the system in the vehicle that has a heating demand.

[0037] It should be noted that obtaining the allowable feedback power of the battery and the heating demand power of the vehicle can be performed in real time or at a fixed time interval (the size of the fixed time interval can be set according to experience or requirements, etc.), so as to obtain the braking demand power of the vehicle, the allowable feedback power of the battery, and the heating demand power of the vehicle in time, and to control the motor braking according to these parameters, so as to dynamically adjust the feedback power and the heating power of the electric drive system to meet the heating demand under various working conditions. Moreover, by determining whether the vehicle has a heating demand in real time or at a fixed time interval, the changing heating demand power can be obtained in time, so as to dynamically adjust the heating amount of the motor, thereby avoiding unlimitedly increasing the temperature of the motor and the heat conduction circuit, so that the electric drive system and the power battery work under the best temperature condition as much as possible.

[0038] On the basis of the above, the motor cross-axis current and the motor direct-axis current can be controlled according to the braking demand power of the vehicle, so that the motor recovers the kinetic energy of the vehicle and converts it into heat energy. Specifically, the motor cross-axis current and the motor direct-axis current can be controlled according to the braking demand power of the vehicle, the allowable feedback power of the battery, and the heating demand power of the vehicle, so that the motor operates in a low-efficiency region (i.e., the motor operates in the low-efficiency region by adjusting the distribution of the motor cross-axis current and the motor direct-axis current according to the braking demand power of the vehicle, the allowable feedback power of the battery, and the heating demand power of the vehicle). The low-efficiency region is a region with relatively low efficiency of converting kinetic energy into electric energy, and specifically, it can be a region with an efficiency of converting kinetic energy into electric energy lower than a preset efficiency value, which can be determined by calibration, etc. By making the motor operate in the low-efficiency region, the copper loss and the iron loss of the motor are increased to generate heat, so that the kinetic energy recovered by the motor during braking can be converted into not only electric energy but also heat energy. The electric energy can be fed back to the power battery to charge the power battery, and the heat energy can be used to heat the system in the vehicle that has a heating demand through the heat conduction circuit. Through the above process, the absolute value of the motor direct-axis current I d will increase, so that the stator current I sThe increased current generates heat through the winding, which converts the mechanical energy of the motor shaft end into heat energy. The heat energy flows through the heat conduction circuit to the system in the vehicle that needs heating, to heat the system that needs heating, and to improve the utilization rate of the kinetic energy of the vehicle. That is, the foregoing process adjusts the distribution of the direct and quadrature axis currents of the motor to control the motor to operate in the low efficiency area, thereby increasing the copper loss and iron loss of the motor to generate heat. When the motor brakes, the kinetic energy of the vehicle recovered can not only be converted into electric energy to charge the power battery, but also be converted into heat energy through the copper loss and iron loss of the motor to heat the system in the vehicle that needs heating through the heat conduction circuit.

[0039] Referring to Figure 2 which shows the flow chart of the kinetic energy of the vehicle recovered when the motor brakes, the kinetic energy of the vehicle recovered when the motor brakes E m can be converted into the electric energy E e fed back, and the heat energy E heat consumed through the copper loss and iron loss of the motor. That is, part of the kinetic energy of the vehicle recovered when the motor brakes can be converted into electric energy, and part of the kinetic energy of the vehicle recovered when the motor brakes can be converted into heat energy. The converted electric energy can charge the power battery in the vehicle (specifically, the power battery in the vehicle can be charged through the inverter), and the converted heat energy can heat the system in the vehicle that needs heating (specifically, the system in the vehicle that needs heating can be heated through the heat conduction circuit). As known from the foregoing, if the electric energy E e fed back is maintained unchanged, the heat energy E heat consumed through the copper loss and iron loss of the motor is increased, the kinetic energy of the vehicle consumed by the motor can be increased, that is, the braking capacity of the vehicle can be increased, and the loss of the kinetic energy of the vehicle can be reduced, thereby improving the utilization rate of the kinetic energy of the vehicle.

[0040] Referring to Figure 3 which shows the heat conduction circuit diagram of the heat generated by the motor provided by the embodiment of the application, the heat energy generated by the kinetic energy of the vehicle recovered when the motor brakes can flow through the heat conduction circuit to the system in the vehicle that needs heating, to heat the system that needs heating. If the power battery in the vehicle needs heating in a low temperature environment, at this time, the heat energy generated by the kinetic energy of the vehicle recovered when the motor brakes can flow through the heat conduction circuit to the power battery to heat the power battery, so that the temperature of the power battery is rapidly increased to the normal working temperature in the low temperature environment, to improve the charging and discharging performance of the battery, thereby improving the allowable feedback power of the battery, and further improving the braking capacity of the vehicle in the low temperature environment. Of course, the passenger compartment, air conditioning system and the like in the vehicle can also need heating, at this time, the heat generated by the kinetic energy of the vehicle recovered when the motor brakes can also flow through the heat conduction circuit to other systems that need heating to heat these systems.

[0041] The motor is controlled to operate in a low efficiency area by adjusting the motor's direct-axis current and quadrature-axis current distribution, so as to increase the motor's copper loss and iron loss to generate heat, so that the vehicle kinetic energy recovered by the motor during braking can be converted into not only electric energy to charge the vehicle's power battery, but also heat energy to be transmitted to the system in the vehicle that has a heating demand through a heat conduction loop, so as to heat the system that has a heating demand by using the heat energy converted from the recovered vehicle kinetic energy. Through the above process, the vehicle kinetic energy recovered by the motor can be increased even if the feedback power is unchanged, so as to improve the motor's braking capability and reduce the loss of vehicle kinetic energy during braking, and improve the utilization rate of vehicle kinetic energy. That is, through the above process, the motor generates heat while feedback braking, so that part of the vehicle kinetic energy recovered by the motor is converted into electric energy to charge the battery, and part of the vehicle kinetic energy is converted into heat energy to heat the vehicle, thereby improving the motor's recovery capability of vehicle kinetic energy and reducing the waste of vehicle kinetic energy during braking. Moreover, in the above process, the feedback power and heat generation power of the electric drive system can be dynamically adjusted to meet the heating demand under various working conditions while meeting the vehicle braking demand. In addition, the above process directly uses the heat energy generated by the motor during braking to heat the system in the vehicle that has a heating demand, without the need for additional heating components or the need to convert the heat energy into electric energy to heat the vehicle, so as to reduce the vehicle heating cost and the vehicle manufacturing cost, and also improve the utilization rate of feedback energy.

[0042] Through the above process, the motor not only converts the recovered vehicle kinetic energy into electric energy to charge the power battery during braking, but also converts the recovered vehicle kinetic energy into heat energy to heat the system in the vehicle that has a heating demand, thereby not only expanding the way of recovering kinetic energy by the motor, but also achieving full utilization of the kinetic energy recovered by the motor, reducing the waste of the kinetic energy recovered by the motor, and improving the utilization rate of the kinetic energy recovered by the motor.

[0043] The motor braking control method provided by the embodiment of the application controls the motor's direct-axis current and quadrature-axis current according to the vehicle's braking demand power, the battery's allowed feedback power, and the vehicle's heating demand power, so as to make the motor operate in a low efficiency area, recover vehicle kinetic energy, and convert the vehicle kinetic energy into electric energy to charge the vehicle's power battery and heat energy to heat the system in the vehicle that has a heating demand. The method can include: when the vehicle's braking demand power is less than the sum of the battery's allowed feedback power and the vehicle's heating demand power, controlling the motor's direct-axis current and quadrature-axis current according to the vehicle's braking demand power, the battery's allowed feedback power, and the vehicle's heating demand power, so as to preferentially convert the vehicle kinetic energy recovered by the motor into heat energy to heat the system in the vehicle that has a heating demand, or preferentially convert the vehicle kinetic energy recovered by the motor into electric energy to charge the vehicle's power battery.

[0044] In the embodiment of the present application, when the motor is controlled to operate in a low efficiency area to recover the kinetic energy of the vehicle and convert the kinetic energy into electric energy for charging the power battery in the vehicle and heat energy for heating the system in the vehicle having a heating demand, if the braking demand power of the vehicle is less than the sum of the allowed feedback power of the battery and the heating demand power of the vehicle, it indicates that the kinetic energy to be recovered by the vehicle cannot meet the charging demand of the power battery and the heating demand of the vehicle at the same time. At this time, the motor can be controlled according to the braking demand power of the vehicle, the allowed feedback power of the battery and the heating demand power of the vehicle to convert the kinetic energy of the vehicle recovered by the motor into heat energy for heating the system in the vehicle having a heating demand, and the remaining kinetic energy recovered can be converted into electric energy for charging the power battery, so as to preferentially meet the heating demand of the vehicle, thereby efficiently heating the vehicle, reducing the loss of kinetic energy of the vehicle, and facilitating the extension of the driving range of the vehicle. Alternatively, the kinetic energy of the vehicle recovered by the motor can be converted into electric energy for charging the power battery in the vehicle, and the remaining kinetic energy recovered can be converted into heat energy for heating the system in the vehicle having a heating demand, so as to preferentially meet the charging demand of the power battery, thereby extending the driving range of the vehicle as much as possible and enhancing the motor braking capability.

[0045] It should be noted that when the braking demand power of the vehicle is equal to the sum of the allowed feedback power of the battery and the heating demand power of the vehicle, it indicates that the kinetic energy to be recovered by the vehicle can meet the charging demand of the power battery and the heating demand of the vehicle. At this time, the motor can be controlled according to the braking demand power of the vehicle, the allowed feedback power of the battery and the heating demand power of the vehicle to convert the kinetic energy of the vehicle recovered by the motor into heat energy for heating the system in the vehicle having a heating demand and electric energy for charging the power battery in the vehicle, thereby meeting the heating demand of the vehicle and the charging demand of the power battery.

[0046] Referring to Figure 4Fig. 6 is a flow chart showing another motor braking control method provided by the embodiments of the present application. The motor braking control method provided by the embodiments of the present application, when the braking demand power of the vehicle is less than the sum of the battery allowed feedback power and the heating demand power of the vehicle, controls the quadrature axis current and the direct axis current of the motor according to the braking demand power of the vehicle, the battery allowed feedback power and the heating demand power of the vehicle, to preferentially convert the kinetic energy of the vehicle recovered by the motor into heat energy for heating the system in the vehicle which has a heating demand, which can include: if the heating demand power of the vehicle is less than the braking demand power of the vehicle, determining the first braking torque of the motor according to the difference between the braking demand power and the heating demand power; determining the first quadrature axis current and the first direct axis current of the motor according to the heating demand power of the vehicle and the first braking torque of the motor; and braking controlling the motor according to the first quadrature axis current and the first direct axis current of the motor, to preferentially convert the kinetic energy of the vehicle recovered by the motor into heat energy for heating the system in the vehicle which has a heating demand.

[0047] In the embodiments of the present application, when the vehicle has a heating demand, when the braking demand power of the vehicle is less than the sum of the battery allowed feedback power and the heating demand power of the vehicle, the specific process of controlling the quadrature axis current and the direct axis current of the motor according to the braking demand power of the vehicle, the battery allowed feedback power and the heating demand power of the vehicle, to preferentially convert the kinetic energy of the vehicle recovered by the motor into heat energy for heating the system in the vehicle which has a heating demand, can be: when the braking demand power of the vehicle is less than the sum of the battery allowed feedback power and the heating demand power of the vehicle, if the heating demand power of the vehicle is less than the braking demand power of the vehicle, calculating the difference between the braking demand power of the vehicle and the heating demand power of the vehicle (i.e. braking demand power of the vehicle-heating demand power of the vehicle), and determining the first braking torque of the motor according to the difference between the braking demand power of the vehicle and the heating demand power of the vehicle. Then, the first quadrature axis current and the first direct axis current of the motor can be determined according to the heating demand power of the vehicle and the first braking torque of the motor, and the motor is braking controlled according to the determined first quadrature axis current and the first direct axis current of the motor, to control the motor to operate in the low efficiency area by adjusting the distribution of the quadrature axis current and the direct axis current of the motor, and preferentially convert the kinetic energy of the vehicle recovered by the motor into heat energy for heating the system in the vehicle which has a heating demand, and the remaining kinetic energy recovered can be converted into electric energy for charging the power battery, so that the kinetic energy of the vehicle recovered by the motor preferentially meets the heating demand of the vehicle, the remaining kinetic energy of the vehicle can be converted into electric energy to charge the battery, thereby meeting the heating demand of the vehicle, improving the performance of the vehicle and the user experience, avoiding energy loss caused by first converting into electric energy and then converting into heat energy, to reduce the loss of the kinetic energy of the vehicle, improve the utilization rate of the recovered kinetic energy of the vehicle, and also prolong the driving range of the vehicle.

[0048] It should be noted that the relationship between the torque output by the motor and the power of the motor is T=9550*P / n, where T is the torque of the motor, P is the power of the motor, and n is the rotation speed of the motor output, that is, the first brake torque of the motor mentioned above can be determined by using the formula. And when the braking demand power of the vehicle is equal to the sum of the battery allowed feedback power and the heating demand power of the vehicle, the control can be performed in the above manner to convert the kinetic energy recovered by the motor into heat energy for heating the system in the vehicle that has a heating demand and electrical energy for charging the power battery in the vehicle to meet the heating demand of the vehicle and the charging demand of the power battery. In addition, if the heating demand power of the vehicle is not less than the braking demand power of the vehicle, the kinetic energy recovered by the motor can be converted into heat energy by controlling the quadrature axis current and the direct axis current of the motor, so as to preferentially convert the kinetic energy recovered by the motor into heat energy for heating the system in the vehicle that has a heating demand. Or, a part of the kinetic energy recovered by the motor can be converted into heat energy for heating the system in the vehicle that has a heating demand, and a part of the kinetic energy recovered by the motor can be converted into electrical energy for charging the power battery in the vehicle. Specifically, the battery recovery power (specifically, the first preset battery recovery power, which can be less than the smaller one of the braking demand power of the vehicle and the battery allowed feedback power) can be set in advance, the eighth brake torque of the motor is determined according to the first preset battery recovery power, the eighth quadrature axis current and the eighth direct axis current of the motor are determined according to the difference between the braking demand power of the vehicle and the first preset battery recovery power, and the eighth brake torque of the motor, and the motor is controlled according to the eighth quadrature axis current and the eighth direct axis current of the motor.

[0049] The motor brake control method provided by the embodiment of the application can include: obtaining three-phase currents of an inverter connected with the motor and the power battery; determining the current quadrature axis current and the current direct axis current of the motor according to the three-phase currents; and controlling the motor according to the current quadrature axis current and the first quadrature axis current of the motor, and the current direct axis current and the first direct axis current of the motor.

[0050] In the embodiment of the present application, the electric drive system can include an inverter connected to the motor and the power battery. When the electric drive system performs braking control on the motor according to the first quadrature axis current and the first direct axis current of the motor, the three-phase current of the inverter (i.e., the three-phase current of the alternating current of the inverter) connected to the motor and the power battery is first obtained, and the current quadrature axis current and the current direct axis current of the motor are determined according to the three-phase current of the inverter. Then, the braking control on the motor is performed according to the current quadrature axis current of the motor, the first quadrature axis current of the motor, the current direct axis current of the motor, and the first direct axis current of the motor, i.e., the braking control on the motor is realized in a closed-loop feedback control manner, so that the motor can accurately brake according to the determined first quadrature axis current and first direct axis current, thereby improving the motor braking performance.

[0051] The motor braking control method provided in the embodiment of the present application can determine the first quadrature axis current and the first direct axis current of the motor according to the heating demand power of the vehicle and the first braking torque of the motor, which can include:

[0052] The first quadrature axis current and the first direct axis current of the motor are determined according to the first mapping relationship obtained by pre-calibration, the heating demand power of the vehicle, and the first braking torque of the motor. The first mapping relationship is the corresponding relationship among the vehicle heating demand power, the motor braking torque, the motor direct axis current, and the motor quadrature axis current.

[0053] In the embodiment of the present application, the mapping relationship among the vehicle heating demand power, the motor braking torque, the motor direct axis current, and the motor quadrature axis current (i.e., the first mapping relationship obtained by pre-calibration) can be pre-calibrated. Then, the first quadrature axis current of the motor (as the first quadrature axis current of the motor) and the first direct axis current of the motor (as the first direct axis current of the motor) corresponding to the vehicle heating demand power and the first braking torque of the motor can be queried from the first mapping relationship obtained by pre-calibration according to the vehicle heating demand power and the first braking torque of the motor, so as to improve the determination efficiency, convenience, and accuracy of the first quadrature axis current and the first direct axis current of the motor.

[0054] The motor braking control method provided in the embodiments of the present application can further include: if the braking demand power of the vehicle is greater than the allowed feedback power of the battery, determining a second braking torque of the motor according to the allowed feedback power of the battery, determining a first mechanical braking power according to the braking demand power of the vehicle and the allowed feedback power of the battery, sending the first mechanical braking power to the braking system, and performing braking control on the motor according to the second braking torque of the motor, so that the braking system and the motor jointly brake; and if the braking demand power of the vehicle is not greater than the allowed feedback power of the battery, determining a third braking torque of the motor according to the braking demand power of the vehicle, and performing braking control on the motor according to the third braking torque of the motor.

[0055] In the embodiments of the present application, when it is determined that the vehicle has no heating demand, it can be directly determined whether the braking demand power of the vehicle is greater than the allowed feedback power of the battery.

[0056] If it is determined that the braking demand power of the vehicle is greater than the allowed feedback power of the battery, a second braking torque of the motor is determined according to the allowed feedback power of the battery, and braking control is performed on the motor according to the second braking torque, so that the motor brakes according to the allowed feedback power of the battery. In addition, a first mechanical braking power can be determined according to the braking demand power of the vehicle and the allowed feedback power of the battery, specifically, the first mechanical braking power = the braking demand power of the vehicle - the allowed feedback power of the battery, and then the determined first mechanical braking power is sent to the braking system in the vehicle, so that the braking system in the vehicle mechanically brakes according to the second mechanical braking power. If there is an IPB (Integrated Power Brake, intelligent integrated braking system) in the vehicle, the determined first mechanical braking power can be sent to the IPB in the vehicle, so that the IPB mechanically brakes according to the first mechanical braking power. That is, when the vehicle has no heating demand and the braking demand power of the vehicle is greater than the allowed feedback power of the battery, the braking system and the motor can jointly brake to well meet the braking demand of the vehicle, and in this process, the motor brakes according to the maximum braking capacity to recover the kinetic energy of the vehicle and convert it into electrical energy (i.e., the braking power is converted into feedback power as much as possible), so as to reduce the loss of the kinetic energy of the vehicle in the braking process and improve the utilization rate of the kinetic energy of the vehicle in the braking process.

[0057] If it is determined that the braking demand power of the vehicle is not greater than the allowed feedback power of the battery, a third braking torque of the motor is determined according to the braking demand power of the vehicle, and braking control is performed on the motor according to the third braking torque of the motor, so as to utilize the motor braking to meet the braking demand of the vehicle, reduce the loss of the kinetic energy of the vehicle in the braking process, and improve the utilization rate of the kinetic energy of the vehicle.

[0058] The motor braking control method provided in the embodiments of the present application can brake control the motor according to the second braking torque of the motor, which can include: determining the second cross-axis current and the second direct-axis current of the motor according to the MTPA table and the second braking torque of the motor, and brake controlling the motor according to the second cross-axis current and the second direct-axis current of the motor.

[0059] The motor braking control method provided in the embodiments of the present application can brake control the motor according to the third braking torque of the motor, which can include: determining the third cross-axis current and the third direct-axis current of the motor according to the MTPA table and the third braking torque of the motor, and brake controlling the motor according to the third cross-axis current and the third direct-axis current of the motor.

[0060] In the embodiments of the present application, the MTPA (maximum torque current ratio) table of the motor can be acquired in advance.

[0061] On the basis of the above, when brake controlling the motor according to the second braking torque of the motor, the MTPA table of the motor can be queried according to the second braking torque of the motor, the second cross-axis current and the second direct-axis current of the motor corresponding to the second braking torque of the motor are acquired from the MTPA table, and then the motor can be brake controlled according to the acquired second cross-axis current and second direct-axis current of the motor, so as to improve the accuracy of the motor brake control. The process of brake controlling the motor according to the second cross-axis current and the second direct-axis current of the motor can specifically be: acquiring the three-phase current of the inverter, acquiring the current cross-axis current and the current direct-axis current of the motor according to the three-phase current of the inverter, brake controlling the motor according to the current cross-axis current and the second cross-axis current of the motor, and the current direct-axis current and the second direct-axis current of the motor, so as to realize the closed-loop feedback brake control of the motor, thereby enabling the motor to accurately brake run according to the determined second cross-axis current and second direct-axis current, so as to improve the motor brake running performance.

[0062] In addition, when the motor is controlled to brake according to the third brake torque of the motor, the MTPA table of the motor can be inquired according to the third brake torque of the motor, the third quadrature-axis current and the third direct-axis current of the motor corresponding to the third brake torque of the motor can be obtained from the MTPA table, and then the motor can be controlled to brake according to the obtained third quadrature-axis current and third direct-axis current of the motor, so as to improve the accuracy of the motor braking control. The process of controlling the motor to brake according to the third quadrature-axis current and the third direct-axis current of the motor can be specifically: obtaining the three-phase current of the inverter, obtaining the current quadrature-axis current and the current direct-axis current of the motor according to the three-phase current of the inverter, and controlling the motor to brake according to the current quadrature-axis current of the motor and the third quadrature-axis current of the motor, and the current direct-axis current of the motor and the third direct-axis current of the motor, so as to realize the closed-loop feedback braking control of the motor, so that the motor can accurately brake according to the determined third quadrature-axis current and third direct-axis current, so as to improve the motor braking performance.

[0063] Referring to Figure 5 The flowchart of another motor braking control method provided by the embodiment of the application is shown, and the motor braking control method provided by the embodiment of the application comprises the following steps: when the braking demand power of the vehicle is less than the sum of the battery allowed feedback power and the heating demand power of the vehicle, the quadrature-axis current and the direct-axis current of the motor are controlled according to the braking demand power of the vehicle, the battery allowed feedback power and the heating demand power of the vehicle, so as to preferentially convert the kinetic energy of the vehicle recovered by the motor into electric energy for charging the power battery in the vehicle, comprising: if the braking demand power of the vehicle is greater than the battery allowed feedback power, the fourth brake torque of the motor is determined according to the battery allowed feedback power; the fourth quadrature-axis current and the fourth direct-axis current of the motor are determined according to the difference between the fourth brake torque of the motor, the braking demand power of the vehicle and the battery allowed feedback power; and the motor is controlled to brake according to the fourth quadrature-axis current and the fourth direct-axis current of the motor, so as to preferentially convert the kinetic energy of the vehicle recovered by the motor into electric energy for charging the power battery in the vehicle.

[0064] In the embodiment of the present application, when the braking demand power of the vehicle is less than the sum of the battery allowed feedback power and the heating demand power of the vehicle, the specific process of controlling the quadrature axis current and the direct axis current of the motor according to the braking demand power of the vehicle, the battery allowed feedback power and the heating demand power of the vehicle, so as to preferentially convert the kinetic energy of the vehicle recovered by the motor into heat energy for heating the system in the vehicle which has heating demand, when the vehicle has heating demand, can be: when the braking demand power of the vehicle is less than the sum of the battery allowed feedback power and the heating demand power of the vehicle, if the braking demand power of the vehicle is greater than the battery allowed feedback power, the fourth braking torque of the motor is determined according to the battery allowed feedback power, the difference between the braking demand power of the vehicle and the battery allowed feedback power (i.e. the braking demand power of the vehicle minus the battery allowed feedback power) is calculated, the fourth quadrature axis current and the fourth direct axis current of the motor are determined according to the fourth braking torque of the motor and the difference between the braking demand power of the vehicle and the battery allowed feedback power, and then the motor is controlled to brake according to the fourth quadrature axis current and the fourth direct axis current of the motor, so as to control the motor to operate in the low efficiency area by adjusting the distribution of the quadrature axis current and the direct axis current of the motor, preferentially convert the kinetic energy of the vehicle recovered by the motor into electric energy for charging the power battery in the vehicle, and convert the remaining kinetic energy into heat energy for heating the vehicle, so that the kinetic energy of the vehicle recovered by the motor braking is preferentially converted into electric energy to preferentially meet the charging demand of the power battery, and the remaining kinetic energy of the vehicle is converted into heat energy to heat the vehicle, thereby improving the utilization rate of the recovered kinetic energy and prolonging the driving range of the vehicle as much as possible.

[0065] The motor is controlled to brake according to the fourth quadrature axis current and the fourth direct axis current of the motor, and the specific process can be: the three-phase current of the inverter is obtained, the current quadrature axis current and the current direct axis current of the motor are determined according to the three-phase current, and the motor is controlled to brake according to the current quadrature axis current and the fourth quadrature axis current of the motor and the current direct axis current and the fourth direct axis current of the motor, so as to realize the closed-loop feedback control of the motor braking control, so that the motor can accurately brake according to the fourth quadrature axis current and the fourth direct axis current, thereby improving the motor braking operation performance.

[0066] It should be noted that when the braking demand power of the vehicle is equal to the sum of the battery allowed feedback power and the heating demand power of the vehicle, the motor recovered kinetic energy of the vehicle can also be converted into heat energy for heating the system in the vehicle which has heating demand and electric energy for charging the power battery in the vehicle according to the above control method, so as to meet the heating demand and the charging demand of the power battery.

[0067] The motor braking control method provided in the embodiments of the present application determines the fourth quadrature axis current and the fourth direct axis current of the motor according to the fourth braking torque of the motor, the braking demand power of the vehicle and the difference between the battery allowable feedback power, and can include: determining the available heating power according to the difference between the braking demand power of the vehicle and the battery allowable feedback power; determining the fourth quadrature axis current and the fourth direct axis current of the motor according to the available heating power and the fourth braking torque of the motor.

[0068] In the embodiments of the present application, the process of determining the fourth quadrature axis current and the fourth direct axis current of the motor according to the difference between the braking demand power of the vehicle and the battery allowable feedback power and the fourth braking torque of the motor can be: determining the available heating power according to the difference between the braking demand power of the vehicle and the battery allowable feedback power, i.e. the available heating power = the braking demand power of the vehicle - the battery allowable feedback power, that is, determining the difference between the braking demand power of the vehicle and the battery allowable feedback power as the available heating power, at this time, the available heating power is the power used to heat the system in the vehicle that has heating demand. Then, the fourth quadrature axis current and the fourth direct axis current of the motor can be determined according to the available heating power and the fourth braking torque of the motor, so as to recover the kinetic energy of the vehicle by using the motor and make the recovered kinetic energy of the vehicle preferentially meet the battery charging demand, and the remaining kinetic energy recovered can be converted into heat energy to heat the system in the vehicle that has heating demand.

[0069] The motor braking control method provided in the embodiments of the present application determines the fourth quadrature axis current and the fourth direct axis current of the motor according to the available heating power and the fourth braking torque of the motor, and can include: determining the first quadrature axis current and the first direct axis current of the motor according to the second mapping relationship obtained by pre-calibration, the available heating power and the fourth braking torque of the motor; the second mapping relationship is the corresponding relationship among the available heating power, the motor braking torque, the motor direct axis current and the motor quadrature axis current.

[0070] In the embodiments of the present application, the mapping relationship among the available heating power, the motor braking torque, the motor direct axis current and the motor quadrature axis current (i.e. the second mapping relationship obtained by pre-calibration, at this time, the available heating power is the power used to heat the system in the vehicle that has heating demand) can be obtained by pre-calibration, and when the fourth quadrature axis current and the fourth direct axis current of the motor are determined according to the available heating power and the fourth braking torque of the motor, the second mapping relationship obtained by pre-calibration can be queried according to the available heating power and the fourth braking torque of the motor, so as to determine the fourth quadrature axis current and the fourth direct axis current corresponding to the available heating power and the fourth braking torque of the motor.

[0071] In the above manner, the determination efficiency, convenience and accuracy of the fourth quadrature axis current and the fourth direct axis current of the motor can be improved.

[0072] The motor braking control method provided in the embodiments of the present application can further include: if the braking demand power of the vehicle is greater than the battery allowed feedback power and the vehicle has no heating demand, determining a fifth braking torque of the motor according to the battery allowed feedback power, determining a second mechanical braking power according to the braking demand power of the vehicle and the battery allowed feedback power, sending the second mechanical braking power to the braking system, and performing braking control on the motor according to the fifth braking torque of the motor, so that the braking system and the motor jointly brake; if the braking demand power of the vehicle is not greater than the battery allowed feedback power and the vehicle has no heating demand, determining a sixth braking torque of the motor according to the braking demand power of the vehicle, and performing braking control on the motor according to the sixth braking torque of the motor.

[0073] In the embodiments of the present application, when judging whether the braking demand power of the vehicle is greater than the battery allowed feedback power and whether the vehicle has a heating demand, if it is determined that the braking demand power of the vehicle is greater than the battery allowed feedback power and the vehicle has no heating demand, the fifth braking torque of the motor can be determined according to the battery allowed feedback power, and braking control can be performed on the motor according to the fifth braking torque of the motor. Specifically, the fifth cross-axis current and the fifth direct-axis current of the motor can be determined according to the MTPA table and the fifth braking torque of the motor, and braking control can be performed on the motor according to the fifth cross-axis current and the fifth direct-axis current of the motor (specifically, the three-phase current of the inverter can be obtained, the current cross-axis current and the current direct-axis current of the motor can be determined according to the three-phase current of the inverter, and braking control can be performed on the motor according to the current cross-axis current and the fifth cross-axis current, and the current direct-axis current and the fifth direct-axis current), so that the motor brakes according to the battery allowed feedback power. Moreover, the second mechanical braking power can be determined according to the braking demand power of the vehicle and the battery allowed feedback power. Specifically, the second mechanical braking power = the braking demand power of the vehicle - the battery allowed feedback power. Then, the determined second mechanical braking power is sent to the braking system in the vehicle (if the IPB exists in the vehicle, the determined second mechanical braking power can be sent to the IPB in the vehicle), so that the braking system in the vehicle mechanically brakes according to the second mechanical braking power. That is, when the braking demand power of the vehicle is greater than the battery allowed feedback power and the vehicle has no heating demand, the braking system and the motor can jointly brake, so as to well meet the braking demand of the vehicle. Moreover, in this process, the motor brakes according to the maximum braking capability to recover the kinetic energy of the vehicle and convert it into electric energy (i.e., the braking power is converted into feedback power as much as possible), so as to reduce the loss of the kinetic energy of the vehicle in the braking process and improve the utilization rate of the kinetic energy of the vehicle in the braking process.

[0074] If it is determined that the braking demand power of the vehicle is not greater than the allowable feedback power of the battery and there is no heating demand of the vehicle, a sixth braking torque of the motor can be determined according to the braking demand power of the vehicle, and the motor is controlled to brake according to the sixth braking torque of the motor. Specifically, the sixth quadrature axis current and the sixth direct axis current of the motor can be determined according to the MTPA table and the sixth braking torque of the motor, the motor is controlled to brake according to the sixth quadrature axis current and the sixth direct axis current of the motor (specifically, the three-phase current of the inverter can be obtained, the current quadrature axis current and the current direct axis current of the motor are determined according to the three-phase current of the inverter, and the motor is controlled to brake according to the current quadrature axis current and the sixth quadrature axis current, and the current direct axis current and the sixth direct axis current), so as to brake the motor to meet the braking demand of the vehicle, and convert all the kinetic energy recovered by the motor braking into electric energy to charge the power battery, so as to improve the utilization rate of the kinetic energy of the vehicle, increase the electric energy of the power battery, and as far as possible, prolong the driving range of the vehicle.

[0075] In addition, after determining that the braking demand power of the vehicle is not greater than the battery allowed feedback power and the vehicle has a heating demand, if it is determined that the heating demand power of the vehicle is less than the braking demand power of the vehicle, the motor cross-axis current and the motor direct-axis current can be controlled to preferentially convert the recovered kinetic energy into heat energy to heat the system in the vehicle that has a heating demand, and the remaining recovered kinetic energy can be converted into electric energy to charge the power battery in the vehicle. Specifically, a ninth braking torque of the motor can be determined according to the difference between the braking demand power of the vehicle and the heating demand power of the vehicle, the ninth cross-axis current and the ninth direct-axis current of the motor can be determined according to the pre-labeled mapping relationship (i.e., the pre-labeled corresponding relationship among the heating demand power, the motor braking torque, the motor cross-axis current and the motor direct-axis current), the ninth braking torque of the motor, and the heating demand power, and the motor is controlled to brake according to the ninth direct-axis current and the ninth cross-axis current of the motor. After determining that the braking demand power of the vehicle is not greater than the battery allowed feedback power and the vehicle has a heating demand, if it is determined that the heating demand power of the vehicle is not less than the braking demand power of the vehicle, the motor cross-axis current and the motor direct-axis current can be controlled to make the motor recover the kinetic energy, and the kinetic energy recovered by the motor is all converted into heat energy to preferentially convert the kinetic energy recovered by the motor into heat energy for heating the system in the vehicle that has a heating demand, or a part of the kinetic energy recovered by the motor can be converted into heat energy for heating the system in the vehicle that has a heating demand, and a part of the kinetic energy recovered by the motor can be converted into electric energy for charging the power battery in the vehicle. Specifically, a second preset battery recovery power (which can be less than the braking demand power of the vehicle) can be set in advance, a tenth braking torque of the motor can be determined according to the second preset battery recovery power, a tenth cross-axis current and a tenth direct-axis current of the motor can be determined according to the difference between the braking demand power of the vehicle and the second preset battery recovery power and the tenth braking torque of the motor, and the motor is controlled to brake according to the tenth cross-axis current and the tenth direct-axis current of the motor.

[0076] Of course, when it is determined that the braking demand power of the vehicle is not greater than the battery allowed feedback power, a sixth braking torque of the motor can be determined according to the braking demand power, and the motor is controlled to brake according to the sixth braking torque of the motor to satisfy the braking demand of the vehicle by using the motor, and the kinetic energy recovered by the motor is all converted into electric energy to charge the power battery, thereby improving the utilization rate of the kinetic energy of the vehicle and increasing the electric energy of the power battery.

[0077] The motor braking control method provided in the embodiments of the present application controls the cross-axis current and the direct-axis current of the motor according to the braking demand power of the vehicle, the allowed feedback power of the battery and the heating demand power of the vehicle, so that the motor operates in the low-efficiency region to recover the kinetic energy of the vehicle and convert the kinetic energy into electric energy for charging the power battery in the vehicle and thermal energy for heating the system having the heating demand in the vehicle. The motor braking control method can comprise the following steps: when the braking demand power of the vehicle is greater than the sum of the allowed feedback power of the battery and the heating demand power of the vehicle, determining the seventh braking torque of the motor according to the allowed feedback power of the battery, determining the seventh cross-axis current and the seventh direct-axis current of the motor according to the seventh braking torque of the motor and the heating demand power of the vehicle, and determining the third mechanical braking power according to the braking demand power of the vehicle, the heating demand power of the vehicle and the allowed feedback power of the battery; sending the third mechanical braking power to the braking system, and braking controlling the motor according to the seventh cross-axis current and the seventh direct-axis current of the motor, so that the braking system and the motor jointly brake.

[0078] In the embodiments of the present application, when the cross-axis current and the direct-axis current of the motor are controlled according to the braking demand power of the vehicle, the allowed feedback power of the battery and the heating demand power of the vehicle, so that the motor operates in the low-efficiency region to recover the kinetic energy of the vehicle and convert the kinetic energy into electric energy for charging the power battery in the vehicle and thermal energy for heating the system having the heating demand in the vehicle, if the braking demand power of the vehicle is greater than the sum of the allowed feedback power of the battery and the heating demand power of the vehicle, the motor can exert the maximum braking capacity according to the allowed feedback power of the battery and the heating demand power of the vehicle, so as to meet the charging demand of the power battery and the heating demand of the vehicle, and the braking system is intervened to recover the remaining kinetic energy, so as to enhance the braking capacity of the motor and meet the braking demand of the vehicle.

[0079] Specifically, the seventh braking torque of the motor can be determined according to the allowed feedback power of the battery, and the seventh cross-axis current and the seventh direct-axis current of the motor can be determined according to the seventh braking torque of the motor and the heating demand power of the vehicle, so that the kinetic energy recovered by the motor during braking can be converted into electric energy meeting the charging demand of the power battery and thermal energy meeting the heating demand of the vehicle. Moreover, the third mechanical braking power can be determined according to the braking demand power of the vehicle, the heating demand power of the vehicle and the allowed feedback power of the battery, i.e., the third mechanical braking power = the braking demand power of the vehicle - the allowed feedback power of the battery - the heating demand power of the vehicle. Then, the calculated third mechanical braking power can be sent to the braking system (if the IPB exists in the vehicle, the determined third mechanical braking power can be sent to the IPB in the vehicle), and the motor can be braking controlled according to the determined seventh cross-axis current and seventh direct-axis current of the motor, so that the braking system.

[0080] The seventh cross-axis current and the seventh direct-axis current of the motor can be determined according to the first mapping relationship obtained through pre-calibration, the seventh braking torque of the motor and the heating demand power of the vehicle, so as to improve the accuracy and efficiency of determination of the seventh cross-axis current and the seventh direct-axis current of the motor. When the motor is controlled to brake according to the seventh cross-axis current and the seventh direct-axis current of the motor, the three-phase current of the inverter can be obtained, the current cross-axis current and the current direct-axis current of the motor can be determined according to the three-phase current of the inverter, and the motor can be controlled to brake according to the current cross-axis current and the seventh cross-axis current and the current direct-axis current and the seventh direct-axis current, so that the motor can be controlled to brake in a closed-loop feedback control mode, so that the motor can accurately brake according to the determined seventh cross-axis current and seventh direct-axis current, thereby improving the motor braking performance.

[0081] The motor braking control method provided in the embodiments of the present application can be used for a vehicle having a system requiring heating.

[0082] In the embodiments of the present application, the system requiring heating in the vehicle can include a power battery, and of course, can also include a passenger cabin system and / or an air conditioning system and other systems requiring heating.

[0083] On the basis of the above, if the ambient temperature is low, the allowed feedback power of the power battery at this time will be small, which can be less than the vehicle braking demand power, and it can be determined that the vehicle has a heating demand. At this time, the vehicle braking control can be performed according to the above process, so that the vehicle kinetic energy recovered by motor braking can not only be converted into electric energy to charge the power battery, but also be converted into heat energy and transmitted to the power battery through the heat conduction circuit to heat the power battery, so as to rapidly increase the temperature of the power battery in a low-temperature environment, thereby improving the charging and discharging performance of the power battery, and further improving the allowed feedback power of the power battery. The increase of the allowed feedback power of the battery can make the motor have greater braking capacity, so as to recover more vehicle kinetic energy, that is, the braking capacity of the vehicle in a low-temperature environment can be further improved through the foregoing process.

[0084] When the system requiring heating in the vehicle includes a power battery and other systems, the heat energy converted from the vehicle kinetic energy recovered by the motor braking can first meet the heating demand of the power battery, and if there is excess heat, it can meet the heating demand of other systems requiring heating. Of course, the converted heat energy can also flow to each system requiring heating at the same time to heat each system requiring heating at the same time.

[0085] The motor braking control method provided in the embodiments of the present application can further include: obtaining the temperature of the power battery, and determining whether the temperature of the power battery exceeds a temperature threshold; if yes, it is determined that the power battery has no heating demand, and the step of obtaining the regenerative power allowed by the battery and the heating demand power of the vehicle is returned to.

[0086] In the embodiments of the present application, on the basis of the system having a heating demand in the vehicle including the power battery, after the control of the quadrature axis current and the direct axis current of the motor according to the braking demand power of the vehicle, the regenerative power allowed by the battery and the heating demand power of the vehicle, so that the motor operates in the low-efficiency area to recover the kinetic energy of the vehicle and convert it into the electric energy for charging the power battery in the vehicle and the thermal energy for heating the system having a heating demand in the vehicle, the temperature of the power battery can be obtained, and specifically, the temperature of the power battery can be obtained in real time or at a fixed time. After obtaining the temperature of the power battery, it can be determined whether the temperature of the power battery exceeds a temperature threshold, wherein the temperature threshold is determined according to the normal working temperature of the power battery, for example, the temperature threshold can be equal to the normal working temperature of the power battery, so as to enable the power battery to work at the normal working temperature, thereby improving the charging and discharging performance of the power battery.

[0087] If it is determined that the temperature of the power battery does not exceed the temperature threshold, the power battery can continue to be heated by the thermal energy generated during motor braking, and the step of obtaining the regenerative power allowed by the battery and the heating demand power of the vehicle is returned to, so as to dynamically adjust the regenerative power and the heat generation power of the motor based on the obtained parameters, thereby meeting the heating demand under various working conditions.

[0088] If it is determined that the temperature of the power battery exceeds the temperature threshold, it can be determined that the power battery has been heated to a suitable temperature, that is, it can be determined that the power battery has no heating demand. At this time, the vehicle can or can not include other systems having a heating demand. Therefore, the electric drive system can return to execute the step of obtaining the regenerative power allowed by the battery and the heating demand power of the vehicle, so as to dynamically adjust the regenerative power and the heat generation power of the motor based on the obtained parameters, thereby meeting the heating demand under various working conditions.

[0089] The embodiments of the present application also provide a motor braking control device, which is shown in Figure 6 which shows a structural schematic diagram of a motor control device provided by the embodiments of the present application, and can include: a first obtaining module 61, configured to obtain the braking demand power of the vehicle; and a control module 62, configured to control the quadrature axis current and the direct axis current of the motor according to the braking demand power of the vehicle, so that the motor recovers the kinetic energy of the vehicle and converts it into thermal energy.

[0090] The motor control device provided by the embodiment of the application can further comprise a second acquisition module configured to acquire the battery-allowed feedback power and the heating demand power of the vehicle when the braking demand power of the vehicle is acquired.

[0091] The control module 62 can comprise a control submodule configured to control the quadrature-axis current and the direct-axis current of the motor according to the braking demand power of the vehicle, the battery-allowed feedback power and the heating demand power of the vehicle, so that the motor operates in the low-efficiency region to recover the kinetic energy of the vehicle and convert the kinetic energy into electric energy for charging the power battery in the vehicle and heat energy for heating the system in the vehicle that has a heating demand.

[0092] The motor control device provided by the embodiment of the application can further comprise a second acquisition module configured to acquire the battery-allowed feedback power and the heating demand power of the vehicle when the braking demand power of the vehicle is acquired.

[0093] The motor control device provided by the embodiment of the application can further comprise a second acquisition module configured to acquire the battery-allowed feedback power and the heating demand power of the vehicle when the braking demand power of the vehicle is acquired.

[0094] The motor control device provided by the embodiment of the application can further comprise a second acquisition module configured to acquire the battery-allowed feedback power and the heating demand power of the vehicle when the braking demand power of the vehicle is acquired.

[0095] The motor control device provided in the embodiment of the present application, the second determining subunit determines the first quadrature axis current and the first direct axis current of the motor according to the heating demand power of the vehicle and the first braking torque of the motor, and is specifically configured to determine the first quadrature axis current and the first direct axis current of the motor according to the first mapping relationship obtained by pre-calibration, the heating demand power of the vehicle and the first braking torque of the motor; the first mapping relationship is a corresponding relationship among the vehicle heating demand power, the motor braking torque, the motor direct axis current and the motor quadrature axis current.

[0096] The motor control device provided in the embodiment of the present application, the control sub-module further can comprise: a second control unit, configured to, if the vehicle has no heating demand and if the braking demand power of the vehicle is greater than the battery allowed feedback power, determine the second braking torque of the motor according to the battery allowed feedback power, determine the first mechanical braking power according to the braking demand power of the vehicle and the battery allowed feedback power, send the first mechanical braking power to the braking system, and brake control the motor according to the second braking torque of the motor, so that the braking system and the motor jointly brake; a third control unit, configured to, if the vehicle has no heating demand and if the braking demand power of the vehicle is not greater than the battery allowed feedback power, determine the third braking torque of the motor according to the braking demand power of the vehicle, and brake control the motor according to the third braking torque of the motor.

[0097] The motor control device provided in the embodiment of the present application, the second control unit can comprise: a second control subunit, configured to determine the second quadrature axis current and the second direct axis current of the motor according to the MTPA table and the second braking torque of the motor, and brake control the motor according to the second quadrature axis current and the second direct axis current of the motor; a third control unit can comprise: a third control subunit, configured to determine the third quadrature axis current and the third direct axis current of the motor according to the MTPA table and the third braking torque of the motor, and brake control the motor according to the third quadrature axis current and the third direct axis current of the motor.

[0098] The motor control device provided in the embodiment of the present application, the first control unit can comprise: a third determining subunit, configured to, if the braking demand power of the vehicle is greater than the battery allowed feedback power, determine the fourth braking torque of the motor according to the battery allowed feedback power; a fourth determining subunit, configured to determine the fourth quadrature axis current and the fourth direct axis current of the motor according to the difference between the fourth braking torque of the motor, the braking demand power of the vehicle and the battery allowed feedback power; and a fourth control subunit, configured to brake control the motor according to the fourth quadrature axis current and the fourth direct axis current of the motor, so as to preferentially convert the kinetic energy of the vehicle recovered by the motor into electric energy used for charging the power battery in the vehicle.

[0099] The motor control device provided by the embodiment of the application includes a fourth determination subunit configured to determine a fourth quadrature axis current and a fourth direct axis current of the motor according to a fourth braking torque of the motor, braking demand power of the vehicle and a difference between the battery allowable feedback power, and specifically configured to determine the heating power available according to the difference between the braking demand power of the vehicle and the battery allowable feedback power; and determine the fourth quadrature axis current and the fourth direct axis current of the motor according to the heating power available and the fourth braking torque of the motor.

[0100] The motor control device provided by the embodiment of the application includes a fourth determination subunit configured to determine a fourth quadrature axis current and a fourth direct axis current of the motor according to a fourth braking torque of the motor, braking demand power of the vehicle and a difference between the battery allowable feedback power, and specifically configured to determine the heating power available according to the difference between the braking demand power of the vehicle and the battery allowable feedback power; and determine the fourth quadrature axis current and the fourth direct axis current of the motor according to the heating power available and the fourth braking torque of the motor.

[0101] The motor control device provided by the embodiment of the application includes a fourth determination subunit configured to determine a fourth quadrature axis current and a fourth direct axis current of the motor according to a fourth braking torque of the motor, braking demand power of the vehicle and a difference between the battery allowable feedback power, and specifically configured to determine the heating power available according to the difference between the braking demand power of the vehicle and the battery allowable feedback power; and determine the fourth quadrature axis current and the fourth direct axis current of the motor according to the heating power available and the fourth braking torque of the motor.

[0102] The motor control device provided by the embodiment of the application includes a fourth determination subunit configured to determine a fourth quadrature axis current and a fourth direct axis current of the motor according to a fourth braking torque of the motor, braking demand power of the vehicle and a difference between the battery allowable feedback power, and specifically configured to determine the heating power available according to the difference between the braking demand power of the vehicle and the battery allowable feedback power; and determine the fourth quadrature axis current and the fourth direct axis current of the motor according to the heating power available and the fourth braking torque of the motor.

[0103] The motor control device provided by the embodiment of the application includes a fourth determination subunit configured to determine a fourth quadrature axis current and a fourth direct axis current of the motor according to a fourth braking torque of the motor, braking demand power of the vehicle and a difference between the battery allowable feedback power, and specifically configured to determine the heating power available according to the difference between the braking demand power of the vehicle and the battery allowable feedback power; and determine the fourth quadrature axis current and the fourth direct axis current of the motor according to the heating power available and the fourth braking torque of the motor.

[0104] The motor control device provided in the embodiment of the present application, the control module 62 can further include: an acquisition submodule, configured to acquire the temperature of the power battery, and determine whether the temperature of the power battery exceeds a temperature threshold; a return execution module, configured to, if it is determined that the temperature of the power battery exceeds the temperature threshold, determine that the power battery has no heating demand, and return to execute the steps of acquiring the battery-allowed feedback power and the heating demand power of the vehicle.

[0105] The embodiment of the present application further provides an electric drive system, referring to Figure 7 which shows a structural schematic diagram of an electric drive system provided by the embodiment of the present application. The electric drive system provided by the embodiment of the present application can include a VCU, a motor controller connected with the VCU, and a motor connected with the motor controller. The VCU is configured to acquire the braking demand power of the vehicle, and control the quadrature axis current and the direct axis current of the motor through the motor controller according to the braking demand power of the vehicle, so that the motor recovers the kinetic energy of the vehicle and converts it into heat energy.

[0106] The electric drive system provided by the embodiment of the present application can specifically include a VCU (vehicle control unit), a motor controller (MCU), and a motor. The VCU and the motor controller are connected through a CAN (controller area network) bus for communication. The motor controller is connected with the motor. The embodiment of the present application does not need to change the hardware topology of the electric drive system, but only needs to change the strategy in the VCU and the motor controller. The VCU in the electric drive system can calculate the braking demand power of the vehicle according to the depth of the brake pedal being stepped on and the current vehicle speed information, or can directly acquire the braking demand power of the vehicle. According to the acquired braking demand power of the vehicle, the quadrature axis current and the direct axis current of the motor can be controlled through the motor controller, so that the motor recovers the kinetic energy of the vehicle and converts it into heat energy.

[0107] The electric drive system provided by the embodiment of the present application can further include a BMS connected with the VCU.

[0108] The VCU is further configured to acquire the heating demand power of the vehicle when acquiring the braking demand power of the vehicle, and acquire the battery-allowed feedback power from the BMS. The VCU controls the quadrature axis current and the direct axis current of the motor through the motor controller according to the braking demand power of the vehicle, so that the motor recovers the kinetic energy of the vehicle and converts it into heat energy. Specifically, the quadrature axis current and the direct axis current of the motor are controlled through the motor controller according to the braking demand power of the vehicle, the battery-allowed feedback power, and the heating demand power of the vehicle, so that the motor operates in a low-efficiency zone, to recover the kinetic energy of the vehicle and convert it into electric energy for charging the power battery in the vehicle and heat energy for heating the system in the vehicle that has a heating demand.

[0109] In this application, the electric drive system may include a Battery Management System (BMS) connected to the power battery. The BMS and the Vehicle Control Unit (VCU) communicate via a CAN bus. When acquiring the vehicle's braking power requirement, the VCU can also acquire the battery's allowable regenerative power from the BMS. Specifically, it can directly acquire the allowable regenerative power from the BMS, or it can acquire the maximum allowable regenerative current and maximum regenerative voltage of the power battery from the BMS, and calculate the allowable regenerative power based on these parameters. Furthermore, it determines whether the vehicle has a heating requirement, and if so, acquires the vehicle's heating power requirement. Then, based on the vehicle's braking power requirement, the battery's allowable regenerative power, and the vehicle's heating power requirement, the VCU controls the motor's quadrature-axis current and direct-axis current via the motor controller, causing the motor to operate in an inefficient region to recover the vehicle's kinetic energy and convert it into electrical energy for charging the vehicle's power battery and thermal energy for heating systems within the vehicle that require heating.

[0110] The above method dynamically adjusts the current distribution between the quadrature and direct axes of the motor according to the heating command from the VCU. This allows the motor to consume braking power according to the heating power demand while maintaining constant feedback power, converting it into heat energy and thus increasing the vehicle's braking power. The additional heat generated can be used to heat the power battery and other systems in the vehicle that require heating in low-temperature environments. The specific braking energy flow is as follows: Figure 2 As shown, the vehicle's kinetic energy E is increased through electric motor braking. m Electrical energy E that can be converted into feedback e And the heat energy E lost through the copper and iron losses of the motor heat If the feedback of electrical energy E is maintained e The heat energy E consumed by the increased copper and iron losses of the motor remains unchanged. heat This can increase the vehicle's kinetic energy consumed by the motor, thus increasing the vehicle's braking capacity.

[0111] The above-mentioned motor braking control method does not require changes to the system structure and the hardware topology of the electric drive system; only the software control strategies in the VCU and motor controller need to be changed.

[0112] The electric drive system provided in the embodiments of the present application is used for controlling the quadrature axis current and the direct axis current of the motor by the motor controller according to the braking demand power of the vehicle, the allowed feedback power of the battery and the heating demand power of the vehicle, so that the motor operates in the low efficiency area, and the kinetic energy of the vehicle is recovered and converted into the electric energy for charging the power battery in the vehicle and the heat energy for heating the system with heating demand in the vehicle. Specifically, when the braking demand power of the vehicle is less than the sum of the allowed feedback power of the battery and the heating demand power of the vehicle, the quadrature axis current and the direct axis current of the motor are controlled by the motor controller according to the braking demand power of the vehicle, the allowed feedback power of the battery and the heating demand power of the vehicle, so that the kinetic energy of the vehicle recovered by the motor is converted into the electric energy for charging the power battery in the vehicle or the heat energy for heating the system with heating demand in the vehicle.

[0113] In the embodiments of the present application, when the quadrature axis current and the direct axis current of the motor are controlled by the motor controller according to the braking demand power of the vehicle, the allowed feedback power of the battery and the heating demand power of the vehicle, if the braking demand power of the vehicle is less than the sum of the allowed feedback power of the battery and the heating demand power of the vehicle, the quadrature axis current and the direct axis current of the motor are controlled by the motor controller, so that the kinetic energy of the vehicle recovered by the motor is converted into the electric energy for charging the power battery in the vehicle or the heat energy for heating the system with heating demand in the vehicle.

[0114] The electric drive system provided in the embodiments of the present application is used for controlling the quadrature axis current and the direct axis current of the motor by the motor controller according to the braking demand power of the vehicle, the allowed feedback power of the battery and the heating demand power of the vehicle, so that the motor operates in the low efficiency area, and the kinetic energy of the vehicle is recovered and converted into the electric energy for charging the power battery in the vehicle and the heat energy for heating the system with heating demand in the vehicle. Specifically, when the braking demand power of the vehicle is less than the sum of the allowed feedback power of the battery and the heating demand power of the vehicle, the quadrature axis current and the direct axis current of the motor are controlled by the motor controller according to the braking demand power of the vehicle, the allowed feedback power of the battery and the heating demand power of the vehicle, so that the kinetic energy of the vehicle recovered by the motor is converted into the electric energy for charging the power battery in the vehicle or the heat energy for heating the system with heating demand in the vehicle. Specifically, when the braking demand power of the vehicle is less than the sum of the allowed feedback power of the battery and the heating demand power of the vehicle, the quadrature axis current and the direct axis current of the motor are controlled by the motor controller according to the braking demand power of the vehicle, the allowed feedback power of the battery and the heating demand power of the vehicle, so that the kinetic energy of the vehicle recovered by the motor is converted into the electric energy for charging the power battery in the vehicle or the heat energy for heating the system with heating demand in the vehicle.

[0115] In the embodiment of the present application, when the kinetic energy of the vehicle is preferentially converted into thermal energy for heating the system in the vehicle that has a heating demand by the motor, if the heating demand power is less than the braking demand power, the VCU can calculate the first braking torque of the motor through the braking power distribution strategy, specifically, the first braking torque of the vehicle is determined according to the difference between the braking demand power of the vehicle and the heating demand power of the vehicle. Then, the heating demand power and the first braking torque of the motor can be sent to the motor controller in the form of a message. After the motor controller obtains the heating demand power of the vehicle and the first braking torque of the motor sent by the VCU, the motor controller controls the working condition point of the motor according to the direct and quadrature axis current distribution strategy. Specifically, the first direct and quadrature axis currents of the motor are determined according to the heating demand power and the first braking torque of the motor, and the motor is controlled to brake according to the first direct and quadrature axis currents of the motor, so that the kinetic energy of the vehicle is preferentially converted into thermal energy for heating the system in the vehicle that has a heating demand, and the remaining recovered kinetic energy is converted into electrical energy for charging the power battery. The thermal energy generated by the motor braking flows to the system in the vehicle that has a heating demand through the heat conduction circuit to heat the system in the vehicle that has a heating demand, and the electrical energy generated by the motor braking is fed back to the power battery to charge the power battery.

[0116] The motor controller brakes the motor according to the first direct and quadrature axis currents of the motor, specifically for obtaining the three-phase current of the inverter connected with the motor and the power battery; determining the current direct and quadrature axis currents of the motor according to the three-phase current; and braking the motor according to the current direct and quadrature axis currents of the motor and the first direct and quadrature axis currents of the motor.

[0117] The electric drive system provided by the embodiment of the present application can further include an inverter, the positive and negative poles of the power battery are connected with the direct current bus of the inverter, the three-phase lines of the inverter are connected with the motor, the shaft end of the rotor of the motor is provided with a position sensor, the position of the motor is collected and fed back to the motor controller. The motor controller controls the power module of the inverter to work by outputting a PWM (pulse width modulation) driving signal, and converts direct current into alternating current to drive the motor to work. The alternating current end of the inverter can be provided with a current sensor connected with the motor controller, the current sensor can collect the three-phase current of the inverter and send it to the motor controller. The motor controller determines the current direct and quadrature axis currents of the motor according to the three-phase current of the inverter, and then brakes the motor according to the current direct and quadrature axis currents of the motor and the first direct and quadrature axis currents of the motor, that is, the braking control of the motor is realized in a closed-loop feedback control mode.

[0118] The electric drive system provided in the embodiment of the application, the motor controller determines the first quadrature axis current and the first direct axis current of the motor according to the heating demand power and the first braking torque of the motor, specifically for determining the first quadrature axis current and the first direct axis current of the motor according to the first mapping relationship obtained by pre-calibration, the heating demand power of the vehicle and the first braking torque of the motor; the first mapping relationship is the corresponding relationship among the heating demand power of the vehicle, the braking torque of the motor, the direct axis current of the motor and the quadrature axis current of the motor.

[0119] The electric drive system provided in the embodiment of the application, if the vehicle has no heating demand, the VCU is further used for, if the braking demand power of the vehicle is greater than the battery allowed feedback power, determining the second braking torque of the motor according to the battery allowed feedback power, and determining the first mechanical braking power according to the braking demand power of the vehicle and the battery allowed feedback power, sending the first mechanical braking power to the braking system, sending the second braking torque of the motor to the motor controller, and braking controlling the motor according to the second braking torque of the motor by the motor controller, so that the braking system and the motor jointly brake; if the braking demand power of the vehicle is not greater than the battery allowed feedback power, determining the third braking torque of the motor according to the braking demand power of the vehicle, and sending the third braking torque of the motor to the motor controller, and braking controlling the motor according to the third braking torque of the motor by the motor controller.

[0120] The electric drive system provided in the embodiment of the application, the motor controller brakes controls the motor according to the second braking torque of the motor, specifically for determining the second quadrature axis current and the second direct axis current of the motor according to the MTPA table and the second braking torque of the motor, and braking controlling the motor according to the second quadrature axis current and the second direct axis current of the motor; the motor controller brakes controls the motor according to the third braking torque of the motor, specifically for determining the third quadrature axis current and the third direct axis current of the motor according to the MTPA table and the third braking torque of the motor, and braking controlling the motor according to the third quadrature axis current and the third direct axis current of the motor.

[0121] The electric drive system provided by the embodiment of the application is characterized in that when the braking demand power of the vehicle is less than the sum of the allowed feedback power of the battery and the heating demand power of the vehicle, the motor controller controls the quadrature-axis current and the direct-axis current of the motor according to the braking demand power of the vehicle, the allowed feedback power of the battery and the heating demand power of the vehicle, so as to preferentially convert the kinetic energy of the vehicle recovered by the motor into electric energy for charging the power battery in the vehicle.

[0122] The electric drive system provided by the embodiment of the application is characterized in that the motor controller determines the fourth quadrature-axis current and the fourth direct-axis current of the motor according to the difference between the braking demand power of the vehicle and the allowed feedback power of the battery and the fourth braking torque of the motor, and specifically, determines the available heating power according to the difference between the braking demand power of the vehicle and the allowed feedback power of the battery; and determines the fourth quadrature-axis current and the fourth direct-axis current of the motor according to the available heating power and the fourth braking torque of the motor.

[0123] The electric drive system provided by the embodiment of the application is characterized in that the motor controller determines the fourth quadrature-axis current and the fourth direct-axis current of the motor according to the available heating power and the fourth braking torque of the motor, and specifically, determines the first quadrature-axis current and the first direct-axis current of the motor according to the second mapping relationship obtained through pre-calibration, the available heating power and the fourth braking torque of the motor; and the second mapping relationship is a corresponding relationship among the available heating power, the motor braking torque, the motor direct-axis current and the motor quadrature-axis current.

[0124] The electric drive system provided by the embodiment of the application is characterized in that the VCU is further configured to: if the braking demand power of the vehicle is greater than the allowed feedback power of the battery and the vehicle has no heating demand, determine the fifth braking torque of the motor according to the allowed feedback power of the battery, and determine the second mechanical braking power according to the braking demand power of the vehicle and the allowed feedback power of the battery, send the second mechanical braking power to the braking system and send the fifth braking torque of the motor to the motor controller, and the motor controller controls the motor according to the fifth braking torque of the motor, so that the braking system and the motor jointly brake; and if the braking demand power of the vehicle is not greater than the allowed feedback power of the battery and the vehicle has no heating demand, determine the sixth braking torque of the motor according to the braking demand power of the vehicle, and send the sixth braking torque of the motor to the motor controller, and the motor controller controls the motor according to the sixth braking torque of the motor.

[0125] The electric drive system provided in the embodiment of the present application, the VCU, controls the cross-axis current and the direct-axis current of the motor through the motor controller according to the braking demand power of the vehicle, the allowed feedback power of the battery and the heating demand power of the vehicle, so that the motor operates in the low-efficiency zone, to recover the kinetic energy of the vehicle and convert it into the electric energy for charging the power battery in the vehicle and the thermal energy for heating the system in the vehicle that has a heating demand. Specifically, when the braking demand power of the vehicle is greater than the sum of the allowed feedback power of the battery and the heating demand power of the vehicle, the third mechanical braking power is determined according to the braking demand power of the vehicle, the heating demand power of the vehicle and the allowed feedback power of the battery, the seventh braking torque of the motor is determined according to the allowed feedback power of the battery, the seventh braking torque of the motor is sent to the motor controller, the seventh cross-axis current and the seventh direct-axis current of the motor are determined by the motor controller according to the seventh braking torque of the motor and the heating demand power of the vehicle, the third mechanical braking power is sent to the braking system, and the motor is controlled to brake by the motor controller according to the seventh cross-axis current and the seventh direct-axis current of the motor, so that the braking system and the motor jointly brake.

[0126] The electric drive system provided in the embodiment of the present application, the system in the vehicle that has a heating demand can include the power battery.

[0127] The electric drive system provided in the embodiment of the present application, after the VCU controls the cross-axis current and the direct-axis current according to the braking demand power of the vehicle, the allowed feedback power of the battery and the heating demand power of the vehicle, the VCU is further used to acquire the temperature of the power battery, and determine whether the temperature of the power battery exceeds the temperature threshold value. If yes, it is determined that the power battery has no heating demand, and the step of acquiring the allowed feedback power of the battery and the heating demand power of the vehicle is returned to be executed.

[0128] In order to further illustrate the braking power distribution strategy in the VCU and the cross-axis and direct-axis current distribution strategy in the motor controller, refer to Figure 8 and Figure 9 wherein, Figure 8 Fig. 1 shows a braking power distribution strategy in the VCU provided in the embodiment of the present application, Figure 9 Fig. 2 shows a cross-axis and direct-axis current distribution strategy in the motor controller provided in the embodiment of the present application, and another braking power distribution strategy in the VCU and another cross-axis and direct-axis current distribution strategy in the motor controller can be referred to Figure 5In the brake power distribution strategy, if the ambient temperature is low, resulting in that the battery allows the feedback power at this time is small, the VCU can determine the brake torque required by the motor and the brake power required to be consumed by heating according to the brake demand power, the heating demand power and the battery allows the feedback power, and sends instructions to the motor controller through the message. If there is no heating demand at present and the battery allows the feedback power is greater than or equal to the vehicle brake demand power, the brake power should be converted into feedback power as much as possible, and is fed back to the power battery through the inverter to charge the battery. If there is no heating demand at present and the brake demand power is greater than the battery allows the feedback power, the brake demand power outside the battery allows the feedback power needs to be assisted by the brake system intervention. In the direct and quadrature axis current distribution strategy, the motor controller responds to the torque instruction and the heating power instruction sent by the VCU. If there is no heating power instruction, the motor controller only needs to query the MTPA table according to the torque instruction to obtain the direct and quadrature axis current distribution. If there is a heating power instruction, the motor controller needs to obtain the direct and quadrature axis current corresponding to the brake torque and the heating power according to the pre-marked mapping relationship. The direct axis current I d The absolute value will increase, so that the stator current I s The increased current generates heat through the winding, which converts the mechanical energy of the motor shaft end into heat energy. The heat energy will flow to the power battery and other systems of the vehicle that need heat energy through the heat conduction circuit, including but not limited to the passenger cabin and the air conditioning system, as shown in Figure 3 The heat energy flowing to the power battery can heat the power battery, rapidly increase the temperature of the power battery to the normal working temperature in a low temperature environment, improve the charge and discharge performance of the battery, increase the battery allows the feedback power, and further improve the braking ability of the vehicle in a low temperature environment. And the heating power in the brake distribution strategy is adjustable, which avoids unlimitedly increasing the temperature of the motor and the heat conduction circuit, so that the electric drive system and the power battery work in the best temperature condition.

[0129] Through the above, the embodiment of the application is based on the electric drive hardware topology. By modifying the brake power distribution strategy in the VCU and the direct and quadrature axis current distribution strategy in the motor controller, the new energy vehicle can still brake with a brake power greater than the battery allows the feedback power in the case of low ambient temperature and limited battery allows the feedback power. The brake power outside the feedback power will be converted into heat energy, and the heat will flow to the power battery and other systems of the vehicle that need heating through the heat conduction circuit. The heat flowing to the power battery will be used to heat the power battery, rapidly improve the charge and discharge ability of the battery in a low temperature environment, and further improve the braking ability of the vehicle in a low temperature environment.

[0130] The embodiment of the application also provides a vehicle, which can include any of the above electric drive systems, and is used to implement the steps of any of the above motor control methods.

[0131] The motor control device, the electric drive system and the related part of the vehicle provided in the present application can refer to the detailed description of the corresponding part in the motor control method provided in the present application, and will not be described here.

[0132] It should be noted that the logic and / or steps represented in the flowcharts or otherwise described herein, for example, can be considered as a list of executable instructions for implementing logic functions, which can be embodied in any computer-readable medium for use by or in connection with an instruction execution system, apparatus or device, such as a computer-based system, a system including a processor or other system that can fetch the instructions from an instruction execution system, apparatus or device and execute the instructions, or in conjunction with these instruction execution systems, apparatus or devices. For the purpose of this specification, "computer-readable medium" can be any device that can contain, store, communicate, propagate or transport programs for use by or in connection with an instruction execution system, apparatus or device, or in conjunction with these instruction execution systems, apparatus or devices. More specific examples (non-exhaustive list) of computer-readable medium include the following: electrical connections having one or more wires (electronic devices), portable computer diskette (magnetic devices), random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), fiber optic devices, and portable compact disc read-only memory (CDROM). In addition, the computer-readable medium can even be paper or other suitable medium on which the program can be printed, as the program can be electronically obtained, for example, by optical scanning of the paper or other medium, followed by electronic conversion, interpretation or processing, if necessary, in other suitable ways, and then stored in a computer memory.

[0133] It should be understood that parts of the present application can be implemented in hardware, software, firmware or a combination thereof. In the above-described embodiments, a plurality of steps or methods can be implemented by software or firmware stored in a memory and executed by a suitable instruction execution system. For example, if implemented in hardware, and as in another embodiment, it can be implemented by any one or a combination of the following technologies known in the art: discrete logic circuit with logic gate circuit for implementing logic functions on data signals, application specific integrated circuit with suitable combination logic gate circuit, programmable gate array (PGA), field programmable gate array (FPGA) and the like.

[0134] In the description of the specification, the description of the terms "one embodiment", "some embodiments", "an example", "a specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. In the description of the specification, the illustrative description of the above terms does not necessarily mean the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0135] In addition, the terms "first", "second" are only for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the technical features indicated. Therefore, the features defined with "first", "second" can explicitly or implicitly include at least one of the features. In the description of the present application, the meaning of "a plurality of" is at least two, for example, two, three, etc., unless otherwise explicitly specified and limited.

[0136] In the present application, unless otherwise explicitly specified and limited, the terms "mounting", "connection", "connection", "fixing" and other terms should be understood in a broad sense, for example, can be fixedly connected, can also be detachably connected, or integrated; can be mechanically connected, can also be electrically connected; can be directly connected, can also be indirectly connected through an intermediate medium, can be the internal communication of two elements or the interaction relationship between two elements, unless otherwise explicitly limited. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0137] Although the embodiments of the present application have been shown and described above, it can be understood that the above embodiments are exemplary and cannot be understood as limiting the present application, and those skilled in the art can make changes, modifications, replacements and variations to the above embodiments within the scope of the present application.

Claims

1. A method of electric machine braking control, characterized by, The method comprises the following steps: obtaining the braking demand power of the vehicle, obtaining the battery allowed feedback power, and obtaining the heating demand power of the vehicle from the system in the vehicle that has a heating demand; controlling the quadrature axis current and the direct axis current of the motor according to the braking demand power of the vehicle, the battery allowed feedback power, and the heating demand power of the vehicle, so that the motor operates in the low efficiency area, recovers the kinetic energy of the vehicle, and converts the kinetic energy into electric energy for charging the power battery in the vehicle and heat energy for heating the system in the vehicle that has a heating demand; controlling the quadrature axis current and the direct axis current of the motor according to the braking demand power of the vehicle, the battery allowed feedback power, and the heating demand power of the vehicle, so that the motor operates in the low efficiency area, recovers the kinetic energy of the vehicle, and converts the kinetic energy into electric energy for charging the power battery in the vehicle and heat energy for heating the system in the vehicle that has a heating demand, comprising: when the braking demand power of the vehicle is less than the sum of the battery allowed feedback power and the heating demand power of the vehicle, controlling the quadrature axis current and the direct axis current of the motor according to the braking demand power of the vehicle, the battery allowed feedback power, and the heating demand power of the vehicle, so as to preferentially convert the kinetic energy of the vehicle recovered by the motor into heat energy for heating the system in the vehicle that has a heating demand, or preferentially convert the kinetic energy of the vehicle recovered by the motor into electric energy for charging the power battery in the vehicle; if the heating demand power of the vehicle is not less than the braking demand power of the vehicle, determining an eighth braking torque of the motor according to a first preset battery recovery power, determining an eighth quadrature axis current and an eighth direct axis current of the motor according to the difference between the braking demand power of the vehicle and the first preset battery recovery power and the eighth braking torque of the motor, and controlling the motor according to the eighth quadrature axis current and the eighth direct axis current of the motor, so as to convert part of the kinetic energy recovered by the motor into heat energy for heating the system in the vehicle that has a heating demand and part of the kinetic energy into electric energy for charging the power battery in the vehicle; wherein the first preset battery recovery power is less than the smaller one of the braking demand power of the vehicle and the battery allowed feedback power.

2. The electric motor braking control method according to claim 1, characterized by, when the braking demand power of the vehicle is less than the sum of the battery allowed feedback power and the heating demand power of the vehicle, controlling the quadrature axis current and the direct axis current of the motor according to the braking demand power of the vehicle, the battery allowed feedback power, and the heating demand power of the vehicle, so as to preferentially convert the kinetic energy of the vehicle recovered by the motor into heat energy for heating the system in the vehicle that has a heating demand, comprising: if the heating demand power of the vehicle is less than the braking demand power of the vehicle, determining a first braking torque of the motor according to the difference between the braking demand power and the heating demand power; determining first quadrature-axis current and first direct-axis current of the motor according to heating demand power of the vehicle and first braking torque of the motor; braking control of the motor according to the first quadrature-axis current and the first direct-axis current of the motor, so as to preferentially convert kinetic energy of the vehicle recovered by the motor into heat energy for heating of a system in the vehicle having heating demand.

3. The electric motor braking control method according to claim 2, characterized by, braking control of the motor according to the first quadrature-axis current and the first direct-axis current of the motor, comprising: acquiring three-phase current of an inverter connected with the motor and the power battery; determining current quadrature-axis current and current direct-axis current of the motor according to the three-phase current; braking control of the motor according to the current quadrature-axis current and the first quadrature-axis current of the motor, and the current direct-axis current and the first direct-axis current of the motor.

4. The electric motor braking control method of claim 2, wherein determining first quadrature-axis current and first direct-axis current of the motor according to heating demand power of the vehicle and first braking torque of the motor, comprising: determining the first quadrature-axis current and the first direct-axis current of the motor according to a first mapping relationship obtained through pre-calibration, the heating demand power of the vehicle and the first braking torque of the motor; the first mapping relationship is a corresponding relationship among vehicle heating demand power, motor braking torque, motor direct-axis current and motor quadrature-axis current.

5. The electric motor braking control method of claim 2, wherein if the vehicle has no heating demand, further comprising: if braking demand power of the vehicle is greater than the battery-allowable feedback power, determining second braking torque of the motor according to the battery-allowable feedback power, determining first mechanical braking power according to the braking demand power of the vehicle and the battery-allowable feedback power, sending the first mechanical braking power to a braking system, and braking control of the motor according to the second braking torque of the motor, so as to jointly brake the braking system and the motor; if the braking demand power of the vehicle is not greater than the battery-allowable feedback power, determining third braking torque of the motor according to the braking demand power of the vehicle, and braking control of the motor according to the third braking torque of the motor.

6. The electric motor braking control method of claim 5, wherein braking control of the motor according to the second braking torque of the motor, comprising: determining second quadrature-axis current and second direct-axis current of the motor according to the MTPA table and the second braking torque of the motor, and braking control of the motor according to the second quadrature-axis current and the second direct-axis current of the motor; braking control of the motor according to the third braking torque of the motor, comprising: determining third quadrature-axis current and third direct-axis current of the motor according to the MTPA table and the third braking torque of the motor, and braking control of the motor according to the third quadrature-axis current and the third direct-axis current of the motor.

7. The electric motor braking control method of claim 1, wherein When the braking demand power of the vehicle is less than the sum of the battery allowed feedback power and the heating demand power of the vehicle, the motor quadrature axis current and direct axis current are controlled according to the braking demand power of the vehicle, the battery allowed feedback power and the heating demand power of the vehicle, so as to preferentially convert the kinetic energy of the vehicle recovered by the motor into electric energy for charging the power battery in the vehicle, comprising: If the braking demand power of the vehicle is greater than the battery allowed feedback power, the fourth braking torque of the motor is determined according to the battery allowed feedback power; The fourth motor quadrature axis current and direct axis current are determined according to the difference between the fourth braking torque of the motor, the braking demand power of the vehicle and the battery allowed feedback power; The motor is controlled according to the fourth motor quadrature axis current and direct axis current, so as to preferentially convert the kinetic energy of the vehicle recovered by the motor into electric energy for charging the power battery in the vehicle.

8. The electric motor braking control method of claim 7, wherein The fourth motor quadrature axis current and direct axis current are determined according to the difference between the fourth braking torque of the motor, the braking demand power of the vehicle and the battery allowed feedback power, comprising: The heating power that can be provided is determined according to the difference between the braking demand power of the vehicle and the battery allowed feedback power; The fourth motor quadrature axis current and direct axis current are determined according to the heating power that can be provided and the fourth braking torque of the motor.

9. The electric motor braking control method of claim 8, wherein, The fourth motor quadrature axis current and direct axis current are determined according to the heating power that can be provided and the fourth braking torque of the motor, comprising: The fourth motor quadrature axis current and direct axis current are determined according to the second mapping relationship obtained by pre-calibration, the heating power that can be provided and the fourth braking torque of the motor; The second mapping relationship is the corresponding relationship among the heating power that can be provided, the motor braking torque, the motor direct axis current and the motor quadrature axis current.

10. The electric motor braking control method of claim 7, wherein Further comprising: If the braking demand power of the vehicle is greater than the battery allowed feedback power and the vehicle has no heating demand, the fifth braking torque of the motor is determined according to the battery allowed feedback power, the second mechanical braking power is determined according to the braking demand power of the vehicle and the battery allowed feedback power, the second mechanical braking power is sent to the braking system, and the motor is controlled according to the fifth braking torque of the motor, so as to jointly brake the braking system and the motor; If the braking demand power of the vehicle is not greater than the battery allowed feedback power and the vehicle has no heating demand, the sixth braking torque of the motor is determined according to the braking demand power of the vehicle, and the motor is controlled according to the sixth braking torque of the motor.

11. The electric machine braking control method of any one of claims 1-10, wherein, The motor quadrature axis current and direct axis current are controlled according to the braking demand power of the vehicle, the battery allowed feedback power and the heating demand power of the vehicle, so that the motor operates in the low efficiency area, to recover the kinetic energy of the vehicle and convert it into electric energy for charging the power battery in the vehicle and heat energy for heating the system in the vehicle that has heating demand, comprising: determining a seventh braking torque of the motor according to the braking demand power of the vehicle, the battery allowed regenerative power and the heating demand power of the vehicle, and determining a seventh quadrature axis current and a seventh direct axis current of the motor according to the seventh braking torque of the motor and the heating demand power of the vehicle, and determining a third mechanical braking power according to the braking demand power of the vehicle, the heating demand power of the vehicle and the battery allowed regenerative power; sending the third mechanical braking power to a braking system, and braking controlling the motor according to the seventh quadrature axis current and the seventh direct axis current of the motor, so that the braking system and the motor jointly brake.

12. The electric motor braking control method of claim 1, wherein The system in the vehicle having a heating demand comprises a power battery.

13. The electric machine braking control method of claim 12, wherein, After the control of the quadrature axis current and the direct axis current of the motor according to the braking demand power of the vehicle, the battery allowed regenerative power and the heating demand power of the vehicle, the method further comprises: acquiring a temperature of the power battery, and determining whether the temperature of the power battery exceeds a temperature threshold; if yes, determining that the power battery has no heating demand, and returning to the step of acquiring the battery allowed regenerative power and the heating demand power of the vehicle.

14. An electric machine braking control apparatus characterized by, comprises: a first acquiring module, configured to acquire a braking demand power of a vehicle; a second acquiring module, configured to acquire a battery allowed regenerative power when the braking demand power of the vehicle is acquired, and acquire a heating demand power of the vehicle from a system in the vehicle having a heating demand; a control module, comprising a control submodule, configured to control a quadrature axis current and a direct axis current of the motor according to the braking demand power of the vehicle, the battery allowed regenerative power and the heating demand power of the vehicle, so that the motor operates in a low efficiency area to recover kinetic energy of the vehicle and convert the kinetic energy into electric energy for charging a power battery in the vehicle and heat energy for heating the system in the vehicle having a heating demand; the control submodule comprises: a first control unit, configured to control the quadrature axis current and the direct axis current of the motor according to the braking demand power of the vehicle, the battery allowed regenerative power and the heating demand power of the vehicle when the braking demand power of the vehicle is less than a sum of the battery allowed regenerative power and the heating demand power of the vehicle, so as to preferentially convert the kinetic energy of the vehicle recovered by the motor into heat energy for heating the system in the vehicle having a heating demand, or preferentially convert the kinetic energy of the vehicle recovered by the motor into electric energy for charging the power battery in the vehicle. If the heating demand power of the vehicle is not less than the braking demand power of the vehicle, an eighth braking torque of the motor is determined according to a first preset battery recovery power, an eighth quadrature axis current and an eighth direct axis current of the motor are determined according to a difference between the braking demand power of the vehicle and the first preset battery recovery power and the eighth braking torque of the motor, and braking control is performed on the motor according to the eighth quadrature axis current and the eighth direct axis current of the motor, so that a part of kinetic energy recovered by the motor is converted into heat energy for heating the system in the vehicle having a heating demand and a part of kinetic energy recovered by the motor is converted into electric energy for charging the power battery in the vehicle; wherein the first preset battery recovery power is less than the smaller one of the braking demand power of the vehicle and the battery allowable feedback power.

15. An electric drive system, characterized by The VCU, the motor controller connected with the VCU, the motor connected with the motor controller, and the BMS connected with the VCU are included, wherein: The VCU is configured to acquire the braking demand power of the vehicle, acquire the battery allowable feedback power from the BMS, acquire the heating demand power of the vehicle from the system in the vehicle having a heating demand, and control the quadrature axis current and the direct axis current of the motor through the motor controller according to the braking demand power of the vehicle, the battery allowable feedback power, and the heating demand power of the vehicle, so that the motor operates in a low efficiency zone to recover kinetic energy of the vehicle and convert the kinetic energy into electric energy for charging the power battery in the vehicle and heat energy for heating the system in the vehicle having a heating demand. The VCU controls the quadrature-axis current and direct-axis current of the motor through the motor controller according to the braking demand power of the vehicle, the battery allowed feedback power and the heating demand power of the vehicle, so that the motor operates in the low efficiency area to recover the kinetic energy of the vehicle and convert it into electric energy for charging the power battery in the vehicle and heat energy for heating the system with heating demand in the vehicle, specifically for: when the braking demand power of the vehicle is less than the sum of the battery allowed feedback power and the heating demand power of the vehicle, controlling the quadrature-axis current and direct-axis current of the motor through the motor controller according to the braking demand power of the vehicle, the battery allowed feedback power and the heating demand power of the vehicle, to preferentially convert the kinetic energy recovered by the motor into electric energy for charging the power battery in the vehicle, or preferentially convert the kinetic energy recovered by the motor into heat energy for heating the system with heating demand in the vehicle; if the heating demand power of the vehicle is not less than the braking demand power of the vehicle, determining an eighth braking torque of the motor according to a first preset battery recovery power, determining an eighth quadrature-axis current and an eighth direct-axis current of the motor according to the difference between the braking demand power of the vehicle and the first preset battery recovery power and the eighth braking torque of the motor, and braking controlling the motor according to the eighth quadrature-axis current and the eighth direct-axis current of the motor, to convert part of the kinetic energy recovered by the motor into heat energy for heating the system with heating demand in the vehicle and part of the kinetic energy recovered by the motor into electric energy for charging the power battery in the vehicle; wherein the first preset battery recovery power is less than the smaller one of the braking demand power of the vehicle and the battery allowed feedback power.

16. The electric drive system of claim 15, wherein, The VCU controls the quadrature-axis current and direct-axis current of the motor according to the braking demand power of the vehicle, the battery allowed feedback power and the heating demand power of the vehicle when the braking demand power of the vehicle is less than the sum of the battery allowed feedback power and the heating demand power of the vehicle, to preferentially convert the kinetic energy recovered by the motor into heat energy for heating the system with heating demand in the vehicle, specifically for: if the heating demand power is less than the braking demand power, determining a first braking torque of the motor according to the difference between the braking demand power and the heating demand power, sending the first braking torque of the motor to the motor controller, determining a first quadrature-axis current and a first direct-axis current of the motor according to the heating demand power and the first braking torque of the motor by the motor controller, and braking controlling the motor according to the first quadrature-axis current and the first direct-axis current of the motor, to preferentially convert the kinetic energy recovered by the motor into heat energy for heating the system with heating demand in the vehicle.

17. The electric drive system of claim 16, wherein, Also included is an inverter connected to the motor and the power battery, an AC end of the inverter is provided with a current sensor connected to the motor controller, for collecting three-phase current of the inverter; The motor controller performs brake control on the motor according to the first cross-axis current and the first direct-axis current of the motor, specifically for acquiring the three-phase current of the inverter; determining the current cross-axis current and the current direct-axis current of the motor according to the three-phase current; performing brake control on the motor according to the current cross-axis current and the first cross-axis current of the motor, and the current direct-axis current and the first direct-axis current of the motor.

18. A vehicle characterized by comprising: An electric drive system as claimed in any one of claims 15 to 17 for implementing the steps of the motor brake control method as claimed in any one of claims 1 to 13.

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