Motor braking control method and apparatus, electric drive system, and vehicle

Abstract

A motor braking control method and apparatus, an electric drive system, and a vehicle. The method comprises: acquiring a braking demand power of a vehicle (S11); and controlling a quadrature-axis current and a direct-axis current of a motor on the basis of the braking demand power of the vehicle, so that the motor recovers kinetic energy of the vehicle and converts the kinetic energy into thermal energy (S12). In the method, the quadrature-axis current and the direct-axis current of the motor are controlled on the basis of the braking demand power of the vehicle, allowing the motor to recover the kinetic energy of the vehicle and convert the kinetic energy into thermal energy, so that the manner in which the motor recovers the kinetic energy is no longer limited to converting the kinetic energy into electric energy and feeding the electric energy back into a power battery, thereby expanding the manner in which the motor recovers the kinetic energy, and improving the flexibility and diversity of recovering the kinetic energy of the vehicle during motor braking.

Description

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

[0001] Cross-reference to Related Applications

[0002] The present application claims priority to the Chinese patent application No. 202410833212.1, filed on June 25, 2024, and entitled "Motor braking control method and device, electric drive system and vehicle", the content of which is incorporated herein by reference in its entirety. TECHNICAL FIELD

[0003] The present application relates to the technical field of new energy vehicles, and in particular to a motor braking control method and device, an electric drive system and a vehicle. BACKGROUND

[0004] Compared with traditional fuel vehicles, new energy vehicles use a motor as a power source, and in addition to being able to choose to use a mechanical braking system to provide braking force, the motor can also be used for braking.

[0005] 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 electrical energy by the motor and fed back to the power battery. However, the current motor energy recovery method is relatively single.

[0006] To sum up, how to expand the motor energy recovery method is a technical problem that needs to be solved by the technical personnel in the field at present. SUMMARY

[0007] Therefore, the purpose of the present application is to provide a motor braking control method and device, an electric drive system and a vehicle for expanding the motor energy recovery method.

[0008] In order to achieve the above purpose, the present application provides the following technical solutions:

[0009] A motor braking control method comprises: acquiring braking demand power of a vehicle; 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 it into heat energy.

[0010] 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 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 it into heat energy.

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

[0012] The application provides a vehicle comprising the electric drive system as described in any one of the above, and the vehicle is used to implement the steps of the motor braking control method as described in any one of the above.

[0013] The application provides a motor braking control method and device, an electric drive system, and a vehicle. The method comprises the following steps: acquiring braking demand power of a vehicle; and controlling cross-axis current and direct-axis current of a 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. Compared with the prior art, the motor recovers kinetic energy of the vehicle and converts the kinetic energy into heat energy according to the braking demand power of the vehicle, instead of converting the kinetic energy into electric energy and feeding the electric energy back to a power battery. The way in which the motor recovers kinetic energy is no longer limited to converting the kinetic energy into electric energy and feeding the electric energy back to the power battery, so that the way in which the motor recovers kinetic energy is expanded, and flexibility and diversity of recovering kinetic energy of the vehicle during motor braking are improved.

[0014] Additional aspects and advantages of the application will be made apparent by the following description. BRIEF DESCRIPTION OF DRAWINGS

[0015] FIG. 1 is a flowchart of a motor braking control method according to an embodiment of the application;

[0016] FIG. 2 is a flowchart of kinetic energy of a vehicle recovered during motor braking according to an embodiment of the application;

[0017] FIG. 3 is a schematic diagram of a heat flow circuit of heat generated by a motor according to an embodiment of the application;

[0018] FIG. 4 is a flowchart of another motor braking control method according to an embodiment of the application;

[0019] FIG. 5 is a flowchart of still another motor braking control method according to an embodiment of the application;

[0020] FIG. 6 is a schematic diagram of a structure of a motor control device according to an embodiment of the application;

[0021] FIG. 7 is a schematic diagram of a structure of an electric drive system according to an embodiment of the application;

[0022] FIG. 8 is a schematic diagram of a braking power distribution strategy in a VCU according to an embodiment of the present application;

[0023] FIG. 9 is a schematic diagram of a direct-quadrature axis current distribution strategy in a motor controller according to an embodiment of the present application. DETAILED DESCRIPTION

[0024] 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 when braking. At present, when the motor is used to brake, the motor outputs braking torque. In the process of the motor outputting braking torque, the kinetic energy of the vehicle is converted into electrical energy by the motor and fed back to the power battery. However, the current way of recovering kinetic energy by the motor is relatively single.

[0025] Therefore, the present application provides a motor braking control method and device, an electric drive system and a vehicle, which are used to expand the way of recovering kinetic energy by the motor, so as to improve the flexibility and diversity of recovering kinetic energy when the motor brakes.

[0026] Embodiments of the present application will be described in detail below, examples of which are shown in the drawings, wherein the same or similar reference signs represent the same or similar elements or elements having the same or similar functions throughout. The embodiments described below by referring to the drawings are exemplary and are intended to explain the present application, and cannot be understood as a limitation of the present application.

[0027] Referring to FIG. 1, a flowchart of a motor braking control method according to an embodiment of the present application is shown. The motor braking control method according to an embodiment of the present application can include the following steps.

[0028] S11: Obtain braking demand power of a vehicle.

[0029] It should be noted that the execution subject of the motor braking control method provided in the embodiments of the present application can be an electric drive system, a motor braking control device or a vehicle, etc., and the present application takes the electric drive system as an example for description.

[0030] When braking the vehicle, 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 when the vehicle brakes, i.e., the braking power corresponding to the kinetic energy to be recovered by the vehicle), etc.

[0031] It should be noted that the electric drive system can execute step S11 in real time or at a timing (the timing 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 the motor braking control.

[0032] S12: controlling 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.

[0033] 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, thereby expanding the recovery mode of the kinetic energy of the vehicle during motor braking. For example, the motor can be completely converted into heat energy after recovering the kinetic energy of the vehicle. Alternatively, the motor can be converted into not only heat energy but also electric energy and fed back to the power battery in the vehicle after recovering the kinetic energy of the vehicle.

[0034] Compared with the prior art of converting the kinetic energy into electric energy and feeding it back to the power battery by allowing the motor to output braking torque for power generation during braking, the above technical solution disclosed by the embodiment 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, so that the motor recovers the kinetic energy of the vehicle and converts it into heat energy, thereby expanding the recovery mode of the kinetic energy of the vehicle and improving the flexibility and diversity of the recovery of the kinetic energy of the vehicle during motor braking.

[0035] The motor braking control method provided by the embodiment 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.

[0036] Controlling 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, 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, 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.

[0037] In the embodiments of the present application, the braking demand power of the vehicle can be obtained, and the battery allowed feedback power can also be obtained. The battery allowed feedback power is the maximum power allowed to be fed back by the power battery at the corresponding moment. The battery allowed feedback power can be directly obtained (for example, the battery allowed feedback power is directly obtained from the BMS (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.

[0038] In addition, it can also be determined whether the vehicle has a heating demand at the same time. For example, whether the vehicle has a heating demand can be determined by determining whether the ambient temperature is lower than a preset temperature, whether the heating instruction of the target system (that is, the system in the vehicle that has a heating demand) is obtained, or whether the heating demand power is received. If it is determined that the vehicle has a heating demand, the heating demand power of the vehicle can be obtained at the same time when the braking demand power of the vehicle and the battery allowed feedback power are obtained. Specifically, the heating demand power of the vehicle can be obtained from the system in the vehicle that has a heating demand.

[0039] It should be noted that obtaining the battery allowed feedback power 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 demand), so as to obtain the braking demand power of the vehicle, the battery allowed feedback power and the heating demand power of the vehicle in time, and the motor braking control is performed 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. In addition, 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 in the best temperature condition as much as possible.

[0040] Based on the above, the quadrature-axis current and direct-axis current of the motor are controlled according to the vehicle's braking power demand, enabling the motor to recover the vehicle's kinetic energy and convert it into heat energy. Specifically, this can be achieved by controlling the motor's quadrature-axis current and direct-axis current according to the vehicle's braking power demand, the battery's allowable feedback power, and the vehicle's heating power demand, so that the motor operates in an inefficient region (i.e., adjusting the distribution of the motor's quadrature-axis and direct-axis currents according to the vehicle's braking power demand, battery's allowable feedback power, and vehicle's heating power demand to control the motor's operation in an inefficient region). This inefficient region is the area where the efficiency of converting kinetic energy into electrical energy is relatively low, specifically, the area where the efficiency of converting kinetic energy into electrical energy is lower than a preset efficiency value, which can be determined in advance through calibration, etc. By operating the motor in the inefficient region, the copper and iron losses of the motor are increased, generating heat. This ensures that the vehicle's kinetic energy recovered during braking can not only be converted into electrical energy but also into heat energy through the motor's copper and iron losses. The electrical energy can be fed back to the power battery to charge it, and the heat energy can be used to heat systems in the vehicle that require heating through a heat conduction circuit. Through the above process, the direct-axis current I of the motor d The absolute value will increase, causing the stator current I to... s The increased current heats the motor shaft, converting mechanical energy into heat. This heat then flows through a heat conduction circuit to systems within the vehicle that require heating, thus improving the utilization rate of the vehicle's kinetic energy. In other words, the aforementioned process adjusts the AC and DC axis current distribution of the motor, controlling its operation in the inefficient region. This increases copper and iron losses, generating heat. Consequently, the kinetic energy recovered during braking can not only be converted into electrical energy to charge the battery, but also converted into heat through the motor's copper and iron losses, which then heats systems within the vehicle that require heating.

[0041] Referring to Figure 2, it shows the flow diagram of the vehicle kinetic energy recovered during electric motor braking according to the embodiments of this application. The vehicle kinetic energy E recovered during electric motor braking m It can be converted into feedback electrical energy E e And the heat energy E lost through the copper and iron losses of the motor heat This means that during electric motor braking, a portion of the vehicle's kinetic energy can be converted into electrical energy, and another portion into heat energy. The electrical energy can charge the vehicle's battery (specifically, through an inverter), and the heat energy can heat systems within the vehicle that require heating (specifically, through a heat conduction circuit). As mentioned above, if the regenerative electrical energy E is maintained... e The heat energy E consumed by the increased copper and iron losses of the motor remains unchanged. heatTherefore, the vehicle kinetic energy consumed by the motor can be increased, i.e., the braking capability of the vehicle is increased, and the loss of the vehicle kinetic energy is reduced, and the utilization rate of the vehicle kinetic energy is improved.

[0042] Referring to FIG. 3, a flow circuit diagram of heat generated by the motor is shown. The heat energy generated by the vehicle kinetic energy recovered by the motor during braking can be circulated to the system requiring heating in the vehicle through the heat conduction circuit to heat the system requiring heating. If the power battery in the vehicle has a heating requirement in a low temperature environment, the heat energy generated by the vehicle kinetic energy recovered by the motor during braking can be circulated to the power battery through the heat conduction circuit 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, the charging and discharging performance of the battery is improved, the allowed feedback power of the battery is increased, and the braking capability of the vehicle in the low temperature environment is further improved. Of course, the passenger compartment, air conditioning system and other systems in the vehicle can also have a heating requirement. In this case, the heat generated by the vehicle kinetic energy recovered by the motor during braking can also be circulated to other systems requiring heating through the heat conduction circuit to heat these systems.

[0043] By adjusting the motor d-q axis current distribution, the motor is controlled to operate in the low efficiency area to increase the copper loss and iron loss of the motor to generate heat. When the motor brakes, the recovered vehicle kinetic energy can be converted into electric energy to charge the power battery in the vehicle, and can also be converted into heat energy to be transmitted to the system requiring heating in the vehicle through the heat conduction circuit to heat the system requiring heating by using the heat energy converted from the recovered vehicle kinetic energy. Through the above process, even if the feedback power is unchanged, the recovered vehicle kinetic energy of the motor can be increased to improve the braking capability of the motor and reduce the loss of the vehicle kinetic energy during braking, and improve the utilization rate of the vehicle kinetic energy. That is, through the above process, the motor generates heat while feedback braking, so that part of the recovered vehicle kinetic energy of the motor is converted into electric energy to charge the power battery, and part of the recovered vehicle kinetic energy of the motor is converted into heat energy to heat the vehicle, thereby improving the recovery capability of the motor for the vehicle kinetic energy and reducing the waste of the vehicle kinetic energy during braking. Moreover, in the above process, the feedback power and the heat generation power of the electric drive system can be dynamically adjusted to meet the heating requirements under various working conditions while meeting the braking requirements of the vehicle. In addition, the above process directly uses the heat energy generated by the motor during braking to heat the system requiring heating in the vehicle, without the need for additional heating components or the need for converting the heat energy into electric energy to heat the system requiring heating. Therefore, the heating cost of the vehicle and the manufacturing cost of the vehicle can be reduced, and the utilization rate of the feedback energy can be improved.

[0044] The above process can make the motor not only convert the recovered vehicle kinetic energy into electric energy to charge the power battery when braking, but also convert the kinetic energy into heat energy to heat the system in the vehicle that needs heating, thereby not only expanding the motor kinetic energy recovery mode, but also achieving full utilization of the motor kinetic energy recovery, reducing the waste of kinetic energy recovery, and improving the utilization rate of kinetic energy recovery.

[0045] The motor braking control method provided by the embodiments of the present application controls the motor quadrature axis current and direct axis current according to the vehicle braking demand power, the battery allowed feedback power and the vehicle heating demand power, so that the motor operates in the low efficiency area to recover the vehicle kinetic energy 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 needs heating. The method can include: when the vehicle braking demand power is less than the sum of the battery allowed feedback power and the vehicle heating demand power, controlling the motor quadrature axis current and direct axis current according to the vehicle braking demand power, the battery allowed feedback power and the vehicle heating demand power, to preferentially convert the motor recovered vehicle kinetic energy into heat energy for heating the system in the vehicle that needs heating, or preferentially convert the motor recovered vehicle kinetic energy into electric energy for charging the power battery in the vehicle.

[0046] In the embodiments of the present application, when the motor quadrature axis current and direct axis current are controlled according to the vehicle braking demand power, the battery allowed feedback power and the vehicle heating demand power, so that the motor operates in the low efficiency area to recover the vehicle kinetic energy 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 needs heating, if the vehicle braking demand power is less than the sum of the battery allowed feedback power and the vehicle heating demand power, it indicates that the vehicle kinetic energy to be recovered 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 quadrature axis current and direct axis current can be controlled according to the vehicle braking demand power, the battery allowed feedback power and the vehicle heating demand power, to preferentially convert the motor recovered vehicle kinetic energy into heat energy for heating the system in the vehicle that needs heating, and the remaining kinetic energy recovered can be converted into electric energy for charging the power battery, to preferentially meet the heating demand of the vehicle, so as to efficiently heat the vehicle and reduce the loss of vehicle kinetic energy, and facilitate to extend the driving range of the vehicle. Or, the motor recovered vehicle kinetic energy can be preferentially 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 that needs heating, to preferentially meet the charging demand of the power battery, so as to extend the driving range of the vehicle as much as possible and enhance the motor braking capability.

[0047] 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 quadrature axis current and the direct axis current of 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, so as to convert the kinetic energy of the vehicle recovered by the motor into heat energy for heating the system having the heating demand in the vehicle 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.

[0048] Referring to FIG. 4, a flow chart 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 can include the following steps: 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 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 heat energy for heating the system having the heating demand in the vehicle, 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, so as to preferentially convert the kinetic energy of the vehicle recovered by the motor into heat energy for heating the system having the heating demand in the vehicle.

[0049] In the embodiment of the present application, when the vehicle has a heating demand and 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 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 allowed feedback power of the battery 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 allowed feedback power of the battery 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 controlled to brake according to the determined first quadrature axis current and the first 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 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 and user experience of the vehicle, avoiding energy loss caused by first converting into electric energy and then converting into heat energy, reducing the loss of the kinetic energy of the vehicle, improving the utilization rate of the recovered kinetic energy of the vehicle, and also prolonging the driving range of the vehicle.

[0050] 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.

[0051] 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.

[0052] 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 braking performance of the motor.

[0053] 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, and can include the following steps.

[0054] 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 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.

[0055] In the embodiment of the present application, the mapping 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 (i.e., the first mapping relationship obtained by pre-calibration, and the heating demand power of the vehicle at this time is the power used for heating the system in the vehicle which has heating demand) can be pre-calibrated. Then, the first mapping relationship obtained by pre-calibration can be queried according to the heating demand power of the vehicle and the first braking torque of the motor, to determine the corresponding quadrature axis current of the motor (as the first quadrature axis current of the motor) and the direct axis current of the motor (as the first direct axis current 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.

[0056] 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, determining a second braking torque of the motor according to the battery allowed feedback power, determining a 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, 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 battery allowed feedback power, 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.

[0057] 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 battery allowed feedback power.

[0058] If it is determined that the braking demand power of the vehicle is greater than the battery allowed feedback power, a second braking torque of the motor is determined according to the battery allowed feedback power, and braking control is performed on the motor according to the second braking torque, so that the motor brakes according to the battery allowed feedback power. In addition, a first mechanical braking power can be determined according to the braking demand power of the vehicle and the battery allowed feedback power, specifically, the first mechanical braking power = the braking demand power of the vehicle - the battery allowed feedback power, 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 brakes mechanically 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 brakes mechanically 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 battery allowed feedback power, 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 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.

[0059] If it is determined that the braking demand power of the vehicle is not greater than the battery allowed feedback power, 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 kinetic energy of the vehicle in the braking process, and improve the utilization rate of the kinetic energy of the vehicle.

[0060] 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.

[0061] 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.

[0062] In the embodiments of the present application, the MTPA (maximum torque current ratio) table of the motor can be acquired in advance.

[0063] 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 can be 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 braking 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 include: 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, and 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 braking running performance.

[0064] 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 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.

[0065] Referring to FIG. 5, a flowchart of another motor braking control method provided by the embodiments of the present application is shown. 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. 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.

[0066] In this embodiment, when the vehicle has a heating requirement, and the vehicle's braking power requirement is less than the sum of the battery's allowable regenerative power and the vehicle's heating power requirement, the quadrature-axis current and direct-axis current of the motor are controlled based on the vehicle's braking power requirement, the battery's allowable regenerative power, and the vehicle's heating power requirement to preferentially convert the vehicle's kinetic energy recovered by the motor into thermal energy for heating systems within the vehicle. The specific process can be as follows: When the vehicle's braking power requirement is less than the sum of the battery's allowable regenerative power and the vehicle's heating power requirement, if the vehicle's braking power requirement is greater than the battery's allowable regenerative power, then the fourth braking torque of the motor is determined based on the battery's allowable regenerative power, and the difference between the vehicle's braking power requirement and the battery's allowable regenerative power is calculated (i.e., vehicle's braking power requirement - battery's allowable regenerative power). The fourth quadrature-axis current and the fourth direct-axis current of the motor are determined based on the difference between the fourth braking torque of the motor, the braking power required by the vehicle, and the allowable feedback power of the battery. Then, the motor is braked based on the fourth quadrature-axis current and the fourth direct-axis current to control the motor to operate in the inefficient zone by adjusting the distribution of the quadrature-axis and direct-axis currents. The motor prioritizes the conversion of the kinetic energy recovered by the motor into electrical energy for charging the power battery in the vehicle. The remaining recovered kinetic energy can be converted into heat energy for heating the vehicle. This ensures that the kinetic energy recovered by the motor braking is preferentially converted into electrical energy to meet the charging needs of the power battery, and the remaining kinetic energy is converted into heat energy to heat the vehicle. This improves the utilization rate of recovered kinetic energy and extends the vehicle's driving range as much as possible.

[0067] Specifically, braking control of the motor is achieved based on the fourth quadrature-axis current and the fourth direct-axis current. This can be done by: acquiring the three-phase current of the inverter; determining the current quadrature-axis current and the current direct-axis current of the motor based on the three-phase current; and then applying braking control to the motor based on the current quadrature-axis current, the fourth quadrature-axis current, and the current direct-axis current and the fourth direct-axis current. This closed-loop feedback control method ensures that the motor can accurately brake according to the determined fourth quadrature-axis current and the fourth direct-axis current, thereby improving the motor's braking performance.

[0068] It should be noted that when the vehicle's braking power demand equals the sum of the battery's allowable regenerative power and the vehicle's heating power demand, the control method described above can be used to convert the vehicle's kinetic energy recovered by the motor into thermal energy for heating systems in the vehicle and electrical energy for charging the vehicle's power battery, thereby meeting the vehicle's heating and power battery charging needs.

[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 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.

[0070] 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.

[0071] 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 fourth quadrature axis current and the fourth 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; 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.

[0072] 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 through 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 through 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 through 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.

[0073] 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.

[0074] 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.

[0075] 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.

[0076] 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.

[0077] 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.

[0078] 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.

[0079] 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.

[0080] 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.

[0081] 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.

[0082] 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, and the motor can accurately brake according to the determined seventh cross-axis current and seventh direct-axis current, thereby improving the motor braking performance.

[0083] The motor braking control method provided in the embodiments of the present application can be used for a vehicle having a system requiring heating.

[0084] 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.

[0085] 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 whole 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.

[0086] 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 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.

[0087] The motor braking control method provided in the embodiment of the 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 allowed feedback power of the battery and the heating demand power of the vehicle is returned to be executed.

[0088] In the embodiment of the 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 allowed feedback power of 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.

[0089] If it is determined that the temperature of the power battery does not exceed the temperature threshold, the power battery can be heated by the thermal energy generated during the motor braking, and the step of obtaining the allowed feedback power of the battery and the heating demand power of the vehicle is returned to be executed, so as to dynamically adjust the feedback power and the heat generation power of the motor based on the obtained parameters, thereby meeting the heating demand under various working conditions.

[0090] If it is determined that the temperature of the power battery exceeds the temperature threshold, it is determined that the power battery has been heated to a suitable temperature, that is, it is 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 allowed feedback power of the battery and the heating demand power of the vehicle, so as to dynamically adjust the feedback power and the heat generation power of the motor based on the obtained parameters, thereby meeting the heating demand under various working conditions.

[0091] The embodiment of the application further provides a motor braking control device, as shown in FIG. 6, which shows a structural schematic diagram of a motor control device provided in the embodiment of the 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.

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

[0093] 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.

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

[0095] The motor control device provided by the embodiment of the application can further comprise a second obtaining module configured to obtain the battery-allowed feedback power and the heating demand power of the vehicle when the braking demand power of the vehicle is obtained.

[0096] The motor control device provided by the embodiment of the application can further comprise a second obtaining module configured to obtain the battery-allowed feedback power and the heating demand power of the vehicle when the braking demand power of the vehicle is obtained.

[0097] 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.

[0098] 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.

[0099] 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.

[0100] 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.

[0101] The motor control device provided in the embodiment of the application, the fourth determination subunit 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 allowable feedback power of the battery, and specifically is configured to determine the available heating power according to the difference between the braking demand power of the vehicle and the allowable feedback power of the battery; determine 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.

[0102] The motor control device provided in the embodiment of the application, the fourth determination subunit 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 is configured to determine the fourth quadrature axis current and the fourth 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 a corresponding relationship among the available heating power, the motor braking torque, the motor direct axis current and the motor quadrature axis current.

[0103] The motor control device provided in the embodiment of the application, the control sub-module can further include: a fourth control unit, configured to, if the braking demand power of the vehicle is greater than the allowable feedback power of the battery and the vehicle has no heating demand, determine the fifth braking torque of the motor according to the allowable feedback power of the battery, determine the second mechanical braking power according to the braking demand power of the vehicle and the allowable feedback power of the battery, send the second mechanical braking power to the braking system, and brake control the motor according to the fifth braking torque of the motor, so that the braking system and the motor jointly brake; a fifth control unit, configured to, if the braking demand power of the vehicle is not greater than the allowable 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 brake control the motor according to the sixth braking torque of the motor.

[0104] The motor control device provided in the embodiment of the application, the control sub-module can include: a determination unit, configured to, when the braking demand power of the vehicle is greater than the sum of the allowable feedback power of the battery and the heating demand power of the vehicle, determine the seventh braking torque of the motor according to the allowable feedback power of the battery, determine the seventh quadrature 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 determine the third mechanical braking power according to the braking demand power of the vehicle, the heating demand power of the vehicle and the allowable feedback power of the battery; a sixth control unit, configured to send the third mechanical braking power to the braking system, and brake control 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.

[0105] The motor control device provided in the embodiment of the application, the system with heating demand in the vehicle can include a power battery.

[0106] 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.

[0107] The embodiment of the present application further provides an electric drive system, as shown in 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.

[0108] 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.

[0109] The electric drive system provided by the embodiment of the present application can further include a BMS connected with the VCU.

[0110] 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.

[0111] In the application, the electric drive system can include a BMS connected to the power battery, and the BMS and the VCU are connected through a CAN bus. When obtaining the braking demand power of the vehicle, the VCU can also obtain the battery allowed feedback power from the BMS. Specifically, the battery allowed feedback power can be directly obtained from the BMS, 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. It is also determined whether the vehicle has a heating demand, and the heating demand power of the vehicle is obtained when it is determined that the vehicle has a heating demand. Then, 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 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 a heating demand.

[0112] The above method can dynamically adjust the current distribution of the cross-axis and the direct-axis of the motor according to the heating instruction of the VCU, so that the motor consumes the braking power according to the heating power demand under the condition that the feedback power is unchanged, and converts it into heat energy, thereby increasing the braking power of the vehicle. The additional heat can be used to heat the power battery and other systems on the vehicle that have a heating demand in a low temperature environment. The specific braking energy flow is shown in FIG. 2. Through motor braking, the kinetic energy E m of the vehicle can be converted into feedback electric energy E e and heat energy E heat consumed by motor copper loss and iron loss. If the feedback electric energy E e is maintained unchanged, the heat energy E heat consumed by motor copper loss and iron loss is increased, the kinetic energy consumed by the motor can be increased, that is, the braking capacity of the vehicle can be increased.

[0113] The above motor braking control method does not need to change the system structure and the hardware topology of the electric drive system, and only needs to change the software control strategy in the VCU and the motor controller.

[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 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 in priority by controlling 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.

[0115] 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 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 in priority by controlling 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.

[0116] 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 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 in priority by controlling 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. 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 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 in priority by controlling 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.

[0117] 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.

[0118] 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.

[0119] 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.

[0120] 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.

[0121] 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 allowed feedback power of the battery, determining the second braking torque of the motor according to the allowed feedback power of the battery, and determining the 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, 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 allowed feedback power of the battery, 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.

[0122] 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.

[0123] 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.

[0124] 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.

[0125] 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 fourth quadrature-axis current and the fourth 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.

[0126] 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.

[0127] The electric drive system provided by the embodiment of the application is used for controlling 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 a low-efficiency area, and the kinetic energy of the vehicle is recovered and converted into electric energy for charging the power battery in the vehicle and 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, a 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, a 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.

[0128] The system in the vehicle that has a heating demand in the electric drive system provided by the embodiment of the application can include the power battery.

[0129] The electric drive system provided by the embodiment of the application is used for controlling 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 a low-efficiency area, and the kinetic energy of the vehicle is recovered and converted into electric energy for charging the power battery in the vehicle and 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, a 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, a 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.

[0130] To further illustrate the brake power distribution strategy in the VCU and the direct and quadrature axis current distribution strategy in the motor controller, refer to FIG. 8 and FIG. 9, wherein FIG. 8 shows a brake power distribution strategy in the VCU according to an embodiment of the present application, and FIG. 9 shows a direct and quadrature axis current distribution strategy in the motor controller according to an embodiment of the present application. Another brake power distribution strategy in the VCU and another direct and quadrature axis current distribution strategy in the motor controller can refer to FIG. 5. In the brake power distribution strategy, if the ambient temperature is low, resulting in a small allowed regenerative power of the battery at this time, 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 allowed regenerative power of the battery, and send the instructions to the motor controller through the message. If there is no heating demand at present and the allowed regenerative power of the battery is greater than or equal to the vehicle brake demand power, the brake power should be converted into regenerative power as much as possible, and 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 allowed regenerative power of the battery, the brake demand power other than the allowed regenerative power of the battery needs to be assisted by the brake system. 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 obtain the direct and quadrature axis current distribution according to the torque instruction and the MTPA table. 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 increases, and the increased current generates heat through the winding to convert the mechanical energy at the shaft end of the motor into heat energy. The heat energy will flow through the heat conduction circuit to the power battery and other systems of the vehicle that need heat energy, including but not limited to the passenger compartment and the air conditioning system, as shown in FIG. 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 allowed regenerative power of the battery, and further improve the braking capability of the vehicle in a low temperature environment. Moreover, 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.

[0131] Through the above, the embodiment of the application is based on an electric drive hardware topology, by modifying the braking power distribution strategy in the VCU and the direct and quadrature axis current distribution strategy in the motor controller, so that in the case of low ambient temperature and limited battery allowed feedback power, the new energy vehicle can still brake at a braking power greater than the battery allowed feedback power, and the braking power other than the feedback power will be converted into heat energy, and the heat is circulated to the power battery and other systems of the vehicle that have heating needs through the heat conduction circuit, and the heat circulated to the power battery will be used to heat the power battery, rapidly improving the charging and discharging capability of the battery in a low temperature environment, and further improving the braking capability of the vehicle in a low temperature environment.

[0132] 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.

[0133] The content of the related part in the motor control device, the electric drive system and the vehicle provided by the application can be referred to the detailed description of the corresponding part in the motor control method provided by the application, and will not be described here.

[0134] It should be noted that the logic and / or steps represented in the flowchart 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 instructions from an instruction execution system, apparatus or device and execute the instructions. For the purpose of this specification, "computer-readable medium" can be any device that can contain, store, communicate, propagate or transport a program 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 diskettes (magnetic devices), random access memories (RAM), read-only memories (ROM), erasable programmable read-only memories (EPROM or flash memories), fiber optic devices, and portable compact disk read-only memories (CDROMs). In addition, the computer-readable medium can even be paper or other suitable medium on which the program can be printed, because the program can be electronically obtained, for example, by optical scanning of the paper or other medium, followed by editing, interpreting or otherwise processing the program as necessary, and then storing it in a computer memory.

[0135] It should be understood that portions of the present application can be realized with a hardware, software, firmware or a combination thereof. In the above-described embodiments, a plurality of steps or methods can be realized with software or firmware stored in a memory and executed by a suitable instruction execution system. For example, if realized with hardware, and as in another embodiment, it can be realized with any one or a combination of the following technologies known in the art: discrete logic circuit having logic gates for implementing logic functions on data signals, application specific integrated circuits having appropriate combinational logic gates, programmable gate arrays (PGA), field programmable gate arrays (FPGA), etc.

[0136] In the description of the present application, the description of the terms "one embodiment", "some embodiments", "example", "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 present application, 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.

[0137] 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 indicated technical features. 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.

[0138] In the present application, unless otherwise explicitly specified and limited, the terms "mounting", "connection", "connecting", "fixing" and the like should be understood in a broad sense, for example, can be fixed connection, can also be detachable connection, or integral; can be mechanical connection, can also be electrical connection; 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.

[0139] Although the embodiments of the present application have been shown and described above, it can be understood that the above-described 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-described embodiments within the scope of the present application.

Claims

1. A method for controlling motor braking, characterized in that, include: Obtain the vehicle's braking power requirement; The quadrature-axis current and direct-axis current of the motor are controlled according to the braking power demand of the vehicle, so that the motor can recover the kinetic energy of the vehicle and convert it into heat energy.

2. The motor braking control method according to claim 1, characterized in that, When obtaining the vehicle's braking power requirement, the following is also included: Obtain the battery's allowable regenerative power and the vehicle's heating power requirement; The quadrature-axis current and direct-axis current of the motor are controlled according to the braking power demand of the vehicle, so that the motor recovers the kinetic energy of the vehicle and converts it into heat energy, including: The quadrature-axis current and direct-axis current of the motor are controlled according to the braking power demand of the vehicle, the allowable regenerative power of the battery, and the heating power demand of the vehicle, so that the motor operates in the inefficient zone to recover the kinetic energy of the vehicle and convert it into electrical energy for charging the power battery in the vehicle and thermal energy for heating the systems in the vehicle that require heating.

3. The motor braking control method according to claim 2, characterized in that, The quadrature-axis current and direct-axis current of the motor are controlled according to the braking power demand of the vehicle, the allowable regenerative power of the battery, and the heating power demand of the vehicle, so that the motor operates in the inefficient region to recover the kinetic energy of the vehicle and convert it into electrical energy for charging the power battery in the vehicle and thermal energy for heating systems in the vehicle that require heating, including: When the braking power demand of the vehicle is less than the sum of the battery's allowable regenerative power and the vehicle's heating power demand, the quadrature-axis current and direct-axis current of the motor are controlled according to the vehicle's braking power demand, the battery's allowable regenerative power, and the vehicle's heating power demand. This is to prioritize converting the kinetic energy recovered by the motor from the vehicle into thermal energy for heating systems in the vehicle that require heating, or to prioritize converting the kinetic energy recovered by the motor from the vehicle into electrical energy for charging the power battery in the vehicle.

4. The motor braking control method according to claim 3, characterized in that, When the braking power demand of the vehicle is less than the sum of the battery's allowable regenerative power and the vehicle's heating power demand, the quadrature-axis current and direct-axis current of the motor are controlled according to the vehicle's braking power demand, the battery's allowable regenerative power, and the vehicle's heating power demand, so as to preferentially convert the kinetic energy of the vehicle recovered by the motor into thermal energy for heating systems in the vehicle that require heating, including: If the heating power requirement of the vehicle is less than the braking power requirement of the vehicle, then the first braking torque of the motor is determined based on the difference between the braking power requirement and the heating power requirement. The first quadrature-axis current and the first direct-axis current of the motor are determined based on the heating power demand of the vehicle and the first braking torque of the motor. The motor is braked based on the first quadrature-axis current and the first direct-axis current of the motor, so as to preferentially convert the kinetic energy of the vehicle recovered by the motor into thermal energy for heating the systems in the vehicle that require heating.

5. The motor braking control method according to claim 4, characterized in that, Braking control of the motor based on the first quadrature-axis current and the first direct-axis current includes: Obtain the three-phase current of the inverter connected to the motor and the power battery; The current quadrature-axis current and the current direct-axis current of the motor are determined based on the three-phase currents; Braking control is performed on the motor based on the current quadrature-axis current and the first quadrature-axis current, the current direct-axis current and the first direct-axis current.

6. The motor braking control method according to claim 4, characterized in that, The first quadrature-axis current and the first direct-axis current of the motor are determined based on the heating power requirement of the vehicle and the first braking torque of the motor, including: The first quadrature axis current and the first direct axis current of the motor are determined based on the first mapping relationship obtained by pre-calibration, the heating power demand of the vehicle, and the first braking torque of the motor. The first mapping relationship is the correspondence between the vehicle heating power requirement, the motor braking torque, the motor direct-axis current, and the motor quadrature-axis current.

7. The motor braking control method according to claim 4, characterized in that, If the vehicle does not require heating, then it also includes: If the braking power demand of the vehicle is greater than the allowable regenerative power of the battery, then the second braking torque of the motor is determined according to the allowable regenerative power of the battery, and the first mechanical braking power is determined according to the braking power demand of the vehicle and the allowable regenerative power of the battery. The first mechanical braking power is sent to the braking system, and the motor is braked according to the second braking torque of the motor, so that the braking system and the motor brake together. If the braking power demand of the vehicle is not greater than the allowable regenerative power of the battery, then the third braking torque of the motor is determined according to the braking power demand of the vehicle, and the motor is braked according to the third braking torque of the motor.

8. The motor braking control method according to claim 7, characterized in that, Braking control of the motor based on the second braking torque of the motor includes: The second quadrature axis current and the second direct axis current of the motor are determined according to the MTPA table and the second braking torque of the motor, and the motor is braked according to the second quadrature axis current and the second direct axis current. Braking control of the motor based on the third braking torque of the motor includes: The third quadrature axis current and the third direct axis current of the motor are determined based on the MTPA table and the third braking torque of the motor, and the motor is braked based on the third quadrature axis current and the third direct axis current.

9. The motor braking control method according to claim 3, characterized in that, When the braking power demand of the vehicle is less than the sum of the battery's allowable regenerative power and the vehicle's heating power demand, the quadrature-axis current and direct-axis current of the motor are controlled according to the vehicle's braking power demand, the battery's allowable regenerative power, and the vehicle's heating power demand, so as to preferentially convert the kinetic energy of the vehicle recovered by the motor into electrical energy for charging the power battery in the vehicle, including: If the braking power demand of the vehicle is greater than the allowable regenerative power of the battery, then the fourth braking torque of the motor is determined based on the allowable regenerative power of the battery. The fourth quadrature-axis current and the fourth direct-axis current of the motor are determined based on the difference between the fourth braking torque of the motor, the braking power demand of the vehicle, and the allowable regenerative power of the battery. The motor is braked based on 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 electrical energy for charging the power battery in the vehicle.

10. The motor braking control method according to claim 9, characterized in that, The fourth quadrature-axis current and the fourth direct-axis current of the motor are determined based on the difference between the fourth braking torque of the motor, the braking power demand of the vehicle, and the allowable regenerative power of the battery, including: The heating power that can be provided is determined based on the difference between the braking power required by the vehicle and the allowable regenerative power of the battery. The fourth quadrature-axis current and the fourth direct-axis current of the motor are determined based on the available heating power and the fourth braking torque of the motor.

11. The motor braking control method according to claim 10, characterized in that, Determining the fourth quadrature-axis current and the fourth direct-axis current of the motor based on the available heating power and the fourth braking torque of the motor includes: The fourth quadrature axis current and the fourth direct axis current of the motor are determined based on the pre-calibrated second mapping relationship, the available heating power, and the fourth braking torque of the motor. The second mapping relationship is the correspondence between heating power, motor braking torque, motor direct-axis current and motor quadrature-axis current.

12. The motor braking control method according to claim 9, characterized in that, Also includes: If the braking power demand of the vehicle is greater than the allowable feedback power of the battery and the vehicle has no heating demand, then the fifth braking torque of the motor is determined according to the allowable feedback power of the battery, and the second mechanical braking power is determined according to the braking power demand of the vehicle and the allowable feedback power of the battery. The second mechanical braking power is sent to the braking system, and the motor is braked according to the fifth braking torque of the motor so that the braking system and the motor brake together. If the braking power demand of the vehicle is not greater than the allowable regenerative power of the battery and the vehicle has no heating demand, then the sixth braking torque of the motor is determined according to the braking power demand of the vehicle, and the motor is braked according to the sixth braking torque of the motor.

13. The motor braking control method according to any one of claims 3-12, characterized in that, The quadrature-axis current and direct-axis current of the motor are controlled according to the braking power demand of the vehicle, the allowable regenerative power of the battery, and the heating power demand of the vehicle, so that the motor operates in the inefficient region to recover the kinetic energy of the vehicle and convert it into electrical energy for charging the power battery in the vehicle and thermal energy for heating systems in the vehicle that require heating, including: When the braking power demand of the vehicle is greater than the sum of the battery's allowable regenerative power and the vehicle's heating power demand, the seventh braking torque of the motor is determined based on the battery's allowable regenerative power, and the seventh quadrature-axis current and the seventh direct-axis current of the motor are determined based on the seventh braking torque of the motor and the vehicle's heating power demand, and the third mechanical braking power is determined based on the vehicle's braking power demand, the vehicle's heating power demand, and the battery's allowable regenerative power demand. The third mechanical braking power is sent to the braking system, and the motor is braked according to the seventh quadrature axis current and the seventh direct axis current of the motor, so that the braking system and the motor brake together.

14. The motor braking control method according to claim 2, characterized in that, The systems in the vehicle that require heating include the power battery.

15. The motor braking control method according to claim 14, characterized in that, After controlling the quadrature-axis current and direct-axis current of the motor according to the braking power demand of the vehicle, the allowable regenerative power of the battery, and the heating power demand of the vehicle, the method further includes: The temperature of the power battery is obtained, and it is determined whether the temperature of the power battery exceeds a temperature threshold. If so, it is determined that the power battery has no heating requirement, and the process returns to the step of obtaining the battery's allowable feedback power and the vehicle's heating power requirement.

16. A motor braking control device, characterized in that, include: The first acquisition module is used to acquire the braking power required by the vehicle; The control module is used to control the quadrature-axis current and direct-axis current of the motor according to the braking power demand of the vehicle, so that the motor can recover the kinetic energy of the vehicle and convert it into heat energy.

17. An electric drive system, characterized in that, It includes a VCU, a motor controller connected to the VCU, and a motor connected to the motor controller, wherein: The VCU is used to obtain the braking power demand of the vehicle, and control the quadrature-axis current and direct-axis current of the motor through the motor controller according to the braking power demand of the vehicle, so that the motor recovers the kinetic energy of the vehicle and converts it into heat energy.

18. The electric drive system according to claim 17, characterized in that, It also includes a BMS connected to the VCU; The VCU is also used to obtain the vehicle's heating power requirement when obtaining the vehicle's braking power requirement, and to obtain the battery's allowable regenerative power from the BMS. The VCU controls the quadrature-axis current and direct-axis current of the motor through the motor controller according to the braking power demand of the vehicle, so that the motor recovers the kinetic energy of the vehicle and converts it into heat energy. Specifically, it controls the quadrature-axis current and direct-axis current of the motor through the motor controller according to the braking power demand of the vehicle, the allowable regenerative power of the battery, and the heating power demand of the vehicle, so that the motor operates in the inefficient zone, so as to recover the kinetic energy of the vehicle and convert it into electrical energy for charging the power battery in the vehicle and thermal energy for heating the systems in the vehicle that have heating requirements.

19. The electric drive system according to claim 18, characterized in that, The VCU controls the quadrature-axis current and direct-axis current of the motor through the motor controller based on the vehicle's braking power demand, the battery's allowable regenerative power, and the vehicle's heating power demand. This allows the motor to operate in an inefficient region, recovering the vehicle's kinetic energy and converting it into electrical energy to charge the vehicle's power battery and thermal energy to heat systems within the vehicle that require heating. Specifically, when the vehicle's braking power demand is less than the sum of the battery's allowable regenerative power and the vehicle's heating power demand, the VCU controls the motor's quadrature-axis current and direct-axis current through the motor controller based on the vehicle's braking power demand, the battery's allowable regenerative power, and the vehicle's heating power demand. This prioritizes converting the vehicle's kinetic energy recovered by the motor into electrical energy to charge the vehicle's power battery, or prioritizes converting the vehicle's kinetic energy recovered by the motor into thermal energy to heat systems within the vehicle that require heating.

20. The electric drive system according to claim 19, characterized in that, When the vehicle's braking power demand is less than the sum of the battery's allowable regenerative power and the vehicle's heating power demand, the VCU controls the motor's quadrature-axis current and direct-axis current based on the vehicle's braking power demand, the battery's allowable regenerative power, and the vehicle's heating power demand. This prioritizes converting the vehicle's kinetic energy recovered by the motor into thermal energy for heating systems within the vehicle that require heating. Specifically, if the heating power demand is less than the braking power demand, the VCU determines the motor's first braking torque based on the difference between the braking power demand and the heating power demand. The first braking torque is then sent to the motor controller, which determines the motor's first quadrature-axis current and first direct-axis current based on the heating power demand and the motor's first braking torque. The VCU then controls the motor's braking based on these two currents, prioritizing the conversion of the vehicle's kinetic energy recovered by the motor into thermal energy for heating systems within the vehicle that require heating.

21. The electric drive system according to claim 20, characterized in that, It also includes an inverter connected to the motor and the power battery. The AC terminal of the inverter is equipped with a current sensor connected to the motor controller for collecting the three-phase current of the inverter. The motor controller performs braking control on the motor based on the first quadrature-axis current and the first direct-axis current of the motor. Specifically, it obtains the three-phase current of the inverter; determines the current quadrature-axis current and the current direct-axis current of the motor based on the three-phase current; and performs braking control on the motor based on the current quadrature-axis current and the first quadrature-axis current, the current direct-axis current and the first direct-axis current of the motor.

22. A vehicle, characterized in that, Includes the electric drive system as described in any one of claims 17 to 21, for implementing the steps of the motor braking control method as described in any one of claims 1 to 15.

Images