Motor auxiliary braking control method, motor and vehicle

Abstract

The invention discloses a control method for auxiliary braking of a motor, the motor and a vehicle. The method comprises the steps that a vehicle control unit receives a braking instruction; the battery is in a charging power limited state; confirming that the brake disc is in a high-temperature state; and entering a motor auxiliary braking mode. According to the control method for auxiliary braking of the motor, part of recovered kinetic energy is converted into heat generated by the motor through auxiliary braking of the motor to be consumed, the situation that the energy recovered from the kinetic energy is converted into electric energy of the battery to cause overcharge of the battery when the battery is low in feed or free of feed can be avoided, protection on the battery is increased, and the service life of the battery is prolonged. And meanwhile, the brake disc can be prevented from being overheated in the braking process, the consumption path of energy generated by braking and sliding in the braking process is increased, and the service life of the brake disc is prolonged.

Description

Technical Field

[0001] The present invention relates to the technical field of vehicle motor braking, and in particular to a control method for motor-assisted braking, a motor, and a vehicle. Background Art

[0002] In the prior art, in some special scenarios where the charging power of the power battery is severely limited, such as extremely cold weather, full battery, or battery damage, if the kinetic energy recovery is continued to drag the motor in reverse to convert the braking energy into electrical energy and feed it back to the power battery, it is easy to cause a burden or even damage to the battery due to overcharging. Summary of the Invention

[0003] The present invention aims to solve at least one of the technical problems existing in the prior art. To this end, the first object of the present invention is to propose a control method for motor-assisted braking to increase the protection of the brake disc and the battery.

[0004] The second object of the present invention is to propose a motor controlled by the above control method for motor-assisted braking.

[0005] The third object of the present invention is to propose a vehicle including the above motor and the control method for the motor to assist in braking.

[0006] According to the control method for motor-assisted braking according to the first aspect embodiment of the present invention, the method steps include: The vehicle controller receives a braking instruction; the battery is in a state where the charging power is limited; it is confirmed that the brake disc is in a high-temperature state; enter the motor-assisted braking mode.

[0007] According to the control method for motor-assisted braking according to the embodiment of the present invention, by converting part of the recovered kinetic energy into heat generated by the motor itself through motor-assisted braking for consumption, it is possible to avoid the energy of kinetic energy recovery being converted into electrical energy of the battery and causing overcharging of the battery when the battery has low or no feed, increasing the protection of the battery. At the same time, overheating of the brake disc can be avoided during braking, increasing the consumption path of the energy generated during braking and coasting, and increasing the service life of the brake disc.

[0008] Optionally, for the battery being in a state where the charging power is limited, the method includes: obtaining at least one parameter among the battery power, temperature, and health status; confirming that the maximum allowable charging power of the battery is lower than a threshold; the battery is in a state where the charging power is limited.

[0009] Optionally, the threshold of the maximum allowable charging power of the battery is G, and G satisfies: G ≤ 10KW.

[0010] Optionally, after confirming that the maximum charging power of the battery is allowed to be lower than the threshold, the method includes: the vehicle controller obtains the deceleration required by the vehicle and detects the real-time temperature of each brake disc; the temperature of any brake disc is greater than or equal to the safety threshold temperature; it is confirmed that the brake disc is in a high-temperature state.

[0011] Optionally, the temperature of any brake disc is greater than or equal to 90% of the upper limit of the safety threshold temperature; it is confirmed that the brake disc is in a high-temperature state.

[0012] Optionally, after confirming that the brake disc is in a high-temperature state, the method includes: the vehicle controller obtains the motor temperature and the transmission oil temperature; the motor temperature and the transmission oil temperature are lower than 80% of the upper limit of the safety threshold temperature; enter the motor-assisted braking state and compensate the brake caliper for braking.

[0013] Optionally, when entering the motor-assisted braking state and compensating the brake caliper for braking, the method includes: determining to enter the motor-assisted braking; obtaining the deceleration corresponding to the braking pedal level; calculating the total torque required for braking.

[0014] Optionally, after entering the motor-assisted braking mode, the method includes: obtaining the battery power and the real-time energy consumption power of the vehicle; calculating the maximum allowable charging power of the battery; determining the motor energy recovery power.

[0015] Optionally, after determining the motor energy recovery power, the method includes: the battery is allowed to charge, and the charging power is less than or equal to the preset threshold; the motor enters the low-efficiency power generation assisted braking strategy.

[0016] Optionally, after the motor enters the low-efficiency power generation assisted braking, the method includes: calculating the real-time energy consumption power of the vehicle; confirming that the motor power generation power is greater than or equal to the real-time energy consumption power of the vehicle; confirming that the motor heat generation is within the threshold; adjusting the motor power generation power and the heat generation power.

[0017] Optionally, after determining the motor energy recovery power, the method includes: the battery is not allowed to charge; the motor enters the non-feed motor assisted braking strategy.

[0018] Optionally, when the motor enters the non-feed motor assisted braking strategy, the method includes: short-circuit braking of the three-phase windings of the motor; or, braking by applying three-phase direct current to the stator of the motor.

[0019] Optionally, for the short-circuit braking of the three-phase windings of the motor, the method includes: the braking instantaneous current reaches the preset threshold; short-circuit any two-phase currents in the three-phase electricity; short-circuit the other phase current in the three-phase electricity; enter the short-circuit braking of the three-phase windings of the motor.

[0020] Optionally, after the short-circuit braking of the three-phase windings of the motor, the method includes: controlling the current angle at the time of switching in to cancel the line voltage generated by the counter electromotive force on the three-phase windings.

[0021] Optionally, the motor stator is braked by applying three-phase direct current, and the method includes: obtaining the motor braking power and the real-time vehicle speed, calculating the motor braking torque; obtaining the total required braking torque; determining the required caliper braking compensation torque; and the braking module performing caliper compensation braking.

[0022] Optionally, when entering the motor-assisted braking mode, the method further includes: recording in real time the motor temperature value, the three-phase current value, and the motor power generation duration; any one of the recorded values of the motor temperature value, the three-phase current value, and the motor power generation duration reaching the allowable maximum value; and disconnecting the motor-assisted braking.

[0023] Optionally, when disconnecting the motor-assisted braking, the method further includes: calculating the braking torque to determine the required additional caliper compensation torque; and performing single braking on the brake disc.

[0024] Optionally, after recording in real time the motor temperature value, the three-phase current value, and the motor power generation duration and before any one of the recorded values of the motor temperature value, the three-phase current value, and the motor power generation duration reaches the allowable maximum value, the method includes: calculating the temperatures of the three-phase windings and the permanent magnets; and determining the motor cooling strategy.

[0025] Optionally, when determining the motor cooling strategy, the method includes: the temperature of the motor stator or rotor reaching the safety threshold temperature; adjusting the cooling flow rate of the motor stator or rotor; the temperature of the motor stator or rotor reaching the safety threshold temperature; and disconnecting the motor-assisted braking.

[0026] Optionally, the method includes: the driver releasing the brake to issue a braking end command; the motor and the brake disc braking simultaneously, exiting the motor-assisted braking, and the brake caliper releasing; or, performing single braking on the brake disc and the brake caliper releasing; and the braking ends.

[0027] According to the motor of the second aspect embodiment of the present invention, the motor adopts the control method of motor-assisted braking described in any one of the above embodiments.

[0028] According to the vehicle of the third aspect embodiment of the present invention, it includes the control method of motor-assisted braking described in any one of the above embodiments, or the motor described in the above embodiments.

[0029] The additional aspects and advantages of the present invention will be partially given in the following description, partially become obvious from the following description, or be understood through the practice of the present invention. Description of the Drawings

[0030] The above and / or additional aspects and advantages of the present invention will become obvious and easy to understand from the description of the embodiments in conjunction with the following drawings, where: Figure 1 It is a schematic diagram for judging whether the charging power of the power battery is limited and motor-assisted braking is required; Figure 2It is a schematic diagram of the implementation of motor power generation auxiliary braking; Figure 3 It is a logic flow chart of the implementation of motor power generation auxiliary braking; Figure 4 It is a schematic diagram of the motor power generation efficiency at the torque-speed corresponding operating point under rated current when the motor generates power inefficiently to assist braking; Figure 5 It is a schematic diagram of motor heating at the torque-speed corresponding operating point under rated current when the motor generates power inefficiently to assist braking; Figure 6a It is a schematic diagram of the principle of two-phase short circuit under the motor soft-cut steady-state short circuit strategy; Figure 6b It is a schematic diagram of the principle of three-phase short circuit under the motor soft-cut steady-state short circuit strategy; Figure 7 It is a schematic diagram of the cooling strategy principle of motor generator auxiliary braking. DETAILED DESCRIPTION

[0031] The embodiments of the present invention are described in detail below. The embodiments described with reference to the accompanying drawings are exemplary. Figures 1 - 7 A control method for motor-assisted braking according to an embodiment of the present invention is described, and the method steps include: The vehicle controller receives a braking command; The battery is in a state of limited charging power; Make sure the brake disc is at high temperature; Enter motor-assisted braking mode.

[0032] Specifically, if Figures 1 - 3 As shown, the battery is the power battery of the vehicle. When the power battery charging power is limited, that is, the battery pack is fully charged or nearly fully charged, the ambient temperature is too low, or the battery pack is damaged, the kinetic energy generated during the vehicle braking or sliding cannot be converted into electrical energy and stored in the battery pack. Only the brake disc is used to provide braking, which can easily cause the brake caliper and the brake disc to overheat and wear. At this time, continuing to recover energy may cause the battery to be overcharged, burdening or even damaging the battery pack, and affecting driving comfort and safety. In this application, the consumption of kinetic energy is achieved by converting part of the kinetic energy into motor heating. The driver issues a braking command, which can be that the driver continuously or intermittently steps on the brake pedal, and the vehicle control receives the braking command, and the vehicle enters the braking mode. When the vehicle's power battery charging power is greatly limited, it is determined whether the battery is allowed to charge. If allowed, the drive motor energy recovery braking auxiliary brake disc is turned on within the range of the power battery's allowed charging power for braking; if not allowed, the motor auxiliary braking without feeding is turned on.

[0033] In the motor-assisted braking mode, the required braking torque is first calculated, and then the motor-assisted braking torque and the required brake disc compensation torque are calculated. By changing the proportion of power generation and heat generation of the drive motor, part of the energy generated by braking on the motor is converted into electrical energy within the safe charging power allowed by the power battery for energy recovery, and the remaining energy is converted into heat generated by the motor itself and consumed by the electric drive cooling system. The remaining torque compensation required for braking is provided by the brake disc. Thus, the loss of the brake caliper during excessive braking can be effectively reduced, and the overcharging burden on the battery brought by the energy recovery system when the battery's allowed charging power is too low can be reduced.

[0034] In this application, after receiving the braking command through the vehicle control unit, it is judged whether the battery is in a state of limited charging power. When the battery is in a state of limited charging power, it is judged whether the temperature of the brake disc is in a high-temperature state. When it is confirmed that the brake disc is in a high-temperature state, the motor-assisted braking mode is entered.

[0035] According to the control method of motor-assisted braking in an embodiment of the present invention, by converting part of the recovered kinetic energy into heat generated by the motor itself through motor-assisted braking for consumption, it is possible to avoid the energy of kinetic energy recovery being converted into electrical energy of the battery and causing overcharging of the battery when the battery has low or no power supply, increasing the protection of the battery. At the same time, overheating of the brake disc can be avoided during braking, increasing the energy consumption path for the energy generated during braking and coasting, and increasing the service life of the brake disc.

[0036] Optionally, as Figure 1 shown, when the battery is in a state of limited charging power, the method includes: Obtaining at least one parameter among the battery power, temperature, and health status; Confirming that the maximum allowable charging power of the battery is lower than a threshold; The battery is in a state of limited charging power.

[0037] Optionally, after the vehicle control unit receives the braking command, it monitors and obtains the parameters of the battery. The parameters include the battery power, temperature, and health status, and confirms the maximum allowable charging power of the battery according to the obtained battery parameters. If the maximum allowable charging power of the battery is lower than the threshold, the battery cannot be charged or the charging ability is limited, such as in the case of low or no power supply. Among them, low power supply can be considered when the battery power exceeds 80%. The conditions for low power supply here can be specifically set according to actual needs and are not specifically limited. When it is confirmed that the maximum allowable charging power of the battery is lower than the threshold, it is judged that the battery is in a state of limited charging power. Thus, through the acquisition and judgment of the battery-related parameters, it is convenient to make a more accurate judgment on whether the battery is in a state of limited charging power, and the process of the control method is more accurate.

[0038] Optionally, the threshold for allowing the maximum charging power of the battery is G, where G satisfies: G ≤ 10 KW. That is, in the specific implementation process, when the charging power allowed by the vehicle's battery is less than the threshold, i.e., 10 KW, it can be determined that the battery is in a state of limited charging power.

[0039] Optionally, in combination with Figure 1 , after confirming that the maximum charging power allowed for the battery is lower than the threshold, the method includes: The vehicle controller obtains the deceleration required by the vehicle and detects the real-time temperature of each brake disc; The temperature of any one brake disc is greater than or equal to the safety threshold temperature; Confirm that the brake disc is in a high-temperature state.

[0040] Specifically, when the maximum charging power is lower than the threshold, usually 10 KW, the vehicle controller obtains the corresponding deceleration required by the vehicle according to the brake pedal level and monitors the real-time temperature of each brake disc. When the temperature of any one brake disc reaches the safety threshold temperature, it is determined that the brake disc is in a high-temperature state.

[0041] Further, the temperature of any one brake disc is greater than or equal to 90% of the upper limit of the safety threshold temperature; confirm that the brake disc is in a high-temperature state. That is, to more precisely control the motor, when the temperature of any one brake disc is greater than or equal to 90% of the upper limit of the safety threshold temperature, it can be determined that the brake disc is in a high-temperature state.

[0042] Optionally, after confirming that the brake disc is in a high-temperature state, the method includes: The vehicle controller obtains the motor temperature and the transmission oil temperature; The motor temperature and the transmission oil temperature are lower than 80% of the upper limit of the safety threshold temperature; Enter the motor-assisted braking state and compensate the brake caliper for braking.

[0043] The vehicle controller can obtain the real-time driving motor temperature through the motor controller. The acquisition method can be to set a temperature sensor to obtain the motor temperature and the transmission oil temperature. Here, the transmission oil temperature refers to the temperature of the oil in the transmission. When the motor temperature and the transmission oil temperature are lower than 80% of the upper limit threshold temperature, it is determined that the motor-assisted braking state can be entered, and the brake caliper is compensated for braking.

[0044] Optionally, as Figure 2 shown, when entering the motor-assisted braking state and compensating the brake caliper for braking, the method includes: Determine to enter the motor-assisted braking; Obtain the deceleration corresponding to the brake pedal level; Calculate the total torque required for braking.

[0045] Optionally, when the driver presses the brake pedal and it is determined that motor-assisted braking is engaged, the deceleration required by the vehicle is determined based on the triggering degree of the brake pedal, and thus the total torque required for vehicle braking can be calculated. Part of the energy is consumed by motor heating, the brake disc intervenes, and the brake caliper performs braking. Braking is carried out by compensating for the braking of the brake caliper, resulting in better braking effect. While effectively avoiding overheating of the brake caliper, overheating of the motor is also avoided, protecting the service life of the motor and the brake caliper.

[0046] Optionally, as Figure 2 shown, after entering the motor-assisted braking mode, the method includes: Obtain the battery power and the real-time energy consumption power of the whole vehicle; Calculate the maximum allowable charging power of the battery; Determine the motor energy recovery power.

[0047] Specifically, determine whether to enter the motor low-feed auxiliary braking or no-feed auxiliary braking according to the allowable charging condition of the battery. When the battery state allows charging but the charging power is less than 10 kW, the motor low-efficiency power generation auxiliary braking is used to reduce the kinetic energy recovery motor power generation power, thereby reducing the risk of overcharging the power battery. At this time, calculate the real-time energy consumption power of the vehicle, calculate the maximum allowable charging power of the battery, and determine the motor energy recovery power to ensure that after recovering part of the energy converted into electric energy, the remaining energy can be consumed by motor heating or brake disc heating, ensuring the accuracy of braking.

[0048] Optionally, after determining the motor energy recovery power, the method includes: The battery allows charging, and the charging power is less than or equal to the preset threshold; The motor enters the low-efficiency power generation auxiliary braking strategy.

[0049] Optionally, when it is determined that the motor enters the low-efficiency power generation auxiliary braking, calculate the real-time energy consumption power of the vehicle, ensure that the driving motor power generation power is equal to or slightly greater than the real-time energy consumption power of the vehicle, and at the same time, based on the safe heat dissipation power of the vehicle's electric drive system, ensure that the motor heating is within the controllable range. At this time, the total power of the driving motor low-efficiency power generation braking is the sum of the power generation power and its total heating power, and the total heating power of the motor includes the heating power of the stator and the rotor.

[0050] Optionally, after the motor enters the low-efficiency power generation auxiliary braking, the method includes: Calculate the real-time energy consumption power of the whole vehicle; Confirm that the motor power generation power is greater than or equal to the real-time energy consumption power of the whole vehicle; Confirm that the motor heating is within the threshold; Adjust the motor power generation power and heating power.

[0051] When the battery is about to be fully charged or in an extremely low temperature scenario, in order to protect the battery, the allowed charging power is very low. At this time, the feeding power can be reduced by inefficient power feeding of the motor to complete motor-assisted braking. The specific implementation method is to change the angle between the direct axis and the quadrature axis of the generated current in the motor controller, change the magnitudes of the direct axis and quadrature axis currents, and realize the adjustment between the motor generating power and the heating power. In this application, the generating power is reduced and the heating power is increased, so that part of the energy generated by the braking torque is converted into electrical energy to charge the battery, and part is converted into motor heat loss and taken away by the cooling system.

[0052] Optionally, for the control of the torque-speed range and inefficient generation efficiency corresponding to the inefficient motor generation area, Figure 4 The motor feeding efficiency diagram of the torque-speed corresponding operating points at the rated current during inefficient motor generation-assisted braking is shown. It can be seen that if you want to keep the motor feeding efficiency at a low level (within 72%), the motor can maintain a large braking torque at low speeds, and the braking effect is good at low speeds.

[0053] Figure 5 It is the motor heat generation diagram corresponding to torque-speed. It can be seen that the heat generation during motor-assisted braking is basically proportional to the braking vehicle speed (i.e., the motor speed). Therefore, at a lower vehicle speed, that is, at a lower speed, the greater the braking torque, the lower the motor heat generation.

[0054] Optionally, as Figure 2 shown, after determining the motor energy recovery power, the method includes: The battery does not allow charging; The motor enters the non-feeding motor-assisted braking strategy.

[0055] Optionally, when the motor enters the non-feeding motor-assisted braking strategy, the method includes: The three-phase windings of the motor are short-circuited for braking; or, The stator of the motor is energized with three-phase direct current for braking.

[0056] The battery not allowing charging includes but is not limited to situations where the battery is fully charged, cannot be charged due to low ambient temperature, or cannot be charged due to battery damage. At this time, when using the drive motor for assisted braking, it is completely not allowed for the motor to feed power. Braking can be achieved by fully connecting the upper or lower bridge arm of the IGBT to short-circuit the three-phase windings of the motor, or by applying three-phase direct current to the stator to achieve motor braking.

[0057] Optionally, for the motor three-phase winding short-circuit braking, the method includes: The braking instantaneous current reaches a preset threshold; Short-circuit any two-phase currents in the three-phase electricity; Short-circuit the other phase current in the three-phase electricity; Enter the motor three-phase winding short-circuit braking.

[0058] Optionally, after the short-circuit braking of the three-phase windings of the motor, the method includes: Controlling the current angle at the time of switching in to cancel the line voltage generated by the back electromotive force on the three-phase windings.

[0059] For the short-circuit braking of the three-phase windings of the motor, in combination with Figure 6a and Figure 6b , its principle is soft-switching steady-state short circuit, that is, by judging the sector where the current is located at the moment of braking, controlling the switching sequence of the three-phase bridge of the inverter to short-circuit two-phase currents first and then the third-phase current, and gradually entering the three-phase short-circuit state of the winding. By controlling the current angle at the time of switching in, the line voltage generated by the back electromotive force on the three-phase windings is cancelled, so that the instantaneous current at the time of short circuit approaches zero.

[0060] Figure 6a and Figure 6b show the schematic diagram of the switching sequence in one case of the soft-switching steady-state short-circuit strategy. This method effectively avoids the phenomenon of current surge caused by directly entering the three-phase short circuit. Different from the traditional method of directly connecting the IGBT three-phase bridge arm for hard-switching steady-state short circuit, the current peak at the time of entering the short circuit has no obvious change, which greatly protects the motor and the motor controller circuit.

[0061] Optionally, in Fig. 6, S1 and S3 are connected in short circuit, S5 remains disconnected, and S2, S4, and S6 remain disconnected to achieve two-phase short circuit; Figure 7 In, S1, S3, and S5 are connected in short circuit, and S2, S4, and S6 remain disconnected to achieve three-phase short circuit.

[0062] Optionally, when the stator of the motor is energized with three-phase direct current for braking, the method includes: Obtaining the braking power of the motor and the real-time vehicle speed, and calculating the braking torque of the motor; Obtaining the total torque required for braking; Determining the required caliper braking compensation torque; The braking module performs caliper compensation braking.

[0063] For the stator energized with direct current for auxiliary braking, its principle is that when the vehicle needs to decelerate or brake, the motor controller supplies direct current to the three-phase windings of the motor instead of alternating current. The direct current will generate a fixed magnetic field in the motor windings. This magnetic field interacts with the rotating magnetic field generated by the permanent magnet. Since the magnetic field generated by the direct current is stationary while the rotor (permanent magnet) is still rotating, an electromagnetic force that hinders the movement of the rotor will be generated between the two, thus achieving the braking effect and converting part of the energy generated by the vehicle braking into winding heating and eddy current loss on the rotor.

[0064] Thus, in the present application, through motor-assisted braking, while reducing the risk of overcharging of the power battery, part of the energy generated by braking is shared by the motor, reducing the risks of excessive wear and overheating of the brake discs, and greatly enhancing the safety during braking of range-extended and pure electric vehicle models.

[0065] Optionally, the required caliper compensation torque is calculated based on the braking torque during inefficient power generation and the total braking torque, and caliper compensation braking is performed.

[0066] Specifically, after the motor executes the inefficient power generation strategy, the motor braking torque is calculated based on the motor braking power and the real-time vehicle speed. Based on the obtained total required braking torque, the required caliper braking compensation torque can be determined. The motor controller sends an instruction to the braking module to perform caliper compensation braking. When the state of the brake pedal changes, the driving motor power generation can be adjusted by changing the direct-axis and quadrature-axis current angles, or the caliper braking force can be changed to linearly adjust the vehicle braking torque, so as to reasonably distribute the energy recovered during braking and better protect the battery, motor, and brake calipers.

[0067] Optionally, when entering the motor-assisted braking mode, the method further includes: Real-time recording of the motor temperature value, three-phase current value, and motor power generation duration; Any one of the recorded values of the motor temperature value, three-phase current value, and motor power generation duration reaches the allowable maximum value; Disconnect the motor-assisted braking.

[0068] Specifically, to ensure the safe operation and service life of the motor after it cuts into the inefficient power generation state are not affected, it is necessary to real-time record the temperature values at various positions of the motor, the three-phase current values, and the motor power generation duration, which are monitored by sensors and transmitted to the control system. At the same time, the winding and magnet temperatures are estimated based on the motor temperature and the electronic pump speed, and the cooling strategy is optimized by adjusting each valve body in real time. The above discussion elaborates on the major risk items during motor inefficient power generation-assisted braking, namely, the large amount of motor heat generation and the high risk of magnet demagnetization. At this time, the recording of the motor temperature and the estimation of the magnet temperature, as well as the adjustment of the local cooling flow rate of the motor, are extremely important, which can ensure the upper limit of the braking power and minimize the risks of stator heating and magnet demagnetization caused by harmonics during motor inefficient power generation-assisted braking.

[0069] Optionally, while disconnecting the motor-assisted braking, the method further includes: Calculating the braking torque to determine the required additional caliper compensation torque; Single braking of the brake disc.

[0070] When the motor temperature or current exceeds the allowable maximum value, the motor-assisted braking state is disconnected. At the same time, the braking torque is calculated to determine the required additional caliper compensation torque, and the vehicle enters the state of single braking using the brake disc.

[0071] Specifically, this step is to passively exit the drive motor assisted braking. Excessively high winding temperature or too large three-phase winding current value will increase the risks such as damage to the motor winding insulation, damage to the motor controller circuit, or overcurrent damage to the inverter module. If the detected value is greater than the threshold, after calculating the motor braking torque value at this speed, immediately disconnect the upper and lower bridge switches of the inverter to disconnect the motor. At this time, the vehicle enters a state where it is completely braked by the brake calipers. After the motor is disconnected, the braking force of the calipers is increased according to the calculated torque value to make up for it, ensuring the braking smoothness of the user when driving.

[0072] Optionally, after real-time recording the motor temperature value, three-phase current value, and motor power generation duration, before any of the recorded values of the motor temperature value, three-phase current value, and motor power generation duration reaches the allowable maximum value, the method includes: Calculate the temperatures of the three-phase windings and the permanent magnets. Determine the motor cooling strategy.

[0073] The estimation of the stator and rotor temperatures of the motor and the cooling strategy during motor power generation are formulated here: Figure 7 The working principle of the hydraulic module is shown. The oil flow rates of the stator and rotor are controlled by the stator switching valve and the rotor switching valve respectively, and the electronic pump speed controls the total oil flow rate. Taking the electronic pump speed, rotor oil passage valve signal, power generation power, and physical time signal as inputs, the motor winding thermal model will calculate the winding temperature Tw in real time according to the above conditions. When Tw < Tw1, the electronic pump speed remains unchanged and the stator switching valve remains open. When Tw1 < Tw < Tw2, the electronic pump speed increases and the oil flow rate increases. When Tw > Tw2, exit the motor assisted braking mode. Similarly, the rotor permanent magnet thermal model will calculate the core temperature Tm of the permanent magnet in real time. When Tm < Tm1, the electronic pump speed remains unchanged and the rotor oil passage valve remains closed. When Tm1 < Tm < Tm2, the electronic pump speed increases, the rotor oil passage valve opens, and the oil flow rate increases. When Tm > Tm2, exit the motor assisted braking mode. This cooling strategy ensures that local overheating is avoided within the cooling capacity range of the electric drive system.

[0074] Optionally, to determine the motor cooling strategy, the method includes: The temperature of the motor stator or rotor reaches the safety threshold temperature; Adjust the cooling flow rate of the motor stator or rotor; The temperature of the motor rotor reaches the safety threshold temperature; Disconnect the motor assisted braking.

[0075] Optionally, according to the remaining battery power and the brake pedal level, the electric motor braking power and the caliper compensation torque are adjusted in real time to determine whether the temperature of the motor stator or rotor locally reaches the threshold. When the temperature of the motor stator or rotor locally reaches the threshold, the cooling flow of the stator and rotor is switched to locally focus on cooling the over-temperature area. Then, it is determined again whether the rotor temperature reaches the threshold. When the motor rotor temperature reaches the preset threshold, the electric motor braking is exited, and the brake caliper is fully used for braking. After receiving the brake end signal, the braking is exited.

[0076] Optionally, in combination with Figure 3 , the method includes: The driver releases the brake to issue a brake end command; The motor and the brake disc brake simultaneously, the motor auxiliary brake is exited, and the brake caliper is released; or, The brake disc brakes alone, and the brake caliper is released; The braking ends.

[0077] When the driver releases the brake to issue a brake end command, the braking state at this time is judged. If it is the simultaneous braking of the motor and the brake disc, the motor auxiliary brake is exited first and then the brake caliper is released; if it is the single braking of the brake disc, the brake caliper is released.

[0078] Specifically, this step is an active braking exit. After the motor controller receives the brake end command after the user releases the brake pedal and the vehicle has not entered the single brake disc braking state, the three-phase connection of the drive motor is first disconnected to exit the motor auxiliary braking state, and then the brake caliper is released to end the braking process. If the vehicle enters the single brake disc braking state when the electric motor brake receives the brake end command, that is, the motor has been disconnected and the auxiliary brake has been exited, the brake caliper is directly released to end the vehicle braking process.

[0079] Specifically, in combination with Figure 3, the maximum allowable charging power of the power battery is lower than the threshold; determine whether to allow entry into the drive motor assisted braking; determine the total vehicle braking torque and power; determine the allowable charging power according to the remaining battery power, and calculate the motor energy recovery power; determine the braking recovery torque of the motor in the low power feed state and the caliper braking compensation torque, and start braking; adjust the motor braking power and the caliper compensation torque in real time according to the remaining battery power and the brake pedal level; determine whether the temperature of the motor stator or rotor locally reaches the threshold; when the temperature of the motor stator or rotor locally reaches the threshold, switch the cooling flow of the stator and rotor, and locally focus on cooling the overheated part; determine again whether the rotor temperature reaches the threshold; when the motor rotor temperature reaches the preset threshold, exit the motor braking and fully use the brake caliper braking; exit the braking after receiving the braking end signal. When braking again, the vehicle controller performs a new process according to the braking signal, that is, at this time, return to the judgment of whether the maximum allowable charging power of the power battery is lower than the threshold. Optionally, when it is determined again that the rotor temperature does not reach the threshold, return to the step of adjusting the motor braking power and the caliper compensation torque in real time according to the remaining battery power and the brake pedal level and start again until it is determined again that the stator and rotor temperatures reach the threshold and the motor braking is exited.

[0080] According to the motor of the second aspect embodiment of the present invention, the motor adopts the control method of the motor assisted braking in any one of the above embodiments.

[0081] According to the vehicle of the third aspect embodiment of the present invention, it includes the control method of the motor assisted braking in any one of the above embodiments, or the motor in the above embodiments.

[0082] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation of the present invention.

[0083] In the description of the present invention, the "first feature" and the "second feature" may include one or more of such features. In the description of the present invention, the meaning of "a plurality of" is two or more. In the description of the present invention, the first feature being "above" or "below" the second feature may include the direct contact of the first and second features, or may include the contact of the first and second features not directly but through additional features therebetween. In the description of the present invention, the first feature being "above", "over" and "on" the second feature includes the first feature being directly above and obliquely above the second feature, or merely indicating that the horizontal height of the first feature is higher than that of the second feature.

[0084] In the description of this specification, the description with reference to terms such as "an embodiment", "some embodiments", "schematic embodiments", "examples", "specific examples", 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 invention. In this specification, the schematic expressions of the above terms do not necessarily refer to the same embodiment or example.

[0085] Although the embodiments of the present invention have been shown and described, those of ordinary skill in the art can understand that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the present invention, and the scope of the present invention is defined by the claims and their equivalents.

Claims

1. A control method for motor-assisted braking, characterized in that, The method steps include: The vehicle controller receives a braking instruction; The battery is in a state of limited charging power; Confirm that the brake disc is in a high-temperature state; Enter the motor-assisted braking mode.

2. The control method for motor-assisted braking according to claim 1, characterized in that When the battery is in a state of limited charging power, the method includes: Obtain at least one parameter among the battery power, temperature, and health status; Confirm that the maximum allowable charging power of the battery is lower than the threshold; The battery is in a state of limited charging power.

3. The control method for motor-assisted braking according to claim 2, wherein The threshold value of the maximum allowable charging power of the battery is G, and G satisfies: G ≤ 10KW.

4. The control method of motor-assisted braking according to claim 2, wherein After confirming that the maximum allowable charging power of the battery is lower than the threshold, the method includes: The vehicle controller obtains the deceleration required by the vehicle and detects the real-time temperature of each brake disc; The temperature of any brake disc is greater than or equal to the safety threshold temperature; Confirm that the brake disc is in a high-temperature state.

5. The control method for motor-assisted braking according to claim 4, characterized in that, The temperature of any brake disc is greater than or equal to 90% of the upper limit of the safety threshold temperature; Confirm that the brake disc is in a high-temperature state.

6. The control method of motor-assisted braking according to claim 4, characterized in that, After confirming that the brake disc is in a high-temperature state, the method includes: The vehicle controller obtains the motor temperature and the transmission oil temperature; The motor temperature and the transmission oil temperature are lower than 80% of the upper limit of the safety threshold temperature; Enter the motor-assisted braking state and compensate the brake caliper for braking.

7. The control method of motor-assisted braking according to claim 6, characterized in that, When entering the motor-assisted braking state and compensating the brake caliper for braking, the method includes: Determine to enter the motor-assisted braking; Obtain the deceleration corresponding to the braking pedal level; Calculate the total torque required for braking.

8. The control method of motor-assisted braking according to claim 1, characterized in that, After entering the motor-assisted braking mode, the method includes: Obtain the battery power and the real-time energy consumption power of the vehicle; Calculate the maximum allowable charging power of the battery; Determine the motor energy recovery power.

9. The control method for motor-assisted braking according to claim 8, characterized in that, After determining the motor energy recovery power, the method includes: The battery is allowed to charge, and the charging power is less than or equal to the preset threshold; The motor enters the low-efficiency power generation assisted braking strategy.

10. The control method for motor-assisted braking according to claim 9, wherein After the motor enters the low-efficiency power generation assisted braking, the method includes: Calculate the real-time energy consumption power of the vehicle; Confirm that the motor power generation power is greater than or equal to the real-time energy consumption power of the vehicle; Confirm that the motor heat generation is within the threshold; Adjust the motor power generation power and the heat generation power.

11. The control method for motor-assisted braking according to claim 8, characterized in that, After determining the motor energy recovery power, the method includes: The battery is not allowed to charge; The motor enters the non-feed motor assisted braking strategy.

12. The control method for motor-assisted braking according to claim 11, wherein When the motor enters the non-feed motor assisted braking strategy, the method includes: The three-phase windings of the motor are short-circuited for braking; or, The stator of the motor is energized with three-phase direct current for braking.

13. The control method for motor-assisted braking according to claim 12, characterized in that, When the three-phase windings of the motor are short-circuited for braking, the method includes: The braking instantaneous current reaches the preset threshold; Short-circuit any two-phase currents in the three-phase electricity; Short-circuit the other-phase current in the three-phase electricity; Enter the short-circuit braking of the three-phase windings of the motor.

14. The control method for motor-assisted braking according to claim 12, characterized in that, After the short-circuit braking of the three-phase windings of the motor, the method includes: Control the current angle at the cut-in to cancel the line voltage generated by the back electromotive force on the three-phase windings.

15. The control method for motor-assisted braking according to claim 12, characterized in that, When the stator of the motor is energized with three-phase direct current for braking, the method includes: Obtain the motor braking power and the real-time vehicle speed, and calculate the motor braking torque; Obtain the total torque required for braking; Determine the required caliper braking compensation torque; The braking module performs caliper compensation braking.

16. The control method of motor-assisted braking according to claim 1, characterized in that, When entering the motor-assisted braking mode, the method further includes: Record the motor temperature value, the three-phase current value, and the motor power generation duration in real time; Any of the recorded values of the motor temperature value, the three-phase current value, and the motor power generation duration reaches the allowable maximum value; Disconnect the motor-assisted braking.

17. The control method for motor-assisted braking according to claim 16, characterized in that, While disconnecting the motor-assisted braking, the method further includes: Calculate the additional compensation torque required for the caliper to determine the braking torque; Single braking of the brake disc.

18. The control method for motor-assisted braking according to claim 16, wherein After the motor temperature value, three-phase current value, and motor power generation duration are recorded in real time, and before any of the recorded values of the motor temperature value, three-phase current value, and motor power generation duration reaches the allowable maximum value, the method includes: Calculate the temperatures of the three-phase windings and the permanent magnets; Determine the motor cooling strategy.

19. The control method for motor-assisted braking according to claim 18, characterized in that, Determine the motor cooling strategy, the method includes: The temperature of the motor stator or rotor reaches the safety threshold temperature; Adjust the cooling flow rate of the motor stator or rotor; The temperature of the motor stator or rotor reaches the safety threshold temperature; Disconnect the motor auxiliary brake.

20. The control method for motor-assisted braking according to any one of claims 1-19, wherein the method Includes: The driver releases the brake to issue a braking end command; The motor and the brake disc brake simultaneously, the motor auxiliary brake is exited, and the brake caliper is released; Or, Single braking of the brake disc, and the brake caliper is released; Braking ends.

21. A motor, characterized in that, The motor adopts the control method of the motor auxiliary brake described in any one of claims 1-20.

22. A vehicle, characterized in that, Includes the control method of the motor auxiliary brake described in any one of claims 1-20, or the motor described in claim 21.

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