A controller for driving a motor and related equipment

Abstract

The present application provides a controller for a drive motor and related equipment thereof, wherein the drive motor performs heat exchange with a power battery through a cooling circuit, the drive motor includes a three-phase stator winding, and the power battery supplies power to the three-phase stator winding through an inverter circuit; wherein the controller controls the output current of the inverter circuit in response to the temperature of the power battery being greater than or equal to a preset battery temperature so that the drive motor outputs torque to drive the wheels; the controller adjusts the output current of the inverter circuit in response to the temperature of the power battery being less than a preset battery temperature and according to the comparison result between the voltage of the power battery and the preset battery voltage, and controls the output current of the inverter circuit so that the heat generated by the three-phase stator winding of the drive motor increases. By implementing the present application, the heat generated by the drive motor can be used to heat the power battery, thereby reducing costs.

Description

Technical Field

[0001] The present application relates to the field of new energy vehicle technology, and in particular to a controller for driving a motor and related equipment. Background Art

[0002] In electric vehicles, the power battery provides electrical energy to the drive motor, which converts the electrical energy into mechanical energy to drive the electric vehicle. However, the power battery has an optimal operating temperature range. For example, the optimal operating temperature of the lithium battery is around 20°C. When the battery temperature of the power battery is too low, the battery capacity of the power battery is greatly lost, and the discharge rate and charging rate will decrease. Therefore, when using electric vehicles in low temperature environments, the power battery needs to be heated.

[0003] A heating device for a power battery provided by the prior art is as follows Figure 1 As shown, the heating device includes a positive temperature coefficient thermistor (PTC) and a switch tube. When the battery management system (BMS) in the electric vehicle determines that the temperature of the power battery BAT is low, the switch tube is controlled to close, and the PTC is connected to the circuit to generate Joule heat, which can heat the coolant in the cooling circuit, thereby heating the power battery BAT. The heating method of the prior art requires the addition of an additional heating device, which is costly. Summary of the invention

[0004] The present application provides a controller for a drive motor and related equipment thereof, which can utilize the heat generated by the drive motor to heat the power battery and reduce costs.

[0005] In the first aspect, the embodiment of the present application provides a controller for a drive motor, wherein the drive motor includes a three-phase stator winding. The three-phase stator winding is connected to the output end of the inverter circuit and can receive the output current of the inverter circuit; the input end of the inverter circuit is connected to the power battery, that is, the power battery supplies power to the three-phase stator winding through the inverter circuit. In addition, the control end of the inverter circuit is connected to the controller.

[0006] In a specific implementation, in response to the temperature of the power battery being greater than or equal to a preset battery temperature, the controller controls the output current of the inverter circuit so that the drive motor outputs torque to drive the wheels; in response to the temperature of the power battery being less than a preset battery temperature, the controller adjusts the output current of the inverter circuit according to a comparison result between the voltage of the power battery and the preset battery voltage, and controls the output current of the inverter circuit so that the heat generated by the three-phase stator winding of the drive motor increases.

[0007] Since the three-phase stator winding and the rotor winding can exchange heat with the power battery through the cooling circuit, that is, the heat generated by the three-phase stator winding can be used to heat the power battery. Then, when the heat generated by the three-phase stator winding increases, the heating rate of the power battery increases. It should be explained that the faster heating rate of the power battery can be understood as the increase in the temperature of the power battery per unit time.

[0008] In combination with the first aspect, in a first possible implementation, the controller outputs a first control signal to control the output current of the inverter circuit so that the output torque of the drive motor is zero in response to the temperature of the power battery being lower than a preset battery temperature.

[0009] In combination with the first aspect or the first possible implementation of the first aspect, in a second possible implementation, the controller controls the output current of the inverter circuit to meet a first preset condition in response to the temperature of the power battery being less than a preset battery temperature. At this time, when the output current of the inverter circuit meets the first preset condition, the DC component and the AC component of the quadrature-axis current of the three-phase stator winding are zero.

[0010] In combination with the first aspect or any one of the above possible implementations of the first aspect, in a third possible implementation, the controller outputs a first control signal to control the output current of the inverter circuit in response to the voltage of the power battery being less than or equal to the preset battery voltage; the controller outputs a third control signal to control the output current of the inverter circuit in response to the voltage of the power battery being greater than the preset battery voltage. In an embodiment of the present application, when the voltage of the power battery is greater than the preset battery voltage, the controller may inject harmonics into the output current of the inverter circuit, that is, inject harmonics into the current of the three-phase stator winding, further increase the heat generated by the three-phase stator winding, and accelerate the heating efficiency of the power battery.

[0011] In combination with the first aspect or any one of the above possible implementation methods of the first aspect, in a fourth possible implementation method, when the controller responds to the voltage of the power battery being less than or equal to the preset battery voltage, the controller controls the output current of the inverter circuit to meet a first preset condition; when the controller responds to the voltage of the power battery being greater than the preset battery voltage, the controller controls the output current of the inverter circuit to meet a third preset condition, and when the inverter circuit outputs a current that meets the third preset condition, the AC component of the cross-axis current of the three-phase stator winding is not zero.

[0012] In combination with the first aspect, in a fifth possible implementation, the drive motor further includes a rotor winding. The rotor winding is connected to the output end of the DC conversion circuit and can receive the output current of the DC conversion circuit; the input end of the DC conversion circuit is connected to the power battery, that is, the power battery supplies power to the rotor winding via the DC conversion circuit. And the control end of the DC conversion circuit is connected to the controller.

[0013] In a specific implementation, in response to the temperature of the power battery being lower than a preset battery temperature, the controller outputs a second control signal to control the output current of the inverter circuit and the DC conversion circuit so that the output torque of the drive motor is zero.

[0014] In the embodiment of the present application, in addition to the three-phase stator winding being connected to the inverter circuit, the rotor winding is also connected to the DC conversion circuit, that is, the drive motor at this time can be understood as a synchronous motor. In the implementation of the embodiment of the present application, in addition to utilizing the heat generated by the three-phase stator winding, the heat generated by the rotor winding can also be utilized to heat the power battery, without the need for an additional heating device, which can reduce costs. That is, the heat generated by the drive motor in the embodiment of the present application can be further increased, thereby further accelerating the heating rate of the power battery.

[0015] In combination with the first aspect, in a sixth possible implementation, the drive motor further includes a rotor winding. The rotor winding is connected to the output end of the DC conversion circuit and can receive the output current of the DC conversion circuit; the input end of the DC conversion circuit is connected to the power battery, that is, the power battery supplies power to the rotor winding via the DC conversion circuit. And the control end of the DC conversion circuit is connected to the controller.

[0016] In a specific implementation, in response to the temperature of the power battery being lower than a preset battery temperature, the controller controls the output current of the inverter circuit and the DC conversion circuit to meet a second preset condition. At this time, the torque of the drive motor is zero, and the direct axis current of the three-phase stator winding is in a preset proportional relationship with the current of the rotor winding.

[0017] In combination with the fifth possible implementation of the first aspect or in combination with the sixth possible implementation of the first aspect, in a seventh possible implementation, the controller outputs a second control signal to control the output current of the inverter circuit and the DC conversion circuit in response to the voltage of the power battery being less than or equal to the preset battery voltage; the controller outputs a fourth control signal to control the output current of the inverter circuit and the DC conversion circuit in response to the voltage of the power battery being greater than the preset battery voltage. In the embodiment of the present application, when the voltage of the power battery is greater than the preset battery voltage, harmonics can be injected into the output current of the inverter circuit and the output current of the DC conversion circuit, that is, harmonics can be injected into the current of the three-phase stator winding and the current of the rotor winding, so as to further increase the heat generated by the drive motor and accelerate the heating efficiency of the power battery.

[0018] In combination with the fifth possible implementation of the first aspect or in combination with the sixth possible implementation of the first aspect, in an eighth possible implementation, the controller controls the output current of the inverter circuit and the output current of the DC conversion circuit to meet the second preset condition in response to the voltage of the power battery being less than or equal to the preset battery voltage; the controller controls the output current of the inverter circuit and the output current of the DC conversion circuit to meet the fourth preset condition in response to the voltage of the power battery being greater than the preset battery voltage. At this time, the fourth condition is that the torque of the drive motor is zero. At this time, the cross-axis current of the three-phase stator winding includes a DC component and at least one AC component, the current of the rotor winding includes a DC component and at least one AC component, and the DC component of the cross-axis current of the three-phase stator winding is in a preset proportional relationship with the DC component of the rotor winding.

[0019] In combination with the first aspect or any possible implementation of the first aspect, in a ninth possible implementation, the controller controls the output current of the inverter circuit to switch from satisfying the third preset condition to satisfying the first preset condition, or from the fourth preset condition to satisfying the second preset condition in response to the temperature of the three-phase stator winding being greater than the preset stator temperature or the temperature of the rotor winding being greater than the preset rotor temperature. At this time, the controller controls the output current of the inverter circuit to switch from a mode of injecting harmonics to a mode of not injecting harmonics, which can reduce the copper loss and iron loss of the three-phase stator winding, avoid damage to the three-phase stator winding and the rotor winding due to excessively high temperatures, and has good safety and high reliability.

[0020] In combination with the first aspect or any one of the above possible implementations of the first aspect, in a tenth possible implementation, the controller reduces the output current of the inverter circuit in response to the temperature of the three-phase stator winding being greater than a preset stator temperature or the temperature of the rotor winding being greater than a preset rotor temperature. By implementing the embodiments of the present application, damage to the three-phase stator winding due to excessive temperature can be avoided, and the safety and reliability are high.

[0021] In the second aspect, an embodiment of the present application provides a motor control unit, which includes a controller and an inverter circuit. The controller can control the output current of the inverter circuit, the output end of the inverter circuit is connected to the three-phase stator winding of the drive motor, and the input end of the inverter circuit is connected to the power battery.

[0022] In a specific implementation, in response to the temperature of the power battery being greater than or equal to the preset battery temperature, the inverter circuit outputs a current that satisfies a fifth preset condition so that the drive motor outputs torque to drive the wheels; in response to the temperature of the power battery being less than the preset battery temperature, the inverter circuit outputs a current that satisfies a sixth preset condition so that the heat generated by the three-phase stator winding of the drive motor increases, and adjusts the output current based on a comparison result between the voltage of the power battery and the preset battery voltage to change the heat generated by the three-phase stator winding of the drive motor.

[0023] In combination with the second aspect, in a first possible implementation, in response to the temperature of the power battery being lower than a preset battery temperature, the inverter circuit outputs a current that satisfies a sixth preset condition so that the output torque of the drive motor is zero.

[0024] In combination with the second aspect or the first possible implementation of the second aspect, in a second possible implementation, the motor control unit further includes a DC conversion circuit, an output end of the DC conversion circuit is connected to the rotor winding of the drive motor, and an input end of the DC conversion circuit is connected to the power battery. The sixth preset condition includes the first preset condition, the second preset condition, the third preset condition, and the fourth preset condition.

[0025] In a specific implementation, when the inverter circuit outputs a current that satisfies the first preset condition or the third preset condition, the DC component of the cross-axis current of the three-phase stator winding is zero; when the inverter circuit and the DC conversion circuit output a current that satisfies the third preset condition or the fourth preset condition, the AC component of the cross-axis current of the three-phase stator winding is not zero; when the inverter circuit and the DC conversion circuit output a current that satisfies the second preset condition or the fourth preset condition, the direct-axis current of the three-phase stator winding is in a preset proportional relationship with the current of the rotor winding.

[0026] In combination with the second possible implementation manner of the second aspect, in a third possible implementation manner, in response to the temperature of the power battery being lower than a preset battery temperature, the inverter circuit outputs a current that satisfies a first preset condition.

[0027] In combination with the second possible implementation method of the second aspect, in a fourth possible implementation method, in response to the voltage of the power battery being less than or equal to the preset battery voltage, the inverter circuit outputs a current that satisfies a first preset condition; in response to the voltage of the power battery being greater than the preset battery voltage, the inverter circuit outputs a current that satisfies a third preset condition.

[0028] In combination with the second possible implementation method of the second aspect, in a fifth possible implementation method, in response to the temperature of the power battery being lower than a preset battery temperature, the DC conversion circuit and the inverter circuit output a current that satisfies a second preset condition so that the output torque of the drive motor is zero.

[0029] In combination with the second possible implementation method of the second aspect, in a sixth possible implementation method, in response to the voltage of the power battery being less than or equal to the preset battery voltage, the inverter circuit and the DC conversion circuit output a current that satisfies the second preset condition; in response to the voltage of the power battery being greater than the preset battery voltage, the inverter circuit and the DC conversion circuit output a current that satisfies the fourth preset condition.

[0030] In combination with the second possible implementation of the second aspect, in a seventh possible implementation, when the inverter circuit and the DC conversion circuit output a current that satisfies the fourth preset condition, the frequency of the AC component of the direct-axis current of the three-phase stator winding is different from the frequency of the AC component of the current of the rotor winding. By implementing the embodiment of the present application, the mutual coupling of the AC component in the current of the three-phase stator winding and the AC component in the current of the rotor winding can be avoided, thereby avoiding the drive motor from generating torque.

[0031] In a third aspect, an embodiment of the present application provides an electric drive system, which includes an inverter circuit, a DC conversion circuit, a drive motor, and a controller in combination with the first aspect or in combination with any one of the possible implementations of the first aspect. The electric drive system is connected to a power battery. In a specific implementation, the drive motor includes a rotor winding and a three-phase stator winding, wherein the three-phase stator winding is connected to the output end of the inverter circuit, the rotor winding is connected to the output end of the DC conversion circuit, the input end of the inverter circuit and the input end of the DC conversion circuit are connected to the power battery, and the control end of the inverter circuit and the control end of the DC conversion circuit are connected to the controller.

[0032] In a fourth aspect, an embodiment of the present application provides an electric vehicle, comprising a power battery and an electric drive system in combination with the second aspect, wherein the power battery can provide power to the electric drive system.

[0033] It should be understood that the implementation and beneficial effects of the above-mentioned aspects of the present application can refer to each other. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 A heating device for a power battery provided by the prior art;

[0035] Figure 2 A schematic diagram of a scenario of an electric vehicle provided in an embodiment of the present application;

[0036] Figure 3 A schematic diagram of the structure of an electric drive system provided in an embodiment of the present application;

[0037] Figure 4 A schematic diagram of a partial chassis structure of an electric vehicle provided in an embodiment of the present application;

[0038] Figure 5 A circuit diagram of an electric drive system provided in an embodiment of the present application;

[0039] Figure 6 A schematic diagram of a process for controlling heat generation of an electric drive system provided in an embodiment of the present application;

[0040] Figure 7 It is a schematic diagram of the three-phase current and dq coordinates of the motor;

[0041] Figure 8 A schematic diagram of another process for controlling heat generation of an electric drive system provided in an embodiment of the present application;

[0042] Fig. 9 A schematic diagram of another process for controlling heat generation of an electric drive system provided in an embodiment of the present application;

[0043] Fig.10 A schematic diagram of another process for controlling heat generation of an electric drive system provided in an embodiment of the present application;

[0044] Fig.11 A schematic diagram of the process of heat exchange between the drive motor and the power battery provided in an embodiment of the present application. DETAILED DESCRIPTION

[0045] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0046] The implementation of the technical solution of the present application is further described in detail below in conjunction with the accompanying drawings.

[0047] See also Figure 2 , Figure 2 A schematic diagram of a scene of an electric car provided in an embodiment of the present application. Figure 2 As shown, the electric vehicle 20 includes an electric drive system 201 and a power battery 202. The power battery 202 is connected to the electric drive system 201, and the power battery 202 provides power to the electric drive system 201.

[0048] A cooling circuit is provided between the power battery 202 and the electric drive system 201, and the electric drive system 201 exchanges heat with the power battery 202 through the cooling circuit. At this time, the heat generated by the electric drive system 201 can heat the power battery 202.

[0049] The following is an exemplary description of how the electric drive system 201 generates heat and how the power battery 202 is heated in conjunction with the structure of the electric drive system 201 .

[0050] See also Figure 3 , Figure 3 This is a schematic diagram of the structure of the electric drive system provided in the embodiment of the present application. Figure 3 As shown, the electric drive system 201 includes an inverter circuit 2011 , a DC conversion circuit 2012 , a drive motor 2013 and a controller 2014 .

[0051] The input end of the inverter circuit 2011 and the input end of the DC conversion circuit 2012 are connected to the power battery 202. The power battery 202 may be, for example, a lithium-ion battery, a lead-acid battery, a solar cell, etc., and the present application does not limit the type of the power battery.

[0052] The output end of the inverter circuit 2011 is connected to the drive motor 2013, specifically connected to the three-phase stator winding of the drive motor 2013. The inverter circuit 2011 can convert the direct current output by the power battery 202 into three-phase alternating current, that is, the output current of the inverter circuit 2011 in the embodiment of the present application is specifically implemented as three-phase alternating current. The inverter circuit transmits the output three-phase alternating current to the three-phase stator winding respectively. The inverter circuit 2011 can be specifically implemented as a three-phase three-level inverter or a three-phase two-level inverter, etc.

[0053] The output end of the DC conversion circuit 2012 is connected to the drive motor 2013, specifically connected to the rotor winding of the drive motor 2013. The DC conversion circuit 2012 can convert the DC voltage output by the power battery 202, and at this time, the DC conversion circuit 2012 can be specifically implemented as a DC / DC converter, such as a BUCK converter, a BOOST converter, or a BUCK-BOOST converter.

[0054] The controller 2014 is connected to the control end of the inverter circuit 2011 and the control end of the DC conversion circuit 2012, and the controller 2014 can send control signals to the inverter circuit 2011 and the DC conversion circuit 2012, so as to control the output current of the inverter circuit 2011 and the output current of the DC conversion circuit 2012. Exemplarily, the controller 2014 can be specifically implemented as a central processing unit (CPU), other general-purpose processors, digital signal processors (DSP), application specific integrated circuits (ASIC), field-programmable gate arrays (FPGA) or other programmable logic devices, discrete gates or transistor logic devices, discrete hardware components, etc.

[0055] Furthermore, the output current of the inverter circuit 2011 flows into the three-phase stator winding of the drive motor 2013, and the three-phase stator winding generates Joule heat; the output current of the DC conversion circuit 2012 flows into the rotor winding of the drive motor 2013, and the rotor winding generates Joule heat. At this time, the drive motor 2013 generates heat.

[0056] A cooling circuit is provided between the drive motor 2013 and the power battery 202, and the cooling circuit includes a motor coolant and a battery coolant. In addition, a pump device 203 is provided in the cooling circuit, and the pump device 203 can drive the motor coolant and the battery coolant to circulate in the cooling circuit. The motor coolant can absorb the heat generated by the drive motor 2013, and the motor coolant performs heat exchange with the battery coolant in the cooling circuit; the battery coolant can heat the power battery 202 through heat transfer.

[0057] In one embodiment, the controller 2014 and the inverter circuit 2011 can be integrated into a motor control unit, and the DC conversion circuit 2012 can be integrated into the motor control unit or can be separately arranged. Optionally, the inverter circuit 2011 is integrated into the motor control unit, and the controller 2014 and the DC conversion circuit 2012 are separately arranged. In general, the embodiments of the present application do not limit the specific arrangement positions of the controller, the inverter circuit, and the DC conversion circuit.

[0058] In one embodiment, the electric drive system 201 may include at least two drive motors. Figure 3 The drive motor 2013 shown in the figure can be any drive motor in the electric drive system 201 . Figure 4 For example, the electric drive system 201 includes two drive motors, for example, the electric drive system 201 includes a drive motor 2013A and a drive motor 2013B, the drive motor 2013A drives the front wheels of the electric vehicle 20, and the drive motor 2013B drives the rear wheels of the electric vehicle 20. The drive motor 2013 involved in the present application can be any one of the drive motor 2013A and the drive motor 2013B.

[0059] Exemplarily, the drive motor 2013A may be a permanent magnet synchronous motor, which is the main drive motor of the electric vehicle 20; the drive motor 2013B may be an electrically excited synchronous motor, which is the auxiliary drive motor of the electric vehicle 20. It is understandable that, taking the drive motor 2013 as an example, the drive motor 2013B may not rotate during the rotation of the drive motor 2013A, and the drive motor 2013B is used to heat the power battery 202. Then the application scenario at this time can be specifically implemented as follows: during the process of the main drive motor outputting torque to drive the wheels of the electric vehicle, the auxiliary drive motor outputs zero torque, and the auxiliary drive motor heats the power battery 202, and the auxiliary drive motor is in an idling state. Alternatively, the auxiliary drive motor can also output torque to drive the wheels of the electric vehicle, and the auxiliary drive motor heats the power battery 202 during the process of driving the wheels of the electric vehicle. It needs to be explained that driving the electric vehicle can be understood as providing torque to the electric vehicle, and idling can be understood as the auxiliary drive motor not providing torque to the electric vehicle, that is, the output torque is zero.

[0060] For example, taking the inverter circuit 2011 as a three-phase two-level inverter, the circuit of the electric drive system 201 can be as follows: Figure 5 shown.

[0061] At this time, the inverter circuit 2011 includes three bridge arms. Each bridge arm includes two switch units connected in series, and the switch unit may include at least one switch connected in series or in parallel. In specific practice, the switch unit can select multiple switches in series or in parallel according to the voltage and current of the inverter circuit. Among them, the switch can be specifically implemented as an insulated gate bipolar transistor (IGBT) and its anti-parallel diode, or a metal oxide semiconductor field effect transistor (MOSFET), etc. In general, the embodiment of the present application does not limit the type of switches and the number of switches in the switch unit.

[0062] For example, the switch included in the bridge arm is specifically implemented as an IGBT and its anti-parallel diode. One end of each bridge arm is connected to the positive terminal of the power battery 202, that is, the switch tube Q 51 The collector of the switch tube Q 53 The collector and switch tube Q 55 The collector is connected to the positive terminal of the power battery 202.

[0063] The other end of each bridge arm is connected to the negative terminal of the power battery 202, that is, the switch tube Q 52 The emitter of the switch tube Q 54 The emitter and switch tube Q 56 The emitter is connected to the negative terminal of the power battery 202.

[0064] Optionally, a capacitor unit is connected in parallel between the positive terminal and the negative terminal of the power battery 202. The capacitor unit includes at least one capacitor, for example, a capacitor C 51 The capacitor C 51 The output voltage of the power battery 202 may be filtered.

[0065] The midpoint of each bridge arm is connected to the corresponding stator winding, i.e. the switch tube Q 51 The emitter and switch tube Q 52 The collector is connected to the stator winding U of the drive motor 2013, and the switch tube Q 53 The emitter and switch tube Q 54 The collector is connected to the stator winding V of the drive motor 2013, and the switch tube Q 55 The emitter and switch tube Q 56The collector is connected to the stator winding W of the drive motor 2013.

[0066] The positive terminal of the power battery 202 is also connected to the positive input terminal of the DC conversion circuit 2012, and the negative terminal of the power battery 202 is also connected to the negative input terminal of the DC conversion circuit 2012. The positive output terminal of the DC conversion circuit 2012 is connected to one end of the rotor winding Ls of the drive motor 2013, and the negative output terminal of the DC conversion circuit 2012 is connected to the other end of the rotor winding Ls of the drive motor 2013.

[0067] In one embodiment, the controller 2014 may be connected to the gates of the switches in the inverter circuit 2011 to control the on or off of the switches in the inverter circuit 2011 , thereby controlling the output current of the inverter circuit 2011 .

[0068] In one embodiment, the controller 2014 can also be connected to the control end of the DC conversion circuit 2012, that is, connected to the control end of each switch tube in the DC conversion circuit 2012, to control the conduction or shutdown of each switch tube in the DC conversion circuit 2012, thereby controlling the output current of the DC conversion circuit 2012.

[0069] In one embodiment, the controller 2014 may execute Figure 6 The flow chart shown in FIG. 1 controls the output current of the inverter circuit 2011. Figure 6 As shown, the execution steps of the controller include:

[0070] In step S600, the controller 2014 detects whether the temperature of the power battery 202 is lower than a preset battery temperature. If so, the controller 2014 executes step S601b, otherwise, the controller 2014 executes step S601a to start the drive motor 2013 normally.

[0071] In one embodiment, the controller 2014 may obtain the temperature of the power battery 202 through a battery management system (BMS). Alternatively, the controller 2014 may obtain the temperature of the power battery 202 through a vehicle control unit (VCU).

[0072] The controller 2014 compares the temperature of the power battery 202 with a preset battery temperature, which is any one of the optimal operating temperature ranges of the power battery 202. The preset battery temperature can be adjusted according to the actual operating conditions of the power battery 202, for example, according to the usage time or remaining power of the power battery 202.

[0073] Step S601a: In response to the temperature of the power battery 202 being greater than or equal to the preset battery temperature, the controller 2014 normally starts the drive motor 2013. At this time, the controller 2014 can control the output current of the inverter circuit 2011 so that the drive motor 2013 outputs torque to drive the wheels of the electric vehicle.

[0074] Step S601b: In response to the temperature of the power battery 202 being lower than the preset battery temperature, the controller 2014 adjusts the output current of the inverter circuit 2011 according to the comparison result between the voltage of the power battery 202 and the preset battery voltage. At this time, the controller 2014 controls the output current of the inverter circuit 2011 so that the heat generated by the three-phase stator winding of the drive motor 2013 increases.

[0075] The controller 2014 may specifically control the output current of the inverter circuit 2011 by outputting a control signal to the inverter circuit 2011. The control signal may be a pulse width modulation (PWM) signal.

[0076] For example, when the temperature of the power battery 202 is lower than a preset battery temperature, the controller 2014 may output a first control signal to the inverter circuit 2011 to control the output current of the inverter circuit 2011 , thereby making the output torque of the drive motor 2013 zero.

[0077] For another example, the controller 2014 may control the output current of the inverter circuit 2011 to meet a first preset condition when the temperature of the power battery 202 is lower than a preset battery temperature.

[0078] It is understandable that the output current of the inverter circuit 2011 is the current flowing into the three-phase stator winding, that is, the current of the stator winding U, the current of the stator winding V and the current of the stator winding W. Then, the first control signal can control the current of the three-phase stator winding to meet the first preset condition.

[0079] At present, the current analysis of the three-phase stator winding of the drive motor 2013 can be carried out by using Park Transformation, such as Figure 7 As shown, the three-phase coordinates of the current of the three-phase stator winding are transformed into dq axis coordinates, wherein the d axis (direct axis), also known as the direct axis, is parallel to the rotation axis (magnetic pole axis) of the drive motor 2013. The q axis (quadrature axis), also known as the quadrature axis, is perpendicular to the magnetic pole axis of the drive motor 2013, that is, perpendicular to the d axis.

[0080] At this time, the d-axis current and the q-axis current are equal to the projections of the three-phase stator winding on the d-axis and the q-axis respectively, and the relationship between the d-axis current and the q-axis current and the current of the three-phase stator winding can be expressed by the formula:

[0081]

[0082] Among them, I d is the d-axis current, I q is the q-axis current; I U is the current of stator winding U, I V is the current of stator winding V, I W is the current of the stator winding W; and θ=ωt, ω is the angular frequency of the current signal of each phase stator winding.

[0083] The first preset condition is that the output torque of the drive motor 2013 is zero. At this time, the DC component and AC component of the q-axis current of the three-phase stator winding are both zero, that is, the q-axis current of the three-phase stator winding is zero.

[0084] Torque T of the drive motor 2013 e It can be expressed as:

[0085] T e =1.5p*I q *[M f I f +(L d -L q )I d ] Formula 2

[0086] Among them, p is a constant, M f is the mutual inductance of the rotor winding Ls, I f is the current of the rotor winding Ls, L d is the d-axis inductance, L q is the q-axis inductance. M f , L d and L q These are the device properties of the drive motor 2013.

[0087] Therefore, according to Formula 2, the first preset condition can be expressed as:

[0088] I q =0 Formula 3

[0089] Combining Formula 1 and Formula 3, we can get the current relationship of the three-phase stator winding at this time:

[0090]

[0091] The controller 2014 controls the output current of the inverter circuit 2011 to meet the first preset condition, that is, the three-phase stator winding current of the drive motor 2013 satisfies Formula 4. It can be understood that the current of the three-phase stator winding that satisfies Formula 4 may have multiple current combinations.

[0092] The Joule heat generated by the drive motor 2013 can be expressed by the formula:

[0093] Q=I d 2 ×R s +I f 2 ×R f Formula 5

[0094] Among them, R s is the impedance of the three-phase stator winding, R f is the impedance of the rotor winding.

[0095] Among the multiple current combinations satisfying Formula 4, there is a current combination that can minimize the heat generated by the drive motor 2013, that is, the Q value in Formula 5 is the smallest. The embodiment of the present application abandons the current combination that minimizes the heat generated by the drive motor 2013, and selects other current combinations except the current combination with the minimum heat generated, thereby increasing the heat generated by the drive motor 2013. Further, the current combination that maximizes the heat generated by the drive motor 2013 can be selected.

[0096] For example, the current combination A and the current combination B are included in the multiple current combinations satisfying Formula 4, where the current combination A specifically includes I U =2,I V =1,I W =2; current combination B specifically includes I U =4,I V =2,I W =3, assuming that current combination A and current combination B are substituted into formula 1 to calculate the corresponding I d They are 1A and 0.5A respectively. It can be known that the heat generated by the drive motor calculated by substituting current combination A into formula 5 is greater than the heat generated by the drive motor calculated by substituting current combination B into formula 5. Therefore, the controller can control the output current of the inverter circuit to be combination A.

[0097] In general, when implementing the embodiments of the present application, a current combination that can increase the heat generation of the three-phase stator winding can be selected from various current combinations that meet the first preset condition, that is, a current combination that increases the heat generation of the drive motor can be selected.

[0098] In one embodiment, the controller 2014 may also execute Figure 8The flow chart shown in FIG. 1 is used to adjust the output current of the inverter circuit 2011. Figure 8 As shown, the execution steps of the controller include:

[0099] Step S601b1: The controller 2014 detects whether the voltage of the power battery 202 is greater than the preset battery voltage. If so, execute step S602b; otherwise, execute step S602a.

[0100] The preset battery voltage represents the voltage required for the power battery 202 to inject harmonics into the output current of the inverter circuit 2011. It can be understood that the judgment of the voltage of the power battery is added in step S601b1, and the execution of steps S602a and S602b can be switched, so as to improve the power battery's power efficiency and reduce power waste. Exemplarily, the controller 2014 can collect the voltage of the power battery 202 through the voltage sampling circuit, and compare the voltage of the power battery 202 with the preset battery voltage.

[0101] In one embodiment, in response to the voltage of the power battery 202 being less than or equal to the preset battery voltage, the controller 2014 executes step S602a, that is, the controller 2014 outputs a first control signal to control the output current of the inverter circuit 2011. It can be understood that at this time, the first control signal can control the output current of the inverter circuit 2011 to meet the first preset condition.

[0102] In one embodiment, the controller 2014 executes step S602b in response to the voltage of the power battery 202 being greater than the preset battery voltage, that is, outputting a third control signal to control the output current of the inverter circuit 2011. At this time, the third control signal can control the output current of the inverter circuit 2011 to meet the third preset condition. The third preset condition is that the output torque of the drive motor 2013 is zero. At this time, the q-axis current of the three-phase stator winding includes a DC component and at least one AC component, the DC component of the q-axis current is zero, and the AC component is not zero.

[0103] In a specific implementation, the output current of the inverter circuit 2011 includes a DC component and at least one AC component, and the current of the three-phase stator winding includes a DC component and at least one AC component, that is, harmonics are injected into the current of the three-phase stator winding. Then, the current of the three-phase stator winding can be specifically expressed as:

[0104]

[0105] Among them, I d_0 is the DC component of the d-axis current, I d_0 cosω 1 t is the AC component of the d-axis current; I q_0 is the DC component of the q-axis current, Iq_0 cosω 1 t is the AC component of the q-axis current.

[0106] It should be noted that Formula 6 is only an example. In an embodiment, the d-axis current and the q-axis current may further include multiple AC components, which are not listed here one by one.

[0107] Torque T of the drive motor 2013 e ′ can be expressed as:

[0108] T e ′=1.5p*I q_0 *[M f I f +(L d -L q )I d_0 ] Formula 7

[0109] Therefore, according to Formula 7, the third preset condition can be expressed as:

[0110] I q_0 =0 Formula 8

[0111] According to Park transformation, the relationship between the DC component of the d-axis current and the DC component of the q-axis current and the current of the three-phase stator winding can be obtained as follows:

[0112]

[0113] Combining Formula 8 and Formula 9, the current relationship of the three-phase stator winding can still be obtained as shown in Formula 4.

[0114] At this time, the Joule heat generated by the current of the three-phase stator winding causing the drive motor 2013 can still be expressed by Formula 5. However, relative to the first control signal in step S602a controlling the output current of the inverter circuit 2011 to include only a DC component, the third control signal in the embodiment of the present application controls the output current of the inverter circuit 2011 to include both a DC component and an AC component, that is, the embodiment of the present application injects harmonics into the current of the three-phase stator winding, which can increase the copper loss and iron loss of the three-phase stator winding, thereby further increasing the heat generation of the drive motor.

[0115] In general, the current of the three-phase stator winding satisfies the third preset condition. Similarly, there are multiple current combinations that satisfy the third preset condition. In the embodiment of the present application, a current combination that can increase the heat generation of the three-phase stator winding can be selected from the current combinations that satisfy the third preset condition, and harmonics can be injected into the current combination.

[0116] In one embodiment, the first control signal and the third control signal are PWM signals, and the duty cycle of the third control signal is greater than the duty cycle of the first control signal. That is, the controller 2014 injects harmonics into the current of the three-phase stator winding by increasing the duty cycle of the control signal of the inverter circuit 2011.

[0117] In one embodiment, the controller 2014 monitors the temperature of the three-phase stator winding in real time through a first temperature sensor, and the first temperature sensor can be set on the surface of the three-phase stator winding. The controller 2014 compares the detected temperature of the three-phase stator winding with a preset stator temperature, and the preset stator temperature can be understood as the safe temperature of the three-phase stator winding, and the safe temperature of the three-phase stator winding can be the same. If the temperature of the three-phase stator winding is greater than the preset stator temperature, the controller 2014 selects a current combination that makes the heat generation of the drive motor smaller from multiple current combinations that satisfy Formula 4. Exemplarily, the controller 2014 reduces the output current of the inverter circuit 2011 by reducing the duty cycle of the first control signal so that the temperature of the three-phase stator winding is within the safe temperature range, and the torque of the drive motor is still zero. The implementation of the embodiment of the present application can avoid damage to the three-phase stator winding due to excessive temperature, and has good safety and high reliability.

[0118] In one embodiment, when the temperature of the three-phase stator winding is greater than the preset stator temperature, the controller 2014 controls the output current of the inverter circuit 2011 to switch from satisfying the third preset condition to satisfying the first preset condition. At this time, the controller 2014 controls the output current of the inverter circuit to switch from the mode of injecting harmonics to the mode of not injecting harmonics, which can reduce the copper loss and iron loss of the three-phase stator winding, avoid the three-phase stator winding from being damaged due to excessive temperature, and has good safety and high reliability.

[0119] In one embodiment, after the controller 2014 determines the output current of the inverter circuit 2011, that is, after determining the current of the three-phase stator winding, the controller 2014 can determine the voltage amplitude and voltage phase of the three-phase stator winding respectively based on the current of the three-phase stator winding based on Ohm's law. Thus, the controller can determine the duty cycle of the control signal of the inverter circuit 2011 according to the voltage amplitude of the three-phase stator winding, and determine the sending time of the control signal of the inverter circuit 2011 according to the voltage phase of the three-phase stator winding.

[0120] In one embodiment, the controller 2014 may execute Fig. 9 The flow chart shown in FIG. 1 controls the output current of the inverter circuit 2011 and the DC conversion circuit 2012. Fig. 9 As shown, the execution steps of the controller include:

[0121] In step S900 , the controller 2014 detects whether the temperature of the power battery 202 is lower than a preset battery temperature. If so, the controller 2014 executes step S901b , otherwise, the controller 2014 executes step S901a to start the drive motor 2013 normally.

[0122] It is understandable that the relationship between the temperature of the power battery 202 detected by the controller 2014 and the preset battery temperature can be referred to the description of step S600 above, which is not repeated here.

[0123] Step S901a: In response to the temperature of the power battery 202 being greater than or equal to the preset battery temperature, the controller 2014 normally starts the drive motor 2013. At this time, the controller 2014 can control the output current of the inverter circuit 2011 and the DC conversion circuit 2012 so that the drive motor 2013 outputs torque to drive the wheels of the electric vehicle.

[0124] Step S901b, the controller 2014 responds to the temperature of the power battery 202 being lower than the preset battery temperature, and adjusts the output current of the inverter circuit 2011 and the DC conversion circuit 2012 according to the comparison result between the voltage of the power battery 202 and the preset battery voltage. At this time, the controller 2014 controls the output current of the inverter circuit 2011 and the DC conversion circuit 2012 to increase the heat generation of the three-phase stator winding of the drive motor 2013. It can be seen that, compared with the previous step S601b, at this time, the controller 2014 adds the control of the output current of the DC conversion circuit 2012, that is, adds the control of the current flowing into the rotor winding.

[0125] The controller 2014 can control the output current of the inverter circuit 2011 and the DC conversion circuit 2012 by outputting control signals to the inverter circuit 2011 and the DC conversion circuit 2012. It should be explained that the control signal output by the controller 2014 to the inverter circuit 2011 is different from the control signal output to the DC conversion circuit 2012, and the second control signal and the fourth control signal involved in the present application include an inverter sub-control signal corresponding to the inverter circuit 2011, and also include a transformer sub-control signal corresponding to the DC conversion circuit 2012.

[0126] For example, when the temperature of the power battery 202 is lower than a preset battery temperature, the controller 2014 may output an inverter sub-control signal of a second control signal to the inverter circuit 2011 and a transformer sub-control signal of a second control signal to the DC conversion circuit 2012 to control the output current of the inverter circuit 2011 and the DC conversion circuit 2012, thereby making the output torque of the drive motor 2013 zero.

[0127] For another example, when the temperature of the power battery 202 is lower than the preset battery temperature, the controller 2014 can control the output current of the inverter circuit 2011 to be the first current, that is, the current flowing into the three-phase stator winding is the first current, and the controller 2014 controls the output current of the DC conversion circuit 2012 to be the second current, that is, the current flowing into the rotor winding is the second current. The first current and the second current meet the second preset condition, which is that the torque of the drive motor 2013 is zero, and the first current and the second current are in a preset proportional relationship.

[0128] In the embodiment of the present application, the Park transformation can still be used to analyze the current of the three-phase stator winding, that is, Formula 1 still holds true.

[0129] According to formula 2, the second preset condition can be expressed as:

[0130] I d =M f I f / (L q -L d ) Formula 10

[0131] Combining Formula 1 and Formula 10, we can get the relationship between the current of the three-phase stator winding and the current of the rotor winding:

[0132]

[0133] The controller 2014 controls the output current of the inverter circuit 2011 and the output current of the DC conversion circuit 2012 to meet the second preset condition, that is, the current of the three-phase stator winding and the current of the rotor winding of the drive motor 2013 meet formula 11. It can be understood that the current of the three-phase stator winding and the current of the rotor winding meet formula 11 and can also have multiple current combinations.

[0134] At this time, the current of the rotor winding Ls is not zero, and the Joule heat generated by the drive motor 2013 can be expressed by the formula:

[0135] Q′=I d 2 ×R s +I q 2 ×R s +I f 2 ×R f Formula 12

[0136] Among the multiple current combinations that satisfy Formula 11, there is a current combination that can minimize the heat generated by the drive motor 2013, that is, the Q' value in Formula 12 is the smallest. Similarly, the embodiment of the present application abandons the current combination that minimizes the heat generated by the drive motor 2013, and selects other current combinations except the current combination with the minimum heat generated, thereby increasing the heat generated by the drive motor. Further, a current combination that maximizes the heat generated by the drive motor 2013 can be selected.

[0137] For example, the current combination C and the current combination D are included in the multiple current combinations satisfying Formula 11, where the current combination C specifically includes I U =2,I V =1,I W =2; the current combination D specifically includes I U =4,I V =2,I W =3, assuming that the current combination C is substituted into Formula 1 and Formula 11 to calculate I d =1A, I q =0.5A and I f =0.5A, substitute the current combination D into Formula 1 and Formula 11 to calculate I d =2A, I q =0.5A and I f =1A. Then we know that the heat generated by the drive motor calculated by substituting the current combination C into formula 12 is greater than the heat generated by the drive motor calculated by substituting the current combination D into formula 12. Then the output current of the inverter circuit controlled by the controller and the output current of the DC conversion circuit are combination C.

[0138] In general, in the implementation of the embodiment of the present application, a current combination that can increase the heat generation of the three-phase stator winding and the heat generation of the rotor winding can be selected from the current combinations that meet the second preset condition. Therefore, in the implementation of the embodiment of the present application, compared with the above-mentioned combination Figure 6 In addition to increasing the heat generation of the three-phase stator winding in the described embodiment, the embodiment of the present application can further increase the heat generation of the rotor winding, thereby further increasing the heat generation of the drive motor.

[0139] In one embodiment, the controller 2014 may also execute Fig.10 The flow chart shown in FIG. 1 is used to adjust the output current of the inverter circuit 2011 and the DC conversion circuit 2012. Fig.10 As shown, the execution steps of the controller include:

[0140] Step S901b1: The controller 2014 detects whether the voltage of the power battery 202 is greater than the preset battery voltage. If so, execute step S902b; otherwise, execute step S902a.

[0141] The preset battery voltage represents the voltage required for the power battery 202 to inject harmonics into the output current of the inverter circuit 2011 and the output current of the DC conversion circuit 2012. It can be understood that the judgment of the voltage of the power battery is added in step S901b1, and the execution of steps S902a and S902b can be switched, so as to improve the power battery's power utilization efficiency and reduce power waste.

[0142] In one embodiment, in response to the voltage of the power battery 202 being less than or equal to the preset battery voltage, the controller 2014 executes step S902a, and the controller 2014 outputs a second control signal to control the output current of the inverter circuit 2011 and the DC conversion circuit 2012, that is, the controller 2014 outputs an inverter sub-control signal of the second control signal to the inverter circuit 2011 and a transformer sub-control signal of the second control signal to the DC conversion circuit 2012. At this time, the inverter sub-control signal of the second control signal can control the output current of the inverter circuit 2011 to be the first current, and the transformer sub-control signal of the second control signal can control the output current of the DC conversion circuit 2012 to be the second current, wherein the first current and the second current meet the second preset condition.

[0143] In one embodiment, in response to the voltage of the power battery 202 being greater than the preset battery voltage, the controller 2014 executes step S902b, and the controller 2014 outputs a fourth control signal to control the output current of the inverter circuit 2011 and the DC conversion circuit 2012, that is, the controller 2014 outputs an inverter sub-control signal of the fourth control signal to the inverter circuit 2011 and a transformer sub-control signal of the fourth control signal to the DC conversion circuit 2012. At this time, the inverter sub-control signal of the fourth control signal can control the output current of the inverter circuit 2011 to be a third current, and the transformer sub-control signal of the fourth control signal can control the output current of the DC conversion circuit 2012 to be a fourth current, wherein the third current and the fourth current meet a fourth preset condition. The fourth condition is that the torque of the drive motor 2013 is zero, at this time, the q-axis current of the three-phase stator winding includes a DC component and at least one AC component, the current of the rotor winding includes a DC component and at least one AC component, and the DC component of the q-axis current of the three-phase stator winding is in a preset proportional relationship with the DC component of the rotor winding.

[0144] In a specific implementation, the current of the three-phase stator winding and the current of the rotor winding both include a DC component and at least one AC component, that is, harmonics are injected into the current of the three-phase stator winding and the current of the rotor winding. Then, the current of the three-phase stator winding and the current of the rotor winding can be specifically expressed as:

[0145]

[0146] Among them, I f_0 is the DC component of the rotor winding, I f_0 cosω 2 t is the AC component of the rotor winding.

[0147] It should be noted that Formula 13 is only an example. In an embodiment, the d-axis current, the q-axis current and the current of the rotor winding may also include multiple AC components, which are not listed here one by one.

[0148] Torque T of the drive motor 2013 e ″ can be expressed as:

[0149] T e ″=1.5p*I q_0 *[M f I f_0 +(L d -L q )I d_0 ] Formula 14

[0150] Therefore, according to formula 14, the fourth preset condition can be expressed as:

[0151] I d_0 =M f I f_0 / (L q -L d ) Formula 15

[0152] According to Park transformation, the relationship between the DC component of the d-axis current and the DC component of the q-axis current and the current of the three-phase stator winding is shown in Formula 9.

[0153] Combining Formula 9 and Formula 15, the current relationship of the three-phase stator winding can be obtained as follows:

[0154]

[0155] At this time, the Joule heat generated by the current of the three-phase stator winding to the drive motor 2013 can still be expressed by Formula 12, but relative to the second control signal in step S902a controlling the output current of the inverter circuit 2011 and the DC conversion circuit 2012 to include only the DC component, the fourth control signal in the embodiment of the present application controls the output current of the inverter circuit 2011 and the DC conversion circuit 2012 to include both the DC component and the AC component, that is, the embodiment of the present application injects harmonics into the current of the three-phase stator winding and injects harmonics into the current of the rotor winding. By implementing the embodiment of the present application, the copper loss and iron loss of the three-phase stator winding and the rotor winding can be increased, thereby further increasing the heat generation of the drive motor.

[0156] In general, the current of the three-phase stator winding and the current of the rotor winding meet the fourth preset condition. Similarly, there are multiple current combinations that meet the fourth preset condition. In the embodiment of the present application, a current combination that can increase the heat generation of the three-phase stator winding and the heat generation of the rotor winding can be selected from the current combinations that meet the fourth preset condition, and harmonics can be injected into the current combinations respectively.

[0157] In one embodiment, the second control signal and the fourth control signal are PWM signals, and the duty cycle of the fourth control signal is greater than the duty cycle of the second control signal, that is, the controller 2014 injects harmonics into the current of the three-phase stator winding by increasing the duty cycle of the inverter sub-control signal of the inverter circuit 2011, and injects harmonics into the current of the rotor winding by increasing the duty cycle of the transformer sub-control signal of the DC conversion circuit 2012.

[0158] In one embodiment, the controller 2014 reduces the output current of the inverter circuit 2011 and the output current of the DC conversion circuit 2012 when the temperature of the three-phase stator winding is greater than a preset stator temperature or the temperature of the rotor winding is greater than a preset rotor temperature.

[0159] In a specific implementation, the controller 2014 monitors the temperature of the three-phase stator winding in real time through a first temperature sensor, and the first temperature sensor can be set on the surface of the three-phase stator winding. The controller 2014 compares the detected temperature of the three-phase stator winding with a preset stator temperature, which can be understood as a safe temperature of the three-phase stator winding. If the temperature of the three-phase stator winding is greater than the preset stator temperature, the controller 2014 selects a current combination that makes the heat generation of the drive motor smaller from multiple current combinations that satisfy formula 15. Exemplarily, the controller 2014 reduces the output current of the inverter circuit 2011 by reducing the duty cycle of the inverter sub-control signal of the second control signal, so that the temperature of the three-phase stator winding is within the safe temperature range, and in order to ensure that the output current of the inverter circuit 2011 and the output current of the DC conversion circuit 2012 meet the second preset condition, the controller 2014 also reduces the output current of the DC conversion circuit 2012 by reducing the duty cycle of the transformer sub-control signal of the second control signal. At this time, the torque of the drive motor is still zero.

[0160] Similarly, the controller 2014 monitors the temperature of the rotor winding in real time through the second temperature sensor, and the second temperature sensor can be arranged on the surface of the rotor winding. The controller 2014 compares the detected temperature of the rotor winding with the preset rotor temperature, and the preset rotor temperature can be understood as the safe temperature of the rotor winding. The preset rotor temperature and the preset sub-temperature can be the same temperature. If the temperature of the rotor winding is greater than the preset rotor temperature, the controller 2014 selects a current combination that makes the heat generation of the drive motor smaller from the multiple current combinations that satisfy formula 15. Exemplarily, the controller 2014 reduces the output current of the DC conversion circuit 2012 by reducing the duty cycle of the transformer control signal of the second control signal. And in order to ensure that the output current of the inverter circuit 2011 and the output current of the DC conversion circuit 2012 meet the second preset condition, the controller 2014 reduces the output current of the inverter circuit 2011 by reducing the duty cycle of the inverter control signal of the second control signal. At this time, the torque of the drive motor is still zero.

[0161] By implementing the embodiments of the present application, it is possible to avoid damage to the three-phase stator winding and the rotor winding due to excessive temperatures, thereby achieving good safety and high reliability.

[0162] In one embodiment, when the temperature of the three-phase stator winding is greater than the preset stator temperature or the temperature of the rotor winding is greater than the preset rotor temperature, the controller 2014 controls the output current of the inverter circuit 2011 and the DC conversion circuit 2012 to switch from satisfying the fourth preset condition to satisfying the second preset condition. At this time, the controller 2014 controls the output current of the inverter circuit 2011 and the DC conversion circuit 2012 to switch from a mode of injecting harmonics to a mode of not injecting harmonics, which can reduce the copper loss and iron loss of the three-phase stator winding, thereby reducing the heat generated by the drive motor.

[0163] In one embodiment, the frequency of the AC component of the third current is different from that of the AC component of the fourth current, that is, the frequency of the AC component of the current of the three-phase stator winding is different from that of the AC component of the current of the rotor winding. That is, in formula 13, ω 1 The value of 2 By implementing the embodiment of the present application, it is possible to avoid the mutual coupling between the AC component in the current of the three-phase stator winding and the AC component in the current of the rotor winding, thereby preventing the drive motor from generating torque.

[0164] In one embodiment, after the controller 2014 determines the output current of the DC conversion circuit 2012, that is, after determining the current of the rotor winding, the controller 2014 can determine the voltage amplitude of the rotor winding from the current of the rotor winding based on Ohm's law, and determine the duty cycle of the control signal of the DC conversion circuit 2012 according to the voltage amplitude of the rotor winding.

[0165] It is understandable that the above Figures 6 to 10 This article introduces how the drive motor generates heat. Fig.11 The heat generated by the drive motor to heat the power battery 202 is exemplified. Fig.11 As shown, the execution steps include:

[0166] S1101 , the pump device 203 drives the motor coolant to enter the three-phase stator winding and the rotor winding.

[0167] The flow of the motor coolant in the cooling circuit is driven by the pump device 203. In one embodiment, the controller 2014 can also control the working state of the pump device 203, for example, it can control the output power, opening or closing of the pump device 203. It is understandable that the pump device 203 can also be controlled by other controllers such as the vehicle controller at the same time. Exemplarily, when the controller 2014 detects that the temperature of the power battery 202 is lower than the preset battery temperature, the controller 2014 turns on the pump device 203.

[0168] S1102: In the cooling circuit, the motor coolant heats the battery coolant.

[0169] It is understandable that the present application refers to the liquid flowing into the drive motor as the motor coolant, and the liquid flowing into the cooling channel of the power battery as the battery coolant. In fact, both the motor coolant and the battery coolant are cooling media flowing in the cooling circuit, which can be specifically implemented as oil cooling. At this time, the motor coolant flowing into the three-phase stator winding and the rotor winding returns to the cooling circuit and conducts heat transfer with the battery coolant, that is, the heat generated by the three-phase stator winding and the rotor winding is transferred to the battery coolant.

[0170] S1103 : The pump device 203 drives the battery coolant to enter the cooling channel of the power battery 202 to heat the power battery 202 .

[0171] It is understandable that a cooling channel is provided around the power battery 202 , and the battery coolant does not directly contact the power battery.

[0172] S1104 , the controller 2014 detects whether the temperature of the power battery 202 is lower than a preset battery temperature.

[0173] When the controller 2014 detects that the temperature of the power battery 202 is lower than the preset battery temperature, the controller 2014 executes the above-described steps S601b and S901b.

[0174] S1105. Start the drive motor normally.

[0175] It should be explained that the controller 2014 normally starts the drive motor by executing the existing drive motor control method, that is, the torque of the drive motor is not zero, the torque is as large as possible; and the heat generated by the drive motor 2013 is as small as possible.

[0176] It should be noted that the above terms “first” and “second” are only used for descriptive purposes and should not be understood as indicating or implying relative importance.

[0177] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art can easily think of changes or substitutions within the technical scope disclosed by the present invention, which should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A controller for driving a motor, It is characterized in that The drive motor performs heat exchange with the power battery through a cooling circuit, the drive motor includes a three-phase stator winding, the power battery supplies power to the three-phase stator winding via an inverter circuit, and the controller is used for: In response to the temperature of the power battery being greater than or equal to a preset battery temperature, controlling the output current of the inverter circuit so that the drive motor outputs torque to drive the wheels; In response to the temperature of the power battery being lower than the preset battery temperature, and according to the comparison result between the voltage of the power battery and the preset battery voltage, the output current of the inverter circuit is adjusted, and the output current of the inverter circuit is controlled so that the heat generated by the three-phase stator winding of the drive motor is increased; The preset battery voltage represents the voltage required for the power battery to inject harmonics into the output current of the inverter circuit, and the controller is used to: In response to the voltage of the power battery being less than or equal to the preset battery voltage, outputting a first control signal to control the output current of the inverter circuit to meet a first preset condition, wherein the first preset condition is that the output torque of the drive motor is zero and the DC component and the AC component of the quadrature-axis current of the three-phase stator winding are both zero; In response to the voltage of the power battery being greater than the preset battery voltage, a third control signal is output to control the output current of the inverter circuit to meet a third preset condition, wherein the third preset condition is that the output torque of the drive motor is zero and the DC component of the quadrature-axis current of the three-phase stator winding is zero and the AC component is not zero.

2. The controller according to claim 1, It is characterized in that The drive motor further includes a rotor winding, the power battery supplies power to the rotor winding via a DC conversion circuit, and the controller is used for: In response to the temperature of the power battery being lower than the preset battery temperature, a second control signal is output to control the output current of the inverter circuit and the DC conversion circuit so that the output torque of the drive motor is zero.

3. The controller according to claim 1, It is characterized in that The drive motor further includes a rotor winding, the power battery supplies power to the rotor winding via a DC conversion circuit, and the controller is used for: In response to the temperature of the power battery being lower than the preset battery temperature, the output current of the inverter circuit and the output current of the DC conversion circuit are controlled to meet a second preset condition.

4. The controller according to any one of claims 2 to 3, It is characterized in that The controller is used to: In response to the voltage of the power battery being less than or equal to the preset battery voltage, outputting a second control signal to control the output current of the inverter circuit and the DC conversion circuit; In response to the voltage of the power battery being greater than the preset battery voltage, a fourth control signal is output to control the output current of the inverter circuit and the DC conversion circuit.

5. The controller according to claim 4, It is characterized in that The controller is used to: In response to the voltage of the power battery being less than or equal to the preset battery voltage, controlling the output current of the inverter circuit and the output current of the DC conversion circuit to meet a second preset condition; In response to the voltage of the power battery being greater than the preset battery voltage, the output current of the inverter circuit and the output current of the DC conversion circuit are controlled to meet a fourth preset condition.

6. The controller according to claim 5, It is characterized in that The controller is also used for: In response to the temperature of the three-phase stator winding being greater than a preset stator temperature or the temperature of the rotor winding being greater than a preset rotor temperature, the output current of the inverter circuit is controlled to switch from satisfying a third preset condition to satisfying a first preset condition, or from a fourth preset condition to satisfying a second preset condition.

7. A motor control unit, It is characterized in that The motor control unit includes a controller and an inverter circuit, wherein the controller is used to control the output current of the inverter circuit, the output end of the inverter circuit is connected to the three-phase stator winding of the drive motor, and the input end of the inverter circuit is connected to the power battery; In response to the temperature of the power battery being greater than or equal to a preset battery temperature, the inverter circuit outputs a current that satisfies a fifth preset condition so that the drive motor outputs torque to drive the wheels; In response to the temperature of the power battery being lower than the preset battery temperature, the inverter circuit outputs a current satisfying a sixth preset condition so that the heat generated by the three-phase stator winding of the drive motor increases, and adjusts the output current according to a comparison result between the voltage of the power battery and the preset battery voltage so as to change the heat generated by the three-phase stator winding of the drive motor; Among them, the preset battery voltage represents the voltage required for the power battery to inject harmonics into the output current of the inverter circuit. In response to the voltage of the power battery being greater than the preset battery voltage, the inverter circuit outputs a current that satisfies a third preset condition. When the inverter circuit outputs a current that satisfies the third preset condition, the output torque of the drive motor is zero and the DC component of the quadrature-axis current of the three-phase stator winding is zero, and the AC component is not zero.

8. The motor control unit according to claim 7, It is characterized in that In response to the temperature of the power battery being lower than the preset battery temperature, the inverter circuit outputs a current satisfying the sixth preset condition so that the output torque of the drive motor is zero.

9. The motor control unit according to claim 8, It is characterized in that The motor control unit further comprises a DC conversion circuit, the output end of the DC conversion circuit is connected to the rotor winding of the drive motor, and the input end of the DC conversion circuit is connected to the power battery; The sixth preset condition includes the first preset condition, the second preset condition and the fourth preset condition; When the inverter circuit outputs a current that satisfies the first preset condition, the DC component and the AC component of the quadrature-axis current of the three-phase stator winding are zero; When the inverter circuit and the DC conversion circuit output currents that satisfy the third preset condition or the fourth preset condition, the AC component of the quadrature-axis current of the three-phase stator winding is not zero; When the inverter circuit and the DC conversion circuit output currents that meet the second preset condition or the fourth preset condition, the direct-axis current of the three-phase stator winding and the current of the rotor winding are in a preset proportional relationship.

10. The motor control unit according to claim 9, It is characterized in that In response to the temperature of the power battery being lower than the preset battery temperature, the inverter circuit outputs a current that satisfies the first preset condition.

11. The motor control unit according to claim 9, It is characterized in that In response to the voltage of the power battery being less than or equal to the preset battery voltage, the inverter circuit outputs a current that meets the first preset condition.

12. The motor control unit according to claim 9, It is characterized in that In response to the temperature of the power battery being lower than the preset battery temperature, the DC conversion circuit and the inverter circuit output a current that satisfies the second preset condition so that the output torque of the drive motor is zero.

13. The motor control unit according to claim 9, It is characterized in that In response to the voltage of the power battery being less than or equal to the preset battery voltage, the inverter circuit and the DC conversion circuit output a current that meets the second preset condition; In response to the voltage of the power battery being greater than the preset battery voltage, the inverter circuit and the DC conversion circuit output a current that meets the fourth preset condition.

14. The motor control unit according to claim 9, It is characterized in that When the inverter circuit and the DC conversion circuit output currents satisfying the fourth preset condition, the frequencies of the AC component of the direct-axis current of the three-phase stator winding and the AC component of the current of the rotor winding are different.

15. An electric drive system, It is characterized in that The electric drive system includes an inverter circuit, a DC conversion circuit, a drive motor and a controller as described in any one of claims 1-6.

16. An electric car, It is characterized in that The electric vehicle comprises a power battery and the electric drive system as claimed in claim 15; wherein the power battery is used to provide power to the electric drive system.

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