CN117227509A - Motor controller, power assembly and method for balancing multiphase heating power - Google Patents

Abstract

A motor controller, power assembly and method for balancing multi-phase heating power relate to the field of new energy vehicles and can be applied to pure electric vehicles and hybrid vehicles. The motor controller includes: the motor controller is used to output drive current to the drive motor of the electric vehicle and output multiple heating currents. The drive current is used to control the torque output by the drive motor to be greater than zero. Each heating current is used to control the torque output by the drive motor. is zero, each heating current includes three-phase currents, where: the parameters of any two heating currents are different, and the parameters include the ratio of the effective values of each phase current in the three-phase currents of each heating current. According to the solution of this application, the multi-phase heating power of the motor can be balanced and the battery heating efficiency can be improved.

Description

A motor controller, powertrain and method for balancing multi-phase heating power

Technical field

The present application relates to the field of electric vehicles, and more particularly, to a motor controller, powertrain and method for equalizing multi-phase power.

Background technique

Driven by both market demand and policy guidance, the electric vehicle industry is entering a stage of rapid development. With the vigorous popularization and application of electric vehicles, the problem of attenuation of vehicle power and endurance at low temperatures has gradually attracted people's attention. Compared with normal temperature environments, the discharge rate of batteries in low-temperature environments drops sharply, resulting in insufficient vehicle power. At the same time, when charging batteries at low temperatures, lithium ions are prone to negative electrode deposition and generate lithium dendrites, causing an irreversible decrease in battery capacity and shortening battery life. mileage; and, over time, the growing lithium dendrites may pierce the separator between the positive and negative electrodes of the battery, forming an internal short circuit and causing safety hazards. Current battery heating solutions use resistance heating devices such as positive temperature coefficient (PTC) thermistors to heat power batteries, which have disadvantages such as high cost and large installation space. There are also plans to use the motor's self-heating to heat the power battery and replace some or all of the original PTC components to improve system integration and reduce costs. However, in this heating scheme, there are problems of uneven multi-phase power of the motor and uneven heating. When the current load of a certain phase reaches the maximum, it is easy to cause the single-phase high voltage stress to exceed the limit and the single-phase temperature to rise too fast, which in turn causes the temperature sensor close to the single-phase winding to quickly overheat, affecting the heating power of the motor and causing the heating rate of the power battery to be affected. Influence. At the same time, uneven heating of the three-phase windings will also cause the one phase with severe heating to have a shorter life. Long-term use will affect the symmetry and reliability of the motor.

Therefore, how to balance the multi-phase heating power of the motor during the battery heating process is an urgent problem to be solved.

Contents of the invention

This application provides a motor controller, control method and power assembly that balances multi-phase power. By allowing the motor to switch back and forth between different heating currents in a zero-torque state, it avoids a certain phase winding where the heating power is concentrated, thereby balancing the The multi-phase heating power of the motor improves the battery heating efficiency.

In a first aspect, this application provides a motor controller, which is used to output a driving current to a driving motor of an electric vehicle and to output a variety of heating currents. The driving current is used to control the torque output by the driving motor to be greater than zero. One heating current is used to control the output torque of the drive motor to be zero. Each heating current includes three-phase currents. The parameters of any two heating currents are different. The parameters include the effective value of each phase current in the three-phase currents of each heating current. value ratio.

In this application, the motor controller outputting multiple heating currents to the drive motor can be understood as outputting one type of heating current to the drive motor to run for a period of time, and then switching to another type of heating current to run with the other type of heating current for a period of time. By analogy, it is carried out under various heating currents in turn, and this working process is continuously cycled.

According to the solution of this application, by letting the motor run alternately between different heating currents in the zero-torque state, the stator coil loss of the motor generates heat in the stationary state, and conducts the heat to the power battery, thereby heating the battery. Different heating currents are used in The current distribution ratios in the three-phase stator windings are different, so the three-phase power ratios corresponding to different heating currents are different, avoiding a certain phase winding where the heating power is concentrated, balancing the multi-phase heating power of the motor, and improving the battery heating efficiency.

It should be understood that the purpose of setting multiple heating currents is to allow the motor to generate heat in a stationary state, so the goal of setting multiple heating currents is to make the torque of the motor zero. However, due to the implementation level of the device and the actual working state of the motor For other reasons, the motor may produce unstable and small torque under various heating currents. As long as the vehicle is kept stationary, the actual output torque can be a small value close to zero.

In connection with the first aspect, in some implementations of the first aspect, the motor controller is configured to first output the first heating current, and then output at least one of the second heating current, the third heating current and the fourth heating current, or , sequentially output at least one of the second heating current, the third heating current and the fourth heating current, and then output the first heating current; wherein, the quadrature axis current component of the first heating current and the quadrature axis current of the third heating current The component is not zero, and the quadrature-axis current component of the second heating current and the quadrature-axis current component of the fourth heating current are zero.

In connection with the first aspect, in some implementations of the first aspect, the direct axis current component of the first heating current, the direct axis current component of the second heating current, the direct axis current component of the third heating current and None of the direct-axis current components of the fourth heating current is zero.

Under the first heating current or the third heating current, the quadrature-axis current component corresponding to the stator winding of the drive motor is not zero, so the reluctance torque is not zero. The direct-axis current corresponds to the quadrature-axis current, so that the synchronous torque and reluctance The absolute value of the torque is equal and the sign is opposite, so the electromagnetic torque of the motor is zero. Under the second heating current or the fourth heating current, the quadrature axis current component corresponding to the stator winding of the drive motor is zero, and the direct axis current component is not zero, that is, the magnetic field direction generated by the current in the three-phase stator winding is the same as the magnetic field direction of the rotor. , so that the synchronous torque and reluctance torque of the drive motor are both zero.

In conjunction with the first aspect, in some implementations of the first aspect, during the process of the motor controller outputting the first heating current, the ratio of the quadrature-axis current component and the direct-axis current component of the first heating current is the working angle, when The working angle of the first heating current is less than 45 degrees, and the variance of the effective value of each phase current in the three-phase current of the first heating current decreases with the increase of the working angle of the first heating current; when the motor controller outputs the third heating During the current process, the arc tangent value of the ratio of the quadrature-axis current component and the direct-axis current component of the third heating current is the working angle. When the working angle is less than 45 degrees, the effective value of each phase current in the three-phase current of the third heating current is The variance of decreases with the increase of working angle.

In conjunction with the first aspect, in some implementations of the first aspect, during the process of the motor controller outputting the first heating current, when the working angle of the first heating current is greater than 45 degrees, one of the three-phase currents of the first heating current The effective values of each phase current are the same; during the process of the motor controller outputting the third heating current, when the working angle of the third heating current is greater than 45 degrees, the effective values of each phase current in the three-phase current of the third heating current are the same.

In connection with the first aspect, in some implementations of the first aspect, the effective value of each phase current in the three-phase current of each heating current changes with the change of the rotor angle of the driving motor.

In connection with the first aspect, in some implementations of the first aspect, the motor controller is configured to output the first heating current first, and then output at least one of the second heating current, the third heating current and the fourth heating current. , or in the process of the motor controller being used to output at least one of the second heating current, the third heating current and the fourth heating current in sequence, and then outputting the first heating current, the duration of the motor controller being used to output each heating current Changes with the change of the rotor angle of the drive motor.

It should be understood that the ratio of the working time corresponding to each heating current among the multiple heating currents is related to the rotor position angle of the motor. With different rotor position angles, the working time of the heating current will change accordingly.

In conjunction with the first aspect, in some implementations of the first aspect, in the process of the motor controller outputting multiple heating currents to the drive motor, the heating power of any one of the heating currents on any phase winding of the drive motor accounts for The ratio of any heating current to the total heating power on the three-phase winding of the drive motor is less than 2/3.

In conjunction with the first aspect, in some implementations of the first aspect, during a process in which the current output by the motor controller switches from one heating current to another heating current, the motor controller is used to control the torque output by the driving motor to always Less than the torque preset value.

It should be understood that in order to keep the motor stationary, during the process of switching between multiple heating currents, the current transformation should first decrease and then increase to the target heating current, thereby ensuring that the current output from the inverter circuit is driven The motor's torque value is always zero.

In connection with the first aspect, in some implementations of the first aspect, in the process of switching the current output by the motor controller from one heating current to another heating current, the current output by the motor controller first decreases and then increases. big.

In conjunction with the first aspect, in some implementations of the first aspect, in response to the temperature of the power battery being lower than a threshold and/or the heating instruction, the motor controller is configured to output multiple heating currents to the drive motor.

It should be understood that the motor controller can output a variety of heating currents to the drive motor when receiving an indication signal that the temperature of the power battery is lower than the threshold, or when receiving a heating command. For detecting the temperature of the power battery and sending The heating instruction may be executed by the vehicle controller 70 , and the motor controller may also perform heating of the power battery in response to other instructions, which is not limited in this application.

According to the solution of this application, the heating power of the multi-phase windings of the drive motor can be balanced and the battery heating efficiency can be improved.

In a second aspect, a power assembly is provided. The power assembly includes: a driving motor and a motor controller, the motor controller is used to output at least one heating current to the driving motor to control the torque of the driving motor to be zero, wherein: Neither the quadrature-axis current component nor the direct-axis current component of at least one heating current is zero.

The quadrature-axis current component and the direct-axis current component of the heating current output by the motor controller of the powertrain provided by this application are not zero, but the heating current can control the torque of the drive motor to be zero. Compared with the heating current with zero quadrature axis current, the heating power of this heating current on the three-phase winding of the drive motor is more uniform, which can avoid local temperature rise of the motor winding and improve the reliability and heating efficiency of the electric drive heating process.

The motor controller of the powertrain provided in the second aspect of this application is used to output a heating current with non-zero quadrature-axis current component and direct-axis current component to the drive motor to heat the windings of the drive motor. Combined with the second aspect, in the second In some implementations of aspects, in response to a temperature of the power battery being lower than a threshold and/or a heating command, the motor controller is configured to output at least one heating current.

The motor controller of the powertrain provided by this application is used to output heating current to heat the windings of the drive motor, and the current generated on the windings of the drive motor passes through the heat conduction device to heat the power battery. In one scenario, when the temperature of the power battery is too low, the motor controller outputs a heating current to heat the power battery. In another scenario, the driver actively issues a heating command, and in response to the heating command, the motor controller outputs a heating current to heat the power battery in response to the heating command.

In connection with the second aspect, in some implementations of the second aspect, in the process of the motor controller outputting at least one heating current, the arc tangent value of the ratio of the quadrature-axis current component and the direct-axis current component of each heating current is the working angle. When the working angle is less than 45 degrees, the variance of the effective value of each phase current in the three-phase heating current decreases as the working angle increases.

The uniformity of the three-phase effective value of the heating current output by the motor controller in the powertrain provided by this application will increase as the working angle increases. When the working angle is greater than 45 degrees, the three-phase current of the heating current is effective. The values are the same, so that the heating power of the heating current in the three-phase windings is the same, and the heating of the drive motor is more uniform, which is beneficial to providing heating performance.

In a third aspect, a motor control method is provided, which method includes: controlling the motor controller to output multiple heating currents to the drive motor in sequence, each heating current is used to control the torque output by the drive motor to be zero, and each heating current includes Three-phase current, wherein: in the first time period, the motor controller is controlled to output the first heating current; in the second time period after the first time period, the motor controller is controlled to output the second heating current, the third heating current and the third heating current. Any one of the four heating currents; in the third time period after the second time period, the motor controller is controlled to output any one of the first heating current, the second heating current, the third heating current and the fourth heating current; wherein , the quadrature-axis current component of the first heating current and the quadrature-axis current component of the third heating current are not zero, and the direct-axis current component of the second heating current and the direct-axis current component of the fourth heating current are zero.

Combined with the third aspect, in some implementations of the third aspect, in the process of switching the current output by the motor controller from one heating current to another heating current, the current output by the motor controller is controlled to first decrease and then increase, and control the motor controller so that the torque output by the drive motor is always less than the torque preset value.

In a fourth aspect, an electric vehicle is provided. The electric vehicle includes a vehicle controller, a power battery and a powertrain as in the second aspect and various possible implementations of the second aspect. The vehicle controller responds to the temperature of the power battery. Below the threshold and/or the heating requirement, a heating command is sent to the powertrain, which instructs the powertrain to heat the power battery; the heat conduction device is used to conduct the heat generated by the drive motor in the powertrain to the power battery.

For beneficial effects in other aspects, reference can be made to the beneficial effects described in the first aspect and will not be described again here.

Description of drawings

Figure 1 is a schematic diagram of an electric vehicle provided by an embodiment of the present application;

Figure 2 is a schematic diagram of the electric vehicle thermal management system provided by the embodiment of the present application;

Figure 3 is a schematic diagram of a motor controller provided by an embodiment of the present application;

Figure 4 is a schematic diagram of the zero-torque heating current of a permanent magnet synchronous motor provided by this application;

Figure 5 is a schematic diagram of the zero-torque heating current of an electric excitation synchronous motor provided by this application;

Figure 6 is a schematic diagram of three-phase current at different rotor angles provided by this application;

Figure 7 is a schematic diagram of three-phase power at different rotor angles provided by this application;

Figure 8 is a schematic diagram of a switching curve between heating currents provided by this application;

Figure 9 is a schematic flow chart of a motor control method provided by this application;

Figure 10 is a schematic diagram of a workflow provided by this application;

Figure 11 is a diagram of the relationship between three-phase power and rotor angle at different working angles provided by this application.

Detailed ways

The technical solutions in this application will be described below with reference to the accompanying drawings. The detailed description of the following embodiments and the accompanying drawings are used to illustrate the principles of the present application, but cannot be used to limit the scope of the present application, that is, the present application is not limited to the described embodiments.

With the vigorous popularization and application of electric vehicles, the problem of attenuation of vehicle power and endurance at low temperatures has gradually attracted people's attention.

Compared with normal temperature environments, the discharge rate of batteries in low-temperature environments drops sharply, resulting in insufficient vehicle power. At the same time, when charging batteries at low temperatures, lithium ions are prone to negative electrode deposition and generate lithium dendrites, causing an irreversible decrease in battery capacity and shortening battery life. mileage; and, over time, the growing lithium dendrites may pierce the separator between the positive and negative electrodes of the battery, forming an internal short circuit and causing safety hazards. Therefore, it is usually necessary to heat the battery to ensure the normal use of the battery.

In one possible implementation, an additional PTC heating device is added to the vehicle thermal management system, and its heat is transferred to the cooling medium of the thermal management system through the radiator, and then the battery pack is heated through thermal circulation to raise the temperature to The normal working range ensures normal charging and discharging capabilities.

However, the independent PTC heating device not only increases the material cost and is limited by the vehicle's internal space and installation method, but also incurs additional structural design costs, resulting in a higher cost of the battery heating solution.

In another possible implementation, the motor stator windings can be reused for heating. The voltage generated by the inverter circuit 52 is controlled to excite the motor to generate a specific current. This current acts on the stator winding to only generate current along the direction of the rotor magnetic field, thereby generating Joule heat. The heat then indirectly heats the battery pack through the circulation of the cooling system.

Although the above implementation method can save the cost of PTC, since the motor is stationary during heating, the three-phase currents of the motor are all DC, and the sizes of the three are related to the current rotor position. If the rotor stays in any position, the three-phase winding power will not be equal. , thus the heating power of each phase is seriously unbalanced. The inverter power device will also be affected by the imbalance of three-phase power. The conduction loss of the switching tube of the corresponding bridge arm when the maximum power of the winding is significantly higher than that of the other two-phase bridge arms. When designing the maximum heating power index, since it is necessary to consider the temperature rise of the maximum power phase including windings and power devices under extreme circumstances to leave more safety margins, the maximum heating power of the motor is limited and the battery temperature rise rate is slow. , affecting user travel experience.

Based on the above problems, this application provides a motor controller, a motor control method and a power assembly. By allowing the drive motor to alternately operate between different heating currents in the zero-torque state, the stator coil loss of the drive motor is generated in the stationary state. The heat is transferred to the power battery to heat the battery. Different heating currents have different current distribution ratios in the three-phase stator windings, so the three-phase power ratios corresponding to different heating currents are different, avoiding a certain phase where the heating power is concentrated. The winding balances the multi-phase heating power of the motor and improves the battery heating efficiency.

In the description of this application, it should be noted that, unless otherwise clearly stated and limited, the terms "set", "installation", "connected" and "connected" should be understood in a broad sense. For example, it can be a fixed connection or a fixed connection. It can be detachably connected or integrally connected; it can be directly connected or indirectly connected through an intermediate medium. For those of ordinary skill in the art, the specific meanings of the above terms in this application may be understood based on specific circumstances. The term "comprising" used in this application should not be construed as limited to what is listed thereafter; it does not exclude other elements or steps. It should therefore be construed as specifying the presence of mentioned features, integers, steps or components but not excluding the presence or addition of one or more other features, integers, steps or components and groups thereof. Therefore, the expression "apparatus comprising means A and B" should not be limited to a plant consisting only of components A and B.

In order to facilitate understanding of the embodiments of the present application, first, the concepts and technologies involved in the embodiments of the present application are briefly introduced.

It should be understood that the relevant terms and explanations in the following are common to various embodiments throughout the text. Different embodiments can be used independently or in combination based on certain internal or external connections. Different implementations in the embodiments can be used independently or in combination.

1. Resolver

It can be called a resolver for short. It is a sensor installed on the shaft end of the motor rotor and is used to obtain the current position of the motor rotor.

2. Synchronous motor

A type of AC motor that generates a rotating magnetic field by passing a symmetrical current into the stator winding. The rotor is equipped with permanent magnets or excitation windings. The rotor magnetic field rotates synchronously with the stator rotating magnetic field due to the magnetic pull of the stator magnetic field, and generates torque externally. .

3. Electromagnetic torque

The torque output by the motor shaft of a synchronous motor is called electromagnetic torque, which is composed of synchronous torque and reluctance torque.

4. Synchronous torque

The torque generated by the interaction between the stator rotating magnetic field and the rotor rotating magnetic field is called synchronous torque.

5. Reluctance torque

The equivalent air gap thickness of the direct-axis magnetic circuit and the quadrature-axis magnetic circuit in the synchronous motor is inconsistent, resulting in unequal reluctance. Since the magnetic flux will always preferentially choose the path with the smallest reluctance, the inconsistent magnetic resistance between the direct axis and the quadrature axis will cause the magnetic flux to be biased in path selection, producing an additional torque, called reluctance torque.

6. Copper consumption

The heat generated by AC/DC current passing through the copper conductor in the winding, the heating power is calculated by I ² R, where I is the passing current (effective value of DC or AC quantity), and R is the conductor resistance.

7. Vector control

A control method suitable for motors with rotating magnetic fields. The three-phase stator current coefficient can be equivalent to an orthogonal two-phase system, and the motor rotor space vector can be decomposed into components on two rectangular coordinate axes: the magnetic field direction component and the rotor electromotive force direction component. , and control these two components independently, so that direct control of the motor's magnetic flux and electromotive force can be achieved, thereby achieving the purpose of accurately controlling the motor's torque and speed. Specifically, the mutual conversion of each physical quantity between the three-axis two-dimensional stator stationary coordinate system and the two-axis rotating coordinate system can be realized through Clark transformation and Park transformation. Taking the vector control method of a permanent magnet synchronous motor as an example, the direction of the rotor magnetic field is the direct axis (d-axis), and its leading 90° direction is the quadrature axis (q-axis), forming a rotating coordinate system. The three-phase current can be converted into currents on the d-axis and q-axis. The direction of the magnetic field formed by the current vector I _s synthesized by the given direct-axis current I _d and the quadrature-axis current I _q forms an angle with the direction of the rotor magnetic field, which is reasonable. The angle allows the magnetic fields to interact with each other to form the maximum torque, thereby causing the motor to output torque.

Figure 1 is a schematic diagram of an electric vehicle provided by an embodiment of the present application. As shown in FIG. 1 , the electric vehicle 10 includes a power battery 20 , a powertrain 30 and a vehicle controller 70 . The vehicle controller 70 may send instructions to the powertrain 30 to control vehicle operation or perform operations such as heating. The powertrain 30 is used to drive the electric vehicle 10 or to heat the power battery 20 . Powertrain 30 includes motor controller 50 and drive motor 60 . The motor controller 50 includes a control device 51 and an inverter circuit 52. The inverter circuit 52 may be a control circuit composed of an insulated gate bipolar transistor (IGBT). The on-off control signal of the IGBT in the control circuit is composed of the above-mentioned The control device 51 is provided. Taking the control of a three-phase motor as an example, six IGBTs are used to form an inverter control circuit to convert the DC current at the battery end into a three-phase AC current, which is provided to the three-phase windings (U, V, W) of the three-phase motor respectively. , to control the speed or torque output of the three-phase motor. Thermal transfer device 40 may be considered included in powertrain 30 . The heat generated by the driving motor 60 is conducted to the power battery 20 through the heat conduction device 40 to heat the power battery 20 . The motor controller 50 can generate a modulated voltage by turning on and off internal power devices, thereby stimulating the three-phase windings of the motor to generate heating current.

As shown in Figure 2, the embodiment provided by this application can be applied to the electric vehicle thermal management system architecture, in which the heat generated by the motor winding is brought into the fuel tank through the oil cooling pipeline, and the heat from the fuel tank is brought into the coolant circulation through the coolant Pipes and cooling pipes are connected to the power battery, so that the power battery can be heated by the heat generated by the driving motor.

This application is mainly used in electric vehicle power battery heating scenarios. Specifically, it can be any of different types of vehicles such as cars, trucks, and passenger buses, or it can also be a transport device for carrying people or goods such as a tricycle, a two-wheeler, or a train. , or other types of vehicles powered by power batteries. Electric vehicles include but are not limited to pure electric vehicle/battery electric vehicle (pure EV/battery EV), hybrid electric vehicle (HEV), range extended electric vehicle (REEV), plug-in Type hybrid electric vehicle (plug-in hybrid electric vehicle, PHEV), new energy vehicle (new energy vehicle, NEV), etc.

The drive motor 60 in the embodiment of the present application includes but is not limited to a three-phase or multi-phase, axial or radial permanent magnet synchronous motor, a three-phase or multi-phase, axial or radial permanent magnet auxiliary synchronous reluctance motor, and Three-phase or multi-phase, axial or radial electric excitation synchronous motor, etc. The structure of the drive motor 60 in the embodiment of the present application is the same as that of a common motor, and includes a rotor, a stator core, and a stator winding. When the driving motor 60 is a multi-phase winding motor, the number of motor phases may be 3 phases, 5 phases, 6 phases, 9 phases, etc. Commonly used cooling methods for this motor can be oil cooling, water cooling, or air cooling. For the sake of simplicity of description, a three-phase drive motor is taken as an example to illustrate the solution of the present application. For multi-phase situations, similar reference can be made to the description of a three-phase drive motor.

The power battery in the embodiment of the present application may be a lithium-ion battery, a lithium metal battery, a lead-acid battery, a nickel-cadmium battery, a nickel-hydrogen battery, a lithium-sulfur battery, a lithium-air battery, a sodium-ion battery, etc., which are not limited here. In terms of scale, the power battery in the embodiment of the present application can be a single cell, a battery module or a battery pack, which is not limited here. In terms of application scenarios, the power battery can be used in power devices such as cars and ships. For example, it can be applied to powered cars to power the motors of powered cars as a power source for electric cars. The power battery can also power other electrical devices in electric vehicles, such as in-car air conditioners and car players. For the convenience of description, the solution of this application will be described below by taking the application of power batteries in electric vehicles (or new energy vehicles) as an example.

The motor controller 50 in the embodiment of the present application includes an inverter circuit 52, which is composed of an insulated gate bipolar transistor IGBT. The motor control may also include a control device 51 , and the on-off control signal of the IGBT in the inverter circuit 52 may be provided by the control device 51 . Taking the control of a three-phase motor as an example, six IGBTs are used to form an inverter circuit 52 to pass the current in the power battery 20 into the motor and provide current to the three-phase windings of the three-phase motor respectively to control the three-phase motor. speed or torque output.

This application provides a motor controller 50.

As shown in FIG. 3 , the motor controller 50 includes an inverter circuit 52 . The inverter circuit 52 includes three-phase bridge arms connected in parallel. One end of each phase bridge arm is used to connect the positive electrode of the power battery 20 , and the other end of each phase bridge arm is used to connect the positive electrode of the power battery 20 . One end is used to connect the negative pole of the power battery 20 , and the midpoint of each phase bridge arm is used to connect one phase winding of the three-phase stator winding of the motor.

The motor controller 50 is used to output a driving current to the driving motor 60 of the electric vehicle 10 and to output multiple heating currents. The driving current is used to control the torque output by the driving motor 60 to be greater than zero, and each heating current is used to control the output of the driving motor 60 . The torque is zero, and each heating current includes three-phase currents, where: the parameters of any two heating currents are different, and the parameters include the ratio of the effective values of each phase current in the three-phase currents of each heating current.

In a possible implementation, the multiple heating currents include a first heating current, the quadrature-axis current component of the first heating current is not zero; the multiple heating currents also include a second heating current, a third heating current, and At least one of the fourth heating currents, the quadrature-axis current component of the third heating current is not zero, the third heating current is not equal to the first heating current, and the quadrature-axis current components of the second heating current and the fourth heating current are zero. , the second heating current and the fourth heating current are not equal.

In a possible implementation, the motor controller 50 is configured to output the first heating current first, and then output at least one of the second heating current, the third heating current, and the fourth heating current, or to output the third heating current first. At least one of the second heating current, the third heating current and the fourth heating current outputs the first heating current; wherein the quadrature axis current component of the first heating current and the quadrature axis current component of the third heating current are not zero, The quadrature-axis current component of the second heating current and the quadrature-axis current component of the fourth heating current are zero.

The direct-axis current component of the first heating current, the direct-axis current component of the second heating current, the direct-axis current component of the third heating current, and the direct-axis current component of the fourth heating current are all non-zero.

For example, the effective value ratio of each phase current in the three-phase current of the first heating current is: U phase: V phase: W phase = I _u1 : I _v1 : I _w1 ; each phase of the three-phase current of the second heating current The current effective value ratio is: U phase: V phase: W phase = I _u2 : I _v2 : I _w2 ; then I _u1 : I _v1 : I _w1 and I _u2 : I _v2 : I _w2 are different.

In a possible implementation, the motor controller 50 also includes a control device 51, and the control terminals of the six switch modules included in the three-phase bridge arm are respectively connected to the control device 51; the control device 51 is used to control the switching module. The inverter circuit 52 is turned off to alternately output various heating currents to the driving motor 60 .

It should be understood that the purpose of setting various heating currents is to allow the motor to generate heat in a stationary state, so the goal of setting various heating currents is to make the torque of the driving motor 60 zero. However, due to the implementation level of the device and the actual performance of the motor, Due to working conditions and other reasons, the drive motor 60 may produce unstable and small torque under various heating currents. As long as the vehicle can be kept stationary, the actual output torque can be a small value close to zero. In a preferred situation Down, can be zero.

The effective value of each phase current among the three-phase currents of each heating current changes as the rotor angle of the drive motor 60 changes. The electromagnetic torque generated by the motor under the first heating current or the third heating current is 0 and the reluctance torque generated is not 0. The third heating current is not equal to the first heating current. The first heating current or the third heating current The current can be determined based on the motor rotor rotation angle θ _e , the motor temperature and the current amplitude _Im .

The current amplitude I _m can be directly indicated by the heating command, or it can be calculated by the formula from the motor heating power P _m in the received heating command. Among them, R ₀ is the phase resistance of the motor stator winding, the current amplitude is the maximum current value in the three-phase stator winding of the motor, and the current amplitude is also the vector current value synthesized by the direct axis current I _d and the quadrature axis current I _q .

The temperature of the motor can be obtained through a temperature sensing device, which can measure the ambient temperature of the motor, or the temperature of the heat-carrying fluid of the motor thermal circuit, or the temperature of the motor stator winding, or the temperature in the heat conduction device, etc. This application is for This is not limited.

The rotor angle of the drive motor 60 can be detected by a sensor installed at the motor rotor shaft end, which is equal to the rotation angle measured by the sensor, and the rotation angle ranges from 0 to 360°.

The electromagnetic torque and reluctance torque generated by the drive motor 60 under the second heating current or the fourth heating current are both 0. The second heating current and the fourth heating current are not equal, and the electromagnetic torque of the drive motor 60 is 0. The direction of the magnetic field generated by the current in the three-phase stator winding is the same as that of the rotor, that is, the quadrature axis current is 0, and the reluctance torque is 0 at this time.

It is easy to understand that when current is passed through the windings of the driving motor 60 and the heat loss of the stator winding is used to heat the power battery 20, it is necessary to ensure that the motor does not generate torque during the heating process so that the vehicle can heat the battery 20 in a stationary state.

The torque of a three-phase synchronous motor can be described as:

T _e =1.5·n _p ·[ψ _f +(L _d -L _q )·i _d ]·i _q (1)

Among them: T _e is the motor torque, n _p is the number of pole pairs of the motor, ψ _f is the motor rotor flux linkage, L _d is the direct axis inductance (also called d-axis inductance), L _q is the quadrature axis inductance (also called q-axis Inductance), i _d is the direct axis current (also known as d-axis current), and i _q is the quadrature axis current (also known as q-axis current).

The electromagnetic torque in formula (1) includes two parts: synchronous torque T ₁ and reluctance torque T ₂ .

T _e =T ₁ +T ₂

Different types of synchronous motors have different sources of rotor flux, and the relationship between the motor's direct-axis inductance and quadrature-axis inductance is also different. For three-phase or multi-phase permanent magnet synchronous motors, the rotor flux linkage is generated by permanent magnets, and the permanent magnets are installed on the d-axis. Since the magnetic permeability of the permanent magnet is close to that of air, the d-axis equivalent air gap is thicker than the q-axis, so the magnetic permeability of the d-axis magnetic circuit is smaller, so the d-axis inductance is smaller than the q-axis inductance, that is, L _d <L _q ; For three-phase or multi-phase electrically excited synchronous motors, the rotor flux is generated by the field winding wound on the rotor. The equivalent air gap of the d-axis of the electrically excited synchronous motor is thinner than that of the q-axis, so the magnetic permeance of the d-axis magnetic circuit is larger, so the d-axis inductance is greater than the q-axis inductance, that is, L _d > L _q .

Taking the three-phase permanent magnet synchronous motor as an example, L _d <L _q , the permanent magnet synchronous motor has significant saturation nonlinear characteristics, so there is a specific combination of id _{and iq} such that the synchronous torque T ₁ and the reluctance torque T ₂ are equal in size and opposite in sign. At this time there are:

ψ _f =-(L _d -L _q )·i _d (3)

The combinations of _id and _iq that satisfy the relationship of equation (3) constitute several segmented curves, which can be called zero-torque curves.

Since synchronous motors have saturated nonlinear characteristics, the inductance will change with changes in current, and the relationship between i _d and i _q will change at different temperatures. Therefore, the motor temperature can be used to determine when the motor's electromagnetic torque is 0. The zero torque curve of the direct axis current and the quadrature axis current.

It should be understood that the zero torque curve will also be different for different drive motors 60. Therefore, the zero torque curve of the drive motor 60 can be determined by calibration or advance calculation, or can be obtained by calculation. This application does not Make limitations.

According to the above zero torque curve and current amplitude, the corresponding direct axis current and quadrature axis current can be determined. Combined with the rotation angle of the rotor of the drive motor 60, the current value that needs to be input into the three-phase stator winding can be determined.

The distribution diagram of the zero torque curve is shown in Figure 4 or Figure 5. The current amplitude is set to I _m . In order to ensure that the output torque is zero during the heating of the motor, the current vector can stay at four as shown in Figure 4 or Figure 5. a work point. Figure 4 shows a permanent magnet synchronous motor. Since the magnetic permeability of the permanent magnet is close to that of air, the d-axis equivalent air gap is thicker than the q-axis. Therefore, the magnetic permeance of the d-axis magnetic circuit is smaller, so the d-axis inductance is smaller than q. Shaft inductance, that is, L _d <L _q ; Figure 5 shows an electrically excited synchronous motor, and the rotor flux is generated by the field winding wrapped around the rotor. The equivalent air gap of the d-axis of the electrically excited synchronous motor is thinner than that of the q-axis, so the magnetic permeance of the d-axis magnetic circuit is larger, so the d-axis inductance is greater than the q-axis inductance, that is, L _d > L _q . Both Figures 4 and 5 include 4 working points. The difference is that working point 2 and working point 4 are located in different quadrants.

The following takes the case of the permanent magnet synchronous motor L _d < L _q in Figure 4 as an example. The description of the electric excitation synchronous motor in Figure 5 is similar and will not be described again.

For operating point 2, the current vector is located on the d-axis, i _d =I _m and i _q =0. At this time, the synchronous torque T ₁ and the reluctance torque T ₂ are both 0. When the drive motor 60 is parked at different angles When , the effective values of the three-phase currents U, V, and W are:

Among them, I _{u_rms} , I _{v_rms} , and I _{w_rms} are the three-phase current effective values of U, V, and W respectively, and θ _e is the rotor position angle, which can be obtained by measuring the resolver installed at the rotor shaft end of the drive motor 60. The effective values of the three-phase currents at different rotor angles are shown in Figure 6. It can be seen from Figure 6 and Table 1 that the effective values of each phase current are not equal at any angle, so the three-phase power is also not equal.

Table 1. Three-phase current effective value within the electrical angle range of 0 to 180°

For operating point 1, the current vector is located on the zero-torque curve of the first quadrant. At this time, i _d =I _m cosδ ₀ , i _q =I _m sinδ ₀ , where δ ₀ is the angle between the current vector and the d-axis δ ₀ = arctan(i _q /i _d ). At this time, the synchronous torque T ₁ is positive and the reluctance torque T ₂ is negative. Their absolute values are equal and their sum is zero, so the output torque is 0. When the rotor of the drive motor 60 is parked at different angles, the effective values of the U, V, and W three-phase currents are:

For operating point 3, the current vector is located on the zero torque curve of the fourth quadrant. At this time, _id =I _m cosδ ₀ , i _q =-I _m sinδ _0. At this time, the synchronous torque T ₁ is negative and the reluctance torque T ₂ is positive, their absolute values are equal, and their sum is zero, so the output torque is 0. When the rotor of the drive motor 60 is parked at different angles, the effective values of the U, V, and W three-phase currents are:

For operating point 4, the current vector is located on the d-axis, at this time _id =-I _m , i _q = 0, the synchronous torque T ₁ and the reluctance torque T ₂ are both 0. Obviously, at this time U, V, The effective value of W three-phase current is the same as that at operating point 2. See formula (4).

Among the above four working points, the total heating power of the three-phase windings of working point 1, working point 2, working point 3 and working point 4 is the same, but the current distribution ratio in the three-phase stator winding at each working point is different, that is The magnitude ratios of U-phase, V-phase, and W-phase currents at different operating points are different, so the heating power distributions of U-phase, V-phase, and W-phase are different; the currents of operating points 2 and 4 in the three-phase stator winding The effective values are the same, but the direction of the current is not exactly the same.

In a possible implementation, the heating current corresponding to the working point 1 may be the first heating current, the heating current corresponding to the working point 2 may be the second heating current, and the heating current corresponding to the working point 3 may be the third heating current. Heating current, the heating current corresponding to operating point 4 may be the fourth heating current.

In another possible implementation, the heating current corresponding to the working point 1 may be the third heating current, the heating current corresponding to the working point 2 may be the fourth heating current, and the heating current corresponding to the working point 3 may be the third heating current. A heating current, the heating current corresponding to the operating point 4 may be the second heating current.

When the driving motor 60 operates with a current corresponding to operating point 1 or operating point 3, the quadrature axis current of the driving motor 60 is not 0, so the reluctance torque is not 0 either. The direct axis current corresponds to the quadrature axis current, and the driving motor 60 The absolute values of the synchronous torque and the reluctance torque are equal, and their sum is 0, so the electromagnetic torque of the drive motor 60 is 0.

When the drive motor 60 operates with a current corresponding to operating point 2 or 4, the quadrature axis current of the drive motor 60 is 0, and the direct axis current is equal to the current amplitude, so the reluctance torque and synchronous torque are both 0, thus driving The electromagnetic torque of the motor 60 is 0.

As shown in Figure 7, when the drive motor 60 only operates with the second heating current or the fourth heating current, the relationship between the three-phase power and the current rotor dwell position is as shown in the figure. It can be seen that under different rotor positions, the three-phase total power Although it is always 1.5, the U, V, and W phase powers may be 0 or the maximum value of 1.

Therefore, in order to balance the three-phase heating power, the following possible combinations of heating currents can be used for motor control. The following method is only an example, and other possible combinations are also within the protection scope of this application.

method one

The various heating currents include three heating currents corresponding to working point 1, working point 2 and working point 3, so that the three-phase stator winding of the drive motor 60 can go back and forth between the currents corresponding to working point 1, working point 2 and working point 3. Alternate switching operation.

Method 2

The various heating currents include two heating currents corresponding to working point 1, working point 2 and working point 4, so that the three-phase stator winding of the drive motor 60 can go back and forth between the currents corresponding to working point 1, working point 2 and working point 4. Alternate switching operation.

Method three

The various heating currents include four heating currents corresponding to working point 1, working point 2, working point 3 and working point 4, so that the three-phase stator winding of the drive motor 60 can operate at working point 1, working point 2, working point 3 and working point. The current corresponding to point 4 switches back and forth alternately.

Method four

The various heating currents include two heating currents corresponding to working point 3 and working point 4, thereby allowing the three-phase stator winding of the drive motor 60 to alternately switch back and forth between working point 3 and the current corresponding to working point 3.

In the process of the motor controller 50 outputting multiple heating currents to the driving motor 60, the heating power of any heating current on any phase winding of the driving motor 60 accounts for the proportion of the heating power of any heating current on the three-phase windings of the driving motor 60. The ratio of the total heating power is less than 2/3.

In one possible implementation, in response to the temperature of the power battery 20 being lower than the threshold and/or the heating instruction, the motor controller 50 is configured to output multiple heating currents to the drive motor 60 so that the stator winding of the drive motor 60 generates heat. .

It should be understood that the motor controller 50 can perform the process of heating the battery 20 when the temperature of the battery 20 is low, and the inverter circuit 52 alternately outputs various heating currents to the three-phase stator windings of the driving motor 60 . This process may also be executed when a heating command is received.

Exemplarily, the heating instruction can be, for example, through a heating button. The user presses the heating button, and the motor controller 50 can execute the process immediately after receiving the heating instruction; the motor controller 50 can also detect after receiving the heating instruction. Whether the temperature of the power battery 20 is lower than the threshold, if it is lower than the threshold, this process is executed.

In a possible implementation, during the process in which the motor controller 50 is used to output the first heating current first, and then output at least one of the second heating current, the third heating current and the fourth heating current, or when the motor The controller 50 is used to output at least one of the second heating current, the third heating current and the fourth heating current in sequence, and then outputs the first heating current. During the process, the motor controller 50 is used to output the duration of each heating current. The angle of the rotor of the drive motor 60 changes.

When the rotor position angle of the driving motor 60 is different, the inverter circuit 52 outputs a different duration ratio of each of the multiple heating currents.

After each heating current runs for a certain period of time, it can be switched to another heating current and run for another period of time. When the motor controller 50 outputs one of the multiple heating currents and switches to another of the multiple heating currents, each heating current can be determined based on the rotor rotation angle θ _e of the drive motor 60 and the size of the heating current. corresponding running time.

Taking the three working points of working point 1, working point 2, and working point 3 in the above method 1 as an example, the heating current corresponding to each working point is not equal. Within a fixed time period, reasonable allocation of the operating time proportions of the three operating points can make the total heat generation of the three-phase windings in the time period basically the same. Therefore, the balance of the average power of each of the three-phase windings (the ratio of the total heat generated by each winding in the time period to the total duration of the time period) is improved.

In a possible implementation, the working time corresponding to each heating current may be preset or controlled by control instructions. For example, each heating current can be run for 10 seconds and then switched to another heating current for another 10 seconds, and then run alternately.

In another possible implementation, the running time corresponding to each heating current can be determined based on the rotation angle θ _e of the rotor of the drive motor 60 and the size of the heating current.

For example, the power values under different heating currents can be determined through the first heating current, and then the running time corresponding to each heating current is allocated according to the power value and the rotation angle of the motor rotor.

In another possible implementation, different time allocation proportion correspondences can be set according to the current vector corresponding to the first heating current and the angle δ ₀ of the rotor, and then the specific time is determined in the determined correspondence according to θ _e Allocation proportion.

For example, the angle δ ₀ between the current vector corresponding to the first heating current and the rotor can be determined based on the three-phase current magnitude of the first heating current, thereby setting different values according to the angle δ ₀ between the current vector corresponding to the first heating current and the rotor. The corresponding relationship between time allocation proportions, and then determine the specific time allocation proportions in the determined correspondence relationship based on θ _e . Taking the heating current combination control motor in the above method 1 as an example, the working time allocation proportions corresponding to working point 1, working point 2 and working point 3 are determined based on θ _e and δ ₀ . Since there are many parameters required in the precise control process of the three-phase synchronous motor, in order to make it more convenient to use in the actual process, the drive motor 60 under special working conditions mostly adopts the look-up table method, because this requires the least performance of the controller and is convenient for different drives. Motor calibration.

The proportions of the motor's running time at working point 1, working point 2, and working point 3 are k ₁ , k ₂ , and k ₃ respectively, where k ₁ +k ₂ +k ₃ =1, and the phase resistance of the motor winding is R _s , Then the average power of the three-phase winding is:

When δ ₀ ≤15°, query the time allocation proportion corresponding to θ _e according to the first query table such as Table 2; when 15° <δ ₀ ≤45°, then query the time allocation proportion corresponding to θ e according to the second query table such as Table 3 (including Table 4 ), query the time allocation proportion corresponding to θ _e ; when δ ₀ >45°, query the time allocation proportion corresponding to θ _e according to a third query table such as Table 5.

It should be understood that at the same temperature, different driving motors 60 will have different sizes of δ ₀ . For the case where δ ₀ ≤15°, the three-phase power proportions of different operating points are relatively close, but in general, The δ ₀ corresponding to the synchronous motor is greater than 15°.

Table 2, first query table

Table 3, second query table

Motor angle θ _e Allocation pattern of k ₁ , k ₂ , k ₃ 0°≤θ _e <15° Mode 2 15°≤θ _e <45° Mode one 45°≤θ _e <75° Mode three 75°≤θ _e <105° Mode 2 105°≤θ _e <135° Mode one 135°≤θ _e <165° Mode three 165°≤θ _e <180° Mode 2

Table 4. Second query table (attached table)

Table 5, third query table

For example, when δ ₀ =30° and θ _e =30°, the distribution mode using mode one is queried according to the second lookup table, and then the following is queried according to the appendix of the second lookup table:

Thereby, the drive motor 60 can be controlled to operate in one heating cycle according to the ratio of k ₁ , k ₂ , and k ₃ under different heating currents.

It can be seen that when the rotor position angle of the driving motor 60 is different, the time ratio of the motor controller 50 to output each heating current is different.

Substituting the time proportion queried above into formula (7), the average power of the three-phase winding can be calculated.

It should be understood that the division of angles and the setting of time proportions in the lookup table in the above implementation are only examples, and can be set as needed in actual applications. This application does not discuss the specific angle setting methods and time proportions in the table. There are no restrictions on the setting method.

In a possible implementation, when the current output by the inverter circuit 52 switches from one heating current to another heating current, the current output by the inverter circuit 52 first decreases and then increases, and the output current drives The torque value of the drive motor 60 is less than the preset value.

It is easy to understand that in order to ensure that the motor does not generate torque during the heating process so that the vehicle can heat the battery 20 in a stationary state, when the motor switches between multiple heating currents, the current changes still need to be along the zero torque curve. During this process, the actual output torque may have small fluctuations. As long as the vehicle is kept stationary, the actual output torque may be a value close to zero that is less than the preset value, and the preset value is a smaller value close to zero.

In a possible implementation manner, during the process of switching the current output by the motor controller 50 from one type of heating current to another type of heating current, the current output by the motor controller 50 first decreases and then increases. During the switching process when the motor controller 50 outputs multiple heating currents, the current in the three-phase stator winding changes along the switching curve, first decreasing from one heating current to 0, and then increasing from 0 to another heating current, thus The electromagnetic torque of the drive motor 60 is maintained at 0, and the switching curve is the zero torque curve mentioned above.

As shown in Figure 8, when the current of the driving motor 60 switches between working point 1, working point 2, working point 3, and working point 4, in order to ensure that the torque of the driving motor 60 is always zero during the switching process, the three-phase current corresponding The transformation trajectories of direct-axis current and quadrature-axis current must always be maintained on the zero-torque curve. During the switching from the first working point to the second working point, the heating current change trajectory of the driving motor 60 must first return to the origin from the first working point (that is, the direct axis current and the quadrature axis current are both zero), and then move to the second working point.

For example, when the working point 1 and the working point 2 switch, the current changes first along the path 1 to the origin, and then along the path 2 to the working point 2; when the working point 1 and the working point 3 switch, the current changes The method first returns to the origin along path 1, and then along path 3 to working point 3; when working point 1 and working point 4 switch, the current size changes first along path 1 to return to the origin, and then along path 4 to working point 4; When working point 2 and working point 3 switch, the current changes first along path 2 back to the origin, and then along path 3 to work point 3; when working point 2 and working point 4 switch, the current changes first along the path 2 returns to the origin, and then follows path 4 to reach working point 4; when switching between working point 3 and working point 4, the current changes first returns to the origin along path 3, and then reaches working point 4 along path 4.

The switching path in the above example is bidirectional, and the reverse switching between two working points also switches along the path.

According to the solution of this application, each heating current is not equal. Therefore, within a fixed time period, the proportion of running time of multiple heating currents can be reasonably allocated so that the total of each of the three-phase windings in this time period can be The calorific value is basically the same. Thus, the balance of the average power of each of the three-phase windings is improved.

This application also provides a powertrain 30.

The powertrain 30 includes a drive motor 60 and the above-mentioned motor controller 50 . The drive motor 60 includes a rotor and a three-phase stator winding. Each phase winding of the three-phase stator winding is used to connect to the inverter circuit 52 of the motor controller 50 . At the midpoint of each of the three-phase bridge arms, the drive motor 60 receives the current of the power battery 20 from the inverter circuit 52 .

The drive motor 60 is used to output torque to zero under the driving of various heating currents. The various heating currents correspond to different current distribution ratios. The current distribution ratio is the current size of each phase stator winding in the three-phase stator winding under each heating current. proportion.

In one possible implementation, in response to the temperature of the power battery 20 being lower than a threshold and/or the heating instruction, the driving motor 60 is configured to output a torque of zero driven by multiple heating currents.

In a possible implementation, the powertrain 30 further includes a heat conduction device 40 , and the heat conduction device 40 is used to conduct heat generated by the motor to the power battery 20 .

Figure 9 is a schematic diagram of a motor control method provided by this application. As shown in Figure 9, the method includes the following steps:

It should be noted that, unless otherwise stated, in various embodiments of the present application, the sequence numbers of each process, such as S110, S120..., etc., do not mean the order of execution, and the order of execution of each process should be based on The functions and internal logic are determined and should not constitute any limitation on the implementation process of the embodiments of the present application.

This control method is applied to the electric vehicle 10. The electric vehicle 10 includes a power battery 20, a drive motor 60 and the motor controller 50 mentioned above.

S110, control the motor controller 50 to output multiple heating currents to the driving motor 60 in sequence.

Each heating current is used to control the torque output by the drive motor 60 to be zero, and each heating current includes three-phase currents, wherein: during the first time period, the motor controller 50 is controlled to output the first heating current; after the first time period In the second time period, the motor controller 50 is controlled to output any one of the second heating current, the third heating current and the fourth heating current; in the third time period after the second time period, the motor controller 50 is controlled to output the third heating current. Any one of a heating current, a second heating current, a third heating current and a fourth heating current; wherein the quadrature-axis current component of the first heating current and the quadrature-axis current component of the third heating current are not zero, and the second The direct-axis current component of the heating current and the direct-axis current component of the fourth heating current are zero.

It should be understood that the description of various heating currents may refer to the foregoing description.

This step may include the following steps. It should be understood that the following steps may not necessarily be performed or may be performed together with S110:

S120, obtain the current amplitude I _m , the motor temperature and the motor rotor rotation angle θ _e .

The current amplitude can be directly indicated by the heating command, or it can be calculated from the motor heating power P _m in the received heating command through the formula Among them, R ₀ is the phase resistance of the motor stator winding, and the current amplitude is the maximum current value in the three-phase stator winding of the driving motor 60. The current amplitude is also the vector current value synthesized by the direct axis current I _d and the quadrature axis current I _q . />

The temperature of the motor can be obtained through a temperature sensing device, which can measure the ambient temperature of the motor, or the temperature of the heat-carrying fluid of the motor thermal circuit, or the temperature of the stator winding of the drive motor 60, or the temperature in the heat conduction device, etc., this There are no restrictions on this application.

The rotation angle of the rotor of the drive motor 60 can be detected by a sensor installed on the rotor shaft end of the drive motor 60, which is the rotation angle of the drive motor 60 in a stationary state. The rotation angle ranges from 0 to 360°.

In a possible implementation, if the current rotor angle is greater than 180°, 180° is subtracted so that θ _e is in the range of 0 to 180°.

S130, determine multiple heating currents.

Current values corresponding to various heating currents are calculated based on the obtained current amplitude _Im , motor temperature and rotor rotation angle θ _e of the drive motor 60.

For the specific process, please refer to the relevant descriptions of the aforementioned calculation formulas (4), (5) and (6).

S140, determine the running time corresponding to each heating current.

The running time corresponding to each heating current can be determined based on the rotation angle θ _e of the rotor of the drive motor 60 and the size of the heating current.

For the specific determination process, please refer to the aforementioned table lookup method.

As shown in FIG. 10 , a possible specific process for the above-mentioned motor controller 50 , powertrain 30 and electric vehicle 10 to execute the above-mentioned control method is as follows.

Step 1: The motor controller 50 in the powertrain 30 obtains a heating instruction. The heating instruction may be sent by the vehicle controller 70 to instruct the execution of the battery 20 heating process. When the temperature of the power battery 20 is lower than the threshold and/or the user presses the heating button (i.e., issues a heating demand command), the vehicle is in a stationary state and does not need to be started and the temperature of the power battery 20 is lower than a predetermined value, the vehicle controller 70 will send Heating instructions.

Step 2: The vehicle controller 70 detects whether the vehicle status meets the parking heating conditions, such as battery pack temperature, remaining battery capacity, whether the vehicle is stationary, whether the handbrake is on, etc. If the heating conditions are met, the battery is heated.

Step 3: The motor controller 50 in the powertrain 30 obtains the command value P _m of the motor heating power, so that the heating current amplitude can be calculated Where R _s is the phase resistance of the motor stator winding.

Step 4: The motor controller 50 in the powertrain 30 detects the rotor angle of the drive motor 60 in a stationary state, that is, the rotor rotation angle θ _e . The rotor rotation angle θ _e can be obtained through a sensor installed on the shaft end of the motor rotor, or can be obtained through other methods, which is not limited in this application. The range of the rotation angle is 0~360°. If the current angle is greater than 180°, 180° can be subtracted so that θ _e is always in the range of 0~180°.

Step 5: The motor controller 50 in the powertrain 30 obtains the motor temperature and queries the motor zero torque ammeter at the current temperature.

Step 6: According to the heating current amplitude _Im , the motor controller 50 in the powertrain 30 obtains the direct-axis current i _dm and the quadrature-axis current i _qm corresponding to the amplitude _Im from the zero-torque ammeter in the first quadrant of the motor. , and calculate the angle between the zero-torque operating point and the direct axis: δ ₀ = arctan (i _qm /i _dm ), and the range of δ ₀ is 0 to 90°.

Step 7: The motor controller 50 in the powertrain 30 determines the running time of each of the multiple heating currents based on θ _e and δ ₀ , for example, the motor is at the direct axis zero torque operating point (i.e., operating point 1), The running time distribution proportions k _{1 , k 2 , and k 3 of the zero-torque working point in the first quadrant (i.e., working point 2) and the zero-torque working point in the fourth quadrant (i.e., working point 3) are k 1} , k ₂ , and k ₃ .

For example, when δ ₀ ≤15°, the time allocation proportion corresponding to θ _e is queried according to the first lookup table such as Table 2; when 15°<δ ₀ ≤45°, then the time allocation proportion corresponding to θ e is queried according to the second lookup table such as Table 3 (Including Table 4), query the time allocation proportion corresponding to θ _e ; when δ ₀ >45°, query the time allocation proportion corresponding to θ _e according to the third query table such as Table 5.

Step 8: The motor controller 50 in the powertrain 30 controls the switching tube in the inverter circuit 52, so that the drive motor 60 runs cyclically at three operating points. Suppose a heating period is T, then the drive motor 60 is The running time of each working point is k ₁ T, k ₂ T, k ₂ T respectively. For example, if a heating cycle is 5 seconds, the drive motor 60 is allowed to run stably at working point 1 for 5k _{for 1} second, then switch to working point 2 to run stably for 5k for ₂ seconds, and then switch to working point 3 to run stably for 5k _{for 3} seconds;

Step 9: The motor controller 50 in the power assembly 30 detects the temperature of the power battery 20. If the temperature of the power battery 20 does not reach the set temperature, return to step 5. Since there is a temperature rise in the drive motor 60 during the heating process, the zero-torque ammeter of the drive motor 60 will change. Therefore, in step 5, the zero-torque ammeter needs to be reacquired based on the newly acquired temperature of the drive motor 60 . If the temperature of the power battery 20 reaches the set temperature, heating is stopped.

Figure 11 is a diagram showing the relationship between three-phase power and rotor angle at different working angles δ ₀ . As shown in Figure 11, through the above implementation process provided by this application, the total three-phase power remains unchanged at 1.5 at any position, but the maximum phase power is significantly reduced, the minimum phase power is significantly increased, and the three-phase power balance is improved. Moreover, as δ ₀ increases, the difference between the maximum phase power and the minimum phase power shrinks, and the three-phase power balance improves; when δ ₀ ≥ 45°, the three-phase power can be completely balanced at any rotor position.

In a possible implementation, during the process of the motor controller 50 outputting the first heating current, the ratio of the quadrature-axis current component and the direct-axis current component of the first heating current is the working angle. When the first heating current is working The angle is less than 45 degrees, and the variance of the effective value of each phase current in the three-phase current of the first heating current decreases with the increase of the working angle of the first heating current; in the process of the motor controller 50 outputting all three heating currents, The arctangent value of the ratio of the quadrature-axis current component and the direct-axis current component of the third heating current is the working angle. When the working angle is less than 45 degrees, the variance of the effective value of each phase current in the three-phase current of the third heating current changes with the working angle. decreases with increasing.

In a possible implementation, during the process of the motor controller 50 outputting the first heating current, when the working angle of the first heating current is greater than 45 degrees, the effective value of each phase current in the three-phase current of the first heating current The same; during the process of the motor controller 50 outputting the third heating current, when the working angle of the third heating current is greater than 45 degrees, the effective values of each phase current in the three-phase current of the third heating current are the same.

According to the solution of this application, the drive motor 60 is allowed to switch back and forth between different heating currents in the zero-torque state to avoid a certain phase winding where the heating power is concentrated, thereby balancing the multi-phase heating power of the drive motor 60 and improving heating efficiency.

Those of ordinary skill in the art will appreciate that the units and algorithm steps of each example described in conjunction with the embodiments disclosed herein can be implemented with electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Skilled artisans may implement the described functionality using different methods for each specific application, but such implementations should not be considered beyond the scope of this application.

Those skilled in the art can clearly understand that for the convenience and simplicity of description, the specific working processes of the systems, devices and units described above can be referred to the corresponding processes in the foregoing method embodiments, and will not be described again here.

In the several embodiments provided in this application, it should be understood that the disclosed systems, devices and methods can be implemented in other ways. For example, the device embodiments described above are only illustrative. For example, the division of the units is only a logical function division. In actual implementation, there may be other division methods. For example, multiple units or components may be combined or can be integrated into another system, or some features can be ignored, or not implemented. On the other hand, the coupling or direct coupling or communication connection between each other shown or discussed may be through some interfaces, and the indirect coupling or communication connection of the devices or units may be in electrical, mechanical or other forms.

If the functions are implemented in the form of software functional units and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present application is essentially or the part that contributes to the existing technology or the part of the technical solution can be embodied in the form of a software product. The computer software product is stored in a storage medium, including Several instructions are used to cause a computer device (which may be a personal computer, a server, or a network device, etc.) to execute all or part of the steps of the methods described in various embodiments of this application. The aforementioned storage media include: U disk, mobile hard disk, read-only memory (ROM), random access memory (RAM), magnetic disk or optical disk and other media that can store program code. .

The above are only specific embodiments of the present application, but the protection scope of the present application is not limited thereto. Any person familiar with the technical field can easily think of changes or substitutions within the technical scope disclosed in the present application. should be covered by the protection scope of this application. Therefore, the protection scope of this application should be subject to the protection scope of the claims.

Claims (15)

1. A motor controller, characterized in that the motor controller is used to output a driving current to a driving motor of an electric vehicle and to output a variety of heating currents, and the driving current is used to control the torque output by the driving motor to be greater than zero. , each of the heating currents is used to control the torque output by the driving motor to be zero, and each of the heating currents includes three-phase currents, where: The parameters of any two heating currents are different, and the parameters include the ratio of the effective values of each phase current in the three-phase current of each heating current. 2. The motor controller according to claim 1, wherein the motor controller is configured to output a first heating current first, and then output at least one of a second heating current, a third heating current and a fourth heating current. or, sequentially output at least one of the second heating current, the third heating current and the fourth heating current, and then output the first heating current; Wherein, the quadrature axis current component of the first heating current and the quadrature axis current component of the third heating current are not zero, and the quadrature axis current component of the second heating current and the quadrature axis current component of the fourth heating current are not zero. The current component is zero. 3. The motor controller according to claim 2, wherein the direct axis current component of the first heating current, the direct axis current component of the second heating current, the direct axis current component of the third heating current Neither the current component nor the direct-axis current component of the fourth heating current is zero. 4. The motor controller according to claim 3, wherein during the process of the motor controller outputting the first heating current, the quadrature-axis current component and the direct-axis current component of the first heating current The ratio of is the working angle. When the working angle of the first heating current is less than 45 degrees, the variance of the effective value of each phase current in the three-phase current of the first heating current increases with the working angle of the first heating current. large and reduced; In the process of the motor controller outputting the third heating current, the arc tangent value of the ratio of the quadrature-axis current component and the direct-axis current component of the third heating current is the working angle. When the working angle is less than 45 degree, the variance of the effective value of each phase current in the three-phase current of the third heating current decreases as the working angle increases. 5. The motor controller according to claim 4, wherein during the process of the motor controller outputting the first heating current, when the working angle of the first heating current is greater than 45 degrees, the The effective values of each phase current in the three-phase current of the first heating current are the same; During the process of the motor controller outputting the third heating current, when the working angle of the third heating current is greater than 45 degrees, the effective values of the three-phase currents of the third heating current are the same. 6. The motor controller according to any one of claims 1 to 5, characterized in that the effective value of each phase current in the three-phase current of each heating current changes with the rotor angle of the driving motor. And change. 7. The motor controller according to any one of claims 2 to 5, wherein the motor controller is configured to output a first heating current, a second heating current, a third heating current and In the process of at least one of the fourth heating current, or in the process of the motor controller being used to output at least one of the second heating current, the third heating current and the fourth heating current in sequence, and then output the first heating current, The time period for the motor controller to output each heating current changes with the change of the rotor angle of the drive motor. 8. The motor controller according to any one of claims 1 to 5, wherein during the process of the motor controller outputting the plurality of heating currents to the driving motor, any one of the heating currents The ratio of the heating power on any phase winding of the drive motor to the total heating power of any heating current on the three-phase winding of the drive motor is less than 2/3. 9. The motor controller according to any one of claims 1 to 5, characterized in that during the process of switching the current output by the motor controller from one type of heating current to another type of heating current , the current output by the motor controller first decreases and then increases, and the motor controller is used to control the torque output by the drive motor to always be less than the preset torque value. 10. The motor controller according to any one of claims 1 to 9, characterized in that, in response to the temperature of the power battery being lower than a threshold and/or a heating instruction, the motor controller is configured to provide the driver with The motor outputs the various heating currents. 11. A powertrain, characterized by comprising a drive motor and a motor controller, the motor controller being configured to output at least one heating current to the drive motor to control the torque of the drive motor to be zero, wherein: Neither the quadrature-axis current component nor the direct-axis current component of the at least one heating current is zero. 12. The powertrain of claim 11, wherein the motor controller is configured to output the at least one heating current in response to the temperature of the power battery being below a threshold and/or a heating command. 13. The powertrain according to any one of claims 11-12, wherein during the process of the motor controller outputting the at least one heating current, the quadrature axis current of each heating current The arctangent value of the ratio between the component and the direct-axis current component is the working angle. When the working angle is less than 45 degrees, the variance of the effective value of each phase current in the three-phase current of the heating current increases with the increase of the working angle. decrease. 14. A control method for a motor controller, characterized in that the control method includes: The motor controller is controlled to output multiple heating currents to the drive motor in sequence, each of the heating currents is used to control the torque output by the drive motor to be zero, and each of the heating currents includes three-phase currents, where: In a first period of time, control the motor controller to output a first heating current; In a second time period after the first time period, control the motor controller to output any one of the second heating current, the third heating current and the fourth heating current; In a third time period after the second time period, control the motor controller to output any one of the first heating current, the second heating current, the third heating current and the fourth heating current; Wherein, the quadrature-axis current component of the first heating current and the quadrature-axis current component of the third heating current are not zero, and the direct-axis current component of the second heating current and the direct-axis current component of the fourth heating current are not zero. The current component is zero. 15. The control method according to claim 14, characterized in that the control method includes: In the process of switching the current output by the motor controller from one type of heating current to another type of heating current, the current output by the motor controller is controlled to first decrease and then increase, and the motor is controlled to The controller makes the torque output by the drive motor always less than the preset torque value.