CN117227509A

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

Info

Publication number: CN117227509A
Application number: CN202311270586.9A
Authority: CN
Inventors: 姜峰; 李红勇; 郭金辉; 张庆志; 杨帆
Original assignee: Huawei Digital Power Technologies Co Ltd
Current assignee: Huawei Digital Power Technologies Co Ltd
Priority date: 2023-09-27
Filing date: 2023-09-27
Publication date: 2023-12-15

Abstract

A motor controller, a power assembly and a method for balancing multiphase heating power relate to the field of new energy automobiles and can be applied to pure electric vehicles and hybrid vehicles. The motor controller includes: the motor controller is used for outputting driving current and outputting various heating currents to the driving motor of the electric automobile, the driving current is used for controlling the torque output by the driving motor to be larger than zero, each heating current is used for controlling the torque output by the driving motor to be zero, each heating current comprises three-phase current, and the three-phase current comprises the following components: the parameters of any two heating currents are different, and the parameters comprise the ratio of the effective values of each phase current in the three-phase currents of each heating current. According to the scheme of the application, the heating power of the motor can be balanced, and the heating efficiency of the battery can be improved.

Description

Motor controller, power assembly and method for balancing multiphase heating power

Technical Field

The present disclosure relates to the field of electric automobiles, and more particularly, to a motor controller, powertrain, and method of balancing multiphase power.

Background

Under the dual drive of market demand and policy guidance, the electric automobile industry is moving into a high-speed development stage. With the great popularization and application of electric automobiles, the problems of vehicle dynamics and endurance decay at low temperature are gradually attracting attention. Compared with the normal temperature environment, the discharge multiplying power of the battery in the low temperature environment is rapidly reduced, so that the power of the vehicle is insufficient; meanwhile, when the battery is charged at low temperature, negative electrode deposition is easy to occur to lithium ions, lithium dendrites are generated, and the capacity of the battery is irreversibly reduced, so that the endurance mileage is shortened; moreover, over time, the growing lithium dendrites may puncture the separator between the positive and negative electrodes of the battery, forming an internal short circuit, causing a safety hazard. In the prior battery heating scheme, the power battery is heated by using a resistance heating device such as a positive temperature coefficient (positive temperature coefficient, PTC) thermistor and the like, so that the defects of high cost, large installation space and the like exist. And the proposal also proposes to adopt the self-heating of the motor to heat the power battery to replace the original part or all of PTC components so as to improve the integration level of the system and reduce the cost. However, in this heating scheme, there is a problem that the motor is unbalanced in multiphase power and uneven in heat generation. The current load of a certain phase reaches the maximum, so that the single-phase high-voltage stress overrun and the single-phase temperature rise are easy to cause, and further, a temperature sensor close to the single-phase winding is caused to overheat rapidly, the heating power of a motor is influenced, and the heating rate of a power battery is influenced. Meanwhile, uneven heating of the three-phase winding can also cause a phase with serious heating to have shorter service life, and the symmetry and reliability of the motor can be influenced after long-term use.

Therefore, how to balance the heating power of the motor phases during the process of heating the battery is a problem to be solved.

Disclosure of Invention

The application provides a motor controller, a control method and a power assembly for balancing multiphase power, which are used for avoiding a certain phase winding with concentrated heating power by switching back and forth between different heating currents of a motor in a zero torque state, so that the multiphase heating power of the motor is balanced, and the heating efficiency of a battery is improved.

In a first aspect, the present application provides a motor controller for outputting a driving current for controlling a torque output by a driving motor to be greater than zero and outputting a plurality of heating currents, each heating current for controlling the torque output by the driving motor to be zero, each heating current including three-phase currents, to a driving motor of an electric vehicle, wherein: the parameters of any two heating currents are different, and the parameters comprise the ratio of the effective values of each phase current in the three-phase currents of each heating current.

In the present application, the motor controller outputs a plurality of heating currents to the driving motor is understood as outputting one heating current to the driving motor for a period of time, then switching to another heating current for a period of time, and the like, sequentially under a plurality of heating currents, and continuously cycling the operation.

According to the scheme of the application, the motor alternately operates between different heating currents in a zero torque state, so that the stator coil of the motor is lost to generate heat in a static state and the heat is transmitted to the power battery, thereby heating the battery, and the current distribution ratios of the different heating currents in the three-phase stator windings are different, so that the three-phase power ratios corresponding to the different heating currents are different, a phase winding in which heating power is concentrated is avoided, the multi-phase heating power of the motor is balanced, and the heating efficiency of the battery is improved.

It should be appreciated that the various heating currents are set for the purpose of generating heat at rest of the motor, so the various heating currents are set for the purpose of zero torque of the motor, but the motor may generate unstable small torque at various heating currents due to implementation level of the device and actual working state of the motor, so only the stationary state of the vehicle needs to be maintained, and the actual output torque may be a small value close to zero.

With reference to the first aspect, in some implementations of the first aspect, the motor controller is configured to sequentially output first heating current, and then output at least one of second heating current, third heating current, and fourth heating current, or sequentially output at least one of second heating current, third heating current, and 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 zero.

With reference to the first aspect, in certain implementations of the first aspect, none of a direct-axis current component of the first heating current, a direct-axis current component of the second heating current, a direct-axis current component of the third heating current, and a direct-axis current component 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 driving motor is not zero, so that the reluctance torque is not zero, the direct axis current corresponds to the quadrature axis current, the absolute values of the synchronous torque and the reluctance torque are equal, the signs are opposite, and 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 driving motor is zero, the direct axis current component is not zero, namely 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 the reluctance torque of the driving motor are both zero.

With reference to the first aspect, in some implementations of the first aspect, in a process of outputting the first heating current by the motor controller, a ratio of a quadrature-axis current component and a direct-axis current component of the first heating current is an operating angle, and when the operating angle of the first heating current is less than 45 degrees, a variance of an effective value of each phase current in three-phase currents of the first heating current decreases with an increase in the operating angle of the first heating current; in the process that the motor controller outputs the third heating current, the arctangent value of the ratio of the quadrature axis current component and the direct axis current component of the third heating current is a working angle, and when the working angle is smaller than 45 degrees, the variance of the effective value of each phase current in the three-phase current of the third heating current is reduced along with the increase of the working angle.

With reference to the first aspect, in some implementations of the first aspect, when the working angle of the first heating current is greater than 45 degrees during the process of outputting the first heating current by the motor controller, the effective values of all phase currents in the three phase currents of the first heating current are the same; in the process that the motor controller outputs the third heating current, when the working angle of the third heating current is larger than 45 degrees, the effective values of all phase currents in the three-phase currents of the third heating current are the same.

With reference to the first aspect, in certain implementations of the first aspect, an effective value of each phase current in the three phase currents of each heating current varies as a function of a rotor angle of the drive motor.

With reference to the first aspect, in certain implementation manners of the first aspect, in a process that the motor controller is configured to sequentially 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 in a process that the motor controller is configured to 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, a duration that the motor controller is configured to output each heating current varies with a variation of a rotor angle of the driving motor.

It will be appreciated that the ratio of the operating time period for each of the plurality of heating currents is related to the rotor position angle of the motor, and that the operating time period for the heating currents will vary correspondingly from one rotor position angle to another.

With reference to the first aspect, in certain implementations of the first aspect, during the process that the motor controller outputs multiple heating currents to the driving motor, a ratio of heating power of any one heating current on any one phase winding of the driving motor to total heating power of any one heating current on three phase windings of the driving motor is less than 2/3.

With reference to the first aspect, in certain implementations of the first aspect, during switching of the current output by the motor controller from one heating current to another heating current, the motor controller is configured to control the torque output by the drive motor to be always less than the torque preset value.

It should be appreciated that, in order to keep the motor stationary, the current transformation should be reduced first and then increased to the target heating current during the switching process between the various heating currents, so as to ensure that the torque value of the motor driven by the current output by the inverter circuit is always zero.

With reference to the first aspect, in certain implementations of the first aspect, during a switching of the current output by the motor controller from one heating current to another heating current, the current output by the motor controller decreases and then increases.

With reference to the first aspect, in certain implementations of the first aspect, the motor controller is configured to output a plurality of heating currents to the drive motor in response to a temperature of the power battery being below a threshold and/or a heating command.

It should be appreciated that the motor controller may output various heating currents to the drive motor upon receiving an indication that the temperature of the power battery is below a threshold, or upon receiving a heating command, and that detecting the temperature of the power battery and sending the heating command may be performed by the vehicle controller 70, or the motor controller may perform power battery heating in response to other commands, as the application is not limited in this respect.

According to the scheme of the application, the heating power of the multiphase winding of the driving motor can be balanced, and the heating efficiency of the battery is improved.

In a second aspect, there is provided a powertrain comprising: a drive motor and a motor controller for outputting at least one heating current to the drive motor to control the torque of the drive motor to zero, wherein: at least one of the heating currents has a quadrature-axis current component and a direct-axis current component that are non-zero.

The quadrature axis current component and the direct axis current component of the heating current output by the motor controller of the power assembly are not zero, but the heating current can control the torque of the driving motor to be zero. Compared with the heating current with zero quadrature axis current, the heating power of the heating current on the three-phase winding of the driving motor is more uniform, so that the local temperature rise of the motor winding can be avoided, and the reliability and the heating efficiency of the electric drive heating process are improved.

In combination with the second aspect, in certain implementations of the second aspect, the motor controller is configured to output at least one heating current to the drive motor in response to the temperature of the power battery being below a threshold value and/or a heating command.

The motor controller of the power assembly is used for outputting heating current to heat the winding of the driving motor, and the current generated on the winding of the driving 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.

With reference to the second aspect, in certain implementations of the second aspect, during output of at least one heating current by the motor controller, an arctangent value of a ratio of a quadrature-axis current component and a direct-axis current component of each heating current is an operating angle, and when the operating angle is less than 45 degrees, a variance of an effective value of each phase current in three-phase currents of the heating current decreases with an increase in the operating angle.

The uniformity of the three-phase current effective values of the heating current output by the motor controller in the power assembly provided by the application can be enhanced along with the increase of the working angle, and when the working angle is larger than 45 degrees, the three-phase current effective values of the heating current are the same, so that the heating power of the heating current in the three-phase winding is the same, the heating of the driving motor is more uniform, and the heating performance is facilitated to be provided.

In a third aspect, there is provided a motor control method, the method comprising: the control motor controller outputs multiple heating currents to the driving motor in sequence, each heating current is used for controlling the torque output by the driving motor to be zero, and each heating current comprises three-phase currents, wherein: controlling the motor controller to output a first heating current in a first time period; controlling the motor controller to output any one of the second heating current, the third heating current and the fourth heating current in a second period of time after the first period of time; controlling 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 in a third period after the second period; 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.

With reference to the third aspect, in some implementations of the third aspect, during a process of switching a current output by the motor controller from one heating current to another heating current, the current output by the motor controller is controlled to decrease and then increase, and the motor controller is controlled so that a torque output by the driving motor is always smaller than a torque preset value.

In a fourth aspect, there is provided an electric vehicle comprising a vehicle controller, a power battery and a power assembly as in the second aspect and in various possible implementations of the second aspect, the vehicle controller sending a heating command to the power assembly in response to the temperature of the power battery being below a threshold and/or a heating demand, the heating command instructing the power assembly to heat the power battery; the heat conduction device is used for conducting heat generated by the driving motor in the power assembly to the power battery.

Other advantages of the first aspect may be referred to as the advantages described in the first aspect, and will not be described here again.

Drawings

Fig. 1 is a schematic diagram of an electric vehicle according to an embodiment of the present application;

FIG. 2 is a schematic diagram of an electric vehicle thermal management system according to an embodiment of the present application;

FIG. 3 is a schematic diagram of a motor controller according to an embodiment of the present application;

Fig. 4 is a schematic diagram of zero torque heating current of a permanent magnet synchronous motor provided by the application;

FIG. 5 is a zero torque heating current schematic diagram of an electrically excited synchronous motor provided by the application;

FIG. 6 is a schematic diagram of three-phase currents at different rotor angles according to the present application;

FIG. 7 is a schematic diagram of three-phase power at different rotor angles provided by the present application;

FIG. 8 is a schematic diagram of a switching curve between heating currents according to the present application;

FIG. 9 is a schematic flow chart of a motor control method provided by the application;

FIG. 10 is a schematic of a workflow provided by the present application;

FIG. 11 is a graph of three phase power versus rotor angle for different operating angles provided by the present application.

Detailed Description

The technical scheme of the application will be described below with reference to the accompanying drawings. The following detailed description of the embodiments and the accompanying drawings are provided to illustrate the principles of the application and are not intended to limit the scope of the application, i.e., the application is not limited to the embodiments described.

With the great popularization and application of electric automobiles, the problems of vehicle dynamics and endurance decay at low temperature are gradually attracting attention.

Compared with the normal temperature environment, the discharge multiplying power of the battery in the low temperature environment is rapidly reduced, so that the power of the vehicle is insufficient; meanwhile, when the battery is charged at low temperature, negative electrode deposition is easy to occur to lithium ions, lithium dendrites are generated, and the capacity of the battery is irreversibly reduced, so that the endurance mileage is shortened; moreover, over time, the growing lithium dendrites may puncture the separator between the positive and negative electrodes of the battery, forming an internal short circuit, causing a safety hazard. Therefore, it is generally necessary to heat the battery so as to ensure the normal use of the battery.

In one possible implementation manner, an additional PTC heating device is added to the vehicle thermal management system, and the heat is transferred to the cooling medium of the thermal management system through the radiator, and then the battery pack is heated through thermal cycle, so that the battery pack is heated to a normal working range, and the normal charge and discharge capability is ensured.

However, the separate PTC heating device not only increases material costs, but is limited by the vehicle interior space and manner of installation, and also creates additional structural design costs, resulting in higher costs for the battery heating scheme.

In another possible implementation, the motor stator windings may be multiplexed for heating. The inverter circuit 52 is controlled to generate a voltage to excite the motor to generate a specific current, and the current acts on the stator winding to generate only current along the direction of the rotor magnetic field, so that joule heat is generated, and the heat indirectly heats the battery pack through the circulation of the cooling system.

Although PTC cost can be saved in the implementation mode, three-phase currents of the motor are all direct currents due to the fact that the motor is static during heating, the three-phase currents are related to the current rotor position, the rotor stays at any position, three-phase winding power is not equal, and therefore heating power of each phase is seriously unbalanced. The inverter power device is also affected by three-phase power imbalance, and the switching tube conduction loss of the bridge arm corresponding to the maximum power of the winding is obviously higher than that of other two-phase bridge arms. When the maximum heating power index is designed, the maximum heating power of the motor is limited because the temperature rise condition of the maximum power phase including the winding and the power device under the extreme condition needs to be considered so as to leave more safety margin, and the battery temperature rise rate is slow, so that the traveling experience of a user is influenced.

Based on the problems, the application provides a motor controller, a motor control method and a power assembly, wherein the driving motor alternately operates between different heating currents in a zero torque state, so that the stator coil of the driving motor is in a static state to generate heat in a loss mode, and the heat is transmitted to a power battery, so that the battery is heated, the current distribution ratios of the different heating currents in three-phase stator windings are different, the three-phase power ratios corresponding to the different heating currents are different, a certain phase winding with concentrated heating power is avoided, the multi-phase heating power of the motor is balanced, and the heating efficiency of the battery is improved.

In the description of the present application, it should be noted that, unless explicitly stated and limited otherwise, the terms "disposed," "mounted," "connected," and "connected" are to be construed broadly, and may be, for example, fixedly connected, detachably connected, or integrally connected; can be directly connected or indirectly connected through an intermediate medium. The specific meaning of the above terms in the present application can be understood as appropriate by those of ordinary skill in the art. The term "comprising" as used in the present application should not be construed as limited to what is listed thereafter; it does not exclude other elements or steps. Thus, it should be interpreted as specifying the presence of the stated features, integers, steps or components as referred to, but does not preclude the presence or addition of one or more other features, integers, steps or components, or groups thereof. Thus, the expression "a device comprising means a and B" should not be limited to a device consisting of only components a and B.

In order to facilitate understanding of the embodiments of the present application, first, concepts and technologies related to the embodiments of the application will be briefly described.

It is to be understood that the following related terms and illustrations are generic to each embodiment, and to different embodiments, individually or in combination, based on some inherent or extrinsic relationship.

1. Rotary transformer

May be simply referred to as a resolver, which is a sensor mounted to the shaft end of the motor rotor, for obtaining the current position of the motor rotor.

2. Synchronous motor

In one type of ac motor, a rotating magnetic field is generated by supplying symmetrical current to a stator winding, a rotor is provided with a permanent magnet or an exciting winding, and the rotor magnetic field synchronously rotates with the rotating magnetic field of the stator due to the magnetic pulling force of the stator magnetic field and generates torque to the outside.

3. Electromagnetic torque

The torque output from the motor shaft of the synchronous motor to the outside is called electromagnetic torque, which consists of synchronous torque and reluctance torque.

4. Synchronous torque

The torque generated by the interaction of 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 not consistent, so that the magnetic resistance is not equal. Since the magnetic flux always preferentially selects the path with the smallest reluctance, the inconsistency of the direct axis and the quadrature axis reluctance causes the magnetic flux to be biased in the path selection, and an extra torque called reluctance torque is generated.

6. Copper loss

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

7. Vector control

The control method is suitable for the motor with the rotating magnetic field, can equivalent the three-phase stator current coefficient to an orthogonal two-phase system, and decomposes the space vector of the motor rotor into components on two rectangular coordinate axes: the magnetic field direction component and the rotor electromotive force direction component are independently controlled, so that direct control of the magnetic flux and the electromotive force of the motor can be realized, and the aim of accurately controlling the torque and the speed of the motor is fulfilled. Specifically, the mutual conversion of the physical quantities between a three-axis two-dimensional stator stationary coordinate system and a two-axis rotating coordinate system can be realized through a clark (clark) conversion and a park (park) conversion. Taking the vector control mode of a permanent magnet synchronous motor as an example, a rotating coordinate system is formed by taking the direction of a rotor magnetic field as a straight axis (d axis) and taking the direction advanced by 90 degrees as a quadrature axis (q axis). Three-phase current can be converted into current on d-axis and q-axis, and the given direct-axis current I _d And quadrature axis current I _q Synthesized current vector I _s The formed magnetic field direction forms an angle with the rotor magnetic field direction, and the reasonable angle enables the magnetic fields to act to form maximum torque, so that the motor outputs torque.

Fig. 1 is a schematic diagram of an electric vehicle according to 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 commands to the powertrain 30 to control vehicle operation or to perform heating, etc. The power assembly 30 is used to drive the electric vehicle 10 or to heat the power battery 20. The powertrain 30 includes a motor controller 50 and a drive motor 60. The motor controller 50 includes a control device 51 and an inverter circuit 52, and the inverter circuit 52 may be a control circuit formed by insulated gate bipolar transistors (insulated gate bipolar transistor, IGBTs), wherein on-off control signals of the IGBTs are provided by the control device 51. Taking control of the three-phase motor as an example, 6 IGBTs are adopted to form an inversion control circuit, direct current at a battery end is converted into three-phase alternating current, and the three-phase alternating current is respectively supplied to three-phase windings (U, V, W) of the three-phase motor so as to control the rotating speed or torque output of the three-phase motor. The heat transfer device 40 may be considered to be included in the powertrain 30. The heat generated by the driving motor 60 is transferred to the power battery 20 through the heat conduction device 40 to heat the power battery 20. The motor controller 50 can generate modulation voltage through the on-off of the internal power device, so as to excite the motor three-phase winding to generate heating current.

As shown in fig. 2, the embodiment provided by the application can be applied to the electric automobile thermal management system architecture, wherein heat generated by a motor winding is brought into an oil tank through an oil cooling pipeline, heat of the oil tank is brought into a cooling liquid circulation pipeline through cooling liquid, and the cooling pipeline is communicated with a power battery, so that the power battery can be heated by heat generated by a driving motor.

The application is mainly applied to the heating scene of the power battery of the electric automobile, and can be particularly any one of different types of automobiles such as a car, a truck, a passenger car and the like, and can also be a transportation device for carrying people or goods such as a tricycle, a two-wheel vehicle, a train and the like, or other types of transportation means driven by the power battery. Electric vehicles include, but are not limited to, pure electric vehicles (pure electric vehicle/battery electric vehicle, pure EV/battery EV), hybrid electric vehicles (hybrid electric vehicle, HEV), extended range electric vehicles (range extended electric vehicle, REEV), plug-in hybrid electric vehicles (plug-in hybrid electric vehicle, PHEV), new energy vehicles (new energy vehicle, NEV), and the like.

The drive motor 60 in embodiments of the present application includes, but is not limited to, three-phase or multi-phase, axial or radial permanent magnet synchronous motors, three-phase or multi-phase, axial or radial permanent magnet auxiliary synchronous reluctance motors, and three-phase or multi-phase, axial or radial electrically excited synchronous motors, etc. The driving motor 60 in the embodiment of the present application has the same structure 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 can be 3 phases, 5 phases, 6 phases and 9 phases. The cooling mode commonly used by the motor can be oil cooling, water cooling or air cooling. For simplicity of description, the solution of the present application will be described below by taking a three-phase driving motor as an example, and the case of multiple phases may be similar to the description of the three-phase driving motor.

The power battery in the embodiment of the application can 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 or a sodium ion battery, etc., and is not limited herein. In terms of scale, the power battery in the embodiment of the application may be a battery cell unit, or may be a battery module or a battery pack, which is not limited herein. From the application scene, the power battery can be applied to power devices such as automobiles, ships and the like. For example, the present application can be applied to a power vehicle to supply power to a motor of the power vehicle as a power source of the electric vehicle. The power battery can also supply power for other electric devices in the electric automobile, such as an in-car air conditioner, an in-car player and the like. For convenience of description, the following will take an example that the power battery is applied to an electric automobile (or called a new energy automobile), and the scheme of the present application will be described.

The motor controller 50 in the embodiment of the application comprises an inverter circuit 52, and the inverter circuit 52 is formed by Insulated Gate Bipolar Transistors (IGBTs). The motor control may further 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 control of a three-phase motor as an example, 6 IGBTs are used to form the inverter circuit 52, and current in the power battery 20 is fed into the motor to supply current to three-phase windings of the three-phase motor, respectively, to control the rotational speed or torque output of the three-phase motor.

The present application provides a motor controller 50.

As shown in fig. 3, the motor controller 50 includes an inverter circuit 52, where the inverter circuit 52 includes three-phase legs connected in parallel, one end of each phase leg is used to connect with the positive pole of the power battery 20, the other end of each phase leg is used to connect with the negative pole of the power battery 20, and the midpoint of each phase leg is used to connect with one phase winding of the three-phase stator windings of the motor.

The motor controller 50 is configured to output a driving current for controlling a torque output from the driving motor 60 to be greater than zero and to output a plurality of heating currents for controlling a torque output from the driving motor 60 to be zero to the driving motor 60 of the electric vehicle 10, each heating current including three-phase currents, wherein: the parameters of any two heating currents are different, and the parameters comprise the ratio of the effective values of each phase current in the three-phase currents of each heating current.

In one possible implementation, the plurality of heating currents includes a first heating current having a non-zero quadrature axis current component; the plurality of heating currents further comprises at least one of a second heating current, a third heating current and a fourth heating current, the quadrature axis current component of the third heating current is not zero, the third heating current is unequal to the first heating current, the quadrature axis current component of the second heating current and the fourth heating current is zero, and the second heating current and the fourth heating current are unequal.

In one possible implementation, the motor controller 50 is configured to sequentially 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; 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 zero.

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

Illustratively, the ratio of the effective values of each phase of the three phases of current of the first heating current is: and U phase: v phase: w phase=i _u1 ：I _v1 ：I _w1 The method comprises the steps of carrying out a first treatment on the surface of the The ratio of the effective values of each phase of current in the three-phase current of the second heating current is as follows: and U phase: v phase: w phase=i _u2 ：I _v2 ：I _w2 The method comprises the steps of carrying out a first treatment on the surface of the Then I _u1 ：I _v1 ：I _w1 And I _u2 ：I _v2 ：I _w2 Different.

In a possible implementation manner, the motor controller 50 further includes a control device 51, and control ends of six switch modules included in the three-phase bridge arm are respectively connected with the control device 51; the control device 51 is used for controlling the on-off of the switch module to make the inverter circuit 52 alternately output a plurality of heating currents to the driving motor 60.

It should be appreciated that the various heating currents are set for the purpose of generating heat at the stationary state of the motor, so the various heating currents are set for the purpose of making the torque of the driving motor 60 zero, but the driving motor 60 may generate unstable small torque at various heating currents due to the implementation level of the device and the actual operating state of the motor, so long as the stationary state of the vehicle can be maintained, the actually output torque may be a small value close to zero, and may be zero in a preferred case.

The effective value of each phase current in the three phase currents of each heating current varies with the variation of the rotor angle of the driving motor 60. The electromagnetic torque generated by the motor under the first heating current or the third heating current is 0, the generated reluctance torque is not 0, the third heating current is unequal to the first heating current, and the first heating current or the third heating current can be changed according to the rotation angle theta of the motor rotor _e Motor temperature and current amplitude I _m And (5) determining.

Current amplitude I _m Can be directly indicated by a heating instruction or can be heated by the motor heating power P in the received heating instruction _m Is calculated by a formulaWherein R is ₀ For 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 the direct-axis current I _d And quadrature axis current I _q The value of the resultant vector current is calculated,

the motor temperature may be obtained by a temperature sensing device that may measure the ambient temperature of the motor, or the temperature of the heat carrier fluid of the motor thermal circuit, or the temperature of the motor stator windings, or the temperature within the heat conduction device, etc., as the application is not limited in this regard.

The rotor angle of the driving motor 60 can be detected by a sensor arranged at the shaft end of the motor rotor, and the rotor angle in the static state of the motor is equal to the rotation angle measured by the sensor, and the rotation angle ranges from 0 to 360 degrees.

The electromagnetic torque and the reluctance torque generated by the driving 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 unequal, the electromagnetic torque of the driving motor 60 is 0, 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, namely, the quadrature axis current is 0, and the reluctance torque is 0 at the moment.

As will be readily appreciated, when heating the power battery 20 by heat loss from the stator windings by supplying current to the windings of the drive motor 60, it is necessary to ensure that the motor does not produce torque during heating so that the vehicle can warm up 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)

wherein: t (T) _e For motor torque, n _p Is the pole pair number of the motor, psi _f For the flux linkage of the motor rotor, L _d Is a direct axis inductance (also called d axis inductance), L _q Is a quadrature axis inductance (also called q-axis electricityFeel), i _d I is a direct axis current (also called d axis current) _q Is the quadrature axis current (also known as q-axis current).

The electromagnetic torque in the 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 linkage, and the magnitude relation between the direct axis inductance and the quadrature axis inductance of the motor is also different. For a three-phase or multiphase permanent magnet synchronous motor, the rotor flux linkage is produced by permanent magnets, and the permanent magnets are mounted on the d-axis. Since the magnetic permeability of the permanent magnet is close to that of air, the equivalent air gap of the d-axis is thicker than that of the q-axis, so that the magnetic permeability of the d-axis magnetic circuit is smaller, and the d-axis inductance is smaller than that of the q-axis inductance, namely L _d <L _q The method comprises the steps of carrying out a first treatment on the surface of the Whereas for a three-phase or multi-phase electrically excited synchronous motor, the rotor flux linkage is produced by the field winding wound on the rotor. The d-axis equivalent air gap of the electrically excited synchronous motor is thinner than the q-axis, so that the magnetic conductance of the d-axis magnetic circuit is larger, and the d-axis inductance is larger than the q-axis inductance, namely L _d >L _q 。

Taking a three-phase permanent magnet synchronous motor as an example, L _d <L _q There is a significant saturation nonlinearity of the permanent magnet synchronous motor, so there is a specific i _d 、i _q Combined such that the torque T is synchronized ₁ And reluctance torque T ₂ Equal in size and opposite in sign. The method comprises the following steps:

ψ _f ＝-(L _d -L _q )·i _d (3)

i satisfying the relation of formula (3) _d 、i _q Which form several piecewise curves, may be referred to as zero torque curves.

Because of the characteristic of saturation nonlinearity of the synchronous motor, the inductance can change along with the change of the current, and i is at different temperatures _d 、i _q The relation of (2) will change and thus the temperature of the motor can be usedAnd determining a zero torque curve of the direct-axis current and the quadrature-axis current when the electromagnetic torque of the motor is 0.

It should be appreciated that the zero torque curve may also vary from one drive motor 60 to another, and thus the zero torque curve for the drive motor 60 may be determined by calibration or pre-calculation, or may be obtained by calculation, which is not limited in this regard by the present application.

According to the zero torque curve and the current amplitude, the magnitudes of the corresponding direct-axis current and quadrature-axis current can be determined. The current values to be input into the three-phase stator windings can be determined in combination with the rotor pitch angle of the drive motor 60.

The distribution of the zero torque curve is schematically shown in fig. 4 or 5, and the current amplitude is set as I _m To ensure zero output torque during motor heating, the current vector may be left at four operating points as shown in fig. 4 or 5. In fig. 4, the permanent magnet synchronous motor is shown, because the permeability of the permanent magnet is close to that of air, the equivalent air gap of the d axis is thicker than that of the q axis, so that the magnetic permeability of the d axis magnetic circuit is smaller, and the d axis inductance is smaller than that of the q axis inductance, namely L _d <L _q The method comprises the steps of carrying out a first treatment on the surface of the In fig. 5, which is an electrically excited synchronous machine, the rotor flux linkage is produced by field windings wound on the rotor. The d-axis equivalent air gap of the electrically excited synchronous motor is thinner than the q-axis, so that the magnetic conductance of the d-axis magnetic circuit is larger, and the d-axis inductance is larger than the q-axis inductance, namely L _d >L _q . Both fig. 4 and 5 comprise 4 operating points, with the difference that operating point 2 and operating point 4 are located in different quadrants.

Hereinafter, the permanent magnet synchronous motor L in FIG. 4 _d <L _q The description of the electrically excited synchronous machine in fig. 5 is similar to that of the case of the example, and will not be repeated.

For operating point 2, the current vector is located on the d-axis, i _d ＝I _m ，i _q =0, at which time the torque T is synchronized ₁ And reluctance torque T ₂ All are 0, and when the driving motor 60 is stopped at different angles, the effective values of the three-phase currents of U, V and W are as follows:

wherein I is _{u_rms} ，I _{v_rms} ，I _{w_rms} Respectively the effective values of the three-phase currents of U, V and W, theta _e The rotor position angle may be obtained by measuring a resolver mounted on the rotor shaft end of the driving motor 60. As shown in fig. 6, the effective values of the three-phase currents at different rotor angles are different from each other, and as can be seen from fig. 6 and table 1, the effective values of the currents of each phase are not equal at any angle, so that the three-phase power is also different.

TABLE 1 three-phase current effective values in electrical angle range of 0-180 DEG

For operating point 1, the current vector is located on the zero torque curve of the first quadrant, where i _d ＝I _m cosδ ₀ ，i _q ＝I _m sinδ ₀ Wherein delta ₀ Is the included angle delta between the current vector and the d axis ₀ ＝arctan(i _q /i _d ). At this time, the torque T is synchronized ₁ Positive reluctance torque T ₂ Negative, equal in absolute value, and zero, so the output torque is 0. When the rotor of the driving motor 60 is stopped at different angles, the effective values of the three-phase currents of U, V and W are as follows:

for operating point 3, the current vector is located on the zero torque curve in the fourth quadrant, where i _d ＝I _m cosδ ₀ ，i _q ＝-I _m sinδ ₀ At this time, the torque T is synchronized ₁ Negative reluctance torque T ₂ Positive, equal in absolute value, and zero, so the output torque is 0. When the rotor of the driving motor 60 is stopped at different angles, the effective values of the three-phase currents of U, V and W are as follows:

for operating point 4, the current vector is located on the d-axis, i _d ＝-I _m ，i _q =0, synchronous torque T ₁ And reluctance torque T ₂ All are 0, and obviously, the effective values of the three-phase currents U, V and W are the same as those of the working point 2, and can be seen in a formula (4).

Among the four working points, the three-phase windings of the working point 1, the working point 2, the working point 3 and the working point 4 have the same total heating power, but the current distribution ratio of each working point in the three-phase stator winding is different, namely the current ratios of the U phase, the V phase and the W phase of different working points are different, so that the respective heating power distribution of the U phase, the V phase and the W phase is different; the effective current values of the working point 2 and the working point 4 in the three-phase stator winding are the same, but the directions of the currents are not completely the same.

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

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

When the drive motor 60 is operated at the current corresponding to the operating point 1 or the operating point 3, the quadrature axis current of the drive motor 60 is not 0, and therefore the reluctance torque is not 0, the direct axis current corresponds to the quadrature axis current, the synchronous torque of the drive motor 60 is equal to the absolute value of the reluctance torque, and the sum of the synchronous torque and the reluctance torque is 0, so that the electromagnetic torque of the drive motor 60 is 0.

When the driving motor 60 is operated at the current corresponding to the operating point 2 or the operating point 4, the quadrature axis current of the driving motor 60 is 0, and the direct axis current is equal to the current amplitude, so that both the reluctance torque and the synchronous torque are 0, and the electromagnetic torque of the driving motor 60 is 0.

As shown in fig. 7, when the driving motor 60 is operated with only the second heating current or the fourth heating current, the relationship between the three-phase power and the current rotor stopping position is shown, and it can be seen that, at different rotor positions, the total power of the three phases is always 1.5, but the power of U, V, W phases may be 0 or the maximum value is 1.

Thus, in order to balance the three-phase heating power, the motor control may be performed using several possible combinations of heating currents, which are only examples, and other possible combinations are also within the scope of the present application.

Mode one

The various heating currents comprise three heating currents corresponding to the working point 1, the working point 2 and the working point 3, so that the three-phase stator winding of the driving motor 60 alternately switches and operates between the currents corresponding to the working point 1, the working point 2 and the working point 3.

Mode two

The various heating currents comprise two heating currents corresponding to the working point 1, the working point 2 and the working point 4, so that the three-phase stator winding of the driving motor 60 alternately switches and operates between the currents corresponding to the working point 1, the working point 2 and the working point 4.

Mode three

The plurality of heating currents comprise four heating currents corresponding to the working point 1, the working point 2, the working point 3 and the working point 4, so that the three-phase stator winding of the driving motor 60 alternately switches and operates between currents corresponding to the working point 1, the working point 2, the working point 3 and the working point 4.

Mode four

The various heating currents comprise two heating currents corresponding to the working point 3 and the working point 4, so that the three-phase stator winding of the driving motor 60 alternately switches and runs back and forth between the working point 3 and the current corresponding to the working point 3.

In the process that the motor controller 50 outputs various heating currents to the driving motor 60, the ratio of the heating power of any one heating current on any one phase winding of the driving motor 60 to the total heating power of any one heating current on the three phase winding of the driving motor 60 is less than 2/3.

In one possible implementation, in response to the temperature of the power battery 20 being below a threshold and/or a heating command, the motor controller 50 is configured to output a plurality of heating currents to the drive motor 60 such that the stator windings of the drive motor 60 generate heat.

It should be appreciated that the motor controller 50 may perform a flow of heating the battery 20 when the temperature of the battery 20 is low, and the inverter circuit 52 alternately outputs a plurality of heating currents to the three-phase stator windings of the driving motor 60. The flow may be executed when a heating instruction is received.

Illustratively, the heating command may be, for example, by a heating button, which the user presses, and the motor controller 50 may execute the flow immediately after receiving the heating command; the motor controller 50 may detect whether the temperature of the power battery 20 is lower than a threshold value after receiving the heating command, and execute the process if the temperature is lower than the threshold value.

In one possible implementation, in the process that the motor controller 50 is configured to sequentially 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 in the process that the motor controller 50 is configured to 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, a duration of the motor controller 50 for outputting each heating current varies with a variation of a rotor angle of the driving motor 60.

When the rotor position angle of the drive motor 60 is different, the ratio of the time period during which the inverter circuit 52 outputs each of the plurality of heating currents is different.

After each heating current is operated for a certain period of time, the heating current can be switched to another heating current, and the heating current is operated for a certain period of time. When the motor controller 50 outputs one of the plurality of heating currents and switches to another of the plurality of heating currents, the rotation angle θ of the rotor of the driving motor 60 may be changed according to _e And the heating current magnitude determines the run time corresponding to each heating current.

Taking the three working points of the working point 1, the working point 2 and the working point 3 in the first mode as an example, the heating current corresponding to each working point is not equal. In a fixed time period, the operating time duty ratios of the three working points are reasonably distributed, so that the total heating values of the three-phase windings in the time period are basically consistent. Thus, the balance of the respective average powers (the ratio of the total heating value of the respective windings in the period to the total time length of the period) of the three-phase windings is raised.

In one possible implementation, the operating time for each heating current may be preset or controlled by a control instruction. For example, each heating current may be switched to another heating current for another 10 seconds after a fixed operation for 10 seconds, and sequentially alternately operated.

In another possible implementation, the run time for each heating current may be based on the rotational angle θ of the rotor of the drive motor 60 _e And heating current magnitude determination.

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

In another possible implementation, the angle delta of the rotor and the current vector corresponding to the first heating current can be calculated ₀ Setting different time allocation duty ratio corresponding relations, and then according to theta _e And determining a specific time allocation duty ratio in the determined corresponding relation.

The angle delta of the current vector corresponding to the first heating current and the rotor can be determined by the three-phase current magnitude of the first heating current ₀ Thereby according to the angle delta between the current vector corresponding to the first heating current and the rotor ₀ Setting different time allocation duty ratio corresponding relations, and then according to theta _e And determining a specific time allocation duty ratio in the determined corresponding relation. When the motor is controlled by the combination of heating currents according to the first embodiment, for example, the motor is controlled according to θ _e And delta ₀ And determining the corresponding working time allocation duty ratio of the working point 1, the working point 2 and the working point 3. Due to accurate control of three-phase synchronous motorIn the actual process, for more convenient use, the driving motor 60 under special working conditions mostly adopts a table look-up method, because the requirement on the performance of the controller is minimum, and the calibration according to different driving motors is convenient.

The motor has a running time duty ratio of k at the working point 1, the working point 2 and the working point 3 respectively ₁ 、k ₂ 、k ₃ Wherein k is ₁ +k ₂ +k ₃ =1, the phase resistance of the motor winding is R _s The average power of the three-phase windings is:

when delta ₀ 15℃or less, then θ is queried according to a first lookup table, e.g. in Table 2 _e Corresponding time allocation duty cycle; when 15 DEG<δ ₀ Less than or equal to 45 degrees, then referring to θ in accordance with a second lookup table, e.g., table 3 (including Table 4) _e Corresponding time allocation duty cycle; when delta ₀ >45 deg., then, according to a third lookup table, e.g., lookup θ in Table 5 _e Corresponding time allocation duty cycles.

It should be appreciated that at the same temperature, there will be different amounts of delta for different drive motors 60 ₀ For delta ₀ Under the condition of less than or equal to 15 degrees, the three-phase power occupation of different working points is relatively close, but under the general condition, the delta corresponding to the synchronous motor ₀ Greater than 15 deg..

Table 2, first lookup table

TABLE 3 second lookup table

Motor angle theta _e	k ₁ 、k ₂ 、k ₃ Is allocated mode of (a)
		0°≤θ _e <15°	Mode two
15°≤θ _e <45°	Mode one
		45°≤θ _e <75°	Mode three
75°≤θ _e <105°	Mode two
		105°≤θ _e <135°	Mode one
135°≤θ _e <165°	Mode three
		165°≤θ _e <180°	Mode two

Table 4, second lookup table (attached table)

Table 5, third lookup table

Illustratively, when delta ₀ ＝30°，θ _e When=30°, the allocation pattern of the first usage pattern is found according to the second lookup table, and then found according to the second lookup table in the attached table:

thus, the driving motor 60 can be controlled to work according to k under different heating currents ₁ 、k ₂ 、k ₃ Is operated during a heating cycle.

As can be seen, when the rotor position angle of the driving motor 60 is different, the ratio of the time duration in which the motor controller 50 outputs each heating current is different.

Substituting the queried time duty ratio into the formula (7) can calculate the average power of the three-phase winding.

It should be understood that the division of angles and the setting of time ratios of the lookup table in the above implementation are merely examples, and may be set as needed in practical applications, and the specific angle setting manner and the time ratio setting manner in the table are not limited in the present application.

In one possible implementation, during the process of switching the current output by the inverter circuit 52 from one heating current to another, the current output by the inverter circuit 52 decreases and then increases, and the torque value of the driving motor 60 driven by the output current is smaller than the preset value.

It will be readily appreciated that in order to ensure that the motor does not produce torque during heating so that the vehicle can warm up the battery 20 in a stationary condition, the motor will still need to be changed along a zero torque curve during switching between various heating currents, during which the actual output torque may have small fluctuations, only to keep the vehicle stationary, the actual output torque may be a near zero value less than a preset value, the preset value being a small value near zero.

In one possible implementation, the current output by the motor controller 50 is decreased and then increased during the switching of the current output by the motor controller 50 from one heating current to another. During the switching process of the motor controller 50 outputting various heating currents, the current in the three-phase stator windings is changed along the switching curve, i.e. the zero torque curve described above, by decreasing from one heating current to 0 and then increasing from 0 to another heating current, so that the electromagnetic torque of the driving motor 60 is kept at 0.

As shown in fig. 8, when the current of the driving motor 60 is switched among the working point 1, the working point 2, the working point 3 and the working point 4, in order to ensure that the torque of the driving motor 60 is always zero in the switching process, the direct-axis current and the quadrature-axis current transformation track corresponding to the three-phase current must be always maintained on a zero torque curve. During switching from the first operating point to the second operating point, the heating current profile of the drive motor 60 must first return from the first operating point to the origin (i.e., zero both in the direct and quadrature axis currents) and then move to the second operating point.

Illustratively, when the working point 1 and the working point 2 are switched, the current magnitude changes in a manner that the current returns to the original point along the path 1 and then reaches the working point 2 along the path 2; when the working point 1 and the working point 3 are switched, the change mode of the current firstly returns to the original point along the path 1, and then reaches the working point 3 along the path 3; when the working point 1 and the working point 4 are switched, the change mode of the current firstly returns to the original point along the path 1, and then reaches the working point 4 along the path 4; when the working point 2 and the working point 3 are switched, the change mode of the current firstly returns to the original point along the path 2, and then reaches the working point 3 along the path 3; when the working point 2 and the working point 4 are switched, the change mode of the current firstly returns to the original point along the path 2, and then reaches the working point 4 along the path 4; when the working point 3 and the working point 4 are switched, the current change mode firstly returns to the original point along the path 3, and then reaches the working point 4 along the path 4.

The switching path in the above example is bi-directional and the reverse switching between the two operating points is also along the path.

According to the scheme of the application, each heating current is unequal, so that the running time duty ratio of a plurality of heating currents is reasonably distributed in a fixed time period, and the total heating value of each three-phase winding in the time period is basically consistent. Thus, the balance degree of the average power of each three-phase winding is improved.

The present application also provides a powertrain 30.

The powertrain 30 includes a drive motor 60 and the motor controller 50 described above, the drive motor 60 including a rotor and three-phase stator windings, each of the three-phase stator windings being configured to connect a midpoint of each of the three-phase legs of the inverter circuit 52 of the motor controller 50, the drive motor 60 receiving current from the power battery 20 from the inverter circuit 52.

The driving motor 60 is used for outputting zero torque under the driving of various heating currents, and the various heating currents are different in corresponding current distribution ratio, wherein the current distribution ratio is the proportion of the current of each phase of stator winding in the three-phase stator winding under each heating current.

In one possible implementation, the drive motor 60 is configured to output zero torque under the actuation of a plurality of heating currents in response to the temperature of the power cell 20 being below a threshold and/or a heating command.

In one possible implementation, the powertrain 30 further includes a heat transfer device 40, the heat transfer device 40 being configured to transfer heat generated by the electric machine to the power cell 20.

Fig. 9 is a schematic diagram of a motor control method according to the present application, as shown in fig. 9, the method includes the following steps:

it should be noted that, in the various embodiments of the present application, the sequence numbers of the respective processes, such as S110, S120, … …, etc., do not mean the sequence of execution, and the execution sequence of the respective processes should be determined by the functions and the internal logic thereof, and should not be construed as limiting the implementation process of the embodiments of the present application.

The control method is applied to the electric vehicle 10, and the electric vehicle 10 includes the power battery 20, the driving motor 60, and the motor controller 50 described above.

S110, the control motor controller 50 sequentially outputs a plurality of heating currents to the driving motor 60.

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 current, wherein: during a first period of time, controlling the motor controller 50 to output a first heating current; in a second period after the first period, controlling the motor controller 50 to output any one of the second heating current, the third heating current, and the fourth heating current; in a third period after the second period, controlling the motor controller 50 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.

It should be appreciated that various descriptions of heating currents may be made with reference to the foregoing.

This step may include the following steps, it being understood that the following steps may not necessarily be performed or may be performed in conjunction with inclusion in S110:

s120, obtaining a current amplitude I _m Motor temperature and motor rotor rotation angle θ _e 。

The current amplitude can be directly indicated by a heating instruction, or the motor heating power P in the received heating instruction can be used _m Is calculated by a formulaWherein R is ₀ For the phase resistance of the motor stator windings, the current magnitude is the maximum current value in the three-phase stator windings of the drive motor 60, and the current magnitude is the direct current I _d And quadrature axis current I _q Synthesized vector current value, ">

The motor temperature may be obtained by a temperature sensing device that may measure the ambient temperature of the motor, or the temperature of the heat carrier fluid of the motor thermal circuit, or the temperature of the stator windings of the drive motor 60, or the temperature within the heat conduction device, etc., as the application is not limited in this regard.

The rotor angle of the driving motor 60, i.e., the rotation angle, in a stationary state of the driving motor 60 can be detected by a sensor mounted at the rotor shaft end of the driving motor 60, and the rotation angle ranges from 0 to 360 °.

In one possible implementation, if the current rotor angle is greater than 180 °, 180 ° is subtracted, such that θ _e Is in the range of 0-180 degrees.

S130, determining various heating currents.

According to the acquired current amplitude I _m Motor temperature and drive motor 60 rotor rotation angle θ _e And calculating the current values corresponding to various heating currents.

Specific procedures can be described with reference to the foregoing calculation formulas (4), (5) and (6).

And S140, determining the corresponding operation time of each heating current.

The corresponding running time of each heating current can be based on the rotation angle theta of the rotor of the driving motor 60 _e And heating current magnitude determination.

The specific determination process can refer to the table look-up mode.

As shown in fig. 10, one possible specific procedure for the motor controller 50, the powertrain 30, and the electric vehicle 10 to execute the control method described above is as follows.

In step 1, the motor controller 50 in the powertrain 30 obtains a heating command, which may be sent by the vehicle controller 70, for instructing execution of the battery 20 heating process. When the temperature of the power battery 20 is below a threshold and/or the user presses a heat button (i.e., a heat demand command is issued), the vehicle is stationary, no start is required, and the temperature of the power battery 20 is below a predetermined value, the vehicle controller 70 will send the heat command.

In step 2, the vehicle controller 70 detects whether the vehicle state satisfies the parking heating condition, such as the battery pack temperature, the battery remaining capacity, whether the vehicle is stationary, whether the hand brake is on, and the like. If the heating condition is satisfied, battery heating is performed.

Step 3, the motor controller 50 in the powertrain 30 obtains the command value P of the motor heating power _m Thereby the heating current amplitude can be calculatedWherein R is _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 driving motor 60 in the stationary state, i.e., the rotor rotation angle θ _e . Rotor rotation angle theta _e The current rotor position of the drive motor 60 may be obtained by a sensor mounted to the shaft end of the motor rotor, or may be obtained by other means, which is not limited in this regard. The range of the rotation angle is 0-360 degrees, and if the current angle is larger than 180 degrees, 180 degrees can be subtracted, so that theta is achieved _e Always in the range of 0-180 degrees.

And 5, the motor controller 50 in the power assembly 30 acquires the motor temperature and queries a motor zero torque ammeter at the current temperature.

Step 6, the motor controller 50 in the powertrain 30 is based on the heating current amplitude I _m Obtaining the amplitude I from a zero-torque ammeter in the first quadrant of the motor _m Corresponding direct axis current i _dm Current of intersecting axis i _qm And calculating the included angle between the zero torque working point and the straight shaft: delta ₀ ＝arctan(i _qm /i _dm )，δ ₀ In the range of 0 to 90.

Step 7, motor controller 50 in powertrain 30 is controlled according to θ _e And delta ₀ Determining the run time of each heating current of a plurality of heating currents, such as the run time allocation duty ratio k of the motor at a direct-axis zero-torque operating point (i.e., operating point 1), a first-quadrant zero-torque operating point (i.e., operating point 2), and a fourth-quadrant zero-torque operating point (i.e., operating point 3) ₁ 、k ₂ 、k ₃ 。

Illustratively, when delta ₀ 15℃or less, then θ is queried according to a first lookup table, e.g. in Table 2 _e Corresponding time allocation duty cycle; when 15 DEG<δ ₀ Less than or equal to 45 degrees, then referring to θ in accordance with a second lookup table, e.g., table 3 (including Table 4) _e Corresponding time allocation duty cycle; when delta ₀ >45 deg., then, according to a third lookup table, e.g., lookup θ in Table 5 _e Corresponding time allocation duty cycles.

Step 8, the motor controller 50 in the power assembly 30 controls the on-off of the switching tube in the inverter circuit 52, so that the driving motor 60 circularly operates at 3 working points, and if a heating period is set as T, the operation time of the driving motor 60 at each working point is k respectively ₁ T、k ₂ T、k ₂ T. For example, if a heating period is 5 seconds, the driving motor 60 is operated stably at the operating point 1 for 5k ₁ Second, switching to the working point 2 to stably run for 5k ₂ Second, switching to the working point 3 to stably run for 5k ₃ Second, wherein the second is;

step 9, the motor controller 50 in the power assembly 30 detects the temperature of the power battery 20, and if the temperature of the power battery 20 does not reach the set temperature, the step 5 is returned. Since there is a temperature rise of the driving motor 60 during the heating process, the zero torque ammeter of the driving motor 60 will change, so in step 5, the zero torque ammeter needs to be re-acquired according to the current newly acquired temperature of the driving motor 60. If the temperature of the power battery 20 reaches the set temperature, the heating is stopped.

FIG. 11 shows a different working angle delta ₀ Lower three phase power versus rotor angle. As shown in fig. 11, through the implementation process provided by the application, the total power of three phases is still kept 1.5 unchanged at any position, but the maximum phase power is obviously reduced, the minimum phase power is obviously improved, and the balance degree of the three phases of power is improved. And, with delta ₀ The difference between the maximum phase power and the minimum phase power is reduced, and the three-phase power balance degree is improved; when delta ₀ When the three-phase power is more than or equal to 45 degrees, the three-phase power can be completely balanced at any rotor position.

In one possible implementation, during the process of outputting the first heating current by the motor controller 50, the ratio of the quadrature-axis current component and the direct-axis current component of the first heating current is the working angle, and when the working angle of the first heating current is smaller than 45 degrees, 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 outputting the three heating currents by the motor controller 50, the arctangent value of the ratio of the quadrature-axis current component and the direct-axis current component of the third heating current is an operating angle, and when the operating angle is smaller than 45 degrees, the variance of the effective values of the respective phase currents in the three-phase currents of the third heating current decreases with the increase of the operating angle.

In one possible implementation, during the process of outputting the first heating current by the motor controller 50, 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 currents of the first heating current is the same; in the process of outputting the third heating current by the motor controller 50, when the working angle of the third heating current is greater than 45 degrees, the effective values of all phase currents in the three phase currents of the third heating current are the same.

According to the scheme of the application, the driving motor 60 is switched back and forth between different heating currents in a zero torque state, and a certain phase winding with concentrated heating power is avoided, so that the heating power of multiple phases of the driving motor 60 is balanced, and the heating efficiency is improved.

Those of ordinary skill in the art will appreciate that the various illustrative elements and algorithm steps described in connection with the embodiments disclosed herein may be implemented as electronic hardware, or combinations of computer software and electronic hardware. Whether such functionality is implemented as hardware or software depends upon the particular application and design constraints imposed on the solution. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present application.

It will be clear to those skilled in the art that, for convenience and brevity of description, specific working procedures of the above-described systems, apparatuses and units may refer to corresponding procedures in the foregoing method embodiments, and are not repeated herein.

In the several embodiments provided by the present application, it should be understood that the disclosed systems, devices, and methods may be implemented in other manners. For example, the apparatus embodiments described above are merely illustrative, e.g., the division of the units is merely a logical function division, and there may be additional divisions when actually implemented, e.g., multiple units or components may be combined or integrated into another system, or some features may be omitted or not performed. Alternatively, the coupling or direct coupling or communication connection shown or discussed with each other may be an indirect coupling or communication connection via some interfaces, devices or units, which may be in electrical, mechanical or other form.

The functions, if implemented in the form of software functional units and sold or used as a stand-alone product, may be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present application may be embodied essentially or in a part contributing to the prior art or in a part of the technical solution, in the form of a software product stored in a storage medium, comprising several instructions for causing a computer device (which may be a personal computer, a server, a network device, etc.) to perform all or part of the steps of the method according to the embodiments of the present application. And the aforementioned storage medium includes: a U-disk, a removable hard disk, a Read-Only Memory (ROM), a random access Memory (Random Access Memory, RAM), a magnetic disk, or an optical disk, or other various media capable of storing program codes.

The foregoing is merely illustrative of the present application, and the present application is not limited thereto, and any person skilled in the art will readily recognize that variations or substitutions are within the scope of the present application. Therefore, the protection scope of the present application shall be subject to the protection scope of the claims.

Claims

1. A motor controller for outputting a driving current for controlling a torque output by a driving motor to be greater than zero and outputting a plurality of heating currents, each of which is for controlling the torque output by the driving motor to be zero, to a driving motor of an electric automobile, each of which includes three-phase currents, wherein:

any two parameters of the heating currents are different, wherein the parameters comprise the ratio of the effective values of the phase currents in the three-phase currents of each heating current.

2. The motor controller of claim 1, wherein the motor controller is configured to sequentially 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 current component of the first heating current and the quadrature current component of the third heating current are not zero, and the quadrature current component of the second heating current and the quadrature current component of the fourth heating current are zero.

3. The motor controller of 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, and the direct-axis current component of the fourth heating current are all non-zero.

4. A motor controller according to claim 3, wherein, in the process of outputting the first heating current by the motor controller, the ratio of the quadrature-axis current component and the direct-axis current component of the first heating current is an operating angle, and when the operating angle of the first heating current is smaller than 45 degrees, the variance of the effective values of the respective phase currents in the three-phase currents of the first heating current decreases with an increase in the operating angle of the first heating current;

and in the process of outputting the third heating current by the motor controller, the arctangent value of the ratio of the quadrature axis current component and the direct axis current component of the third heating current is a working angle, and when the working angle is smaller than 45 degrees, the variance of the effective value of each phase current in the three-phase current of the third heating current is reduced along with the increase of the working angle.

5. The motor controller according to claim 4, wherein, in the process of outputting the first heating current by the motor controller, when the working angle of the first heating current is greater than 45 degrees, the effective values of all phase currents in the three-phase currents of the first heating current are the same;

And in the process of outputting the third heating current by the motor controller, when the working angle of the third heating current is larger than 45 degrees, the effective values of all phase currents in the three-phase currents of the third heating current are the same.

6. A motor controller according to any one of claims 1 to 5, wherein the effective value of each phase current in the three phase currents of each heating current varies with the variation of the rotor angle of the drive motor.

7. The motor controller according to any one of claims 2 to 5, wherein in the process that the motor controller is configured to sequentially output first heating current and then output at least one of second heating current, third heating current and fourth heating current, or in the process that the motor controller is configured to sequentially output at least one of second heating current, third heating current and fourth heating current and then output first heating current, the time length for outputting each of the heating currents varies with a variation in a rotor angle of the driving motor.

8. The motor controller according to any one of claims 1 to 5, wherein a ratio of heating power of any one heating current on any one phase winding of the drive motor to total heating power of any one heating current on three phase windings of the drive motor is less than 2/3 in outputting the plurality of heating currents to the drive motor by the motor controller.

9. A motor controller according to any one of claims 1-5, wherein during switching of the current output by the motor controller from one of the heating currents to the other heating current, the current output by the motor controller decreases and then increases and the motor controller is adapted to control the torque output by the drive motor to be always smaller than a torque preset value.

10. The motor controller according to any one of claims 1-9, wherein the motor controller is configured to output the plurality of heating currents to the drive motor in response to a temperature of the power battery being below a threshold value and/or a heating command.

11. A powertrain comprising a drive motor and a motor controller for outputting at least one heating current to the drive motor to control torque of the drive motor to zero, wherein:

the quadrature-axis current component and the direct-axis current component of the at least one heating current are non-zero.

12. The powertrain of claim 11, wherein the motor controller is configured to output the at least one heating current in response to a temperature of the power cell being below a threshold and/or a heating command.

13. The powertrain of any of claims 11-12, wherein during output of the at least one heating current by the motor controller, an arctangent of a ratio of a quadrature-axis current component to a direct-axis current component of each of the heating currents is an operating angle, and a variance of an effective value of each phase current in three-phase currents of the heating currents decreases as the operating angle increases when the operating angle is less than 45 degrees.

14. A control method for a motor controller, the control method comprising:

controlling the motor controller to sequentially output a plurality of heating currents to the driving motor, wherein each heating current is used for controlling the torque output by the driving motor to be zero, and each heating current comprises three-phase current, and the three-phase current comprises the following components:

controlling the motor controller to output a first heating current in a first time period;

controlling the motor controller to output any one of a second heating current, a third heating current and a fourth heating current in a second period of time after the first period of time;

controlling the motor controller to output any one of a first heating current, a second heating current, a third heating current and a fourth heating current in a third period after the second period;

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.

15. The control method according to claim 14, characterized in that the control method includes:

and in the process of switching the current output by the motor controller from one heating current to the other heating current, controlling the current output by the motor controller to be firstly reduced and then increased, and controlling the motor controller to enable the torque output by the driving motor to be always smaller than a torque preset value.