CN108258971B - Motor control method and device, controller and automobile - Google Patents

Motor control method and device, controller and automobile Download PDF

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Publication number
CN108258971B
CN108258971B CN201810027185.3A CN201810027185A CN108258971B CN 108258971 B CN108258971 B CN 108258971B CN 201810027185 A CN201810027185 A CN 201810027185A CN 108258971 B CN108258971 B CN 108258971B
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motor
voltage
control
peak
power
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CN108258971A (en
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程洲
黄静
关龙华
白龙
田斌
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Beijing Electric Vehicle Co Ltd
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Beijing Electric Vehicle Co Ltd
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    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
    • H02P23/00—Arrangements or methods for the control of AC motors characterised by a control method other than vector control
    • H02P23/04—Arrangements or methods for the control of AC motors characterised by a control method other than vector control specially adapted for damping motor oscillations, e.g. for reducing hunting
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60L—PROPULSION OF ELECTRICALLY-PROPELLED VEHICLES; SUPPLYING ELECTRIC POWER FOR AUXILIARY EQUIPMENT OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRODYNAMIC BRAKE SYSTEMS FOR VEHICLES IN GENERAL; MAGNETIC SUSPENSION OR LEVITATION FOR VEHICLES; MONITORING OPERATING VARIABLES OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRIC SAFETY DEVICES FOR ELECTRICALLY-PROPELLED VEHICLES
    • B60L15/00—Methods, circuits, or devices for controlling the traction-motor speed of electrically-propelled vehicles
    • B60L15/20—Methods, circuits, or devices for controlling the traction-motor speed of electrically-propelled vehicles for control of the vehicle or its driving motor to achieve a desired performance, e.g. speed, torque, programmed variation of speed
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
    • H02P27/00—Arrangements or methods for the control of AC motors characterised by the kind of supply voltage
    • H02P27/04—Arrangements or methods for the control of AC motors characterised by the kind of supply voltage using variable-frequency supply voltage, e.g. inverter or converter supply voltage
    • H02P27/06—Arrangements or methods for the control of AC motors characterised by the kind of supply voltage using variable-frequency supply voltage, e.g. inverter or converter supply voltage using dc to ac converters or inverters
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
    • H02P2205/00—Indexing scheme relating to controlling arrangements characterised by the control loops
    • H02P2205/03—Power loop, i.e. comparison of the motor power with a power reference
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
    • Y02T10/00—Road transport of goods or passengers
    • Y02T10/60—Other road transportation technologies with climate change mitigation effect
    • Y02T10/64—Electric machine technologies in electromobility
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
    • Y02T10/00—Road transport of goods or passengers
    • Y02T10/60—Other road transportation technologies with climate change mitigation effect
    • Y02T10/72—Electric energy management in electromobility

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Transportation (AREA)
  • Mechanical Engineering (AREA)
  • Electric Propulsion And Braking For Vehicles (AREA)
  • Control Of Ac Motors In General (AREA)

Abstract

The invention provides a motor control method, a motor control device, a controller and an automobile, wherein the method is applied to a motor controller MCU of the electric automobile, and the method comprises the following steps: acquiring a first direct current bus voltage of a battery pack of the electric automobile in a current control period of the MCU; determining a first control voltage of a motor of the electric automobile according to the first direct current bus voltage; and according to the first control voltage, when the motor is currently in an under-voltage drop power working condition, controlling the motor to work at constant power or constant torque. The invention solves the problem of motor output torque fluctuation caused by the voltage fluctuation of the direct current bus on the electric automobile.

Description

Motor control method and device, controller and automobile
Technical Field
The invention relates to the technical field of automobiles, in particular to a motor control method, a motor control device, a motor control controller and an automobile.
Background
With the rapid development of automobile technology, new energy automobiles mainly comprising electric automobiles have gradually opened the market and enter people's lives. In the running process of the electric automobile, the output power is usually influenced by the direct-current bus voltage, for example, when the direct-current bus voltage comprises 3 critical points, Va, Vb and Vc, and Va > Vb > Vc; between Va and Vb, the motor can run at full power; when the voltage of the direct current bus is reduced to be lower than Vb, the motor needs to be operated with reduced power; when the voltage of the direct current bus is reduced to Vc, the motor runs at zero power. When the vehicle runs, when the voltage of the direct-current bus is reduced to be between Vb and Vc, the voltage fluctuates, and if the power control is not good due to under-voltage drop, the output torque of the motor also fluctuates, so that the riding comfort of the vehicle is influenced.
In order to solve the above problem, a scheme may adopt a continuous linear power reduction strategy, in which a power reduction coefficient Kp is set, the dc bus voltage is Vx, when the dc bus voltage Vx is between Vc and Vb, the power reduction coefficient Kp is (Vx-Vc)/(Vb-Vc), and the maximum limit power is Kp multiplied by the power of the motor during full-power operation.
Alternatively, the motor may also be made to execute a step-down power strategy, such as setting another critical point Vd between Vb and Vc: 1/2 when dividing the DC bus voltage between Vd and Vb, the maximum limit power of the motor is full power operation; when the voltage of the direct current bus is between Vc and Vd, 1/4 when the maximum power of the motor is limited to full power operation; when the voltage of the direct current bus is reduced to be lower than Vc, the motor is enabled to run at zero power; although the scheme can keep the maximum limit power of the motor in each voltage range (Vd to Vb, Vc to Vd) constant and prevent the torque output of the motor from shaking, when the direct current bus voltage fluctuates around Vb, Vc and Vd, the maximum limit power of the motor still generates large fluctuation, and the torque output of the motor also generates shaking.
Therefore, how to solve the problem of motor output torque fluctuation caused by the voltage fluctuation of the direct current bus on the electric automobile becomes a problem to be solved in the field of motors.
Disclosure of Invention
The invention provides a motor control method, a motor control device, a motor controller and an automobile, and aims to solve the problem of motor output torque fluctuation caused by voltage fluctuation of a direct-current bus on the electric automobile.
In order to achieve the above object, an embodiment of the present invention provides a motor control method applied to a motor controller MCU of an electric vehicle, the method including:
acquiring a first direct current bus voltage of a battery pack of the electric automobile in a current control period of the MCU;
determining a first control voltage of a motor of the electric automobile according to the first direct current bus voltage;
and according to the first control voltage, when the motor is currently in an under-voltage drop power working condition, controlling the motor to work at constant power or constant torque.
Optionally, the step of determining a first control voltage of a motor of the electric vehicle according to the first dc bus voltage includes:
when a second direct current bus voltage of a previous control period before the current control period is recorded in the MCU, determining a first control voltage of a motor of the electric automobile according to the first direct current bus voltage and the second direct current bus voltage; or
And when the second direct current bus voltage of the previous control period before the current control period is not recorded in the MCU, determining the first direct current bus voltage as the first control voltage of the motor of the electric automobile.
Optionally, the step of determining a first control voltage of a motor of the electric vehicle according to the first dc bus voltage and the second dc bus voltage includes:
if the first direct current bus voltage is larger than the second direct current bus voltage, obtaining a first control voltage of a motor of the electric automobile according to a preset algorithm; otherwise, the first direct current bus voltage is used as the first control voltage.
Optionally, the step of obtaining a first control voltage of a motor of the electric vehicle according to a preset algorithm includes:
by the formula: obtaining a first control voltage of a motor of the electric vehicle by (1+ Kn) × Va2 Va 1;
wherein Va1 is the first control voltage, and Va2 is the second control voltage of the motor of the electric vehicle in the last control cycle;
kn is a preset voltage rise coefficient.
Optionally, the step of controlling the motor to operate at a constant power or a constant torque comprises:
determining the peak power of the motor according to the first control voltage;
acquiring a preset peak torque of the motor;
determining a peak rotating speed according to the peak power and the peak torque;
when the current rotating speed of the motor is equal to or lower than the peak rotating speed, controlling the motor to work at the peak torque constant torque; or when the current rotating speed of the motor is higher than the peak rotating speed, controlling the motor to work at the peak power constant power.
Optionally, the step of determining the peak power of the motor according to the first control voltage includes:
determining a peak power of the motor according to the following formula:
Pmax＝Pm(V3-Vc)/(Vb-Vc)；
wherein Pmax is the peak power, Pm is a preset maximum power of the motor, V3 is the first control voltage, Vb is a preset reference voltage, and Vc is a preset zero-power operating voltage value of the motor.
Optionally, the step of determining a peak rotational speed according to the peak power and the peak torque includes:
determining a peak rotational speed according to the following formula:
Nmax＝9550*Pmax/Tmax；
where Nmax is the peak rotational speed and Tmax is the peak torque.
On the other hand, the embodiment of the invention also provides a motor control device, which is applied to a motor controller MCU of an electric automobile, and the device comprises:
the acquisition module is used for acquiring a first direct current bus voltage of a battery pack of the electric automobile in a current control period of the MCU;
the determining module is used for determining a first control voltage of a motor of the electric automobile according to the first direct current bus voltage;
and the control module is used for controlling the motor to work at constant power or constant torque according to the first control voltage when the motor is currently in the under-voltage and under-voltage power-drop working condition.
Optionally, the determining module includes:
the first determining submodule is used for determining a first control voltage of a motor of the electric automobile according to the first direct-current bus voltage and a second direct-current bus voltage when the second direct-current bus voltage of a previous control period before the current control period is recorded in the MCU; or
And the second determining submodule is used for determining the first direct-current bus voltage as the first control voltage of the motor of the electric automobile when the second direct-current bus voltage of the previous control period before the current control period is not recorded in the MCU.
Optionally, the first determining sub-module includes:
the voltage determining unit is used for obtaining a first control voltage of a motor of the electric automobile according to a preset algorithm if the first direct current bus voltage is greater than the second direct current bus voltage; otherwise, the first direct current bus voltage is used as the first control voltage.
Optionally, the voltage determination unit is configured to:
by the formula: obtaining a first control voltage of a motor of the electric vehicle by (1+ Kn) × Va2 Va 1;
wherein Va1 is the first control voltage, and Va2 is the second control voltage of the motor of the electric vehicle in the last control cycle;
kn is a preset voltage rise coefficient.
Optionally, the control module comprises:
the power determination submodule is used for determining the peak power of the motor according to the first control voltage;
the torque acquisition submodule is used for acquiring a preset peak torque of the motor;
the rotating speed determining submodule is used for determining the peak rotating speed according to the peak power and the peak torque;
the control submodule is used for controlling the motor to work at the peak torque constant torque when the current rotating speed of the motor is equal to or lower than the peak rotating speed; or when the current rotating speed of the motor is higher than the peak rotating speed, controlling the motor to work at the peak power constant power.
Optionally, the power determination sub-module is configured to:
determining a peak power of the motor according to the following formula:
Pmax＝Pm(V3-Vc)/(Vb-Vc)；
wherein Pmax is the peak power, Pm is a preset maximum power of the motor, V3 is the first control voltage, Vb is a preset reference voltage, and Vc is a preset zero-power operating voltage value of the motor.
Optionally, the rotation speed determination submodule is configured to:
determining a peak rotational speed according to the following formula:
Nmax＝9550*Pmax/Tmax；
where Nmax is the peak rotational speed and Tmax is the peak torque.
In another aspect, an embodiment of the present invention further provides an automobile, including the above motor control device.
In yet another aspect, an embodiment of the present invention further provides a controller, which includes a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor reads the program in the memory and executes the steps in the motor control method.
In still another aspect, embodiments of the present invention further provide an automobile, including the above controller.
The scheme of the invention at least comprises the following beneficial effects:
in the embodiment of the invention, when the vehicle is in the under-voltage power-down operation condition, the control voltage of the motor is determined according to the DC bus voltage, the peak power and the peak torque are determined according to the control voltage and the first control voltage, and the motor is controlled to work at the constant power of the peak power or work at the constant torque of the peak torque.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings needed to be used in the description of the embodiments of the present invention will be briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art that other drawings can be obtained according to these drawings without inventive labor.
FIG. 1 is a flow chart illustrating steps of a motor control method provided by an embodiment of the present invention;
FIG. 2 is a schematic diagram of an electric vehicle driving system according to an embodiment of the present invention;
FIG. 3 is a flow chart illustrating steps of a specific example provided by an embodiment of the present invention;
fig. 4 is a block diagram of a motor control device according to an embodiment of the present invention.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, not all, embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Referring to fig. 1, an embodiment of the present invention provides a motor control method applied to a motor controller MCU of an electric vehicle, including:
step 101, obtaining a first direct current bus voltage of a battery pack of the electric automobile in a current control period of the MCU.
Referring to fig. 2, fig. 2 is a schematic diagram illustrating an architecture of a driving system of an electric vehicle; the voltage (the voltage between DC + and DC-) at two ends of the battery pack DC is the DC bus voltage; the battery pack is used as an energy source of the electric automobile and provides direct current for a Motor Control Unit (MCU).
The MCU is used as a driving control unit of the motor and is used for converting direct current provided by the battery pack into three-phase alternating current to be output to the motor so as to drive the motor to rotate.
The motor is used for converting electric energy into mechanical energy, generating driving torque and driving the vehicle to run.
Wherein the control period is the control period of the MCU. In each control period, the MCU collects the dc bus voltage, hereinafter the first dc bus voltage is denoted by V1.
And 102, determining a first control voltage of a motor of the electric automobile according to the first direct current bus voltage.
Wherein a first control voltage of the motor is determined according to V1, hereinafter denoted as Va1, which in the embodiment of the invention is used as an intermediate variable for determining the peak power as well as the peak torque.
103, controlling the motor to work at constant power or constant torque when the motor is currently in the under-voltage and under-voltage power-drop working condition according to the first control voltage.
Specifically, when the motor is currently in an under-voltage power-down (or under-voltage power-limiting) working condition, the peak power and the peak torque are determined according to the first control voltage, and the motor is controlled to work at the peak power constant power or at the peak torque constant torque.
Optionally, in an embodiment of the present invention, step 102 includes:
the method comprises the steps that firstly, when a second direct current bus voltage of a previous control period before a current control period is recorded in the MCU, a first control voltage of a motor of the electric automobile is determined according to the first direct current bus voltage and the second direct current bus voltage; or
And secondly, when the second direct current bus voltage of the previous control period before the current control period is not recorded in the MCU, determining the first direct current bus voltage as the first control voltage of the motor of the electric automobile.
In the first step, if a second direct current bus voltage (hereinafter, denoted by V2) of a previous control period before a current control period is recorded in the MCU, one of the first and second direct current bus voltages is determined as a first control voltage of the motor of the electric vehicle according to a value between the first and second direct current bus voltages.
In the second step, if the second dc bus voltage of the previous control period before the current control period is not recorded in the MCU, the first dc bus voltage is the first control voltage of the motor.
Optionally, in the first step, the step of determining a first control voltage of a motor of the electric vehicle according to the first dc bus voltage and the second dc bus voltage includes:
if the first direct current bus voltage is larger than the second direct current bus voltage, obtaining a first control voltage of a motor of the electric automobile according to a preset algorithm; otherwise, the first direct current bus voltage is used as the first control voltage.
In this step, if V1 is greater than V2, the first control voltage is determined according to a preset algorithm, so that the first control voltage is slowly increased relative to the control voltage in the previous period; if V1 is less than or equal to V2, then the first control voltage is assigned to be equal to the first DC bus voltage V1.
Further, the step of obtaining the first control voltage of the motor of the electric vehicle according to a preset algorithm includes:
by the formula: obtaining a first control voltage of a motor of the electric vehicle by (1+ Kn) × Va2 Va 1;
wherein Va1 is the first control voltage, and Va2 is the second control voltage of the motor of the electric vehicle in the last control cycle;
kn is a preset voltage rise coefficient, and optionally, the value range of Kn is between 0.01 and 0.02, for example, 0.015;
when V1 is greater than V2, the first control voltage Va1 is increased by a factor Kn with respect to the second control voltage Va2 of the motor of the electric vehicle of the previous control cycle, and the value of Kn is small, so that the control voltage is slowly raised at a fixed rising speed, avoiding causing output torque fluctuation.
In the embodiment of the invention, when the vehicle is in an under-voltage-drop power operation condition, a parameter voltage rise coefficient Kn of control voltage is additionally added, and when the voltage of the direct current bus rises, the control voltage slowly rises at a fixed speed by taking the voltage rise coefficient Kn as a reference edge.
Optionally, in step 103, the step of controlling the motor to operate at a constant power or a constant torque includes:
determining the peak power of the motor according to the first control voltage;
acquiring a preset peak torque of the motor;
determining a peak rotating speed according to the peak power and the peak torque;
when the current rotating speed of the motor is equal to or lower than the peak rotating speed, controlling the motor to work at the peak torque constant torque; or when the current rotating speed of the motor is higher than the peak rotating speed, controlling the motor to work at the peak power constant power.
In this step, the maximum rotation speed point at which the peak torque can be output is calculated according to the limit value of the power, with the numerical value of the control voltage as a reference when the peak power and the peak torque are calculated. When the current vehicle speed is equal to or lower than the peak value, the torque amplitude limit maintains the maximum available torque, and the motor is controlled to work at the peak value torque constant torque, so that the maximum torque can be still output within the capacity range even if the battery voltage is lower under the conditions of low speed, slope stopping and the like.
When the current vehicle speed is higher than the peak value rotating speed, the motor is controlled to work at the peak value power constant power, the output torque is limited, and the output torque fluctuation caused by high vehicle speed is avoided.
Optionally, in an embodiment of the present invention, the step of determining the peak power of the motor according to the first control voltage includes:
determining a peak power of the motor according to the following formula:
Pmax＝Pm(V3-Vc)/(Vb-Vc)；
wherein Pmax is the peak power, Pm is a preset maximum power of the motor, V3 is the first control voltage, Vb is a preset reference voltage, and Vc is a preset zero-power operating voltage value of the motor.
Where V3 is Va1 as before, both of which represent the first control voltage.
The preset reference voltage is a preset value, is predetermined according to the running characteristics of the motor, is usually a critical voltage for determining that the current motor is in an undervoltage state, and indicates that the vehicle enters a low-dropout power working condition currently when the voltage of the direct-current bus is lower than the preset reference voltage.
And determining the peak power according to the product of the relation among the first control voltage, the preset reference voltage and the zero-power operation voltage value and the preset maximum power of the motor.
Optionally, in an embodiment of the present invention, the step of determining a peak rotation speed according to the peak power and the peak torque includes:
determining a peak rotational speed according to the following formula:
Nmax＝9550*Pmax/Tmax；
where Nmax is the peak rotational speed and Tmax is the peak torque.
In this step, the peak rotational speed is determined from the peak power and the peak torque.
Optionally, in an embodiment of the present invention, in step 103, further including: determining that the motor is currently in an under-voltage power-down working condition; the method specifically comprises the following steps:
when Va1 is (1+ Kn) multiplied by Va2, namely the first control voltage is determined according to the second control voltage, and the first direct current bus voltage and/or the first control voltage are/is smaller than or equal to a preset reference voltage, determining that the motor is currently in an under-voltage power-reduction working condition; or
And when the first control voltage is the first direct current bus voltage and the first direct current bus voltage is smaller than the first preset reference voltage, determining that the motor is currently in an under-voltage drop power working condition.
That is, when the first control voltage is determined according to the second control voltage, only when the first dc bus voltage and the first control voltage are both greater than the preset reference voltage, it may be determined that the first dc bus voltage is not currently under the condition of the under-voltage drop power, otherwise, both the first dc bus voltage and the first control voltage are under the condition of the under-voltage drop power.
And when the first control voltage is the first direct current bus voltage, if the first direct current bus voltage is smaller than the first preset reference voltage, determining that the motor is currently in an under-voltage drop power working condition.
In the embodiment of the invention, when the vehicle is in the under-voltage power-down operation condition, the control voltage of the motor is determined according to the direct-current bus voltage, the peak power and the peak torque are determined according to the control voltage, and the motor is controlled to work at the peak power constant power or work at the peak torque constant torque. According to the invention, by additionally adding a voltage rising coefficient Kn, when the voltage of the direct current bus rises, the voltage is controlled to rise along a fixed and slower speed; when the peak power and the peak torque are calculated, the numerical value of the control voltage is used as a reference, on one hand, the control voltage is not higher than the direct current bus voltage, so that the system can output a power amplitude limit value obtained based on the control voltage, and on the other hand, the fluctuation of the peak power and the peak torque is reduced. The invention solves the problem of motor output torque fluctuation caused by the voltage fluctuation of the direct current bus on the electric automobile.
As a specific example, referring to fig. 3, the motor control method shown in fig. 3 mainly includes the following steps:
step 301, collecting the direct current bus voltage V2 of the current control period.
Step 302, determining whether V2 is less than a preset reference voltage Vb: if so, go to step 303, otherwise, go to step 304, exit the brownout power control process.
The MCU collects the direct current bus voltage in real time, and judges whether the motor enters the under-voltage drop power working condition or not according to the direct current bus voltage and the preset reference voltage, namely when V1 is smaller than Vb, the motor enters the under-voltage drop power working condition.
Step 303, assigning the second control voltage Va2 ═ V2;
in step 305, the current peak power Pmax is determined according to the second control voltage Va 2.
Wherein, the assigned control voltage Va2 is equal to the direct current bus voltage V2, and the current peak power Pmax of the motor is determined according to Va 2.
And step 306, determining the peak rotating speed Nmax according to the peak power Pmax and the peak torque Tmax.
Step 307, when the rotating speed of the motor is equal to or lower than the peak rotating speed, controlling the motor to work at the peak torque constant torque; or when the rotating speed is higher than the peak rotating speed, controlling the motor to work at the peak power constant power.
In order to ensure that the motor can still output the maximum torque Tmax (maximum output torque during full power running) within the capacity range even under the working condition of under-voltage power reduction under the conditions of low speed, slope stopping and the like, the maximum rotating speed point of the output peak torque can be confirmed according to the Pmax and the peak torque Tmax; when the rotating speed of the motor is below Nmax, the constant torque (Tmax) of the motor is output, and when the rotating speed of the motor is above Nmax, the constant power (Pmax) of the motor is output.
Step 308, continuing to acquire the direct-current bus voltage V1 in the current control period;
step 309, determining whether V1 is greater than the dc bus voltage V2 of the previous control cycle: if yes, go to step 310; otherwise, step 311 is executed to assign the current first control voltage Va1 ═ V1, and step 305 is returned to.
After a new control period is started, the MCU continues to acquire the current dc bus voltage, which is recorded as V1, and determines whether the current dc bus voltage V1 is greater than the dc bus voltage V2 in the previous period, if V1 is less than or equal to V2, the current first control voltage Va1 is assigned as V1, and the calculation of Pmax and Tmax is completed; if V1 is greater than V2, go to step 310.
At step 310, the current first control voltage Va1 is assigned (1+ Kn) × Va 2.
Step 312, determining whether Va1 is greater than a preset reference voltage Vb, and the dc bus voltage V1 is greater than the preset reference voltage Vb:
if yes, go to step 304, exit the undervoltage control process; otherwise, return to step 305.
The current period control voltage is assigned, Kn is a preset control voltage rising coefficient, in order to prevent the control voltage from rising too fast, the Kn value can be selected as small as possible, and the value range is between 0.01 and 0.02; and then judging whether the current direct current bus voltage V1 and the current control voltage Va1 are simultaneously greater than Vb, if so, exiting the under-voltage drop power control, otherwise, returning to the step 305, and finishing the calculation of the Pmax and the Tmax.
In the above example of the present invention, a voltage increase coefficient Kn is additionally added under the under-voltage drop power operation condition, and when the under-voltage drop power operation condition is entered, and when the dc bus voltage is lower than the current control voltage, the updated control voltage is equal to the dc bus voltage; when the dc bus voltage rises, the control voltage rises at a fixed, slower rate. When the peak power and the peak torque are calculated, the value of the control voltage is used as a reference, on one hand, the control voltage is not higher than the direct current bus voltage, and the peak torque and the peak power are obtained based on the control voltage, so that the system can output the power amplitude limit value obtained based on the control voltage, and on the other hand, the fluctuation of the peak power and the peak torque is reduced.
Referring to fig. 4, an embodiment of the present invention further provides a motor control device, which is applied to a motor controller MCU of an electric vehicle, where the motor control device includes:
an obtaining module 401, configured to obtain a first dc bus voltage of a battery pack of the electric vehicle in a current control period of the MCU.
Referring to fig. 2, fig. 2 is a schematic diagram illustrating an architecture of a driving system of an electric vehicle; the voltage (the voltage between DC + and DC-) at two ends of the battery pack DC is the DC bus voltage; the battery pack is used as an energy source of the electric automobile and provides direct current for a Motor Control Unit (MCU).
The MCU is used as a driving control unit of the motor and is used for converting direct current provided by the battery pack into three-phase alternating current to be output to the motor so as to drive the motor to rotate.
The motor is used for converting electric energy into mechanical energy, generating driving torque and driving the vehicle to run.
Wherein the control period is the control period of the MCU. In each control period, the MCU collects the dc bus voltage, hereinafter the first dc bus voltage is denoted by V1.
A determining module 402, configured to determine a first control voltage of a motor of the electric vehicle according to the first dc bus voltage.
Wherein a first control voltage of the motor is determined according to V1, hereinafter denoted as Va1, which in the embodiment of the invention is used as an intermediate variable for determining the peak power as well as the peak torque.
And the control module 403 is configured to control the motor to operate at a constant power or a constant torque according to the first control voltage when the motor is currently in the under-voltage and under-voltage power-drop working condition.
Specifically, when the motor is currently in an under-voltage power-down (or under-voltage power-limiting) working condition, the peak power and the peak torque are determined according to the first control voltage, and the motor is controlled to work at the peak power constant power or at the peak torque constant torque.
Optionally, the determining module 402 includes:
the first determining submodule is used for determining a first control voltage of a motor of the electric automobile according to the first direct-current bus voltage and a second direct-current bus voltage when the second direct-current bus voltage of a previous control period before the current control period is recorded in the MCU; or
And the second determining submodule is used for determining the first direct-current bus voltage as the first control voltage of the motor of the electric automobile when the second direct-current bus voltage of the previous control period before the current control period is not recorded in the MCU.
Optionally, the first determining sub-module includes:
the voltage determining unit is used for obtaining a first control voltage of a motor of the electric automobile according to a preset algorithm if the first direct current bus voltage is greater than the second direct current bus voltage; otherwise, the first direct current bus voltage is used as the first control voltage.
Optionally, the voltage determination unit is configured to:
by the formula: obtaining a first control voltage of a motor of the electric vehicle by (1+ Kn) × Va2 Va 1;
wherein Va1 is the first control voltage, and Va2 is the second control voltage of the motor of the electric vehicle in the last control cycle;
kn is a preset voltage rise coefficient.
Optionally, the control module 403 includes:
the power determination submodule is used for determining the peak power of the motor according to the first control voltage;
the torque acquisition submodule is used for acquiring a preset peak torque of the motor;
the rotating speed determining submodule is used for determining the peak rotating speed according to the peak power and the peak torque;
the control submodule is used for controlling the motor to work at the peak torque constant torque when the current rotating speed of the motor is equal to or lower than the peak rotating speed; or when the current rotating speed of the motor is higher than the peak rotating speed, controlling the motor to work at the peak power constant power.
Optionally, the power determination sub-module is configured to:
determining a peak power of the motor according to the following formula:
Pmax＝Pm(V3-Vc)/(Vb-Vc)；
wherein Pmax is the peak power, Pm is a preset maximum power of the motor, V3 is the first control voltage, Vb is a preset reference voltage, and Vc is a preset zero-power operating voltage value of the motor.
Optionally, the rotation speed determination submodule is configured to:
determining a peak rotational speed according to the following formula:
Nmax＝9550*Pmax/Tmax；
where Nmax is the peak rotational speed and Tmax is the peak torque.
In another aspect, an embodiment of the present invention further provides an automobile, including the above motor control device.
In yet another aspect, an embodiment of the present invention further provides a controller, which includes a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor reads the program in the memory and executes the steps in the motor control method.
In still another aspect, embodiments of the present invention further provide an automobile, including the above controller.
In the embodiment of the invention, when the vehicle is in the under-voltage power-down operation condition, the control voltage of the motor is determined according to the direct-current bus voltage, the peak power and the peak torque are determined according to the control voltage, and the motor is controlled to work at the peak power constant power or work at the peak torque constant torque. According to the invention, by additionally adding a voltage rising coefficient Kn, when the voltage of the direct current bus rises, the voltage is controlled to rise along a fixed and slower speed; when the peak power and the peak torque are calculated, the numerical value of the control voltage is used as a reference, on one hand, the control voltage is not higher than the direct current bus voltage, so that the system can output a power amplitude limit value obtained based on the control voltage, and on the other hand, the fluctuation of the peak power and the peak torque is reduced. The invention solves the problem of motor output torque fluctuation caused by the voltage fluctuation of the direct current bus on the electric automobile.
It should be noted that the motor control device provided by the embodiment of the present invention is a device to which the above method is applied, that is, all embodiments of the above method are applicable to the device, and can achieve the same or similar beneficial effects.
While the foregoing is directed to the preferred embodiment of the present invention, it will be understood by those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the invention as defined in the appended claims.

Claims (15)

1. A motor control method is applied to a motor controller MCU of an electric automobile, and is characterized by comprising the following steps:
acquiring a first direct current bus voltage of a battery pack of the electric automobile in a current control period of the MCU;
determining a first control voltage of a motor of the electric automobile according to the first direct current bus voltage;
according to the first control voltage, when the motor is currently in an under-voltage power-down working condition, controlling the motor to work at constant power or constant torque;
wherein the step of controlling the motor to operate at a constant power or a constant torque comprises:
determining the peak power of the motor according to the first control voltage;
acquiring a preset peak torque of the motor;
determining a peak rotating speed according to the peak power and the peak torque;
when the current rotating speed of the motor is equal to or lower than the peak rotating speed, controlling the motor to work at the peak torque constant torque; or when the current rotating speed of the motor is higher than the peak rotating speed, controlling the motor to work at the peak power constant power.
2. The method of claim 1, wherein the step of determining a first control voltage for a motor of the electric vehicle based on the first dc bus voltage comprises:
when a second direct current bus voltage of a previous control period before the current control period is recorded in the MCU, determining a first control voltage of a motor of the electric automobile according to the first direct current bus voltage and the second direct current bus voltage; or
And when the second direct current bus voltage of the previous control period before the current control period is not recorded in the MCU, determining the first direct current bus voltage as the first control voltage of the motor of the electric automobile.
3. The method of claim 2, wherein the step of determining a first control voltage for a motor of the electric vehicle based on the first and second dc bus voltages comprises:
if the first direct current bus voltage is larger than the second direct current bus voltage, obtaining a first control voltage of a motor of the electric automobile according to a preset algorithm; otherwise, the first direct current bus voltage is used as the first control voltage.
4. The method according to claim 3, wherein the step of obtaining a first control voltage of the electric machine of the electric vehicle according to a preset algorithm comprises:
by the formula: obtaining a first control voltage of a motor of the electric vehicle by (1+ Kn) × Va2 Va 1;
wherein Va1 is the first control voltage, and Va2 is the second control voltage of the motor of the electric vehicle in the last control cycle;
kn is a preset voltage rise coefficient.
5. The method of claim 1, wherein the step of determining a peak power of the motor based on the first control voltage comprises:
determining a peak power of the motor according to the following formula:
Pmax＝Pm(V3-Vc)/(Vb-Vc)；
wherein Pmax is the peak power, Pm is a preset maximum power of the motor, V3 is the first control voltage, Vb is a preset reference voltage, and Vc is a preset zero-power operating voltage value of the motor.
6. The method of claim 5, wherein said step of determining a peak rotational speed based on said peak power and peak torque comprises:
determining a peak rotational speed according to the following formula:
Nmax＝9550*Pmax/Tmax；
where Nmax is the peak rotational speed and Tmax is the peak torque.
7. The utility model provides a motor control device, is applied to electric automobile's motor controller MCU, its characterized in that, the device includes:
the acquisition module is used for acquiring a first direct current bus voltage of a battery pack of the electric automobile in a current control period of the MCU;
the determining module is used for determining a first control voltage of a motor of the electric automobile according to the first direct current bus voltage;
the control module is used for controlling the motor to work at constant power or constant torque according to the first control voltage when the motor is currently in an under-voltage and under-voltage power-drop working condition;
wherein the control module comprises:
the power determination submodule is used for determining the peak power of the motor according to the first control voltage;
the torque acquisition submodule is used for acquiring a preset peak torque of the motor;
the rotating speed determining submodule is used for determining the peak rotating speed according to the peak power and the peak torque;
the control submodule is used for controlling the motor to work at the peak torque constant torque when the current rotating speed of the motor is equal to or lower than the peak rotating speed; or when the current rotating speed of the motor is higher than the peak rotating speed, controlling the motor to work at the peak power constant power.
8. The apparatus of claim 7, wherein the determining module comprises:
the first determining submodule is used for determining a first control voltage of a motor of the electric automobile according to the first direct-current bus voltage and a second direct-current bus voltage when the second direct-current bus voltage of a previous control period before the current control period is recorded in the MCU; or
And the second determining submodule is used for determining the first direct-current bus voltage as the first control voltage of the motor of the electric automobile when the second direct-current bus voltage of the previous control period before the current control period is not recorded in the MCU.
9. The apparatus of claim 8, wherein the first determination submodule comprises:
the voltage determining unit is used for obtaining a first control voltage of a motor of the electric automobile according to a preset algorithm if the first direct current bus voltage is greater than the second direct current bus voltage; otherwise, the first direct current bus voltage is used as the first control voltage.
10. The apparatus of claim 9, wherein the voltage determination unit is configured to:
by the formula: obtaining a first control voltage of a motor of the electric vehicle by (1+ Kn) × Va2 Va 1;
wherein Va1 is the first control voltage, and Va2 is the second control voltage of the motor of the electric vehicle in the last control cycle;
kn is a preset voltage rise coefficient.
11. The apparatus of claim 7, wherein the power determination sub-module is configured to:
determining a peak power of the motor according to the following formula:
Pmax＝Pm(V3-Vc)/(Vb-Vc)；
wherein Pmax is the peak power, Pm is a preset maximum power of the motor, V3 is the first control voltage, Vb is a preset reference voltage, and Vc is a preset zero-power operating voltage value of the motor.
12. The apparatus of claim 11, wherein the rotational speed determination submodule is configured to:
determining a peak rotational speed according to the following formula:
Nmax＝9550*Pmax/Tmax；
where Nmax is the peak rotational speed and Tmax is the peak torque.
13. An automobile, comprising: the motor control device according to any one of claims 7 to 12.
14. A controller comprising a memory, a processor and a computer program stored on the memory and executable on the processor, wherein the processor reads the program in the memory and executes the steps of the motor control method according to any one of claims 1 to 6.
15. An automobile, comprising: the controller of claim 14.
CN201810027185.3A 2018-01-11 2018-01-11 Motor control method and device, controller and automobile Active CN108258971B (en)

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