CN110661474A

CN110661474A - Motor locked-rotor state protection method and device and electronic equipment

Info

Publication number: CN110661474A
Application number: CN201910944115.9A
Authority: CN
Inventors: 王冬; 张磊; 李军营; 吕凤龙; 赵广兴
Original assignee: Weichai Power Co Ltd
Current assignee: Weichai Power Co Ltd
Priority date: 2019-09-30
Filing date: 2019-09-30
Publication date: 2020-01-07

Abstract

The application provides a method and a device for protecting a locked-rotor state of a motor and electronic equipment, which are used for acquiring power limiting parameters of an electric drive system, the rotating speed of the motor, and output torque and current in real time; the power limiting parameters at least comprise the temperature of the IGBT module, the temperature difference of the IGBT module and the motor locked-rotor depth; judging whether the motor enters a locked-rotor state or not according to the rotating speed, the output torque and the current of the motor; if the motor is judged to enter the locked-rotor state, aiming at each power limiting parameter of the electric drive system, the corresponding relation between the pre-established power limiting parameter and the limiting coefficient is utilized to determine the limiting coefficient value corresponding to the current power limiting parameter of the electric drive system, then the minimum limiting coefficient value is utilized to correct the required torque value of the motor to obtain the target torque value, and the output torque of the motor is set as the target torque.

Description

Motor locked-rotor state protection method and device and electronic equipment

Technical Field

The invention relates to the technical field of motor control, in particular to a method and a device for protecting a locked-rotor state of a motor and electronic equipment.

Background

When the electric automobile runs, if the whole automobile tire is locked or climbs over the whole automobile and relates to the conditions of climbing a steep slope and the like, the driving motor of the electric automobile can enter a locked-rotor state. The motor is in a locked-rotor state for a long time, and the motor body and the motor controller are easily damaged. Therefore, a corresponding locked-rotor protection method is generally designed in the motor controller to avoid damage to the motor body and the motor controller caused by a locked-rotor state.

The existing locked rotor protection method generally detects a certain operation index of the motor, judges whether the motor enters a locked rotor state according to the operation index, and further adjusts the output torque of the motor according to the operation index and a preset adjustment rule, so as to achieve the purpose of avoiding the damage of a motor body and a motor controller.

However, the conventional method generally only considers a single operation index of the motor, for example, according to an accumulated value of an effective current of the motor, or according to an output torque of the motor and a duration within a specific torque range, and the like, and the single operation index often cannot accurately and timely reflect the working states of the motor body and the motor controller, so that the conventional locked rotor protection method may have a situation of untimely torque adjustment.

Disclosure of Invention

Aiming at the defects of the prior art, the invention provides a method and a device for protecting a locked-rotor state of a motor and electronic equipment, and aims to solve the problem that the existing locked-rotor protection method based on a single index is not timely in response.

The invention provides a protection method for a locked-rotor state of a motor, which comprises the following steps:

acquiring power limiting parameters of an electric drive system, the rotating speed of a motor, output torque and current in real time; the electric drive system comprises a motor and a motor controller, the motor controller comprises an IGBT module, and the power limiting parameters at least comprise the temperature of the IGBT module, the temperature difference of the IGBT module and the motor stalling depth;

judging whether the motor enters a locked-rotor state or not according to the rotating speed, the output torque and the output current of the motor;

if the motor is judged to enter the locked-rotor state, determining a limiting coefficient value corresponding to the current power limiting parameter of the motor by utilizing a pre-established corresponding relation between the power limiting parameter and the limiting coefficient aiming at each power limiting parameter of the electric drive system;

correcting the required torque value of the motor by using the minimum limit coefficient value in the plurality of determined limit coefficient values to obtain a target torque value;

setting an output torque of the motor to the target torque value.

Optionally, the determining whether the motor enters a locked-rotor state according to the rotation speed, the output torque and the current of the motor includes:

judging whether the rotating speed of the motor is smaller than a rotating speed threshold value or not, whether the output torque of the motor is larger than a torque threshold value or not and whether the current of the motor is larger than a current threshold value or not;

if the rotating speed of the motor is smaller than the rotating speed threshold value, the output torque of the motor is larger than the torque threshold value, and the current is larger than the current threshold value, the motor is judged to enter a locked-rotor state;

and if any one or combination of the three conditions that the rotating speed of the motor is greater than or equal to the rotating speed threshold value, the output torque of the motor is less than or equal to the torque threshold value and the current is less than or equal to the current threshold value exists, judging that the motor does not enter a locked-rotor state.

Optionally, before the step of correcting the required torque value of the motor by using the minimum limit coefficient value of the determined plurality of limit coefficient values to obtain the target torque value, the method further includes:

and if the motor does not enter the locked-rotor state, determining a limit coefficient value corresponding to the current power limit parameter of the motor by utilizing a pre-established corresponding relation between the power limit parameter and the limit coefficient for each power limit parameter of the electric drive system except the locked-rotor depth of the motor.

Optionally, after acquiring the current power limitation parameter of the motor, the method further includes:

judging whether the locked rotor depth of the current motor is larger than a preset frequency reduction depth threshold value or not;

and if the current locked-rotor depth of the motor is greater than or equal to the frequency reduction depth threshold, reducing the frequency of the control signal of the inverter to a first frequency threshold.

Optionally, the corresponding relationship between each power limiting parameter and the limiting coefficient is established according to the operation condition of the motor in the maximum loss locked-rotor state;

when the motor is in a maximum loss locked-rotor state, the rotor position of the motor is in a locked-rotor state of the rotor position corresponding to the maximum loss value of the IGBT module;

the rotor position corresponding to the maximum loss value of the IGBT module comprises the following steps: 0 °, 60 °, 120 °, 180 °, 240 ° and 300 °.

The second aspect of the present invention provides a protection device for a locked-rotor state of a motor, comprising:

the acquisition unit is used for acquiring the power limiting parameters of the electric drive system, the rotating speed of the motor, the output torque and the current in real time; the electric drive system comprises a motor and a motor controller, the motor controller comprises an IGBT module, and the power limiting parameters at least comprise the temperature of the IGBT module, the temperature difference of the IGBT module and the motor stalling depth;

the judging unit is used for judging whether the motor enters a locked-rotor state or not according to the rotating speed, the output torque and the current of the motor;

the determining unit is used for determining a limiting coefficient value corresponding to the current power limiting parameter of the motor by utilizing a pre-established corresponding relation between the power limiting parameter and the limiting coefficient aiming at each power limiting parameter of the electric drive system if the motor is judged to enter the locked-rotor state;

the correction unit is used for correcting the required torque value of the motor by using the minimum limit coefficient value in the plurality of determined limit coefficient values to obtain a target torque value;

a setting unit for setting an output torque of the motor to the target torque value.

Optionally, the determining unit is configured to, when determining whether the motor enters a locked-rotor state according to the rotation speed, the output torque, and the current of the motor:

Optionally, the determining unit is further configured to:

A third aspect of the invention provides an electronic device comprising a memory and a processor;

the memory is to store computer instructions;

the processor is configured to execute the computer instructions stored in the memory, and when executed, the computer instructions are specifically configured to execute the protection method for a locked-rotor state of a motor according to any one of the first aspect of the present invention.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the provided drawings without creative efforts.

Fig. 1 is a flowchart of a protection method for a locked-rotor state of a motor according to an embodiment of the present invention;

fig. 2 is a flowchart of another protection method for a locked-rotor state of a motor according to an embodiment of the present invention;

fig. 3 is a schematic structural diagram of a protection device for a locked-rotor state of a motor according to an embodiment of the present invention;

fig. 4 is a schematic structural diagram of an electronic 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 only a part of the embodiments of the present invention, and not all of the embodiments. 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.

When the electric automobile runs, if the whole automobile tire is locked or climbs over the whole automobile and relates to the conditions of climbing a steep slope and the like, the driving motor of the electric automobile can enter a locked-rotor state.

The locked-rotor state is characterized in that the motor has output torque, but the output shaft of the motor does not rotate or the rotating speed is extremely low.

On the other hand, in the above case, the driver often keeps the required torque of the motor near the locked-rotor peak torque for a long time by depressing the accelerator pedal in order to enable the vehicle to run. If the required torque of the motor is not adjusted, the controller of the motor can directly set the output torque of the motor to be the required torque, and then the motor in the locked-rotor state can be operated nearby the locked-rotor peak torque for a long time. Most of the power of the motor in the locked-rotor state cannot be converted into mechanical energy to be output, and the power is finally converted into heat, so that the temperature of components such as a motor body and an IGBT module rises rapidly, and the hardware is damaged finally.

In order to avoid damage to the motor and the IGBT module when the motor runs in a locked-rotor peak torque for a long time, embodiments of the present application provide a protection method for a locked-rotor state of the motor, which corrects a required torque by using a correction coefficient, and sets an output torque of the motor to a target torque obtained after correction, thereby avoiding damage to hardware caused by overheating of hardware in an electric drive system.

Referring to fig. 1, the method includes the following steps:

s101, acquiring power limiting parameters of the electric drive system, the rotating speed of the motor, and output torque and current in real time.

The electric drive system comprises a motor and a motor controller, the motor controller comprises an IGBT module, and the power limiting parameters at least comprise the temperature of the IGBT module, the temperature difference of the IGBT module and the motor stalling depth.

The power limiting parameters of the motor at least comprise the current locked rotor depth of the motor, the current IGBT module temperature of the motor and the current IGBT module temperature difference of the motor.

Optionally, the power limiting parameter of the motor may further include: current motor temperature, current motor controller temperature, current motor phase current, current bus voltage, current phase voltage, and the like.

The IGBT module of the motor is a device which is composed of three bridge arms and is used for converting direct current output by a battery into three-phase alternating current so as to drive the motor to run. Each bridge arm is divided into an upper bridge arm and a lower bridge arm, and each section is provided with an Insulated Gate Bipolar Transistor (IGBT). Each bridge arm of the motor IGBT module corresponds to one phase of three-phase alternating current.

The switching frequency of the IGBT module of the motor (the frequency of switching between the IGBT on state and the IGBT off state). The higher the frequency of the PWM signal, the higher the switching frequency of each IGBT in the IGBT module, and the greater the switching loss of the IGBT module, and conversely, the lower the frequency of the PWM signal, the smaller the switching loss of the IGBT module.

In this embodiment, the temperatures of the three bridge arms of the IGBT module of the motor can be measured by using a resistor having a negative temperature coefficient.

The current IGBT module temperature difference of the motor is the difference value between the current temperature of the bridge arm with the highest temperature and the current temperature of the bridge arm with the lowest temperature in the three bridge arms of the IGBT module.

The current temperature of the IGBT module refers to the highest temperature in three bridge arms of the IGBT module.

Optionally, the current locked-rotor depth of the motor may be acquired by setting a locked-rotor timer in the motor controller.

Specifically, the initial value of the locked-rotor timer is 0, after it is determined that the motor enters the locked-rotor state through the following step S102, the locked-rotor timer enters the count-up state, and increments the current time, and if it is determined that the motor currently exits the locked-rotor state through the step S102 at any time, the locked-rotor timer enters the count-down state and decrements the current time on the premise that the accumulated time of the locked-rotor timer is greater than 0, until the accumulated time is equal to 0, or the motor enters the locked-rotor state again, and the process is repeated.

Based on the working principle of the locked-rotor timer, at any moment, only the current accumulated time value of the locked-rotor timer needs to be read, and the obtained result is the current locked-rotor depth.

And S102, outputting torque and current according to the rotating speed of the motor to judge whether the motor enters a locked-rotor state.

The motor generally has the following characteristics when entering a locked-rotor state: the rotating speed is extremely low, the passing effective current is extremely high, and the output torque is extremely high.

For this feature, the determination in step S102 can be based on the rotation speed, torque and effective current of the motor. Specifically, the specific implementation manner of step S102 may be:

acquiring the rotating speed, the effective current and the output torque of the motor in real time, and comparing the rotating speed, the effective current and the output torque of the motor with corresponding thresholds;

if the following conditions are simultaneously satisfied: judging that the motor enters a locked-rotor state if the rotating speed of the motor is less than a preset rotating speed threshold value, the effective current of the motor is greater than a preset current threshold value and the output torque of the motor is greater than a preset torque threshold value; the locked-rotor timer performs an up-counting state.

If at least one of the three conditions is not met, the motor is judged not to enter the locked-rotor state, and the locked-rotor timer performs the count-down state until the timing is 0.

If the motor is determined to enter the locked-rotor state, step S103 is executed, and if the motor is determined not to enter the locked-rotor state, step S104 is executed.

Optionally, after the motor is judged to enter the locked-rotor state, the locked-rotor early warning information can be output to prompt a driver to enter the locked-rotor state according to whether the locked-rotor depth of the motor is greater than the early warning time threshold or not.

S103, determining a corresponding limit coefficient value according to each current power limit parameter of the motor.

Specifically, each motor power limiting parameter corresponds to a limiting coefficient. The current locked-rotor depth of the motor corresponds to a first limiting coefficient K1, the current IGBT module temperature of the motor corresponds to a second limiting coefficient K2, and the current IGBT module temperature difference of the motor corresponds to a third limiting coefficient K3.

If the power limiting parameters collected in step S101 further include the current motor temperature, the current motor controller temperature, the current motor phase current, the current bus voltage, and the current phase voltage, the limiting coefficient determined in step S103 further includes:

the current motor temperature corresponds to a fourth limiting coefficient K4, the current motor controller temperature corresponds to a fifth limiting coefficient K5, the current motor phase current corresponds to a sixth limiting coefficient K6, the current bus voltage corresponds to a seventh limiting coefficient K7, and the current phase voltage corresponds to an eighth limiting coefficient K8.

Step S103 may be obtained based on the correspondence between the power limiting parameter of the motor and the limiting coefficient, which is experimentally measured in advance.

In any embodiment of the present application, the corresponding relationship between each power limiting parameter and the limiting coefficient is determined according to the operation condition of the motor in the maximum loss locked-rotor state.

In this embodiment, the correspondence between the power limiting parameter and the limiting coefficient of the motor can be represented in the form of the following tables 1 and 2:

table 1 is a correspondence table of the locked rotor depth and the first restriction coefficient:

TABLE 1

Depth of locked rotor	T1	T2	T3	……	Tn
						First limiting coefficient	X1	X2	X3	……	Xn

The first row is values of different locked rotor depths, which are sequentially recorded as T1 and T2 … … Tn, and each locked rotor depth value corresponds to a value of a first limiting coefficient determined according to actual requirements and test results, which is sequentially recorded as X1 and X2 … … Xn. Wherein X1 is equal to 1, Xn is equal to 0, and the respective first limit coefficient values between X1 and Xn are gradually decreased with increasing number until Xn is equal to 0.

After the current locked-rotor depth of the motor is acquired, if the current locked-rotor depth of the motor is smaller than the minimum locked-rotor depth T1 in the table 1, the first limiting coefficient is set to be 1.

If the current locked-rotor depth of the motor can be directly obtained by searching from the table 1, the value of the first limiting coefficient corresponding to the current locked-rotor depth of the motor recorded in the table 1 is directly determined as the first limiting coefficient corresponding to the current locked-rotor depth in step S105.

If the acquired current locked-rotor depth cannot be directly searched from the table 1, the minimum interval including the current locked-rotor depth may be searched from the table 1. For example, if the current locked-rotor depth Tx is greater than the locked-rotor depth T5 in table 1 and smaller than T6, the interval defined by T5 and T6 constitutes the minimum interval including the current locked-rotor depth.

After the interval is determined, the first limiting coefficient corresponding to the current locked rotor depth may be calculated by using an interpolation algorithm according to the values of the first limiting coefficients corresponding to the locked rotor depths at the two ends of the interval (specifically, in the above example, the locked rotor depths at the two ends are T5 and T6).

Besides the corresponding relation between the locked-rotor depth and the first limiting coefficient, the corresponding relation between other power limiting parameters and the limiting coefficients can be set according to the safe working range characteristics of the device.

Similarly, the correspondence between the temperature of the IGBT module of the motor and the limiting coefficient acquired in step S104 can be represented by the following table 2:

TABLE 2

Temperature of IGBT module	W1	W2	W3	……	Wn
						Second limiting factor	Y1	Y2	Y3	……	Yn

Similar to table 1 above, Y1 equals 1 and Yn equals 0. The method for determining the second limiting coefficient corresponding to the current temperature of the IGBT module of the motor using table 2 is similar to the method for determining the first limiting coefficient using table 1, and is not described herein again. The respective second limit coefficient values between Y1 and Yn gradually decrease with increasing numbering until Yn equals 0.

If the temperature of the IGBT module is less than the minimum value in table 2, the value of the second limiting coefficient is 1. Other power limiting parameters are similar, and if the current parameter value is smaller than the minimum value in the corresponding relation, the value of the corresponding limiting coefficient is 1, that is, the output torque is not adjusted.

Further, in any embodiment of the present application, the correspondence between the temperature difference of the IGBT module of the motor and the third limiting coefficient K3, the correspondence between the motor temperature and the fourth limiting coefficient K4, the correspondence between the motor controller temperature and the fifth limiting coefficient K5, and the correspondence between the motor phase current and the sixth limiting coefficient K6 may be recorded in the form of table 1 and table 2. And, the method for finding out the value of the limiting coefficient corresponding to the current power limiting parameter according to the corresponding relation table is consistent with the method for finding out the first limiting coefficient.

And S104, determining a limiting coefficient value corresponding to each power limiting parameter of the electric drive system except for the locked-rotor depth of the motor.

The process of determining the constraint coefficient value in the determination step S104 is identical to the process in the aforementioned step S103, and is not described herein again.

And S105, determining a minimum limit coefficient value from the limit coefficients corresponding to the current power limit parameters.

Specifically, if the current locked-rotor depth of the motor, the current IGBT module temperature of the motor, and the current IGBT module temperature difference of the motor are collected in step S101, and step S103 is executed, the first limit coefficient value, the second limit coefficient value, and the third limit coefficient value may be determined in step S103, and at this time, the step S105 needs to determine the minimum limit coefficient value from the three limit coefficient values.

If the current locked-rotor depth of the motor, the current IGBT module temperature of the motor, and the current IGBT module temperature difference of the motor are collected in step S101, but step S104 is executed without executing step S103, so as to determine the second limit coefficient value and the third limit coefficient value, step S105 needs to determine the minimum limit coefficient value from the two limit coefficient values.

Optionally, if, in addition to the three power limiting parameters, step S101 further acquires a current motor temperature, a current motor controller temperature, a current motor phase current, a current bus voltage, and a current phase voltage, step S103 may determine eight limiting coefficient values, step S104 may determine seven limiting coefficient values, and according to whether the motor enters a locked-rotor state, if step S103 is executed, a minimum value needs to be determined from the eight limiting coefficient values in step S105, and if step S104 is executed, a minimum value needs to be determined from the seven limiting coefficient values in step S105.

And S106, correcting the required torque by using the minimum limit coefficient value to obtain a target torque value.

The required torque is a torque value set by the driver by stepping on the accelerator,

the correction in step S106 is to multiply the minimum limit coefficient value by the required torque, and the result is the target torque value.

And S107, setting the output torque value of the motor as a target torque value.

It is understood that after step S107 is completed, the process may return to step S101 again to continue monitoring the operation state of the motor.

That is to say, the method provided by the embodiment can be operated in real time to monitor whether the motor enters the locked-rotor state, and the output torque of the motor is corrected when the motor is in the locked-rotor state for a long time.

The technical scheme that this application embodiment provided when being applied to the protection of the locked-rotor state of motor, has following advantage:

on the first hand, the hardware does not need to be changed, the hardware cost is not increased, the universality and the flexibility are wide, and the good protection effect can be achieved by reasonably setting the software parameter configuration; and each limiting coefficient is effective in locked rotor and non-locked rotor states, and plays a good role in protection.

In the second aspect, the delay effect of the negative temperature coefficient resistance for measuring temperature in the IGBT module is effectively reduced.

The IGBT module is generally internally provided with a negative temperature coefficient resistor for temperature measurement, and the traditional locked rotor state protection method generally only considers the measured temperature of the IGBT of each bridge arm of the IGBT module. But there is a significant delay effect when this type of resistor is used: namely, when the junction temperature of the IGBT rises sharply, the resistance value change of the negative temperature coefficient resistor lags behind the temperature change of the IGBT, so that the measured temperature cannot reflect the real temperature of the IGBT timely and accurately. Therefore, when only the temperature is used as the basis for adjusting the output torque of the motor, poor adjustment effect is easily caused due to the delay effect, and further the IGBT module of the motor is damaged.

The temperature difference between the highest temperature and the lowest temperature in the three bridge arms of the IGBT module is used as a basis for adjusting the output torque, so that the influence of a delay effect can be effectively compensated, and the output torque of the motor can be corrected timely and accurately.

In a third aspect, the effect of temperature sensor installation variations in the IGBT module is reduced.

The temperature sensor is also the aforementioned negative temperature coefficient resistance for measuring the temperature of the IGBT module. The common IGBT module structure generally adopts a scheme of "single module double switch tube", and in order to reduce cost during actual hardware assembly, the upper bridge arm and the lower bridge arm of the same bridge arm use the same temperature sensor, which may cause the following problems: when the motor actually works, the working bridge arm is far away from the temperature sensor, and the temperature of the working bridge arm cannot be really measured.

According to the scheme, the temperature difference between the highest temperature and the lowest temperature in three bridge arms of the IGBT module is used as a basis for correcting the output torque, so that the problems can be effectively prevented.

According to the fourth aspect, the torque correction coefficient is adjusted in real time according to the locked rotor depth reflected by the locked rotor depth of the motor by recording the locked rotor depth of the motor in real time, and meanwhile, parameters such as the continuous operation time of the motor at the locked rotor peak torque and the like can be set conveniently.

In the fifth aspect, the possibility of stopping the motor is reduced to the maximum extent while automatic control is realized through dynamic adjustment of limiting coefficients corresponding to various power limiting parameters. The operation of dynamically correcting the output torque is carried out by using the minimum value in the plurality of limiting coefficients, so that the protection of the current worst operation index is realized, meanwhile, along with the reduction of the output torque, the operation indexes such as the temperature of the motor and the IGBT module gradually tend to be stable and unchanged, a certain output torque is maintained when no other worse operation index appears, the motor is prevented from entering a shutdown state, and therefore more time for processing the locked rotor state is strived for by a driver.

In the sixth aspect, the output torque is adjusted according to other power limiting parameters (including parameters such as the temperature of the IGBT module and the temperature difference of the IGBT module) except for the locked rotor depth in the non-locked rotor state in step S104, so that the electric drive system can be protected under various working conditions of the motor. In addition, each parameter and the corresponding limiting coefficient in the scheme are independently calculated and used for controlling the output torque, and even if the acquisition device of one parameter fails, the protection effect of other limiting coefficients cannot be influenced.

In summary, compared with the existing locked rotor protection method, the locked rotor protection method has the advantages that the locked rotor depth, the IGBT module temperature and the IGBT module temperature difference are introduced to serve as the basis for correcting the output torque of the motor in the locked rotor state, and the problems that the existing locked rotor protection method only considers a single operation index to cause untimely torque adjustment are effectively solved.

Another embodiment of the present application further provides a method for protecting a locked-rotor state of a motor, please refer to fig. 2, where the method includes the following steps:

s201, acquiring power limiting parameters of the electric drive system, the rotating speed of the motor, and output torque and current in real time.

S202, judging whether the motor enters a locked-rotor state or not according to the rotating speed, the output torque and the current of the motor.

If the motor is determined to enter the locked-rotor state, step S203 is executed.

If the motor is determined not to enter the locked-rotor state, step S206 is executed.

if the current locked-rotor depth of the motor is greater than or equal to the frequency-reduction depth threshold,

s203, judging whether the locked rotor depth of the current motor is larger than a preset frequency reduction depth threshold value or not.

If the current locked-rotor depth of the motor is greater than or equal to the frequency-reduction depth threshold, step S204 is executed.

If the current locked-rotor depth of the motor is smaller than the down-conversion depth threshold, step S205 is executed.

And S204, reducing the frequency of the PWM control signal of the inverter to a first frequency threshold value.

S205, determining a corresponding limit coefficient value according to each current power limit parameter of the motor.

And S206, determining a limiting coefficient value corresponding to each power limiting parameter of the electric drive system except for the locked-rotor depth of the motor.

And S207, determining a minimum limit coefficient value from the limit coefficients corresponding to the current power limit parameters.

And S208, correcting the required torque by using the minimum limit coefficient value to obtain a target torque value, and setting the output torque value of the motor as the target torque value.

The embodiment can further prolong the continuous operation time of the motor under the locked rotor peak torque by reducing the frequency of the PWM signal.

Generally, the motor body can support continuous operation for more than 60 seconds under the locked rotor peak torque without damage, but the existing motor controller can only support continuous operation for 10 seconds under the locked rotor peak torque generally, and damage is easy to occur after more than 10 seconds. When the locked-rotor depth is greater than the frequency reduction time threshold value, the switching loss of the IGBT module is reduced by reducing the frequency of the PWM signal for controlling the switching frequency of the IGBT module, so that the temperature of the IGBT in the IGBT module is reduced, and the continuous operation time of the motor controller under the locked-rotor peak torque is prolonged.

In combination with the method for protecting a locked-rotor state of a motor according to any embodiment of the present application, another embodiment of the present application provides a device for protecting a locked-rotor state of a motor, please refer to fig. 3, where the device includes the following structure:

and the acquisition unit 301 is used for acquiring the power limit parameters of the electric drive system, the rotating speed of the motor, the output torque and the current in real time.

The judging unit 302 is configured to judge whether the motor enters a locked-rotor state according to the rotation speed, the output torque, and the output current of the motor.

The determining unit 303 is configured to determine, for each power limiting parameter of the electric drive system, a limiting coefficient value corresponding to a current power limiting parameter of the motor by using a pre-established correspondence between the power limiting parameter and the limiting coefficient if it is determined that the motor enters the locked-rotor state.

And a correcting unit 304 for correcting the required torque value of the motor by using the smallest limiting coefficient value among the determined plurality of limiting coefficient values to obtain a target torque value.

A setting unit 305 for setting the output torque of the motor to the target torque value.

Optionally, when the determining unit 302 determines whether the motor enters the locked-rotor state according to the rotation speed, the output torque, and the current of the motor, the determining unit is specifically configured to:

Optionally, the determining unit 303 is further configured to:

Optionally, the determining unit 302 is further configured to:

and if the current locked-rotor depth of the motor is greater than or equal to the frequency reduction depth threshold, reducing the frequency of the control signal of the IGBT module to a first frequency threshold.

The specific working principle of the protection device for the locked-rotor state of the motor provided by any embodiment of the present application can refer to the protection method for the locked-rotor state of the motor provided by any embodiment of the present application, and is not repeated here.

The application provides a protection device for a locked-rotor state of a motor, wherein a collecting unit 301 collects power limiting parameters of an electric driving system, the rotating speed of the motor, and output torque and current in real time; the power limiting parameters at least comprise the temperature of the IGBT module, the temperature difference of the IGBT module and the motor locked-rotor depth; the judging unit 302 judges whether the motor enters a locked-rotor state according to the rotating speed, the output torque and the current of the motor; if the motor is judged to enter the locked-rotor state, for each power limiting parameter of the electric drive system, the determining unit 303 determines a limiting coefficient value corresponding to the current power limiting parameter of the electric drive system by using a pre-established corresponding relationship between the power limiting parameter and the limiting coefficient, the correcting unit 304 corrects the required torque value of the motor by using the minimum limiting coefficient value to obtain a target torque value, and the setting unit 305 sets the output torque of the motor as the target torque.

Still another embodiment of the present application provides an electronic device, please refer to fig. 4, which includes a memory 401 and a processor 402;

the memory 401 is used for storing computer instructions;

the processor is configured to execute the computer instructions stored in the memory 401, and when the computer instructions are executed, the computer instructions are specifically configured to execute the protection method for the locked-rotor state of the motor according to any embodiment of the present application.

Those skilled in the art can make or use the present application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the application. Thus, the present application is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for protecting a locked-rotor state of a motor is characterized by comprising the following steps:

setting an output torque of the motor to the target torque value.

2. The protection method according to claim 1, wherein the judging whether the motor enters the locked-rotor state according to the rotation speed, the output torque and the current of the motor comprises:

3. The protection method according to claim 1, wherein before the step of correcting the required torque value of the motor to obtain the target torque value by using the smallest limiting coefficient value among the determined limiting coefficient values, further comprises:

4. The protection method according to claim 1, wherein after collecting the current power limit parameter of the motor, the method further comprises:

5. The protection method according to any one of claims 1 to 4, wherein the corresponding relation between each power limiting parameter and the limiting coefficient is established according to the operation condition of the motor in the maximum loss locked-rotor state;

6. A protection device for a locked-rotor state of a motor is characterized by comprising:

7. The protection device according to claim 6, wherein the determining unit is configured to, when determining whether the motor enters the locked-rotor state according to the rotation speed, the output torque, and the current of the motor:

8. The protection device according to claim 6, wherein the determination unit is further configured to:

9. The protection device according to claim 6, wherein the determination unit is further configured to:

10. An electronic device comprising a memory and a processor;

the memory is to store computer instructions;

the processor is configured to execute the computer instructions stored in the memory, and when executed, is specifically configured to perform the method of protecting a locked rotor condition of a motor according to any one of claims 1 to 5.