Torque derating control method and device of permanent magnet synchronous motor

Abstract

The invention provides a torque derating control method and device for a permanent magnet synchronous motor. The torque derating control method comprises the steps of collecting a current rotating speed of a target permanent magnet synchronous motor; according to the motor rotation direction indicated by the current rotation speed, a torque derating strategy corresponding to the current rotation speed is determined, the torque derating strategy indicates a plurality of torque derating stages, and different torque derating stages correspond to different derating slopes; determining a target torque derating stage of the current rotating speed according to the current rotating speed and a torque derating strategy corresponding to the current rotating speed; according to the target torque derating stage, determining a target derating slope corresponding to the target torque derating stage; and controlling the output torque of the target permanent magnet synchronous motor to derated according to the target derating slope. The torque derating of different speed degrees is carried out according to the actual overspeed condition of the motor, and the protection effect of the permanent magnet synchronous motor on the motor when the permanent magnet synchronous motor is applied to different overspeed working conditions is improved.

Description

Technical Field

[0001] The present application relates to the technical field of motor torque derating control, and in particular to a method and device for torque derating control of a permanent magnet synchronous motor. Background Art

[0002] Permanent magnet synchronous motors are widely used in new energy vehicles and can be used as drive motors and generators. The operating state of the motor is crucial to the power system. If the permanent magnet synchronous motor runs at an overspeed, the mechanical stress of the rotor and bearings will increase, which may cause premature wear or damage to the mechanical parts. In addition, when the motor runs at an overspeed, the internal loss will increase with the increase in temperature, which may cause the motor to overheat. Under extreme overspeed conditions, high temperature may cause partial demagnetization of the permanent magnet, affecting the performance of the motor. When the whole vehicle is running, if the motor runs at an overspeed, it may cause the whole vehicle to run too fast, which is prone to safety accidents. In order to avoid these potential problems, when the permanent magnet synchronous motor is running, there must be an overspeed derating mechanism. When the motor runs at an overspeed, the output power is derating controlled to reduce the output power to ensure that the motor operates within a safe speed range.

[0003] The commonly used derating method at present is to set two fixed derating thresholds, compare the motor temperature with the derating thresholds for linear derating. The disadvantage of this linear derating method is that the derating slope is fixed, so the torque output cannot be adjusted according to the change of motor speed, which reduces the protection effect of permanent magnet synchronous motor under different overspeed conditions. Summary of the invention

[0004] In view of this, the purpose of the present application is to at least provide a torque derating control method and device for a permanent magnet synchronous motor, which performs torque derating at different speeds according to the actual overspeed situation of the motor, thereby improving the protection effect of the permanent magnet synchronous motor on the motor when applied to different overspeed conditions.

[0005] This application mainly includes the following aspects:

[0006] In a first aspect, an embodiment of the present application provides a torque derating control method for a permanent magnet synchronous motor, the method comprising: acquiring a current speed of a target permanent magnet synchronous motor; determining a torque derating strategy corresponding to the current speed according to the motor rotation direction indicated by the current speed, the torque derating strategy indicating a plurality of torque derating stages, and different torque derating stages corresponding to different derating slopes; determining a target torque derating stage of the current speed according to the current speed and the torque derating strategy corresponding to the current speed; determining a target derating slope corresponding to the target torque derating stage according to the target torque derating stage; and controlling the output torque of the target permanent magnet synchronous motor to be derated at the target derating slope.

[0007] In one possible implementation, the torque derating strategy includes a motor forward derating strategy and a motor reverse derating strategy, wherein the target derating slope corresponding to the current speed is determined in the following manner: if the current speed is greater than or equal to zero, the target torque derating stage and the target derating slope corresponding to the current speed are determined according to the motor forward derating strategy; if the current speed is less than zero, the target torque derating stage and the target derating slope corresponding to the current speed are determined according to the motor reverse derating strategy.

[0008] In a possible implementation, the motor forward derating strategy includes a first torque derating stage under the motor forward state and its corresponding first section forward derating starting threshold, first section forward derating end threshold, a second torque derating stage under the motor forward state and its corresponding second section derating starting threshold and second section derating end threshold, wherein the first section forward derating starting threshold is greater than zero, the first section forward derating starting threshold is less than the first section forward derating end threshold, the first section forward derating end threshold is equal to the second section derating starting threshold, the second section derating starting threshold is less than the second section derating end threshold, wherein, according to the motor forward derating strategy, the target torque derating stage and target torque derating stage corresponding to the current speed are determined. The step of determining the derating slope includes: if the current speed is greater than the first-stage positive derating starting threshold and less than or equal to the first-stage positive derating ending threshold, determining that the target permanent magnet synchronous motor is in the first torque derating stage; determining the first positive derating slope according to the first-stage positive derating starting threshold and the first-stage positive derating ending threshold, and determining the first positive derating slope as the target derating slope; if the current speed is greater than the second-stage derating starting threshold and less than or equal to the second-stage derating ending threshold, determining that the target permanent magnet synchronous motor is in the second torque derating stage; determining the second derating slope according to the second-stage derating starting threshold and the second-stage derating ending threshold, and determining the second derating slope as the target derating slope.

[0009] In a possible implementation, the first positive derating slope and the second derating slope are determined in the following manner: a first difference between a first-segment positive derating starting point threshold and a first-segment positive derating ending point threshold is calculated, and a ratio between 1 and the first difference is determined as the first derating slope; a second difference between a second-segment positive derating starting point threshold and a second-segment positive derating ending point threshold is calculated, and a ratio between 1 and the second difference is determined as the second derating slope.

[0010] In a possible implementation, the step of controlling the output torque of the target permanent magnet synchronous motor to derate at a target derate slope includes: if the motor is in the first torque derate stage in the forward rotation state of the motor, calculating the first theoretical derate coefficient according to the first positive derate slope, the current speed and the first forward derate endpoint threshold; if the first theoretical derate coefficient is less than or equal to zero, determining zero as the first actual derate coefficient corresponding to the first torque derate stage; if the first theoretical derate coefficient is greater than or equal to 1, determining 1 as the first actual derate coefficient corresponding to the first torque derate stage; determining the first actual derate coefficient according to the first actual derate coefficient, the requested torque of the motor, and the first torque derate stage corresponding to the forward rotation state of the motor. The torque derating bias is used to determine the output torque of the motor at the current speed; if the motor is in the second torque derating stage, the second theoretical derating coefficient corresponding to the second torque derating stage is calculated according to the second derating slope, the current speed and the second derating endpoint threshold; if the second theoretical derating coefficient is less than or equal to zero, zero is determined as the second actual derating coefficient corresponding to the second torque derating stage under the forward rotation state of the motor; if the second theoretical derating coefficient is greater than or equal to 1, 1 is determined as the second actual derating coefficient corresponding to the second torque derating stage under the forward rotation state of the motor; the output torque of the motor at the current speed is determined according to the second actual derating coefficient and the output torque corresponding to the first torque derating stage.

[0011] In a possible implementation, the motor reversal derating strategy includes a first derating stage under the motor reversal state and its corresponding first section reverse derating starting point threshold, first section reverse derating end point threshold, a second derating stage under the motor reversal state and its corresponding second section derating starting point threshold and second section derating end point threshold, wherein the first section reverse derating starting point threshold is greater than zero, the first section reverse derating starting point threshold is less than the first section reverse derating end point threshold, the first section reverse derating end point threshold is equal to the second section derating starting point threshold, and the second section derating starting point threshold is less than the second section derating end point threshold, wherein, according to the motor reversal derating strategy, the step of determining the target derating slope corresponding to the current speed includes: calculating the absolute value corresponding to the current speed to obtain the current target speed; if the current target speed If the target speed is greater than the first-stage reverse derating starting threshold and less than or equal to the first-stage reverse derating end threshold, it is determined that the target permanent magnet synchronous motor is in the first torque derating stage under the motor reversal state; according to the first-stage reverse derating starting threshold and the first-stage reverse derating end threshold, the first reverse derating slope is determined, and the first reverse derating slope is determined as the target derating slope; if the current speed is greater than the second-stage derating starting threshold and less than or equal to the second-stage derating end threshold, it is determined that the target permanent magnet synchronous motor is in the second torque derating stage under the motor reversal state; according to the second-stage derating starting threshold and the second-stage derating end threshold corresponding to the second torque derating stage under the motor reversal state, the second derating slope is determined, and the second derating slope is determined as the target derating slope.

[0012] In a possible implementation, the first reverse derating slope and the second derating slope are determined in the following manner: a third difference between a first-segment reverse derating starting point threshold and a first-segment reverse derating ending point threshold is calculated, and a ratio between 1 and the third difference is determined as the first reverse derating slope; a second difference between a second-segment reverse derating starting point threshold and a second-segment reverse derating ending point threshold is calculated, and a ratio between 1 and the second difference is determined as the second derating slope.

[0013] In a possible implementation, the step of controlling the output torque of the target permanent magnet synchronous motor to derate at a target derating slope includes: if the motor is in the first torque derating stage in the motor reversal state, calculating the first theoretical derating coefficient according to the first reverse derating slope, the current target speed and the first reverse derating endpoint threshold; if the first theoretical derating coefficient is less than or equal to zero, determining zero as the first actual derating coefficient corresponding to the first torque derating stage; if the first theoretical derating coefficient is greater than or equal to 1, determining 1 as the first actual derating coefficient corresponding to the first torque derating stage; determining the motor in the first torque derating stage according to the first actual derating coefficient and the requested torque of the motor. output torque at the current speed; if the motor is in the second torque derating stage under the motor reversal state, calculate the second theoretical derating coefficient corresponding to the second torque derating stage under the motor reversal state according to the second derating slope, the current target speed and the second derating endpoint threshold; if the second theoretical derating coefficient is less than or equal to zero, zero is determined as the second actual derating coefficient corresponding to the second torque derating stage; if the second theoretical derating coefficient is greater than or equal to 1, 1 is determined as the second actual derating coefficient corresponding to the second torque derating stage; determine the output torque of the motor at the current speed according to the second actual derating coefficient and the output torque corresponding to the second torque derating stage.

[0014] In a possible implementation, the method also includes: if the target permanent magnet synchronous motor is in a first torque derating stage, controlling the derating recovery of the target permanent magnet synchronous motor according to a fast recovery mode, and the fast recovery mode is that the output torque recovers to the requested torque as the speed of the target permanent magnet synchronous motor decreases; if the target permanent magnet synchronous motor is in a second torque derating stage, controlling the derating recovery of the target permanent magnet synchronous motor according to a slow recovery mode, and the slow recovery mode is to maintain the current output torque of the target permanent magnet synchronous motor.

[0015] In the second aspect, an embodiment of the present application also provides a torque derating control device for a permanent magnet synchronous motor. In a possible implementation, the device includes: an acquisition module, used to acquire the current speed of the target permanent magnet synchronous motor; a derating strategy determination module, used to determine the torque derating strategy corresponding to the current speed according to the motor rotation direction indicated by the current speed, the torque derating strategy indicating multiple torque derating stages, and different torque derating stages corresponding to different derating slopes; a torque derating stage determination module, used to determine the target torque derating stage of the current speed according to the current speed and the torque derating strategy corresponding to the current speed; a derating slope determination module, used to determine the target derating slope corresponding to the target torque derating stage according to the target torque derating stage; a derating control module, used to control the output torque of the target permanent magnet synchronous motor to be derated at the target derating slope.

[0016] The embodiment of the present application provides a method and device for controlling torque derating of a permanent magnet synchronous motor, including: collecting the current speed of the target permanent magnet synchronous motor; determining the torque derating strategy corresponding to the current speed according to the motor rotation direction indicated by the current speed, the torque derating strategy indicating multiple torque derating stages, and different torque derating stages corresponding to different derating slopes; determining the target torque derating stage of the current speed according to the current speed and the torque derating strategy corresponding to the current speed; determining the target derating slope corresponding to the target torque derating stage according to the target torque derating stage; controlling the output torque of the target permanent magnet synchronous motor to be derated at the target derating slope. The present application performs torque derating of different speeds according to the actual overspeed situation of the motor, thereby improving the protection effect of the permanent magnet synchronous motor on the motor when applied to different overspeed conditions.

[0017] In order to make the above-mentioned objects, features and advantages of the present application more obvious and easy to understand, preferred embodiments are specifically cited below and described in detail with reference to the attached drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0019] Figure 1 A flow chart of a torque derating control method for a permanent magnet synchronous motor provided in an embodiment of the present application is shown;

[0020] Figure 2 A functional module diagram of a torque derating control device for a permanent magnet synchronous motor provided in an embodiment of the present application is shown;

[0021] Figure 3 A schematic structural diagram of an electronic device provided in an embodiment of the present application is shown. DETAILED DESCRIPTION

[0022] To make the purpose, technical scheme and advantages of the embodiments of the present application clearer, the technical scheme in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. It should be understood that the drawings in the present application only serve the purpose of explanation and description and are not used to limit the scope of protection of the present application. In addition, it should be understood that the schematic drawings are not drawn in real proportion. The flowchart used in this application shows the operations implemented according to some embodiments of the present application. It should be understood that the operations of the flowchart can be implemented out of sequence, and the steps without logical context can be reversed in order or implemented simultaneously. In addition, those skilled in the art, under the guidance of the content of the present application, can add one or more other operations to the flowchart, or remove one or more operations from the flowchart.

[0023] In addition, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. The components of the embodiments of the present application described and shown in the drawings here can be arranged and designed in various configurations. Therefore, the following detailed description of the embodiments of the present application provided in the drawings is not intended to limit the scope of the application claimed for protection, but merely represents the selected embodiments of the present application. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without making creative work belong to the scope of protection of the present application.

[0024] In the prior art, in order to avoid a series of potential problems such as premature wear or damage of the mechanical parts of the permanent magnet synchronous motor caused by overspeed operation, partial demagnetization of the permanent magnet caused by overheating of the motor, and vehicle driving safety, an overspeed derating mechanism is required when the permanent magnet synchronous motor is running. That is, when the motor is running at an overspeed, the output power of the motor is derating controlled to reduce the motor output power to ensure that the motor operates within a safe speed range. The currently commonly used derating method is to set two fixed derating thresholds, compare the motor temperature with the derating thresholds for linear derating. The disadvantage of this linear derating method is that the derating slope is fixed, so the torque output cannot be adjusted according to the change in motor speed, which reduces the protection effect of the permanent magnet synchronous motor under different overspeed conditions.

[0025] Based on this, the embodiment of the present application provides a method and device for controlling torque derating of a permanent magnet synchronous motor, which performs torque derating at different speeds according to the actual overspeed condition of the motor, thereby improving the protection effect of the permanent magnet synchronous motor on the motor when applied to different overspeed conditions, as follows:

[0026] See also Figure 1 , Figure 1 FIG. 1 is a flow chart showing a method for controlling torque derating of a permanent magnet synchronous motor provided in an embodiment of the present application. Figure 1 As shown, the method provided in the embodiment of the present application comprises the following steps:

[0027] S100: Collect the current rotation speed of the target permanent magnet synchronous motor.

[0028] S200: Determine a torque derating strategy corresponding to the current speed according to the motor rotation direction indicated by the current speed.

[0029] The torque derating strategy indicates a plurality of torque derating stages, and different torque derating stages correspond to different derating slopes.

[0030] S300: Determine a target torque derating stage of the current speed according to the current speed and the torque derating strategy corresponding to the current speed.

[0031] S400: Determine a target derating slope corresponding to the target torque derating stage according to the target torque derating stage.

[0032] S500: Control the output torque of the target permanent magnet synchronous motor to be derated at a target derated slope.

[0033] In a specific implementation, different torque derating stages correspond to different overspeed states of the permanent magnet synchronous motor. The multiple torque derating stages include a first torque derating stage and a second torque derating stage. The first torque derating stage and the second torque derating stage correspond to different derating slopes. The present application determines a torque derating strategy corresponding to the current speed in combination with the current speed of the target permanent magnet synchronous motor and the speed direction indicated by the current speed. In combination with the target torque derating stage matching the current speed, a target derating slope matching the current speed is determined, thereby controlling the derating of the output torque of the target permanent magnet synchronous motor based on the target derating slope. In this process, the process of switching the derating slope corresponding to the output torque of the motor according to the overspeed state of the permanent magnet synchronous motor is realized, that is, torque derating of different speeds is performed according to the actual overspeed situation of the motor, thereby improving the protection effect of the permanent magnet synchronous motor on the motor when applied to different overspeed conditions.

[0034] In a preferred embodiment, the torque derating strategy includes a motor forward rotation derating strategy and a motor reverse rotation derating strategy, wherein the target derating slope corresponding to the current rotation speed is determined by:

[0035] If the current speed is greater than or equal to zero, the motor is determined to be rotating forward, and the target torque derating stage and target derating slope corresponding to the current speed are determined according to the motor forward derating strategy. If the current speed is less than zero, the motor is determined to be rotating reversely, and the target torque derating stage and target derating slope corresponding to the current speed are determined according to the motor reverse derating strategy.

[0036] Specifically, the present application divides the torque derating strategy into a motor forward derating strategy corresponding to the motor forward rotation and a motor reverse derating strategy corresponding to the motor reverse rotation according to the two operating conditions of the permanent magnet synchronous motor, namely, forward rotation and reverse rotation. This realizes dynamic adjustment of the derating strategy by using different derating strategies according to the two different speed conditions of the permanent magnet synchronous motor, namely, forward rotation and reverse rotation. This makes the entire overspeed derating process of the permanent magnet synchronous motor cover more operating conditions and makes the derating control more precise.

[0037] Preferably, the motor forward derating strategy includes a first torque derating stage under the motor forward state and its corresponding first section forward derating starting threshold, first section forward derating end threshold, a second torque derating stage under the motor forward state and its corresponding second section derating starting threshold and second section derating end threshold.

[0038] Among them, 0<first stage positive derating starting point threshold value StartValue1<first stage positive derating ending point threshold value EndValue1=second stage derating starting point threshold value StartValue2<second stage derating ending point threshold value EndValue2.

[0039] In a preferred embodiment, according to the motor forward rotation derating strategy, the step of determining the target derating slope corresponding to the current rotation speed includes:

[0040] If the first section forward derating starting point threshold StartValue1 < current speed Spd ≤ the first section forward derating end point threshold EndValue1, it is determined that the target permanent magnet synchronous motor is in the first torque derating stage in the forward rotation state of the motor, and the first positive derating slope S1 is determined according to the first section forward derating starting point threshold StartValue1 and the first section forward derating end point threshold EndValue1, and the first positive derating slope S1 is determined as the target derating slope.

[0041] If the second derating starting point threshold StartValue2 is less than the current speed Spd≤the second derating end point threshold EndValue2, it is determined that the target permanent magnet synchronous motor is in the second torque derating stage in the forward rotation state of the motor, and the second derating slope S2 is determined according to the second derating starting point threshold StartValue2 and the second derating end point threshold EndValue2, and the second derating slope S2 is determined as the target derating slope.

[0042] Specifically, if the current speed Spd≤the first stage positive derating starting point threshold StartValue1, it is determined that the target permanent magnet synchronous motor is not running at an overspeed. At this time, there is no need to derating the output torque of the motor.

[0043] In the above embodiment, the derating thresholds corresponding to the two torque derating stages (including the starting derating threshold and the ending derating threshold) form two continuous torque derating stages, thereby realizing continuous derating control of the output torque of the target permanent magnet synchronous motor during the forward overspeed operation.

[0044] In a preferred embodiment, the first positive derating slope and the second derating slope are determined by:

[0045] A first difference between a first-stage positive derating starting threshold and a first-stage positive derating ending threshold is calculated, and a ratio between 1 and the first difference is determined as a first positive derating slope. A second difference between a second-stage positive derating starting threshold and a second-stage positive derating ending threshold is calculated, and a ratio between 1 and the second difference is determined as a second derating slope.

[0046] In one example, when the current speed Spd≥0 (the motor rotates forward), the first derating slope S1 corresponding to the first torque derating stage is 1 / (StartValue1-EndValue1), and the second derating slope S2 corresponding to the second torque derating stage is 1 / (StartValue2-EndValue2).

[0047] It can be seen that when there is a need to adjust the first positive derating slope S1 and the second derating slope S2, the present application can adjust the first positive derating slope S1 by pre-adjusting StartValue1 and EndValue1, and adjust the second derating slope S2 by adjusting the second derating starting point threshold StartValue2 and the second derating end point threshold EndValue2. In this way, the derating slope corresponding to the torque derating stage itself can be adjusted or switched, so that the derating slope is no longer single and can cope with more working conditions.

[0048] In a possible implementation, step S500 includes:

[0049] If the motor is in the first torque derating stage in the forward rotation state, the first theoretical derating coefficient is calculated according to the first forward derating slope, the current speed and the first forward derating endpoint threshold. If the first theoretical derating coefficient is less than or equal to zero, zero is determined as the first actual derating coefficient corresponding to the first torque derating stage. If the first theoretical derating coefficient is greater than or equal to 1, 1 is determined as the first actual derating coefficient corresponding to the first torque derating stage. The output torque of the motor at the current speed is determined according to the first actual derating coefficient, the requested torque of the motor, and the torque derating offset corresponding to the first torque derating stage in the forward rotation state of the motor.

[0050] In one example, when the first positive derating starting point threshold StartValue1 < current speed Spd ≤ the first positive derating ending point threshold EndValue1 (i.e., in the first torque derating stage), the first theoretical derating coefficient K1 corresponding to the first torque derating stage is calculated first, that is:

[0051] The first theoretical derating factor K1 =(Spd-EndValue1)×S1.

[0052] Here, when K1≤0, the first actual derating coefficient K1x corresponding to the first torque derating stage is set to 0, and when K1≥1, the first actual derating coefficient K1x corresponding to the first torque derating stage is set to 1, so that the derating coefficient range is maintained between [0, 1].

[0053] If the current speed reaches the first positive derating starting point threshold value StartValue1, the first actual derating coefficient K1x=1; if the current speed reaches the first positive derating ending point threshold value EndValue1, the first actual derating coefficient K1x=0.

[0054] Further, the output torque Trq_Out1 of the target permanent magnet synchronous motor at the current speed Spd (in the first derating stage) is calculated as (Trq_Req-Offset)×K1x+Offset, wherein Trq_Req is the requested torque corresponding to the target permanent magnet synchronous motor, and Offset represents the torque derating offset corresponding to the first derating stage when the current speed Spd≥0. In the present application, when the motor is in the forward rotation state, the torque derating offset corresponding to the first derating stage is Offset (Offset≠0), and the torque derating offset corresponding to the second derating stage is 0. When the first actual derating coefficient K1x=1, the output torque Trq_Out1=Trq_Req, and when the first actual derating coefficient K1x=0, Trq_Out1=Offset, that is, in the first derating stage when the current speed Spd≥0 (motor forward rotation), the output torque corresponding to the target permanent magnet synchronous motor is derated to the torque derating offset Offset at the first derating slope S1 as the speed increases.

[0055] If the motor is in the second torque derating stage, the second theoretical derating coefficient corresponding to the second torque derating stage is calculated according to the second derating slope, the current speed and the second derating endpoint threshold. If the second theoretical derating coefficient is less than or equal to zero, zero is determined as the second actual derating coefficient corresponding to the second torque derating stage. If the second theoretical derating coefficient is greater than or equal to 1, 1 is determined as the second actual derating coefficient corresponding to the second torque derating stage. According to the second actual derating coefficient and the output torque corresponding to the first torque derating stage, the output torque of the motor at the current speed is determined.

[0056] In one example, when the second derating starting point threshold value StartValue2 < current speed Spd ≤ second derating end point threshold value EndValue2 (i.e., in the second torque derating stage), the second theoretical derating coefficient K2 corresponding to the second torque derating stage is calculated first, that is:

[0057] The second theoretical derating factor K2 = (Spd-EndValue2) x S2.

[0058] Here, when K2≤0, the second actual derating coefficient K2x corresponding to the second torque derating stage is set to 0, and when K2≥1, the second actual derating coefficient K2x corresponding to the second torque derating stage is set to 1, so that the derating coefficient range is maintained between [0, 1].

[0059] If the current speed reaches the second derating starting point threshold value StartValue2, the second actual derating coefficient K2x=1; if the current speed reaches the second derating ending point threshold value EndValue2, the second actual derating coefficient K2=0.

[0060] Furthermore, the output torque Trq_Out2=Trq_Out1×K2x of the target permanent magnet synchronous motor at the current speed Spd (in the second derating stage) is calculated, wherein when the second actual derating coefficient K2x=1, the output torque Trq_Out2=Trq_Out1 corresponding to the second derating stage in the forward rotation state of the motor, and when the second actual derating coefficient K2x=0, the output torque Trq_Out2=0 corresponding to the second derating stage, that is, in the second derating stage when the current speed Spd≥0, the output torque corresponding to the target permanent magnet synchronous motor is linearly derated to 0 at the second derating slope S2 as the speed increases.

[0061] In a preferred embodiment, the motor reversal derating strategy includes a first derating stage under the motor reversal state and its corresponding first reverse derating starting threshold StartValue1_Neg, first reverse derating ending threshold EndValue1_Neg, a second derating stage under the motor reversal state and its corresponding second reverse derating starting threshold StartValue2 and second reverse derating ending threshold EndValue2.

[0062] Among them, 0<the first section reverse derating starting point threshold StartValue1_Neg≤the first section reverse derating ending point threshold EndValue1_Neg=the second section derating starting point threshold StartValue2<the second section derating ending point threshold EndValue2.

[0063] In a preferred embodiment, according to the motor reverse derating strategy, the step of determining the target derating slope corresponding to the current speed includes:

[0064] Calculate the absolute value corresponding to the current speed to obtain the current target speed abs(Spd).

[0065] If the first reverse derating starting point threshold StartValue1_Neg<current target speed abs(Spd)≤the first reverse derating end point threshold EndValue1_Neg, then it is determined that the target permanent magnet synchronous motor is in the first torque derating stage in the motor reversal state, and the first reverse derating slope S1_Neg is determined according to the first reverse derating starting point threshold StartValue1_Neg and the first reverse derating end point threshold EndValue1_Neg, and the first reverse derating slope S1_Neg is determined as the target derating slope.

[0066] If the second-stage derating starting threshold StartValue2 is less than the current target speed abs(Spd)≤the second-stage derating end threshold EndValue2, it is determined that the target permanent magnet synchronous motor is in the second torque derating stage under the motor reversal state, and the second derating slope S2 is determined according to the second derating starting threshold StartValue2 and the second derating end threshold EndValue2 corresponding to the second torque derating stage under the motor reversal state, and the second derating slope is determined as the target derating slope.

[0067] Specifically, if the current target speed Spd≤the first-stage reverse derating starting point threshold StartValue1_Neg, it is determined that the target permanent magnet synchronous motor is not running at an overspeed. At this time, there is no need to derating the output torque of the motor.

[0068] Similarly, the first reverse derating starting point threshold StartValue1_Neg, the first reverse derating end point threshold EndValue1_Neg, the second derating starting point threshold StartValue2 and the second derating end point threshold EndValue2 form two continuous torque derating stages under the motor reversal state, thereby realizing continuous derating control of the output torque of the target permanent magnet synchronous motor during reverse overspeed operation.

[0069] In a preferred embodiment, the first reverse derating slope and the second derating slope are determined in the following manner:

[0070] The third difference between the first reverse derating starting point threshold StartValue1_Neg and the first reverse derating ending point threshold EndValue1_Neg is calculated, and the ratio between 1 and the third difference is determined as the first reverse derating slope S1_Neg, that is:

[0071] The first reverse derating slope S1_Neg=1 / (StartValue1_Neg-EndValue1_Neg).

[0072] The calculation method corresponding to the second derating slope S2 is similar to the above, which will not be repeated here. The second derating slope S2 = 1 / (StartValue2-EndValue2).

[0073] Similarly, when there is a need to adjust the first reverse derating slope S1_Neg and the second derating slope S2, the present application can adjust the first reverse derating slope S1_Neg by pre-adjusting StartValue1_Neg and EndValue1_Neg, and adjust the second derating slope S2 by adjusting the second derating starting point threshold StartValue2 and the second derating end point threshold EndValue2. In this way, the derating slope corresponding to the torque derating stage itself can be adjusted or switched, so that the derating slope is no longer single and can cope with more working conditions.

[0074] In a preferred embodiment, step S500 further includes:

[0075] If the motor is in the first torque derating stage in the motor reversal state, the first theoretical derating coefficient is calculated according to the first reverse derating slope, the current target speed and the first reverse derating endpoint threshold. If the first theoretical derating coefficient is less than or equal to zero, zero is determined as the first actual derating coefficient corresponding to the first torque derating stage. If the first theoretical derating coefficient is greater than or equal to 1, 1 is determined as the first actual derating coefficient corresponding to the first torque derating stage. According to the first actual derating coefficient and the requested torque of the motor, the output torque of the motor at the current speed is determined.

[0076] In one example, when the first reverse derating starting point threshold StartValue1_Neg<current target speed abs(Spd)≤the first reverse derating end point threshold EndValue1_Neg (i.e., the first torque derating stage in the motor reversing state), the first theoretical derating coefficient K1 corresponding to the first torque derating stage in the motor reversing state is first calculated, that is:

[0077] The first theoretical derating factor K1 =(abs(Spd)-EndValue1_Neg)×S1_Neg.

[0078] Here, when K1≤0, the first actual derating coefficient K1x corresponding to the first torque derating stage in the motor reversal state is set to 0; when K1≥1, the first actual derating coefficient K1x corresponding to the first torque derating stage in the motor reversal state is set to 1, so that the derating coefficient range remains between [0, 1].

[0079] If the current target speed reaches the first reverse derating starting point threshold value StartValue1_Neg, the first actual derating coefficient K2x=1; if the current target speed reaches the first reverse derating ending point threshold value EndValue1_Neg, the second actual derating coefficient K2=0.

[0080] Further, the output torque Trq_Out1=Trq_Req×K1x of the target permanent magnet synchronous motor at the current target speed abs(Spd) (in the first derating stage) is calculated, wherein Trq_Req is the requested torque corresponding to the target permanent magnet synchronous motor, and the derating biases corresponding to the first derating stage and the second derating stage in the motor reversal state are both 0, so they are not brought in. When the first actual derating coefficient K1x=1, the output torque Trq_Out1=Trq_Req, and when the first actual derating coefficient K1x=0, Trq_Out1=0. It can be seen that when the motor is in the reverse state (Spd<0) and the current target speed abs(Spd) reaches the first reverse derating end threshold EndValue1_Neg, the output torque is derated to 0, which can cope with the rapid torque unloading when the target permanent magnet synchronous motor is running in reverse.

[0081] If the motor is in the second torque derating stage under the motor reversal state, the second theoretical derating coefficient corresponding to the second torque derating stage under the motor reversal state is calculated according to the second derating slope, the current target speed and the second derating endpoint threshold. If the second theoretical derating coefficient is less than or equal to zero, zero is determined as the second actual derating coefficient corresponding to the second torque derating stage. If the second theoretical derating coefficient is greater than or equal to 1, 1 is determined as the second actual derating coefficient corresponding to the second torque derating stage. According to the second actual derating coefficient and the output torque corresponding to the first torque derating stage, the output torque of the motor at the current speed is determined.

[0082] In one example, when the second derating starting point threshold StartValue2 < current target speed abs(Spd) ≤ the second derating end point threshold EndValue2 (i.e., the second torque derating stage in the motor reversal state), the second theoretical derating coefficient K2 corresponding to the second torque derating stage is calculated first, that is:

[0083] The second theoretical derating factor K2 = (abs(Spd) - EndValue2) x S2, wherein abs(Spd) represents the absolute value processing of the current rotation speed Spd to obtain the current target rotation speed abs(Spd).

[0084] Here, when K2≤0, the second actual derating coefficient K2x corresponding to the second torque derating stage in the motor reversal state is set to 0; when K2≥1, the second actual derating coefficient K2x corresponding to the second torque derating stage in the motor reversal state is set to 1, so that the derating coefficient range remains between [0, 1].

[0085] Furthermore, the output torque Trq_Out2=Trq_Out1×K2x of the target permanent magnet synchronous motor at the current target speed abs(Spd) is calculated, wherein when the second actual derating coefficient K2x=1, the output torque Trq_Out2=Trq_Out1 corresponding to the second derating stage, and when the second actual derating coefficient K2x=0, the output torque Trq_Out2=0 corresponding to the second derating stage, that is, in the second derating stage when the current speed Spd<0, the output torque corresponding to the target permanent magnet synchronous motor is linearly derated to 0 with the increase of the speed at the second derating slope S2.

[0086] For the case of forward rotation or reverse rotation of the motor, in the corresponding first torque derating stage and the first torque derating stage, it can be seen from the derating coefficient determination process that when the corresponding speed of the motor decreases, the derating coefficient will increase, that is, the derating recovery is the process in which the output torque recovers to the requested torque as the speed decreases.

[0087] In a preferred embodiment, the method provided by the present application further includes:

[0088] If the target permanent magnet synchronous motor is in the first torque derating stage, the derating recovery of the target permanent magnet synchronous motor is controlled according to the fast recovery mode. The fast recovery mode is that the output torque is restored to the requested torque as the speed of the target permanent magnet synchronous motor decreases. If the target permanent magnet synchronous motor is in the second torque derating stage, the derating recovery of the target permanent magnet synchronous motor is controlled according to the slow recovery mode. The slow recovery mode is to maintain the current output torque of the target permanent magnet synchronous motor.

[0089] The first torque derating stage is the first torque derating stage in the forward rotation state of the motor or the first torque derating stage in the reverse rotation state of the motor.

[0090] Specifically, the application of the two recovery modes (fast recovery mode and slow recovery mode) can avoid the problem that when the motor speed is in the second derating stage and during the recovery process, the torque recovers too quickly, causing the motor speed to rise again.

[0091] In summary, the present application makes up for the shortcoming of the lack of overspeed derating control in the prior art derating control, and performs derating control on the overspeed process of the motor's forward and reverse speeds respectively, thereby improving the diversity of derating strategies, while being compatible with the derating control of overspeed of the motor's forward and reverse speeds. Moreover, regardless of whether it is the motor forward derating control strategy or the motor reverse derating control strategy, two derating slopes are set in the corresponding derating control process, and torque derating and torque derating recovery of different speeds can be performed according to the actual speed of the motor, thereby improving the singleness of the derating and recovery control strategies, and improving the protection effect of the permanent magnet synchronous motor on the motor when applied to different overspeed conditions.

[0092] Based on the same application concept, the embodiments of the present application also provide a torque derating control device for a permanent magnet synchronous motor corresponding to the torque derating control method for a permanent magnet synchronous motor provided in the above embodiments. Since the principle of solving the problem by the device in the embodiments of the present application is similar to the torque derating control method for a permanent magnet synchronous motor in the above embodiments of the present application, the implementation of the device can refer to the implementation of the method, and the repeated parts will not be repeated.

[0093] See also Figure 2 , Figure 2 FIG. 1 shows a functional module diagram of a torque derating control device for a permanent magnet synchronous motor provided in an embodiment of the present application. Figure 2 As shown, the device comprises:

[0094] The acquisition module 600 is used to acquire the current speed of the target permanent magnet synchronous motor;

[0095] A derating strategy determination module 610 is used to determine a torque derating strategy corresponding to the current speed according to the motor rotation direction indicated by the current speed, wherein the torque derating strategy indicates a plurality of torque derating stages, and different torque derating stages correspond to different derating slopes;

[0096] The torque derating stage determination module 620 is used to determine the target torque derating stage of the current speed according to the current speed and the torque derating strategy corresponding to the current speed;

[0097] A derating slope determination module 630 is used to determine a target derating slope corresponding to a target torque derating stage according to the target torque derating stage;

[0098] The derating control module 640 is used to control the output torque of the target permanent magnet synchronous motor to be derated at a target derating slope.

[0099] Based on the same application idea, please refer to Figure 3 , Figure 3 FIG. 1 is a schematic diagram showing the structure of an electronic device provided by an embodiment of the present application. Figure 3As shown, the electronic device 700 includes: a processor 710, a memory 720 and a bus 730. The memory 720 stores machine-readable instructions executable by the processor 710. When the electronic device 700 is running, the processor 710 and the memory 720 communicate through the bus 730. The machine-readable instructions are executed by the processor 710 when it is running, such as the steps of the torque derating control method for a permanent magnet synchronous motor provided in any of the above embodiments.

[0100] Based on the same application concept, an embodiment of the present application also provides a computer-readable storage medium, on which a computer program is stored. When the computer program is executed by a processor, the steps of the torque derating control method of the permanent magnet synchronous motor provided in the above embodiment are executed.

[0101] Those skilled in the art can clearly understand that, for the convenience and simplicity of description, the specific working process of the system and device described above can refer to the corresponding process in the aforementioned method embodiment, and will not be repeated here. In the several embodiments provided in the present application, it should be understood that the disclosed system, device and method can be implemented in other ways. The device embodiments described above are merely schematic. For example, the division of the units is only a logical function division. There may be other division methods in actual implementation. For example, multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some communication interfaces, indirect coupling or communication connection of devices or units, which can be electrical, mechanical or other forms.

[0102] The units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed on multiple network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0103] In addition, each functional unit in each embodiment of the present application may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit.

[0104] If the function is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a non-volatile computer-readable storage medium that is executable by a processor. Based on this understanding, the technical solution of the present application, or the part that contributes to the prior art or the part of the technical solution, can be embodied in the form of a software product, and the computer software product is stored in a storage medium, including a number of instructions to enable a computer device (which can be a personal computer, a server, or a network device, etc.) to perform all or part of the steps of the method described in each embodiment of the present application. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (ROM), random access memory (RAM), disk or optical disk, etc., various media that can store program codes.

[0105] The above are only specific implementations of the present application, but the protection scope of the present application is not limited thereto. Any technician familiar with the technical field can easily think of changes or substitutions within the technical scope disclosed in the present application, which should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

Claims

1. A method for controlling torque derating of a permanent magnet synchronous motor, characterized in that: The method comprises: Collect the current speed of the target permanent magnet synchronous motor; Determining a torque derating strategy corresponding to the current speed according to the motor rotation direction indicated by the current speed, wherein the torque derating strategy indicates a plurality of torque derating stages, and different torque derating stages correspond to different derating slopes; Determining the target torque derating stage of the current speed according to the current speed and the torque derating strategy corresponding to the current speed; According to the target torque derating stage, determining a target derating slope corresponding to the target torque derating stage; The output torque of the target permanent magnet synchronous motor is controlled to be derated at a target derated slope.

2. The method according to claim 1, characterized in that The torque derating strategy includes a motor forward derating strategy and a motor reverse derating strategy. The target derating slope corresponding to the current speed is determined in the following manner: If the current speed is greater than or equal to zero, determining the target torque derating stage and target derating slope corresponding to the current speed according to the motor forward derating strategy; If the current speed is less than zero, the target torque derating stage and the target derating slope corresponding to the current speed are determined according to the motor reverse derating strategy.

3. The method according to claim 2, characterized in that The motor forward derating strategy includes a first torque derating stage under the motor forward state and its corresponding first section forward derating starting threshold, first section forward derating end threshold, a second torque derating stage under the motor forward state and its corresponding second section derating starting threshold and second section derating end threshold, wherein the first section forward derating starting threshold is greater than zero, the first section forward derating starting threshold is less than the first section forward derating end threshold, the first section forward derating end threshold is equal to the second section derating starting threshold, the second section derating starting threshold is less than the second section derating end threshold, The step of determining the target torque derating stage and the target derating slope corresponding to the current speed according to the motor forward rotation derating strategy includes: If the current speed is greater than the first-stage positive derating starting point threshold and less than or equal to the first-stage positive derating ending point threshold, it is determined that the target permanent magnet synchronous motor is in the first torque derating stage; Determine a first forward derating slope according to a first forward derating starting point threshold and a first forward derating ending point threshold, and determine the first forward derating slope as a target derating slope; If the current speed is greater than the second derating starting point threshold and less than or equal to the second derating ending point threshold, it is determined that the target permanent magnet synchronous motor is in the second torque derating stage; A second derating slope is determined according to a second derating starting point threshold and a second derating ending point threshold, and the second derating slope is determined as a target derating slope.

4. The method according to claim 3, characterized in that The first forward derating slope and the second forward derating slope are determined by: Calculating a first difference between a first-stage forward derating starting point threshold and a first-stage forward derating ending point threshold, and determining a ratio between 1 and the first difference as a first derating slope; A second difference between the second derating starting point threshold and the second derating ending point threshold is calculated, and a ratio between 1 and the second difference is determined as a second derating slope.

5. The method according to claim 3, characterized in that: The step of controlling the output torque of the target permanent magnet synchronous motor to be derated at a target derated slope comprises: If the motor is in the first torque derating stage in the forward rotation state of the motor, a first theoretical derating coefficient is calculated according to the first forward derating slope, the current rotation speed and the first forward derating endpoint threshold; If the first theoretical derating coefficient is less than or equal to zero, zero is determined as the first actual derating coefficient corresponding to the first torque derating stage; if the first theoretical derating coefficient is greater than or equal to 1, 1 is determined as the first actual derating coefficient corresponding to the first torque derating stage; determining the output torque of the motor at the current speed according to the first actual derating coefficient, the requested torque of the motor, and the torque derating offset corresponding to the first torque derating stage in the forward rotation state of the motor; If the motor is in the second torque derating stage, calculating a second theoretical derating coefficient corresponding to the second torque derating stage according to the second derating slope, the current speed and the second derating end point threshold; If the second theoretical derating coefficient is less than or equal to zero, zero is determined as the second actual derating coefficient corresponding to the second torque derating stage in the forward rotation state of the motor; if the second theoretical derating coefficient is greater than or equal to 1, 1 is determined as the second actual derating coefficient corresponding to the second torque derating stage in the forward rotation state of the motor; The output torque of the motor at the current speed is determined according to the second actual derating coefficient and the output torque corresponding to the first torque derating stage.

6. The method according to claim 2, characterized in that The motor reversal derating strategy includes a first derating stage under the motor reversal state and its corresponding first section reverse derating starting threshold, first section reverse derating end threshold, a second derating stage under the motor reversal state and its corresponding second section derating starting threshold and second section derating end threshold, wherein the first section reverse derating starting threshold is greater than zero, the first section reverse derating starting threshold is less than the first section reverse derating end threshold, the first section reverse derating end threshold is equal to the second section derating starting threshold, the second section derating starting threshold is less than the second section derating end threshold, Wherein, the step of determining the target derating slope corresponding to the current speed according to the motor reverse derating strategy comprises: Calculate the absolute value corresponding to the current speed to obtain the current target speed; If the current target speed is greater than the first reverse derating starting point threshold and less than or equal to the first reverse derating ending point threshold, it is determined that the target permanent magnet synchronous motor is in the first torque derating stage in the motor reversal state; Determine a first reverse derating slope according to a first reverse derating starting point threshold and a first reverse derating ending point threshold, and determine the first reverse derating slope as a target derating slope; If the current speed is greater than the second derating starting point threshold and less than or equal to the second derating ending point threshold, it is determined that the target permanent magnet synchronous motor is in the second torque derating stage in the motor reversal state; A second derating slope is determined according to a second derating starting point threshold and a second derating ending point threshold corresponding to a second torque derating stage in a motor reversing state, and the second derating slope is determined as a target derating slope.

7. The method according to claim 6, characterized in that The first reverse derating slope and the second derating slope are determined by: Calculating a third difference between a first-stage reverse derating starting point threshold and a first-stage reverse derating ending point threshold, and determining a ratio between 1 and the third difference as a first reverse derating slope; A second difference between the second derating starting point threshold and the second derating ending point threshold is calculated, and a ratio between 1 and the second difference is determined as a second derating slope.

8. The method according to claim 6, characterized in that The step of controlling the output torque of the target permanent magnet synchronous motor to be derated at a target derated slope comprises: If the motor is in the first torque derating stage in the motor reversal state, a first theoretical derating coefficient is calculated according to the first reverse derating slope, the current target speed and the first reverse derating endpoint threshold; If the first theoretical derating coefficient is less than or equal to zero, zero is determined as the first actual derating coefficient corresponding to the first torque derating stage; if the first theoretical derating coefficient is greater than or equal to 1, 1 is determined as the first actual derating coefficient corresponding to the first torque derating stage; determining an output torque of the motor at the current speed according to the first actual derating factor and a requested torque of the motor; If the motor is in the second torque derating stage under the motor reversing state, then calculating the second theoretical derating coefficient corresponding to the second torque derating stage under the motor reversing state according to the second derating slope, the current target speed and the second derating end point threshold; If the second theoretical derating coefficient is less than or equal to zero, zero is determined as the second actual derating coefficient corresponding to the second torque derating stage; if the second theoretical derating coefficient is greater than or equal to 1, 1 is determined as the second actual derating coefficient corresponding to the second torque derating stage; The output torque of the motor at the current speed is determined according to the second actual derating coefficient and the output torque corresponding to the second torque derating stage.

9. The method according to claim 1, characterized in that: The method further comprises: If the target permanent magnet synchronous motor is in the first torque derating stage, the derating recovery of the target permanent magnet synchronous motor is controlled in a fast recovery mode, and the fast recovery mode is that the output torque is restored to the requested torque as the speed of the target permanent magnet synchronous motor decreases; If the target permanent magnet synchronous motor is in the second torque derating stage, the derating recovery of the target permanent magnet synchronous motor is controlled according to a slow recovery mode, and the slow recovery mode is to maintain the current output torque of the target permanent magnet synchronous motor.

10. A torque derating control device for a permanent magnet synchronous motor, characterized in that: The device comprises: An acquisition module, used to acquire the current speed of the target permanent magnet synchronous motor; A derating strategy determination module, configured to determine a torque derating strategy corresponding to the current speed according to the motor rotation direction indicated by the current speed, wherein the torque derating strategy indicates a plurality of torque derating stages, and different torque derating stages correspond to different derating slopes; a torque derating stage determining module, configured to determine a target torque derating stage of a current speed according to the current speed and the torque derating strategy corresponding to the current speed; A derating slope determination module, used to determine a target derating slope corresponding to a target torque derating stage according to the target torque derating stage; The derating control module is used to control the output torque of the target permanent magnet synchronous motor to be derated at a target derating slope.

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