A permanent magnet synchronous motor power protection method, system and motor

Abstract

The present application relates to the field of power protection and control of permanent magnet synchronous motor, especially refers to a kind of permanent magnet synchronous motor power protection method, system and motor, the method is calculated and filtered input power by collecting motor electrical parameters, combined with the power state of over-power frequency count determination;When over-power, the torque limiting curve is divided into constant torque zone and constant power zone according to the turning speed, respectively using corresponding strategy adjusts torque limiting value, after low-pass filtering realizes curve smooth transition, clamp with target instruction torque to obtain output torque;At the same time, it has over-power fault diagnosis (trigger stop or alarm when the number exceeds threshold) and high-power working condition torque coefficient adjustment mechanism.Power protection system includes parameter acquisition, power calculation, multiple judgment units, torque limiting adjustment unit, etc., each unit works cooperatively, can adapt to control scene containing only torque ring or with speed ring, realizes high-precision, high-response power protection, improves the stability and safety of motor operation.

Description

Technical Field

[0001] This invention relates to the field of power protection and control of permanent magnet synchronous motors, and in particular to a power protection method, system and motor for permanent magnet synchronous motors. Background Technology

[0002] Under permanent magnet synchronous motor (PMSM) operating conditions, the motor's input power demand increases synchronously with the increase of external load torque. However, the motor's input power is limited by the rated load capacity of the power supply. When the external load torque is too high, the power supply will enter an overload condition, causing a sharp rise in the temperature of the power module. If this overload condition persists or the overload level exceeds the threshold, it may cause the entire PMSM control system to fail or hardware damage in severe cases. Therefore, it is necessary to effectively limit the input power of the PMSM and, when necessary, accurately identify abnormal power conditions and trigger corresponding protection mechanisms to ensure the safe and stable operation of the PMSM control system.

[0003] Currently, existing technologies for power control of permanent magnet synchronous motors in the industry are mainly divided into two categories: The first method is the torque limiting method: This method indirectly controls the motor's output power by directly limiting the motor's output torque, thereby limiting the motor's input power. Its core logic is based on the electromechanical energy conversion relationship of "power = torque × speed". Under relatively steady-state operating conditions, by constraining the upper limit of torque, the upper limit of power is controlled.

[0004] The second method is the speed command adjustment method: This method collects the motor's output power in real time, compares the actual power with the allowable power threshold, and dynamically adjusts the motor's speed command based on the deviation. When the actual power exceeds the threshold, the speed command is reduced to decrease power demand, ultimately keeping the motor power within the allowable range.

[0005] However, both of the above-mentioned existing technologies have significant shortcomings and are difficult to meet the requirements of high-precision and high-response power control under complex operating conditions:

[0006] The torque limiting method has a relatively crude control logic, relying solely on a single, fixed upper limit for torque constraint without dynamically adjusting the torque limit value based on the motor's real-time operating conditions. This results in low power control accuracy. When the speed fluctuates, the power output corresponding to the same torque will change, easily leading to situations where the torque is within the upper limit but the power exceeds the limit, or the torque is limited but the power is still too low. Furthermore, under heavy loads, the rigid torque limit can cause the motor's output torque to fail to match the load demand, making the motor susceptible to being dragged by the load or seizing due to insufficient torque, potentially leading to motor stall, controller overcurrent, and other malfunctions.

[0007] The speed command adjustment method has limitations in its applicability. It is only suitable for systems with closed-loop speed control, such as fans and pumps that operate at constant speeds. It cannot be applied to applications without speed control, such as precision machine tool spindles and robot joint drives that only require precise torque output. In these cases, the motor does not need a fixed speed, and adjusting the speed command would compromise the accuracy of torque control. Furthermore, this method has a slow response time: adjusting the speed command requires a closed-loop cycle of "power acquisition - deviation calculation - speed adjustment - power feedback," which introduces a time delay. When faced with sudden overloads (such as a sudden increase in load), it cannot quickly reduce power, easily causing the power to continuously exceed limits within the delay window, missing the optimal protection opportunity. Summary of the Invention

[0008] Therefore, the technical problem to be solved by the present invention is to address the technical problems in the existing power protection methods for permanent magnet synchronous motors, such as the torque limiting method being coarse and inaccurate, which is prone to causing faults; the speed adjustment command method being unsuitable for torque control conditions and slow in adjustment; and the lack of effective identification of power anomalies. The present invention aims to achieve higher adjustment speed and power control accuracy, adapt to torque control conditions, and complete power anomaly identification and protection.

[0009] To address the aforementioned technical problems, this invention provides a power protection method, system, and motor for a permanent magnet synchronous motor. The method includes the following steps: S1: During the operation of the permanent magnet synchronous motor, the electrical parameters of the motor are collected in real time, and the input power of the motor is calculated by combining the preset power correction coefficient. The electrical parameters are parameters that reflect the voltage and current status of the motor. S2: Filter the input power to obtain the filtered input power, and determine whether the filtered input power exceeds a preset maximum motor power threshold. If the filtered input power does not exceed the motor's maximum power threshold, determine whether a power reduction adjustment strategy has been implemented during the current motor power-on working cycle: If not executed, return to step S1 and continue to monitor the motor power status in real time; If already executed, proceed to step S5; If the filtered input power exceeds the maximum power threshold of the motor, the number of overpower counts is counted to obtain the current overpower count, and then step S3 is executed. S3: Compare the current overpower count with a preset fault count threshold: If the current overpower count exceeds the fault count threshold, an overpower fault signal is sent to the permanent magnet synchronous motor control system, and corresponding fault handling operations are performed. If the current overpower count does not exceed the fault count threshold, then proceed to step S4; S4: Obtain the current actual speed and current actual torque of the motor. Adjust the initial torque limit curve according to the speed range in which the current actual speed is located to obtain the adjusted torque limit curve. Perform clamping processing based on the adjusted torque limit curve and the target command torque, output the clamped torque command, and return to execute step S1. S5: Determine whether the current motor operating status meets the high-power operating conditions. If the condition is not met, return to step S1. If satisfied, then further determine whether the filtered input power is within a preset reasonable power range: If the filtered input power is within the reasonable power range, then return to step S1. If the filtered input power is not within the reasonable power range, adjust the torque reduction coefficient to make the torque limitation level lower than the previous adjustment level, and execute step S1; The reasonable power range is defined as the power value range between the difference between the maximum power of the motor and a preset power threshold, with the maximum power of the motor as the upper limit and the lower limit as the upper limit.

[0010] In one embodiment of the present invention, in S4, the method for obtaining the adjusted torque limiting curve is as follows: Regarding the current actual torque The actual torque is obtained by performing low-pass filtering. ; According to the preset turning speed The initial torque limiting curve It is divided into a constant torque region and a constant power region, wherein the constant torque region is when the motor speed is less than the preset turning speed. The constant power zone is defined as the range in which the motor speed is greater than the preset turning speed. And less than or equal to the maximum speed of the motor The interval; The actual speed corresponding to the current overpower point When in the constant torque region, based on the actual torque Adjust the initial torque limiting curve according to the following rules. To obtain the adjusted torque limiting curve : when At that time, the adjusted torque limiting curve is obtained. : ; when At that time, the adjusted torque limiting curve is obtained. : ; when If the motor is deemed to be at risk of losing control, the adjustment of the initial torque limit curve is stopped, and the current overpower count continues to accumulate until it exceeds the preset fault count threshold. The actual speed corresponding to the current overpower point When in the constant power region, based on the actual torque The following rules apply only to the initial torque limiting curve. Mid-turn speed Up to the motor's maximum speed Curve segments in the interval Adjustments were made to obtain the constant power region segment of the adjusted torque limiting curve. : when At that time, the constant power region curve segment of the adjusted torque limiting curve is obtained. : ; when At that time, the constant power region curve segment of the adjusted torque limiting curve is obtained. : ; when If the motor is deemed to be at risk of losing control, the adjustment of the initial torque limit curve is stopped, and the current overpower count continues to accumulate until it exceeds the preset fault count threshold. in, Initial torque limiting curve Maximum torque, To reduce the torque coefficient, ; A coefficient greater than 1; The initial torque limit curve at the current actual speed The torque limit value at that location.

[0011] In one embodiment of the present invention, the method further includes: adjusting the initial torque limiting curve. At the same time, maintain the constant power region corresponding to the initial torque limiting curve from 0 to the turning speed. curve segment Unchanged, meaning the constant torque region segment of the adjusted torque limit curve remains unchanged. .

[0012] In one embodiment of the present invention, in S4, the current actual torque It is calculated using the following formula: , in, This represents the number of pole pairs of the motor. It is a permanent magnet flux linkage. For d-axis inductance, It is the q-axis inductance.

[0013] In one embodiment of the present invention, the criteria for determining the high-power operating condition are as follows: Get the current actual speed of the motor and current actual torque Regarding the current actual torque The actual torque is obtained by performing low-pass filtering. ; When the motor's current actual speed greater than the preset turning speed And the actual torque after filtering If so, the current motor operating state is deemed to meet the high-power operating condition conditions; in, A coefficient no greater than 1 For the adjusted torque limit curve and the current speed The corresponding torque limit value.

[0014] In one embodiment of the present invention, in S2, the method for obtaining the current overpower count is as follows: The number of overpower events is counted using an overpower event counter. The initial value of the overpower event counter is zero. Each time the processed input power is detected to exceed the maximum power threshold of the motor, the value of the overpower event counter increases. Add 1 to the current value to update it to the current overpower count.

[0015] In one embodiment of the present invention, in S1, the input power of the motor is calculated. The method is as follows: ,in, This is the d-axis command voltage. This is the q-axis command voltage. For d-axis sampling current, For q-axis sampling current, This is the power correction factor. This is the power correction factor obtained through offline calibration.

[0016] In one embodiment of the present invention, in step S4, the method for outputting the clamped torque command is as follows: The torque limit value corresponding to the adjusted torque limit curve is compared with the target command torque of the motor. The smaller of the two values ​​is compared and obtained as the torque command after clamping. .

[0017] Based on the same inventive concept, the present invention also provides a power protection system for a permanent magnet synchronous motor, comprising: a parameter acquisition unit, a power calculation unit, a first judgment unit, a second judgment unit, a torque limit adjustment unit, a third judgment unit, a fourth judgment unit, and a torque reduction coefficient adjustment unit. The parameter acquisition unit is used to acquire electrical parameters reflecting the voltage and current status of the permanent magnet synchronous motor in real time during operation. The power calculation unit is connected to the parameter acquisition unit and is used to calculate the input power of the motor by combining a preset power correction coefficient, and to filter the input power to obtain the filtered input power. The first judgment unit is connected to the power calculation unit and is used to judge whether the filtered input power exceeds the preset maximum power threshold of the motor. When the filtered input power exceeds the maximum power threshold of the motor, the number of overpower counts is counted to obtain the current overpower count. The second judgment unit is connected to the first judgment unit and is used to compare the current overpower count with a preset fault count threshold. When the current overpower count exceeds the fault count threshold, the second judgment unit sends an overpower fault signal to the permanent magnet synchronous motor control system and performs corresponding fault handling operations. The torque limit adjustment unit is connected to the parameter acquisition unit and the second judgment unit respectively. It is used to obtain the current actual speed and current actual torque of the motor when the current overpower count does not exceed the fault count threshold, adjust the initial torque limit curve according to the speed range in which the current actual speed is located to obtain the adjusted torque limit curve, and output the clamped torque command after clamping the adjusted torque limit curve and the target command torque. The third judgment unit is connected to the first judgment unit and is used to determine whether a power reduction adjustment strategy has been executed during the current motor power-on working cycle when the filtered input power does not exceed the maximum power threshold of the motor. If a power reduction adjustment strategy has been executed, it is determined whether the current motor operating state meets the high power condition conditions. The fourth judgment unit is connected to the third judgment unit and is used to determine whether the filtered input power is within a preset reasonable power range when the high power operating condition is met. The reasonable power range is: the power value range between the lower limit value and the upper limit value, with the difference between the maximum power of the motor and the preset power threshold value as the lower limit value and the maximum power of the motor as the upper limit value. The torque reduction coefficient adjustment unit is connected to the parameter acquisition unit and the fourth judgment unit respectively, and is used to adjust the torque reduction coefficient so that the torque limitation is lower than the limitation of the previous adjustment when the filtered input power is within the reasonable power range.

[0018] In addition, the present invention also provides an electric motor that includes the aforementioned permanent magnet synchronous motor power protection system.

[0019] Compared with the prior art, the above-described technical solution of the present invention has the following advantages: This invention is adaptable to control applications with only a torque loop as well as those with a speed loop, overcoming the limitations of some existing methods in terms of applicable operating conditions. The torque limiting design is sophisticated, dividing the initial torque limiting curve into a constant torque region and a constant power region based on the turning speed. Corresponding formulas are used to adjust the torque limiting value for different regions with overpower conditions, avoiding over-limiting caused by simply limiting torque. Furthermore, a low-pass filter is used to achieve a smooth transition of the torque limiting curve when the speed approaches the turning speed, effectively preventing system overshoot. Simultaneously, a comprehensive fault diagnosis mechanism is incorporated. By counting the number of overpower events and comparing them with a fault count threshold, abnormal power can be identified and reported in a timely manner, taking protective measures such as shutdown or alarm to prevent damage to the control system from overpower. Moreover, it uses the torque range as the adjustment standard, rather than relying on a single torque limit, significantly reducing the risk of system oscillation while balancing high power control accuracy and adjustment speed. Attached Figure Description

[0020] To make the content of this invention easier to understand, the invention will be further described in detail below with reference to specific embodiments and accompanying drawings.

[0021] Figure 1 This is a flowchart illustrating a power protection method for a permanent magnet synchronous motor provided in an embodiment of the present invention. Figure 2 This is a schematic diagram of the torque limiting curve of the permanent magnet synchronous motor provided in the embodiments of the present invention; Figure 3 This is a schematic diagram of the structure of a permanent magnet synchronous motor power protection system provided in an embodiment of the present invention; Explanation of reference numerals in the accompanying drawings: 10 Parameter acquisition unit; 20 Power calculation unit; 30 First judgment unit; 40 Second judgment unit; 50 Torque limit adjustment unit; 60 Third judgment unit; 70 Fourth judgment unit; 80 Torque reduction coefficient adjustment unit. Detailed Implementation

[0022] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, so that those skilled in the art can better understand and implement the present invention. However, the embodiments described are not intended to limit the present invention.

[0023] This embodiment provides a power protection method for permanent magnet synchronous motors, aiming to solve the problems of coarse torque limiting control, limited applicability and slow adjustment of speed adjustment command methods, and lack of effective power anomaly identification in existing technologies. It achieves high-precision and high-responsiveness power protection, and the process can be referred to... Figure 1 The specific steps are as follows: Step S1: During the operation of the permanent magnet synchronous motor, electrical parameters reflecting the voltage and current status of the motor are collected in real time through the parameter acquisition module. These electrical parameters specifically include the d-axis command voltage. q-axis command voltage d-axis sampling current and q-axis sampling current Combined with the preset power correction coefficient The input power of the motor can be calculated using the following formula. :

[0024] ,

[0025] in, To obtain the coefficients through offline calibration, the calibration process needs to be carried out under various typical operating conditions such as motor no-load and rated load to ensure the accuracy of input power calculation under different operating conditions. After completing the input power calculation, proceed to step S2.

[0026] Step S2: Calculate the input power obtained in step S1. A low-pass filter is used to filter out high-frequency interference in the power signal, resulting in the filtered input power. .

[0027] Will With the preset maximum power threshold of the motor The comparison is handled in two ways:

[0028] like Determine whether the power reduction adjustment strategy has been executed during the current motor power-on working cycle: if not, return to step S1 to continue monitoring the motor power status in real time; if it has been executed, proceed to step S5.

[0029] like The number of overpower events is counted using an overpower event counter, which is initially set to 0. Each time an overpower event is detected... At that time, the counter value Add 1 to the current value to obtain the current overpower count, and then proceed to step S3.

[0030] Step S3: Calculate the current overpower count obtained in step S2. Compared with the preset fault count threshold Comparison:

[0031] like If the motor is determined to be in a state of continuous overpower, an overpower fault signal is sent to the permanent magnet synchronous motor control system. The control system then performs shutdown or alarm operations (such as triggering an audible and visual alarm, cutting off the motor power supply circuit, etc.) according to the preset fault management strategy to prevent the control system from being damaged due to long-term overpower.

[0032] like If the current overpower is determined to be instantaneous or adjustable, proceed to step S4.

[0033] Step S4: Calculate the current actual torque of the motor using the following formula. :

[0034] ,

[0035] in, The number of pole pairs of the motor (e.g., a 4-pole motor) ); It is a permanent magnet flux linkage, determined by the characteristics of the permanent magnet in the motor; For d-axis inductance, This is the q-axis inductance. For The actual torque is obtained by performing low-pass filtering. This reduces the impact of torque signal fluctuations on adjustment accuracy.

[0036] like Figure 2 As shown, according to the preset turning speed The initial torque limiting curve Divided into the following two intervals:

[0037] The first interval is the constant torque zone: the actual speed corresponding to the current overpower point. Less than Within this range, the motor can output its maximum torque. , Initial torque limiting curve The maximum torque value;

[0038] The second interval is the constant power zone: the actual speed corresponding to the current overpower point. Greater than or equal to the motor's maximum speed Within a certain range, the torque decreases as the speed increases in order to maintain stable power.

[0039] The actual speed corresponding to the current overpower point When in the constant torque region, based on the actual torque Adjust the initial torque limiting curve according to the following rules. To obtain the adjusted torque limiting curve :

[0040] when At that time, the adjusted torque limiting curve is obtained. :

[0041] ;

[0042] when At that time, the adjusted torque limiting curve is obtained. :

[0043] ;

[0044] when If it is determined that the motor is at risk of running out of control, the adjustment of the initial torque limiting curve is stopped. , so that the current overpower count The count continues to accumulate until it exceeds the preset fault count threshold. This triggers fault protection.

[0045] The actual speed corresponding to the current overpower point When in the constant power region, only the initial torque limiting curve is considered. Mid-turn speed Up to the motor's maximum speed Curve segments in the interval Adjustments were made, from 0 to the turning speed. curve segment Unchanged, that is :

[0046] when At that time, the constant power region curve segment of the adjusted torque limiting curve is obtained. : ; when At that time, the constant power region curve segment of the adjusted torque limiting curve is obtained. : ; when If it is determined that the motor is at risk of running out of control, the adjustment of the initial torque limiting curve is stopped. , so that the current overpower count The count continues to accumulate until it exceeds the preset fault count threshold. This triggers fault protection. in, Initial torque limiting curve Maximum torque, To reduce the torque coefficient, , The larger the value, the stronger the power limitation. A coefficient greater than 1; The initial torque limit curve at the current actual speed The torque limit value at that location.

[0047] In addition, when the motor speed drops to When near, to avoid the torque limiting curve being in The system overshoot was caused by a large drop during the interval switching. exist The curve segments before and after are low-pass filtered again to achieve a smooth transition.

[0048] Adjusted torque limit curve The corresponding torque limit value and the target command torque of the motor The two values ​​are compared, and the smaller value is taken as the torque command after clamping. The output is sent to the motor drive module to reduce the motor torque and control the power. After completion, return to step S1 to continue real-time monitoring.

[0049] Step S5: Obtain the current actual speed of the motor and the filtered actual torque Determine whether the current motor operating status meets the current actual motor speed. greater than the preset turning speed And the actual torque after filtering High-power operating conditions: If the condition is not met, return to step S1. If satisfied, then set the preset reasonable power range as follows: , Power threshold (e.g.) hour, The reasonable range is Further determine the filtered input power. Is it within the preset reasonable power range? If the filtered input power is within the reasonable power range, and the current power reduction is deemed appropriate, then return to step S1. If the filtered input power is not within the reasonable power range, then the bisection method is used to reduce the torque reduction coefficient. This lowers the torque limit compared to the previous adjustment, and then returns to step S1.

[0050] Based on the same inventive concept as the above method, this embodiment also provides a power protection system for a permanent magnet synchronous motor, the structure of which can be referred to in the appendix. Figure 3 It includes a parameter acquisition unit 10, a power calculation unit 20, a first judgment unit 30, a second judgment unit 40, a torque limit adjustment unit 50, a third judgment unit 60, a fourth judgment unit 70, and a torque reduction coefficient adjustment unit 80. The parameter acquisition unit 10 is connected to the motor's voltage sensor, current sensor, and speed sensor (such as an encoder) to collect electrical parameters reflecting the motor's voltage and current status in real time during the operation of the permanent magnet synchronous motor, including the d-axis command voltage. q-axis command voltage d-axis sampling current q-axis sampling current and the current actual speed ; The power calculation unit 20 is connected to the parameter acquisition unit 10 and is used to receive the parameters acquired by the parameter acquisition unit 10. , , , Combined with the preset power correction coefficient Through formula Calculate the input power of the motor Regarding the input power Perform low-pass filtering to obtain the filtered input power. ; The first judgment unit 30 is connected to the power calculation unit 20 and is used to judge the filtered input power. Does it exceed the preset maximum power threshold for the motor? The filtered input power Exceeding the maximum power threshold of the motor At that time, the number of overpower events is counted by an overpower event counter to obtain the current overpower event count. ; The second judgment unit 40 is connected to the first judgment unit 30 and is used to determine the current overpower count. Compared with the preset fault count threshold Comparison: in the current overpower count Exceeding the fault count threshold When the fault occurs, an overpower fault signal is sent to the permanent magnet synchronous motor control system and corresponding fault handling operations are performed; otherwise, an adjustable signal is sent to the torque limiting adjustment unit 50 to trigger torque adjustment. The torque limiting adjustment unit 50 is connected to the parameter acquisition unit 10 and the second judgment unit 40 respectively, and is used to adjust the current overpower count. The fault count threshold was not exceeded. At that time, obtain the actual speed corresponding to the current overpower point of the motor. and current actual torque Based on the current actual speed Adjust the initial torque limit curve within the specified speed range. To obtain the adjusted torque limiting curve Based on the adjusted torque limit curve With target command torque After clamping, output the clamped torque command. The output is sent to the motor drive module to reduce the motor torque in order to control the power; The third judgment unit 60 is connected to the first judgment unit 30 and is used to determine the filtered input power. The maximum power threshold of the motor was not exceeded. When the power reduction adjustment strategy has been executed during the current motor power-on working cycle, it is determined whether the current motor operating status meets the high power condition conditions. The fourth judgment unit 70 is connected to the third judgment unit 60 and is used to judge the filtered input power when the high-power operating condition is met. Whether it is within a preset reasonable power range, wherein the reasonable power range is: based on the maximum power of the motor With preset power threshold The difference is used as the lower limit, based on the maximum power of the motor. The upper limit value is the power value range between the lower limit value and the upper limit value; The torque reduction coefficient adjustment unit 80 is connected to the parameter acquisition unit 10 and the fourth judgment unit 70 respectively, and is used to adjust the filtered input power. When the power is within the reasonable range, adjust the torque reduction coefficient. Adjust the torque limit to a lower level than the previous adjustment, then return to monitoring mode.

[0051] It should be noted that the permanent magnet synchronous motor power protection system proposed in this embodiment is used to implement the aforementioned permanent magnet synchronous motor power protection method. Therefore, the specific implementation of the permanent magnet synchronous motor power protection system can be found in the embodiment section of the aforementioned permanent magnet synchronous motor power protection method. The system has multiple cooperative working modules used to implement steps S1 to S5 in the permanent magnet synchronous motor power protection method in Embodiment 1. Therefore, its specific implementation can be referred to the description of the corresponding embodiments. To avoid redundancy, it will not be repeated here.

[0052] In addition, this embodiment also provides a motor, including the aforementioned permanent magnet synchronous motor power protection system. The system is integrated inside the motor controller and is directly connected to the motor's stator windings (via voltage and current sensors), rotor (via speed sensor), and drive module. It can respond to the motor's operating status in real time and realize power protection.

[0053] This motor can be applied to various equipment such as precision machine tool spindles, robot joint drives (torque loop control only), fans, and water pumps (with speed loop control). Under conditions such as load fluctuations and speed changes, it can achieve high-precision power control through the above methods and systems, avoid overpower damage, and improve operational stability and safety.

[0054] Those skilled in the art will understand that embodiments of this application can be provided as methods, systems, or computer program products. Therefore, this application can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, this application can take the form of a computer program product embodied on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0055] This application is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of this application. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart... Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0056] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0057] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0058] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A power protection method for a permanent magnet synchronous motor, characterized in that, include: S1: During the operation of the permanent magnet synchronous motor, the electrical parameters of the motor are collected in real time, and the input power of the motor is calculated by combining the preset power correction coefficient. The electrical parameters are parameters that reflect the voltage and current status of the motor. S2: Filter the input power to obtain the filtered input power, and determine whether the filtered input power exceeds a preset maximum motor power threshold. If the filtered input power does not exceed the motor's maximum power threshold, determine whether a power reduction adjustment strategy has been implemented during the current motor power-on working cycle: If not executed, return to step S1 and continue to monitor the motor power status in real time; If already executed, proceed to step S5; If the filtered input power exceeds the maximum power threshold of the motor, the number of overpower counts is counted to obtain the current overpower count, and then step S3 is executed. S3: Compare the current overpower count with a preset fault count threshold: If the current overpower count exceeds the fault count threshold, an overpower fault signal is sent to the permanent magnet synchronous motor control system, and corresponding fault handling operations are performed. If the current overpower count does not exceed the fault count threshold, then proceed to step S4; S4: Obtain the current actual speed and current actual torque of the motor. Adjust the initial torque limit curve according to the speed range in which the current actual speed is located to obtain the adjusted torque limit curve. Perform clamping processing based on the adjusted torque limit curve and the target command torque, output the clamped torque command, and return to execute step S1. S5: Determine whether the current motor operating status meets the high-power operating conditions. If the condition is not met, return to step S1. If satisfied, then further determine whether the filtered input power is within a preset reasonable power range: If the filtered input power is not within the reasonable power range, then return to step S1. If the filtered input power is within the reasonable power range, then adjust the torque reduction coefficient to make the torque limitation level lower than the previous adjustment level, and execute step S1; The reasonable power range is defined as the power value range between the difference between the maximum power of the motor and a preset power threshold, with the maximum power of the motor as the upper limit and the lower limit as the upper limit.

2. The power protection method for a permanent magnet synchronous motor according to claim 1, characterized in that, In S4, the method for obtaining the adjusted torque limiting curve is as follows: Regarding the current actual torque The actual torque is obtained by performing low-pass filtering. ; According to the preset turning speed The initial torque limiting curve It is divided into a constant torque region and a constant power region, wherein the constant torque region is when the motor speed is less than the preset turning speed. The constant power zone is defined as the range in which the motor speed is greater than the preset turning speed. And less than or equal to the maximum speed of the motor The interval; The actual speed corresponding to the current overpower point When in the constant torque region, based on the actual torque Adjust the initial torque limiting curve according to the following rules. To obtain the adjusted torque limiting curve : when At that time, the adjusted torque limiting curve is obtained. : ； when At that time, the adjusted torque limiting curve is obtained. : ； when If the motor is deemed to be at risk of losing control, the adjustment of the initial torque limit curve is stopped, and the current overpower count continues to accumulate until it exceeds the preset fault count threshold. The actual speed corresponding to the current overpower point When in the constant power region, based on the actual torque The following rules apply only to the initial torque limiting curve. Mid-turn speed Up to the motor's maximum speed Curve segments in the interval Adjustments were made to obtain the constant power region segment of the adjusted torque limiting curve. : when At that time, the constant power region curve segment of the adjusted torque limiting curve is obtained. : ； when At that time, the constant power region curve segment of the adjusted torque limiting curve is obtained. : ； when If the motor is deemed to be at risk of losing control, the adjustment of the initial torque limit curve is stopped, and the current overpower count continues to accumulate until it exceeds the preset fault count threshold. in, Initial torque limiting curve Maximum torque, To reduce the torque coefficient, ; A coefficient greater than 1; The initial torque limit curve at the current actual speed The torque limit value at that location.

3. The power protection method for a permanent magnet synchronous motor according to claim 2, characterized in that, Also includes: Adjusting the initial torque limiting curve At the same time, maintain the constant power region corresponding to the initial torque limiting curve from 0 to the turning speed. curve segment Unchanged, meaning the constant torque region segment of the adjusted torque limit curve remains unchanged. .

4. The power protection method for a permanent magnet synchronous motor according to claim 1 or 2, characterized in that, In S4, the current actual torque It is calculated using the following formula: ， in, This represents the number of pole pairs of the motor. It is a permanent magnet flux linkage. For d-axis inductance, It is the q-axis inductance.

5. The power protection method for a permanent magnet synchronous motor according to claim 1, characterized in that, In S5, the criteria for determining the high-power operating condition are as follows: Get the current actual speed of the motor and current actual torque Regarding the current actual torque The actual torque is obtained by performing low-pass filtering. ; When the motor's current actual speed greater than the preset turning speed And the actual torque after filtering If so, the current motor operating state is deemed to meet the high-power operating condition conditions; in, A coefficient no greater than 1 For the adjusted torque limit curve and the current speed The corresponding torque limit value.

6. The power protection method for a permanent magnet synchronous motor according to claim 1, characterized in that, In S2, the method for obtaining the current overpower count is as follows: The number of overpower events is counted using an overpower event counter. The initial value of the overpower event counter is zero. Each time the processed input power is detected to exceed the maximum power threshold of the motor, the value of the overpower event counter increases. Add 1 to the current value to update it to the current overpower count.

7. The power protection method for a permanent magnet synchronous motor according to claim 1, characterized in that, In S1, the input power of the motor is calculated. The method is as follows: ， in, This is the d-axis command voltage. This is the q-axis command voltage. For d-axis sampling current, For q-axis sampling current, This is the power correction factor. This is the power correction factor obtained through offline calibration.

8. The power protection method for a permanent magnet synchronous motor according to claim 1, characterized in that, In S4, the method for outputting the clamped torque command is as follows: The torque limit value corresponding to the adjusted torque limit curve is compared with the target command torque of the motor. The smaller of the two values ​​is compared and obtained as the torque command after clamping. .

9. A power protection system for a permanent magnet synchronous motor, characterized in that, include: The parameter acquisition unit is used to acquire electrical parameters reflecting the voltage and current status of the permanent magnet synchronous motor in real time during operation. A power calculation unit, connected to the parameter acquisition unit, is used to calculate the input power of the motor by combining a preset power correction coefficient, and to filter the input power to obtain the filtered input power. The first judgment unit is connected to the power calculation unit and is used to judge whether the filtered input power exceeds the preset maximum power threshold of the motor. When the filtered input power exceeds the maximum power threshold of the motor, the number of over-power counts is counted to obtain the current over-power count. The second judgment unit, connected to the first judgment unit, is used to compare the current overpower count with a preset fault count threshold, and when the current overpower count exceeds the fault count threshold, send an overpower fault signal to the permanent magnet synchronous motor control system and perform corresponding fault handling operations. The torque limit adjustment unit is connected to the parameter acquisition unit and the second judgment unit respectively. When the current overpower count does not exceed the fault count threshold, it acquires the current actual speed and current actual torque of the motor, adjusts the initial torque limit curve according to the speed range in which the current actual speed is located to obtain the adjusted torque limit curve, and outputs the clamped torque command after clamping the adjusted torque limit curve and the target command torque. The third judgment unit, connected to the first judgment unit, is used to determine whether a power reduction adjustment strategy has been executed during the current motor power-on working cycle when the filtered input power does not exceed the maximum power threshold of the motor; and if a power reduction adjustment strategy has been executed, to determine whether the current motor operating state meets the high power condition conditions. The fourth judgment unit, connected to the third judgment unit, is used to determine whether the filtered input power is within a preset reasonable power range when the high power operating condition is met. The reasonable power range is: the power value range between the difference between the maximum power of the motor and the preset power threshold as the lower limit value, the maximum power of the motor as the upper limit value, and the power value between the lower limit value and the upper limit value. The torque reduction coefficient adjustment unit is connected to the parameter acquisition unit and the fourth judgment unit, respectively, and is used to adjust the torque reduction coefficient so that the torque limitation is lower than the limitation of the previous adjustment when the filtered input power is within the reasonable power range.

10. An electric motor, characterized in that, Includes the permanent magnet synchronous motor power protection system as described in claim 9.

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