Motor and control method and device thereof, storage medium and computer program product

Abstract

The invention discloses a motor and a control method and device thereof, a storage medium and a computer program product, and the method comprises the steps: obtaining the operation parameters of the motor under the operation condition of the motor; according to the operation parameters of the motor, whether irreversible demagnetization happens to the motor is determined, and whether the motor enters a weak magnetic working condition is determined; and if the irreversible demagnetization of the motor is determined and the motor is determined to enter a weak magnetic working condition, adjusting a current control angle of the motor so as to compensate the output torque reduced by the irreversible demagnetization of the motor. According to the scheme, the current control angle of the motor is adjusted and the output torque of the motor is improved when the motor generates irreversible demagnetization and the motor is in the weak magnetic working condition, so that the output power of the motor is improved and the energy efficiency of the whole motor system is ensured.

Description

Technical Field

[0001] The present invention belongs to the field of motor technology, and specifically relates to a motor control method, device, motor, storage medium and computer program product, and more particularly to a demagnetization detection and compensation method, device, motor, storage medium and computer program product for a permanent magnet motor. Background Art

[0002] Motors (such as built-in permanent magnet synchronous motors) offer advantages such as high power density, a wide speed regulation range, compact size, and high efficiency, making them widely used in industries such as industry, transportation, home appliances, and healthcare. While permanent magnet motors offer some unsurpassed advantages over other types of motors, they also have some disadvantages. As a type of permanent magnet motor, the permanent magnet has a large specific temperature coefficient (i.e., temperature coefficient), and the remanence of the permanent magnet decreases as the temperature rises. The remanence of the permanent magnet is significantly affected by temperature, and the motor can experience reversible demagnetization during operation. Furthermore, irreversible demagnetization can also occur in strong reverse magnetic fields. Irreversible demagnetization of the motor reduces motor performance and affects the energy efficiency of the entire system.

[0003] The above content is only used to assist in understanding the technical solution of the present invention and does not constitute an admission that the above content is prior art. Summary of the Invention

[0004] The object of the present invention is to provide a motor control method, device, motor, storage medium and computer program product to solve the problem that irreversible demagnetization occurs in motors (such as permanent magnet motors) during operation, which reduces motor performance and affects the energy efficiency of the entire motor system. The present invention achieves the effect of increasing the output torque of the motor by adjusting the current control angle of the motor when irreversible demagnetization occurs in the motor and the motor is in a weak magnetic field condition, thereby increasing the output power of the motor and ensuring the energy efficiency of the entire motor system.

[0005] The present invention provides a method for controlling a motor, comprising: obtaining operating parameters of the motor when the motor is running; determining whether irreversible demagnetization occurs in the motor and whether the motor enters a magnetic weakening operating condition based on the operating parameters of the motor; if it is determined that irreversible demagnetization occurs in the motor and that the motor enters a magnetic weakening operating condition, adjusting a current control angle of the motor to compensate for a decrease in output torque caused by irreversible demagnetization of the motor.

[0006] In some embodiments, when the motor is running, obtaining the operating parameters of the motor includes: at a preset normal temperature, obtaining the current value required for the initial unit torque of the motor at the normal temperature, and obtaining the point at which the motor enters a weakening magnetic condition at the normal temperature; when the motor is running, obtaining the actual temperature of the motor during operation, obtaining the current of the motor under any one of more than one operating conditions during operation, and obtaining the output torque of the motor under the any one operating condition during operation; at the normal temperature, obtaining the current of the motor under the any operating condition at the normal temperature, and obtaining the output torque of the motor under the any operating condition at the preset normal temperature; the current value required for the initial unit torque of the motor at the normal temperature, the point at which the motor enters a weakening magnetic condition at the normal temperature, the actual temperature of the motor during operation, the current of the motor under any one of more than one operating conditions during operation, the output torque of the motor under the any operating condition during operation, the current of the motor under the any operating condition at the normal temperature, and the output torque of the motor under the any operating condition at the normal temperature are used as the operating parameters of the motor.

[0007] In some embodiments, the operating parameters of the motor include: the current value required for the initial unit torque of the motor at the normal temperature, the point at which the motor enters the weak magnetic condition at the normal temperature, the actual temperature of the motor during operation, the current of the motor in any of more than one operating conditions during operation, the output torque of the motor in any of the operating conditions during operation, the current of the motor in any of the operating conditions at the normal temperature, and the output torque of the motor in any of the operating conditions at the normal temperature; determining whether the motor has irreversible demagnetization according to the operating parameters of the motor and determining whether the motor has entered the weak magnetic condition, including: determining whether the motor has irreversible demagnetization according to the actual temperature of the motor during operation ... operating parameters of the motor The torque difference caused by the temperature difference of the motor is determined based on the current under any one of more than one operating conditions during operation; whether the motor has undergone irreversible demagnetization is determined based on the current value required for the initial unit torque of the motor at the normal temperature, the torque difference caused by the temperature difference of the motor, the current of the motor under any one of more than one operating conditions during operation, the output torque of the motor under the any operating condition during operation, the current of the motor under the any operating condition at the normal temperature, and the output torque of the motor under the any operating condition at the normal temperature; if it is determined that the motor has undergone irreversible demagnetization, whether the motor has entered a magnetic weakening condition is determined based on the point at which the motor enters a magnetic weakening condition at the normal temperature.

[0008] In some embodiments, determining the torque difference caused by the temperature difference of the motor based on the actual temperature of the motor during operation and the current of the motor under any one of more than one operating conditions during operation includes: calculating the torque difference caused by the temperature difference of the motor based on the following formula based on the actual temperature of the motor during operation and the current of the motor under any one of more than one operating conditions during operation:

[0009] ΔT=P*α*ψ t0 *(t-t0)*i q ;

[0010] Wherein, ΔT is the torque difference generated by the temperature difference of the motor, P is the number of pole pairs of the motor, and α is the specific temperature coefficient of the permanent magnet. is the permanent magnet flux value of the motor at a preset normal temperature, t is the actual temperature of the motor during operation, t0 is the preset normal temperature, i q It is the q-axis current component in the current of the motor in any one of more than one operating conditions when the motor is running.

[0011] In some embodiments, determining whether irreversible demagnetization occurs in the motor is performed based on the current value required for the initial unit torque of the motor at the normal temperature, the torque difference caused by the temperature difference of the motor, the current of the motor in any of more than one operating conditions when the motor is running, the output torque of the motor in any of the operating conditions when the motor is running, the current of the motor in any of the operating conditions at the normal temperature, and the output torque of the motor in any of the operating conditions at the normal temperature. The method includes: determining whether irreversible demagnetization occurs in the motor based on the torque difference caused by the temperature difference of the motor, the current of the motor in any of more than one operating conditions when the motor is running, and the output torque of the motor in any of the operating conditions at the normal temperature. The output torque under any operating condition, the current of the motor under any operating condition at the normal temperature, and the output torque of the motor under any operating condition at the normal temperature are used to determine whether the current value required for the initial unit torque of the motor at the normal temperature increases; if it is determined that the current value required for the initial unit torque of the motor at the normal temperature increases, then determine whether irreversible demagnetization occurs in the motor; wherein, determining whether the current value required for the initial unit torque of the motor at the normal temperature increases includes: determining whether the following conditions are met, and if so, determining that the current value required for the initial unit torque of the motor at the normal temperature increases:

[0012] I0 / (T0-ΔT)>I / T;

[0013] I / (T0-ΔT)≥(k1~k2)*(I / T);

[0014] Among them, I0 is the current of the motor under any one of more than one operating conditions during operation, T0 is the output torque of the motor under the any operating condition during operation, ΔT is the torque difference caused by the temperature difference of the motor, I is the current of the motor under the any operating condition at the normal temperature, T is the output torque of the motor under the any operating condition at a preset normal temperature, I / T represents the current value required for the initial unit torque of the motor at the normal temperature, k1 and k2 are both calculation coefficients, and k2>k1 is greater than 1.

[0015] In some embodiments, determining whether the motor enters the magnetic weakening condition is based on the point at which the motor enters the magnetic weakening condition at normal temperature, including: if the operating condition of the motor reaches the point at which the motor enters the magnetic weakening condition at normal temperature, determining that the motor enters the magnetic weakening condition; wherein, the operating condition of the motor includes: the speed of the motor, the output torque of the motor, and the terminal voltage of the motor; the point at which the motor enters the magnetic weakening condition at normal temperature includes: at the same speed of the motor, the terminal voltage of the motor reaches the rated voltage of the motor, and the terminal voltage of the motor does not increase with the increase of the output torque of the motor.

[0016] In some embodiments, the current control angle of the motor is adjusted to compensate for the output torque decreased due to irreversible demagnetization of the motor, including: controlling the current control angle of the motor to decrease, so as to reduce the d-axis current component of the motor and increase the q-axis current component of the motor, until the terminal voltage of the motor reaches a preset maximum voltage limit value, thereby compensating for the output torque decreased due to irreversible demagnetization of the motor.

[0017] Matching the above method, the present invention provides a control device for a motor on the other hand, comprising: an acquisition unit, configured to acquire the operating parameters of the motor when the motor is running; a control unit, configured to determine whether the motor has undergone irreversible demagnetization and whether the motor has entered a magnetic weakening condition based on the operating parameters of the motor; the control unit is further configured to adjust the current control angle of the motor if it is determined that the motor has undergone irreversible demagnetization and that the motor has entered a magnetic weakening condition, so as to compensate for the output torque decreased due to irreversible demagnetization of the motor.

[0018] In some embodiments, the acquisition unit acquires the operating parameters of the motor when the motor is running, including: acquiring, at a preset normal temperature, a current value required for an initial unit torque of the motor at the normal temperature, and acquiring a magnetic weakening operating point of the motor at the normal temperature; acquiring, when the motor is running, an actual temperature of the motor during operation, acquiring a current of the motor under any one of more than one operating conditions during operation, and acquiring an output torque of the motor under the any one operating condition; acquiring, at the normal temperature, the current of the motor under any one of the normal temperature conditions, and acquiring an output torque of the motor under the any one of the normal temperature conditions; and using the current value required for the initial unit torque of the motor at the normal temperature, the magnetic weakening operating point of the motor at the normal temperature, the actual temperature of the motor during operation, the current of the motor under any one of more than one operating conditions during operation, the output torque of the motor under the any one of the operating conditions during operation, the current of the motor under the normal temperature conditions, and the output torque of the motor under the normal temperature conditions as the operating parameters of the motor.

[0019] In some embodiments, the operating parameters of the motor include: the current value required for the initial unit torque of the motor at the normal temperature, the point at which the motor enters the weak magnetic condition at the normal temperature, the actual temperature of the motor during operation, the current of the motor in any of more than one operating conditions during operation, the output torque of the motor in any of the operating conditions during operation, the current of the motor in any of the operating conditions at the normal temperature, and the output torque of the motor in any of the operating conditions at the normal temperature; the control unit determines whether the motor has irreversible demagnetization and whether the motor has entered the weak magnetic condition based on the operating parameters of the motor, including: determining the current value required for the initial unit torque of the motor at the normal temperature, and the output torque of the motor in any of the operating conditions at the normal temperature based on the actual temperature of the motor during operation. The method comprises the following steps: determining the torque difference caused by the temperature difference of the motor according to the current of the motor under any one of more than one operating conditions when the motor is running; determining whether the motor has undergone irreversible demagnetization according to the current value required for the initial unit torque of the motor at the normal temperature, the torque difference caused by the temperature difference of the motor, the current of the motor under any one of more than one operating conditions when the motor is running, the output torque of the motor under the any operating condition when the motor is running, the current of the motor under the any operating condition at the normal temperature, and the output torque of the motor under the any operating condition at the normal temperature; if it is determined that the motor has undergone irreversible demagnetization, determining whether the motor has entered a magnetic weakening operating condition according to the point at which the motor enters a magnetic weakening operating condition at the normal temperature.

[0020] In some embodiments, the control unit determines the torque difference caused by the temperature difference of the motor based on the actual temperature of the motor during operation and the current of the motor under any one of more than one operating conditions during operation, including: calculating the torque difference caused by the temperature difference of the motor based on the following formula based on the actual temperature of the motor during operation and the current of the motor under any one of more than one operating conditions during operation:

[0021]

[0022] Wherein, ΔT is the torque difference generated by the temperature difference of the motor, P is the number of pole pairs of the motor, and α is the specific temperature coefficient of the permanent magnet. is the permanent magnet flux value of the motor at a preset normal temperature, t is the actual temperature of the motor during operation, t0 is the preset normal temperature, i q It is the q-axis current component in the current of the motor in any one of more than one operating conditions when the motor is running.

[0023] In some embodiments, the control unit determines whether irreversible demagnetization occurs in the motor based on the current value required for the initial unit torque of the motor at the normal temperature, the torque difference caused by the temperature difference of the motor, the current of the motor in any of more than one operating conditions when the motor is running, the output torque of the motor in any of the operating conditions when the motor is running, the current of the motor in any of the operating conditions at the normal temperature, and the output torque of the motor in any of the operating conditions at the normal temperature, including: determining whether irreversible demagnetization occurs in the motor based on the torque difference caused by the temperature difference of the motor, the current of the motor in any of more than one operating conditions when the motor is running, and the output torque of the motor in any of the operating conditions at the normal temperature. The output torque under any operating condition, the current of the motor under any operating condition at the normal temperature, and the output torque of the motor under any operating condition at the normal temperature are used to determine whether the current value required for the initial unit torque of the motor at the normal temperature increases; if it is determined that the current value required for the initial unit torque of the motor at the normal temperature increases, then determine whether irreversible demagnetization occurs in the motor; wherein, the control unit determines whether the current value required for the initial unit torque of the motor at the normal temperature increases, including: determining whether the following conditions are met, and if so, determining that the current value required for the initial unit torque of the motor at the normal temperature increases:

[0024] I0 / (T0-ΔT)>I / T;

[0025] I / (T0-ΔT)≥(k1~k2)*(I / T);

[0026] Among them, I0 is the current of the motor under any one of more than one operating conditions during operation, T0 is the output torque of the motor under the any operating condition during operation, ΔT is the torque difference caused by the temperature difference of the motor, I is the current of the motor under the any operating condition at the normal temperature, T is the output torque of the motor under the any operating condition at a preset normal temperature, I / T represents the current value required for the initial unit torque of the motor at the normal temperature, k1 and k2 are both calculation coefficients, and k2>k1 is greater than 1.

[0027] In some embodiments, the control unit determines whether the motor enters the magnetic weakening operating condition based on the magnetic weakening operating point at which the motor enters at the normal temperature, including: if the operating condition of the motor reaches the magnetic weakening operating point at which the motor enters at the normal temperature, then determines that the motor enters the magnetic weakening operating condition; wherein, the operating condition of the motor includes: the speed of the motor, the output torque of the motor, and the terminal voltage of the motor; the magnetic weakening operating point at which the motor enters at the normal temperature includes: at the same speed of the motor, the terminal voltage of the motor reaches the rated voltage of the motor, and the terminal voltage of the motor does not increase with the increase of the output torque of the motor.

[0028] In some embodiments, the control unit adjusts the current control angle of the motor to compensate for the decrease in output torque caused by irreversible demagnetization of the motor, including: controlling the current control angle of the motor to decrease, so as to reduce the d-axis current component of the motor and increase the q-axis current component of the motor, until the terminal voltage of the motor reaches a preset maximum voltage limit value, thereby compensating for the decrease in output torque caused by irreversible demagnetization of the motor.

[0029] Matching the above device, the present invention further provides a motor, including: the control device of the motor described above.

[0030] In accordance with the above method, the present invention further provides a storage medium, which includes a stored program, wherein when the program is running, the device where the storage medium is located is controlled to execute the steps of the motor control method described above.

[0031] In accordance with the above method, the present invention further provides a computer program product, comprising a computer program, which implements the steps of the above motor control method when executed by a processor.

[0032] Therefore, the solution of the present invention is for a motor (such as a permanent magnet motor), and at room temperature, the current value I / T required for the initial unit torque of the motor and the point at which the motor enters the weakening magnetic condition are collected; when the motor is running, the temperature of the motor is collected, and the difference Δψ between the permanent magnet flux linkage of the motor when the motor temperature is t and the permanent magnet flux linkage of the motor when the motor temperature is room temperature is calculated, and the torque difference ΔT caused by the temperature difference of the motor is calculated; based on the torque difference ΔT caused by the temperature difference of the motor, it is judged that if the current value I / T required for the unit torque of the motor increases, it is judged that irreversible demagnetization has occurred in the motor, and when it is judged that the motor enters the weakening magnetic condition based on the point at which the motor enters the weakening magnetic condition, the current control angle β of the motor is controlled to decrease until the terminal voltage U of the motor reaches the maximum voltage limit value U max ; Thus, by adjusting the current control angle of the motor when irreversible demagnetization occurs and the motor is in a weak magnetic condition, the output torque of the motor is increased to increase the output power of the motor and ensure the energy efficiency of the entire motor system.

[0033] Other features and advantages of the present invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the present invention.

[0034] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 1 is a flow chart of an embodiment of a method for controlling a motor according to the present invention;

[0036] Figure 2 1 is a flow chart of an embodiment of the method for obtaining the operating parameters of the motor in the present invention;

[0037] Figure 3 1. A flow chart of an embodiment of the method of the present invention for determining whether irreversible demagnetization of the motor occurs and whether the motor enters a magnetic weakening condition;

[0038] Figure 4 1. A flow chart of an embodiment of the method for determining whether irreversible demagnetization occurs in the motor according to the present invention;

[0039] Figure 5 Schematic diagram of the structure of an embodiment of a motor control device of the present invention;

[0040] Figure 6 Schematic diagram of the flow of the demagnetization detection and compensation method of the permanent magnet motor of the present invention;

[0041] Figure 7Schematic diagram of a motor torque comparison curve of the demagnetization detection and compensation method for a permanent magnet motor of the present invention and the control method in a related solution, wherein the red line represents the motor torque curve of the demagnetization detection and compensation method for a permanent magnet motor of the present invention, and the green line represents the motor torque curve of the control method in the related solution;

[0042] Figure 8 Table 1 is the data table for each working condition.

[0043] In conjunction with the accompanying drawings, the reference numerals in the embodiments of the present invention are as follows:

[0044] 102 - acquisition unit; 104 - control unit. DETAILED DESCRIPTION

[0045] To make the objectives, technical solutions, and advantages of the present invention more clear, the technical solutions of the present invention will be clearly and completely described below in conjunction with specific embodiments of the present invention and corresponding drawings. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0046] Considering that motors (such as permanent magnet motors) have irreversible demagnetization during operation, it will reduce the motor performance and affect the energy efficiency of the entire motor system.

[0047] Specifically, when the terminal voltage reaches the maximum output voltage of the driver during the operation of the motor, its operating speed cannot continue to increase. In order to further increase the speed, weak magnetic control must be performed. Through weak magnetic control, the motor system can widen the speed regulation range. The motor of the magnetic levitation blower usually has a high operating speed, and the motor often operates under weak magnetic conditions. When the motor undergoes irreversible demagnetization, under weak magnetic conditions, if the motor controller MCU outputs current according to the control program in the relevant scheme, the motor output torque will drop significantly, reducing the output power of the motor and affecting the performance of the entire motor system (such as the entire blower unit system).

[0048] The control method of the related solution does not determine whether the motor has experienced irreversible demagnetization. Regardless of whether the motor has experienced irreversible demagnetization, the set current output is used under all operating conditions without adjustment. However, after the motor's permanent magnets undergo irreversible demagnetization, the permanent magnet flux decreases. Under field-weakening conditions, the required d-axis current id decreases. If the originally set output currents (d-axis current id and q-axis current iq) are still used, the motor's output torque will decrease. Another reason is that the reduction in permanent magnet flux also causes a decrease in motor torque.

[0049] Therefore, in order to address the problem that after irreversible demagnetization of a permanent magnet motor occurs, under weak magnetic conditions, the motor controller microcontroller unit (MCU) outputs current according to the control program of the relevant scheme, resulting in a significant decrease in the motor output torque, reducing the output power of the motor, affecting the performance of the entire motor system, and reducing the motor efficiency, the solution of the present invention proposes a motor control method, specifically a demagnetization detection and compensation method for a permanent magnet synchronous motor. After detecting that the motor has irreversible demagnetization, under weak magnetic conditions, the current control angle beta (i.e., β) of the motor is adjusted to increase the motor's output torque and increase the motor's output power while keeping the motor current unchanged, thereby ensuring the output performance of the entire motor system (such as a blower unit system) under high-speed conditions, which is beneficial to improving the energy efficiency of the entire motor system.

[0050] According to an embodiment of the present invention, a method for controlling a motor is provided. Figure 1 FIG. 1 is a flow chart of an embodiment of a method of the present invention. The motor control method may include steps S110 to S130.

[0051] In step S110 , when the motor is running, operating parameters of the motor are acquired.

[0052] In step S120 , it is determined whether irreversible demagnetization occurs in the motor and whether the motor enters a field weakening state based on the operating parameters of the motor.

[0053] At step S130, if it is determined that irreversible demagnetization has occurred in the motor and that the motor has entered a magnetic weakening condition, the current control angle of the motor is adjusted to compensate for the decrease in output torque caused by the irreversible demagnetization of the motor; that is, if it is determined that irreversible demagnetization has occurred in the motor and the motor is in a magnetic weakening condition, the motor controller MCU gradually reduces the current control angle beta (i.e., β) to increase the output torque of the motor, compensate for the torque decrease caused by the demagnetization of the motor, and increase the output power of the motor.

[0054] The present invention proposes a demagnetization detection and compensation scheme for a permanent magnet synchronous motor. After detecting that the motor has irreversible demagnetization, the current control angle beta (i.e., β) of the motor is adjusted under weak magnetic conditions. Under the premise that the current of the motor remains unchanged, the output torque of the motor is increased, the output power of the motor is increased, the output capacity of the motor system under high-speed conditions is guaranteed, and the energy efficiency of the blower unit system is improved.

[0055] In some embodiments, the specific process of obtaining the operating parameters of the motor when the motor is running in step S110 is described in the following exemplary embodiments.

[0056] The following combination Figure 2 The flowchart of an embodiment of the method for obtaining the operating parameters of the motor in the present invention further illustrates the specific process of obtaining the operating parameters of the motor in step S110, including steps S210 to S240.

[0057] Step S210, at a preset normal temperature, obtaining the current value required for the initial unit torque of the motor at the normal temperature, and obtaining the point at which the motor enters the weak magnetic field operating condition at the normal temperature; that is, at a preset normal temperature, obtaining the current value I / T required for the initial unit torque of the motor, specifically obtaining the current value I / T required for the initial unit torque of the motor in each of more than one operating condition; at a preset normal temperature, obtaining the point at which the motor enters the weak magnetic field operating condition, specifically obtaining the critical point at which the motor enters the weak magnetic field operating condition.

[0058] Step S220, when the motor is running, obtain the actual temperature of the motor when running, obtain the current of the motor under any one of more than one operating conditions when running, and obtain the output torque of the motor under the any one of the operating conditions when running; that is, when the motor is running, obtain the actual temperature of the motor, such as obtaining the temperature t of the motor; and obtain the current and torque of the motor under any one of more than one operating conditions when running.

[0059] Step S230, at the normal temperature, obtain the current of the motor under the normal temperature in any operating condition, and obtain the output torque of the motor under the preset normal temperature in any operating condition; that is, at the preset normal temperature, under any operating condition among more than one operating conditions, obtain the current of the motor under the any operating condition, and obtain the output torque of the motor under the any operating condition.

[0060] In step S240, the current value required for the initial unit torque of the motor at the normal temperature, the point at which the motor enters the weak magnetic condition at the normal temperature, the actual temperature of the motor during operation, the current of the motor under any of more than one operating conditions during operation, the output torque of the motor under the any operating condition during operation, the current of the motor under the any operating condition at the normal temperature, and the output torque of the motor under the any operating condition at the normal temperature are taken as the operating parameters of the motor.

[0061] When irreversible demagnetization occurs in the motor, under weak magnetic working conditions, if the motor controller MCU outputs current according to the control program of the relevant scheme, the motor output torque will drop significantly, reducing the output power of the motor and affecting the output capacity of the entire motor system. The scheme of the present invention proposes a demagnetization detection and compensation scheme for a permanent magnet synchronous motor, which collects the current value I / T required for the initial unit torque of the motor and the point when the motor enters the weak magnetic working condition, considers the torque difference caused by the temperature difference of the motor, and eliminates the influence of the reversible demagnetization of the motor on the strategy of judging whether the motor has irreversible demagnetization. When it is determined that the motor has irreversible demagnetization and the motor is in a weak magnetic working condition, the motor controller adjusts the current control angle beta (i.e. β) of the motor to increase the output torque of the motor under the same current, compensate for the torque drop caused by the irreversible demagnetization of the motor, increase the output power of the motor, ensure the output capacity of the motor system under high-speed working conditions, and improve the energy efficiency of the blower unit system.

[0062] In some embodiments, the operating parameters of the motor include: the current value required for the initial unit torque of the motor at the normal temperature, the point at which the motor enters the weak magnetic operating condition at the normal temperature, the actual temperature of the motor during operation, the current of the motor under any of more than one operating conditions during operation, the output torque of the motor under any of the operating conditions during operation, the current of the motor under any of the operating conditions at the normal temperature, and the output torque of the motor under any of the operating conditions at the normal temperature.

[0063] For the specific process of determining whether irreversible demagnetization of the motor occurs and whether the motor enters a magnetic weakening condition based on the operating parameters of the motor in step S120, see the following exemplary description.

[0064] The following combination Figure 3 The flowchart of an embodiment of the method of the present invention for determining whether irreversible demagnetization occurs in the motor and whether the motor enters a weak magnetic working condition is shown, further illustrating the specific process of determining whether irreversible demagnetization occurs in the motor and whether the motor enters a weak magnetic working condition in step S120, including: steps S310 to S330.

[0065] Step S310, determining the torque difference caused by the temperature difference of the motor based on the actual temperature of the motor during operation and the current of the motor under any one of more than one operating conditions during operation, such as determining the difference Δψ between the permanent magnet flux linkage of the motor when the motor temperature is t and the permanent magnet flux linkage of the motor when the motor temperature is normal temperature 25°C.

[0066] Step S320, determining whether irreversible demagnetization occurs in the motor based on the current value required for the initial unit torque of the motor at the normal temperature, the torque difference caused by the temperature difference of the motor, the current of the motor in any of more than one operating conditions during operation, the output torque of the motor in any of the operating conditions during operation, the current of the motor in any of the operating conditions at the normal temperature, and the output torque of the motor in any of the operating conditions at the normal temperature.

[0067] Step S330: If it is determined whether the motor has irreversible demagnetization, determine whether the motor has entered a magnetic weakening operating condition according to the magnetic weakening operating condition point at which the motor enters at the normal temperature.

[0068] In the solution of the present invention, the torque difference caused by the temperature difference of the motor (that is, the torque difference caused by the temperature difference of the motor when the motor undergoes reversible demagnetization) is taken into consideration, and whether the motor has undergone irreversible demagnetization is determined based on the current value required for the initial unit torque of the motor. If it is determined that the motor has undergone irreversible demagnetization and the motor is in a weak magnetic condition, the motor controller MCU gradually reduces the current control angle beta (that is, β), thereby increasing the output torque of the motor, compensating for the torque drop caused by the demagnetization of the motor, increasing the output power of the motor, ensuring the output capacity of the motor system under high-speed conditions, and improving the energy efficiency of the blower unit system.

[0069] In some embodiments, determining the torque difference caused by the temperature difference of the motor according to the actual temperature of the motor during operation and the current of the motor under any one of more than one operating conditions during operation in step S310 includes: calculating the torque difference caused by the temperature difference of the motor according to the following formula according to the actual temperature of the motor during operation and the current of the motor under any one of more than one operating conditions during operation:

[0070]

[0071] Wherein, ΔT is the torque difference generated by the temperature difference of the motor, P is the number of pole pairs of the motor, and α is the specific temperature coefficient of the permanent magnet. is the permanent magnet flux value of the motor at a preset normal temperature, t is the actual temperature of the motor during operation, t0 is the preset normal temperature, i q It is the q-axis current component in the current of the motor in any one of more than one operating conditions when the motor is running.

[0072] Figure 6 FIG. 1 is a flow chart of the demagnetization detection and compensation method of the permanent magnet motor of the present invention. Figure 6 As shown, the specific steps of the permanent magnet assisted reluctance motor demagnetization protection method proposed in the solution of the present invention are as follows:

[0073] Step 1: At room temperature, before the motor is used normally, test on a test bench to collect the current value I / T required for the initial unit torque of the motor at various operating points and the critical point at which the motor enters the weak magnetic condition. In this embodiment, the room temperature is 25°C, and then perform step 2.

[0074] Among them, each operating point is usually recorded at every 10Nm (Newton meter) of output torque at every 500rpm (revolutions per minute). The finer the data, the more accurate it is. By fitting the data of the current value I / T required for the initial unit torque of the motor at each operating point, the I / T data under any operating condition can be obtained. Figure 8 Examples are shown in Table 1. Figure 8 Table 1 is the data table for each working condition.

[0075] The critical point for entering the field-weakening condition is typically determined by the motor's terminal voltage. Motor speed, output torque, and terminal voltage are directly proportional. At the same speed, as output torque increases, the terminal voltage gradually increases. When the terminal voltage reaches the motor's rated voltage and no longer increases with output torque, this point is considered the critical point for entering the field-weakening condition at that speed.

[0076] Step 2: While the motor is running, collect the motor temperature t in real time. Calculate the difference Δψ between the permanent magnet flux at temperature t and the motor's normal temperature of 25°C. Then proceed to Step 3. The motor temperature t is measured using a PT100 (platinum resistance thermometer) temperature sensor, which is pre-installed in the motor windings. The temperature measured by the temperature sensor may differ slightly from the permanent magnet temperature, but this is within an acceptable range.

[0077] The calculation formula for the difference Δψ between the permanent magnet flux linkage of the motor when the motor temperature is t and the permanent magnet flux linkage of the motor when the motor temperature is room temperature 25°C is as follows:

[0078] Δψ=αψ 25℃ Δt (1).

[0079] Wherein, Δψ is the difference between the permanent magnet flux linkage of the motor at temperature t and the permanent magnet flux linkage of the motor at room temperature t0 (e.g., t0=25°C); α is the specific temperature coefficient of the permanent magnet, which in this embodiment is -0.12% / °C; ψ 25℃ It is the permanent magnet flux linkage value of the motor when the temperature is room temperature 25℃; Δt is the difference between the real-time temperature t of the motor and t0=25℃, Δt=t-25℃.

[0080] Step 3: Calculate the torque difference ΔT caused by the motor temperature difference, and then proceed to step 4. The formula for calculating the torque difference ΔT caused by the motor temperature difference is as follows:

[0081] ΔT=PΔψiq (2).

[0082] Where ΔT is the torque difference caused by the motor temperature difference; P is the number of motor pole pairs; Δψ is the difference between the permanent magnet flux linkage of the motor at temperature t and the permanent magnet flux linkage of the motor at temperature t0; i q is the q-axis current component.

[0083] In this solution, the torque difference caused by motor temperature differences is considered. The current required per unit torque is used to determine whether the motor has experienced irreversible demagnetization. If demagnetization has occurred and the motor is operating under field-weakening conditions, the current control angle beta is gradually reduced to increase the motor's output torque. Thus, irreversible demagnetization is determined based on the current required per unit torque, while also accounting for the effects of temperature. Once irreversible demagnetization is determined, the current control angle beta (i.e., β) is adjusted under field-weakening conditions to increase the motor's output torque without increasing the motor current.

[0084] In some embodiments, determining whether irreversible demagnetization has occurred in the motor based on an initial current value per unit torque of the motor at room temperature, a torque difference caused by a temperature difference of the motor, a current of the motor in any one of more than one operating conditions during operation, an output torque of the motor in the any operating condition during operation, a current of the motor in the any operating condition at room temperature, and an output torque of the motor in the any operating condition at room temperature includes:

[0085] The following combination Figure 4 The flowchart of an embodiment of the method for determining whether irreversible demagnetization occurs in the motor according to the present invention is shown, which further illustrates the specific process of determining whether irreversible demagnetization occurs in step S320, including: steps S410 to S420.

[0086] Step S410, determining whether the current value required for the initial unit torque of the motor at the normal temperature increases based on the torque difference generated by the temperature difference of the motor, the current of the motor under any of more than one operating conditions during operation, the output torque of the motor under the any operating condition during operation, the current of the motor under the any operating condition at the normal temperature, and the output torque of the motor under the any operating condition at the normal temperature.

[0087] In step S420 , if it is determined that the current value required for the initial unit torque of the motor at the normal temperature increases, it is determined whether irreversible demagnetization occurs in the motor.

[0088] Determining whether the current value required for the initial unit torque of the motor at the normal temperature increases in step S420 includes: determining whether the following conditions are met; if so, determining that the current value required for the initial unit torque of the motor at the normal temperature increases:

[0089] I0 / (T0-ΔT)>I / T;

[0090] I / (T0-ΔT)≥(k1~k2)*(I / T);

[0091] Among them, I0 is the current of the motor under any one of more than one operating conditions during operation, T0 is the output torque of the motor under the any operating condition during operation, ΔT is the torque difference caused by the temperature difference of the motor, I is the current of the motor under the any operating condition at the normal temperature, T is the output torque of the motor under the any operating condition at a preset normal temperature, I / T represents the current value required for the initial unit torque of the motor at the normal temperature, k1 and k2 are both calculation coefficients, and k2>k1 is greater than 1.

[0092] like Figure 6 As shown, the specific steps of the permanent magnet assisted reluctance motor demagnetization protection method proposed in the solution of the present invention are as follows:

[0093] Step 4: Determine whether the current value I / T required for the motor unit torque increases, that is, whether it satisfies formula (3) and formula (4), and then execute step 5:

[0094] I0 / (T0-ΔT)>I / T (3);

[0095] I / (T0-ΔT)≥(101.5%~103%)*(I / T) (4).

[0096] Where I0 is the motor current under any operating condition; T0 is the motor torque under the same operating condition; I is the current under the same operating condition measured at room temperature; and T is the output torque under the same operating condition measured at room temperature. I and T are reference values ​​for each operating condition obtained through experimental testing at room temperature before the motor is put into normal operation. I0 and T0 are the real-time current and torque values ​​of the motor during normal operation.

[0097] Step 5: If the current value I / T required for the unit torque of the motor does not increase, that is, I0 / (T0-ΔT)<I / T, or I / (T0-ΔT)<(101.5%~103%)*(I / T), the motor is operating normally, and the controller does not take any action, that is, returns to step 2.

[0098] If the current value required for the unit torque of the motor increases to a certain extent, that is,

[0099] I0 / (T0-ΔT)>I / T and I / (T0-ΔT)≥(101.5%~103%)*(I / T), that is, the motor

[0100] If the current required per unit torque increases by more than 1.5% to 3%, it is determined that the motor has been demagnetized, and then step 6 is executed.

[0101] In the solution of the present invention, due to the demagnetization of the magnetic steel, under the weak magnetic working condition, the method reduces the d-axis weak magnetic component and increases the q-axis current component, thereby improving the output torque of the motor, compensating for the torque drop caused by the demagnetization of the motor, improving the output power of the motor, ensuring the output capacity of the motor system under high-speed working conditions, and improving the energy efficiency of the blower unit system.

[0102] In some embodiments, in step S330, whether the motor enters the magnetic weakening condition is determined based on the magnetic weakening operating point at which the motor enters the normal temperature, including: if the operating condition of the motor reaches the magnetic weakening operating point at which the motor enters the normal temperature, then determining that the motor enters the magnetic weakening condition.

[0103] The operating conditions of the motor include: the motor speed, the motor output torque, and the motor terminal voltage. The motor entering the field weakening operating point at room temperature includes: at the same motor speed, the motor terminal voltage reaches the rated voltage of the motor, and the motor terminal voltage does not increase with an increase in the motor output torque.

[0104] like Figure 6 As shown, the specific steps of the permanent magnet assisted reluctance motor demagnetization protection method proposed in the solution of the present invention are as follows:

[0105] Step 6: Determine whether the motor enters the field weakening condition: If so, execute step 7; otherwise, terminate the current permanent magnet assisted reluctance motor demagnetization protection program.

[0106] Among them, based on the critical point of the weakening magnetic condition collected at room temperature, it is judged whether the motor has entered the weakening magnetic condition. Specifically, based on the motor terminal voltage, the terminal voltage will increase with the increase of speed and output torque. At the same speed, as the output torque increases, the terminal voltage gradually increases. When the terminal voltage reaches the rated voltage of the motor, it does not increase with the increase of torque. Then this operating point is the critical point for entering the weakening magnetic condition at this speed. For example: if the rated voltage of the motor is 220V, at 3500rpm, 80Nm operating conditions, the terminal voltage is 215V, at 3500rpm, 90Nm operating conditions, the terminal voltage is 218V, at 3500rpm, 100Nm operating conditions, the terminal voltage is 220V, and at 3500rpm, 110Nm operating conditions, the terminal voltage is 220V. Then, the motor begins to enter the weakening magnetic condition at 3500rpm, 100Nm operating conditions.

[0107] In the solution of the present invention, when it is detected that irreversible demagnetization has occurred in the motor and the motor is in a weak magnetic condition, the current control angle beta (i.e., β) of the motor is adjusted to increase the output torque of the motor and compensate for the torque drop caused by the demagnetization of the motor.

[0108] In some embodiments, the current control angle of the motor is adjusted in step S130 to compensate for the output torque decreased due to irreversible demagnetization of the motor, including: controlling the current control angle of the motor to decrease, so as to reduce the d-axis current component of the motor and increase the q-axis current component of the motor, until the terminal voltage of the motor reaches a preset maximum voltage limit value, thereby compensating for the output torque decreased due to irreversible demagnetization of the motor.

[0109] like Figure 6 As shown, the specific steps of the permanent magnet assisted reluctance motor demagnetization protection method proposed in the solution of the present invention are as follows:

[0110] Step 7. The terminal voltage U of the motor refers to the output voltage at both ends of the motor stator winding, which is determined by the rotor flux and rotor speed. The maximum limit value of the motor voltage is U max Usually it is the rated voltage of the motor. According to the critical point of the weak magnetic condition collected at room temperature, it is judged whether the motor has entered the weak magnetic condition. If the motor is in the weak magnetic condition, the motor controller MCU gradually reduces the motor current control angle beta (ie β), reduces id, and increases iq until the terminal voltage U of the motor reaches the maximum voltage limit value U max :

[0111] U=U max (5).

[0112] Among them, the current control angle beta (i.e. β) of the motor is the angle between the stator current vector and the d-axis, and the d-axis usually refers to the magnetic axis direction of the permanent magnet; by adjusting β, the components of the current on the d-axis and q-axis can be controlled, thereby affecting the performance of the motor. Weak magnetic control is to change the magnetic flux by adjusting the d-axis component in the stator current (i.e. d-axis current id). In other words, under high-speed working conditions, the d-axis current id has a demagnetizing effect on the rotor, allowing the motor to meet the terminal voltage limit conditions, so that the motor can operate at a higher speed. In the scheme of the present invention, the above steps have determined that the motor has irreversible demagnetization and the magnetic flux has become smaller. If the motor is not adjusted according to the d-axis current id and q-axis current iq values ​​originally preset in the relevant scheme, the d-axis current id will be too large, the degree of demagnetization will be too large, and the output torque of the motor will decrease. In the solution of the present invention, according to the logic of weak magnetic control, the current control angle beta (i.e., β) is gradually reduced, the d-axis current id is reduced, and the q-axis current iq is increased until the terminal voltage reaches the maximum voltage limit value (rated voltage). In this way, the motor output torque can be increased and the motor output power can be improved without increasing the current.

[0113] Figure 7 This is a schematic diagram of the motor torque comparison curve of the demagnetization detection and compensation method of the permanent magnet motor of the present invention and the control method in the related scheme, wherein the red line represents the motor torque curve of the demagnetization detection and compensation method of the permanent magnet motor of the present invention, and the green line represents the motor torque curve of the control method in the related scheme. Figure 7 In the figure, the vertical axis title is torque and the unit is Nm, and the horizontal axis title is time and the unit is ms; Figure 7 It can be seen that the output torque of the motor in the solution of the present invention is greater than that of the traditional solution.

[0114] The technical solution of this embodiment is adopted. By collecting the current value I / T required for the initial unit torque of the motor and the point at which the motor enters the weak magnetic field operating condition at room temperature for the motor (such as a permanent magnet motor), while the motor is running, the temperature of the motor is collected, and the difference Δψ between the permanent magnet magnetic flux of the motor when the motor temperature is t and the permanent magnet magnetic flux of the motor when the motor temperature is room temperature is calculated, and the torque difference ΔT caused by the temperature difference of the motor is calculated; based on the torque difference ΔT caused by the temperature difference of the motor, it is judged that the current value I / T required for the unit torque of the motor increases, and it is judged that irreversible demagnetization has occurred in the motor. When the motor enters the weak magnetic field operating condition, it is judged that the motor enters the weak magnetic field operating condition according to the point at which the motor enters, and the current control angle β of the motor is controlled to decrease until the terminal voltage U of the motor reaches the maximum voltage limit value U max ; Thus, by adjusting the current control angle of the motor when irreversible demagnetization occurs and the motor is in a weak magnetic condition, the output torque of the motor is increased to increase the output power of the motor and ensure the energy efficiency of the entire motor system.

[0115] According to an embodiment of the present invention, a motor control device corresponding to the motor control method is also provided. Figure 5 FIG2 is a schematic structural diagram of an embodiment of the device of the present invention. The motor control device may include: an acquisition unit 102 and a control unit 104 .

[0116] The acquisition unit 102 is configured to acquire the operating parameters of the motor when the motor is running. The specific functions and processing of the acquisition unit 102 are shown in step S110.

[0117] The control unit 104 is configured to determine whether the motor has irreversible demagnetization and whether the motor has entered a field weakening state based on the operating parameters of the motor. Specific functions and processing of the control unit 104 are described in step S120.

[0118] The control unit 104 is further configured to, if it is determined that the motor has undergone irreversible demagnetization and that the motor has entered a field-weakening condition, adjust the motor's current control angle to compensate for the decrease in output torque caused by the irreversible demagnetization. In other words, if it is determined that the motor has undergone irreversible demagnetization and is in a field-weakening condition, the motor controller MCU gradually reduces the current control angle beta (i.e., β) to increase the motor's output torque, compensate for the decrease in torque caused by the motor's demagnetization, and increase the motor's output power. The specific functions and processing of the control unit 104 are further described in step S130.

[0119] The present invention proposes a demagnetization detection and compensation scheme for a permanent magnet synchronous motor. After detecting that the motor has irreversible demagnetization, the current control angle beta (i.e., β) of the motor is adjusted under weak magnetic conditions. Under the premise that the current of the motor remains unchanged, the output torque of the motor is increased, the output power of the motor is increased, the output capacity of the motor system under high-speed conditions is guaranteed, and the energy efficiency of the blower unit system is improved.

[0120] In some embodiments, the acquiring unit 102 acquires the operating parameters of the motor when the motor is running, including:

[0121] The acquisition unit 102 is further configured to, at a preset normal temperature, acquire the current value required for the initial unit torque of the motor at the preset normal temperature and acquire the point at which the motor enters a field weakening operating condition at the preset normal temperature. Specifically, the acquisition unit 102 acquires the current value I / T required for the initial unit torque of the motor at the preset normal temperature, specifically acquiring the current value I / T required for the initial unit torque of the motor under each of one or more operating conditions; and acquires the point at which the motor enters a field weakening operating condition at the preset normal temperature, specifically acquiring the critical point at which the motor enters a field weakening operating condition. The specific functions and processing of the acquisition unit 102 are further described in step S210.

[0122] The acquisition unit 102 is further configured to, when the motor is running, acquire the actual temperature of the motor, acquire the current of the motor under any one of more than one operating conditions, and acquire the output torque of the motor under the operating condition. Specifically, when the motor is running, the acquisition unit 102 acquires the actual temperature of the motor, such as the temperature t of the motor, and acquires the current and torque of the motor under any one of more than one operating conditions. The specific functions and processing of the acquisition unit 102 are further described in step S220.

[0123] The acquisition unit 102 is further configured to, at the normal temperature, acquire the current of the motor under any operating condition at the normal temperature, and acquire the output torque of the motor under any operating condition at the preset normal temperature. That is, at the preset normal temperature, in any one of more than one operating conditions, acquire the current of the motor under the any operating condition, and acquire the output torque of the motor under the any operating condition. The specific functions and processing of the acquisition unit 102 are further described in step S230.

[0124] The acquisition unit 102 is further configured to use the current required for the initial unit torque of the motor at room temperature, the point at which the motor enters the field weakening operating condition at room temperature, the actual temperature of the motor during operation, the current of the motor under any of more than one operating conditions during operation, the output torque of the motor under the operating condition, the current of the motor under the operating condition at room temperature, and the output torque of the motor under the operating condition at room temperature as the operating parameters of the motor. The specific functions and processing of the acquisition unit 102 are further described in step S240.

[0125] When irreversible demagnetization occurs in the motor, under weak magnetic working conditions, if the motor controller MCU outputs current according to the control program of the relevant scheme, the motor output torque will drop significantly, reducing the output power of the motor and affecting the output capacity of the entire motor system. The scheme of the present invention proposes a demagnetization detection and compensation scheme for a permanent magnet synchronous motor, which collects the current value I / T required for the initial unit torque of the motor and the point when the motor enters the weak magnetic working condition, considers the torque difference caused by the temperature difference of the motor, and eliminates the influence of the reversible demagnetization of the motor on the strategy of judging whether the motor has irreversible demagnetization. When it is determined that the motor has irreversible demagnetization and the motor is in a weak magnetic working condition, the motor controller adjusts the current control angle beta (i.e. β) of the motor to increase the output torque of the motor under the same current, compensate for the torque drop caused by the irreversible demagnetization of the motor, increase the output power of the motor, ensure the output capacity of the motor system under high-speed working conditions, and improve the energy efficiency of the blower unit system.

[0126] In some embodiments, the operating parameters of the motor include: the current value required for the initial unit torque of the motor at the normal temperature, the point at which the motor enters the weak magnetic operating condition at the normal temperature, the actual temperature of the motor during operation, the current of the motor under any of more than one operating conditions during operation, the output torque of the motor under any of the operating conditions during operation, the current of the motor under any of the operating conditions at the normal temperature, and the output torque of the motor under any of the operating conditions at the normal temperature.

[0127] The control unit 104 determines whether irreversible demagnetization occurs in the motor and whether the motor enters a field weakening state according to the operating parameters of the motor, including:

[0128] The control unit 104 is further configured to determine a torque difference caused by a temperature difference in the motor based on the actual temperature of the motor during operation and the current of the motor under any one of one or more operating conditions during operation, such as determining a difference Δψ between the permanent magnet flux linkage of the motor when the motor temperature is t and the permanent magnet flux linkage of the motor when the motor temperature is a normal temperature of 25°C. The specific functions and processing of the control unit 104 are further described in step S310.

[0129] The control unit 104 is further configured to determine whether irreversible demagnetization has occurred in the motor based on the current required for the initial unit torque of the motor at room temperature, the torque difference caused by the temperature difference of the motor, the current of the motor under any one of more than one operating conditions during operation, the output torque of the motor under the operating condition during operation, the current of the motor under the operating condition at room temperature, and the output torque of the motor under the operating condition at room temperature. The specific functions and processing of the control unit 104 are further described in step S320.

[0130] The control unit 104 is further configured to determine whether the motor has entered a field weakening operating state based on the field weakening operating point of the motor at room temperature if irreversible demagnetization has occurred. The specific functions and processing of the control unit 104 are further described in step S330.

[0131] In the solution of the present invention, the torque difference caused by the temperature difference of the motor (that is, the torque difference caused by the temperature difference of the motor when the motor undergoes reversible demagnetization) is taken into consideration, and whether the motor has undergone irreversible demagnetization is determined based on the current value required for the initial unit torque of the motor. If it is determined that the motor has undergone irreversible demagnetization and the motor is in a weak magnetic condition, the motor controller MCU gradually reduces the current control angle beta (that is, β), thereby increasing the output torque of the motor, compensating for the torque drop caused by the demagnetization of the motor, increasing the output power of the motor, ensuring the output capacity of the motor system under high-speed conditions, and improving the energy efficiency of the blower unit system.

[0132] In some embodiments, the control unit 104 determines the torque difference caused by the temperature difference of the motor based on the actual temperature of the motor during operation and the current of the motor under any one of more than one operating conditions during operation, including: the control unit 104 is further configured to calculate the torque difference caused by the temperature difference of the motor based on the actual temperature of the motor during operation and the current of the motor under any one of more than one operating conditions during operation according to the following formula:

[0133]

[0134] Wherein, ΔT is the torque difference generated by the temperature difference of the motor, P is the number of pole pairs of the motor, and α is the specific temperature coefficient of the permanent magnet. is the permanent magnet flux value of the motor at a preset normal temperature, t is the actual temperature of the motor during operation, t0 is the preset normal temperature, i q It is the q-axis current component in the current of the motor in any one of more than one operating conditions when the motor is running.

[0135] Figure 6 FIG. 1 is a flow chart of the demagnetization detection and compensation method of the permanent magnet motor of the present invention. Figure 6 As shown, the specific steps of the permanent magnet assisted reluctance motor demagnetization protection method proposed in the solution of the present invention are as follows:

[0136] Step 1: At room temperature, collect the current value I / T required for the initial unit torque of the motor at each operating point, and collect the critical point at which the motor enters the weak magnetic condition. In this embodiment, the room temperature is 25° C., and then execute step 2.

[0137] Among them, each operating point is usually recorded at every 10Nm (Newton meter) of output torque at every 500rpm (revolutions per minute). The finer the data, the more accurate it is. By fitting the data of the current value I / T required for the initial unit torque of the motor at each operating point, the I / T data under any operating condition can be obtained. Figure 8 Examples are shown in Table 1. Figure 8 Table 1 is the data table for each working condition.

[0138] The critical point for entering the field-weakening condition is typically determined by the motor's terminal voltage. Motor speed, output torque, and terminal voltage are directly proportional. At the same speed, as output torque increases, the terminal voltage gradually increases. When the terminal voltage reaches the motor's rated voltage and no longer increases with output torque, this point is considered the critical point for entering the field-weakening condition at that speed.

[0139] Step 2: While the motor is running, collect the motor temperature t in real time. Calculate the difference Δψ between the permanent magnet flux at temperature t and the motor's normal temperature of 25°C. Then proceed to Step 3. The motor temperature t is measured using a PT100 (platinum resistance thermometer) temperature sensor, which is pre-installed in the motor windings. The temperature measured by the temperature sensor may differ slightly from the permanent magnet temperature, but this is within an acceptable range.

[0140] The calculation formula for the difference Δψ between the permanent magnet flux linkage of the motor when the motor temperature is t and the permanent magnet flux linkage of the motor when the motor temperature is room temperature 25°C is as follows:

[0141] Δψ=αψ 25℃ Δt (1).

[0142] Wherein, Δψ is the difference between the permanent magnet flux linkage of the motor at temperature t and the permanent magnet flux linkage of the motor at room temperature t0 (e.g., t0=25°C); α is the specific temperature coefficient of the permanent magnet, which in this embodiment is -0.12% / °C; ψ 25℃ It is the permanent magnet flux linkage value of the motor when the temperature is room temperature 25℃; Δt is the difference between the real-time temperature t of the motor and t0=25℃, Δt=t-25℃.

[0143] Step 3: Calculate the torque difference ΔT caused by the motor temperature difference, and then proceed to step 4. The formula for calculating the torque difference ΔT caused by the motor temperature difference is as follows:

[0144] ΔT=PΔψi q (2).

[0145] Where ΔT is the torque difference caused by the motor temperature difference; P is the number of motor pole pairs; Δψ is the difference between the permanent magnet flux linkage of the motor at temperature t and the permanent magnet flux linkage of the motor at temperature t0; i q is the q-axis current component.

[0146] In this solution, the torque difference caused by motor temperature differences is considered. The current required per unit torque is used to determine whether the motor has experienced irreversible demagnetization. If demagnetization has occurred and the motor is operating under field-weakening conditions, the current control angle beta is gradually reduced to increase the motor's output torque. Thus, irreversible demagnetization is determined based on the current required per unit torque, while also accounting for the effects of temperature. Once irreversible demagnetization is determined, the current control angle beta (i.e., β) is adjusted under field-weakening conditions to increase the motor's output torque without increasing the motor current.

[0147] In some embodiments, the control unit 104 determines whether irreversible demagnetization occurs in the motor based on the current value required for the initial unit torque of the motor at the normal temperature, the torque difference caused by the temperature difference of the motor, the current of the motor in any one of more than one operating conditions during operation, the output torque of the motor in the any operating condition during operation, the current of the motor in the any operating condition at the normal temperature, and the output torque of the motor in the any operating condition at the normal temperature, including:

[0148] The control unit 104 is further configured to determine whether the initial unit torque required current value of the motor at normal temperature has increased based on the torque difference generated by the temperature difference of the motor, the current of the motor under any of the one or more operating conditions during operation, the output torque of the motor under the any operating condition during operation, the current of the motor under the any operating condition at normal temperature, and the output torque of the motor under the any operating condition at normal temperature. The specific functions and processing of the control unit 104 are further described in step S410.

[0149] The control unit 104 is further configured to determine whether irreversible demagnetization has occurred in the motor if it is determined that the current value required for the initial unit torque of the motor at the normal temperature has increased. The specific functions and processing of the control unit 104 are further described in step S420.

[0150] The control unit 104 determines whether the current value required for the initial unit torque of the motor at the normal temperature increases, including: the control unit 104 is further configured to determine whether the following conditions are met, and if so, determine that the current value required for the initial unit torque of the motor at the normal temperature increases:

[0151] I0 / (T0-ΔT)>I / T;

[0152] I / (T0-ΔT)≥(k1~k2)*(I / T);

[0153] Among them, I0 is the current of the motor under any one of more than one operating conditions during operation, T0 is the output torque of the motor under the any operating condition during operation, ΔT is the torque difference caused by the temperature difference of the motor, I is the current of the motor under the any operating condition at the normal temperature, T is the output torque of the motor under the any operating condition at a preset normal temperature, I / T represents the current value required for the initial unit torque of the motor at the normal temperature, k1 and k2 are both calculation coefficients, and k2>k1 is greater than 1.

[0154] like Figure 6 As shown, the specific steps of the permanent magnet assisted reluctance motor demagnetization protection method proposed in the solution of the present invention are as follows:

[0155] Step 4: Determine whether the current value I / T required for the motor unit torque increases, that is, whether it satisfies formula (3) and formula (4), and then execute step 5:

[0156] I0 / (T0-ΔT)>I / T (3);

[0157] I / (T0-ΔT)≥(101.5%~103%)*(I / T) (4).

[0158] Wherein, I0 is the motor current under any operating condition when the motor is running; T0 is the motor torque under the same operating condition; I is the current under the same operating condition collected at room temperature; T is the output torque under the same operating condition collected at room temperature.

[0159] Step 5: If the current value I / T required for the unit torque of the motor does not increase, that is, I0 / (T0-ΔT)<I / T, or I / (T0-ΔT)<(101.5%~103%)*(I / T), the motor is operating normally, and the controller does not take any action, that is, returns to step 2.

[0160] If the current value required per unit torque of the motor increases to a certain extent, that is, I0 / (T0-ΔT)>I / T and I / (T0-ΔT)≥(101.5%~103%)*(I / T) are satisfied at the same time, that is, the current value required per unit torque of the motor increases by more than 1.5%~3%, it is determined that the motor has been demagnetized, and then step 6 is executed.

[0161] In the solution of the present invention, due to the demagnetization of the magnetic steel, under the weak magnetic working condition, the method reduces the d-axis weak magnetic component and increases the q-axis current component, thereby improving the output torque of the motor, compensating for the torque drop caused by the demagnetization of the motor, improving the output power of the motor, ensuring the output capacity of the motor system under high-speed working conditions, and improving the energy efficiency of the blower unit system.

[0162] In some embodiments, the control unit 104 determines whether the motor enters the magnetic weakening operating condition based on the magnetic weakening operating point at which the motor enters the normal temperature, including: the control unit 104 is specifically configured to determine that the motor enters the magnetic weakening operating condition if the operating condition of the motor reaches the magnetic weakening operating point at which the motor enters the normal temperature.

[0163] The operating conditions of the motor include: the motor speed, the motor output torque, and the motor terminal voltage. The motor entering the field weakening operating point at room temperature includes: at the same motor speed, the motor terminal voltage reaches the rated voltage of the motor, and the motor terminal voltage does not increase with an increase in the motor output torque.

[0164] like Figure 6As shown, the specific steps of the permanent magnet assisted reluctance motor demagnetization protection method proposed in the solution of the present invention are as follows:

[0165] Step 6: Determine whether the motor enters the field weakening condition: If so, execute step 7; otherwise, terminate the current permanent magnet assisted reluctance motor demagnetization protection program.

[0166] Among them, based on the critical point of the weakening magnetic condition collected at room temperature, it is judged whether the motor has entered the weakening magnetic condition. Specifically, based on the motor terminal voltage, the terminal voltage will increase with the increase of speed and output torque. At the same speed, as the output torque increases, the terminal voltage gradually increases. When the terminal voltage reaches the rated voltage of the motor, it does not increase with the increase of torque. Then this operating point is the critical point for entering the weakening magnetic condition at this speed. For example: if the rated voltage of the motor is 220V, at 3500rpm, 80Nm operating conditions, the terminal voltage is 215V, at 3500rpm, 90Nm operating conditions, the terminal voltage is 218V, at 3500rpm, 100Nm operating conditions, the terminal voltage is 220V, and at 3500rpm, 110Nm operating conditions, the terminal voltage is 220V. Then, the motor begins to enter the weakening magnetic condition at 3500rpm, 100Nm operating conditions.

[0167] In the solution of the present invention, when it is detected that irreversible demagnetization has occurred in the motor and the motor is in a weak magnetic condition, the current control angle beta (i.e., β) of the motor is adjusted to increase the output torque of the motor and compensate for the torque drop caused by the demagnetization of the motor.

[0168] In some embodiments, the control unit 104 adjusts the current control angle of the motor to compensate for the decrease in output torque caused by irreversible demagnetization of the motor, including: the control unit 104 is specifically configured to control the current control angle of the motor to decrease, so as to reduce the d-axis current component of the motor and increase the q-axis current component of the motor until the terminal voltage of the motor reaches a preset maximum voltage limit value, thereby compensating for the decrease in output torque caused by irreversible demagnetization of the motor.

[0169] like Figure 6 As shown, the specific steps of the permanent magnet assisted reluctance motor demagnetization protection method proposed in the solution of the present invention are as follows:

[0170] Step 7: Based on the critical point of the weak magnetic condition collected at room temperature, determine whether the motor has entered the weak magnetic condition. If the motor is in the weak magnetic condition, the motor controller MCU gradually reduces the motor current control angle beta (i.e. β), reduces id, and increases iq until the terminal voltage U of the motor reaches the maximum voltage limit value U max :

[0171] U=U max (5).

[0172] Among them, the current control angle beta (i.e. β) of the motor is the angle between the stator current vector and the d-axis, and the d-axis usually refers to the magnetic axis direction of the permanent magnet; by adjusting β, the components of the current on the d-axis and q-axis can be controlled, thereby affecting the performance of the motor. Weak magnetic control is to change the magnetic flux by adjusting the d-axis component in the stator current (i.e. d-axis current id). In other words, under high-speed working conditions, the d-axis current id has a demagnetizing effect on the rotor, allowing the motor to meet the terminal voltage limit conditions, so that the motor can operate at a higher speed. In the scheme of the present invention, the above steps have determined that the motor has irreversible demagnetization and the magnetic flux has become smaller. If the motor is not adjusted according to the d-axis current id and q-axis current iq values ​​originally preset in the relevant scheme, the d-axis current id will be too large, the degree of demagnetization will be too large, and the output torque of the motor will decrease. In the solution of the present invention, according to the logic of weak magnetic control, the current control angle beta (i.e., β) is gradually reduced, the d-axis current id is reduced, and the q-axis current iq is increased until the terminal voltage reaches the maximum voltage limit value (rated voltage). In this way, the motor output torque can be increased and the motor output power can be improved without increasing the current.

[0173] Figure 7 This is a schematic diagram of the motor torque comparison curve of the demagnetization detection and compensation method of the permanent magnet motor of the present invention and the control method in the related scheme, wherein the red line represents the motor torque curve of the demagnetization detection and compensation method of the permanent magnet motor of the present invention, and the green line represents the motor torque curve of the control method in the related scheme.

[0174] Since the processing and functions implemented by the device of this embodiment basically correspond to the embodiments, principles and examples of the aforementioned method, for any details not fully described in this embodiment, please refer to the relevant descriptions in the aforementioned embodiments and will not be repeated here.

[0175] According to an embodiment of the present invention, a motor corresponding to the motor control device is also provided. The motor may include: the motor control device described above.

[0176] Since the processing and functions implemented by the motor of this embodiment basically correspond to the embodiments, principles and examples of the aforementioned device, for any details not fully described in this embodiment, please refer to the relevant descriptions in the aforementioned embodiments and will not be repeated here.

[0177] According to an embodiment of the present invention, a computer program product corresponding to the motor control method is further provided, comprising a computer program. When the computer program is executed by a processor, the steps of the motor control method described above are implemented.

[0178] Since the processing and functions implemented by the product of this embodiment basically correspond to the embodiments, principles and examples of the aforementioned method, for any details not fully described in this embodiment, please refer to the relevant descriptions in the aforementioned embodiments and will not be repeated here.

[0179] According to an embodiment of the present invention, a storage medium corresponding to the motor control method is also provided, wherein the storage medium includes a stored program, wherein when the program is running, the device where the storage medium is located is controlled to execute the steps of the motor control method described above.

[0180] Since the processing and functions implemented by the storage medium of this embodiment basically correspond to the embodiments, principles and examples of the aforementioned method, for any details not fully described in this embodiment, please refer to the relevant descriptions in the aforementioned embodiments and will not be repeated here.

[0181] In summary, it is easy for those skilled in the art to understand that, under the premise of no conflict, the above-mentioned advantageous methods can be freely combined and superimposed.

[0182] The foregoing description is merely an embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention are intended to be within the scope of the claims.

Claims

1. A method for controlling a motor, characterized in that: include: When the motor is running, obtaining operating parameters of the motor; Determining whether irreversible demagnetization occurs in the motor and whether the motor enters a field weakening operating state according to operating parameters of the motor; If it is determined that irreversible demagnetization occurs in the motor and that the motor enters a field-weakening operating state, the current control angle of the motor is adjusted to compensate for the decrease in output torque caused by the irreversible demagnetization of the motor.

2. The motor control method according to claim 1, characterized in that: When the motor is running, obtaining operating parameters of the motor includes: At a preset normal temperature, obtaining a current value required for an initial unit torque of the motor at the normal temperature, and obtaining a magnetic weakening operating point of the motor at the normal temperature; When the motor is running, obtaining an actual temperature of the motor during operation, obtaining a current of the motor under any one of more than one operating conditions during operation, and obtaining an output torque of the motor under the any one operating condition during operation; At the normal temperature, obtaining the current of the motor under any working condition at the normal temperature, and obtaining the output torque of the motor under any working condition at a preset normal temperature; The current value required for the initial unit torque of the motor at the normal temperature, the point at which the motor enters the weak magnetic condition at the normal temperature, the actual temperature of the motor during operation, the current of the motor under any of more than one operating conditions during operation, the output torque of the motor under any of the operating conditions during operation, the current of the motor under any of the operating conditions at the normal temperature, and the output torque of the motor under any of the operating conditions at the normal temperature are used as the operating parameters of the motor.

3. The motor control method according to claim 1 or 2, characterized in that: The operating parameters of the motor include: the current value required for the initial unit torque of the motor at the normal temperature, the point at which the motor enters the field weakening operating condition at the normal temperature, the actual temperature of the motor during operation, the current of the motor under any one of more than one operating conditions during operation, the output torque of the motor under the any operating condition during operation, the current of the motor under the any operating condition at the normal temperature, and the output torque of the motor under the any operating condition at the normal temperature; Determining whether irreversible demagnetization occurs in the motor and whether the motor enters a field weakening state according to operating parameters of the motor includes: determining a torque difference generated by a temperature difference of the motor according to an actual temperature of the motor during operation and a current of the motor under any one of more than one operating conditions during operation; determining whether irreversible demagnetization occurs in the motor based on a current value required for an initial unit torque of the motor at the normal temperature, a torque difference caused by a temperature difference of the motor, a current of the motor in any one of more than one operating conditions during operation, an output torque of the motor in the any one operating condition during operation, a current of the motor in the any one operating condition at the normal temperature, and an output torque of the motor in the any one operating condition at the normal temperature; If it is determined whether the motor has irreversible demagnetization, then it is determined whether the motor has entered a magnetic weakening operating condition according to a magnetic weakening operating condition entry point of the motor at the normal temperature.

4. The motor control method according to claim 3, characterized in that: Determining a torque difference caused by a temperature difference of the motor according to an actual temperature of the motor during operation and a current of the motor under any one of more than one operating conditions during operation includes: According to the actual temperature of the motor during operation and the current of the motor under any one of more than one operating conditions during operation, the torque difference generated by the temperature difference of the motor is calculated according to the following formula: Wherein, ΔT is the torque difference generated by the temperature difference of the motor, P is the number of pole pairs of the motor, and α is the specific temperature coefficient of the permanent magnet. is the permanent magnet flux value of the motor at a preset normal temperature, t is the actual temperature of the motor during operation, t0 is the preset normal temperature, i q It is the q-axis current component in the current of the motor in any one of more than one operating conditions when the motor is running.

5. The motor control method according to claim 3, characterized in that: Determining whether irreversible demagnetization occurs in the motor based on a current value required for an initial unit torque of the motor at the normal temperature, a torque difference caused by a temperature difference of the motor, a current of the motor in any one of more than one operating conditions during operation, an output torque of the motor in the any operating condition during operation, a current of the motor in the any operating condition at the normal temperature, and an output torque of the motor in the any operating condition at the normal temperature includes: determining whether an initial current required per unit torque of the motor at the normal temperature has increased based on a torque difference generated by a temperature difference of the motor, a current of the motor under any one of more than one operating conditions during operation, an output torque of the motor under the any operating condition during operation, a current of the motor under the any operating condition at the normal temperature, and an output torque of the motor under the any operating condition at the normal temperature; If it is determined that the current value required for the initial unit torque of the motor at the normal temperature increases, determining whether irreversible demagnetization occurs in the motor; Determining whether the current value required for the initial unit torque of the motor at the normal temperature increases includes: Determine whether the following conditions are met, and if so, determine that the current value required for the initial unit torque of the motor at the normal temperature is increased: I0 / (T0-ΔT)>I / T; I / (T0-ΔT)≥(k1~k2)*(I / T); Among them, I0 is the current of the motor under any one of more than one operating conditions during operation, T0 is the output torque of the motor under the any operating condition during operation, ΔT is the torque difference caused by the temperature difference of the motor, I is the current of the motor under the any operating condition at the normal temperature, T is the output torque of the motor under the any operating condition at a preset normal temperature, I / T represents the current value required for the initial unit torque of the motor at the normal temperature, k1 and k2 are both calculation coefficients, and k2>k1 is greater than 1.

6. The motor control method according to claim 3, characterized in that: Determining whether the motor enters a magnetic weakening operating condition according to a magnetic weakening operating condition entry point of the motor at the normal temperature includes: If the operating condition of the motor reaches the point where the motor enters a weakened magnetic condition at the normal temperature, it is determined that the motor enters a weakened magnetic condition; The operating conditions of the motor include: the speed of the motor, the output torque of the motor, and the terminal voltage of the motor; The motor enters the weakening magnetic operating point at the normal temperature, including: at the same rotation speed of the motor, the terminal voltage of the motor reaches the rated voltage of the motor, and the terminal voltage of the motor does not increase with the increase of the output torque of the motor.

7. The method for controlling a motor according to any one of claims 1 to 6, characterized in that: Adjusting the current control angle of the motor to compensate for the decrease in output torque caused by irreversible demagnetization of the motor includes: The current control angle of the motor is controlled to decrease so as to reduce the d-axis current component of the motor and increase the q-axis current component of the motor until the terminal voltage of the motor reaches a preset maximum voltage limit value, thereby compensating for the output torque decreased due to irreversible demagnetization of the motor.

8. A motor control device, characterized in that: include: an acquiring unit, configured to acquire operating parameters of the motor when the motor is running; a control unit configured to determine whether irreversible demagnetization occurs in the motor and whether the motor enters a field weakening state according to operating parameters of the motor; The control unit is further configured to adjust the current control angle of the motor to compensate for the decrease in output torque caused by irreversible demagnetization of the motor if it is determined that irreversible demagnetization has occurred in the motor and that the motor has entered a weak magnetic field operating state.

9. A motor, characterized in that: include: The motor control device according to claim 8.

10. A storage medium, characterized in that: The storage medium includes a stored program, wherein when the program is executed, the device where the storage medium is located is controlled to execute the motor control method according to any one of claims 1 to 7.

11. A computer program product comprising a computer program, characterized in that When the computer program is executed by a processor, the steps of the motor control method according to any one of claims 1 to 7 are implemented.

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