Permanent magnet motor eddy current loss suppression method and device, electronic equipment and storage medium

Abstract

The invention provides a permanent magnet motor eddy current loss suppression method and device, electronic equipment and a storage medium, and belongs to the field of motor control. The method comprises the following steps: calculating the switching loss of the inverter through an initial switching loss formula, obtaining a simulation value by using a simulation tool, and comparing the two values to obtain an error value. And correcting the initial sinusoidal current based on the error to obtain a target sinusoidal current, and substituting the target sinusoidal current into an initial switching loss formula to form a target switching loss formula. Thirdly, an eddy current loss model field is established, a target switching loss formula and the model field are subjected to joint simulation, and the total loss change condition under different switching frequencies is analyzed; and finally, determining that the optimal switching frequency is the frequency with the minimum total loss and the minimum eddy-current loss ratio. According to the method, the optimal inverter switching frequency is solved through the improved algorithm, the current harmonics of the working condition change of the motor are considered at the same time, and the eddy current loss of the motor can be simply suppressed without changing the structure of the motor.

Description

Technical Field

[0001] This application belongs to the field of motor control, and particularly relates to a method, device, electronic device, and storage medium for suppressing eddy current loss in a permanent magnet motor. Background Art

[0002] Currently, high-end mainstream new energy vehicles all use high-speed permanent magnet synchronous motors as their driving cores. However, the high-speed and high-voltage platform characteristics of these high-end models can lead to an increase in voltage step and a decrease in sampling carrier ratio, thereby injecting a large amount of high-order current harmonics into the motor. Since eddy current loss is particularly sensitive to high-order harmonics, this results in significant eddy current loss inside the rotor and a large amount of heat release. On the other hand, considering that the rotor is a moving part, only limited heat conduction can be achieved through the air gap, making it difficult to dissipate heat effectively.

[0003] Therefore, these eddy current losses not only reduce the motor efficiency but may also cause thermal overload phenomena, affecting the service life of the motor. In order to meet the operating requirements of the motor under high-speed and high-power density conditions, automobile manufacturers need to take measures to suppress the eddy current loss in the rotor of high-speed permanent magnet synchronous motors. Against this background, it is particularly important to conduct in-depth research on methods for suppressing eddy current loss in high-speed permanent magnet synchronous motors used in new energy vehicles.

[0004] Currently, many patents and technical literatures tend to reduce eddy current loss by optimizing the motor structure, such as adjusting the stator slot design, changing the shape and position of permanent magnets, and optimizing the winding layout. Although these methods can suppress eddy current loss to a certain extent, they may also bring some adverse effects. For example, increasing the number of stator slots may increase the stator iron loss; changing the design of permanent magnets may lead to a decrease in the mechanical strength of the rotor; and increasing the number of winding layers may increase the volume of the motor. In addition, the actual operating conditions of the motor, including factors such as speed, load, and battery power, will affect the current characteristics input to the motor, thereby generating a variety of and frequently changing current harmonics. Traditional methods based on structural optimization do not fully consider the changes in current harmonics caused by changes in operating conditions. In practical applications, especially in the case of frequently changing operating conditions, the effects are often not satisfactory.

[0005] In summary, for high-speed permanent magnet synchronous motors used in new energy vehicles, in addition to structural optimization, it is also necessary to comprehensively consider various changes in the actual operation of the motor to develop more effective eddy current loss suppression strategies to ensure the stability and reliability of motor performance. Summary of the Invention

[0006] The purpose of the embodiments of the present application is to provide a method, device, electronic device and storage medium for suppressing eddy current loss in a permanent magnet motor, so as to solve the problems in the prior art that the eddy current loss suppression method focuses on optimizing the motor structure, such as stator slot and winding layout, but may cause a series of side effects such as increasing iron loss, reducing rotor strength or increasing rotor volume, and does not fully consider the influence of current harmonics caused by working condition changes, resulting in limited actual application effects.

[0007] To solve the above technical problems, the present application is implemented as follows: In a first aspect, the embodiments of the present application provide a method for suppressing eddy current loss in a permanent magnet motor, the method includes: Calculating a calculated value of the inverter switching loss according to an initial switching loss formula; wherein, the initial switching loss formula calculates the sum of the switching losses of the transistor and the diode using an initial sinusoidal current; the initial sinusoidal current is calculated based on the amplitude of the load current of the inverter; Building an inverter model through a simulation tool and obtaining a simulated value of the inverter switching loss; Comparing the simulated value with the calculated value to obtain an error value; Based on the error value, correcting the initial sinusoidal current to a target sinusoidal current; wherein, the amplitude of the target sinusoidal current is the maximum current value at the moment when the diode turns off; Substituting the target sinusoidal current into the calculation term of the diode switching loss in the initial switching loss formula to obtain a target switching loss formula; Based on the three-dimensional model of the motor and the eddy current loss calculation formula, building an eddy current loss model field through a simulation tool; Performing co-simulation on the target switching loss formula and the eddy current loss model field to obtain the total loss at different switching frequencies; Determining the optimal switching frequency according to the change of the total loss value at different frequencies; the optimal switching frequency corresponds to the switching frequency at which the proportion of eddy current loss is the smallest when the total loss is the smallest.

[0008] Compared with the prior art, the above technical solution provided by the present application at least includes the following beneficial effects: This application first calculates the calculated value of the inverter switching loss according to the initial switching loss formula; among them, the initial switching loss formula uses the initial sinusoidal current to calculate the sum of the switching losses of the transistor and the diode; an inverter model is built through a simulation tool, and the simulated value of the inverter switching loss is obtained; the simulated value and the calculated value are compared to obtain the error value; based on the error value, the initial sinusoidal current is corrected to the target sinusoidal current; among them, the amplitude of the target sinusoidal current is the maximum current value at the moment when the diode turns off; the target sinusoidal current is substituted into the calculation term of the diode switching loss in the initial switching loss formula to obtain the target switching loss formula; based on the three-dimensional model of the motor and the eddy current loss calculation formula, an eddy current loss model field is built through a simulation tool; the target switching loss formula and the eddy current loss model field are jointly simulated to obtain the total loss at different switching frequencies; according to the change of the total loss value at different frequencies, the optimal switching frequency is determined; the optimal switching frequency corresponds to the switching frequency at which the eddy current loss accounts for the smallest proportion when the total loss is the smallest. This application solves the optimal inverter switching frequency through an improved algorithm, and at the same time considers the current harmonics of the motor operating conditions, and can simply suppress the eddy current loss of the motor without changing the motor structure.

[0009] Preferably, the calculation term formula of the transistor switching loss in the initial switching loss formula is: Among them, represents the switching loss of the transistor, is the switching frequency, is the power factor angle of the load, is the phase angle corresponding to the switching time point, is the initial sinusoidal current, and represent the conduction and turn-off losses of the transistor respectively.

[0010] Preferably, the calculation term formula of the diode switching loss in the initial switching loss formula is: Among them, represents the switching loss of the diode, is the switching frequency, is the initial sinusoidal current, is the power factor angle of the load, is the phase angle corresponding to the switching time point, represents the reverse recovery loss of the diode.

[0011] Preferably, the correction formula for correcting the initial sinusoidal current to the target sinusoidal current is: Among them, represents the target sinusoidal current, Represents the reverse recovery current of the diode, which is the phase angle corresponding to the switching time point.

[0012] Preferably, based on the three-dimensional model of the motor and the eddy current loss calculation formula, the specific steps of building the eddy current loss model field through the simulation tool include: Establish a three-dimensional model of the motor; Determine the corresponding eddy current loss formula of the motor model to calculate the total eddy current loss from the harmonic perspective.

[0013] Preferably, the specific steps of determining the corresponding eddy current loss formula of the motor model to calculate the total eddy current loss from the harmonic perspective include: Calculate the eddy current density of each harmonic based on the interaction between the magnetic vector potential and the rotor speed; The formula for calculating the eddy current density of each harmonic is: where, represents the eddy current density, is the conductivity of the permanent magnet and the shaft of the motor, is the magnetic vector potential, is the curl operator of the vector field, is the rotor speed, is the harmonic order; Calculate the total eddy current loss based on the harmonic eddy current density and Joule's law; The formula for calculating the total eddy current loss is: where, represents the eddy current loss, represents the rotor volume.

[0014] Preferably, the specific steps of jointly simulating the target switching loss formula and the eddy current loss model field to obtain the total loss at different switching frequencies include: Based on the motor parameters in the eddy current loss model field, determine the minimum switching frequency; where, the motor parameters at least include the maximum speed of the motor, the switching frequency, and the fundamental frequency; Determine the maximum switching frequency according to the transistor device parameters; Construct a frequency test range based on the minimum value and the maximum value; Apply the frequency test range to the joint simulation to obtain the total loss at different switching frequencies.

[0015] In a second aspect, an embodiment of the present application provides a device for suppressing eddy current loss of a permanent magnet motor, including: Switching loss calculation module: used to calculate the calculated value of the inverter switching loss according to the initial switching loss formula; wherein, the initial switching loss formula calculates the sum of the switching losses of the transistor and the diode using the initial sinusoidal current; the initial sinusoidal current is calculated based on the amplitude of the load current of the inverter; Switching loss simulation module: used to build an inverter model through a simulation tool and obtain the simulated value of the inverter switching loss; Switching loss comparison module: used to compare the simulated value with the calculated value to obtain the error value; Current correction module: used to correct the initial sinusoidal current to the target sinusoidal current based on the error value; wherein, the amplitude of the target sinusoidal current is the maximum current value at the moment when the diode turns off; Target formula module: used to substitute the target sinusoidal current into the calculation term of the diode switching loss in the initial switching loss formula to obtain the target switching loss formula; Eddy current loss module: used to build an eddy current loss model field through a simulation tool based on the three-dimensional model of the motor and the eddy current loss calculation formula; Joint simulation module: used to perform a joint simulation on the target switching loss formula and the eddy current loss model field to obtain the total loss at different switching frequencies; Optimal switching frequency determination module: used to determine the optimal switching frequency according to the change of the total loss value at different frequencies; the optimal switching frequency corresponds to the switching frequency at which the proportion of eddy current loss is the smallest when the total loss is the smallest.

[0016] In a third aspect, an embodiment of the present application provides an electronic device, which includes a processor, a memory, and a program or instruction stored on the memory and executable on the processor. When the program or instruction is executed by the processor, the steps of the method described in the first aspect are implemented.

[0017] In a fourth aspect, an embodiment of the present application provides a readable storage medium, on which a program or instruction is stored. When the program or instruction is executed by the processor, the steps of the method described in the first aspect are implemented.

[0018] It can be understood that the beneficial effects of the technical solutions provided in the above second aspect, third aspect, and fourth aspect can refer to the relevant descriptions in the first aspect above, and will not be repeated here.

[0019] The additional aspects and advantages of the present application will be partially given in the following description, partially become obvious from the following description, or be understood through the practice of the present application. Description of the Drawings

[0020] The above and / or additional aspects and advantages of the present application will become obvious and easy to understand from the description of the embodiments in conjunction with the following drawings, where: Figure 1 Schematic diagram of the method for suppressing eddy current loss of a permanent magnet motor provided by some embodiments of the present application; Figure 2 Relationship curve between IGBT load current and initial sinusoidal current shown by some embodiments of the present application; Figure 3 Relationship curve graph of diode load current, initial sinusoidal current and target sinusoidal current shown by some embodiments of the present application; Figure 4 Block diagram of the device for suppressing eddy current loss of a permanent magnet motor shown by some embodiments of the present application; Figure 5 Block diagram of an electronic device shown by some embodiments of the present application. Detailed implementation manners

[0021] Next, the technical solutions in the embodiments of the present application will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are some, but not all, of the embodiments of the present application. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present application without creative efforts shall fall within the protection scope of the present application.

[0022] The terms "first", "second", etc. in the specification and claims of the present application are used to distinguish similar objects, rather than to describe a specific order or sequence. It should be understood that such data can be interchanged under appropriate circumstances so that the embodiments of the present application can be implemented in an order different from those illustrated or described herein. In addition, "and / or" in the specification and claims means at least one of the connected objects, and the character " / " generally represents an "or" relationship between the associated objects before and after.

[0023] Next, a method, device and electronic device for suppressing eddy current loss of a permanent magnet motor provided by the embodiments of the present application will be described in detail in conjunction with the accompanying drawings through specific embodiments and their application scenarios.

[0024] Figure 1 Schematic diagram of a method for suppressing eddy current loss of a permanent magnet motor according to the first embodiment of the present application. Please refer to Figure 1 , the method includes: Step S101: Calculate the calculated value of the inverter switching loss according to the initial switching loss formula; wherein, the initial switching loss formula calculates the sum of the switching losses of the transistor and the diode using the initial sinusoidal current; the initial sinusoidal current is calculated based on the amplitude of the load current of the inverter; The traditional switching loss analysis model, i.e., the initial switching loss formula, uses the initial sinusoidal current to calculate the loss. This initial sinusoidal current is obtained based on the amplitude of the load current of the inverter. The formula for obtaining the initial sinusoidal current is as follows: Where, is the initial sinusoidal current, representing the instantaneous value of the sinusoidal trend change of the load current as changes; is the angle corresponding to the switching time point; is the power factor angle of the load, which determines the phase shift of the current relative to the voltage; is the amplitude of the load current, usually in the range of [0, 2π].

[0025] For the modulation strategy in the inverter, since the switching action occurs at the intersection of the carrier wave and the modulation wave, it will cause switching losses. Therefore, the switching loss of the inverter can be obtained by adding up the losses of each switching action. The switching loss of the inverter mainly consists of two parts: the switching loss of the Insulate-Gate Bipolar Transistor (hereinafter referred to as IGBT) and the switching loss of the diode; among them, the switching loss formula of the IGBT is as follows: The switching loss formula of the diode is as follows: Where, , respectively refer to the switching losses of the IGBT and the diode; is the switching frequency; is the power factor angle of the load, which determines the phase shift of the current relative to the voltage; is the initial sinusoidal current, representing the instantaneous value of the sinusoidal trend change of the load current as changes; is the angle corresponding to the switching time point, with a range of [0, 2π]; , and are the conduction loss of the IGBT, the turn-off loss of the IGBT, and the reverse recovery loss of the diode respectively; represents is a function of

[0026] In a possible implementation, the IGBT model adopted in the inverter circuit is SKAI45A2GD12-W12DI, and the diode model is SEMIKRON-SKN12. In practical applications, the current-loss curves of the IGBT and the diode can be obtained from the corresponding data sheets.

[0027] Step S102: Build an inverter model through a simulation tool and obtain the simulation value of the inverter switching loss; Step S103: Compare the simulation value with the calculated value to obtain the error value; Please refer to Table 1. After simulation verification, compared with the simulation value obtained from the simulation results, the calculated value of the diode switching loss calculated by the diode switching loss calculation term in the initial switching loss formula has a huge error.

[0028] Table 1 Calculated values and simulation values of diode switching loss by traditional methods Further, please refer to Figure 2 and Figure 3 , the abscissa ωt is the instantaneous angular displacement, which represents the phase change experienced by the angular frequency t starting from the initial moment ω =0. The load current of the inverter is divided into the IGBT load current and the diode load current . The true values of these two load currents always fluctuate around the initial sinusoidal current , and do not exactly conform to the numerical change of the initial sinusoidal current, resulting in errors in calculating the inverter switching loss. Therefore, this embodiment analyzes the reasons for such errors and modifies the parameters to optimize the initial switching loss formula of the inverter.

[0029] Please refer to Figure 2 . Since the IGBT generates switching losses at both the turn-on and turn-off moments, its turn-on current and turn-off current are distributed on both sides of the initial sinusoidal current . Therefore, using the initial sinusoidal current to calculate the IGBT switching loss will not introduce obvious errors.

[0030] Please continue to refer to Figure 3 , is the turn-on current of the diode, is the turn-off current, also known as the reverse recovery current, is the maximum value of the reverse recovery current in the current change cycle. Since the diode only generates reverse recovery losses when it is turned off, and the reverse recovery current is always less than the initial sinusoidal current , this difference leads to a large error in calculating the switching loss of the diode. As shown in Table 1 above, the error can reach 30%.

[0031] Step S104: Based on the error value, correct the initial sinusoidal current to a target sinusoidal current; wherein, the amplitude of the target sinusoidal current is the maximum current value at the moment when the diode turns off; In this embodiment, the initial sinusoidal current used in the calculation item of the diode reverse recovery loss is corrected to a target sinusoidal current that can better reflect the switching loss condition of the diode , please continue to refer to Figure 2 and Figure 3 , is the target sinusoidal current, and its amplitude is the maximum value of the diode reverse recovery current in the current change cycle , therefore, the calculation formula for the target sine is as follows: Step S105: Substitute the target sinusoidal current into the calculation item of the diode switching loss in the initial switching loss formula to obtain the target switching loss formula; Specifically, substitute the target sinusoidal current into the calculation item of the diode switching loss in the initial switching loss formula, and optimize this item to the target diode switching loss calculation item: wherein, is the target diode switching loss.

[0032] Then, apply the target diode switching loss calculation item to the initial switching loss formula to obtain the integrated target switching loss calculation formula.

[0033] Please refer to Table 2. Using the target switching loss formula to calculate the diode switching loss at different switching frequencies, compared with the simulation value, the error rate is significantly reduced compared with the error rate in Table 1 above.

[0034] Table 2 Calculated values and simulation values of diode switching loss after optimizing the formula Step S106: Based on the three-dimensional model of the motor and the eddy current loss calculation formula, build an eddy current loss model field through a simulation tool; In order to suppress the eddy current loss of the high-speed permanent magnet synchronous motor, first, a rotor eddy current loss model of the high-speed permanent magnet synchronous motor needs to be established. This step will establish a model that can calculate the rotor eddy current loss of the motor in detail from the perspective of harmonics.

[0035] First, establish the three-dimensional model of the motor; In a possible implementation example, a commercial 35-kW, 110-krpm permanent magnet synchronous motor designed by Delta Motorsport for plug-in hybrid vehicles is used as a case study. This motor is specifically designed for plug-in hybrid vehicles. The motor has a three-phase distributed winding placed in 12 semi-closed slots, and a two-pole rotor equipped with segmented neodymium permanent magnets, a carbon fiber sleeve, and a hollow magnetic shaft. In this example, the finite element analysis tool MAXWELL is used to build a motor model to obtain the distribution of eddy current losses in the permanent magnets under different input current conditions, so as to observe the distribution of eddy current losses in the motor.

[0036] Secondly, determine the corresponding eddy current loss formula of the motor model to calculate the total eddy current loss from the harmonic perspective.

[0037] Furthermore, based on the interaction between the magnetic vector potential and the rotor speed, calculate the eddy current density of each harmonic; Eddy currents are caused by the interaction between time and space harmonics in an alternating magnetic field and the asynchronous rotation of the rotor. The eddy current density J of the nth harmonic n can be calculated by the following formula: where, represents the eddy current density, is the conductivity of the permanent magnet and shaft of the motor, is the magnetic vector potential, is the curl operator of the vector field, is the rotor speed, is the harmonic order; Furthermore, based on the harmonic eddy current density and Joule's law, calculate the total eddy current loss; Substitute J n in the above formula into Joule's law to calculate the eddy current loss, then integrate the eddy current loss in the rotor, and superimpose the rotor eddy current losses generated by each current harmonic to obtain the rotor eddy current loss of the motor calculated in detail from the harmonic perspective; The formula for calculating the total eddy current loss is as follows: where, represents the eddy current loss, represents the rotor volume.

[0038] Step S107: Perform a co-simulation of the target switching loss formula and the eddy current loss model field to obtain the total loss at different switching frequencies; Based on the motor parameters in the eddy current loss model field, determine the minimum value of the switching frequency; Among them, the motor parameters at least include the maximum speed, switching frequency, and fundamental frequency of the motor; According to the transistor device parameters, determine the maximum value of the switching frequency; Construct a frequency test range based on the minimum value and the maximum value; In this embodiment, since the maximum speed of the motor is 110 krpm, if the sampling rate ratio (the ratio of the switching frequency to the fundamental frequency) is less than 9, the sideband harmonics will overlap and reinforce each other, resulting in an undesirable waveform. Therefore, it is necessary to keep the sampling rate greater than the minimum threshold ratio of 9. Furthermore, according to the calculation of various parameters in the motor eddy current simulation, the minimum value of the switching frequency needs to be 16 kHz. On the other hand, based on the limitations of silicon-based IGBT devices, 25 kHz is selected as the highest frequency. Therefore, the test range of the switching frequency is constructed. fsw is 16 - 25 kHz.

[0039] Apply the frequency test range to the co-simulation to obtain the total losses at different switching frequencies.

[0040] To further improve the simulation efficiency, in this embodiment, co-simulations are carried out at several key switching frequency values, such as 16 kHz, 18 kHz, 20 kHz, and 25 kHz.

[0041] First, the d,q-axis currents with time harmonics are exported from the PLECS inverter model and imported into the motor model in MAXWELL for finite element analysis to obtain the shaft eddy current loss and the rotor eddy current loss respectively. Since the co-simulation is finite element analysis (FEA) + PLECS circuit simulation, the complexity is high, especially in the case of high frequencies, and the solution process takes several hours to several days. Therefore, the switching losses of the inverter do not rely on simulation calculation, but are calculated using the target switching loss formula. This method only requires the simulation output current signal, and the losses can be directly obtained through the formula, thereby reducing the complexity of the co-simulation and improving the simulation efficiency.

[0042] Step S108: Determine the optimal switching frequency according to the change of the total loss values at different frequencies; the optimal switching frequency corresponds to the switching frequency at which the proportion of the eddy current loss is the smallest when the total loss is the smallest.

[0043] In a possible implementation manner, the simulation results of the co-simulation include statistical graphs of the eddy current loss - switching frequency and the switching loss - switching frequency numerical changes. Within a certain range, the eddy current loss of the motor rotor is proportional to the switching frequency, and the eddy current loss gradually decreases as the switching frequency increases. At the same time, the switching loss of the inverter is proportional to the switching frequency, and the switching loss gradually increases as the switching frequency increases.

[0044] However, as the switching frequency increases, although the rotor eddy current loss gradually decreases, the rate of decrease gradually slows down, while the inverter loss increases linearly and the rate of increase remains unchanged. Therefore, there is an optimal switching frequency at which the eddy current loss can be most effectively suppressed without increasing the overall loss.

[0045] In this embodiment, the experimental results show that when the switching frequency is close to 18 kHz, the minimization of rotor eddy current loss and switching loss can be achieved. Based on this, in the method for suppressing eddy current loss of a high-speed permanent magnet synchronous motor of a plug-in hybrid vehicle proposed in this embodiment, 18 kHz is selected as the optimal switching frequency, which can effectively suppress eddy current loss without increasing the overall loss. This discovery provides a theoretical basis and technical guidance for optimizing the performance of the motor.

[0046] The above embodiment provides a method for suppressing eddy current loss of a permanent magnet motor. Since eddy current loss is more sensitive to high-order harmonics, and the high-speed and high-voltage requirements of high-end new energy vehicles lead to more high-order harmonics. Therefore, it is highly rewarding to suppress the eddy current loss of the motor by increasing the switching frequency to reduce the current harmonics input to the stator of the motor. First, the calculated value of the inverter switching loss is calculated using a traditional formula, the simulation value of the switching loss is obtained by simulating the inverter, the error value is obtained by comparing the calculated value and the simulation value, and the formula parameters are analyzed based on the error value to numerically optimize the sine current used in the calculation process, so as to more accurately quantify the impact of the increase in switching frequency on the loss. Then, a new target switching loss formula is proposed, which can reduce the calculation error of the inverter switching loss. Next, from the perspective of current harmonics, a model for calculating the rotor eddy current loss of a high-speed permanent magnet synchronous motor in detail from the perspective of harmonics is established. Subsequently, according to the specific parameters in the eddy current loss model field, the range of the switching frequency is determined, and the law of the influence of the switching frequency on the rotor eddy current loss and the inverter switching loss of the motor is found through co-simulation. Finally, the optimal switching frequency is obtained, which can achieve the suppression of eddy current loss without increasing the overall loss.

[0047] It should be noted that for the method for suppressing eddy current loss of a permanent magnet motor provided in the embodiments of the present application, the execution subject can be a device for suppressing eddy current loss of a permanent magnet motor, or a control module in the device for suppressing eddy current loss of a permanent magnet motor for executing the method for suppressing eddy current loss of a permanent magnet motor. In the embodiments of the present application, the method for suppressing eddy current loss of a permanent magnet motor executed by the device for suppressing eddy current loss of a permanent magnet motor is taken as an example to illustrate the method for suppressing eddy current loss of a permanent magnet motor provided in the embodiments of the present application.

[0048] Figure 4 is a schematic diagram of a device for suppressing eddy current loss of a permanent magnet motor shown in the second embodiment of the present application. Please refer to Figure 4 , the device 200 for suppressing eddy current loss of a permanent magnet motor includes: A switching loss calculation module 201: configured to calculate a calculated value of the inverter switching loss according to an initial switching loss formula; wherein, the initial switching loss formula calculates the sum of the switching losses of transistors and diodes using an initial sine current; The calculation term formula for the transistor switching loss in the initial switching loss formula is: Among them, represents the switching loss of the transistor, is the switching frequency, is the power factor angle of the load, is the phase angle corresponding to the switching time point, is the initial sinusoidal current, and represent the conduction and turn-off losses of the transistor respectively.

[0049] The calculation term formula of the diode switching loss in the initial switching loss formula is: Among them, represents the switching loss of the diode, is the switching frequency, is the initial sinusoidal current, is the power factor angle of the load, is the phase angle corresponding to the switching time point, represents the reverse recovery loss of the diode.

[0050] Switching loss simulation module 202: used to build an inverter model through a simulation tool and obtain the simulation value of the inverter switching loss; Switching loss comparison module 203: used to compare the simulation value with the calculated value to obtain the error value; Current correction module 204: used to correct the initial sinusoidal current to the target sinusoidal current based on the error value; among them, the amplitude of the target sinusoidal current is the maximum current value at the diode turn-off moment; The correction formula for correcting the initial sinusoidal current to the target sinusoidal current is: Among them, represents the target sinusoidal current, represents the reverse recovery current of the diode, is the phase angle corresponding to the switching time point.

[0051] Target formula module 205: used to substitute the target sinusoidal current into the calculation term of the diode switching loss in the initial switching loss formula to obtain the target switching loss formula; Eddy current loss module 206: used to build an eddy current loss model field through a simulation tool based on the three-dimensional model of the motor and the eddy current loss calculation formula; including: Establish a three-dimensional model of the motor; determine the corresponding eddy current loss formula of the motor model to calculate the total eddy current loss from the harmonic angle. Based on the interaction between the magnetic vector potential and the rotor speed, calculate the eddy current density of each harmonic; The formula for calculating the harmonic eddy current density is as follows: where represents the eddy current density, is the conductivity of the permanent magnet and the shaft of the motor, is the magnetic vector potential, is the curl operator of the vector field, is the rotor speed, is the harmonic order; Based on the harmonic eddy current density and Joule's law, the total eddy current loss is calculated; The formula for calculating the total eddy current loss is as follows: where represents the eddy current loss, represents the rotor volume.

[0052] Co - simulation module 207: used to perform co - simulation on the target switching loss formula and the eddy current loss model field to obtain the total loss at different switching frequencies; including: Based on the motor parameters in the eddy current loss model field, determine the minimum switching frequency; where the motor parameters at least include the maximum speed, switching frequency, and fundamental frequency of the motor; including: Determine the maximum switching frequency according to the transistor device parameters; construct a frequency test range based on the minimum and maximum values; apply the frequency test range to the co - simulation to obtain the total loss at different switching frequencies.

[0053] Optimal switching frequency determination module 208: used to determine the optimal switching frequency according to the change of the total loss values at different frequencies; the optimal switching frequency corresponds to the switching frequency at which the proportion of eddy current loss is the smallest when the total loss is the smallest.

[0054] The permanent magnet motor eddy current loss suppression device in the embodiments of the present application can be a device, or a component, integrated circuit, or chip in a terminal. The device can be a mobile electronic device or a non-mobile electronic device. Exemplarily, the mobile electronic device can be a mobile phone, a tablet computer, a laptop computer, a palmtop computer, a vehicle-mounted electronic device, a wearable device, an ultra-mobile personal computer (UMPC), a netbook, or a personal digital assistant (PDA), etc. The non-mobile electronic device can be a server, a Network Attached Storage (NAS), a personal computer (PC), a television (TV), a teller machine, or a self-service machine, etc. The embodiments of the present application do not make specific limitations.

[0055] The permanent magnet motor eddy current loss suppression device in the embodiments of the present application can be a device with an operating system. The operating system can be the Android operating system, the iOS operating system, or other possible operating systems. The embodiments of the present application do not make specific limitations.

[0056] The permanent magnet motor eddy current loss suppression device provided in the embodiments of the present application can implement Figure 1 each process implemented by the permanent magnet motor eddy current loss suppression method in the method embodiments. To avoid repetition, it will not be elaborated here.

[0057] A permanent magnet motor eddy current loss suppression device provided in this embodiment first calculates the calculated value of the inverter switching loss according to the initial switching loss formula; wherein, the initial switching loss formula calculates the sum of the switching losses of the transistor and the diode using the initial sinusoidal current; builds an inverter model through a simulation tool and obtains the simulated value of the inverter switching loss; compares the simulated value with the calculated value to obtain an error value; based on the error value, corrects the initial sinusoidal current to the target sinusoidal current; wherein, the amplitude of the target sinusoidal current is the maximum current value at the moment when the diode turns off; substitutes the target sinusoidal current into the calculation term of the diode switching loss in the initial switching loss formula to obtain the target switching loss formula; based on the three-dimensional model of the motor and the eddy current loss calculation formula, builds an eddy current loss model field through a simulation tool; performs a co-simulation on the target switching loss formula and the eddy current loss model field to obtain the total losses at different switching frequencies; determines the optimal switching frequency according to the change of the total loss values at different frequencies; the optimal switching frequency corresponds to the switching frequency at which the eddy current loss accounts for the smallest proportion when the total loss is the smallest. The present application solves the optimal inverter switching frequency through an improved algorithm, and takes into account the current harmonics of the motor operating conditions change. Without changing the motor structure, it can simply suppress the eddy current loss of the motor.

[0058] Optionally, refer to Figure 5 , Embodiments of the present application further provide an electronic device 300, including a processor 301, a memory 302, and a computer program 303 stored on the memory 302 and executable on the processor 301. When the computer program 303 is executed by the processor 301, it implements each process of the above-described embodiment of the permanent magnet motor eddy current loss suppression method and can achieve the same technical effect. To avoid repetition, it will not be elaborated here.

[0059] Embodiments of the present application further provide a readable storage medium, on which a program or instruction is stored. When the program or instruction is executed by a processor, it implements each process of the above-described embodiment of the permanent magnet motor eddy current loss suppression method and can achieve the same technical effect. To avoid repetition, it will not be elaborated here.

[0060] Among them, the processor is the processor in the electronic device described in the above embodiment. The readable storage medium includes computer-readable storage media, such as computer read-only memory (ROM), random access memory (RAM), magnetic disk, or optical disc, etc.

[0061] Embodiments of the present application further provide a chip, which includes a processor and a communication interface. The communication interface is coupled to the processor. The processor is used to run a program or instruction to implement each process of the above-described embodiment of the permanent magnet motor eddy current loss suppression method and can achieve the same technical effect. To avoid repetition, it will not be elaborated here.

[0062] It should be understood that the chip mentioned in the embodiments of the present application may also be referred to as a system-on-chip, system chip, chip system, or system-on-chip, etc.

[0063] It should be noted that in this text, the term "including", "comprising" or any other variant thereof is intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements not only includes those elements, but also includes other elements not explicitly listed, or further includes elements inherent to such process, method, article or device. Without more limitations, an element defined by the statement "including one..." does not exclude the existence of additional identical elements in the process, method, article or device including that element. In addition, it should be pointed out that the scope of the methods and devices in the embodiments of the present application is not limited to performing functions in the order shown or discussed, and may also include performing functions in a substantially simultaneous manner or in the reverse order according to the functions involved. For example, the described methods may be performed in an order different from that described, and various steps may be added, omitted, or combined. Additionally, the features described with reference to certain examples may be combined in other examples.

[0064] Through the description of the above embodiments, those skilled in the art can clearly understand that the methods of the above embodiments can be implemented by means of software plus a necessary general hardware platform. Of course, they can also be implemented by hardware, but in many cases the former is a better implementation. Based on such an understanding, the technical solution of the present application, in essence, or the part that contributes to the prior art, can be embodied in the form of a software product. This computer software product is stored in a storage medium (such as ROM / RAM, magnetic disk, optical disk) and includes several instructions to enable a terminal (which can be a mobile phone, computer, server, air conditioner, or network device, etc.) to execute the methods described in various embodiments of the present application.

[0065] The embodiments of the present application have been described above in conjunction with the accompanying drawings. However, the present application is not limited to the above specific embodiments. The above specific embodiments are merely illustrative and not restrictive. Under the inspiration of the present application, those of ordinary skill in the art can also make many forms without departing from the purpose of the present application and the scope protected by the claims, and all of them belong to the protection scope of the present application.

Claims

1. A method for suppressing eddy current loss of a permanent magnet motor, characterized in that Including: Calculating a calculated value of the inverter switching loss according to an initial switching loss formula; wherein, the initial switching loss formula calculates the sum of the switching losses of the transistor and the diode using an initial sinusoidal current; the initial sinusoidal current is calculated according to the amplitude of the load current of the inverter; Building an inverter model through a simulation tool and obtaining a simulated value of the inverter switching loss; Comparing the simulated value with the calculated value to obtain an error value; Based on the error value, correcting the initial sinusoidal current to a target sinusoidal current; wherein, the amplitude of the target sinusoidal current is the maximum current value at the moment when the diode turns off, and is used to correct the calculation error; Substituting the target sinusoidal current into the calculation term of the diode switching loss in the initial switching loss formula to obtain a target switching loss formula; Based on the three-dimensional model of the motor and the eddy current loss calculation formula, building an eddy current loss model field through a simulation tool; Performing co-simulation on the target switching loss formula and the eddy current loss model field to obtain the total loss at different switching frequencies; Determining the optimal switching frequency according to the change of the total loss value at different frequencies; the optimal switching frequency corresponds to the switching frequency at which the eddy current loss accounts for the smallest proportion when the total loss is the smallest.

2. The method for suppressing eddy current loss of a permanent magnet motor according to claim 1, wherein, The calculation term formula of the transistor switching loss in the initial switching loss formula is: Among them, represents the switching loss of the transistor, is the switching frequency, is the power factor angle of the load, θ is the phase angle corresponding to the switching time point, is the initial sinusoidal current, and represent the conduction and turn-off losses of the transistor respectively.

3. The method for suppressing eddy current loss of the permanent magnet motor according to claim 1, characterized in that The calculation term formula of the diode switching loss in the initial switching loss formula is: Among them, represents the switching loss of the diode, is the switching frequency, is the initial sinusoidal current, is the power factor angle of the load, is the phase angle corresponding to the switching time point, represents the reverse recovery loss of the diode.

4. The method for suppressing eddy current loss of the permanent magnet motor according to claim 1, characterized in that, The correction formula for correcting the initial sinusoidal current to a target sinusoidal current is: Among them, represents the target sinusoidal current, represents the reverse recovery current of the diode, is the phase angle corresponding to the switching time point.

5. The method for suppressing eddy current loss of a permanent magnet motor according to claim 1, wherein The specific steps for building an eddy current loss model field through a simulation tool based on the three-dimensional model of the motor and the eddy current loss calculation formula include: Building the three-dimensional model of the motor; Determining the eddy current loss formula corresponding to the motor model to calculate the total eddy current loss from the harmonic perspective.

6. The method for suppressing eddy current loss of a permanent magnet motor according to claim 5, wherein, The specific steps for determining the eddy current loss formula corresponding to the motor model to calculate the total eddy current loss from the harmonic perspective include: Calculating the eddy current density of each harmonic based on the interaction between the magnetic vector potential and the rotor speed; The formula for calculating the eddy current density of each harmonic is: Among them, represents the eddy current density, is the conductivity of the permanent magnet and the shaft of the motor, is the magnetic vector potential, is the curl operator of the vector field, is the rotor speed, is the harmonic order; t Calculating the total eddy current loss based on the harmonic eddy current density and Joule's law; The formula for calculating the total eddy current loss is: Among them, represents the eddy current loss, represents the rotor volume.

7. The method for suppressing eddy current loss of a permanent magnet motor according to claim 1, characterized in that, The specific steps for performing co-simulation on the target switching loss formula and the eddy current loss model field to obtain the total loss at different switching frequencies include: Based on the motor parameters in the eddy current loss model field, determining the minimum value of the switching frequency; wherein, the motor parameters at least include the highest speed, switching frequency and fundamental frequency of the motor; Determining the maximum value of the switching frequency according to the transistor device parameters; Constructing a frequency test range based on the minimum value and the maximum value; Applying the frequency test range to the co-simulation to obtain the total loss at different switching frequencies.

8. A device for suppressing eddy current loss of a permanent magnet motor, characterized in that Including: Switching loss calculation module: used to calculate the calculated value of the inverter switching loss according to the initial switching loss formula; wherein, the initial switching loss formula calculates the sum of the switching losses of the transistor and the diode using an initial sinusoidal current; the initial sinusoidal current is calculated according to the amplitude of the load current of the inverter; Switching loss simulation module: used to build an inverter model through a simulation tool and obtain the simulation value of the switching loss of the inverter; Switching loss comparison module: used to compare the simulation value with the calculated value to obtain an error value; Current correction module: used to correct the initial sinusoidal current to a target sinusoidal current based on the error value; wherein, the amplitude of the target sinusoidal current is the maximum current value at the diode turn-off moment; Target formula module: used to substitute the target sinusoidal current into the calculation term of the diode switching loss in the initial switching loss formula to obtain a target switching loss formula; Eddy current loss module: used to build an eddy current loss model field through a simulation tool based on the three-dimensional model of the motor and the eddy current loss calculation formula; Co-simulation module: used to perform co-simulation on the target switching loss formula and the eddy current loss model field to obtain the total loss at different switching frequencies; Optimal switching frequency determination module: used to determine the optimal switching frequency according to the change of the total loss value at different frequencies; the optimal switching frequency corresponds to the switching frequency with the smallest proportion of eddy current loss when the total loss is the smallest.

9. An electronic device, characterized in that, Including: A memory, a processor, and a program or instruction stored on the memory and executable on the processor, and when the program or instruction is executed by the processor, the steps of the permanent magnet motor eddy current loss suppression method according to any one of claims 1-7 are implemented.

10. A readable storage medium, characterized in that, A program or instruction is stored on the readable storage medium, and when the program or instruction is executed by the processor, the steps of the permanent magnet motor eddy current loss suppression method according to any one of claims 1-7 are implemented.

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