Six-phase permanent magnet synchronous motor loss and efficiency estimation method

Abstract

The invention discloses a six-phase permanent magnet synchronous motor loss and efficiency estimation method, and belongs to the technical field of motor loss estimation. The method specifically comprises the following steps: dividing loss power # imgabs0 # of a motor, wherein the loss power # imgabs0 # is composed of copper loss power # imgabs1 #, iron loss power # imgabs2 # and additional loss power # imgabs3 # of the motor; modeling is carried out on expressions of the copper loss power # imgabs4 #, the iron loss power # imgabs5 # and the additional loss power # imgabs6 # under all the working conditions; the power of the three types of loss is added, and the total loss power # imgabs7 #: # imgabs8 # of the motor is calculated; and finally, the efficiency # imgabs9 # of the motor is calculated. Wherein the additional loss power # imgabs10 # is obtained based on speed interval division and through a self-adaptive algorithm calculation mode. According to the method, a relatively accurate additional loss power value can be obtained, the loss and the efficiency of the six-phase permanent magnet synchronous motor can be estimated more accurately, and meanwhile, a certain reference is provided for the method for estimating the loss and the efficiency of the motor.

Description

Technical Field

[0001] The present invention relates to the technical field of motor loss estimation, and more specifically to a method for estimating the loss and efficiency of a six-phase permanent magnet synchronous motor. Background Art

[0002] Permanent magnet synchronous motors primarily generate a rotating magnetic field through stator current, which interacts with the magnetic field of the rotor's permanent magnets to produce electromagnetic torque, driving the motor's rotation. Permanent magnet synchronous motors offer advantages such as high efficiency and energy saving, compact structure, strong reliability, low noise, and environmental friendliness. They are widely used in new energy vehicles, industrial automation, home appliances and energy, rail transit, and other fields. Currently, most methods for estimating motor losses and efficiency are largely cookie-cutter, resulting in large calculation errors. This makes it difficult to accurately calculate motor losses and efficiency under various operating conditions. Consequently, the resulting efficiency data is severely distorted, making it impossible to accurately plot an efficiency map.

[0003] The Chinese invention patent application publication number CN 114465537A discloses a high-precision modeling method, device, and storage medium for a permanent magnet synchronous motor. Step S2 of the modeling method is to derive a thermal model of the motor's internal losses and temperature changes based on the thermal characteristics of the automotive permanent magnet synchronous motor. The motor's internal losses include copper loss and iron loss, and iron loss includes hysteresis loss, eddy current loss, additional loss, and high-frequency loss. The motor's stator iron loss is expressed as: P Fe =P h +P c +P e +P f , P h is the hysteresis loss, P c is the eddy current loss, P e is the additional loss, P f The patent does not consider the influence of motor speed in calculating additional loss, which results in insufficient accuracy in calculating motor loss. Summary of the Invention

[0004] The present invention provides a method for estimating the loss and efficiency of a six-phase permanent magnet synchronous motor, aiming to solve the shortcomings of existing permanent magnet synchronous motors in which the calculation of additional loss does not take into account the influence of the motor speed, resulting in insufficient calculation accuracy of the motor loss.

[0005] The present invention adopts the following technical solutions: A method for estimating the loss and efficiency of a six-phase permanent magnet synchronous motor comprises the following steps: Step 1: Power loss of the motor Divide by the copper power consumption of the motor , iron loss power and additional power loss Composition, namely: ; Step 2: Model the copper power consumption expression under each working condition. The formula is as follows: ,in, is the number of motor phases, here we take ; is the current per phase, is the motor impedance per phase, is the impedance of the motor controller; Step 3: Model the iron loss power expression under each working condition. The formula is as follows: ,in, and is the material coefficient, is the current frequency, is the magnetic flux density amplitude; Step 4: Calculate the additional power loss under each working condition The expression is modeled and obtained by adaptive algorithm calculation: ① Divide the speed into 3 intervals 、 、 , and their corresponding powers are 、 and ;in, is the instantaneous speed of the motor, is the rated speed of the motor; ② Set the initial additional power loss value to , the convergence region parameter is , calculate the impact factor and ; ③ Calculate the theoretical additional loss value of the first generation and the offset from the first generation ; ④ Calculate the theoretical additional loss value of the Nth generation and the offset of the Nth generation ⑤ Determine whether If so, output the theoretical additional loss value ⑥ Similarly, output additional loss value and ⑦ Write a piecewise function of the additional power loss: ; Step 5. Add the power of the above three categories of loss and calculate the total loss power of the motor. , then: ; Step 6: Calculate the efficiency of the motor , then: ,in, is the bus voltage, is the bus current.

[0006] The motor impedance in step 2 above It is obtained using the following formula: , ;in, is the temperature, The motor phase resistance at 25℃, resistance The motor line resistance at 25°C is Temperature The motor resistance below.

[0007] The controller impedance in step 2 above It is calculated as follows: ;in, is the influence factor of the controller, is the equivalent capacitance of the controller, is the switching frequency of the controller, is the bus voltage of the controller, is the on-time of the controller.

[0008] The above controller is a SIC controller. ; For IGBT controller, take .

[0009] The impact factor in step 4 above and The calculation method is as follows: hour, ,but ;when hour, ,but ;when hour, ,but .

[0010] Theoretical additional loss value of the first generation in step 4 above and the offset from the first generation Calculated using the following formula: .

[0011] It can be seen from the above description of the present invention that, compared with the prior art, the present invention has the following advantages: The present invention is based on dividing the speed interval and calculating the output of 3 theoretical additional power loss values ​​through adaptive algorithm. 、 、 , a more accurate additional loss power value can be obtained, which will make the estimation of the loss and efficiency of the six-phase permanent magnet synchronous motor more accurate, and also provide a certain reference for the estimation method of motor loss and efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 Flowchart of the present invention.

[0013] Figure 2 This is a flow chart of the method for obtaining additional power loss according to the present invention. DETAILED DESCRIPTION

[0014] The following describes specific embodiments of the present invention with reference to the accompanying drawings. Numerous details are provided below to provide a comprehensive understanding of the present invention, but those skilled in the art will appreciate that the present invention can be practiced without these details. Well-known components, methods, and processes are not described in detail below.

[0015] This embodiment provides a method for estimating the loss and efficiency of a six-phase permanent magnet synchronous motor. Figure 1 , specifically including the following steps: Step 1: Divide the motor losses and model them separately.

[0016] Motor power loss Mainly due to the copper power consumption of the motor , iron loss power and additional power loss Composition, namely: .

[0017] Step 2: Model the copper power consumption expression under each working condition. The formula is as follows: in, is the number of motor phases, here we take ; is the current per phase, is the motor impedance per phase, is the impedance of the motor controller.

[0018] ① Motor impedance Obtained: The above phase current It can be measured in real time, but the most important thing to consider is The value will change with the change of temperature, and the general change pattern is as follows: in, is the temperature, The motor phase resistance at 25℃, resistance The motor line resistance at 25°C is Temperature The motor resistance below.

[0019] ②Controller impedance Acquisition Regarding the impedance of the controller, the impedance of different controllers is slightly different. The impedance mainly considers the switching loss and conduction loss. It is calculated as follows: in, is the influence factor of the controller. For the SIC controller, take ; For IGBT controller, take ; is the equivalent capacitance of the controller; is the switching frequency of the controller; is the bus voltage of the controller; is the on-time of the controller.

[0020] Step 3: Model the iron loss power expression under each working condition. The formula is as follows: in, and is the material coefficient, is the current frequency, is the magnetic flux density amplitude.

[0021] Step 4: Calculate the additional power loss under each working condition Modeling expressions.

[0022] Additional power loss It is mainly caused by stray loss, which accounts for a relatively low proportion. However, in order to improve data accuracy, it is obtained by calculation based on an adaptive algorithm. Figure 2 , as follows: ①Additional power loss It is divided into three sections, namely, additional loss section 1 ( ), additional loss 2 segments ( ) and additional loss 3 segments ( ), and their corresponding powers are 、 and .in, is the instantaneous speed of the motor, is the rated speed of the motor.

[0023] ② For the seven-segment SVPWM wave generation method, in the additional loss 1 segment ( ), considering the additional loss caused by the change of the motor magnetic field due to the switch, in a complete PWM wave cycle, the PWM actually changes 6 times, and the average time for each change is approximately , so assuming the rated voltage is , so we have: Assume that in the 0th generation (initial state) setting, the initial additional power loss value is set to , the convergence region parameter is , and calculate the impact factor as and , which is calculated as follows: when hour, ,but ; when hour, ,but ; when hour, ,but .

[0024] ③When there is additional power loss value , then the deviation of the theoretically calculated additional power loss value of the first generation is called "1st generation offset ”, set to .

[0025] ④ Further calculate the additional power loss value of the first generation and the offset from the first generation , that is: ⑤Continue the above steps and analogize until there is , if exists , it indicates that That is value.

[0026] ⑥Similarly, we can calculate and value.

[0027] ⑦ Write a piecewise function to solve the problem as follows: The judgment logic of the above piecewise function is: (1) collect the motor speed and first make an interval judgment based on the speed value; (2) after obtaining the speed interval, calculate the theoretical value based on the calculation function of the additional power loss value.

[0028] Step 5. Add the power of the three major types of loss above and calculate the total loss power of the motor. , then: Step 6: Calculate the efficiency of the motor , then: in, is the bus voltage, is the bus current.

[0029] The above is only a specific implementation of the present invention, but the design concept of the present invention is not limited to this. Any non-substantial changes to the present invention using this concept shall be deemed as an infringement of the protection scope of the present invention.

Claims

1. A method for estimating the loss and efficiency of a six-phase permanent magnet synchronous motor, characterized in that: The following steps are involved: Step 1: Power loss of the motor Divide by the copper power consumption of the motor , iron loss power and additional power loss Composition, namely: ; Step 2: Model the copper power consumption expression under each working condition. The formula is as follows: ,in, is the number of motor phases, here we take ; is the current per phase, is the motor impedance per phase, is the impedance of the motor controller; Step 3: Model the iron loss power expression under each working condition. The formula is as follows: ,in, and is the material coefficient, is the current frequency, is the magnetic flux density amplitude; Step 4: Calculate the additional power loss under each working condition The expression is modeled and obtained by adaptive algorithm calculation: ① Divide the speed into 3 intervals 、 、 , and their corresponding powers are 、 and ;in, is the instantaneous speed of the motor, is the rated speed of the motor; ② Set the initial additional power loss value to , the convergence region parameter is , calculate the impact factor and ; ③ Calculate the theoretical additional loss value of the first generation and the offset from the first generation ; ④ Calculate the theoretical additional loss value of the Nth generation and the offset of the Nth generation ⑤ Determine whether If so, output the theoretical additional loss value ⑥ Similarly, output additional loss value and ⑦ Write a piecewise function of the additional power loss: ; Step 5. Add the power of the above three categories of loss and calculate the total loss power of the motor. , then: ; Step 6: Calculate the efficiency of the motor , then: ,in, is the bus voltage, is the bus current.

2. A method for estimating the loss and efficiency of a six-phase permanent magnet synchronous motor according to claim 1, characterized in that: Motor impedance in step 2 It is obtained using the following formula: , ;in, is the temperature, The motor phase resistance at 25℃, resistance The motor line resistance at 25°C is Temperature The motor resistance below.

3. The method for estimating the loss and efficiency of a six-phase permanent magnet synchronous motor according to claim 1, wherein: Controller impedance in step 2 It is calculated as follows: ;in, is the influencing factor of the controller, is the equivalent capacitance of the controller, is the switching frequency of the controller, is the bus voltage of the controller, is the on-time of the controller.

4. A method for estimating the loss and efficiency of a six-phase permanent magnet synchronous motor according to claim 3, characterized in that: The controller is a SIC controller. ; For IGBT controller, take .

5. The method for estimating the loss and efficiency of a six-phase permanent magnet synchronous motor according to claim 1, wherein: The impact factor in step 4 and The calculation method is as follows: hour, ,but ;when hour, ,but ;when hour, ,but .

6. The method for estimating the loss and efficiency of a six-phase permanent magnet synchronous motor according to claim 1, wherein: Theoretical additional loss value of the first generation in step 4 and the offset from the first generation Calculated using the following formula: .

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