A method for identifying resistance and inductance parameters of a levitation electromagnet

Abstract

The application discloses a kind of identification method of resistance and inductance parameter of suspension electromagnet, it is related to electromagnetic parameter identification technical field, comprising: by hardware circuit respectively detection electromagnet voltage and current;Control sampling chopper to drive suspension electromagnet with fixed duty ratio, first cycle gathers current differential, calculates inductance initial estimated value;Resistance initial estimated value is obtained after current stabilization.The resistance initial estimated value is converted into real-time estimated value after electromagnet starts, and resistance identification is completed.Voltage is reconstructed, and the difference between measured and reconstructed voltage is multiplied by current differential, and the real-time inductance estimated value is obtained after low-pass filtering and PID adjustment and inductance initial value summation, and inductance identification is completed.Finally, the suspension air gap unit value is calculated from inductance estimated value, and the electromagnet acceleration is obtained by filtering and differentiating.The prior art solves the problem that the calculation error is very large and the identification accuracy is not high in the DC voltage pulsation of the suspension controller.

Description

Technical Field

[0001] This invention relates to the field of electromagnet parameter identification technology, specifically to a method for identifying the resistance and inductance parameters of a levitating electromagnet. Background Technology

[0002] Normal-conducting maglev trains utilize electromagnetic forces generated by levitation electromagnets. To maintain a stable levitation air gap, constant air gap control is employed, making air gap detection crucial. Existing technologies, such as patent CN118244007B, disclose an online identification method for the resistance and inductance parameters of a levitation electromagnet. This method calculates the levitation air gap using the electromagnet's inductance, replacing existing air gap sensors with a low-cost approach. However, while this method works when the DC voltage of the levitation controller remains constant, it suffers from significant calculation errors and low identification accuracy when the DC voltage fluctuates. Summary of the Invention

[0003] The purpose of this invention is to overcome the shortcomings of the prior art and provide a method for identifying the resistance and inductance parameters of a levitation electromagnet.

[0004] The objective of this invention is achieved through the following technical solution: This application discloses a method for identifying the resistance and inductance parameters of a levitation electromagnet, comprising the following steps: S1. The voltage detection of the electromagnet is realized through hardware circuit. The voltage of the first electromagnet is obtained by differential detection of the inductor voltage, and then filtered and amplified to obtain the average voltage of the electromagnet. S2. The current detection of the electromagnet is realized through hardware circuit. The current of the electromagnet is obtained by sampling through resistor. After differential detection and filtering, the average current of the inductor is obtained. Then, the differential current is obtained through differential operation. S3. Control the sampling chopper output to a fixed duty cycle to drive the levitation electromagnet. In the first cycle of the sampling chopper's operation, sample the current differential and calculate the initial estimate of the electromagnet's inductance. After the electromagnet's current stabilizes, calculate the initial estimate of the electromagnet's resistance. S4. After the levitation electromagnet is started, the initial estimated resistance value of the electromagnet calculated in step S3 is converted into a real-time estimated resistance value to complete the resistance identification. S5. Based on the initial inductance estimate, current derivative, electromagnet current and resistance estimate, reconstruct the electromagnet voltage to obtain the second electromagnet voltage. Multiply the difference between the first and second electromagnet voltages by the current derivative. Then, process the calculation results sequentially through the first low-pass filter and the PID controller. Sum the output of the PID controller with the initial inductance estimate to obtain the electromagnet inductance estimate, thus completing the inductance identification. S6. Calculate the per-unit value of the suspension air gap based on the inductance estimate obtained in step S5. After filtering the per-unit value of the suspension air gap through the second low-pass filter, obtain the acceleration of the electromagnet through differentiation.

[0005] Further, the hardware circuit described in step S1 includes a first differential detection module, a first filtering module, and an amplification module. The first filtering module is connected to both the first differential detection module and the amplification module. The first differential detection module performs differential detection on the inductor voltage to obtain the first electromagnet voltage. The voltage of the first electromagnet is then passed through the first filtering module and the amplification module in sequence. The process is performed to obtain the average voltage of the electromagnet. .

[0006] Preferably, the hardware circuit in step S2 includes a resistance sampling module, a second differential detection module, and a second filtering module. The second differential detection module is connected to both the resistance sampling module and the second filtering module, and the electromagnet current is obtained by sampling the resistance through the resistance sampling module. After being processed sequentially by the second differential detection module and the second filtering module, the average inductor current is obtained. Then, the differential is performed to obtain the current differential. .

[0007] Preferably, step S3 specifically includes: controlling the sampling chopper output to have a fixed duty cycle D0, which is used to drive the levitation electromagnet, and sampling the current differential during the first cycle of the sampling chopper's operation. Through formula Calculate the initial estimate of the inductance of an electromagnet. After the current in the electromagnet stabilizes, it can be determined by the formula... Calculate the initial estimate of the electromagnet's resistance. .

[0008] Preferably, step S4 specifically includes: after the levitation electromagnet is started, the initial estimated value of the electromagnet's resistance calculated in step S3 is... Converted into real-time estimated resistance values .

[0009] Preferably, step S5 specifically includes: reconstructing the electromagnet voltage based on the initial inductance estimate, the current derivative, the electromagnet current, and the resistance estimate, i.e. Obtain the voltage of the second electromagnet Multiply the difference between the voltage of the first electromagnet and the voltage of the second electromagnet by the differential of the current, i.e. Then, the signal is passed sequentially through the first low-pass filter and the PID controller. The process involves comparing the output of the PID controller with the initial estimate of the inductance. Summing these values ​​yields an estimated value for the electromagnet's inductance. .

[0010] Preferably, step S6 specifically includes: the per-unit value of the suspending air gap is inversely proportional to the inductance of the electromagnet, that is... The per-unit value of the suspended air gap After filtering by a second low-pass filter, the acceleration of the electromagnet is obtained through differentiation. .

[0011] The beneficial effects of this invention are: 1) This invention provides an online identification method for the resistance and inductance parameters of a levitation electromagnet. The method calculates the levitation air gap and acceleration using the electromagnet's inductance, replacing existing air gap sensors in a low-cost manner. Simultaneously, it utilizes the electromagnet's resistance and inductance to diagnose and warn of over-temperature and internal short-circuit faults in the electromagnet. Attached Figure Description

[0012] Figure 1 This is a schematic diagram illustrating the steps of a method for identifying the resistance and inductance parameters of a levitation electromagnet according to an embodiment of the present invention. Figure 2 This is a flowchart illustrating a method for identifying the resistance and inductance parameters of a levitation electromagnet according to an embodiment of the present invention. Detailed Implementation

[0013] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0014] See Figures 1-2 This application discloses a method for identifying the resistance and inductance parameters of a levitation electromagnet, comprising the following steps: S1. The voltage detection of the electromagnet is realized through hardware circuit. The voltage of the first electromagnet is obtained by differential detection of the inductor voltage, and then filtered and amplified to obtain the average voltage of the electromagnet. S2. The current detection of the electromagnet is realized through hardware circuit. The current of the electromagnet is obtained by sampling through resistor. After differential detection and filtering, the average current of the inductor is obtained. Then, the differential current is obtained through differential operation. S3. Control the sampling chopper output to a fixed duty cycle to drive the levitation electromagnet. In the first cycle of the sampling chopper's operation, sample the current differential and calculate the initial estimate of the electromagnet's inductance. After the electromagnet's current stabilizes, calculate the initial estimate of the electromagnet's resistance. S4. After the levitation electromagnet is started, the initial estimated resistance value of the electromagnet calculated in step S3 is converted into a real-time estimated resistance value to complete the resistance identification. S5. Based on the initial inductance estimate, current derivative, electromagnet current and resistance estimate, reconstruct the electromagnet voltage to obtain the second electromagnet voltage. Multiply the difference between the first and second electromagnet voltages by the current derivative. Then, process the calculation results sequentially through the first low-pass filter and the PID controller. Sum the output of the PID controller with the initial inductance estimate to obtain the electromagnet inductance estimate, thus completing the inductance identification. S6. Calculate the per-unit value of the suspension air gap based on the inductance estimate obtained in step S5. After filtering the per-unit value of the suspension air gap through the second low-pass filter, obtain the acceleration of the electromagnet through differentiation.

[0015] Specifically, the hardware circuit described in step S1 includes a first differential detection module, a first filtering module, and an amplification module. The first filtering module is connected to both the first differential detection module and the amplification module. The first differential detection module performs differential detection on the inductor voltage to obtain the first electromagnet voltage. The voltage of the first electromagnet is then passed through the first filtering module and the amplification module in sequence. The process is performed to obtain the average voltage of the electromagnet. The voltage of the first electromagnet is an AC voltage with equal amplitude but asymmetrical width. To obtain a better response speed, a high-frequency operational amplifier should be selected as the amplification module.

[0016] Specifically, the hardware circuit in step S2 includes a resistance sampling module, a second differential detection module, and a second filtering module. The second differential detection module is connected to both the resistance sampling module and the second filtering module. The resistance sampling module samples the resistance to obtain the electromagnet current. After being processed sequentially by the second differential detection module and the second filtering module, the average inductor current is obtained. Then, the differential is performed to obtain the current differential. To suppress high-frequency interference, a high-frequency noise suppression filter is added to the output. To improve response speed, both the resistor sampling module and the second filtering module should use high-frequency operational amplifiers.

[0017] Specifically, step S3 includes: controlling the sampling chopper output to have a fixed duty cycle D0, which is used to drive the levitation electromagnet, and sampling the current differential during the first cycle of the sampling chopper's operation. Through formula Calculate the initial estimate of the inductance of an electromagnet. After the current in the electromagnet stabilizes, it can be determined by the formula... Calculate the initial estimate of the electromagnet's resistance. .

[0018] Specifically, step S4 includes: after the levitation electromagnet is started, the initial estimated value of the electromagnet's resistance calculated in step S3 is... Converted into real-time estimated resistance values .

[0019] Specifically, step S5 includes: reconstructing the electromagnet voltage based on the initial inductance estimate, the current derivative, the electromagnet current estimate, and the resistance estimate, i.e. Obtain the voltage of the second electromagnet Multiply the difference between the voltage of the first electromagnet and the voltage of the second electromagnet by the differential of the current, i.e. Then, the signal is passed sequentially through the first low-pass filter and the PID controller. The process involves comparing the output of the PID controller with the initial estimate of the inductance. Summing these values ​​yields an estimated value for the electromagnet's inductance. .

[0020] Specifically, step S6 includes: the per-unit value of the suspended air gap is inversely proportional to the inductance of the electromagnet, that is... The per-unit value of the suspended air gap After filtering by a second low-pass filter, the acceleration of the electromagnet is obtained through differentiation. .

[0021] For example, a theoretical analysis of the principles of this application is provided: The voltage equation of an electromagnet is: ,in and It can be detected by sensors. This represents the actual inductance, and the electromagnet voltage is reconstructed using the initial estimates of the electromagnet's inductance and resistance. Subtract the two formulas, that is The resistance estimate is obtained through the formula Perform calculations. ,therefore The hover controller has two modes: T1 and T2 when activated. When T1 and T2 are turned off It can be seen that the sign of the relationship between voltage difference and inductance difference changes; to obtain a relationship that remains unchanged, the formula is... Multiply both sides ,Right now ,because ,like ,but ;like ,but ,like ,but ,visible and Proportional.

[0022] For example, a flowchart illustrating the method for identifying the resistance and inductance parameters of a levitation electromagnet is shown below. Figure 2 As shown, Figure 2 There are two low-pass filters (LP1 and LP2). Low-pass filter LP2 is used to filter the voltage of the first electromagnet. Filtering yields the average value of the inductor voltage. In practice, the resistance of an electromagnet changes slowly, and at the same time The switching frequency has a high AC component. To achieve a good filtering effect, the low-pass filter LP1 has a time constant of 50ms and a cutoff frequency of 3.18Hz. The main harmonic frequency is twice the switching frequency. The cutoff frequency of LP2 is taken as 1 / 5 to 1 / 10 of the switching frequency (corresponding to a 5kHz switching frequency, the RC of LP2 is 250μS-500μS; when the switching frequency is 10kHz, the RC of LP1 is 125μS-250μS). It can be seen that the higher the switching frequency, the higher the cutoff frequency of LP2, the smaller the filter hysteresis, and the larger the integrator coefficient of the PI controller can be in the identification process, thus resulting in a faster response speed. Identifying the electromagnet inductance can serve as a basis for inductor fault diagnosis, and more importantly, it can be used as an air gap gauge. The per-unit value of the suspension air gap is inversely proportional to the electromagnet inductance, i.e. During suspension control, acceleration signals are required. Differentiation yields the air gap rate of change, i.e., the acceleration of the electromagnet. Because the air gap contains high-frequency components that are harmonics of the switching frequency, differentiation introduces significant interference. Therefore, a low-pass filter LP3 can be added before differentiation to suppress the interference signal. The cutoff frequency of LP3 can be the same as that of LP2.

[0023] The above description is merely a preferred embodiment of the present invention. It should be understood that the present invention is not limited to the forms disclosed herein and should not be construed as excluding other embodiments. It can be used in various other combinations, modifications, and environments, and can be altered within the scope of the concept described herein through the above teachings or related technologies or knowledge. Modifications and variations made by those skilled in the art that do not depart from the spirit and scope of the present invention should be within the protection scope of the appended claims.

Claims

1. A method for identifying the resistance and inductance parameters of a levitation electromagnet, characterized in that, Includes the following steps: S1. The voltage detection of the electromagnet is realized through hardware circuit. The voltage of the first electromagnet is obtained by differential detection of the inductor voltage, and then filtered and amplified to obtain the average voltage of the electromagnet. S2. The current detection of the electromagnet is realized through hardware circuit. The current of the electromagnet is obtained by sampling through resistor. After differential detection and filtering, the average current of the inductor is obtained. Then, the differential current is obtained through differential operation. S3. Control the sampling chopper output to a fixed duty cycle to drive the levitation electromagnet. In the first cycle of the sampling chopper's operation, sample the current differential and calculate the initial estimate of the electromagnet's inductance. After the electromagnet's current stabilizes, calculate the initial estimate of the electromagnet's resistance. S4. After the levitation electromagnet is started, the initial estimated resistance value of the electromagnet calculated in step S3 is converted into a real-time estimated resistance value to complete the resistance identification. S5. Based on the initial inductance estimate, current derivative, electromagnet current and resistance estimate, reconstruct the electromagnet voltage to obtain the second electromagnet voltage. Multiply the difference between the first and second electromagnet voltages by the current derivative. Then, process the calculation results sequentially through the first low-pass filter and the PID controller. Sum the output of the PID controller with the initial inductance estimate to obtain the electromagnet inductance estimate, thus completing the inductance identification. S6. Calculate the per-unit value of the suspension air gap based on the inductance estimate obtained in step S5. After filtering the per-unit value of the suspension air gap through the second low-pass filter, obtain the acceleration of the electromagnet through differentiation.

2. The method for identifying the resistance and inductance parameters of a levitation electromagnet according to claim 1, characterized in that: The hardware circuit described in step S1 includes a first differential detection module, a first filtering module, and an amplification module. The first filtering module is connected to both the first differential detection module and the amplification module. The first differential detection module performs differential detection on the inductor voltage to obtain the first electromagnet voltage. The voltage of the first electromagnet is then passed through the first filtering module and the amplification module in sequence. The process is performed to obtain the average voltage of the electromagnet. .

3. The method for identifying the resistance and inductance parameters of a levitation electromagnet according to claim 2, characterized in that: The hardware circuit described in step S2 includes a resistance sampling module, a second differential detection module, and a second filtering module. The second differential detection module is connected to both the resistance sampling module and the second filtering module. The resistance sampling module samples the resistance to obtain the electromagnet current. After being processed sequentially by the second differential detection module and the second filtering module, the average inductor current is obtained. Then, the differential is performed to obtain the current differential. .

4. The method for identifying the resistance and inductance parameters of a levitation electromagnet according to claim 3, characterized in that, Step S3 specifically includes: controlling the sampling chopper output to have a fixed duty cycle D0, which is used to drive the levitation electromagnet, and sampling the current differential during the first cycle of the sampling chopper's operation. Through formula Calculate the initial estimate of the inductance of an electromagnet. After the current in the electromagnet stabilizes, it can be determined by the formula... Calculate the initial estimate of the electromagnet's resistance. .

5. The method for identifying the resistance and inductance parameters of a levitation electromagnet according to claim 4, characterized in that, Step S4 specifically includes: after the levitation electromagnet is started, the initial estimated value of the electromagnet's resistance calculated in step S3 is... Converted into real-time estimated resistance values .

6. The method for identifying the resistance and inductance parameters of a levitation electromagnet according to claim 5, characterized in that, Step S5 specifically includes: reconstructing the electromagnet voltage based on the initial inductance estimate, current derivative, electromagnet current estimate, and resistance estimate, i.e. Obtain the voltage of the second electromagnet Multiply the difference between the voltage of the first electromagnet and the voltage of the second electromagnet by the differential of the current, i.e. Then, the signal is passed sequentially through the first low-pass filter and the PID controller. The process involves comparing the output of the PID controller with the initial estimate of the inductance. Summing these values ​​yields an estimated value for the electromagnet's inductance. .

7. The method for identifying the resistance and inductance parameters of a levitation electromagnet according to claim 6, characterized in that, Step S6 specifically includes: the per-unit value of the suspended air gap is inversely proportional to the inductance of the electromagnet, that is... The per-unit value of the suspended air gap After filtering by a second low-pass filter, the acceleration of the electromagnet is obtained through differentiation. .

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