A random square wave voltage injection method for estimating rotor position and speed of a PMSM

Abstract

This invention discloses a method for estimating the rotor position and speed of a PMSM (Permanent Magnet Synchronous Motor) by random square wave voltage injection, specifically including the following steps: Step 1, designing a random switching frequency of the inverter using random numbers following a Beta distribution and injecting a random high-frequency square wave voltage signal along the α axis; Step 2, extracting and demodulating the rotor position-related signal obtained from the high-frequency current response generated by the injected random high-frequency square wave voltage signal in Step 1, and obtaining an orthogonal signal of the rotor position-related signal through an orthogonal signal generator; Step 3, estimating the rotor position and speed of the permanent magnet synchronous motor using a phase-locked loop based on the orthogonal signal obtained in Step 2. This invention solves the problems of audible noise caused by the concentration of stator current power spectral density and inaccurate rotor position estimation due to DC bias in existing high-frequency injection methods.

Description

Technical Field

[0001] This invention belongs to the field of permanent magnet synchronous motor control technology, specifically relating to a method for estimating the rotor position and speed of a PMSM by random square wave voltage injection. Background Technology

[0002] Permanent magnet synchronous motors (PMSMs) possess numerous advantages such as high power density, high torque density, and robust structure, leading to their widespread application in industrial sectors, transportation, and defense equipment. High-performance PMSM control relies on accurate rotor position and speed, typically detected using mechanical sensors. However, installing mechanical sensors not only increases the cost of the PMSM drive system but also reduces its reliability. Therefore, researching methods for estimating rotor position and speed in high-performance PMSMs is crucial.

[0003] High-frequency voltage injection based on salient pole characteristic tracking does not rely on back EMF and motor parameters, and can estimate rotor position and speed at low or even zero speeds. However, the injected high-frequency voltage, within the range of human hearing sensitivity, will produce harsh audible noise. While pseudo-random high-frequency injection can expand the power spectral density of the high-frequency current, helping to reduce audible noise, it still exhibits high discrete harmonics at the least common multiple and integer multiples of the two injected voltage frequencies, limiting its ability to reduce audible noise. The non-uniform distribution of the stator current power spectrum within the range of human hearing inevitably causes harsh audible noise. Summary of the Invention

[0004] The purpose of this invention is to provide a method for estimating the rotor position and speed of a PMSM by random square wave voltage injection, which solves the problems of harsh audible noise caused by the concentration of stator current power spectral density and inaccurate rotor position estimation caused by DC bias in existing high-frequency injection methods.

[0005] The technical solution adopted in this invention is:

[0006] A method for estimating the position and speed of a PMSM rotor using random square wave voltage injection specifically includes the following steps:

[0007] Step 1: Using random numbers that follow a Beta distribution, design the random switching frequency of the inverter and inject a random high-frequency square wave voltage signal along the α axis. The specific steps are as follows:

[0008] Step 1.1: Design the random switching frequency of the inverter using random numbers that follow a Beta distribution;

[0009] The probability density function of the Beta distribution is shown in Equation (1):

[0010]

[0011] Where m and n are adjustable parameters greater than 0, x is a generated random number that follows a Beta distribution, and x∈[0,1];

[0012] To make the probability density of the random number x following a Beta distribution symmetric about x = 0.5, we set m = n; when m = n > 1, the probability density function of x is convex; when m = n < 1, the probability density function of x is concave; the random switching frequency of the inverter generated by the random number x following a Beta distribution is shown in formula (2):

[0013] f sk =f min +xΔf (2)

[0014] Among them, f sk It is the random switching frequency of the inverter, f min It is the minimum value of the inverter switching frequency, and Δf is the range of the inverter switching frequency.

[0015] Step 1.2: Inject a random high-frequency square wave voltage signal by designing random numbers that follow a Beta distribution;

[0016] To reduce high-frequency losses while maintaining rotor position estimation accuracy, the amplitude of the high-frequency current response should be equal in each injection cycle. Let the amplitude of the high-frequency current response be I. h Then, a random high-frequency square wave voltage is injected along the α axis as shown in formula (3):

[0017]

[0018] Among them, u αhk u βhk These are the high-frequency square wave voltages injected into the α and β axes respectively during the k-th switching cycle, where k is the count value of the PWM interrupt cycle, V. hk =2πf sk I h L n L is the amplitude of the high-frequency square wave voltage injected in the k-th switching cycle, which varies with the random switching frequency of the inverter. n =2L dh L qh / (L dh +L qh ), L dh L qh These are the inductances along the d-axis and q-axis, respectively.

[0019] Step 2: Extract and demodulate the rotor position correlation signal obtained from the high-frequency current response generated by the random high-frequency square wave voltage signal injected in Step 1, and obtain the orthogonal signal of the rotor position correlation signal through an orthogonal signal generator. The specific steps are as follows:

[0020] Step 2.1: Extract and demodulate the rotor position-related signal obtained from the high-frequency current response generated by the random high-frequency square wave voltage signal injected in Step 1;

[0021] Since the frequency of the injected random high-frequency square wave voltage is much greater than the operating frequency of the motor, the permanent magnet synchronous motor can be considered as a purely inductive load. The high-frequency voltage equation of the permanent magnet synchronous motor in the two-phase stationary coordinate system is shown in formula (4):

[0022]

[0023] Among them, i αhk i βhk These are the components of the high-frequency current along the α-axis and β-axis in the k-th switching cycle, respectively, θ r This is the actual rotor position. T -1 (θ r ) is T(θ r The transpose of ), where p is the differential operator;

[0024] The differential of the high-frequency current response is obtained through formula (4) as shown in formula (5):

[0025]

[0026] The difference between two consecutively sampled high-frequency currents obtained from formulas (3) and (5) is shown in formula (6):

[0027]

[0028] Where, Δi αhk It is the difference between the high-frequency current sample value of the k-th switching cycle and the high-frequency current sample value of the (k-1)-th switching cycle on the α-axis, Δi βhk I is the difference between the high-frequency current sample value in the k-th switching cycle and the high-frequency current sample value in the (k-1)-th switching cycle on the β-axis. n =V hk / (πf sk L n );

[0029] Multiply formula (6) by (-1) k The rotor position-related signals are obtained as shown in formula (7):

[0030]

[0031] Where, Δiαdk , Δi βdk These are the rotor position-related signals for the α-axis and β-axis, respectively, θ r This is the actual rotor position;

[0032] Step 2.2: Obtain the orthogonal signals of the rotor position-related signals through an orthogonal signal generator;

[0033] Due to Δi αdk It contains a DC bias and a 2x base frequency signal. When the motor is running at low speed, the DC bias and the 2x base frequency signal are difficult to separate, and Δi βdk It only contains twice the fundamental frequency signal, therefore only Δi is used. βdk To estimate rotor position and speed, the phase-locked loop (PLL) requires orthogonal signals related to rotor position as input. An orthogonal signal generator is used to obtain Δi. βdk The orthogonal signals are shown in formula (6):

[0034]

[0035] Where, Δi βdkq Δi is generated by an orthogonal signal generator βdk orthogonal signals, ω e It is used to estimate the rotor speed, where s is the complex frequency, and c and g are adjustable parameters;

[0036] Using an orthogonal signal generator to measure Δi βdk Noise suppression is performed as shown in formula (10):

[0037]

[0038] Where, Δi βdkp For Δi βdk Rotor position correlation signal after noise suppression;

[0039] Step 3: Using the quadrature signals obtained in Step 2, estimate the rotor position and speed of the permanent magnet synchronous motor through a phase-locked loop. The specific steps are as follows:

[0040] The rotor position error signal calculated using formulas (8) and (10) is shown in formula (11) below:

[0041] ε=Δi βdkp cosθ e -Δi βdkq sinθ e (11)

[0042] Where, θ e This is the estimated rotor position;

[0043] The rotor position error signal ε is adjusted by a PI controller to obtain the estimated rotational speed as shown in the following formula (12):

[0044]

[0045] Among them, K p It is the proportional gain of the PI controller, K i It is the integral gain of the PI controller;

[0046] For the estimated rotational speed ω e The estimated rotor position obtained by integration is shown in formula (13):

[0047]

[0048] Furthermore, in step 1.1, in order to reduce audible noise by lowering the power spectral density of the high-frequency current at the average switching frequency and its integer multiples, m = n = 0.7 is set.

[0049] Furthermore, the adjustable parameters c and g mentioned in step 2.2 are adaptively adjusted according to the principle shown in the following formula (9):

[0050]

[0051] Where, Δω=ω * -ω e ω * The set rotational speed is used to adaptively adjust parameter c based on the absolute value of the difference between the set rotational speed and the estimated rotational speed. When the absolute value of the difference between the set rotational speed and the estimated rotational speed is large, parameter c is adaptively increased to improve the dynamic performance of the quadrature signal generator. When the absolute value of the difference between the set rotational speed and the estimated rotational speed is small, parameter c is adaptively decreased to improve the ability of the quadrature signal generator to suppress interference. When parameter c is greater than 4, c = 4 is set.

[0052] The beneficial effects of this invention are:

[0053] Compared to traditional high-frequency injection methods, this invention injects a random pulsating high-frequency square wave voltage signal into a stationary coordinate system. This random pulsating high-frequency square wave voltage signal follows a Beta distribution, effectively reducing the high-frequency current power spectral density near the average injection frequency and its integer multiples, thereby suppressing audible noise generated by the high-frequency injection method. High-frequency current demodulation obtains the orthogonal signal of the β-axis rotor position correlation signal through an orthogonal signal generator. The dynamic performance and noise suppression capability of the orthogonal signal generator are improved by adaptively adjusting the audible parameter c. The rotor position observation process does not require a DC-biased α-axis high-frequency current, avoiding rotor position errors caused by DC bias. Finally, the rotor position and speed are estimated using a phase-locked loop. This invention suppresses audible noise caused by the high-frequency voltage injection method and solves the rotor position error caused by DC bias in the high-frequency voltage injection method. Attached Figure Description

[0054] Figure 1 This is a block diagram of the vector control system used in the PMSM rotor position and speed estimation method of random square wave voltage injection according to the present invention;

[0055] Figure 2 This is a block diagram of the orthogonal signal generator structure used in the PMSM rotor position and speed estimation method of random square wave voltage injection in this invention;

[0056] Figure 3 This is a block diagram of the phase-locked loop structure used in the method for estimating the position and speed of a PMSM rotor by random square wave voltage injection according to the present invention. Detailed Implementation

[0057] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0058] This invention discloses a method for estimating the rotor position and speed of a PMSM (Polarized Microwave Screwdriver) using random square wave voltage injection. The block diagram of the vector control system for this method is shown below. Figure 1 As shown, the specific steps are as follows:

[0059] Step 1: Using random numbers that follow a Beta distribution, design the random switching frequency of the inverter and inject a random high-frequency square wave voltage signal along the α axis. Specifically:

[0060] Step 1.1: Design the random switching frequency of the inverter using random numbers that follow a Beta distribution;

[0061] The probability density function of the Beta distribution is shown in Equation (1) below:

[0062]

[0063] Where m and n are adjustable parameters greater than 0, x is a generated random number that follows a Beta distribution, and x∈[0,1];

[0064] To make the probability density of the random number x following a Beta distribution symmetric about x = 0.5, we set m = n. When m = n > 1, the probability density function of x is convex; when m = n < 1, the probability density function of x is concave. To reduce the audible noise by lowering the power spectral density of the high-frequency current at the average switching frequency and its integer multiples, we set m = n = 0.7. The random switching frequency of the inverter is generated by the random number x following a Beta distribution as shown in the following formula (2):

[0065] f sk =f min+xΔf (2)

[0066] Among them, f sk It is the random switching frequency of the inverter, f min It is the minimum value of the inverter switching frequency, and Δf is the range of the inverter switching frequency.

[0067] Step 1.2: Inject a random high-frequency square wave voltage signal by designing random numbers that follow a Beta distribution;

[0068] To reduce high-frequency losses while maintaining rotor position estimation accuracy, the amplitude of the high-frequency current response should be equal in each injection cycle. Let the amplitude of the high-frequency current response be I. h Then, a random high-frequency square wave voltage is injected along the α axis as shown in formula (3):

[0069]

[0070] Among them, u αhk u βhk These are the high-frequency square wave voltages injected into the α and β axes respectively during the k-th switching cycle, where k is the count value of the PWM interrupt cycle, V. hk =2πf sk I h L n L is the amplitude of the high-frequency square wave voltage injected in the k-th switching cycle, which varies with the random switching frequency of the inverter. n =2L dh L qh / (L dh +L qh ), L dh L qh These are the inductances along the d-axis and q-axis, respectively.

[0071] Step 2: Extract and demodulate the rotor position correlation signal obtained from the high-frequency current response generated by the random high-frequency square wave voltage signal injected in Step 1, and then process it as follows: Figure 2 The quadrature signal generator shown obtains quadrature signals of rotor position correlation signals, specifically:

[0072] Step 2.1: Extract and demodulate the rotor position-related signal obtained from the high-frequency current response generated by the random high-frequency square wave voltage signal injected in Step 1;

[0073] Since the frequency of the injected random high-frequency square wave voltage is much greater than the operating frequency of the motor, the permanent magnet synchronous motor can be considered as a purely inductive load. The high-frequency voltage equation of the permanent magnet synchronous motor in the two-phase stationary coordinate system is shown in the following formula (4):

[0074]

[0075] Among them, iαhk i βhk These are the components of the high-frequency current along the α-axis and β-axis in the k-th switching cycle, respectively, θ r This is the actual rotor position. T -1 (θ r ) is T(θ r The transpose of ), where p is the differential operator;

[0076] The differential of the high-frequency current response obtained from formula (4) is shown in formula (5) below:

[0077]

[0078] The difference between two consecutively sampled high-frequency currents obtained from formulas (3) and (5) is shown in formula (6) below:

[0079]

[0080] Where, Δi αhk It is the difference between the high-frequency current sample value of the k-th switching cycle and the high-frequency current sample value of the (k-1)-th switching cycle on the α-axis, Δi βhk I is the difference between the high-frequency current sample value in the k-th switching cycle and the high-frequency current sample value in the (k-1)-th switching cycle on the β-axis. n =V hk / (πf sk L n );

[0081] Multiply formula (6) by (-1) k The rotor position related signal is obtained as shown in the following formula (7):

[0082]

[0083] Where, Δi αdk , Δi βdk These are the rotor position-related signals for the α-axis and β-axis, respectively.

[0084] Step 2.2, through as follows Figure 2 The quadrature signal generator shown obtains quadrature signals of rotor position-related signals;

[0085] Due to Δi αdk It contains a DC bias and a 2x base frequency signal. When the motor is running at low speed, the DC bias and the 2x base frequency signal are difficult to separate, and Δi βdk It only contains twice the fundamental frequency signal, therefore only Δi is used. βdk To estimate rotor position and speed, the phase-locked loop (PLL) requires orthogonal signals related to rotor position as input. An orthogonal signal generator is used to obtain Δi. βdkThe orthogonal signals are shown in the following formula (8):

[0086]

[0087] Where, Δi βdkq Δi is generated by an orthogonal signal generator βdk orthogonal signals, ω e It is used to estimate the rotor speed, where s is the complex frequency, and c and g are adjustable parameters;

[0088] The adjustable parameters c and g are adaptively adjusted according to the principle shown in the following formula (9):

[0089]

[0090] Where, Δω=ω * -ω e ω * The set rotational speed is used to adaptively adjust parameter c based on the absolute value of the difference between the set rotational speed and the estimated rotational speed. When the absolute value of the difference between the set rotational speed and the estimated rotational speed is large, parameter c is adaptively increased to improve the dynamic performance of the quadrature signal generator. When the absolute value of the difference between the set rotational speed and the estimated rotational speed is small, parameter c is adaptively decreased to improve the ability of the quadrature signal generator to suppress interference. When parameter c is greater than 4, c = 4 is set.

[0091] Using an orthogonal signal generator to measure Δi βdk The noise suppression is performed as shown in the following formula (10):

[0092]

[0093] Where, Δi βdkp For Δi βdk Rotor position correlation signal after noise suppression;

[0094] Step 3, the orthogonal signals obtained in Step 2 are processed as follows: Figure 3 The phase-locked loop shown estimates the rotor position and speed of the permanent magnet synchronous motor as follows:

[0095] The rotor position error signal calculated using formulas (8) and (10) is shown in formula (11) below:

[0096] ε=Δi βdkp cosθ e -Δi βdkq sinθ e (11)

[0097] Where, θ e This is the estimated rotor position;

[0098] The rotor position error signal ε is adjusted by a PI controller to obtain the estimated rotational speed as shown in the following formula (12):

[0099]

[0100] Among them, K p It is the proportional gain of the PI controller, K i It is the integral gain of the PI controller.

[0101] For the estimated rotational speed ω e The estimated rotor position obtained by integration is shown in the following formula (13):

[0102]

[0103] The block diagram of the vector control system used in a method for estimating the rotor position and speed of a PMSM using random square wave voltage injection is shown below. Figure 1 As shown, the system consists of three PI controllers, forming a dual-loop control system with a speed loop and a current loop. The output of the speed loop PI controller serves as the input to the maximum torque-to-current ratio control (MTPA), and the MTPA outputs the current command. As the input to the current loop PI regulator, the output of the current regulator controls the power electronic converter.

[0104] The processor generates random numbers x, x∈[0,1], that follow a Beta distribution, and adjusts the switching frequency f based on these random numbers. sk =f min +xΔf, adjust the square wave voltage injected into the α axis of the stationary coordinate system in each switching cycle according to the random switching frequency, and then use a current Hall sensor to detect the stator current i of the permanent magnet synchronous motor in the three-phase stationary coordinate system. a i b i c The stator current i a i b i c It includes fundamental frequency current, high-frequency current, and harmonic current; the detected three-phase stator current i a i b i c The current value i is transformed into a two-phase stationary coordinate system through the abc / αβ transformation. sα i sβ i sα i sβ The current value i is transformed into a two-phase synchronous rotating coordinate system through the αβ / dq transformation. sd i sq i sd i sqThe fundamental frequency component i of the stator current in the two-phase synchronous rotating coordinate system is obtained by using a low-pass filter (LPF). d i q Current value i in a two-phase stationary coordinate system sβ The β-axis high-frequency current response Δi is obtained by subtracting the sampled value of the k-th switching cycle from the sampled value of the (k-1)-th switching cycle. βhk High-frequency current response Δi βhk Multiply by (-1) k Obtain the rotor position correlation signal Δi βdk Rotor position related signal Δi βdk After such Figure 2 The quadrature signal generator shown produces the quadrature signal Δi. βdkp , Δi βdkq Orthogonal signal Δi βdkp , Δi βdkq After such Figure 3 The phase-locked loop shown obtains the estimated rotor θ e With rotational speed ω e ; Set the given speed ω of the speed ring * Rotational speed ω estimated by phase-locked loop e The difference is calculated, and after passing through the speed loop PI controller, the electromagnetic torque setpoint is output. The given excitation current is then obtained from the maximum torque-to-current ratio (MTPA). and given torque current Given excitation current With feedback current i d The difference is calculated, and the d-axis voltage is output through the current loop PI controller. Given excitation current With feedback current i q The difference is calculated, and the output q-axis voltage is obtained through a current loop PI controller. The two-phase voltages in the two-phase stationary coordinate system are obtained after dq / αβ transformation. α-axis stator voltage Superimposed injection of high-frequency voltage u αhk and β-axis stator voltage The three-phase inverter is controlled by SVPWM modulation to drive the permanent magnet synchronous motor.

[0105] While specific embodiments of the present invention have been described above, those skilled in the art should understand that these are merely illustrative examples, and the scope of protection of the present invention is defined by the appended claims. Those skilled in the art can make various changes or modifications to these embodiments without departing from the principles and essence of the present invention, but all such changes and modifications fall within the scope of protection of the present invention.

Claims

1. A method for estimating the position and speed of a PMSM rotor by random square wave voltage injection, characterized in that, Specifically, the following steps are included: Step 1: Using random numbers that follow a Beta distribution, design the random switching frequency of the inverter and inject a random high-frequency square wave voltage signal along the α axis. The specific steps are as follows: Step 1.1: Design the random switching frequency of the inverter using random numbers that follow a Beta distribution; The probability density function of the Beta distribution is shown in Equation (1): Where m and n are adjustable parameters greater than 0, x is a generated random number that follows a Beta distribution, and x∈[0,1]; To make the probability density of the random number x following a Beta distribution symmetric about x = 0.5, we set m = n; when m = n > 1, the probability density function of x is convex; when m = n < 1, the probability density function of x is concave; the random switching frequency of the inverter generated by the random number x following a Beta distribution is shown in formula (2): f sk =f min +xΔf (2) Among them, f sk It is the random switching frequency of the inverter, f min It is the minimum value of the inverter switching frequency, and Δf is the range of the inverter switching frequency. Step 1.2: Inject a random high-frequency square wave voltage signal by designing random numbers that follow a Beta distribution; To reduce high-frequency losses while maintaining rotor position estimation accuracy, the amplitude of the high-frequency current response should be equal in each injection cycle. Let the amplitude of the high-frequency current response be I. h Then, a random high-frequency square wave voltage is injected along the α axis as shown in formula (3): Among them, u αhk u βhk These are the high-frequency square wave voltages injected into the α and β axes respectively during the k-th switching cycle, where k is the count value of the PWM interrupt cycle, V. hk =2πf sk I h L n L is the amplitude of the high-frequency square wave voltage injected in the k-th switching cycle, which varies with the random switching frequency of the inverter. n =2L dh L qh / (L dh +L qh ), L dh L qh These are the inductances along the d-axis and q-axis, respectively. Step 2: Extract and demodulate the rotor position correlation signal obtained from the high-frequency current response generated by the random high-frequency square wave voltage signal injected in Step 1, and obtain the orthogonal signal of the rotor position correlation signal through an orthogonal signal generator. The specific steps are as follows: Step 2.1: Extract and demodulate the rotor position-related signal obtained from the high-frequency current response generated by the random high-frequency square wave voltage signal injected in Step 1; Since the frequency of the injected random high-frequency square wave voltage is much greater than the operating frequency of the motor, the permanent magnet synchronous motor is considered to be a purely inductive load. The high-frequency voltage equation of the permanent magnet synchronous motor in the two-phase stationary coordinate system is shown in formula (4): Among them, i αhk i βhk These are the components of the high-frequency current along the α-axis and β-axis in the k-th switching cycle, respectively, θ r This is the actual rotor position. T -1 (θ r ) is T(θ r The transpose of ), where p is the differential operator; The differential of the high-frequency current response is obtained through formula (4) as shown in formula (5): The difference between two consecutively sampled high-frequency currents obtained from formulas (3) and (5) is shown in formula (6): Where, Δi αhk It is the difference between the high-frequency current sample value of the k-th switching cycle and the high-frequency current sample value of the (k-1)-th switching cycle on the α-axis, Δi βhk I is the difference between the high-frequency current sample value in the k-th switching cycle and the high-frequency current sample value in the (k-1)-th switching cycle on the β-axis. n =V hk / (πf sk L n ); Multiply formula (6) by (-1) k The rotor position-related signals are obtained as shown in formula (7): Where, Δi αdk , Δi βdk These are the rotor position-related signals for the α-axis and β-axis, respectively, θ r This is the actual rotor position; Step 2.2: Obtain the orthogonal signals of the rotor position-related signals through an orthogonal signal generator; Due to Δi αdk It contains a DC bias and a 2x base frequency signal. When the motor is running at low speed, the DC bias and the 2x base frequency signal are difficult to separate, and Δi βdk It only contains twice the fundamental frequency signal, therefore only Δi is used. βdk To estimate rotor position and speed, the phase-locked loop (PLL) requires orthogonal signals related to rotor position as input. An orthogonal signal generator is used to obtain Δi. βdk The orthogonal signals are shown in formula (6): Where, Δi βdkq Δi is generated by an orthogonal signal generator βdk orthogonal signals, ω e It is used to estimate the rotor speed, where s is the complex frequency, and c and g are adjustable parameters; Using an orthogonal signal generator to measure Δi βdk Noise suppression is performed as shown in formula (10): Where, Δi βdkp For Δi βdk Rotor position correlation signal after noise suppression; Step 3: Using the quadrature signals obtained in Step 2, estimate the rotor position and speed of the permanent magnet synchronous motor through a phase-locked loop. The specific steps are as follows: The rotor position error signal calculated using formulas (8) and (10) is shown in formula (11) below: e=Δi βdkp cosθ e -Yes βdkq sinth e (11) Where, θ e This is the estimated rotor position; The rotor position error signal ε is adjusted by a PI controller to obtain the estimated rotational speed as shown in the following formula (12): Among them, K p It is the proportional gain of the PI controller, K i It is the integral gain of the PI controller; For the estimated rotational speed ω e The estimated rotor position obtained by integration is shown in formula (13):

2. The method for estimating the position and speed of a PMSM rotor by random square wave voltage injection according to claim 1, characterized in that, In step 1.1, in order to reduce the audible noise by lowering the power spectral density of the high-frequency current at the average switching frequency and its integer multiples, m = n = 0.7 is set.

3. The method for estimating the position and speed of a PMSM rotor by random square wave voltage injection according to claim 1, characterized in that, The adjustable parameters c and g mentioned in step 2.2 are adaptively adjusted according to the principle shown in the following formula (9): Where, Δω=ω * -ω e ω * The set rotational speed is used to adaptively adjust parameter c based on the absolute value of the difference between the set rotational speed and the estimated rotational speed. When the absolute value of the difference between the set rotational speed and the estimated rotational speed is large, parameter c is adaptively increased to improve the dynamic performance of the quadrature signal generator. When the absolute value of the difference between the set rotational speed and the estimated rotational speed is small, parameter c is adaptively decreased to improve the ability of the quadrature signal generator to suppress interference. When parameter c is greater than 4, c = 4 is set.

Images