A method for detecting the rotor position of a synchronous machine during static variable frequency starting

Abstract

A method for detecting the medium- and high-frequency rotor position during static variable-frequency starting of a synchronous machine includes: utilizing motor parameters and machine-end electrical quantity signals to obtain the αβ-axis machine-end voltage and current components; adaptively filtering the αβ-axis machine-end voltage and current components with a second-order generalized integrator with a variable center frequency based on the center frequency output by a dynamic feedforward phase-locked loop (PFLL) to obtain the filtered machine-end voltage, filtered motor current, and filtered quadrature current; phase-locking the filtered machine-end voltage using a dynamic feedforward phase-locked loop to obtain the machine-end voltage phase angle and motor speed, with the motor speed being input into a second-order generalized integrator as the center frequency feedback value; calculating the internal voltage and machine-end motor flux based on the motor parameters, filtered motor current, and filtered quadrature current; and determining the medium- and high-frequency rotor position angle based on the machine-end motor flux. This method accurately calculates the rotor position of a synchronous machine operating at 3Hz to 60Hz, enabling smooth starting of the synchronous machine.

Description

Technical Field

[0001] The present invention belongs to the technical field of motor driving, and in particular relates to a method for detecting a medium- and high-frequency rotor position during static variable-frequency starting of a synchronous machine. Background Art

[0002] In the field of synchronous motor starting, static inverters are often the preferred starting method due to their high starting efficiency, minimal system impact during the startup process, and excellent economic efficiency. Current source inverters are the preferred choice for large synchronous motors. During the startup process, current source inverters require real-time, highly accurate acquisition of the synchronous motor's rotor position to trigger the inverter side. Rotor position detection is highly dependent on the motor's terminal voltage and current. In actual synchronous motors, the voltage and current waveforms during current source inverter startup are severely degraded due to thyristor commutation, significantly reducing the accuracy of rotor position detection and further impacting the control process.

[0003] In the prior art, for detecting the rotor position during static variable frequency starting of a synchronous machine, a combination of a high-pass filter and a low-pass filter is usually used to filter the machine-end voltage. This method requires different filtering parameters in the low-frequency and high-frequency stages, and phase compensation is performed by providing the rotational speed through the motor body, which makes the control complex. Moreover, when solving the rotor position, the tangent method is usually used, which has poor anti-interference ability and is prone to fluctuations, resulting in commutation failure on the inverter side. Summary of the Invention

[0004] To address the deficiencies in the prior art, the present invention provides a method for detecting the rotor position of a synchronous machine during static variable-frequency starting. The method calculates the motor speed with high precision within a wide frequency band of 3-60 Hz and adaptively filters the voltage and current at the machine end. The motor magnetic flux is then calculated based on the filtered voltage and current, and the rotor position of the synchronous machine is locked, thereby achieving a smooth starting of the synchronous machine.

[0005] The present invention adopts the following technical solutions.

[0006] The present invention proposes a method for detecting the position of a medium-high frequency rotor during static variable frequency starting of a synchronous machine, comprising:

[0007] Step 1: Obtain motor parameters and motor-side electrical quantity signals;

[0008] Step 2: Use the motor parameters and the electrical quantity signal at the machine end to obtain the voltage component u of the αβ axis machine end α 、u β and the current component i α 、i β ;

[0009] Step 3: According to the center frequency ω output by the dynamic feedforward phase-locked loop MThe voltage component u at the machine end of the αβ axis α 、u β and the current component i α , ix performs adaptive filtering with a second-order generalized integrator with a variable center frequency to obtain the terminal voltage u after filtering α ′、u β ′、Filtered motor current i α ′、i β ′ and the filtered quadrature current i qα ′、i qβ ';

[0010] Step 4: Use a dynamic feedforward phase-locked loop to phase-lock the filtered terminal voltage to obtain the terminal voltage phase angle θ u and motor speed ω M , with motor speed ω M As the center frequency feedback value input to the second-order generalized integrator;

[0011] Step 5: According to the motor parameters, the motor current i is filtered α ′、i β ′ and the filtered quadrature current i qα ′、i qβ Calculate the internal potential e α 、e β , and the motor flux at the end of the computer is calculated based on the internal potential ψ α , ψ β ; According to the motor flux ψ α , ψ β Determine the medium and high frequency rotor position angle θ M .

[0012] Preferably, in step 1, the motor parameters include: stator equivalent inductance L M , stator equivalent resistance r M ; The electrical quantity signals at the machine end include: the line voltage u AB 、u BC 、u CA , the machine end phase current i A 、i B 、i C .

[0013] Preferably, in step 2, the terminal line voltage u AB 、u BC 、u CA , the machine end phase current i A 、i B 、i C , stator equivalent inductance L M , stator equivalent resistance r M The average is normalized to the corresponding per-unit value u AB ′、uBC ′、u CA ′、i A ′、i B ′、i C ′、L M ′、r M ′; and the per-unit value u AB ′、u BC ′、u CA ′、i A ′、i B ′、i C ′The voltage component u of the αβ axis terminal is obtained by Clark transformation α 、u β and the current component i α 、i β .

[0014] Preferably, the terminal voltage u after filtering α ′、u β 'for:

[0015]

[0016] Motor current after filtering i α ′、i β 'for:

[0017]

[0018] Filtered quadrature current i qα ′、i qβ ′ is the same as i α ′、i β 'The orthogonal current components are as follows:

[0019]

[0020] Where,

[0021] H d (z) and H q (z) are the transfer functions of the output of the adaptive filter of the second-order generalized integrator with variable center frequency and its orthogonal quantity,

[0022] b0 is the closed-loop gain of the filter discrete transfer function,

[0023] a1 and a2 are the first and second coefficients of the denominator polynomial of the filter discrete transfer function, respectively, and satisfy: where x = 2kω M T s , y=(ω M T s ) 2 ,

[0024] T s To control the cycle,

[0025] ω M is the center frequency of the dynamic phase-locked loop output, that is, the motor speed,

[0026] k is the filter gain,

[0027] i qα 、i qβ and i α 、i β Orthogonal current components

[0028] z -1 is a unit time delay operator, z -2 is a 2-unit time delay operator.

[0029] Preferably, in step 4, the dynamic feedforward phase-locked loop input is the d-axis machine terminal voltage u d :

[0030] u d = sinθ u u α ′-cosθ u u β '

[0031] Where,

[0032] θ u is the phase angle of the terminal voltage, mod is the π / 2 rounding function.

[0033] Preferably, in step 4, the motor speed ω M The calculation formula is as follows:

[0034]

[0035] Where,

[0036] k pu 、k iu They are the proportional and integral coefficients of the dynamic feedforward phase-locked loop,

[0037] ω set is the dynamic feedforward factor.

[0038] Preferably, the internal potential e α 、eβ 计 The calculation formula is:

[0039]

[0040] Where,

[0041] r M ′、LM ′ is the stator equivalent inductance L M The per-unit value and stator equivalent resistance r M The per-unit value of

[0042] ω M ′ is the per-unit value of the motor speed, satisfying ωB 为 Speed ​​reference value.

[0043] Preferably, the motor flux ψ α , ψ β The calculation formula is:

[0044]

[0045] Where θ rotate is the rotation angle.

[0046] Preferably, the input of the flux loop is the q-axis flux ψ q :

[0047] ψ q = -sinθ M ψ α +cosθ M ψ β

[0048] Where θ M is the medium and high frequency rotor position angle.

[0049] Preferably, the medium and high frequency rotor position angle θ M The calculation formula is as follows:

[0050]

[0051] Where,

[0052] ψ d is the d-axis magnetic flux,

[0053] k pM 、k iM are the proportional and integral coefficients of the flux phase-locked loop respectively.

[0054] The beneficial effect of the present invention is that, compared with the prior art, the method proposed in the present invention adaptively filters out the voltage gap caused by commutation during the startup of the synchronous machine and the DC voltage bias at low frequency according to the motor speed, and finally accurately calculates the rotor position of the synchronous machine operating at 3Hz to 60Hz.

[0055] The present invention filters the voltage and current of the unit through a bandpass filter with a variable center frequency, calculates the magnetic flux of the motor based on the filtered voltage and current and motor parameters, and finally phase-locks the magnetic flux through a variable-feedforward wide-band phase-locked loop to obtain the high-precision high-frequency motor rotor position, providing a speed closed-loop commutation basis for the synchronous machine startup.

[0056] The present invention has the characteristics of simple control structure, wide frequency adaptability, high rotor position calculation accuracy and strong anti-interference ability. BRIEF DESCRIPTION OF THE DRAWINGS

[0057] Figure 1 This is a flow chart of a method for detecting the position of a medium- and high-frequency rotor during static variable-frequency starting of a synchronous machine proposed by the present invention;

[0058] Figure 2 is a schematic diagram of the main circuit in an embodiment of the present invention;

[0059] Figure 2 The reference numerals in the figures are described as follows:

[0060] TV1, TV2, TV3, TV4, TV5, TV6 - the first thyristor, second thyristor, third thyristor, fourth thyristor, fifth thyristor, and sixth thyristor of the upper half arm of the rectifier bridge;

[0061] TV1', TV2', TV3', TV4', TV5', TV6' - the first thyristor, second thyristor, third thyristor, fourth thyristor, fifth thyristor, and sixth thyristor of the lower half arm of the rectifier bridge;

[0062] TV1”, TV2”, TV3”, TV4”, TV5”, TV6” - the first thyristor, second thyristor, third thyristor, fourth thyristor, fifth thyristor, and sixth thyristor of the inverter bridge;

[0063] L-smoothing reactor;

[0064] Figure 3 Schematic diagram of the control principle in an embodiment of the present invention;

[0065] Figure 4 2 is a control effect diagram in an embodiment of the present invention. DETAILED DESCRIPTION

[0066] To make the objectives, technical solutions, and advantages of the present invention more clear, the technical solutions of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. The embodiments described in this application are only part of the embodiments of the present invention, not all of them. Based on the spirit of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0067] On the one hand, the present invention proposes a medium-high frequency rotor position detection method during the static variable frequency starting of a synchronous machine. During the static starting process of the synchronous machine, by collecting the electrical quantities of the synchronous machine end and its own parameters and using the medium-high frequency rotor position detection method, real-time high-precision rotor position and speed estimation during the starting process is achieved, thereby realizing smooth and uniform starting of the synchronous machine.

[0068] like Figure 1 As shown in the figure, a method for detecting the rotor position of a synchronous machine during static variable frequency starting is suitable for Figure 2 The main circuit shown includes:

[0069] Step 1: Obtain motor parameters and motor-end electrical quantity signals.

[0070] Figure 2 In the main circuit shown, the grid is connected to the synchronous machine via a phase-shifting transformer, a 12-pulse rectifier bridge, a smoothing reactor, and a 6-pulse inverter bridge. The 12-pulse rectifier bridge includes an upper arm and a lower arm, each with six thyristors. The 6-pulse inverter bridge also includes six thyristors.

[0071] Among them, the motor parameters include: stator equivalent inductance L M , stator equivalent resistance r M ; The electrical quantity signals at the machine end include: the line voltage u AB 、u BC 、u CA , the machine end phase current i A 、i B 、i c .

[0072] Step 2: Use the motor parameters and the electrical quantity signal at the machine end to obtain the voltage component u of the αβ axis machine end α 、u β and the current component i α 、i β .

[0073] The terminal line voltage u AB 、u BC 、u CA , the machine end phase current i A 、i B 、i C , stator equivalent inductance L M , stator equivalent resistance r M The average is normalized to the corresponding per-unit value u AB ′、u BC ′、u CA ′、i A ′、i B ′、i C ′、L M′、r M ′; and the per-unit value u AB ′、u BC ′、u CA ′、i A ′、i B ′、i C ′The voltage component u of the αβ axis terminal is obtained by Clark transformation α 、u β and the current component i α 、i β .

[0074] Machine end line voltage u AB 、u Bc 、u CA and the machine-end phase current i A 、i B 、i C The per-unit normalization formula is as follows:

[0075]

[0076]

[0077] In the formula

[0078] u AB ′、u BC ′、u CA ′ and i A ′、i B ′、i C ′ are the per unit values ​​of the machine-end line voltage and the machine-end phase current, Among them, u N 、i N They are the rated voltage and rated current of the machine end respectively.

[0079] The formula for normalizing motor parameters is as follows:

[0080]

[0081]

[0082] Where,

[0083] z B As the reference impedance, u B is the phase voltage at the machine end,

[0084] L B As the reference inductance,

[0085] ω B The speed reference value.

[0086] αβ axis machine end voltage component u α 、u β and the current component i α 、i β The linear transformation formula is as follows:

[0087]

[0088]

[0089] Step 3, such as Figure 3 As shown, according to the center frequency ω output by the dynamic feedforward phase-locked loop M The voltage component u at the machine end of the αβ axis α 、u β and the current component i α 、i β Perform adaptive filtering with a second-order generalized integrator with variable center frequency to obtain the terminal voltage u after filtering. α ′、u β ′、Filtered motor current i α ′、i β ′ and the filtered quadrature current i qα ′、i qβ ′.

[0090] Among them, after filtering using a second-order generalized integral adaptive filter with a variable center frequency, the discrete forms of the voltage and current are as follows:

[0091] Terminal voltage u after filtering α ′、u β 'for:

[0092]

[0093] Motor current after filtering i α ′、i β 'for:

[0094]

[0095] Filtered quadrature current i qα ′、i qβ ′ is the same as i α ′、i β 'The orthogonal current components are as follows:

[0096]

[0097] Where,

[0098] H d (z) and H q(z) are the transfer functions of the output of the adaptive filter of the second-order generalized integrator with variable center frequency and its orthogonal quantity,

[0099] b0 is the closed-loop gain of the filter discrete transfer function,

[0100] a1 and a2 are the first and second coefficients of the denominator polynomial of the filter discrete transfer function, respectively, and satisfy: where x = 2kω M T s , y=(ω M T s ) 2 ,

[0101] T s To control the cycle,

[0102] ω M is the center frequency of the dynamic phase-locked loop output, that is, the motor speed,

[0103] k is the filter gain,

[0104] i qα 、i q x and i α 、i β Orthogonal current components

[0105] z -1 is a unit time delay operator, z -2 is a 2-unit time delay operator.

[0106] Step 4: Use a dynamic feedforward phase-locked loop to phase-lock the filtered terminal voltage to obtain the terminal voltage phase angle θ u and motor speed ω M , with motor speed ω M It is input as the center frequency feedback value to the second-order generalized integrator.

[0107] The dynamic feedforward phase-locked loop input is the d-axis terminal voltage u d :

[0108] u d = sinθ u u α ′-cosθ u u β '

[0109] Where,

[0110] θ u is the phase angle of the terminal voltage, mod is the π / 2 rounding function.

[0111] Center frequency ω M The calculation formula is as follows:

[0112]

[0113] Where,

[0114] k pu 、k iu They are the proportional and integral coefficients of the dynamic feedforward phase-locked loop,

[0115] ω set is the dynamic feedforward factor.

[0116] Step 5: According to the motor parameters, the motor current i is filtered α ′、i β ′ and the filtered quadrature current i qα ′、i qβ Calculate the internal potential e α 、e β , and the motor flux at the end of the computer is calculated based on the internal potential ψ α , ψ β ; According to the motor flux ψ α , ψ β Determine the medium and high frequency rotor position angle θ M .

[0117] Internal potential e α 、e β The calculation formula is:

[0118]

[0119] Where,

[0120] r M ′、L M ′ is the stator equivalent inductance L M The per-unit value and stator equivalent resistance r M The per-unit value of

[0121] ω M ′ is the per-unit value of the motor speed, satisfying ω B The speed reference value.

[0122] The calculated internal potential e is rotated by vector α 、e β Directly rotate 90° to get the motor flux ψ d , ψ q .

[0123] Motor flux ψ d , ψ q The calculation formula is:

[0124]

[0125] Where θ rotate is the rotation angle.

[0126] The input of the flux loop is the q-axis flux ψ q :

[0127] ψ q = -sinθ M ψα+cosθ M ψ β

[0128] High-frequency rotor position angle θ M The calculation formula is as follows:

[0129]

[0130] Where,

[0131] ψ d is the d-axis magnetic flux,

[0132] k pM 、k iM are the proportional and integral coefficients of the flux phase-locked loop respectively.

[0133] like Figure 4 As shown, the method proposed in the present invention adaptively filters out the voltage gap caused by commutation during the startup of the synchronous machine and the voltage DC bias at low frequency according to the motor speed, and finally accurately calculates the rotor position of the synchronous machine running at 3Hz to 60Hz.

[0134] The present invention filters the voltage and current of the unit through a bandpass filter with a variable center frequency, calculates the magnetic flux of the motor based on the filtered voltage and current and motor parameters, and finally phase-locks the magnetic flux through a variable-feedforward wide-band phase-locked loop to obtain the high-precision high-frequency motor rotor position, providing a speed closed-loop commutation basis for the synchronous machine startup.

[0135] The present invention has the advantages of wide adaptability frequency band, high rotor position measurement accuracy, simple structure, and is convenient for practical application.

[0136] The present disclosure may be a system, method and / or computer program product. The computer program product may include a computer-readable storage medium carrying computer-readable program instructions for causing a processor to implement various aspects of the present disclosure.

[0137] A computer-readable storage medium can be a tangible device that can hold and store instructions for use by an instruction execution device. A computer-readable storage medium can be, for example, but not limited to, an electrical storage device, a magnetic storage device, an optical storage device, an electromagnetic storage device, a semiconductor storage device, or any suitable combination thereof. More specific examples (a non-exhaustive list) of computer-readable storage media include: a portable computer disk, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), a static random access memory (SRAM), a portable compact disc read-only memory (CD-ROM), a digital versatile disk (DVD), a memory stick, a floppy disk, a mechanical encoding device, such as a punch card or a raised structure in a groove on which instructions are stored, and any suitable combination thereof. As used herein, a computer-readable storage medium is not to be construed as a transient signal per se, such as a radio wave or other freely propagating electromagnetic wave, an electromagnetic wave propagating through a waveguide or other transmission medium (e.g., a light pulse through a fiber optic cable), or an electrical signal transmitted through an electrical wire.

[0138] The computer-readable program instructions described herein can be downloaded from a computer-readable storage medium to each computing / processing device, or downloaded to an external computer or external storage device via a network, such as the Internet, a local area network, a wide area network, and / or a wireless network. The network can include copper transmission cables, fiber optic transmission, wireless transmission, routers, firewalls, switches, gateway computers, and / or edge servers. The network adapter card or network interface in each computing / processing device receives the computer-readable program instructions from the network and forwards the computer-readable program instructions to be stored in the computer-readable storage medium in each computing / processing device.

[0139] The computer program instructions for performing the operations of the present disclosure may be assembly instructions, instruction set architecture (ISA) instructions, machine instructions, machine-dependent instructions, microcode, firmware instructions, state setting data, or source code or object code written in any combination of one or more programming languages, including object-oriented programming languages ​​such as Smalltalk, C++, and conventional procedural programming languages ​​such as "C" language or similar programming languages. Computer-readable program instructions may be executed entirely on a user's computer, partially on a user's computer, as an independent software package, partially on a user's computer, partially on a remote computer, or entirely on a remote computer or server. In the case of a remote computer, the remote computer may be connected to the user's computer via any type of network, including a local area network (LAN) or a wide area network (WAN), or may be connected to an external computer (e.g., utilizing an Internet service provider to connect via the Internet). In some embodiments, an electronic circuit, such as a programmable logic circuit, a field programmable gate array (FPGA), or a programmable logic array (PLA), may be personalized by utilizing the state information of the computer-readable program instructions. The electronic circuit may execute the computer-readable program instructions, thereby realizing various aspects of the present disclosure.

[0140] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the field should understand that the specific implementation methods of the present invention can still be modified or replaced by equivalents. Any modification or equivalent replacement that does not depart from the spirit and scope of the present invention should be covered by the scope of protection of the claims of the present invention.

Claims

1. A method for detecting the rotor position of a synchronous machine during static variable frequency starting, characterized in that: include: Step 1: Obtain motor parameters and motor-end electrical quantity signals; motor parameters include: stator equivalent inductance L M , stator equivalent resistance r M ; The electrical quantity signals at the machine end include: the line voltage u AB 、u BC 、u CA , the machine end phase current i A 、i B 、i C ; Step 2: Use the motor parameters and the electrical quantity signal at the machine end to obtain the voltage component u of the αβ axis machine end α 、u β and the current component i α 、i β ; Step 3: According to the center frequency ω output by the dynamic feedforward phase-locked loop M The voltage component u at the machine end of the αβ axis α 、u β and the current component i α 、i β Perform adaptive filtering with a second-order generalized integrator with variable center frequency to obtain the terminal voltage u after filtering. α ′、u β ′、Filtered motor current i α ′、i β ′ and the filtered quadrature current i qα ′、i qβ '; terminal voltage u after filtering α ′、u β 'for: Motor current after filtering i α ′、i β 'for: Filtered quadrature current i qα ′、i qβ ′ is the same as i α ′、i β 'The orthogonal current components are as follows: Where H d (z) and H q (z) are the transfer functions of the output of the second-order generalized integrator adaptive filter with variable center frequency and its orthogonal quantity, b0 is the closed-loop gain of the filter discrete transfer function, a1 and a2 are the first and second coefficients of the denominator polynomial of the filter discrete transfer function, and satisfy: Where x = 2kω M T s , y=(ω M T s ) 2 , T s is the control period, k is the filter gain, i qα 、i qβ and i α 、i β Orthogonal current components, z -1 is a unit time delay operator, z -2 is a 2-unit time delay operator; Step 4: Use a dynamic feedforward phase-locked loop to phase-lock the filtered terminal voltage to obtain the terminal voltage phase angle θ u and motor speed ω M , with motor speed ω M As the center frequency feedback value input to the second-order generalized integrator; Step 5: According to the motor parameters, the motor current i is filtered α ′、i β ′ and the filtered quadrature current i qα ′、i qβ Calculate the internal potential e α 、e β , and based on the internal potential, the computer end motor flux Ψ α ,Ψ β ; According to the motor flux Ψ α ,Ψ β Determine the medium and high frequency rotor position angle θ M .

2. The method for detecting the medium and high frequency rotor position during static frequency conversion starting of a synchronous machine according to claim 1, characterized in that: include: In step 2, the terminal line voltage u AB 、u BC 、u CA , the machine end phase current i A 、i B 、i C , stator equivalent inductance L M , stator equivalent resistance r M The average is normalized to the corresponding per-unit value u AB ′、u BC ′、u CA ′、i A ′、i B ′、i C ′、L M ′、r M ′; and the per-unit value u AB ′、u BC ′、u CA ′、i A ′、i B ′、i C ′The voltage component u of the αβ axis terminal is obtained by Clark transformation α 、u β and the current component i α 、i β .

3. The method for detecting the medium and high frequency rotor position during static frequency conversion starting of a synchronous machine according to claim 1, characterized in that: include: In step 4, the dynamic feedforward phase-locked loop input is the d-axis terminal voltage u d : in d =sinθ u in α ′-cosθ u in β ′ Where θ u is the phase angle of the terminal voltage, mod is the π / 2 rounding function.

4. The method for detecting the medium and high frequency rotor position during static variable frequency starting of a synchronous machine according to claim 3, characterized in that: include: In step 4, the motor speed ω M The calculation formula is as follows: Where k pu 、k iu They are respectively the proportional and integral coefficients of the dynamic feedforward phase-locked loop, ω set is the dynamic feedforward factor.

5. The method for detecting the medium and high frequency rotor position during static frequency conversion starting of a synchronous machine according to claim 1, characterized in that: include: Internal potential e α 、e β The calculation formula is: Where r M ′、L M ′ is the stator equivalent inductance L M The per-unit value and stator equivalent resistance r M The per-unit value, ω M ′ is the per-unit value of the motor speed, satisfying ω B The speed reference value.

6. The method for detecting the medium and high frequency rotor position during static variable frequency starting of a synchronous machine according to claim 5, characterized in that: include: Motor flux Ψ α ,Ψ β The calculation formula is: Where θ rotate is the rotation angle.

7. The method for detecting the medium and high frequency rotor position during static variable frequency starting of a synchronous machine according to claim 6, characterized in that: include: The input of the flux loop is the q-axis flux Ψ q : P q =-sinθ M P α +cosθ M P β Where θ M is the medium and high frequency rotor position angle.

8. The method for detecting the medium and high frequency rotor position during static variable frequency starting of a synchronous machine according to claim 7, characterized in that: include: Medium and high frequency rotor position angle θ M The calculation formula is as follows: Where, d is the d-axis magnetic flux, k pM 、k iM are the proportional and integral coefficients of the flux phase-locked loop respectively.

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