Permanent magnet synchronous motor turn-to-turn short circuit fault diagnosis method based on high-frequency negative sequence component

Abstract

The invention discloses a permanent magnet synchronous motor turn-to-turn short circuit fault diagnosis method based on a high-frequency negative-sequence component, and the method comprises the steps: obtaining a high-frequency voltage injection signal according to the three-phase current of a motor, obtaining a high-frequency current signal through space vector pulse width modulation, injecting the high-frequency current signal into the motor, obtaining the three-phase voltage and three-phase current of the current motor, and extracting a high-frequency component in the three-phase voltage and three-phase current; high-frequency negative-sequence voltage and high-frequency negative-sequence current are obtained according to the extracted high-frequency components, and fault features are constructed; comparing the fault feature with a fault threshold value, judging that the permanent magnet synchronous motor is healthy if the fault feature is smaller than the fault threshold value, and judging that the permanent magnet synchronous motor is faulty if the fault feature is larger than or equal to the fault threshold value. According to the method, extra detection hardware is not needed, real-time detection and positioning of the turn-to-turn short circuit fault can be realized by using the negative sequence component of the motor in the high-frequency domain in the servo operation state of the permanent magnet synchronous motor, and the method has relatively high applicability and robustness.

Description

Technical Field

[0001] This invention belongs to the field of motor fault diagnosis technology, and specifically relates to a method for diagnosing inter-turn short-circuit faults in permanent magnet synchronous motors based on high-frequency negative sequence components. Background Technology

[0002] With the development of rare-earth permanent magnet materials and power electronics technology, permanent magnet synchronous motors (PMSMs) have been widely used in servo systems due to their high efficiency, high power density, and high torque density. However, servo systems often operate in harsh environments such as overheating, overvoltage, and shocks, which can easily lead to significant thermal, electrical, and mechanical stresses on the winding insulation, increasing the risk of failure. Statistics show that stator winding faults account for 21%–37% of motor failures, with inter-turn short circuit faults (ISCF) being the most common. ISCF causes increased circulating current, increased losses and heat generation, weakened magnetic permeability, as well as vibration and noise, and may develop into phase-to-phase or ground short circuits within a short period of time, causing downtime, damage, or even serious accidents. Therefore, ISCF diagnosis is crucial for ensuring the stable operation of PMSM servo systems and achieving fault-tolerant control after a fault.

[0003] However, under servo operating conditions, the PMSM frequently experiences changes in speed and load, causing fluctuations in the amplitude and phase of the fundamental signal. This makes it easy for fault characteristics based on the fundamental signal in traditional fault diagnosis methods to be masked or distorted, leading to misdiagnosis or missed diagnosis. Therefore, traditional methods have poor reliability and robustness in fault diagnosis under servo operating conditions. Summary of the Invention

[0004] The purpose of this invention is to provide a method for diagnosing inter-turn short-circuit faults in permanent magnet synchronous motors based on high-frequency negative sequence components. This method requires no additional detection hardware and can achieve real-time detection and location of inter-turn short-circuit faults by utilizing the negative sequence components of the motor in the high-frequency domain during servo operation of the permanent magnet synchronous motor. It has high applicability and robustness.

[0005] To achieve the above objectives, the solution of the present invention is:

[0006] A method for diagnosing inter-turn short-circuit faults in permanent magnet synchronous motors based on high-frequency negative sequence components includes the following steps:

[0007] Step 1, based on the three-phase current i of the motor a0 i b0 i c0 High-frequency voltage injection signal u is obtained αh0 ,u βh0 The high-frequency voltage injection signal is modulated by space vector pulse width modulation to obtain a high-frequency current signal;

[0008] Step 2: Inject the high-frequency current signal into the motor to obtain the current three-phase voltage u of the motor.a1 ,u b1 ,u c1 and three-phase current i a1 i b1 i c1 And extract the high-frequency components u from them respectively. αh1 ,u βh1 i αh1 i βh1 ;

[0009] Step 3, based on the extracted high-frequency component u αh1 ,u βh1 i αh1 i βh1 High-frequency negative sequence voltage is obtained. and high-frequency negative sequence current And based on the high-frequency negative sequence voltage and high-frequency negative sequence current Constructing fault features μI fh ;

[0010] Step 4, transfer the fault feature μI fh The fault feature μI is compared with a fault threshold. fh If the value is less than the fault threshold, the permanent magnet synchronous motor is judged to be healthy. The fault characteristic μI fh If the value is greater than or equal to the fault threshold, the permanent magnet synchronous motor is considered to be faulty.

[0011] The specific process of step 1 is as follows:

[0012] Step 11, convert the three-phase current i of the motor a0 i b0 i c0 The actual value of the dq-axis high-frequency current i is obtained by transforming the three-phase stationary to two-phase rotating high-frequency coordinates and then passing it through a low-pass filter. dh0 i qh0 ,

[0013] [i dh0 i qh0 ] T =T 3s-2r (ω h t)·[i a0 i b0 i c0 ] T

[0014] Among them, T 3s-2r (ω h t) is the high-frequency rotating coordinate transformation matrix from three-phase stationary to two-phase rotating, as shown in the following equation.

[0015]

[0016] Where, ω h The angular frequency of the injected signal;

[0017] Step 12, based on the actual value i of the dq axis high-frequency current. dh0 i qh0 Calculate the high-frequency voltage injection signal u αh0 and u βh0 ,

[0018]

[0019] Where, k p and k i These are the proportional and integral coefficients of the proportional-integral controller, respectively; i qhref This is the reference value for the q-axis high-frequency current; L s =LM is the synchronous inductance of the permanent magnet synchronous motor, L is the self-inductance of the motor windings, and M is the mutual inductance of the motor windings; T is the high-frequency rotating coordinate transformation matrix from two-phase rotation to two-phase stationary. 2r-2s (ω h t) is shown in the following formula.

[0020]

[0021] Step 13, inject high-frequency voltage into signal u αh0 and u βh0 u, respectively superimposed on the vector control of the permanent magnet synchronous motor α0 and u β0 Then, the superimposed signal is input into the space vector pulse width modulation to obtain the high-frequency current signal required to inject into the motor.

[0022] In step 2, the current three-phase voltage u of the motor is... a1 ,u b1 ,u c1 and three-phase current i a1 i b1 i c1 Perform a rotating coordinate transformation from three-phase stationary to two-phase stationary to obtain the two-phase voltage u of the motor. α1 ,u β1 and two-phase current i α1 i β1 ,

[0023] [u α1 u β1 ] T =T 3s-2s ·[u a1 u b1 u c1 ] T

[0024] [i α1 i β1 ] T =T 3s-2s ·[i a1 i b1 i c1 ] T

[0025] Among them, the rotating coordinate transformation matrix T from three-phase stationary to two-phase stationary is... 3s-2s as follows,

[0026]

[0027] A second-order generalized integrator is used to extract the two-phase voltage u of the motor. α1 ,u β1 High-frequency components u αh1 ,u βh1 and two-phase current i α1 i β1 High-frequency components i αh1 i βh1 Its calculation formula is,

[0028] [u αh1 u βh1 ] T =SOGI[u α1 u β1 ] T

[0029] [i αh1 i βh1 ] T =SOGI[i α1 i β1 ] T

[0030] Here, SOGI represents a second-order generalized integrator, whose expression is as follows:

[0031]

[0032] Among them, Y (z) X is the output signal of the second-order generalized integrator. (z) X is the input signal of the second-order generalized integrator. (z-2) To delay the input signal by two control cycles, Y (z-1) To delay the output signal by one control cycle, Y (z-2) The output signal is delayed by two control cycles; k is the damping coefficient of the second-order generalized integrator; f c f is the frequency of the high-frequency signal. s This is the sampling frequency of the control system.

[0033] In step 3, based on the extracted high-frequency component u αh1 ,u βh1 The high-frequency negative sequence voltage component was obtained. The specific process is as follows:

[0034] The high-frequency component u at time t αh1 ,u βh1 Write it as the following expression:

[0035]

[0036] Among them, u ph and θ up These represent the amplitude and phase of the high-frequency positive-sequence voltage, u. nh and θ un These represent the amplitude and phase of the high-frequency negative sequence voltage, respectively; ω h The angular frequency of the injected signal;

[0037] The αβ axis high-frequency voltage at time t is delayed by 1 / 4 of a high-frequency period T. h The high-frequency voltage at this time is obtained.

[0038]

[0039] The high-frequency negative sequence voltages along the αβ axis are then obtained as follows:

[0040]

[0041] Construct the high-frequency negative sequence voltage as follows:

[0042]

[0043] in, It is a high-frequency negative sequence voltage;

[0044] Based on the extracted high-frequency component i αh1 i βh1 The high-frequency negative sequence current component was obtained. The specific process is as follows:

[0045] The high-frequency component i at time t αh1 i βh1 Write it as the following expression:

[0046]

[0047] Among them, i ph and θ ip i represents the amplitude and phase of the high-frequency positive-sequence current, respectively. nh and θ in These represent the amplitude and phase of the high-frequency negative sequence current, respectively.

[0048] The αβ axis high-frequency current at time t is delayed by 1 / 4 high-frequency period T. h The high-frequency current at this time is obtained.

[0049]

[0050] The high-frequency negative sequence currents along the αβ axis are then obtained as follows.

[0051]

[0052] The high-frequency negative sequence current is constructed as follows:

[0053]

[0054] in, It is a high-frequency negative sequence current.

[0055] In step 3, based on the high-frequency negative sequence voltage and high-frequency negative sequence current The fault characteristic μI is constructed according to the following formula. fh ,

[0056]

[0057] Among them, R s L is the winding resistance of a permanent magnet synchronous motor. s For the synchronous inductance of a permanent magnet synchronous motor, ω h ω is the angular frequency of the injected signal.

[0058] Step 4 further includes determining the minimum phase difference d based on the phase difference between the high-frequency phase voltage and the high-frequency negative sequence current when judging a fault in the permanent magnet synchronous motor. x An inter-turn short-circuit fault occurs in the phase, x = a, b, c.

[0059] The specific process for calculating the phase difference between the high-frequency phase voltage and the high-frequency negative-sequence current is as follows:

[0060] Step a, obtain the phase of the high-frequency negative sequence current, including,

[0061] According to the high-frequency component i αh1 i βh1 The high-frequency negative sequence current along the αβ axis was obtained.

[0062] The αβ axis high-frequency negative sequence current A high-frequency rotating coordinate transformation from two-phase stationary to two-phase rotating phases is performed to obtain the dq-axis high-frequency negative sequence current.

[0063]

[0064] For the dq-axis high-frequency negative sequence current After low-pass filtering, its phase is extracted according to the following formula.

[0065]

[0066] in, and This represents the DC component of the high-frequency current along the dq axis.

[0067] Step b, obtain the phase of the high-frequency phase voltage, including,

[0068] Ignoring other subharmonic components, assume the high-frequency phase voltage of phase x is as follows:

[0069] u xh =U xh sin(ω h t+θ xh )

[0070] Among them, U xh θ represents the amplitude of the high-frequency phase voltage. xh The phase of the high-frequency phase voltage;

[0071] The high-frequency phase voltage can be transferred to the dq-axis coordinate system according to the following formula.

[0072]

[0073] After filtering out the higher harmonics in the above formula, we get:

[0074]

[0075] Among them, u xdh,dc and u xqh,dc This represents the DC component of the high-frequency voltage along the dq axis.

[0076] The phase of the high-frequency phase voltage is extracted as follows:

[0077] θ uxh =tan -1 (u xdh,dc / u xqh,dc )

[0078] Step c, the phase difference between the high-frequency negative sequence current and the high-frequency phase voltage is calculated by the following formula,

[0079]

[0080] Compared with the prior art, the present invention has the following significant advantages after adopting the above solution:

[0081] (1) Compared with the rotating high-frequency voltage (RHFV) injection method, the rotating high-frequency current (RHFC) injection method used in this invention injects high-frequency signals into the system through closed-loop control of the high-frequency current controller, which significantly improves the symmetry and anti-interference capability of the injected signal. At the same time, the second-order generalized integrator (SOGI) achieves accurate extraction of high-frequency response without amplitude attenuation and phase shift.

[0082] (2) This invention uses the signal delay method to calculate the negative sequence component, which effectively reduces the computational complexity of the discrete Fourier analysis (DFT) method; and combines the negative sequence components of voltage and current to construct fault features that directly map the severity of faults, thereby improving the sensitivity of fault diagnosis.

[0083] (3) The present invention introduces a three-phase minimum phase difference criterion to avoid the shortcomings of being easily affected by noise or disturbance under a single index, and improves the robustness of fault location. Attached Figure Description

[0084] Figure 1 This is a schematic diagram of the inter-turn short-circuit fault involved in this invention;

[0085] Figure 2 This is a fault diagnosis block diagram involved in the present invention;

[0086] Figure 3 This is a schematic diagram of the high-frequency negative-order component calculation process based on signal delay involved in this invention;

[0087] Figure 4 This is a schematic diagram of the phase difference calculation process involved in this invention;

[0088] Figure 5 is a schematic diagram of the experimental results of the speed change process involved in this invention:

[0089] Among them, Figure 5(a) is the rotation speed diagram of the PMSM of the present invention switching between healthy state and fault state, Figure 5(b) is the phase current diagram of the PMSM of the present invention switching between healthy state and fault state, Figure 5(c) is the fault feature diagram of the PMSM of the present invention switching between healthy state and fault state, Figure 5(d) is the fault indication FI diagram of the PMSM of the present invention switching between healthy state and fault state, and Figure 5(e) is the phase difference diagram of the PMSM of the present invention switching between healthy state and fault state.

[0090] Figure 6 is a schematic diagram of the experimental results of the variable load process involved in this invention:

[0091] Among them, Figure 6(a) is the torque diagram of the PMSM of the present invention switching between healthy state and fault state, Figure 6(b) is the phase current diagram of the PMSM of the present invention switching between healthy state and fault state, Figure 6(c) is the fault feature diagram of the PMSM of the present invention switching between healthy state and fault state, Figure 6(d) is the fault indication FI diagram of the PMSM of the present invention switching between healthy state and fault state, and Figure 6(e) is the phase difference diagram of the PMSM of the present invention switching between healthy state and fault state. Detailed Implementation

[0092] When a permanent magnet synchronous motor experiences an inter-turn short-circuit fault, the three-phase windings become unbalanced, resulting in negative-sequence components in electrical signals such as voltage and current. Utilizing this characteristic, a high-frequency voltage injection signal is calculated by combining the motor's three-phase current and a high-frequency current controller. A second-order generalized integrator is used to extract high-frequency signals from the α and β axis voltages and currents. The negative-sequence components in the voltage and current are calculated using a signal delay method, and fault characteristics related to the inter-turn short-circuit fault are constructed based on this. When the fault characteristics exceed a given threshold, a fault is determined in the motor system. Furthermore, the faulty phase is located based on the minimum phase difference between the high-frequency phase voltage and the high-frequency negative-sequence current.

[0093] This invention provides a method for diagnosing inter-turn short-circuit faults in permanent magnet synchronous motors based on high-frequency negative sequence components, comprising the following steps:

[0094] Step 1: Collect the three-phase current i of the motor a0 i b0 i c0 and electrical angle θ e The three-phase voltage u of the motor is calculated by combining the DC bus voltage and the inverter switching signal. a0 ,u b0 ,u c0 ;

[0095] Step 2, combining the three-phase current i of the motor a0 i b0 i c0 The high-frequency voltage signal is calculated by the high-frequency current controller to realize rotating high-frequency current (RHFC) injection, injecting the specified high-frequency current signal into the system;

[0096] Step 3: Use a second-order generalized integrator (SOGI) to extract the high-frequency components u in the voltage and current. αβh i αβh ;

[0097] Step four: Calculate the high-frequency negative-sequence components in the voltage and current using the signal delay method. And construct the fault feature μI fh ;

[0098] Step 5: Calculate the phase of the high-frequency negative sequence current using a phase-locked loop. The high-frequency phase voltage phase θ is calculated using a frequency tracking algorithm and a phase-locked loop. uxh Furthermore, the phase difference d between the high-frequency phase voltage and the high-frequency negative-sequence current is calculated. abc ;

[0099] Step six, when the fault characteristic μI fh When the value is less than the fault threshold, the permanent magnet synchronous motor is judged to be healthy, and the fault indicator FI = 0 is output; when the fault characteristic μI is less than the fault threshold, the permanent magnet synchronous motor is judged to be healthy. fh When the fault threshold is greater than or equal to the fault threshold, and the phase difference d x The minimum value indicates that a short circuit fault has occurred in phase x of the permanent magnet synchronous motor, and the fault indication FI = 1 is output.

[0100] In a specific embodiment of the present invention, a schematic diagram of ISCF generation in a permanent magnet synchronous motor is shown below. Figure 1 As shown. Inter-current fault circuit (ISCF) can cause an imbalance in the stator windings of a permanent magnet synchronous motor. ISCF is typically simulated using an additional short-circuit branch, where the fault resistance R... f To simulate the degree of winding insulation degradation, fault current i f It flows in the short-circuit branch. ISCF will cause an imbalance in the amplitude of phase voltage and phase current, thus generating negative sequence components in voltage and current. The inter-turn short-circuit fault involved in this invention is... Figure 1 To conduct a simulation.

[0101] In an embodiment of the present invention, the motor drive system includes a DC voltage source, an inverter circuit, a drive circuit, a current and voltage sampling circuit, a controller, and a protection circuit. The DC voltage source provides the DC bus voltage to the system, the inverter circuit converts the DC power into the three-phase AC power required to control the motor, the drive circuit drives the power devices within the inverter, the sampling circuit monitors the voltage and current signals in real time, the controller generates PWM signals based on the sampled data to control the motor operation, and the protection circuit ensures the safe operation of the system under abnormal conditions.

[0102] The specific parameters of the PMSM in this embodiment include: stator phase resistance R. s =3Ω, direct-axis inductance L d =30mH, quadrature axis inductance L q =30mH, permanent magnet fundamental flux linkage ψ f =0.82Wb, moment of inertia J = 0.1337 kg·m 2 polar number n p =4.

[0103] The specific experimental conditions are as follows: the DC bus voltage of the PMSM is 510V; the sampling frequency and switching frequency are 10kHz; the servo operating conditions include variable speed and variable load conditions: under variable speed conditions, the speed increases from 300r / min to 500r / min in increments of 100r / min, and then immediately returns to 300r / min, with the load torque remaining constant at 5.5N·m; under variable load conditions, the load torque increases from 5.5N·m to 15.3N·m in increments of 4.9N·m, and then immediately returns to the initial value, with the speed remaining constant at 300r / min.

[0104] Fault diagnosis flowchart as follows Figure 2 As shown, the specific steps included in the embodiment are as follows:

[0105] In step 1, based on the DC bus voltage u dc Three-phase space vector pulse width modulation switching signal S a ,S b ,S c The initial three-phase voltage u is obtained based on the following formula. a0 ,u b0 ,u c0 ,

[0106] u x =u dc (2S x -S x+1 -S x+2 ) / 3

[0107] Among them, u x Let x be the phase voltage of phase x, where x represents one of phases a, b, or c; x+1 represents a phase that lags phase x by 120 degrees, and x+2 represents a phase that lags phase x by 240 degrees.

[0108] In step 2, a high-frequency current controller is designed, and the high-frequency voltage injection signal is calculated based on the three-phase current of the motor, thereby realizing rotating high-frequency current injection. This includes...

[0109] The output of the high-frequency current controller is calculated using the following formula, which is to calculate the high-frequency voltage injection signal u. αh0 and u βh0 ,

[0110]

[0111] Among them, T 2r-2s (ω h t) is the high-frequency rotating coordinate transformation matrix from two-phase rotation to two-phase stationary state, ω h k is the angular frequency of the injected signal. p and k i These are the proportional and integral coefficients of the proportional-integral (PI) controller, respectively; i dhand i qh These are the dq-axis high-frequency currents after low-pass filtering, i qhref This is the reference value for the q-axis high-frequency current; L s =LM is the synchronous inductance of the permanent magnet synchronous motor, L is the self-inductance of the motor winding, and M is the mutual inductance of the motor winding.

[0112] High-frequency rotating coordinate transformation matrix T 2r-2s (ω h The expression for t) is shown in the following equation.

[0113]

[0114] Additionally, the dq-axis high-frequency current i dh and i qh The calculation formula is obtained by transforming the three-phase current through a high-frequency rotating coordinate system from a three-phase stationary state to a two-phase rotating state.

[0115] [i dh i qh ] T =T 3s-2r (ω h t)·[i a i b i c ] T

[0116] High-frequency rotating coordinate transformation matrix T 3s-2r (ω h The expression for t) is shown in the following equation.

[0117]

[0118] In step 3, a second-order generalized integrator (SOGI) is used to extract the high-frequency components in the voltage and current. The calculation formula is as follows:

[0119]

[0120] Among them, Y (z) X is the output signal of SOGI. (z) X is the input signal for SOGI. (z-2) To delay the input signal by two control cycles, Y (z-1) To delay the output signal by one control cycle, Y (z-2) The output signal is delayed by two control cycles; k is the damping coefficient of SOGI; f c f is the frequency of the high-frequency signal. s This represents the system's sampling frequency.

[0121] In step 4, the high-frequency negative-sequence components in voltage and current are calculated using the signal delay method. A schematic diagram of the calculation process for the high-frequency negative-sequence components based on signal delay is shown below. Figure 3 As shown. Taking the calculation of high-frequency negative sequence voltage components as an example, the αβ-axis high-frequency voltage at time t can be expressed as,

[0122]

[0123] Among them, u ph and θ p For the amplitude and phase of the high-frequency positive sequence voltage, u nh and θ n This represents the amplitude and phase of the high-frequency negative sequence voltage.

[0124] The αβ axis high-frequency voltage at time t is delayed by 1 / 4 of a high-frequency period T. h , can be represented as follows,

[0125]

[0126] Combining the two equations above, the αβ-axis high-frequency negative sequence voltage can be calculated as follows:

[0127]

[0128] Finally, the high-frequency negative sequence voltage can be expressed as:

[0129]

[0130] Based on the same principle, the high-frequency negative sequence current can be obtained as follows:

[0131]

[0132] Furthermore, the characteristics of inter-turn short-circuit faults in permanent magnet synchronous motors are constructed as follows:

[0133]

[0134] Among them, R s This refers to the winding resistance of a permanent magnet synchronous motor.

[0135] In step 5, the phase difference between the high-frequency phase voltage and the high-frequency negative sequence current is calculated. A schematic diagram of the phase difference calculation process is shown below. Figure 4 As shown. The process includes,

[0136] By performing a two-phase stationary to two-phase rotating high-frequency coordinate transformation on the αβ-axis high-frequency negative-sequence current from step 5, the dq-axis high-frequency negative-sequence current can be obtained, as shown below.

[0137]

[0138] After removing high-order harmonics from the high-frequency negative-sequence current along the dq axis using a low-pass filter (LPF), the phase of the high-frequency negative-sequence current is extracted using phase-locked loop (PLL) technology as follows.

[0139]

[0140] in, and This represents the DC component of the high-frequency current along the dq axis.

[0141] The phase of a single-phase high-frequency phase voltage is estimated using a frequency tracking algorithm. The process includes:

[0142] Ignoring other subharmonic components, assume the high-frequency phase voltage of phase x is as follows:

[0143] u xh =U xh sin(ω h t+θ xh )

[0144] Among them, U xh θ represents the amplitude of the high-frequency phase voltage. xh Let be the phase of the high-frequency phase voltage. Then, the high-frequency phase voltage is transformed into the dq-axis coordinate system according to the following formula:

[0145]

[0146] After filtering out the higher harmonics in the above formula, we can obtain:

[0147]

[0148] Among them, u xdh,dc and u xqh,dc This represents the DC component of the high-frequency voltage along the dq axis.

[0149] Similarly, the phase of the high-frequency phase voltage is extracted using PLL technology as follows:

[0150] θ uxh =tan -1 (u xdh,dc / u xqh,dc )

[0151] Finally, the phase difference between the high-frequency negative sequence current and the high-frequency phase voltage can be calculated using the following formula.

[0152]

[0153] In step 6, the fault threshold obtained in step 4 and the phase difference in step 5 are analyzed to determine whether an inter-turn short circuit fault has occurred in phase x of the permanent magnet synchronous motor. The process includes...

[0154] Fault feature μI fh Compare with a preset threshold: when the fault characteristic μI fh When the fault value is less than the fault threshold, the permanent magnet synchronous motor is judged to be in a healthy state, and the fault indicator FI = 0 is output; when the fault characteristic μI fh When the fault threshold is greater than or equal to the fault threshold, the permanent magnet synchronous motor is judged to be in a fault state, and the fault indication FI=1 is output.

[0155] At the same time, compare the three-phase phase difference: when d a When the minimum value is reached, it indicates that the inter-turn short-circuit fault occurred in phase a of the permanent magnet synchronous motor; when d... b When the minimum value is reached, it indicates that the inter-turn short-circuit fault occurred in phase b of the permanent magnet synchronous motor; when d... c When the value is at its minimum, it indicates that the inter-turn short-circuit fault occurred in phase c of the permanent magnet synchronous motor.

[0156] This invention utilizes a method for diagnosing inter-turn short-circuit faults in permanent magnet synchronous motors based on high-frequency negative-sequence components. Under the premise of rotating high-frequency current injection, the negative-sequence components are extracted in the high-frequency domain, enabling inter-turn short-circuit fault diagnosis under servo operating conditions. Experimental results for fault detection and location under varying speeds are shown in Figures 5(a)-(e); experimental results for fault detection and location under varying loads are shown in Figures 6(a)-(e). The experimental results demonstrate that this invention can achieve highly reliable and robust diagnosis of inter-turn short-circuit faults in permanent magnet synchronous motors under variable speed and load servo operating conditions.

[0157] This invention utilizes a high-frequency current controller to inject a high-frequency signal and extracts the high-frequency components of the αβ-axis voltage and current using a second-order generalized integrator. It employs a signal delay method to calculate the negative-sequence component, constructing fault characteristics that reflect the severity of the fault, and locates the faulty phase based on the minimum phase difference between the high-frequency phase voltage and the high-frequency negative-sequence current. This method requires no additional hardware and can achieve real-time fault detection and location during servo operation, exhibiting high applicability and robustness.

[0158] This invention is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart illustrations and / or block diagrams. Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0159] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0160] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0161] Although preferred embodiments of the invention have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including both the preferred embodiments and all changes and modifications falling within the scope of the invention.

[0162] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

Claims

1. A method for diagnosing inter-turn short-circuit faults in a permanent magnet synchronous motor based on high-frequency negative sequence components, characterized in that... Includes the following steps: Step 1, based on the three-phase current i of the motor a0 i b0 i c0 High-frequency voltage injection signal u is obtained αh0 ,u βh0 The high-frequency voltage injection signal is modulated by space vector pulse width modulation to obtain a high-frequency current signal; Step 2: Inject the high-frequency current signal into the motor to obtain the current three-phase voltage u of the motor. a1 ,u b1 ,u c1 and three-phase current i a1 i b1 i c1 And extract the high-frequency components u from them respectively. αh1 ,u βh1 i αh1 i βh1 ; Step 3, based on the extracted high-frequency component u αh1 ,u βh1 i αh1 i βh1 High-frequency negative sequence voltage is obtained. and high-frequency negative sequence current And based on the high-frequency negative sequence voltage and high-frequency negative sequence current Constructing fault features μI fh ; Step 4, transfer the fault feature μI fh The fault feature μI is compared with a fault threshold. fh If the value is less than the fault threshold, the permanent magnet synchronous motor is judged to be healthy. The fault characteristic μI fh If the value is greater than or equal to the fault threshold, the permanent magnet synchronous motor is considered to be faulty.

2. The method for diagnosing inter-turn short-circuit faults in permanent magnet synchronous motors based on high-frequency negative sequence components as described in claim 1, characterized in that: The specific process of step 1 is as follows: Step 11, convert the three-phase current i of the motor a0 i b0 i c0 The actual value of the dq-axis high-frequency current i is obtained by transforming the three-phase stationary to two-phase rotating high-frequency coordinates and then passing it through a low-pass filter. dh0 i qh0 , [i dh0 i qh0 ] T =T 3s-2r (ω h t)·[i a0 i b0 i c0 ] T Among them, T 3s-2r (ω h t) is the high-frequency rotating coordinate transformation matrix from three-phase stationary to two-phase rotating, as shown in the following equation. Where, ω h The angular frequency of the injected signal; Step 12, based on the actual value i of the dq axis high-frequency current. dh0 i qh0 Calculate the high-frequency voltage injection signal u αh0 and u βh0 , Where, k p and k i These are the proportional and integral coefficients of the proportional-integral controller, respectively; i qhref This is the reference value for the q-axis high-frequency current; L s =LM is the synchronous inductance of the permanent magnet synchronous motor, L is the self-inductance of the motor windings, and M is the mutual inductance of the motor windings; T is the high-frequency rotating coordinate transformation matrix from two-phase rotation to two-phase stationary. 2r-2s (ω h t) is shown in the following formula. Step 13, inject high-frequency voltage into signal u αh0 and u βh0 u, respectively superimposed on the vector control of the permanent magnet synchronous motor α0 and u β0 Then, the superimposed signal is input into the space vector pulse width modulation to obtain the high-frequency current signal required to inject into the motor.

3. The method for diagnosing inter-turn short-circuit faults in permanent magnet synchronous motors based on high-frequency negative sequence components as described in claim 1, characterized in that: In step 2, the current three-phase voltage u of the motor is... a1 ,u b1 ,u c1 and three-phase current i a1 i b1 i c1 Perform a rotating coordinate transformation from three-phase stationary to two-phase stationary to obtain the two-phase voltage u of the motor. α1 ,u β1 and two-phase current i α1 i β1 , [u α1 u β1 ] T =T 3s-2s ·[u a1 u b1 u c1 ] T [i α1 i β1 ] T =T 3s-2s ·[i a1 i b1 i c1 ] T Among them, the rotating coordinate transformation matrix T from three-phase stationary to two-phase stationary is... 3s-2s as follows, A second-order generalized integrator is used to extract the two-phase voltage u of the motor. α1 ,u β1 High-frequency components u αh1 ,u βh1 and two-phase current i α1 i β1 High-frequency components i αh1 i βh1 Its calculation formula is, [in αh1 in βh1 ] T =SOGI[u α1 in β1 ] T [i αh1 I βh1 ] T =SOGI[i α1 I β1 ] T Here, SOGI represents a second-order generalized integrator, whose expression is as follows: Among them, Y (z) X is the output signal of the second-order generalized integrator. (z) X is the input signal of the second-order generalized integrator. (z-2) To delay the input signal by two control cycles, Y (z-1) To delay the output signal by one control cycle, Y (z-2) The output signal is delayed by two control cycles; k is the damping coefficient of the second-order generalized integrator; f c f is the frequency of the high-frequency signal. s This is the sampling frequency of the control system.

4. The method for diagnosing inter-turn short-circuit faults in permanent magnet synchronous motors based on high-frequency negative sequence components as described in claim 1, characterized in that: In step 3, based on the extracted high-frequency component u αh1 ,u βh1 The high-frequency negative sequence voltage component was obtained. The specific process is as follows: The high-frequency component u at time t αh1 ,u βh1 Write it as the following expression: Among them, u ph and θ up These represent the amplitude and phase of the high-frequency positive-sequence voltage, u. nh and θ un These represent the amplitude and phase of the high-frequency negative sequence voltage, respectively; ω h The angular frequency of the injected signal; The αβ axis high-frequency voltage at time t is delayed by 1 / 4 of a high-frequency period T. h The high-frequency voltage at this time is obtained. The high-frequency negative sequence voltages along the αβ axis are then obtained as follows: Construct the high-frequency negative sequence voltage as follows: in, It is a high-frequency negative sequence voltage; Based on the extracted high-frequency component i αh1 i βh1 The high-frequency negative sequence current component was obtained. The specific process is as follows: The high-frequency component i at time t αh1 i βh1 Write it as the following expression: Among them, i ph and θ ip i represents the amplitude and phase of the high-frequency positive-sequence current, respectively. nh and θ in These represent the amplitude and phase of the high-frequency negative sequence current, respectively. The αβ axis high-frequency current at time t is delayed by 1 / 4 high-frequency period T. h The high-frequency current at this time is obtained. The high-frequency negative sequence currents along the αβ axis are then obtained as follows. The high-frequency negative sequence current is constructed as follows: in, It is a high-frequency negative sequence current.

5. The method for diagnosing inter-turn short-circuit faults in permanent magnet synchronous motors based on high-frequency negative sequence components as described in claim 1, characterized in that: In step 3, based on the high-frequency negative sequence voltage and high-frequency negative sequence current The fault characteristic μI is constructed according to the following formula. fh , Among them, R s L is the winding resistance of a permanent magnet synchronous motor. s For the synchronous inductance of a permanent magnet synchronous motor, ω h ω is the angular frequency of the injected signal.

6. The method for diagnosing inter-turn short-circuit faults in permanent magnet synchronous motors based on high-frequency negative sequence components as described in claim 1, characterized in that: Step 4 further includes determining the minimum phase difference d based on the phase difference between the high-frequency phase voltage and the high-frequency negative sequence current when judging a fault in the permanent magnet synchronous motor. x An inter-turn short-circuit fault occurs in the phase, x = a, b, c.

7. The method for diagnosing inter-turn short-circuit faults in permanent magnet synchronous motors based on high-frequency negative sequence components as described in claim 6, characterized in that: The specific process for calculating the phase difference between the high-frequency phase voltage and the high-frequency negative-sequence current is as follows: Step a, obtain the phase of the high-frequency negative sequence current, including, According to the high-frequency component i αh1 i βh1 The high-frequency negative sequence current along the αβ axis was obtained. The αβ axis high-frequency negative sequence current A high-frequency rotating coordinate transformation from two-phase stationary to two-phase rotating phases is performed to obtain the dq-axis high-frequency negative sequence current. For the dq-axis high-frequency negative sequence current After low-pass filtering, its phase is extracted according to the following formula. in, and This represents the DC component of the high-frequency current along the dq axis. Step b, obtain the phase of the high-frequency phase voltage, including, Ignoring other subharmonic components, assume the high-frequency phase voltage of phase x is as follows: you xh =U xh sin(ω h t+θ xh ) Among them, U xh θ represents the amplitude of the high-frequency phase voltage. xh The phase of the high-frequency phase voltage; The high-frequency phase voltage can be transferred to the dq-axis coordinate system according to the following formula. After filtering out the higher harmonics in the above formula, we get: Among them, u xdh,dc and u xqh,dc This represents the DC component of the high-frequency voltage along the dq axis. The phase of the high-frequency phase voltage is extracted as follows: θ uxh =tan -1 (the xdh,dc / the xqh,dc ) Step c, the phase difference between the high-frequency negative sequence current and the high-frequency phase voltage is calculated by the following formula,

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