A method for open-circuit fault rotor position estimation of permanent magnet synchronous motor

Abstract

The application belongs to the field of fault-tolerant control of polyphase electric machines, and relates to a permanent magnet synchronous motor open-circuit fault rotor position estimation method, which comprises the following steps: step (1), according to different open-circuit fault types, the motor mathematical model in the natural coordinate system is modified to obtain a fault motor mathematical model; step (2), according to different open-circuit fault types, a corresponding coordinate transformation matrix is established; step (3), the coordinate transformation matrix obtained in the above step (2) is used to decouple the fault motor mathematical model to obtain a fundamental mathematical model under different open-circuit fault types; and step (4), the fundamental mathematical model is used to construct a sliding mode observer to estimate rotor position information. The application realizes accurate estimation of rotor position information under motor open-circuit fault by constructing a modified sliding mode observer based on a novel fundamental mathematical model.

Description

Technical fields:

[0001] This invention belongs to the field of motor drive technology and relates to a method for estimating rotor position information under open circuit faults in multiphase motors, which is used for fault-tolerant operation control of multiphase motors. Background technology:

[0002] Permanent magnet synchronous motors use permanent magnet excitation instead of electrical excitation, offering advantages such as small size, high torque density, and high reliability. Compared to three-phase motor drive systems, multiphase motors have the following advantages: suitable for large-capacity drives, suitable for high-density applications, suitable for high-reliability drives, and offer more flexible and diverse control methods. Therefore, research on multiphase motor drive control is of great significance.

[0003] Sensorless control aims to replace mechanical sensors by using detected stator voltage, stator current, and other relevant variables of the motor to estimate rotor position and speed through control algorithms. Among various control algorithms, closed-loop control algorithms that establish various observers based on the mathematical model of the motor are widely used.

[0004] Multiphase motors have strong fault tolerance. When one or more phases of the stator windings fail, they can maintain operating efficiency comparable to that under normal conditions, allowing the motor to continue operating stably, depending on the control strategy employed. Furthermore, the rotor position angle θ and speed ω required for fault-tolerant control methods can be estimated using positionless control algorithms.

[0005] Therefore, how to accurately estimate the rotor position information of the motor under fault and fault-tolerant operating conditions to meet the requirements of fault-tolerant control strategies is an urgent problem to be solved. Summary of the Invention:

[0006] The purpose of this invention is to achieve sensorless control of multiphase motors under fault-tolerant operating conditions. It relates to the construction of a modified sliding mode observer, which derives the fundamental mathematical model of the faulty motor in a stationary orthogonal coordinate system using a novel coordinate transformation. This provides a new approach for accurately estimating rotor position information using observer control algorithms.

[0007] To achieve the aforementioned objectives, this invention analyzes sensorless control under fault conditions, including open-circuit faults in one or both phases of the stator winding and fault-tolerant operation. First, the mathematical model of the motor in the natural coordinate system is appropriately modified for different open-circuit fault types. The Clarke transformation matrix is ​​also appropriately modified for different open-circuit fault types, causing the α-axis position in the orthogonal stationary coordinate system to shift according to different fault types. The modified Clarke matrix is ​​used to decouple the faulty motor mathematical model, resulting in a novel fundamental mathematical model in the stationary coordinate system. The parameter characteristics of the fundamental mathematical model under different fault types are observed, and patterns are summarized. Finally, a modified sliding mode observer is reconstructed based on the novel fundamental mathematical model to estimate rotor position information.

[0008] The specific process steps of the rotor position estimation method for open-circuit fault in a permanent magnet synchronous motor according to the present invention are as follows:

[0009] Step (1): According to different open circuit fault types, the mathematical model of the motor in the natural coordinate system is modified to obtain the mathematical model of the faulty motor;

[0010] Step (2): Establish the corresponding coordinate transformation matrix according to different open circuit fault types;

[0011] Step (3): Use the Clarke transformation matrix obtained in step (2) above to decouple the mathematical model of the faulty motor and obtain the fundamental mathematical model under different open circuit fault types;

[0012] Step (4): Construct a sliding mode observer using the fundamental wave mathematical model to estimate the rotor position information.

[0013] Optionally, in step (1), the fault-related variables in the voltage, current, and flux linkage matrices are changed to 0, and the stator winding mutual inductance matrix and permanent magnet flux linkage equation are corrected.

[0014] Optionally, in step (3), the modified mathematical model is decoupled using a new coordinate transformation matrix to summarize the characteristics of motor parameter changes corresponding to different open circuit fault types.

[0015] Compared with the prior art, the present invention has the following advantages: First, the derived novel fundamental mathematical model intuitively reflects the changes in parameters under open circuit faults of the motor; Second, the modified sliding mode observer can effectively eliminate the DC bias error of the back electromotive force under open circuit faults; Third, for any open circuit fault, there is a corresponding modified sliding mode observer to accurately estimate the rotor position information, which has comprehensive and wide applicability. Attached image description:

[0016] Figure 1 This is a schematic diagram of the semi-symmetrical stator winding distribution involved in the present invention.

[0017] Figure 2 This is a schematic diagram of the Clarke transform when phase a1 is open.

[0018] Figure 3 This is a schematic diagram of the Clarke transform when phase b1 is open.

[0019] Figure 4 This is a schematic diagram of the Clarke transform when phases a1 and a2 are open.

[0020] Figure 5 This is a schematic diagram of the Clarke transform when phases a1 and b1 are open.

[0021] Figure 6 A schematic diagram of the Clarke transform for an open-circuit fault in any phase.

[0022] Figure 7 A schematic diagram for correcting the rotor position information estimated by the sliding mode observer. Detailed implementation method:

[0023] The present invention will be further described below with reference to the embodiments and accompanying drawings.

[0024] This embodiment uses an open-circuit fault in one phase (a1) and two phases (a1b1) of a nine-phase permanent magnet synchronous motor as an example. The specific process is as follows:

[0025] (1) Constructing the mathematical model of the motor in the natural coordinate system when an open-circuit fault occurs in any phase of the motor: First, write the mathematical model for normal operation.

[0026] Voltage equation:

[0027] Magnetic flux linkage equation: ψ s =L s i s +ψ f F s (θ)

[0028] Inductor matrix: L s =L m L+L l E

[0029] coefficient matrix F s (θ) is defined as:

[0030]

[0031] u s R is the stator phase voltage matrix. s Let i be the stator resistance diagonal matrix. s Let ψ be the stator phase current matrix. s Let L be the stator flux linkage matrix. sFor the stator inductance matrix, ψ f L is the flux linkage amplitude of the rotor permanent magnet, and L is the mutual inductance matrix. m For stator mutual inductance, L l This is due to stator leakage.

[0032] For different fault types, the mathematical model of the motor is modified accordingly, for example:

[0033] (1A) The corrected mathematical model for a1 phase open-circuit fault is:

[0034] u s =[0 u a2 u a3 u b1 u b2 u b3 u c1 u c2 u c3 ] T

[0035] i s =[0 i a2 i a3 i b1 i b2 i b3 i c1 i c2 i c3 ] T

[0036] ψ s =[0 ψ a2 ψ a3 ψ b1 ψ b2 ψ b3 ψ c1 ψ c2 ψ c3 ] T

[0037]

[0038] (1B) The corrected mathematical model for a1b1 two-phase open-circuit fault is:

[0039] u s =[0 0 u a3 u b1 u b2 u b3 u c1 u c2 u c3 ] T

[0040] is =[0 0 i a3 i b1 i b2 i b3 i c1 i c2 i c3 ] T

[0041] ψ s =[0 0 ψ a3 ψ b1 ψ b2 ψ b3 ψ c1 ψ c2 ψ c3 ] T

[0042]

[0043] (2) Novel Decoupling Coordinate Transformation: For different open-circuit faults in the motor, there exists a corresponding Clarke decoupling transformation matrix, which can transform the modified motor mathematical model to the αβ coordinate system. The fundamental Clarke transformation matrix is:

[0044]

[0045] Where γ is a variable corresponding to different fault types, i.e., the angle of offset in the αβ coordinate system, such as... Figure 6 As shown. For example, when phase a1 is open, γ = 0, as... Figure 2 As shown; when phases a1 and a2 are open-circuited, γ = π / 18, as... Figure 4 As shown.

[0046] (3) Novel Fundamental Wave Mathematical Model: A novel fundamental wave mathematical model is obtained by decoupling the modified mathematical model using a novel Clarke transformation matrix. Specifically, it can be divided into:

[0047] (3A) When a1 phase is open-circuit fault, the transformed new fundamental frequency mathematical model is:

[0048]

[0049] Compared with the fundamental mathematical model of the motor during normal operation, the motor parameters have changed:

[0050]

[0051] (3B) When an open-circuit fault occurs in phase b1, take γ = 6π / 9, and perform the Clarke transformation as follows: Figure 3 As shown, the transformed fundamental wave mathematical model is:

[0052]

[0053] (3C) When a two-phase open-circuit fault occurs (a1a2), take γ = π / 18, and the Clarke transform is as follows: Figure 4 As shown, the transformed fundamental wave mathematical model is:

[0054]

[0055] (3D) When a two-phase open-circuit fault occurs in phases a1b1, take γ = π / 3, and the Clarke transform is as follows: Figure 5 As shown, the transformed fundamental wave mathematical model is:

[0056]

[0057] (4) Construction of the modified sliding mode observer: Based on the new fundamental mathematical model, a modified sliding mode observer for estimating rotor position information under open-circuit fault conditions is constructed. When any phase is open-circuited, the fundamental mathematical model remains consistent and is as shown in process (3A). The constant-velocity reaching law is chosen as the control function u = K * sgn(s), where K is the sliding mode gain. The designed current observer is as follows:

[0058]

[0059] in These are current observations.

[0060] The state equation for current error is:

[0061]

[0062] When any two phases are open, the fundamental wave mathematical model can be written as:

[0063]

[0064] Where k α k β These are coefficients related to the two-phase open-circuit fault type. Analogous to the construction of a sliding mode observer when one phase is open, the state equation for the current error when two phases are open is:

[0065]

[0066] After estimating the back electromotive force using a modified sliding mode observer, the two orthogonal back electromotive forces are processed using a phase-locked loop to extract rotor position information. Note that the estimated θ should compensate for the γ angle.

[0067] (5) The values ​​of γ and the corresponding new fundamental wave mathematical models under single-phase open-circuit and two-phase open-circuit faults are summarized as follows:

[0068] (5A) When a single-phase open circuit fault occurs, the value of γ is as shown in Table 1.

[0069] Table 1

[0070] <![CDATA[a1 open circuit]]> <![CDATA[a2 open circuit]]> <![CDATA[a3 open circuit]]> <![CDATA[b1 open circuit]]> <![CDATA[b2 open circuit]]> <![CDATA[b3 open circuit]]> <![CDATA[c1 open circuit]]> <![CDATA[c2 open circuit]]> <![CDATA[c3 open circuit]]> γ=0 c = pi / 9 γ=2π / 9 γ=6π / 9 γ=7π / 9 γ=8π / 9 γ=12π / 9 γ=13π / 9 γ=14π / 9

[0071] The resulting mathematical model for the fundamental wave is as follows:

[0072]

[0073] (5B) When any two phases experience an open-circuit fault, the position of the α-axis in the αβ coordinate system, i.e., the value of γ, follows this criterion: fix the α-axis on the angle bisector of the two phase axes where the open-circuit fault occurs. γ has the following relationship with the fault type: the spatial distribution of each phase stator winding is as follows... Figure 1 As shown, i.e., θ a1 =0, θ a2 =π / 9, θ a3 =2π / 9, θ b1 =6π / 9, θ b2 =7π / 9, θ b3 =8π / 9, θ c1 =12π / 9, θ c2 =13π / 9, θ c3 =14π / 9, γ=(θ) 故障相1 +θ 故障相2 The new fundamental wave mathematical model obtained by dividing by 2 is:

[0074]

[0075] in, It is the back electromotive force.

[0076] The process of estimating rotor position information using a novel fundamental wave mathematical model is as follows: Figure 7 As shown.

[0077] The open-circuit fault types of any two phases and the spatial angle difference Δθ between the two open-circuit phases can be summarized as shown in Table 2.

[0078] Table 2

[0079]

[0080] And k α k β The relationship between Δθ and Δθ is shown in Table 3.

[0081] Table 3

[0082] Dth <![CDATA[k α ]]> <![CDATA[k β ]]> π / 9 2.5603 4.4397 2π / 9 2.734 4.266 4π / 9 3.3264 3.6736 5π / 9 3.6736 3.3264 6π / 9 4 3 7π / 9 4.266 2.734 8π / 9 4.4397 2.5603

[0083] This invention constructs a modified sliding mode observer, which can accurately estimate the rotor position information of a motor under fault-tolerant conditions, including single-phase and two-phase open-circuit faults. Compared with existing technologies, the modified sliding mode observer is simpler in form and can better meet the requirements of various fault-tolerant control methods.

Claims

1. A method for estimating the rotor position in an open-circuit fault of a permanent magnet synchronous motor, characterized in that, The method includes the following steps: Step (1): According to different open circuit fault types, the mathematical model of the motor in the natural coordinate system is modified to obtain the mathematical model of the faulty motor; Step (2): Establish the corresponding coordinate transformation matrix according to different open circuit fault types; Step (3): Use the coordinate transformation matrix obtained in step (2) above to decouple the mathematical model of the faulty motor and obtain the fundamental wave mathematical model under different open circuit fault types; Step (4): Construct a sliding mode observer using a fundamental mathematical model to estimate rotor position information, wherein, When any phase is open, the fundamental mathematical model remains consistent. Choosing the constant-rate reaching law as the control function u = K * sgn(s), where K is the sliding mode gain, the designed current observer is: in For current i α1 i β1 Observations, R s Let ψ be the stator resistance diagonal matrix. f L is the flux linkage amplitude of the rotor permanent magnet. m For stator mutual inductance, L l For stator leakage inductance, u α1 Let u be the α-axis voltage in the fundamental plane. β1 Let i be the β-axis voltage in the fundamental plane. α1 Let i be the α-axis current in the fundamental plane. β1 The current is the β-axis current in the fundamental plane; The state equation for current error is: in ω is the current observation error value, θ is the electric angular velocity, and θ is the rotor electric angle. When any two phases are open, the fundamental wave mathematical model can be written as: Where k α k β It is a coefficient related to the two-phase open-circuit fault type. The state equation for the current error during two-phase open-circuit faults is: After estimating the back electromotive force using a modified sliding mode observer, a phase-locked loop is used to process the two orthogonal back electromotive forces to extract rotor position information.

2. The method for estimating the rotor position in an open-circuit fault of a permanent magnet synchronous motor according to claim 1, characterized in that, The mathematical model of the faulty motor is the permanent magnet flux linkage equation.

3. The method for estimating the rotor position in an open-circuit fault of a permanent magnet synchronous motor according to claim 2, characterized in that, In step (2), the coordinate transformation matrix corresponds one-to-one with the open circuit fault type.

4. The method for estimating the rotor position in an open-circuit fault of a permanent magnet synchronous motor according to claim 3, characterized in that, In the decoupling step, the permanent magnet synchronous motor operates in an open-circuit, phase-disconnected state.

5. A method for estimating the rotor position in an open-circuit fault of a permanent magnet synchronous motor according to any one of claims 1 to 4, characterized in that, In step (3), the fundamental mathematical model of the single-phase open-circuit fault type is consistent.

6. A method for estimating the rotor position in an open-circuit fault of a permanent magnet synchronous motor according to any one of claims 1 to 4, characterized in that, The permanent magnet synchronous motor has nine phases.

7. A method for estimating the rotor position in an open-circuit fault of a permanent magnet synchronous motor according to any one of claims 1 to 4, characterized in that, The permanent magnet synchronous motor has multiple phases.

8. The method for estimating the rotor position in an open-circuit fault of a permanent magnet synchronous motor according to claim 1, characterized in that, In the step of correcting the mathematical model of the motor in the natural coordinate system according to different open circuit fault types, the fault-related variables in the voltage, current, and flux linkage matrices are changed to 0, and the stator winding mutual inductance matrix and permanent magnet flux linkage equation are corrected.

9. The method for estimating the rotor position in an open-circuit fault of a permanent magnet synchronous motor according to claim 1, characterized in that, In the step of establishing the corresponding coordinate transformation matrix according to different open circuit fault types, the position of the α axis in the orthogonal stationary coordinate system shifts and changes according to different open circuit fault types.

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