Rotor position estimation method for two-phase and three-phase motors based on fault phase diode current

Abstract

This invention proposes a rotor position estimation method for a dual three-phase motor based on fault phase diode current. First, the fault phase current in the dual three-phase motor is collected. Then, using the collected fault phase current, an estimated fault back EMF and estimated fault phase current are obtained according to a designed Luneburger observer. The obtained fault back EMF estimate is then decomposed to obtain intermediate variables. Finally, the estimated electrical angle of the motor is obtained using the relationship between the intermediate variables and the rotor position estimation error. This invention is based on the idea of ​​extracting the rotor position of a dual three-phase motor from the fault phase diode current of the inverter. It decouples fault-tolerant control and position estimation in traditional schemes, eliminating the need to adjust the PWM mode and achieving independent estimation of the motor rotor position, thus improving the stability of the motor drive system after a fault. Furthermore, the Luneburger observer of this invention fully considers the influence of mutual inductance between the two sets of windings on the diode current, thereby enabling its application to dual three-phase permanent magnet synchronous motors.

Description

Technical Field

[0001] This invention relates to the field of rotor position estimation technology for permanent magnet synchronous motors, and in particular to a method for rotor position estimation of a dual three-phase permanent magnet synchronous motor using fault phase diode current. Background Technology

[0002] Dual three-phase permanent magnet synchronous motors have been widely used in high-voltage DC permanent magnet starting and generating systems for conventional aircraft due to their significant advantages such as high power output, low torque ripple, high reliability, and strong fault tolerance. They have also received widespread attention and application as main drive motors in electric propulsion aircraft. There are various ways to arrange the stator windings of dual three-phase permanent magnet synchronous motors, among which the motor with neutral point isolation and a 30-degree phase winding difference is widely favored due to its good harmonic characteristics and low torque ripple.

[0003] Dual three-phase permanent magnet synchronous motor drive systems are typically equipped with position sensors to achieve precise closed-loop control of speed or position. However, due to strong electromagnetic interference between onboard equipment and high-frequency vibration environments, position sensors, transmission cables, and their decoding chips are prone to failure. Therefore, positionless control is an effective way to enhance the reliability of motor closed-loop control. Statistics show that during the operation of a motor drive system, inverter failures due to external or internal influences account for as much as 82.5% of all drive system failures, with open-circuit faults in switching devices being the most typical. When short-circuit overcurrent or high temperature conditions in switching devices trigger the blocking of the faulty bridge arm drive signal, the inverter also exhibits an open-circuit fault. If positionless control can still be achieved under inverter open-circuit faults, the safety of the drive system can be further improved; however, achieving accurate position estimation under fault conditions presents a significant challenge.

[0004] When a dual three-phase permanent magnet synchronous motor experiences an inverter open-circuit fault while operating at rated speed, the traditional approach is to disconnect all three-phase windings containing the faulty phase, allowing the motor to continue operating as a normal three-phase motor. This simple fault-tolerant method reduces the motor's output capacity. Therefore, current research on fault-tolerant control for multiphase motors focuses on fully utilizing information such as rotor position and phase current feedback to ensure the smooth output of the system's original torque by redistributing the current of the remaining healthy phases. Positionless control of dual three-phase permanent magnet synchronous motors often borrows methods from traditional three-phase permanent magnet motors. During rated speed operation, an observer based on a motor model is typically used, with its input being the voltage and current of each phase. However, in the case of a phase loss caused by a single-phase open-circuit fault in the inverter, the unbalanced mutual inductance coupling between the healthy three-phase and the remaining faulty phase windings causes voltage and current distortion. Using fault-tolerant control further alters the voltage and current phases, leading to a mutual deterioration of the performance of fault-tolerant control and traditional position observation. Optimizing the position observer requires redesigning the current and voltage sampling algorithms and adjusting the PWM mode, resulting in high costs and algorithmic complexity. Summary of the Invention

[0005] The technical problem to be solved:

[0006] After an inverter open-circuit fault occurs, the diodes connected in reverse parallel to the switching devices generally do not fail and still possess current-carrying capacity. Although this current contains back EMF characteristics, it is often overlooked. If this current can be fully utilized for rotor position estimation, then position estimation and fault-tolerant control can be decoupled and designed independently, improving the safety of the drive system after a fault. Based on this idea, the applicant further discovered that when using the post-fault current for rotor position estimation in a dual three-phase motor, the mutual inductance between the two windings of the dual three-phase motor affects the accuracy of rotor position estimation. Therefore, it is necessary to analyze the influence of the mutual inductance between the two windings of the dual three-phase motor and redesign it to eliminate the influence of mutual inductance on rotor position estimation.

[0007] The technical solution of this invention is as follows:

[0008] A method for rotor position estimation of a dual three-phase motor based on fault phase diode current includes the following steps:

[0009] Step 1: Collect the fault phase current in the dual three-phase motor ;

[0010] Step 2: Utilize the fault phase current acquired in Step 1 According to the Lundberg observer

[0011]

[0012] The estimated fault back potential is obtained. ;in For the stator resistance of a dual three-phase motor, For the main self-inductance of each phase in a dual three-phase motor This refers to the first-phase current in a set of windings of a two-phase three-phase motor that does not contain the faulty phase. The first phase is 30° out of phase with the faulty phase. This refers to the second phase current in a set of windings of a dual three-phase motor that does not contain the faulty phase. The second phase is 150° out of phase with the faulty phase. The proportional gain of the observer; The estimated fault phase current;

[0013] Step 3: Estimate the back electromotive force of the fault obtained in Step 2. Decompose to obtain intermediate variables and ;

[0014] Step 4: Based on rotor position estimation error and intermediate variables and The relationship is used to obtain the estimated electrical angle of the motor.

[0015] Furthermore, in step 3, according to the formula

[0016]

[0017]

[0018] The fault back potential estimate obtained in step 2 Decompose to obtain intermediate variables and ,in and Same frequency and phase, and Orthogonal, with a 90-degree phase shift; for The expression after Laplace transform; These are the closed-loop coefficients. The resonant frequency, It is a complex frequency.

[0019] Furthermore, in step 4, according to the formula

[0020]

[0021] The estimated electrical angle of the motor was calculated. ;in for The rotor position estimation error at time t. To be After conversion to the time domain The value at time, To be After conversion to the time domain The value at time, In order, they are respectively Time and Estimated electrical angle at time, In order, they are respectively Time and The intermediate summation term at time, and These are, in order, the proportional coefficient and the integral coefficient; for The estimated electric angular velocity at any given time. For time step.

[0022] Furthermore, if a DSP is used as the control chip in the dual three-phase motor, then in step 1, current sampling is performed when the counter returns to zero and when the counter equals the period value, respectively, to obtain the fault phase current in the dual three-phase motor. .

[0023] Furthermore, in step 1, the fault phase current is collected. During a switching cycle, the currents of the inverters “x11” and “x00” with faulty phases are sampled, and the current with the amplitude is taken as the faulty phase current.

[0024] Furthermore, the present invention also proposes an electronic device and a readable storage medium:

[0025] An electronic device includes a processor and a memory, the memory being used to store one or more programs;

[0026] The above method is implemented when the one or more programs are executed by the processor.

[0027] A readable storage medium storing a computer program that, when executed by a processor, implements the above-described method.

[0028] Beneficial effects:

[0029] This invention is based on the idea of ​​extracting the rotor position of a dual three-phase motor from the diode current of the faulty phase of the inverter. It decouples the fault-tolerant control and position estimation in the traditional scheme, and realizes independent estimation of the motor rotor position without adjusting the PWM mode, thereby improving the stability of the motor drive system after a fault. Moreover, this invention proposes a back EMF Luenberger observer based on the pulse current of the faulty phase diode. This observer fully considers the influence of the mutual inductance between the two sets of windings on the diode current, so it can be used for dual three-phase permanent magnet synchronous motors.

[0030] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0031] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which:

[0032] Figure 1 This is a schematic diagram of the diode current path after an open-circuit fault in phase A of the inverter in this application;

[0033] Figure 2 This is a block diagram of the positionless control after a single-phase open-circuit fault in the dual three-phase permanent magnet synchronous motor inverter of this application.

[0034] Figure 3 For this application Diagram of the conduction loop of the faulty phase diode current;

[0035] Figure 4 For this application Diagram of the conduction loop of the faulty phase diode current;

[0036] Figure 5 This is a schematic diagram of the Luneburger observer in this application;

[0037] Figure 6 This is a schematic diagram of the SOGI+PLL rotor position estimation in this application;

[0038] Figure 7 This is a simplified PLL structure diagram according to this application;

[0039] Figure 8 The waveforms of each phase current after an open-circuit fault in the inverter are shown in the embodiments of this application.

[0040] Figure 9 The fault phase current and sampling are shown in the embodiments of this application;

[0041] Figure 10 The back potential observation results are shown in the embodiments of this application;

[0042] Figure 11 The simulation results for the SOGI+PLL rotor position estimation in the embodiments of this application are shown. Detailed Implementation

[0043] The embodiments of the present invention are described in detail below. These embodiments are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0044] This embodiment proposes a rotor position estimation method for a dual three-phase permanent magnet synchronous motor with neutral point isolation and two sets of windings spaced 30° apart. The method analyzes the back electromotive force and its excited diode current after a single-phase fault in the inverter. Considering the influence of mutual inductance of the dual three-phase motor on the diode current, a fault phase current sampling method is designed to extract the diode current under special switching conditions. This diode current is used to estimate the back electromotive force, and finally, the rotor position is estimated using the back electromotive force.

[0045] This embodiment takes an open-phase fault in phase A of the inverter as an example to analyze the characteristics of the current loop. The specific process is as follows:

[0046] The diode current loop after an open-phase fault in phase A of the inverter is as follows: Figure 1 As shown. Phases ABC constitute the first set of windings, and UVW constitute the second set of windings. When a fault occurs in phase A, analyzing the current loop of phase A reveals that, in addition to the mutual inductance effect of phases BC on phase A, the three phases of the second set of windings UVW will also have a mutual inductance effect on phase A. The inductance matrix of this dual three-phase permanent magnet synchronous motor is as follows:

[0047] (1)

[0048] in For the self-sensitivity of phase X, , The mutual inductance between phase X and phase Y. , The main self-inductance characterizes the coupling capability between the winding and the main magnetic flux, and is related to the magnetic circuit structure and air gap permeability.

[0049] Different faults with opposite potentials The excited diode currents are also different, such as Figure 3 and Figure 4 They are respectively and In a current-carrying loop, the outflowing current is negative and the inflowing current is positive. Kirchhoff's laws are used to analyze the current loops under both conduction conditions, and the current equations are established as follows:

[0050] (2)

[0051] in These are, in order, the stator resistance and the A-phase inductance matrix; Let be the current vector after a phase A open-phase fault occurs on each phase, where These are, in order, the currents flowing through phases A, B, and C of the first winding. These are the currents on phases UVW of the second winding, respectively. The sign for differentiation is given; point P is the positive terminal of the power supply, O is the negative terminal of the power supply, and N1 and N2 are the neutral points of the first and second windings, respectively. The voltage between point P and N1, This is the voltage between point O and N1.

[0052] The inverter's switching state is represented by the symbol "xxx", where x has two states: 1 and 0. 1 indicates the upper switch is on and the lower switch is off, while 0 indicates the lower switch is on and the upper switch is off. When the three-phase (ABC) switches are in states "x11" and "x00", and Setting the value to 0 and simplifying the current equation (2), the following unified current equation is established:

[0053] (3)

[0054] Due to neutral point isolation, the currents in the two windings satisfy the following relationship.

[0055] (4)

[0056] Combining the relationship between the inductance matrix (1) and winding current of the dual three-phase permanent magnet synchronous motor (4), the current equation (3) is further expressed as follows:

[0057] (5)

[0058] Thus, the current of phase A after the fault is obtained. Opposite potential of A The relationship between the back EMF of phase A and the diode current it induces is clarified. Once the relationship between the back EMF of phase A and the diode current it induces is understood, the back EMF of phase A can be estimated based on the collected phase A current. Since the back EMF contains rotor position information, the rotor position can be estimated using the estimated back EMF.

[0059] To achieve rotor position estimation using the estimated back EMF, this invention proposes a Luneburger observer suitable for dual three-phase permanent magnet synchronous motors. This observer fully considers the influence of the mutual inductance between the two windings on the diode current. The Luneburger observer is designed according to equation (5) as follows, and the structural diagram of the Luneburger observer is shown below. Figure 5 As shown:

[0060] (6)

[0061] in The proportional gain of the observer, The current in phase A and the estimated current in phase A are shown in the following figures, respectively. The estimated opposite potential of A is given.

[0062] Based on the above analysis, it can be seen that the rationality of fault phase current sampling directly affects the estimation of back EMF. Through previous analysis, when the back EMF... When the diode current flows out, it can be obtained by sampling only when the ABC three-phase switch is in the "x11" state. Conversely... At that time, sampling at "x00" can obtain the diode current. However, the back EMF is not required during actual motor operation. The amplitude information is obtained by sampling the current in both the "x11" and "x00" switching states of the first inverter within a switching cycle, and then using the larger amplitude as the true value of the diode current. In systems where the DSP is used as the control chip, PWM interrupts (10kHz) are typically used to trigger current sampling, so the frequency of current sampling is usually the same as the frequency of the PWM interrupt (10kHz). The interrupt trigger can usually be set to reset the counter to zero (CTR_ZERO), equal to the period value (CTR_PRD), or equal to the CMPA / B value (CTR_CMPA / B). Triggering the interrupt when the counter is reset to zero is the most common method, which means that current sampling is interrupted at the midpoint of the "x00" switching state, but at this time, only the current sampled at this time can be collected. To sample the complete current, sampling is required when the counter equals the period value. The final diode sampling current is shown below:

[0063] (7)

[0064] in, This indicates the sampling current of diode A; These represent the current values ​​sampled at the midpoint between the switch states "x00" and "x11", respectively.

[0065] Back potential observed by the Lundberg Observatory Rotor position estimation is performed using a second-order generalized integrator (SOGI) and a phase-locked loop (PLL). The block diagram is as follows: Figure 6 As shown.

[0066] The transfer function of the second-order generalized integrator (SOGI) is as follows:

[0067] (8)

[0068] in The resonant frequency representing SOGI, in this example, is related to the estimated electrical angular velocity of the motor. same, These are the closed-loop coefficients, which primarily affect the bandwidth of the closed-loop system. and All are intermediate variables. It is a complex frequency.

[0069] The estimated back potential And the estimated electric angular velocity of the motor As input to SOGI, intermediate variables can be output. and ,in and Same frequency and phase, and They are orthogonal and have a 90-degree phase shift.

[0070] Because in theory and It has the following expression:

[0071] (9)

[0072] in The magnetic flux linkage of the permanent magnet in the motor. The electrical angle of the motor, Let be the electric angular velocity of the motor. Therefore, establish as follows: Figure 7 The phase-locked loop (PLL) shown utilizes intermediate variables. and Rotor position estimation is performed using a PLL, where the estimation error is:

[0073] (10)

[0074] in For error, This is the estimated electrical angle of the motor. This method estimates the electrical angle of the motor, which is the rotor position.

[0075] Based on the above analysis, the rotor position estimation method for a dual three-phase motor based on fault phase diode current proposed in this embodiment specifically includes the following steps:

[0076] Step 1: Collect the fault phase current in the dual three-phase motor ;

[0077] Step 2: Utilize the fault phase current acquired in Step 1 According to the Lundberg observer

[0078]

[0079] The estimated fault back potential is obtained. ;in For the stator resistance of a dual three-phase motor, For the main self-inductance of each phase in a dual three-phase motor This refers to the first-phase current in a set of windings of a two-phase three-phase motor that does not contain the faulty phase. The first phase is 30° out of phase with the faulty phase. This refers to the second phase current in a set of windings of a dual three-phase motor that does not contain the faulty phase. The second phase is 150° out of phase with the faulty phase. The proportional gain of the observer; The estimated fault phase current;

[0080] Step 3: According to the formula

[0081]

[0082]

[0083] The fault back potential estimate obtained in step 2 Decompose to obtain intermediate variables and ,in and Same frequency and phase, and Orthogonal, with a 90-degree phase shift; for The expression after Laplace transform; These are the closed-loop coefficients. The resonant frequency, It is a complex frequency;

[0084] Step 4: According to the formula

[0085]

[0086] The estimated electrical angle of the motor was calculated. ;in for The rotor position estimation error at time t. To be After conversion to the time domain The value at time, To be After conversion to the time domain The value at time, In order, they are respectively Time and Estimated electrical angle at time, In order, they are respectively Time and The intermediate summation term at time, and These are, in order, the proportional coefficient and the integral coefficient; for The estimated electric angular velocity at any given time. For time step.

[0087] The following is a specific implementation example to illustrate the effectiveness of the method proposed in this invention:

[0088] For a dual three-phase permanent magnet synchronous motor with an open-phase fault in one phase of the inverter, let's assume the open-phase fault is phase A. The parameters of the dual three-phase permanent magnet synchronous motor used are shown in Table 1. In the simulation, the open-phase fault in phase A is simulated by controlling the PWM duty cycle of the two bridge arms of phase A to 0. The current waveform after the motor experiences the fault is shown in Table 1. Figure 8 As shown, the current that appears after the fault is generated by back EMF excitation. The current after excitation will only appear in a specific switching state and will exhibit a sinusoidal waveform.

[0089] Table 1. Parameter List of Dual Three-Phase Permanent Magnet Synchronous Motors

[0090]

[0091] The sampling is triggered based on the PWM state of phase B or the upper phase C. If either the PWM state of phase B or the upper phase C is 0, sampling is triggered during switch state "x00"; if both the PWM states of phase B and the upper phase C are 1, sampling is triggered during switch state "x11". The diode current of phase A is sampled twice within one PWM cycle. The sampled current is the average of the fault phase currents, and the larger of the two amplitudes is taken as the current value. Simulation results are as follows... Figure 9As shown, the current amplitude after acquisition is the average value of the phase current amplitude, and the acquired waveform is a sine wave.

[0092] Based on the collected A-phase diode current, the back potential of A-phase was observed using a Luneburger detector. The observation results are as follows: Figure 10 As shown, due to the addition of a filtering algorithm in the simulation, the observed back EMF and the actual back EMF amplitude are different, but they have the same phase, so it does not affect the rotor position estimation.

[0093] Based on the observed back electromotive force A, the rotor position is estimated using SOGI and PLL. The simulation results are as follows: Figure 11 As shown, the rotor position can be accurately estimated using SOGI and PLL.

[0094] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention without departing from the principles and spirit of the present invention.

Claims

1. A method for rotor position estimation of a dual three-phase motor based on fault phase diode current, characterized in that: Includes the following steps: Step 1: Collect the fault phase current in the dual three-phase motor ; The fault is a single-phase open-phase fault in the inverter. Step 2: Utilize the fault phase current acquired in Step 1 According to the Lundberg observer The estimated fault back potential is obtained. ;in For the stator resistance of a dual three-phase motor, For the main self-inductance of each phase in a dual three-phase motor This refers to the first-phase current in a set of windings of a two-phase three-phase motor that does not contain the faulty phase. The first phase is 30° out of phase with the faulty phase. This refers to the second phase current in a set of windings of a dual three-phase motor that does not contain the faulty phase. The second phase is 150° out of phase with the faulty phase. The proportional gain of the observer; The estimated fault phase current; For the derivative sign; Step 3: Estimate the back electromotive force of the fault obtained in Step 2. Decompose to obtain intermediate variables and ; Step 4: Based on rotor position estimation error and intermediate variables and The relationship is used to obtain the estimated electrical angle of the motor.

2. The method for estimating the rotor position of a dual three-phase motor based on the fault phase diode current as described in claim 1, characterized in that: In step 3, according to the formula The fault back potential estimate obtained in step 2 Decompose to obtain intermediate variables and ,in and Same frequency and phase, and Orthogonal, with a 90-degree phase shift; for The expression after Laplace transform; These are the closed-loop coefficients. The resonant frequency, It is a complex frequency.

3. The method for estimating the rotor position of a dual three-phase motor based on the fault phase diode current according to claim 2, characterized in that: In step 4, according to the formula The estimated electrical angle of the motor was calculated. ;in for The rotor position estimation error at time t. To be After conversion to the time domain The value at time, To be After conversion to the time domain The value at time, In order, they are respectively Time and Estimated electrical angle at time, In order, they are respectively Time and The intermediate summation term at time, and These are, in order, the proportional coefficient and the integral coefficient; for The estimated electric angular velocity at any given time. For time step.

4. The method for estimating the rotor position of a dual three-phase motor based on the fault phase diode current as described in claim 1, characterized in that: If the dual three-phase motor uses a DSP as the control chip, then in step 1, current sampling is performed when the counter returns to zero and when the counter equals the period value, respectively, to obtain the fault phase current in the dual three-phase motor. .

5. The method for estimating the rotor position of a dual three-phase motor based on the fault phase diode current according to claim 1, characterized in that: In step 1, the fault phase current is collected. During a switching cycle, the currents of the inverters with faulty phases "x11" and "x00" in the switching state are sampled, and the current with the amplitude is taken as the faulty phase current. The switching state "xxx" is used to represent the switching state of the inverter. x has two states: 1 and 0. 1 means that the upper switch is on and the lower switch is off, and 0 means that the lower switch is on and the upper switch is off.

6. An electronic device comprising a processor and a memory, the memory being used to store one or more programs; characterized in that: When the one or more programs are executed by the processor, the method of any one of claims 1 to 5 is implemented.

7. A readable storage medium storing a computer program, characterized in that: When the computer program is executed by the processor, it implements the method described in any one of claims 1 to 5.

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