Current reconstruction method for open-winding permanent magnet synchronous motor in single-phase open-phase operation

Abstract

The invention relates to the technical field of open-winding permanent magnet synchronous motor control, in particular to a current reconstruction method for an open-winding permanent magnet synchronous motor in single-phase open-phase operation, which comprises the following steps: acquiring reference voltage under a coordinate system, a sector where a reference voltage vector synthesized by the reference voltage is located, first action time and second action time; acquiring bus current corresponding to the sector where the reference voltage vector is located, the first action time, the second action time and the minimum sampling time; and obtaining the phase current of the residual phase of the reconstructed open-winding permanent magnet synchronous motor. According to the invention, an unobservable area existing in a single-phase open-phase space vector pulse width modulation method is effectively reduced, the number of current sensors is reduced, the system cost is reduced, accurate reconstruction of the phase current is realized on the premise of keeping a symmetric triangular carrier modulation method, and the system performance is improved. And the performance and the reliability of the open-winding permanent magnet synchronous motor in single-phase open-phase operation are improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of open-winding permanent magnet synchronous motor control, and particularly relates to a current reconstruction method for an open-winding permanent magnet synchronous motor in single-phase open-phase operation. BACKGROUND

[0002] Compared with a traditional star-winding permanent magnet synchronous motor, an open-winding permanent magnet synchronous motor has higher fault tolerance and more flexible control mode. The three-phase open-winding motor adopts double inverters for independent current control, so that it can continue to work in the case of single-phase open-phase, and thus has good application value in high-reliability places. At present, researchers have applied the open-winding motor driving system to electric vehicles, high-power driving, starting / generating systems, wind power systems and other fields.

[0003] The open-winding permanent magnet synchronous motor needs to detect the phase current of each phase, and the use of multiple phase current sensors increases the system cost and volume and reduces the system reliability. In order to achieve the goals of low cost and high reliability of the motor control system, many scholars have invested in the research of phase current reconstruction methods. The open-winding motor not only needs to focus on the current reconstruction method under normal operation, but also needs to ensure that the current reconstruction can be realized to maintain the operation of the motor in the case of single-phase open-phase.

[0004] When the open-winding motor is in single-phase open-phase, the phase current of the remaining phase increases, and the motor system is mostly operated in the high modulation region. However, the existing current reconstruction methods such as pulse phase shift method, measured vector insertion method and three-state pulse width modulation method all have unobservable regions in the high modulation region. Therefore, it is necessary to study the current reconstruction method for the open-winding permanent magnet synchronous motor in single-phase open-phase operation in the high modulation region.

[0005] Therefore, it is necessary to provide a current reconstruction method for an open-winding permanent magnet synchronous motor in single-phase open-phase operation to solve the above problems. SUMMARY

[0006] To solve the problem that the existing current reconstruction methods such as pulse phase shift method, measured vector insertion method and three-state pulse width modulation method all have unobservable regions in the high modulation region, i.e. the existing technology cannot accurately reconstruct the current in the unobservable region of the high modulation region, the present application provides a current reconstruction method for an open-winding permanent magnet synchronous motor in single-phase open-phase operation to solve the existing problems.

[0007] The current reconstruction method for an open-winding permanent magnet synchronous motor in single-phase open-phase operation of the present application adopts the following technical scheme, comprising: According to the three-phase current of the open-winding permanent magnet synchronous motor, the reference voltage in the coordinate system is obtained According to the reference voltage in the coordinate system, the reference voltage in the coordinate system is obtained The reference voltage in the coordinate system, and the first action time, second action time, and... are obtained based on the single-phase missing-phase vector pulse width modulation method. The sector in which the synthesized reference voltage vector of the reference voltage in the coordinate system is located; In the high modulation region of the space voltage vector region, when the sector where the reference voltage vector is located is arbitrary, and both the first and second action times are greater than or equal to the minimum sampling time, sampling is performed at the first and second action times respectively to obtain the corresponding first bus current and second bus current; when the sector where the reference voltage vector is located is sector I, III, IV, or VI, and the first action time is greater than or equal to the minimum sampling time, and the second action time is less than the minimum sampling time, then sampling is performed only twice at the first action time to obtain the first bus current and second bus current; when the sector where the reference voltage vector is located is sector II or V, the first action time is greater than or equal to the minimum sampling time, and the second action time is less than the minimum sampling time, then sampling is performed twice only at the first action time to obtain the first bus current and second bus current; when the sector where the reference voltage vector is located is sector II or V, the first action time is greater than or equal to the minimum sampling time, and the second action time is less than the minimum sampling time. When the first action time is greater than or equal to the minimum sampling time, and the second action time is less than the minimum sampling time, then the target first action time is set to the difference between the first action time and the second action time. Sampling is performed only at the target first action time to obtain the first bus current and the second bus current. When the sector where the reference voltage vector is located is sector II or V, and the first action time is less than the minimum sampling time, and the second action time is greater than or equal to the minimum sampling time, then the target second action time is set to the difference between the second action time and the first action time. Sampling is performed only at the target second action time to obtain the first bus current and the second bus current. The first bus current and the second bus current are obtained from the sampling, and The sector where the reference voltage vector synthesized in the coordinate system is located is determined, and the phase current of the remaining phase of the reconstructed open-winding permanent magnet synchronous motor is obtained based on the single-phase missing-phase vector pulse width modulation method. Specifically, when the sector where the reference voltage vector is located is sector I, III, IV, or VI, and the first action time is less than the minimum sampling time, and the second action time is greater than or equal to the minimum sampling time, then sampling is performed only during the second action time to obtain the third bus current. The zero-sequence current is obtained from the third bus current, and the α-axis stator current at the current moment is obtained from the zero-sequence current. Based on the α-axis stator current and β-axis stator current at the previous moment, the following parameters are obtained: The estimated values ​​of the stator current along the α-axis and the stator current along the β-axis in the coordinate system, and based on the stator current along the α-axis at the current moment, The current error relationship in the coordinate system, as well as the estimated values ​​of the α-axis stator current and the β-axis stator current, are used to obtain the β-axis stator current at the current moment. The Clark inverse transformation is performed on the α-axis stator current and the β-axis stator current to obtain the phase current of the remaining phase of the reconstructed open-winding permanent magnet synchronous motor.

[0008] A further aspect of the present invention involves calculating the current based on the three-phase current of the open-winding permanent magnet synchronous motor using a closed-loop proportional-integral method. Reference voltage in the coordinate system.

[0009] A further aspect of the present invention is that... This is the high modulation region of the space voltage vector region, where, This is the bus voltage.

[0010] A further aspect of the present invention, according to The steps for obtaining the reference voltage in the coordinate system and the first and second action times of the space voltage vector based on the single-phase missing-phase vector pulse width modulation method are as follows: Will The first and second action times of the space voltage vector are obtained in the single-phase missing-phase vector pulse width modulation method of the reference voltage input in the coordinate system.

[0011] In a further embodiment of the present invention, the DC bus branches corresponding to the two inverters of the open-winding permanent magnet synchronous motor are arranged in opposite directions, and the same inductive current sensor is used to sample the bus current at both DC bus branches.

[0012] A further aspect of the present invention is to obtain the α-axis stator current and β-axis stator current at the previous moment. The steps for estimating the α-axis stator current and the β-axis stator current in the coordinate system are as follows:

[0013] In the formula, This represents the estimated value of the α-axis stator current at time k; This represents the estimated value of the β-axis stator current at time k; Indicates the control cycle; Indicates stator resistance; This represents the α-axis stator current at time k-1; This represents the α-axis stator current at time k-1; Let α represent the voltage along the α axis at time k; Represents the α-axis voltage at time k; Indicates stator inductance; Indicates the fundamental flux linkage; Indicates the rotor's electrical angular frequency; This indicates the rotor electrical angle.

[0014] A further aspect of the present invention is based on the current α-axis stator current. The steps to obtain the current β-axis stator current at the current moment are as follows: (Consider the current error relationship in the coordinate system, the estimated values ​​of the α-axis stator current, and the estimated values ​​of the β-axis stator current.)

[0015]

[0016] In the formula, This represents the difference between the current α-axis stator current and the estimated α-axis stator current. This represents the difference between the current β-axis stator current and the estimated β-axis stator current. This represents the estimated value of the α-axis stator current at time k; This represents the estimated value of the β-axis stator current at time k; This represents the stator current along the α axis at the current moment; This represents the β-axis stator current at the current moment.

[0017] In a further embodiment of the present invention, the sector comprises six sectors, namely I, II, III, IV, V, and VI, wherein each sector includes three regions: a, b, and c.

[0018] A further aspect of this invention is that the single-phase loss vector pulse width modulation method follows the principle of changing the switching state of only one bridge arm and minimizing the number of switching operations each time the inverter bridge arm is switched.

[0019] In a further embodiment of the present invention, sectors I, III, IV and VI only need to introduce zero vector 44' (0000) to participate in vector synthesis to form a five-segment SVPWM control waveform; sector II selects zero vector 24' (1000) and zero vector 23' (1011), sector V selects zero vector 42' (0010) and zero vector 32' (1110), and introduces zero vector 44' (0000) and zero vector 22' (1010) to participate in vector synthesis to form a seven-segment SVPWM control waveform.

[0020] The beneficial effects of this invention are: This invention, based on the single-phase loss space vector pulse width modulation method, can sample the sum of the phase currents of the remaining two phases in the single-vector unobservable region, thereby reconstructing the zero-sequence current. The α-β axis stator current is obtained through estimation. In the double-vector unobservable region, voltage vectors with the same effect are synthesized into a reference voltage vector through alternating arrangements, allowing the motor drive system sufficient DC bus sampling time to reconstruct the phase currents of the remaining two phases. Ultimately, this achieves closed-loop current operation of the open-winding permanent magnet synchronous motor during single-phase loss. This invention effectively reduces the unobservable region of the single-phase loss space vector pulse width modulation method, reduces the number of current sensors, lowers system costs, and achieves accurate phase current reconstruction while maintaining a symmetrical triangular carrier modulation method, thus improving the performance and reliability of the open-winding permanent magnet synchronous motor during single-phase loss operation.

[0021] Secondly, this invention improves the current detection circuit topology of the common DC bus type dual inverter by arranging the DC bus branches of the two inverters of the open-winding permanent magnet synchronous motor in reverse order and using the same inductive current sensor to sample the bus current. This reduces the number of current sensors used. Combined with the reconstruction algorithm and vector modulation method, it can still reconstruct the current of the open-winding permanent magnet synchronous motor when operating in single-phase loss mode, thus realizing the current closed-loop control of the system. The pulse width modulation (PWM) method of this invention is based on triangular carrier generation, which is simple and easy to apply in practice. It also maintains waveform symmetry, does not cause current waveform distortion, and avoids the increase of even-order harmonics and total harmonics. This invention can reconstruct the current of the open-winding permanent magnet synchronous motor when operating in single-phase loss mode by using the bus current collected by the DC bus current sensor. Without increasing the system cost, it can reduce the unobservable area in the high modulation region and improve the current closed-loop control effect of the open-winding permanent magnet synchronous motor when operating in single-phase loss mode. Attached Figure Description

[0022] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0023] Figure 1 This is a flowchart illustrating a current reconfiguration method for an open-winding permanent magnet synchronous motor during single-phase loss operation according to the present invention. Figure 2 This is a schematic diagram of the topology of the open-winding permanent magnet synchronous motor system for single-phase loss operation according to the present invention. Figure 3 This is a diagram showing the sector division results of the high and low modulation regions and the unobservable region in an embodiment of the present invention; Figure 4 This is a block diagram of the speed and current dual closed-loop control of the open-winding permanent magnet synchronous motor system during single-phase loss operation according to the present invention. Figure 5 In the embodiments of the present invention, coordinate system Shaft reference voltage and Shaft reference voltage The synthesized reference voltage vector is located in the sector Ic of the PWM waveform. Figure 6 In the embodiments of the present invention, coordinate system Shaft reference voltage and Shaft reference voltage The PWM waveform when the synthesized reference voltage vector is located in sector Ia; Figure 7 In the embodiments of the present invention, coordinate system Shaft reference voltage and Shaft reference voltage The synthesized reference voltage vector is located in sector II.a, which is the PWM waveform at that point. Figure 8 In the embodiments of the present invention, coordinate system Shaft reference voltage and Shaft reference voltage The synthesized reference voltage vector is located in sector II.b, which is the PWM waveform at that point. Figure 9 This is a schematic diagram of the current error relationship in a two-phase stationary coordinate system in an embodiment of the present invention; Figure 10 This is a schematic diagram of the simulation waveform of the phase current reconstructed using the reconstructed current method of the present invention. Detailed Implementation

[0024] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0025] This invention provides an embodiment of a current reconstruction method for an open-winding permanent magnet synchronous motor during single-phase loss operation. The motor used in this embodiment is a three-phase open-winding permanent magnet synchronous motor with a common DC bus topology. A Hall current sensor SL is selected as the inductive DC bus current sensor. The installation position and method are as follows. Figure 2 As shown, that is Figure 2To adopt a common DC bus topology, the bus branches of the two inverters are passed through the same DC bus current sensor for phase current reconstruction sampling. Taking phase A loss as an example, single-phase loss faults include four situations: (1) one or both switches of the A-phase bridge arm of the first inverter are open-circuited; (2) one end of the A-phase winding is open-circuited; (3) the other end of the A-phase winding is open-circuited; (4) one or both switches of the A-phase bridge arm of the second inverter are open-circuited; in addition, combinations of the above four faults of phase A are also included. In practical applications, due to some non-ideal factors of the system hardware, there will be a dead time T of the switching transistors. d Opening time T on The minimum sample-and-hold time T of the A / D converter A / D Among them, T A / D It is the sampling time t sam and A / D conversion time t conv The sum. When the power supply voltage is applied to the motor windings, due to the inductance in the windings, a certain settling and stabilization time T is required for the current to rise to a stable value. set Therefore, to accurately sample the DC bus current, the effective switching state should last for at least the minimum sampling time T. min In medium-vector modulation, the space voltage vector region can be divided into a low-modulation region and a high-modulation region, and its reconstruction dead zone is as follows: Figure 3 As shown, the high-modulation region and low-modulation region are divided by connecting the midpoints of six space voltage vectors sequentially. The unobservable region based on SVPWM is marked, and each sector is divided into three parts: a, b, and c. This invention mainly solves the problem of the unobservable region in the high-modulation region. The core idea of ​​this embodiment is: when the open-winding permanent magnet synchronous motor system operates with a single-phase loss, this embodiment adjusts the SVPWM in the unobservable region of the high-modulation region to meet the bus current sampling time, thus achieving bus current sampling. The sampled current is processed to obtain the reconstructed phase current or zero-sequence current, ultimately realizing dual closed-loop control of the system's speed and current, as shown below. Figure 4 As shown, the reference rotational speed n ref Compared with actual speed n The difference is used to obtain the reference q-axis stator current after passing through a PI controller. Set the reference d-axis stator current. =0, and Compared with the actual q-axis stator current i q and d-axis stator current i d The difference is processed by a PI controller to obtain the reference qd-axis voltage. and , and Obtained through Park inverse transform Under the axis and The switching S of the first inverter is obtained through the proposed SVPWM. bc1 and the switch S of the first inverter bc2 Taking the high modulation regions of sectors I and II as examples, we analyze SVPWM and current sampling to realize the current reconstruction of the system.

[0026] Specifically, such as Figure 1 As shown, a current reconfiguration method for an open-winding permanent magnet synchronous motor during single-phase loss operation according to this embodiment includes: S1, Obtain The reference voltage in the coordinate system, the sector where the synthesized reference voltage vector is located, the first action time, and the second action time; Specifically, based on the three-phase current of the open-winding permanent magnet synchronous motor, obtain... The reference voltage in the coordinate system, according to The reference voltage in the coordinate system, and the first action time, second action time, and... are obtained based on the single-phase missing-phase vector pulse width modulation method. The sector where the reference voltage vector synthesized from the reference voltage in the coordinate system is located.

[0027] For example, in one specific embodiment, the current is calculated based on the three-phase current of the open-winding permanent magnet synchronous motor using the current closed-loop proportional-integral method. Reference voltage in the coordinate system. That is, in this embodiment, the permanent magnet synchronous motor's... a Phase current is i a Permanent magnet synchronous motor b Phase current is i b Permanent magnet synchronous motor c Phase current is i c ; The reference voltage in the coordinate system is Shaft reference voltage and Shaft reference voltage .

[0028] For example, according to The steps for obtaining the reference voltage in the coordinate system and the first and second action times of the space voltage vector based on the single-phase missing-phase vector pulse width modulation method are as follows: Shaft reference voltage and Shaft reference voltage Substituting this into the single-phase missing-phase vector pulse width modulation method, we obtain the first action time T1 and the second action time T2 of the space voltage vector.

[0029] S2. Obtain the bus current corresponding to each of the following conditions: the sector where the reference voltage vector is located, the first action time, the second action time, and the minimum sampling time; Specifically, in the high-modulation region of the space voltage vector region, when both the first action time and the second action time are greater than or equal to the minimum sampling time, sampling is performed at the first action time and the second action time respectively to obtain the corresponding first bus current and second bus current; when the sector where the reference voltage vector is located is sector I, III, IV, or VI, and the first action time is greater than or equal to the minimum sampling time, and the second action time is less than the minimum sampling time, then sampling is performed only twice at the first action time to obtain the first bus current and the second bus current; when the sector where the reference voltage vector is located is sector II or V, and the first action time is greater than or equal to the minimum sampling time, and the second action time is less than the minimum sampling time, then the target first action time is set to... The first and second bus currents are obtained by sampling only during the target first action time, which is the difference between the first and second action times. When the reference voltage vector is located in sector II or V, the first action time is less than the minimum sampling time, and the second action time is greater than or equal to the minimum sampling time. Then, the target second action time is set to the difference between the second and first action times, and the first and second bus currents are obtained by sampling only during the target second action time. When the reference voltage vector is located in sector I, III, IV, or VI, the first action time is less than the minimum sampling time, and the second action time is greater than or equal to the minimum sampling time. Then, the third bus current is obtained by sampling only during the second action time.

[0030] For example, in one specific embodiment, the high modulation region of the space voltage vector region (i.e. , (This is the bus voltage), through Figure 3 The sector, the first action time T1, the second action time T2, and the minimum sampling time T min The process is divided into different scenarios: Specifically, in this embodiment, the sector consists of six sector-shaped regions, which are named I, II, III, IV, V, and VI in sequence. Each sector-shaped region includes three areas: a, b, and c. Where the sector where the reference voltage vector is located is any sector, and both the first action time and the second action time are greater than or equal to the minimum sampling time (T1≥T... min And T2≥T min ),Right now coordinate system Shaft reference voltage and Shaft reference voltage The synthesized reference voltage vector is located in sector Ic, IIc, IIIc, IVc, Vc, or VIc; this embodiment takes sector Ic as an example, and its modulation method is as follows: Figure 5 As shown, during the first action time T1, the current sensor S... L The first bus current i was obtained by sampling. dc1 During the second action time T2, the current sensor S L The second bus current i was obtained by sampling dc2 .

[0031] Specifically, when the reference voltage vector is located in sector I, III, IV, or VI, the first action time is greater than or equal to the minimum sampling time, and the second action time is less than the minimum sampling time (T1≥T...). min And T2 < T min (time), that is coordinate system Shaft reference voltage and Shaft reference voltage The sector where the synthesized reference voltage vector is located is sector Ia, III.b, IV.a, or VI.b. This embodiment takes sector Ia (the unobservable region of the two vectors) as an example. Figure 3 As shown, by alternating the vector U6 with a first action time of T1, the five-segment SVPWM is transformed into a seven-segment SVPWM, and its modulation method is as follows. Figure 6 As shown, since the vectors themselves alternate, the current sensor S only passes through during the first action time T1. L The first bus current i is obtained by sampling twice. dc1 Second bus current i dc2 .

[0032] Specifically, when the sector where the reference voltage vector is located is sector II or V, the first action time is greater than or equal to the minimum sampling time, and the second action time is less than the minimum sampling time (T1≥T...). min And T2 < T min (time), that is coordinate system Shaft reference voltage and Shaft reference voltage The sector where the synthesized reference voltage vector is located is sector II.a or Va. In this embodiment, sector II.a (the unobservable region of the two vectors) is taken as an example. Let the first action time of the target vector U2 corresponding to the first action time be T1. ,but The auxiliary voltage vector is the large vector 21' of sector II, and the duration of the auxiliary voltage vector is... ,but Its modulation method is as follows: Figure 7 As shown, since the vectors appear alternately, the first action time of the target only occurs during the vector's action time. Time through current sensor S L The first bus current i was obtained by sampling. dc1 Second bus current i dc2 .

[0033] Specifically, when the reference voltage vector is located in sector II or V, the first action time is less than the minimum sampling time, and the second action time is greater than or equal to the minimum sampling time (T1 < T). min And T2≥T min ),Right now coordinate system Shaft reference voltage and Shaft reference voltage The sector where the synthesized reference voltage vector is located is sector II.b or Vb. In this embodiment, sector II.b (the unobservable region of the two vectors) is taken as an example. Let the target second action time of vector U6, whose second action time is T2, be... ,but The auxiliary voltage vector is the large vector 21' of sector II, and the duration of the auxiliary voltage vector is... ,but Its modulation method is as follows: Figure 8 As shown, since the vectors themselves appear alternately, the second action time of the target only occurs during the vector's action time. At that time, through the current sensor S L The first bus current i was obtained by sampling. dc1 Second bus current i dc2 .

[0034] Specifically, when the reference voltage vector is located in sector I, III, IV, or VI, the first action time is less than the minimum sampling time, and the second action time is greater than or equal to the minimum sampling time (T1 < T). min And T2≥T min ),Right now coordinate system Shaft reference voltage and Shaft reference voltage The synthesized reference voltage vector is located in sector Ib, III.a, IV.b, or VI.a. Taking the reference voltage vector as being in sector Ib (the unobservable region of a single vector) as an example, the third bus current i is obtained only when the vector action time is the second action time T2. dc3 .

[0035] It should be noted that the sector consists of six sector regions, namely I, II, III, IV, V, and VI. Each sector region includes three regions: a, b, and c. The single-phase missing phase vector pulse width modulation method follows the principle of changing the switching state of only one bridge arm and minimizing the number of switching operations each time the inverter bridge arm is switched. For sectors I, III, IV, and VI, only zero vector 44' (0000) needs to be introduced to participate in vector synthesis to form a five-segment SVPWM control waveform. For sector II, zero vectors 24' (1000) and 23' (1011) are selected, and for sector V, zero vectors 42' (0010) and 32' (1110) are selected. Zero vectors 44' (0000) and 22' (1010) are introduced to participate in vector synthesis to form a seven-segment SVPWM control waveform.

[0036] Thus, the bus current under the relationship between the first action time, the second action time, and the minimum sampling time is obtained.

[0037] S3. Obtain the phase current of the remaining phases of the reconstructed open-winding permanent magnet synchronous motor; Specifically, the first bus current and the second bus current are obtained based on sampling, and The sector where the reference voltage vector synthesized in the coordinate system is located is determined, and the phase current of the remaining phase of the reconstructed open-winding permanent magnet synchronous motor is obtained based on the single-phase missing-phase vector pulse width modulation method. Specifically, when the sector where the reference voltage vector is located is sector I, III, IV, or VI, and the first action time is less than the minimum sampling time, and the second action time is greater than or equal to the minimum sampling time, the zero-sequence current is obtained from the third bus current, the α-axis stator current at the current moment is obtained from the zero-sequence current, and the α-axis stator current at the previous moment is obtained from the α-axis stator current and β-axis stator current at the previous moment. The estimated values ​​of the stator current along the α-axis and the stator current along the β-axis in the coordinate system, and based on the stator current along the α-axis at the current moment, The current error relationship in the coordinate system, as well as the estimated values ​​of the α-axis stator current and the β-axis stator current, are used to obtain the β-axis stator current at the current moment. The Clark inverse transformation is performed on the α-axis stator current and the β-axis stator current to obtain the phase current of the remaining phase of the reconstructed open-winding permanent magnet synchronous motor.

[0038] For example, in one specific embodiment, when phase A is missing, the first remaining phase is phase B, and the second remaining phase is phase C. Then, the reconstructed open-winding permanent magnet synchronous motor when phase A is missing... b Phase current i b , c Phase current i c The values ​​are shown in Table 1.

[0039] Table 1

[0040] When phase B is missing, the first remaining phase is phase C, and the second remaining phase is phase A. Therefore, the reconstructed open-winding permanent magnet synchronous motor after phase B loss... c Phase current i c , a Phase current i a The values ​​are shown in Table 2.

[0041] Table 2

[0042] When phase C is missing, the first remaining phase is phase A, and the second remaining phase is phase B. Therefore, the phase current of the reconstructed open-winding permanent magnet synchronous motor when phase C is missing is... a Phase current i a , b Phase current i b The values ​​are shown in Table 3.

[0043] Table 3

[0044] For example, in one specific embodiment, when the sector where the reference voltage vector is located is sector I, III, IV, or VI, and the first action time is less than the minimum sampling time, and the second action time is greater than or equal to the minimum sampling time, then the zero-sequence current needs to be obtained based on the third bus current. The expression for the zero-sequence current is:

[0045] In the formula, i a express a Phase current; i b express b Phase current; i c express cPhase current; This indicates the phase loss current, i.e. Pick a、 b or c That is, when any single phase is missing, the corresponding phase current is 0; The expression for the third bus current, based on the zero-sequence current expression, can be obtained as follows: The relationship between the zero-sequence current and the α-axis stator current is: ; Based on the α-axis stator current and β-axis stator current at the previous moment, and the voltage equation for the α-β axis, we can obtain... The estimated values ​​of the stator current along the α-axis and the stator current along the β-axis in the coordinate system are as follows:

[0046] In the formula, This represents the estimated value of the stator current along the α-axis at time k (i.e., the projected component of the stator current along the α-axis). This represents the estimated value of the stator current along the β axis at time k (the projected component of the stator current along the α axis). Indicates the control cycle; Indicates stator resistance; This represents the α-axis stator current at time k-1; This represents the α-axis stator current at time k-1; Represents the α-axis voltage at time k; Represents the α-axis voltage at time k; Indicates stator inductance; Indicates the fundamental flux linkage; Indicates the rotor's electrical angular frequency; This indicates the rotor electrical angle.

[0047] pass The relationship between current error in the coordinate system, such as Figure 9 As shown, we can obtain ,in , It is the difference between the actual current value and the estimated current value, that is:

[0048] In the formula, This represents the difference between the current α-axis stator current and the estimated α-axis stator current. This represents the difference between the current β-axis stator current and the estimated β-axis stator current. This represents the estimated value of the α-axis stator current at time k; This represents the estimated value of the β-axis stator current at time k; This represents the stator current along the α axis at the current moment; This represents the β-axis stator current at the current moment.

[0049] The above equation yields the α-axis stator current. and β-axis stator current This enables current reconstruction and closed-loop current control of the open-winding permanent magnet synchronous motor system, controlling the α-axis stator current. and β-axis stator current The phase currents of the remaining phases of the reconstructed open-winding permanent magnet synchronous motor are obtained by performing the Clark inverse transform.

[0050] At this point, the current i passing through the first busbar... dc1 Second bus current i dc2 and the third bus current i dc3 The phase current of an open-winding permanent magnet synchronous motor operating in single-phase loss mode can be reconstructed, and the current waveform is as follows: Figure 10 As shown.

[0051] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A current reconfiguration method for an open-winding permanent magnet synchronous motor during single-phase loss operation, characterized in that, include: Based on the three-phase current of the open-winding permanent magnet synchronous motor, obtain The reference voltage in the coordinate system, according to The reference voltage in the coordinate system, and the first action time, second action time, and... are obtained based on the single-phase missing-phase vector pulse width modulation method. The sector in which the synthesized reference voltage vector of the reference voltage in the coordinate system is located; In the high modulation region of the space voltage vector region, when the sector where the reference voltage vector is located is arbitrary, and the first action time and the second action time are both greater than or equal to the minimum sampling time, the corresponding first bus current and second bus current are obtained by sampling at the first action time and the second action time, respectively. When the reference voltage vector is located in sector I, III, IV, or VI, and the first action time is greater than or equal to the minimum sampling time, and the second action time is less than the minimum sampling time, then the first bus current and the second bus current are obtained by sampling twice only during the first action time. When the reference voltage vector is located in sector II or V, and the first action time is greater than or equal to the minimum sampling time, and the second action time is less than the minimum sampling time, then the target first action time is set to the difference between the first action time and the second action time, and the first bus current and the second bus current are obtained by sampling only during the target first action time. When the reference voltage vector is located in sector II or V, and the first action time is less than the minimum sampling time, and the second action time is greater than or equal to the minimum sampling time, then the target second action time is set to the difference between the second action time and the first action time, and the first bus current and the second bus current are obtained by sampling only during the target second action time. The first bus current and the second bus current are obtained from the sampling, and The sector where the reference voltage vector synthesized in the coordinate system is located is determined, and the phase current of the remaining phase of the reconstructed open-winding permanent magnet synchronous motor is obtained based on the single-phase missing-phase vector pulse width modulation method. Specifically, when the sector where the reference voltage vector is located is sector I, III, IV, or VI, and the first action time is less than the minimum sampling time, and the second action time is greater than or equal to the minimum sampling time, then sampling is performed only during the second action time to obtain the third bus current. The zero-sequence current is obtained from the third bus current, and the α-axis stator current at the current moment is obtained from the zero-sequence current. Based on the α-axis stator current and β-axis stator current at the previous moment, the following parameters are obtained: The estimated values ​​of the stator current along the α-axis and the stator current along the β-axis in the coordinate system, and based on the stator current along the α-axis at the current moment, The current error relationship in the coordinate system, as well as the estimated values ​​of the α-axis stator current and the β-axis stator current, are used to obtain the β-axis stator current at the current moment. The Clark inverse transformation is performed on the α-axis stator current and the β-axis stator current to obtain the phase current of the remaining phase of the reconstructed open-winding permanent magnet synchronous motor.

2. The current reconfiguration method for an open-winding permanent magnet synchronous motor during single-phase loss operation according to claim 1, characterized in that, Based on the three-phase current of the open-winding permanent magnet synchronous motor, and calculated using the current closed-loop proportional-integral method, the following is obtained: Reference voltage in the coordinate system.

3. The current reconfiguration method for an open-winding permanent magnet synchronous motor during single-phase loss operation according to claim 1, characterized in that, exist This is the high modulation region of the space voltage vector region, where, This is the bus voltage.

4. The current reconfiguration method for an open-winding permanent magnet synchronous motor during single-phase loss operation according to claim 1, characterized in that, according to The steps for obtaining the reference voltage in the coordinate system and the first and second action times of the space voltage vector based on the single-phase missing-phase vector pulse width modulation method are as follows: Will The first and second action times of the space voltage vector are obtained in the single-phase missing-phase vector pulse width modulation method of the reference voltage input in the coordinate system.

5. The current reconfiguration method for an open-winding permanent magnet synchronous motor during single-phase loss operation according to claim 1, characterized in that, The DC bus branches corresponding to the two inverters of the open-winding permanent magnet synchronous motor are arranged in opposite directions, and the same inductive current sensor is used to sample the bus current at both DC bus branches.

6. The current reconfiguration method for an open-winding permanent magnet synchronous motor during single-phase loss operation according to claim 1, characterized in that, Based on the α-axis stator current and β-axis stator current at the previous moment, obtain The steps for estimating the α-axis stator current and the β-axis stator current in the coordinate system are as follows: In the formula, This represents the estimated value of the α-axis stator current at time k; This represents the estimated value of the β-axis stator current at time k; Indicates the control cycle; Indicates stator resistance; This represents the α-axis stator current at time k-1; This represents the α-axis stator current at time k-1; Let α represent the voltage along the α axis at time k; Represents the α-axis voltage at time k; Indicates stator inductance; Indicates the fundamental flux linkage; Indicates the rotor's electrical angular frequency; This indicates the rotor electrical angle.

7. The current reconfiguration method for an open-winding permanent magnet synchronous motor during single-phase loss operation according to claim 1, characterized in that, Based on the current α-axis stator current, The steps to obtain the current β-axis stator current at the current moment are as follows: (Consider the current error relationship in the coordinate system, the estimated values ​​of the α-axis stator current, and the estimated values ​​of the β-axis stator current.) In the formula, This represents the difference between the current α-axis stator current and the estimated α-axis stator current. This represents the difference between the current β-axis stator current and the estimated β-axis stator current. This represents the estimated value of the α-axis stator current at time k; This represents the estimated value of the β-axis stator current at time k; Indicates the rotor electrical angle; This represents the α-axis stator current at the current moment; This represents the β-axis stator current at the current moment.

8. The current reconfiguration method for an open-winding permanent magnet synchronous motor during single-phase loss operation according to claim 1, characterized in that, The sector consists of six sectors, numbered I, II, III, IV, V, and VI respectively. Each sector includes three regions: a, b, and c.

9. A current reconfiguration method for an open-winding permanent magnet synchronous motor during single-phase loss operation according to claim 8, characterized in that, The single-phase loss vector pulse width modulation method follows the principle of changing the switching state of only one bridge arm and minimizing the number of switching operations each time the inverter bridge arm is switched.

10. A current reconfiguration method for an open-winding permanent magnet synchronous motor during single-phase loss operation according to claim 9, characterized in that, Sectors I, III, IV and VI only need to introduce zero vector 44' (0000) to participate in vector synthesis to form a five-segment SVPWM control waveform; sector II selects zero vector 24' (1000) and zero vector 23' (1011), sector V selects zero vector 42' (0010) and zero vector 32' (1110), and introduces zero vector 44' (0000) and zero vector 22' (1010) to participate in vector synthesis to form a seven-segment SVPWM control waveform.

Images