Predictive Current Control Method for Semi-Centralized Open-Winding Permanent Magnet Synchronous Motor System

Abstract

The present invention discloses a three-vector predictive current control method for a semi-centralized open-winding permanent magnet synchronous motor system, belonging to the technical field of motor drive and control. The system consists of two open-winding three-phase permanent magnet synchronous motors sharing a common DC bus, three two-level inverters, and a predictive current control unit, for the DC bus voltage U dc , the three-phase currents i a1 (k), i b1 (k), i c1 (k), i a2 (k), i b2 (k), i c2 (k), the rotor position angles θ m1 (k), θ m2 (k), the mechanical rotational angular velocities ω m1 (k), ω m2 (k) are sampled; then the currents i d1 (k + 1), i q1 (k + 1), i 01 (k + 1), i d2 (k + 1), i q2 (k + 1), i 02 (k + 1) in the next state are predicted; the voltage reference value in the k + 1 state is deduced according to the deadbeat principle; a two-dimensional plane space based on phase voltage vectors is constructed to quickly confirm the sector and calculate the durations of two adjacent basic effective phase voltage vectors and a zero-phase voltage vector, realizing the deadbeat output of the reference phase voltage vector within the modulation range, so as to improve the steady-state performance of the system.

Description

Technical Field

[0001] The present invention is a three-vector predictive current control method for a semi-centralized open-winding permanent magnet synchronous motor system, belonging to the technical field of motor drive and control. Background Art

[0002] In a drive system composed of n motors, a traditional open-winding permanent magnet synchronous motor would require 2n inverters, which would occupy a huge volume and increase costs. By sharing a multiplexed inverter on one side of these motors, the number of required inverters can be reduced to n + 1. However, since these inverters belong to the same control system, the number of voltage vectors will increase exponentially, which is not conducive to the use of predictive current control. Summary of the Invention

[0003] Objective of the Invention: The present invention proposes a three-vector predictive current control system based on a semi-centralized open-winding permanent magnet synchronous motor system for the field of electric drive. This method proposes the concept of phase voltage vectors. Utilizing the characteristics of the three independent phases of the open-winding motor, the durations of two basic effective phase voltage vectors and one basic zero voltage vector of each phase are calculated respectively, and then their corresponding trigger signals are distributed to each inverter. While ensuring the cooperative control effect, steady-state performance, and zero-sequence current suppression performance of the two motors, the computational complexity is greatly reduced.

[0004] Technical Solution: A three-vector predictive current control method for a semi-centralized open-winding permanent magnet synchronous motor system, which calculates the durations of two basic effective phase voltage vectors and one basic zero voltage vector of each phase respectively, and then distributes their corresponding trigger signals to each inverter.

[0005] Further, the method includes controlling the a-phase voltage of the motor through the a-phase bridge arm of the independent inverters and the multiplexed inverter of the two motors, and the same applies to the b and c phases.

[0006] Further, the method includes sampling the current of each phase, rotor speed, rotor position of the two motors, and the DC bus voltage data of the inverter, and then calculating the durations of two basic effective phase voltage vectors and one basic zero voltage vector of each phase at the next moment.

[0007] Further, the method includes calculating the optimal phase voltage vector at the next moment, generating a control signal and sending it into the inverter to control the bridge arm switching state of the inverter, forming a closed-loop control system of inverter - motor - control unit - inverter.

[0008] Advantageous Effects:

[0009] By calculating three parameters related to the spatial position of the reference phase voltage vector, the sector can be quickly confirmed, and the durations of two adjacent basic effective phase voltage vectors and a zero-phase voltage vector can be calculated, realizing the error-free output of the reference phase voltage vector within the modulation range, thereby improving the steady-state performance of the system. Brief Description of the Drawings

[0010] Figure 1 is the semi-concentrated open-winding permanent magnet synchronous motor topology;

[0011] Figure 2 is the distribution diagram of the phase voltage vector, its sector schematic diagram and N m distribution;

[0012] Figure 3 is the control block diagram of the three-vector predictive current control system for the semi-concentrated open-winding permanent magnet synchronous motor system;

[0013] Figure 4 is the experimental waveform of the three-vector predictive current control strategy. Detailed Embodiment

[0014] The following combines the attached Figure 1 to elaborate on the technical solution of the present invention in detail;

[0015] As shown in the attached Figure 1 A three-vector predictive current control method for a semi-concentrated open-winding permanent magnet synchronous motor system disclosed in an embodiment of the present invention is characterized in that: the system includes two three-phase open-winding permanent magnet synchronous motors, three two-level voltage source inverters, and a predictive current control unit. The three inverters are connected in a common DC bus manner. Each open-winding motor needs to be powered from both the left and right ends simultaneously. The two motors are respectively called the first motor and the second motor. One independent inverter is used at the left end of the first motor and the right end of the second motor, while the right end of the first motor and the left end of the second motor share a multiplexed inverter. The respective independent inverters are called the first inverter and the second inverter, and the shared multiplexed inverter is called the zero inverter; by controlling the a-phase bridge arm of the first inverter and the zero inverter, the a-phase voltage of the first motor can be controlled. By controlling the a-phase bridge arm of the second inverter and the zero inverter, the a-phase voltage of the second motor can be controlled. The same applies to the b and c phases; the predictive current control unit samples the phase currents, rotor speed, rotor position, and DC bus voltage data of the two motors, calculates the optimal phase voltage vector at the next moment, generates a control signal and sends it into the inverter to control the bridge arm switching state of the inverter, forming a closed-loop control system of inverter-motor-control unit-inverter. The specific implementation steps are as follows:

[0016] (1) First, for the DC bus voltage U dc, the three-phase currents i of two permanent magnet synchronous motors a1 (k), i b1 (k), i c1 (k), i a2 (k), i b2 (k), i c2 (k), the rotor position angle θ m1 (k), θ m2 (k), the mechanical rotational angular velocity ω m1 (k), ω m2 (k) are sampled, and through coordinate transformation, the i in the dq0 coordinate system is obtained d1 (k), i q1 (k), i 01 (k), i d2 (k), i q2 (k), i 02 (k);

[0017]

[0018] Among them, P n is the number of pole pairs, k represents the value at the current moment, k + 1 represents the value at the next moment, and so on; the subscript 1 represents the value of the first motor, and the subscript 2 represents the value of the second motor;

[0019] (2) According to the motor phase current i in the synchronous rotating dq0 coordinate system at the current moment, i.e., k moment d1 (k), i q1 (k), i 01 (k), i d2 (k), i q2 (k), i 02 (k), combined with the value u of the current motor phase voltage in the dq0 coordinate system d1 (k), u q1 (k), u 01 (k), u d2 (k), u q2 (k), u 02 (k), substitute it into the discrete-domain mathematical model to predict the motor phase current i at the k + 1 moment d1 (k + 1), i q1 (k + 1), i 01 (k + 1), i d2 (k + 1), i q2 (k + 1), i 02 (k + 1);

[0020]

[0021] Among them, F1(k), F2(k), G, H1(k), and H2(k) are matrices;

[0022]

[0023] Among them, T s is the sampling period; R is the phase resistance; L d is the direct-axis inductance; L q is the quadrature-axis inductance; L0 is the zero-sequence inductance; ψ f1 is the fundamental component of the permanent magnet flux linkage; ψ f3 is the third harmonic component of the permanent magnet flux linkage;

[0024] (3) Obtain the quadrature-axis current reference values of two permanent magnet motors at the (k + 2)th moment through the speed regulator and set the direct-axis current reference value and the zero-sequence current reference value (k + 2) to 0;

[0025] (4) According to the deadbeat principle, based on the motor phase current reference values at the (k + 2)th moment and the motor phase current values at the (k + 1)th moment i d1 (k + 1), i q1 (k + 1), i 01 (k + 1), i d2 (k + 1), i q2 (k + 1), i 02 derive the motor phase voltage reference values at the (k + 1)th moment

[0026]

[0027] Among them, G -1 is the inverse matrix of the G matrix;

[0028] (5) Transform the motor phase voltage reference values through coordinate transformation to obtain the phase voltage reference values in the abc coordinate system From and Combine to obtain the reference phase voltage vectors of the m phases, where m = a, b, c.

[0029]

[0030] (6) List the 8 basic phase voltage vectors (u m1 , u m2), m = a, b, c and the switching states of their bridge arms (S m1 , S m2 , S m0 ), as shown in Table 1;

[0031] Table 1

[0032]

[0033] In the table, S mn are the switching states of the bridge arms of each phase of each inverter. When S mn = 1, the upper bridge arm of the bridge arm m of the inverter n conducts; otherwise, the lower bridge arm of the bridge arm m of the inverter n conducts, m = a, b, c; n = 1, 2, 0; u m1 , u m2 are the phase m voltages of the first motor and the second motor respectively, m = a, b, c. U dc is the DC bus voltage.

[0034] (7) Calculate the parameters X m , Y m , Z m , N m , m = a, b, c. And determine the sector where the reference phase voltage vector of the m phase is located and the basic effective phase voltage vectors that will be used to synthesize the reference phase voltage vector according to Table 2.

[0035]

[0036] N m = X m + 4 * Y m + 16 * Z m

[0037] Table 2

[0038]

[0039] (8) Calculate the transverse axis duration T xm and the longitudinal axis duration T ym , m = a, b, c.

[0040]

[0041] In the formula, T s is the control period.

[0042] (9) Combine the situations of each sector to allocate T xm and T ym to the 2 basic effective phase voltage vectors selected in (7). T jm That is, the phase m V jDuration of the vector, j = 0, 1, 2, 3, 4, 5, 6, 7; m = a, b, c.

[0043] ① When the reference phase voltage vector is in sector 1, only V2 can provide the direct-axis duration, so all of T ym is allocated to V2. However, V2 also provides part of the quadrature-axis duration. The quadrature-axis duration not satisfied by V2 is allocated to V1, and the effective duration T m is obtained as shown in the following equation:

[0044] T 2m = T ym ; T 1m = T xm - T ym ; T m = T 1m + T 2m

[0045] ② When the reference phase voltage vector is in sector 2, only V2 can provide the quadrature-axis duration, so all of T xm is allocated to V2. However, V2 also provides part of the direct-axis duration. The direct-axis duration not satisfied by V2 is allocated to V3, and the effective duration T m is obtained as shown in the following equation:

[0046] T 2m = T xm ; T 3m = T ym - T xm ; T m = T 2m + T 3m

[0047] ③ When the reference phase voltage vector is in sector 3, only V4 can provide the quadrature-axis duration and only V3 can provide the direct-axis duration. So all of T xm is allocated to V4, and at the same time all of T ym is allocated to V3, and the effective duration T m is obtained as shown in the following equation:

[0048] T 4m = T xm ; T 3m = T ym ; T m = T 3m + T 4m

[0049] ④ When the reference phase voltage vector is in sector 4, only V5 can provide the direct-axis duration, so all of T ymAllotted to V5. At the same time, V5 also provides part of the horizontal axis duration. The horizontal axis duration not satisfied by V5 is allotted to V4, and the effective duration T is obtained as follows: m , as shown in the following formula:

[0050] T 5m = T ym ; T 4m = T xm - T ym ; T m = T 4m + T 5m

[0051] ⑤ When the reference phase voltage vector is located in sector 5, only V5 can provide the horizontal axis duration. Therefore, all T xm are allotted to V5. At the same time, V5 also provides part of the vertical axis duration. The vertical axis duration not satisfied by V5 is allotted to V6, and the effective duration T is obtained as follows: m , as shown in the following formula:

[0052] T 5m = T xm ; T 6m = T ym - T xm ; T m = T 5m + T 6m

[0053] ⑥ When the reference phase voltage vector is located in sector 6, only V1 can provide the horizontal axis duration, and only V6 can provide the vertical axis duration. Therefore, all T xm are allotted to V1, and at the same time, all T ym are allotted to V6, and the effective duration T is obtained as follows: m , as shown in the following formula:

[0054] T 1m = T xm ; T 6m = T ym ; T m = T 6m + T 1m

[0055] (10) Combining the effective durations T a , T b and T c , when the maximum value T max is greater than the control period T s , three-phase synchronization amplitude limiting is required to ensure that the durations of all three phases can be within T s . The adjustment coefficient η is obtained through the following formula:

[0056]

[0057] D jm That is, the m-phase V j The duration after vector adjustment, j = 0, 1, 2, 3, 4, 5, 6, 7; m = a, b, c.

[0058] D jm = ηT jm

[0059] (11) Distribute the redundant duty ratio of each phase equally to two basic zero-phase voltage vectors to obtain D 0m and D 7m :

[0060]

[0061] (12) Combine the situation of each sector to distribute the adjusted duration of the basic effective phase voltage vector to the specific bridge arm, t im is the conduction duration of the upper bridge arm of the m-phase bridge arm of inverter i, i = 0, 1, 2; m = a, b, c.

[0062] ① When the reference phase voltage vector of the m-phase is in sector 1, V1, V2, and V7 require the upper bridge arm of the m-phase of inverter 1 to conduct, V2 and V7 require the upper bridge arm of the m-phase of inverter 2 to conduct, and V7 requires the upper bridge arm of the m-phase of inverter 0 to conduct, as shown in the following formula:

[0063] t 1m = D 1m + D 2m + D 7m ; t 2m = D 2m + D 7m ; t 0m = D 7m

[0064] ② When the reference phase voltage vector of the m-phase is in sector 2, V2 and V7 require the upper bridge arm of the m-phase of inverter 1 to conduct, V2, V3, and V7 require the upper bridge arm of the m-phase of inverter 2 to conduct, and V7 requires the upper bridge arm of the m-phase of inverter 0 to conduct, as shown in the following formula:

[0065] t 1m = D 2m + D 7m ; t 2m = D 2m + D 3m + D 7m ; t 0m = D 7m

[0066] ③When the reference phase voltage vector of the m-phase is located in sector 3, V7 requires the upper arm of the m-phase of the first inverter to conduct, V3, V4, and V7 require the upper arm of the m-phase of the second inverter to conduct, and V4 and V7 require the upper arm of the m-phase of the zero-th inverter to conduct, as shown in the following formula:

[0067] t 1m = D 7m ; t 2m = D 3m + D 4m + D 7m ; t 0m = D 4m + D 7m

[0068] ④When the reference phase voltage vector of the m-phase is located in sector 4, V7 requires the upper arm of the m-phase of the first inverter to conduct, V4 and V7 require the upper arm of the m-phase of the second inverter to conduct, and V4, V5, and V7 require the upper arm of the m-phase of the zero-th inverter to conduct, as shown in the following formula:

[0069] t 1m = D 7m ; t 2m = D 4m + D 7m ; t 0m = D 4m + D 5m + D 7m

[0070] ⑤When the reference phase voltage vector of the m-phase is located in sector 5, V6 and V7 require the upper arm of the m-phase of the first inverter to conduct, V7 requires the upper arm of the m-phase of the second inverter to conduct, and V5, V6, and V7 require the upper arm of the m-phase of the zero-th inverter to conduct, as shown in the following formula:

[0071] t 1m = D 6m + D 7m ; t 2m = D 7m ; t 0m = D 5m + D 6m + D 7m

[0072] ⑥When the reference phase voltage vector of the m-phase is located in sector 6, V1, V6, and V7 require the upper arm of the m-phase of the first inverter to conduct, V7 requires the upper arm of the m-phase of the second inverter to conduct, and V6 and V7 require the upper arm of the m-phase of the zero-th inverter to conduct, as shown in the following formula:

[0073] t 1m = D 1m + D 6m + D 7m ; t2m = D 7m ; t 0m = D 6m + D 7m

[0074] (13) Generate a drive signal according to the result of (12) to control the switching state of the inverter bridge arm, and then control the motor terminal voltage. At the same time, sample the operating state of the motor at time k + 1 and enter the next control cycle.

[0075] In order to verify the effect of the present invention, experimental verification was carried out. Figure 1 is a semi - centralized open - winding permanent - magnet synchronous motor topology structure, Figure 2 is the distribution diagram of phase voltage vectors, its sector schematic diagram and N m distribution, Figure 3 is the control block diagram of the three - vector predictive current control system for a semi - centralized open - winding permanent - magnet synchronous motor system, Figure 4 is the experimental waveform adopting the three - vector predictive current control strategy. Figure 4 The experimental results show that the three - vector predictive current control system based on a semi - centralized open - winding permanent - magnet synchronous motor proposed by the present invention can stably co - control two motors and effectively suppress the zero - sequence current within ±0.1 A.

[0076] In the description of this specification, the descriptions referring to terms such as "an embodiment", "example", "specific example", etc. mean that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in a suitable manner in any one or more embodiments or examples.

[0077] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art of this industry should understand that the present invention is not limited by the above - mentioned embodiments. The above - mentioned embodiments and the descriptions in the specification only illustrate the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention will have various changes and improvements, and these changes and improvements all fall within the scope of the present invention claimed.

Claims

1. A three-vector predictive current control method for a semi-centralized open-winding permanent magnet synchronous motor system, characterized in that The method calculates the durations of two basic effective phase voltage vectors and one basic zero voltage vector of each phase respectively, and then distributes their corresponding trigger signals to each inverter. The method includes controlling the phase-a voltage of the motor through the phase-a bridge arm of the independent inverters and the multiplexed inverter of two motors, and the same applies to phases b and c. The specific steps of the method are as follows: The selected effective phase voltage vectors are the 8 basic phase voltage vectors of each phase of the three inverters in the system (u m1 , u m2 ): V0(0, 0), V1(U dc , 0), V2(U dc , U dc ), V3(0, U dc ), V4(-U dc , 0), V5(-U dc , -U dc ), V6(0, -U dc ), V7(0, 0); u m1 , u m2 are the phase m voltages of the first motor and the second motor respectively, m = a, b, c, U dc is the DC bus voltage. The voltage vectors are divided into six sectors by the effective phase voltage vectors. Combining the situations of each sector, the durations of the adjusted basic effective phase voltage vectors are allocated to specific bridge arms. t im is the conduction duration of the upper bridge arm of the m-phase bridge arm of the inverter i, i = 0, 1, 2; m = a, b, c; 1) When the reference phase voltage vector of phase m is located in sector 1, V1, V2, and V7 require the upper bridge arm of phase m of the first inverter to conduct, V2 and V7 require the upper bridge arm of phase m of the second inverter to conduct, and V7 requires the upper bridge arm of phase m of the zero-th inverter to conduct, as shown in the following formula: t 1m = D 1m + D 2m + D 7m ; t 2m = D 2m + D 7m ; t 0m = D 7m 2) When the reference phase voltage vector of phase m is located in sector 2, V2 and V7 require the upper bridge arm of phase m of the first inverter to conduct, V2, V3, and V7 require the upper bridge arm of phase m of the second inverter to conduct, and V7 requires the upper bridge arm of phase m of the zero-th inverter to conduct, as shown in the following formula: t 1m = D 2m + D 7m ; t 2m = D 2m + D 3m + D 7m ; t 0m = D 7m 3) When the reference phase voltage vector of phase m is located in sector 3, V7 requires the upper bridge arm of phase m of the first inverter to conduct, V3, V4, and V7 require the upper bridge arm of phase m of the second inverter to conduct, and V4 and V7 require the upper bridge arm of phase m of the zero-th inverter to conduct, as shown in the following formula: t 1m = D 7m ; t 2m = D 3m + D 4m + D 7m ; t 0m = D 4m + D 7m 4) When the reference phase voltage vector of phase m is located in sector 4, V7 requires the upper bridge arm of phase m of the first inverter to conduct, V4 and V7 require the upper bridge arm of phase m of the second inverter to conduct, and V4, V5, and V7 require the upper bridge arm of phase m of the zero-th inverter to conduct, as shown in the following formula: t 1m = D 7m ; t 2m = D 4m + D 7m ; t 0m = D 4m + D 5m + D 7m 5) When the reference phase voltage vector of phase m is located in sector 5, V6 and V7 require the upper bridge arm of phase m of the first inverter to conduct, V7 requires the upper bridge arm of phase m of the second inverter to conduct, and V5, V6, and V7 require the upper bridge arm of phase m of the zero-th inverter to conduct, as shown in the following formula: t 1m = D 6m + D 7m ; t 2m = D 7m ; t 0m = D 5m + D 6m + D 7m 6) When the reference phase voltage vector of phase m is located in sector 6, V1, V6, and V7 require the upper bridge arm of phase m of the first inverter to conduct, V7 requires the upper bridge arm of phase m of the second inverter to conduct, and V6 and V7 require the upper bridge arm of phase m of the zero-th inverter to conduct, as shown in the following formula: t 1m = D 1m + D 6m + D 7m ; t 2m = D 7m ; t 0m = D 6m + D 7m According to the above results, drive signals are generated to control the switching states of the inverter bridge arms, thereby controlling the motor terminal voltage; meanwhile, the operating state of the motor at the (k + 1)-th moment is sampled, and the next control cycle is entered.

2. The three-vector predictive current control method for a semi-centralized open-winding permanent magnet synchronous motor system according to claim 1, wherein The method includes sampling the phase currents, rotor speeds, rotor positions of two motors, and the DC bus voltage data of the inverter, and then calculating the durations of two basic effective phase voltage vectors and one basic zero voltage vector of each phase at the next moment.

3. A three-vector predictive current control method for a semi-centralized open-winding permanent magnet synchronous motor system according to claim 1, characterized in that The method includes calculating the optimal phase voltage vector at the next moment, generating control signals and sending them into the inverter to control the switching states of the inverter bridge arms, forming a closed-loop control system of inverter - motor - control unit - inverter.

4. A three-vector predictive current control system based on a semi-centralized open-winding permanent magnet synchronous motor system, characterized in that, The system is used to implement the three-vector predictive current control method for a semi-centralized open-winding permanent magnet synchronous motor system according to any one of claims 1 - 3. The system includes a multiplexed inverter, and the multiplexed inverter adopts a connection method with a common DC bus.

5. A three-vector predictive current control system for a semi-centralized open-winding permanent magnet synchronous motor system according to claim 4, characterized in that, The system includes two three-phase open-winding permanent magnet synchronous motors, three two-level voltage source inverters, and a predictive current control unit. The three inverters are connected in a common DC bus manner. Each open-winding motor is powered from both the left and right ends simultaneously. One independent inverter is used for the left end of one motor and the right end of the other motor, and a multiplexed inverter is shared by the ends of the two motors that do not use independent inverters.

6. A three-vector predictive current control system for a semi-centralized open-winding permanent magnet synchronous motor system according to claim 5, characterized in that The control system samples the DC bus voltage, the three-phase currents of the permanent magnet synchronous motor, the rotor position angle, and the mechanical rotational angular velocity; then predicts the currents in the next state; and calculates the reference value of the state voltage at the next moment based on the deadbeat principle. A two-dimensional plane space based on phase voltage vectors is constructed to quickly confirm the sector and calculate the durations of two adjacent basic effective phase voltage vectors and a zero-phase voltage vector.

7. A storage medium, characterized in that, The storage medium records the three-vector predictive current control system for the semi-centralized open-winding permanent magnet synchronous motor system according to claim 6.

8. A computing execution device, characterized in that, The calculation execution device is used to calculate the three-vector predictive current control system for the semi-centralized open-winding permanent magnet synchronous motor system according to claim 6.

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