A five-phase half-bridge current source inverter low-harmonic vector sequence generation method

Abstract

The application discloses a five-phase half-bridge current source type inverter low-harmonic vector sequence generation method, belongs to the technical field of motor control, and aims at solving the problem of harmonic increase caused by the sudden change of phase voltage amplitude due to sector switching in the adjacent four-vector modulation strategy of the traditional five-phase half-bridge current source type inverter. The method comprises the following steps: S1, obtaining motor operation state information and determining a reference current vector in a stationary coordinate system; S2, judging a sector where the reference current vector is located; S3, selecting a basic non-zero vector corresponding to the sector and a zero vector for supplementing a switching period; S4, calculating the action time of each non-zero basic vector in the sector; S5, calculating the action time of the zero vector; S6, according to the parity of the sector number, dividing the sector into an odd sector and an even sector, and adopting different vector action sequences for the odd sector and the even sector; and S7, performing pulse width modulation according to the vector action sequence generated in step S6 to drive the five-phase motor to operate.

Description

Technical Field

[0001] This invention relates to the field of motor control technology, specifically to a method for generating low-harmonic vector sequences for a five-phase half-bridge current source inverter. Background Technology

[0002] As a core device for energy conversion and power transmission, motor systems are widely used in industrial manufacturing, transportation, new energy power generation, and smart homes. Their performance directly affects the operating efficiency and reliability of equipment. With the continuous expansion of application scenarios, motor systems face challenges such as increased power levels, harsh operating environments, and high reliability requirements. Traditional three-phase motor systems are gradually showing limitations in high-power, high-reliability applications. For example, under high-power conditions, capacity needs to be increased through series and parallel connections of components, leading to increased system complexity and decreased stability. Simultaneously, torque ripple and harmonic interference are significant, affecting operational stability. Furthermore, their fault tolerance is weak; single-phase failures can easily cause system shutdowns, making it difficult to meet the high reliability requirements of critical fields such as aerospace and marine propulsion.

[0003] In recent years, with the mature application of wide-bandgap semiconductor materials such as silicon carbide (SiC), current source inverters (CSI) have regained widespread attention due to their excellent current limiting capability and short-circuit protection performance. Multiphase current source inverters achieve power redundancy by increasing the number of phases, significantly improving the system's fault tolerance. At the same time, they can output near-sinusoidal current, effectively reducing motor harmonic losses and torque ripple, making them suitable for high-power, high-reliability applications.

[0004] exist Figure 1 In the five-phase half-bridge current source inverter shown, the adjacent four-vector modulation strategy is a commonly used space vector modulation method. This strategy divides the vector space into 10 sectors, each using a fixed vector action sequence to achieve tracking control of the fundamental and harmonic currents. However, this strategy suffers from abrupt changes in phase voltage amplitude during sector switching. Analysis shows that this is due to the inconsistent equivalent switching frequencies of the phase arms in different sectors, leading to changes in the voltage modulation frequency and causing local spikes and increased ripple in the voltage waveform. This voltage abrupt change not only increases the voltage stress on power devices and motor windings, accelerating insulation aging, but also introduces additional high-order harmonics, causing electromagnetic interference and affecting system performance and reliability.

[0005] Therefore, how to suppress phase voltage surges and reduce harmonic content during sector switching while maintaining current tracking performance has become a pressing technical problem to be solved in the modulation strategy of five-phase current source inverters. Summary of the Invention

[0006] To address the technical problem of increased harmonics caused by sudden changes in phase voltage amplitude due to sector switching in traditional five-phase half-bridge current source inverters using adjacent four-vector modulation strategies, this invention provides a method for generating low-harmonic vector sequences for five-phase half-bridge current source inverters.

[0007] The present invention discloses a method for generating a low-harmonic vector sequence for a five-phase half-bridge current source inverter, the method comprising the following steps:

[0008] S1. Obtain motor operating status information and determine the reference current vector in the stationary coordinate system;

[0009] S2. Based on the reference current vector and the sector division method of the five-phase current source inverter, determine the sector where the reference current vector is located.

[0010] S3. Based on the sector judgment result, select the non-zero basic vector of the corresponding sector and the zero vector of the supplementary switching cycle;

[0011] S4. Calculate the duration of action of each non-zero fundamental vector in the sector;

[0012] S5. Calculate the zero vector action time based on the switching period and the non-zero basic vector action time;

[0013] S6. Based on the parity of the sector number determined in step S2, divide the sector into odd sector and even sector, and apply different vector action sequences to the odd sector and even sector respectively.

[0014] S7. Perform pulse width modulation based on the vector action sequence generated in step S6 to drive the five-phase motor.

[0015] Preferably, step S1 specifically involves: acquiring motor phase current signals, rotor position signals, and speed signals; obtaining a reference current in the dq coordinate system through the control system; and then converting it into... The reference current component in the stationary coordinate system is used to determine the amplitude and phase of the reference current vector in the stationary coordinate system.

[0016] Preferably, in step S3, based on the sector determination result, four non-zero basic vectors corresponding to the sector are selected in the fundamental vector space and the third harmonic vector space, respectively. The four non-zero basic vectors include two adjacent large vectors and two adjacent small vectors, and a zero vector is selected to supplement the switching cycle.

[0017] Preferably, in step S4, the duration of action of each non-zero fundamental vector in the sector is calculated using the following formula:

[0018] ;

[0019] In the formula, For switching cycles;

[0020] , , , For the first The action times of the four basic vectors of the sector are respectively the first... Large vector at sector starting boundary Action time, first Large vector at sector end boundary Action time, first Small vector of sector starting boundary Action time, first Small vector at the end of sector boundary Duration of action;

[0021] These are the magnitudes of the fundamental reference current vector and the third harmonic reference current vector, respectively.

[0022] These are the fundamental reference current vector phase and the third harmonic reference current vector phase, respectively.

[0023] The first The start and end boundaries of a sector;

[0024] ;

[0025] These represent the large vector amplitude and the small vector amplitude, respectively.

[0026] Preferably, in step S5, the zero vector action time The calculation formula is:

[0027] .

[0028] Preferably, step S6 specifically comprises:

[0029] Both the fundamental frequency vector space and the third harmonic frequency vector space are divided into 10 sectors. These 10 sectors are further divided into odd and even sectors based on the parity of their sector numbers. Specifically, the sector numbers determined in step S2... When the number is odd, it corresponds to an odd sector. When the number is even, it corresponds to an even sector;

[0030] The first vector action sequence is used in odd sectors, and the second vector action sequence is used in even sectors. The second vector action sequence is generated by replacing the original non-zero basic vectors with vectors that are symmetrical about the sector midline.

[0031] Preferably,

[0032] The first vector action sequence is ;

[0033] The second vector action sequence is ;

[0034] In the formula, It is a zero vector.

[0035] Preferably, when the sum of the action times of the four non-zero basic vectors and the zero vector selected in step S3 is greater than the switching period, an overmodulation strategy or an adjustment of the vector combination is adopted to correct the vector action time.

[0036] Preferably, in the same switching cycle, the zero vector is distributed in the middle period of the switching cycle, or it is divided into two equal segments and distributed in the beginning and end periods of the switching cycle, respectively.

[0037] The beneficial effects of this invention are:

[0038] 1. Effectively suppresses phase voltage spikes during sector switching. This invention solves the problem of phase voltage amplitude spikes caused by inconsistent equivalent switching frequencies of each phase arm during sector switching in traditional adjacent four-vector modulation strategies by dividing the vector space into odd and even sectors and employing differentiated vector action sequences in different sectors. Simulation results show that after adopting the method of this invention, local spikes in the phase voltage waveform disappear, and voltage ripple is significantly reduced.

[0039] 2. Significantly reduces output voltage harmonic content. Because phase voltage surges are effectively suppressed, the high-order harmonics generated by voltage surges are greatly weakened, the phase voltage distortion rate is reduced, and the output waveform is closer to a sine wave, reducing harmonic losses to the motor windings and load.

[0040] 3. Reduce voltage stress on power devices and motors. Suppressing phase voltage surges avoids the direct impact of voltage transients on power switching devices and motor windings, reducing the voltage stress on the devices, helping to alleviate the problem of motor winding insulation aging, and extending the service life of power modules and motors.

[0041] 4. Reduced electromagnetic interference and improved system compatibility. The reduction of higher harmonics effectively reduces electromagnetic interference to peripheral equipment and the power grid during inverter operation, making the system more likely to meet electromagnetic compatibility standards and suitable for applications with strict electromagnetic environment requirements.

[0042] 5. Maintaining the original current tracking performance. This invention only adjusts the vector action sequence, without changing the selection rules of the basic vector or the calculation method of the action time. Therefore, the tracking capability of the fundamental current and harmonic current remains consistent with the traditional method, the motor phase current waveform remains smooth, and the dynamic performance of the system is unaffected.

[0043] 6. The implementation method is simple and easy to implement in engineering. This invention only adjusts the vector action order according to the parity of the sector based on the existing modulation strategy, without increasing the additional hardware cost. The algorithm has low complexity and is easy to implement in existing digital controllers, and has good engineering promotion value.

[0044] In summary, this invention effectively solves the problems of phase voltage abrupt changes and increased harmonics caused by sector switching while maintaining the original current tracking performance. It significantly improves the output waveform quality and operational reliability of the inverter system, and is particularly suitable for applications with high requirements for voltage quality and system reliability, such as aerospace, ship propulsion, and new energy power generation. Attached Figure Description

[0045] Figure 1 This is a topology diagram of a five-phase half-bridge current source inverter.

[0046] Figure 2 This is a spatial partitioning diagram of the fundamental wave vector using a traditional adjacent four-vector modulation strategy;

[0047] Figure 3 This is a diagram showing the harmonic vector space partitioning using a traditional adjacent four-vector modulation strategy.

[0048] Figure 4 This is a sequence diagram of the vector action of the traditional adjacent four-vector modulation strategy in sector 1.

[0049] Figure 5 The simulated phase voltage waveforms for a traditional adjacent four-vector modulation strategy are shown.

[0050] Figure 6 This is a sequence diagram of the vector action of the traditional adjacent four-vector modulation strategy in sector 2.

[0051] Figure 7 The waveform of the phase voltage at the switching point between sector 1 and sector 2 is shown for the traditional adjacent four-vector modulation strategy.

[0052] Figure 8 To Figure 4 The sequence diagram shown is the sequence of the vector action sequence in the first sector after zero-crossing correction.

[0053] Figure 9 To Figure 6 The sequence diagram shown is the sequence of the second sector vector action sequence after zero-crossing correction;

[0054] Figure 10 This is a vector action sequence diagram of the few harmonic vector sequence generation method described in this invention in the second sector;

[0055] Figure 11 This is a vector action sequence diagram after zero-crossing correction in the second sector of the low-harmonic vector sequence generation method described in this invention;

[0056] Figure 12 The image shows the simulated phase voltage waveform of the low harmonic vector sequence generation method described in this invention.

[0057] Figure 13 This is a flowchart of the method for generating few harmonic vector sequences according to the present invention. Detailed Implementation

[0058] 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.

[0059] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other.

[0060] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, but this is not intended to limit the scope of the invention.

[0061] Specific Implementation Method 1: The following is combined with... Figures 1 to 13 This embodiment describes a method for generating a low-harmonic vector sequence for a five-phase half-bridge current source inverter. The method includes the following steps:

[0062] S1. Obtain motor operating status information and determine the reference current vector in the stationary coordinate system;

[0063] S2. Based on the reference current vector and the sector division method of the five-phase current source inverter, determine the sector where the reference current vector is located.

[0064] S3. Based on the sector judgment result, select the non-zero basic vector of the corresponding sector and the zero vector of the supplementary switching cycle;

[0065] S4. Calculate the duration of action of each non-zero fundamental vector in the sector;

[0066] S5. Calculate the zero vector action time based on the switching period and the non-zero basic vector action time;

[0067] S6. Divide the sector into odd sector and even sector according to the sector number, and use different vector action sequences in odd sector and even sector respectively;

[0068] S7. Perform pulse width modulation based on the final generated vector action sequence to drive the five-phase motor.

[0069] The five-phase half-bridge current source inverter topology involved in this embodiment is as follows: Figure 1 As shown. This inverter includes an inverter DC current source. Bus inductance It consists of five independent half-bridge power arms. Each half-bridge module's upper and lower arms are composed of a fully controlled power switch and a diode connected in forward series. The fully controlled power switches for the five arms are as follows: , , , , The upper bridge arm is The lower bridge arm is The midpoint of the series connection between the upper and lower bridge arms serves as the AC output terminal for that phase. The output terminals of the five bridge arms are connected one-to-one with the stator windings of each phase of the five-phase permanent magnet synchronous motor (PMSM), and a filter capacitor is connected in parallel on the motor side. Used to absorb switching harmonics.

[0070] For a current-source inverter, at any given moment, only one upper arm and one lower arm of the inverter's five arms are conducting. Therefore, there are a total of 25 switching states, corresponding to 25 current vectors, including 10 large vectors, 10 small vectors, and 5 zero vectors. The directions of the 10 large vectors and 10 small vectors coincide, and the magnitude of the large vectors is... and small vector magnitude With bus current The relationships are as follows:

[0071] ;

[0072] Step S1: Obtain motor operating status information and determine the reference current vector in the stationary coordinate system.

[0073] The control system acquires the phase current, rotor position, and speed signals of the motor in real time. Through coordinate transformation, the acquired three-phase currents are converted to the dq rotating coordinate system and compared with a given reference current. The reference current in the dq coordinate system is then obtained through a current regulator. Subsequently, the reference current in the dq coordinate system is converted to... The reference current component in the stationary coordinate system is used to determine the amplitude of the reference current vector in the stationary coordinate system. With phase Once the amplitude and phase are determined, the reference current vector is also determined.

[0074] Step S2: Determine the sector where the reference current vector is located.

[0075] Based on the reference current vector amplitude obtained in step S1 With phase Based on the sector division method of the five-phase current source inverter, determine the sector number where the reference current vector is located. The sector division of the fundamental vector space is as follows: Figure 2 As shown, the sector division of the harmonic vector space is as follows: Figure 3 As shown. Both spaces are divided into 10 sectors by fundamental vectors, with each sector corresponding to a set of adjacent fundamental vectors. In the fundamental space, the fundamental large vector is defined. The left side is sector 1, and the number of sectors increases sequentially in a counter-clockwise direction up to sector 10.

[0076] Step S3: Select the non-zero fundamental vector and zero vector of the corresponding sector.

[0077] Based on sector judgment results Four non-zero fundamental vectors are selected for corresponding sectors in the fundamental wave vector space and the third harmonic wave vector space, respectively. These four non-zero fundamental vectors include two adjacent large vectors and two adjacent small vectors: the large vector at the sector's initial boundary. Large vector at the end of sector boundary small vector at the starting boundary of the sector (and (Same direction), small vector at the end of the sector boundary (and (Same direction)

[0078] Simultaneously select the zero vector Used to supplement switching cycles.

[0079] Step S4: Calculate the duration of action of each non-zero fundamental vector.

[0080] Combined with the reference current vector magnitude With phase and switching cycle Calculate the duration of action of each non-zero fundamental vector in the sector. The fundamental target vector is located at the [missing information - likely a specific location or position]. The formula for calculating the duration of action of the four basic vectors in a sector is as follows:

[0081] ;

[0082] , , , For the first The action times of the four basic vectors of the sector are respectively the first... Large vector at sector starting boundary Action time, first Large vector at sector end boundary Action time, first Small vector of sector starting boundary Action time, first Small vector at the end of sector boundary Duration of action;

[0083] The first The start and end boundaries of a sector;

[0084] ;

[0085] These represent the large vector amplitude and the small vector amplitude, respectively.

[0086] Taking the fundamental target vector located in sector 1 as an example, the corresponding four basic vectors include two adjacent large vectors. , and 2 adjacent small vectors , The boundary angles of the first sector are respectively and Substituting into the above formula, we can obtain the duration of action of the four basic vectors.

[0087] Step S5: Calculate the zero vector action time.

[0088] According to the switching cycle Calculate the zero vector's interaction time with the four non-zero fundamental vectors. :

[0089] ;

[0090] when When the total duration of the selected basic vectors exceeds the switching cycle, an overmodulation strategy or adjustment of the vector combination is required to correct the vector duration and ensure that the total duration equals the switching cycle.

[0091] Step S6: Use different vector action sequences based on the parity of the sector.

[0092] First, we introduce the traditional modulation strategy, taking the vector action sequence of sector 1 (odd sector) as an example, as follows: Figure 4 As shown, the vector action sequence, taking the second sector (even sector) as an example, is as follows: Figure 6 As shown.

[0093] In the mirror-symmetric switching mode, the zero vector is evenly distributed on both sides of the switching cycle. In the diagram, the gray area represents the corresponding switch in the on state during the corresponding time period, and the white area represents the off state. The sequence for the first sector (n=1) is as follows: ,in, For the two adjacent large vectors in sector 1, For the two adjacent small vectors in sector 1, the relative order of vector action remains unchanged in the remaining 9 sectors. The simulation results of the phase current waveform are as follows: Figure 5 As shown, under this modulation strategy, the phase current waveform of the motor is smooth, but during sector switching, the phase voltage of the motor will change abruptly, resulting in local spikes in the voltage waveform and increased ripple. From Figure 4 It can be seen that in the first sector, except for the zero vector, the vector corresponding to phase A is... Apply twice (the application time is on both sides) The vector corresponding to phase B Apply twice (the application time is on both sides) and The vector corresponding to phase C) One application (within the middle of the application time) The vector corresponding to phase D One application (within the middle of the application time) and The vector corresponding to phase E) Apply twice (the application time is on both sides) and ).

[0094] The sequence of sector 2 (n=2) is as follows ,in, For the two adjacent large vectors in sector 2, For two adjacent small vectors in sector 2, from Figure 6 The vector action sequence in sector 2 shows that the number of times the five-phase vectors act are 1, 1, 2, 2, and 2, respectively. When switching between sectors 1 and 2, the waveforms of the five-phase voltages are as follows: Figure 7 In the selected section, although the vector corresponding to phase E has two application times in both sectors 1 and 2 in the above analysis, it can be seen from the figure that the phase E voltage still undergoes a sudden change. The reason for this phenomenon is that the switching point between sectors 1 and 2 coincides with the zero-crossing point of phase A voltage. Therefore, the vector application time corresponding to phase A is approximately 0, requiring a recalculation of the equivalent frequency of each phase arm. The corrected vector application sequences for sectors 1 and 2 are shown below. Figure 8 and Figure 9As shown. The number of times the five-phase vector is applied in the first and second sectors after correction are 0, 2, 1, 1, 2 and 0, 1, 2, 2, 1 respectively. It can be seen that the voltage of each phase will change abruptly when the sector is switched.

[0095] To address the problems of traditional modulation strategies, this invention employs a few harmonic vector sequence generation method as follows:

[0096] Both the fundamental frequency vector space and the third harmonic frequency vector space are divided into 10 sectors. Based on the parity of the sector numbers, these 10 sectors are further divided into 5 odd sectors and 5 even sectors: odd sectors... Even sector .

[0097] Different vector action sequences are used in odd and even sectors to suppress phase voltage abrupt changes during sector switching. The first vector action sequence (the same as in the traditional method) is used in odd sectors, and the second vector action sequence is used in even sectors. The second vector action sequence is generated by replacing the original non-zero basic vector with a vector symmetrical along the sector centerline.

[0098] When the sector number determined in step S2 When the number is odd, use the first vector action sequence. Use the second vector action sequence when the number is even.

[0099] When the sector number determined in step S2 When the number is odd, taking sector 1 as an example, the order of action of the four fundamental vectors and the zero vector in that sector remains unchanged. .

[0100] When the sector number determined in step S2 When the number is even, taking sector 2 as an example, the order of action of the four basic vectors and the zero vector in that sector is adjusted so that the zero vector is still evenly distributed on both sides of the switching cycle. The optimized vector action sequence is as follows: Figure 10 As shown.

[0101] Within the same switching cycle, the zero vector can be distributed in the middle of the switching cycle, or it can be divided into two equal segments and distributed at the beginning and end of the switching cycle, respectively. This embodiment uses the method of dividing the zero vector into two equal segments and distributing them on both sides of the switching cycle to reduce output voltage harmonics.

[0102] exist Figure 6 and Figure 10 Using the same analytical method, it can be found that after using the few harmonic vector sequence generation method, the number of times the five-phase vector acts in the first and second sectors is 2, 2, 1, 1, 2; Figure 8 and Figure 11 Using the same analysis method, it can be found that after using the few harmonic vector sequence generation method and performing zero-crossing correction, the number of times the five-phase vectors are applied in the first and second sectors are 0, 2, 1, 1, and 2. Therefore, the equivalent frequency of each phase arm does not change before and after sector switching, effectively avoiding the problem of sudden phase voltage changes during sector switching. The simulation results of the phase current waveform using the few harmonic vector sequence generation method are as follows: Figure 12 As shown, the phase current waveform of the motor is smooth and consistent with... Figure 5 In contrast, during sector switching, the voltage surge of the original motor phase is suppressed, and the local spikes in the voltage waveform disappear, proving the effectiveness of the low harmonic vector sequence generation method described in this invention.

[0103] Step S7: Perform pulse width modulation to drive the five-phase motor.

[0104] Based on the vector action sequence generated in step S6, and combined with the action time of each vector, drive pulses for each power switching device are generated. The drive circuit controls the on and off of each switching transistor in the inverter to drive the five-phase motor.

[0105] Zero-crossing correction instructions:

[0106] At the sector boundary, when the voltage of a certain phase approaches the zero-crossing point, the vector action time corresponding to that phase approaches zero, and zero-crossing correction is required. Figure 8 To Figure 4 The diagram shown is a sequence diagram of the vector action sequence in sector 1 after zero-crossing correction. Figure 9 To Figure 6 The sequence diagram shown is the sequence diagram after zero-crossing correction of the vector action sequence of the second sector. Figure 11 This is a sequence diagram of the vector action after zero-crossing correction in the second sector using the method of the present invention.

[0107] Comparison of implementation results:

[0108] Figure 5 The figure shows the simulated phase voltage waveform of the traditional adjacent four-vector modulation strategy. It can be seen that there are obvious voltage spikes and increased ripple at the sector switching points. Figure 7 The phase voltage waveform at the switching point between sector 1 and sector 2 for the traditional modulation strategy clearly shows the voltage change phenomenon.

[0109] Figure 12 The image shows the simulated phase voltage waveform of the low-harmonic vector sequence generation method described in this invention. Compared with traditional methods, the phase voltage abrupt changes during sector switching are effectively suppressed, local spikes in the voltage waveform disappear, and voltage ripple is significantly reduced, demonstrating the effectiveness of this invention.

[0110] While the invention has been described herein with reference to specific embodiments, it should be understood that these embodiments are merely examples of the principles and applications of the invention. Therefore, it should be understood that many modifications can be made to the exemplary embodiments, and other arrangements can be designed without departing from the spirit and scope of the invention as defined by the appended claims. It should be understood that different dependent claims and features described herein can be combined in ways different from those described in the original claims. It is also understood that features described in conjunction with individual embodiments can be used in other described embodiments.

Claims

1. A method for generating a low-harmonic vector sequence for a five-phase half-bridge current source inverter, characterized in that, The method includes the following steps: S1. Obtain motor operating status information and determine the reference current vector in the stationary coordinate system; S2. Based on the reference current vector and the sector division method of the five-phase current source inverter, determine the sector where the reference current vector is located. S3. Based on the sector judgment result, select the non-zero basic vector of the corresponding sector and the zero vector of the supplementary switching cycle; S4. Calculate the duration of action of each non-zero fundamental vector in the sector; S5. Calculate the zero vector action time based on the switching period and the non-zero basic vector action time; S6. Based on the parity of the sector number determined in step S2, divide the sector into odd sector and even sector, and apply different vector action sequences to the odd sector and even sector respectively. S7. Perform pulse width modulation based on the vector action sequence generated in step S6 to drive the five-phase motor to run; In step S3, based on the sector determination result, four non-zero basic vectors corresponding to the sector are selected in the fundamental vector space and the third harmonic vector space respectively. The four non-zero basic vectors include two adjacent large vectors and two adjacent small vectors, and a zero vector is selected to supplement the switching cycle. In step S4, the duration of action of each non-zero fundamental vector in the sector is calculated using the following formula: In the formula, For switching cycles; , , , For the first The action times of the four basic vectors of the sector are respectively the first... Large vector at sector starting boundary Action time, first Large vector at sector end boundary Action time, first Small vector of sector starting boundary Action time, first Small vector at the end of sector boundary Duration of action; These are the magnitudes of the fundamental reference current vector and the third harmonic reference current vector, respectively. These are the fundamental reference current vector phase and the third harmonic reference current vector phase, respectively. The first The start and end boundaries of a sector; ； These represent the large vector magnitude and the small vector magnitude, respectively. In step S5, the zero vector action time The calculation formula is: ； Step S6 specifically involves: Both the fundamental frequency vector space and the third harmonic frequency vector space are divided into 10 sectors. These 10 sectors are further divided into odd and even sectors based on the parity of their sector numbers. Specifically, the sector numbers determined in step S2... When the number is odd, it corresponds to an odd sector. When the number is even, it corresponds to an even sector; The first vector action sequence is used in odd sectors, and the second vector action sequence is used in even sectors. The second vector action sequence is generated by replacing the original non-zero basic vectors with vectors that are symmetrical along the midline of the sector. The first vector action sequence is ; The second vector action sequence is ; In the formula, It is a zero vector.

2. The method for generating a low-harmonic vector sequence for a five-phase half-bridge current source inverter according to claim 1, characterized in that, Step S1 specifically involves: acquiring motor phase current signals, rotor position signals, and speed signals; obtaining the reference current in the dq coordinate system through the control system; and then converting it into... The reference current component in the stationary coordinate system is used to determine the amplitude and phase of the reference current vector in the stationary coordinate system.

3. The method for generating a low-harmonic vector sequence for a five-phase half-bridge current source inverter according to claim 1, characterized in that, When the sum of the action times of the four non-zero basic vectors and the zero vector selected in step S3 is greater than the switching period, an overmodulation strategy or an adjustment of the vector combination is adopted to correct the vector action time.

4. The method for generating a low-harmonic vector sequence for a five-phase half-bridge current source inverter according to claim 1, characterized in that, In the same switching cycle, the zero vector is distributed in the middle of the switching cycle, or it is divided into two equal segments, distributed at the beginning and end of the switching cycle respectively.

Images