Double random control method and system combining random switching sequence and random carrier frequency of double three-phase motor

Abstract

The invention provides a dual-random control method and system combining a dual-three-phase motor random switching sequence and a random carrier frequency. When a dual three-phase motor adopts space vector pulse width modulation, concentrated high-frequency harmonic waves exist at the switching frequency and the integral multiple of the switching frequency of phase current, and vibration noise is caused. The invention provides a double-random control method for a double-three-phase motor to suppress high-frequency harmonic waves, two different switch sequences are designed in each sector, and one switch sequence is selected through random numbers in each carrier period. And in the aspect of random carrier frequency, random number constrained variable delay control is provided, so that the carrier period is randomized, the high-frequency harmonic amplitude of the dual three-phase motor is finally reduced, and the vibration and noise of the motor are suppressed.

Description

Technical Field

[0001] This invention relates to the field of multiphase motors, the field of vector control, and the field of spread spectrum modulation. Specifically, it relates to a control method and system for suppressing high-frequency harmonics in a dual three-phase motor by combining a random switching sequence and a random carrier frequency. Background Technology

[0002] Multiphase motor drive systems, with their high power output, multiple degrees of control freedom, and excellent fault tolerance, have shown broad application prospects in demanding fields such as aerospace and ship propulsion. Among them, the double three-phase motor, which uses two sets of three-phase windings with a spatial phase difference of 30°, has become a key research direction that combines performance and practical value due to its higher torque density and lower operating losses.

[0003] However, when the motor is driven by a six-phase voltage source inverter, the switching action of the power devices generates concentrated high-frequency harmonic currents near the switching frequency. These harmonics can cause significant high-frequency vibrations in the motor, threatening not only the stability of the control system but also potentially causing cumulative damage to the motor's structure. This is a critical problem that urgently needs to be solved in practical applications.

[0004] There are two main categories of methods for suppressing high-frequency harmonics: hardware and software. Hardware methods increase system size and cost. Software methods mainly include random carrier frequency, random zero vector, and changing the switching sequence. Random carrier frequency, by randomly changing the carrier period, diffuses the high-order harmonic energy concentrated at the switching frequency to a wider frequency band, thereby suppressing high-frequency vibrations. The sampling frequency is usually consistent with the carrier frequency; changes in the carrier frequency inevitably lead to changes in the sampling frequency. Changes in the sampling period can disrupt the original matching of traditional PI controller parameters, thus affecting system stability and introducing larger current harmonics and torque ripple. The random zero vector method disperses harmonics by randomly allocating the duration of the middle and side zero vectors. However, in the high modulation ratio operating region (to obtain high voltage utilization), the zero vector duration itself is short, and its room for random adjustment is very small; therefore, the suppression effect of this method is limited under this condition. The method of changing the switching sequence keeps the control period fixed and achieves harmonic shaping by selectively adjusting the number of switches and the sequence of actions of each phase within a cycle. This method can directly eliminate harmonics at odd-numbered harmonics of the switching frequency, but at the cost of increasing harmonics at even-numbered harmonics and leading to an increase in the number of switching operations. By iteratively optimizing and selecting the sequence that minimizes current ripple, current quality can be improved to some extent, and harmonic energy can be diffused, thus suppressing vibration. However, its main drawback is that it significantly increases switching losses and reduces system efficiency. Furthermore, this algorithm is relatively complex to implement and requires high hardware computing power, making it generally difficult to apply to high control frequencies. Summary of the Invention

[0005] This invention designs two different switching sequences for each sector, and randomly selects one of these sequences for pulse output during each control cycle. While maintaining a fixed control frequency and a constant number of switching actions within one electrical cycle, the amplitude of high-frequency harmonics is reduced. Then, an improved variable-delay random carrier frequency control is proposed, which allows for randomization of the carrier frequency while keeping the sampling frequency fixed. By combining random switching sequences and random carrier frequencies, high-frequency harmonics in dual three-phase motors are significantly suppressed.

[0006] To achieve the above-mentioned objectives, the present invention adopts the following technical solution: A dual-random control method combining random switching sequences and random carrier frequencies for a dual three-phase motor includes the following steps: Based on the 12 large vectors of the fundamental wave space of the dual three-phase motor, the fundamental wave space is divided into 12 sectors, and two different switching sequences are designed for each sector. By using a PI controller and coordinate transformation, the sampled values ​​and position information of the two-phase three-phase currents are converted into components of the reference voltage vector in the fundamental and harmonic spaces. Based on the maximum four-vector space vector pulse width modulation algorithm, the sector where the reference voltage vector is located is determined, and the duration of each voltage vector within one carrier cycle is calculated. Random numbers are generated using a random number generation method. Based on the random numbers, one of the two switch sequences corresponding to the sector is selected, and the action time of each vector is allocated. An improved variable delay control method based on random number constraints is adopted to make the carrier period vary randomly, wherein the random number is constrained to avoid clamping the carrier period to the minimum limit value; The selected switching sequence modulation signal is combined with the random carrier frequency modulation signal to generate a pulse width modulation signal, which controls the inverter output to the dual three-phase motor.

[0007] Furthermore, the random number generation method is a linear congruential method, and the random number value range is [0,1].

[0008] Furthermore, in the improved variable delay control, the carrier period is: In the formula, T s ( n ) indicates the generated n One carrier cycle, Δ t ( n ) and Δ t ( n -1) indicates the first n as well as n -1 carrier cycle delay time; T samp The sampling period;R vtd A random number uniformly distributed in [0,1]. R vtd It is also generated by the linear congruential method, and the range of the carrier period is... T c_min to 2 T samp ; T c_min This is the minimum carrier period limit value. If the minimum carrier period limit value is set too small, it will cause large switching losses. If it is set too large, it will affect the high-frequency harmonic diffusion effect.

[0009] Furthermore, the minimum carrier period limit is typically set to half the sampling period, i.e., 0.5. T samp .

[0010] Furthermore, the random number constraint process includes: Calculate the difference between the current random number and the random number from the previous time step. i ; like i If the value is less than 0.5, then output the current random number. like i If ≥0.5, then output 1− R ( n ), R ( n ) is the random number at the current time, and the current random number is updated to this value.

[0011] Furthermore, the switching sequence includes four effective voltage vectors and a zero vector, and the number of switching actions differs between the two switching sequences for each sector.

[0012] Furthermore, the method achieves high-frequency harmonic suppression while keeping the total number of switching actions within one electrical cycle constant.

[0013] Furthermore, the method is applicable to vector control systems for dual three-phase motors without requiring changes to the hardware structure.

[0014] The present invention provides a dual three-phase motor control system, comprising a processor and a memory, wherein the memory stores a computer program, and the processor executes the program to implement the aforementioned dual random control method.

[0015] In contrast to the shortcomings of existing random modulation methods pointed out in the background art, the present invention addresses or circumvents these shortcomings through the following design: To address the issues of PI controller parameter mismatch and system stability caused by random carrier frequencies, this invention proposes an improved variable delay control method based on random number constraints. This method achieves randomization of the carrier period while maintaining a fixed sampling period. Because the sampling frequency is constant, the discretized parameters of the current loop and speed loop PI controllers do not need to be rematched with the carrier period adjustment, thus effectively maintaining the dynamic performance and stability of the control system while dispersing high-frequency harmonics.

[0016] To address the increased switching losses and algorithmic complexity caused by altering the switching sequence, this invention employs a random switching sequence strategy that ensures the total number of motor switching actions within one electrical cycle remains consistent with traditional fixed-sequence SVPWM. Simultaneously, by setting a reasonable lower limit constraint on the random carrier period, it avoids an abnormal increase in the average switching frequency due to an excessively short period. These two measures work together to achieve harmonic energy diffusion while keeping the additional increase in switching losses at a low level, and the algorithm is easily implemented in existing controllers.

[0017] The beneficial effects of this invention are: 1. This invention proposes random switch sequence modulation, which suppresses high-frequency harmonics of a dual three-phase motor by changing the number of switching actions within a carrier cycle, while the number of switching actions within a single electrical cycle does not increase.

[0018] 2. This invention proposes a random carrier frequency control based on improved variable delay. By using random number constraints, the traditional variable delay method is improved, thus avoiding the clamping problem that exists in the traditional variable delay method.

[0019] 3. This invention combines a random switching sequence with a random carrier frequency, which greatly suppresses the high-frequency harmonics of a dual three-phase motor, thereby suppressing the motor's vibration and noise.

[0020] 4. Randomization is achieved under a fixed carrier period, avoiding PI controller parameter mismatch issues caused by period variations and enhancing system robustness. By reasonably constraining the carrier period range, excessively high switching frequencies due to excessively small periods are avoided, thereby controlling switching losses while suppressing harmonics. The dual-randomization strategy (sequence + frequency) provides dual randomization dimensions without increasing hardware costs, making it suitable for various operating conditions.

[0021] 5. This method can be seamlessly integrated with existing SVPWM frameworks, facilitating implementation in existing motor control systems. The spectral spread effect can reduce electromagnetic interference at specific frequencies, improving system EMC performance. Attached Figure Description

[0022] Figure 1 A block diagram of a dual-random control method combining random switching sequences and random carrier frequencies for dual three-phase motors; Figure 2 The voltage vector diagrams for dual three-phase motors are shown below; (a) fundamental frequency space voltage vector diagram, (b) harmonic frequency space voltage vector diagram. Figure 3 The diagram shows two switching sequences for sector I; where (a) is switching sequence IA and (b) is switching sequence IB. Figure 4 The diagram shows two switching sequences for sector III; where (a) is switching sequence III-A and (b) is switching sequence III-B. Figure 5 To improve the timing diagram of variable delay control; Figure 6 To improve the constraint process of random numbers in variable delay control; Figure 7 The waveforms are: (a) the phase current waveform of the conventional control method, and (b) the phase current waveform of the present invention. Figure 8 High-frequency harmonic analysis of phase current; (a) High-frequency harmonics of phase current in conventional control method, (b) High-frequency harmonics of phase current in this invention.

[0023] Specific implementation method The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention.

[0024] Embodiments of the present invention are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0025] like Figure 1 As shown in the structural block diagram, this invention is a control method combining random switching sequences and random carrier frequencies for dual three-phase motors. It mainly includes random switching sequences and random carrier frequency modulation based on improved variable delay.

[0026] This invention uses a dual three-phase motor as the controlled object and performs high-frequency harmonic suppression control on it. The specific measures are as follows: Step 1: Divide the fundamental wave space into 12 sectors based on the 12 large vectors of the fundamental wave space of the dual three-phase motor, and design two different switching sequences for each of the 12 sectors using the corresponding maximum four vectors.

[0027] like Figure 2 As shown, the 12 major vectors in the fundamental space of a dual three-phase motor are as follows: u 44 , u 64 , u66 , u 26 , u 22 , u 32 , u 33 , u 13 , u 11 , u 51 , u 55 , u 45 These 12 vectors divide the entire fundamental plane into 12 sectors.

[0028] The first switching sequence I-A for sector I is: u 00 , u 44 , u 64 , u 45 , u 55 , u 55 , u 45 , u 64 , u 44 , u 00 The number of switching actions is 6. The second switching sequence I-B for sector I is: u 00 , u 44 , u 55 , u 45 , u 64 , u 64 , u 45 , u 55 , u 44 , u 00 The switch was activated 7 times.

[0029] The first switching sequence II-A of sector II is: u 00 , u 44 ,u 45 , u 64 , u 66 , u 66 , u 64 , u 45 , u 44 , u 00 The number of switching actions is 6. The second switching sequence II-B for sector II is: u 00 , u 44 , u 64 , u 66 , u 45 , u 45 , u 66 , u 64 , u 44 , u 00 The switch was activated 7 times.

[0030] The first switching sequence Ⅲ-A of sector Ⅲ is: u 00 , u 44 , u 64 , u 66 , u 26 , u 26 , u 66 , u 64 , u 44 , u 00 The number of switching actions is 5. The second switching sequence Ⅲ-B for sector Ⅲ is: u 00 , u 26 , u 66 , u 64 , u 44 ,u 44 , u 64 , u 66 , u 26 , u 00 The switch action was performed 6 times.

[0031] The first switching sequence IV-A for sector IV is: u 00 , u 22 , u 26 , u 66 , u 64 , u 64 , u 66 , u 26 , u 22 , u 00 The number of switching actions is 5. The second switching sequence IV-B for sector IV is: u 00 , u 64 , u 66 , u 26 , u 22 , u 22 , u 26 , u 66 , u 64 , u 00 The switch action was performed 6 times.

[0032] The first switching sequence V-A of sector V is: u 00 , u 22 , u 32 , u 26 , u 66 , u 66 , u 26 ,u 32 , u 22 , u 00 The number of switching actions is 6. The second switching sequence V-B for sector V is: u 00 , u 22 , u 66 , u 26 , u 32 , u 32 , u 26 , u 66 , u 22 , u 00 The switch was activated 7 times.

[0033] The first switching sequence VI-A for sector VI is: u 00 , u 22 , u 26 , u 32 , u 33 , u 33 , u 32 , u 26 , u 22 , u 00 The number of switching actions is 6. The second switching sequence VI-B for sector VI is: u 00 , u 22 , u 33 , u 32 , u 26 , u 26 , u 32 , u 33 , u 22 , u 00The switch was activated 7 times.

[0034] The first switching sequence VII-A for sector VII is: u 00 , u 22 , u 32 , u 33 , u 13 , u 13 , u 33 , u 32 , u 22 , u 00 The number of switching actions is 5. The second switching sequence VII-B for sector VII is: u 00 , u 13 , u 33 , u 32 , u 22 , u 22 , u 32 , u 33 , u 13 , u 00 The switch action was performed 6 times.

[0035] The first switching sequence VIII-A for sector VIII is: u 00 , u 11 , u 13 , u 33 , u 32 , u 32 , u 33 , u 13 , u 11 , u 00 The number of switching actions is 5. The second switching sequence VIII-B for sector VIII is: u 00 ,u 32 , u 33 , u 13 , u 11 , u 11 , u 13 , u 33 , u 32 , u 00 The switch action was performed 6 times.

[0036] The first switching sequence IX-A of sector IX is: u 00 , u 11 , u 51 , u 13 , u 33 , u 33 , u 13 , u 51 , u 11 , u 00 The number of switching actions is 6. The second switching sequence IX-B for sector IX is: u 00 , u 11 , u 33 , u 13 , u 51 , u 51 , u 13 , u 33 , u 11 , u 00 The switch was activated 7 times.

[0037] The first switching sequence X-A of sector X is: u 00 , u 11 , u 13 ,u 51 , u 55 , u 55 , u 51 , u 13 , u 11 , u 00 The number of switching actions is 6. The second switching sequence X-B for sector X is: u 00 , u 11 , u 55 , u 51 , u 13 , u 13 , u 51 , u 55 , u 11 , u 00 The switch was activated 7 times.

[0038] The first switching sequence XI-A of sector XI is: u 00 , u 11 , u 51 , u 55 , u 45 , u 45 , u 55 , u 51 , u 11 , u 00 The switching action occurs 5 times. The second switching sequence XI-B for sector XI is: u 00 , u 45 , u 55 , u 51 , u 11 , u 11 ,u 51 , u 55 , u 45 , u 00 The switch action was performed 6 times.

[0039] The first switching sequence XII-A of sector XII is: u 00 , u 44 , u 45 , u 55 , u 51 , u 51 , u 55 , u 45 , u 44 , u 00 The number of switching actions is 5. The second switching sequence XII-B for sector XII is: u 00 , u 51 , u 55 , u 45 , u 44 , u 44 , u 45 , u 55 , u 51 , u 00 The switch action was performed 6 times.

[0040] Among them, the two switching sequences in the first sector are as follows: Figure 3 As shown, the two switching sequences in the third sector are as follows: Figure 4 As shown.

[0041] Step 2: Through PI controller and coordinate transformation, the sampled values ​​and position information of the two three-phase phase currents are converted into the components of the reference voltage vector in the fundamental space and harmonic space.

[0042] Position information is obtained in the outer speed loop, and reference values ​​for the inner current loop are obtained through the speed loop PI controller; the current sampling values ​​of each phase are obtained in the inner current loop, and the current values ​​in the fundamental space and harmonic space are obtained through coordinate transformation, and then the reference voltage values ​​in the fundamental space and harmonic space are obtained through the PI controller of the inner current loop. u α This indicates that the reference voltage vector is in the fundamental space. a The components of the axis; u β This indicates that the reference voltage vector is in the fundamental space. b The components of the axis; u z1 This indicates the reference voltage vector in harmonic space. z Components of axis 1; u z2 This indicates the reference voltage vector in harmonic space. z Components of the two axes.

[0043] Step 3: The maximum four-vector space vector pulse width modulation algorithm can generate electromagnetic torque in the fundamental space while suppressing harmonic currents, and is widely used in dual and three-phase motors. Based on the maximum four-vector space vector pulse width modulation algorithm, sector determination is performed, and the voltage vector action time is calculated.

[0044] Based on the sector where the reference voltage vector is located in the fundamental frequency space, select the maximum four vectors corresponding to that sector, and calculate the duration of the maximum four vectors within one carrier period. T 1. T 2. T 3. T 4, and the duration of action of the zero vector. T 00 .

[0045] Based on the sector where the reference voltage vector is located in the fundamental frequency space, select the maximum four vectors corresponding to that sector. Then, calculate the duration of the maximum four vectors within one carrier cycle. T 1. T 2. T 3. T 4, and the duration of action of the zero vector. T 00 This ensures that the voltage vector acting within one carrier cycle is consistent with the reference voltage vector in both the fundamental and harmonic spaces. The calculation of the duration of the maximum four vectors can be expressed as: In the formula, T y ( y =1,2,3,4) represents the first... y The duration of action of a voltage vector within one carrier cycle; U xy ( x= α , β , z 1, z 2) indicates the first y A voltage vector in x Projection on the axis; T s Indicates the carrier period.

[0046] Time of action of the zero vector T 00 It can be represented as: Step 4: Generate random numbers using the linear congruential method. Based on the random numbers and the sector where the reference voltage vector is located, select one of the two switching sequences and allocate the action time of each vector in the selected sequence.

[0047] Random numbers obtained using the linear congruential method R It can be represented as Where mod represents the modulo operation. l , m It is a constant. y For intermediate variables, subscript n and n -1 represents the current time and the previous time, respectively.

[0048] Based on the magnitude of the random number, select one of the two switching sequences designed in step 1 corresponding to the sector. For example, if the reference voltage vector is in the first sector, and the random number is less than 0.5, select the first switching sequence I-A; otherwise, select the second switching sequence I-B. Then, allocate the application time of each vector in the selected sequence according to the application time of the vector corresponding to the sector in step 3.

[0049] Step 5: Traditional variable delay control, due to the lack of constraints on random numbers, causes the carrier period to be clamped to the minimum carrier period limit, resulting in a uniform carrier frequency distribution and affecting the high-frequency harmonic suppression effect. An improved variable delay control based on random number constraints is adopted to ensure that the carrier period... T s Random variation.

[0050] In the formula, T s ( n ) indicates the generated n One carrier cycle, Δ t ( n ) and Δ t ( n -1) indicates the first n as well as n -1 carrier cycle delay time; T samp The sampling period; Rvtd A random number uniformly distributed in [0,1]. R vtd It is also generated by the linear congruential method. The range of the carrier period is... T c_min to 2 T samp . T c_min This is the minimum carrier period limit. Setting the minimum carrier period limit too small will cause significant switching losses, while setting it too large will affect the high-frequency harmonic diffusion effect. The minimum carrier period limit is usually set to half of the sampling period, i.e., 0.5. T samp .

[0051] Due to random numbers R vtd The value of is between 0 and 1, therefore the difference between two adjacent random numbers ( R ( n )− R ( n -1) takes values ​​from -1 to 1. R ( n )− R ( n When -1) is greater than or equal to 0.5, and the current carrier frequency is less than or equal to the minimum carrier period limit, the current carrier period will be clamped to the minimum carrier period limit. Therefore, it should be ensured that... R ( n )− R ( n -1) is less than 0.5.

[0052] The constraint process for random numbers is as follows: Figure 6 As shown, R final This represents the final output random number. i The random number representing the previous time step R ( n -1) and the random number at the current time R ( n The difference is ). When i When the value is less than 0.5, no additional operation is required, and the final output random number is the currently generated random number, represented as: R final = R ( n );when i When the value is greater than or equal to 0.5, the final output random number will become 1− R ( n ), represented as: R final =1−R ( n ); at the same time 1− R ( n This is also recorded as a random number at the current moment, affecting the next moment. i Value. When i When greater than or equal to 0.5, R ( n The value of ) is between 0 and 0.5. R ( n The value of -1) ranges from 0.5 to 1, 1− R ( n This operation can limit its value to between 0.5 and 1. After performing this operation, the random number from the previous time step... R ( n -1) and the current random number 1− R ( n The difference between the two values ​​will be less than 0.5, and the current carrier frequency will be greater than the minimum carrier period limit. Therefore, clamping can be avoided.

[0053] Step 6: The random switch sequence modulation signal is combined with the random carrier frequency modulation signal to output a pulse width modulation signal, which controls the voltage output of the switching device.

[0054] Based on the selected sequence and the duration of each vector in step 4, the comparison values ​​of each phase pulse width modulation are obtained, and compared with the carrier period obtained in step 5. T s The triangular carrier waves are compared to obtain a dual three-phase pulse width modulation signal, which is then output to the motor through the inverter.

[0055] Figure 7 The diagram shows a comparison of phase currents between the traditional vector control method and the method of this invention for a dual three-phase motor. Compared with the traditional vector control method, it can be seen that the phase current of the method of this invention does not deteriorate significantly, with harmonic current distortions of 10.2% and 10.5%, respectively. However, the peak value of the phase current harmonics in the method of this invention is significantly reduced compared to the traditional vector control method. Figure 8 The graph shows a comparison of high-frequency harmonics between the traditional vector control method and the method of the present invention. The peak value of high-frequency harmonics in the traditional vector control method is 1.88%, while the peak value of high-frequency harmonics in the method of the present invention is only 0.30%.

[0056] Example: To more clearly illustrate the technical solution and implementation effect of the present invention, the following description is based on a specific example of a dual three-phase permanent magnet synchronous motor drive system.

[0057] 1. System Configuration and Parameters Controlled object: A dual three-phase permanent magnet synchronous motor with a rated power of 10kW, whose two sets of three-phase windings have a spatial phase difference of 30° electrical angle.

[0058] Inverter: Driven by a six-phase voltage source inverter consisting of six half-bridges.

[0059] Controller: The dual random control algorithm described in this invention is implemented based on a digital signal processor (DSP).

[0060] 2. Control Parameter Settings Sampling and Fixed Periodicity Parameters: System Sampling Period T samp Fixed at 100µs (i.e., sampling frequency) f samp =10kHz). The parameters of the current loop and speed loop PI controllers are tuned based on this fixed sampling period.

[0061] Random carrier frequency parameter: minimum carrier period limit T c_min Set to 0.5 T samp =50μs, carrier period T s The random variation range is constrained to [50μs, 200μs] (i.e. [ T c_min ,2 T samp The corresponding carrier frequency varies randomly within a range of approximately [5kHz, 20kHz].

[0062] Random switch sequence: As described in step 1 of this invention, two different switch sequences (as listed in the specification) are pre-designed and stored for 12 sectors.

[0063] Random number generation: Generate uniformly distributed random numbers within the interval [0,1] using the linear congruential method. R and R vtd The constants are λ=3571 and m=32749.

[0064] Modulation conditions: The test was conducted under steady-state conditions with the motor running at 50% of its rated speed and the load torque at 75% of its rated torque, with a modulation ratio of approximately 0.8.

[0065] Implementation process and results Under the above hardware platform and parameter settings, the control method described in claim 1 of this invention is executed, and the specific process is as follows: Signal Acquisition and Transformation: Real-time acquisition of six-phase current and rotor position signals from the motor. The fundamental frequency space is obtained through Clarke transform and rotational transform. α−β Subspace) and harmonic space ( z1−z2 The current feedback value of the subspace.

[0066] PI Control and Vector Calculation: After calculation by the speed outer loop and current inner loop PI controllers, the reference voltage vectors in the fundamental and harmonic spaces are output. u α , u β , u z1 , u z2 .

[0067] Sector identification and time calculation: based on u α , u β Determine the sector to which the current reference voltage vector belongs (e.g., sector I), and use the maximum four-vector SVPWM algorithm to calculate the duration of the four effective vectors and the zero vector. T 1. T 2. T 3. T 4, T 00 .

[0068] Random switch sequence selection: Use the linear congruential method to generate random numbers. R .like R If the value is less than 0.5, the first switching sequence of the current sector (e.g., sequence I-A for sector I) is selected; otherwise, the second sequence (e.g., sequence I-B) is selected. The calculated action time is then distributed to the vectors of the selected sequences.

[0069] Random carrier period generation: Use the linear congruential method to generate random numbers R vtd .

[0070] according to Figure 6 The process is constrained by calculating the difference between the random number obtained at the previous time step and the previous random number. i .like i If ≥0.5, then let R vtd =1− R vtd .

[0071] According to the formula Δ t ( n )= T samp +( R vtd ( n )− R vtd ( n −1))× T samp and Ts ( n )=Δ t ( n )+Δ t ( n -1) Calculate the current carrier period T s ( n Ensure that its value falls within the range of [50μs, 200μs].

[0072] PWM Generation and Output: The pulse width modulation comparison values ​​of each phase obtained in step 4 are compared with the values ​​generated in step 5, with a period of... T s ( n The triangular carrier waves are compared to generate six PWM signals, which are then used by the drive circuit to control the inverter switching devices to output the desired voltage to the motor. Implementation effect

[0073] By implementing the present invention using the parameters and processes of the above embodiments, the following results are obtained: Figure 7 (b) and Figure 8 (b) shows the phase current waveform and its high-frequency harmonic spectrum. In contrast, under the same operating conditions, a traditional vector control method with a fixed switching sequence and a fixed carrier frequency (10kHz) yields the following results: Figure 7 (a) and Figure 8 As shown in (a).

[0074] Current waveform quality: The total harmonic distortion (THD) of the phase current output by the method of the present invention is 10.5%, which is comparable to 10.2% of the traditional method, indicating that the basic current waveform is not deteriorated by the introduction of the double random strategy.

[0075] High-frequency harmonic suppression effect: Traditional methods exhibit significant high-frequency harmonic peaks at the switching frequency (10kHz) and its harmonics, with peak values ​​reaching 1.88%. However, the method of this invention, through the synergistic effect of random switching sequences and random carrier frequencies, successfully diffuses high-frequency harmonic energy across a wider frequency band, significantly reducing the harmonic amplitude at specific frequency points, with high-frequency harmonic peak values ​​reaching only 0.30%, demonstrating a remarkable suppression effect.

[0076] Switching losses: Measurements show that, under the parameters of this embodiment, the average switching losses of the inverter increased by no more than 5% compared to the traditional fixed-frequency method, which is within an acceptable range. This verifies the effective control of switching losses by constraining the carrier period and keeping the number of switching cycles constant within the electrical cycle.

[0077] This embodiment fully demonstrates that the dual random control method described in this invention can effectively suppress high-frequency harmonics in a dual three-phase motor drive system and reduce motor vibration and noise, while ensuring system stability and control performance and without significantly increasing switching losses.

[0078] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0079] Although embodiments of the invention have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the claims and their equivalents.

Claims

1. A dual-random control method combining a random switching sequence and a random carrier frequency for a dual three-phase motor, characterized in that, Includes the following steps: Based on the 12 large vectors of the fundamental wave space of the dual three-phase motor, the fundamental wave space is divided into 12 sectors, and two different switching sequences are designed for each sector. By using a PI controller and coordinate transformation, the sampled values ​​and position information of the two-phase three-phase currents are converted into components of the reference voltage vector in the fundamental and harmonic spaces. Based on the maximum four-vector space vector pulse width modulation algorithm, the sector where the reference voltage vector is located is determined, and the duration of each voltage vector within one carrier cycle is calculated. Random numbers are generated using a random number generation method. Based on the random numbers, one of the two switch sequences corresponding to the sector is selected, and the action time of each vector is allocated. An improved variable delay control method based on random number constraints is adopted to make the carrier period vary randomly, wherein the random number is constrained to avoid clamping the carrier period to the minimum limit value; The selected switching sequence modulation signal is combined with the random carrier frequency modulation signal to generate a pulse width modulation signal, which controls the inverter output to the dual three-phase motor.

2. The method according to claim 1, characterized in that, The random number generation method is the linear congruential method, and the random number values ​​range from [0,1].

3. The method according to claim 1, characterized in that, In the improved variable delay control, the carrier period is: In the formula, T s ( n ) indicates the generated n One carrier cycle, Δ t ( n ) and Δ t ( n -1) indicates the first n as well as n -1 carrier cycle delay time; T samp The sampling period; R vtd A random number uniformly distributed in [0,1]. R vtd It is also generated by the linear congruential method, and the range of the carrier period is... T c_min to 2 T samp ; T c_min This is the minimum carrier period limit value.

4. The method according to claim 3, characterized in that, The minimum carrier period limit is typically set to half the sampling period, i.e., 0.

5. T samp .

5. The method according to claim 1, characterized in that, The random number constraint process includes: Calculate the random number generated at the current time. R ( n ) and the random number R( from the previous time step) n -1) difference i ; like i If <0.5, then output R ( n ) as the final random number; like i If the value is ≥0.5, then output 1 −R( n This is used as the final random number, and the current random number is updated to this value.

6. The method according to claim 1, characterized in that, The switching sequence includes four effective voltage vectors and a zero vector, and the number of switching actions differs between the two switching sequences in each sector.

7. The method according to claim 1, characterized in that, The method achieves high-frequency harmonic suppression while keeping the total number of switching actions within one electrical cycle constant.

8. The method according to claim 1, characterized in that, The method is applicable to vector control systems for dual three-phase motors and requires no changes to the hardware structure.

9. A dual three-phase motor control system, characterized in that, It includes a processor and a memory, the memory storing a computer program, and the processor executing the program to implement the dual random control method as described in any one of claims 1 to 8.

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