A space vector modulation method for an optimal full modulation range five-phase motor

Abstract

An optimal full-range space vector modulation method for a five-phase motor includes two steps: allocating proportional parameters and modulating a reference voltage to obtain a five-phase SVPWM waveform based on proportional allocation coefficients; and controlling the operating mode of the five-phase motor. The proportional parameter allocation involves five sub-steps. Specifically, based on the time and component vector allocation parameters obtained from the proportional parameters, the effects of four voltage vectors are proportionally allocated to synthesize a new composite vector, resulting in the application time of each of the four voltage vectors. Finally, based on the different sectors and basic voltage vectors, a five-phase output PWM waveform is generated for use by the five-phase motor control software, achieving complete harmonic-optimal full-range space vector modulation for a five-phase motor. This invention balances the maximum modulation range of five-phase space vector modulation with the minimum harmonic voltage of the modulated waveform, providing favorable technical support for the reliable and stable operation of five-phase motors.

Description

Technical Field

[0001] This invention belongs to the field of motor control technology, specifically a space vector modulation method for a five-phase motor with optimal full modulation range. Background Technology

[0002] To achieve better work efficiency, an increasing number of high-power hydraulic and mechanical industrial equipment require electrification retrofits. Furthermore, with the rise of new energy vehicles, the electrification retrofits themselves and the need to ensure stable performance of electric drive equipment place higher demands on motor drive systems. Compared to traditional three-phase motors, five-phase motors offer advantages such as higher power density, smaller size, lower torque ripple, stronger fault tolerance, and multi-dimensional spatial control. Moreover, space vector modulation can achieve greater output power and a wider modulation range under the same bus voltage. Besides being used in high-power, high-precision, and high-reliability applications such as aerospace, marine, and servo motor drives where torque ripple is critical, they are also used in new energy vehicle applications.

[0003] There are two main space vector modulation methods used in five-phase motors: maximum two-vector modulation and nearest four-vector modulation. Maximum two-vector modulation can achieve the maximum modulation range of five-phase space vector modulation, but due to technical limitations, it suffers from a relatively high harmonic content in the modulation voltage. The nearest four-vector modulation method achieves zero harmonic voltage, but due to technical limitations, its modulation range is only 80% of the maximum modulation range. Therefore, achieving optimized space vector modulation that maximizes the modulation range while minimizing harmonic voltage is a crucial issue in five-phase motor space vector modulation. Summary of the Invention

[0004] To overcome the limitations of existing space vector modulation methods for five-phase motors, which, due to technological constraints, cannot achieve the maximum modulation range and have smaller harmonic voltages, thus hindering the effective application of five-phase motors, this invention provides an optimal full-range five-phase motor space vector modulation method that, through the combined action of related steps, can achieve both the maximum modulation range of five-phase space vector modulation and the minimum harmonic voltage of the modulated waveform, thus providing favorable technical support for the reliable and stable operation of five-phase motors.

[0005] The technical solution adopted by this invention to solve its technical problem is:

[0006] A method for optimal full-range space vector modulation of a five-phase motor is characterized by two steps: allocating proportional parameters and modulating the reference voltage according to the proportional allocation coefficient to obtain a five-phase SVPWM waveform, and controlling the operating mode of the five-phase motor. The allocation of proportional parameters includes the following sub-steps: Sub-step A: determining the sector based on the reference voltage angle of the five-phase motor, calculating within a single sector to determine the large and medium vector data; Sub-step B: directly calculating the reciprocal 1 / U2 of the new synthesized vector based on the formula for obtaining the minimum value point across the entire harmonic voltage range, and then using [C... min C max [Mathematical limiting is applied; Step C: Based on the 1 / U2 data obtained in step B and the action time formula of the five-phase two-vector space vector modulation, the magnitude of the reciprocal 1 / U1 of the other new synthesized vector is directly calculated, and then [C] is applied. min C max [Mathematical limiting is applied; Step D: Based on the reciprocal of the data from step C, the values ​​of the two new composite vectors U1 and U2 on the initial and secondary sides of this sector are obtained, and the amplitude of the new composite basic vector is defined in the dual-space formula according to the introduced allocation parameter λ, and the allocation coefficients λ1 and λ of the two composite vectors are calculated; Step E: Based on the two new composite vectors U1 and U2 and the action time formula of the five-phase two-vector space vector modulation, the action time T1 and T2 of the two new composite vectors are calculated; The reference voltage is modulated according to the proportional allocation coefficient to obtain the five-phase SVPWM waveform, and the five-phase motor operation mode is controlled. Specifically, according to the time T1 and T2 obtained in step E and the composite vector allocation parameters λ1 and λ2 obtained in step D, the four basic vectors of composite U1 and U2 are proportionally allocated to obtain the action time T of the four voltage vectors.] L1 T M1 and T M2 T L2 Finally, based on the different sectors and basic voltage vectors, the five-phase output PWM waveform is completed and used by the control software of the five-phase motor, realizing the complete harmonic optimal full modulation range five-phase motor space vector modulation.

[0007] Furthermore, in the allocation ratio parameter, a mathematical model of non-sinusoidal overmodulation is first established, the mathematical expression of the optimal harmonic ratio is analyzed, and then the allocation ratio parameter is obtained.

[0008] Furthermore, the introduced allocation parameter λ defines the magnitude of the new synthetic fundamental vector in the two-space formula as follows:

[0009]

[0010] Furthermore, the introduction of the allocation parameter λ to define the magnitude of the new synthetic fundamental vector in the dual-space formula involves the following formula for establishing the harmonic voltage model in the non-sinusoidal overmodulation region:

[0011]

[0012] Furthermore, in the formula for establishing the harmonic voltage model in the non-sinusoidal overmodulation region, the minimum value of the harmonic voltage can be transformed into a problem of solving for the minimum value of F(1 / U2), as shown in the following formula:

[0013]

[0014] Furthermore, in the formula for establishing the harmonic voltage model of the non-sinusoidal overmodulation region, the median formula of the minimum function of F(1 / U2) is as follows:

[0015]

[0016] Furthermore, the formula for obtaining the minimum value point of the harmonic voltage across the entire range is as follows:

[0017]

[0018] Furthermore, the action time formula for the five-phase two-vector space vector modulation is as follows:

[0019] Furthermore, the action time formulas for the medium and large vectors involved in the five-phase two-vector space vector modulation are as follows:

[0020] The beneficial effects of this invention are as follows: Through the combined action of related steps, this invention introduces a dual proportional coefficient, simplifying the four basic vectors into a two-vector modulation method, thus simplifying the existing five-phase four-vector space vector modulation mechanism and method. By allocating parameter matching, it achieves zero harmonic voltage for the four nearest vectors and minimizes harmonic voltage in the non-sinusoidal modulation region. By establishing a modulation mathematical model for the non-sinusoidal modulation region and using mathematical extrema to solve for the mathematical law of minimum harmonic voltage, it achieves the optimal modulation method for minimum harmonic voltage. Through mathematical limiting, it achieves minimum harmonic voltage across the entire range, reaching the optimal basic vector ratio. It eliminates the need for complex division methods; optimal five-phase space vector modulation across the entire harmonic voltage range can be achieved simply through a unified mathematical expression. This invention balances the maximum modulation range of five-phase space vector modulation with the minimum harmonic voltage of the modulated waveform, providing favorable technical support for the reliable and stable operation of five-phase motors. Based on the above, this invention has good application prospects. Attached Figure Description

[0021] Figure 1 This is a diagram of the drive structure of a five-phase motor voltage source inverter.

[0022] Figure 2 This is a diagram showing the voltage vector distribution in the two spaces of a five-phase motor.

[0023] Figure 3 This is a boundary partition diagram of the minimum harmonic voltage in the first sector.

[0024] Figure 4 A block diagram for the overall implementation of the optimal space vector modulation. Detailed Implementation

[0025] An optimal full-range space vector modulation method for a five-phase motor is proposed. To achieve both maximum modulation ratio and optimal modulation harmonics, this invention mainly comprises two parts. The first part involves adding allocation parameters, establishing a mathematical model for non-sinusoidal overmodulation, analyzing the mathematical expression for optimal harmonic ratios, and deriving the allocation ratio parameters. The second part involves modulating the reference voltage according to the allocation ratio coefficients to obtain the five-phase SVPWM waveform. The five-phase motor voltage source inverter drive structure is as follows... Figure 1 As shown, the dual-space voltage vector distribution of the five-phase motor in this topology is as follows: Figure 2 As shown. To mathematically model the multidimensional vector space vector modulation method, the long vectors U at the same angle in the figure are... L , medium vector U M The space voltages are combined with parameter λ to generate a new set of composite vectors. At this point, the complex multi-vector modulation will be consistent with the three-phase space vector, and the complex calculation of multiple sets of space vectors can be replaced by a simple calculation of two new composite vector modulations. The mathematical expression of the magnitude of the new composite basic vector in the two spaces is defined by the allocation parameter λ as follows:

[0026]

[0027] In the formula, |U|1 and |U|3 are the vector amplitudes of the synthesized fundamental vector with the assigned parameter λ in the fundamental and harmonic spaces, respectively. Based on this mathematical model, a harmonic voltage model for the non-sinusoidal overmodulation region is established, and its expression is as follows:

[0028]

[0029] In the formula, M3 = 4.45407M1 + M2, M1 = U r sin(θ), U r θ and θ represent the amplitude and phase angle of the fundamental plane of the reference voltage vector, respectively; U2 is the amplitude of the synthesized vector of the secondary side of a single sector, U R3 As the reference voltage modulated harmonic amplitude in the harmonic plane, the minimum value of the harmonic voltage in equation (2) can be transformed into the problem of finding the minimum value of F(1 / U2) in equation (3):

[0030]

[0031] F(1 / U2) is a function with 1 / U2 as its independent variable. Since the secondary side composite vector U2 is in the range [0.5257, 0.6472], the range of the function's independent variable is [C]. min C max C min =1.545, C min = 1.809. In this interval, we explore the minimum value of the function F(1 / U²). According to the mean value theorem for quadratic functions, the mean value of the function is:

[0032]

[0033] When the value f in the function m In C min and C min At the boundary, boundary curves a and b within a single sector can be obtained, such as... Figure 3 As shown in the figure, a single sector is divided into three regions: the region between curves a and b, and the function's midpoint f. m Between [C] min C max Between ], the minimum point of the function is f. m Point; in the region to the left of curve a, f m Located in C max On the right, the minimum point is C. max Point; to the right of curve b, f m Located in C min On the left, the minimum point is C. min Point. From the above analysis, it can be seen that the function F(1 / U2) for finding the minimum value of the harmonic voltage should achieve its minimum value in the entire sector, across the entire range, at point 1 / U2, satisfying the amplitude limiting within [C]. min C max The following expressions are within the range:

[0034]

[0035] The reciprocal of the newly synthesized vector 1 / U1 is also limited in [C]. min C max And satisfying equation (6):

[0036]

[0037] At this point, we obtain the initial and secondary side composite vectors U1 and U2 when the harmonic voltage amplitude is minimized. U1 and U2 at this point are the optimal ratio composite vectors for minimizing the space vector modulated harmonic voltage, obtained by solving mathematical extrema.

[0038] The other part is to calculate the ratio parameters λ1 and λ2 of the two composite basic vectors based on U1 and U2 using equation (1), and obtain the expression (7) of the action time T1 and T2 of the two composite vectors based on U1 and U2 as follows:

[0039]

[0040] Based on the optimal harmonic ratio parameters λ1 and λ2, and the action times T1 and T2 of the two composite vectors U1 and U2, the action times of the neighboring medium and large vectors in the sector are obtained, as expressed below:

[0041]

[0042] In the formula, T M1 T M2 T represents the time of action of the vectors in the primary and secondary sides, respectively. L1 T L2 These are the durations of action of the vectors representing the lengths of the first and second sides, respectively.

[0043] The five-phase space vector modulation voltage is completed based on the action time of the four vectors. The overall implementation block diagram of the modulation scheme of this invention is as follows: Figure 4 As shown.

[0044] Figure 1 , 2As shown in Figures 3 and 4, an optimal full-range five-phase motor space vector modulation method is described. Specifically, the allocation of proportional parameters includes the following steps: Step A: Determine the sector based on the reference voltage angle of the five-phase motor, and calculate the large and medium vector data within a single sector; Step B: Directly calculate the magnitude of the reciprocal 1 / U2 of the new synthetic vector using the formula for obtaining the minimum value point across the entire harmonic voltage range (Formula 5), ​​and then mathematically limit it using [Cmin, Cmax]; Step C: Directly calculate the magnitude of the reciprocal 1 / U1 of another new synthetic vector using the 1 / U2 data obtained in Step B and the action time formula for five-phase two-vector space vector modulation (Formula 7), and then mathematically limit it using [Cmin, Cmax]; Step D: Obtain the values ​​of U1 and U2 of the two new synthetic vectors on the initial and secondary sides of the sector based on the reciprocal results of the data in Step C, and then... The allocation parameter λ defines the amplitude of the new synthesized basic vector in the dual-space formula (Formula 1), and calculates the allocation coefficients λ1 and λ2 of the two synthesized vectors; Step E: According to the two new synthesized vectors U1 and U2 and the action time formula of the five-phase two-vector space vector modulation (Formula 7), the action time T1 and T2 of the two new synthesized vectors can be obtained; According to the proportional allocation coefficient, the reference voltage is modulated to obtain the five-phase SVPWM waveform and control the five-phase motor operation mode. According to the time T1 and T2 obtained in step E and the synthesized vector allocation parameters λ1 and λ2 obtained in step D, the four basic vectors of synthesized U1 and U2 are proportionally allocated to obtain the action time TL1, TM1 and TM2, TL2 of the four voltage vectors. Finally, according to the different sectors and basic voltage vectors, the five-phase output PWM waveform is completed for use by the control software of the five-phase motor, realizing the complete harmonic optimal full modulation range five-phase motor space vector modulation.

[0045] Figure 1 , 2 As shown in Figures 3 and 4, this invention, through the combined action of related steps, introduces a dual proportional coefficient, simplifying the four basic vectors into a two-vector modulation method, thus simplifying the existing five-phase four-vector space vector modulation mechanism and method. By allocating parameter matching, it achieves zero harmonic voltage for the four nearest vectors and minimizes harmonic voltage in the non-sinusoidal modulation region. By establishing a modulation mathematical model for the non-sinusoidal modulation region and using mathematical extrema to solve for the minimum harmonic voltage, it obtains the mathematical law for minimizing harmonic voltage, achieving the optimal modulation method for minimizing harmonic voltage. Through mathematical limiting, it achieves minimum harmonic voltage across the entire range, reaching the optimal basic vector ratio. It eliminates the need for complex allocation methods; optimal five-phase space vector modulation across the entire harmonic voltage range can be achieved simply through a unified mathematical expression. This invention balances the maximum modulation range of five-phase space vector modulation with the minimum harmonic voltage of the modulated waveform, providing favorable technical support for the reliable and stable operation of five-phase motors.

[0046] It should be noted that although the embodiments of the present invention have been shown and described above, the implementation methods do not include only one independent technical solution. This description method is only for clarity. For those skilled in the art, it can be understood that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the present invention, forming other implementation methods that can be understood by those skilled in the art. Therefore, the scope of protection of the present invention is defined by the appended claims and their equivalents.

Claims

1. A space vector modulation method for a five-phase motor with optimal full modulation range, characterized in that, The process includes two steps: allocating proportional parameters and modulating the reference voltage according to the proportional allocation coefficient to obtain a five-phase SVPWM waveform, and controlling the operation mode of the five-phase motor. The allocating proportional parameters include the following sub-steps: Sub-step A: Determine the sector based on the reference voltage angle of the five-phase motor, and perform calculations within a single sector to determine the large and medium vector data; Sub-step B: Directly calculate the reciprocal 1 / of the new synthesized vector based on the formula for obtaining the minimum value point across the entire harmonic voltage range. U 2的大小 Then with [C min C max Apply mathematical limiting to it; Step C: Based on the 1 / obtained in step B U 2. The formula for the action time of data and five-phase two-vector space vector modulation, directly calculating the reciprocal of another new synthesized vector 1 / U The size of 1, and then similarly in [C min C max [Apply mathematical amplitude limiting; Step D: Obtain the two new composite vectors of the initial and second sides of this sector based on the reciprocal of the data from step C.] U 1 and U The value of 2, and according to the introduced allocation parameters. λ Define the magnitude of the new composite fundamental vector in a two-space formula, and calculate the distribution coefficients of the two composite vectors. λ1和λ； ; Step E: Based on the two new composite vectors U 1 and U 2. Formulas for the action time of five-phase two-vector space vector modulation, and calculation of the action time of two newly synthesized vectors. T 1. T 2; In the process of modulating the reference voltage according to the proportional distribution coefficient to obtain the five-phase SVPWM waveform and controlling the operation of the five-phase motor, the specific timing is based on the time obtained in step E. T 1. T 2. Assignment parameters of the composite vector obtained in step D λ1和λ2 To allocate to the synthesis in proportion U 1 and U The four basic vectors of 2 are used to obtain the duration of action of the four voltage vectors. T L1 , T M1 and TM2、TL2 Finally, based on the different sectors and basic voltage vectors, the five-phase output PWM waveform is completed for use by the control software of the five-phase motor, realizing complete harmonic optimal full modulation range five-phase motor space vector modulation; in the formula for establishing the harmonic voltage model of the non-sinusoidal over-modulation region, F(1 / U 2)的极小值函数的中值公式如下： The formula for obtaining the minimum value of harmonic voltage across the entire range is as follows: Introducing allocation parameters λ The magnitude of the newly synthesized fundamental vector in the two-space formula is defined as follows: The reciprocal of the newly synthesized vector on the initial side is 1 / U 1 is the same as the limit in [C] min C max [and satisfy the following formula]: .

2. The optimal full modulation range space vector modulation method for a five-phase motor according to claim 1, characterized in that, In the allocation ratio parameters, a non-sinusoidal overmodulation mathematical model is first established, the mathematical expression of the optimal harmonic ratio is analyzed, and then the allocation ratio parameters are obtained.

3. The method for optimal full modulation range space vector modulation of a five-phase motor according to claim 1, characterized in that, Introducing allocation parameters λ The definition of the new synthetic fundamental vector magnitude in the two-space formula involves the following formula for establishing the harmonic voltage model in the non-sinusoidal overmodulation region: .

4. The optimal full modulation range space vector modulation method for a five-phase motor according to claim 3, characterized in that, In establishing the formula for the harmonic voltage model in the non-sinusoidal overmodulation region, the minimum value of the harmonic voltage can be transformed into F(1 / U 2) The formula for solving the minimum value problem is as follows: 。 5. The optimal full modulation range space vector modulation method for a five-phase motor according to claim 1, characterized in that, The action time formula for five-phase two-vector space vector modulation is as follows: .

6. The optimal full modulation range space vector modulation method for a five-phase motor according to claim 5, characterized in that, The action time formulas for the medium and large vectors involved in the five-phase two-vector space vector modulation are as follows: .

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