| With the rapid development of new energy vehicles,Permanent Magnetic Synchronous Motor(PMSM)is the first choice for motors for new energy vehicles with its advantages of simple principle,safe operation and accurate control.At the same time,inverter circuit as one of the core parts of permanent magnet synchronous motor,this paper will be for a domestic car company research and development of a pure electric vehicle permanent magnet synchronous motor,with modular multilevel converter(MMC)as the research object,the inverter circuit modulation algorithm,MMC sub-module capacitor voltage equalization control,MMC circuit circulation phenomenon of detailed research,the related work is as follows:(1)Aiming at the problems that only one reference wave in the traditional multicarrier cascade modulation algorithm leads to large calculation of the modulation algorithm and unstable output voltage waveform,the traditional multi-carrier modulation algorithm is optimized.A multi-reference wave multi-carrier modulation algorithm is proposed,which compares the two to obtain modulated signals corresponding to the number of submodules by reducing the number of carriers and increasing the number of reference waves.For the modular three-level inverter circuit studied in this paper,the appropriate reference wave frequency and carrier frequency are designed.A simulation model is built to compare and analyze with the nearest level approximation modulation algorithm and carrier phase-shift modulation algorithm,observe the output voltage waveform at the midpoint of the three-phase,and analyze the numerical size of the output voltage waveform after fast Fourier transform.It is concluded that the output voltage at the midpoint of the phase unit of the multi-reference wave multi-carrier modulation algorithm is more stable,and the waveform is closer to the sine wave,and it is observed that the multi-reference wave multi-carrier modulation algorithm has less operation time and lower complexity of the modulation algorithm.(2)Aiming at the circulation phenomenon of internal circuits when the capacitor voltages of MMC neutron modules are not equal,a balanced control strategy based on capacitor voltage is proposed for suppression research.In order to reduce the damage caused by circulation to electronic components,the traditional proportional resonance control circulator is optimized,and an improved proportional resonance controller is proposed,which balances the capacitor voltage of each submodule on the single bridge arm and balances the capacitor voltage of the submodule between the bridge arm and the bridge arm,so that the capacitor voltage of each submodule in the inverter circuit is equal,the circulating current value is reduced,the second harmonic and the fourth harmonic of the circulating current are suppressed,and finally the inverter circuit simulation model is built for simulation verification.It is concluded that the improved circulation control algorithm not only has a certain suppression effect on the secondary circulation harmonics in the circulation,but also suppresses the fourth circulation harmonics,and can reach the stable state faster when the disturbance occurs again.(3)A physical prototype was designed for experimentation,and the proposed modulation algorithm and control strategy were physically verified.According to the existing equipment of the laboratory,a hardware simulation platform based on a 1kw motor was built,and the different modulation algorithms and different control strategies of the hardware physical simulation platform were experimentally compared,and the experimental results showed that the modulation algorithm studied in this paper can make the output voltage of the inverter circuit more stable than the traditional modulation algorithm.The control strategy equalizes the capacitor voltage of each submodule and reduces the circulation phenomenon in the circuit.The effectiveness of the modulation algorithm and control strategy designed in this paper is verified. |
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