Three-level optimization PWM method based on PSO algorithm

Abstract

The present invention discloses a three-level optimization PWM method based on a PSO algorithm, relating to the field of optimizing a pulse width modulation method. According to the three-level optimization PWM method based on the PSO algorithm, the harmonic optimization is carried out for a three-level traction inverter, through comparing the inverter output current waveforms obtained by two PWM methods in different frequency-division sections, the current THD obtained by PSO-PWM is much lower than the SPWM, and the current waveform sine degree is better. The current waveform of four working points of different sub frequency bands are optimized for a certain degree, and the good harmonic optimization effect of the PSO-PWM method is verified.

Description

technical field

[0001] The invention relates to the field of optimized pulse width modulation methods, in particular to a three-level optimized PWM method based on a PSO algorithm. Background technique

[0002] In high-power traction inverters, due to the limitation of switching loss and heat dissipation of switching devices, the switching frequency is generally only a few hundred hertz. In the case of low switching frequency, the harmonic content of the output waveform of the traction inverter will be relatively large. These harmonics will increase the additional loss of the traction motor and increase the operating temperature, shorten the insulation life of the motor, and also cause the output torque of the traction motor to pulsate, resulting in mechanical vibration and noise. The traction performance has a great impact. Therefore, it is necessary to adopt an optimized pulse width modulation (PWM) method to reduce the harmonics of the output waveform of the traction in...

Examples

Embodiment Construction

[0022] The preferred implementation of the PSO algorithm-based three-level optimized PWM method of the present invention will be described in detail below in conjunction with the accompanying drawings.

[0023] figure 1 and figure 2 Show the specific implementation of the three-level optimized PWM method based on the PSO algorithm of the present invention: figure 1 The main circuit structure diagram of the three-level traction inverter-motor drive system is given. assumed figure 1 The output phase voltage of the three-level inverter is symmetric in a quarter cycle and anti-symmetric in a half cycle, such as figure 2 shown. It can be seen from the Fourier transform that such a waveform can ensure that the output voltage of the inverter does not contain DC components and even harmonic components. It can be seen from the symmetry of the waveform that as long as the N pulse switching angles in the first quarter cycle are determined, the output voltage pulse sequence of the ...

technical field

[0001] The invention relates to the field of optimized pulse width modulation methods, in particular to a three-level optimized PWM method based on a PSO algorithm. Background technique

[0002] In high-power traction inverters, due to the limitation of switching loss and heat dissipation of switching devices, the switching frequency is generally only a few hundred hertz. In the case of low switching frequency, the harmonic content of the output waveform of the traction inverter will be relatively large. These harmonics will increase the additional loss of the traction motor and increase the operating temperature, shorten the insulation life of the motor, and also cause the output torque of the traction motor to pulsate, resulting in mechanical vibration and noise. The traction performance has a great impact. Therefore, it is necessary to adopt an optimized pulse width modulation (PWM) method to reduce the harmonics of the output waveform of the traction in...

Examples

Embodiment Construction

[0022] The preferred implementation of the PSO algorithm-based three-level optimized PWM method of the present invention will be described in detail below in conjunction with the accompanying drawings.

[0023] figure 1 and figure 2 Show the specific implementation of the three-level optimized PWM method based on the PSO algorithm of the present invention: figure 1 The main circuit structure diagram of the three-level traction inverter-motor drive system is given. assumed figure 1 The output phase voltage of the three-level inverter is symmetric in a quarter cycle and anti-symmetric in a half cycle, such as figure 2 shown. It can be seen from the Fourier transform that such a waveform can ensure that the output voltage of the inverter does not contain DC components and even harmonic components. It can be seen from the symmetry of the waveform that as long as the N pulse switching angles in the first quarter cycle are determined, the output voltage pulse sequence of the ...

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