Abstract
The speed range of the rail transit traction system is very wide and mostly uses the hybrid pulse width modulation. The traditional hybrid pulse width modulation requires different types of modulation strategies to cooperate in switching, which inevitably leads to current and torque ripple and complicates the modulation strategy. In order to solve this problem, this paper proposed an advanced synchronous SVPWM overmodulation method, which can greatly simplify the entire modulation strategy. The modulation method is theoretically analyzed and its detailed mathematical expressions are obtained in this paper. Based on the mathematical expression, this paper analyzed the harmonics of the advanced synchronous SVPWM overmodulation strategy and compared it with that of SHE-PWM. Finally, the simulation and experimental verification of the modulation method are carried out, which proves that the method has simple and efficient and excellent harmonic characteristic.
Highlights
Rail transportation in China is developing rapidly
THE ADVANCED SYNCHRONOUS space vector pulse width modulation (SVPWM) OVERMODULATION STRATEGY The traditional SVPWM modulation strategy is based on 8 unit voltage vectors, including 6 active voltage vectors and
THE HARMONICS ANALYSIS OF THE ADVANCED SYNCHRONOUS SVPWM OVERMODULATION The equation (30) in Appendix is the result of Fourier analysis of advanced synchronous SVPWM overmodulation strategy (ASSOS)
Summary
Rail transportation in China is developing rapidly. Both highspeed railway and urban rail transit such as subway and light rail are being placed in a stage of booming development. With the increase of the modulation index M , the amplitude of the red voltage reference increases gradually, and when the inscribed circle is reached, the traction system transits from the linear modulation to the overmodulation region. In the overmodulation region II, he introduced coefficient K , which varied linearly according to the modulation index, and used coefficient K to control voltage vector, reduced current and torque ripple. This method still divided the overmodulation into two regions, which makes it complex to implement. An advanced synchronous SVPWM overmodulation strategy (ASSOS) is proposed, which can realize a one-stage transition from the linear modulation to the six-step mode. The harmonic characteristic of ASSOS and SHE-PWM are compared and analyzed by simulation and experiment, the practicality and excellent harmonic characteristic of ASSOS are proved
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