Analytical-Solution-Based Voltage Vector Search within a Desired Tolerance Specification for Low-Sampling-Frequency Motor Drives

Abstract

This paper proposes a voltage modulation method that maintains the voltage-integral error vector within the desired tolerance specification for low-sampling-frequency motor drive systems. A conventional modulator outputs an instantaneous voltage vector per sampling period and requires a high sampling frequency. In contrast, the proposed method analytically solves the voltage vector during the sampling period. Thus, the proposed method is adaptable to the low-sampling-frequency systems while maintaining a high time resolution, and it contributes to increased versatility. The proposed method is tested through experiments on a V/f control system with sampling frequencies up to five times lower than those of the conventional method. This paper confirms that the proposed method maintains the voltage-integral error vector within the tolerance specification, regardless of the sampling frequency. Moreover, by designing an evaluation function to reduce the switching frequency, the proposed method achieves the same performance as the conventional method driven under a high sampling frequency.