Analysis and experimental validation of SPWM and SVPWM techniques on two-level three-phase VSI

Abstract

The inverter's output is modulated in terms of frequency and amplitude using a variety of modulation techniques. High-frequency modulation methods are widely used in variable frequency drives due to the advancement of power semiconductor devices. Sine triangular comparison-based pulse width modulation (SPWM) and space vector PWM (SVPWM) are the two high-frequency, continuous modulation methods that are often employed. This study examines and evaluates the aforementioned modulation schemes for a three-phase, two-level voltage source inverter (VSI) through theoretical analysis and hardware implementation. One three-phase, 2.2 kW induction motor is connected across the inverter as a load. The gating signals to the three-phase VSI is provided by using an STM32F407 microcontroller unit (MCU). Both SPWM and SVPWM, powered by the same DC-link voltage, are used in the comparative analysis. The common mode components are inherently present in conventional SVPWM. As a result, SVPWM generates more fundamental AC components than SPWM at the same DC-bus voltage. This study used an experimental method to demonstrate the advantage of SVPWM over SPWM in terms of output voltage quality and amplitude. The RMS output voltage, total harmonic distortion (THD), and DC-bus voltage usage are compared . At various modulation index (MI) values, the inverter's output voltage and three-phase current waveform are observed and recorded. At four different MI values, the THD in voltage and the amplitude of the fundamental AC voltage are calculated using FFT analysis . According to the analysis, SVPWM produces a greater fundamental AC output than SPWM while using the same DC-bus voltage and with significantly less harmonic distortion. The induction motor drive is then loaded with eddy current dynamometer data, and the terminal characteristics of the motor are recorded.