A simple and ultra-fast DSP-based space vector PWM algorithm and its implementation on a two-level inverter covering undermodulation and overmodulation

摘要

The paper proposes a simplified algorithm of space vector modulation (SVM) for a two-level voltage-fed inverter. The algorithm is faster and more flexible than any other algorithm so far proposed in the literature. Another relevant advantage of this approach is that a single algorithm covers the undermodulation and overmodulation regions including the square-wave operation with almost no additional computation cost The simplification of the algorithm is achieved by exploring (1) the coupling between the angle and amplitude of the command voltage vector in the final result of the algorithm, (2) extrapolation of the undermodulation strategy into the overmodulation region, (3) reduction of the number of equations to calculate the switching times, and (4) simplification of the sector identification strategy. As a result, the algorithm can be implemented by using only basic mathematical operators (addition, subtraction and multiplication), Boolean logical operators, and a small one-dimensional look-up table. This simplified algorithm permits SVM implementation at higher switching frequency without loosing any good features of the conventional SVM algorithm. Matlab/Simulink simulation results and laboratory experimental results using DSP type TMS320F240 for a Volts/Hz controlled induction motor drive with 20 kHz switching frequency indicate excellent performance of the system.