SYNTHESIS OF CONTROL SIGNALS OF THREE-LEVEL INVERTERS IN REAL TIME

Melnikov Dmitry Vladimirovich, Vrublevsky Nikolai Fedorovich, Petrovichev Maksim Aleksandrovich

High power applications such as AC drive require a high quality inverter output with low harmonic loss and low torque ripple. Reducing the harmonic content in the output current of the inverter is achieved mainly by increasing the switching frequency of the keys, which in turn leads to an increase in dynamic losses on the transistors. In this work, this problem is solved by using a three-level inverter using the control signal synthesis algorithm, in a simplified way. The algorithm makes it possible to implement space-vector and sinusoidal pulse-width modulation (PWM) in real time. It is based on the simplification of the space-vector diagram of a three-level inverter to a two-level inverter. When simplified by the proposed method, all other procedures required for a three-level PWM are performed as for a conventional two-level inverter, and the execution time is significantly reduced. The problem of controlling the potential of the neutral point of the DC link is implemented without computational costs. Neutral point potential control is already built into the procedure for calculating the opening (closing) time intervals of transistors, and is a P-regulator. The proposed method can be applied to multi-level inverters above three-level. The reliability of the proposed algorithm for synthesizing control signals of three-level inverters is confirmed by a computational experiment.

Keywords:algorithm, inverter, microcontroller, reference voltage, gating, control, pulse width modulation