Hybrid Current Control Algorithm for Voltage Source Inverters

The losses of a voltage source inverter depend on the converter topology and the characteristics of semiconductor power switches, the control system, the inverter current control (modulation) algorithm and DC link voltage level. Significant component of overall losses are the switching losses of voltage source inverters (which are proportional to the switching frequency). Based on simulation results, the switching losses of different inverter control methods were compared in steady state at various and DC link voltages. The hysteresis and the predictive current control, furthermore the carrier based space vector and two-phase PWMs were examined and simulated. It is shown that at lower speed the carrier based PWM control produces less switching losses than other investigated methods, but for higher speed of induction motor the predictive and hysteresis control has the smallest switching losses. On the basis of these results, the optimal solution can be reached by combining the inverter control methods using hybrid current control algorithm and an algorithm selector which can switch between the inverter control algorithms. This paper shows the realization of the algorithm switch method and the simulation results.