Three-Phase inverter Controlled by ISCPWM and DPWM-S1

摘要

Nowadays, it is possible to use sophisticated control techniques due to the permanent technical developments which, by means of microcontrollers, DSPs or FPGAs, allow solving complex equations characterizing various modulation techniques. Here are some of them: Third Harmonic Injection Pulse Width Modulation (THIPWM) [1], Discontinuous Pulse Width Modulation (DPWM) [2], Space Vector Modulation [3], etc. These modulation techniques are used in order to enhance the performances of the power electronic circuit, lower cost, reduce size and increase reliability. Implementing a complex control technique that runs in real time on a computer system implies using many resources such as RAM/ROM memory, work speed, internal blocks: PWM, ADC, PLL, DAC, Timers, UART, etc. This paper uses as a reference wave a Discontinuous Pulse Width Modulation S1 signal (DPWM-S1) modulated by an Inverted Sine Carrier Pulse Width Modulation (ISCPWM) carrier signal. The use of the DPWM-S1 signal is beneficial, since it has the value 1 or -1 on two intervals out of six (i.e. a full period). This is important because, in these time intervals, the power transistors within a three-phase inverter are in continuous conduction or blocked, therefore there are no switching losses. Overall, the efficiency of the three-phase inverter will be higher, since the switching losses on the power transistors are lower and thus, they need smaller heat sinks, their life span will be longer and the price of such a circuit will be lower.