Implementation of DSP-based three-level inverter with dead time compensation

Three-level inverter has gained the advantage over traditional two-level inverter in high-voltage and high-power motor control. In this paper, a 2.2kW three-level voltage source PWM inverter for ac motor applications is described. Space Vector Modulation (SVM) Algorithm is briefed for this inverter. To avoid the switches of the same bridge leg from turning on simultaneous, dead time is added through hardware circuit to secure the whole system. But it also causes current distortion. In order to compensate the voltage deviation resulting from the dead time, a simple but effective method based on the phase current direction is proposed. The difference between actual output voltages and reference ones is calculated at the beginning of every control cycle, and is compensated immediately. Thanks to the powerful floating-point operation capability and high operation precision, TMS320C32 DSP acts as the central unit that implements all the control strategies. PLD is used as PWM generator, which simplifies the structure of the hardware system. At the end of this paper, some simulative and experimental results are given to validate the feasibility.