One-Cycle Control Technique Based Voltage Source Inverter

The power converter technique is one of the most important inverter techniques. And the pulse-width modulation techniques are the major part of the power converter techniques, which have been the subject of intensive research during the last few decades. A large variety of methods, different in concept and performance, have been newly developed and described. Their implementation in the design of the voltage source inverters depends on the load types, the power level, and the semiconductor devices used in the power converter. It is lastly performance and cost criteria to determine the choice of a PWM method in a specific application. A new nonlinear control technique is proposed to control the duty-ratio of the switch such that in each cycle the average value of the switched variable of the switching converter is exactly equal to or proportional to the control reference in the steady-state or in a transient. It improves the output waveform quality, and also abates the undesired harmonic contents. However, the one-cycle control (OCC) technique has shown excellent improvement compared with conventional sinusoidal pulse width modulation (SPWM). By using of one-cycle control theory, a novel voltage source inverter is proposed. The conventional one-cycle control technique needs that the integrator is reset instantaneously. But it is very difficult to realize by hardware due to the finite time constant of the reset circuitry. Therefore, based on the one-cycle control technique, the paper gives a new control scheme to resolve the problem with dual channel integrator, and the performance of the integrators is close to ideal. The paper also uses the dc offset to implement the voltage measurement. Further more, the amplitude and frequency of the output voltage are effectively adjustable. Based on the one-cycle control technique, this paper gives the simulation details of the one-phase source, whose simulation results compare with the voltage source inverter based on the SPWM. And the paper simply shows the simulation results of three-phase voltage inverter source based on the one-cycle technique and the SPWM. For the voltage source inverter, the most important point is the performance of the output voltage. And the key factor is the harmonic distortion and the modulation index of the inverter. Comparative studies are conducted to characterize the output distortions of the voltage source inverters which controlled by SPWM and one-cycle control technique. Simulation results with a 10kHz switching frequency have shown that OCC has better performances. By comparison, in the ideal switch conditions, both two methods are about the same performances of output voltages. When we consider the influence of switching dead time, SPWM controlled inverter is worse than OCC controlled inverter. The one-cycle control technique not only provides fast dynamic response, but also can admirably suppress the perturbation yielded by dc source and abate the undesired harmonic contents. Simulation studies were performed to prove the proposed scheme. The results show that the one-cycle control based voltage source inverter makes good use of dc-link voltage that is 92.8% and THD is only 0.2559%. In conclusion, the simulation and experiment results demonstrate that the one-cycle control technique is suitable and feasible for power converter or voltage source inverter.