Robust hysteresis current-controlled PWM scheme with fixed switching frequency

A robust hysteresis current-controlled PWM scheme is presented, having constant switching frequency for a single-phase inverter with a wide frequency range. An intuitive analysis for the harmonic spectrum characteristic of the hysteresis control PWM inverter is made prior to developing the proposed switching control approach. According to the operating frequency and load nature of inverter, the variation range of the hysteresis band for achieving the desired constant switching frequency is determined, and the hysteresis switching mechanism is devised. Next, the filter design, in accordance with the inverter output frequency feature and the load requirement, is described. In addition, a simple robust controller is proposed to improve the constant frequency control performance and thus to reduce the effect of inverter output harmonics on the load operating characteristics. The proposed hysteresis PWM scheme is applied to an inverter-fed electrodynamic shaker, and its effectiveness is verified by simulation and experimental results.