Integrators in Pulse Width Modulation

Many control methods for switching circuits employ an integrator to realize Pulse-Width-Modulation. Depending how the integrator is used, the dynamic performance differs greatly. This paper presents a systematic evaluation of the function of integrators in some representative integrator related PWM methods, such as ASDTIC control, Delta/Delta-Sigma Modulation, Modulated Integral Control, and One-Cycle Con- trol. In general, zero steady-state error is granted for all meth- ods. Further, the variable frequency controU methods are able to achieve onecycle dynamic response. In the constant frequency category, however, only the OneCycle Control method achieves one-cycle dynamic response, ie, it realizes zero dynamic track- ing error in the cycle average sense. In this paper, performance enhancement rules were explored for variblle frequency control method in order to reduce the frequency variation. all methods. For the One-Cycle Control method, a pulse position modulation effect is identified which deteriorates the perturbation rejection ability of the single-side modulated One-Cycle Control method in the high frequency range. As a result, a double-side modula- tion is propold that effectively reduces this effect. In addition, a fast reset mechanism is suggested that improves the switching error correction. This paper also provides a general approach to use integr&)tors in PWM to realize arbitrary function.