A Pulsewidth Modulation Based Double Integral Sliding Mode Controller for Class-D Amplifiers

In recent years, sliding mode control (SMC) has become more feasible for power electronic converters. One variation of SMC is double integral sliding mode control (DISMC), which has shown good regulation of output voltage, minimum steady-state error, and fast dynamic response to load variation. However, DISMC was rarely applied to class-D amplifiers, and the biggest challenge for applying it to class-D is the stability condition. It becomes more complex than DC-DC converters in which the reference signal is constant and the system’s dynamics at steady state are zero. On the other hand, a class-D amplifier’s reference is a time-varying signal and the system’s dynamics at steady-state are not zero anymore. In this paper, a detailed stability analysis of a PWM-based DISMC for a class-D amplifier is conducted, and controller gains are derived. Simulation results validate the stability of a class-D amplifier that uses DISMC.