The Nonlinear Model of Fourth Order Class-D Amplifier Using Dynamic Sliding Mode Controller

Abstract

Class D amplifier encodes a reference signal to a pulse width modulated signal using a switching circuit that contains MOSFETs. It works as a switch and consumes power on the lower side whether it works in the saturation region or cutoff region. At higher order frequency, disturbance and chattering effects arise and LC filter is used to overcome this issue. To avoid the chattering effect, more stages are needed to flatten the response of the frequency and shooting effect. Consequently, the circuit becomes complex and efficiency is degraded due to the addition of more stages of low pass filter. In this case, the heat sink requirement gains significance. MOSFETs exhibit better efficiency, while operating at high voltage, current, and frequency and GaN MOSFET offers high electric breakdown than Si and SiC. Gallium nitride HEMT (High Electron Mobility Transistor) becomes the potential candidate for WBG (wideband Gap) and low noise impedance. The open-loop simulation of the non-linear fourth-order class D amplifier shows the chattering, settling time, and THD issue. To settle down these issues sliding mode controller (SMC) has been proposed to deal with the nonlinear model of the amplifier. SMC has two major parts; one is sliding manifolds and the other is the control law. SMC is robust and easy to implement on the higher-order system to linearize the model. Super twisting and dynamic controllers are the best techniques of the SMC. The super twisting algorithm is a continuous SM algorithm ensuring the main properties of the first order sliding mode control for systems with Lipschitz continuous matched uncertainties or disturbances with bounded gradients. While the dynamic sliding mode controller (DSMC) is worked with uncertainties, unknown parameters, and disturbances. DSMC has the edge over other SMC techniques because it works for the missing information parameters and converges the whole system. The chattering, noise, shooting, and settling time issues are resolved by using the proposed control technique. The proposed technique enhances the class D amplification more than super twisting sliding mode controller (STSMC) and open loop. This proposed technique is applicable in artificial intelligence vehicles, SONAR, RADAR and wind turbine systems.