Design of high fidelity pulse width modulation inverter
Pulse-width modulation (PWM) is well established in power electronics as a basis for inverters with sinusoidal output voltages. It provides two crucial advantages: high power delivery efficiency and easy digital-to-analog demodulation. Thus PWM can be applied in audio signal processing chain as a switching function for a bridge inverter, and a low-pass filter extracts the audio. Meanwhile, this process is nonlinear. So it has often been assumed that implementation of PWM in audio benefited us with its efficiency improvement at the price of distortion. This work explored how PWM can be applied to provide high fidelity audio signal processing with nonlinearity compensation. The distortion effects are analyzed in depth. Noise-shaping processes that reduce quantization errors in the process are described. An inverter is presented that processes information directly in digital form PWM sequence with accurate correction added in the front end noise shaping module. The signal processing chain from digital input to the inverter gate drives is entirely digital. Simulation results confirm that a PWM inverter with efficient nonlinearity compensation can achieve high fidelity in practice.