SLLA567 August 2021 MCF8316A , MCT8316A
In a half bridge leg, dead time is applied between the switching instants of high side and low side MOSFET to avoid current shoot through condition. Due to dead time insertion, the expected voltage and applied voltage at the phase node differ based on the phase current direction. The phase node voltage distortion introduces undesired distortion in the phase current causing audible noise. The MCF8316 device integrates a proprietary dead time compensation using a resonant controller to control the harmonic component in phase current to zero, ensuring that the current distortion due to dead time is alleviated. The resonant controller is employed in both Iq and Id control paths. Figure 2-4 shows phase current waveform when dead time compensation is disabled and the FFT of phase current. Figure 2-5 shows phase current waveform when dead time compensation is enabled and the FFT of phase current. In below graphs, PWM output frequency is set to 60 kHz and dead time is set to 500 ns. Motor electrical speed is 12 Hz. As seen in the FFT on current waveforms in the graphs (Signal in PINK), phase current is much cleaner after enabling dead time compensation.