Comparison of Digital PWM Control Strategies for High Power Interleaved DC-DC Converters

This paper evaluates three PWM digital control approaches to achieve the current sharing between phases in high power dual interleaved DC-DC converters. The implementation of a digital peak current, multi-sample averaged current and an enhanced single-sample averaged current control in a TMS320F28377D is described. Experimental results from a 60 kW, 75 kHz silicon carbide DC-DC converter are used to evaluate the steady-state and dynamic performance of the three control methods. Overall the best performance in terms of tracking and speed of response was achieved by the enhanced single-sample method. The multi-sampled technique is recommended for applications needing high tracking accuracy; however this is at the expense of the slowest dynamic response. The fastest dynamic response was achieved by the digital peak current control, but this is limited by poor noise immunity and instability for duty-ratios in the region of 0.5.