High digitalized resolution and low switching loss for high power electronics converters based on multi-sampling technology

Digital control has been widely used in power electronics and its sampling rate is important to the control precision. Generally, faster the sampling rate is, closer the digital control is to that of its analog/original antetype. However, in most power electronics system, the sampling rate is commonly once or twice of the PWM switching frequency, which is vital for switching losses. This coupled relationship may result in conflict between high digitalized resolution and high efficiency, especially for high power applications. Multi-sampling technology is to sample the signal many times in one PWM period. Therefore, it doesn´t need to increase the switching speed proportionally while fastening the sampling rate. This paper adopts the multi-sampling in an active power filter (APF) application. A logic method to deal with the problem during implementation due to the nature of digital controller is first proposed. Principle and implementation of this technology is discussed in detail. Analysis and experiment results show that the high compensation performance and low switching loss can be both achieved using the multisampling method.