Sensor Count Reduction for Single-Phase Converters with an Active Power Buffer Using Algebraic Observers

Abstract

Single-phase power converters with an active pulsating power buffer (PPB) have many advantages, such as enabling electrolytic-capacitor-free design and simultaneous high power density and high efficiency. However, this new type of converter generally requires more sensors than converters without a PPB due to the additional PPB circuitry. Requiring an excessive number of sensors largely compromises the power density, reliability, and cost of the overall system. Unfortunately, the high-sensor-count issue of single-phase converters with a PPB is seldom discussed in literature. In this article, an algebraic-estimation-based method is proposed to solve this high-sensor-count problem. Specifically, a general theory of employing algebraic observers to reduce the number of sensors is developed. Comprehensive analysis, design, and optimization of the algebraic observers in both continuous and discrete time domain are also provided. Then, the proposed method is applied to a typical single-phase rectifier with a PPB and is verified with simulation and experiments.