Average value of the DC-link output voltage in multi-phase uncontrolled bridge rectifiers under supply voltage balance and unbalance conditions

Average value of the DC-link output voltage is a variable of interest in multi-phase uncontrolled bridge rectifiers. The aim of this paper is to present a new, effort-saving procedure capable of providing an accurate value of this variable, a value which can be later corrected considering the usually omitted voltage drops. The proposed method, based on the Cauchy’s formula (1841), allows the limitations of the existing methods to be overcome and can be used under supply voltage balance and unbalance conditions. Time-domain simulations and experimental tests were conducted to show the usefulness of the method and validate its accuracy. Under supply voltage balance conditions, the new method allows results as accurate as those provided by analytical expressions available in the literature or time-domain simulations performed by any software to be obtained. Moreover, under supply voltage unbalance conditions, this method outperforms analytical expressions available in the literature and at least equals time-domain simulations performed by any software in terms of accuracy of the obtained results. Therefore, under supply voltage balance and unbalance conditions, the proposed method makes the mathematical effort required to elaborate analytical expressions or the computational effort required to perform time-domain simulations unnecessary. In addition, the new method provides suitable estimates of values experimentally determined.