A three-phase diode bridge rectifier is one of the simplest and most popular rectifiers in industrial applications. The ac-side currents contain harmonics caused by the nonlinear characteristics of the diodes. So far, the performance, including the effect of the resistance on the ac-side, of such rectifiers has been investigated in computer simulation using the currents and powers expressed by Fourier series.
This paper describes theoretical power flow analysis of a three-phase diode bridge rectifier; the effect of the resistance on the ac-side is considered. The method for calculation effective, reactive and apparent powers in fundamental and harmoinic components without computer simulation is discussed; the powers in the circuit are generalized and classified in the paper. Consequently, it can be stated that the harmionic power dissipated in the ac-side resistance is provided from a part of the input power of the rectifier. It is also clear thet the rectifier acts as both a current source related to harmonic powers and a waveform converter from the viewpoint of power conversion. A new equivalent circuit for the diode bridge rectifier is proposed on the basis of sine-wave approximation from the total effective values of volues of voltages and currents.
The analysis and proposed equivalent circuit are simple and considered to be useful for students and engineers in the field of power electronics.