Optimal design for natural convection-cooled rectifiers

There is a huge market demand for convection-cooled rectifiers in Europe, Asia, and America. The main advantages of natural convection-cooled rectifiers over fan-cooled rectifiers are less acoustic noise, higher reliability (fans usually have lower MTBF), and the ability to work in less environmentally-controlled areas (dust and insects). Optimal design for a natural convection-cooled rectifier is therefore a very important subject. This paper describes the design of a convection-cooled rectifier which is utilized in a telephone battery plant. The rectifier consists of two power stages: a power factor correction (PFC) section and an isolated DC-DC converter to achieve low total harmonic distortion (THD<5%), high power factor (>.99), and high efficiency (>91%). The PFC stage is realized by a boost topology with a lossless snubber circuit and a PF enhancement circuit. The isolated DC-DC stage employs a peak current control (PCC) zero voltage switching (ZVS) full-bridge phase-shifted topology. Analysis and measured results are presented. EMI noise suppression is also addressed