船舶大功率AC-DC变换器阻容缓冲器优化方法

Optimum Method for RC Snubber of High-Capacity AC-DC Converter in Ship Electric Propulsion System

船舶电力推进系统大功率AC-DC变换器设计时,必须在晶闸管的两端并联阻容缓冲器,以吸收器件关断过程反向恢复电流的能量,抑制高的过电压冲击及高的电压应力du/dt。但是,阻容参数的设计大多依靠经验公式,参数选取有时产生很大偏差,一旦选取不合理,便会产生很高的尖峰过电压,造成电力电子器件的损坏,影响系统安全运行。针对大功率AC-DC变换器晶闸管阻容缓冲器进行研究,提出了阻容缓冲器优化设计方法,推导出较精确的阻容参数值和电阻的功率,提高大功率AC-DC变换器的可靠性,仿真及实验验证了本方法的可行性。

In design process of high-capacity AC-DC converter in ship electric propulsion system, the RC snubber circuit should be connected to the thyristor in parallel in order to absorb the energy generated at the moment of thyristor switching and suppress overvoltage impulses and high voltage change rate du/dt. However, parameter selection, which is generally depended on empirical formula, sometimes leads to a rather great error. Once the selection of protection parameters is unreasonable, a high spike voltage is likely to occur and render power electronic components will be easily damaged, which threatens the operation safety of equipments. In this paper, a proposed for thyristor in high-capacity AC-DC new optimal design method of RC snubber circuit is converter, R and C parameters and resistor power is deduced more accurately, and the reliability of the AC-DC converter is improved as a result. Numerical simulations and physical experiments are conducted to verify the feasibility and viability of the method.