| Abstract |
In this paper a method for reducing the RF-emissions from a PWM operated load is investigated. The idea is to use an active gate control in order to obtain a smooth transition between the upper and lower voltage level. A smooth transition may reduce emissions compared to using a switching with sharp flanks and thus leading to reduced EMI. Few circuits are available on the market, that reduce the slopes, but not with active feedback control. In this study a flexible curve-shaping circuit for adc-dc PWM converter, with active gate control, is developed and investigated. The result found is that the method works well, which is verified experimentally. Different curve shapes have been studied and a comparison between trapezoidal and sinusoidal curves shows that, employment of sinusoidal curve-shape gives lower RF-emission compared to trapzoidal. In addition the switching losses are reduced by 10% for the sinusoidal curve-shape. Finally, the circuit operates in the region of 8-15 V power supply. |
