These days power applications have to be able to operate at higher frequencies. The opportunity is that the transformer’s volume is inversely proportional to the switching frequency at every power level. As the switching frequency increases, the volume decreases accordingly given the same power level. Switched Mode Power Supplies (SMPS) run at 50 kHz to 200 kHz, with lighter, smaller transformers. The system’s power dissipation – and especially that of the active electronic components – has to be minimized. Otherwise the gain in power density and reduction in weight will come at the cost of a bigger heatsink. The demand for grid-connected power electronics systems’ sinusoidal current sourcing, which requires an active power factor correction (APFC) stage, is making this challenge even more daunting. After all, there is a tradeoff between increased switching frequency and effi ciency. Although increasing the switching frequency helps reduce passive components’ size and cost, it also takes additional eff ort to make effi ciency gains. Nonetheless, the circuit’s effi ciency and cost can be optimized by selecting the right semiconductors and special topologies. 資料下載: ![]() |