Driving a 48V 400W DC motor from a single phase 220V 50Hz AC: Comparison between two topologies.

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Joined Mar 19, 2015

In my mind, there are two ways to do this. However, I don't know pros, cons, and cost-effectiveness of each.

The link above presents driving one from SCRs. The 4 SCRs can't reverse the motor's direction, thereby requiring another four to do so. However, as shown, the topology is work best with 3 phase.

The other way is using a bridge rectifier and a dc-dc converter to convert 220V to 48Vdc. Subsequently, a h-bridge mosfet driver is conneted to 48Vdc to drive my motor. This allow me to control both speed and direction. However, the converter requires a transformer for safety. I'm afraid that the transformer will dump the overall efficiency down.

Which way should I take? Is this a trading off between smoothness of dc voltage across the motor and the overall efficiency?