Half-bridge ?

bennettdan

Hello I was looking to drive a DC motor in forward only with a half-bridge mosfet setup and would like to know if I connect a 180vdc motor to the mosfets I have to somehow make the gate voltage on the·high side, low side or both mosfets·higher than the DC bus voltage? If so would anyone have a suggestion as how to do this?

Paul Baker

If you are looking to drive the motor in only one direction, you don't need an H-bridge. H-bridges enable the operation of a DC motor in both directions. You just need an N-Channel MOSFET (with flyback diode protection) to switch the ground point of the motor off and on. Since Ron of the MOSFET should be less than the resistance of the motor windings, you should be able to control the 180vdc motor with a 0/5 Volt gate signal.

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·1+1=10

stamptrol

The gate voltage may not have to be higher than the buss voltage, but it certainly has to be as per the specs for the devices you're using. The spec you need is Vgs or voltage gate with respect to source.

Do you have the spec sheets for the MOSFETS you're using? Generally you can Google them and then you'll have a place to start. As well, many manufacturers have application sheets on their web sites.

If you're only driving in one direction, couldn't you use only one MOSFET in the neg lead of the motor? That way, the gate voltage will be as low as possible.