DC Solar Pump Driver 6 HP

[adnan012]

Hi,

I want to design an On/OFF solid state switch to drive a 5 to 6 HP Dc Motor (water pump).
The input voltage range from 130 to 300v DC.

The purpose of this switch is to start the motor after sunrise (when there is enough power available to drive the motor to get minimum possible water flow) and switch off the motor in the evening when solar panels power drops to a certain level.

I need suggestions.

 

[ArticCynda]

300V DC can be switched with a power MOSFET (advisable \[V_{DSmax} > 400\,V\]) or with an IGBT. Specific drivers are available for both. However, since your application does not suffer a performance penalty when using a low side switch, I'd go for an N channel MOSFET and drive it with an opamp at 12V set up as a comparator with positive feedback (hysteresis) that compares either the panel output voltage or an input from a dedicated light sensor against a trimpot to set the cut-off luminosity.

 

[adnan012]

Thanks for reply.

What should be the rating of freewheeling diodes? Do i need snubers?

 

[ArticCynda]

What should be the rating of freewheeling diodes? Do i need snubers?

Since it's a DC motor, you do not need a snubber if you use a freewheeling diode for flyback. I would recommend as a rule of thumb to choose a fast switching diode (Schottky) with a reverse breakdown voltage of at least 400 V and an average forward current of 3 to 5 times the nominal current through your pump.