Pure sinewave inverter ups mod

[Sathyan]

Dear Sir,
I wanted to clarify some doubt related to pure sinewave inverter UPS mode. Why 40 volt require to fast trigger of relay in UPS mode. please explain. Since the relay is rated 12volt.

 

[BradtheRad]

Presumably because the relay responds fastest to the maximum voltage its coil can withstand. UPS mode should begin immediately as soon as mains AC stops. Detailed operation of the changeover depends on which circuitry the relay connects or disconnects, and where is the source of the voltage to activate the coil.

Does the inverter contain mosfets? Because 40V is near the safe limit for biasing an ordinary mosfet in order to avoid perforating its insulated gate.

 

[Sathyan]

Presumably because the relay responds fastest to the maximum voltage its coil can withstand. UPS mode should begin immediately as soon as mains AC stops. Detailed operation of the changeover depends on which circuitry the relay connects or disconnects, and where is the source of the voltage to activate the coil.

Does the inverter contain mosfets? Because 40V is near the safe limit for biasing an ordinary mosfet in order to avoid perforating its insulated gate.

Thank you for your immediate reply. The inverter is pure sine wave with medi board ,of course it is mosfets based, the source is from 12 volt battery and external 48 volt transformer with 39 volt Zener diode and 1 k resistor to reduce current and voltage. Please tell me any problem with this circuit.

Thanks.

 

[BradtheRad]

Not knowing anything further about your project's topology, I'll bring up one general rule about mosfet operation. It sounds as though 40 or 48V is present supplying power to the mosfets (full H-bridge?). Expect that the applied bias voltage must be high enough to fully turn On and/or turn Off the high-side devices.

I had a UPS which contained a 24V battery system (made from four 6V gel-cells). Supplying power in a blackout it only lasted a few minutes. A 12V system is burdened even more during a blackout. Attention must be given to design rules governing several Watts of power conversion.