I want suggestions .....

260

02:22:40

Shake your phone to start...
The frequency can be varied by changing the states of the logic inputs 00, 01, 10, 11. The lower one being the MSB

I'm currently working on small induction machine speed control by applying variable frequency source this is as far as I get,
I Used a 1 KHz square wave then I used counter to get a square wave of frequency of 1/2, 1/4, 1/8, 1/16 of the original 1KHz wave, I used a multiplexer to pass one selected signal from the four, then I applied this signal to an H-Bridge to supply the induction motor, so there will be 4 speed options...
The two opamps are just there to make the output of the logic gates more flat...


Is it a good idea or will it work in real world

published 10 years ago

hurz

10 years ago

The top NMOS won't survive. Ug is only 15V Us will by Ugs below. The rest voltage is droped as Uds=300V-Us~285V P=285V*1A -> 285watt pulses!! You have to bring Ug above 300V! Lookup boostrap circuits. Anyway 300V against 10 resistance is a 30A current, if your transistors are in switching mode, which is needed to not despite power. I won't switch this device on without sunclasses ;-)

nikisalli

10 years ago

If you want to use a motor i suggest you to use pwm instead of variable frequency

selman

10 years ago

Hmmm so i need another switching circuit.......

flowDAQ

10 years ago

https://en.m.wikipedia.org/wiki/Variable-frequency_drive

flowDAQ

10 years ago

If you're wanting VFD its done with PWM as nikisalli suggest

rich11292000

10 years ago

Would a pmos fix it?

rich11292000

10 years ago

VFD is the way to go with AC induction motors, i hope your not hooking up a motor designed for mains, these frequencies are to high. What motor are you using.

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