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AC Power Phase Control? Answered

Hello, Can we use AC phase power control Solid State Relay to control the speed of single phase Induction motor, Using PWM as input to the Relay and the output of relay connected to Induction motor, The motor runs at 220v AC,50Hz,55Watt.

Tags:Motor

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user
Downunder35m (author)2016-02-01

Maybe, the problem is the motor.
With PWM control a DC is fine but an AC motor looses a lot of torque this way.
In return it can cause overheating.
A far better way for a single phase motor is to use frequency control.
That way the motor can be driven from about 30% speed to 200% speed with no real loss of torque.
From zero to 30% you will encounter some losses unless the motor and controller are designed for it.

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KaroonjharN (author)Downunder35m2016-02-02

Hi,This is the circuit in which instead of separate optocoupler and triac, I have a solid state relay which has the same mechanism inside, I'm using rp7 lumel ac power phase control Solid state relay.

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steveastrouk (author)KaroonjharN2016-02-02

No, you need frequency control.

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user
KaroonjharN (author)steveastrouk2016-02-02

Are you sure, I can't use AC power phase control relay for it?

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Downunder35m (author)KaroonjharN2016-02-03

Do yourself a favour a look up what types of motors need frequency control and which types can do fine with voltage control.
Basically everything without contacts or bushes inside will work with voltage control - like your vacuum cleaner or electric drill motor.
For everything else you need frequency control.
It is possible with Arduino but requires the use of tables to get half decent sine wave,
That is why smart people invented the frequency controller for AC motors ;)

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steveastrouk (author)KaroonjharN2016-02-03

Use the PWM output, in a high frequency PWM, to synthesise the sine wave you need, and feed that to an H bridge running on high voltage DC.

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Downunder35m (author)KaroonjharN2016-02-02

See it this way:
By phase control, which is nothing more than a fancy dimmer, you keep the frequency but reduce the average voltage available.
With frequency control thevoltage is always the same but the frequency of the AV is changed.
Since a normal AC motor's speed is directly linked to the frequency you will only get a power reduction through the relay.
So even if the speed goes down far enough for you this way, the motor will loose most of the available power.

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KaroonjharN (author)Downunder35m2016-02-03

Thanks, but do you have any idea how to control speed of single-phase induction motor through varying the frequency using Arduino, I have to make speed controlling circuit using Arduino.

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steveastrouk (author)KaroonjharN2016-02-02

You can get small reduction, sometimes, depending on the motor construction.

So, as an engineer with a specialisation in motors, No, you need frequency control.

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KaroonjharN (author)steveastrouk2016-02-03

Thanks, but do you have any idea how to control speed of single-phase induction motor through varying the frequency using Arduino, I have to make speed controlling circuit using Arduino.

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user
KaroonjharN (author)Downunder35m2016-02-02

This is rp7 lumel ac power phase control Solid state relay.

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iceng (author)2016-02-02

An SSR is just a semiconductor switch activated by an opto-isolator.

A relay is a mechanical contact switch activated by a small coil electromagnet..

SSR = Solid State Relay

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