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Can I use PWM with Mosfet based solid state relays ?

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Apr 1, 2013
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Can I use PWM with Mosfet based solid state relays ?

My question seems applicable to analog design section but it is actually related to an embedded application and hence I am asking the question in microcontrollers section.

I want to know whether I can use PWM to control power to AC load using a mosfet based solid state relay. Will these kind of relay work with AC loads ? I will soon post the embedded circuit which is not complete yet and also the code here.

In the above link there is a bi-directional relay section. In that CPC1909 seems promising for my application. I want a confirmation. Can I use that relay with 230V 2 A AC loads ?
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The one you chose is for 60V, for 230VAC you need at least 400V Vp.
You can use it for slow PWM because the switching speed is 25ms.

So, I can use CPC1967 with 1500 Hz PWM ? My load will be 200W bulbs. I = P/V = 200/220 = 0.9A approx. It doesnt increase 1.2A. Should I need heatsink ?

Any other company making better Mosfet based solid state relays ?

It will be easier for you to look at the catalogue of local supply for SSR.
The one you want to use takes 5ms to switch on and 3ms to switch off. To my easement you can use it for max PWM frequency of 10Hz.
Bulbs cause inrush current of 10-15 times the normal current. You will have to check with the datasheet what is the max current.
Are you using it for a dimmer for the chickens? :)

No, I am not using it for dimmers for the chickens. That person is different. I am making a Voice recognition based device control. I have to control power to loads. Like I will have 10 SSRs acting as switches and two SSRs acting as power controller for Fans and lights.

In this thread you can see that I made a dimmer using TRIAC but the problem is if mains frequency fluctuates then light fluctuates.

Your project sounds very interesting, you will have to tell us at the end how well it works.
Using PWM for precisely controlling the power is a good way. You can also do it with triac or the dimmer you did in that post.
It wont be difficult to add a feedback of the output power and to use it by the microcontroller to adjust the phase delay, that will solve the problem of mains fluctuation. I used to do in the past with analogue circuits. It was also a common practice to make regulated power supplies.
Mosfets will always be more reliable than triacs, but triacs are cheap.

I know that the chickens thread is different, I also remember you posting there, I was only joking about it.
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I am doing the project for blind people. Only the dimmer part is pending. All else is tested and working fine. I use mikroElektronika's SpeakUp Click, PIC18LF46K22, 10 SSRs ( **broken link removed** ). Two SSRs or MOSFETS I have to use for dimmer. It allows blind people to control Fans, AC, etc... using voice commands. It is a voice operated switch board.

I am also thinking about using 16 bit I2C port expanders to increase the number of devices controlled. If 8 port expanders are used then one can control 8 * 16 = 128 devices. Just a small 8 pin PIC like PIC12F1840 can do the work as it has I2C and UART. UART is for SpeakUp Click and I2C for port expanders.

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