I want to use an arduino to control some ceiling fans in our factory. There is an existing controller that I want to replicate the functionality of. We want to vary the speed of the fans according to the temperature difference between the floor and ceiling. I just need some advice about the hardware components I should use to drive the fans....
There are 5 fans wired in parallel. They have a neutral connection, and two live connections. With my oscilloscope on the existing controller I can see that every 10ms the live terminals get a burst of oscillating pulses which quickly decay over a few milliseconds. The burst on one terminal starts positive whilst the other starts negative. So they are always in opposition to each other. The speed of the fans is dictated by the amplitude of the burst and the decay time. Irrespective of the amplitude and decay time, the bursts start at 10ms intervals.
It would be great if I could buy a controller which works in the same manner and accepts a pwm input to control the speed. Does such a device exist?
@hoofhearted i advice you to use Arduino UNO and relay. along with dht 11/dht22.The relay will work as a switch for the live connection while also recieving input from Arduino. But I have no idea about speed.
@Railroader: The controller I am trying to emulate is an Xpelair WAC6R I only have the normal user manual which doesn't give any of the detailed information which I need.
@flyex10: The temperature control doesn't concern me at this stage, and I have plenty of experience with temperature/humidity sensors. The fan controller is what I need to focus on. I haven't come across this method of motor control previously.
@sonofcy: It certainly is using pwm. I want to find a way to replicate this functionality. Every 10ms I need to trigger some harware to generate a pair of equal and oppositte bursts of alternating mains voltage.
Doesn't sound like PWM. 10ms is one half cycle of 50Hz AC. Is that what you have in your country? Some phase cutting circuit maybe. Was that described oscilloscope output from low speed run?
Perhaps PWM is the wrong term. PWM refers to a square wave pulse whereas i'm talking about diminishing bursts of AC. I'm in the UK where we use 240v 50hz. So there are two bursts of high frequency ac for every mains cycle. The wavelength within these bursts is alot less than 1ms. I'm not in the office now. So I can't say exactly what the wavelength is. When a low speed is selected, the burst decays in about a millisecond. For higher speeds the decay time is extended to several ms.
