Temperature and duty cycle controlling PWM help needed!
I am working on a Hydrogen generation project. I am using a PWM (pulse width modulator) to control the Generator from going into thermal runaway. However, the current PWM's on the market dont offer temperature control. Only duty cycle control.
So I need some help here. I need a way to control a potentiometer to increase or decrease resistance based upon a temperature range from 80 to 95 degrees. I dont want this to turn the unit off, only lower the duty cycle when the peak temp is reached. Then also, when the unit is cold on start up, it would release full amps into it until it reached it peak operating temp.
The idea is to make a PWM control the generator via duty cycle (amperage draw) and temperature. Make it a "set it, and forget it" system.
My thoughts are using two surface mount thermostatic switches. One for low limit the other for the high limit. Then a relay and another potentiaometer.
Theory of operation: On initial start up, the generator is offered full amperage draw of 40 amps(100% duty cycle) until it reaches its operating temperature of 80 to 95 degrees. Once it reaches the peak of the operating temp the upper limit switch kicks open causing a relay to offer a differing resistance (80% duty cycle) that would effectively make the PWM still keep producing hydrogen, but cool down. When or if the lower limit of 80 degrees is reached the lower limit thermostat would close allowing again 100% duty cycle to the generator.
Thus, this system would keep the generator operating at an optimal temperature at all times regardless of outside temperature, and conditions.
Current PWM's require the user to manually get them set. If the outside temps are colder the system will work less effectively. If the outside temps are hotter the temps may cause thermal runaway. All operating conditions require the user to be constantly fiddling with, and keeping an eye on the amp draw, temps, and voltage. This means eyes not on the road while driving.
I'd like to make this device super simple to operate, and build. With off the shelf items, not custom IC's.