Project Title:  PWM AC Voltage Controller

 

Project Group #4

 

Personnel:

Scott Warren: scottwar@uvic.ca

Brent Sutherland: brent44@uvic.ca

Tim Bodell: tbodell@uvic.ca

Justin Saukarookoff: jsaukaro@uvic.ca

 

Faculty Supervisor:

Supervisor: Dr. Bhat

 

Progress:

 

We have acquired a microcontroller (Arduino Uno) and programmed a PWM output scheme which is dependant on the setting of an external potentiometer. The potentiometer setting is read by one of the analog inputs of the microcontroller and is converted to a digital value which is mathematically calculated to define the duty cycle (between 0-100 percent) of the PWM output.

 

We have attempted to interface a comparator circuit to synchronize the 60Hz signal with the PWM signal.This is in troubleshooting as we are currently having loading problems between the two circuits. Currently the output signal of the comparator is attenuated too much when connected to the microcontroller

 

We have also built and tested a rectifier/transistor bridge that will be used to switch the voltage to the load. These bridges are switched using a MOSFET whose gate is controlled according to the PWM output from the microcontroller. Using this technique we have successfully shown AC voltage control in the low-voltage case (~5 Vpp). This is also is troubleshooting as clipping is apparent when the input signal is increased to over 5Vpp.

 

Future Work:

 

Construct complete power circuit.

 

Design and implement low-pass filter to clean-up harmonics caused by PWM switching.

 

Construct microcontroller isolation circuit.

 

Interface microcontroller to power circuit via isolation circuit.

 

Test and troubleshoot power circuit.