July 2005, Issue 180

Solar-Powered Water Pump Controller
Cypress PSoC High Integration Challenge 2004 Contest Winner

AC VOLTAGE REGULATOR

A simple, closed-loop integral regulator controls the waveform generator’s output gain. The regulator ensures that the AC RMS line-to-neutral voltage remains at the required voltage to guarantee the correct voltage-to-frequency ratio. The regulator also runs every line cycle. The governing control equation is

target VAC is based on the nominal inverter frequency and the V/F ratio. The nominal inverter frequency is typically 50 or 60 Hz. You can increase this by 5 to 55 or 65 Hz using the configuration DIP switches.

The inverter’s AC frequency varies in order to maintain a constant DC solar array voltage. This is also controlled by a simple closed-loop integral regulator, which runs every line cycle. The governing control equation is

The maximum power-point-tracking algorithm sets the target VDC.