INTEGRATED DESIGN OF EFFICIENT & RELIABLE MOTOR
DRIVE AND PFC USING LOW COST MICROCONTROLLER
WITH EMBEDDED PGA’S AND CLA
Heating ventilation and air conditioning (HVAC) drives commonly utilize variable speed
control to maximize efficiency and increasingly power factor correction (PFC) stage in the
rectifier design to comply with regulations, such as IEC 61000-3-2, which limit the input current
harmonics. Cycle by cycle control is desired for both the PFC stage and motor inverter. Closed
loop control of these stages consumes the entire bandwidth available on a typical microcontroller
leaving no bandwidth to implement fault diagnostics, housekeeping and host functions. This
paper presents design of motor control and PFC using a single low cost microcontroller (MCUTI TMS320F2805x) with embedded analog subsystem consisting of programmable gate arrays
(PGA) to sense the shunt inverter currents, windowed comparators and DACs for programmable
protection levels; and small footprint control law accelerator (CLA) to double the bandwidth.
The integrated design reduces the number of components, reducing board size and build cost and
enables on the fly changes which brings enhanced control possibilities for a cost sensitive market
without compromising on cost.