An Integrated Implementation of Two-Phase Interleaved PFC and Dual Motor Drive Using Single MCU With CLA

Heating ventilation and air conditioning (HVAC) drives utilize variable speed control to maximize efficiency. Power factor correction (PFC) stage is used in the rectifier design in these applications to comply with regulations, such as IEC 61000-3-2, which limit the input current harmonics. Typically control of PFC and the motor stage is kept separate, due to limited CPU bandwidth, where fast is desired for PFC stage (up to 200 kHz) and motor inverter (10-20 kHz). This paper presents a MCU with control law accelerator (CLA) architecture, which enables integration of dual motor control and PFC on a single controller, for a cost sensitive application such as HVAC. In addition to cost reduction and performance improvement, the integration enables the control of the stages together. Also, the surplus bandwidth provided by the CLA, allows the execution of slow background tasks, diagnostics and communication. Integration challenges with software and system level details for the proposed solutions are highlighted in the paper. Additionally improvements to the PFC algorithm using a nonlinear control technique for better output voltage control under dynamic load conditions are presented.