A transport refrigeration system is provided with a variable speed compressor which is operated only in the low capacity perishable range of operation. In the way, the line voltage and frequency powercan be used during high capacity operation and a relatively small inverter can be used to provide variable voltage and frequency for the variable speed operation. The variable voltage and frequency can also be provided to a variable speed condenser motor to provide additional condensing capacity during economized operation. It can also be used to provide DC voltage to the compressor for heating purposes.