A transportation refrigeration unit TRU (26) and power system. The TRU (26) and power system including a compressor (58) operatively coupled to an evaporator heat exchanger (76) and an evaporator fan (98) configured to flow a return airflow (134) over the evaporator (76). The system also includes a return air temperature RAT sensor (142) disposed in the return airflow (134) and configured measure the temperature thereof, a TRU controller (82) connected to the RAT sensor (142) that executes a process to determine an AC power requirement for the TRU (26) based on the RAT sensor (142); a generator power converter (164) configured to receive three phase AC power (163) from a three phase AC generator (162) and transmit a second DC power (165b) to an energy storage system (150); a power management system (124a) configured to receive three phase AC power (157) from at least the energy storage system (150) and generate a TRU DC power (129), and directing the TRU DC power (129) to the TRU system (26).