Transportation refrigeration unit with energy storage system and external DC power source

A method of generating and directing power to a transportation refrigeration unit (TRU) system having a compressor configured to compress a refrigerant, an evaporator heat exchanger operatively coupled to the compressor;

• an evaporator fan configured to provide return airflow from a return air intake and flow the return airflow over the evaporator heat exchanger;
• a return air temperature (RAT) sensor disposed in the return airflow and configured to measure the temperature of the return airflow;
• and a TRU controller, the method comprising:
• determining an AC power requirement for the TRU based on at least the RAT;
• operably connecting a generator power converter, to an AC generator operably connected to an axle or wheel hub, and configured to provide a generator three phase AC power, the generator power converter configured to receive the generator three phase AC power provided by the AC generator and transmit a second DC power;
• operably connecting an energy storage system, the energy storage system operable to at least one of receive the second DC power, provide a first three phase AC power, and receive a second three phase AC power;
• and
• operably connecting a power management system to the energy storage system and the TRU, the power management system configured to:
• receive the first three phase AC power to direct power to the TRU based at least in part on the AC power requirement;
• and
• generate a TRU DC power from the first three phase AC power and directing the TRU DC power to the TRU system.