A transportation refrigeration unit, TRU, and power system comprising: a compressor configured to compress a refrigerant, the compressor having a compressor motor configured to drive the compressor; 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 measure the temperature of the return airflow; a TRU controller operably connected to the RAT sensor and configured to execute a process to determine an AC power requirement for the TRU based on at least the RAT; a generator power converter, the generator power converter configured to receive a generator three phase AC power provided by an AC generator and transmit a second DC power; an energy storage system configured to receive the second DC power and provide a first three phase AC power and receive a second three phase AC power; and a power management system configured to receive the first three phase AC power and direct at least a portion of the first three phase AC power to the TRU based at least in part on the AC power requirement; wherein the energy storage system comprises: an energy storage device; a switching device; and at least one of an DC/AC converter configured to provide the first three phase AC power to the power management system based at least in part on the AC power requirement and an AC/DC converter configured to receive the second three phase AC power to supply the energy storage device. a compressor configured to compress a refrigerant, the compressor having a compressor motor configured to drive the compressor; 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 measure the temperature of the return airflow; a TRU controller operably connected to the RAT sensor and configured to execute a process to determine an AC power requirement for the TRU based on at least the RAT; a generator power converter, the generator power converter configured to receive a generator three phase AC power provided by an AC generator and transmit a second DC power; an energy storage system configured to receive the second DC power and provide a first three phase AC power and receive a second three phase AC power; and a power management system configured to receive the first three phase AC power and direct at least a portion of the first three phase AC power to the TRU based at least in part on the AC power requirement; wherein the energy storage system comprises: an energy storage device; a switching device; and at least one of an DC/AC converter configured to provide the first three phase AC power to the power management system based at least in part on the AC power requirement and an AC/DC converter configured to receive the second three phase AC power to supply the energy storage device. an energy storage device; a switching device; and at least one of an DC/AC converter configured to provide the first three phase AC power to the power management system based at least in part on the AC power requirement and an AC/DC converter configured to receive the second three phase AC power to supply the energy storage device.