A transport refrigeration system comprising: a transportation refrigeration unit comprising a motor; a power conversion unit configured to convert an amplitude, a frequency and a phase of an input electrical power signal, an energy storage device configured to supply electrical power to the motor via the power conversion unit during a road mode; characterised in that the power conversion unit comprises a first power bridge, a DC link and a second power bridge; and in that the transport refrigeration system comprises: a first switch configured to selectively connect the first power bridge to the energy storage device or the motor; and a second switch configured to selectively connect the second power bridge to the motor or a power grid; wherein during the road mode, the first switch is positioned to connect the first power bridge to the energy storage device and the second switch is positioned to connect the second power bridge to the motor, wherein during a standby mode, the second switch is positioned to connect the second power bridge to the power grid, wherein during a first time share phase of the standby mode, the first switch is positioned to connect the first power bridge to the energy storage device, and wherein during a second time share phase of the standby mode, the first switch is positioned to connect the first power bridge to the motor. a transportation refrigeration unit comprising a motor; a power conversion unit configured to convert an amplitude, a frequency and a phase of an input electrical power signal, an energy storage device configured to supply electrical power to the motor via the power conversion unit during a road mode; characterised in that the power conversion unit comprises a first power bridge, a DC link and a second power bridge; and in that the transport refrigeration system comprises: a first switch configured to selectively connect the first power bridge to the energy storage device or the motor; and a second switch configured to selectively connect the second power bridge to the motor or a power grid; wherein during the road mode, the first switch is positioned to connect the first power bridge to the energy storage device and the second switch is positioned to connect the second power bridge to the motor, wherein during a standby mode, the second switch is positioned to connect the second power bridge to the power grid, wherein during a first time share phase of the standby mode, the first switch is positioned to connect the first power bridge to the energy storage device, and wherein during a second time share phase of the standby mode, the first switch is positioned to connect the first power bridge to the motor. a first switch configured to selectively connect the first power bridge to the energy storage device or the motor; and a second switch configured to selectively connect the second power bridge to the motor or a power grid; wherein during the road mode, the first switch is positioned to connect the first power bridge to the energy storage device and the second switch is positioned to connect the second power bridge to the motor, wherein during a standby mode, the second switch is positioned to connect the second power bridge to the power grid, wherein during a first time share phase of the standby mode, the first switch is positioned to connect the first power bridge to the energy storage device, and wherein during a second time share phase of the standby mode, the first switch is positioned to connect the first power bridge to the motor.