A motor drive device includes a rectifier unit that rectifies first AC power supplied from a commercial power supply, an inverter that generates second AC power and output the second AC power to a motor, and a control unit that controls the operation of the inverter such that pulsation according to the power state of a capacitor is superimposed on a drive pattern of the motor, to reduce a charge and discharge current of the capacitor. The control unit performs load pulsation compensation control to compensate for load pulsation, power supply pulsation compensation control to reduce the charge and discharge current of the capacitor, and overload compensation control to reduce an inverter input current input to the inverter, while preferentially performing constant current load control to control the rotational speed of the motor.

An electrical assembly including a power converter having an AC side and a DC side, the AC side for connection to an AC network; at least one power transmission medium connected to the DC side of the power converter; a dynamic braking system operably connected to the power transmission medium, the dynamic braking system including a dynamic braking control unit programmed to selectively control activation of the dynamic braking system to carry out a dynamic braking operation; a monitoring unit for monitoring an electrical parameter of the AC network; and a processing unit programmed to determine an operating state of the AC network from the monitored electrical parameter, wherein the dynamic braking control unit is programmed to be responsive to the determined operating state of the AC network by configuring the dynamic braking system to be activatable.

A vehicle charging system includes a charging station comprising a controller configured to selectively supply power from a vehicle to a home. The controller enables charging in response to a predetermined minimum voltage and a predetermined minimum current on an electric vehicle supply equipment (EVSE) side of the charging station. A mobile battery station is configured to supply power from a plurality of batteries to the EVSE side of the charging station at a first voltage greater than or equal to the predetermined minimum voltage and a first current greater than the predetermined minimum current.

Disclosed are a soft start method, device, and system of a hybrid distribution transformer (HDT) based on unbypassing its voltage-compensating converter, which belong to the technical field of transformer control. According to the method, through a grid-side current controller, a DC-link voltage controller, a split-capacitor voltage balance controller, and a load voltage controller, a start process of the HDT is divided into an uncontrolled rectification stage and a PWM rectification stage. According to the present disclosure, an anti-parallel thyristor of the voltage-compensating converter is closed without a bypass in a process of energization. A DC-link capacitor is charged by respective converters of two transformers of the HDT simultaneously, and thus an energization flow is simpler. In addition, an inrush current at an initial phase of the PWM rectification stage can be effectively mitigated by improving an existing steady-state control strategy.