Abstract: An electrical system comprising an electrical motor and a method for controlling the electrical motor. The system comprises the electrical motor, a power source connection, a first motor control device placed between the power source connection and the motor, and a second motor control device placed in parallel with the first motor control device, the first motor control device supplying electrical power to the motor at least one first operating condition of the motor, and the second motor control device supplying electrical power to the motor at least one second operating condition of the motor, wherein the at least one first operating condition differs from the at least one second operating condition of the motor.

Abstract: A unity power factor power supply for an electric motor. A switch-mode circuit is employed which, in a first mode, transfers power from AC main to a constant voltage DC bus. In a second mode, power generated on the DC bus is fed back to the main power supply. The circuit of the invention automatically maintains the DC bus voltage constant and sets an adequate operation mode by processing the DC bus voltage signal. In both operation modes, the unity power factor and sinusoidal waveform of the AC main side are maintained.