Abstract: A step-down circuit has a switch connected in series between a direct current power supply and a load. A switch control circuit is configured to turn the switch off when the voltage across the load is higher than a predetermined first threshold and turn the switch on when the voltage across the load is lower than the first threshold. An energy storage unit is charged by the power supply when the switch is on and supply power to the load when the switch is off. An overcurrent protection circuit turns the switch off when the input current of the switch is higher than a predetermined second threshold.

Abstract: A step-down circuit has a switch connected in series between a direct current power supply and a load. A switch control circuit is configured to turn the switch off when the voltage across the load is higher than a predetermined first threshold and turn the switch on when the voltage across the load is lower than the first threshold. An energy storage unit is charged by the power supply when the switch is on and supply power to the load when the switch is off An overcurrent protection circuit turns the switch off when the input current of the switch is higher than a predetermined second threshold.

Abstract: An electric motor system has a first electric motor, a second electric motor and a control circuit shared by the first motor and the second motor. At least one of the first motor and the second motor is a permanent magnet brushless motor that has a permanent magnet rotor and a stator with stator windings which generate a rotating magnetic field when electrified. The control circuit is configured to control the brushless motor to operate in a synchronous mode so that the rotor rotates in synchronism with the magnetic field of the stator. The electric motor system may be used in a household appliance.