US Patent 7740110 Elevator brake and brake control circuit

A control circuit for controlling an electromechanical elevator brake is disclosed. The control circuit includes at least one brake coil (L1), a direct-voltage source (BR1), a semiconductor switch arrangement, a current measuring unit, at least two semiconductor switches, and a control unit (CO1) for controlling operation of the circuit. The current measuring unit (Lm1) produces current data that is passed to the control unit (CO1). The at least two semiconductor switches (SW1, SW2) are controlled by the control unit (CO1) such that operation is alternated between the two so that the working condition of each switch can be checked in its turn on the basis of feedback data obtained from the current measuring unit.