Patent ID: 6882121
Filing Date: 2005-04-19
Classification: H02P

Abstract:
1. Control device for operating a load circuit having at least one electric motor, said control device comprising a control stage generating a pulse width modulated control signal, a power stage supplying the load circuit and having an electronic switch controlled by the pulse width modulated control signal, a freewheeling element connected in parallel to the load circuit and a blocking monitoring means generating a measurement switch-off interval by suppressing at least one switch-on interval of the pulse width modulated control signal, monitoring the voltage in the load circuit during the measurement switch-off interval, comparing it to a limit value and generating a blocking state signal in accordance with the comparison, the blocking monitoring means for monitoring at least two electric motors connected in parallel in the load circuit carrying out a test run with at least one measurement cycle, in said measurement cycle a voltage sampling being carried out at different defined points in time after the start of at least one measurement switch-off interval and the voltages determined in the load circuit during the voltage samplings being compared with at least one limit value.