Patent ID: 6056384
Filing Date: 2000-05-02
Classification: G01R,H02P

Abstract:
A circuit for facilitating failure diagnosis of switching elements constituting a bridge circuit for driving a motor, the bridge circuit being formed by connecting a first and a second switching element in series and connecting a third and a fourth switching element in series, connecting one motor input terminal between the first and the second switching elements and connecting a second motor input terminal between the third and the fourth switching elements, the circuit comprising:pull up and pull down terminals respectively connected to the input terminals of the motor via resistors;monitor terminals respectively connected to the input terminals of the motor;said pull up/down terminals selectively providing two states including a pull up state for providing voltage for facilitating failure diagnosis to the motor input terminals and a pull down state for providing ground potential to the motor input terminals;means for switching the two states of the pull up/down terminals; andmeans for opening and closing one of the switching elements at a time;whereby a change in potential of the monitor terminals in correspondence with each combination of switching the states and opening and closing of the switching elements indicates open and short-circuit failures or lack thereof and thereby facilitates failure diagnosis of the switching elements without energizing the motor.