Patent ID: 7609021

Claim:
A method of monitoring signals which are supplied from an output stage to a multiphase motor, the pulse width of the signals being controlled by a controller, the method comprising the steps of: generating, by a timer, a gate pulse; measuring, within a predetermined time period corresponding to the gate pulse, a sum of the pulse widths for each phase of the signals which are supplied from an output stage to a multiphase motor, the step of measuring being performed independently of a program sequence in the controller which controls the signals, said measuring comprising one of: combining each of the signals with the gate pulse, sending the combined signals to respective counters, and reading the counters after the predetermined amount of time; or sending each of the signals to respective counters, sending the gate pulse to the counters, enabling the counters for the duration of the gate pulse; and generating a fault signal if the measured sum is outside a predetermined tolerance range.