Device for protecting washing machine motor including brushless motor against overcurrent

A device for protecting a washing machine motor including a brushless motor against an overcurrent, the device comprising:

• a) a position sensing element for sensing a rotational position of a rotor of the washing machine motor;
• b) a motor drive control circuit comprising an inverter main circuit including a plurality of semiconductor switching elements for driving the washing machine motor and an inverter control circuit for controlling the semiconductor switching elements of the inverter main circuit based on a signal generated by the position sensing element;
• c) overcurrent detecting means comprising current detecting means for detecting a current flowing in the inverter main circuit, a reference voltage generating circuit, a comparing circuit comparing a voltage detected by the current detecting means with the reference voltage generated by the reference voltage generating circuit and generating an overcurrent detection signal when the voltage detected by the current detecting means exceeds the reference voltage generated by the reference voltage generating circuit, and a latch circuit latching the overcurrent detection signal generated by the comparing circuit;
• d) abnormal condition detecting means counting up or down and subsequently resetting the latch circuit every time the same is supplied with one overcurrent detection signal from the latch circuit, the abnormal condition detecting means generating an abnormal condition detection signal when having counted up or down by a preselected number of times or more per predetermined period;
• e) means for holding the semiconductor switching elements of the inverter main circuit in an off state when supplied with an abnormal condition detection signal, so that a washing operation by means of the washing machine motor is interrupted;
• and
• f) temporary interruption signal generating means for generating a temporary interruption signal for temporarily turning off the semiconductor switching elements of the inverter main circuit for a predetermined short period of time every time when supplied with the overcurrent detection signal from the latch circuit before the abnormal condition detecting means counts up or down by the preselected number of times.