Drum type washing machine and method of detecting laundry weight thereof

A method of detecting laundry weight of a drum type washing machine, comprising:

• a first step of applying phase-controlled input voltage to a motor;
• a second step of calculating a ratio of voltage applied to the motor to one-cycle input voltage, i.e., a modified voltage value, every phase control cycle, and determining whether the number of rotations of the motor reaches a predetermined number of rotations;
• and
• a third step of adding the modified voltage values calculated at the second step, when the number of rotations of the motor reaches the predetermined number of rotations, to determine the weight of laundry.

A method of detecting laundry weight of a drum type washing machine, comprising:

• a first step of applying input voltage, phase of which is controlled by a triac, to a motor;
• a second step of calculating a ratio of voltage applied to the motor to one-cycle input voltage, i.e., a modified voltage value, every phase control cycle, and determining whether the number of rotations of the motor reaches a predetermined number of rotations;
• and
• a third step of calculating ripples in the number of rotations of the motor for a predetermined period of time, when the number of rotations of the motor reaches the predetermined number of rotations, and detecting the weight of laundry based on the sum of the modified voltage values calculated at the second step and the calculated ripples in the number of rotations of the motor.