A double-drum washing machine has a first washing drum and a second washing drum. A control method comprises water intake and drainage control and high-power process control, wherein the water intake and drainage control comprises water intake control and water drainage control; the first washing drum judges whether to reuse drained water of the second washing drum before executing a water intake process and judges whether to enable the drained water to be drained into the second washing drum and reuse the water or not before executing a water drainage process; and the high-power process control is used for controlling any one of a heating process, a dewatering process and a drying process of the first washing drum and any one of a heating process, a dewatering process and a drying process of the second washing drum not to be executed at the same time.

A washing machine for controlling optimal operating revolutions per minute (rpm) of a drain pump in a draining course and a dehydrating course includes a washing tub; a drain pump configured to drain water in the washing tub; a pump motor configured to operate the drain pump; an inverter circuit configured to supply a driving current to the pump motor to operate the drain pump; and a controller configured to control the inverter circuit to supply reference power to the pump motor in response to starting a draining course, determine reference revolutions per minute (rpm) based on average rpm of the pump motor during a preset period of time, and control the inverter circuit to operate the pump motor at the reference rpm in response to the determining of the reference rpm.

A washing machine for controlling optimal operating revolutions per minute (rpm) of a drain pump in a draining course and a dehydrating course includes a washing tub; a drain pump configured to drain water in the washing tub; a pump motor configured to operate the drain pump; an inverter circuit configured to supply a driving current to the pump motor to operate the drain pump; and a controller configured to control the inverter circuit to supply reference power to the pump motor in response to starting a draining course, determine reference revolutions per minute (rpm) based on average rpm of the pump motor during a preset period of time, and control the inverter circuit to operate the pump motor at the reference rpm in response to the determining of the reference rpm.

Disclosed herein is a drain pump driving apparatus and a laundry treatment machine including the same. The drain pump driving apparatus and the laundry treatment machine including the same according to an embodiment of the present invention include a motor to operate the drain pump, an inverter to convert a direct current (DC) power to an alternating current (AC) power by a switching operation and output the converted AC power to the motor, an output current detector to detect an output current flowing to the motor, and a controller to control the inverter, wherein the controller may calculate a speed ripple of the motor based on the output current and performs a control operation based on the calculated speed ripple of the motor to change a speed of the motor.

A control unit comprises a calculation unit, a determination unit, and a motor rotation control unit. The calculation unit calculates the rate of change in water level, which indicates the amount of change in water level per a predetermined period of time, on the basis of the result of sensing by a water level sensor in connection with a water supply stroke. The determination unit determines whether laundry having a waterproof property is contained in a drum or not on the basis of the rate of change in water level during the water supply stroke calculated by the calculation unit. When it is determined that laundry having a waterproof property is contained in the drum, the motor rotation control unit controls the operation of a driving motor such that the drum is rotated at a predetermined number of rotations or less during the dewatering stroke.

Disclosed is a drain pump driving apparatus and a laundry treatment machine including the same. The laundry treatment machine includes: a drain pump driving apparatus configured to drive a drain pump, wherein the drain pump driving apparatus includes: a motor to drive the drain pump; an inverter to convert a direct current (DC) power to an alternating current (AC) power by a switching operation, and output the converted AC power to the motor; an output current detector to detect an output current flowing to the motor; and a controller configured to control the inverter, wherein the controller is further configured to calculate a speed of the motor based on an output current, and calculate a lift, which is a difference between a water level of a water introduction part through which water flows into the drain pump and s water level of a water discharge part for discharging water from the drain pump, based on the calculated speed.

Disclosed is a drain pump driving apparatus and a laundry treatment machine including the same. The laundry treatment machine includes: a drain pump driving apparatus configured to drive a drain pump, wherein the drain pump driving apparatus includes: a motor to drive the drain pump; an inverter to convert a direct current (DC) power to an alternating current (AC) power by a switching operation, and output the converted AC power to the motor; an output current detector to detect an output current flowing to the motor; and a controller configured to control the inverter, wherein the controller is further configured to calculate a speed of the motor based on an output current, and calculate a lift, which is a difference between a water level of a water introduction part through which water flows into the drain pump and s water level of a water discharge part for discharging water from the drain pump, based on the calculated speed.

The present invention relates to a washing machine (7) and pump (8) for a washing machine (7). The pump is driven by a brushless DC motor (38). The pump can be controlled to improve the operation of the washing machine. In one aspect the invention comprises a washing machine (7) with a variable speed pump (8) for pumping out wastewater, a controller (50) for controlling the speed of the pump and a sensor (10) for determining the flow-rate of water being pumped from the washing machine, wherein the controller (50) controls the speed of the pump to maintain the flow-rate at a desirable level.

A multi-drum washing machine drainage control method, the multi-drum washing machine at least comprising a first washing drum and a second washing drum; the method comprising: when the first washing drum reaches a drainage process, determining whether the second washing drum is draining; if yes, then the first washing drum waits for the second washing drum to finish draining before starting to drain; and if not, then determining whether the first washing drum waits for the second washing drum to finish draining before starting to drain. Alternatively, when the first washing drum reaches the drainage process, determining whether the second washing drum is draining or dehydrating; if yes, then the first washing drum waits for the second washing drum to finish draining before starting to drain; and if not, then determining whether the first washing drum waits for the second washing drum to finish draining before starting to drain.

A washing machine appliance includes a sump for collecting wash fluid and a water supply valve for supplying the wash fluid during a fill cycle. A controller is configured for detecting when a pressure sensor of a water level detection system is partially blocked and implementing an incremental fill process. Specifically, the controller is configured for determining a remaining fill volume for the wash fluid to reach the target fill volume, opening the supply valve to provide a fraction of the remaining fill volume into the sump and then closing the supply valve, determining that a sump pressure measured by the water level detection system has stabilized, and repeating these steps until a stopping criterion occurs, such as when a fill cycle limit or a target volume is achieved.