Fully automatic washer-extractors, as the most practical industrial washing machines, are widely used in various fields of the laundry industry, such as hotels, hospitals, schools, laundry facilities, dyeing plants, and industrial laundry rooms. Fully automatic washer-extractors utilize frequency converters for speed regulation, ensuring smooth and seamless speed control, which offers significant advantages.

There are five main methods for motor speed regulation:

Mechanical Speed Regulation: This method includes electromagnetic clutches, fluid couplings, and fluid viscous couplings. Among them, fluid couplings are the most widely used. They connect a fluid coupling device between the motor and the load, adjusting the coupling force between the motor and the load by the level of the fluid, thereby achieving speed regulation. However, due to limitations in speed range (30% to 99%), insufficient speed regulation accuracy, low efficiency, and the inability to be used in tandem with other machines and requiring downtime for repairs in case of malfunctions, the usage of this method is narrow.

Cascade Speed Regulation: This method requires the use of wound rotor asynchronous motors. It involves diverting some energy from the rotor winding through rectification, inversion, and then sending it back to the power grid, effectively adjusting the rotor's internal resistance and changing the motor's slip. Due to the voltage difference between the rotor and the power grid, an additional transformer is needed for inversion. To save on this transformer, the internal feedback motor form is commonly used, with an auxiliary three-phase winding on the stator specifically designed to accept feedback energy from the rotor. By doing so, the main winding's energy absorption from the power grid decreases, achieving energy-saving speed regulation. However, since wound motor usage in industrial production is limited, the application scope of this method is narrow.

Slip Motor Speed Regulation: Also known as electromagnetic speed regulation asynchronous motors or slip motors, these are AC variable-speed motors controlled by a constant torque through DC electromagnetic slip. They have numerous advantages, including a wide speed range, smooth speed adjustment, high starting torque, small control power, speed feedback, and a hard mechanical characteristic.

DC Motor Speed Regulation: A DC motor speed controller adjusts the speed of a DC motor. Due to the characteristics of DC motors with low speed and high torque, they cannot be replaced by AC motors. The controller alters the average current power on the load by changing the duty cycle of the output square wave, thereby changing the motor speed. Its advantages include efficient energy utilization, high circuit efficiency, a wide speed adjustment range, fast dynamic response, smooth automatic transitions during acceleration and deceleration, high torque at low speeds, excellent excavator characteristics, and automatic limiting of overload current to a set current during low-speed operation.

Frequency Conversion Speed Regulation: Frequency conversion speed regulation adjusts motor speed by altering the supply frequency through a frequency converter, thereby improving the operating efficiency of electrical transmission systems. Frequency conversion speed regulation is the best speed control technology in terms of speed regulation effectiveness, with the widest speed range (100% to 5%) and the highest speed regulation accuracy (±0.5%). It allows for stepless speed regulation, enabling soft motor startups and full automatic control of the entire production system. Compared to other speed regulation methods, frequency conversion speed regulation is the optimal choice. It boasts high efficiency, a wide speed adjustment range, smooth adjustment, soft startup to avoid grid impact, the ability to regulate multiple motors with a single frequency converter, continued operation on mains power in case of faults without affecting production, and significantly enhances process control and production efficiency. As the most ideal speed control device, it is widely used in fully automatic washer-extractors. It enables seamless speed regulation and smooth rotation, serving as the best tool for motor energy conservation and increasingly favored by users.