The efficiency of driving motors low power consumption and miniaturization have a significant role in the design of washing machines. A valuable input for a range of semiconductor products for power supply units, motor driving units, control units, sensor signal input units, etc. It is along with circuit configuration examples. Let us understand the role of Semiconductors in Washing Machine.
What is MCU?
Microcontrollers (MCUs) are used in motor control, analog sensor measurement, front panel keypad control, and LED/LCD display. The home appliance industry mostly applies 8-, 16-, and 32-bit microcontroller-based circuitry for motor control and TRIAC/LED/LCD drive application. The MCU controls all features and functions of the appliance by the user pressing the start button and input from the front panel keyboard goes to the microcontroller as the MPU turns on the three-phase Brushless DC (BLDC) motor/permanent magnet synchronous motor (PMSM). The variation and control of the motor speed are based on the user’s input from the front panel keypad.
The MCU has an internal or external serial EEPROM (I2C/SPI) for old data storage. Provides real-time information for a system clock (RTC) for timekeeping. Temperature measurement can be done using an onboard resistance temperature detector (RTD), thermistor, or thermocouple-based temperature-sensing device.
What is PSoCs?
PSoCs are also very useful in applications in which a capacitive-sensing technology uses touch-based keypads to replace mechanical buttons. This greatly reduces the instances of failures inherent with mechanical buttons, while offering a much better overall reliability of the product.
Many SoCs have production-ready libraries and design tools that auto-tune sensitivity of buttons and sliders. Thus, avoiding manual tuning in the design cycle. Capacitive-based interfaces must also be waterproof in-home appliance solutions. They can sense proximity for the front keypad, activating it when the user places their hand near the keypad. Using a touchscreen-based design on the front panel, instead of an LCD display with keypad, would provide a very good user interface in addition to flexibility.
Use in Washing Machine
The MCU receives numerous types and numbers of analog inputs from an external ADC, which processes signals from various sensors attached to the washing machine. These sensors include the water hardness sensor, humidity sensor, door open sensor, laundry load sensor, optical sensor, detergent density sensor, imbalance load sensor, volume sensor, and water level sensor. It measures temperature using an onboard RTD and stores data in external EEPROM for customized wash programs, memory backup, child lock, and favorites. Thus, the microcontroller allows the washing machine to adjust the water and cuts off the power automatically.
It also controls the self-diagnostics, including failure in water supply, spin failure, drainage failure, child lock, overflow protection, and door lid open. Clocks and timers are used in implementing sleep mode with other normal condition delay-start operations. A buzzer (PWM-based) generates tones at different frequencies and also provides overload alert tones. Power billing is reduced by having the machine automatically turned off after the completion of washing.
Semiconductors in Washing Machine would definitely benefit from fault detection and recovery mechanisms. Other requirements include power supply design with protections against battery, over-current, overheating, and starting fail conditions. Self-diagnostics implementation is another design challenge.
