Motor control is increasingly demanding a design revisit in home appliances while they acquire greater functionality by using network connectivity and user interface enhancements. The fact that air conditioners, refrigerators, and washing machines are shrinking in size also means that power consumption and high-temperature environments are becoming a critical issue in appliance motor control.
To counter these design concerns, a new breed of microcontrollers is allowing developers to use the motor’s current or rotation rate status data for abnormality detection. These MCUs employ the failure detection results to trigger alarms and even facilitate preventive maintenance.
A design solution built around RX66T microcontrollers from Renesas is a case in point. It can identify the fault locations and determine when repairs and maintenance should be performed.
The RX66T-based Renesas Failure Detection e-AI solution can control up to four motors. A washing machine design, for instance, uses three motors: one to rotate the washing tub, one to drive the water circulation pump, and one to drive the drying fan. So, this embedded system can control as well as monitor all three motors for faults with a single RX66T chip.
Run a set of sample program files on the RX66T microcontroller using a GUI tool to collect and analyze property data indicating motor states. Next, start developing the AI models using specialized tools like e-AI Translator and e-AI Checker.
The e-AI Translator converts the open-source machine learning (ML) and deep learning frameworks such as Caffe and TensorFlow to the MCU/MPU development environment. Then, e-AI Checker employs the output result from the translator to calculate the ROM/RAM size and the inference execution processing time.
Once the AI learning models are complete, you can import them into the RX66T chip and optimize them for fault detection and maintenance functionalities. Your motor-equipped home appliance design is ready for failure detection and predictive maintenance.
Managing Heat and Power
Hot air and heated water are also becoming a crucial factor in home appliances like dishwashers, HVAC systems, and food processors. The circuit boards are increasingly being mounted in high-temperature locations, and as a result, the heat challenge is growing for motor-control applications.
The space constraints further reduce the board’s capacity to disperse heat, demanding efficient heat-tolerance solutions for motor control in home appliances. Here, the MCU-centric embedded solutions are incorporating high-temperature tolerance models for operation in expanded temperature ranges.
For example, the RX24T and RX24U microcontrollers from Renesas claim to support temperatures ranging from -40°C to +105°C while maintaining the connectivity, functionality, and energy-efficiency features. These 32-bit MCUs come with a motor control evaluation kit to enable developers to create and review heat tolerance models in appliance designs.
Energy efficiency is also becoming a vital consideration for motors in home appliances steadily shrinking in the form factor. Home appliances, whether line-operated or battery-driven, also demand their motors to feature protection against over- and under-voltage, over-current, rotor lock, etc.
Infineon’s motor control ICs integrate the company’s proprietary Motion Control Engine to improve motor algorithms, and that enhances the management of variable speed drives across a wide voltage range. The iMOTION chips—targeted at home appliances such as air conditioners, fans, and pumps—also employ predictive algorithms like power factor correction (PFC) to boost the motor-control functionality.