Washer Motor Control Switching for Efficiency and High-Speed Power
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Solution Overview
Problem
Existing washing machine motor control systems face challenges in achieving high efficiency and high power operation simultaneously, as these modes are typically mutually exclusive, especially during agitate cycles where low currents and temperatures are desired but high power is necessary for reaching top speeds.
Innovation Solution
Implementing a method that switches between different control algorithms, such as Field-Oriented Control (FOC) and Voltage-Frequency (V/Hz) control, while the motor is spinning, allowing for smooth transitions and enabling the motor to operate efficiently at low speeds and deliver high power at high speeds, with optional soft-start features and time delays for AC induction motors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If Field-Oriented Control (FOC) is used to provide efficient motor operation, then motor efficiency is improved, but power delivery at high speeds deteriorates due to max duty cycle limitations
Solution Approach 1:
The system dynamically switches between FOC and V/Hz control algorithms based on operating conditions. At low speeds, FOC provides high efficiency with current monitoring. At high speeds, the system transitions to V/Hz control which removes duty cycle limitations and enables full power delivery without current shunt monitoring.
Solution Approach 2:
The control strategy changes parameters by switching control algorithms based on speed thresholds. The system monitors motor speed and transitions from FOC (efficient at low speeds) to V/Hz (powerful at high speeds), effectively changing the control parameter set to match operational requirements.
2Power
If V/Hz control is used to deliver high power at high speeds, then power delivery is improved, but motor efficiency deteriorates due to lack of current monitoring
Solution Approach 1:
The system dynamically selects control algorithms based on speed requirements. V/Hz control is activated only when high speed power delivery is needed, while FOC handles efficient operation at lower speeds. This dynamic selection optimizes the power-efficiency tradeoff across the operating range.
Solution Approach 2:
The speed range is segmented into different operational zones. Low-speed operations use FOC for efficiency, while high-speed operations use V/Hz for power delivery. This segmentation allows each control algorithm to operate in its optimal performance region.
3Adaptability or versatility
If control algorithm switching is implemented to achieve both efficiency and high power, then operational versatility is improved, but control system complexity increases
Solution Approach 1:
The control system is designed with multi-functionality by integrating both FOC and V/Hz control algorithms in a single controller. This universal controller can adapt to different operational requirements (efficiency-oriented or power-oriented) without requiring separate control systems, thereby managing complexity while providing versatility.
4Stability of the object's composition
If smooth transition between control algorithms is implemented, then operational stability is improved, but transition time increases
Solution Approach 1:
The system prepares for transition by monitoring speed thresholds in advance. When approaching the transition point, the controller begins preparing the alternative control algorithm, ensuring a smooth handoff without abrupt changes. This preliminary preparation minimizes disruption while maintaining stability.
Data Source
AI summary
The present subject matter relates to methods and apparatus for controlling operation of a washing machine motor. Different control algorithms may be used during different time periods of operation of the motor where each algorithm is configured to provide different operating characteristics of the motor based on the needs of the washing machine system. The method and apparatus both provide for changing from one motor control algorithm to another algorithm while the motor is spinning. For certain type motors, a time period may be established between operation of the motor under a first or second control algorithms where no energy is supplied to the motor but the motor is permitted to continue to spin. During this period of time for these type motors, magnetic fields in the motor are permitted to subside prior to application of the second control algorithm.