U-Shaped Single-Phase PM Motor Control Using Back-EMF Estimation
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Solution Overview
Problem
U-shape single phase synchronous permanent magnetic motors (U-SPSPM) in home appliances like dishwashers and washing machines face challenges with sensorless control due to cogging torque and inability to estimate rotor position without sensors, leading to inefficient power regulation and reduced motor performance.
Innovation Solution
A method and circuit that estimate rotor position using feedback signals of voltage and current, with a microcontroller-based observer model to determine back electromotive force (back-EMF) for sensorless control, allowing for precise control of the motor without physical position sensors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a Hall sensor is used to obtain rotor position information, then the motor can be controlled in unidirectional rotation and optimal power regulation is achieved, but the cost increases due to sensor and wiring expenses
Solution Approach 1:
The patent extracts the rotor position detection function from the physical Hall sensor and implements it through software-based back-EMF estimation. The observer model extracts position information from voltage and current measurements without requiring additional hardware sensors, thereby eliminating sensor and wiring complexity while maintaining control reliability.
Solution Approach 2:
The patent replaces the mechanical/electrical sensor system with a computational model. The observer model uses mathematical relationships between voltage, current, and back-EMF to substitute the physical sensor's function, achieving sensorless control that eliminates hardware complexity while preserving motor control capabilities.
2Reliability
If a Hall sensor is used to obtain rotor position information, then unidirectional rotation control is achieved, but the required space increases for adding sensor and circuitry
Solution Approach 1:
The patent removes the physical sensor components from the system and extracts only the essential function of rotor position detection through computational estimation. This eliminates the need for additional space to accommodate sensors and their associated circuitry while maintaining unidirectional rotation control capability.
3Reliability
If a Hall sensor is used to obtain rotor position information, then precise motor control is achieved, but energy consumption increases
Solution Approach 1:
The patent replaces the power-consuming sensor hardware with a computational observer model that processes existing voltage and current measurements. This substitution eliminates the continuous power consumption associated with physical sensors while maintaining precise rotor position estimation and motor control.
4Device complexity
If only voltage signal is used for sensorless control, then hardware complexity is reduced, but rotor position information is estimable only when current equals zero
Solution Approach 1:
The patent introduces current measurement as an intermediary variable that enables continuous rotor position estimation. By combining voltage and current measurements through the observer model, the system achieves accurate position estimation across all operating conditions, not just when current is zero, while maintaining simple hardware requirements.
Solution Approach 2:
The patent enhances the computational model to process both voltage and current signals, substituting the need for complex hardware with a more sophisticated software algorithm. This allows continuous position estimation under all operating conditions while keeping the hardware simple.
5Device complexity
If voltage-only detection method is used, then hardware costs are reduced, but maximum output power and maximum torque cannot be achieved
Solution Approach 1:
The patent uses current measurement as an intermediary that provides the additional information needed to achieve maximum power and torque. The combination of voltage and current signals in the observer model enables accurate position estimation that allows the motor to operate at its full capability, unlike voltage-only methods.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables efficient and unidirectional rotation of U-SPSPM motors by estimating rotor position with high fidelity, independent of AC power source frequency, thereby improving motor performance and reducing energy consumption and hardware costs.
Implementation Method 1
Estimating a position of the rotor by estimating a back electromotive force (back-EMF) based on an observer model with inputs indicative of the measured feedback signals
Data Source
AI summary
A method and circuit for controlling or starting a U-shape single phase synchronous permanent magnetic motor (U-SPSPM motor) having a rotor and a stator and coupled to a single phase alternating current (AC) power source through a switch, including estimating back electromotive force (back-EMF) of the motor based on an observer model with inputs indicative of the measured signals, and triggering the switch to supply power to the motor based on the estimates of the back-EMF.