Motor Rotor Alignment Using Periodic AC Current
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Solution Overview
Problem
Existing motor control methods for home appliances, such as washing machines, face challenges with vibration and noise during initial position alignment, which affects detection accuracy and operational efficiency due to the use of DC current for sensorless control.
Innovation Solution
A motor control system that applies a first and second waveform current with varying magnitudes to the stator of the motor to align the rotor position, reducing vibration and noise, and accurately detecting stator resistance through voltage measurement, thereby stabilizing motor operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If DC current is applied to align the rotor position, then the initial position detection accuracy is improved, but vibration and noise are generated
Solution Approach 1:
The patent applies periodic AC current instead of DC current for rotor alignment. The AC current is applied in multiple cycles with varying frequencies, creating a rotating magnetic field that aligns the rotor without causing continuous vibration and noise. The periodic nature of AC current allows the rotor to align smoothly through magnetic attraction while minimizing harmful mechanical vibrations.
Solution Approach 2:
The patent changes the current parameters from DC to AC with specific frequency characteristics. By using AC current with frequencies below a predetermined threshold and applying it in multiple cycles, the alignment process achieves accurate rotor positioning while reducing vibration and noise. The parameter change from constant DC to variable-frequency AC resolves the contradiction between detection accuracy and harmful vibrations.
2Measurement precision
If DC current is applied for alignment, then the rotor position can be detected, but the alignment time increases operation duration
Solution Approach 1:
The patent applies AC current in multiple periodic cycles for rotor alignment. By using periodic AC current application with optimized frequency and cycle count, the alignment process achieves accurate rotor position detection more efficiently than traditional DC current methods. The periodic action allows for faster convergence to the correct rotor position while maintaining detection accuracy.
Solution Approach 2:
The patent uses AC current with specific frequency characteristics to rush through the alignment process more quickly. By applying AC current at optimized frequencies and cycles, the system achieves rapid rotor alignment without the prolonged operation time associated with DC current methods, effectively skipping through the alignment phase efficiently.
3Measurement precision
If voltage error exists in detection, then measurement accuracy deteriorates, but stator resistance detection becomes unreliable
Solution Approach 1:
The patent employs feedback mechanisms to detect and compensate for voltage errors during AC current application. By continuously monitoring the voltage and current parameters during the alignment process and using this feedback to calculate stator resistance, the system maintains high measurement accuracy and reliable resistance detection even in the presence of voltage errors. The feedback loop allows for real-time correction of measurement inaccuracies.
Solution Approach 2:
The patent replaces traditional resistance measurement methods with a calculation-based approach using AC current characteristics. Instead of direct DC resistance measurement prone to voltage errors, the system calculates stator resistance from AC voltage and current parameters, substituting a more reliable electrical measurement method that is less susceptible to voltage errors and provides more accurate results.
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
The system effectively aligns the rotor position without causing vibration or noise, reduces alignment time, and accurately detects stator resistance, leading to stable and precise motor control.
Implementation Method 1
a first waveform current and a second waveform current having a magnitude varying with time are applied to a stator of the motor before operating the motor
Implementation Method 2
the stator resistance is detected based on a result of a voltage measurement according to each application result
Data Source
AI summary
Disclosed is about an apparatus, a system, and a method aligning a position of a rotor by applying a specific current to align the rotor a plurality of times to reduce vibration and noise when starting an operation of the motor to align the position of the rotor.