Sinusoidal Motor Control Angle Shift Compensation
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Solution Overview
Problem
Motorized window treatments face challenges in achieving efficient motion and reduced noise due to speed oscillations and torque ripple caused by linear and nonlinear control systems, particularly in sinusoidally driven motors, which result in audible noise and inefficiency.
Innovation Solution
A motor control system that uses a position detector and controller to maintain a fixed frequency sinusoidal motor control signal, adjusting the amplitude based on angle shifts between the motor control signal and feedback signal to maintain an angle shift threshold, thereby minimizing noise and maximizing efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If linear control methods are used to control the motor, then system reliability and torque output are improved, but speed oscillations occur causing audible noise
Solution Approach 1:
The patent implements feedback control by continuously monitoring the actual motor speed and comparing it with the reference speed. The speed error is fed back to the controller to adjust the control signals, thereby eliminating speed oscillations and reducing audible noise while maintaining system reliability.
Solution Approach 2:
The patent changes the control parameter from direct torque control to speed-based control. By monitoring and controlling motor speed directly and adjusting the control signal based on speed error, the system eliminates speed oscillations caused by traditional linear control while maintaining reliable operation.
2Adaptability or versatility
If nonlinear control systems are used to modify output by changes in input, then dynamic subtleties under certain operating regions are improved, but system complexity increases and total convergence cannot be guaranteed
Solution Approach 1:
The patent uses parameter changes by switching between different control modes based on operating conditions. The controller adjusts control parameters dynamically - using high-frequency switching when speed error is large and sinusoidal control when speed error is small - providing adaptability without requiring complex nonlinear control algorithms.
Solution Approach 2:
The patent segments the control process into different stages based on speed error magnitude. When speed error exceeds a threshold, high-frequency switching control is applied; when it's within the threshold, sinusoidal control is used. This segmentation provides adaptability while keeping each control mode simple.
3Speed
If the frequency of the sinusoidal waveform is changed to maintain constant output speed under load, then speed control is improved, but torque ripple and timing errors occur
Solution Approach 1:
The patent changes the control approach from frequency modulation to amplitude modulation. Instead of changing the frequency of the sinusoidal waveform to control speed, the system maintains a fixed frequency and adjusts the amplitude (duty cycle) of the control signal based on speed error, thereby maintaining timing accuracy while achieving speed control.
Solution Approach 2:
The patent implements feedback control where the actual motor speed is continuously monitored and compared with the reference speed. The control signal amplitude is adjusted based on the speed error feedback, maintaining constant output speed without the timing errors and torque ripple associated with frequency changes.
4Measurement precision
If Hall Effect sensors are used to determine rotor position, then position detection is improved, but sensor placement accuracy requirements increase causing constant lag and shift in sinusoidal waveform
Solution Approach 1:
The patent implements self-service by using the motor's own back-EMF signals to detect rotor position. The controller analyzes the back-EMF waveform characteristics to determine rotor position and adjust control timing, eliminating the need for precise Hall Effect sensor placement and reducing manufacturing precision requirements.
Solution Approach 2:
The patent replaces the mechanical sensor-based position detection system with an electrical field-based detection method. By using back-EMF signals and electrical commutation timing, the system substitutes physical sensor placement with electrical measurement, thereby reducing sensitivity to mechanical manufacturing tolerances.
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 solution effectively reduces noise and maintains efficient motor operation by locking the frequency and dynamically adjusting the amplitude of the motor control signal, ensuring constant speed and energy efficiency without affecting the motor's frequency or speed.
Implementation Method 1
Hall Effect sensors 106a-c are generally placed around the rotor 102 for each phase control to track the position of the rotor 102 and provide feedback to the controller 110
Implementation Method 2
Current is run through the phase windings 105a-c in alternating directions in a sequence such that the permanent magnet poles follow the revolving magnetic field that is caused by the windings
Data Source
AI summary
An angle shift compensation system and method for controlling a sinusoidally driven motor to achieve efficient motion and reduced noise. The motor controller uses the angle shift compensation method to monitor the angle shift between a sinusoidal motor control signal configured to drive the motor and a feedback signal received from at least one position detector indicating the position of the motor rotor with respect to the motor stator. In response, the motor controller proportionally adjusts the amplitude of the motor control signal based on the monitored angle shift to maintain the angle shift substantially equal to an angle shift threshold.