Motor Control Apparatus Fundamental Wave Angular Acceleration
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Solution Overview
Problem
Existing motor control methods for periodic loads face instability in higher harmonics when fidelity is improved and increased cost due to high current requirements, and inaccuracies in rotor position detection without rotary encoders, leading to potential divergence in speed control.
Innovation Solution
A motor control method that detects the fundamental wave component of angular acceleration and controls voltage or current to reverse its phase relative to the angular acceleration, reduces the amplitude of the fundamental wave component of angular acceleration to zero, and adjusts instrument constants to improve rotor position detection accuracy without rotary encoders.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If fidelity is improved in motor control, then speed control accuracy is improved, but instability is realized in higher harmonics
Solution Approach 1:
The patent extracts only the fundamental wave component of angular acceleration using a band-pass filter, separating it from higher harmonic components. This allows accurate speed control based on the fundamental component while excluding destabilizing higher harmonics from the control loop.
Solution Approach 2:
The control system segments the angular acceleration signal into different frequency components (fundamental wave and higher harmonics) using filtering. The fundamental component is used for control while higher harmonics are excluded, achieving both accuracy and stability.
2Measurement precision
If fidelity is improved in motor control, then current becomes too great, but power devices and motor with great capacity should be employed
Solution Approach 1:
The patent extracts only the fundamental wave component of the angular acceleration signal, excluding higher harmonic components. This reduces the peak current requirements while maintaining effective speed control, allowing the use of smaller power devices and motors.
3Ease of manufacture
If rotor position is detected without rotary encoder using voltage and current, then cost is reduced, but area is generated due to changing instrument constants
Solution Approach 1:
The patent uses feedback from voltage and current measurements combined with instrument constants to detect rotor position. By continuously monitoring the relationship between applied voltage, current, and motor parameters, the system determines rotor position without requiring expensive rotary encoders.
4Stability of the object's composition
If voltage and current are controlled to cancel speed changing, then speed stability is improved, but processing for detecting rotor position is possibly diverged
Solution Approach 1:
The patent extracts only the fundamental wave component of angular acceleration for speed control feedback. By excluding higher harmonic components that could cause divergence, the system maintains speed stability while ensuring reliable rotor position detection convergence.
Data Source
AI summary
A voltage detection section and current detection section detect a voltage and current supplied to a motor, and the detected voltage and current are supplied to a position detection section. An angular speed output from the position detection section is supplied to a differentiator to output an angular acceleration. A fundamental wave component extraction section extracts a fundamental wave component of the angular acceleration, and the extracted fundamental wave component is supplied to an amplitude adjustment section. The output of the amplitude adjustment section is subtracted from the average current command by a subtraction section. This subtraction result, current detection value, and the rotor position from the position detection section are supplied to a current control section to carry out the current control operation so as to obtain a current command. The current command is supplied to an inverter to control the voltage and current so as to suppress the speed changing due to the load torque changing. Thus, stability is improved, and a decrease in cost is realized.