Motor Unit Controller Using Segmented Control Stages
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Solution Overview
Problem
In motor starting, the large difference between target and actual rotation numbers leads to detection errors and delays, causing overshoot and prolonged stabilization time due to rapid rotation increases, especially when using low-resolution sensors.
Innovation Solution
A motor unit with a controller that employs multiple calculators and a pulse generator to generate pulse signals based on control values, using a constant pattern at the initial stage to gradually increase rotation, followed by PI control stages to adjust and stabilize the rotation, thereby avoiding rapid increases and ensuring accurate detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If feedback control is performed using actual rotation number detected by sensor, then rotation control accuracy is improved, but detection error and detection delay increase at low rotation speeds
Solution Approach 1:
The control process is segmented into multiple control stages (first control stage, second control stage, third control stage) with different control strategies. The first control stage uses open-loop control without feedback, the second control stage introduces feedback control, and the third control stage uses feedback control with rotation number limitation. This segmentation allows the system to avoid using unreliable sensor detection at low speeds while still achieving accurate control at higher speeds.
Solution Approach 2:
The system performs preliminary open-loop control in the first control stage before entering feedback control. During this preliminary stage, the rotation number is increased from zero to a predetermined value without relying on sensor detection, thereby avoiding detection errors and delays that would occur if feedback control were applied immediately at low speeds.
2Speed
If PI control is applied to increase rotation number from zero, then target rotation is reached, but overshoot occurs causing rapid rotation increase and impact on motor
Solution Approach 1:
The control process is divided into multiple stages with different control strategies. The first control stage uses open-loop control to gradually increase rotation without overshoot. The second control stage introduces PI control only after the rotation has reached a safe level. The third control stage adds rotation number limitation to prevent overshoot. This segmentation prevents the instability that would occur if PI control were applied directly from zero rotation.
Solution Approach 2:
The system applies preliminary open-loop control to establish a safe operating baseline before introducing feedback control. This preliminary action prevents the conditions that would lead to overshoot and instability, by ensuring the motor is already rotating at a controlled pace before feedback mechanisms engage.
3Stability of the object's composition
If feedback control waits for natural deceleration after overshoot, then rotation stabilizes, but starting time is prolonged
Solution Approach 1:
The control process is segmented into three stages that progressively introduce feedback control mechanisms. The second control stage introduces PI control at an optimal point to prevent overshoot, and the third control stage adds rotation number limitation. This segmentation allows the system to achieve both stability and reduced starting time by avoiding the need to wait for natural deceleration after overshoot.
Solution Approach 2:
The system performs preliminary open-loop control to establish a safe operating baseline before introducing feedback control. This preliminary action prevents overshoot from occurring in the first place, thereby eliminating the need to wait for natural deceleration and significantly reducing the overall starting time while maintaining stability.
4Measurement precision
If multiple control stages with different calculators are used, then rotation control accuracy is improved, but device complexity increases
Solution Approach 1:
The controller is segmented into multiple calculators (first calculator, second calculator, third calculator) that each handle specific control tasks. The first calculator performs open-loop control, the second calculator performs PI control, and the third calculator performs rotation number limitation. This segmentation improves control accuracy by dedicating specific computational resources to specific control functions, while the modular structure makes the complexity manageable.
Solution Approach 2:
The controller dynamically switches between different calculators and control strategies based on the current operating stage. The pulse generator selectively outputs pulse signals based on control values from different calculators depending on the stage. This dynamic adaptation allows the system to achieve high control accuracy across different operating conditions while keeping the overall structure flexible and manageable.
Data Source
AI summary
A motor unit includes a motor, a controller that outputs a pulse signal, a driver that supplies a drive current to the motor based on the pulse signal, and a detector that determines an actual rotation number of the motor. The controller includes calculators that calculate control values of a rotation number of the motor, and control stages. The controller also includes a pulse generator that selects one of the control values calculated by the calculators to generate the pulse signal based on the control value selected, at each of the control stages.