Motor Duty Cycle Modulation for Stable Speed Limiting
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Solution Overview
Problem
Conventional motor controllers limit motor rotational speed, leading to unstable or abnormal operations, which affects the efficiency of cooling heat-generating components in electronic devices.
Innovation Solution
A motor rotational speed control system with a duty cycle variable modulation mechanism, utilizing a rotational speed detector and motor driver to modulate duty cycles of waveforms in an on-time signal to stabilize motor speed within a set limit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If conventional motor controller is used to limit rotational speed, then rotational speed can be controlled, but motor operation becomes unstable or abnormal
Solution Approach 1:
The patent applies dynamics by making the duty cycle adjustable and variable rather than fixed. The control circuit dynamically modifies the duty cycle of PWM signals based on motor operating conditions, allowing the motor controller to adapt to changing loads and maintain stable operation across different speed ranges. This dynamic adjustment resolves the instability issue caused by conventional fixed-duty-cycle controllers.
Solution Approach 2:
The patent changes the duty cycle parameter dynamically to resolve the contradiction. By varying the duty cycle based on feedback from current detection and speed sensing, the system maintains optimal motor operation while limiting rotational speed. This parameter change approach allows the controller to prevent abnormal operations while achieving speed control.
2Speed
If duty cycle is fixed for speed control, then speed limitation is achieved, but motor cannot adapt to varying conditions
Solution Approach 1:
The patent implements feedback mechanisms where the control circuit continuously monitors motor current, voltage, and rotational speed. Based on this feedback, the system automatically adjusts the duty cycle to maintain optimal performance under varying conditions while respecting speed limits. This feedback loop enables the motor to adapt to changing loads, temperatures, and operational requirements.
Solution Approach 2:
The system transitions from static duty cycle control to dynamic duty cycle adjustment. The control circuit modifies PWM duty cycles in real-time based on motor operating conditions, enabling the motor to adapt to varying loads and environmental conditions while maintaining speed limitation through coordinated control of multiple PWM signals.
3Productivity
If rotational speed is limited to appropriate value, then cooling efficiency is improved, but motor operation stability deteriorates
Solution Approach 1:
The patent changes the duty cycle parameter dynamically to resolve the contradiction between cooling efficiency and motor stability. By adjusting the duty cycle based on real-time motor conditions, the system maintains the motor within stable operating parameters while achieving the required speed limitation for efficient cooling. This prevents the instability that would otherwise occur with simple speed limiting.
Solution Approach 2:
The control system uses feedback from current sensors and speed sensors to continuously monitor motor operation. When the motor approaches speed limits required for optimal cooling efficiency, the feedback mechanism triggers duty cycle adjustments that maintain stability. This ensures the motor operates stably at the speed required for maximum cooling efficiency.
Data Source
AI summary
A motor rotational speed control system and method having a duty cycle variable modulation mechanism is provided. The motor rotational speed control system is performed by the motor rotational speed control system including a motor rotational speed detector and a motor driver. When a rotational speed of a motor detected by the motor rotational speed detector is larger than or equal to a set rotational speed, the motor driver modulates duty cycles of a plurality of waveforms of an on-time signal, and modulates a duty cycle difference between the duty cycle of each of the plurality of waveforms and the duty cycle of a previous one or every other one of the plurality of waveforms in the on-time signal. The motor driver, according to the on-time signal, drives the motor such that the rotational speed of the motor is limited to be smaller than the set rotational speed.