Fan Motor Rotation Locking System with Lookup Table Compensation
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Solution Overview
Problem
The challenge lies in precisely controlling the rotational speed of fan motors to efficiently cool heat-generating components in electronic devices, as the inertial force of the fan makes it difficult to achieve the target rotational speed due to incorrect duty cycles in the driving signal, leading to inefficiencies.
Innovation Solution
A rotation locking system comprising a speed detector circuit, closed-loop control circuit, lookup table arithmetic circuit, driver circuit, and speed feedback control circuit that compensates the duty cycle signal based on current and target rotational speeds, using a lookup table to calculate and apply a compensation duty cycle to ensure the motor reaches and maintains the target speed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the duty cycle of the driving signal is adjusted to control the rotational speed of the motor, then the rotational speed can be changed, but the inertial force of the fan causes the rotational speed to deviate from the target speed
Solution Approach 1:
The patent implements a feedback mechanism by detecting the current rotational speed of the motor and comparing it with the target rotational speed. Based on the speed difference, the system adjusts the duty cycle of the driving signal to compensate for inertial effects. This closed-loop control ensures that the fan reaches and maintains the target rotational speed accurately despite inertial forces.
Solution Approach 2:
The patent applies preliminary action by pre-calculating and storing compensation duty cycle values in a lookup table based on different speed transitions. When a speed change is required, the system retrieves the appropriate compensation value in advance, allowing the motor to anticipate and counteract inertial effects before they cause significant deviation from the target speed.
2Measurement precision
If the duty cycle is compensated multiple times to account for inertial force, then the target rotational speed can be reached more accurately, but the control system becomes more complex
Solution Approach 1:
The patent reduces control system complexity by pre-calculating compensation duty cycle values and storing them in a lookup table. Instead of performing complex real-time calculations, the system simply retrieves the appropriate compensation value based on the current and target speeds, significantly simplifying the control logic while maintaining high precision.
Solution Approach 2:
The patent transforms the complex inertial compensation problem into a simpler parameter lookup operation. By representing compensation values as discrete parameters in a lookup table, the system avoids complex mathematical computations during runtime, reducing both computational complexity and control system complexity while maintaining accuracy.
3Device complexity
If the duty cycle signal does not account for inertial force, then the control system is simpler, but the fan cannot reach or maintain the target rotational speed efficiently
Solution Approach 1:
The patent maintains relatively simple control system architecture while improving productivity by using a lookup table to store pre-calculated compensation values. This approach adds minimal complexity to the control system but significantly improves the fan's ability to reach and maintain target rotational speeds, thereby enhancing cooling efficiency without substantially increasing system complexity.
Solution Approach 2:
The patent introduces compensation parameters based on inertial force characteristics, transforming the duty cycle signal from a basic speed control parameter to an optimized parameter that accounts for inertial effects. This parameter enhancement allows the system to achieve better cooling efficiency through more accurate speed control without requiring a fundamentally more complex control architecture.
Data Source
AI summary
A rotation locking system of a motor of a fan is provided. A closed-loop control circuit outputs an initial duty cycle signal according to a current rotational speed and a target rotational speed. A driver circuit outputs a driving signal to the motor to drive the motor to rotate according to the initial duty cycle signal. A lookup table arithmetic circuit looks up, from a lookup table, two reference duty cycles correspond to two reference rotational speeds that are respectively equal to the current rotational speed and the target rotational speed. The lookup table arithmetic circuit calculates a difference between the two reference duty cycles. A speed feedback control circuit compensates the initial duty cycle signal according to the difference to output a final duty cycle signal to the driver circuit. The driver circuit drives the motor to rotate according to the final duty cycle signal.