Motor Speed Control Circuit with Sharp Jump Threshold
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Solution Overview
Problem
Existing motor control technologies cannot achieve sharp jumps in rotation speed from low speed or static state at a specific duty cycle, limiting their application in fans and Central Process Units (CPUs).
Innovation Solution
A device and method utilizing a reference voltage generating module, PWM signal converting module, comparator, switching element, and follower to control motor speed, enabling the motor to jump to a high speed when the duty cycle exceeds a predetermined threshold, by switching between a predetermined speed and speed controlled by the duty cycle.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional motor control methods are used, then the motor rotation speed changes gradually, but the inability to achieve sharp speed jumps limits application flexibility
Solution Approach 1:
The patent applies preliminary action by pre-setting a reference voltage threshold that corresponds to the desired duty cycle threshold. When the PWM-derived voltage signal crosses this pre-set threshold, the comparator immediately triggers a switching action, enabling the motor speed to jump sharply to a predetermined high speed without gradual transition. This pre-configured threshold mechanism allows the system to achieve application-flexible speed jumps in fans and CPUs.
2Adaptability or versatility
If a switching mechanism is introduced to enable sharp speed jumps, then rotation speed control flexibility improves, but the device complexity increases
Solution Approach 1:
The patent uses a comparator as an intermediary device that simplifies the control architecture. The comparator continuously compares the PWM-derived voltage signal with a reference voltage and automatically generates switching signals when the threshold is crossed. This intermediary mechanism eliminates the need for complex microcontroller-based threshold detection and switching logic, thereby achieving speed control flexibility without significantly increasing device complexity.
Solution Approach 2:
The control circuit is segmented into distinct functional modules: PWM signal conversion module, voltage comparison module, and switching control module. Each module performs a specific function, making the overall system easier to design, analyze, and implement. This segmentation allows the sharp speed jump functionality to be achieved through simple modular components rather than a complex monolithic circuit.
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
Enables the realization of desired rotation speed control curves with sharp jumps, providing more flexible and diverse control over motor speed, eliminating hysteresis phenomena and ensuring accurate speed control.
Implementation Method 1
a first comparator having a positive terminal connected with the reference voltage generating module and a negative terminal connected with the PWM signal converting module, and configured to output a first level when a voltage of the voltage signal converted from the PWM signal is less than or equal to the reference voltage, and to output a second level when the voltage of the voltage signal converted from the PWM signal is greater than the reference voltage
Implementation Method 2
a first switching element having a control terminal connected with an output terminal of the first comparator and a first terminal input with a first signal, and configured to be turned on when receiving the second level output from the output terminal of the first comparator so as to enable a connection between a first terminal and a second terminal of the first switching element, and to be turned off when receiving the first level output from the output terminal of the first comparator
Implementation Method 3
a PWM signal converting module configured to convert a PWM signal into a voltage signal corresponding to a duty cycle of the PWM signal
Data Source
AI summary
The present application discloses a device, method and system for controlling a rotation speed of a motor. The device includes: a reference voltage generating module generating a reference voltage; a PWM signal converting module converting a PWM signal into a voltage signal; a first comparator outputting a first level or a second level; a first switching element having a control terminal connected with an output terminal of the first comparator and a first terminal input with a first signal, and being turned on when receiving the second level and being turned off when receiving the first level; a follower having an input terminal connected with the PWM signal converting module; and a control signal outputting terminal outputting the first signal or the voltage signal. The device, method and system are capable of controlling the rotation speed of the motor to jump at a specific duty cycle.