Single Phase DC Motor Drive Circuit Back-EMF Direction Detection
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Solution Overview
Problem
Existing single phase DC motor drive circuits face challenges in determining the rotation direction, leading to overcurrent issues and potential burnout due to the need for multiple Hall elements and complex pin connections.
Innovation Solution
A motor drive circuit incorporating a back electromotive force detecting module and processing module to detect and determine the rotation direction of a single phase DC motor using back electromotive force and hall signals, simplifying the design and reducing the number of pins required.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If two Hall elements are used to determine rotation direction, then the rotation direction can be determined, but the device complexity increases and the number of pins required increases
Solution Approach 1:
The patent extracts the rotation direction detection function from the traditional multi-Hall-element approach and implements it through a single Hall element combined with back electromotive force detection. By removing the redundant Hall elements and focusing on detecting the back EMF signal characteristics (polarity and magnitude) in conjunction with Hall signal timing, the system achieves rotation direction determination with reduced device complexity and fewer pins required.
2Measurement precision
If multiple Hall elements are installed, then the rotation direction can be determined, but the pin connections become more complex and inconvenient
Solution Approach 1:
The patent merges the rotation direction detection function into a single Hall element system that works in conjunction with back electromotive force detection. By combining the Hall signal timing information with the back EMF signal characteristics, the system achieves the same rotational direction determination capability as multiple Hall elements but with simplified pin connections and easier operation.
3Reliability
If the motor starts in reverse direction, then the motor cannot be brought back to forward direction, but overcurrent occurs and burns out inner elements
Solution Approach 1:
The patent implements preliminary detection of rotation direction by analyzing the back electromotive force signal characteristics and Hall signal timing before the motor enters a harmful overcurrent state. By detecting the back EMF polarity and magnitude in conjunction with the Hall signal, the system identifies reverse rotation early and can take corrective action before overcurrent occurs and damages the motor elements.
Solution Approach 2:
The patent employs feedback mechanisms where the back electromotive force detection module continuously monitors the motor's back EMF signal and feeds this information to the processing module. This feedback loop, combined with Hall signal timing analysis, enables real-time rotation direction determination and allows the control system to adjust the drive signals accordingly, preventing the motor from entering a harmful reverse rotation state that would cause overcurrent.
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
Effectively determines the rotation direction of the single phase DC motor, preventing overcurrent and reducing the risk of burnout by simplifying the system design and minimizing the number of pins needed in the control circuit.
Implementation Method 1
the back electromotive force detecting module is configured to detect a back electromotive force of the single phase DC motor
Implementation Method 2
a hall signal outputted by a hall element disposed in the single phase DC motor
Data Source
AI summary
A motor drive circuit including a back electromotive force detecting module and a processing module is disclosed herein. The back electromotive force detecting module is electrically connected to a single phase DC motor and is configured to detect a back electromotive force of the single phase DC motor and to output a detecting signal correspondingly. The processing module is electrically connected to the back electromotive force detecting module and the single phase DC motor. The processing module is configured to determine the rotation direction of the single phase DC motor according to the detecting signal and a hall signal outputted by a hall element located in the single phase DC motor, and is configured to control the single phase DC motor.