Brushless DC Motor Phase Control via Auxiliary Coil Back-EMF
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Solution Overview
Problem
Conventional motor systems with Hall sensing elements face performance degradation and increased volume and cost due to sensing errors, making integration into electronic apparatus challenging.
Innovation Solution
A motor system without a Hall sensing element, utilizing a primary coil and an auxiliary coil to determine phase switching time points, with a motor controller that includes a switch circuit, current detecting unit, and voltage detecting unit to generate control signals for phase switching, allowing the auxiliary coil to replace the Hall sensing element.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a Hall sensing element is used to detect rotor position, then the motor controller can switch phases, but sensing errors occur and performance degrades
Solution Approach 1:
The patent removes the Hall sensing element from the motor system entirely. Instead of using external Hall sensors to detect rotor position, the system extracts position information from the back-EMF voltage generated by the auxiliary coil during motor operation. This extraction approach eliminates the sensing errors associated with Hall elements while maintaining phase switching capability.
Solution Approach 2:
The patent introduces an auxiliary coil as an intermediary element that generates a voltage signal proportional to the rotor position. This auxiliary coil acts as a mediator between the rotor's magnetic field and the control system, providing accurate position information without requiring separate sensing elements. The voltage from the auxiliary coil serves as an intermediate representation of rotor position that the controller can use for precise phase switching.
2Ease of operation
If a Hall sensing element is installed for rotor position detection, then phase switching can be controlled, but the volume and cost of the motor system increase
Solution Approach 1:
The patent merges the position sensing function with the existing coil structure by adding an auxiliary coil that serves dual purposes: it participates in the motor's magnetic circuit and simultaneously generates the position detection signal. This consolidation eliminates the need for separate Hall sensing elements and their associated mounting space, reducing overall system volume while maintaining full phase control capability.
Solution Approach 2:
The auxiliary coil performs multiple functions within the motor system. It contributes to the magnetic field generation like the main coils while simultaneously serving as the position sensing element. This multi-functionality reduces the total number of components needed, thereby reducing system volume and complexity while preserving ease of operation for phase control.
3Ease of operation
If a Hall sensing element is installed for rotor position detection, then phase switching can be controlled, but the cost of the motor system increases
Solution Approach 1:
The patent replaces expensive Hall sensing elements with a simpler auxiliary coil structure that can be manufactured using standard winding processes. The auxiliary coil uses the same materials and manufacturing techniques as the main coils, making it a cost-effective solution that eliminates the need for specialized sensing components and reduces overall manufacturing cost while maintaining phase control capability.
Solution Approach 2:
The patent changes the approach from using external sensing elements to using the electrical parameters (voltage) generated by the auxiliary coil for position detection. By utilizing the natural back-EMF voltage produced during motor operation, the system eliminates the need for additional sensing components and their associated costs, achieving phase control through parameter extraction rather than component addition.
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
This solution enables accurate phase switching without Hall sensing elements, reducing system volume and cost while maintaining motor performance, suitable for single-phase brushless DC motors.
Implementation Method 1
The winding may surround the stator for driving the rotor based on the magnetic induction resulting in the variation of the magnetic field
Data Source
AI summary
The present invention discloses a motor system without a hall sensing element. The motor system comprises a first output pin, a second output pin, an auxiliary pin, a stator, a rotor, a primary coil, and an auxiliary coil. Both the primary coil and the auxiliary coil surround the stator. The primary coil is coupled to the first output pin and the second output pin. The auxiliary coil is coupled to the auxiliary pin. The auxiliary coil is configured to determine a phase switching time point. The motor system detects the zero point of the voltage of the auxiliary pin, so as to detect the position of the rotor and determine the phase switching time point.