Brushless DC Motor Position Control via Hall Sensor Signal Conversion
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Stepping motors are energy inefficient due to excessive torque requirements and size, while brushless DC motors lack position/hold control without encoders, which can be prone to malfunctions and increase production costs.
Innovation Solution
A control device that includes a motor driving unit and a rotational-position detecting unit, converting magnetic-pole-phase signals into higher-resolution rotational-position detection signals, enabling position/hold control without the need for encoders on the motor or driven object.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a rotary encoder is added onto the output shaft of a brushless DC motor to enable position control, then position/hold control capability is improved, but device complexity and production cost increase due to additional components
Solution Approach 1:
The patent extracts the position detection function from a separate rotary encoder component and integrates it into the brushless DC motor's existing Hall effect sensor system. By utilizing the magnetic pole position information already available from the motor's internal Hall sensors, the system achieves position control without requiring an additional rotary encoder on the output shaft, thereby reducing device complexity while maintaining position/hold control capability
Solution Approach 2:
The patent makes the Hall effect sensors serve multiple functions: they simultaneously perform commutation control for the brushless DC motor operation and position detection for position/hold control. This multi-functionality eliminates the need for separate detection devices, reducing both device complexity and production cost while achieving the desired position control capability
2Ease of operation
If a linear encoder is added onto an object to be driven by a brushless DC motor to enable position control, then position/hold control capability is improved, but device complexity and production cost increase due to additional components
Solution Approach 1:
The patent extracts the position detection function from a separate linear encoder component and integrates it into the brushless DC motor's existing Hall effect sensor system. By utilizing the magnetic pole position information already available from the motor's internal Hall sensors, the system achieves position control without requiring an additional linear encoder on the driven object, thereby reducing device complexity while maintaining position/hold control capability
Solution Approach 2:
The patent replaces the mechanical contact-based linear encoder system with a magnetic field-based detection approach using Hall effect sensors. This substitution eliminates the need for mechanical encoders on the driven object, reducing device complexity and improving reliability while achieving accurate position/hold control through magnetic pole position detection
3Measurement precision
If a detecting device such as an encoder or resolver is provided on an output shaft of a brushless DC motor, then position control precision is improved, but reliability decreases due to malfunction from dust, dirt, or heat
Solution Approach 1:
The patent extracts the position detection function from external detecting devices that are vulnerable to environmental factors and integrates it into the motor's internal Hall effect sensor system. The Hall sensors are positioned within the motor structure where they are protected from dust, dirt, and excessive heat, thereby maintaining position control precision while significantly improving reliability
Solution Approach 2:
The patent nests the position detection function within the existing motor structure by utilizing the Hall effect sensors that are already integrated into the motor assembly. This nested approach allows the detection system to benefit from the motor's protective structure, shielding it from external contaminants and heat while maintaining accurate position detection capability
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 efficient position/hold control for brushless DC motors, reducing energy consumption and production costs by eliminating the need for additional detection devices, and maintaining compatibility with conventional driving systems.
Implementation Method 1
a rotational-position detecting unit that converts the magnetic-pole-phase signal into a rotational-position detection signal and outputs the rotational-position detection signal
Data Source
AI summary
A control device includes a motor driving unit that supplies electric power to a motor according to a magnetic-pole-phase signal output from the motor; and a rotational-position detecting unit that converts the magnetic-pole-phase signal into a rotational-position detection signal and outputs the rotational-position detection signal. The rotational-position detection signal indicates a rotation amount and a rotation direction of an output shaft of the motor and has a higher resolution than the magnetic-pole-phase signal.