Brushless DC Motor Position Determination Circuit
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Solution Overview
Problem
The high cost of dedicated position sensors, such as LVDT or RVDT, for determining the position of actuators in brushless DC motor systems poses a significant challenge, especially in applications where accurate closed-loop position control is required.
Innovation Solution
A position determination circuit utilizing a commutation sensor, pulse generator, and integrator circuit to generate a position signal representative of the actuator's position, eliminating the need for a dedicated sensor by leveraging the rotational position signal from the brushless DC motor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a dedicated position sensor (LVDT or RVDT) is used to determine actuator position, then measurement precision and reliability are improved, but device cost increases significantly
Solution Approach 1:
The commutation sensor originally designed for motor control is made to serve dual purposes: motor commutation control and actuator position determination. By processing the commutation sensor's rotational position signal through a pulse generator and integrator circuit, the system extracts position information without requiring a separate dedicated position sensor, thus reducing system cost while maintaining measurement capability
Solution Approach 2:
The system uses its own existing commutation sensor to provide position information that would otherwise require a separate sensor. The commutation sensor's output signal is processed through the pulse generator and integrator to generate position feedback, allowing the system to serve its own position measurement needs without external dedicated sensors
2Manufacturing precision
If a second position sensor is added to supply position feedback signal, then closed-loop position control accuracy is improved, but device complexity and cost increase
Solution Approach 1:
The commutation sensor is made multi-functional by using it for both motor commutation and position feedback. The pulse generator converts the commutation signal into position information, and the integrator accumulates position data to provide closed-loop feedback, eliminating the need for a second dedicated position sensor while maintaining control accuracy
Solution Approach 2:
The pulse generator and integrator circuit act as intermediary components that transform the commutation sensor's rotational position signal into useful position feedback information. These intermediary circuits enable the existing commutation sensor to provide the position feedback function that would otherwise require a separate sensor
Data Source
AI summary
A position determination circuit uses the commutation sensor of a brushless DC motor to determine the position of an actuator and/or actuated component 125. The commutation sensor supplies a rotational position signal representative of the rotational position of the motor to a pulse generator. The pulse generator generates a pulse each time the rotational position signal represents a complete revolution of the brushless DC motor. The generated pulses are supplied to an integrator circuit, which selectively supplies a position signal having a voltage magnitude representative of the position of the actuator and/or component.