Three-Phase Motor Control Using Single Rotor Sensor
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Solution Overview
Problem
Conventional three-phase motor driving apparatuses require multiple expensive rotor sensors, leading to increased manufacturing costs and decreased product yield due to precision requirements, and fail to accurately estimate rotor position when rotation speed varies.
Innovation Solution
A three-phase motor driving method using only one rotor sensor to detect the magnetic pole of a first phase, estimating rotational positions based on reference pulse signals to control the motor driver in sequential driving patterns, allowing for proper estimation of rotor position even with varying rotation speeds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If three rotor sensors are used to detect magnetic poles of three phases, then the rotational position of the rotor can be detected, but the manufacturing cost increases and product yield decreases
Solution Approach 1:
The patent extracts the essential function of rotor position detection from the conventional three-sensor approach and implements it using only one rotor sensor. By taking out the redundant sensors and focusing on detecting only the magnetic pole of one phase, the system achieves the necessary rotational position information while significantly reducing manufacturing cost and improving yield.
Solution Approach 2:
The patent generates virtual detection signals for the remaining two phases by calculating timing information based on the single detected phase and the known 120-degree phase shift relationship. This copying approach creates the necessary control signals without physically installing additional sensors, thereby reducing cost while maintaining detection accuracy.
2Ease of manufacture
If one rotor sensor is used to reduce cost, then manufacturing cost decreases, but the rotational position cannot be properly estimated when rotation speed varies
Solution Approach 1:
The patent implements a dynamic timing calculation method that adapts to varying rotation speeds. Instead of using fixed timing intervals, the system calculates the timing of magnetic poles for other phases based on the actual detected pulse period and the known electrical angle relationships. This dynamic approach ensures accurate rotational position estimation regardless of speed variations.
Solution Approach 2:
The system uses feedback from the single detected phase to continuously update the timing calculations for all three phases. By monitoring the actual pulse period and using it to recalculate the timing of magnetic poles for all phases, the system maintains accurate rotational position information even when rotation speed changes, effectively using feedback to compensate for the reduced sensor count.
3Measurement precision
If three rotor sensors are positioned with high precision, then detection signals are precise, but the yield of products decreases
Solution Approach 1:
The patent removes two of the three rotor sensors, leaving only one sensor that does not require high-precision positioning relative to other sensors. This extraction eliminates the yield-reducing constraint of multi-sensor alignment while maintaining sufficient detection precision through computational timing calculation.
Solution Approach 2:
The patent replaces the mechanical positioning requirement of multiple precision-aligned sensors with a computational system that calculates timing based on electrical angle relationships. This substitution eliminates the need for precise mechanical installation of multiple sensors, thereby improving product yield while maintaining detection accuracy.
Data Source
AI summary
The three-phase motor driving apparatus according to an aspect of the present invention comprises a controlling part that estimates a rotational position of the three-phase brushless motor based on a reference pulse signal output by the rotor sensor according to a rotational position of the magnetic pole of the first phase of the rotor when the three-phase brushless motor rotates, and controls the motor driver in driving patterns sequentially prescribed so as to correspond to the estimated rotational position of the three-phase brushless motor.