Motor Rotor Position Estimation Without Preliminary Rotation
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Solution Overview
Problem
Conventional position estimation methods for motor rotors are hindered by the need for absolute angle position sensors, which are large and costly, and struggle to estimate initial rotational positions, particularly in applications like robots and unmanned transport vehicles where preliminary rotation is not allowed.
Innovation Solution
A method and device that estimate the rotational position of a motor rotor using learning data acquired through a process involving magnetic sensors and signal processing, allowing for the determination of the rotor's initial position without requiring preliminary rotation, by dividing the learning period into quadrants and sections based on digital and analog signals from multiple sensors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If an absolute angle position sensor is used to accurately control rotor position, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The patent creates a virtual absolute angle position sensor by using multiple incremental angle position sensors to detect magnetic field signals at different phases. Through coordinate transformation and calculation, these multiple simple sensors collectively provide the functionality of a single complex absolute sensor, achieving the same measurement precision without the complexity and cost of an absolute angle position sensor
Solution Approach 2:
The patent makes the incremental angle position sensors serve multiple functions: they not only detect incremental position changes but also, through coordinated operation and signal processing, enable absolute position determination. This multi-functionality eliminates the need for separate absolute sensing hardware, reducing device complexity while maintaining measurement precision
2Device complexity
If conventional position estimation method is used, then device complexity is reduced, but initial position estimation fails in applications where preliminary rotation is not allowed
Solution Approach 1:
The patent performs preliminary calibration operations during the motor manufacturing or assembly phase, where the rotor can be freely rotated. During this calibration, the relationship between the signals from multiple incremental sensors and the actual absolute position is established and stored as correction data. This preliminary action enables the system to reliably determine initial position later without requiring additional rotation operations
Solution Approach 2:
The patent introduces a correction value or calibration data as an intermediary element that bridges the gap between incremental sensor readings and absolute position. This intermediary data, obtained during preliminary calibration, allows the system to accurately determine initial position even when the motor cannot rotate during normal operation, thus improving reliability without increasing device complexity
3Measurement precision
If preliminary rotation is performed to estimate initial position, then position estimation accuracy is improved, but driving time and power consumption increase
Solution Approach 1:
The patent performs the time-consuming position calibration operation once during manufacturing or assembly, rather than requiring it during each operational cycle. This preliminary calibration establishes the necessary correction data that enables rapid initial position determination during normal operation, eliminating the need for repeated preliminary rotations and thus reducing driving time and power consumption
4Measurement precision
If preliminary rotation is performed to estimate initial position, then position estimation accuracy is improved, but power consumption increases
Solution Approach 1:
The patent performs the energy-consuming calibration process once during manufacturing or assembly when the motor is stationary or can be freely rotated. The calibration data obtained during this one-time operation enables accurate initial position determination during normal operation without requiring additional energy expenditure for preliminary rotations, thus reducing overall power consumption
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 accurate estimation of the rotor's initial position without the need for preliminary rotation, reducing driving time and power consumption, and is suitable for applications where initial position adjustment is not feasible.
Implementation Method 1
N1 first magnetic sensors opposed to the magnet and arranged along a rotation direction of the magnet... N2 second magnetic sensors opposed to the rotor and arranged along a rotation direction of the rotor
Data Source
AI summary
One aspect of a position estimation method of the present invention includes: a learning step of acquiring learning data necessary for estimation of a rotational position of a rotor on the basis of an input sensor signal; and a position estimation step of estimating the rotational position of the rotor on the basis of the input sensor signal and the learning data. The learning step is performed, thereby acquiring, as the learning data, data indicating the correspondence relationship between a segment number associated with a section included in each of a plurality of quadrants and a pole pair number representing a pole pair position. The position estimation step is performed, thereby determining an initial position of the rotor on the basis of the input sensor signal and the learning data.