Motor Control Using Sector Duration Ratios for Rotor Position
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Solution Overview
Problem
Existing motor control systems, particularly for DC and multi-phase motors, face challenges in accurately determining rotor position due to non-ideal sensor placements and magnetic pole errors, leading to inefficiencies and torque ripple, especially when using Hall-effect sensors.
Innovation Solution
A motor controller that measures the duration of each electrical sector during a mechanical rotation, calculates sector duration ratios, and stores them in a table to accurately predict rotor angle and speed, minimizing torque ripple and noise while maintaining efficient torque production.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If Hall-effect sensors are used for rotor position measurement, then maximum torque at zero speed is achieved, but hardware complexity and wiring increase
Solution Approach 1:
The patent creates a virtual model of the motor's electrical sectors by measuring duration ratios and storing them in a table. This virtual representation allows the system to predict rotor position without physical sensors, eliminating the need for Hall-effect sensors while maintaining torque control capability through software-based position estimation
Solution Approach 2:
The patent replaces the mechanical sensor-based measurement system with an electronic/software-based duration ratio measurement system. By measuring the time duration of electrical sectors and calculating ratios, the system substitutes physical Hall-effect sensors with electronic timing and computation, reducing hardware complexity while maintaining position measurement accuracy
2Measurement precision
If traditional sector duration measurement is used, then rotor position is tracked, but torque ripple and noise increase due to non-ideal sensor placement
Solution Approach 1:
The patent implements feedback by measuring actual electrical sector durations, comparing them against stored duration ratios from previous cycles, and using this information to accurately determine rotor position. This feedback mechanism allows the system to compensate for non-ideal sensor placement and magnetic pole errors, reducing torque ripple and noise while maintaining precise position estimation
Solution Approach 2:
The patent changes the approach from direct sensor angle reading to measuring time duration parameters of electrical sectors. By measuring the duration of each electrical sector and calculating ratios between measured and stored durations, the system transforms the position measurement problem into a time-based parameter comparison, which is more robust to sensor placement variations and reduces torque ripple
3Measurement precision
If duration ratios are calculated and stored in a table for each sector, then rotor position prediction accuracy improves, but memory requirements and processing complexity increase
Solution Approach 1:
The patent performs preliminary action by measuring and storing the duration ratios of electrical sectors in a table during an initial phase or first operational cycle. This pre-stored reference data is then used for subsequent position predictions, eliminating the need for complex real-time calculations and reducing processing complexity during normal operation while maintaining high position prediction accuracy
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
The solution provides precise rotor position estimation, reducing torque ripple and noise, and enhancing motor efficiency by accurately predicting rotor angle changes and maintaining optimal flux relationships between rotor and stator, even in non-ideal conditions.
Implementation Method 1
A motor controller that measures the duration of each electrical sector during a mechanical rotation... particularly when using Hall-effect sensors
Data Source
AI summary
A motor control determines if a motor is rotating at steady state velocity and then populates a table with information about each individual motor sector. At steady state velocity, the duration of the motor within an electrical sector is measured. The duration of the complete mechanical rotation of the motor is determined. The controller determines a ratio of the measured duration of the sector to a duration of a complete mechanical rotation of the motor. The ratio of sector duration to rotation duration is stored in a table. The controller is configured for controlling the motor using the table values.