Rotor Position Transducer Offset Measurement Using PWM Phase Walking
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Solution Overview
Problem
Current methods for measuring rotor position transducer (RPT) signal offset in electrical machines are cumbersome, time-consuming, and prone to errors due to assembly tolerances, requiring disassembly and manual adjustments.
Innovation Solution
A method using a rotary encoder or software encoder algorithm with PWM control to systematically determine RPT signal offset by gradually shifting voltage phases and recording encoder readings to calculate precise angular positions, allowing for accurate and efficient measurement without disassembly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If manual disassembly and reference point marking methods are used to measure RPT signal offset, then measurement can be performed, but the process becomes time-consuming and cumbersome
Solution Approach 1:
The patent replaces manual mechanical operations (disassembly, marking reference points, physical rotation) with an automated electronic measurement system. The controller automatically energizes stator phases, detects rotor position through RPT signals, and calculates offset angles without human intervention, thereby reducing measurement time while maintaining accuracy.
Solution Approach 2:
The measurement system is self-contained and automated. The controller automatically performs all measurement steps: energizing stator phases in sequence, detecting rotor locked positions through RPT signal transitions, calculating offset angles, and storing results. The system serves itself without requiring external manual operations for each measurement cycle.
2Measurement precision
If manual rotation and oscilloscope monitoring methods are used to identify RPT signal falling edges, then offset measurement can be obtained, but human error increases and efficiency decreases
Solution Approach 1:
The patent replaces manual oscilloscope monitoring and visual detection with automated electronic signal detection. The controller directly reads RPT signal transitions through electronic circuits, automatically identifies falling edges, and computes offset angles programmatically, eliminating human error and increasing measurement speed.
Solution Approach 2:
The system implements automated feedback loops where the controller continuously monitors RPT signals, detects phase transitions, and adjusts measurements based on real-time signal feedback. This automated feedback mechanism ensures accurate detection of falling edges and reliable offset calculation without manual intervention.
3Measurement precision
If complex manual procedures including disassembly and reassembly are used, then RPT signal offset can be measured, but device complexity and operational difficulty increase
Solution Approach 1:
The patent extracts the essential measurement function from the complex manual procedure. Instead of requiring disassembly and physical manipulation, the system isolates the measurement task to electronic signal detection and processing, removing unnecessary mechanical steps while preserving measurement accuracy.
Solution Approach 2:
The measurement system is self-contained and automated. The controller automatically performs all measurement steps: energizing stator phases in sequence, detecting rotor locked positions through RPT signal transitions, calculating offset angles, and storing results. The system serves itself without requiring external manual operations for each measurement cycle.
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 faster, more accurate measurement of RPT signal offset, reducing human error and improving measurement efficiency by using controlled voltage walks and encoder readings to determine precise rotor pole positions.
Implementation Method 1
A magnetic ring 6 mounted on the rotor shaft 4 excites a Hall-effect magnet sensor 8 mounted on the electric circuit board (not shown) to generate rotor position information for motor control software.
Data Source
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AI summary
A method for measuring a Rotor Position Transducer (RPT) signal offset with respect to reference points in the rotor-stator geometry in an electrical machine comprising pairs of adjacent phases; the method comprising the steps of applying a PWM controlled voltage of a predetermined maximum duty cycle value to a first phase, and simultaneously applying a PWM controlled voltage of a predetermined minimum value to a phase adjacent the first phase; subsequently applying a PWM walk-up step, and subsequently applying a walk-down step, and repeating the walk-up and walk-down for each pair of adjacent phases, and when RPT signal transition occurs, using encoder means, such as a software encoder, to determine the RPT signal offset for each rotor pole.