Resolver Interface Phase Detection for Lower CPU Overhead
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Solution Overview
Problem
Conventional resolver interface systems consume a significant number of instruction cycles for computing shaft angle, with the arc tan function typically exceeding 100 cycles and accounting for around 40% of the total resolver function implementation, necessitating an improvement in computational efficiency.
Innovation Solution
A resolver interface system utilizing phase-analog techniques with dual excitation signals applied to stator windings and phase detectors, coupled with differentiators and timers, to determine the rotor shaft angle independently of the CPU, reducing computational overhead.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional arc tan function computation is used to determine shaft angle, then measurement precision is achieved, but processing time increases significantly consuming 40% of instruction cycles
Solution Approach 1:
The patent replaces the software-based arc tan computation with a hardware-based phase detection system. Phase detectors and timers are used to directly measure phase differences and compute shaft angle through hardware circuitry, eliminating the need for CPU-intensive mathematical functions and significantly reducing processing time while maintaining measurement precision.
Solution Approach 2:
The patent introduces phase detectors as intermediary components between the resolver output and the shaft angle computation. These phase detectors convert the analog resolver signals into phase difference measurements that can be processed by timers and counters, providing an intermediate representation that enables faster computation without sacrificing accuracy.
2Measurement precision
If CPU-based arc tan computation is used, then shaft angle can be determined, but CPU overhead increases reducing computational resources availability
Solution Approach 1:
The patent substitutes CPU-based software computation with dedicated hardware circuits including phase detectors, timers, and counters. This hardware implementation performs shaft angle determination independently of the CPU, freeing computational resources for other tasks while maintaining precise angle measurement capability.
Solution Approach 2:
The patent implements a self-service system where the phase detection and angle computation occur autonomously through hardware circuits without requiring continuous CPU intervention. The timer and counter automatically measure phase differences and compute angles based on input signals, making the system independent of CPU availability and improving overall productivity.
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 system significantly reduces CPU overhead by utilizing high-end timer functions and dual phase detectors, allowing for efficient computation of the shaft angle without relying on the CPU, thus conserving computational resources.
Implementation Method 1
a resolver having a first excitation input, a second excitation input and a rotation signal output
Data Source
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AI summary
A resolver interface system for a motor drive system includes a phase detector (114a, 114b) configured to be operatively connected to a rotation signal output of a resolver (102) to receive a rotation signal therefrom and generate a phase difference signal. A differentiator (116a, 116b) is operatively connected to an output of the phase detector to convert the phase difference signal of the phase detector into a pulse output configured to be read by a processing system (120).