High Speed AC Sensor Phase Measurement Circuit
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Solution Overview
Problem
Existing high-speed electronic measurement circuits for determining the voltage and phase shift of AC signals in resolvers, LVDTs, and proximity sensors require at least a full cycle of the sinusoidal waveform, making them slow to respond to rapidly changing parameters.
Innovation Solution
A high-speed electronic measurement circuit that determines the voltage and phase shift using two samples of a sinusoidal waveform spaced π/2 radians apart, applying trigonometric substitutions to calculate the root-mean-square value and phase shift in less than a half-cycle.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional algorithms requiring a full cycle of sinusoidal waveform are used, then measurement precision is maintained, but measurement speed deteriorates
Solution Approach 1:
The patent applies partial action by using only a portion of the sinusoidal waveform cycle (specifically, sampling at two points separated by π/2 radians) rather than requiring a full cycle. This allows phase measurement to be completed in less than half a waveform cycle, significantly improving measurement speed while maintaining sufficient precision through trigonometric calculations based on the sampled values.
2Measurement precision
If algorithms requiring detection of zero crossings are used, then phase shift calculation accuracy is improved, but response time increases
Solution Approach 1:
The patent implements preliminary action by pre-calculating the relationship between sinusoidal waveform values and phase angles using trigonometric substitutions. Instead of waiting for zero crossings to occur and then calculating phase, the system uses the sampled values directly in trigonometric formulas (such as atan2 functions) to determine phase shift, eliminating the time delay associated with waiting for zero crossings.
3Speed
If high-speed measurement in less than half waveform cycle is implemented, then system responsiveness is improved, but measurement complexity increases
Solution Approach 1:
The patent replaces traditional mechanical or analog measurement methods (such as zero-crossing detection circuits and full-cycle integration) with digital signal processing techniques. By using digital sampling and trigonometric substitutions in software or digital logic, the system achieves high-speed measurement without the complexity of specialized analog circuitry, leveraging the computational power of digital systems instead.
Data Source
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AI summary
A system for determining a phase angle of a sensor waveform relative to an excitation waveform includes a controller (104) that provides an excitation signal having an excitation frequency and a sample signal having four times the excitation frequency. An exciter provides a sinusoidal excitation waveform at the excitation frequency to a primary winding (126), thereby inducing a sensor waveform in a secondary winding (124). An analog-to-digital converter (ADC) (114) measures a first and second voltage of the sensor waveform separated in time by the period of the sample frequency, and a wrap-around ADC (166) measures a first and second voltage of the sinusoidal excitation waveform. The first voltage measurements are made at the same time, and the second voltage measurements are made at the same time. The system calculates the phase angle based on the first voltage measurements and the second voltage measurements.