Angle Detector Phase Correction for Motor Drive
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Solution Overview
Problem
Existing angle detection systems in vehicles face errors due to waveforms not passing through zero level points during AD conversion, leading to phase bias and increased angle detection errors when the excitation period approaches an integral multiple of the motor rotation period.
Innovation Solution
An angle detector comprising an AD converter for plural-phase signal waves, a corrector that delays the excitation signal to match the phase difference, a wave detector for synchronous detection, and an angle calculator to estimate the rotation angle, ensuring accurate phase correction and reduced error detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the excitation period approaches an integral multiple of the motor rotation period, then the AD conversion can be performed at regular intervals, but the waveform does not pass through zero level points causing phase bias and angle detection errors
Solution Approach 1:
The patent implements a feedback mechanism where the detected zero-crossing points of the signal wave are used to continuously adjust and correct the phase of the excitation signal. This ensures that even when the excitation period is an integral multiple of the motor rotation period, the system maintains accurate angle detection by dynamically compensating for any phase deviations through continuous feedback from the zero-crossing detection.
Solution Approach 2:
The patent changes the parameter of excitation signal phase dynamically based on detected zero-crossing points. By adjusting the phase parameter of the excitation signal in response to detected waveform characteristics, the system ensures that zero-crossing points are properly detected and angle measurement accuracy is maintained regardless of the relationship between excitation period and motor rotation period.
2Productivity
If the waveform does not pass through zero level points, then the AD conversion completes successfully, but phase bias occurs leading to angle detection errors
Solution Approach 1:
The patent performs preliminary action by detecting zero-crossing points of the signal wave before using them to correct the excitation signal phase. This advance detection and correction ensures that the phase is properly aligned before angle measurement occurs, preventing phase bias from affecting measurement accuracy while maintaining successful AD conversion.
Solution Approach 2:
The system uses feedback from zero-crossing detection to continuously monitor and adjust the excitation signal phase. When zero-crossing points are detected, this information is fed back to correct any phase bias in the excitation signal, ensuring that angle detection accuracy is maintained even when waveform characteristics change during operation.
3Device complexity
If zero-crossing points are not accurately detected, then the system operates without phase correction, but angle detection errors increase
Solution Approach 1:
The patent introduces an intermediary zero-crossing detection mechanism that bridges the excitation signal and the angle measurement process. By detecting zero-crossing points as an intermediate step, the system obtains accurate phase information without significantly increasing overall system complexity, enabling precise angle detection through this intermediate measurement point.
Solution Approach 2:
The system performs self-service by using its own output signals to correct its input signals. The signal wave generated by the system is used to detect zero-crossing points, which then feed back to correct the phase of the excitation signal that generated the waveform in the first place. This self-correcting mechanism improves angle detection accuracy without requiring external calibration equipment.
Data Source
AI summary
Certain embodiments provide an angle detector comprising: an AD converter configured to analog-to-digital convert plural-phase signal waves having respective different phases; a corrector configured to delay a phase of an excitation signal by an amount corresponding to a phase difference between the excitation signal and the signal wave; a wave detector configured to perform synchronous detection to an output signal from the AD converter in synchronization with the excitation signal whose phase is corrected; and an angle calculator configured to calculate an estimated rotation angle using an output signal of the wave detector and output the estimated rotation angle to the AD converter.