Rotation Position Phase Detection Using Velocity-Synced Counters
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Solution Overview
Problem
Existing phase difference detection devices using two counters suffer from low precision due to delay in outputting detected phase differences, which can change significantly before being output, and errors from noise, especially at high rotation velocities.
Innovation Solution
A phase difference detection device with a reference counter synchronized with a clock pulse, a velocity detection unit, a pulse conversion unit, and a phase count unit that latches and outputs the count value when the detection signal reaches the reference phase, allowing for precise phase detection by adjusting the pulse interval based on rotation velocity and direction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the frequency of the excitation signal is raised to prevent counter reset before latching, then the measurement reliability is improved, but the device complexity increases
Solution Approach 1:
The invention divides the phase detection process into two separate counters: a first counter for detecting phase difference during the first half-cycle of the excitation signal, and a second counter for detecting phase difference during the second half-cycle. This segmentation allows each counter to operate independently with shorter measurement intervals, preventing the counter reset problem without requiring excessive increase in excitation signal frequency.
Solution Approach 2:
The invention implements periodic resetting of counters synchronized with the excitation signal cycles. The first counter is reset at the start of the first half-cycle and the second counter is reset at the start of the second half-cycle, creating a periodic measurement rhythm that ensures accurate phase difference detection without requiring the excitation signal frequency to be excessively high.
2Measurement precision
If two counters are used to detect phase difference for each cycle, then the measurement precision is improved, but the device complexity increases
Solution Approach 1:
The phase detection function is segmented into two counters operating on different half-cycles of the excitation signal. The first counter handles the first half-cycle and the second counter handles the second half-cycle, allowing continuous phase detection with improved precision while distributing the computational load and avoiding the need for more complex single-counter solutions.
Solution Approach 2:
The invention performs preliminary action by resetting the first counter before the first half-cycle begins and resetting the second counter before the second half-cycle begins. This ensures that each counter is ready to accurately measure the phase difference from the start of its respective half-cycle, improving measurement precision through proper initialization timing.
3Device complexity
If phase difference is detected by adding up rotation velocities, then the device complexity is reduced, but the measurement precision deteriorates due to noise and errors
Solution Approach 1:
The invention replaces the mechanical integration method (adding up rotation velocities over time) with a direct electronic phase difference measurement approach using counters and latch circuits. This substitution eliminates the accumulation of errors and noise inherent in iterative velocity addition, providing more accurate phase detection while maintaining relatively simple device complexity.
Data Source
AI summary
A phase difference detection device able to detect a phase with a high precision is provided. A phase difference detection device 4 detecting a phase difference θ between an excitation signal Ss and a second detection signal Sd in accordance with a rotation position θ of a rotary body 101 has a reference counter 13 performing a count in synchronization with a first clock pulse CLK1 and reset when the excitation signal Ss causes zero cross down, a velocity detection unit 19 acquiring information capable of specifying the rotation velocity of the rotary body 101, a pulse conversion unit 21 outputting a second clock pulse CLK2 by using, as a pulse interval Tp, a time specified based on the information acquired by the velocity detection unit 19 and required for the rotation of the rotary body 101 by an angle corresponding to 1 count of the reference counter 13, and a phase counter 23 in which a count value counted by the reference counter 13 is set at an initial value for each fall of a second detection signal Sd, and which performs count in synchronization with the second clock pulse CLK2.