Inductive Angular Position Sensor With Non-Resonant Excitation
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Solution Overview
Problem
Inductive angular position sensors face challenges in achieving faster measurement and reducing power consumption while maintaining operational life, particularly when operating on battery power.
Innovation Solution
The use of a non-resonant driver to switch an exciter coil between voltage terminals generates a triangular-shaped excitation current, and a difference encoder compares receiver coil voltages to determine angular position, eliminating the need for resonant circuits and reducing energy waste.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a resonant driver is used to generate sinusoidal excitation current, then the sensor can operate continuously, but the measurement speed is slower and power consumption is higher
Solution Approach 1:
The patent employs periodic pulsed excitation instead of continuous sinusoidal excitation. The exciter coil is driven by periodic voltage pulses that generate triangular-shaped current bursts, allowing the system to take measurements at specific intervals rather than continuously. This periodic action reduces average power consumption while maintaining measurement capability at required speed intervals.
Solution Approach 2:
The patent changes the waveform parameter from sinusoidal to triangular-shaped current. This is achieved by using a non-resonant driver with pulse-width modulation to generate triangular current bursts instead of sinusoidal waves. The triangular waveform enables faster rise and fall times, improving measurement speed while the pulsed nature reduces overall power consumption.
2Measurement precision
If continuous measurements are taken to track angle and turn-count, then measurement accuracy is maintained, but power consumption increases and operational life decreases
Solution Approach 1:
The system performs measurements periodically at optimized intervals rather than continuously. The control unit triggers measurement cycles at specific rates, allowing the sensor to maintain accurate angle and turn-count tracking while consuming power only during measurement intervals. This extends battery-operated operational life while preserving measurement precision through adequate sampling frequency.
Solution Approach 2:
The patent maintains continuous tracking capability through periodic measurements that capture sufficient data points to continuously update angle and turn-count values. By strategically spacing measurements, the system ensures that useful action (measurement) continues at sufficient frequency to maintain accuracy without the waste of truly continuous operation.
3Productivity
If a non-resonant driver with triangular-shaped current is used, then measurement speed increases and power consumption decreases, but the excitation waveform is non-sinusoidal
Solution Approach 1:
The patent deliberately changes the excitation waveform from sinusoidal to triangular-shaped through the use of a non-resonant driver with pulse-width modulation. This parameter change enables faster switching and measurement cycles, improving productivity. The triangular waveform's sharp edges allow for quicker establishment of magnetic fields and faster measurement completion.
Solution Approach 2:
The triangular-shaped excitation current is applied in periodic bursts rather than continuous sinusoidal waves. This periodic triangular excitation allows the system to complete measurements faster during each pulse while reducing overall power consumption, thereby increasing measurement throughput without requiring sinusoidal waveforms.
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
This approach allows for faster and more power-efficient angle measurements, extending the operational life of the sensor by conserving energy and enabling operation in a low-power mode using battery power.
Implementation Method 1
a rotor coil configured to couple a magnetic field generated by the excitation current to the plurality of receiver coils according to an angle-dependent inductive coupling between the rotor coil and the plurality of receiver coils
Implementation Method 2
couple a magnetic field generated by the excitation current to the plurality of receiver coils according to an angle-dependent inductive coupling
Data Source
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AI summary
An inductive sensor may track an angle of a movable element. In some cases, it is desirable to operate the inductive sensor using battery power so that turns are tracked properly even when power is lost. The disclosed inductive sensor includes circuitry to conserve power, such as a non-resonant driver that allows for fast measurements without wasting energy and a difference encoder that can estimate the angle within a range without the need for digitization and complicated processing.