Resonant Drive Circuit for Inductive Position Coil Voltage Control
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Solution Overview
Problem
Conventional inductive position transducers face limitations in speed, resolution, and reduced transducer signal output due to the inductance of the drive coil not participating in determining the oscillation frequency, leading to suboptimal performance.
Innovation Solution
An inductive position transducer system with a drive circuit comprising a resonant circuit portion and an amplifier portion, including a current-driven single stage differential amplifier, is used to drive the field generating coil, with a controller adjusting the bias current to maintain a specified voltage level across the coil.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by stationary object
If a conventional intermittent drive circuit is used to supply a time-varying drive signal to the field generating coils, then power consumption is reduced, but speed and resolution are limited
Solution Approach 1:
The patent employs periodic action by using an intermittent drive circuit that charges a capacitor and then discharges it through the field generating coil in repeated cycles. This periodic charging and discharging creates time-varying drive signals that excite the coil to ring at its resonant frequency, achieving both energy efficiency and improved measurement precision compared to continuous drive circuits.
2Device complexity
If the inductance of the drive coil does not participate in determining the oscillation frequency, then circuit design is simplified, but signal output is detrimentally reduced
Solution Approach 1:
The patent applies feedback by configuring the intermittent drive circuit so that the oscillation frequency is determined by the resonant frequency of the field generating coil, which depends on its inductance. The circuit monitors and adjusts the discharge timing based on the coil's natural oscillation, ensuring that the drive frequency matches the resonant frequency. This feedback mechanism maximizes signal output while maintaining relatively simple circuit design.
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 achieves higher coil voltages, improved signal resolution, and enhanced measurement accuracy by optimizing the impedance matching and power dissipation in the stray resistance, resulting in stronger magnetic fields and reduced noise interference.
Implementation Method 1
The resonant circuit portion comprises at least a first resonant circuit portion component, a second resonant circuit portion component, and a third resonant circuit portion component... The resonator portion comprising at least the resonant circuit portion and the first field generating coil has a resonant frequency... providing an oscillating drive signal at the first and second resonant circuit portion nodes
Implementation Method 2
Inductive position transducers are widely used to measure relative displacements between one or more sensing elements and one or more disrupting elements that modulate the inductive coupling between the sensing elements and a field generating coil
Data Source
AI summary
An inductive position transducer system includes a drive circuit and an inductive position transducer with at least a first field generating coil. The drive circuit includes a resonant circuit portion and an amplifier portion. The amplifier portion comprises a current-driven single stage differential amplifier and is configured to provide an oscillating drive signal to the resonant circuit portion which results in a driving of the field generating coil (e.g., at a coil voltage which may be larger than a power supply voltage, such as over 2× larger). A controller may adjust a bias current that is provided to the amplifier portion to maintain the voltage across the field generating coil (e.g., at a specified voltage level). The amplifier portion may comprise CMOS transistors and may be fabricated on a chip (as part of a low-voltage CMOS integrated circuit) along with other portions of the inductive position transducer system.