Complementary PCB Coil Switch Current Sensing Without Reset Circuits
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Solution Overview
Problem
Existing switch current sensors using integrator circuits face challenges with output droop and offset bias at high frequencies, making it impractical to design auxiliary reset circuits for high-frequency applications in power electronics.
Innovation Solution
The use of complementary PCB-embedded coil pairs with non-inverting and inverting integrator circuits cancels output offset drift, allowing operation at high frequencies without auxiliary reset circuits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If integrator circuits are used in switch current sensors, then current measurement capability is provided, but output droop and offset bias occur at high frequencies
Solution Approach 1:
The sensor is divided into multiple independent integrator circuits (first integrator circuit and second integrator circuit) that process signals separately and then combine results. This segmentation allows each integrator to be optimized for specific frequency ranges and reduces the impact of individual integrator drift on overall measurement accuracy.
Solution Approach 2:
The patent uses complementary coil pairs with opposite winding directions to create counterbalancing magnetic flux paths. The first coil and second coil are configured such that their offset drifts are equal in magnitude but opposite in polarity, allowing the drifts to cancel each other out when signals are combined, thereby compensating for integrator circuit imperfections.
2Measurement precision
If auxiliary reset circuits are added to compensate for output droop, then measurement accuracy improves, but device complexity increases
Solution Approach 1:
The sensor system performs self-compensation for offset drift through the complementary coil configuration and signal processing algorithm. The dual-coil arrangement with opposite polarities automatically generates counterbalancing signals that eliminate the need for external reset circuits, allowing the system to correct its own measurement errors without additional active components.
Solution Approach 2:
The patent extracts and eliminates the need for auxiliary reset circuits by using the complementary coil configuration. Instead of adding complex reset circuitry to correct integrator drift, the design removes the source of drift imbalance through symmetric coil pairing and differential signal processing.
3Speed
If high-frequency operation is implemented, then switching speed improves, but output offset drift increases
Solution Approach 1:
The complementary coil pairs are wound in opposite directions to create magnetic flux paths that generate equal but opposite offset drifts at high frequencies. When the signals from both coils are combined, the high-frequency offset drifts cancel each other, maintaining output stability even during rapid switching operations.
Solution Approach 2:
The patent inverts the winding direction of one coil relative to the other, creating a mirror-image magnetic coupling configuration. This inversion ensures that any offset drift generated by parasitic elements in one coil is counterbalanced by an equal and opposite drift from the other coil, stabilizing the output during high-frequency operation.
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 provides large detection bandwidth and high slew rate in compact configurations, effectively compensating for output offset drift and maintaining accurate current measurements in power electronics devices.
Implementation Method 1
a first-type integrator circuit coupled to a first coil, a second-type integrator circuit coupled to a second coil
Data Source
AI summary
A switch current sensor includes a summing circuit, at least one first-type switch current sensor subcircuit and configured to be coupled at a first input to a conductor, and coupled at a first output to the summing circuit, and at least one second-type switch current sensor subcircuit configured to be coupled at a second input to the conductor and coupled at a second output to the summing circuit. The summing circuit is configured to aggregate the first output of the at least one first-type switch current sensor subcircuit and the second output of the at least one second-type switch current sensor subcircuit to obtain a voltage waveform that is proportional to a switch current configured to flow in the conductor, the voltage waveform including a DC component and steady-state AC components of the switch current.