Rogowski Coil Current Sensing for Fast Converter Protection
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Solution Overview
Problem
Current sensors for power electronic converters are often costly, large, and have slow response times with significant losses, making them inefficient for protection and control purposes.
Innovation Solution
A system comprising a power switching circuit with high-bandwidth current sensor circuits using Rogowski coils and a digital signal processor (DSP) to measure and reconstruct drive current signals, enabling accurate and rapid current sensing by sampling midpoints of high-side and low-side pulses and generating output currents based on duty cycles, thus avoiding inaccurate sensing and power losses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If traditional current sensors are used in power electronic converters, then current sensing is achieved, but the sensors are costly, large, have slow response and large losses
Solution Approach 1:
The patent segments the current sensing function into two separate high-bandwidth current sensor circuits, each measuring current through one switch (high-side and low-side). This segmentation allows each sensor to operate independently at high bandwidth, avoiding the compromises of traditional single-sensor approaches and enabling fast response times while maintaining low losses through efficient Rogowski coil design.
Solution Approach 2:
The patent replaces traditional magnetic core-based current sensors with Rogowski coils, which use air cores and rely on electromagnetic induction without ferromagnetic materials. This substitution eliminates the bandwidth limitations and losses associated with magnetic cores, achieving high-speed response and low power losses simultaneously.
2Measurement precision
If traditional current sensors are used in power electronic converters, then current sensing is achieved, but the sensors are costly and large
Solution Approach 1:
The patent replaces bulky magnetic core structures with compact Rogowski coils that use air cores and flexible wiring. This substitution dramatically reduces sensor size and cost while maintaining high measurement precision through accurate electromagnetic induction and digital signal processing.
Solution Approach 2:
The patent uses two separate current sensor circuits to measure high-side and low-side currents independently, creating accurate copies of the actual switch currents. These copied signals are then processed digitally to reconstruct the full current waveform, achieving high measurement precision without requiring a single large complex sensor.
3Speed
If traditional current sensors are used in power electronic converters, then current sensing is achieved, but the response is slow
Solution Approach 1:
The patent replaces magnetic core-based sensors with Rogowski coils that have no magnetic saturation effects and minimal inductance, enabling extremely fast response times. The air-core design eliminates the bandwidth limitations of ferromagnetic materials while digital signal processing maintains measurement precision through accurate reconstruction of current waveforms.
Solution Approach 2:
The patent implements dynamic current sensing by continuously measuring both high-side and low-side switch currents at high bandwidth and dynamically reconstructing the full current waveform in real-time. This dynamic approach allows the system to adapt to changing current conditions while maintaining both fast response and high precision.
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 solution provides a compact, low-loss, high-bandwidth current sensing system that enables fast over-current protection and accurate drive current reconstruction, improving the efficiency and responsiveness of current sensing in power electronic converters.
Implementation Method 1
a first high-bandwidth current sensor circuit that measures a series of high-side current pulses through the first switch and provides a first analog signal that is proportional to the series of high-side pulses; a second high-bandwidth current sensor circuit that measures a series of low-side current pulses through the second switch
Data Source
Figure 1
Figure 2
Figure 3A~3C
AI summary
A system having: a power switching circuit (110) providing a drive current to a load, and having: a power source; first and second serially connected switches convert DC power from the power source into AC current to form the drive current, or vice versa; a first high-bandwidth current sensor circuit measures high-side current pulses through the first switch and provides a first analog signal, proportional to the high-side pulses; a second high-bandwidth current sensor circuit measures low-side current pulses through the second switch and provides a second analog signal is proportional to the low-side pulses; a signal processing device coupled to the first and second current sensor circuits performs steps of converting the first analog signal to a first digital signal and the second analog signal to a second digital signal; and reconstructing the drive current and obtaining its cycle average values from the first and second digital signals.