Dual Chopped Current Sensing for Fast Overcurrent and High Resolution
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Solution Overview
Problem
Current sensors face challenges in accurately detecting over-current conditions (ODR current) with high resolution and speed, especially in applications like electric cars, where shunt resistors can affect measurement accuracy and require fast detection within microseconds, while also needing to maintain galvanic isolation and provide both fast and accurate output signals.
Innovation Solution
A sensing system comprising a first chopped circuit for fast detection of ODR current and a second chopped circuit for high-resolution current measurement, both synchronized by a clock generator, allowing for galvanic isolation and precise current sensing with a monolithic integrated circuit chip that includes bias compensation for temperature and technology spread.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If shunt resistors are used to detect ODR current, then fast detection speed is achieved, but measurement accuracy deteriorates
Solution Approach 1:
The patent divides the sensing function into two separate circuits: a first chopped circuit for fast ODR current detection and a second chopped circuit for high-resolution current measurement. This segmentation allows each circuit to be optimized for its specific function without compromise - the first circuit achieves microsecond-level response for overcurrent protection, while the second circuit provides precise measurement for control applications.
2Measurement precision
If high resolution current measurement is implemented, then measurement precision is improved, but response speed deteriorates
Solution Approach 1:
The patent separates high-resolution measurement from fast response functions into different chopped circuits. The second chopped circuit is designed specifically for high-resolution measurement with auto-zeroing comparators, while the first chopped circuit handles fast ODR detection. This allows the measurement circuit to operate at lower speeds without compromising overall system response time.
3Reliability
If galvanic isolation is implemented, then safety and reliability are improved, but device complexity increases
Solution Approach 1:
The patent combines multiple functions (fast ODR detection, high-resolution measurement, auto-zeroing compensation, and galvanic isolation) into a single monolithic integrated circuit chip. This integration achieves galvanic isolation for safety and reliability while managing complexity through unified design rather than separate discrete components.
Data Source
AI summary
A system including a sensing system, a first chopped circuit, a second chopped circuit, and a clock generator. The sensing system is configured to provide sensed input signals. The first chopped circuit is configured to provide a switched output signal that switches in response to values of the sensed input signals crossing a limit. The second chopped circuit is configured to provide a high resolution output signal that corresponds to the sensed input signals and has a higher resolution than the switched output signal. The clock generator is configured to provide clock signals that synchronize chopping of the first chopped circuit and the second chopped circuit.