Sense Current Detection Unit for Low-Current Accuracy
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Solution Overview
Problem
Current electronic control units for electromagnetic solenoids face accuracy issues in current feedback control due to high quantization error when the current value is small, as the analog-digital conversion accuracy is compromised, especially in regions where the sense current is low.
Innovation Solution
A sense current detection unit comprising multiple sense transistors with different current flow rates is used, allowing for increased sense current input to the analog/digital converter in regions where the main current is small, thereby reducing quantization error and improving detection accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the sense current value is increased in low-current regions, then the quantization error is reduced and detection accuracy is improved, but the device complexity increases due to multiple sense transistors
Solution Approach 1:
The sense current detection unit is segmented into multiple sense transistors (first sense transistor and second sense transistor) with different current flow rates. This segmentation allows the system to handle different current ranges separately, improving measurement precision in low-current regions by using the second sense transistor with higher current flow rate, while maintaining simplicity in high-current regions by using only the first sense transistor.
Solution Approach 2:
The system dynamically switches between different sense transistors based on the main current value. When the main current value is small (below threshold), the second sense transistor is activated to increase sense current and reduce quantization error. When the main current value is large (above threshold), only the first sense transistor is used. This dynamic adaptation resolves the contradiction by optimizing detection accuracy only when needed.
2Device complexity
If a single sense transistor is used, then the device complexity is low, but the quantization error is large in low-current regions reducing detection accuracy
Solution Approach 1:
The sense current detection unit is segmented into multiple sense transistors (first sense transistor and second sense transistor) with different current flow rates. This segmentation allows the system to handle different current ranges separately, improving measurement precision in low-current regions by using the second sense transistor with higher current flow rate, while maintaining simplicity in high-current regions by using only the first sense transistor.
Solution Approach 2:
The system dynamically switches between different sense transistors based on the main current value. When the main current value is small (below threshold), the second sense transistor is activated to increase sense current and reduce quantization error. When the main current value is large (above threshold), only the first sense transistor is used. This dynamic adaptation resolves the contradiction by optimizing detection accuracy only when needed.
3Measurement precision
If the number of bits of the analog/digital converter is increased, then the quantization error is reduced, but the area of the converter increases and read response time increases causing control problems
Solution Approach 1:
Instead of increasing the converter's resolution to reduce quantization error, the invention converts the harmful effect of low sense current into a benefit by using multiple sense transistors to amplify the sense current in low-current regions. This approach reduces quantization error at the source (sense current level) rather than at the conversion level, avoiding the need for a larger, slower converter.
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 configuration enhances the detection accuracy of the sense current by reducing quantization error in low-current regions, ensuring precise current feedback control.
Implementation Method 1
the current flowing through the coil is detected by using a sense transistor such as a MOSFET connected to the current output transistor
Implementation Method 2
the sense current detected by the sense transistor is input to an analog/digital converter and converted into a digital value (quantization)
Data Source
AI summary
An object is to provide a new electronic control unit that can improve detection accuracy of a sense current even in a region where the current value of the sense current is small. Provided is a sense current detection unit including a plurality of sense transistors that have different current flow rates and that are connected to current output transistors controlling a current flowing in a coil load. The current in the sense current detection unit is input to an analog/digital converter, and the current value of the current flowing in the sense current detection unit is converted into a digital value. The current value of the current flowing in the sense current detection unit is increased through a combination or a selection of the plurality of sense transistors of the sense current detection unit in a region where the current value of the main current of the current output transistors is small compared to a region where the current value of the main current is large.