Switched Current Measurement Circuit With Timed Sensing Windows
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Solution Overview
Problem
Current circuit arrangements for current measurement in transistors, such as IGBTs, require components to be dimensioned for the maximum duration of the switching period, leading to increased power loss and heat dissipation, which complicates design and reduces the circuit's cost-effectiveness and lifespan.
Innovation Solution
A circuit arrangement with a control circuit that activates a current measuring apparatus only for a limited measurement period, using a monostable multivibrator to deactivate it after the measurement is complete, allowing for a more efficient and cost-effective design by reducing average power loss and heat generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the current measuring apparatus is activated for the entire switching period, then the current measurement is continuous and complete, but the power loss and heat dissipation increase significantly
Solution Approach 1:
The current measuring apparatus is activated only during specific measurement periods within the switching period, rather than continuously. The control circuit switches the measuring apparatus on during the measurement period (when current flows through the load) and off during other periods,实现 periodic measurement that reduces power loss while maintaining measurement completeness
Solution Approach 2:
The control circuit is designed to activate the current measuring apparatus in advance at the appropriate timing within the switching period. By predicting when current measurement is needed and preparing the measuring apparatus accordingly, the system ensures measurement completeness while minimizing activation time and power consumption
2Measurement precision
If the current measuring apparatus is activated for the entire switching period, then the measurement is comprehensive, but the circuit elements require larger design and higher cost
Solution Approach 1:
By activating the measuring apparatus periodically rather than continuously, the average current through measuring components is reduced, allowing for smaller resistor values and smaller overall circuit element sizes while maintaining measurement accuracy during active periods
Solution Approach 2:
The measurement is performed partially (only during measurement periods) rather than excessively (continuously throughout the entire switching period). This partial action approach provides sufficient measurement data for control purposes while reducing component stress and size requirements
3Measurement precision
If the current measuring apparatus is activated for the entire switching period, then the measurement data is complete, but the heat dissipation increases and reduces circuit lifespan
Solution Approach 1:
The measuring apparatus operates periodically with on/off cycles rather than continuously, reducing the cumulative thermal stress on circuit elements. This extends the operational lifespan of resistors, capacitors, and other components by limiting their exposure to power dissipation to only the necessary measurement periods
Solution Approach 2:
The periodic deactivation of the measuring apparatus, which might seem to reduce measurement completeness, actually benefits the circuit by reducing heat generation. The measurement data obtained during active periods is sufficient for control purposes, and the reduced thermal stress extends component lifespan
Data Source
AI summary
The invention relates to a circuit arrangement having a switching device (1) which is designed to provide a first voltage (UE) and a first electrical current (IE) in a power path and to provide a second voltage (US) and a second electrical current (IS) in a measuring path for the duration of a switching period, wherein the first electrical current corresponds to the second electrical current; having a current measuring apparatus (2) which is arranged in the measuring path and is designed to provide an output signal (UM) which corresponds to the first electrical current; and having a control circuit (3, 4) which is designed to activate the current measuring apparatus for the duration of a measuring period and to deactivate the current measuring apparatus again after the measuring period expires.