Indirect Average Current Measurement in Power Converters
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Solution Overview
Problem
In power converter systems, direct access to output current is often not available, leading to increased costs or inefficiencies, and existing methods struggle to accurately measure inaccessible average currents.
Innovation Solution
A system and method for indirect average current measurement, using a measurement system that measures accessible currents and derives average current measurements based on timing control signals, applicable to various converter topologies like buck, boost, and flyback, allowing for the determination of inaccessible currents through fundamental relationships between input and output currents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If direct sensing of output current is implemented, then current control feedback is achieved, but cost increases and system complexity increases
Solution Approach 1:
The patent uses an intermediary approach by measuring accessible currents (input current, switch current, or inductor current) and deriving the inaccessible output current through mathematical relationships and timing control signals. This mediator method avoids direct sensing at the output while still achieving accurate current control feedback.
Solution Approach 2:
The patent creates a copy of the output current information by measuring related currents at accessible locations and using timing relationships to reconstruct the output current waveform characteristics. This copying approach allows feedback control without direct physical access to the output current.
2Measurement precision
If direct access to output load current is obtained, then current measurement is accurate, but cost increases and inefficiencies are introduced
Solution Approach 1:
The measurement system uses intermediary measurements of accessible currents combined with timing control signals to derive the output current. This intermediary approach maintains measurement precision while avoiding the cost and inefficiency of direct output access.
Solution Approach 2:
The patent replaces the physical mechanical connection required for direct current sensing with an electrical/mathematical derivation approach. By using timing control signals and mathematical relationships, the system substitutes direct physical access with indirect computational measurement.
3Loss of information
If level shifting or current transfer across isolation barrier is implemented, then inaccessible current information is obtained, but system complexity and cost increase
Solution Approach 1:
The patent uses timing control signals as intermediaries to transfer current information across the isolation barrier. Instead of using complex level shifting circuits or magnetic coupling, the system derives output current information from input-side measurements combined with timing signals, simplifying the isolation barrier requirements.
4Ease of operation
If indirect current measurement method is implemented, then direct access requirements are eliminated, but measurement precision may be compromised
Solution Approach 1:
The patent implements feedback by using the derived output current measurement to control the power converter operation. The timing control signals provide feedback information about the output current characteristics, allowing the system to maintain precision through closed-loop control even with indirect measurement.
Solution Approach 2:
The measurement system dynamically adapts by using timing control signals that vary with the operating conditions. The system adjusts the measurement and derivation process based on real-time switching timing, maintaining measurement precision across different operating points and load conditions.
Data Source
AI summary
One example of the invention relates to a power system. The power system can include a switching power converter configured to convert an input voltage to an output voltage for providing power at an output thereof to which a load is connectable. A measurement system can include measurement circuitry configured to measure an average of an accessible current in the power converter during both continuous and discontinuous modes of operation and derive an average measurement of another current in the power converter based on timing control signals used to control operation of the power converter.