Average Inductor Current Sensing for Lossless DC-DC Regulation
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Solution Overview
Problem
Existing power conversion systems face challenges in accurately and efficiently regulating average current in DC-DC power converters, often relying on lossy sense elements and complex methods that introduce inefficiency and inaccuracy.
Innovation Solution
A circuit and control method that utilize a voltage regulator circuit, current sensing circuitry, and a current control loop to generate pulse width modulated signals based on the average inductor current, allowing for precise regulation of the average current without lossy sense elements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If lossy sense elements are used for current sensing, then current regulation can be achieved, but energy efficiency deteriorates due to power losses
Solution Approach 1:
The patent replaces traditional lossy current sensing methods (resistive sense elements) with a lossless sensing approach that utilizes the existing inductor and switching node voltage. The current sense circuitry senses the voltage at the switching terminal during the switch on-time, eliminating the need for separate sense resistors and associated power losses.
Solution Approach 2:
The patent makes the inductor serve a dual function: both its original power transfer function and current sensing function. By utilizing the voltage already present at the switching terminal during switch conduction, the system uses its own operating voltages for sensing purposes, eliminating the need for separate sensing components and their associated losses.
2Measurement precision
If complex sensing methods are used, then measurement accuracy may improve, but device complexity increases
Solution Approach 1:
The patent makes the existing inductor and switching node serve multiple functions: power transfer and current sensing. The same switching terminal voltage that drives the power conversion is also used for current measurement, eliminating the need for separate sensing circuits and reducing overall system complexity.
Solution Approach 2:
The patent extracts only the essential sensing information (voltage at switching terminal during on-time) needed for average current calculation, discarding unnecessary complex sensing mechanisms. The control circuitry processes only the relevant voltage pulses to determine average current, simplifying the sensing approach while maintaining accuracy.
Data Source
AI summary
Current regulation circuits and techniques. In one example, a circuit includes a voltage regulator circuit, current sensing circuitry, and a current control loop. The voltage regulator circuit is coupled to an output terminal of a DC-DC power converter and configured to produce a regulation signal based on a voltage at a regulator input terminal. The current sensing circuitry is coupled to a switching terminal of the DC-DC power converter and configured to produce a pulse signal based on a voltage at the switching input terminal and a threshold set by the regulation signal. The current control loop is coupled to control terminals of switching transistors of the DC-DC power converter and configured to generate switching control signals, based on the pulse signal, to control the switching transistors to drive an average value of a current flowing through the switching terminal to a target average current value corresponding to the threshold.