Step Up Down Converter Inductor Current Detection
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Solution Overview
Problem
Conventional step up/down converters with H bridge circuits face challenges in detecting inductor current across all switching modes, leading to limitations in operating both step up and step down modes due to the absence of detecting resistors in certain switch configurations, requiring complex circuit configurations for accurate current detection.
Innovation Solution
A step up/down converter configuration where a detecting resistor is placed between the ends of two switches, allowing inductor current detection in any switch mode, with a control circuit adjusting detection signals to ensure accurate feedback control and rapid response, including error amplifiers and comparators for generating driving signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional H bridge circuit configuration is used with current detecting resistors connected to specific switches, then the circuit can operate in certain switching modes, but the inductor current cannot be detected accurately in all switching modes leading to operational limitations
Solution Approach 1:
The detecting resistor is connected to a node that is accessible in all switching modes (the node between the second switch and third switch), making it a universal detection point that functions reliably regardless of which switches are ON or OFF. This single connection point serves all four switching modes without requiring mode-specific detection circuits.
Solution Approach 2:
The detecting resistor is placed at an intermediary node in the H bridge circuit that serves as a common reference point for current detection across all operating modes. This intermediary position allows the control circuit to measure inductor current indirectly through voltage detection at this strategic location, eliminating the need for multiple detecting resistors.
2Reliability
If multiple current detecting resistors are used to cover all switching modes, then current detection reliability improves, but the circuit complexity increases
Solution Approach 1:
Multiple current detection functions that would traditionally require separate detecting resistors for each switching mode are merged into a single detection point. The voltage at the node between the second and third switches contains information about the inductor current in all modes, allowing one detecting resistor to replace what would otherwise be multiple resistors.
Solution Approach 2:
A single detecting resistor configuration serves multiple functions by detecting inductor current in all four switching modes (first state, second state, step-up mode, and step-down mode), eliminating the need for mode-specific detection circuits and reducing overall component count.
3Measurement precision
If detecting resistors are placed in series with the inductor, then current detection accuracy improves, but the voltage drop across the detecting resistor increases causing power loss
Solution Approach 1:
Instead of placing the detecting resistor in direct series with the inductor current path, the invention uses an intermediary approach by detecting the voltage at a specific node in the H bridge circuit. This node voltage, when combined with knowledge of the switching state, provides accurate current information without requiring the detecting resistor to bear the full inductor current, thereby reducing power loss.
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
Enables easy and accurate detection of inductor current in any switch mode, enhancing power conditioning accuracy and response speed, and supports stable operation of loads like light emitting elements with low power consumption.
Implementation Method 1
an inductor 106, first to fourth switches 101 to 104, two of which are connected to each of both ends of the inductor 106
Implementation Method 2
a detecting resistor 9, connected between an other end of the second switch 2 and an other end of the third switch 3, and configured to detect an inductor current IL flowing through the inductor 6
Data Source
AI summary
Provided is a step up/down converter, in which the inductor current can be easily detected by a simple configuration in any connecting mode of the switches. This comprises a first switch, one end of which is connected to an input power source, and the other end of which is connected to one end of the inductor, a second switch, one end of which is connected to the one end of the inductor, and the other end of which is connected to a reference potential applying unit, a third switch and a fourth switch, one end of which is connected to the other end of the inductor; a capacitor circuit element, connected between the other end of the third switch and the other end of the fourth switch, and configured to generate an output voltage for applying to a load, a detecting resistor, connected between the other end of the second switch and the other end of the third switch, and configured to detect an inductor current flowing through the inductor, and a control circuit configured to perform control from the first switch to the fourth switch based on the inductor current detected by the detecting resistor.