Switch-mode Power Supply Output Compensation via Inductor Voltage Detection
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Solution Overview
Problem
Conventional switch-mode power supplies require lengthy feedback signal conductors to account for voltage drops across power conductors, which are expensive and difficult to route, especially when the load is distant from the power supply.
Innovation Solution
A compensation network is used to detect voltage drops across the inductor and adjust the feedback voltage provided to the control circuitry, allowing for voltage drop compensation without measuring feedback voltage near the load, thus eliminating the need for lengthy feedback conductors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If lengthy feedback signal conductors are used to measure feedback voltage near the load, then voltage drop compensation is achieved, but conductor length and routing complexity increase
Solution Approach 1:
The patent introduces an intermediary approach by using the inductor's voltage drop as a proxy measurement. Instead of directly measuring the voltage at the load through lengthy conductors, the compensation network measures the voltage drop across the inductor (which is electrically close to the power supply) and uses this information to calculate and compensate for the voltage drop in the power conductors. This intermediary measurement point eliminates the need for long feedback conductors while still achieving accurate voltage drop compensation.
Solution Approach 2:
The patent implements a feedback mechanism where the compensation network continuously monitors the inductor voltage and adjusts the feedback voltage provided to the control circuitry accordingly. The sensed voltage drop across the inductor is fed back to modify the feedback signal, creating a closed-loop system that automatically compensates for voltage drops in the power conductors without requiring direct measurement at the load.
2Measurement precision
If lengthy feedback signal conductors are used to account for voltage drops, then voltage regulation accuracy is improved, but device complexity and routing difficulty increase
Solution Approach 1:
The inductor voltage measurement serves as an intermediary that simplifies the measurement system. By measuring the voltage at the inductor (which has minimal resistance compared to the power conductors) and using this as a reference, the system achieves accurate voltage regulation without the complexity of routing feedback conductors through the entire power distribution network to the load.
Solution Approach 2:
The patent replaces the mechanical/routing complexity of lengthy physical feedback conductors with an electrical calculation approach. Instead of physically extending the feedback path to the load, the system uses electrical measurements at the inductor and mathematical compensation to achieve the same effect, substituting physical routing complexity with electrical signal processing.
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 solution reduces the length of conductors needed for the switch-mode power supply, simplifies signal routing, and ensures that the output voltage remains within specifications by compensating for voltage drops in power conductors, enhancing efficiency and reliability.
Implementation Method 1
The compensation network is configured to detect voltage drop across the inductor
Implementation Method 2
to conduct a current from the inductor output terminal to the drive transistor current output terminal
Implementation Method 3
The compensation network is configured to adjust a feedback voltage provided to the control circuitry based on a voltage drop across the inductor
Data Source
AI summary
A switch-mode power supply includes a drive transistor, an inductor, and a compensation network. The drive transistor includes a drive transistor current output terminal. The inductor includes an inductor input terminal and an inductor output terminal. The inductor input terminal is coupled to the drive transistor current output terminal. The compensation network is disposed across the inductor. The compensation network is configured to detect voltage drop across the inductor, and to conduct a current from the inductor output terminal to the drive transistor current output terminal.