Switch Converter Inductor-End Sampling for Accurate Current Sensing
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing switch converter technologies face challenges with low sampling accuracy and high power consumption for current sampling, particularly in applications like wireless charging, where real-time monitoring of average current is crucial for normal operation and fault protection.
Innovation Solution
A switch converter design that eliminates the need for high-precision sampling resistors by using an acquisition unit to acquire voltage signals from the inductor ends, an operation unit to process these signals, and a control circuit to manage switching based on the current sampling signal, thereby achieving accurate and efficient current sampling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If high-precision sampling resistors are used for current sampling, then sampling accuracy is improved, but material costs increase and PCB layout becomes more difficult
Solution Approach 1:
The patent extracts the current sampling function from the traditional external resistor-based approach and integrates it into the existing switch transistor structure. By utilizing the on-resistance of the switch transistor itself as the sampling element, the design eliminates the need for separate high-precision sampling resistors, thereby simplifying PCB layout while maintaining sampling accuracy.
Solution Approach 2:
The switch transistor serves multiple functions: it acts as both the power switching element and the current sampling element. The on-resistance of the switch transistor is utilized for current sensing in addition to its primary switching function, eliminating the need for dedicated sampling components and reducing overall system complexity.
2Device complexity
If current mirroring method is used for sampling, then circuit structure is simplified, but sampling accuracy decreases and power consumption increases
Solution Approach 1:
The patent replaces the complex current mirroring mechanism with a direct voltage sampling approach. Instead of using operational amplifiers to mirror and compare currents, the design directly measures the voltage drop across the switch transistor's on-resistance, significantly reducing circuit complexity and power consumption while improving sampling accuracy.
3Measurement precision
If operational amplifier is used for current sampling, then current can be sampled, but operation amplifier requires high performance and sampling is affected by switch noise
Solution Approach 1:
The patent employs periodic sampling during the switch transistor's on-state, capturing voltage information when the switch is conducting. By timing the sampling operation to coincide with the switch's on-period, the design captures accurate current information while avoiding the high-frequency switching noise that occurs during transitions.
Data Source
AI summary
The present application discloses a switch converter, and the switch converter comprises a first switch transistor, a second switch transistor, and an inductor, and further comprises: an acquisition unit for acquiring voltage of at least one end of the inductor, to obtain a first sampling signal and a second sampling signal; an operation unit, to obtain a current sampling signal based on the first sampling signal and the second sampling signal. The current sampling method in the switch converter of the present disclosure is simple, not easily affected by noise interference, and it has low requirements for devices, and adapts to different converters.