Capacitive Voltage Converter Inductor Current Control
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Solution Overview
Problem
Existing capacitive voltage converters face challenges in controlling switching due to high peak current values and variations, making it difficult to detect current and maintain efficiency, especially when the load is small or absent.
Innovation Solution
Incorporating an inductor in series between the capacitive voltage conversion circuit and the output capacitor, along with a current detector and controller, to control switching based on detected current thresholds, reducing peak current values and variations, and optimizing switching frequency to improve efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a general charge pump configuration is used without an inductor, then the device can be miniaturized and is suitable for compact power supply devices, but the current peak value becomes significantly high making current detection difficult and causing difficulty in controlling switching
Solution Approach 1:
An inductor is introduced as an intermediary component between the capacitive voltage conversion circuit and the output capacitor. This inductor acts as a buffer that smooths the current waveform, converting the high peak current from the charge pump into a more manageable current profile that can be easily detected and controlled, while still maintaining the compact structure without requiring external inductors for the charge pump itself
2Loss of energy
If the switching frequency is lowered to improve efficiency when load is small, then switching losses are reduced, but current peak value variations and charging/discharging time variations increase making control difficult
Solution Approach 1:
A current detector monitors the current flowing through the inductor and provides feedback to a controller. The controller adjusts the switching of the charge pump based on this feedback, maintaining stable current levels and consistent charging/discharging times even when operating at lower switching frequencies to reduce switching losses during light load conditions
Solution Approach 2:
The switching frequency and timing of the charge pump are made dynamic rather than fixed. The controller continuously adjusts the switching parameters based on real-time current detection, allowing the system to optimize between switching losses and current stability depending on operating conditions such as load level
3Ease of operation
If an inductor is added in series to reduce peak current, then current detection becomes easier and control is improved, but the device complexity increases
Solution Approach 1:
The inductor serves multiple functions simultaneously: it smooths current to reduce peak values, enables easy current detection, provides a basis for feedback control, and helps regulate the output voltage. By making the inductor multi-functional, the added component justifies the increased complexity through substantial improvements in controllability and performance
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 configuration enables stable current detection and control, reducing switching losses and improving voltage conversion efficiency by adjusting the switching frequency relative to the resonant frequency, especially when the load is small.
Implementation Method 1
an inductor coupled in series between the capacitive voltage conversion circuit and the output capacitor
Implementation Method 2
a capacitive voltage conversion circuit to receive an input voltage, convert the input voltage into an output voltage, and output the output voltage
Data Source
AI summary
A voltage converter includes a capacitive voltage conversion circuit, an output capacitor, an inductor, a current detector, and a controller. The capacitive voltage conversion circuit includes switches, at least one flying capacitor, and an intermediate capacitor at an output portion. The current detector detects a current flowing in the inductor. The controller controls the switches in the capacitive voltage conversion circuit to change between at least two states by comparing the current flowing in the inductor to a threshold current.