Power Supply Circuit for OLED Displays with Reduced Conduction Loss
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Solution Overview
Problem
Three-level boost converters for portable electronic devices with OLED displays face challenges such as increased conduction loss due to current flowing through two switches and require complex control circuits to maintain the voltage of a flying capacitor, which also necessitate additional converters for power supply to different elements.
Innovation Solution
A power supply circuit design that involves only one switch element in the inductor current path and automatically initializes the flying capacitor voltage to half of the output voltage every switching period, eliminating the need for a separate balancing circuit and additional converters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a three-level boost converter is used to reduce inductor size, then the inductor size is reduced, but conduction loss increases due to current flowing through two switches
Solution Approach 1:
The patent extracts one switch element from the inductor current path, leaving only one switch (Q1) involved in the inductor current. This is achieved by configuring the circuit such that the inductor current flows through Q1 and the flying capacitor, but not through Q2, thereby reducing conduction loss while maintaining the three-level boost converter's compact inductor design
Solution Approach 2:
The flying capacitor (CF) acts as an intermediary element that enables the inductor current to bypass one of the two switches. By using the flying capacitor to transfer energy, the circuit can maintain the voltage transformation function while reducing the number of switches in the current path, thus lowering conduction loss
2Volume of moving object
If a three-level boost converter is used to reduce inductor size, then the inductor size is reduced, but the control circuit complexity increases due to separate balancing circuit requirements
Solution Approach 1:
The patent implements self-service by using the existing switching operations and control signals to automatically maintain the flying capacitor voltage at half the output voltage. The control circuit leverages the natural charging and discharging cycles of the flying capacitor during normal converter operation, eliminating the need for separate balancing circuits and reducing overall control complexity
Solution Approach 2:
The control circuit is designed to perform multiple functions: it controls the main power conversion operation and simultaneously maintains the flying capacitor voltage balance. By integrating the balancing function into the existing control architecture, the circuit reduces complexity while maintaining both voltage transformation and capacitor voltage regulation
3Device complexity
If a three-level boost converter is used, then only one output voltage is generated, but additional converters are required to supply power to different elements
Solution Approach 1:
The patent makes the three-level boost converter multi-functional by enabling it to generate multiple output voltages (first output voltage and second output voltage) from a single converter structure. This is achieved by utilizing the flying capacitor to provide different voltage levels to different loads, eliminating the need for additional converters and improving power supply capability
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 design reduces power loss and simplifies the control circuit by minimizing the number of switch elements involved in the inductor current path and automatically maintains the flying capacitor voltage, thereby eliminating the need for additional power generation converters.
Implementation Method 1
charge the first capacitor and the second capacitor based on a current of the first inductor and discharge the third capacitor to provide a first output current to the display module
Implementation Method 2
charge the first capacitor and the second capacitor based on a current of the first inductor
Implementation Method 3
for a first time interval, based on a drive signal of the switch control circuit, charge the first capacitor and the second capacitor based on a current of the first inductor
Data Source
AI summary
An example electronic device including a power supply circuit may include a battery; a display module including a display panel; a regulator; a power supply circuit configured to: based on an input voltage of the battery, provide a first voltage and a second voltage to the display module, and provide a third voltage to the regulator; and a switch control circuit configured to: control a switching operation of the power supply circuit, wherein the power supply circuit includes: a first power circuit and a second power circuit, wherein the first power circuit includes multiple switch elements, a first capacitor, a second capacitor, a third capacitor, and a first inductor, and is configured to: for a first time interval, based on a drive signal of the switch control circuit, charge the first capacitor and the second capacitor, based on a current of the first inductor and discharge the third capacitor to provide a first output current to the display module, and for a second time interval, based on a drive signal of the switch control circuit, charge the third capacitor and discharge the first capacitor and the second capacitor to provide the first output current and a second output current to the display module, and wherein the second power circuit is configured to: convert a voltage level of the input voltage of the battery to provide a second voltage to the display module.