Two-Step Inverter Using Switched Capacitors to Eliminate Inductors
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Solution Overview
Problem
Existing wireless power transfer systems often require large and expensive inductors in the DC/DC converter stage, which can lead to inefficiencies and increased PCB area.
Innovation Solution
The implementation of a switched capacitor converter that eliminates the need for an inductor by merging the switched capacitor stage with the inverter into a single integrated stage, utilizing a flying capacitor and a ladder of switching devices to regulate output power.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a DC/DC converter stage with inductor is used to vary DC bus voltage, then output power can be regulated, but the inductor and DC bus capacitor become undesirably large
Solution Approach 1:
The patent merges the DC/DC converter stage with the inverter stage into a single integrated two-step inverter. The switched capacitor converter and inverter share common components and circuitry, eliminating the need for separate large inductors and DC bus capacitors. This integration achieves both power regulation and voltage conversion in one unified stage, reducing overall component size and PCB area while maintaining output power regulation capability
Solution Approach 2:
The patent uses switched capacitor technology to change the voltage conversion mechanism from inductor-based to capacitor-based. By switching capacitors in series and parallel configurations, the system achieves variable voltage output without requiring large magnetic components. The switched capacitor stage dynamically changes capacitance connections to regulate output power, replacing the traditional inductor-based voltage regulation
2Power
If a DC/DC converter stage with inductor is used to vary DC bus voltage, then output power can be regulated, but system efficiency decreases
Solution Approach 1:
The integration of switched capacitor converter and inverter into a single stage reduces energy losses by eliminating the need for separate conversion stages. The shared circuitry and direct coupling between stages minimize parasitic losses and improve overall system efficiency while maintaining power regulation capability
Solution Approach 2:
The patent changes the energy storage and transfer mechanism from magnetic (inductor) to electric (capacitor). Switched capacitor converters generally exhibit lower conduction losses and switching losses compared to inductor-based converters, especially at high frequencies. This parameter change improves system efficiency by reducing resistive losses and magnetic core losses
Data Source
AI summary
A switched capacitor converter can include a switched capacitor stage comprising a flying capacitor and a ladder of three switching devices. A first switching device can be connected between a DC input of the switched capacitor converter and an AC bus. A second switching device is connected between the DC input and a third switching device. The third switching device can be connected between the second switching device and ground. The flying capacitor can be connected between the AC bus and a junction of the second switching device and the third switching device. The switched capacitor converter can further include an inverter stage having an input coupled to the AC bus and an output that delivers an AC voltage.