Multi-Level Boost Converter Topology for High Voltage Stress Reduction
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Solution Overview
Problem
High-voltage boost converters face inefficiencies due to the need for costly diodes that suffer from reverse recovery issues and high forward voltage drops, especially in applications where input voltages range from 200-1000V and output voltages reach up to 1200V.
Innovation Solution
A multi-level boost converter topology is introduced, featuring series-connected diodes, a flying capacitor, and a bridge circuit generating a multi-level waveform, which reduces voltage stress on components and allows for the use of smaller, less expensive devices by maintaining lower voltage levels across them, along with a pre-charge path for the flying capacitor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a single high-voltage diode is used to support full output voltage, then the converter can achieve high voltage output, but the diode suffers from reverse recovery issues and high forward voltage drop
Solution Approach 1:
The patent divides the single high-voltage diode into multiple series-connected diodes (first diode and second diode). Each diode only needs to withstand a portion of the total output voltage, reducing the forward voltage drop and reverse recovery losses for each individual diode while maintaining the full voltage blocking capability across the series combination.
2Power
If a single high-voltage diode is used, then the converter can achieve high voltage output, but the diode becomes costly and complex
Solution Approach 1:
The patent segments the high-voltage diode function into multiple lower-voltage diodes connected in series. This reduces the complexity and cost of each individual diode while achieving the same overall voltage handling capability through the series combination.
3Stress or pressure
If series-connected diodes are used, then voltage stress on each component is reduced, but the circuit complexity increases
Solution Approach 1:
The patent introduces a flying capacitor connected between the series-diode nodes and a bridge circuit that generates multi-level waveforms. This segmentation approach distributes voltage stress across multiple components while the flying capacitor and bridge circuit manage the increased complexity through controlled switching operations.
Solution Approach 2:
The flying capacitor acts as an intermediary element between the series-connected diodes and the bridge circuit. It facilitates voltage balancing and energy transfer, enabling the series diode configuration to function effectively while managing the additional circuit complexity through its capacitive coupling.
4Loss of energy
If multi-level waveform generation is implemented, then conduction losses are reduced, but the switching complexity increases
Solution Approach 1:
The patent employs periodic switching of the bridge circuit to generate multi-level waveforms at the flying capacitor. This periodic action creates distinct voltage levels during different switching intervals, reducing conduction losses by optimizing current paths while managing complexity through regular, predictable switching patterns.
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 topology efficiently handles high voltage levels with reduced conduction losses and component stress, enabling the use of smaller inductors and devices, while providing a reliable solution for abnormal grid interactions and efficient voltage regulation.
Implementation Method 1
When the switch S013 is in the on state and closed, the current path from Vin 17 is through S013 to ground and the current though the inductor L 12 increases. When the switch S013 is in the off state and open, the only path available to the current is through the diode D014 and on to the capacitor Co 15. This results in the energy accumulated while S013 was on being transferred into the capacitor Co 15.
Implementation Method 2
An output capacitor Co 15 is connected between the output node at Vo and ground, in parallel with the load Ro 19, and an input capacitor Cin 11 is connected between the input and ground, in parallel with the voltage source Vin 17.
Data Source
AI summary
A DC to DC converter uses a multi-level boost converter topology. In addition to the input voltage being connected to an output node through a boost inductor in series with a pair of diodes, a bridge circuit generates a multi-level waveform on one side of flying capacitor, which is on the other side connected between the series connected diodes. The boost converter topology maintains low voltage stress on its components under abnormal conditions on the output node and allows for simple pre-charging of the flying capacitor.