DC/DC Converter Capacitor Series Circuit Topology
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Solution Overview
Problem
Current DC/DC converters face challenges in efficiently converting high direct voltages to lower voltages due to high conduction and turn-off losses in semiconductor switches, requiring expensive SiC MOSFETs and having limitations in response time and capacitor dielectric strength, especially with high input voltages exceeding 1000V.
Innovation Solution
A DC/DC converter design featuring a capacitor series circuit with two inverse converters sharing a middle capacitor, utilizing a bridge circuit with semiconductor switches and coils to achieve symmetrical and stacked arrangements, allowing for indirect power transfer and reduced dielectric strength requirements on capacitors, enabling the use of standard components and soft-switching for low losses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If standard MOSFETs are used for high voltage conversion, then the converter can be implemented with inexpensive components, but conduction losses increase significantly and efficiency decreases
Solution Approach 1:
The patent divides the single high-voltage switch into multiple lower-voltage switches arranged in series. Each switch experiences only a portion of the total voltage, allowing the use of standard, inexpensive MOSFETs while maintaining low conduction losses since each switch operates at acceptable voltage levels.
Solution Approach 2:
The patent transitions from a single-switch topology to a multi-switch series arrangement, adding the dimension of switch quantity. This dimensional change allows voltage distribution across multiple components, enabling the use of standard MOSFETs without incurring high conduction losses.
2Power
If high voltage ratios are implemented with conventional topologies, then the converter can handle high input voltages, but capacitor dielectric strength requirements become problematic and exceed standard component capabilities
Solution Approach 1:
The patent segments the voltage stress across multiple capacitors connected in series. Each capacitor experiences only a fraction of the total input voltage, specifically less than half, which falls within the dielectric strength capabilities of standard electrolytic capacitors while maintaining the ability to handle high input voltages.
Solution Approach 2:
The patent inverts the conventional approach by using indirect power transfer through capacitors rather than direct switching. The capacitor series circuit with intermediate voltage tapping allows high voltage handling while distributing stress across multiple lower-voltage-rated components.
3Speed
If the converter is designed for ultra-short response times to handle extreme load jumps, then the response time improves, but the time constant increases due to required passive component dimensioning
Solution Approach 1:
The patent segments the power transfer function across multiple switching stages and capacitors. This segmentation allows for smaller individual passive components with lower time constants while maintaining the overall voltage conversion capability, enabling faster response to load changes.
Solution Approach 2:
The patent implements dynamic voltage sharing and soft-switching control that adapts to load conditions. The multi-switch topology enables flexible current distribution and voltage regulation that reduces the effective time constant, allowing ultra-short response times for extreme load jumps.
4Adaptability or versatility
If bidirectional power flow is implemented with stacked synchronous converters, then power can be transferred in both directions, but output current is reduced by the inverse polarity effect and capacitor currents increase during dynamic effects
Solution Approach 1:
The patent inverts the conventional synchronous converter topology by using inverse converters with indirect power transfer through capacitors. This inversion eliminates the inverse polarity effect that reduces output current, as the capacitor-based power transfer does not suffer from the same current cancellation issues.
Solution Approach 2:
The patent introduces capacitors as intermediary energy storage elements between input and output. This intermediary approach enables bidirectional power flow without the direct current path issues of synchronous converters, maintaining high output current while allowing reverse power flow 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 the dielectric strength requirements on capacitors, allows for efficient operation with high input voltages, and enables cost-effective implementation using standard components while maintaining output power and reducing current load on capacitors, suitable for applications with high voltage ratios and rapid response times.
Implementation Method 1
a first DC voltage at an input into a second DC voltage at an output... with a capacitor series circuit of at least three... wherein a first DC voltage is present at the capacitor series circuit as the input voltage and a second DC voltage which is tapped from the capacitor series circuit is present at the output of the DC/DC converter
Implementation Method 2
a bridge circuit made up of a first switch series circuit with at least one first and second semiconductor switch... converting a first DC voltage at an input into a second DC voltage at an output
Implementation Method 3
a series circuit made up of first and third capacitors and an electrical connection as a bridge branch, in which a first coil is arranged... a series circuit made up of second and third capacitors and an electrical connection as a bridge branch, in which a second coil is arranged
Data Source
Figure 1
Figure 2~9
Figure 10
AI summary
For a DC/DC converter with high dynamics and for high voltage ratios, it is provided that a series connection (2) of at least three capacitors (C1, C2, C3) is provided in the DC/DC converter (1), wherein a first capacitor (C1) and middle third capacitor (C3) of the series connection (2) are part of a first inverse converter (7) and a second capacitor (C2) and the middle third capacitor (C2) of the series connection (2) are part of a second inverse converter (8), and that the first DC voltage (UIN) is applied to the series connection (2) and the second DC voltage (UOUT) is applied to the common third capacitor (C3) of the first and second inverse converters (7, 8).