Resonant Capacitive Converter for Transformer-Less Galvanic Isolation
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Solution Overview
Problem
Existing DC/DC converters for medium voltage applications often require transformers for galvanic insulation, which are costly, space-intensive, and complex, and may not efficiently provide constant output voltage and sinusoidal currents in phase with the grid phase voltages.
Innovation Solution
A transformer-less DC/DC converter design utilizing a resonant circuit with capacitors and inductors to provide galvanic insulation between the DC/AC and AC/DC stages, generating medium frequency AC power for efficient power transfer between medium and low voltage sides.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a medium frequency transformer is used for galvanic insulation between medium voltage and low voltage stages, then galvanic insulation is provided, but initial cost, operating cost, space requirement, system complexity, and conversion efficiency are worsened
Solution Approach 1:
The patent extracts and removes the transformer component from the converter system. Instead of using a transformer for galvanic insulation and power transfer, the invention directly couples the medium voltage and low voltage stages through power electronic switches and circuitry, eliminating the need for a separate transformer and its associated complexity, cost, and space requirements.
Solution Approach 2:
The patent introduces power electronic switches (such as IGBTs or MOSFETs) and control circuitry as intermediary components between the medium voltage and low voltage stages. These intermediaries enable galvanic insulation and power transfer through controlled switching operations, replacing the transformer's magnetic coupling mechanism with an electronically controlled approach.
2Reliability
If a medium frequency transformer is used, then galvanic insulation is achieved, but initial cost and operating cost increase
Solution Approach 1:
The patent extracts and removes the transformer component from the converter system. Instead of using a transformer for galvanic insulation and power transfer, the invention directly couples the medium voltage and low voltage stages through power electronic switches and circuitry, eliminating the need for a separate transformer and its associated complexity, cost, and space requirements.
3Reliability
If a medium frequency transformer is used, then galvanic insulation is provided, but space requirement increases
Solution Approach 1:
The patent extracts and removes the transformer component from the converter system. Instead of using a transformer for galvanic insulation and power transfer, the invention directly couples the medium voltage and low voltage stages through power electronic switches and circuitry, eliminating the need for a separate transformer and its associated complexity, cost, and space requirements.
4Reliability
If a medium frequency transformer is used, then galvanic insulation is achieved, but conversion efficiency deteriorates
Solution Approach 1:
The patent introduces power electronic switches (such as IGBTs or MOSFETs) and control circuitry as intermediary components between the medium voltage and low voltage stages. These intermediaries enable galvanic insulation and power transfer through controlled switching operations, replacing the transformer's magnetic coupling mechanism with an electronically controlled approach that reduces energy losses.
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 solution enables efficient power transfer with reduced costs, complexity, and improved efficiency, providing constant output voltage and sinusoidal currents in phase with the grid, suitable for high-power applications like electric vehicle charging and renewable energy systems.
Implementation Method 1
a resonant circuit provided between the DC/AC stage and the AC/DC stage and configured for transferring the medium frequency AC power
Implementation Method 2
The at least two capacitors provide galvanic insulation between the DC/AC stage and the AC/DC stage
Data Source
Figure 1~2
Figure 3
Figure 4~5
AI summary
A converter including at least one DC/AC stage configured for generating a medium frequency AC power and having first and second AC outputs for the medium frequency AC power, at least one AC/DC stage configured for generating a DC power from the medium frequency AC power and having first and second AC inputs for the medium frequency AC power, and a resonant circuit provided between the DC/AC stage and the AC/DC stage and configured for transferring the medium frequency AC power. The resonant circuit includes at least two capacitors including a first capacitor and a second capacitor. The first capacitor is connected between the first AC output and the first AC input, and the second capacitor is connected between the second AC output and the second AC input. The resonant circuit further includes at least two inductors including a first inductor and a second inductor connected in series and defining a connection point between the two inductors. In a first alternative, the first inductor is connected in series between the first capacitor and the first AC input, and the second inductor is connected in series between the first AC input and the second AC input. In a second alternative, the first inductor is connected in series between the first capacitor and the first AC output, and the second inductor is connected in series between the first AC output and the second AC output. The at least two capacitors provide galvanic insulation between the DC/AC stage and the AC/DC stage.