Current Sharing Transformer for Power Conversion Units
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Multiunit power conversion systems face challenges in current sharing due to phase shifts and parameter differences among subunits, leading to inefficiencies, increased losses, and reduced device lifetime, especially when the current deviation frequency approaches switching frequency.
Innovation Solution
A multiunit power conversion system incorporating a current sharing transformer with windings connected in parallel to resonant capacitors or inductors, allowing for effective current balancing without requiring large inductance values, reducing winding losses, and accommodating phase shifts in drive signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If coupled inductors with large inductance values are used to suppress current deviation, then current sharing is improved, but the size and loss of the inductors increase significantly
Solution Approach 1:
The patent introduces a current sharing transformer as an intermediary component with magnetically coupled windings. This transformer mediates the current distribution among parallel power conversion subunits by providing a magnetic coupling path that automatically balances currents, eliminating the need for large coupled inductors in the main current path while achieving effective current sharing.
Solution Approach 2:
The patent segments the current sharing function from the main power conversion function. Instead of using large coupled inductors that handle both main current and current sharing, the invention separates these functions by introducing a dedicated current sharing transformer with magnetically coupled windings that only handle current balancing, allowing the main inductors to be much smaller.
2Reliability
If coupled inductors with large inductance values are used to suppress current deviation, then current sharing is improved, but winding losses increase due to large wire diameter requirements
Solution Approach 1:
The current sharing transformer acts as an intermediary that handles current balancing with much smaller current magnitudes compared to the main power current. The magnetically coupled windings provide the necessary coupling effect for current sharing while carrying only the difference current, dramatically reducing winding losses compared to large coupled inductors that must carry the full main current.
3Reliability
If the frequency of current deviation among subunits is close to the switching frequency, then control measures become ineffective, but hardware-based current sharing is required
Solution Approach 1:
The patent replaces the control-based current sharing approach with a hardware-based magnetic coupling approach. Instead of using controllers and sensors to detect and correct current deviations (which becomes ineffective when deviation frequency approaches switching frequency), the invention uses the magnetic coupling of transformer windings to automatically suppress current deviations through inherent electromagnetic relationships, eliminating the need for complex control systems.
4Power
If series connection of power conversion subunits is used to increase capacity, then power density is improved, but voltage level requirements increase
Solution Approach 1:
The patent merges multiple power conversion subunits in series while using the current sharing transformer to manage the interactions between them. The magnetic coupling of the transformer windings provides a unified current reference that helps coordinate the series-connected subunits, allowing them to operate together as a unified high-power system while managing the voltage stress through proper transformer design and winding configuration.
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
The current sharing transformer effectively suppresses current imbalances, minimizes winding losses, and allows for compact design, while enabling high potential differences and phase shifts, thereby enhancing system efficiency and reliability.
Implementation Method 1
a current sharing transformer comprising a first winding and a second winding magnetically coupled to each other
Data Source
AI summary
A multiunit power conversion system comprises: a first power conversion unit, a second power conversion unit, and a current sharing transformer. The first power conversion unit comprises a first resonant capacitor and a first resonant inductor in series. The second power conversion unit comprises a second resonant capacitor and a second resonant inductor in series. The current sharing transformer comprises a first winding and a second winding magnetically coupled for current-sharing of the first and second power conversion units. The first and second windings are connected in parallel to the first and second resonant capacitors, respectively; or the first and second windings are connected in parallel to the first and second resonant inductors, respectively; or the first winding is connected in parallel to the first resonant capacitor and the first resonant inductor, and the second winding is connected in parallel to the second resonant capacitor and the second resonant inductor.