Auxiliary AC Unit for Power Conversion Loss Reduction
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Solution Overview
Problem
Existing power conversion units face inefficiencies due to significant reactive power flow and switching losses, particularly at peak power conditions, which limit their operational range and increase energy losses.
Innovation Solution
The power conversion unit employs a power transmission unit with a main transformer and an auxiliary AC unit that provides a tunable auxiliary AC voltage, allowing for zero-current switching and in-phase AC voltages and currents, thereby minimizing reactive power and switching losses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If phase shift control is used to establish power flow between AC power units, then power transmission capability is improved, but reactive power flow increases causing significant losses
Solution Approach 1:
An auxiliary AC unit is introduced as an intermediary component connected between the AC power units and the transformer. This auxiliary unit generates an auxiliary AC voltage that acts as a mediator to control the current flow through the transformer, enabling power transmission without requiring phase shift between the main AC power unit voltages, thereby eliminating reactive power losses.
Solution Approach 2:
The invention changes the control parameter from phase shift to auxiliary AC voltage magnitude and frequency. By adjusting the auxiliary AC voltage parameters instead of phase shifting the main AC voltages, the system achieves power flow control without generating reactive power, thus resolving the contradiction between power transmission capability and energy losses.
2Productivity
If power switches are operated at peak power conditions, then power conversion speed is improved, but switching losses increase significantly
Solution Approach 1:
The auxiliary AC unit performs preliminary action by pre-establishing the current flow path and conditions before the main power switches operate. By controlling the auxiliary AC voltage, the system prepares the circuit state in advance, allowing switches to operate under optimized conditions that reduce switching losses while maintaining fast power conversion.
Solution Approach 2:
The auxiliary AC unit operates with periodic voltage cycles that synchronize with the power conversion process. This periodic action creates optimal switching intervals and current waveforms that reduce switching losses while maintaining high power conversion speed through controlled periodic operation rather than continuous peak power switching.
3Loss of energy
If resonant topologies are used to reduce switching losses, then switching efficiency is improved, but current amplitude and shape control capability is lost
Solution Approach 1:
The system combines resonant operation for loss reduction with dynamic control capability through the auxiliary AC unit. The auxiliary unit can dynamically adjust its voltage parameters to control current amplitude and shape while the resonant circuit maintains low switching losses. This dynamic adjustment capability restores control flexibility that would otherwise be lost in fixed resonant topologies.
Solution Approach 2:
The auxiliary AC unit serves multiple functions simultaneously: it enables resonant operation for loss reduction, provides current amplitude and shape control, and maintains power flow regulation. This multi-functionality resolves the contradiction by making the system capable of both efficient resonant operation and precise control, unlike traditional resonant topologies that sacrifice control capability.
4Loss of energy
If additional inductors are added to ensure zero-voltage switching, then switching efficiency is improved, but device complexity and cost increase
Solution Approach 1:
The auxiliary AC unit merges multiple functions into a single device: it provides the necessary inductance for zero-voltage switching, generates the control voltage for power flow regulation, and enables resonant operation for loss reduction. By combining these functions in one unit rather than adding separate inductors and control circuits, the invention reduces overall device complexity while achieving improved switching efficiency.
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 configuration achieves high efficiency power conversion with reduced reactive power and switching losses, enabling operation over a wide range while maintaining low electromagnetic interference and harmonic content.
Implementation Method 1
a power transmission unit (1.1, 1.2, 1.3, 1.4, 1.5) with a main transformer (2) and an auxiliary AC unit (5, 5.1, 5.2, 5.3, 5.4, 5.5, 5.6) that provides a tunable auxiliary AC voltage (7)
Data Source
Figure 1~2C
Figure 2D~3
Figure 4~5C
AI summary
A power transmission unit for controlling a flow of electric energy between two AC power units is provided. The power transmission unit comprises a main transformer having a first winding and a second winding as well as a switchable auxiliary AC unit for applying a tunable auxiliary AC voltage across an auxiliary AC side of the auxiliary AC unit. The auxiliary AC side is connected in series with the first winding of the main transformer to form a series connection. Further, a power conversion unit comprising the power transmission unit and two AC power units as well as a method for controlling a flow of electric energy by using such a power conversion unit are provided.