Modular Direct Converter Control for Lower Battery Loss in AC Supply
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Solution Overview
Problem
Existing power supply systems for electrical devices, such as electric vehicles, face inefficiencies due to battery losses associated with internal resistance and varying currents, leading to increased energy losses and harmonic issues, which are not effectively mitigated by current converter technologies.
Innovation Solution
A system comprising N pairs of modular energy storage direct converter systems (MESDCS) with a control system that allows for the connection of energy storage elements in series, parallel, and anti-series configurations, and the application of a common time-dependent offset voltage to minimize energy storage element losses during AC voltage generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a conventional B6 bridge converter is used to convert DC battery voltage to AC phase voltages, then AC power can be supplied to electrical consumers, but significant energy losses occur due to battery internal resistance and varying currents
Solution Approach 1:
The patent applies periodic action by superimposing a common time-dependent offset voltage on all phase voltages. This offset voltage varies periodically over time and is designed to reduce the variance of currents through the energy storage elements. By periodically adjusting the offset, the system achieves reduced battery losses while maintaining AC power supply functionality.
Solution Approach 2:
The patent implements parameter changes by dynamically adjusting the common time-dependent offset voltage parameter. This offset is specifically designed to change over time in a manner that minimizes energy losses. The control system modifies voltage parameters to optimize current distribution and reduce losses in the battery internal resistance.
2Object-generated harmful factors
If PWM conversion is used in the B6 bridge converter, then DC voltage can be converted to AC phase voltages, but high harmonic voltages and currents are generated causing EMC problems
Solution Approach 1:
The patent extracts the harmonic generation problem from the conventional PWM converter by using a different approach. Instead of using PWM switching that inherently generates harmonics, the system uses a multi-level converter architecture where energy storage elements are connected in series/parallel combinations. This extracts the harmful harmonic generation from the voltage conversion process while maintaining the ability to generate AC phase voltages.
Solution Approach 2:
The patent introduces an intermediary common time-dependent offset voltage that mediates between the DC battery voltage and the AC phase voltages. This offset voltage acts as an intermediary signal that, when added to the phase voltages, reduces current variance and indirectly reduces harmonic content without compromising the voltage conversion capability.
3Loss of energy
If fast switching of high voltages is performed in the B6 bridge converter, then AC voltage generation is achieved, but high switching losses occur
Solution Approach 1:
The patent reduces switching losses by applying periodic action through the common time-dependent offset voltage. This offset is updated at optimal intervals and varies periodically to minimize current variance. By using periodic adjustment rather than fast continuous switching, the system achieves reduced switching losses while maintaining effective voltage control.
Solution Approach 2:
The patent implements dynamics by making the common time-dependent offset voltage adaptive and time-varying. Rather than using fixed high-speed switching, the system dynamically adjusts the offset voltage parameter over time to optimize performance. This dynamic approach reduces the need for frequent high-speed switching operations, thereby reducing switching losses.
Data Source
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AI summary
Disclosed herein is a system (20) for storing energy and providing N AC phase voltages. The system (20) comprises N pairs of modular energy storage direct converter systems (MESDCS) (22), wherein the first ends of the first MESDCS (22-1, 22-2, 22-3) of each of said N pairs are connected to a first common external terminal (32), the first ends (24) of the second MESDCS (22-4, 22-5, 22-6) of each of said N pairs are connected to a second common external terminal (34), and the second ends (26) of the j-th pair of MESDCS (22) are connected to a common j-th phase terminal (28-j), with j = 1, ...,N. The N pairs of MESDCS (22) are controlled such that a predetermined external voltage or voltage pattern Uo is provided between said first and second common external terminals (32, 34), and such that at each of said N common phase terminals (28-j), a corresponding AC phase voltage is applied. A time-dependent offset Uoff(t) that is common to each of said phase voltages Uj, is applied that allows for reducing battery losses in the system.