Three-Phase DAB DC-DC Converter Phase Angle Control
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Solution Overview
Problem
Conventional Dual Active Bridge (DAB) DC/DC converters face challenges in rapidly regulating current while minimizing oscillations during power changes, leading to reduced dynamics and asymmetrical current distribution due to high leakage inductance and low ohmic losses.
Innovation Solution
A method for operating a three-phase DAB DC/DC converter with independently adjustable phase angles between primary and secondary AC voltages, allowing rapid phase angle changes to minimize oscillations and achieve dynamic current regulation, using actively switched voltage bridges and a multi-phase transformer to control power flow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the phase angle is changed rapidly to achieve fast current regulation, then the dynamics of current control is improved, but oscillations and asymmetrical current distribution occur
Solution Approach 1:
The patent segments the phase angle control into independent per-phase control, allowing each phase to be adjusted individually rather than as a unified system. This enables rapid phase angle changes while maintaining current distribution symmetry by compensating for asymmetries in each phase separately.
Solution Approach 2:
The patent changes the control parameter from a unified phase angle to independent per-phase phase angles. By adjusting each phase's phase angle independently based on its specific current distribution characteristics, the system achieves fast regulation without causing asymmetrical current distribution.
2Stability of the object's composition
If the phase angle is changed slowly to minimize oscillations, then current distribution symmetry is maintained, but the dynamics of current control is reduced
Solution Approach 1:
The patent divides the control system into independent per-phase controllers that can operate simultaneously. This segmentation allows the system to achieve fast response by adjusting multiple phases in parallel while maintaining symmetry through individualized control of each phase.
Solution Approach 2:
The patent implements dynamic per-phase phase angle adjustment where each phase can be rapidly adjusted according to its specific conditions. This dynamic control approach enables fast current regulation while preventing oscillations through real-time symmetry maintenance.
3Adaptability or versatility
If high leakage inductance is used to enable wide voltage range operation, then voltage adaptability is improved, but the oscillation decay time constant increases
Solution Approach 1:
The patent changes the control approach from adjusting a single unified phase angle to independently adjusting per-phase phase angles. This parameter change allows the system to compensate for the increased oscillation time constant caused by high leakage inductance, enabling rapid current regulation despite the wider voltage range operation capability.
Solution Approach 2:
The patent creates independent control copies for each phase, allowing parallel adjustment of multiple phases. This copying approach enables the system to overcome the slow oscillation decay caused by high leakage inductance by simultaneously adjusting multiple phases to achieve the desired current distribution.
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
Enables fast and dynamic power transmission with minimized oscillations and symmetrical current distribution, suitable for medium to high power applications with high dynamic requirements.
Implementation Method 1
the DC input voltage is converted into an AC voltage in an input converter and is thus fed to a transformer. The output of the transformer is connected to an output converter that converts the AC voltage back into a DC output voltage
Data Source
Figure 1
Figure 2(a)~2(c)
Figure 3
AI summary
The invention relates to DC-DC converters having a so-called dual active bridge (DAB) topology and to a method for operating these DC-DC converters having a primary side (1) comprising at least three actively switched primary-side voltage bridges (11, 12, 13) with a plurality of active switches (S1) for converting a DC input voltage (ES) into primary-side AC voltages (111, 112, 113) for each of the primary-side voltage bridges (11, 12, 13) and having a secondary side (2) comprising at least three actively switched secondary-side voltage bridges (21, 22, 23) with a plurality of active switches (S2) for converting the secondary-side AC voltages (211, 212, 213) for each of the secondary-side voltage bridges (21, 22, 23) into a common DC output voltage (AS), wherein the primary-side and the secondary-side AC voltages (111, 112, 113, 211, 212, 213) are each shifted by a phase angle φ with the periods T, and each of the primary-side and secondary-side voltage bridges (11, 12, 13, 21, 22, 23) is coupled to one phase in each case via one or more transformers (3), comprising the steps of adjusting the phase angle φ from a first phase angle φ1 to a second phase angle φ2 as a switching operation for transmitting power from the primary side (1) to the secondary side (2), wherein the primary-side and secondary-side voltage bridges (11, 12, 13, 21, 22, 23) are switched in the switching operation in such a manner that the phase angles φ of the individual phases are adjusted in the switching operation in a manner temporally independent of one another, as a result of which it is possible to quickly control the current while simultaneously minimizing the oscillations in the DC current in the event of power changes.