Modular AC Phase Voltage Topology Without Polarity Reversing Circuits
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing modular energy storage direct converter systems (MESDCS) face inefficiencies in generating bipolar AC phase voltages due to the need for additional polarity reversing circuits and high-voltage switches, which increase costs and conductance losses.
Innovation Solution
A system and method utilizing N modular energy storage direct converter systems (MESDCS) with a control system to generate bipolar AC phase-to-phase voltages by connecting modules in series, parallel, and bypassing them, without requiring anti-series connections, using two-quadrant modules with fewer switches, and optimizing the offset voltage to minimize losses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If polarity reversing circuits are added to generate bipolar AC phase voltages, then the system can provide bipolar output voltages, but the number of switches and switching effort increases
Solution Approach 1:
The patent extracts the polarity reversing circuit from the system, realizing that bipolar AC phase voltages can be generated directly by the MESDCS without additional polarity reversing circuits. The converter arms connect converter modules in series to generate bipolar output voltages directly, eliminating the need for separate polarity reversal components.
Solution Approach 2:
The converter modules are designed to perform multiple functions: they can connect energy storage elements in series to generate high voltages, in parallel to generate low voltages, and bypass energy storage elements when needed. This multi-functionality allows the same modules to handle both voltage generation and polarity control without requiring dedicated polarity reversing circuits.
2Adaptability or versatility
If polarity reversing circuits are added to generate bipolar AC phase voltages, then the system can provide bipolar output voltages, but hardware costs and conductance losses increase
Solution Approach 1:
By removing the polarity reversing circuits, the patent eliminates the additional conductance losses and hardware costs associated with those components. The MESDCS generates bipolar voltages directly through series connection of converter modules, avoiding the energy losses that would occur in separate polarity reversal stages.
3Power
If modules are connected in series to generate higher voltages, then the output voltage increases, but the internal resistance of the converter arm increases
Solution Approach 1:
The patent implements dynamic switching of module connections, allowing the system to adaptively change between series and parallel configurations based on voltage requirements. When high voltage is needed, modules connect in series; when lower voltage is sufficient, modules can connect in parallel to reduce resistance, optimizing both voltage output and resistance characteristics in real-time.
4Loss of energy
If standard low-voltage silicon MOSFETs are used instead of IGBTs or silicon carbide-MOSFETs, then switching losses are reduced, but the system must operate at lower voltages
Solution Approach 1:
The patent segments the voltage generation into multiple converter modules, each operating at low voltage with efficient silicon MOSFETs. By connecting these low-voltage modules in series, the system achieves high output voltage while each individual module maintains low switching losses using standard silicon devices, avoiding the need for expensive IGBTs or silicon carbide-MOSFETs.
Data Source
AI summary
Disclosed herein is a system (20) for providing N bipolar AC phase voltages UVj, with j=1 . . . N, said system (20) comprising N modular energy storage direct converter systems (MESDCS) (22) and a control system (20), wherein the first ends (24) of each MESDCS (22) are connected to a common floating connection point (28), and wherein the j-th MESDCS (22) is controllable to output at its second end (26) a star voltage USj with respect to the floating connection point (28), with j=1, . . . , N, wherein said system (20) is configured to provide each of said phase voltages UVj as voltage differences between two of said star voltages, such that UVj=USj+1−USj, or UVj=USj−USj+1, for each j between 1 and N−1, and UVN=US1−USN, or UVN=USN−US1, respectively, wherein said control system (30) is configured to control each MESDCS (22) to output a corresponding unipolar star voltage Us, that can be decomposed into a periodic bipolar AC function Pj(t) and a unipolar offset Uoff(t) that is common to each star voltage USj, such that USj(t)=Pj(t)+Uoff(t), wherein the absolute value of said common unipolar offset Uoff(t) is at all times t sufficiently high that USj(t) is unipolar,wherein the periodic bipolar AC functions Pj(t) associated with different star voltages USj are phase-shifted copies of each other such that for each integers i, j chosen from [1, . . . , N] and k chosen from [1, . . . , N−1], Pi(t)=Pj(t+k·T/N), wherein T is the period of said periodic bipolar AC function Pj(t), wherein in particular, Pi(t)=Pj(t+(i−j)·T/N).