2019 Fiscal Year Research-status Report
Novel High Reliability DC/DC Modular Multilevel Converter as a Power Router for Next Generation Medium Voltage DC Power Network
| Project/Area Number |
19K14963
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| Research Institution | Kyoto Institute of Technology |
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Principal Investigator |
黄 品諭 京都工芸繊維大学, 電気電子工学系, 助教 (70835313)
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| Project Period (FY) |
2019-04-01 – 2021-03-31
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| Keywords | Ripple Cancel / Multilevel Converter / Medium voltage / Solid state transformer / Reliability / Power router / DC microgrid / DAB/TAB |
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| Outline of Annual Research Achievements |
Future medium voltage DC distributed microgrid is expected to be a high reliability power system. In power system, the converters are one of the most critical parts in terms of failure rate, lifetime, etc. Especially, the DC-link capacitor has highest failure ratio because of the high ripple current.
To solve this problem, three prototypes of power routers with different input/output voltage ranges were proposed and implemented.
All proposed converters have the ripple cancel characteristic of DC-link capacitors. The ripple current of DC-link capacitors is reduced to nearly zero. Thus, the reliability improvement of power routers in DC power distributed system can be expected. In addition, the modular multilevel configuration was proposed for future 6.6kV to 400V medium voltage applications.
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| Current Status of Research Progress |
Current Status of Research Progress
1: Research has progressed more than it was originally planned.
Reason
In 2019, three prototypes of ripple cancel type power routers were proposed and implemented to demonstrate the feasibility. First prototype is a 2-port basic unit circuit with 400V/400V/1kW. Second prototype is a 3-port basic unit circuit with 400V/400V/400V/1kW. Third prototype is a 2-port modular multilevel converter with 900V/600V/1kW.
The fundamental operation and circuit design consideration of proposed three converters were analyzed. The proposed converters demonstrated that the ripple current of DC-link capacitor is greatly reduced to nearly zero. In addition, the proposed modular multilevel configuration demonstrated that the low voltage stress switches can be applied to high input/output voltage applications and realized the voltage stresses auto balance on switches.
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| Strategy for Future Research Activity |
In the next year, the comparison between conventional bidirectional converter and proposed bidirectional ripple cancel type converter is scheduled. The converters comparison includes the features of efficiency, EMI, small signal models, and soft switching ranges.
To achieve the meshed power network system, the 3-port converter is considering as a potential topology because it can reduce the conversion steps and total number of power switches. Thus, the system efficiency can be further improved and make the power distribution system more cost-effectively.
Accordingly, the implementation of a 3-port modular multilevel configurations prototype is planned to demonstrate the feasibility of medium voltage DC distributed microgrid.
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| Causes of Carryover |
Due to COVID-19 this year, lots of international conferences were cancelled or rescheduled. Thus, it makes the difference of total actual expenditure on travel expenses and miscellaneous.
The amount to be used next fiscal year, 170270円, will be scheduled as the article cost for prototype implementation.
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Research Products
(4 results)
