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General information
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Description
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Principle
Insulated Gate Bipolar Transistors (IGBTs) are today's state-of-the-art power
electronics for the traction system of electric (and diesel-electric) rail
vehicles. They replace the previous inverter generation represented by GTO (gate
turn-off thyristors).
In contract to conventional transistors, IGBTs operate at very high currents
(> 1000 A). The principle benefit of IGBTs over GTOs is a much (3 to 4 times)
higher switching frequency. This reduces the current required and therefore the
heat generated, giving smaller and lighter units. The high switching frequencies
also smoothen the acceleration process and reduce the traction noise.
Fields of application
Power electronics based on IGBTs are used in a number of fields in industry
and transportation. |
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General criteria
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Status of development: in use |
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In the course of the last years, all major manufacturers of railway traction technologies have completely migrated to IGBT technology. This migration has already taken place some years ago in the MU segment and is presently taking place in the locomotive segment of around 7 MW. |
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Time horizon for broad application: now |
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(no details available) |
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Expected technological development: highly dynamic |
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Although IGBTs have reached maturity, R&D dynamics is still high in this
field, Major aims are:
- raise blocking voltages
- increase switching frequency
- reduce losses
- reduce weight
The IGBT itself is integrated in a complex power module which includes
besides the transistor the circuits and the cooling etc. These "peripherals"
offer even more potential for future optimisation than the IGBT
itself. |
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Motivation:
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Energy efficiency |
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Benefits (other than environmental): big |
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- Reduced switching losses (compared to GTO)
- Less cooling required (no organic coolants required)
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Barriers: low |
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Refurbishment costs
Refitting old vehicles with IGBTs is usually not profitable (for present
energy prices). Diffusion is therefore essentially limited to stock
renewal. |
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Success factors:
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(no details available) |
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Applicability for railway segments: high |
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Type of traction: electric - DC, electric - AC, diesel
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Type of transportation: passenger - main lines, passenger - high speed, passenger - regional lines, passenger - suburban lines, freight
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IGBTs are generally applicable to electric traction motors. This includes electric and diesel-electric traction.
Refitting old vehicles with IGBTs is expensive, but has been realised in some cases, e.g. NS Reizigers has refurbished their Sprinter train sets with IGBT choppers. |
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Grade of diffusion into railway markets:
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Diffusion into relevant segment of fleet: 5 - 20% |
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Share of newly purchased stock: > 50% |
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Diffusion into relevant segment of fleet
Most fleets have already a considerable share of vehicles with IGBTs, others
like the SBB fleet don't have any IGBT stock yet.
Share of newly purchased stock
Siemens claims that virtually all electric rail vehicles presently produced
at Siemens Transportation are based on IGBT traction systems. |
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Market potential (railways): high |
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(no details available) |
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Example:
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(no details available) |
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Environmental criteria
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Impacts on energy efficiency:
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Energy efficiency potential for single vehicle: 5 - 10% |
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Energy efficiency potential throughout fleet: > 5% |
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Improved traction efficiency
According to an expert from Bombardier, the efficiency of the IGBT at payload
is about 5 - 6% better than the efficiency of the GTO (95% vs. 90 % efficiency).
The effect on energy efficiency in real operation maybe even bigger due to the
fact that the relative advantage of IGBTs over GTOs is even higher at low loads.
This may push the efficiency gain even beyond 10%. for instance, Japanese JR
Hokkaido claims that IGBT controlled 3-phase AC motors save 15 % energy compared
to their GTO predecessors.
Mass reduction
IGBT modules are generally lighter than GTO modules (some 30%). This may
offer constructive advantages but is negligible for energy
efficiency. |
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Other environmental impacts: positive |
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Noise reduction
Japanese JR Hokkaido claims that IGBT controlled 3-phase AC motors reduce
noise by 10% compared to their GTO counterpart. |
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Economic criteria
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Vehicle - fix costs: low |
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IGBT drive technology is a mature technology in rail vehicles. It does not substantially increase the vehicle price compared GTO or other technology. |
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Vehicle - running costs: significant reduction |
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(no details available) |
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Infrastructure - fix costs: none |
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(no details available) |
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Infrastructure - running costs: unchanged |
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(no details available) |
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Scale effects: low |
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Scale effects within railways have already been exploited. Scale effects from mass markets are unlikely since the specifications (e.g. blocking voltage) for railway IGBTs require dedicated development and production. |
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Amortisation: < 1 year |
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(no details available) |
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Application outside railway sector
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Status of development outside railway sector: in use |
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(no details available) |
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Time horizon for broad application outside railway sector: now |
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(no details available) |
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Expected technological development outside railway sector: highly dynamic |
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cf. XXX
At present, no innovations in power electronic replacing IGBTs are close to
market stage in the low-power segment, which is usually an early monitor for
later developments in the power segments relevant for railway
applications. |
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Market potential outside railway sector: high |
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(no details available) |
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Overall rating
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Overall potential: very promising |
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Time horizon: short-term |
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The advent of IGBTs has yielded strong efficiency gains in electric drive technology. There are no barriers for introduction. However, diffusion is essentially limited to stock renewal since refurbishment is possible but usually too expensive. |
click icon to print 
date created: 2002-10-09
