Development of Advanced
Energy-efficient Transportation
Systems Using High-Performance
Batteries
HIROSHI OGAWA*1

HIROSHI YAMASHITA*2		

KATSUAKI MORITA*2

Mitsubishi Heavy Industries, Ltd. (MHI) is involved in the development of transportation systems such as automated people
movers (APMs) and light rail transit (LRT). These systems have attracted great public enthusiasm as effective means of transportthat are friendly to both people and the environment. MHI is currently developing a new environmentally friendly battery-poweredtransportation system. The use of high-performance, high-capacity batteries will not only improve electrical power efficiency but also
contribute to a less-cluttered urban landscape and simplified operation by eliminating catenary wires. The system is completing its
final operational testing on MHI’s own test track and is in the final productions stages, with demonstrations for potential customers
to follow shortly.

1.1 Battery-powered transportation systems
With environmental issues attracting increasing attention
worldwide, MHI has been developing automated people
mover (APM; Fig. 1) and light rail transit (LRT) systems(Fig. 2) to solve traffic problems such as congestion, noise,and various other environmental issues. Major cities aroundthe globe are welcoming APMs and LRT as means of peoplefriendly transportation that are also environmentally sound.
APMs are an effective means of public transit used between
terminals in an airport or within a metropolitan area. They
almost operate unattended and are equipped with rubber
tires to reduce noise and vibration.
LRT vehicles are a new generation of streetcar with highperformance and stylish appearance. Their barrier-freedesign with extremely low floor levels makes them easily

accessible to all. These features contribute to LRT’s favorable
acceptance as an effective means of public transit.
Using battery power for vehicles in a guideway transportsystem to eliminate the conventional catenary lines offers
the following features:• energy savings due to the efficient regeneration of power
during braking, and elimination of power transmission loss;• uncluttered space by eliminating the catenary wires andutility poles that would otherwise spoil the view;• reduction in construction time and cost;• reduction in maintenance costs and improvement in
occupational safety by eliminating catenary wires andassociated maintenance work involving high voltages andelevated work platforms.
The system is highly energy efficient and thus environmentallyfriendly; no power transmission loss occurs because no catenarylines are involved, and power is recovered for reuse during

Fig. 1 APM : Automated people mover

Fig. 2 LRT : Light rail transit

1. Features of battery-powered transportation systems

Mitsubishi Heavy Industries, Ltd.
Technical Review Vol. 45 No. 1 (Mar. 2008)*1 Plant and Transportation Systems Engineering & Construction Center*2 Hiroshima Research & Development Center, Technical Headquarters77efficient regenerative braking. The contribution to preserving
scenic city views by eliminating catenary wires is a majoradvantage.
Many research organizations and vehicle manufacturers
have been studying battery-powered transportation systems.
Since its early development stages, MHI’s work has focusedon lithium-ion batteries as the vehicle-mounted power source.
1.2 Application of high-capacity batteries
A mong the various types of high-performance, highc a p a c i t y b a t t e r i e s b e i n g de ve l o p e d fo r a ut o m o t i ve
applications, lithium ion stands out as being capable ofstoring and instantaneously supplying high power, andallowing stable continuous charging and discharging athigh currents. Lithium-ion batteries are the most suitablefor A PM and LR T vehicles with their operating patternsof repeated and frequent high rates of acceleration anddeceleration. Approximately 40–50% of the energy consumed
when accelerating can be recovered during braking and thenreused. In addition, while parked at a terminal or a station
at the end of a route, for example, up to half the total energy
required for the next recharging can be quickly transferredin less than 5 minutes depending on the route characteristics
and the vehicle operation schedules. Because of their high-energy density, lithium-ion batteries are small and compact
enough to fit into the limited space available in the vehicle.
Once recharged, a lithium-ion battery is capable of running
the vehicle for a distance of 10 kilometers or longer without
recharging.

2. Development outline
2.1 System configuration
Figure 3 shows examples of battery-powered transportation
system configurations. Fed by the direct-current electric
power f rom the bat ter y, the va r iable volt age va r iablefrequency (VVVF) inverter drives the induction motor. The
V V VF inverter also efficiently returns regenerative energy
to the battery during braking. The same battery supplies
electrical power for air conditioning, fluorescent lighting, andother vehicle devices through the static inverter (SIV) thatconverts the direct current into alternating current.
MHI is studying several different and flexible configurations
as shown in the following examples. Figure 3(a) presents aconfiguration suited to new railway construction in which nocatenary wires are used. Quick recharging takes place whilethe vehicle is at rest. Figure 3(b) is applicable to a routein which part of the track is under catenary wires, but theElectric power feeder for recharging
Power collector dedicated to recharging

Waysidepower supply
for recharging

VVVF
inverterBatteries

MotorMotor

SIV(a) Example of the system for a rail track with no catenary wires
Electric power feeder for recharging
Power collector for both recharging
and running beneath catenary wires
Waysidepower supplyfor recharging

Selector switch

VVVF
inverterBatteries

Fig. 4 Operational testing of a battery-powered APM vehicle

Motor
Motor

SIV

(b) Example 1: System for a route having partial catenary wires(power supply from a wayside recharger)
Power collector for zones with caternay wires
Battery charger

VVVF
inverterBatteries

Motor
Motor

SIV
(c) Example 2: System for a route with partial catenary wires(recharging from the catenary wires during running or while stopped)
Fig. 5 Operational testing of a battery-powered LRT vehicle

Fig. 3 Examples of system configurations for battery-powered LRT

Mitsubishi Heavy Industries, Ltd.
Technical Review Vol. 45 No. 1 (Mar. 2008)78

operation has been extended to a new section that has nooverhead wires. The power supply switches back and forth
between the pantographs/catenaries and the batteries asrequired. Quick recharging also takes place during stops.
Figure 3(c) shows a configuration in which the vehicle isequipped with an internal battery charger that charges thebattery while the vehicle is running under the catenarywires.
2.2 Operational testing
Figures 4 and 5 are photographs of the operational
testing of battery-powered APM and LRT vehicles on MHI’s
test track. The range of running tests includes operation atvery low temperatures to improve the commercial viability ofthe products under realistic operating conditions. Collecting
and verif ying the data obtained from the running tests
enables simulation of the power consumption of batterypowered vehicles while taking into account the battery
characteristics. The simulated results are used to study thelayout of a power recharging system along an actual track as
well as to evaluate the capacity, life, and other parameters of
the batteries installed on the vehicles.

3. Conclusions
This paper has briefly described MHI’s development ofnext-generation transportation systems using high-capacitybatteries. MHI is currently in the process of producing
a new demonstration vehicle. In addition to the ongoingcomprehensive system tests, customer demonstrations arealso scheduled. MHI wishes to promote the production ofthese products as environmentally friendly transportation
systems that are attractive to both transit authorities andpassengers.
References
1. Kashiwa, M. et al., Automated People Mover "Crystal Mover"for Singapore Changi International Airport, Mitsubishi HeavyIndustries Technical Review Vol. 44 No. 2 (2007)
2. Ogasa, M. et al., Plant Test Results of Trolley & Battery Hybrid
Power Control to Suppress the Regeneration Cancellation, Papersof 11th Railway Technology Symposium
3. Ogawa, H. et al., Development of Automatic Steering & Battery
Powered Automated People Mover, Mitsubishi Heavy Industries
Technical Review Vol. 44 No. 2 (2007)

Hiroshi Ogawa

Hiroshi Yamashita

Katsuaki Morita

Mitsubishi Heavy Industries, Ltd.
Technical Review Vol. 45 No. 1 (Mar. 2008)

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