Development of a Gas Turbine Generator On-Board Electric Power Source for MAGLEV Trains

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Cuthbert Kennedy
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1 THE AMERICAN SOCIETY OF MECHANICAL ENGINEERS 305 E. 07 St., New York, N.Y The Society shall not be responsible for statements or opinions advanced in papers or In dis. cussion at meetings of the Society Or Divisions or Sections, or printed in its publications. Discussion is printed only If the paper is published In an ASME Journal. Papers are available Iron ASME for fifteen months after the meeting. Printed In USA. 92-GT-46 Copyright 1992 by ASME I Development of a Gas Turbine Generator On-Board Electric Power Source for MAGLEV Trains TERUO WASHIZU Toshiba Corporation Heavy Apparatus Engineering Lab. Yokohama, Japan SHOJI MATSUDA Toshiba Corporation MAGLEV Engineering Dept. Tokyo, Japan TERU MORISHITA Toyota Motor Corporation Higashifuji Technical Center Susono, Japan NOBUO TERAUCHI Railway Technical Research Institute Tokyo, Japan ABSTRACT I CONTI r,1cont.2 I CONT.3 I We have been jointly developing an on-board electric power source for MAGLEV trains by applying a 30kW generator for gas turbine hybrid passenger cars. Operating the generator on a test model apparatus simulating the generator installed in a MAGLEV train, we investigated its electrical and mechanical characteristics with the location close to superconducting coils. The effects of magnetic field on the generator's characteristics are investigated and described in this paper. MAGLEV trains require about a 50kW on-board power supply per car: At present, we are designing a 50kW gas turbine generator on the basis of the 30kW gas turbine generator. INTRODUCTION A hybrid system composed of a gas turbine engine and batteries has been developed as a new power supply for passenger cars (Nakamura, 1976) (Watanabe and Fukuda, 1985). With this system, the output of the gas turbine is convened into an electrical output by a generator directly coupled to the gas turbine, which is, after rectification by a rectifier, fed to the battery and a chopper. With the input power controlled by a chopper, the wheels are driven by the motor's output. The system diagram and the layout of the components in a passenger car are shown in Figs. I and 2 respectively. The ultra-high-speed generator runs at the same speed as the gas turbine, enabling a high output density (Washizu et al., 1984). Recently, we have developed a gas turbine generator based on the power generator of the gas turbine battery hybrid system for the on-board power source. This paper is a report on the system. On MAGLEV trains, the cars are coupled to each other in a bogie system, and superconducting coils are installed in the bogies. Basically, the power required for the car is obtained by r,csfc GT GT :Gas turbine G : Generator B : Battery C :Chopper M : DC motor. TIM :Transmission D : Differential gear W : Wheel 71M TITM TIDIF Tikt 00 CONT.1 : FJG controller CONT.2 : Field controller CONT.3 : Chopper controller ncd =TIC DIF Fig. 1 System diagram Fig. 2 Configurations electromagnetic induction due to the relative moment of the cars to magnetic field. When the train runs at a low speed, the gas turbine generator is necessary as an auxiliary system because induced Presented at the International Gas Turbine and Aeroenglne Congress and Exposition Cologne, Germany June 1-4, 1992

2 electrical power is of rather low level. Sufficiently compact, the gas turbine generators can be installed in dead spaces on the bogies to supply power to each car. For the on-board electric power source, we are proposing this system of installing a gas turbine generator on each car, which does not take up any of the space for passengers. This individual powersupply system will also improve the redundancy of the on-board electric power supply for MAGLEV trains. With the gas turbine generator placed at a location of the test apparatus where it can simulate the generator in a fully-equipped MAGLEV train, we investigated and analyzed the effect of the magnetic fields generated by the superconducting coils on the generator's characteristics. Installing a gas turbine generator, rated output 30kW, designed on the basis of the gas turbine hybrid system, on a test model apparatus, which simulated a MAGLEV train, we conducted tests while varying engine operation and magnetic field conditions. Inert gas Heater Bonding component Bottom lid NI, Top lid Pressure vessel Adiabatic layer Base ULTRA-HIGH-SPEED GENERATOR Fig. 4 Conceptual diagram of main body of HIP furnacfe A sketch of the structure of the generator is shown in Fig. 3. hours yielded the best results with a bonding strength of 85 kgf/ The magnetic circuit is shown by a line with arrows. MM 2. The structures of major components are outline below. Stator gq The core is made of laminated silicon steel sheets and is designed to be oil-cooled. The stator is internally sealed with a heatresistant material to prevent oil leakage. Excitation is performed by the solenoidal coils located at the each side of the stator core with the rotor serving as a magnetic pole. The magnetic flux is either clockwise (as shown in Fig. 3) or counterclockwise depending on the direction of the field current flow, but there is no difference in electrical properties. The rotor is a tandem type (claw type), having a circular crosssection with the space between tandem (claw) poles filled with nonmagnetic material to reduce windage losses. The rotor is manufactured by a HIP joining method. HIP stands for hot isostatic pressing. This is a diffusion bonding method that uses an inert gas such as argon as a pressure medium, and applies both a high temperature of several hundred degrees to 2000t and a high pressure of several hundred kgf/cm 2 to 2000 kgf/ cm 2 to the bonding components. The conceptual structure of a HIP furnace is shown in Fig. 4. The magnetic poles are made of a steel alloy, and the nonmagnetic material is a Ni-based super-alloy. To determine HIP conditions, tests were conducted with temperature and hold time varied against a constant Ar gas pressure of 1000 kgf/cm 2. A temperature of 1200t and a hold time of two Bearings The bearings are angular ball bearings. They are lubricated by a jet lubrication system because the dtnn value is above 2,000,000. The generator has been manufactured with the components as Armature coil Magnetic circuit (flux) Stator Magnetic field winding Rotor Fig. 3 Claw-pole type synchronous machine 2

3 described above, and various improvement measures have been taken as follows: Because of application for passenger cars, importance was given to increasing output density. The magnetic poles were designed with electromagnetically optimal shapes through static model and electromagnetic analyses. For mechanical strength, a mock-up rotor was manufactured and confirmed by spin tests. The field windings on the stator were wound directly on the structural part. To suppress the vibration, the outer bearing rings were supported with resilient 0-rings. The output density is 1.1 kw/kg, the highest for 30kW generators in Japan.. The generator is directly coupled to the gas turbine with splines. The specifications of the 30kW generator are shown in Table I. Type Form Rating Table 1 Specifications of the 30kW generator Claw-pole type synchronous machine Ball bearing Oil cooling Flange Direct couple 2p-30kW-86,000rpm-1,433Hz-145V 125.8A-0.95pf-C-conti. TEST APPARATUS AND MEASUREMENT It is considered that the magnetic field of the generator might be affected by the superconducting coils when excited. It is also considered that there might be decreases in mechanical performance such as wear to bearings due to vibration, noise, etc., as well as decreases in power generation performance. The test apparatus is shown in Fig. 5. The base, enclosure, and scaffolding that support the gas turbine generator are made of aluminum or wood to enable the magnetic field to be applied directly to the generator. The system for measuring generator characteristics and measuring instruments are shown in Fig. 6. We also measured noise. To recognize how the electrical characteristics of the generator are affected by the magnetic field generated when the superconducting coils are excited, the terminal voltage V, of the generator should be measured, while varying the no-load characteristics of the generator in the field current If range: 0-23A of the generator. Then, the load characteristics of the generator should be measured. This is to measure the DC voltage and current VDc and l the on-load resistance side in the field current If range of 0 23A. Gas turbine Controller railleill Shunt resistance Operating panel Ini 1 i Volt To. Generator Rectifier xperience E room mete AC) --1 Measuring 1:1 n MOM 6 Pen recorder Am re meter (DC) Volt meter (DC) Resistance (Load) Fig. 6 Block diagram of the generator and measuring instruments Gas turbine generator Enclosure Engine auxiliaries Base Superconducting coil Scaffolds Fig. 5 Gas turbine generator test apparatus 3

4 While changing the direction of the field current, a test should be conducted to check if the electrical characteristics change depending on the direction of the magnetic field generated by the excited superconducting coils and that of the magnetic flux in the generator. The magneto-motive force of superconducting coils during the tests are 500 and 7001cAT. Then, the preliminary currents Pc are 5001cAT and the rating currents Pc are 700kAT. 300 TEST RESULTS The test was conducted over four days. The no-load and onload characteristics of the generator are shown in Figs. 7 and 8 respectively. As Fig. 7 shows, there is little difference in induced voltage between with the superconducting coils excited (Pc = 5001cAT or 700kAT) and not excited (Pc = 0), although the no-load induced voltage of the generator shows a little scatter. Figure 8 shows that there is no difference in generator output under the same superconducting coil conditions as in Fig. 7. No change is seen either when the field current flow of the generator is reversed. Noise-measuring positions and noise levels are shown in Fig. 9 and Table 2 respectively. As to noise levels, there is no difference between when superconducting coils are excited and not. Also, no change is seen either when the the generator's field current direction is reversed. This proves that the performance of a gas turbine generator is not affected by the magnetic field of the uperconducting coils. Pc (kat) A Exciting field current: If (A) Fig. 7 No-load saturation curve Fig. 9 Noise-measuring position A Pc (kat) Table 2 Noise level Unit: db (A scale) Position Condition A B Rating speed (86,000rpm) Idling speed (30,000rpm) Background noise Exciting field current: If (A) Fig. 8 Characteristics of generator output power 4 CONCLUSION The test results proved that the gas turbine generator, as an onboard power source for MAGLEV trains under conditions simulating installation on a fully equipped car, was not affected by

5 the magnetic field of the superconducting coils. After the test, we disassembled the gas turbine generator for inspection, discovering that none of the parts including the bearings were damaged. We reassembled the machine and checked its electrical and mechanical performance including noise aspects. As a result, we discovered no changes. Thus, we found the gas turbine generator promising for application as an on-board power source. At present, we are engaged in designing a gas turbine generator at the level of 50kW, which is the requirement per car of MAGLEV trains. REFERENCES Nakamura,.K., 1976, "Gas Turbine Powered Passenger Car," Journal of ISME, Vol. 79, pp Washizu, T., et al., 1984, "Prototype Development of 30kW Ultra-high-speed Rotary Electric Machines," Nishishiba Review, Vol. 18, pp Watanabe, A., and Fukuda, D., 1985, "An Experimented Study on Gas Turbine/Battery Hybrid-Powered Vehicle," ASME Paper 85- GT 203 5

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