2005 EPE (Gerling - Hildebrand - Hofmann - Jungnickel - Lange - Pyc)

7/29/2019 2005 EPE (Gerling - Hildebrand - Hofmann - Jungnickel - Lange - Pyc)

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Test-Bench for Ultra High-Speed Electrical Drives

Dieter Gerling, Rainer Hildebrand, Harald Hofmann,Kathrin Jungnickel, Benno Lange, Marcin Pyc

Institute for Electrical DrivesUniversity of Federal Defense, Munich

Werner-Heisenberg-Weg 39D-85577 Neubiberg, Germany

phone: +49 89 6004 3708, fax: +49 89 6004 3718

e-mail: [email protected]

Keywords:

Electrical Machine, High-Speed Drive, Measurement, Test Bench

Abstract

In this paper, a test-bench for electrical drives with ultra high-speeds is described. The components of this

test-bench are explained and the respective characteristics are given. The entire system shows a capability of1

max140000 minn

= ,max

30NmT = andmax

39kWP = .

1. Introduction

There is a technical trend for electrical drives towards ever increasing speeds. This holds true for industrial

drives (e.g. servo drives or industrial pumps) as well as for other applications (e.g. vacuum cleaner). The

main reason is to reduce volume and weight at constant power level (or to increase the power level at

constant volume and weight). In addition, there are many applications, which intrinsically need a very high

speed, e.g. an electrical turbo-charger for the automotive industry. For such applications a test-bench has

been designed and realized that features extremely high rotational speed.

A special challenge for ultra high-speed drives is the direct torque measurement. In [1] it is mentioned that

spindle drives may reach 180000 min-1, but the described test set-up is just capable to reach 50000 min-1. In

addition the torque is measured by an eddy current brake. This means that the test-bench intrinsically is

passive.

Acceleration measurements on a 170kW, 76000min-1

drive are described in [2]. Even with this set-up no

direct torque measurement is possible.

In [3] the authors describe the testing of a 16kW, 15000min-1

drive. The test set-up is composed of d.c. load

machine, gear box and torque transducer. With this set-up, principally motor and generator operation can be

tested. The major drawback of this test-bench is the quite low maximum speed.

A back-to-back test of a high-speed generator (110kW, 70000min-1

) is described in [4]. As the load motor is

identical to the test motor, testing the power limits is very critical. In addition, in this paper the losses are

measured calorimetrically which means a very complex set-up.

It was our aim to design and realize a test-bench for medium power (30kW and above) and ultra high-speed

(well above 100000min-1) with the possibility of direct torque (and speed) measurement in motor and

generator (i.e. 4-quadrant) operation. With such a set-up, the drawbacks of known test-benches (passivebrakes, speed below 50000min-1, back-to-back test or calorimetric measurement) can be avoided.

Test-Bench for Ultra High-Speed Electrical Drives HILDEBRAND Rainer

EPE 2005 - Dresden ISBN : 90-75815-08-5 P.1


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2. Principle design of the test-bench

The design of the test-bench is composed of a high-speed inverter-driven induction motor as a load, a gear-

set to reach an ultra high-speed and a torquemeter specially designed for this speed level. In addition, a

controlled cooling system is applied to guarantee certain operating points during the measurements. Theprinciple set-up is shown in the block diagram below (figure 1).

Fig. 1: Principle set-up of the test-bench.

3. Components of the test-bench

3.1 Load

The load of this test-bench is composed of a 4-quadrant power electronics supplying the high-speed

induction motor. The inverter is operated with a switching frequency of 16kHzsf = and a power rating of

max52kVAS = . The induction motor has a maximum speed of

1

max25000minn

= , with a field weakening

range of 2:1. The maximum torque ismax

30NmT = .

GetriebeAntrieb/Last(drive/load)

1:1/1:3/1:9

Khlmittel

Prfling(temperature)

Temperatur

(temperature)

Messwelle Temperatur

0 0 00 0 0 0 0

0 - 260 V45 - 5000 Hz

I I I

0 0 0 0

Oszilloskop(oscilloscope)

Elektronisches Wattmeter

(test object)

Drehzahl (speed)

Drehmoment (torque)

(electronic powermeter)

(gear set)

Temperatur und Durchfluss geregelt(controlled temperature and flow)

(cooling fluid)

I I I

B6

UU I

B6

UU

I

50 Hz400 V

B6

I I




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The induction motor itself is supplied by a frequency inverter and control unit. As a consequence the motor

may be operated with field oriented control (FOC) or just by using a voltage-frequency-characteristic. The

closed-loop control region (torque or speed control can be selected) is limited to a maximum speed of

16000min-1. In the region between 16000min-1 and 25000min-1 just open-loop control is possible. The

reference value input may be realized by setting the system parameters (via Combivis), by analogue input

(e.g. potentiometer) , or by digital input (e.g. keyboard or bus). The bus used in our set-up is the CAN-bus.

3.2. Gear-set

The gear set, which was especially designed and built for this test-bench, offers different, selectable ratios:

1:1, 1:3, and 1:9. In addition, the maximum speed of this gear-set is limited to1

max180000 minn

= . This

limitation comes from the fact that the high-speed bearing at the output of the gear-set is not capable to reach

higher speeds. Moreover, this high-speed bearing requires an oil-pressure supply.

3.3 Torquemeter

Measuring torques at that high speed is a very delicate business. In this test-bench a measuring unit for

torque and speed has been introduced, that is capable of a maximum speed of1

max140000 minn

= . In

addition to this limitation, which limits the maximum speed of the entire test-bench, even the bearings of this

component have to be supplied by an external oil-reservoir. This oil-supply is a different one to that used for

the high-speed bearing of the gear-set. The software driver to read out the torque values has been realized

with the software package LabView.

The torque-speed-characteristics of the different parts of the entire test-bench (load motor, gear-set,

torquemeter) are shown in the following figure 2:

Fig. 2: Torque-speed-characteristics of load motor, gear-set and torquemeter.

0

5

10

15

20

25

30

35

0 25 50 75 100 125 150 175 200

Drehzahl (speed) in 1000/min

Drehmom

ent(torque)inNm Belastungsmotor (load motor)

1. Getriebestufe (1st gear)

2. Getriebestufe (2nd gear)

1. Messwelle (1st torque meter)

2. Messwelle (2nd torque meter)

P = 10 kW, 25 kW, 40 kW

0

5

10

15

20

25

30

35

0 25 50 75

0

5

10

15

20

25

30

35

0 25 50 75 100 125 150 175 200

Drehzahl (speed) in 1000/min

Drehmom

ent(torque)inNm Belastungsmotor (load motor)

1. Getriebestufe (1st gear)

2. Getriebestufe (2nd gear)

1. Messwelle (1st torque meter)

2. Messwelle (2nd torque meter)

P = 10 kW, 25 kW, 40 kW




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3.4 Safety means

Testing electrical motors at ultra high-speed means that in the rotating masses an extremely high energy is

stored. Even in the case of a malfunction, the use of the test-bench must be safe for the people operating this

set-up. To guarantee this, a box has been built covering all rotating parts. This box is made of a sandwich

structure with hard and soft material. The soft material is used for energy absorbing means, the hard material

guarantees that no particles will get out of this box.

3.5 Controlled cooling

The thermal behaviour of electrical drives critically determines the performance characteristics. Therefore,

the knowledge of the thermal state of the drive is an essential prerequisite for a detailed analysis (e.g.

efficiency measurements). This test-bench is equipped with a means for controlled liquid cooling of the test

objects. The parameters are: Maximum cooling powermax

13kWP = , controlled flow up to 60 l min and

controlled temperature of the cooling liquid in the region of 10C 90C +K .

3.6 Linear amplifier

The entire test-bench is completed by a linear amplifier of maximum powermax

5.25kVAS = in the

frequency region of 45Hz 5kHzK . This linear amplifier is used to drive the test motors in addition to an

inverter supply. From a comparison the influence of the inverter supply on the test drive can be measured.Such a comparison is of special interest in the ultra high-speed region (e.g. because of possible additionaliron losses as a consequence of the inverter supply). The following figure 3 shows a photograph of therealized test-bench with the most important components (the safety means, controlled cooling, and inverterfor supplying the load motor are not shown).

Fig. 3: Photograph of the realized test-bench.

Drehstromversorgung (3 Phase-AC Power Source)5,25 kVA 45 Hz-5 kHz Sinus

Asynchron-Antrieb/Last (4 Quadranten)

(4Q-IM-drive/load)

Getriebe (gear set)

Drehmomentmess-

welle (torquemeter)

Prfling

(test object)



(4Q-IM-drive/load)

Getriebe (gear set)

Drehmomentmess-

welle (torquemeter)

Prfling

(test object)



(4Q-IM-drive/load)

Getriebe (gear set)

Drehmomentmess-

welle (torquemeter)

Prfling

(test object)



(4Q-IM-drive/load)

Getriebe (gear set)

Drehmomentmess-

welle (torquemeter)

Prfling

(test object)




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3.7 Data acquisition

A very sophisticated data acquisition system is required for such a complex test-bench. To have a singlesystem for operating the test-bench as well as for data acquisition, the software package LabView is used.Measuring devices like a Yokogawa Precision Power Meter or the Torquemeter (see section 3.3) areincluded into the set-up. The user interface realized with LabView is as simple as possible to guarantee highconcentration of the people operating the test-bench: just the values of speed, torque and power aredisplayed, together with the temperatures at some critical spots. The measured data can be stored directly toan excel-file. The user interface is shown in the following figure 4.

Fig. 4: Screenshot of the user interface realized with LabView.

4. Summary

In this paper a test-bench for electrical drives with ultra high-speeds is described, making use of direct torqueand speed measurement on the high-speed shaft. The main system is composed of inverter-suppliedinduction motor, gear-set and torquemeter. The outstanding features are: maximum speed of

1

max140000 minn

= , maximum torque ofmax

30NmT = and maximum power ofmax

39kWP = .

In addition, a high performance means for controlled liquid cooling of the test objects (13kW , 60 l min ,

10C 90C +K ) is applied to this test-bench. Moreover, dedicated safety means, a linear amplifier and a

sophisticated data acquisition system accomplish the entire measurement set-up.

References

[1] A. Boglietti, P. Ferraris, M. Lazzari, F. Profumo: Test Procedure for Very High Speed Spindle Motors, IEEEIAS Annual Meeting, 1990, vol. 1, pages 102 108

[2] A. Castagnini, I. Leone: Test Results of a Very High Speed PM Brushless Motor, International Conferenceon Electrical Machines (ICEM), 2002, Brugge, Belgium

[3] B.C. Mecrow, A.G. Jack, D.J. Atkinson, S. Green, G.J. Atkinson: Design and Testing of a 4 Phase FaultTolerant Permanent Magnet Machine for an Engine Fuel Pump, International Electric Machines and Drives

Conference (IEMDC), 2003, Madison, WI, USA[4] O. Aglen: Back-to-Back Tests of a High Speed Generator, International Electric Machines and Drives

Conference (IEMDC), 2003, Madison, WI, USA



2005 EPE (Gerling - Hildebrand - Hofmann - Jungnickel - Lange - Pyc)

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