measurement and analysis of common mode voltage … · module 3: five level diode clamped...

http://www.iaeme.com/IJEET/index.asp 16 [email protected]

International Journal of Electrical Engineering & Technology (IJEET) Volume 7, Issue 4, July–Aug, 2016, pp.16–22, Article ID: IJEET_07_04_002

Available online at

http://www.iaeme.com/IJEET/issues.asp?JType=IJEET&VType=7&IType=4

ISSN Print: 0976-6545 and ISSN Online: 0976-6553

Journal Impact Factor (2016): 8.1891 (Calculated by GISI) www.jifactor.com

© IAEME Publication

MEASUREMENT AND ANALYSIS OF COMMON

MODE VOLTAGE IN CASE OF MULTI LEVEL

INVERTER FED INDUCTION MOTOR DRIVE

Prafulla J. Kale

Department of Electrical Engineering, Govt. College of Engineering,

Aurangabad (M.S), India

Dr. V. A. Kulkarni

Department of Electrical Engineering, Govt. College of Engineering,

Aurangabad (M.S), India

ABSTRACT

In this paper, a method, to reduce the common mode voltage (CMV) using diode clamped

multilevel inverter (DCMLI) with Pulse Width Modulation Technique for three phase induction

motor drive is presented. Simulation model of Conventional Two Level Inverter fed Induction

Motor (IM); Three Level Diode Clamped Inverter fed IM, Five Level Diode Clamped Inverter

(FLDCI) fed IM with POD SPWM Technique are developed under MATLAB-SIMULINK. A

Miniature Model of Three Level Diode Clamped Inverter fed Induction Motor Drive is developed.

Simulation Results versus Hardware Results are compared to examine Common Mode Voltage.

Key words: CMV, DCMLI, FLDCI, MV, POD SPWM, THD

Cite this Article: Prafulla J. Kale and Dr. V. A. Kulkarni, Measurement and Analysis of Common

Mode Voltage In Case of Multi Level Inverter Fed Induction Motor Drive. International Journal of

Electrical Engineering & Technology, 7(4), 2016, pp. 16–22.

http://www.iaeme.com/IJEET/issues.asp?JType=IJEET&VType=7&IType=4

1. INTRODUCTION

Inverters are widely used in variable speed drives because of their ability to control the magnitude &

frequency of the output voltage. Common mode voltage is main disadvantage of 2-level inverter. The Shaft

voltage and the premature failure of the bearings is mainly effect of CMV [1]. The simultaneous switching

of the series connected devices generates voltage with a high dv/dt at the output terminal of the inverter

[2]. Hence, in the applications of AC motor drives, the analysis of the common mode voltage is important.

A MLI can reduce as well as eliminate the CMV & reduces harmonic distortion at low switching

frequency. Among the configurations of multilevel inverter, 5-level diode clamped multilevel inverters

have some advanced features hence simulation is performed using FLDCI & simulation results show that it

reduces CMV as well as THD [3]. A passive electromagnetic interference (EMI) filter can keep the shaft

voltage in check and eliminate both bearing current and ground current from an inverter-driven motor rated

at 400 V, 3.7 kW [4-11].

Measurement and Analysis of Common Mode Voltage In Case

http://www.iaeme.com/IJEET

2. MULTILEVEL INVERTER

The basic structure of the multilevel inverter is to synthesize a sinusoidal voltage from several levels of

voltages typically gain from capacitor voltage sources. “Multilevel” starts from three levels

of multilevel inverter control is an alternative solution for induction

performance equally that of dc motors

diode clamped inverters, flying capacitor inverters and cascaded inverters.

3. DIODE CLAMPED MULTIL

The number of main switches in each topology is equal. Comparison with other types, diode clamped

inverters require less number of capacitors but require additional clampin

clamped multilevel structure is better for high and medium voltage drives which are easily connected to the

utility drive. The Diode Clamped Multilevel Inverter typically consists of (m

in which m is the total number of positive, negative and zero levels in the output voltage. Figure1 shows a

three phase half-bridge five level diode clamped inverter. The order of numbering of the switches for phase

x is Sa1, Sa2, Sa3, Sa4, Sa1‟, Sa2‟

of four capacitors C1, C2, C3 and C4 act as voltage divider. For a DC bus voltage Vdc, the voltage across

each capacitor is Vdc/4 and voltage stress on each (Switch) device is limited to Vdc/4 through clamp

diode. The midpoint of the four capacitors “n” can be defined as the neutral point. Table 1 shows the

output voltage levels and the corresponding switch states for one phase of the chosen five levels DCMLI.

The switches are arranged into 4 pairs (Sa1,

the pair is turned on, the complementary switch of the same pair must be off. Four switches are triggered at

any point of time to select the required

Figure 1 A three phase five level DCMLI

4. COMMON MODE VOLTAGE

In the applications of AC motor drives, the analysis of the common m

between the neutral point of the star connected motor (node n) to the earth ground (node e),

common mode current [2]. The Shaft voltage and the premature failure of the bearings is mainly effect of

CMV. The simultaneous switching of the series connected devices produces voltage with a high dv/dt at

the output terminal of the inverter.

application. It is very important to reduce the CMV and limit this voltage within certain bounds. A MLI

can reduce as well as eliminate the CMV

passive filters and dual bridge inverters but

CMV [5]. Causes of CMV are leakage current, bearing current & Bearing Failure.

f Common Mode Voltage In Case of Multi Level Inverter Fed Induction Motor Drive

EET/index.asp 17

MULTILEVEL INVERTER


voltages typically gain from capacitor voltage sources. “Multilevel” starts from three levels

of multilevel inverter control is an alternative solution for induction motor which is operated to achieve

performance equally that of dc motors [5]. The main multilevel configuration is classified into three types:

ing capacitor inverters and cascaded inverters.

DIODE CLAMPED MULTILEVEL INVERTER


inverters require less number of capacitors but require additional clampin


utility drive. The Diode Clamped Multilevel Inverter typically consists of (m-1) capacitors on the DC bus

e total number of positive, negative and zero levels in the output voltage. Figure1 shows a

bridge five level diode clamped inverter. The order of numbering of the switches for phase

‟, Sa2‟, Sa3‟ and Sa4‟ and likewise for other two phases. The DC bus consists


each capacitor is Vdc/4 and voltage stress on each (Switch) device is limited to Vdc/4 through clamp



The switches are arranged into 4 pairs (Sa1, Sa1‟), (Sa2, Sa2‟), (Sa3, Sa3‟), (Sa4, Sa4


any point of time to select the required level in the five levels DCMLI [5].

ee phase five level DCMLI Table I Switching State and Magnitude of

OLTAGE

In the applications of AC motor drives, the analysis of the common mode voltage is important. It occurs

he star connected motor (node n) to the earth ground (node e),

The Shaft voltage and the premature failure of the bearings is mainly effect of


the output terminal of the inverter. The sudden rise in inverter voltage is hazardous to the motor drive


s eliminate the CMV [3]. Some approaches to reduce CMV include four leg inverters,

and dual bridge inverters but five level diode clamped inverter is the best option to reduce

. Causes of CMV are leakage current, bearing current & Bearing Failure.

f Multi Level Inverter Fed Induction Motor Drive

[email protected]


voltages typically gain from capacitor voltage sources. “Multilevel” starts from three levels. The concept

motor which is operated to achieve

The main multilevel configuration is classified into three types:


inverters require less number of capacitors but require additional clamping diodes. Hence the diode


1) capacitors on the DC bus

e total number of positive, negative and zero levels in the output voltage. Figure1 shows a

bridge five level diode clamped inverter. The order of numbering of the switches for phase

ikewise for other two phases. The DC bus consists


each capacitor is Vdc/4 and voltage stress on each (Switch) device is limited to Vdc/4 through clamping



‟), (Sa4, Sa4‟). If one switch of


Switching State and Magnitude of Output voltage [5]

ode voltage is important. It occurs

he star connected motor (node n) to the earth ground (node e), it leads to

The Shaft voltage and the premature failure of the bearings is mainly effect of


hazardous to the motor drive


Some approaches to reduce CMV include four leg inverters,

level diode clamped inverter is the best option to reduce

. Causes of CMV are leakage current, bearing current & Bearing Failure.

Prafulla J. Kale and Dr. V. A. Kulkarni


5. MODELING & SIMULATION OF DIODE CLAMPED MULTILEVEL

INVERTER

An Inverter fed three phase squirrel cage Induction Motor is used for simulation. Reduction of common

mode voltage and Total Harmonic Distortion in Line Voltage is obtained by using Multilevel Inverter as

explained in this paper. Analysis of CMV of the Three phase Induction Motor by using different Level

Inverter i.e. Two Level Inverter, Three Level Inverter and Five Level Inverter. Here, Two Level Inverter

and Three Level Inverter is control by using PWM technique. In Five Level Diode Clamped Inverter,

SPWM technique is used to reduce CMV as well as THD.

MODULE 1: TWO LEVEL INVERTER FED INDUCTION MOTOR

Induction Motor is fed by Conventional Two Level Inverter. Simulation in MATLAB environment has

been made for full load torque condition. In these Two Level Inverter, two levels i.e. +300 and -300 of

output voltage is obtained. CMV from simulation result of Conventional method is found to be 300V to -

300V. From FFF analysis THD is obtained 80.63% in Line Voltage of Two Level Inverter. Here, CMV is

high and THD is also more.

Output Voltage of Two Level Inverter

Figure 2 Output Voltage waveform of Two level Inverter

CMV of Two Level Inverter THD of Two Level Inverter

Fig.3 Common Mode Voltage waveform of Fig.4 Total Harmonic Distortion Two level Inverter Fed Induction

Motor Two Level Inverter

MODULE 2: THREE LEVEL INVERTER FED INDUCTION MOTOR

Induction Motor is fed by Three Level Inverter. Simulation in MATLAB environment has been made for

three fourth load torque condition. In this Module of Three Level Inverter should get three levels of output

voltage and ±Vdc/3 CMV.

Measurement and Analysis of Common Mode Voltage In Case of Multi Level Inverter Fed Induction Motor Drive


Output Voltage of Three Level Inverter

Figure 5 Output Voltage waveform of Three Level Inverter

CMV of Three Level Inverter THD of Three Level Inverter

Fig.6 Common Mode Voltage waveform Fig.7 Total Harmonic Distortion of Three level Inverter Fed Induction

Motor of Three Level Inverter

From Three Level Inverter output waveform three levels i.e. -300V, 0V and +300V of output voltage is

obtained. Three Level Inverter is operates in 27 switching states. The CMV varies from -200V to +200V

can be observed from waveform of CMV of Three Level Inverter. From FFF analysis THD is obtained

42.22% in Line Voltage of Two Level Inverter. Here, comparison with Two Level Inverter CMV & THD

decreases.

MODULE 3: FIVE LEVEL DIODE CLAMPED MULTILEVEL INVERTER FED

INDUCTION MOTOR

Induction Motor is fed by Five Level Diode Clamped Inverter. Simulation in MATLAB environment has

been made for full load torque condition. In this Module of Five Level Diode Clamped Inverter should get

five levels of output voltage and ±Vdc/12 CMV



Output voltage of five level Diode Clamped inverter

Figure 8 Output Voltage waveform of FLDC Inverter

CMV of FLDC Inverter THD of FLDC Inverter

Figure 8 Common Mode Voltage waveform of FLDCI Figure 9 Total Harmonic Distortion of FLDCI Fed

Induction Motor

From Five Level Diode Clamped Inverter output waveform, five levels i.e. -300V, -150, 0V, +150 and

+300V of output voltage is obtained. Five Level Inverter is operates in 125 switching states. The CMV

varies from -50V to +50V can be observed from waveform of CMV of Five Level Diode Clamped

Inverter. From FFF analysis THD is obtained 34.21% in Line Voltage of Five Level Diode Clamped

Inverter.

Table II Comparision of Total Harmonic Distortion In Line Voltage And Common Mode Voltage

THD in Line Voltage CMV

Two Level Inverter 80.51% ±Vdc/2

Three Level Inverter 42.14% ±Vdc/3

FLDC Inverter with POD SPWM 34.21% ±Vdc/12

Measurement and Analysis of Common Mode Voltage In Case of Multi Level Inverter Fed Induction Motor Drive


Here, CMV is decreases as compare to CMV of Two Level and Three Level Inverter. THD is also

decreases as compare to Two Level and Three Level Inverter.

MODULE 4: HARDWARE PROTOTYPE OF 3-LEVEL DIODE CLAMPED INVERTER

FED INDUCTION MOTOR DRIVE

Hardware Prototype of 3-Level Diode Clamped inverter fed 3-Phase Induction Motor is developed and

analyzed for CMV of the system. This system consists of five main modules Power supply model, Control

Circuit Model, Gate Drive Circuit Model, Inverter Model, 3-Phase Squirrel Cage Induction Motor shown

in figure11.

1) Power supply model - Two regulated power supply of +12v and +5v requires for different card of our

circuit hence multi tapping step down Transformer whose rating 230/12Volt is used.

2) Control Circuit Model - In this system, In order to control IGBT, AT 89C52 Microcontroller was chosen

to generate a three level Pulse Width Modulation (PWM) Technique for greater efficiency.

Figure 11 Actual Hardware Model

3) Gate Drive Circuit Model – In this system Insulated Gate Bipolar Transistor (IGBT) is used as

switching device and TLP250 IC is a gate drive circuit. Microcontroller gives pulses to TLP250 IC. Output

of TLP250 IC is given to IGBT Switches.

4) Inverter Circuit Model - A variable voltage, variable frequency three phase supply for three phase

induction motor can be generated by a use of a Pulse Width Modulated (PWM) inverter. The implemented

system is proposed to drive 3-Phase Induction Motor with 12 Switches is connected in the form a Diode

Clamped Multilevel Inverter. The three phases are maintained at 120° relative to each other. Both the

frequency and amplitude of the fundamental component of output voltage waveform can be varied by

controlling the timing of the switching signals to the inverter devices.

5) Three-Phase Induction Motor – The experimental setup has been tested on Squirrel Cage Induction

Motor of 0.37kW, Star Connected, 400Volt, 1.2A, 50Hz, 4-Pole, 1440 RPM as load.

Hardware Results

Hardware Prototype of 3-Level Diode Clamped inverter fed 3-Phase Induction Motor is developed and

CMV of system has been examined. It has been found to be ±Vdc/3



Table III Comparision of Matlab and Hardware Result

Mat lab Result Hardware Result

From MATLAB Result Common Mode Voltage was

observed = 67 V From Hardware Result Common Mode Voltage was

observed = 70 V

CONCLUSION

In this Paper the simulation results of Conventional Two Level Inverter fed Induction Motor (IM), Three

Level Diode Clamped Inverter fed IM, Five Level Diode Clamped Inverter fed IM with POD SPWM

Technique are analyzed under MATLAB-SIMULINK. A Miniature Model of Three Level Diode Clamped

Inverter fed Induction Motor Drive is developed and analyzed. The Common Mode Voltage of each

system has been examined. Simulation Results versus Hardware Results are compared. As the level of

Inverter goes on increasing it has been observed that the CMV and Total Harmonic Distortion decreases.

REFERENCES

[1] C. Bharatiraja, S. Raghu, Prakash Rao , K.R.S. Paliniamy, Comparative Analysis of the Different PWM

Techniques to Reduce Common Mode Voltage in Three- Level Neutral- Point- Clamped Inverters for

Variable Speed Induction Drives, International Journal of Power Electronics and Drive System,

3(1),Marc 2013, pp. 105–116.

[2] M. M. Renge, and H. M. Suryawanshi, Five-level diode clamped inverter to eliminate common mode

voltage and reduce dv/dt in medium voltage rating induction motor drives, IEEE Trans Power Electron.,

23(4), pp. 1598–1607, Jul. 2008.

[3] Mohan M. Renge and Hiralal M. Suryawanshi, Multilevel Inverter to Reduce Common Mo- Voltage in

AC Motor Drives Using SPWM Technique, Journal of Power Electronics, 11(1), January 2011, 2006,

pp.21-27.

[4] Hirofui Akagi, and Shunsuke Tamura, A Passive EMI filter for eliminating both bearing current and

ground leakage current from an inverter-driven motor, IEEE Trans. Power Elctron., 21(5), pp. 982-989,

Sep. 2006.

[5] C. R. Balamurugan, S. P. Natarajan, R. Bensraj, Investigations on Three Phase Five Level Diode

Clamped Multilevel Inverter. International Journal of Modern Engineering Research, 2(3), May–June

2012 pp-1273–1279.

[6] Chenggang Mei, Juan Carlos Balda, and William P. Waite, Cancellation of common-mode voltages for

induction motor drives using active method, IEEE Trans. Energy Conversion, 21(2), pp. 380–386, Jun.

2006.

[7] K. Gupta and A. M. Khambadkone, A general space vector PWM algorithm for multilevel inverters,

including operation in over modulation range, IEEE Tra Power Elec tron., 22(2), pp. 517–526, Mar.

2007.

[8] Haoran Zhang, Annette Von Jouanne, and Shaoan Dai, A reduced switched dual bridge inverter

topology for the mitigation of bearing current, EMI, and dc voltage variation, IEEE Trans. Ind. Appl.,

37(5), Sep/Oct. 2001.

[9] Gopal Mondal, K. Gopakumar, P. N. Tekwani, and Emil Levi, A reduced- switch-count five-level

inverter with common-mode voltage elimination for an open-end winding induction motor drive, IEEE

Trans. on Indl. Electron. 54(4), pp. 2344–2351, Aug 2007.

[10] P. Chiang, D. G. Holmes, Y. Fukuta, and T. A. Lipo, A reduced common mode hysteresis current

regulation strategy for multilevel inverter, IEEE Trans Power Electron., 19(1), pp. 1992–2000, Jan.

2004.

[11] Hee-Jung Kim, Hyeoun-Dong Lee, Member, IEEE, and Seung-Ki Sul, Fellow, IEEE A New PWM

Strategy for Common-Mode Voltage Reduction in Neutral-Point-Clamped Inverter-Fed AC Motor

Drives, IEEE Transactions On Industry Applications, 37(6), Nov/Dec.2001

measurement and analysis of common mode voltage … · module 3: five level diode clamped...

Documents