4 Staggered Converters Draw 24-Pulse Current

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DEMO TITLES

4 staggered converters draw 24-pulse current Case I: Converters feed RL loads

Case II: Converters feed H Bridges (DC motors drive)

Author: Tshibain Tshibungu Simsmart Technologies Inc.

Brossard, Quebec Canada

Software used: Simsmart Engineering Suite V6 (ES V6)

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1. OBJECTIVE AND DESCRIPTION

The following test cases are done in order to test and validate the power electronics components from the Engineering suite V6 Electrical library and analog components.

Case I: 4 staggered converters draw 24-pulse current feeding RL loads Four separate 6-pulse converters combine to draw a 24-pulse current from the power system. All converters feed identical RL loads.

Case II: 4 staggered converters draw 24-pulse current feeding H bridges that drive DC motors

Four separate 6-pulse converters combine to draw a 24-pulse current from the power system. All converters feed identical H bridges that drive 4-quadrant DC motors.

2. PROCESSES DATA

1. 4 staggered converters draw 24-pulse current (RL loads)

Source voltage (sine wave) and diode with snubber

Transformer Yy 0 degree

Phase shifting transformers (Zny 7.5 deg, Zny -22.5 deg, Zny -7.5 deg, Zny -37.5 deg)

Loads

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2. 4 staggered converters draw 24-pulse current (DC motors) Source voltage (sine wave) and diode with snubber

Transformer Yy 0 degree

Phase shifting transformers (Zny 7.5 deg, Zny -22.5 deg, Zny -7.5 deg, Zny -37.5 deg)

DC motors

Maximum current and smoothing inductor are respectively 20 A and 10 mH

The speed PI controller

( )

Hysteresis current control: 2 A

IGBT without snubber

The load torque is proportional to motor speed:

Reference speed: Initially 1000 rpm (104.72 rad/s), at 0.8 s set to -1000 rpm (-104.72 rad/s)

3. SIMULATION PARAMETERS

The simulation was run in time domain with sample time of

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4. PROCESSES REPRESENTATION IN ES V6

4 staggered converters draw 24-pulse current (RL loads)

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4 staggered converters draw 24-pulse current (DC motors)

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6. ENGINEERING SUITE V6 RESULTS

4 staggered converters draw 24-pulse current (RL loads)

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NETWORK CURRENT FOURIER ANALYSIS

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4 staggered converters draw 24-pulse current (DC motors)

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NETWORK CURRENT FOURIER ANALYSIS

Conclusion

The following conclusions can be made:

the network current in steady state contains less harmonics (2.5 %) as displayed above.

the inrush current (network) is due to the capacitor charging. One can avoid that by using a precharged capacitor or another circuit to precharge.

the motors current dont exceed the maximum allowed (20 A).

7. REFERENCE BOOKS

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1. Power electronics. Converters, applications and design, 2nd edition. Mohan / Underland / Robbins.

2. Power electronics. Converter Harmonics. Multipulse methods for clean power. Derek A. Paice

3. Electric Motor Drives. Modeling, Analysis, and Control. R. Krishnan.