Self-Excited Induction Generator as an Auxiliary Brake

Contents

• Introduction

• Braking systems in vehicles

• Self excited induction generator

• Regenerative braking

• Proposed auxiliary brake

• Experimental results

• Conclusion

• References

2

Introduction

• Brake –main system for driver safety

• Heavy vehicles need high braking torque and high reliability

• Risk of brake fade down the slope

• Retarder braking system proves effective

Types

• Engine compression retarder

• Engine exhaust retarder

• Engine hydraulic retarder

• Electric retarder

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Electric Retarder Brake

• Placed within drive train

• Augment frictional braking system

• Serve to slow and maintain steady speed for heavy vehicles

• Increasing service life of frictional brakes

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Electric Retarder Brake….

• Eddy current brake

• Conventional ERB require dc control power

• Some- self excited ERB employs permanent magnets

• Proposing a self excited ERB without permanent magnets

• SEIG+ Electric retarder =auxiliary brake!!

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Self excited ERB

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Shaft/Rotor

SEIG Retarder

Stator Stator

StatorStator

Current

Self Excited Induction Generator

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SEIG…

• Induction motor made to run above Ns

• Slip negative

• Delta connected capacitor bank for the supply of reactive power

• Takes reactive power -Delivering active power

• The stator flux induces currents in the rotor, but since the opposing rotor flux is now cutting the stator coils

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Required capacitance of SEIG

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a= per unit frequencyb=per unit speed

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3

1

Required capacitance of SEIG..

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IM SEIG

Induction

Motor

Induction

Generator

SEIG

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Prime mover run at N>Ns Reactive power taken from supply line

Prime mover run at N>Ns Reactive power supplied by capacitor bank

Advantages of SEIG as auxiliary brake

• Efficiency in braking system is not important

• Can be controlled by simple circuits

• Regenerative braking

• Robust

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Regenerative Braking

• Earlier K.E Heat energy

• Energy recovery mechanism: K.E Usable energy

• Electric motor Electric Generator

(running) (braking)

• Delhi metro reduced CO2 emissions

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Regenerative Braking..

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Limitations of Regenerative braking

Used in conjunction with Friction based braking

• Effect drop off at lower speed

• Need Backup

• Effective when sink is not fully charged

• Power on some wheels

• Poor emergency braking performance

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Proposed Electric Retarder

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SEIG

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• Capacitor exciting current IG Capacitor V Exc.current

• Voltage buildup continues till Xm gets saturated

• Without load : Is=Ic

• With load : Is=Ic + IL

• Load current control strategy to control braking torque

Control System - Load

• Rectifier , Control signal generator, Load impedance , Switch

• Rectifier

Half wave rectifier dc voltage value=peak value of induced emf

Self excited voltage very high

Low CRect rectified voltage will vary highly

High CRect Voltage build up time increases

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Control System…

• Load impedance

RL+jXL limits load current during switched on

When switched off , load current flows through F.D

High frequency switching with help of control signal gen.is used

• Control signal generator

Schmitt trigger control switching frequency

RC1 and RC2 create a raw control signal with low voltage

Large Cc2 fswitch

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Control System…

• Switch

Power MOSFET used to control load current

IGBT not used as it needs negative V to switch off

• Interface for Battery charging converter

Scope for both power regeneration and braking torque

System cost increases

Problem arises when battery is fully charged

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Experimental setup

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Results

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Results…

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Conclusion

• Introduced SEIG as a brake and simple control circuit is proposed

• Controller does not need ECU thus cheap

• Since point meter has constant value , controller is stable

• Operating principle and control strategy is verified in Exp. Model

• Modifications in main devices in control circuit ,controlling a scaled up retarder becomes possible

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References

• “ Self-Excited Induction Generator as an Auxiliary Brake for Heavy Vehicles and Its Analog Controller"by Jae-Nam Bae , in IEEE transactions on industrial electronics ,vol,62,no 5,May 2015

• IEEE journal on”Capacitance requirements of self excited induction generators”by T F Chan in IEEE Transactions on Energy Conversion, Vol. 8, No. 2, June 1993

• Electrical Machines II by U A Bakshi and M V Bakshi

• Wikipedia

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THANK YOU