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1. E4102- DC MOTOR CONTROL FADZILAH BINTI HASHIM E4102- DC MOTORCONTROLLED (KAWALAN MOTOR AT) TOPIK 5ELECTRIC BRAKING LECTURER :

FADZILAH BT HASHIM 012-5469607

2. E4102- DC MOTOR CONTROL FADZILAH BINTI HASHIM TOPIK 5ELECTRICBRAKING REGENERATIVE DYNAMIC PLUGGING ELECTRIC BRAKING

3. E4102- DC MOTOR CONTROL FADZILAH BINTI HASHIM 5.0 Introduction Slow or stop amotor and load pacuannya as important as the beginning of many applications such as

cranes and traction(tarikan) on a slope to prevent excessive speed. Method based on friction

braking, electromechanical response, eddy currents and so forth. It does not depend on the

motor, but sometimes electric braking (electrical braking) is better, especially in terms of

economy and the absence of wear on the brakes (brake wear). DC motors are widely used

as a means of holding or braking. TOPIK 5ELECTRIC BRAKING

4. E4102- DC MOTOR CONTROL FADZILAH BINTI HASHIM 5.0 Introduction DC motors arewidely used as a means of holding or braking. One reason for this is a good braking

characteristics and the ability to change (transition) the motor current from the generator

mode (mod penjana) and vice versa. During the period of braking, the motor berkendali sbg

generator and energy (potential energy) the kinetic (kinetik) or gravity (Gravitational)

degenerative (dissipated) to the resistance (plugging) or returned to the supply (regenerative

braking). Electromechanical braking is a process to stop the motor. Braking can be done to

stop the rotation of the motor armature. For larger motors there is inertia load (armature

rotates) on the motor. Therefore it can not be dismissed so quickly. TOPIK 5ELECTRIC

BRAKING

5. E4102- DC MOTOR CONTROL FADZILAH BINTI HASHIM There are three types ofbraking method; Dynamic braking. Plugging braking. Regeneration braking. TOPIK 5

ELECTRIC BRAKING

6. E4102- DC MOTOR CONTROL FADZILAH BINTI HASHIM 5.1 Dynamic braking Brakingis more popular. It is a way to stop the rotation of the motor armature where armature

disconnected from the supply source but connected to the external resistance. When the

external resistance is connected, the current,Ia will change direction, the torque will happen

with the fight against the direction of rotation. The opposite direction of this torque causes the

motor to stop. In this way also the armature current can be limited during the braking

process. This method can be briefly described as figure 5.1 TOPIK 5ELECTRIC BRAKING

7. E4102- DC MOTOR CONTROL FADZILAH BINTI HASHIM Figure 5.1 The block diagramof the dynamic braking method Referring to figure 5.1 before the braking output voltage


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dynamics are as follows; Eo = Va - IaRa After the dynamic braking??? 5.1 Dynamic braking

TOPIK 5ELECTRIC BRAKING

8. E4102- DC MOTOR CONTROL FADZILAH BINTI HASHIM Selepas pembrekan dinamik.Power during the initial braking is ; 5.1 Dynamic braking TOPIK 5ELECTRIC BRAKING

9. E4102- DC MOTOR CONTROL FADZILAH BINTI HASHIM Referring to figure 5.2 thearmature is separated from the supply and a braking resistor, Rb directly connected

merintanginya. In this way the motor acts as a generator, driven by the stored kinetic energy

to generate power to the Rb . 5.1 Dynamic braking TOPIK 5ELECTRIC BRAKING

10. E4102- DC MOTOR CONTROL FADZILAH BINTI HASHIM This is a simple method ofbringing the motor close to stop conditions. Braking time is dependent on the system inertia,

load torque and motor rating. When the braking circuit is connected to left field to supply the

input. One danger is that if supply fails, the braking will also fail. If the field is left connected

across the armature, resulting in braking torque is the same but start falling with the the high

rate of slope which propotional to speed, then the problem arises once the speed falls below

the critical imperative of self (self-excitation). For the series motor, it is necessary to reverse

the continued braking whether the field winding or armature winding to produce the emf in the

armature. Rb values must be (Rb + Ra + RSE) is less than the critical resistance to the

speed at which braking is made. 5.1 Dynamic braking TOPIK 5ELECTRIC BRAKING

11. E4102- DC MOTOR CONTROL FADZILAH BINTI HASHIM Example calculation ofdynamic braking: 1. A DC series motor with the supply 240V using a chopper with a duty

cycle 75% motor speed in the eddy current 15A and armature resistance 0.15 is 1000rpm.

If the motor stopped by dynamic braking of the external resistance 0.35 and moment of

inertia 95kgm2 . Calculate: - Initial braking power - Mechanical time constant -Time the motor

to reach 25% initial speed . TOPIK 5ELECTRIC BRAKING

12. E4102- DC MOTOR CONTROL FADZILAH BINTI HASHIM TOPIK 5ELECTRICBRAKING



15. E4102- DC MOTOR CONTROL FADZILAH BINTI HASHIM 5.2 Plugging braking In thismethod of supply to the armature will be disconnected from the supply source and

reconnected to the opposite polarity. Change of polarity will cause the torque generated in


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opposite directions, and against the direction of rotation. These changes cause the motor to

stop immediately. This method is shown in Figure 5.3. Faster than the dynamics of 2Tm.

TOPIK 5ELECTRIC BRAKING

16. E4102- DC MOTOR CONTROL FADZILAH BINTI HASHIM 5.2 Plugging braking TOPIK5ELECTRIC BRAKING

17. E4102- DC MOTOR CONTROL FADZILAH BINTI HASHIM Power when Initial braking, P= (Va + Eo)Ia. Time to stop the motor Tb = 2Tm. 5.2 Plugging braking TOPIK 5ELECTRIC

BRAKING

18. E4102- DC MOTOR CONTROL FADZILAH BINTI HASHIM 5.2 Plugging brakingReferring to figure 5.4 this braking method involves the exchange and at the same

connection on the field winding (field) or the armature coil (armature) while the motor is

berkendali. A powerful braking torque is obtained by setting the same voltage supply with

armature while the connections is inverted. TOPIK 5ELECTRIC BRAKING

19. E4102- DC MOTOR CONTROL FADZILAH BINTI HASHIM 5.2 Plugging brakingArmature voltage is used (Ea + V) is in 2V, thus the limiting braking resistor (also can

resistor starters) should be placed on the circuit. Kinetic energy caused by the movement of

the system is removed (dissipated) to the armature and braking resistance Whichever

method is electrical braking will become less effective as speed is reduced due to a reduction

in braking torque of the supply shall be disconnected at a speed close to 0 (except to change

the motor rotation direction) by means of a current relay or router speed and wear a

mechanical or hydraulic brakes for cause the motor is stationary. High starting currents and

mechanical stress could limit the application of the method of plugging, especially to a small

motor. TOPIK 5ELECTRIC BRAKING


21. E4102- DC MOTOR CONTROL FADZILAH BINTI HASHIM Tm = time for the motorspeed decreased by 50% of actual speed. J - moment of inertia at the motor shaft rotation

(kg/m2 ) W1 - the actual speed when you start braking (rpm) P1 = the actual power received

by the braking resistance of the armature TOPIK 5 ELECTRIC BRAKING

22. E4102- DC MOTOR CONTROL FADZILAH BINTI HASHIM Contoh pengiraanPembrekan plugging: 1 A series of DC motor with a 240V supply using the chopper 75% duty

cycle in the 15A eddy current motor and 0.15 armature resistance when speed is 1000rpm.

If the motor stopped by braking plugging using a series resistance of 2.23. Calculate; -


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Current and power during the initial braking. - Time to stop the motor. TOPIK 5ELECTRIC

BRAKING



25. E4102- DC MOTOR CONTROL FADZILAH BINTI HASHIM 5.3 RegenerativeBraking(Pembrekan penjanaan semula) In this process of braking the motor will function as a

generator. Motor is fed energy from the supply. Chopper is used to rise and reduce the

voltage. Referring to figure 5.5 : TOPIK 5 ELECTRIC BRAKING

26. E4102- DC MOTOR CONTROL FADZILAH BINTI HASHIM 5.3 RegenerativeBraking(Pembrekan penjanaan semula) When the chopper Ch1 work, the machine will

function as a motor and the chopper Ch2 off, the energy stored in the motor will be

discharged through the diode D1, thereby reducing current flow. When the chopper CH2

work, the motor voltage to be generated. Opposite currents will flow through the chopper and

the energy stored in the motor. When the chopper CH2 off, energy will be released in the

form of current through the diode D2 to supply. TOPIK 5ELECTRIC BRAKING

27. E4102- DC MOTOR CONTROL FADZILAH BINTI HASHIM 5.3 RegenerativeBraking(Pembrekan penjanaan semula) Referring to figure 5.4 chopper voltage; Vch = (I

D)Vs (where D is the duty cycle ) Power generated Pg = IaVs(I - D) = IaVch The voltage

generated when the motor acts as generator Eo = Kv.IaW Eo = Vch + IaRm = (ID)Vs +

IaRm TOPIK 5ELECTRIC BRAKING


29. E4102- DC MOTOR CONTROL FADZILAH BINTI HASHIM THANK YOUTHANKYOU TOPIK 5 ELECTRIC BRAKING

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