Control of DC Motors by Choppers · PRINCIPLE OF CHOPPER OPERATION • A chopper is a high speed...
Transcript of Control of DC Motors by Choppers · PRINCIPLE OF CHOPPER OPERATION • A chopper is a high speed...
![Page 1: Control of DC Motors by Choppers · PRINCIPLE OF CHOPPER OPERATION • A chopper is a high speed “on" or “off” semiconductor switch • It connects source to load and disconnect](https://reader033.fdocuments.us/reader033/viewer/2022041916/5e69aad8aa81f644270bccdc/html5/thumbnails/1.jpg)
Control of DC Motors by Choppers
Dr. D G Padhan PSD 1
![Page 2: Control of DC Motors by Choppers · PRINCIPLE OF CHOPPER OPERATION • A chopper is a high speed “on" or “off” semiconductor switch • It connects source to load and disconnect](https://reader033.fdocuments.us/reader033/viewer/2022041916/5e69aad8aa81f644270bccdc/html5/thumbnails/2.jpg)
DC Chopper
• a static power electronic device that converts fixed dc
input voltage to a variable dc output voltage
• considered as dc equivalent of an ac transformer since
they behave in an identical manner
• used all over the world for rapid transit systems
• used in trolley cars, marine hoist, forklift trucks and mine
haulers
• offer smooth control, high efficiency, faster response and
regeneration facility
• The power semiconductor devices used for a chopper
circuit can be force commutated thyristor, power BJT,
MOSFET and IGBT 2 Dr. D G Padhan PSD
![Page 3: Control of DC Motors by Choppers · PRINCIPLE OF CHOPPER OPERATION • A chopper is a high speed “on" or “off” semiconductor switch • It connects source to load and disconnect](https://reader033.fdocuments.us/reader033/viewer/2022041916/5e69aad8aa81f644270bccdc/html5/thumbnails/3.jpg)
• GTO based chopper are also used
• These devices are generally represented by a switch.
• When the switch is off, no current can flow.
• Current flows through the load when switch is “on”.
• The power semiconductor devices have on-state voltage
drop of 0.5V to 2.5V across them.
• For the sake of simplicity, this voltage drop across these
devices is generally neglected
3 Dr. D G Padhan PSD
![Page 4: Control of DC Motors by Choppers · PRINCIPLE OF CHOPPER OPERATION • A chopper is a high speed “on" or “off” semiconductor switch • It connects source to load and disconnect](https://reader033.fdocuments.us/reader033/viewer/2022041916/5e69aad8aa81f644270bccdc/html5/thumbnails/4.jpg)
PRINCIPLE OF CHOPPER OPERATION
• A chopper is a high speed “on" or “off” semiconductor
switch
• It connects source to load and disconnect the load from
source at a fast speed.
• In this manner, a chopped load voltage is obtained from
a dc supply of constant magnitude
4 Dr. D G Padhan PSD
![Page 5: Control of DC Motors by Choppers · PRINCIPLE OF CHOPPER OPERATION • A chopper is a high speed “on" or “off” semiconductor switch • It connects source to load and disconnect](https://reader033.fdocuments.us/reader033/viewer/2022041916/5e69aad8aa81f644270bccdc/html5/thumbnails/5.jpg)
5 Dr. D G Padhan PSD
![Page 6: Control of DC Motors by Choppers · PRINCIPLE OF CHOPPER OPERATION • A chopper is a high speed “on" or “off” semiconductor switch • It connects source to load and disconnect](https://reader033.fdocuments.us/reader033/viewer/2022041916/5e69aad8aa81f644270bccdc/html5/thumbnails/6.jpg)
• During the period Ton, chopper is on and load voltage is
equal to source voltage Vs.
• During the period Toff, chopper is off, load voltage is
zero. In this manner, a chopped dc voltage is produced
at the load terminals
6 Dr. D G Padhan PSD
![Page 7: Control of DC Motors by Choppers · PRINCIPLE OF CHOPPER OPERATION • A chopper is a high speed “on" or “off” semiconductor switch • It connects source to load and disconnect](https://reader033.fdocuments.us/reader033/viewer/2022041916/5e69aad8aa81f644270bccdc/html5/thumbnails/7.jpg)
7 Dr. D G Padhan PSD
![Page 8: Control of DC Motors by Choppers · PRINCIPLE OF CHOPPER OPERATION • A chopper is a high speed “on" or “off” semiconductor switch • It connects source to load and disconnect](https://reader033.fdocuments.us/reader033/viewer/2022041916/5e69aad8aa81f644270bccdc/html5/thumbnails/8.jpg)
CONTROL STRATEGIES
• The average value of output voltage Vo can be
controlled through duty cycle by opening and closing the
semiconductor switch periodically. The various control
strategies for varying duty cycle are as following:
1. Time ratio Control (TRC)
2. Current-Limit Control.
8 Dr. D G Padhan PSD
![Page 9: Control of DC Motors by Choppers · PRINCIPLE OF CHOPPER OPERATION • A chopper is a high speed “on" or “off” semiconductor switch • It connects source to load and disconnect](https://reader033.fdocuments.us/reader033/viewer/2022041916/5e69aad8aa81f644270bccdc/html5/thumbnails/9.jpg)
Time ratio Control (TRC)
• Time ratio Ton/T(duty ratio) is varied.
• 1. CONSTANT FREQUENCY SYSTEM
on-time is varied but chopping frequency f is kept constant.
Variation of Ton means adjustment of pulse width, as such
this scheme is also called pulse-width-modulation scheme.
• 2. VARIABLE FREQUENCY SYSTEM
the chopping frequency f is varied and either (i) on-time
Ton is kept constant or (ii) off-time Toff is kept constant.
This method of controlling duty ratio is also called
Frequency-modulation scheme.
9 Dr. D G Padhan PSD
![Page 10: Control of DC Motors by Choppers · PRINCIPLE OF CHOPPER OPERATION • A chopper is a high speed “on" or “off” semiconductor switch • It connects source to load and disconnect](https://reader033.fdocuments.us/reader033/viewer/2022041916/5e69aad8aa81f644270bccdc/html5/thumbnails/10.jpg)
CURRENT- LIMIT CONTROL
• the on and off of chopper circuit is decided by the
previous set value of load current. The two set values
are maximum load current and minimum load current.
• When the load current reaches the upper limit, chopper
is switched off. When the load current falls below lower
limit, the chopper is switched on. Switching frequency of
chopper can be controlled by setting maximum and
minimum level of current.
10 Dr. D G Padhan PSD
![Page 11: Control of DC Motors by Choppers · PRINCIPLE OF CHOPPER OPERATION • A chopper is a high speed “on" or “off” semiconductor switch • It connects source to load and disconnect](https://reader033.fdocuments.us/reader033/viewer/2022041916/5e69aad8aa81f644270bccdc/html5/thumbnails/11.jpg)
11 Dr. D G Padhan PSD
![Page 12: Control of DC Motors by Choppers · PRINCIPLE OF CHOPPER OPERATION • A chopper is a high speed “on" or “off” semiconductor switch • It connects source to load and disconnect](https://reader033.fdocuments.us/reader033/viewer/2022041916/5e69aad8aa81f644270bccdc/html5/thumbnails/12.jpg)
Types of choppers
Dr. D G Padhan PSD 12
![Page 13: Control of DC Motors by Choppers · PRINCIPLE OF CHOPPER OPERATION • A chopper is a high speed “on" or “off” semiconductor switch • It connects source to load and disconnect](https://reader033.fdocuments.us/reader033/viewer/2022041916/5e69aad8aa81f644270bccdc/html5/thumbnails/13.jpg)
Step down chopper
13 Dr. D G Padhan PSD
When S is ON, e0 is equal to Edc. When S is OFF, eo is equal to
zero.
![Page 14: Control of DC Motors by Choppers · PRINCIPLE OF CHOPPER OPERATION • A chopper is a high speed “on" or “off” semiconductor switch • It connects source to load and disconnect](https://reader033.fdocuments.us/reader033/viewer/2022041916/5e69aad8aa81f644270bccdc/html5/thumbnails/14.jpg)
Step up chopper
14 Dr. D G Padhan PSD
![Page 15: Control of DC Motors by Choppers · PRINCIPLE OF CHOPPER OPERATION • A chopper is a high speed “on" or “off” semiconductor switch • It connects source to load and disconnect](https://reader033.fdocuments.us/reader033/viewer/2022041916/5e69aad8aa81f644270bccdc/html5/thumbnails/15.jpg)
15 Dr. D G Padhan PSD
![Page 16: Control of DC Motors by Choppers · PRINCIPLE OF CHOPPER OPERATION • A chopper is a high speed “on" or “off” semiconductor switch • It connects source to load and disconnect](https://reader033.fdocuments.us/reader033/viewer/2022041916/5e69aad8aa81f644270bccdc/html5/thumbnails/16.jpg)
16 Dr. D G Padhan PSD
![Page 17: Control of DC Motors by Choppers · PRINCIPLE OF CHOPPER OPERATION • A chopper is a high speed “on" or “off” semiconductor switch • It connects source to load and disconnect](https://reader033.fdocuments.us/reader033/viewer/2022041916/5e69aad8aa81f644270bccdc/html5/thumbnails/17.jpg)
Dr. D G Padhan PSD 17
![Page 18: Control of DC Motors by Choppers · PRINCIPLE OF CHOPPER OPERATION • A chopper is a high speed “on" or “off” semiconductor switch • It connects source to load and disconnect](https://reader033.fdocuments.us/reader033/viewer/2022041916/5e69aad8aa81f644270bccdc/html5/thumbnails/18.jpg)
• The choppers are also classified based on
their regions of operation
• Single Quadrant chopper
1. Type A Chopper
2. Type B Chopper
• Two Quadrant Chopper 1. Type C Chopper
2. Type D Chopper
• Four Quadrant Chopper 1. Type E Chopper
Dr. D G Padhan PSD 18
![Page 19: Control of DC Motors by Choppers · PRINCIPLE OF CHOPPER OPERATION • A chopper is a high speed “on" or “off” semiconductor switch • It connects source to load and disconnect](https://reader033.fdocuments.us/reader033/viewer/2022041916/5e69aad8aa81f644270bccdc/html5/thumbnails/19.jpg)
First quadrant chopper or Type A chopper
19 Dr. D G Padhan PSD
![Page 20: Control of DC Motors by Choppers · PRINCIPLE OF CHOPPER OPERATION • A chopper is a high speed “on" or “off” semiconductor switch • It connects source to load and disconnect](https://reader033.fdocuments.us/reader033/viewer/2022041916/5e69aad8aa81f644270bccdc/html5/thumbnails/20.jpg)
• The equivalent circuit is shown below
20 Dr. D G Padhan PSD
![Page 21: Control of DC Motors by Choppers · PRINCIPLE OF CHOPPER OPERATION • A chopper is a high speed “on" or “off” semiconductor switch • It connects source to load and disconnect](https://reader033.fdocuments.us/reader033/viewer/2022041916/5e69aad8aa81f644270bccdc/html5/thumbnails/21.jpg)
21 Dr. D G Padhan PSD
![Page 22: Control of DC Motors by Choppers · PRINCIPLE OF CHOPPER OPERATION • A chopper is a high speed “on" or “off” semiconductor switch • It connects source to load and disconnect](https://reader033.fdocuments.us/reader033/viewer/2022041916/5e69aad8aa81f644270bccdc/html5/thumbnails/22.jpg)
22 Dr. D G Padhan PSD
![Page 23: Control of DC Motors by Choppers · PRINCIPLE OF CHOPPER OPERATION • A chopper is a high speed “on" or “off” semiconductor switch • It connects source to load and disconnect](https://reader033.fdocuments.us/reader033/viewer/2022041916/5e69aad8aa81f644270bccdc/html5/thumbnails/23.jpg)
23 Dr. D G Padhan PSD
![Page 24: Control of DC Motors by Choppers · PRINCIPLE OF CHOPPER OPERATION • A chopper is a high speed “on" or “off” semiconductor switch • It connects source to load and disconnect](https://reader033.fdocuments.us/reader033/viewer/2022041916/5e69aad8aa81f644270bccdc/html5/thumbnails/24.jpg)
![Page 25: Control of DC Motors by Choppers · PRINCIPLE OF CHOPPER OPERATION • A chopper is a high speed “on" or “off” semiconductor switch • It connects source to load and disconnect](https://reader033.fdocuments.us/reader033/viewer/2022041916/5e69aad8aa81f644270bccdc/html5/thumbnails/25.jpg)
![Page 26: Control of DC Motors by Choppers · PRINCIPLE OF CHOPPER OPERATION • A chopper is a high speed “on" or “off” semiconductor switch • It connects source to load and disconnect](https://reader033.fdocuments.us/reader033/viewer/2022041916/5e69aad8aa81f644270bccdc/html5/thumbnails/26.jpg)
![Page 27: Control of DC Motors by Choppers · PRINCIPLE OF CHOPPER OPERATION • A chopper is a high speed “on" or “off” semiconductor switch • It connects source to load and disconnect](https://reader033.fdocuments.us/reader033/viewer/2022041916/5e69aad8aa81f644270bccdc/html5/thumbnails/27.jpg)
Second quadrant or type-B chopper
27 Dr. D G Padhan PSD
![Page 28: Control of DC Motors by Choppers · PRINCIPLE OF CHOPPER OPERATION • A chopper is a high speed “on" or “off” semiconductor switch • It connects source to load and disconnect](https://reader033.fdocuments.us/reader033/viewer/2022041916/5e69aad8aa81f644270bccdc/html5/thumbnails/28.jpg)
• If the chopper (or switch S) is turned ON and turned OFF
at regular intervals the average voltage E0 is +ve and I0
is –ve.
• The stored energy in the rotor is converted into electrical
energy and fed back into the system.
• This is equivalent to regenerative braking
Dr. D G Padhan PSD 28
![Page 29: Control of DC Motors by Choppers · PRINCIPLE OF CHOPPER OPERATION • A chopper is a high speed “on" or “off” semiconductor switch • It connects source to load and disconnect](https://reader033.fdocuments.us/reader033/viewer/2022041916/5e69aad8aa81f644270bccdc/html5/thumbnails/29.jpg)
• During the period TON the switch S ON and hence e0 =0.
The equivalent circuit is shown in Fig.4.6(a)
Dr. D G Padhan PSD 29
![Page 30: Control of DC Motors by Choppers · PRINCIPLE OF CHOPPER OPERATION • A chopper is a high speed “on" or “off” semiconductor switch • It connects source to load and disconnect](https://reader033.fdocuments.us/reader033/viewer/2022041916/5e69aad8aa81f644270bccdc/html5/thumbnails/30.jpg)
Dr. D G Padhan PSD 30
![Page 31: Control of DC Motors by Choppers · PRINCIPLE OF CHOPPER OPERATION • A chopper is a high speed “on" or “off” semiconductor switch • It connects source to load and disconnect](https://reader033.fdocuments.us/reader033/viewer/2022041916/5e69aad8aa81f644270bccdc/html5/thumbnails/31.jpg)
Dr. D G Padhan PSD 31
![Page 32: Control of DC Motors by Choppers · PRINCIPLE OF CHOPPER OPERATION • A chopper is a high speed “on" or “off” semiconductor switch • It connects source to load and disconnect](https://reader033.fdocuments.us/reader033/viewer/2022041916/5e69aad8aa81f644270bccdc/html5/thumbnails/32.jpg)
Dr. D G Padhan PSD 32
![Page 33: Control of DC Motors by Choppers · PRINCIPLE OF CHOPPER OPERATION • A chopper is a high speed “on" or “off” semiconductor switch • It connects source to load and disconnect](https://reader033.fdocuments.us/reader033/viewer/2022041916/5e69aad8aa81f644270bccdc/html5/thumbnails/33.jpg)
Dr. D G Padhan PSD 33
![Page 34: Control of DC Motors by Choppers · PRINCIPLE OF CHOPPER OPERATION • A chopper is a high speed “on" or “off” semiconductor switch • It connects source to load and disconnect](https://reader033.fdocuments.us/reader033/viewer/2022041916/5e69aad8aa81f644270bccdc/html5/thumbnails/34.jpg)
Two-quadrant chopper or Type C chopper
T1 conducts va = Vdc
Q1 Q2
Va
Ia
T1
T2
D1
+
Va
-
D2
ia
+
Vdc
Dr. D G Padhan PSD 34
![Page 35: Control of DC Motors by Choppers · PRINCIPLE OF CHOPPER OPERATION • A chopper is a high speed “on" or “off” semiconductor switch • It connects source to load and disconnect](https://reader033.fdocuments.us/reader033/viewer/2022041916/5e69aad8aa81f644270bccdc/html5/thumbnails/35.jpg)
Two-quadrant converter
Q1 Q2
Va
Ia
T1
T2
D1
+
Va
-
D2
ia
+
Vdc
D2 conducts va = 0 T1 conducts va = Vdc
Quadrant 1 The average voltage is made larger than the back emf Dr. D G Padhan PSD 35
![Page 36: Control of DC Motors by Choppers · PRINCIPLE OF CHOPPER OPERATION • A chopper is a high speed “on" or “off” semiconductor switch • It connects source to load and disconnect](https://reader033.fdocuments.us/reader033/viewer/2022041916/5e69aad8aa81f644270bccdc/html5/thumbnails/36.jpg)
Two-quadrant converter
Q1 Q2
Va
Ia
T1
T2
D1
+
Va
-
D2
ia
+
Vdc
T2 conducts va = 0
Quadrant 2 The average voltage is made smaller than the back emf, thus
forcing the current to flow in the reverse direction
Dr. D G Padhan PSD 36
![Page 37: Control of DC Motors by Choppers · PRINCIPLE OF CHOPPER OPERATION • A chopper is a high speed “on" or “off” semiconductor switch • It connects source to load and disconnect](https://reader033.fdocuments.us/reader033/viewer/2022041916/5e69aad8aa81f644270bccdc/html5/thumbnails/37.jpg)
Two-quadrant converter
Q1 Q2
Va
Ia
T1
T2
D1
+
Va
-
D2
ia
+
Vdc
D1 conducts va = Vdc
Dr. D G Padhan PSD 37
![Page 38: Control of DC Motors by Choppers · PRINCIPLE OF CHOPPER OPERATION • A chopper is a high speed “on" or “off” semiconductor switch • It connects source to load and disconnect](https://reader033.fdocuments.us/reader033/viewer/2022041916/5e69aad8aa81f644270bccdc/html5/thumbnails/38.jpg)
Two quadrant or Type C Chopper
Dr. D G Padhan PSD 38
![Page 39: Control of DC Motors by Choppers · PRINCIPLE OF CHOPPER OPERATION • A chopper is a high speed “on" or “off” semiconductor switch • It connects source to load and disconnect](https://reader033.fdocuments.us/reader033/viewer/2022041916/5e69aad8aa81f644270bccdc/html5/thumbnails/39.jpg)
Dr. D G Padhan PSD 39
![Page 40: Control of DC Motors by Choppers · PRINCIPLE OF CHOPPER OPERATION • A chopper is a high speed “on" or “off” semiconductor switch • It connects source to load and disconnect](https://reader033.fdocuments.us/reader033/viewer/2022041916/5e69aad8aa81f644270bccdc/html5/thumbnails/40.jpg)
Dr. D G Padhan PSD 40
![Page 41: Control of DC Motors by Choppers · PRINCIPLE OF CHOPPER OPERATION • A chopper is a high speed “on" or “off” semiconductor switch • It connects source to load and disconnect](https://reader033.fdocuments.us/reader033/viewer/2022041916/5e69aad8aa81f644270bccdc/html5/thumbnails/41.jpg)
Dr. D G Padhan PSD 41
![Page 42: Control of DC Motors by Choppers · PRINCIPLE OF CHOPPER OPERATION • A chopper is a high speed “on" or “off” semiconductor switch • It connects source to load and disconnect](https://reader033.fdocuments.us/reader033/viewer/2022041916/5e69aad8aa81f644270bccdc/html5/thumbnails/42.jpg)
Dr. D G Padhan PSD 42
![Page 43: Control of DC Motors by Choppers · PRINCIPLE OF CHOPPER OPERATION • A chopper is a high speed “on" or “off” semiconductor switch • It connects source to load and disconnect](https://reader033.fdocuments.us/reader033/viewer/2022041916/5e69aad8aa81f644270bccdc/html5/thumbnails/43.jpg)
Dr. D G Padhan PSD 43
![Page 44: Control of DC Motors by Choppers · PRINCIPLE OF CHOPPER OPERATION • A chopper is a high speed “on" or “off” semiconductor switch • It connects source to load and disconnect](https://reader033.fdocuments.us/reader033/viewer/2022041916/5e69aad8aa81f644270bccdc/html5/thumbnails/44.jpg)
Dr. D G Padhan PSD 44
![Page 45: Control of DC Motors by Choppers · PRINCIPLE OF CHOPPER OPERATION • A chopper is a high speed “on" or “off” semiconductor switch • It connects source to load and disconnect](https://reader033.fdocuments.us/reader033/viewer/2022041916/5e69aad8aa81f644270bccdc/html5/thumbnails/45.jpg)
Dr. D G Padhan PSD 45
![Page 46: Control of DC Motors by Choppers · PRINCIPLE OF CHOPPER OPERATION • A chopper is a high speed “on" or “off” semiconductor switch • It connects source to load and disconnect](https://reader033.fdocuments.us/reader033/viewer/2022041916/5e69aad8aa81f644270bccdc/html5/thumbnails/46.jpg)
Two quadrant chopper- Type D Chopper
Dr. D G Padhan PSD 46
![Page 47: Control of DC Motors by Choppers · PRINCIPLE OF CHOPPER OPERATION • A chopper is a high speed “on" or “off” semiconductor switch • It connects source to load and disconnect](https://reader033.fdocuments.us/reader033/viewer/2022041916/5e69aad8aa81f644270bccdc/html5/thumbnails/47.jpg)
Dr. D G Padhan PSD 47
![Page 48: Control of DC Motors by Choppers · PRINCIPLE OF CHOPPER OPERATION • A chopper is a high speed “on" or “off” semiconductor switch • It connects source to load and disconnect](https://reader033.fdocuments.us/reader033/viewer/2022041916/5e69aad8aa81f644270bccdc/html5/thumbnails/48.jpg)
Dr. D G Padhan PSD 48
![Page 49: Control of DC Motors by Choppers · PRINCIPLE OF CHOPPER OPERATION • A chopper is a high speed “on" or “off” semiconductor switch • It connects source to load and disconnect](https://reader033.fdocuments.us/reader033/viewer/2022041916/5e69aad8aa81f644270bccdc/html5/thumbnails/49.jpg)
Dr. D G Padhan PSD 49
![Page 50: Control of DC Motors by Choppers · PRINCIPLE OF CHOPPER OPERATION • A chopper is a high speed “on" or “off” semiconductor switch • It connects source to load and disconnect](https://reader033.fdocuments.us/reader033/viewer/2022041916/5e69aad8aa81f644270bccdc/html5/thumbnails/50.jpg)
Dr. D G Padhan PSD 50
![Page 51: Control of DC Motors by Choppers · PRINCIPLE OF CHOPPER OPERATION • A chopper is a high speed “on" or “off” semiconductor switch • It connects source to load and disconnect](https://reader033.fdocuments.us/reader033/viewer/2022041916/5e69aad8aa81f644270bccdc/html5/thumbnails/51.jpg)
Dr. D G Padhan PSD 51
![Page 52: Control of DC Motors by Choppers · PRINCIPLE OF CHOPPER OPERATION • A chopper is a high speed “on" or “off” semiconductor switch • It connects source to load and disconnect](https://reader033.fdocuments.us/reader033/viewer/2022041916/5e69aad8aa81f644270bccdc/html5/thumbnails/52.jpg)
Dr. D G Padhan PSD 52
![Page 53: Control of DC Motors by Choppers · PRINCIPLE OF CHOPPER OPERATION • A chopper is a high speed “on" or “off” semiconductor switch • It connects source to load and disconnect](https://reader033.fdocuments.us/reader033/viewer/2022041916/5e69aad8aa81f644270bccdc/html5/thumbnails/53.jpg)
Dr. D G Padhan PSD 53
![Page 54: Control of DC Motors by Choppers · PRINCIPLE OF CHOPPER OPERATION • A chopper is a high speed “on" or “off” semiconductor switch • It connects source to load and disconnect](https://reader033.fdocuments.us/reader033/viewer/2022041916/5e69aad8aa81f644270bccdc/html5/thumbnails/54.jpg)
Dr. D G Padhan PSD 54
![Page 55: Control of DC Motors by Choppers · PRINCIPLE OF CHOPPER OPERATION • A chopper is a high speed “on" or “off” semiconductor switch • It connects source to load and disconnect](https://reader033.fdocuments.us/reader033/viewer/2022041916/5e69aad8aa81f644270bccdc/html5/thumbnails/55.jpg)
Dr. D G Padhan PSD 55
![Page 56: Control of DC Motors by Choppers · PRINCIPLE OF CHOPPER OPERATION • A chopper is a high speed “on" or “off” semiconductor switch • It connects source to load and disconnect](https://reader033.fdocuments.us/reader033/viewer/2022041916/5e69aad8aa81f644270bccdc/html5/thumbnails/56.jpg)
Dr. D G Padhan PSD 56
![Page 57: Control of DC Motors by Choppers · PRINCIPLE OF CHOPPER OPERATION • A chopper is a high speed “on" or “off” semiconductor switch • It connects source to load and disconnect](https://reader033.fdocuments.us/reader033/viewer/2022041916/5e69aad8aa81f644270bccdc/html5/thumbnails/57.jpg)
Dr. D G Padhan PSD 57
![Page 58: Control of DC Motors by Choppers · PRINCIPLE OF CHOPPER OPERATION • A chopper is a high speed “on" or “off” semiconductor switch • It connects source to load and disconnect](https://reader033.fdocuments.us/reader033/viewer/2022041916/5e69aad8aa81f644270bccdc/html5/thumbnails/58.jpg)
Dr. D G Padhan PSD 58
![Page 59: Control of DC Motors by Choppers · PRINCIPLE OF CHOPPER OPERATION • A chopper is a high speed “on" or “off” semiconductor switch • It connects source to load and disconnect](https://reader033.fdocuments.us/reader033/viewer/2022041916/5e69aad8aa81f644270bccdc/html5/thumbnails/59.jpg)
59
Chopper fed DC drive
Four-quadrant Chopper
+ Va Q1
Q2
Q3
Q4
D1 D3
D4 D2
+
Vdc
Q1 & Q4 is ON
Current Flow : Vdc + _ Q1 _Motor_Q4_Vdc
-
Current Ia & Va are positive
Operates in First Quadrant
Forward Motoring
Va
Ia
![Page 60: Control of DC Motors by Choppers · PRINCIPLE OF CHOPPER OPERATION • A chopper is a high speed “on" or “off” semiconductor switch • It connects source to load and disconnect](https://reader033.fdocuments.us/reader033/viewer/2022041916/5e69aad8aa81f644270bccdc/html5/thumbnails/60.jpg)
60
Chopper fed DC drive
Four-quadrant Chopper
+ Va Q1
Q2
Q3
Q4
D1 D3
D4 D2
+
Vdc
Q1 is OFF & Q4 is ON. Inductor current has to flow in the
same Direction.
Diode D2 is FB
Inductor Current freewheels through D2 & Q4
Output Voltage is Zero
![Page 61: Control of DC Motors by Choppers · PRINCIPLE OF CHOPPER OPERATION • A chopper is a high speed “on" or “off” semiconductor switch • It connects source to load and disconnect](https://reader033.fdocuments.us/reader033/viewer/2022041916/5e69aad8aa81f644270bccdc/html5/thumbnails/61.jpg)
61
Chopper fed DC drive
Four-quadrant Chopper
+ Va Q1
Q2
Q3
Q4
D1 D3
D4 D2
+
Vdc
Q4 is OFF. Q2 is ON. Load is not connected with the source.
Back Emf drives the current through Q2 & D4
![Page 62: Control of DC Motors by Choppers · PRINCIPLE OF CHOPPER OPERATION • A chopper is a high speed “on" or “off” semiconductor switch • It connects source to load and disconnect](https://reader033.fdocuments.us/reader033/viewer/2022041916/5e69aad8aa81f644270bccdc/html5/thumbnails/62.jpg)
62
Chopper fed DC drive
Four-quadrant Chopper
+ Va Q1
Q2
Q3
Q4
D1 D3
D4 D2
+
Vdc
Q2 is OFF. Diode D1 is FB
Current flows through D4 & D1
Current Ia is negative & Va is positive.
Operates in second quadrant.
Va
Ia
Forward Braking
![Page 63: Control of DC Motors by Choppers · PRINCIPLE OF CHOPPER OPERATION • A chopper is a high speed “on" or “off” semiconductor switch • It connects source to load and disconnect](https://reader033.fdocuments.us/reader033/viewer/2022041916/5e69aad8aa81f644270bccdc/html5/thumbnails/63.jpg)
63
Chopper fed DC drive
Four-quadrant Chopper
- Va + Q1
Q2
Q3
Q4
D1 D3
D4 D2
+
Vdc
Q3 & Q2 is ON
Current Flow : Vdc + _ Q3 _Motor_Q2_Vdc
-
Current Ia & Va are negative
Operates in third Quadrant
![Page 64: Control of DC Motors by Choppers · PRINCIPLE OF CHOPPER OPERATION • A chopper is a high speed “on" or “off” semiconductor switch • It connects source to load and disconnect](https://reader033.fdocuments.us/reader033/viewer/2022041916/5e69aad8aa81f644270bccdc/html5/thumbnails/64.jpg)
64
Chopper fed DC drive
Four-quadrant Chopper
- Va + Q1
Q2
Q3
Q4
D1 D3
D4 D2
+
Vdc
Q3 is OFF. Q2 is ON. Current has to be continuous.
Diode D4 is FB
Current flows through Q2,D4 & (Eb,La,Ra)
![Page 65: Control of DC Motors by Choppers · PRINCIPLE OF CHOPPER OPERATION • A chopper is a high speed “on" or “off” semiconductor switch • It connects source to load and disconnect](https://reader033.fdocuments.us/reader033/viewer/2022041916/5e69aad8aa81f644270bccdc/html5/thumbnails/65.jpg)
65
Chopper fed DC drive
Four-quadrant Chopper
- Va + Q1
Q2
Q3
Q4
D1 D3
D4 D2
+
Vdc
Q4 Is ON & Q2 is OFF.
Back emf Drives the current through Q4 – D2 - MOTOR
![Page 66: Control of DC Motors by Choppers · PRINCIPLE OF CHOPPER OPERATION • A chopper is a high speed “on" or “off” semiconductor switch • It connects source to load and disconnect](https://reader033.fdocuments.us/reader033/viewer/2022041916/5e69aad8aa81f644270bccdc/html5/thumbnails/66.jpg)
66
Chopper fed DC drive
Four-quadrant Chopper
- Va + Q1
Q2
Q3
Q4
D1 D3
D4 D2
+
Vdc
Q4 IS Turned Off,
D3 is FB
Current Flows through Va+ - D3 – D2 – Va-
Va is negative. But current Ia is positive
Operates in fourth quadrant
![Page 67: Control of DC Motors by Choppers · PRINCIPLE OF CHOPPER OPERATION • A chopper is a high speed “on" or “off” semiconductor switch • It connects source to load and disconnect](https://reader033.fdocuments.us/reader033/viewer/2022041916/5e69aad8aa81f644270bccdc/html5/thumbnails/67.jpg)
67
Four Quadrant Chopper or Type E Chopper
![Page 68: Control of DC Motors by Choppers · PRINCIPLE OF CHOPPER OPERATION • A chopper is a high speed “on" or “off” semiconductor switch • It connects source to load and disconnect](https://reader033.fdocuments.us/reader033/viewer/2022041916/5e69aad8aa81f644270bccdc/html5/thumbnails/68.jpg)
68
![Page 69: Control of DC Motors by Choppers · PRINCIPLE OF CHOPPER OPERATION • A chopper is a high speed “on" or “off” semiconductor switch • It connects source to load and disconnect](https://reader033.fdocuments.us/reader033/viewer/2022041916/5e69aad8aa81f644270bccdc/html5/thumbnails/69.jpg)
69
![Page 70: Control of DC Motors by Choppers · PRINCIPLE OF CHOPPER OPERATION • A chopper is a high speed “on" or “off” semiconductor switch • It connects source to load and disconnect](https://reader033.fdocuments.us/reader033/viewer/2022041916/5e69aad8aa81f644270bccdc/html5/thumbnails/70.jpg)
70
![Page 71: Control of DC Motors by Choppers · PRINCIPLE OF CHOPPER OPERATION • A chopper is a high speed “on" or “off” semiconductor switch • It connects source to load and disconnect](https://reader033.fdocuments.us/reader033/viewer/2022041916/5e69aad8aa81f644270bccdc/html5/thumbnails/71.jpg)
71
![Page 72: Control of DC Motors by Choppers · PRINCIPLE OF CHOPPER OPERATION • A chopper is a high speed “on" or “off” semiconductor switch • It connects source to load and disconnect](https://reader033.fdocuments.us/reader033/viewer/2022041916/5e69aad8aa81f644270bccdc/html5/thumbnails/72.jpg)
72
![Page 73: Control of DC Motors by Choppers · PRINCIPLE OF CHOPPER OPERATION • A chopper is a high speed “on" or “off” semiconductor switch • It connects source to load and disconnect](https://reader033.fdocuments.us/reader033/viewer/2022041916/5e69aad8aa81f644270bccdc/html5/thumbnails/73.jpg)
73
![Page 74: Control of DC Motors by Choppers · PRINCIPLE OF CHOPPER OPERATION • A chopper is a high speed “on" or “off” semiconductor switch • It connects source to load and disconnect](https://reader033.fdocuments.us/reader033/viewer/2022041916/5e69aad8aa81f644270bccdc/html5/thumbnails/74.jpg)
74
![Page 75: Control of DC Motors by Choppers · PRINCIPLE OF CHOPPER OPERATION • A chopper is a high speed “on" or “off” semiconductor switch • It connects source to load and disconnect](https://reader033.fdocuments.us/reader033/viewer/2022041916/5e69aad8aa81f644270bccdc/html5/thumbnails/75.jpg)
75
![Page 76: Control of DC Motors by Choppers · PRINCIPLE OF CHOPPER OPERATION • A chopper is a high speed “on" or “off” semiconductor switch • It connects source to load and disconnect](https://reader033.fdocuments.us/reader033/viewer/2022041916/5e69aad8aa81f644270bccdc/html5/thumbnails/76.jpg)
76
![Page 77: Control of DC Motors by Choppers · PRINCIPLE OF CHOPPER OPERATION • A chopper is a high speed “on" or “off” semiconductor switch • It connects source to load and disconnect](https://reader033.fdocuments.us/reader033/viewer/2022041916/5e69aad8aa81f644270bccdc/html5/thumbnails/77.jpg)
77