Transcript 3_DCDC_converters

Author: Ales Havel
E-mail: [email protected]
Phone number: 4287
Headquarters: E227
Web page: http://homen.vsb.cz/~hav278/
POWER SEMICONDUCTOR SYSTEMS I
Presentation contents

Main types of converters
 AC-DC
converters
 DC-DC converters
 1-quadrant




choppers
Buck converter
Boost converter
Buck-Boost converter
Resistance converters
 2-quadrant
choppers
 4-quadrant choppers
 DC-AC
converters
 AC-AC converters
Power converters

A power semiconductor converter is an electrical
device for converting electrical energy.
1-Quadrant choppers
Buck converter (step down chopper)
Load voltage for continuous
load current case:
Ud 
T1
U  z U
T
1
Load voltage for discontinuous U d  U  T1  U i (T  tk )
T
load current case:
Discontinuous load current
Continuous load current
Load current
transistor time:
id 
U  Ui
R
Load current
diode time:
  URi 
id  iv 0  e 


1-Quadrant choppers
Example 1:
The Buck converter is working with the R + L + Ui type of the load. The duty cycle of
the converter (z) is 15% and the switching frequency (f) is 200Hz. Evaluate the UAV
load voltage for these cases:
(U = 100V, Ui = 20V)
1) Continuous load current
2) Bypass diode conducting time is T/3.
Solution:
1)
Ud 
T1
U  z U  0.15 100  15V
T
2)
Ud 
T  tk
T
1
1 
1

 100  0.15  20  1  (0.15  )   15  10  25.33V
U  T1  Ui (T  tk )  U 1  Ui
T
T
T
3 
3

1-Quadrant choppers
Boost converter (step up chopper)
Load voltage for continuous
load current case:
Ud 
T2
T  T1
U
U  (1  z )U
T
T
1
Load voltage for discontinuous
U d  U  tk  T1   U i (T  tk ) 
T
load current case:
Continuous load current
Discontinuous load current
Max. load current
transistor time:
id _ max 
Ui
R
Min. load current
diode time:
id _ min 
U  U i
R
1-Quadrant choppers
Example 1:
The Boost converter is working with the R + L + Ui type of the load. The transistor
conducting time T1 = 1ms, the bypass diode conducting time is 1ms. The switching
frequency (f) is 400Hz. Evaluate the UAV load voltage, if U = 100V and Ui = 30V.
Solution:
Ud 
1

 1

 2 103   
U  tk  T1   U i (T  tk )   400 100  2 103  1103   30 
T
 400


 400  0.1  0.015  46V
1-Quadrant choppers
Resistance converter without capacitor
Regulation range of equivalent resistance:
0  Req  Rp
Resistance converter with capacitor
Regulation range of equivalent resistance:
0  Rp  
2-Quadrant choppers
2-Quadrant DC/DC converter with current reversion:
2-Quadrant choppers
2-Quadrant DC/DC converter with voltage reversion:
4-Quadrant chopper
2 ways of control:
- Bipolar
4-Quadrant chopper
2 ways of control:
- Unipolar
Thank You for your attention