Dc-Dc Converter
EE3501E – Power Electronics
Lecture 2
Text
Power Electronics ‐ A First Course Author: Ned Mohan ‐ / 2012 John Wiley and Sons
1
Lecture 1 ‐ Review
• • • • • • What is Power Electronics? Applications of power electronics. Linear vs Switched power conversion. Switching‐power pole Inductors and capacitors‐basic properties. Pulse‐Width‐Modulation (PWM)
2
Linear vs Switch mode conversion
3
Switching Power‐Pole
+ Vin q
A
qA 1
vv A
+ vA -
A
Vin
0 0
t
• Bi‐Positional Switch • Voltage Port – where a capacitor is connected in parallel to Vin so that it cannot change instantaneously • Current Port – where an inductor is connected in series through which current cannot change instantaneously
4
Control by Pulse‐Width Modulation (PWM) qA + 1
idA d A Ts +
iA
0 Tup Ts vA 0 Vin
dA t Vin
-
vA
-
qA 1or 0
vA t • The power‐pole chops the input voltage into high‐frequency voltage pulses • Output is synthesized as the switching‐cycle‐average of these pulses • Within each switching cycle, the average value is controlled by the duty‐ratio
dA
Tup Ts 0 dA 1
5
v A d AVin ,
Switching Power‐Pole in a Buck DC‐DC Converter: An Example qA iin 0 d ATs Ts Vin 1 t
Vin
iL vA
vA 0 Vo iL 0 iin
vA t qA
t
(a) 0 (b) t
Vo v A d AVin
0 Vo Vin
6
Problems
P.1.23
In a Buck converter, the input voltage Vin 12V . The output voltage Vo is required to be 9V . The switching frequency f s 400kHz. Assume ideal switchign power pole, calculate the pulse width Tup of the switching signal and the duty - ratio d A of the power pole.
7
Problems
P.1.24
In a Buck converter in Problem P - 1.23, Assuming the current through the inductor to be ripple - free with average value of 15A, draw the waveforms of voltage v A and the input current iin .
8
Problems
P.1.25
Using the same specifications given in Problem 1.23, calculate the
Lecture 2
Text
Power Electronics ‐ A First Course Author: Ned Mohan ‐ / 2012 John Wiley and Sons
1
Lecture 1 ‐ Review
• • • • • • What is Power Electronics? Applications of power electronics. Linear vs Switched power conversion. Switching‐power pole Inductors and capacitors‐basic properties. Pulse‐Width‐Modulation (PWM)
2
Linear vs Switch mode conversion
3
Switching Power‐Pole
+ Vin q
A
qA 1
vv A
+ vA -
A
Vin
0 0
t
• Bi‐Positional Switch • Voltage Port – where a capacitor is connected in parallel to Vin so that it cannot change instantaneously • Current Port – where an inductor is connected in series through which current cannot change instantaneously
4
Control by Pulse‐Width Modulation (PWM) qA + 1
idA d A Ts +
iA
0 Tup Ts vA 0 Vin
dA t Vin
-
vA
-
qA 1or 0
vA t • The power‐pole chops the input voltage into high‐frequency voltage pulses • Output is synthesized as the switching‐cycle‐average of these pulses • Within each switching cycle, the average value is controlled by the duty‐ratio
dA
Tup Ts 0 dA 1
5
v A d AVin ,
Switching Power‐Pole in a Buck DC‐DC Converter: An Example qA iin 0 d ATs Ts Vin 1 t
Vin
iL vA
vA 0 Vo iL 0 iin
vA t qA
t
(a) 0 (b) t
Vo v A d AVin
0 Vo Vin
6
Problems
P.1.23
In a Buck converter, the input voltage Vin 12V . The output voltage Vo is required to be 9V . The switching frequency f s 400kHz. Assume ideal switchign power pole, calculate the pulse width Tup of the switching signal and the duty - ratio d A of the power pole.
7
Problems
P.1.24
In a Buck converter in Problem P - 1.23, Assuming the current through the inductor to be ripple - free with average value of 15A, draw the waveforms of voltage v A and the input current iin .
8
Problems
P.1.25
Using the same specifications given in Problem 1.23, calculate the