Power Electronics Flashcards
What are DC/DC Converters useful for?
- Voltage Supply in Automotive Power Nets or Server Farms
What are inverters useful for?
For Supply of Multi Phase Machines
What are the two sides of Power Electronics?
Control Engineering and High Power Side
What is a half-bridge?
Two semi-conductor elements connected in Series
What components does an Electrical Drive train consist of?
- Grid
- Filters
- Converter
- Load
- Control Electronics
- Signal Electronics
What is the voltage and current in and ideal voltage source?
Voltage is fixed, current is arbtitrary
What is line regulation?
{dV_out}/{dVi_in}
What is the load regulation?
Change in output voltage for change in output current
What effect does a voltage divider have on line regulation?
Reduces line regulation
How can you decrease losses of a zener voltage regulator?
Add a transistor
When are losses of MOSFET in a unipolar power output stage the maxiumum?
1/2 of short circuit current
What are the top and bottom switch in a half bridge?
Top bridge series with load, bottom parallel
What are two configurations for a half bridge and what are the voltage levels in each?
Top open and bottom closed: V = 0
Top closed and bottom open: V = V_in
What happens if both transistors in a half bridge are open?
Short circuit
What is line regulation for ideal voltage source?
0
What is Load regulation for Ideal source?
0 ohms
What is Line regulation for unloaded voltage source with resistance?
1
What is load regulation for unloaded voltage source with resistance?
-R
How can you tell that a MOSFET is in short circuit condition?
V_DS = 0 (Drain source voltage)
How can be a MOSFET modelled as a swtich?
- Assume allowed voltage range
- Assume voltage drop can be neglected when conducting current
What is an advantage of using half bridge?
Low losses
What does 0 and 1 mean for switches?
0 is open 1 is closed
What is an F bridge?
Half bridge with inductor and load
What is PWM?
A method for providing input voltage to half bridge
What is duty cycle?
Ratio of time where switch is closed to time where switch is open
What are some modulation schemes?
- Time-Average model
- Pulse wave modulation
- Closed loop modulation
What is an advantage of Closed loop modulation?
Is stable without knowing system dynamics
What is a syncronous buck converter?
- Syncronous implies two active elements
- Initially lossless
- Low damping
What is a boost converter?
A system that provides higher voltage than input
What is an easy way to tell a system is syncronous?
Half-bridge with two switches present
