1. Power Factor Correction Input Circuit
Kevin Wong, Paul Glaze,
Ethan Hotchkiss, Jethro Baliao
Advisor: Prof. Ali Bazzi
10/27/2016
JETHRO
Introduce Ourselves
Copyright © 2016 – Advanced Power Electronics & Electric Drives Lab (APEDL)

2. Outline JETHRO Go over what the course of the presentation will be
Background
Power Factor (PF)
Power Factor Correction (PFC)
Problem Statement
Importance for Lenze
Specifications
Constraints
Approach
Active vs passive rectification
DC/DC Design Topologies
Boost
Buck-Boost
Sepic
Flyback
Design simulations
Timeline moving forward
JETHRO
Go over what the course of the presentation will be
Copyright © 2016 – Advanced Power Electronics & Electric Drives Lab (APEDL)

3. Power Factor(PF)=cos=(P/S)
What is Power Factor?
The ratio of real power to apparent power in the circuit
Power Factor(PF)=cos=(P/S)
Another way of looking at this relationship is from the power triangle.
The apparent power, S can be determined by taking the vector sum of the reactive power, Q and the real power.
S = √(P2 * Q2)
JETHRO
Working Power(Actual Power, Active Power, or Real Power) is what powers equipment
Reactive Power is Power that transformers and motors to produce magnetic flux
Apparent power is the vectorial summation of Reactive Power and Working Power
Beer Analogy
is 16.7A at Unity Power Factor but at a 0.7 Power Factor
This would not trip a breaker at Unity Power Factor but at a 0.7 Power Factor it would.
Copyright © 2016 – Advanced Power Electronics & Electric Drives Lab (APEDL)

4. What is Power Factor Correction?
Reducing the reactive power consumed by an inductive load improves power factor
Power factor correction methods:
Capacitor Banks
Pros: Simple, inexpensive, quiet
Cons: Large size, limited adjustment
Synchronous Condenser
Pros: Extensive adjustment
Cons: Large size, noise, expensive
Power Electronics Switching Converter
Pros: Extensive adjustment, small size, quiet
Cons: Expensive
JETHRO
Simply Put, Reducing the Foam improves the amount of Beer you get
Examples of improving PF is the following
Capacitor Banks store electrical energy and corrects power supply error in electric motors and transformers
Synchronous Condenser would absorb reactive power
Power Electronics are small, generate no noise

5. Why is this important for Lenze?
Looking for a circuit to improve the Power Factor in one of their drives due to more consumer market requests.
PFC creates less distortion on the line for the customer
Design and manufacture affordable Variable Frequency Drives(VFDs).
VFDs control the frequencies and voltages to motors.
This is important because:
Reduction in Energy Consumption and Costs
Increase Longevity and Reduce Maintenance on Equipment
Efficiency saves on power component and thermal management, and therefore Size and Cost
JETHRO
Lenze manufactures VFDs in Uxbridge MA
Appliances include Heating, Ventilation and Air Conditioning (HVAC), Drills, and Pumps.
Importance of VFD’s
Reduction in Energy Consumption
If an application does not have to function at full load, a VFD can cut down on the extra costs by controlling the motor. The VFD will match the load and the input to maximize efficiency.
Electric Motor systems account for more than 60% of the power consumption in industry.
Having one can potentially reduce energy consumption by 70% depending on the application
Longevity and Maintenance
The VFD will have the motor operate at its optimal speed preventing any overloads, under voltage, over voltage, etc.

6. Block Diagram KEVIN NEXT JETHRO
Simple Block Diagram showing how we plan on approaching this project
First the AC input runs through a Diode Bridge Rectifier
That DC output will run into our choice of topology:
Buck
That output will feedback into the Switch/MOSFET using either:
PID Controller
Analog Controller
Microcontroller
KEVIN NEXT

7. Specifications Input Requirements Output Requirements
Voltage Input: 90Vac-132Vac
Power Factor: >0.95
Frequency: 48-62Hz
Inrush Current: <40A
Output Requirements
Voltage Output: 325Vdc
Max Continuous Power: 1472
Voltage Ripple: 20Vpk-pk
System Requirements
Operating Temperature: -10 to 55 °C
Switching Frequency: >20KHz
Kevin

8. Constraints Lenze is looking for PAUL NEXT Low Cost Small Footprint
High Efficiency
PCB Design
Possible Three-Phase Circuit
230Vac to 325Vdc
KEVIN
Something Cheap, they plan on mass producing this product
Small Footprint is a plus, this will be going to be working with one of their VFDs
High Efficiency is Key to saving money and energy
PCB design would be great for Lenze, although a hardwired project would also be helpful too before working with the final design
Three-Phase is one of the extra goals for this project
Three-Phase is advantageous over Single-Phase because
Due to the Instantaneous Power (power consumed and power generated at anytime during a cycle)
Consistent Power Delivery and more efficient
PAUL NEXT

9. Active vs Passive Rectification
Pros:
Lower voltage drop
Bi-directional current
Higher efficiency
Cons:
Requires control
More expensive
More complex
Passive:
Pros:
No external control
Simple
Inexpensive
Cons:
Uni-directional current
Higher voltage drop
Lower efficiency
PAUL

10. Possible DC/DC Topologies
Boost
Flyback
SEPIC
Buck Boost
PAUL
ETHAN NEXT
Copyright © 2016 – Advanced Power Electronics & Electric Drives Lab (APEDL)

11. Boost Converter Diagram
ETHAN

12. Ideal Boost Waveforms Output Voltage ETHAN
Power
~ W
Input
Current
~0-50A
Power
Factor
>0.9999
ETHAN
All visible ripples are at fundamental frequency(60Hz)
Not at the PWM switching frequency (>20kHz)
Very high power factor due to ideal components and control circuit
Output
Voltage
Copyright © 2016 – Advanced Power Electronics & Electric Drives Lab (APEDL)

13. Boost Pros Pros: Small Footprint Simple Design PF well over 0.99
Inexpensive
No transformer required
Operates at large range of power
ETHAN
Requires only 4 components at most basic level
With control circuit, capable of very high PF
Due to simplicity, boost converter is relatively inexpensive
Does not require a transformer(saves on weight and space)
Large range of Power applications

14. Boost Cons Cons: Difficult to stabilize High voltage ripple
High current inrush
Requires a large inductor
ETHAN
Difficult to stabilize due to RHP zero
High Vo ripple and IL ripple in the case of PFC because of input dropping to 0V
Requires a large inductor to control inrush current
JETHRO NEXT

15. Flyback Converter Diagram
JETHRO
The Flyback Converter is a derivative of the buck-boost converter
The centerpiece is known as a “Flyback Transformer”
Current does not flow simultaneously in both windings
So when the switch closes current will flow through the primary winding (Left side).
This will induce a voltage over the secondary winding.
On the right side of the circuit the diode is reversed biased so there will be no secondary current.
There is a snubber circuit to suppress voltage spikes caused by the switch

16. Ideal Flyback Waveforms
Input Current:
0A~59A
Output Power:
900W~1180W
Output Voltage:
290V~340V
JETHRO
These are the Ideal Flyback Waveforms Using Simulink to simulate
Used a 1ohm resistor to limit the inrush current that was around 500A without it.
If the lower ohm resistor is used the output voltage would be significantly greater than the required specifications.
A greater ohm resistor will result in a lower output voltage compared to the required specifications
The inrush current is also 3 times greater than the specified amount which is >40A
Output Power is less than the requested which is 1472W continuous instead of 1180W
The Voltage Ripple for the Output Voltage is around 40Vpk-pk which is twice the amount needed
The Power Factor was hovering around 0.998
Power Factor:
0.998

17. Flyback Pros Pros No need for an additional inductor
Offers Single or Multiple Isolated Output Voltages
Great for High Voltages (at Low Power)
Simple Design
Low Cost
Similar Advantages from a Buck-Boost Converter
JETHRO
No additional inductor is needed because of the Flyback Transformer
Due to the Flyback Transformer the Flyback Topology can have the output voltages adjusted by varying the turns ratio in the Transformer
Great for low-power applications (But we are working something over 1000 watts)
Similar advantages to the Buck-Boost which will be explained later
Copyright © 2016 – Advanced Power Electronics & Electric Drives Lab (APEDL)

18. Flyback Cons
Cons
Due to the use of a Transformer the Converter is not suitable for high power applications
Feedback Loop requires a lower bandwidth due to a Right hand plane (RHP) zero in response of the converter
High-Value Output Capacitor
In CCM, the control loop needs slope compensation when the duty cycle is above 50%.
High Current Stress of the Switch and Output Diode can cause EMI problems
JETHRO
Not suitable for High power yet is good for high voltages outputs
Not only does the Boost have RHP (imaginary pole) problems but so does the Flyback making this Topology Difficult to stabilize
Requires a Separate snubber design(which was shown in the Diagram before
High-Value Output Capacitor will increase the size of the topology
Boost and Flyback don't require high side drivers
Flyback also capable of true shutdown
Components and layout are also important to efficiency
KEVIN NEXT
Copyright © 2016 – Advanced Power Electronics & Electric Drives Lab (APEDL)
10/20/16

19. SEPIC Converter Diagram
KEVIN
Mosfet switched to 1, closed; Input voltage increases current in inductor 1 and loops back down. C1 discharges, increasing the current in Inductor 2. When Switch is 0 or open, then both inductors produce current through load and capacitors are charged.

20. Ideal SEPIC Waveforms Output Voltage: 322V-329V Input Current: 0-150A
KEVIN
Open Loop Results. The Output Voltage is within the requirements but the input current is much greater than what it should be. Output voltage is V and the Input Current after the inrush current is 0 to 150A.
Input Current:
0-150A

21. SEPIC Pros Pros Can increase or decrease input voltage values
Output same polarity
High Power Efficiency
Inductor is on input side, limiting slope of current
KEVIN
Copyright © 2016 – Advanced Power Electronics & Electric Drives Lab (APEDL)
10/20/16

22. SEPIC Cons
Cons
Transfers all its energy via series capacitor, capacitor requires high capacitance and current handling capability
Voltage Drop on Diode is critical to reliability and efficiency (switching time needs to be fast to not generate high voltage spikes across inductors)
Schottky diodes solution
Larger number of components as well as high complexity
KEVIN
PAUL NEXT
Copyright © 2016 – Advanced Power Electronics & Electric Drives Lab (APEDL)
10/20/16

23. Buck-Boost Converter Diagram
PAUL

24. Ideal Buck-Boost Waveforms Open Loop
Output
Voltage
~ V
Power
~ W
Input
Current
~0-50A
Power
Factor
~0.93
PAUL
Output
Voltage
Copyright © 2016 – Advanced Power Electronics & Electric Drives Lab (APEDL)

25. Buck-Boost Pros Pros: Large frequency range No transformer
No inrush current or precharge like the boost
More stable output voltage
PAUL

26. Buck-Boost Cons Cons: High transients
Voltage stress on the FET (switch)
Less efficient than flyback or boost
Calculations for control are more difficult
Boost and buck-boost only have one possible voltage
Difficult to stabilize
Power is inverted
No Common Ground
Adaptations:
EMI filter (may cost more in efficiency)
High quality FET
Additional supply for controls
PAUL
Inductor current = Iin+iout
Inverted output
no common ground

27. Buck-Boost
There is a high quality pdf of this uploaded in the simulation file.
This simulation is now working but I was able to get some data from before the simulation had an error.
The chip is LT8312 Boost power correction factor controller. It had to be almost tricked to work. That is why there are so many passive components.
The LT4320 was used to control the mosfets for rectification.
PAUL
ETHAN NEXT

28. DC/DC Converter Pros & Cons
ETHAN

29. Which methods fit our needs?
DC/DC Converter Topology
We presented the pros and cons of each topology along with preliminary simulations to Lenze on Monday and they have decided that they want us to move forward with the boost converter.
Active vs. Passive Rectification
Lenze has also stated that they would like us to start with passive rectification in order to simplify the design.
ETHAN

30. What is next? Small signal modeling of the boost converter
Optimize closed-loop control simulation
Size components
Convert ideal simulation in Simulink to non-ideal simulation in both Simulink and LT Spice?
Explore control options(programmable microcontroller vs. modifying a pre-made IC chip)
Begin physical prototyping
Begin PCB design
ETHAN
JETHRO NEXT

31. Fall Timeline
JETHRO
Sepic and Buck Boost are probably the bulkiest options
Flyback has limited power
Boost is probably the best option
Look at power levels Lenze looks for
Low cost and simple option
Mosfet Based bridge input instead of Diode could give more control
Copyright © 2016 – Advanced Power Electronics & Electric Drives Lab (APEDL)
10/20/16

32. Spring Timeline JETHRO How out next semester looks
Mostly Testing and Delivering Weekly reports (assuming we get the prototype functional by the end of this semester)
This is still subject to change however

33. Resources
J. Betten. (2011, Q2) “Benefits of a coupled-inductor SEPIC converter” Analog Applications Journal [Online] Available: [October ].
G. Sharp. “Sepic Converter Design and Operation.” BS, WPI, Worcester, MA, 2014.
ST. “TM sepic converter in PFC pre-regulator.” Internet: 34/73/b9/27/48/65/CD pdf/files/CD pdf/jcr:content/translations/en.C D pdf, March 2007[October 10, 2016].
J.W. Kolar and T. Friedli. “The Essence of Three-Phase PFC Rectifier Systems-Part I.” IEEE Transactions on Power Electronics, Vol. 28, No.1,pp , [ September 20, 2016].
H. Wei, and I. Batarseh. (1998) “Comparison of Basic Converter Topologies For Power Factor Correction.” [September 20, 2016]
"The Flyback Converter," in University of Colorado. [Online]. Available: [Oct. 27, 2016].
De Nardo et al, “Power Stage Design of Fourth-Order DC-DC Converters by Means of Principal Components Analysis.”IEEE Transactions on power Electronics, Vol. 23 No. 6,pp
Consistent w/ citations
Include Problem Statement
What is PFC?
Why is this important for Lenze?
Include Block Diagram
Constraints
Design Options
Literature
Build a pros/cons table
Gantt Chart
Copyright © 2016 – Advanced Power Electronics & Electric Drives Lab (APEDL)

34. Semiconductor Options
IGBT
Voltage Rating: >1kv
Current Rating: >500A
Slower switching
More expensive
MOSFET
Voltage Rating: <1kV
Current Rating: <200A
Faster switching
Less expensive

35. Frequency Domain Analysis: Buck-Boost
Current vs Voltage 100k Ohm Load
PAUL
FFT of current with no load at 100kHz

36. Frequency Domain Analysis: Buck-Boost
Current vs Voltage 100 ohm
100 ohm load FFT of current
PAUL

37. Frequency Domain Analysis: Buck-Boost
In the 100 ohm FFT there was an 80 db harmonic and a 60db. Not terrible but an emi filter would help the true power correction a lot.
With the loaded voltage vs current source we see the big advantage of Buck Boost, a steady rise in current. The inrush current was inherently limited by the boost controller’s soft start and orientation of the FET.
The power factor here is about 1. The distortion power factor is very bad. A proper filter will round off the square wave
PAUL
Because of the error I did not get a good efficiency calculation. If you look at the scale of the input current it is in KAmp. The efficiency should be very high but it must be less than the boost as it has fewer and smaller components.

38. Questions?