# ecesd.engr.uconn.edu

Power Factor Correction Input Circuit Kevin Wong, Paul Glaze, Ethan Hotchkiss, Jethro Baliao Advisor: Prof. Ali Bazzi 10/27/2016 Copyright 2016 Advanced Power Electronics & Electric Drives Lab (APEDL) 1 Outline 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 Copyright 2016 Advanced Power Electronics & Electric Drives Lab (APEDL) 2 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) Copyright 2016 Advanced Power Electronics & Electric Drives Lab (APEDL) 3 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 4 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 5 Block Diagram 6

Specifications Input 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 7 Constraints Lenze is looking for

Low Cost Small Footprint High Efficiency PCB Design Possible Three-Phase Circuit 230Vac to 325Vdc 8 Active vs Passive Rectification Active:

Pros: Lower voltage drop Bi-directional current Higher efficiency Passive: Pros: No external control Simple Inexpensive Cons: Requires control More expensive

More complex Cons: Uni-directional current Higher voltage drop Lower efficiency 9 Possible DC/DC Topologies Boost Flyback SEPIC Buck Boost

Copyright 2016 Advanced Power Electronics & Electric Drives Lab (APEDL) 10 Boost Converter Diagram 11 Ideal Boost Waveforms Output Voltage ~305-345V

Input Current ~0-50A Output Power ~1325-1525W Power Factor >0.9999 Copyright 2016 Advanced Power Electronics & Electric Drives Lab (APEDL)

12 Boost Pros Pros: Small Footprint Simple Design PF well over 0.99 Inexpensive No transformer required Operates at large range of power 13 Boost Cons

Cons: Difficult to stabilize High voltage ripple High current inrush Requires a large inductor 14 Flyback Converter Diagram 15 Ideal Flyback Waveforms Input

Current: 0A~59A Output Power: 900W~1180W Output Voltage: 290V~340V Power Factor: 0.998

16 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 Copyright 2016 Advanced Power Electronics & Electric Drives Lab (APEDL) 17

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

10/20/16 Copyright 2016 Advanced Power Electronics & Electric Drives Lab (APEDL) 18 SEPIC Converter Diagram 19 Ideal SEPIC Waveforms Output Voltage: 322V329V

Input Current: 0-150A 20 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 10/20/16

Copyright 2016 Advanced Power Electronics & Electric Drives Lab (APEDL) 21 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 10/20/16 Copyright 2016 Advanced Power Electronics & Electric Drives Lab (APEDL) 22 Buck-Boost Converter Diagram 23 Ideal Buck-Boost Waveforms Open Loop

Output Voltage ~-315-335V Input Current ~0-50A Output Power ~1325-1525W Power Factor

~0.93 Copyright 2016 Advanced Power Electronics & Electric Drives Lab (APEDL) 24 Buck-Boost Pros Pros: Large frequency range No transformer No inrush current or precharge like the boost More stable output voltage 25

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 26 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 LT4320 was used to control the mosfets for rectification. 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.

27 DC/DC Converter Pros & Cons 28 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. 29 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 30 Fall Timeline 10/20/16

Copyright 2016 Advanced Power Electronics & Electric Drives Lab (APEDL) 31 Spring Timeline 32 Resources

J. Betten. (2011, Q2) Benefits of a coupled-inductor SEPIC converter Analog Applications Journal [Online] Available: http://www.ti.com/lit/an/slyt411/slyt411.pdf [October 14 2016]. G. Sharp. Sepic Converter Design and Operation. BS, WPI, Worcester, MA, 2014. ST. TM sepic converter in PFC pre-regulator. Internet: http://www.st.com/content/ccc/resource/technical/document/application_note/48/9d/ 34/73/b9/27/48/65/CD00134778.pdf/files/CD00134778.pdf/jcr:content/translations/ en.CD00134778.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,pp176-198, [ 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: http://ecee.colorado.edu/~ecen4517/materials/flyback.pdf. [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,pp2867-2877 Copyright 2016 Advanced Power Electronics & Electric Drives Lab (APEDL) 33

Semiconductor Options IGBT MOSFET Voltage Rating: >1kv Voltage Rating: <1kV Current Rating: >500A Current Rating: <200A Slower switching

Faster switching More expensive Less expensive 34 Frequency Domain Analysis: Buck-Boost Current vs Voltage 100k Ohm Load

FFT of current with no load at 100kHz 35 Frequency Domain Analysis: Buck-Boost Current vs Voltage 100 ohm 100 ohm load FFT of current 36

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 controllers 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 37 Questions? 38

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