Hybrid Go-Kart University of Connecticut Department of Electrical Engineering Team Members: Jonathan Blake (EE), Nathan Butterfield (EE), Joshua Calkins (EE), Anupam Ojha (EE) Advisor: Prof. Sung-Yeul Park 11/18/2013 1

Outline Introduction Power Sources Boost Converter Revisions Flyback Converter EIS Characteristics Timeline/Next Steps 2

What is Our Project? Design a power electronics system to combine three separate power sources in order to drive an electric go-kart. 3

The Power Sources We will use three power sources: o A 30V Lead Acid battery o Four ultra-capacitors, wired in series, at 14V across bank o Photovoltaic Panel, 8->40V output, 200W 4

System Overview 5

Boost Converter Design The design of our boost converter has changed drastically. The driving factor of these changes has been the input current. All of the following topologies were designed for 1.2kW. 6

Initial Design: 12V->36V Two boost converters in parallel, one for the ultra-capacitors, one for the battery. Input current of 100A. Finding an inductor rated for this current within out budget proved impossible. 7

Parallel Current Paths Placing multiple power stages in parallel is one way to handle the current. 8

Parallel Paths (cont.) 9

Integrated Circuit Controller 10

PCB Implementation Some of the paths shown in the previous diagram would have currents of 100 A. The cost of a PCB capable of handling these currents may be cost prohibitive. 11

Boost Power-Stage Platform High-current sections of a boost converter placed on separate platform, connected by cables. Current and voltage sensor output to microcontroller. Gate switching would determined by microcontroller, sent through gate drive circuit. 12

Boost Power-Stage Platform (cont.) 13

Flyback Specifications 14

Flyback Schematic

Flyback Transformer 16

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Litz Wire 18 High frequency increases wire loss due to skin effect. Multistrand Litz wire distributes current Small wire gauge allows signal to penetrate into the wire. Higher cost Window fill

Measure impedance at different frequencies Different sources and loads have different electrochemical characteristics that can change overtime Humidity, temperature, oxidation & electrode corrosion Diffusion creates impedance at low frequencies (Warburg)  makes impedance difficult to determine Electron & ion transport, gas & solid phase reactant transport, heterogeneous reactions  different characteristic time-constants  exhibited at different AC frequencies. EIS Testing

EIS Setup The device under test (DUT) will be the battery, PV panel and ultra-capacitor. Block diagram required for FRA to preform tests and obtain data.

FRA & eLoad FRA injects a range of frequencies along with a perturbation into the test device & signals the programmable load Measures voltage and current; creates Bode and Nyquist Plots Programmable eLoad varies impedance throughout the test. Programmable eLoad Frequency Response Analyzer (FRA)

EIS Setup Phases FRA  Computer interface o Manuals, Drivers, XP OS FRA out signal o Frequency sweep test Cooling T connector o Battery, ultra-capacitors, PV panel C2E2 EIS testing setup o Battery & ultra-capacitors FRA  Computer interface

Timeline Updated Blue = Original Plan Yellow = Updated Plan

Next Steps PCB Design of Flyback and Gate Drivers Physical Layout of Boost Power-Stage Platform EIS of Battery and Ultra-Capacitors Software algorithm and MPPT 24

Questions? 25