Power Management Chip. Anthony Kanago Valerie Barry Benjamin Sprague John Sandmeyer

Transcription

1 mmax Power Management Chip Anthony Kanago Valerie Barry Benjamin Sprague John Sandmeyer 1

2 Outline Design Goals and Challenges Power Management IC Design Maximum Power Point Tracking (MPPT) Implementation Measurement Results Demonstration Platform Conclusion 2

3 Design Goals and Challenges Goals to design, fabricate, and test an integrated circuit (IC) to maximize the power production of an energy-harvesting system such as a micro solar cells, piezoelectric generator, or microbial bio fuel cells Challenges o Low-power operation o Low-voltage operation o Design complexity o Size limitation 3

4 Why Maximum Power Point Tracking? Maximum power point tracking (MPPT) is critical for efficient power generation from photovoltaic (PV) sources. Harvesting energy from small or integrated solar cells requires a lowpower MPP tracker and power management system. Electrical Model of PV Cell 4

5 Fractional Open Circuit Voltage The ratio of open circuit voltage (V OC ) and maximum power point (MPP) voltage (V mp ) is constant for fixed operating point. This is true for photovoltaic (solar) cells, thermoelectric generators (TEG) and microbial fuel cells (MFC). V mp 550mV Fraction=0.55 Micro Solar Cells V Thermoelectric Generator Microbial Fuel Cells oc 5

6 Fractional MPPT Implementation 0.4MΩ 1.6MΩ 200nA Utilize a pilot cell Approximate Voc with very large R string Comparator speed, input range considered 6

7 System Overview 7

8 Circuit Implementations

9 Fractional MPPT 9

10 Fractional MPPT V solar V oc V mp 10

11 Fractional MPPT V solar V oc V mp Trade off smoothing of Vsolar for response time with low-pass filtering 11

12 DC-DC Conversion 0-V AA V thp + V AA Clock self-generated by MPPT Comparator 12

13 Charge-Skimming Regulator (CSR) Structure imitates Anti-Blooming control in CCD/CMOS Imagers V target - V thp 13

14 Charge-Skimming Regulator (CSR) Structure imitates Anti-Blooming control in CCD/CMOS Imagers 1.8V 1.2V V target - V thp 14

15 Simulation Results Total Power Consumption: 17 mw Block Component Power Consumption Maximum Power Point Reference Generator Power Management TOTAL POWER Comparator Divider Beta Multiplier Reference Current Digital to Analog Converter Two Comparators Dynamic Power 1.56 mw 1.56 mw 0 mw 4.74 mw 3.13 mw 1.61 mw mw 3.12 mw 7.60 mw 17.02mW 15

16 Results Circuit Area 0.35mm2 Measured Power Consumptions During Harvesting μW After Caps Charged 18.04μW 16

17 Measurement Results Vout V 1.8V 6x SCPD 30K Lux Vout 2x 1000mF Caps (1) V out1 charged (1.8V) (2) V out2 charged (1.2), self-powering (3) CSR engages Vout PWR_Self 1.2V 1.2V 17

18 Demonstration Platform Sample state of system realtime using ADC Send via USB to host PC (Windows) Host PC plots signals realtime Custom wireless display interface using Android Tablet 18

19 Demonstration Platform Sample state of system realtime using ADC read by Xilinx FPGA Send via USB to host PC (Windows) Host PC plots signals realtime Custom wireless display interface using Android Tablet 19

20 Demonstration Platform 20

21 Summary Fractional open-circuit voltage MPPT Integrated, self-clocked, boost converter for voltage step up A new charge skimming regulation (CSR) suitable for low-voltage, lowpower applications Low-overhead power management algorithm 21

22 Acknowledgement Thank you to Dr. Ay and VSRG for opportunity, facilities, fabrication! Cadence University Program MOSIS Educational Service 22

23 Q & A 23

24 Testbench 24

25 Solar Cell Data Illumination (lux) Voltage at Max Power (V) Current at Max Power (A) Short Circuit Current (A) E Open Circuit Voltage (V) Rso (Ohms) Rsho (Ohms) Rsh (Ohms) n Is (Amps) E E E-10 Rs (Ohms) Iph (Amps) E

26 Solar Cells Series vs. Parallel 26

27 Power Management Switch Layout 27

28 MPP Comparator Layout 28

29 MPP Divider Layout 29

30 Power Management Switch Layout 30

31 Current DAC Layout 31

32 Top-Level Simulation 32

33 Top-Level Simulation 33

34 Current Digital to Analog Converter (idac) Schematic Design 34

35 BMR Simulations Transient Analysis DC Voltage Analysis 35

36 MPP Divider Simulation Transient Analysis 36

37 Battery Operation 37