Embedded Green System Project

65nm Process, 1.4mm square

LSI IP Award

Multiple-Performance Processor• Dynamic Voltage and Frequency Scaling• Dynamic Reconfigurable Cache Structure

Grant: Japan Cabinet Funding Program for Next Generation World-Leading Researchers

Target: Embedded computer systemGoal: Battery-less operation of the system

Approach: improving the efficiency of energy generation, transfer and consumption

Members:

Project Overview

Research Topics

OnoderaLaboratory

Energy Harvesting System

OS-based Energy Management

10mm x 7.5mm0.18um Process

• High efficiency by concerning the transferring efficiency

Results: 20~70% Reduction of power loss

SystemHardware(Kyungsoo LEE)

-Control engineering

-Energy harvesting

-Fuel cells-Modeling

SystemSoftware(Tohru ISHIHARA)

-Leader-RTOS-Compiler-Processor

Onodera Lab.

-VLSI design-Low-Power & Dependable Circuits

Collaboration with Prof. Chang of SNU

-Control theory-Energy harvesting

-RTOS-Embedded system

Collaboration with Prof. Takada of Nagoya Univ.

Configuratione.g.) VDD, Freq.

Configuratione.g.) MPPT

Periodically checks statuses of generation, charge, and consumption Make actions; change QoS, configurations, and execution modes

Quality of Servicee.g.）pixel resolution

Quality of Servicee.g.）frame rate

Execution modee.g.) CPU speed,

cache size

Execution modee.g.) LCD backlight

ConfigurationCharge/discharge

ConfigurationSeries/parallel

Quality of Servicee.g.）Service cycle

DC-DCconverter

ScalableProcessor

Scalable I/O

OS-based Energy Management Software

E generator Controller

Application Application Application

E storage Charger

Reduce voltage difference by the array reconfiguration Direct power supply from the supercapacitor I/O aware task scheduling

0 2 4 6 8Output voltage (V)

Out

put c

urre

nt (m

A)

IV curve

PV curve

Out

put p

ower

(mW

)400

0

100

200

300

500

80

0

20

40

60

100 MPP (5.08V, 81.8mA)

PV VI curve Efficiency of DC-DC converter

Pow

er lo

ss (m

W)

Voltage di↵erence (Vin

� Vout

)

Effic

ienc

y (%

)

100

75

50

25

0

100

75

50

25

00

25

50

75

100

-1.5 -1.0 -0.5 0 0.5 1.0 1.5 2.0 2.5

Power loss at 10 mA outputPower loss at 100 mA outputEfficiency at 10 mA outputEfficiency at 100 mA output

2. The system operation mode - Power pass configuration - Amount of charge/discharge control

DC-DC

DC-DC

DC-DC

DC-DC

Charger

L1

L2

Li

(mpv, npv)PV

Cap(mc, nc)

SW1

SW2

SW3

Vjunc = VMPP

DC-DC

DC-DC

DC-DC

DC-DC

Charger

L1

L2

Li

(mpv, npv)PV

Cap(mc, nc)

SW1

SW2

SW3

Vjunc = VMPP

DC-DC

DC-DC

DC-DC

DC-DC

Charger

L1

L2

Li

(mpv, npv)PV

Cap(mc, nc)

SW1

SW2

SW3

Vjunc = VCap

1. The voltage of energy source - Dynamic array configuration - Solar cell and supercapacitor array

3. I/O aware task scheduling