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HW/SW codesign of a multiple-injections driver for engine

control systems

Alessandra Nardi

Fan Mo

Mentor : Alberto Ferrari

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OUTLINE

• Problem definition

• Driver specifications

• Behavioral model

• Functional simulation results

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PROBLEM DEFINITION - I

• HW/SW Driver for fuel injection

• Direct injection engine– 2 to 4 cylinders

• One injector for every cylinder– independent– max 5 strokes for engine cycle

• Tight time constraints

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PROBLEM DEFINITION - I

INTAKE COMPRESSION EXPANSION EXHAUSTED

120°

320°

440°

570°

CRANKSHAFT ANGLE

Massimo Baleani, Alberto Ferrari

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PROBLEM DEFINITION - II

Engine phase Engine angle

0

180

360

540

Exhaust ExplosionCompression Intake

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PROBLEM DEFINITION - III

• Fuel sub-system– sensor for fuel temperature (FT)– sensor for fuel pressure (FP)

• Engine angle – fly-wheel (FW) - every 6

– phase-wheel (PW)

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DRIVER INPUT/OUTPUT

INPUTS

• FW, PW, FT, FP

• Stroke fuel quantities (Q1,…,Q5)

• Stroke opening angles (T1,…,T5)• every TDC Exhaust

PARAMETERS:

Stroke angle ranges : (_o_k, _c_k)

Minimum closure time : Tcmin

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DRIVER INPUT/OUTPUT

OUTPUTS• Engine angle position (ALPHA90) - every 90

• Engine speed (SRPM90) - every 90

• DC events

• Injector signal J

• Fuel injected in the last cycle: F1, F2, F3, F4, F5

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DRIVER SPECIFICATIONS - I

• Max 5 strokes for each cycle of each cylinder

• k-th Injection Stroke (ISk) only in (_o_k, _c_k)

• Guarantee : IS1 < IS2 < IS3 < IS4 < IS5

• Overlapped strokes:– injector closed for a minimum amount of time

Tcmin

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DRIVER SPECIFICATIONS - II

Tk (_o_k, _c_k) ?

• IF Tk < _o_k

THEN _o_k = _o_k

• IF Tk > _o_k

THEN ISk not scheduled

• IF Tk (_o_k, _c_k)

THEN _o_k = Tk

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DRIVER SPECIFICATIONS - III

• In case of overlapped strokes:

Minimum Closure Time

IS1

IS1

IS2

IS2

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IMPLEMENTATION CONSTRAINTS

• Injection open angle resolution : +/- 0.2• Injected fuel quantity precision : 0.1mg

– if not cut

• All computation must be integer• Only basic mathematical instructions (no sqrt)

• Use IC/OC to implement timed functionality

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IMPLEMENTATION CONSTRAINTSInjection open angle resolution : +/- 0.2• Constant speed model

= ·t

• Constant acceleration model

= 0 ·t + 1/2 · a ·t2

• Error : = 1/2 · a ·( / 0 )2

• Example: = 60 = 1,000 rpm

a = 10,000 rpm/s = 0.03

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IMPLEMENTATION CONSTRAINTS• Injected fuel quantity resolution : +/- 0.1mgV = Q / D = 0.1mg/(0.76mg/mm3) = 0.131mm3

t = 13.1 s

Example:

= 0.03

t = / 0

0 = 1,000 rpm t = 5s

Counter Precision0 = 8,000 rpm t = 125 s Tclock = 0.5s

0 = 500 rpm t = 2 ms # ticks = 4000

# bits = 12

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FUNCTIONAL/ARCHITECTURE CODESIGN

• Behavioral Model– Behavioral Decomposition #1

resources– Behavioral Decomposition #2

resources optimization

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BEHAVIORAL DECOMPOSITION #1

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BEHAVIORAL DECOMPOSITION #2

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BEHAVIORAL DECOMPOSITION #2

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DRIVER SYSTEM

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ENGINE DETECTION

Description of the modules:

- FRC

- DETECTOR

- SAMPLE90

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CYLINDER DRIVER

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CYL_DRIVER/OPEN_INJECTION_ANGLES

Tk (_o_k, _c_k) ?

• IF Tk < _o_k

THEN _o_k = _o_k

• IF Tk > _o_k

THEN Isk not scheduled

• IF Tk (_o_k, _c_k)

THEN _o_k = Tk

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CYL_DRIVER/TIMER_SYSTEM_MNG

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TIMER_SYSTEM_MNG/V_T_S_CONVERTER

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DESIGN FLOW

ESTERELDescription

ESTERELCOMPILER

C SIMULATIONPlatform

TESTBENCHPART

DESIGN MODULEPART

TESTBENCHDescription

CCOMPILER

ExecutableFile

OUTPUT DATARecordCOMPARE

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SIMULATION RESULTS: RPM

0

1000

2000

3000

4000

5000

6000

7000

8000

0 1000000 2000000 3000000 4000000

Time [s]

Spe

ed [

rpm

]

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SIMULATION RESULTS: INJECT PULSE

0

0.2

0.4

0.6

0.8

1

1.2

0 1000000 2000000 3000000 4000000

Time [s]

Inje

ctor

sig

nal

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SIMULATION RESULTS: INJECT PULSE

0

0.2

0.4

0.6

0.8

1

1.2

0 50 100 150

Inje

ctor

sig

nal

Angle [°]

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PERFORMANCE

- RPM: error < 0.3rov/min

- STROKE: no functional error,

angle error < 0.08 degree

- CLOCK FREQUENCY: 1MHz

(with reference to Testbench provided by Alberto Ferrari)