National Instruments NI 9751 User manual

SHC68-68-RDIO

USER MANUAL

NI 9751

NI Powertrain Controls Direct Injector Driver Module

Contents

Safety Guidelines...................................................................................................................... 2

Introduction .............................................................................................................................. 2

Pinout........................................................................................................................................ 3

Hardware .................................................................................................................................. 4

Powering the Module................................................................................................................ 4

Platform Compatibility ............................................................................................................. 6

Internal Boost Power Supply.................................................................................................... 7

Direct Injector Drivers.............................................................................................................. 10

Connecting Injectors to the Module ......................................................................................... 25

Specifications............................................................................................................................ 26

Where to Go for Support .......................................................................................................... 29

2|ni.com |NI 9751 User Manual

Safety Guidelines

High Voltage The NI 9751 normally operates at voltages up to 190 V. Take

extreme care to protect against shock. Even when the NI 9751 is completely powered

off, allow approximately three minutes for the internal high voltage to dissipate. Do

not touch any of the module screw terminals or injector terminals while the NI 9751

is powered on.

Caution Do not operate this module in a manner not specified in these operating

instructions. Product misuse can result in a hazard. You can compromise the safety

protection built into the product if the product is damaged in any way. If the product

is damaged, return it to National Instruments for repair.

Caution The fuse illustrated in Figures 32 and 33 is user-supplied and required in

all instances.

Introduction

The NI 9751 Direct Injector (DI) Driver Module includes the following components:

• CompactRIO (cRIO) module with the following components for driving a variety of diesel

and gasoline DIs, including many piezo actuated injectors:

– 3-channel solenoid injector drivers

– 2-channel piezo injector drivers (in piezo mode)

– Up to 120 V internal boost power supply in solenoid mode

– Up to 190 V internal boost power supply in piezo mode

– Up to 40 A peak current drive

– 7 V to 32 V battery

– Optional external input for high voltage supply (up to 190 V)

• Internal boost supply automatically shuts down when external high voltage

applied is greater than 24 V

– Circuit protection and diagnostics features, including:

• Protected against INJ± short to battery/high voltage

• Protected against INJ± short to GND

• Internal power supply overload protection

• Internal power supply over-charge protection

• Module temperature protection

• Open circuit detection

• Fault flags reported for all above conditions

NI 9751 User Manual |© National Instruments |3

• LabVIEW FPGA and RT VIs with the following features for engine-synchronous,

multi-pulse injection control strategies:

– Up to 16 pulses per injection cycle (Engine Speed Limited)

– Configurable for any combination of angle and time triggering

– Current control profile with the following characteristics:

• Up to 8 phases

• Each phase provides settings for upper and lower current dithering setpoints

• Duration and drive voltage (battery or boost) specified for each phase

• First phase can be configured to end after first peak

• DI Calibrator application, which assists with firing injectors on a test bench for configuring

the injector current/voltage profile

• Piezo injector operation for unipolar drive

• Inverted piezo drive supported (Discharge = ON, Charge = OFF)

Each DI driver channel is individually controlled for timing and duration, but channel operation

cannot overlap. The NI 9751 cannot control piezo and solenoid actuator types simultaneously.

When configured for piezo mode, channel 3 is not available and you must short the terminals

together.

Pinout

BATT

INJ1–

INJ1+

INJ2–

INJ2+

INJ3–

INJ3+

EXT PWR

GND

4|ni.com |NI 9751 User Manual

Hardware

The NI 9751 provides three channels for driving unipolar solenoid and piezo injectors in a

National Instruments cRIO module. Use the included internal boost power supply to provide

short phases of boosted voltages for higher current operation.

Powering the Module

The NI 9751 requires power from each of the following sources:

• The CompactRIO backplane male high density 15-pin DSUB (HD15) connector, which

mates with the female HD15 connector on the module. This power source provides a

regulated 5 V and ground to various digital logic functions. The CompactRIO 5 V source

is active whenever the CompactRIO or R Series Expansion Chassis is properly powered.

You can power the NI 9757 only at the HD15 connector by plugging it into a CompactRIO

or R Series Expansion Chassis. Do not connect the HD15 connector to any other device.

• The external screw terminal connector block, the terminals of which are labeled BATT (0)

and GND (9). A typical power source is an automotive 12 VDC or 24 VDC battery system,

but the NI 9751 can accept power from a range of 7 VDC to 32 VDC.

Caution You must use a UL-listed power supply with the NI 9751.

With the internal boost power supply and injector outputs disabled, the NI 9751 requires up to

100 mA from the external supply. The following formula calculates the total power required to

operate the module and drive injectors:

Where: Ip (A) = Peak current

Ih (A) = Hold current

HVTarget (V) = High Voltage Target from internal boost supply

BattV (V) = Battery voltage supplied to BATT(0)

Tip (sec) = Time of peak current phase

DurAve (sec) = Average duration of all injection pulses within an engine cycle

RPMmax (RPM) = Maximum engine speed in RPM

Nchan = Number of channels used

Npulse = Number of injection pulses per engine cycle

This formula assumes a 4-stroke engine cycle. For 2-stroke engines, multiply the result by 2.

Power HVT etarg IP×Tip×

20.70×

----------------------------------------------------- BattV Ih×DurAve Tip–()×+





RPMmax Nchan×Npulse×

260×

-------------------------------------------------------------------------

×=

NI 9751 User Manual |© National Instruments |5

A 100 W power supply is sufficient for most applications. Power requirements might peak up to

150 W for more demanding applications.

The external battery ground is isolated, within the module, from the CompactRIO 5 V supply

ground. You can externally connect the external battery ground and the CompactRIO ground.

Note Both power supplies must be active for software to recognize the module.

Caution The external battery supply input terminals are not protected against

reverse-voltage polarity. Connecting power to the module in reverse polarity will

damage the module. This event is not covered by warranty.

The NI 9751 includes an optional power input to the external screw terminal connector block

labeled EXT PWR (7). The ground reference for EXT PWR (7) must be the same ground as

GND (9). This power input can range from 24 V to 190 V and is optionally used to provide the

boost voltage in place of the internal boost supply. Because the internal boost power supply is a

significant contributor to the internal module heat generation, this external power input might be

necessary if the injector drive requirements, in combination with maximum engine speeds, cause

the internal module temperature to exceed the limit.

When a voltage greater than 24 V is applied to the EXT PWR (7) terminal, the internal boost

power supply automatically shuts off, even if it is enabled via software. Even when EXT PWR

(7) is connected to an external high voltage power source, BATT (0) must still be connected to

7 V to 32 V in order for the module to be properly powered for general functions. In most

applications the EXT PWR (7) terminal is not necessary and should be left unconnected.

Table 1. Example Power Calculation

Parameter Value

Ip 25 A

Ih 15 A

HVTarget 75 V

BattV 13.8 V

Tip 0.000100 sec

DurAve 0.000800 sec

RPMmax 4500 RPM

Nchan 3

Npulse 2

Power 65 W

Continuous Current 4.5 A

6|ni.com |NI 9751 User Manual

Platform Compatibility

NI Powertrain Control modules require a hardware support system to function. You cannot use

the modules independently or interfaced with third-party devices at the backplane HD15

connector. NI Powertrain Control modules are compatible with the following National

Instruments platforms:

• CompactRIO, which consists of a CompactRIO controller, chassis, or integrated

controller/chassis.

• NI PXI, which consists of any NI PXI chassis, NI PXI RT controller, and NI PXI-78xxR

R Series FPGA card. The NI Powertrain Control modules insert into an NI R Series

expansion chassis. Connect an NI R Series expansion chassis to the NI PXI FPGA card

using a SHC68-68-RDIO cable.

Note NI Powertrain Control modules are not compatible with the National

Instruments CompactDAQ chassis.

You can use NI Powertrain Control modules with NI cRIO-911x, NI cRIO-907x, and NI R Series

Expansion systems under the following conditions:

• Leave one empty chassis slot between NI Powertrain Control modules and other

NI modules.

• Maintain an ambient system operating temperature of 0 °C to 45 °C.

Note Typical specifications of National Instruments modules might not apply when

used in a system with NI Powertrain Control modules.

Note National Instruments guarantees warranted specifications for all National

Instruments modules except thermocouple modules when used in a system with

NI Powertrain Control modules.

Note National Instruments recommends the NI 9214 for thermocouple

measurements in CompactRIO systems using NI Powertrain Control modules.

Note NI Powertrain Control modules do not support Scan Interface mode,

auto-detection, or ID mode.

NI 9751 User Manual |© National Instruments |7

Internal Boost Power Supply

The NI 9751 contains an internal boost power supply that can maintain a voltage level from

battery voltage up to 190 V. You can use software to enable or disable boost power supply at

any time. The internal booster power supply is disabled automatically whenever critical faults

occur and can only be enabled by clearing the faults. Internal capacitors store the high voltage,

which is used to drive the high-voltage phases of the injector current profile.

High Voltage The NI 9751 normally operates at voltages up to 190 V. Take

extreme care to protect against shock. Even when the NI 9751 is completely powered

off, allow approximately three minutes for the internal high voltage to dissipate. Do

not touch any of the module screw terminals or injector terminals while the NI 9751

is powered on.

Internal Boost Power Supply Performance

The following critical factors determine how well the internal boost power supply will perform

for a particular injector solenoid application:

• Injector solenoid resistance

• Injector solenoid inductance

• Peak current required to open the injector valve

• Working voltage requirement (HVTarget)

• Frequency of injection events

• Injector solenoid back-boost time (BackBoostTime)

Injector Solenoid Resistance

Typical common rail diesel injector solenoids will have a resistance of 1 Ωor less. This

resistance wastes, as heat, a portion of the energy supplied to the solenoid and affects the

maximum current achieved in the coil, which depends on the drive voltage applied. In general,

lower solenoid resistances are better for common rail solenoid injector applications.

Injector Solenoid Inductance

Typical common rail injector solenoids have an inductance of 1 mH or less. Inductance acts to

resist current change through the coil. As inductance increases, more time is required to achieve

the required peak current level, given a constant drive voltage. When you use the internal high

voltage to drive current, energy transfers from the internal high voltage capacitance to the

injector solenoid. Longer drive times deplete energy from the internal high voltage capacitance.

The internal boost supply works harder to maintain the high voltage target. Inductance is

proportional to the magnetic force generated for opening the injector valve.

Peak Current Requirement

Higher peak-currents require more energy from the internal boost power supply because the

internally stored high voltage depletes at a higher rate.

8|ni.com |NI 9751 User Manual

Working Voltage Requirement

The internal boost power supply can maintain a higher working voltage to drive the peak current

level in a shorter amount of time and provide quicker valve opening times and more predictable

fuel injection quantities over a given injection duration. The boost power supplies operate less

efficiently at higher voltages. The power supply must work harder to maintain a higher working

voltage. Typical times to reach 20 A in common-rail diesel injectors are on the order of 30 to

100 μs, with a working voltage of 100 V.

Frequency of Injection Events

The frequency of injection events is directly proportional to the work the power supply requires

to maintain the working voltage.

Injector Back-Boost

You can obtain a significant and useful back-boost charge from the injector solenoid at the end

of each injection event. This back-boost from the solenoid depends on the hold-current level

during the injection event and the working voltage of the boost power supply. If you correctly

configure the current profile, a small back-boost on the order of 5 V occurs to the power supply,

which reduces the work required to maintain the working voltage.

You might incorrectly configure the module to use very little of the high voltage supply for

driving the peak current while also setting a high hold-current level. This configuration can lead

to back-boosting the power supply over the required working voltage. Use the internal high

voltage supply to prevent this from happening. If the working voltage exceeds 190 V, a fault

occurs and shut down proceeds automatically.

Power Supply Faults and Protections

The following critical faults related to the operation of the internal power supply might cause all

operations of the module to shut down automatically. Two or more of these faults might occur

under certain conditions. For example, the power supply might be loaded such that the board

temperature reaches its limit before the overload integrator limit is reached. You can re-enable

the internal boost power supply and injection control by manually clearing the faults with

software.

Power Supply Charge Fault (PSCharge)

If the power supply is actively attempting to recharge and detects that the voltage is not rising,

the charge fault is set. This fault most likely occurs when an internal problem, such as a capacitor

failure, exists with the module.

Power Supply Overload Fault (PSOverLoad)

The NI 9751 maintains an integrator of power supply usage. An internal counter increments with

each power supply voltage boost and decrements according to a fixed time interval. If the

integrator winds up to 148,480 counts, an overload fault is set. This fault indicates that the

module temperature will soon rise beyond the maximum operating temperature unless stopped.

The module temperature fault might trip before the overload fault, depending on the actual

conditions.

NI 9751 User Manual |© National Instruments |9

Module Temperature Fault (ModuleTemperature)

Due to the C Series module housing design, there is limited ability for heat to escape. The

primary source of heat within the NI 9751 is the internal boost power supply. If the internal

module temperature rises above approximately 80 °C, the module temperature fault is set.

High Voltage Limit Fault (HighVoltageLimit)

If the charge on the internal power supply exceeds 190 V, the high voltage limit fault sets. This

fault can occur due to excessive injector solenoid back-boosting. Excessive solenoid

back-boosting can be caused by driving solenoids with very high inductance while not using

the boost supply.

Internal Boost Power Supply Benchmarks

Table 2 describes bench test results that demonstrate power supply capability.

With air flow over the NI 9751, you can extend the duration of operation at heavy loads.

Table 2. Bench Test Results

Test Condition

Test 1

(Solenoid)

Test 2

(Solenoid)

Test 3

(Piezo)

External Battery Voltage (V) 13.8 13.8 13.8

HVTarget (V) 75 75 190

PeakCurrent (A) 27 27 8

PeakTime (ms) 0.18 0.18 s N/A

HoldCurrent (A) 15 15 N/A

BackBoostTime (ms) 0.20 0.20 N/A

Number of injectors operated 3 3 2

Number of fuel pulses per cycle 1 5 1

Simulated engine speed (RPM) 5,000 2,000 7,200

Length of test (min) 10 10 480

Ambient temperature (°C) 25 25 25

Final module temperature (°C) 50 75 72

Temperature stabilized? Y N Y

Injector under test Bosch P/N 0445 110 072

Mercedes Benz P/N 611 070 09 87

Bosch P/N

0445 115 027

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