National Instruments NI 9751, Руководство пользователя, Страница: 6 / 30

NI 9751 User Manual
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© National Instruments
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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