Rail Pressure Control Setup Window - National Instruments NI DIDS-2003 Manual

National Instruments Direct Injector Driver System Manual

4.10 Rail Pressure Control Setup Window

The purpose of the Rail Pressure Control (RPC) Setup window, is to configure a dedicated direct injection common-
rail fuel pressure control function. The function writes to the optional PFI Driver module lowside driver channels
which are connected to a high pressure pump Inlet Metering Valve (IMV) and a High Pressure Valve (HPV) on the
rail. The RPC function implements two PID controllers; one for RPC via the IMV, and one for RPC via the HPV. Only
one PID controller may be enabled at one time, either for IMV PID or HPV PID. While IMV PID is enabled, the HPV
must be controlled via constant PWM duty cycle. While HPV PID is enabled, the IMV must be controlled via constant
PWM duty cycle. The reason for this is because two PID controllers acting on IMV and HPV simultaneously would
conflict. Typically, RPC is performed using IMV PID control while applying a constant duty cycle to the HPV. The
RPC function must also have rail pressure feedback from an analog sensor mounted to the fuel rail. The analog
signal can be connected to any of the four channels of the optional NI 9215 analog input module. The utilized analog
channel can be selected via this Rail Pressure Control Setup window.
Typical IMV and HPV solenoids require up to 3A continuous current operation. Therefore it is important to utilize the
LS channel locking feature which locks LS1 with LS2 and locks LS3 with LS4. The locked channel pairs can be used
to operate the IMV and HPV with up to 3A continuous current. The example wiring diagram, figure 4.10.a, illustrates
wiring an IMV to a locked LS1 and LS2 pair, and wiring a HPV to a locked LS3 and LS4 pair. The LS channel locking
feature can be implemented via the PFI and LS Driver Setup window.
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