36 | © Danfoss | August 2018 AQ00000211
The PVED-CLS can control the cut-off solenoid valve, using two different current control algorithms, ON-OFF control
mode and closed loop control mode. The control algorithm is selected using the parameter P3073: Cut-off valve control
mode. Basically, both control algorithm is based on a PWM signal. Each of the control algorithms are described below.
ON-OFF control mode, i.e. P3073: Cut-off valve control mode is set to 0
This control algorithm will set the duty cycle of the PWM signal to 100%, when the PVED-CLS is activating the cut-off
solenoid valve, this means that the power supply of the cut-off solenoid valve will be equal to the PVED-CLS power
supply.
When the PVED-CLS is de-activating the cut-off solenoid valve, the duty cycle of the PWM signal will be set to 0%,
Meaning that power supply of the cut-off solenoid valve will be equal to 0VDC
Closed loop control mode, i.e. P3073: Cut-off valve control mode is set to 255
This control algorithm utilizes three different current levels; PWM pre-load, pull current and hold current. Each level
can be modified using the following parameters; P3097: Cut-off valve PWM pre-load value, P3074: Cut-off valve CL
pull current and P3076: Cut-off valve CL hold current.
The closed loop control mode allows for a lower current consumption, by setting P3076: Cut-off valve CL hold current
lower than P3074: Cut-off valve CL pull current.
The PWM pre-load, applies a PWM duty cycle, specified by P3097: Cut-off valve PWM pre-load value, for a period of
120ms, this ensures a fast pulling of the armature. After the 120ms period of PWM pre-load, the closed loop control
algorithm is applied.
The cut-off solenoid valve needs a higher current to pull the armature, then to hold the armature, once it has been pulled
to its open position. Therefore, the closed loop control algorithm, will start by applying P3074: Cut-off valve CL pull
current as set-point for a 1880ms pull period. In order avoid unnecessary energy waste, the closed loop control
algorithm, will then apply P3076: Cut-off valve CL hold current as set-point.
Therefore, it will take 2000ms, from the PVED-CLS activates the cut-off solenoid valve until it enters “power saving
mode”. The timing of the closed loop control mode is further described in Figure 14.
Since the closed loop mode, will keep the current constant regardless of the battery voltage, it possible to use the same
solenoids in all systems/machines.
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