Wesley BC-620-4CA - Manual (Page 99)

Curtis 1234/36/38 Manual,
OS
11 95
2 3 J U LY 2 0 0 8 D R A F T
The following brake processing variables are accessible by VCL:
VCL VARIABLE ACCESS DESCRIPTION
Pot2_Raw Read Only Voltage measurement at pin 17
Brake_Pot_Output Read Only Brake pot input value after being scaled
for the proper wiring
OS_Brake Read Only Brake pot value after mapping, to be used
in VCL when VCL Brake Enable = On and
Brake Type = 1–3
VCL_Brake Read/Write VCL-accessible brake command
Mapped_Brake Read Only Brake pot value after mapping
Brake_Command Read Only Command resulting from brake processing
Control Mode and Motor Control Processing
Figure 15 begins with the Throttle_Command and Brake_Command inputs
and a switch that will zero the Throttle_Command if Brake_Command is any
value but 0%. The signal chains are then directed to Speed Mode Express, Speed
Mode, or Torque Mode based on Control Mode Select. Note that in Torque
Mode there is no emergency reverse.
The control mode function uses algorithms to convert the incoming
throttle and brake signals and the motor rpm input into a Controller Torque
Command.
The selected control mode calculates the desired Controller Torque Com-
mand, which is passed to the Motor Control block (see Figure 14). The Motor
Control block uses its mathematical model of the specific AC induction motor
used to generate the high efficiency three-phase outputs that are output to the
AC motor via the cables connected to the
U , V , and W terminals.
INTERFACING THE PROPORTIONAL CURRENT DRIVER
VCL code can directly interface the proportional current driver (PD), as shown
in Figure 16. VCL can change the working parameters of the PD and can
provide the command.
Depending on how the PD system is to be used, certain parameters need
to be set; they can be set via the 1311 handheld programmer or via VCL.
1. PD_Enable must be set On for current control, otherwise
the PD_Output will be controlled by the VCL function
Put_PWM(PWM5,xxxx), which is voltage control.
2. Hyd_Lower_Enable must be set On to use the throttle input
to control lowering in a hydraulic lift/lower system.
3. Hyd_Lower_Enable must be set Off to allow using a VCL
variable (VCL_PD_Throttle) as the PD command.
Once the PD parameters are set, the PD_Throttle variable will be mapped
between PD_Min_Current and PD_Max_Current and sent to the dither
7 — VCL