4.7 Drive Command Controller
4-15
Chap. 4 BLOCK DIAGRAMS FOR CONTROL LOGIC
The simplified block diagram shown in Figure 4.6 explains the process in which the inverter drives the motor
according to the internal run command <FWD>/<REV> from the frequency generator, or the PID frequency
command from the PID controller, and the run commands.
Additional and supplemental information is given below.
- The logic shown in the left part of the block diagram processes the drive frequency command so as to invert
(u(-1)) the command for reverse rotation of the motor or to replace it with 0 (zero) for stopping the motor.
- The accelerator/decelerator processor determines the output frequency of the inverter by referring to the set
data of related function codes. If the output frequency exceeds the peak frequency given by function code F15,
the controller limits the output frequency at the peak.
- Acceleration/deceleration time is selectable from acceleration/deceleration time 1 or 2, or
acceleration/deceleration time for jogging operation. The suppression of the regenerative braking feature may
multiply the commanded acceleration/deceleration time by 3. Refer to role of function code H69 in the block
diagram.
- If the overload prevention control feature is active, then the logic automatically switches the output frequency
to one of overload suppression control and controls the inverter using the switched frequency.
However, if the current limit control is active (F43 z 30, H12 = 1), the overload prevention control
automatically becomes inactive.
- If the current limit control is active, then the logic automatically switches the output frequency to one of
current limit control and controls inverter using the switched frequency.
- The slip compensation facility adds frequency components calculated from the load based on the preset rated
slip frequency inside the inverter to the frequency currently commanded. The logic adjusts the error between
the rated slip frequency of the motor currently under load and the preset frequency according to the set data of
function code P09 that controls slip compensation gain for the motor.
- The voltage processor determines the output voltage of the inverter. The processor adjusts the output voltage
to control the motor output torque.
- If DC braking control is active, the logic switches the voltage and frequency control components to ones
determined by the DC braking block to feed the proper power to the motor for DC braking.
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