Inverter for high torque application
Tags: inverter, Vector control
For any high Torque applications like Jaw Crusher, V/F (being a scalar control) is never a right Torque control selection mode for inverters. Frequency inverter will obviously trip on over current faults whenever sudden dynamic response or Torque demanded is seen from the Load.
Also, if you operate a constant Torque application at low speed typically less than 30Hz in V/F control, inverter will trip on over current as it cannot provide the required Torque demanded by Load. V/F is best suited for variable Torque applications like Fan and pump.
The best selection in my understanding would be a modern Vector control inverter operated in vector mode. Many modern inverters have some best Torque Control features like FORCE (Field Oriented Control) that gives excellent Dynamic response, Torque control and are designed to run such application smoothly.
FORCE can provide control similar to that of a DC inverter by separating Flux and Torque producing components and controlling them individually to achieve best Torque and speed control results.
Also, if you operate a constant Torque application at low speed typically less than 30Hz in V/F control, inverter will trip on over current as it cannot provide the required Torque demanded by Load. V/F is best suited for variable Torque applications like Fan and pump.
The best selection in my understanding would be a modern Vector control inverter operated in vector mode. Many modern inverters have some best Torque Control features like FORCE (Field Oriented Control) that gives excellent Dynamic response, Torque control and are designed to run such application smoothly.
FORCE can provide control similar to that of a DC inverter by separating Flux and Torque producing components and controlling them individually to achieve best Torque and speed control results.
<- - I have an Opinion - ->
The inverter was commissioned on vector mode with speed control, the inverter is working satisfactorily, but we did also try out v/f mode. We found that whenever the current crossed the motor rated current, the inverter was unable to pump the required torque to the motor
when the inverter was configured on vector mode the output voltage increased whenever there was requirement for torque, in trend function available in inverter software we monitored the quadrature axis and direct axis component of output current. As per vector control theory, the quadrature axis component provides the magnetizing component while the other the load current. it was evident that the vector control is the best suitable one.
But whenever a situation occurs where the jaw crusher needs to be jogged from full loaded condition, many a time we had to jog the inverter forward and reverse to breakdown the rock. The problem was later resolved by increasing the overload rating and the jog setpoint - -> by: Shob K