Is there any steady state error present in speed output at any load in direct torque control of induction motor?

  • \$\begingroup\$ Can you explain a bit more about the control system? And also, why you are asking? In general, with an induction motor, I don't think there is any way to control speed without steady-state error, unless you use a speed sensor and feedback to correct the error. But I also don't think your question is very clear. \$\endgroup\$ – mkeith Apr 19 '19 at 6:28
  • \$\begingroup\$ Sorry for my confusing writing.Actually in my design speed error is calculated from speed reference and estimated speed which is used to command torque reference to controller through proportional controller.The torque error in found from command torque and estimated torque to find out most suitable switch vector applied to inverter for generating maximum torque available from motor.Here in this case flux error also need to be determine and appropriate switch vector applied to make it constant through out the operation.But when the load is applied there is speed error with proportional control \$\endgroup\$ – MANAS JENA Apr 19 '19 at 6:58
  • \$\begingroup\$ When I use PI control to reduce steady state error simulink show me singularity .halt the running plz help \$\endgroup\$ – MANAS JENA Apr 19 '19 at 7:02
  • \$\begingroup\$ I don't think I am knowledgeable enough to help. But even with very good vector control, induction motor speed may have some error unless an encoder or other speed sensor is used. \$\endgroup\$ – mkeith Apr 19 '19 at 7:03
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    \$\begingroup\$ This question needs a block diagram. \$\endgroup\$ – Chu Apr 19 '19 at 7:36

Without shaft speed feedback, the steady state speed error of an induction motor controlled by a VFD is likely to be 0.1% to 0.8% of rated speed. The error would include any speed change due to change in load plus changes due to variations in power-line voltage and temperature from a cold start. The error would be about the same for an excellent implementation of direct torque control and some other control strategies. The superiority of direct torque control is realized mostly in dynamic performance and performance at very low operating speeds.

  • \$\begingroup\$ Thank you very much \$\endgroup\$ – MANAS JENA Apr 20 '19 at 6:45

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