Technical data of Parvalux motors required by controllers

Topic:

• What motor data is required for proper configuration of Parvalux motors in use by maxon controllers?
• What "Thermal time constant winding" should be in use if it is not specified?

Solution:

maxon controllers mainly demand for the following motor data during initial commissioning (by ESCON and EPOS Studio's Startup wizard):

• Nominal current
• Thermal time constant winding

Parvalux and maxon motors can be overloaded for a short time during operation, i.e. they can also be operated above the specified "Nominal current" for a limited period of time. The configured values "Nominal current" and "Thermal time constant winding" are used by the motor control to permanently estimate the winding temperature with the so-called I2t algorithm depending on the profile of the actual load 's torque and motor current demands. If the estimated motor winding temperature reaches its maximum value, the motor current is limited to the configured "Nominal current" (i.e. also limited to the "Nominal torque") to prevent further heating up of the winding. The motor is thus effectively protected against overload and winding failure. The precondition that this works reliable is that the "Nominal current" and "Thermal time constant winding" are configured based on the motor's data sheet or a lower value but not higher values.

An additional important motor data is its "Speed constant" (or "Nominal speed") to configure a maximum speed level which can actually be reached on base of the controller's supply voltage.

The motor's "Nominal current" is present by Parvalux data sheets and can be configured accordingly.

The motor's "Thermal time constant winding" value is currently still missing by most Parvalux data sheets resp. it is still under investigation.

• If the "Thermal time constant winding" data is not specified, insert a value of approx. 35 seconds by maxon's ESCON and EPOS Studio's Startup wizard. This is a rough rule of thumb figure which offers a reliable winding protection for most Paravalux motors fitting to maxon's ESCON and EPOS4 power range. 
• If the "Thermal time constant winding" is specified by the motor's data sheet, please insert the specified value properly.
  
  

Additional motor data for proper configuration?

Another indirectly relevant motor parameter is the "Speed constant" (or "Nominal speed") present by its data sheet. Based on the speed/voltage characteristic or the "Nominal speed" and "Nominal voltage" of a motor, the maximum speed achievable in a system can be correctly calculated as a function of the supply voltage of the controller. This value has to be configured as "Max. speed" finally.

Additional remarks:

• The Parvalux controller SC50/15 (P/N: 738590) uses an internally fixed configured value for the "Thermal time constant winding" (of approx. 35s). There is no chance and no need to adapt this value.
• If you are thinking about a positioning or low speed control application by maxon controllers, please ensure that there is an encoder stiffly mounted on the motor shaft (e.g. by a motor combination ex factory) which fulfills the following preconditions:
  • Incremental or SSI absolute encoder
  • Encoder supply voltage: 5V
  • At least 500 counts per turn of the motor shaft
  • Differential encoder signals with a line driver, i.e. in case of ...
    • ... an incremental encoder: A, A\, B, B\ + optional I, I\
    • ... an absolute SSI encoder: CLK, CLK\, Data, Data\

Cross Reference:

• "EPOS4 Firmware Specification.pdf":
  • Chapter "3.11.2 Output Current Limitation according to I2t Method"
• Support Center documents:
  • ESCON / EPOS: How to configure "Max. speed" properly?
  • What supply voltage is required by a controller?
  • ESCON or EPOS: What controller should I select?
  • Parvalux PBL60 + maxon ESCON / EPOS4
  • Motor's "Nominal voltage" versus a Controller's "Supply voltage"?
  • Why can the usage of a motor controller be an advantage even for a DC motor?
  • Which encoder resolution should be chosen?