Lenz vfd

[anupsrn 0]

Hi, We have a lot of lenze 9300servo vfd's in our plant. The feedback type in one of the parameters is set as resolver. The parameter has three choices- resolver, encoder or no feedback. I checked the motor run by this vfd and found that it has an encoder connected to it. What is the difference between a resolver and an encoder? I am new to automation and really require some basic guides to vfd's and plcs's. If u have any link to tutorials or pdf's please help. Thanks

[Joan M 3]

A resolver is giving you an absolute and single turn measure as it converts the degrees (0..360) where the motor is to the read data. An encoder can be absolute (single or multi turn) and incremental. Take a look at this whitepaper which will explain you the differences between the three measuring systems: Whitepaper Previous note: CALIBRATION or HOMING: this operation must be done with any system that require knowing it's real position and: - when the feedback comes from an incremental encoder. - when the feedback comes from a resolver but we make more than one turn/lap with the motor during the movements. Typically this operation is done with a sensor moving the axis towards the sensor until it changes, then you can set/know the position where you are. Summarizing: - A resolver will give you a degree in each turn so your controller will handle the data as the real degree where the motor is plus the number of turns that have been made to calculate the position. - An incremental encoder will give you pulses while the motor turns and those pulses will be counted by the controller to keep track of the position. - A single turn absolute encoder is typically used to control movements that require only one turn and when you don't want to calibrate the axis. - A multi turn absolute encoder is typically used when you don't want to calibrate. The previous list is ordered from cheap to expensive. Hope this helps you.