Installation and Commissioning

Servo SystemSystem DescriptionThe following diagrams outline the system structure for AC operation as well as thefundamental structure of the drive unit.ComputerRotor positionTorque referenceSerial measurementboardDC link Drive Unit M RAC OPERATIONDC linkTORQUEreferenceROTORPOSITIONCURRENTESTIMATOR++M M--CURRENTREGULATORPWMPWM+-+-+UWVMMPWM-MAINCIRCUITSFigure 11 System structure for AC operation.3.4 Overload protectionPTC resistance is built into the robot motors to provide thermal protection against overloads.The PTC sensors are connected to an input on the panel unit which is sensitiveto resistance level and which check that low resistance is maintained.The robot computer checks the motors for overloading at regular intervals by readingthe panel unit register. In the event of an overload, all motors are switched off.14 Product Manual