tailieunhanh - High Performance Driver P4

Equation of mechanical motion that describes rotor rotation is the same, irrespective of the type of the electric machine under consideration. It is given with the well-known expression Te − TL = J dω dt | HIGH PERFORMANCE DRIVES 1 1. WHAT IS A HIGH PERFORMANCE DRIVE GENERAL CONSIDERATIONS Equation of mechanical motion that describes rotor rotation is the same irrespective of the type of the electric machine under consideration. It is given with the well-known expression Te - Tl jdT dt Variation of speed of rotation is then given with 1 J j Te - Tl dt Let us assume that load torque is zero that the machine is at rest and there is now application of step speed command. The fastest possible response of the actual speed to its command will be obtained if it is possible to produce instantaneous step in the machine torque from zero to the highest allowed value Temax and to keep torque at this value until the actual speed becomes equal to its command. In such a case actual speed of the machine will be given with T e max . 1 ------1 Thus if a step increase in speed is required the torque command is a step function as well and the fastest response of the machine speed delayed with respect to reference because of inertia J is obtained if the actual torque in the machine can be stepped instantaneously to its commanded value which is equal to maximum permissible value. Hence the essential requirement in any drive which is to be used for highly demanding applications where precision and fastness of speed or position or torque control are of ultimate importance is possibility of instantaneous torque control. In other words not only steady-state but transient behaviour of the machine is controlled as well. A high performance drive is therefore a drive that provides an instantaneous torque response to the change in torque command with ideally actual torque equal to the reference torque without any delay. Typical areas that ask for high performance electric drives are robotics machine tools rolling mills paper industry electric vehicles traction elevators cranes etc. Some of these ask for torque controlled drives electric vehicles traction while in others the .