Presence Of Load Variations Research Articles

A contactless electrical energy transmission system for portable-telephone battery chargers

A high-performance contactless electrical energy transmission (CEET) technique which employs the inductive energy transmission principle is described. The proposed technique enables the implementation of high-efficiency high-power-density fully regulated CEET systems suitable for applications with a wide input and load range. A high efficiency of the system is achieved by recovering the energy stored in the leakage inductances of the transformer by incorporating them in the operation of the circuit, and by employing high-frequency-inverter and controlled-rectifier topologies that allow a controlled bidirectional power flow through the transformer. In addition, a feedforward variable-switching-frequency control of the inverter is used to maintain approximately constant power transfer through the transformer with the input voltage changes, whereas the output-side rectifier employs a local pulsewidth-modulation control to achieve a tight regulation of the output in the presence of load variations. Specifically, the described CEET system is suitable for use in universal-input battery chargers.

Robust Digital Control of Flexible Transmissions Using the Combined Pole Placement/Sensitivity Function Shaping Method

The control of very flexible transmissions in the presence of load variations is a challenging control problem. In this paper it is shown that based on identified discrete time models a robust digital linear controller can be designed using the combined pole placement method with sensitivity function shaping in the frequency domain. This controller provides satisfactory performance for a large range of load variations.

Integral variable structure control approach for robot manipulators

An integral variable structure control (IVSC) approach for robot manipulators is presented to achieve accurate servo-tracking in the presence of load variations, parameter variations and nonlinear dynamic interactions. A procedure is proposed for choosing the control function so that it guarantees the existence of the sliding mode and for determining the coefficients of the switching plane and the integral control gain such that the IVSC approach has the desired properties. Furthermore, a modified proper continuous function is introduced to overcome the chattering problem. The proposed IVSC approach has been simulated for the first three links of a PUMA 560 robot arm as an illustration. The simulation results demonstrate the potential of the proposed scheme.