Proportional control

About: Proportional control is a research topic. Over the lifetime, 3756 publications have been published within this topic receiving 49050 citations.

A New Current Feedback PR Control Strategy for Grid-Connected VSI with an LCL Filter

Abstract: Proportional Resonant (PR) controller with harmonic compensators has extremely higher gain at the desired frequencies to reduce the harmonic distortions in the alternative voltage or current waves. However, the harmonic compensators of the PR controller are limited to several low-order current harmonics, due to the system instability when the compensated frequency is out of the bandwidth of the system control loop, especially for the grid-connected converters with the use of an LCL-filter and conventional current feedback methods. In this paper, a new current feedback method and PR control strategy for grid-connected voltage source inverters (VSI) with an LCL-filter is proposed. The weighted average value of the currents flowing through the two inductors of the LCL-filter is used as the feedback to the current PR regulator. Consequently, the control system with the LCL-filter is degraded from a third-order function to a first-order one. In this way, a large proportional control loop gain can be chose to obtain a wide control loop bandwidth that is required by the harmonics compensations of the PR controller, the system can be optimized easily for minimum current harmonic distortions as well as the system stability. The characteristics of the inverter system with the proposed controller are investigated and compared with those using traditional control methods. Experimental results on a 5kW fuel cell inverter are provided, and the new current control strategy has been verified.

Adaptive PID with sliding mode control for the rotary inverted pendulum system

Abstract: In this paper, a novel adaptive PID with sliding mode control for the rotary inverted pendulum is proposed. The goal is to achieve system robustness against parameter variations and external disturbances. In this study, the three parameters of PID controller, proportional gain, integral gain, and derivative gain can be systematically obtained according to the adaptive law. Further reduction of the high frequency chattering in the controller is achieved by using the boundary layer technique. The proposed control method is applied to a rotary inverted pendulum control system. By using Lyapunov theorem, the stability and convergence of the proposed scheme is proven. Simulation results show that the chattering and the steady state error are eliminated and trajectory tracking is achieved effectively.

Thyristorized DC Drives with Regenerative Braking and Speed Reversal

Abstract: This paper presents a systematic development of the analysis, design, and testing of a thyristor (SCR) controlled separately excited dc motor drive system. The motor armature voltage is supplied from a three-phase fully controlled six-pulse thyristor bridge. Closed loop control is analyzed using transfer function techniques and the necessity of an inner current control loop is demonstrated. Armature reconnection is used to enable regenerative braking and speed reversal. Design of both a proportional and proportional integral controller is outlined and experimental results are given.

A learning scheme for low-speed precision tracking control of hybrid stepping motors

Abstract: Servo control of the hybrid stepping motor is complicated due to its highly nonlinear torque-current-position characteristics, especially under low operating speeds. This paper presents a simple and efficient control algorithm for the high-precision tracking control of hybrid stepping motors. The principles of learning control have been exploited to minimize the motor's torque ripple, which is periodic and nonlinear in the system states, with specific emphasis on low-speed situations. The proposed algorithm utilizes a fixed proportional-derivative (PD) feedback controller to stabilize the transient dynamics of the servomotor and the feedforward learning controller to compensate for the effect of the torque ripple and other disturbances for improved tracking accuracy. The stability and convergence performance of the learning control scheme is presented. It has been found that all error signals in the learning control system are bounded and the motion trajectory converges to the desired value asymptotically. The experimental results demonstrated the effectiveness and performance of the proposed algorithm.

Tracking Control of Robot Manipulators Using Sliding Mode

Abstract: A new methodology using the theory of variable structure systems is developed for accurate tracking control of robotic manipulators. The proposed method, based on a sliding mode controller, produces a discontinuity control input so that the nonlinear interactions and influence caused by unknown parameter variations can be depressed whereas the resulting control law is simple and easy to apply to on-line computer control. The digital simulation results of a three-degree-of-freedom manipulator show the validity of accurate tracking capability and robust performance of the system with the developed control scheme.