Open-loop controller

About: Open-loop controller is a research topic. Over the lifetime, 16148 publications have been published within this topic receiving 224014 citations. The topic is also known as: non-feedback controller & open-loop control law.

Inverter system for driving motor

Abstract: An inventor system in which a first power supply system powers: a switching-element-group driving a motor, a charging-pump-type gate-driving-circuit, an inverter controller. A second power supply system powers an air conditioning controller outside of the inverter. An insulating communication circuit provides communication between the inverter controller and the air conditioning controller insulating these two controller. Most parts of the inverter system are powered by a single power supply system, i.e. the first power supply system, whereby electromagnetic noises are reduced, spaces involved in insulation can be saved, and the amount of wiring as well as cost is reduced.

Input-shaped control of three-dimensional maneuvers of flexible spacecraft

Abstract: This paper deals with the control of three-dimensional rotational maneuvers of flexible spacecraft. A spacecraft model with a cylindrical huh and four symmetric appendages is considered. The appendages are tong and flexible, leading to low-frequency vibration under any control action. To provide a comprehensive treatment of input-shaped controllers (time-delay filters), both open-loop and closed-loop maneuvers are considered. For the open-loop maneuver, a five-switch, near-minimum-time bang-bang controller is designed based on the rigid-body model. The design procedure accounts for the presence of the time-delay filter for determining the switch times. In addition, a combination of a Lyapunov controller with the time-delay control technique is proposed to take advantage of the simple feedback control strategy and augment it with a technique that can eliminate the vibratory motion of the flexible appendages more efficiently. I. Introduction N this paper the problem of reorientation of a hub-apI pendage structure is considered. Considerable work has been done on Lyapunov control of single-axis maneuvers of hub-appendage structures. Hablani5 provides a technique for the estimation of the switch times for a bang-bang profile for zero residual energy, single-axis slew of a flexible spacecraft. Techniques are provided to estimate switch times for a system with either damped or undamped modes. A weighted time-fuel optimal controller for the rest-to-rest slew with zero residual energy is designed using the principles of dynamics by Skaar et a1.6 An elegant input-shaping scheme proposed by Smith 7 and later modified by Singer and Seering* has been used by Wie and Liu9 to modify the flexible-body time optimal control profile to produce a robust control scheme, which has been applied to the control of a two-mass spring model. Here we consider the three-dimensional case, leading to a model that has kinematic and dynamic nonlinearities. The system under consideration consists of a cylindrical hub, with four cantilevered cylindrical appendages of equal dimensions (Fig. 1). In modeling this system, only those modes that will be excited by a hub torque are considered. These modes lead to displacements of the appendages (which are modeled as EulerBernoulli beams), which resemble a three-dimensional starfish. The equations of motion of the flexible appendages are arrived at using the Lagrangian approach, and the rigidbody equations are arrived at using the Newton-Euler technique. The assumed modes technique is used to transform the partial differential equations (representing the equations of motion of the flexible appendages) to ordinary differential equations. Two modes are used to represent the displacement of each of the flexible appendages in the simulation of the system. The first controller proposed in this study is based on the amalgamation of two powerful control techniques. First, the rigid-body controller is designed based on the Lyapunov sta

An improved three phase variable band hysteresis current regulator

Abstract: This paper presents an improved variable band hysteresis current controller for a two level three phase voltage source inverter. The controller takes the average voltages of the phase-leg switched outputs as an approximation to the load back-EMFs, and uses this result to vary the hysteresis bands to maintain constant phase leg switching frequencies. The switching frequency control process is then further refined by fine tuning the hysteresis band variations to synchronise the zero crossings of the phase leg current errors with a fixed reference clock, to ensure nearest space vector switching and hence achieve the best possible harmonic switching performance. Finally, a technique is proposed to replace the third phase leg current regulator with a fixed frequency open loop PWM modulator, where its commanded reference is generated from the average switched output voltage of the other two phases. This avoids the hazard of three independent current regulators in a conventional system adversely interacting as an over constrained control problem, and allows the linear modulation range to be increased by adding a common mode third harmonic component to the third phase leg reference command.

Analysis of multi-rate discrete equivalent of continuous controller

Abstract: The paper is concerned with the analysis of multi-rate controllers, which update the controller output faster than the measurement sampling frequency by a factor of N. The controlled system is continuous, and the discrete time controller is obtained as its zero order hold equivalent. After deriving a set of equations necessary for analysis and design of multi-rate systems, the open loop characteristics of the multi-rate controller and the closed loop characteristics are examined. Several physical meanings can be derived from the formulation of the multi-rate controller.