A fault detection and isolation (FDI) algorithm is proposed for the stuck fault detection of an aircraft with multiple control surfaces. The proposed FDI approach is composed of an adaptive observer and a bias estimation algorithm. The adaptive observer is designed for the stuck fault detection of the control surfaces, and the bias estimation algorithm is used to estimate the stuck position of the corresponding control surface. The bias estimation algorithm is designed using an unscented Kalman filter. Non-linear back-stepping control is applied. Also, to achieve the fault-tolerant property without redesigning the controller, control allocation technique is used. A non-linear aircraft model with the multiple control surfaces is considered. Numerical simulations are performed to demonstrate the performance of the proposed FDI algorithm.Nomenclature a angle of attack (rad) a 0 trim angle of attack (rad) Da difference between a and a 0 (rad) b sideslip angle (rad) f roll angle (rad) p roll angular rate (rad/s) q pitch angular rate (rad/s) r yaw angular rate (rad/s) g 0 gravitational constant (m/s 2
To measure the displacement of a shape memory alloy (SMA) coil spring actuator for feedback control, displacement sensors larger than the actuator are normally required. In this study, a novel method for estimating the displacement of an SMA coil spring actuator without a sensor is proposed. Instead of a sensor, coil inductance is used for estimating the displacement. Coil inductance is estimated by measuring the voltage and the transient response of the current. It has a one-to-one relationship with the displacement of the coil and is not affected by load. Previous methods for estimating displacement using resistance measurements are heavily affected by load variations. The experimental results herein show that displacement is estimated with reasonable accuracy under varying loads using coil inductance. This sensorless method of estimating the displacement of an SMA coil spring actuator can be used to build a compact feedback controller because there is no need for a bulky displacement sensor.
This paper presents a novel family of single-switch resonant dc-dc converters with low switch voltage stress. The single-switch resonant converter which has a ground-referenced switch is advantageous for implementing the gate drive circuit and operating at several-MHz switching frequency. However, the conventional ones mostly have high voltage stress on the switch, roughly 4-5 times the input voltage. In this paper, we propose the single-switch converter topologies derived from the drain-source impedance networks consisting of two inductors and two capacitors. The switch voltage of the proposed converters is shaped into a near trapezoid by designing the resonant networks to have the desired drain-source impedance. Furthermore, a simple and specific design scheme is presented here so that the peak switch voltage is lowered to 2.2-2.5 times the input voltage while zero voltage switching (ZVS) is achieved. Experimental results from a 20-W GaN-based prototype operating at 10 MHz demonstrate the feasibility of the proposed converter topologies and the design method.Index Terms-High frequency, resonant converter, single switch, switch peak voltage, zero voltage switching (ZVS).
In this paper, a new maximum torque per ampere (MTPA) control method for surface permanent magnet synchronous motors (SPMSMs) controlled by the scalar control (v/f) method is proposed. The scalar control is a sensorless method that controls only the magnitude and the frequency of the stator voltage vector without the information of the rotor position. This method suggests the injection of the high frequency voltage signal in the stator current vector reference frame, which can be calculated from the measured phase currents, to avoid the use of rotor position information. In addition, this method adjusts only the magnitude of the stator voltage to minimize the stator current based on the calculated input power. Another merit of this method is the robustness of the MTPA control to machine parameter errors or variations. With this proposed method, the stator current can be minimized in the whole speed-torque range and the drive efficiency can be improved. Simulation and experimental results are provided to verify the performance of this control strategy. INDEX TERMS V/f scalar control, maximum torque per ampere (MTPA), surface permanent magnet synchronous motor (SPMSM), high frequency voltage injection.
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