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The conventional pulse width modulation (PWM) modes for braking operation in Brushless DC motor may cause diode freewheeling in inactive phase during normal conduction period which will aggravate torque ripple. In this paper, a novel braking PWM modulation mode named PWM_OFF_PWM is proposed to eliminate the diode freewheeling. The performance of the proposed PWM_OFF_PWM mode on diode freewheeling...
An inertial stability and tracking control method based on parameter identification is presented for the nonlinear driving missile launcher. Nonlinear driving structure of the missile launcher is analyzed, and the kinematic relationships and dynamical equations are described. Nonlinear driving part will be identified by the polynomials fitting function. Compared with the traditional inertial stability...
Brushless DC motor has been becoming more popular in industry, electric and aerospace applications, making the control for four-quadrant operation of Brushless DC motor greatly significant. This paper presents pulse width modulation (PWM) control mode for four-quadrant operation of Brushless DC motor, which can realize both motoring and braking operation at the same rotation direction. Based on the...
This paper presents a novel method based on delaying Hall signal for reducing torque ripple of brushless DC motor. During the delayed interval, the back electromotive force (back-EMF) amplitude of outgoing phase declines and the phase current rises to stabilize phase voltage. The electromagnetic torque can remain steady by regulating the duty ratio. During the commutation interval, the time of outgoing...
Welding robots have become increasingly intelligent, but they cannot possibly carry out any welding operation entirely by themselves and have to be operated by human beings. The paper serves as a useful source of information on standards developed for qualification of robotic welding personnel and it also touches on the robotic welding safety issues.
Owing to the inductance in the stator winding of brushless DC motor, the current can't respond immediately. During the commutation interval, the non-commutation phase current ripple and commutation torque ripple are emerged. This paper presents a novel voltage compensation topology, including four switches, one power diode and one capacitor. By controlling switches sequences, in the non-commutation...
A dual loop iterative learning control method is presented for macro-micro dual actuator driving systems. As the model and coupling effects of the macro-micro motion system are analyzed, the dual loop macro-micro control structure is employed to attenuate the coupling effects. In addition, dual loop iterative learning control is employed based on the above structure. Then tracking errors of the micro...
In order to provide high quality video service on large-size display in the Terrestrial Digital Multimedia Broadcasting (T-DMB), this paper adopts the hierarchical modulation and the transponder technique. The hierarchical modulation is used to increase the data rate, while the backwards compatible is guaranteed. For expanding the coverage of the T-DMB, the antenna transponder is applied. Meanwhile,...
Expected to serve in the next generation of illumination, LED offers such advantages as high brightness, lower power consumption and long lifetime. The LED lighting system, based on high switching performance, can also be utilized in communication. So it is available that the research is processed in the LED indoor visible-light communication. In this paper, consulting the channel model of indoor...
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