This paper deals with the control of a flyback converter in power factor correction (PFC) mode and the influence of the conduction mode on the converter design when using an optimization under constraints approach. In this context, a mixed control associated with mixed current conduction combining both discontinuous and continuous conduction over the low frequency period is presented, simulated and validated by experiments. This mixed conduction, which allows a compromise between transformer volume and semiconductor current constraints (maximal and RMS current values), is integrated within a flyback design approach using optimization under constraints. The obtained results demonstrate the effectiveness of this optimization approach in determining the balance between discontinuous and continuous conduction durations over the low frequency period. Moreover, the interest to consider the conduction mode as an optimization criterion is established.
In this paper, a position sensorless control method for IPMSMs using a full-order observer based on an algebraic design is proposed. The full-order observer is well known to be one of the powerful estimators for sensorless control of AC motors, for which design strategies have already been discussed. Although many numerical design and heuristic design approaches have been proposed so far, the design formulation for improving robustness with respect to mismatches in some parameters, however, is now an open problem. First, the proposed flux model for position sensorless control of IPMSMs has been reviewed, in which this model can approximately estimate the maximum torque control (MTC) frame, which stands for a new coordinate aligned with the current vector at the MTPA control. Next, an algebraic design of the full-order observer based on the proposed flux model has been proposed. In this paper, a design guideline to suppress the sensitivity of the speed estimation error has also been proposed. Finally, some experimental results demonstrate the effectiveness of the proposed method.
This paper introduces a method to generate minimal energy joint trajectories during a single support phase of linear inverted pendulum model (LIPM)-based biped walking. By using a variational approach and B-spline curves, this method is able to generate new set of joint configurations. This joint set minimizes the cost function which reduces the energy consumption while keeping the center of mass almost at the same position in x-, y- and z-directions. Constraining the center of mass to be the same during minimization helps in conserving the zero moment point (ZMP) of the predefined walking trajectory. The energy consumption function is represented by the actuator's electrical energy which consists of copper loss and mechanical energy. From the simulation results, it is verified that the proposed method is effective.
High-performance power switching devices are used to realize high-performance power converters. These devices tend to generate high-speed switching harmonics that cause electromagnetic interference (EMI). There are several methods for reducing undesirable effects of EMI. An EMI filter or shielding is one of the most popular ways to reduce EMI; however, both EMI filter and shielding increase the cost, size, and weight of power modules. It is well known that the shape of the switching transient strongly affects the harmonics distribution. This paper proposes a new method for reducing high-frequency noise at specific frequency bands by modifying switching transient slopes. This paper describes the improvement in the method of transient wave calculation for obtaining more effective waveforms. In addition, it provides experimental verifications to show the feasibility of the proposed method.
This letter presents a full-function design and implementation of a multi-channel audiometer with programmable devices. Audiologists perform a battery of tests to measure the psychoacoustic and auditory capabilities of a patient. However, there is an increasing need for developing a multi-channel psychoacoustic testing system to evaluate the spatial hearing abilities of hearing impaired subjects, and also to measure the perceptual benefits of directional hearing aids. The design combines programmable devices and software to obtain higher-quality and complete signals required for audiometric tests. Electro-acoustic measurements and perceptual evaluations of the proposed design show that the proposed system provides comparable performance as a commercial audiometer, with increased programmability, portability, and multi-channel testing capabilities.