Impaired perceptual learning in a mouse model of Fragile X syndrome is mediated by parvalbumin neuron dysfunction and is reversible.

To uncover the circuit-level alterations that underlie atypical sensory processing associated with autism, we adopted a symptom-to-circuit approach in the Fmr1-knockout (Fmr1-/-) mouse model of Fragile X syndrome. Using a go/no-go task and in vivo two-photon calcium imaging, we find that impaired visual discrimination in Fmr1-/- mice correlates with marked deficits in orientation tuning of principal neurons and with a decrease in the activity of parvalbumin interneurons in primary visual cortex. Restoring visually evoked activity in parvalbumin cells in Fmr1-/- mice with a chemogenetic strategy using designer receptors exclusively activated by designer drugs was sufficient to rescue their behavioral performance. Strikingly, human subjects with Fragile X syndrome exhibit impairments in visual discrimination similar to those in Fmr1-/- mice. These results suggest that manipulating inhibition may help sensory processing in Fragile X syndrome

EPROM-based modulator for synchronized asymmetric regular-sampled SPWM technique

The objective of sinusoidal PWM technique is to synthesize the motor currents as near to a sinusoid as possible economically. Traditionally, PWM control is accomplished using a natural sampling technique. Though its implementation is simple and in real time, it cannot give good performance in the entire operating range. Microprocessor-based PWM generation can offer significant advantages but suffer from computational time limitations. Moreover, it is not economical for general-purpose variable speed drives. A novel technique of PWM signal generation is addressed in this paper. While different requirements of high performance SPWM are fulfilled, the circuit configuration is reduced compared with conventional circuits. A regular sampled, asymmetric, synchronized SPWM with variable gear ratio and third harmonic injection at higher modulation depth, is realized with much reduced hardware. Such reduction in complexity, cost and space are essential to boost the changeover from constant speed to variable speed drive for energy saving in general applications. This was the motivation of work presented. The technique is well suited even for dedicated implementation using a microcontroller.© IEE

Performance of line start permanent magnet synchronous motor with single-phase supply system

The operation of a three-phase induction motor from a single-phase supply with a capacitor in circuit is well known. While detailed investigations on the performance of the induction motor under such operating conditions are well reported in the literature, no such work is reported for the synchronous motor. The fine-start permanent-magnet synchronous motor (LSPMSM) is actively being considered as an energy efficient alternative to the induction motor in general purpose, heavy duty applications. The paper presents an analytical and experimental evaluation on the performance of a three-phase LSPMSM fed from a single-phase supply. This analysis is carried out using symmetrical component theory. A capacitor is connected across two stator phases during starting and running. Estimation of the capacitor value to achieve the desired objectives, such as minimum unbalance, maximum power factor, maximum torque or maximum efficiency, is carried out. Load tests are conducted to validate the simulation results

Investigations on delta modulated inverter

Delta modulation offers a number of unique advantages in static PWM inverter applications in variable speed AC drives. The performance of a delta modulator is investigated in this paper for a square wave reference signal. This changeover from sine wave reference signal to square wave reference signal can reduce the cost of the control circuit significantly which is crucial in FHP drive range. The parametric sensitivity of this modulator is studied in this paper.© IEE

Synchronous motor using ferrite magnets for general purpose energy efficient drive

A synchronous motor using ferrite magnets has the potential for energy saving in general applications such as fan, pump and compressor drives. A rotor geometry is suggested for this machine which eliminates the drawbacks of the conventionally used rotor geometries and gives higher airgap flux density. The performance of this machine with the proposed rotor geometry is compared with the conventional geometries for the same magnet volume and conductor density, employing field based circuit analysis. The performance of the machine for different operating conditions and asynchronous performance are also presented. The machine is also modified to suit the inverter fed drive.© IEE

Equivalent circuit of single phase permanent magnet synchronous motor

Growing consumer and legislative pressures are increasing the demand for improved efficiency of fractional horse power motors. The single phase line start permanent magnet synchronous motor has been shown to have potential for high efficiency. An equivalent circuit for this motor is proposed to predict the steady state performance of this machine. Criteria for estimating the value of capacitor required for balanced operation for desired load is outlined. The analysis is analytically validated.© IEE

Steady state performance of polyphase permanent magnet synchronous motor fed from single phase supply system

The operation of a three phase induction motor from a single phase supply with a capacitor in circuit is well known. While detailed investigations on induction motor performance under such operating condition are reported in the literature, no such work is reported for a synchronous motor. This paper presents analytical and experimental evaluation of the performance of a three phase permanent magnet synchronous motor (PMSM) fed from a single phase supply. A capacitor is connected across two of the stator phases during starting and running. The symmetrical component concept is used for the analysis. Estimation of capacitor value to meet the desired objective such as minimum unbalance or maximum efficiency is carried out. Experimental load tests are conducted on the machine, which validate the simulation results.© IEE

A new hybrid rotor geometry for permanent magnet synchronous motor

In this paper a new hybrid rotor geometry is suggested for line start permanent magnet synchronous motor, which uses circumferentially as well as radially magnetized magnets. It is derived from two basic configurations of interior permanent magnet motor and has the advantages of both the configurations. The main objective is to increase the air gap flux density of PM motor using ferrites magnets. The proposed geometry is also suitable for bonded rare earth magnets. The four pole configuration is studied using FEM analysis and different alternatives are suggested. A hybrid rotor using both ferrites and bonded rare earth magnets is also studied as a compromise between the performance and the cost. The field plots of computer simulation using Maxwell software are presented. The results are compared with the basic configurations for same magnet volume.© IEE