Input Voltage Amplitude Research Articles

Dynamic and contact analysis of a bimodal ultrasonic motor

A bimodal ultrasonic motor, which operates with only one power amplifier, uses two simultaneously excited modes to drive the rotor; a longitudinal mode and a flexural mode. The equations of motion describing the vibrations and contact behavior are derived by Hamilton's principle and the geometry constraint. The Lagrange multiplier method is used to treat the frictional contact problem. The finite element method and numerical integration scheme are used to simulate the dynamic responses of this system with and without contact. Some important factors are studied for the bimodal ultrasonic motor design. The factors include structure design, amplitude of input voltage, phase displacement, exciting frequency, and contact behavior.

An improved analysis for the bipolar linear transconductor

An improved analysis for the bipolar linear transconductor, assuming a finite value for the transistor current-gain β, is presented. A new expression for the normalized input-voltage as a function of the normalized output-current is obtained. A Fourier-series model is presented for this current-voltage relationship. Closed-form expressions are also derived for the harmonic and intermodulation components resulting from exciting the bipolar linear transconductor by a multisinusoidal input voltage. These expressions can be used to predict the limiting values of the input voltage amplitudes for a prescribed tolerable distortion percentage.

Analysis, design and implementation of the space-vector modulator for forced-commutated cycloconvertors

Novel research results on control of forced-commutated cycloconvertors (FCCs)with matrix topology are summarised. The space-vector-modulation (SVM) technique for control of the 3-phase/3-phase matrix convertor is presented. The SVM technique provides FCC output voltages of any frequency, from zero to a maximum value constrained by the switching frequency, and any amplitude, up to √(3)/2 of the input voltage amplitude, without low-frequency harmonics. Time-domain-simulation results and spectral analysis of the output voltages and input currents are shown. The space-vector modulator is digitally implemented in a microprocessor system with reduced real-time computation. The switching times are precalculated offline and the results are stored in EPROMs. A multistepped switching procedure for safe control of the matrix-convertor switches is also presented. The safe-control algorithm is implemented with a sequential circuit by using a PROM lookup table. The FCC space-vector modulator is experimentally verified.

Class E low dv/dt synchronous rectifier with controlled duty ratio and output voltage

A class-E high-frequency low-dv/dt synchronous rectifier/DC regulator is analyzed. The circuit is derived from a class-E rectifier by replacing a diode with a controllable switch. It can then both rectify and regulate the rectified output against variations in DC load and amplitude of the AC input voltage. The switch consists of a transistor and an antiparallel diode or a series diode. The DC output voltage of the rectifier is regulated by varying the ON duty ratio of the switch. The AC input voltage can be at a constant or varying frequency. The controllable switch turns on and off at zero voltage with low dv/dt, reducing switching losses, stresses, and noise. Equations governing the circuit operation are derived. Experimental results at 0.5 MHz were in good agreement with the theoretical predictions. The rectifier can be used in high-frequency-power-density multiple-output power supplies, all of whose outputs are regulated. The frequency need not be varied to regulate the DC output.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

DYNAMIC CALIBRATION METHODS FOR TRANSDUCER INSTRUMENTATION

Both DC and AC measurement bridges should be calibrated for dynamic use. This paper has described methods of calibration for both types and has shown how the equipment requirement may be kept to a minimum while maintaining the accuracy of the calibration. Methods of measurement of the input and output voltage amplitudes are also suggested.

Research note On the nonlinear performance of a current follower

Abstract The nonlinear behaviour of the input stage of the follower proposed by DeJager and Smit is analysed. Closed-form expressions are obtained for the harmonic components of the input current resulting from exciting the current follower by a single-sinusoid. These expressions can be used to predict the limiting values of the input voltage amplitude for a prespecified tolerable distortion percentage.

Linear charge injection to charge-coupled devices using capacitive metering

The input circuit of a charge-coupled device has the form of an m.o.s.f.e.t. Linear charge injection has been achieved by the negative feedback caused by a capacitor connected in series with the equivalent source electrode. The capacitor charge is reset between each sampling event. The distortion is similar to that obtained with fill-and-spill techniques, and the input voltage amplitude is more convenient.

Beam Phase Lock Using Amplitude Limited Pulse Comparison for the Zero Gradient Synchrotron (ZGS)

Solid state high frequency limiter amplifiers and fast rise time voltage comparators for pulse shaping make zero crossing time a meaningful phase reference. A circuit based on these principles was developed and is in use in the beam phase feedback loop of the ZGS. It has excellent linearity for voltage out vs delay for up to 50° with a phase error of < 8° for the following input condition: input voltage amplitude from 0.1 - 2.0 V and beam bunch rate from 4.4 - 14.0 MHz. A detector is included to insure a zero output reference when there is no beam or when beam levels are below the phase-lock threshold.

A highly efficient inductorless voltage regulator

This versatile and highly efficient voltage regulator, for applications where the conventional series regulator and the inductor type of switching regulator are impractical, uses solid-state switching techniques. Efficiencies greater than 90 percent have been achieved, independent of input voltage amplitudes. Good load regulation is provided, with a ripple increase as the main effect of a load-current increase. High-peak-current capability is another major advantage of the regulator. The circuit described successfully delivers power peaks of 600 watts. Output voltage restoration from the power line is accomplished as quickly as possible. Some applications of the regulator are prereugulation, class-B audio amplifiers, and solenoid driving.