Sine wave

About: Sine wave is a research topic. Over the lifetime, 12183 publications have been published within this topic receiving 93013 citations. The topic is also known as: sinusoid.

Self oscillation circuits

Abstract: An object of the present invention is to provide a small size output transformer capable of producing sine wave oscillation at stability and high efficiency. A drive circuit including a switching circuit is connected to DC power source input units 12 a , 12 b , and an output transformer 10 is connected to the drive circuit. At the drive circuit, the switching circuit is turned on and off on the basis of a feedback signal of the primary side resonance voltage induced in the input side primary winding of the output transformer. The energizing direction of the DC power source to the output transformer is converted in clockwise and counter-clockwise direction by the on and off of the switching circuit, and the power source is applied as the AC signal to the input side primary winding of the output transformer. The phase detecting means detects the phase of the resonance waveform at the primary side of the output transformer 10 and outputs the phase signal. The control circuit connected to the drive circuit converts the signal of the phase detecting means to two phase signals of mutually reversal phases and outputs the drive signal for the on-off control of the switching circuit of the drive circuit.

Streamer polarity dependence of NOx removal by dielectric barrier discharge with a multipoint-to-plane geometry

Abstract: In this paper, we experimentally investigated an effect of streamer polarity on the reduction of NOx by using a barrier discharge plasma reactor with a multipoint-to-plane geometry. A high-frequency sine wave voltage generator and a repetitive pulse generator, which generated narrow and high-voltage pulses were used to remove nitrogen oxide (NOx). By the optical spectrum measurement, it is clarified that electrons with high energy, more than 10 eV, are produced in the discharge region at atmospheric pressure. The intensity ratio of the first negative system of N2+ (391.4 nm, threshold energy 18 eV) to the second positive system of N2 (337.1 nm, threshold energy 11 eV) neither depends on the applied voltage nor the frequency, but it depends on streamer polarity. Further, it is shown that the value is higher in a positive streamer than in a negative streamer. The use of a multipoint-to-plane electrodes caused the streamer polarity interchange every half cycle of the sine wave of the applied voltage, while in a case of the parallel plane electrodes, the positive streamer was only generated in the discharge region. The simulated gas and the exhaust gas from a diesel engine generator were used to confirm the NOx removal performance of the reactor.

Electric control apparatus for brushless motor

Abstract: A control apparatus for controlling an output torque of a brushless electric motor based on a torque command signal received from a torque command signal generator. The control apparatus includes magnetic pole position sensors for producing position signals indicative of a rotational position of a rotor of the motor. A counter outputs an address signal based on the position signals. A sine wave memory, which stores plural sine waves, outputs a sine wave signal based on the address signal. Then the amplitude of the sine wave signal is linearly controlled based on the torque command signal, and stator current is applied to stator windings of the motor based on the linearly controlled sine wave signal.

A Novel Control Technique for Grid-Tied Inverters Considering Unbalanced Grid Voltage Conditions and Control Input Saturation

Abstract: This paper presents a new method to design a current controller for grid-tied inverters under both balanced and unbalanced grid voltage conditions. The proposed controller consists of combining a feedback-output controller with a disturbance observer (DO). The control design is carried out in the $\alpha \beta$ reference frame. Thus, the objective of the composite controller is to ensure that the output of the system tracks a sinusoidal reference signal with zero steady-state error. A feedback controller only cannot achieve a good tracking performance because of the presence of model uncertainties and unknown disturbances. To account for the natural mismatch between the actual system and the mathematical model, the system dynamics are first augmented with an additional state-variable, representing the disturbance, and the feedback controller is designed based on the assumption that the disturbance input is available for feedback. Then, an observer is constructed to estimate the disturbance, which is assumed to be a sine wave oscillating at the grid frequency. Another feature of the DO is its ability to compensate for the effect of the saturation blocks required to limit the control input during transients, leading to improved dynamic performance. Several experimental tests were conducted to verify the effectiveness of the proposed controller, and the results demonstrated its capability to achieve accurate fast stable responses.

Forced oscillations of a separated shear layer with application to cavity flow‐tone effects

Abstract: Wave boundary conditions near the point of separation at a sharp edge are carefully examined, with new insights being derived for some common flow‐tone situations. Application of the continuity of velocity principle enables the amplitude and phase of the instability wave to be related to the acoustic driving wave phasor. Likewise, continuity of shear stress leads to a mathematical dependence of shear layer dynamics on upstream wall boundary layer parameters. Some surprising results: (1) An instability wave driven near the point of separation is found to move initially at half the velocity expected from linear theory. (2) Although resonator‐controlled flow tones operate at levels above the nonlinear saturation point for shear layer instability, they can exist only for shear layers that would otherwise be highly unstable. Some longstanding mysteries cleared up: (1) Why unflanged resonators (e.g., coke bottles) resist excitation by flow at grazing incidence. (2) Why flow‐tone spectra are nearly pure sine waves, even for multimode cavity systems.