Voltage regulator

About: Voltage regulator is a research topic. Over the lifetime, 33536 publications have been published within this topic receiving 350859 citations.

A study on voltage collapse mechanism in electric power systems

Abstract: A mechanism of the dynamic phenomenon of voltage collapse is presented from the physical point of view. It is shown that an iterative reaction of voltage drop between a dynamic load and the system network can cause voltage collapse. The dynamic phenomenon of voltage collapse is analyzed on a simple power system model which includes a synchronous motor. Dynamic equations describing the mechanism of voltage collapse caused by a very small disturbance are derived, and the physical explanation of the voltage collapse mechanism is presented in detail for the case when the system is operating near the bifurcation point and its linearized system matrix has a very small negative eigenvalue. It is shown that an iterative reaction of voltage drop between a dynamic load and the system network can cause voltage collapse. >

Step-up/down AC voltage regulator using transformer with tap changer and PWM AC chopper

Abstract: A step-up/down AC voltage regulator is proposed, in which a tap-changing transformer and a pulsewidth modulation (PWM) AC chopper are combined. The proposed regulator can step up or down the output voltage to input voltage. Also, the proposed regulator restrains more harmonics of output voltage compared to the conventional PWM regulator. The input current flows continuously in the proposed regulator, while it flows discontinuously in the conventional PWM regulator. Through digital simulation, several characteristics are investigated theoretically and then compared with those of conventional schemes. Practical verification of the theoretical predictions is presented to confirm the capabilities of the proposed regulator.

Standby power system

Abstract: The standby power system (20) provides backup power to a load, such as a computer system, when main AC line power fails. A system DC battery (30) voltage is converted to an AC output voltage signal at line voltage levels by a power conversion system including a high frequency push-pull inverter (56), a light-weight low-cost high frequency transformer (52), a rectifier (54), and a line frequency inverter (56). The high frequency inverter (56) is controlled to provide high frequency battery voltage pulse bursts separated by low frequency zero voltage dead times which are boosted by the transformer (52) to line voltage levels and rectified by the rectifier (54). The line frequency inverter (56) is controlled to provide the rectified line voltage level pulse bursts to the standby power system (20) output in the form of a stepped square wave output signal at line frequencies. The system controller (38) detects the occurrence of AC line faults using a single digital line sense signal. Since analog-to-digital conversion of the power system input and output voltage waveforms is not required for line fault detection (44) or output voltage control, the system controller (38) may be implemented using a low-cost microprocessor (38).

Primary-side regulated pulse width modulation controller with improved load regulation

Abstract: The present invention provides a primary-side regulated PWM controller with improved load regulation. In every PWM cycle, a built-in feedback voltage samples and holds a flyback voltage from the auxiliary winding of the transformer via a sampling switch and generates a feedback voltage accordingly. A bias current sink pulls a bias current that is proportional to the feedback voltage. Via a detection resistor, the bias current will produce a voltage drop to compensate the voltage drop of an output rectifying diode as the output load changes. According to the present invention, the bias current can enable the PWM controller to regulate the output voltage very precisely without using a secondary feedback circuit.

Reduced DC-Link Voltage Active Power Filter Using Modified PUC5 Converter

Abstract: In this letter, the five-level packed U-cell (PUC5) inverter is reconfigured with two identical dc links operating as an active power filter (APF). Generally, the peak voltage of an APF should be greater than the ac voltage at the point-of-common coupling (PCC) to ensure the boost operation of the converter in order to inject harmonic current into the system effectively; therefore, full compensation can be obtained. The proposed modified PUC5 (MPUC5) converter has two equally regulated separated dc links, which can operate at no load condition useful for APF application. Those divided dc terminals amplitudes are added at the input of the MPUC5 converter to generate a boosted voltage that is higher than the PCC voltage. Consequently, the reduced dc-links voltages are achieved since they do not individually need to be higher than the PCC voltage due to the mentioned fact that their summation has to be higher than PCC voltage. The voltage balancing unit is integrated into the modulation technique to be decoupled from the APF controller. The proposed APF is practically tested to validate its good dynamic performance in harmonic elimination, ac-side power factor correction, reactive power compensation, and power quality improvement.