433 results about "Capacitive voltage divider" patented technology

A voltage converter including a capacitive voltage divider combined with a buck converter and battery charger. The converter includes four capacitors, a switch circuit, an inductor and a controller. The capacitors form a capacitor loop between an input node and a reference node and include a fly capacitor controlled by the switch circuit, which is controlled by a PWM signal to half the input voltage to provide a first output voltage on a first output node, and to convert the first output voltage to the second output voltage via the inductor. The controller controls the PWM signal to regulate the second output voltage, and provides a voltage control signal to control the input voltage to maintain the first output node between a predetermined minimum and maximum battery voltage levels. A battery charge path is coupled to the reference node and battery charge mode depends upon the battery voltage.

A power conversion circuit senses an output voltage to detect shorted lamp conditions in a backlight system. The power conversion circuit can drive at least one fluorescent lamp. A voltage sensing feedback circuit, such as a capacitive voltage divider or a resistive voltage divider, senses the output voltage at an output of the power conversion circuit and generates a voltage feedback signal for a shorted lamp detector. The shorted lamp detector reliably detects a shorted lamp condition of one fluorescent lamp in a multi-lamp configuration or detects a short circuit condition of the output voltage line coupling the output voltage of the power conversion circuit to the fluorescent lamps.

A zero-voltage-switched, full-bridge, phase-shifted DC-DC converter for use in a DC power supply or battery charger includes a power transformer, four switching transistors connected to form a full bridge, and a decoupling capacitor and resonant inductor connected in series to the primary winding of the power transformer. At high loads, i.e., high output voltages, the resonant inductor charges the stray and internal capacitance of the switching transistors. Under light loads or in a no-load condition, with the current through the resonant inductor insufficient to allow the inductor to recharge these capacitances, the combination of a second inductor connected at one end to the central tap of the power transformer's primary winding and at its second opposed end to the middle point of a capacitive voltage divider, permits the second inductor to store enough energy to effectively recharge the stray and internal capacitance of the switching transistors for improved operating efficiency.

Techniques and corresponding circuitry are presented for the detection of wordline leakage in a memory array. In an exemplary embodiment, a capacitive voltage divider is used to translate the high voltage drop to low voltage drop that can be compared with a reference voltage to determine the voltage drop due to leakage. An on-chip self calibration method can help assure the accuracy of this technique for detecting leakage limit. In other embodiments, the current drawn by a reference array, where a high voltage is applied to the array with all wordlines non-selected, is compared to the current drawn by an array where the high voltage is applied and one or more selected wordlines. In these current based embodiments, the reference array can be a different array, or the same array as that one selected for testing.

A voltage converter including a buck converter and a capacitive voltage divider. The converter includes four capacitors, a switch circuit, an inductor and a controller. A first capacitor is coupled between a reference node and a first output node which develops a first output voltage. A second capacitor is coupled between an input node and either the reference node or the first output node. The switch circuit couples a third capacitor between the reference and first output nodes in a first state of a PWM signal, and couples the third capacitor between the first output and input nodes in a second PWM signal state. The inductor is coupled to the third capacitor and provides a second output node coupled to the fourth capacitor providing a second output voltage. The controller controls the duty cycle of the PWM signal to regulate the second output voltage to a predetermined level.

The invention relates to an infrared photoacoustic spectroscopy detection device and method for decomposed components of sulfur hexafluoride under partial discharge, belonging to the technical field of partial discharge on-line monitoring of SF6 gas insulating electrical equipment. The device of the invention mainly comprises an induction voltage regulator, a corona free experimental transformer, a partial discharge free protective resistor, a standard capacitive voltage divider, a non-inductive resistor, a GIS analog element, a wide-frequency high-speed ultrahigh-capacity digital storage oscillograph and an infrared photoacoustic spectroscopy system. In the method of the invention, infrared photoacoustic spectroscopy detection is carried out on the decomposed gas of SF6 under partial discharge in the GIS analog element by the device of the invention. The invention has high sensitivity, little gas consumption, multiple detection components and strong anti-jamming capability, can effectively detect SF6, CF4, SO2F2, SOF2, SO2, HF and the like as low as 0.01 muL/L, and is suitable for on-line detection. The invention can be widely used for detection of partial discharge decomposed gas of SF6 in the SF6 gas insulating electrical equipment, especially the GIS equipment.

The present invention relates to structures and methods that reduce ESD damage to electronic devices. In an embodiment, the structure is a parallel plate dissipative capacitor formed by sandwiching a dissipative dielectric layer between two conductive layers in series to the electronic device. The dissipative dielectric layer includes a nonconductive dielectric doped with a voltage dependent resistive material that defines a conductive threshold voltage. The structure functions as a voltage dependent resistor in response to an applied voltage such as an ESD surge voltage exceeding the defined conductive threshold voltage and dissipates the applied voltage into thermal energy before it can reach the electronic device and cause damage. The dissipative dielectric layer restores to a dielectric and the structure functions as a capacitor when the excess voltage is depleted that is drops below the defined conductive threshold voltage. In another embodiment, the structure is a parallel plate dissipative capacitors in series that enhances ESD mitigation through a capacitive voltage divider structure. The structures can be used in EMI/RFI shielding applications.

A light sensing cell comprising output means (T1, T2) for generating an output voltage depending on the voltage of a sensing node (2), the voltage of the sensing node varying as a function of a received light; a reset transistor (T3) operable to force the voltage of the sensing node (2) to a reset voltage; a feedback loop comprising an operational amplifier (A1) operable to add through a capacitive voltage divider (C3, C4) a correction voltage to the voltage of the sensing node (2), said correction voltage depending on the output voltage; and preset means (T5) for, during the operation of the reset transistor (T3) and until the amplifier (A1) is operated, setting the input of the capacitive voltage divider (C3, C4) to a predetermined voltage (Vinit).

A power supply comprises a pair of first and second capacitors forming a capacitive voltage divider. A source of a periodic input supply voltage is coupled to the capacitive voltage divider for producing in the second capacitor, from a portion of the periodic input supply voltage, a second supply voltage that is coupled to a load circuit. A switch is coupled to the second capacitor for selectively coupling the first capacitor to the second capacitor in a manner to regulate the second supply voltage.

Disclosed are apparatus and methodology for providing a capacitive voltage divider configured to reduce a relatively high level alternating current (AC) to a lower level direct current (DC). The apparatus provides a series of capacitors and diodes configured for series charging of the capacitors and parallel discharge thereof by way of a single switching element. In operation, the capacitor series is charged during the negative half cycle of the AC source and then discharged during the positive half cycle thereof.

A high-voltage power cable nondestructive detection device is used for detecting defects of power cables and comprises an alternating current withstand voltage testing system and a partial discharge testing system. The alternating current withstand voltage testing system comprises a power supply, a high voltage reactor and a voltage divider which are serially connected to form a loop. During testing, the end or a middle joint of a cable to be tested is connected into a high frequency wave trapper, a capacitive voltage divider, a high frequency current transformer and a partial discharge tester, and long-distance and large-capacity cable testing requirements can be met by arranging the high voltage reactor; and the high frequency wave trapper can restrain high frequency interference of the power supply side, the high frequency current transformer can sense pulses and form partial discharge signals on the partial discharge tester, and whether the cable has hidden defects can be judged by comparing the obtained partial discharge signals and standard partial discharge signals.

Drive and startup circuits are described particularly suitable for use with a switched capacitor divider. In one example, a drive circuit has a level shifter coupled to a gate of each switch of a switched capacitor drive circuit to couple alternating current into the respective gate, a positive phase low side driver coupled to each level shifter to drive the gates of the top switch path through the respective level shifters, and a negative phase low side driver coupled to each level shifter to drive gates of the bottom switch path through the respective level shifters. A startup circuit, such as a capacitive soft start circuit may be used to slow the application of the current to each switch.

The invention discloses a capacitive voltage-division type self-calibration optical voltage transducer, which is used for solving the problem that the existing capacitive voltage-division type optical voltage transducer generates measurement accuracy temperature drift under the influence of temperature and is poor in interference rejection. The capacitive voltage-division type self-calibration optical voltage transducer comprises a capacitive voltage divider, a base and an optical voltage sensor, the capacitive voltage divider comprises a high-voltage capacitor, a low-voltage capacitor, a signal output terminal and a grounding terminal; the optical voltage sensor comprises an optical voltage sensing unit, and further comprises a signal processing unit; and the signal processing unit comprises a photoelectric conversion module, an anti-aliasing filter, a band-pass filter, an amplifier, an A/D (analogue/digital) conversion module, a DSP (Digital Signal Processor),a D/A conversion module, an amplifying module, an overvoltage protection module, an LED (Light-Emitting Diode) light source, a power conversion module, a combining unit and a direct current power module, and further comprises a photoelectric hybrid connector module. The capacitive voltage-division type self-calibration optical voltage transducer is used for voltage measurement in an electric power system.

The invention relates to a capacitor voltage transformer suitable for high-voltage harmonic measurement and a measurement method. The capacitor voltage transformer is characterized in that a current transformer is respectively connected into a low-voltage capacitance branch and an intermediate transformer branch of a capacitive voltage divider of the capacitor voltage transformer in series, two conventional current transformers are additionally arranged in a conventional capacitor voltage transformer, and the size and the phase position of harmonic voltage of a high-voltage system can be worked out by using electric currents measured by the two current transformers. Therefore, the capacitor voltage transformer has the advantages of being simple in structure and convenient to realize, having high measurement accuracy of voltage harmonics, being free of influence of the size of a load of the capacitor voltage transformer and having very high application value and market promotion prospect in occasions where high-voltage harmonics are measured.

The invention discloses a system for testing a GIS electronic transformer based on a small connecting and disconnecting capacity current of a disconnecting switch. The system comprises a high-voltage testing transformer connected to a BSG sleeve, a capacitive voltage divider, a load capacitor arranged on the other BSG sleeve, the disconnecting switch arranged between the two sleeves, a calibration primary transient state testing system and the electronic transformer to be tested, one end of a secondary converter is connected with the electronic transformer to be tested, the other end of the secondary converter is connected with a merging unit, and the other end of the merging unit is connected with a fault recorder. When the disconnecting switch is connected or disconnected, voltage values and current values of a high-voltage bus are tested and compared with the output values of the electronic transformer to be tested. According to the testing system, the electromagnetic environment at the voltage levels of 110KV, 220KV, 500KV and the like in the process of electricity connection and electricity disconnection can be simulated, the site disconnecting switch connecting and disconnecting hollow conducting wire and capacity small current loading process is simulated, similar site transient sate strong-interference is generated, and the electromagnetic protective performance of the electronic transformer under the condition is examined.