556 results about "Reservoir capacitor" patented technology

An electrosurgical generator for supplying RF power to an electrosurgical instrument for cutting or vaporising tissue has an RF output stage (42) with an RF power bridge (Q1, Q2, Q3, Q4), a pair of output lines (74) and a series-resonant output network (48). The output impedance of the output stage (42) at the output lines (74) is less than 200/√P ohms, where P is the maximum continuous RF output power of the generator. The generator offers improved cutting and vaporising performance, especially in relation to the reliability with which an arc can be struck when presented with an initial low impedance load. Overloading of the output stage is prevented by rapidly operating protection circuitry responsive to a predetermined electrical condition such as a substantial short-circuit across the output lines. In the preferred embodiment, the output stage is capable of maintaining output pulses at least 1kW peak by supplying the power bridge from a large reservoir capacitor (60). Pulsing is dynamically variable in response to load conditions by controlling the maximum energy per pulse in response to the reservoir capacitor voltage.

This invention generally relates to a bootstrap circuit for a switch mode power supply, a controller for a switch mode voltage converter, a switch mode flyback converter comprising the bootstrap circuit, a switch mode forward converter comprising the bootstrap circuit, and a method of bootstrapping a switch mode power converter. The bootstrap circuit comprises: a current bleed impedance (Rht1) to bleed current from an input power supply (VH+); circuitry to deliver current from the input power supply (VH+) via the current bleed impedance (Rht1) to the base of a power switch (Q1) such that the power switch (Q1) is operable to amplify the current delivered from the internal power supply; a passive circuit (Dst) to provide the amplified current to a reservoir capacitor (Cdd); and the passive circuit element (Dst) further to substantially block reverse current flow from the supply input (Vdd) to the emitter of the power switch (Q1).

A single-stage input-current-shaping (S<2>ICS) flyback converter achieves substantially reduced conduction losses in the primary side of the S<2>ICS flyback converter by connecting a bypass diode between the positive terminal of a full-bridge rectifier and the positive terminal of an energy-storage capacitor. An effective current interleaving between an energy-storage inductor and the bypass diode is thus obtained in the S<2>ICS flyback converter around the peak of the rectified line voltage, resulting in a significantly reduced input-current ripple and reduced current stress on the switch. Further, by rearranging the rectifiers in the ICS part of the S<2>ICS flyback converter in such a way that the energy-storage capacitor and the ICS inductor are connected to the ac line voltage through only two rectifiers, one diode forward-voltage drop is eliminated, which results in a substantially reduced conduction loss in the primary-side rectifiers.

In a pulsed laser diode driver an energy storage capacitor is continuously being charged to a supply voltage Vr. When a pulse is initiated, energy stored in the capacitor is delivered to the laser diode load. The capacitor voltage Vd at the end of a pulse is used to control Vr to ensure that Vd is maintained above a minimum voltage Vm required to ensure operation of a current control device (such as FET) just above saturation. Test pulses (such as with attenuated currents or reduced pulsewidth) may be fired to determine an initial optimum value for Vr. After a test pulse, a slightly high estimate for Vr may be used and may be iterated (incremented) down to an optimum value Vm during a firing burst. A digital processor may be used to calculate and store data to optimize the performance. Various embodiments are disclosed.

An AC to DC power converter with hold up time function has a charging switch and a mode switch. The charging switch is connected between an output capacitor of a PFC controlling circuit and an energy-storage capacitor. The mode switch is connected between the energy-storage capacitor and an input of the PFC controlling circuit. The charging and mode switches are controlled by a PFC controller. When AC power is normal, the charging switch turns on and mode switch turns off. Meanwhile, the energy-storage capacitor and the output capacitor are connected in parallel to store energy in the energy-storage capacitor. When the AC power source is interrupted, the charging switch turns off and mode switch turns on. Therefore, the energy-storage capacitor is disconnected from the output capacitor. The PFC circuit obtains power from the energy-storage capacitor and continuous to supply an output voltage for a while.

An electrosurgical generator for supplying RF power to an electrosurgical instrument for cutting or vaporising tissue has an RF output stage with RF output devices, a series-resonant output network and an RF output. The generator offers improved cutting and vaporising performance, especially in relation to the reliability with which an arc can be struck when presented with an initial load impedance load. This is achieved by virtue of the output stage being capable of maintaining output pulses of at least 1 kW peak by supplying the RF output devices from a large reservoir capacitor. An appropriate combination of cutting performance and haemostasis is provided by allowing for pulsed or continuous wave operation once an arc has been established, according to whether or not a surplus energy condition exists, as indicated by the voltage across the reservoir capacitor.

A variable voltage electronic pet training apparatus. The variable voltage electronic pet training apparatus controls the intensity of the stimulation by the controlling the voltage level present at the primary side of the transformer while maintaining a fixed signal to the correction pulse switch. A trigger signal contains information about the desired stimulus intensity level. A controller interprets the trigger signal and produces a voltage control signal associated with the desired energy level. Application of the voltage control signal to a power converter keeps the voltage level applied to an energy storage capacitor sufficient to produce the desired stimulation intensity.

Examples of the present invention include high electric energy density polymer film capacitors with high dielectric constant, low dielectric dissipation tangent, and low leakage current in a broad temperature range. More particularly, examples include a polymer film capacitor in which the dielectric layer comprise a copolymer of a first monomer (such as tetrafluoroethylene) and a second polar monomer. The second monomer component may be selected from vinylidene fluoride, trifluoroethylene or their mixtures, and optionally other monomers may be included to adjust the mechanical performance. The capacitors can be made by winding metallized films, plain films with metal foils, or hybrid construction where the films comprise the new compositions. The capacitors can be used in DC bus capacitors and energy storage capacitors in pulsed power systems.

A high voltage pulse generator utilizes an even number of Marx cells using L-C inversion topology. Each Marx cell is associated with an individual inverter transformer having a primary winding connected to the output of an ac power supply such as a series resonant inverter. The secondary of each inverter transformer is half-wave rectified to charge the energy storage capacitors in each Marx cell. A distributed voltage sensing scheme can be provided for accurate feedback to the inverter's controller. An inductive element can be used to achieve a magnetic diode effect in the L-C inversion circuit to reduce component stress and improve efficiency. A transformer-coupled floating gate drive circuit is used to provide local power conditioning and trigger timing for discharge of the energy storage capacitors.

A hybrid battery power source for implantable medical use provides relatively stable resistance during discharge and avoids the voltage delays that develop as a result of variable resistance increase in Li/SVO cells. The hybrid battery power source utilizes two batteries or cells, one being a primary battery of relatively high energy density and the other being a rechargeable secondary battery of low relatively stable internal resistance. The primary and secondary batteries are connected in a parallel arrangement, preferably via an intermediate voltage boost circuit having an inductor and a pulse generating control circuit therein. The energy storage capacitors of the medical device in which the hybrid battery power source is situated are driven in whole or substantial part by the secondary battery. The primary battery is used to as an energy source for recharging the secondary battery. By arranging the two batteries in parallel, with one serving as a primary battery and the other as a rechargeable secondary battery, all the benefits of the defibrillatory impulse will be obtained and the deficiencies arising from variable voltage delay found in prior art implantable power sources will not be present.

An active power filter comprises an energy storage capacitor, an inverter, a filtering circuit and a controller. The inverter is controlled to act as a virtual resister at a fundamental frequency for compensating for the power loss of the active power filter, act as a virtual capacitor at a fundamental frequency for compensating for a fundamental reactive power of the load, and/or generate a harmonic current for suppressing the harmonic currents of specific orders of the load.

A load control device adapted to be coupled between an AC power source and an electrical load for controlling the power delivered to the load includes a power supply having an energy storage capacitor and a charge pump circuit adapted to conduct an input charging current through the load and to conduct an output charging current through the energy storage capacitor to thus generate a DC supply voltage across the energy storage capacitor, where the output charging current has a magnitude greater than the input charging current. The charge pump circuit includes a switched capacitor operable to charge through the load during a first half-cycle, and to discharge into the energy storage capacitor in a second, subsequent half-cycle. The charge pump circuit operates at line frequency and the magnitude of the input charging current is substantially small so as to avoid generating noise in a noise-sensitive circuit of the load control device.

An isolated boost converter includes first and second switches that are switched simultaneously, a transformer and an energy storage capacitor on the primary side of the transformer for storing energy received from input power source. In one embodiment, when the first and second switches are closed, the energy in the capacitor is transferred to the output load while a boost inductor is charged, and when the first and second switches are open, the boost inductor provides energy from the input voltage source to supply the load and to charge the capacitor, In one embodiment, a third switch is provided to relieve the voltage stress on the secondary side.

The invention discloses a high-power downhole electromagnetic pulse transmission device which comprises a ground instrument and a downhole instrument. The core of the ground instrument is an industrial personal computer and consists of a depth/magnetic mark/global position system (GPS) signal recording module, a Manchester coding and decoding module and a cable driving module; the depth/magnetic mark/GPS signal recording module and the Manchester coding and decoding module are connected with the industrial personal computer respectively through two serial ports; based on the principle of phantom power supply, the cable driving module is connected with the downhole instrument by a cable; the downhole instrument is sequentially provided with an alternating-current boost module, an energy-storage capacitor, a transmitting coil, a data acquisition module, a high-voltage discharging switch and a controller manipulated by a computer; and the ground instrument supplies power to the downhole instrument through the cable. By the high-power downhole electromagnetic pulse transmission device, magnetic field pulse excitation with instantaneous high power can be realized in a cased well, full time-interval data during transmitting wave forms and receiving signals in a well is recorded, and an observation system is provided for a downhole electromagnetic detection method which is used for evaluating and developing the distribution state of remaining oil in an oil storage layer.

A variable frequency oscillator (VFO) circuit having an increased frequency tuning range to selectively obtain operating frequencies above and below a set frequency. The circuit includes a tank inductor connected in parallel with a tank capacitor for primarily defining the set oscillating frequency of the VFO circuit. A switchable capacitor is included for selectively providing a predetermined step-wise decrease of the oscillating frequency to a frequency value below the set frequency of the circuit, and a varactor is included for accommodating selective tuning of the oscillating frequency within a range of frequency values below the set frequency. The inventive circuit selectively includes a switchable inductance element which is selectively electromagnetically coupled to the tank inductor to decrease the overall inductance value of the VFO circuit and, thereby, selectively increase the oscillating frequency above the set frequency value.

The present invention is a system, apparatus and method of a PFC rectifier having a programmable output voltage that does not incur a drastic penalty in the overall size or volume of the device, or a significant degradation in efficiency. The PFC rectifier of the present invention may incorporate a two-stage solution for output voltage regulation. The present invention provides a topology of a small-size/volume PFC rectifier with a variable (i.e. programmable) output voltage and a complementary control method. The two-stage system of the present invention incorporates a smaller and lower cost capacitor than the bulky size and costly energy storage capacitors required in conventional prior art. The present invention also achieves tight output regulation. The two-stage topology of the present invention further achieves on-line efficiency optimization and significantly reduces the volume of the downstream stage over the prior art examples through dynamic adjustment of the downstream stage supply voltage.

The invention discloses a high-repetition rate all-solid-state high-voltage pulse generator which comprises a direct current power supply, a resonance charging circuit, an energy storage capacitor, a step-up pulse transformer and a magnetic pulse compression switch circuit, wherein the direct current power supply is connected into the resonance charging circuit after being connected with a filter capacitor in parallel; the resonance charging circuit then is connected with the two ends of the filter capacitor after being connected with the energy storage capacitor; the two ends of a primary coil of the step-up pulse transformer are connected with the two ends of the energy storage capacitor; and a secondary coil of the step-up pulse transformer is connected into the magnetic pulse compression switch circuit. The invention has the beneficial effects that a high-pressure rapid pulse is generated by adopting a method of combining a power semiconductor switch with a magnetic pulse compression switch to replace a thyratron, is used for discharging and exciting a gas laser and can overcome the defects caused by the thyratron; and the running demands of an excimer laser at high repetition rate and long service life are satisfied.

A radar level gauge system comprising power management circuitry for regulating operating power to be used by a microwave unit and a processing circuitry of the radar level gauge system. The power management circuitry comprises a DC-DC converter having an input terminal connected to the interface, an output terminal connected to the microwave unit and the processing circuitry, and a reference terminal connected to an electrical reference point, wherein a first voltage level at the input terminal and a second voltage level at the output terminal relates to a reference voltage level at the electrical reference point. The power management circuitry further comprises an energy storage capacitor connected between the input and output terminals of the DC-DC converter. According to this design, the capacitance of the power management circuitry gets reduced due to that the capacitance is originating from a series capacitance.