2525 results about "Capacitance voltage" patented technology

A system master unit is connected to a 24V AC power source. One or more slave units is connected to the master unit by a power/communication line. Bulk capacitance in the master and slave units stores power during a power source positive half cycle. When the source voltage is higher than the bulk capacitance voltages, power is delivered to the loads, during which time communication cannot take place over the power/communication line. During the power source negative half cycle, the power/communication line is disconnected from the AC power source and is then used for communication between the master and slave units. System power is delivered from the energy stored in the bulk capacitance.

A shield electrode is provided in parallel with a sensor electrode. A detecting circuit detects a capacitance formed thereby around the sensor electrode. A capacitance-voltage conversion circuit converts the capacitance into a voltage by repeating a predetermined sequence. A shield electrode drive unit switches an electric state of the shield electrode in synchronization with the predetermined sequence. The shield electrode drive unit switches an electric state of the shield electrode in accordance with an electric state of the sensor electrode.

Disclosed are systems and methods which provide voltage conversion in increments less than integer multiples of a power supply (e.g., battery) voltage. A representative embodiment provides power supply voltage multipliers in a binary ladder distribution to provide a desired number of output voltage steps using a relatively uncomplicated circuit design. By using different sources in various combinations and/or by “stacking” different sources in various ways, the voltage multiplier circuit may be used to provide desired voltages. In order to minimize the number of components used in a voltage converter of an embodiment, a capacitive voltage converter circuit uses one or more storage capacitors in place of pump capacitors in a voltage generation cycle. Also, certain embodiments do not operate to generate an output voltage until the time that voltage is needed.

The invention discloses a control circuit for a voltage dropping type power factor corrector, which is used for controlling a voltage dropping converter to realize the power factor correction function. Inductance current critical intermittent control of changed on-time is performed on a Buck circuit through the control circuit to ensure that the on-time of a switching tube rises in the power frequency period along with increase of input voltage; and the critical intermittent working mode of inductance current in the Buck circuit is controlled, and when the inductance current is greater than zero, the junction capacitance of the switching tube and inductance are resonated, and the switching tube is connected when the voltage resonance of the junction capacitance reaches the volley bottom. The control circuit for the voltage dropping type power factor corrector has the characteristics of ensuring high power factors in the whole input voltage range, and meeting the harmonic requirements of IEC 61000-3-2 Class C, Class D, along with high efficiency.

An energy harvesting circuit harvests energy from a voltage source and charges a storage element with the harvested energy. The energy harvesting circuit includes an energy source, a storage capacitor to store energy output from the energy source, a power converter circuit, an energy storage element, and an enabling circuit. The enabling circuit turns the boost converter circuit on and off according to a monitored capacitance voltage of the storage capacitor. When the boost converter circuit is turned off, the storage capacitor accumulates energy output from the energy source until a reference voltage is reached, whereupon the boost converter circuit is turned on, enabling current flow from the storage capacitor to the storage element. When the storage capacitor discharges to a minimum voltage level, the boost converter circuit is turned off. The enabling circuit and a reference voltage supply are powered by the energy source.

The invention discloses an optimal pressure equalizing control method of a modular multilevel converter type direct current transmission system. By setting an upper limit and a lower limit on voltage, the pressure equalizing control is mainly carried out on submodules with out-of-limit capacitor voltage, and capacitor voltage sequencing for submodules with no out-of-limit capacitor voltage is processed by combing the charging/discharging conditions of bridge arm current so as to increase the probability of maintaining an original switching state for the submodules with no out-of-limit capacitor voltage when the next action is in triggering control and lower the switching frequency of devices. The introduction of the pressure equalizing control can not lower the working frequency of triggering control and the tracking speed of a converter by using submodule capacitor voltage sequencing and triggering control to work at different frequencies. The optimal pressure equalizing control method of the invention can greatly lower the switching frequency of the devices on the premise of having no obvious increment on submodule capacitor voltage fluctuation.

The invention discloses a robust dicyclic photovoltaic grid-connected control method based on power feedforward, which mainly comprises three parts: proportion integration (PI) control of exocyclic voltage, dead-beat control of endocyclic robust predictive current and power feedforward control, wherein the exocyclic PI control of the voltage is used for stabilizing the capacitive voltage of a direct-current side; the dead-beat control of the endocyclic robust predictive current is used for carrying out linear prediction on the voltage of a power grid at a next control period and carrying out non-linear prediction on grid-connected current by advanced control so as to obtain the command value of the grid-connected current at the next period; and then, PWM (pulse-width modulation) and grid-connected control are realized by the dead-beat control. According to the robust dicyclic photovoltaic grid-connected control method based on the power feedforward, a photovoltaic grid-connected inverter has higher robustness, wider stability margin and quicker dynamic response, and the requirement of grid-connected running of an inverter is better met.

The invention belongs to the power transmission and distribution field, and specifically relates to a pulse width control method of a modular multilevel converter. The method is characterized by determining the switched number of submodules at any time by carrier phase-shifting and then determining switching of the specific submodules by capacitance-voltage balance control, and comprising the steps of carrier comparison, signal acquisition, signal processing, PWM pulse signal generation and the like. The pulse width control method is simple, scientific and reasonable and easy for engineering realization, and has good dynamic property, thus being applicable to occasions with wider range of frequency variation in an AC system and free from restriction of the level number.

A purpose of the present invention is disclosing a flyback type miniature photovoltaic grid connected inverter with a power decoupling circuit and a control method thereof. The inverter comprises a flyback converter and a power frequency polarity conversion circuit. The flyback converter is provided with a power decoupling circuit, a decoupling capacitance voltage grade is higher than output voltage of a solar energy photovoltaic array, decoupling capacitance voltage is allowed to fluctuate in a large range, thus decoupling capacitance capacity is decreased, power decoupling can be realized by only using a non-electrolytic capacitor, using an electrolytic capacitor is avoided, a service life of the miniature photovoltaic grid connected inverter is prolonged, and reliability is raised. Through the control method, not only is decoupling of miniature photovoltaic grid connected inverter output power and solar energy photovoltaic array output power realized, but also direct current voltage and current waveform outputted by the solar energy photovoltaic array can maintain smooth, a service life of the solar energy photovoltaic array is guaranteed, and realization of maximum power point tracking (MPPT) is facilitated.

The invention provides an electronic power transformer based on a multi-media card (MMC). The electronic power transformer based on the MMC comprises the MMC and a direct current-direct current (DC-DC) isolator. The MMC comprises a plurality of sub-modules which are connected in series, the direct current output side and the direct current input side of the DC-DC isolator are respectively connected with capacitors in parallel, the direct current output side of the DC-DC isolator is connected with a low voltage direct current power grid, the direct current input side of the DC-DC isolator is connected with the direct current output ends of the sub-modules, and each sub-module comprises a half-bridge circuit and a capacitor, wherein the half-bridge circuits and the capacitors are connected in parallel. When direct current capacitor voltage of the MMC is unbalanced, the sub-modules with high capacitor voltage in the MMC charge the capacitors with low voltage to raise voltage values through the DC-DC isolator with the help of the low voltage direct current power grid and then through the DC-DC isolator again, stability of voltage on the direct current side is guaranteed, and therefore automatic balance of the direct current capacitor voltage of the MMC is achieved.

The invention relates to a sub-module circuit board used for a dynamic simulation test for simulating a high-capacity multi-level modular converter (MMC). A digital controller on the circuit board is used for controlling a plurality of MMC sub-modules of which parameters are reduced according to an exponential method, the sub-modules are connected in series. Each MMC sub-module comprises a main circuit an insulated gate bipolar transistor (IGBT) and silicon controlled rectifier driving circuit, a capacitance and voltage sampling circuit, a circuit board isolation power supply, a control and coding-decoding chip shared by a plurality of sub-modules, and a fiber channel, wherein the main circuit a capacitor, two IGBTs which are connected vertically in series and connected with the capacitor in parallel, a bypass switch connected with the lower IGBT in parallel, and a silicon controlled rectifier which is used for protecting the IGBTs and the capacitor and connected with the lower IGBT.

Dynamic range of a differential pixel is enhanced by injecting, synchronously or asynchronously, a fixed compensating offset (ΔV) into a differential signal capacitor whenever magnitude of the differential signal across the capacitor exceeds a predetermined value. The number (N) of ΔV offsets made is counted. Effective differential signal capacitor voltage V(t)=Vo+N·ΔV, where Vo is capacitor voltage. Differential pixel signal/noise ratio is increased by dynamically maximizing operational amplifier gain A_G for each differential pixel.

The invention relates to a modular multi-level converter capacitor voltage fluctuation inhibition method under a low-frequency working condition, and belongs to the technical field of power electronics and motor drive. The method comprises the following steps: the alternating-current side three-phase phase current which meets the low-frequency working need is obtained by performing closed-loop control on the modular multi-level converter alternating-current side three-phase phase current; loop current only contains a direct-current component and a high-frequency alternating-current component by closed-loop control of the three-phase loop current, and a bridge arm voltage contains a high-frequency zero sequence component by overlapping high-frequency voltage at the midpoint electric potential at the direct-current side; the amplitude values, the frequencies and the phases of the loop current high-frequency alternating-current component and the bridge arm voltage high-frequency zero sequence component are obtained by operation, so that the phase voltage and the phase current of the alternating-current side do not contain high-frequency harmonic waves, moreover, the cycles of charging and discharging submodules are shortened, and the effect of inhibiting the capacitor voltage vibration of the submodules is realized; the electrical quantity of each bridge arm is kept to be balanced by the balancing control on the bridge arm energy so as to guarantee that the modular multi-level converter runs symmetrically and stably.

A sulfur hexafluoride gaseous discharge micro component infrared detection device and method relates to a sulfur hexafluoride gaseous infrared absorption spectrum analysis device and method. The device of the invention mainly comprises an induction voltage regulator, a corona free experimental transformer, a non local discharge protective resistor, a standard capacitance voltage divider, a GIS analogue element, a non inductive resistance, a Fourier transform infrared spectrometer and a wideband high speed super capacity digital storage oscilloscope; wherein the gas tank in the Fourier transform infrared spectrometer is a long optical distance one. The method of the invention includes that discharge micro component detection is carried out on SF6 gas sample in GIS by utilizing the device ofthe invention. The invention can accurately detect various products produced by gas discharge decomposition of SF6 and has the characteristics of high detection precision, high spectrum resolution, good absorption peak symmetry, high signal to noise ratio and the like. The invention can be widely applicable to GIS equipment online running local discharge and provides reliable data for GIS equipment online running state analysis.

The invention relates to a circuit breaker and a realization method thereof, and specifically relates to a mixed high-voltage direct-current circuit breaker and a realization method thereof. The direct-current circuit breaker is based on the principle of secondary current transfer. A main branch is composed of a quick-action mechanical switch and a current transfer module which contains a full-controlled device, which ensures the advantages of low loss and flexible current transfer control in the state of normal conduction. A first current transfer branch is composed of half-controlled device thyristors connected in series, so that the circuit breaker has strong fault flow capacity and breaking capacity, 'zero voltage and zero current' of the mechanical switch can be maintained long enough, and arc-free switching of the mechanical switch is realized. A second current transfer branch is composed of capacitors with pre-charged voltage, an inductor, and series-connected thyristors. After the thyristors of the first current transfer branch are reliably switched off, the capacitors quickly build up direct voltage high enough to resist the system, and an energy absorption circuit limits the voltage of the capacitors. Thus, the size and cost of the capacitors are well controlled.

The invention relates to an energy transfer type power battery quick balancing system and a control method thereof. The invention relates to the battery voltage balancing system and further relates to the control method of battery pack quick balancing process, which solves the problem that a balanced battery single body and an energy storing element are impacted through pulse current by a currentbalancer in the prior art. The system comprises a power battery pack single body battery voltage and flying capacitor voltage detecting network, a current sensor and a signal modulating circuit, a single chip microcomputer, an electric power transfer channel, a first filter circuit, a two-way buck-boost converter, a second filter circuit and a flying capacitor. After starting to work, the system firstly detects the battery pack single body battery voltage, the flying capacitor voltage and the charging/discharging current; and if the dropout voltage between the highest voltage of the battery single body and the lowest voltage of the single body exceeds a set value, the balancing operation is started.

The invention provides a relaxation oscillator of which the linearity is significantly improved. The relaxation oscillator comprises an oscillating circuit, a reference level self-regulating circuit and a transmission gate selective signal generating circuit. Capacitor voltage overshoot caused by delay of a control circuit is worked out by detecting the voltage peak of charge and discharge capacitors in the oscillating circuit, and accordingly the reference level of comparators in the oscillating circuit is reduced by a corresponding quantity to serve as a new reference level so that the oscillation amplitude of the charge and discharge capacitors can be just a theoretical value. According to the high-linearity relaxation oscillator, when the new reference level is larger than zero, influence, brought by the capacitor voltage overshoot caused by delay of the control circuit, of the charge and discharge capacitors on output frequency is eliminated, and the linearity of a frequency-control circuit of the relaxation oscillator is significantly improved. The transmission gate selective signal generating circuit provides the initial reference level for the comparators by controlling transmission gates and transmits the new reference level to the reverse phase ends of the comparators when the new reference level is generated, and therefore the initial reference level can be isolated from the reverse phase ends of the comparators.

Capacitive voltage multiplier for generating voltage pulses, preferably up to 100 V, that are higher than the supply voltage for displays, non-volatile memories and corresponding units especially in small electronic devices, such as handheld telecommunication terminals or corresponding devices, wherein the multiplier comprises a switching capacitor circuit (21) provided with capacitors and switches for charging the capacitors in parallel and discharging them in series in order to deliver a high voltage pulse. The multiplier further comprises a diode chain circuit (22) consisting of a diode-chain and pumping capacitors for delivering high voltage current. The inventive system allows the output high voltage to be switched on and held with little longtime drop and with small switching losses and able to supply a load current without significant ripple. Additionally switching the high voltage on and off does not result in efficiency loss.

The invention provides an online monitoring method for a DC-link capacitor of a three-phase system. The method comprises that voltage of the DC-link capacitor is collected, and a voltage drop curve of the DC-link capacitor is obtained; three-phase output current is collected, and capacitive current is reconstructed according to the three-phase output current; and the capacitance (C) and equivalent serial resistance (ESR) of the DC-link capacitor are obtained according to the voltage drop curve and the capacitive current of the DC-link capacitor. The voltage drop curve and the three-phase output current of the DC-link capacitor as well as control signals of a semiconductor switch are monitored in the process that power equipment as a three-phase frequency converter is switched off, so that the C and ESR of the DC-link capacitor are calculated accurately, and non-invasive online monitoring for the DC-link capacitor of the AC/DC/AC system is realized. The method can be applied to online monitoring for an aluminum electrolytic capacitor, other capacitors as a film capacitor as well as other three-phase systems including a wind power converter, a photovoltaic AC/DC/AC system and a three-phase aviation power system.

The invention relates to the technical field of photovoltaic grid-connected inverters, particularly to a method for detecting the failure of relays and protecting filter capacitors of photovoltaic grid-connected inverters. The method comprises the following steps: before the relays are closed, if the difference of the absolute values of the effective value (Vinv) of one-phase or multi-phase inversion voltage and the effective value (Vgrid) of the same-phase grid voltage is detected to be smaller than the failure voltage threshold (delta V) of the relays, namely the absolute value of(Vinv-Vgrid)is smaller than delta v, judging that the relays in the phase are adhered, otherwise, judging that the relays are normal; similarly, after the detection of the relays on closed inversion sides, the detection of the relays on closed grid sides, and the closed detection of the relays on both sides are successively performed by the same method, if the relays have no failures in every step, grid connection is allowed, if any relay has a failure, machines are stopped, and grid connection is denied. According to the method disclosed by the invention, when every relay is accurately detected to have a failure or not, the filter capacitor voltage output by the inverters is processed, so that the possibility that at the moment of grid connection of the inverters, the grids generate current impact on the filter capacitors is eliminated, the system stability of the inverters is improved, and the service life of the filter capacitors is prolonged.