624 results about "Dc capacitor" patented technology

A battery pack for an electronic device comprises battery cells, a battery charging circuit, and an energy receiving element adapted to receive power from a planar inductive charging system. The energy receiving element has an inductance and a capacitor is connected to the energy receiving element and forms a resonant tank therewith. A diode rectifier and a DC capacitor are connected to the energy receiving element to provide a rectified DC voltage that can be fed from the energy receiving element to said battery charging circuit. The energy receiving element may comprise a soft magnetic sheet with a coil wound around its edges, or a coil formed on a printed circuit board, or a combination of the two. The energy receiving element may be formed integrally with the battery pack, or may be provided as a separate component that can be added to an existing battery.

A method of balancing the voltage of DC links in a cascaded multi-level converter (CMC) semiconductor circuit, including the steps of providing a plurality of H-bridge converters per phase in the CMC circuit and utilizing a three phase duty cycle value from the main controller to determine a normalized duty cycle value, a ceiling duty cycle value and a floor duty cycle value. The normalized duty cycle value and an output current of the CMC is used to determine the direction and polarity of a capacitor current, and utilizing the capacitor current to determine a plurality of output capacitor voltages. A voltage summation result and direction is obtained from a ceiling index pointer and a floor index pointer and the voltage summation result, direction from the ceiling index pointer and a floor index pointer are used to create a combined switching table for the H-bridge converters. A pulse width modulator is utilized to balance the voltage of the DC links and thereby eliminate DC-capacitor voltage imbalance.

A power converter apparatus having a configuration of a plurality of unit cells, including a DC capacitor and semiconductor devices, connected in cascade, includes a variable voltage source that is connected with a DC link, and a unit having a function that initially charges up the DC capacitor in the unit cell alone selected at a time of an initial charge.

The invention relates to a current forecasting dead-beat control method of a Z source type interconnected inverter and a control device thereof, which belongs to the field of electrical energy conversion and is used for interconnected power generation. The current forecasting dead-beat control method overcomes the defect of sampling delay of the conventional control method. In each sampling period, a robust prediction algorithm is adopted to forecast interconnected current of the next period, and the needed inverted voltage is calculated according to a voltage equation of the inverter to realize the deadbeat control of the interconnected current. A single-voltage space vector modulating method with a through zero vector is used for generating a through-state pulse-width modulation wave shapes of the inverted voltage to control the DC capacitance voltage and the interconnected inverted voltage. The control device comprises a central processing unit, a synchronous signal generating circuit, a voltage and current testing circuit and an isolated driving circuit. The current forecasting dead-beat control method of the Z source type interconnected inverter has high control precision, is easy to digitally realize, has stronger inverted-side inductance parameter variation robustness, and the like.

In addition to the construction of a typical elevator control device in which power generated during regenerative operation is dissipated by a resistance chopper (18), an elevator control device is newly provided with: an electric double layer capacitor (21) connected in parallel with the DC capacitor (3) that smoothes the DC ripple of the rectifier circuit (2) that rectifies the AC power of the AC power source (1) and having an electrostatic capacitance that is considerably larger than this DC capacitor; a voltage detection circuit (22) that detects the terminal voltage of this electric double layer capacitor; and a drive control unit (5) that uses a voltage in the vicinity of the rated voltage of the electric double layer capacitor as the operating voltage of resistance chopper and, when the terminal voltage detected by a voltage detection circuit reaches the voltage in the vicinity of the rated voltage of the electric double layer capacitor, operates and controls the resistance chopper.

The adaptive superconductive magnetic energy storage (SMES) control method and system control a SMES device connected to a power generation system. A radial basis function neural network (RBFNN) connected to the controller adaptively adjusts gain constants of the controller. A processor executes an improved particle swarm optimization (IPSO) procedure to train the RBFNN from input-output training data created by the IPSO, and thereafter generate starting weights for the neural network. Tests carried out show that the proposed adaptive SMES controller maintains the DC capacitor voltage constant, thus improving the efficiency of wind energy transfer. The power output (reactive and real) of the SMES device improves the voltage profile following large voltage dips and provides added damping to the system.

The invention discloses an AC-DC hybrid micro grid bidirectional power converter virtual synchronization motor control method, and relates to the AC-DC hybrid micro grid virtual synchronization motorcontrol field; the bidirectional power converter is a three-phase voltage source type PWM converter formed by IGBT switch tubes; the AC side is connected to a AC bus via a LC filter and a line impedance Z ac; the DC side is connected to a DC bus via a DC capacitor Cdc and an line impedance Zdc; the energy bidirectional transmission can be realized respectively via a frequency control unit, a virtual excitation control unit and a bidirectional power transmission control unit; the AC frequency and DC voltage can be directly controlled so as to keep AC-DC subnet load balancing; throughput characteristics of various types of power supplies and loads of the AC-DC subnet can be fully utilized so as to provide inertia for the AC frequency and DC voltage, thus enabling the bidirectional power converter to present sagging characteristics under a stable state, and building a bidirectional power converter closed loop system small signal model so as to provide a key parameter design method.

The excitation overcurrent detection unit for the doubly-fed electric machine is provided with a function to determine an excitation current magnitude relationship among three phases. The firing pulse is held to on-state or off-state to cause the largest-current phase and the second-largest-current phase to charge the DC capacitor by the operation of diodes. The conduction ratio of the third-largest-current phase or minimum current phase is controlled according to the detected current value to protect against a possible short-circuit across the DC capacitor. When the voltage of the DC capacitor exceeds a preset value, the voltage is suppressed by operating active or passive power devices.

The invention discloses a capacitive charging DC breaker. The capacitive charging DC breaker comprises an auxiliary branch and a primary branch, which are connected with each other in parallel, wherein the auxiliary branch is formed by connecting a first mechanical switch and a power electronic device valve bank in series; and the primary branch is formed by connecting DC capacitors and a diode valve bank in series. A DC fault current is isolated through the charging effect of a DC to each DC capacitor during a DC fault period. A reclosing instruction is sent out only when the condition that a line side current of the DC breaker is higher than a threshold is detected in the reclosing process. The invention further discloses the DC breaker. The primary branch is formed by connecting multiple groups of DC capacitors which are connected with one another in series and the mechanical switches in parallel. The invention further discloses a control method for carrying out fast reclosing on the DC breaker correspondingly. The defect that inductance-capacitance oscillation is easily formed by the DC capacitors and line inductor of the existing DC breaker can be avoided; opening and closing of the DC fault current are stable and reliable; and fast reclosing can be achieved.

A sub-module for a modular multi-level converter, a converter comprising the sub-module, and an application thereof. The sub-module comprises a first switching module (1), a second switching module (2), a direct current capacitor (4), and a third switching module (3). The first switching module (1) and the second switching module (2) are connected in series, a negative end of the first switching module (1) is connected to a positive end of the second switching module (2), and the switching modules (1, 2, 3) are each formed by connecting a full-controlled device and a diode in an antiparallel mode. A positive electrode and a negative electrode of the direct current capacitor (4) are connected to a positive end of the first switching module (1) and a negative end of the second switching module (2). The third switching module (3) is electrically connected to the first switching module (1) and the second switching module (2), so that a full-controlled device of the third switching module (3) applies trigger pulse all the time during normal operation and is in a conducting state all the time, and can be locked by locking the trigger pulse of the third switching module (3) when direct current faults occur. By means of the solution, a function of isolating the direct current faults is achieved, quantity and switching losses of fully-controllable devices in the sub-module are decreased, and requirements on trigger simultaneity are reduced.

A wind turbine pitch drive system comprises an electric grid for supplying electrical power, a motor for driving a pitch actuator, an electronic converter for controlling the motor and a back-up energy storage unit for supplying electrical power. The electronic converter comprises a DC-link capacitor bank. The system furthermore comprises a switching device for selectively connecting the DC-capacitor bank link to the back-up energy storage unit, and a frequency generator for controlling the switching device. Also disclosed is a method for protecting a component of the electronic converter.

The invention discloses a switch capacitance access high frequency bi-directional DC (direct current) transformer and belongs to the field of the electric power technology; the switch capacitance access high frequency bi-directional DC transformer is mainly composed of n pieces of DC converter units serially connected in a port and connected in parallel in another port, the DC converter units are the same and n is any positive integer; each DC converter unit is composed of eleven semiconductor switches, two DC capacitors, one high frequency inductor and one high frequency transformer; k pieces of DC converter units in n pieces of DC converter units are in redundancy work state; under normal circumstances, the high voltage sides of the n-k pieces of DC converter units are serially connected to the high voltage DC side while the low voltage sides are connected to the low voltage DC side in parallel; any DC converter unit in redundancy work state can be adopted for working while any DC converter unit has damage or fault for the interior; the semiconductor switches of all DC converter units are turned off while the high voltage DC side or the low voltage DC side has short-circuit fault, and the capacitor voltage is kept. The system circulation is reduced, the fault treatment and redundancy technology are simplified and the reliability is improved.

A DC chopper comprising a control unit and a power circuit and a DC chopping method for a DFIG (doubly fed induction generator) system are provided. The input terminal of the control unit is coupled to a DC capacitor of a converter to detect a DC voltage. The power circuit includes input terminals, an overvoltage protection module, a rectifier module and output terminals. The overvoltage protection module comprises at least one discharge unit formed from a discharge resistor and a switch element, and the rectifier module is coupled in parallel to the overvoltage protection module. When a grid voltage drops, the control unit outputs a corresponding control signal to drive the switch element to be ON or OFF, and the output terminal of the power circuit absorbs a portion of rotor inrush current, so as to impose over-current protection.

The invention relates to a cascading-type STATCOM (Static Synchronous Compensator) DC (Direct Current) side capacitor voltage balance control method. In the control method, the direct current control and the indirect current control are combined. The method comprises the following steps: generating an active current reference value; selecting a special bridge; generating an STATCOM output current reference value; carrying out indirect current control of the special bridge; and carrying out direct current control of a non-special bridge. The control method provided by the invention is used for controlling the cascading-type STATCOM DC side capacitor voltage balance. The method not only ensures the balance of a DC capacitor voltage between H bridges and improves the response speed of a control link and optimizes the system performance, but also does not require an additional hardware circuit and cannot ensure the hardware cost of a STATCOM device to be increased.

The invention discloses a movable model device of a system of offshore wind powder synchronized through flexible DC (Direct Current) power transmission. The movable model device comprises a main circuit system and a control protection system, wherein the main circuit system comprises an offshore wind power generator unit simulation device, a flexible DC power transmission system, an AC (Alternating Current) bus and a movable model grid, the flexible DC power transmission system is respectively connected with the offshore wind power generator unit simulation device and the AC bus through solid switches and consists of an even number of structural units, wherein each structural unit comprises a converter transformer, a reactor, a voltage source type converter, a DC capacitor, a grounded circuit, a DC line, a solid switch and voltage and current mutual inductor elements, and the control protection system comprises a background computer, a microcontroller system and a data acquisition card system. The movable model device disclosed by the invention provides a reliable and convenient research platform and test environment for a main circuit design, dynamic response characteristic analysis, control policy design and control system of the system of offshore wind powder synchronized through flexible DC power transmission.

A method in a controller for energizing a chain-link converter including one or more phase legs, each phase leg including a number of series-connected converter cells, each converter cell including four valves arranged in an H-bridge connection with a DC capacitor. Each valve in turn includes a semiconductor switch in parallel with a diode. The method includes the steps of: charging the DC capacitor of each converter cell to a voltage level at which the semiconductor switches are controllable but below their nominal voltage; diagnosing the converter cells so as to detect failed components thereof; bypassing faulty components in a controlled manner; charging the DC capacitors to their nominal voltage. The invention also relates to a controller, computer programs and computer program products.

An improved power sensor having an input connector connected to an input port having a center pin and a ground side; an amplifier; first and second detectors; and a thermal stabilization system, including a thermal mass disposed between the ground side of the input connection and the detectors, a ground plane for holding the temperature of thermally sensitive components constant to within 2 degrees C., and a thermal impedance disposed between the center pin of the input port, preferably including a splitter and at least one DC capacitor, and a temperature sensor disposed on the ground plane.

A power converter 100 includes a DC capacitor C, semiconductor switch groups each of which includes semiconductor switches connected in series to each other, bridge-cells 11u-j, 11v-j, and 11w-j each of which includes the DC capacitor C and two semiconductor switch groups connected in parallel to the DC capacitor C, a delta connection unit 10 including delta-connected bridge-cells and a integrated control unit 1 for controlling a circulating current flowing in the delta connection unit such that each of DC-capacitor by-phase average values follows a DC-capacitor three-phase average value, each of the DC-capacitor by-phase average values being obtained by averaging voltage values of the DC capacitors at a corresponding phase of three phases, and the DC-capacitor three-phase average value being obtained by averaging voltage values of the DC capacitors at all of the three phases.

The invention discloses a method for controlling the balance of capacitive voltages of a five-level diode neutral point clamped converter. The method has the advantages that an integral modulation degree area is divided into a low modulation degree area (with an m<SV> smaller than or equal to 0.5) and a high modulation degree area (with an m<SV> larger than 0.5), and direct-current-side voltages of different modulation degree areas are controlled by different processes; a process for optimizing objective functions and a process for decomposing a reference voltage are combined with each other in a process for controlling the direct-current capacitive voltages in the low modulation degree area, the process for controlling the direct-current capacitive voltages in the low modulation degree area can be implemented easily, redundant switch states of various vectors are sufficiently utilized, and waveforms outputted by a system are improved; and complicated overlap area judging algorithms are omitted in an optimized process for selecting balancing vectors in the high modulation degree area, and the system is high in the response speed.

An auxiliary quasi-resonant DC tank (AQRDCT) power converter with fast current charging, voltage balancing (or charging), and voltage clamping circuits is provided for achieving soft-switched power conversion. The present invention is an improvement of the invention taught in U.S. Pat. No. 6,111,770, herein incorporated by reference. The present invention provides faster current charging to the resonant inductor, thus minimizing delay time of the pulse width modulation (PWM) due to the soft-switching process. The new AQRDCT converter includes three tank capacitors or power supplies to achieve the faster current charging and minimize the soft-switching time delay. The new AQRDCT converter further includes a voltage balancing circuit to charge and discharge the three tank capacitors so that additional isolated power supplies from the utility line are not needed. A voltage clamping circuit is also included for clamping voltage surge due to the reverse recovery of diodes.

The invention relates to a direct current (DC) side capacitor voltage balancing control circuit for an H-bridge cascaded active power filter, which comprises a single-phase transformer bank (2), wherein the single-phase transformer bank comprises m single-phase transformers, and primary windings are connected in parallel through a public alternating current (AC) bus (1); n secondary windings of the M single phase transformers are connected with n single-phase half-bridge converters through an inductor and a DC isolation capacitor; the n single phase half-bridge converters are respectively connected with DC voltage supporting capacitor of cascaded power units of an H-bridge cascaded multi-level converter, wherein m and n are natural numbers no less than 2, and m is no more than n. The balancing control circuit can balance DC capacitor voltages in same cascaded power units of the cascaded multi-level converter and DC capacitor voltages of different cascaded power units.

The invention relates to a measurement device for stray inductance in an IGBT module. The measurement device is characterized in that the measurement device comprises a power supply device, a to-be-measured IGBT module, a current probe, a voltage probe, an oscilloscope, a pulse triggering device, controllable switches S1, S2, S3, a DC capacitor C1, a DC discharging resistor R1, a load inductor L1 and a freewheeling diode D1; the controllable switch S2 is serially connected with the DC discharging resistor R1 and is parallelly connected with the DC capacitor C1; the freewheeling diode D1, the controllable switch S3 and the to-be-measured IGBT module are serially connected; the pulse triggering device is connected with the controllable switch S3; and the load inductor L1 is parallelly connected with two sides of the freewheeling diode D1. The measurement device can effectively evaluate induction voltage of an inner packaging parasitic parameter when the IGBT module is in a switching-off transient state. The packaged stray inductance which is calculated according to the voltage and current over two ends of a parasitic inductor is more practical and can be used for evaluating an IGBT safety margin, and furthermore can be used for verifying IGBT module designing. The measurement device and the measurement method have a certain meaning to semiconductor manufacturers and IGBT application parties.

Method of controlling a voltage controlled PWM (Pulse Width Modulated) frequency converter comprising a single phase rectifier bridge (10) connectable to a sinusoidal single phase supply, a DC intermediate circuit (11) and a controlled inverter bridge (12) for generating an AC output voltage with varying amplitude and frequency to a load, said inverter bridge (12) having PWM controlled semiconductor switches (V11–V16) and flywheel diodes (D11–D16) connected in inverse-parallel with the semiconductor switches, wherein the DC intermediate circuit (11) is provided with a DC capacitor unit, and wherein the frequency converter is controlled so that the supply line current (Iin) is essentially sinusoidal and in phase with the supply line voltage (Uin). The inverter bridge is controlled so that the curve of filtered average current (Idc) in the DC intermediate circuit follows essentially the curve of the rectified AC supply voltage (Udc), the rectifier bridge is (10) connected to the inverter bridge (12) directly without a DC capacitor unit acting as an intermediate energy storage, and the curve of the power fed to the load has essentially the form sin2(2πft) (f=line frequency t=time).

The invention discloses an improved switched capacitor-accessed two-way DC transformer and a control method thereof, and belongs to the technical field of electric power. The transformer is formed by connecting n identical DC conversion units at one port in series and at the other port in parallel; and each DC conversion unit comprises eight semiconductor switches, two auxiliary semiconductor switches, two DC capacitors, a high-frequency inductor and a high-frequency transformer. The method comprises the steps as follows: under the normal condition, high-voltage sides of the n DC conversion units are connected in series and then are connected to a high-voltage DC side through a DC electric reactor; low-voltage sides of the n DC conversion units are connected in parallel and then are directly connected to a low-voltage DC side; when smaller than k DC conversion units have internal faults, the DC conversion units with the faults are directly bypassed; and when an external fault appears at the high-voltage or low-voltage DC side, the semiconductor switches and the auxiliary semiconductor switches of all DC conversion units are turned off and the capacitor voltage can be kept constant. According to the improved switched capacitor-accessed two-way DC transformer, the operation economy and reliability of a device are improved.

The invention discloses an inverter circuit and a voltage space vector pulse width modulation method thereof, which belong to the technical field of circuits. The inverter circuit comprises a direct current capacitor, a first three-phase bridge inverter circuit, a second three-phase bridge inverter circuit and a three-phase isolating transformer. The voltage space vector pulse width modulation method comprises the following steps of: acquiring basic voltage space vectors of the inverter circuit and corresponding switching tube switching state combinations thereof; computing a modulation degree according to an expected voltage space vector; determining the basic voltage space vector for synthesizing the expected voltage space vector according to the modulation degree, finding the corresponding switching tube switching state combinations of the determined basic voltage space vector, and selecting a switching tube switching state combination with the lowest switching frequency from the found switching tube switching state combinations; and regulating a switching tube according to the selected switching tube switching state combination to realize the synthesis of the expected voltage space vector. By the inverter circuit and the method, the problem of voltage unbalance of the direct current capacitor is solved, and the aim of lowest switching frequency in vector switching is fulfilled.

The invention discloses a zero-voltage switching energy storage bridge-type inverter without additional voltage and a modulation method for the inverter. The zero-voltage switching energy storage bridge-type inverter comprises a direct-current-side energy storage battery, direct-current capacitors, an alternating-current filter inductor and a single-phase bridge arm. The single-phase bridge arm comprises four fully-controlled main switches with antiparallel diodes, an auxiliary switch with an antiparallel diode is connected between the energy storage battery and a direct-current bus of the single-phase bridge arm, the capacitors are respectively connected to two ends of each main switch and two ends of the auxiliary switch in parallel, the two ends of the auxiliary switch are connected with a resonance branch circuit, and a resonance inductor and a clamping resistor are serially connected to form the resonance branch circuit. The zero-voltage switching energy storage bridge-type inverter and the modulation method have the advantages that the zero-voltage switching energy storage bridge-type inverter can run independently in an on-load manner or run in a grid-connected manner, and is simple in structure, power flows in two directions, and a storage battery can be charged and discharged; the sinusoidal pulse width modulation method is implemented for the main switches, and modulation signals of the auxiliary switch are synchronous with the main switches; zero-voltage switching of all the main switches can be realized only by one-step action of the auxiliary switch in each switching period, reverse recovery current of the antiparallel diode of each main switch is suppressed, the zero-voltage switching energy storage bridge-type inverter is low in switching loss, high in circuit efficiency and beneficial to increasing working frequency, and the power density is increased.

This power converter (1) is provided with: unit cells (11-M) having a semiconductor switch, a DC capacitor (C) and a charge / discharge current I / O terminal; a first arm (12-P) and a second arm (12-N) comprising multiple unit cells (11-M) connected to each other in cascade; an arm connecting unit (13) which has a first terminal to which the first arm (12-P) is connected, a second terminal to which the second arm (12-N) is connected, and a third terminal to which a DC power source is connected; and a transformer (14) which has an AC I / O terminal on the primary side and an intermediate terminal on the secondary side winding, and in which the terminal of the first arm (12-P) and the terminal of the second arm (12-N) are connected to the two end terminals on the secondary winding, and the DC power source (Vdc) is connected to the intermediate terminal.

The invention discloses a system and method for high-voltage direct-current starting and power generation of a stator duplex winding asynchronous motor. A main loop comprises the stator duplex winding asynchronous motor, a rectifier bridge, a power converter, a direct-current power source, a diode, a control side direct-current capacitor and a power side direct-current capacitor. A detecting loop comprises a first voltage transducer, a second voltage transducer, a first current transducer and a second current transducer. A control loop comprises a digital signal processor and a driving circuit. Five-phase centralized full-pitch star-shaped structures are adopted by both sets of stator windings which are a power winding and a control winding of the stator duplex winding asynchronous motor. In the starting and power generating process, the power converter implants three times of proper harmonic currents to the motor through the control winding under the control of the digital signal controller, an air-gap magnetic field is controlled to be a standard square wave, and therefore the torque density and the power density of the motor are improved. The system and method for the high-voltage direct-current starting and power generation of the stator duplex winding asynchronous motor is simple in structure and free of electric brush sliding rings, can achieve the integration of start and power generation, and has the advantages of being high in power density and torque density, easy to operate with fault-tolerance and the like.