187results about How to "Reduce on-state loss" patented technology

The invention relates to a breaker of a direct current system, in particular to a semi-controlled active injection current high voltage direct current breaker and a realization method thereof. The breaker comprises a high speed switch-thyristor module branch, as well as a lightning arrester branch and a bridge circuit which are connected in parallel with the branch, wherein a capacitor-reactor series branch and a resistor-thyristor series branch are connected in parallel and then connected with middle points of two bridge arms of the bridge circuit; and the two ends of a capacitor are connected in parallel with a charging loop. The breaker is based on a direct current breaking principle by the traditional active injection current manner; semi-controlled power electronic devices are added; a high speed mechanical switch is adopted; the advantage of low loss during normal breakover is kept; and bidirectional current can be broken quickly without an arc. The breaker is simple in circuit topological structure, simple and convenient to control, mature in technology, easy to realize, great in current breaking capability, high in withstand voltage level and strong in expansion capability, and the cost is lowered greatly since the number of the adopted power electronic devices is small.

The invention discloses a phase shift control method for a double-active full bridge bidirectional DC-DC converter in a full load range ZVS and belongs to the high frequency switching power supply inthe power electronic field. The method is characterized in that an excitation current is introduced by the converter on the basis of the original topology, the minimum current required for resonance of a secondary side switch tube when it is turned off is compensated, and thereby the soft switching range of the secondary side switch tube of the converter is expanded. In an EPS mode, based on the injected excitation current, the control strategy for the full load range ZVS and the low current stress is designed, by controlling an on-bridge duty cycle of a high voltage side and an inter-bridge phase shift angle of two full bridges, the converter can operate in the ZVS region at different voltage ratios under different transmission powers, that the converter achieves soft switching over the full load range is guaranteed, switching loss of the switch tube is reduced, moreover, the current peak is reduced, the current stress of the power device is reduced, on-state loss and loop loss of theconverter are reduced, and circuit loss is further reduced. The converter is advantaged in that efficiency and reliability can be improved.

A bipolar transistor having at least a low doped drift layer (14) of crystalline SiC comprises at least one first layer (13) of a semi-conductor material having a wider energy gap between the conduction band and the valence band than an adjacent layer (14) of SiC.

The invention relates to a circuit breaker and a realization method thereof, and particularly relates to a high-voltage DC circuit breaker and a realization method thereof. The DC circuit breaker, based on a secondary current transferring principle, comprises a main branch, a current transferring branch and an energy absorption branch in parallel connection. The DC circuit breaker is serially connected in a DC system. The main branch comprises at least one high-speed mechanical switch K and at least one current transferring module comprising a fully-controlled device in serial connection. The current transferring branch is a bridge circuit formed by thyristor valves, inductors and capacitors. The energy absorption branch is formed by a non-linear resistor. The invention also provides a high-voltage DC circuit breaker realization method. The circuit breaker provided by the invention has a simple topological structure, the control is simple and convenient, used power electronic devices are mainly half-controlled thyristors, the technology is mature, realization is easy, the current breaking ability is large, a voltage-withstanding grade is high, the extension ability is strong, and the cost is greatly reduced.

The invention discloses a fault-tolerance-capability-equipped MMC sub-module structure capable of realizing DC fault self-protection. Current stress balance of two capacitors and eight power switch tubes in a sub-module are adjusted through redundant switch states; three level can be output at a normal mode, and the level integration of the sub-module is improved; under the condition of a locking mode, the capacitors of the sub-module are completely invested into legs, the capacitors of the sub-module are charged, a reverse electromotive force is generated, and a function of isolating DC-side faults is realized. According to the invention, when the sub-module structure is applied to an MMC-HVDC system, self-protection of the DC-side faults can be realized. Due to the symmetry of the structure, the output characteristics of sub-module structure, under the condition of the locking mode, are symmetrical about a current direction, and good symmetry helps to maintain the current stress balance of the power devices and the capacitors in the sub-module; and when the MMC sub-module structure is applied to an HCMC-HVDC system, the MMC sub-module structure is lower in conduction loss than a full-bridge sub-module structure and higher in system operation efficiency.

The invention discloses a dual-capacitor module based MMC type multi-port power electronic transformer. The transformer comprises a modular multilevel converter (MMC), a DC / DC converter and an inverter, wherein the MMC has two sub modules; the DC / DC converter comprises a primary part, a high frequency voltage transformation part and a secondary part, wherein the primary part has four kinds of selective topologies. The transformer can be operated on the high voltage direct current side at a low voltage; the transformer has fault ride-through capability, and relatively less devices are used; the module in the MMC and the DC / DC converter are responsible for direct current voltage control and power control respectively; a single capacitor voltage of the module can be controlled independently, or two capacitor voltages of the module can be controlled simultaneously; the transformer is equipped with the four ports, including a high voltage direct current port, a high voltage alternating current port, a low voltage direct current port and a low voltage alternating current port, so that the transformer is suitable for multi-kind high-voltage high-power occasions of multiple voltage levels, and particularly suitable for the energy internet; for example, the transformer can be used as an energy router, and the like.

The invention discloses a capacitor-clamped three-level dual-buck half-bridge inverter which comprises a first three-level duck circuit, a second three-level duck circuit, a direct-current power-supply input circuit and a load circuit, wherein each three-level duck circuit comprises two power switching tubes, two power diodes, a clamping capacitor and an inductor, and +1, -1 and 0 three-state levels are output by an inverter bridge under the actions of controlling the switching tubes and clamping the clamping capacitor, thereby realizing the three-level dual-buck half-bridge inverter. The invention has the advantages that the advantage that a DBI circuit has not problems of through bridge arms or backward recovery of switching tube body diodes is inherited; the advantage that a three-level convertor per se has small output voltage harmonic content is reserved; compared with a traditional half-bridge inverter, the voltage stress of power devices is reduced; and the whole circuit structure is simpler and easy to realize.

A passive high-voltage direct-current circuit breaker and an implementation method therefor. The high-voltage direct-current circuit breaker is connected in a direct-current system in series, and comprises an energy absorption branch, a main branch and a current transfer branch which are connected in parallel, wherein the current transfer branch comprises first current transfer branches (T1, T2) and second current transfer branches(T3, T4); the energy absorption branch is composed of a nonlinear resistor (MOV); and the main branch comprises at least two groups of high-speed mechanical switches (K1, K2) and at least two groups of full controlled device modules which are connected in series. Since the circuit has a simple topology structure, is simple and convenient to control, and is flexible to apply, the energy required by injecting a current into a capacitor can be obtained from a system without configuring an auxiliary power source, thereby improving the reliability of an apparatus. The used power electronic devices are mainly half controlled thyristors, so that the series connection technology is mature, the capability for current segmentation is strong, the level of withstand voltage is high, the expansion capability is strong, and the costs of devices are low.

The invention relates to a three-state three-level PFC circuit, which comprises an inductor, a combined three-state switch, a first capacitor and a second capacitor. The inductor is connected between a first end of an AC power supply and a first end of the combined three-state switch; a second end of the combined three-state switch is connected at a first end of the first capacitor; a third end of the combined three-state switch is connected at a second end of the second capacitor; a fourth end of the combined three-state switch is grounded; and the first end of the first capacitor, a second end of the first capacitor, and the second end of the second capacitor output three-level voltage. The invention also provides a multi-state three-level PFC circuit correspondingly. Compared with the common circuit without a three-state switch or a multi-state switch, the PFC circuit provided by the invention can obviously reduce the dimensions of the inductor and the capacitors, improve the powerfactor of the circuit simultaneously and reduce the total harmonic content on the premise of maintaining the switch frequency and ripples on a passive device invariable, and can reduce the switch frequency and obviously improve the circuit efficiency on the premise of maintaining the input current ripple frequency and magnitude invariable.

The invention discloses a mixed-type high-voltage DC breaker and an implementation method thereof. The DC breaker is connected in a DC system in series and concretely comprises the following branches connected in parallel: an on-state branch, a pre-transfer branch, a re-transfer branch and an energy-dissipating branch. The on-state branch comprises at least one quick mechanical switch and a first current transfer module including a full control device, and the quick mechanical switch and the first current transfer module are connected in series. The pre-transfer branch comprises the following parts connected in series: a first inductor, a first semi-control device thyristor serial connection module, and a second current transfer module including a full control device. The re-transfer branch comprises the following parts connected in series: a second inductor, a second semi-control device thyristor serial connection module, and a capacitor. The energy-dissipating branch is formed by a non-linear resistor. The implementation method comprises corresponding operations when the DC system runs normally or when a short circuit fault happens to the DC system. With the prerequisites including a fast enough breaking speed and low losses ensured, the DC breaker employs the semi-control device thyristors, so that the capability of breaking current is good, the voltage-withstanding level is high, and the cost is greatly reduced.

The invention provides a direct current monopole grounding fault ride-through method for a multi-port flexible high-voltage direct current power transmission system. The fault ride-through method is realized through coordination matching between an MMC (modular multilevel converter) based on low-resistance grounding and having negative electric level output capability and a mechanical direct current isolation switch; in a fault period, by regulating common-mode component of a reference voltage of each MMC bridge arm, fault transient state overvoltage can be eliminated under the premise of not sacrificing the controllability of the converter; meanwhile, by overlaying a fault pole bridge arm reference voltage with a first reference voltage signal and by controlling a fault pole bridge arm current to be zero, the mechanical direct current isolation switch can isolate direct current fault in a zero current condition, so that foundation is laid for the application of the mechanical direct current isolation switch in the multi-port flexible direct current power transmission system; and in the fault period, the MMC forms a loop through sound direct current bus-alternating current side low-impedance grounding pole-ground, so that transmission of half rated active power can be maintained.

The invention provides a high voltage direct current circuit breaker topology circuit which comprises a main branch, a current transfer branch and an energy absorption branch. The main branch, the current transfer branch and the energy absorption branch are connected in parallel. According to the high voltage direct current circuit breaker topology circuit provided by the invention, the structure of a circuit topology is simple; a stable current zero crossing point is in a breaking process; and the high voltage direct current circuit breaker topology circuit has the advantages of convenient control, flexible application, easy realization, high current breaking capacity, high withstand voltage level, high expansibility and low equipment cost.

The invention relates to direct current (DC) step-up power conversion technology and discloses a current-type multi-resonance DC converter. The current-type multi-resonance DC converter comprises a square-wave current source generator, a multi-resonance network and a rectification filtering output unit which are sequentially connected in series, and is characterized in that: the multi-resonance network comprises a transformer, a parallel resonant inductor, a parallel resonant capacitor and a serial resonant inductor, wherein the serial resonant inductor is connected with a primary side of the transformer; the rectification filtering output unit comprises a diode rectifying circuit and a filtering capacitor which is connected with an output end of the diode rectifying circuit in parallel.

The invention discloses a switch reluctance wind power generator converter. The switch reluctance wind power generator converter consists of a converter main circuit, an output bus capacitor, an isolated DC / DC converter, an excitation and discharge main circuit; the output end of the converter main circuit is connected to the output bus capacitor, and also serves as the input end of the isolated DC / DC converter; the output end of the isolated DC / DC converter is connected to the input end of the excitation and discharge main circuit; the output end of the excitation and discharge main circuit is connected to the input end of the converter main circuit; the output anode end of the converter main circuit is also connected to the discharge input end of the excitation and discharge main circuit; and the output anode end of the excitation and discharge main circuit, the output cathode end of the converter main circuit and the input anode end of the converter main circuit are short-circuited. Under the structure, through three types of control modes under different conditions, wide power generation range, high power generation capacity and multi-angle flexible control are realized, and the switch reluctance wind power generator converter is applicable to various wind power generation fields.

This invention discloses a single-step power factor correction circuit for reducing switch loss, in which, a HF transformer includes two primary windings, and a pair of same-name ends are connected with the leakage of a switch tube, a mode of mutual couple of two windings is applied to put an inductance device for correcting input current waves in front of a rectifying bridge to improve the magnetic interference of the single-step PFC circuit at the same time when correcting power factors, when a switch tube is off, part of energy stored in the primary PFC inductor and the leakage inductor of the feedback winding is provided to the capacitor for charging and the other part is transmitted to secondary capacitor by the transformer directly so as to reduce loss brought with leakage inductance of the feedback winding and the switch loss and increases the efficiency.

The present invention provides an inverter, a method and device for controlling the inverter. The invention aims to improve the efficiency of the inverter. The inverter comprises an active clamping three-level topological structure comprising a first bus-bar capacitor, a second bus-bar capacitor and an inverter circuit. The inverter circuit includes a first switching tube, a second switching tube,a third switching tube, a fourth switching tube, a fifth switching tube and a sixth switching tube; the first switching tube, the second switching tube, the third switching tube and the fourth switching tube are sequentially connected in series in the same direction between a positive direct-current bus-bar and a negative direct-current bus-bar; the fifth switching tube and the sixth switching tube are connected in series in same direction; one end of the fifth switching tube and the sixth switching tube is connected with the series connection point of the first switching tube and the secondswitching tube, and the other end of the fifth switching tube and the sixth switching tube is connected with the series connection point of the third switching tube and the fourth switching tube; theseries connection point of the fifth switching tube and the sixth switching tube is connected with the series connection point of the first bus-bar capacitor and the second bus-bar capacitor; and eachswitching tube is in reverse parallel connection with one corresponding diode. The inverter also comprises a seventh switching tube and an eighth switching tube; the seventh switching tube and the eighth switching tube are connected in series in the same direction between the positive direct-current bus-bar and the negative direct-current bus-bar; the series connection point of the seventh switching tube and the eighth switching tube is connected with the series connection point of the second switching tube and the third switching tube; and the seventh switching tube and the eighth switchingtube are in reverse parallel connection with corresponding diodes.

The invention relates to a self-turnoff component driving protection circuit which particularly comprises positive and negative power supplies, an optical coupler isolating circuit, a control circuit, an anti-saturation circuit, a high power transistor and a composite buffer circuit, wherein a control signal current is subjected to resistance-capacitance filtering and is subsequently input into the anode of a primary light emitting diode of the optical coupler component; an emitter electrode of a secondary phototriode of the optical coupler component is directly connected with the input end of a chip UAA4002 in the control circuit; the positive power supply is connected with the collector electrode of the phototriode through a switch; the positive and negative power supplies are respectively connected with positive and negative power supply pins of the chip UAA4002 and are respectively connected with the collector electrodes of subsequent upper and lower pair tubes, the control circuit is connected with the anti-saturation circuit through a current-limiting resistor; the anti-saturation circuit is connected in parallel between the base electrode and the collector electrode of the high power transistor; and the composite buffer circuit is directly connected in parallel between the collector electrode and the emitter electrode of the high power transistor; thereby a self-turnoff component driving protection circuit which is simple in circuit structure, complete in function, high in reliability, small in switch consumption and rapid in protection response is provided.

The invention includes reduction voltage circuit of first and third electrical level, and reduction voltage circuit of second and third electrical level. Un the two circuits, one end of the power switch tube is connected to external electrical source; and the other end is connected to three levels combined switch composed of two power diodes and one power switch connected to each other. Advantages of the invention are: small content of harmonic wave in output voltage, reduced switch frequency and wastage of switch, no need of large capacitance on DC side, applicable to condition of high voltage and large power, no straight through issue of bridge arm, and no issue of backward recovery of diode in switch tube. Moreover, the invention possesses simple structure and control scheme, and good dynamic properties of the invention.

The invention discloses a flyback converter for implementing auxiliary output voltage control by using a triode and a control method. The flyback converter comprises a transformer, a main switch, a PWM (pulse width modulation) control circuit, a main output rectification filter circuit, an auxiliary output rectification filter circuit and an auxiliary output control circuit, wherein the main switch is connected with the primary winding of the transformer; the PWM control circuit controls the main switch; the main output rectification filter circuit is connected with the secondary winding of the transformer; the auxiliary output control circuit is connected with the auxiliary output rectification filter circuit; the auxiliary output rectification filter circuit comprises an auxiliary loop switch; and the auxiliary output control circuit switches on and off the auxiliary output rectification filter circuit through controlling the auxiliary loop switch. According to the invention, the stability of the auxiliary output voltage is improved effectively, the circuit loss is reduced, and the flyback converter has the advantages of small volume, low cost, simpleness for control and the like.

The invention discloses a five-level double-step down grid-connected inverter and belongs to the field of inverters. The structure comprises an input direct current source, an input voltage-dividing capacitor branch, a neutral-point clamped branch, a full bridge power branch, a common mode inductor branch and an output filtering branch, wherein the common mode inductor branch and each power branch comprise multiple configuration and connection modes. The beneficial effects are that power switch tubes and filtering inductors are low in voltage change ratio, the size of a filter is small, and the power density and the conversion efficiency are high; the number of filtering inductors in the output filtering branch is reduced through coupling inductors, thereby achieving a bidirectional power flow; and the inverter is suitable for occasions of middle and high voltage and large power, and has a wide application prospect in the new energy grid-connected power generation field with high requirements for inverter power density and conversion efficiency.

The invention discloses a two-way half-bridge unilateral tri-level DC-DC converter and an optimization control method for a minimum current effective value. The method realizes the optimization of the minimum current effective value during two-way transmission of power between a primary side and a secondary side by controlling the duty ratio D1 of the neutral-point voltage of a high-voltage side bridge arm and the phase shift ratio between the neutral-point voltage of primary side bridge arm and a secondary side bridge arm. The method gives the steps of solving the minimum current effective value D1, realizes the control of the minimum current effective value in the range of total power, also realizes zero voltage conduction of all switching tubes in the full-load range, and therefore effectively reduces the on-state loss and the switching loss of the converter.

The invention discloses a current effective value minimizing control method for a bidirectional half-bridge tri-level DC (Direct Current)-DC converter. Three controlled quantities in a topological structure of the bidirectional half-bridge tri-level DC-DC converter are controllable, namely a primary side bridge arm middle point voltage duty ratio D1, a secondary side bridge middle point voltage duty ratio D2 and a phase shift angle Dalpha between primary side bridge arm middle point and secondary side bridge arm middle point voltage; minimized control of the current effective level is achieved under the premise that power required for transmission load is satisfied. According to the current effective value minimizing control method for a bidirectional half-bridge tri-level DC (Direct Current)-DC converter, D1, D2 and Dalpha is coordinately controlled, the current effective value of a transformer is minimum under the condition that the power required for the load is satisfied, copper loss of a magnetic element in a circuit and conduction losses of a switch tube are reduced, meanwhile switch tubes in the circuit can achieve zero-voltage conduction within the integral transmission power range, and switch loss of a power device is effectively reduced.

The invention discloses a Boost double-voltage power factor correction circuit utilizing a reverse blocking insulated gate bipolar transistor (IGBT). The circuit comprises two input inductors, two switching tubes, two output rectifier diodes, and two output filter capacitors, wherein both of the two input inductors are connected with the same end of an input power supply; the two switching tubes respectively connect the other end of each of the two input inductors to the other end of the input power supply not directly connected with the inductors so as to form a charging loop respectively; the two output rectifier diodes connect the two input inductors to the two output filter capacitors respectively; and the output filter capacitors can be connected with a load respectively. Due to the adoption of the reverse blocking IGBT, an input rectifier diode can be saved; on one hand, the total amount of the circuit devices is reduced so as to save the cost; and on the other hand, the number of conducting semiconductor devices on a current path is reduced so as to reduce conduction loss and contribute to improving the efficiency of an overall machine. In addition, the circuit has high electro magnetic compatibility (EMC) by utilizing two input inductors compared with using a single inductor.

This invention discloses a single-step power factor correction circuit for reducing EMI, which applies a mode of mutual couple of two windings and puts an inductor for correcting input current wave on the front of a rectifying bridge to improve the magnetic interference of single-step PFC circuit and limits voltage of energy-storing capacitor by connecting central taps of first windings of a transformer, when a switch tube is turned off, part of energy stored in the primary coupled PFC inductor is provided to the energy-stored capacitor for charging and the other is transmitted to the secondary by the transformer directly so as to increase the entire efficiency of the converter.

The invention relates to a dual-reduction inverter, which comprises capacitor divide circuit, the first reduction circuit and the second reduction circuit, wherein the divide circuit is formed by two serially connected first and second capacitors; the first reduction circuit has the first power switch tube, the third power switch tube and the first inductance; the second reduction circuit has the second power switch tube, the fourth power switch tube and the second inductance; the load is connected between the anode of first power diode and the cathode of second power diode. The invention has the advantages that: when the input bus voltage is lower than output voltage, the inverter also can operate invert operation, with simple structure and simple control.

The invention provides an oscillation transfer and solid-state switch combined direct-current circuit breaker, which is composed of a main current loop, a current transfer branch, an energy absorptionbranch and a control system. According to the invention, under the condition of small current on-off, a high-speed mechanical switch is controlled to be switched off to be connected with a corresponding power electronic device, current is transferred to a current transfer branch under the action of arc voltage, and then the power electronic device is controlled to be switched off, voltage at thetwo ends of a power electronic assembly rises and a lightning arrester is controlled to be connected; when a large-current short-circuit fault occurs, the high-speed mechanical switch is controlled tobe switched off to be conducted with the power electronic device; and a pre-charging capacitor injects reverse current into the fracture, the fracture current is subjected to zero-crossing arc extinguishing, short-circuit current is transferred to the current transfer branch and charges the capacitor, and when the capacitor voltage is greater than the lightning arrester conduction voltage, the lightning arrester is conducted. The novel direct-current circuit breaker has the characteristics of simple structure, low on-state loss, high full-current breaking speed and the like.

The invention discloses a single phase asymmetrical full-bridge non-isolated photovoltaic grid-connected inverter, and belongs to the technical field of power electronic converters. The single phase asymmetrical full-bridge non-isolated photovoltaic grid-connected inverter is composed of an input capacitance branch, an improved full-bridge switch unit and a net filter branch. On the basis of a basic full-bridge circuit, an auxiliary switch is disposed on the single phase asymmetrical full-bridge non-isolated photovoltaic grid-connected inverter, so that a after-flow return circuit is separated from an output end of a photovoltaic cell during after-flow, electric potential of the after-flow return circuit is or near to half of the cell voltage, and thus the non-isolated photovoltaic grid-connected inverter is prevented and avoided from leaking currents. Compared with the prior non-isolated photovoltaic inverter topology, the single phase asymmetrical full-bridge non-isolated photovoltaic grid-connected inverter has the advantages that number of switch tubes of current paths decreases, conduction losses are reduced, and conversion efficiency is improved. Further, the single phase asymmetrical full-bridge non-isolated photovoltaic grid-connected inverter is suitable for photovoltaic grid-connected sites without isolation of transformers.

The invention discloses an energy routing system based on LCC-MMC, and a direct current fault protection method, and belongs to the technical field of hybrid high-voltage direct current transmission. The topology of the system comprises a power grid phase control converter LCC, a modular multilevel converter MMC, an energy storage device BESS, an improved hybrid DC circuit breaker DCCB and a direct current bus. The energy regulation and control mode of the system comprises LCC side constant direct current voltage control, MMC alternating current side power decoupling control and energy storage interface Buck / Boost control. According to the direct current fault protection method of the system, energy storage unit power switching control and an improved hybrid direct current circuit breaker DCCB are combined to form a set of complete combined fault protection scheme. While the fault current is quickly isolated, the MMC side alternating current can be prevented from being distorted, the power supply quality of the system is greatly improved, reliable and stable operation of the alternating current power grid is ensured, and quick recovery of the system after the fault is facilitated.