557 results about "Level converter" patented technology

Provided in the present invention is a transformerless unified power quality conditioner, comprising a three-phase conditioner substructure, wherein each phase of the conditioner substructure can comprise an ANPC three-level converter and an output half-bridge module connected to the ANPC three-level converter. Also provided are a corresponding modulation method and system and a corresponding control method and system. Compared with existing voltage regulation apparatuses, the transformerless unified power quality conditioner and the modulation method and control method therefor provided in the present invention do not include a power-frequency transformer in the topology, but use a three-level converter to expand ports to realize voltage regulation, thus having the advantages of lower costs, smaller size, smaller footprint, lower loss, etc.

The invention provides a modularized multi-level converter current control method based on feedforward analysis. The deviation between the direct-current side voltage and the reference value is stably monitored in real time based on the direct-current bus voltage, a first waveform signal is dynamically generated, and the direct-current side voltage fluctuation range is limited. According to the circulating current interphase voltage sharing, the dynamic deviation between the actual value and the rated value is calculated by collecting the capacitor voltage actual value of the bridge arm sub-module, and a second waveform signal is generated to balance the circulating current distribution of each phase of bridge arm. The loop current suppression based on feedforward analysis generates a third waveform signal to compensate for high-frequency loop current interference through real-time comparison of theoretical modeling and actual loop current components. In the modulation wave generation process, information in all aspects is integrated to accurately control the on-off state of the sub-module, so that the operation effect of the system is improved under the complex working condition, and the real-time performance and predictability of control are considered through combination of closed-loop adjustment and feed-forward compensation, so that the effectiveness of control is improved.

A multiple input converter for outputting power from AC power or a battery to positive and negative direct current (DC) buses is provided. The multiple input converter includes at least one bridge arm unit and a bidirectional DC-DC conversion unit. The bridge arm unit corresponds to one phase of the alternating current (AC) power and includes an upper and lower bridge arms that can independently form a two-level converter. In a battery mode, the upper and lower bridge arms discharge power from the rechargeable battery to the positive and negative DC buses, and the bidirectional DC-DC conversion unit discharges power from the rechargeable battery to the positive and negative DC buses or balances voltages of the positive and negative DC buses. In a mains mode, the bridge arm units are connected to the AC power. The bidirectional DC-DC conversion unit determine whether to charge or discharge according to load conditions.

The invention discloses a low-cost charging pile topology for a fast charging-slow discharging scene of an electric vehicle and a modulation strategy of the low-cost charging pile topology. According to the low-cost charging pile topology, a group of half-bridge type shunt diodes are connected in parallel to each phase of main bridge arm of a traditional T-shaped three-level converter. In the discharging mode, the charging pile is consistent with a traditional T-type three-level operation state, and works in a slow-release scene with rated power and below. In the charging mode, the charging pile continuously shunts the main bridge arm power device by using the additionally arranged shunting diode, so that the current stress and thermal stress of the main bridge arm power device are reduced; and through a self-adaptive modulation strategy of three-level / two-level modulation mode switching, the loss distribution of a power device is optimized, the active power output capability of the charging pile in a charging mode is improved, the fast charging operation of the charging pile with over-rated power is realized, the equipment capacity utilization rate of the charging pile is fully excavated, and the method has remarkable engineering application value.

The invention relates to the technical field of parallel three-level converter control, and provides a parallel three-level converter model prediction control method and system, and the method comprises the steps: enabling a parallel three-level converter to be modeled as a series connection of an equivalent voltage source and an equivalent filter inductor according to the Thevenin theorem, enabling the parallel three-level converter to be equivalent to a five-level converter, and enabling the parallel three-level converter to be connected in parallel; a three-layer optimization control strategy is adopted; in the first layer, a candidate vector closest to a reference voltage vector is selected as an optimal five-level basic vector so as to track a parallel total output current; in the second layer, a redundant five-level voltage vector is selected to balance the neutral-point voltage; and in the third layer, selecting the candidate switching state which enables the circulating current suppression value function to be the minimum as the optimal redundant three-level switching state so as to suppress the circulating current. The method can effectively reduce output current harmonics under low switching frequency, and balance of neutral-point voltage and effective suppression of circulating current are realized to ensure safe and stable operation of a parallel converter system.

The invention relates to the technical field of modular multilevel converters, and provides an MMC fault diagnosis method, system and device based on a sorting voltage-sharing algorithm. Comprising the steps that according to measurement data of the modular multilevel converter, a theoretical value and an actual value of bridge arm voltage of the modular multilevel converter are obtained through calculation, the theoretical value and the actual value are compared with a first alarm threshold value, and a corresponding bridge arm fault and a fault type are determined; calculating the number of fault sub-modules according to the bridge arm voltage actual value and the bridge arm voltage theoretical value; judging the switching number of the fault bridge arm sub-modules, and controlling and adjusting the bridge arm sub-modules to be switched on according to the fault type and the number of the fault sub-modules; and calculating a capacitor voltage minimum difference value, comparing the capacitor voltage minimum difference value with a second alarm threshold value, and determining a fault sub-module. According to the multi-tube fault diagnosis method, the problem that the fault positioning performance is poor under the light load working condition is solved, and the sub-module positioning performance in the full power range is improved.

A system may include a multi-level power converter comprising a power inductor and a plurality of switches and a controller configured to control the plurality of switches such that the multi-level power converter generates a regulated output voltage from an input voltage to the multi-level power converter, monitor an average inductor current through the power inductor, and operate the multi-level power converter in one of a continuous conduction mode and a discontinuous conduction mode based on the average inductor current.

The invention is suitable for the technical field of flexible power distribution of a power system, and discloses a modular multilevel converter multi-objective optimization method, system and device based on model predictive control and space vector modulation, and a medium. Obtaining an output current reference value and a circulating current reference value; obtaining a reference voltage vector based on the output voltage reference value, and screening out a plurality of groups of redundant voltage vector sequences through a space vector diagram; performing performance evaluation through rolling optimization by combining each redundant voltage vector sequence with a multi-target cost function to obtain an optimal voltage vector sequence; and on the basis of the optimal voltage vector sequence and the corresponding duty ratio, a switching signal for driving each sub-module switching device of the MMC is generated, and multi-target cooperative control is realized. The three targets of reference output current tracking, circulating current suppression and sub-module capacitor voltage balance are met, and the dynamic response capability, efficiency and reliability of MMC system operation are comprehensively improved.

The invention discloses a display device, a control method thereof and display equipment, and relates to the field of display, the display device comprises a time schedule controller, a power management module, a display panel and a plurality of level converters, the display panel comprises a plurality of pixel areas, and each pixel area comprises at least one pixel row; the time sequence controller is connected with the time sequence input end of each level translator, the power supply management module is connected with the voltage input end of each level translator, each pixel region is connected with the time sequence output end of one level translator, and different pixel regions are connected with different level translators; the level converter is used for receiving a time sequence reference signal sent by the time sequence controller and is also used for receiving a target grid high-level voltage sent by the power supply management module; the level shifter is further configured to generate a timing control signal based on the target gate high-level voltage and a timing reference signal. The problem that the brightness display of the display panel is not uniform is solved.

Disclosed is a test device to test the operation of an MMC by fabricating only one or several SMs constituting the MMC testing under real-time operating conditions. The test device for a modular multi-level converter (MMC) includes a simulation model of an MMC having at least one arm to which sub modules (SMs) are serially connected, at least one test target SM among the serially connected SMs being replaced with a dependent voltage source; an arm current simulation circuit including an equivalent SM that implements the test target SM as actual physical hardware and an inverter that supplies current to the equivalent SM; and a control unit configured to control the arm current simulation circuit to correspond to an operation of the simulation model and set a voltage corresponding to a charge / discharge voltage of the equivalent SM of the arm current simulation circuit to the dependent voltage source.

The invention discloses a fault current analysis method and system for a multi-terminal flexible DC circuit, and the method comprises the steps: analyzing fault current data when the DC side of a modular multilevel converter is short-circuited, and obtaining time sequence segmentation rule data; performing equivalent processing on the modular multilevel converter based on the segmentation rule data to obtain an equivalent circuit model comprising an RLC series circuit and a time-varying current source; constructing a second-order differential equation for describing the fault current according to the equivalent circuit model, and solving the second-order differential equation to obtain a fault current expression containing dynamic alternating current feed-in; constructing a fault equivalent network of the multi-terminal flexible DC circuit; and constructing a state-space equation of the fault equivalent network based on a branch current method and the fault current expression, and solving the state-space equation to obtain fault current data of the multi-terminal flexible DC circuit. According to the method, the accuracy of fault analysis is improved.

The invention discloses a multi-terminal flexible direct current transmission line protection method based on injection signals, and relates to the technical field of power distribution network line protection. After the bipolar short-circuit fault is detected, the modularized multi-level converter is controlled to enter an active current limiting mode, and the fault current is limited to be 1.1 times of rated current, so that the impact on equipment is reduced; a main control station injects current sinusoidal signals with different angular frequencies twice, current and voltage signals of a port of the main control station are extracted, the impedance amplitude difference under the two angular frequencies is obtained, and the fault section protection method based on the impedance amplitude difference is established. Through a cut-and-trial method, the number of current-limiting reactors through which fault current flows is calculated, a criterion for matching and detecting a fault line section is established, and the fault section is isolated by a protection action. According to the method, synchronous communication is not needed, fault line protection can be realized under high resistance and noise, and the protection reliability and the recovery efficiency of the complex topology multi-terminal flexible direct current power grid are remarkably improved.

The invention provides a unified carrier reverse lamination modulation method based on a three-level converter. The method comprises the following steps: acquiring the current three-phase reference voltage of the three-level converter; calculating a zero-sequence component of a current modulation strategy according to the three-phase reference voltage and the current modulation strategy; determining a three-phase modulation wave according to the three-phase reference voltage and the zero-sequence component; and generating a switching tube driving signal of each bridge arm in the three-level converter according to the three-phase modulation wave. According to the invention, through a unified zero-sequence component calculation mode, on the basis of carrier reverse-phase laminated modulation, compatibility with different modulation strategies is realized, a zero-sequence vector calculation process is omitted, a space vector region does not need to be judged, occupation of calculation resources when the modulation strategies are realized is effectively reduced, and the implementation efficiency of the modulation strategies is improved. And transient oscillation during strategy switching is suppressed.

The invention discloses a flexible direct-current power transmission system and a fault ride-through method and system thereof. The flexible direct-current power transmission system comprises a main control module, and a new energy sending-out system, an alternating-current energy consumption device, a sending-end converter, a direct-current circuit breaker, a receiving-end converter and a receiving-end alternating-current power grid which are connected in sequence, the direct current circuit breaker is deployed on a direct current power transmission line between the sending end converter and the receiving end converter, and the receiving end converter is a modular multi-level converter formed by cascading a plurality of half-bridge sub-modules with damping branches; the main control module is in communication connection with the half-bridge sub-modules, the direct-current circuit breaker and the alternating-current energy consumption device and used for controlling the damping branches of the half-bridge sub-modules in the running state, the direct-current circuit breaker and the alternating-current energy consumption device to act when a direct-current fault occurs so as to restrain direct current and adjust direct-current voltage to be within a set voltage range. Therefore, no-locking fault ride-through is completed. According to the invention, high-reliability and low-cost DC fault ride-through can be realized.

The invention provides a neutral-point potential control method and system for a three-level converter, and relates to the technical field of intelligent control, positive bus voltage and negative bus voltage are sampled, a voltage deviation value is calculated, an additional control quantity is generated according to the voltage deviation value and a symbol of alternating current, and the additional control quantity is obtained through a symbol function and proportional control processing; performing amplitude limiting processing on the additional control quantity to obtain an amplitude-limited additional control quantity; superposing the amplitude-limited additional control quantity on the positive modulation wave, negating the amplitude-limited additional control quantity, and superposing the negated amplitude-limited additional control quantity on the negative modulation wave to obtain a final positive modulation wave and a final negative modulation wave; comparing the final positive modulation wave and the final negative modulation wave with a carrier wave, and generating a driving signal of the power device; and the on-off of the switching device is controlled according to the driving signal, so that a corresponding level is output to realize neutral-point potential balance. According to the invention, neutral-point voltage low-frequency fluctuation and direct-current offset suppression can be realized at the same time.

An interleaved flying capacitor multi-level converter includes a plurality of arms and a phase-shift PWM generation circuit. Each arm includes a flying capacitor multi-level circuit having an upper arm and a lower arm coupled at a middle node. The upper arm includes a plurality of serially coupled upper arm switches and the lower arm includes a plurality of serially coupled lower arm switches. One capacitor is correspondingly coupled between every two upper arm switches and every two lower arm switches. The phase-shift PWM generation circuit generates a plurality of switch control signals to respectively control the plurality of upper arm switches and the plurality of lower arm switches.

Disclosed herein is a multilevel converter (50) for voltage conversion between a three-phase AC voltage and a DC voltage, comprising three converter arms (58), each having a first end (60) for connecting to a corresponding phase of a three-phase AC voltage source (52) and a second end (62), wherein each converter arm (58) comprises a plurality of sequentially interconnected modules (64), a main energy store (54) having a positive terminal (76) connected or connectable to a positive conduction line (78) and a negative terminal (80), a switching arrangement (84), a control system (92), configured to establish a positive state, in which the negative conduction line (82) is connected with a star point (56) of said three-phase AC voltage source (52) and the positive conduction line (78) is connected with the second end (62) of one or two converter arms (58) to which a positive phase voltage is currently applied, and a negative state, in which the positive conduction line (78) is connected with said star point (56) of said three-phase AC voltage source, and the negative conduction line (82) is connected with the second end (62) of one or two converter arms (58) to which a negative phase voltage is currently applied.

The invention belongs to the field of two-level converter small signal and impedance modeling, and discloses a VSC impedance analysis method in a superposition oscillation component scene and a related device. The method comprises the following steps of: superposing an alternating-current voltage oscillation component, and establishing each steady-state quantity frequency domain model; establishing a main circuit steady-state frequency domain model; establishing each small semaphore frequency domain model based on the main circuit steady-state frequency domain model; establishing a main circuit small signal frequency domain model; constructing a PLL controller small signal model, a DC voltage controller small signal model and an AC current controller small signal model; constructing a small signal model of the alternating current modulation signal; and calculating the port impedance of the two-level current converter in the scene of superposition of the oscillation components based on a small signal model of the alternating-current modulation signal. According to the method, the VSC port impedance in the scene of superposition of the oscillation components can be accurately analyzed, and key technical support is provided for oscillation mechanism analysis and stability improvement of new energy access to a weak point network.

A submodule (120) for a modular multilevel converter (102) includes a bridge cell (220) and an active power decoupling module (140). The bridge cell includes an energy storage capacitor (222) and a first bridge pair of power switches (224, 224') connected in parallel with the energy storage capacitor. The active power decoupling module includes first and second terminals (150, 152), a second bridge pair (169) of power switches (170, 170') connected between the first and second terminals and in parallel with the energy storage capacitor, and an inductor (166) connected in series with a power decoupling capacitor (168) to a junction between the power switches of the second bridge pair of power switches.

The invention relates to the technical field of power grid resource scheduling, in particular to a charging station resource scheduling system and method based on bridge arm balance, and the system comprises a switching control module, a charging and discharging adjustment module, a common bus switching module and a bridge arm balance control module. The switching control module monitors the power grid three-phase load state corresponding to the charging station in real time, and generates a phase switching instruction when detecting that the unbalance degree exceeds a threshold value; the common bus switching module receives the phase switching instruction and dynamically accesses the input side of the charging station to a target power grid phase; the charging and discharging adjusting module generates a modulation signal based on the power distribution instruction, and controls the switching time sequence of power subunits in the commutation power module; and the bridge arm balance control module comprises a three-phase bridge arm circuit, generates a compensation signal according to the voltage deviation and feeds back the compensation signal to the charging and discharging adjustment module, so as to maintain the energy balance of the three-phase bridge arm circuit of the charging station. According to the invention, the problem that the reliability of the system is reduced due to the dynamic unbalance of the bridge arm energy of the multi-level converter is effectively solved.

The invention relates to a driving circuit and a driving method of a display panel and the display panel, the driving circuit comprises a time schedule controller, a memory and a level translator, the time schedule controller is provided with a first communication port, a second communication port and a third communication port, the second communication port is connected with the memory, the third communication port is connected with the level translator, and the level translator is connected with the memory. Wherein the time schedule controller is used for acquiring a refresh rate adjustment instruction, acquiring an overcurrent protection parameter corresponding to the refresh rate adjustment instruction, and sending the overcurrent protection parameter to the level translator; the memory is used for storing at least two over-current protection parameters; and the level converter is used for setting an overcurrent protection function of the display panel according to the overcurrent protection parameter, so that the width of a detection window of the overcurrent protection function is adaptive to the pulse width of the vertical clock signal under the target refresh rate. Through the circuit, the technical problem that the design of a fixed overcurrent protection parameter is difficult to adapt to a display panel with a variable refresh rate is solved.

The utility model relates to a distributed photovoltaic power station main converter, and belongs to the field of photovoltaic power generation. The main current transformer comprises a T-type three-level current transformer and a Buck-Boost current transformer; one end of the main converter is connected with a power grid, and the other end is connected with a photovoltaic module system and energy storage equipment of the distributed photovoltaic power station; the T-type three-level converter comprises three bridge arms, two output capacitors and the like; each bridge arm is provided with four power switch tubes; the two output capacitors are connected in series, and the connection point is called as the midpoint O of the T-type three-level converter. The Buck-Boost converter comprises a direct current inductor, two power switch tubes and the like; and one end of the direct-current inductor is connected with the midpoint O so as to realize midpoint potential automatic balance. The system is low in cost, simple in control, small in current harmonic wave, low in power consumption, and capable of realizing fast and automatic balance of neutral-point potential, thereby effectively coping with the influence of illumination and network voltage fluctuation on system control, and realizing fast and stable control of a distributed photovoltaic power station.

The invention provides a hybrid direct-current power transmission system, a system control method and a hybrid direct-current power transmission device.The system comprises a sending-end converter and a receiving-end converter which are used for being electrically connected with an alternating-current bus, the sending-end converter comprises a positive-pole converter and a negative-pole converter, the positive-pole converter is used for being electrically connected with a positive pole of a direct-current line, and the negative-pole converter is used for being electrically connected with a negative pole of the direct-current line; the negative current converter is electrically connected with the negative electrode of the direct current line, and the positive current converter comprises a full-control current source current converter; the cathode converter comprises a modularized multi-level converter and / or a controllable commutation current source converter, and the anode converter and the cathode converter both comprise full-control devices; the receiving-end converter is electrically connected with the sending-end converter through a direct-current line, and the receiving-end converter is a converter controlled by direct-current voltage. According to the system, a CCSC and HCC / MMC hybrid high-voltage direct-current power transmission system is adopted at the sending end, and hundred percent new energy sending of an alternating-current bus is achieved.

A bi-directional level shifter is described that combines an input / output (I / O) signal and a direction control signal into a single signal, thereby reducing the number of total pins. The combination of I / O and direction is encoded by different voltage levels, and thus no information is encoded by currents. This advantageously keep power consumption low compared to conventional designs. Moreover, because a predetermined voltage encoding is used in which the bi-directional level shifter is configured to detect and respond via hardware, transitions between data flow are detected very quickly.

A level shifter includes a first buffer circuit, a first capacitor, a second capacitor, a cross-coupled inverter, and a second buffer circuit. The first buffer circuit is configured to drive a first input signal and a second input signal with a first high power supply voltage and a first low power supply voltage to generate a first main driving signal and a second main driving signal. The first capacitor, the second capacitor, and the cross-coupled inverter are configured to generate signals of a first node and a second node based on the first and second main driving signals. The second buffer circuit is configured to drive the signals of the first and second nodes with a second high power supply voltage and a second low power supply voltage to generate a first output signal and a second output signal.

The invention discloses an operation parameter optimization method and system for improving the overload capacity of a power electronic converter, and belongs to the technical field of power electronics. The method comprises the following steps: constructing an output current model considering current ripples in a switching period, and obtaining an accurate current waveform expression; calculating conduction loss and switching loss of each power device in each switching period based on the model; under a set temperature rise or loss constraint condition, parameters such as direct-current voltage and switching frequency are optimized through an optimization algorithm, and the optimized parameters are applied to converter operation. The method solves the problem that loss estimation is inaccurate due to the fact that a traditional simplified model ignores current ripples, through precise modeling, refined loss calculation and scientific parameter optimization, the thermal stress of a device is remarkably reduced, the overload capacity of the converter is improved, the method is suitable for various topologies such as a two-level converter, a three-level converter and a direct-current converter, and the method has wide application prospects. The method can be widely applied to the fields of new energy and rail transit.

A battery storage system includes a multilevel-converter and a plurality of storage sections. Each storage section includes at least one holding means configured to hold at least one battery and at least one cable with at least one connector configured to electrically connect at least one of the batteries. The multilevel-converter includes a plurality of converter modules connected in series with each other and each converter module has at least one bypass switch configured to bypass the converter module and a battery switch configured to disconnect the battery at the same time when the bypass switch is on. The battery storage system further includes a controller with means for detecting the presence of a battery in each storage section and means for configuring the switches of the plurality of converter modules based on the presence of batteries such that the plurality of converter modules provides a required voltage.