51results about How to "Solve the circulation problem" patented technology

The invention discloses a large-capacity battery converter and control method thereof. The converter of the invention comprises several branch single stage type DC/AC converter modules parallel to one another. Each battery cluster (Battery Cluster BC) converges energy to an AC bus via each branch single stage type DC/AC converter module to be transformed in voltage in order to connect to an AC grid or to operate independently with load. The invention solves the circular current and uniform current problems brought by serial and parallel connection of the battery cluster, and adopts the technology of module combination and alternate balance to effectively improve the system efficiency under low power and power quality at the AC and DC sides and to realize balanced use of the battery cluster. Each battery branch can conduct intelligent charge and discharge management and the control function and the protection function are configured independently to ensure the largest availability of the system. The invention has simple structure, small volume, small energy loss, easy modularization, high reliability, small output harmonic wave, good system expansibility and low requirement to insulating ability of the converter and can operate with reduced capacity when the unit is in failure. The control method of the large-capacity battery converter of the invention is convenient and simple in operation and easy in realization.

At present, strong extra-high voltage direct-current electric power transmission grids are built in China. Energy is needed to be stored in a storage battery and then transmitted to the grid or the storage battery is needed to be hung on the direct-current electric power transmission grid because of the randomness of power supply from new energy resources. However, a bidirectional direct-current converter has the characteristic of implementing bidirectional flow of the energy through a set of hardware, so that the bidirectional direct-current converter which is suitable for energy transmission between the high voltage electric power transmission grid and the storage battery becomes a hot topic in the research. The invention provides a bidirectional direct-current converter with high buck-boost ratio, which can be applied to high-voltage and high-power applications. Through the invention, the problem of the flow of the energy among modules after the original bidirectional converter is connected in series or parallel. The circuit of the bidirectional direct-current converter is characterized in that a main circuit is a two-stage bidirectional converter, wherein the front stage is an original-edge inversion auxiliary edge rectification type direct-current converter, and the rear stage is a BUCK-BOOST type bidirectional converter. The control mode is that each module is independently controlled so that staggered-frequency control is realized, electromagnetic interference is reduced and the voltage isolation level of drive signals is effectively lowered.

The invention discloses an energy feedback unit and an energy feedback method. The energy feedback unit comprises a three-phase input wire voltage sampling module, a current sampling module, a busbar voltage sampling module and a control module, wherein the three-phase input wire voltage sampling module is used for sampling the voltage of a power grid and transmitting the voltage to the control module, the current sampling module is used for sampling the current of the power grid and transmitting the current to the control module, the busbar voltage sampling module is used for sampling the busbar side voltage of the energy feedback unit and transmitting the busbar side voltage to the control module, and the control module is used for performing an automatic phase distinguishing and locking algorithm according to a signal transmitted by the three-phase input wire voltage sampling module and performing a double-closed-loop control algorithm and a zero sequence current compensation control algorithm according to signals transmitted by the current sampling module and the busbar voltage sampling module so as to generate a PWM driving signal for driving a first inverter bridge. The energy feedback unit and the energy feedback method have the advantages that the zero sequence current compensation algorithm is adopted for eliminating loop current, the power supply reliability is improved, the phase position of power grids can be automatically identified, and indifference grid connection is achieved.

A production method for three cleaving transmission transformer belongs to transformer technology field and solves impedance matching problem of three low press windings. It counts electric field, magnetic field, short circuit impedance, short circuit intensity and leak magnetic field of transformer to match impedance of three low press windings. a. Count voltage and current parameter. b. Select iron core parameter. c. Select loop parameter. d. Count short circuit impedance. e. Count spoilage, temperature rise and mechanical power. f. Confirm structure collocation type and parameter. It finds the rule about the three cleaving transmission transformer to solve the problem of high voltage winding circumfluence and keep the transformer with natural function at all kinds of load condition. When satisfied the coequal load condition, it can reduce 50% area and 15-20%spoilage with high over loading ability and its sequential course can reach to 115% of rated capability.

The invention provides a lithium battery system for multi-path parallel connection and a control method thereof. The voltages among multiple paths can be kept consistent, the problems of circular current or large current impact and the like can be solved, and the service life of a battery can be prolonged. The lithium battery system comprises a BMS and a plurality of branch modules, and the branchmodules are connected in parallel. Each branch module comprises a lithium battery module formed by connecting single battery cells in series. The lithium battery system further comprises an equalization module, a charging module and a discharging module which are connected in parallel and are then connected with the BMS. The total positive end of the branch modules after parallel connection is connected with the BMS and one end of a node formed by parallel connection of the equalization module, the discharging module and the charging module, and the total negative end of the branch modules after parallel connection is connected with the BMS and the other end of the node formed by parallel connection of the equalization module, the discharging module and the charging module. Each branch module further comprises a fuse, a branch current sensor and a branch relay, wherein the fuse, the lithium battery module, the branch current sensor and the branch relay are sequentially connected in series, and the branch current sensor and the branch relay are both connected with the BMS.

The invention relates to a coordination control method of a large-scale energy storage device. A coordination controller is used for controlling the startup and the shutdown of bottom layer control units; the bottom layer control units are used for feeding back the fault and a running state to the coordination controller; the coordination controller is used for monitoring the state of a bottom layer module and the allowable maximum charging/discharging power of a storage battery; a power control unit is used for distributing the power rating to each bottom layer control unit according to the proportional distribution; in the off-grid operation, a power balance control manner capable of avoiding the circulation of an inverter is adopted; and the balance of the storage battery is performed in an automatic balancing manner in a system shutdown or standby state. The coordination control method has the benefits that the difficult problem of multi-objective coordination control of the large-scale energy storage device is solved, a basis is laid for the research and development, and the popularization of the large-scale energy storage device, and the theoretical significance and the engineering practical significance are very important.

The invention relates to an energy balanced control method and device for an energy-storage power supply system and a balanced system. The method comprises the following steps: during charging balanced control, acquiring actually stored electric energy of each energy storage module, and finding the minimal electric energy; calculating an error value between each of the other electric energy and the minimal electric energy, and judging the amplitude of each of the error values and a first set balanced threshold value, wherein for each of the error values exceeding the first set balanced threshold value, corresponding energy storage branches are controlled to perform charging according to corresponding PWM (Pulse-Width Modulation) control pulses; and during discharging balanced control, finding the maximal electric energy, and calculating an error value between the maximal electric energy and each of the other actual electric energy, wherein for each of the error values exceeding a second set balanced threshold value, corresponding energy storage branches are controlled to perform discharging according to the corresponding PWM control pulses. In the previous two situations, duty ratios of the PWM control pulses are in reverse proportion to the error values. Corresponding charging and discharging energy distribution is performed according to the energy state of each energy storagemodule, so that energy balanced control is realized.

The embodiment of the invention provides a battery system and an electric vehicle, and relates to the technical field of battery application. The battery system comprises at least two battery branchesand a controller, wherein each battery branch comprises a battery and a regulating unit, each battery branch is connected in parallel with each other, the battery in each battery branch is connectedin series with the regulating unit in each battery branch, and the controller is electrically connected with the regulating unit in each battery branch; The controller is used for regulating the resistance value of the regulating unit in each battery branch according to a pre-established mathematical model, thereby regulating the output current of each battery branch. The battery system and the electric vehicle provided by the embodiment of the invention can solve the problem that the output current distribution of each branch of the battery system is unbalanced.

The invention discloses a controller of an energy feedback device. The controller of the energy feedback device is used for controlling the magnitude and direction of transmission power of a regenerative electric energy feedback device; the controller of the energy feedback device comprises an analog input unit and a reactive power calculation unit; the analog input unit is used for obtaining alternating current bus voltage of a traction station, incoming line current of the traction station, alternating current bus voltage of a main station and incoming line current of the main station; the reactive power calculation unit outputs the corresponding reactive power according to a target value of a power factor of the traction station and compensates the power factor of the traction station;or, in order to improve a power factor of the main station, the regenerative electric energy feedback device is controlled to output given reactive power. The invention further provides a traction power supply system for rail transit and a circulating current suppression method thereof, the reactive power is output by adjusting the regenerative electric energy feedback device, the alternating current output voltage of the regenerative energy feedback device is stabilized, and the circulating current between the regenerative energy feedback device and a traction rectifier is avoided.

The invention provides a synchronous pulse-based multi-converter control method, which comprises the following steps of: 1) selecting any converter from a microgrid as a master converter, periodicallychanging the phase of the master converter by power frequency, and taking the rest converters as slave converters; 2) when the phase of the main converter is within [theta0, theta0 + delta theta], continuously sending a synchronous pulse signal out; 3) enabling the slave converters to set the phases of the slave converters to realize phase synchronization among the converters. Compared with a traditional phase locking method, the method has the advantages that the problem that the phase locking performance is reduced due to three-phase imbalance of a synchronous signal source, high harmonic content, errors of a voltage sensor and the like is solved; according to the method provided by the invention, a phase gradual approximation method is adopted when the slave converter performs synchronization operation, and the phase is not directly assigned, so that the synchronization of the phase is ensured, and the circulation problem possibly caused by direct assignment is avoided.

The invention designs an IGBT multi-parallel module driving circuit, which is composed of a plurality of IGBT single-module driving circuits. The IGBT single-module driving circuit comprises an inverter open-drain output module U1, an optical coupler U2, a resistor R1, a resistor R2, a resistor R3, a resistor R4, a resistor R5, a resistor R6, and a resistor R7, a non-polar capacitor C1, a non-polar capacitor C2, a non-polar capacitor C3, and a non-polar capacitor C4, an NPN tube silicon triode Q1 and a PNP tube silicon triode Q2, a bidirectional voltage-regulator tube D1, and a voltage-regulator diode D2. The driving circuit has the advantages of avoiding a circulation problem, meeting synchronous operation of the test, and being good in the current sharing effect.

The invention discloses a power-on method of a battery system, the battery system and a readable storage medium. The method comprises the following steps: receiving working state data of all battery packs; judging whether the working state of the battery pack is normal or not according to the working state data; if the judgment result is that the working state of the battery pack is normal, obtaining the number of the battery packs in the battery system; and determining a corresponding power-on strategy according to the number of the battery packs, and controlling the battery packs to be powered on according to the power-on strategy. According to the invention, the circulating current problem when the parallel battery pack is electrified can be solved, and the service life of the battery pack is prolonged.

The invention discloses a high-capacity combined converter used for the electric energy storage, comprising two-level three-phase voltage source type converters (VSC), a chopper and a superconducting inductor; alternating current sides of the two-level three-phase voltage source type converters are connected mutually through an equivalent inductance resistor LR, and then connected to a power grid through multiple groups of coil transformers T; direct current sides are linked to a voltage-stabilizing capacitor C and an equivalent storage battery B in parallel, and then linked with the two-quadrantal chopper in series; the two-quadrantal chopper is connected with the superconducting inductor through a flat wave inductor L1 to form a bidirectional voltage source type converter. For adopting the method of cascading two-level three-phase voltage source type converters and matching up with the chopper, the discharging and charging controls of the superconducting magnet are realized, the rapid flow of energy can be flexibly realized, and the harmonic wave content is effectively reduced; furthermore, the pressure resistance, the flow resistance and other problems of a switch tube in the process of high power conversion are solved, the circulation problem existing in the prior art is avoided, and the high power conversion is realized.

The invention discloses a composite circulating current suppression method and device for a shore power supply system, which can solve the problem of circulating current in a shore power supply parallel system. The composite circulating current suppression method comprises a circulating current suppression method based on the combination of average current control and centralized control, and theamplitude, frequency and phase of the output voltage of a shore power supply are controlled through a current equalization control method in the control process. The centralized control is realized through a coordination controller, the dq coordinate system modulation waves are uniformly generated and are issued to each variable frequency power supply central controller, each central controller receives the dq axis modulation waves Umd, and Umq is divided by the average value of the direct current bus voltage of each variable frequency power supply and then is superposed with the compensationamount generated by the current equalization control to achieve the purpose of circulating current suppression of the parallel shore power systems, so that the stable operation of the shore power systems is guaranteed. In addition, the composite circulating current suppression device for a shore power supply system is easy to implement and has the advantages of being low in cost and high in reliability, being easy to expand and the like.

The invention discloses a method for controlling a storage battery shared manager, which comprises the following steps: accessing all batteries into a system, and acquiring related data in real time by using a DSP of the storage battery shared manager; using a double-loop control strategy for direct-current output; dividing the system discharge current to calculate the average discharge current ofeach group of batteries of the system, performing average value operation on the discharge current of each group of batteries, and performing subtraction on the average discharge current of each group of batteries and the discharge current of each group of batteries to calculate a current difference value; multiplying the mean value of the current difference values by a proportionality coefficient and then superposed on a voltage loop. The DSP in the control system is used for detecting the charging and discharging current, the battery voltage, the system output voltage and the system charging and discharging current of each group of batteries, the working modes are divided into four modes, namely the standing mode, the charging mode, the discharging mode and the protection mode, the stable operation of the system is ensured, and the problem of system battery circulation can be avoided.