260 results about "Dc bus capacitor" patented technology

An AC/DC/AC power converter is constructed without using any electrolytic capacitor, such that it is more compact, durable and reliable. This converter only required a small capacitance for its DC link and this capacitor can be easily obtainable with other types of capacitors such as film or ceramic type. The system further includes means to disconnect both input and output to this DC bus capacitor. A controller capable of fast monitoring the DC bus voltage is also able of quickly disconnecting the capacitor out of either input or output energy path to prevent the capacitor from being charged to over-voltage. The controller also possesses capability of re-connecting the disrupted energy path once the DC bus voltage returns to normal.

Examples of the present invention include high electric energy density polymer film capacitors with high dielectric constant, low dielectric dissipation tangent, and low leakage current in a broad temperature range. More particularly, examples include a polymer film capacitor in which the dielectric layer comprise a copolymer of a first monomer (such as tetrafluoroethylene) and a second polar monomer. The second monomer component may be selected from vinylidene fluoride, trifluoroethylene or their mixtures, and optionally other monomers may be included to adjust the mechanical performance. The capacitors can be made by winding metallized films, plain films with metal foils, or hybrid construction where the films comprise the new compositions. The capacitors can be used in DC bus capacitors and energy storage capacitors in pulsed power systems.

The invention relates to a double-fed wind generating set control system and a stable control method. An energy storage cell is added at the DC side of a back-to-back converter of a double-fed motor, the DC side energy storage cell is connected to a DC bus capacitor by the double-way DC/DC cell side converter, and a third control circuit controls the cell converter to charge and discharge the energy storage cell. The cell can send active power and adsorbs the active power under the necessary condition, and residual energy is stored in the energy storage cell during breakdown. The invention provides the guarantee for the low voltage of wind power generation and improves the safety and stability of the voltage of the DC side of the converter of the double-fed wind generating set, thus further accelerating the better development of wind power generation.

The invention discloses a cascaded photovoltaic grid-connected inverter and a control method. The cascaded photovoltaic grid-connected inverter has the advantages of high voltage level, high power level, high power quality and the like, and can realize direct high voltage grid connection without any transformer to save cost and an occupied area. The inverter comprises a photovoltaic array and a plurality of cascaded unit bodies. The photovoltaic array comprises a plurality of photovoltaic units of which each is connected with the input side of a corresponding unit body. Each unit body is a single-stage single-phase photovoltaic grid-connected inverter which comprises a DC bus capacitor and an H bridge inverter circuit, wherein the DC bus capacitor is connected in parallel to the input endof the single-stage single-phase photovoltaic grid-connected inverter; and the H bridge inverter circuit is connected in parallel with the DC bus capacitor.

A method and system for controlling a power converter system with first, second, and third phase legs with respective first, second, and third associated phase currents determine direction of current flow in at least two phase legs and switch states of the power converter system in response to the current flow directions to reduce ripple current in a connected direct current (DC)-bus capacitor.

A system and method for pre-charging the DC bus of a utility connected power converter. In one embodiment, a full-wave rectifier circuit is coupled to the utility grid through an isolation transformer and circuit protector. The rectifier circuit output is connected to the DC bus of the power converter to provide a pre-charging current to the DC bus capacitors. The output from the rectifier circuit also supplies power to the control circuit power supply for the converter. When the control circuit closes the contactor of the converter system and activates the converter, the voltage across the DC bus capacitors is increased above the level of the rectified power grid voltage provided at the output of the pre-charge circuit. This reverse-biases the rectifier diodes, placing the pre-charge circuit into an inactive state. The impedance of the isolation transformer limits the in-rush current into the DC bus capacitors during the pre-charge.

The invention discloses a comprehensive series compensation voltage ride-through device of a wind turbine generator. The comprehensive series compensation voltage ride-through device of the wind turbine generator is mounted on a three-phase circuit between a wind driven generator and a control device of the wind driven generator and a PCC (point of common coupling) of a power grid, and comprises a three-phase standard transducer, a series coupling transformer, a two-way charge-discharge circuit, a DC bus capacitor and a by-pass switch. With the adoption of a dynamic voltage restorer, a chopper circuit and a super capacitor with high-capacity energy storage in the power electronic technology, low voltage ride through, high voltage ride through and harmonic compensation are realized under the condition that generator terminal voltage drops off during power grid fault, generator terminal voltage rises due to excessive reactive power of the power grid and the harmonic content of the power grid is overlarge, the wind turbine generator is prevented from being separated from the grid, and harmful effects of harmonic are prevented; and moreover, a conventional wind turbine generator is not required to be transformed, and the device can be taken as an independent control module and added at the stator output port of the wind turbine generator and is convenient to mount.

The invention discloses a control method for an electric automobile participating in grid frequency modulation based on V2G technology. A charge/discharge circuit is a two-stage converter circuit, which comprises a PWM rectification circuit and a matched LC filter and a Buck-Boost conversion circuit, wherein the two circuits are connected through a DC bus capacitor; the PWM rectification circuit rectifies a network voltage into a 700V DC voltage, AC-side harmonic waves are filtered through the LC filter, and the PWM rectification circuit is connected with a power grid through a network-side inductor; and the Buck-Boost conversion circuit converts the 700V DC voltage into a 60V DC voltage, and is connected with an electric automobile directly. The method adopts an AC/DC control module and a DC/DC control module, and meanwhile, enables a frequency modulation control module to be embedded into the DC/DC control module; and charge and discharge power reference values of a power battery are given through the frequency modulation control module, and a current transformer makes a response to realize primary and secondary frequency modulation of the power grid.

The invention discloses a permanent magnet synchronous motor control algorithm for improving the transient stability of a small capacity DC bus capacitor voltage. According to the difference between a DC bus voltage and an absolute value of a grid voltage, a given component of a motor direct-axis current is adjusted, the transient stability of the DC bus voltage is improved, and the distortion rate of a grid input current is reduced. A small capacity thin-film capacitor is used for replacing a power factor correction circuit to extend the service life of the entire system. However, the capacitance of the thin-film capacitor is small and the capacitor voltage is susceptible to motor back electromotive force, which results in a series of problems of a high distortion rate of the grid input current and the like. For this reason, the invention adjusts the given component of the direct-axis current based on the difference between the DC bus voltage and the absolute value of the grid voltage, and adopts an internal model controller or a repetitive controller or a PR controller as a current controller to realize the fast tracking of period demand signals by d-q currents of the motor.

The invention relates to an inverter integrated into a motor. The inverter is characterized in that the inverter is integrated into the rear side of the motor; the bearing of a reducer output shaft is arranged on the inverter; a wire connector, a DC busbar, and a Y capacitor are arranged below a DC bus capacitor; the wire connector is installed on a main box; an air conditioner fuse is fixed to the embedded nuts of the wire connector; one end of the air conditioner fuse is connected with the negative extension end of the DC busbar; the other end of the air conditioner fuse is connected with the negative wire harness of an air conditioner connector; the DC busbar is electrically connected with the terminal of a DC connector and is connected with one end of the air conditioner fuse and the positive wire harness of the air conditioner connector at the wire connector. The inverter can be well integrated with the motor and the reducer, and the entire integrated device occupies small space as much as possible. Further, the inverter is compact in structure, low in cost, high in power density, and simple and reliable in cooling design.

The invention relates to a starting method for a current transformer, and is applied to the current transformer of which a main circuit is formed by sequentially connecting a direct current (DC)/DC conversion circuit and a DC/alternating current (AC) conversion circuit. A DC bus capacitor is arranged between the output end of the DC/DC conversion circuit and the input end of the DC/AC conversion circuit. The method comprises the following steps of: connecting an AC power grid with the DC end of the main circuit by a current limiting resistor, charging the DC bus capacitor by utilizing the AC power grid, regulating the main circuit to make the amplitude and phase of the output voltage of the main circuit are the same as those of the voltage of the AC power grid to meet grid connection requirements, and connecting the AC end of the main circuit to the AC power grid. By the starting method for the current transformer, not only relatively lower starting current is ensured to make radiation designing easier to realize, but also synchronous grid connection is realized to make grid connection impact current relatively lower; and the method is particularly applied to the starting of a DC double-channel or multi-channel current transformer.

A method and apparatus for converting three phase AC voltages on first, second and third input lines to DC voltage across positive and negative DC buses, the apparatus comprising a rectifier including first, second and third rectifier legs, each leg including a switch and a diode wherein the switch is linked between the positive DC bus and an cathode of the diode, an anode of the diode is linked to the negative DC rail and the first, second and third diode cathodes are linked to the first, second and third input lines, respectively, a DC bus voltage sensor linked to the positive DC bus and measuring the DC bus voltage to generate a measured DC bus voltage and a rectifier controller that receives the measured DC bus voltage, a reference voltage value and the three phase AC voltages wherein, when the measured DC bus voltage is at least equal to the reference voltage value, the controller turns on the switches in the first, second and third rectifier legs when the voltages on the first, second and third input lines are positive, respectively.

The invention discloses an internal potential response-based inertia control method and device for a full-power wind generator. When a full-power wind power generator system suddenly increases or reduces a load, a phase-locked loop cannot accurately lock the phase and the frequency of a power grid immediately by reducing the bandwidth of the phase-locked loop and changing the damping ratio of the phase-locked loop, so that a DC bus capacitor voltage correspondingly changes due to a sudden change of the power grid; a DC bus voltage is not adjusted to a reference value too fast by reducing the bandwidth of a DC bus voltage control loop and adjusting the damping ratio of a DC bus voltage loop; the inertia is shown for the power grid by a fast response of the DC bus voltage; difference operation is carried out on a DC bus measurement value and a DC bus voltage instruction value; the difference value is multiplied by a proportion coefficient to obtain an additional instruction; the additional instruction is added to a rotating speed loop to utilize rotation energy of a full-power wind generator set, so that the full-power wind generator set can provide an inertia support to the system. According to the internal potential response-based inertia control method and device for the full-power wind generator, a fast frequency and an acute change caused by a low rotational inertia of the system are avoided.

The invention proposes a DC-bus-capacitor discharge device of a motor controller used for an electric vehicle. The DC-bus-capacitor discharge device includes a discharge module; a first controllable switch which is serially connected with the discharge module and connected in parallel with a DC bus capacitor after being serially connected with the discharge module; and a second switch connected in parallel with the first controllable switch. The motor controller of the electric vehicle controls the first controllable switch to switch on after receiving a switch-off signal of the electric vehicle so that the DC bus capacitor is discharged for a first time through the discharge module, and the DC bus capacitor is discharged for a second time through the discharge module after the second switch is switched on. The discharge device is capable of discharging the residual high voltage of the bus capacitor for twice after the electric vehicle is shut down so that the discharge device has a dual discharge function and high-voltage operation and maintenance security of maintenance personnel is ensured in a substantial degree. The invention also proposes the electric vehicle.

The invention provides a voltage discharge method for a motor controller, a system and a vehicle. The method comprises steps: a discharge command is received; a motor winding discharge circuit is controlled to be conducted to discharge the motor controller; after first predetermined time, whether the voltage of a bus drops to safety voltage is judged; if not, an active discharge circuit is controlled to discharge the motor controller intermittently until the active discharge circuit continuously discharges the motor controller when the voltage drop of the bus voltage is larger than predetermined voltage drop; and after second predetermined time,, if the bus voltage does not drop to the safety voltage, discharge is stopped, discharge timeout signals are reported, or otherwise, discharge onthe motor controller is completed. The method can quickly discharge the voltage of a DC bus capacitor in the motor controller after normal high voltage switching off of the whole vehicle, and high voltage power consumption safety is further improved.

A power supply unit is provided which comprises an AC/DC conversion unit with an input to which an input voltage is coupled and an output to which a DC bus voltage is coupled. The power supply unit furthermore comprises a DC bus capacitor which is coupled to the output of the AC/DC conversion unit. The power supply unit furthermore comprises at least one sub-power supply unit receiving the DC bus voltage as input for providing at least one power supply. The power supply of the at least one sub-power supply unit or part of the load is at least reduced or switched off if the input voltage falls below a predetermined threshold value.

The invention discloses a wind power generation control device and a wind power generation system. The wind power generation control device is coupled between a fan and a power grid, and comprises a converter unit and a switching unit, wherein the converter unit comprises a machine side converter, a DC bus capacitor and a grid side converter; an AC side of the machine side converter is coupled to a rotor side of the fan; a DC side of the machine side converter is coupled to the DC bus capacitor; the DC side of the grid side converter is coupled to the DC bus capacitor; the AC side of the grid side converter is coupled to the power grid; the wind power generation control device is switched between a doubly-fed generation operation mode and a full-power operation mode when the wind speed meets the switching conditions.