1402 results about "Three phase inverter" patented technology

An integral method for realizing parallel generation and network reactive power compensation at the same time is based on the transient reactive power theory applying park transfer to transform a three phase inverter output current to a rotation dq coordinate to realize separation of active current and reactive current to convert the DC current of the photovoltaic to AC current by controlling the currents and directions carry out reactive power compensation to the local network. When a photovoltaic battery has enough energy to output, it realizes parallel generation and reactive compensation at the same time, when it stops the output, the inverter compensates the network independently.

The invention relates to a series resonance DC/DC converter of a photovoltaic system, which comprises a single-pole converter (40), a series resonance circuit (50), a high-frequency isolation transformer (16) and a rapid uncontrollable rectifier (20), wherein the single-pole converter (40) is used for converting a direct voltage (26) of a photovoltaic array (10) into a single-pole pulse voltage; the series resonance circuit (50) is used for converting the single-pole pulse voltage into a sine voltage with a fixed frequency; the high-frequency isolation transformer (16) is used for boosting and isolating as well as protecting; and the rapid uncontrollable rectifier (20) is used for rectifying the high-frequency sine voltage into a stable direct current voltage (28). The converter (100) is only provided with two switching elements, has the advantages of simple control mode and no switching loss, and can be used for boosting and stabilizing the larger photovoltaic array so as to be convenient for synchronizing through a three-phase converter or charging a storage battery.

The invention discloses an energy-saving type cascade multilevel photovoltaic grid-connected generating control system comprising an energy-saving cascade multilevel photovoltaic generating inverter, a controller and a power grid, wherein the multilevel inverter consists of 3n energy-saving type photovoltaic generating modules, wherein n modules are connected in series into one phase of a three-phase inverter; and the single-stage power of each module is converted to realize the buck-boost, the inverting and energy saving and adapt to the wide-range change of the battery voltage with high reliability. 3n photovoltaic cells and energy-saving cells are distributed on 3n modules; the generation of each module is independently controlled, thereby realizing the distributed maximum power track, collecting solar energy to the maximum extent, realizing high efficiency and avoiding the problems of power loss and hot spot caused by the local shade generated when the photovoltaic cells are connected in series; and the invention can flexibly control the stable power of a feeder grid of the multilevel inverter and achieve the functions of reactive power consumption, the power pitch peak control and the like, has the advantage of multilevel inversion and low output harmonic voltage and is suitable for high-voltage, high-power and transformer-free grid connection.

In a power drive unit having power modules (three-phase inverter circuits) connected to a control circuit board, bus bars extending from the power modules and a current sensor each installed near the bus bars and including a sensing element that detects currents outputted from the bus bars, there are provided a sensor board on which the sensing element is mounted, and lead pins each connecting the sensor board to the control circuit board and having a bowed shape whose one end is connected to the sensor board and other end once extends away from the circuit board and then turns back toward the circuit board. With this, the circuit board and current sensors can be connected through the lead pins without increasing the distance therebetween and stress produced in the lead pins can be alleviated, thereby enabling the unit to be minimized in size and utilized in a harsh service environment.

The present invention aims to provide a synchronous motor drive system that is capable of suppressing ripples in current while reducing switching loss. The system includes three-phase inverters 201-203, a control circuit 400 for controlling the operations of the three-phase inverters and a synchronous motor 300 including a plurality of three-phase coils. To control the operations of the three-phase inverters, the control circuit 400 causes the three-phase inverters 201 and 203 and the three-phase inverter 202 to use different carrier frequencies to generate three-phase AC power, and each of the three-phase inverters supplies a different one of the three-phase coils with three-phase AC power.

A method for measuring current in each phase of a three-phase inverter driven motor is based on the three-phase inverter being controlled in a PWM mode by three PWM signals including the use of a common DC-link current sensing resistor. The current on the sensing resistor is intermittently sampled. The method includes determining a modulation index for the voltage demand set by a motor controller. Based on specific mutual duty cycle conditions of the three PWM phase driving signals, sampling windows of sufficient duration are created for allowing distinct sampling of two of the phase currents.

A multiple DC-to-AC inverter system, which is suitable for an electric or hybrid vehicle application, includes a plurality of inverters controlled by a single controller. One example embodiment includes four three-phase inverters driving one six-phase motor, where the output of the first inverter is coupled to the output of the fourth inverter and the output of the second inverter is coupled to the output of the third inverter. In response to the failure of an inverter, the drive signals to the inverter that is coupled to the faulty inverter are updated such that the partner inverter can remain active without being driven into an over-current condition.

Disclosed is a dead-time compensation method of a 3-phase inverter using an SVPWM scheme. The dead-time compensation method includes generating a switching signal having dead-time with respect to the power semiconductor switches of the upper and lower arms in order to obtain a predetermined output through the SVPWM scheme, detecting medium phase current from each phase current output through the switching signal, determining polarity of the medium phase current, and generating a switching signal by calculating switching time in order to compensate for time to apply effective voltage according to the polarity of the medium phase current. Through the dead-time compensation method, the distortion of the output voltage and the reduction of voltage having a fundamental wave in the output voltage, which are caused by the dead-time, are minimized through the switching of compensating for the time to apply effective voltage based on the polarity of the load current.

The invention discloses a three-level inverter circuit, belonging to the field of electric power electronics. The three-level inverter circuit comprises a circuit with power supply and a single-phase or three-phase inverter circuit, two switching tubes on an inverter bridge of the single-phase or three-phase inverter circuit are respectively connected with a first capacitor and a second capacitor in parallel, and intermediate nodes of the two switching tubes connected in series are connected with a first inductor in series. By adding the first capacitor, the second capacitor and the first inductor in the three-level inverter circuit, zero-voltage or zero-current on and off are realized between each switch tube and each inverse-parallel diode thereof, accordingly effect of a 'soft-switch' is achieved, and then loss of switches and electromagnetic interference are eliminated or reduced. The three-level inverter circuit can be applied to improve three-level T-type inverter circuit topologies and three-level I-type inverter circuit topologies.

An IGBT (insulated-gate bipolar transistor) stuck-open fault diagnosis method for a three-phase inverter bridge of a frequency converter belongs to the technical field of IGBT fault diagnosis of three-phase inverter bridges and solves problem that misdiagnosis is caused in instant load or instant unload when stuck-open fault of IGBTs of an inverter bridge is determined through the Park vector method. The method comprises the following steps: firstly, three phase currents ia, ib and ic of a motor stator used for speed regulation and controlled by the frequency converter are collected; secondly, the three phase currents ia, ib and ic are transformed through discrete Fourier transform to obtain cosine component aj, k and sine component bj, k of direct current component amplitude and fundamental component amplitude of the three phase currents ia, ib and ic; thirdly, the direct current component amplitude is normalized through the fundamental component amplitude to obtain a direct current component normalization value hj; fourthly, a fault phrase of the three-phase inverter bridge is determined according to the direct current component normalization value hj; and then whether the faultphrase is in an upper transistor or a lower transistor is determined. The invention is suitable for fault diagnosis of three-phase inverter bridges.

The invention relates to a super capacitor energy-storage type elevator driver which mainly comprises a diode three-phase uncontrollable rectifier, a three-phase inverter, a three-phase alternating current variable-frequency motor, a voltage-stabilizing filter capacitor, a super capacitor group, a first current limiting circuit, a second current limiting circuit, a direct current side voltage detecting circuit, a super capacitor group end voltage detecting circuit, a super capacitor group current detecting circuit, a signal conditioning circuit and a set of driving and controlling circuits, wherein the diode three-phase uncontrollable rectifier is connected with a three-phase electric network, the three-phase inverter comprises IGBT (Insulated Gate Bipolar Transistor) antiparallel diode moulds, and DSP (Digital Signal Processing) is used as the control core of the set of driving and controlling circuits. The invention changes the energy-saving scheme of feeding braking energy back to the electric network, energy is stored in the super capacitor group, and on-the-spot utilization is realized, thereby not only more conveniently and efficiently realizing energy saving, but also lowering the cost of the elevator driver, improving the operating safety of an elevator, and achieving popularization and application values.

The embodiment of the invention discloses a total power aging test circuit for a current transformer or a frequency transformer. The total power aging test circuit comprises a filter reactor, a boosting transformer and a direct-current power supply, wherein the direct-current power supply is communicated with two ends of a bus capacitor; the input end of the boosting transformer is communicated with the output end of a three-phase inverter through the filter reactor, and the output end of the boosting transformer is communicated with the input end of the three-phase inverter. The total power aging test circuit also comprises an aging test module arranged in a controller and an aging test triggering unit arranged on human interface device. The aging test triggering unit is used for controlling the running state of the aging test module, and the aging test module is used for controlling the current transformer or the frequency transformer for an aging test. The total power aging test circuit can effectively reduce the energy consumption in the aging test process, simplifies the structure of a test system, and reduces the maintenance cost of the system.

The invention discloses an electric vehicle charging and discharging and motor driving integrated device. The device comprises a three-phase bridge type two-way DC/AC converter, an isolated three-portDC/DC converter, a main controller, an integrated device operating mode switching device, a single-phase alternating-current power source input interface device and a single-phase alternating-currentoutput interface. A three-phase inverter for driving a motor in an electric vehicle driving system is subjected to topological reconstruction to form a single-phase rectifier in charging or a single-phase inverter in outward power supplying, so that an integral hardware circuit structure is formed. The three-phase bridge type two-way DC/AC converter, the isolated three-port DC/DC converter, a relay switch and corresponding driving modules are subjected to control switching according to an integral control method in the main controller, so that seamless switching of charging-discharging and driving modes is realized, and braking energy recovery, V2V/V2L and vehicular low-voltage storage battery charging functions are realized. The integrated device has advantages of optimized size, weightreduction, cost saving and reliability improvement.

The invention discloses an output power-based diagnosis method for an open-circuit fault of an insulated gate bipolar transistor (IGBT) of a three-phase inverter. The method comprises the following steps of: A, respectively measuring three-phase voltages and three-phase currents by using a potential transformer (PT) and a current transformer (CT) installed on the output phase in the inverter, and respectively calculating the half-wave power corresponding to six half-wave currents of the three phases of the current period; and B, comparing the six half-wave power values with a set open-circuit fault power threshold value P0, if one or two half-wave power values are less than the set open-circuit fault power threshold value P0, judging that the corresponding IGBT causes an open-circuit fault; or if three half-wave power values are less than the set open-circuit fault power threshold value P0, judging that the IGBTs corresponding to the two half-wave power values on the same side cause the open-circuit fault. By the method, any one or two IGBTs which cause the open-circuit fault can be detected and positioned, so that a controller of the inverter can take a tolerance strategy and reduce waveform distortion conveniently; the inverter can be maintained in time; and the loss enlargement and accidents are avoided effectively.

An inverter controlling method is applied in a system comprising a single-phase rectification circuitry and three-phase inverter. The method determines a capacitance of a capacitor connected between output terminals of the single-phase rectification circuitry for allowing an output voltage of the single-phase rectification circuitry to pulsate at twice frequency with respect to a power frequency; controls the three-phase inverter for supplying output voltages or output currents from the three-phase inverter to a motor; and suppresses a current flowing into the capacitor from a power source via the single-phase rectification circuitry.

The invention discloses a single-stage boosting/reducing energy storage type photovoltaic grid-connected power generation control system, which comprises an energy storage type power conversion main circuit and a control system which are connected mutually. The energy storage type power conversion main circuit comprises a photovoltaic cell, an inductance and capacitance circuit network, an energystorage cell and a three-phase inverter which are connected mutually; and the control system is used for performing charging and discharging management on the energy storage cell, maximum power tracking and threshold control on the photovoltaic cell and closed-loop control on output active and reactive power of the three-phase inverter. The system finishes boosting/reducing, inversion and energy storage through single-stage power conversion, realizes the minimum inverter capacity with a simple structure, ensures the steady power of the power grid, can collect solar energy to the greatest degree, improves the power generation efficiency, realizes reactive compensation, electric peak regulation control and the like, and improves the quality of the power grid.

Methods and apparatus are provided for controlling a stand-alone four-leg three-phase inverter. The inverter three-phase output is converted from AC domain elements to corresponding DC domain elements. The DC domain elements are processed into combined regulating and imbalance compensating signals, including over-current limiting. The compensating signals are restored to corresponding AC domain signals, and are processed into control inputs for the inverter, in order to stabilize the inverter output when connected to an unbalanced load. The inverter controller can be implemented entirely in software as a control algorithm.

A motor driving circuit includes a three-phase inverter circuit 8, including three upper-arm switching elements 56a to 56c for driving upper arms of different phases of a three-phase motor 3, and three lower-arm switching elements 56d to 56f for driving lower arms of different phases. At least one of the upper-arm switching elements 56a to 56c and the lower-arm switching elements 56d to 56f is a semiconductor element that performs a diode operation. The diode operation is an operation in which a voltage less than or equal to a threshold voltage of a gate electrode G is applied to the gate electrode G with reference to a potential of a first ohmic electrode S, thereby conducting a current flow from the first ohmic electrode S to a second ohmic electrode D and blocking a current flow from the second ohmic electrode D to the first ohmic electrode S.

An apparatus and method for converting DC voltage across positive and negative DC buses to three phase AC voltages on first, second and third AC output lines, the method comprising the steps of providing first and second three phase inverters that include a first subset of inverter switches and a second subset of inverter switches, respectively, linking a first choke in series with the first three phase inverter between the positive and negative DC buses and the AC output lines, linking a second choke in series with the second three phase inverter between the positive and negative DC buses and the AC output lines and synchronously controlling the first and second inverter switch subsets so that switching of first and second inverter switch subsets is substantially synchronized among the three phases.

The invention discloses a microgrid control method having functions of voltage unbalance compensation and harmonic suppression. An integrated controller acquires a common bus voltage and calculates an unbalance factor vector, a characteristic order harmonic component positive-sequence compensation reference vector and a characteristic order harmonic component negative-sequence compensation reference vector of the common bus voltage, and transmits the vectors to a local controller of every parallel inverter through low-bandwidth communication. In the local controller, a characteristic order harmonic positive- and negative-sequence compensation voltage vector is calculated and is superposed with a reference voltage vector, a virtual impedance voltage vector and the common bus voltage unbalance factor vector to synthesize and correct a voltage regulating reference vector, and unbalance compensation and harmonic suppression of the common bus voltage is carried out through inverter voltage and current control. By applying the method provided by the invention to a multi-inverter parallel system in which a common bus is connected with a three-phase unbalanced load and a nonlinear load, three-phase voltage balance of the microgrid can be maintained, output voltage distortion of three-phase inverters can be reduced, and output power of the parallel inverters can be accurately allocated.

The invention relates to a novel topological structure voltage source type inverter and an adjusting method. The structure is a star-like topological structure and is formed by connecting a three-phase bridge type inverter in series at a neutral point of cascaded inverters connected in a star shape. Compared with the conventional cascaded inverters connected in the star shape, the novel topological structure theoretically has a function of completely compensating negative sequence current; and compared with the conventional three-phase bridge type inverter, the novel topological structure can realize extended application under high voltage level without using a device cascade or MMC (Multilevel Converter) structure. In the novel topological structure, a direct current side of the three-phase bridge type inverter can be connected with a direct current network, energy storage equipment or a power grid through a current transformer; the inverter can be widely applied to the fields of flexible direct current power transmission, new energy connection, high voltage frequency converter and the like; and the application prospect of the voltage source type inverter in the corresponding field is expanded. The novel topological structure has good generalization performance based on mature unit cascade and three-phase inverter structure and control technology.