839 results about "Three level inverter" patented technology

The present invention relates to a high efficiency three-level inverter apparatus containing both bipolar and field effect transistors. An embodiment of a modified control scheme is also presented whereby transistors are modulated differently for each quadrant of output voltage-current phase. This embodiment of a modified control scheme allows efficient switching of field effect transistors without additional freewheeling and series diodes.

A device for converting power from a floating source of DC power to a dual direct current (DC) output, the device includes: positive and negative input terminals connectible to the floating source of DC power; and positive and negative, and ground output terminals connectible to the dual DC output that may feed an inverter. The inverter may be either a two or three level inverter. A charge storage device may be connected in parallel to, and charged from, the positive and negative input terminals. A resonant circuit may be also connected between the charge storage device and the dual DC output. The resonant circuit may include an inductor connected in series with a capacitor. The charge storage device may discharge through the resonant circuit by switching through to either the negative output terminal or the positive output terminal.

Three-level inverter and rectifier power conversion systems and space vector modulation (SVM) controls having even-order harmonic elimination for neutral voltage balancing with a predefined vector switching sequences for half-wave symmetry in open loop system operation. The vector sequence listings for each SVM diagram segment includes switching state entries individually indicating one of three possible switching state levels positive (P), zero (0), or negative (N) for each of three or more switching groups of the power conversion system, with listings for each pair of first and second diametrically opposite diagram segments include symmetrically opposite switching states, with positive levels in the entries of the listing for the first segment corresponding to negative levels in the entries of the listing for the second segment and vice versa.

A tri-level inverter power module has an architecture employing a high degree of modularity that allows a base power module to be quickly, easily, and cost effectively configured to address a large variety of applications.

Three-level inverter and rectifier power conversion systems and space vector modulation (SVM) controls having even-order harmonic elimination for neutral voltage balancing with a predefined vector switching sequences for half-wave symmetry in open loop system operation. The vector sequence listings for each SVM diagram segment includes switching state entries individually indicating one of three possible switching state levels positive (P), zero (0), or negative (N) for each of three or more switching groups of the power conversion system, with listings for each pair of first and second diametrically opposite diagram segments include symmetrically opposite switching states, with positive levels in the entries of the listing for the first segment corresponding to negative levels in the entries of the listing for the second segment and vice versa.

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.

A tri-level inverter power module has an architecture employing a high degree of modularity that allows a base power module to be quickly, easily, and cost effectively configured to address a large variety of applications.

The invention discloses a device open-circuit fault diagnosis circuit for a diode NPC three-level inverter. The circuit comprises three open-circuit fault diagnosis unit circuits with same structures. The open-circuit fault diagnosis unit circuits are composed of signal sampling units, signal adjusting units, narrow pulse filtering units, first and second pulse missing detection units and upper and lower bridge arm circuit determining units. The signal sampling units isolate and sample bridge arm voltages, the signal adjusting units perform rectification, voltage separation and filtering on voltage signals after isolation and sampling, the narrow pulse filtering units and the first and second pulse missing detection units determine whether open-circuit faults occur to devices in bridge arm circuits, and the upper and lower bridge arm circuit determining units distinguish that fault devices are devices in an upper bridge arm circuit or a lower bridge arm circuit. By means of the device open-circuit fault diagnosis circuit for the diode NPC three-level inverter, which device in the three-level inverter is subjected to open-circuit fault can be detected accurately, the diagnosis speed is fast, and the diagnosis accuracy is high.

The present invention discloses a three electric level inverter control system. It contains three electric level voltage source inverter (NPC), field programmable gate array (FPGA), digital signal processor (DSP), wherein FPGA field programmable gate array (FPGA) receiving digital signal processor (DSP) sent control voltage instruction generating three electric level voltage source inverter (NPC) control signal. The present invention also discloses three level inverter control method, featuring 1, digital signal processor (DSP) transmitting space voltage vector amplitude value m and argument for controlling three level inverter triphase reference voltage, 2, field programmable gate array (FPGA) receiving DSP sent space voltage vector amplitude value m and argument, generating signal Vca, Vcb, Vcc, through direct current biasing and dead zone compensation techniques processing to generate three-phase voltage modulation signal Vca **, Vcb **, Vcc **, 3, finally respectively comparing with positive triangular wave, negative triangular wave to generate control pulse. The present invention overcomes the insufficiency of current pulse width modulation method (SVPWM) and special harmonic cancellation method (SHE-PWM), provides a fine rapidity, simple controlling, and practical three level inverter control system and method.

A power supply system that supplies high-voltage power to a vehicle drive motor is provided to achieve reduction in size, weight and cost of power supply. The power supply system includes a plurality of battery modules connected in series. With the intermediate connection point of the battery modules as an electrical neutral point, power is supplied to a three-level inverter via a three-level-potential high-voltage power supply line having potentials of +150V and −150V relative to this neutral point. In the three-level inverter, direct-current electric power is converted into three-phase alternating-current electric power to drive an electric motor. Accordingly, the withstand-voltage performance required of control units or control elements connected to the high-voltage power supply line can be halved as compared with the related art, thereby allowing a reduction in the size, weight, and cost of the power supply system. Further, the electric power generated by a generator is converted into direct-current electric power by a three-level converter and supplied to the high-voltage power supply line to charge the battery modules.

The invention relates to a single-supply open-coil winding permanent magnet synchronous motor driving system for electric vehicles. Six end leads of a stator winding of a three-phase permanent magnet synchronous motor are respectively connected to two standard two-level inverters. The driving system is supplied power by a direct-current power supply, and generates a rotary circular magnetic field by voltage space vector generated after space vector pulse width modulation. The driving system comprises a direct-current voltage source (1), a first inverter (2), a second inverter (3), a capacitor (4), an open-coil winding permanent magnet synchronous motor (5) and a common-mode voltage suppression vector (6). The first inverter is connected to one end of the winding of the permanent magnet synchronous motor, and the second inverter is connected to the other end of the winding. The drying system has advantages of a three-level inverter and can be applied to the field of driving of high-voltage high-power motors; while quantity of power devices is reduced. Owning to the compact design of the single supply, reliability of the driving system is improved. In addition, the effect of suppressing common-mode voltage can be achieved by effectively selecting the voltage space vectors on the basis of not increasing redundant switch devices.

The invention discloses a tri-sync inverter neutral-point potential balance control system and a control method, and belongs to the technical field of power electronic multi-level convertors. The system comprises a direct tri-sync power inverter unit, a voltage space vector modulation unit, a positive / negative small vector selection unit, a neutral-point potential deviation quantification factor calibration unit, a positive / negative small vector action time redistribution unit and a fuzzy-integral mixed controller. The neutral-point balance control method corrects the quantification factor ofthe calibration unit in real time according to the unbalance of the neutral-point potential, simultaneously detects the direction of the load current, judges whether the current small vector is positive or negative, and adjusts the action time of the positive / negative small vector in real time according to the designed fuzzy rules, thereby finally realizing dynamic balance of the neutral-point potential. The invention can control both static errors and dynamic errors within a small range, thereby achieving the effect of accurate balance of the neutral-point potential and enhancing the reliability of the multi-level power inverter system.

The present invention provides a medium voltage variable frequency driving system, including a three-phase switch-mode rectification module, a multilevel inverter and a high-capacity capacitor module. The three-phase switch-mode rectification module is coupled with a three-phase electrical grid, for converting an AC voltage input with a fixed operating frequency on the three-phase electrical grid into a DC voltage. The multilevel inverter is used for converting the DC voltage into an AC voltage with a required variable frequency, so as to drive an induction motor. The high-capacity capacitor module is coupled between the three-phase switch-mode rectification module and the multilevel inverter, for temporarily storing the DC voltage. In the present invention, a three-phase switch-mode rectification technology is used at the front-end rectifier, and a diode-clamped three-level inverter is adapted correspondingly at the rear-end inverter.

The invention relates to a three-level inverter multi-mode fault diagnosis circuit and a diagnosis method thereof. Voltage signals of an upper bridge arm, a middle bridge arm and a lower bridge arm of each phase of bridge arms of an NPC three-level inverter are collected. A bridge arm voltage fault feature extraction module extracts fault features of the voltage signals and then sends the fault features to a neural network module to be analyzed. Voltage of each middle bridge arm is measured through a main neural network module so that eleven fault modes, including a fault-free mode, of an open circuit of a single-bridge-arm component of the three-level inverter can be diagnosed. Voltage of each upper bridge arm and voltage of each lower bridge arm are measured through two auxiliary neural network modules so that the other four fault modes of the open circuit of the single-bridge-arm component of the three-level inverter can be diagnosed, and by combination of the three neural network modules, thirteen multi-fault modes of the open circuit of each single-bridge-arm component of each phase of the bridge arms of the three-level inverter and simultaneous open circuits of multiple components of each phase of the bridge arms of the three-level inverter are diagnosed together. According to the three-level inverter multi-mode fault diagnosis circuit and the diagnosis method thereof, fault components can be exactly positioned, the algorithm structure is simplified, calculation of a Hessian matrix can be avoided, and accordingly the calculation amount and internal storage demands in a training are reduced, the operation speed is high, the diagnosis accuracy is high and the anti-interference capacity is high.

A power supply system that supplies high-voltage power to a vehicle drive motor is provided to achieve reduction in size, weight and cost of power supply. The power supply system includes a plurality of battery modules connected in series. With the intermediate connection point of the battery modules as an electrical neutral point, power is supplied to a three-level inverter via a three-level-potential high-voltage power supply line having potentials of +150V and −150V relative to this neutral point. In the three-level inverter, direct-current electric power is converted into three-phase alternating-current electric power to drive an electric motor. Accordingly, the withstand-voltage performance required of control units or control elements connected to the high-voltage power supply line can be halved as compared with the related art, thereby allowing a reduction in the size, weight, and cost of the power supply system. Further, the electric power generated by a generator is converted into direct-current electric power by a three-level converter and supplied to the high-voltage power supply line to charge the battery modules.

A three level inverter apparatus for suppressing a resonance current flowing therethrough, to thus improve its conversion efficiency and operational stability. This inverter apparatus includes a converter 1 for converting AC power source power to DC power, an inverter for converting thus converted DC power to AC power, and a DC link for interconnecting these converter and inverter. This DC link has two first smoothing capacitors connected in series between a positive-polarity potential bus P and a negative-polarity potential bus N for storing DC power obtained by the converter 1 and two second smoothing capacitors connected in series between the positive-polarity potential bus P and the negative-polarity potential bus N for storing DC power to be supplied to the inverter. The positive-polarity and negative-polarity potential buses each have a resonance-suppressing reactor inserted therein and the intermediate-potential bus, a resonance-suppressing resistor inserted therein.

The invention, which belongs to the power converter control field of the driving motor, relates to a method for controlling neutral point voltage balance of a three level converter, wherein the method is based on a voltage space vector pulse width modulation technology and is used for controlling a neutral point clamped three level inverter. The method comprises the following steps that: step one, an action time distribution factor of a redundant small vector is obtained; step two, an area where control on a neutral point potential balance can be realized by a nearest three vector (NTV) method is obtained; step three, an NTV action area in a mixed voltage space vector pulse width modulation method is obtained; step four, a switching condition of the mixed voltage space vector pulse width modulation method is designed; and step five, the mixed voltage space vector pulse width modulation method with a proportion of pm is realized. According to the invention, a redundant small vector distribution factor is employed to design a switching condition of a mixed voltage space vector pulse width modulation strategy; therefore, an essence of a space vector modulation method is embodied; themethod can be used flexibly and used variables are less, so that it is beneficial for analysis and development application.

A three-level inverter dead time compensation control method is used for compensating the decrease of system performance caused by dead time. According to the topological structure of a three-phase three-level PWM (pulse width modulation) inverter, the method first sets corresponding dead time and determines the on-off delays of power elements in the inverter; the method then considers the tube voltage drops of the power transistors of the inverter and the tube voltage drops of clamping diodes of the inverter and calculates the common voltage expression of the output neutral point of the inverter; afterwards, according to the sector with three-phase current value and a reference voltage vector, the method determines the relational coefficient between voltage error caused by the tube voltage drops of the power transistors, the tube voltage drops of the clamping diodes and the on-off delays of the power transistors and current, and thereby the total dead time compensation time of each phase of the three-level PWM inverter is worked out. The method takes the dead time, the on-off delays of the power elements and the tube voltage drops into full consideration, solves the problem of voltage and current distortion caused by the dead time effect in the three-level inverter, and enhances system performance.

The invention discloses a three-level three-phase four-wire active power filter and a control method thereof. The filter comprises two capacitors, a three-level inverter bridge, a previous LC (inductance and capacitance) output filter, a posterior LC output filter and a grid-connected switch, middle points of the two capacitors are directly connected with a neutral wire of a power grid, the two capacitors are connected with three bridge arms of the three-level inverter bridge in parallel after being serially connected with each other, the three-level inverter bridge is a three-level diode-clamped type three-level inverter bridge, and an output end of the three-level inverter bridge is connected into a three-phase power source in a three-phase four-wire power source by the previous LC output filter, the posterior LC output filter and the grid-connected switch sequentially. The control method includes controlling the three-level three-phase four-wire active power filter by the aid of control of three control loops and a hysteresis comparator.

The invention relates to a 60degree coordinate system based virtual vector modulation algorithm of a tri-level inverter, belonging to the field of power and electronic application. According to the algorithm, virtual space vectors (VSVPWM) are mapped into a 60degree coordinate system via Clark / Park coordinate transformation so that basic vector coordinates are changed into simple algebraic coordinates, large and small sectors are discriminated according to logic judgment of linear coordinate equations, action time of three latest basic vectors are calculated via the algebraic coordinates in a volt-second balance principle, PWM signals are output in a nine-segment switching time sequence with a positive small vector at first, and action time of redundant small vectors is adjusted via closed-loop PI regulation according to two capacitance difference values. A lot of trigonometric function and irrational number operation in a traditional VSVPWM algorithm can be omitted, and the 60degree coordinate system based virtual vector modulation algorithm is characterized by being simple in calculation, high in instantaneity and easy to realize.

The invention discloses a diode neutral point clamped three-level inverter current limiting control method and a related circuit thereof. The diode neutral point clamped three-level inverter current limiting control method comprises specific steps as follows: when the current in switching tubes is lowered to be not bigger than a first current preset value, the related circuit drives one of the switching tubes at the inner side of a bridge arm to be switched on; after a first delay time, another one of the switching tubes at the inner side is driven to be switched on; after a second delay time, one of the switching tubes at the inner side is controlled to be switched off, and another one of the switching tubes is controlled to be normally switched on; and all the switching tubes are controlled to be switched on or switched off according to the control time sequence of the diode neutral point clamped three-level inversion circuit. In such control mode, the switching sequence of the switching tubes in the diode neutral point clamped three-level inversion circuit can be controlled, thereby reducing the voltage stress of the switching tubes and ensuring that the voltage stress of the switching tubes can not exceed the standard even if the limited current is exceeded.

The invention discloses a VSVPWM (Virtual Space Vector Pulse Width Modulation)-based three-level inverter neutral point potential compensation balance control strategy. A virtual median vector is introduced on the basis of the conventional SVPWM, the current which flows by a neutral point in each sampling period can be zero through recombination of a small vector and the median vector. The invention provides the VSVPWM-based neutral point potential accurate compensation control strategy. According to the method, a voltage adjustment coefficient is introduced according to detected neutral point potential deviation, three-phase output current and direct current side neutral point current direction to set different adjustment coefficients for different small vectors so as to increase the control capacity of corresponding positive or negative small vector to the neutral point current and reduce the fluctuation of the neutral point potential.

A method for driving a neutral point clamped three-level inverter is provided. In one exemplary embodiment, DC current is received at a neutral point-clamped three-level inverter. The inverter has a plurality of nodes including first, second and third output nodes. The inverter also has a plurality of switches. Faults are checked for in the inverter and predetermined switches are automatically activated responsive to a detected fault such that three-phase electrical power is provided at the output nodes.

The invention discloses a three-level inverter of a single-phase mixed bridge, comprising six switching tubes T1 to T6, four diodes D1 to D4, two electrolytic capacitors C1 to C2 and one output filter; wherein the four switching tubes T1 to T4, the two electrolytic capacitors C1 to C2 and the diodes D1 and D2 form a three-level single-phase converter unit of a diode middle point clamping position, the switching tubes T5 and T6, and the two electrolytic capacitors C1 to C2 form a single-phase half-bridge converter unit, a serial-connection branch circuit of D3 and D4 is connected with a serial-connection branch circuit of D1 and D2 in parallel, and the middle point of the D3 and D4 is connected with the middle point of the bridge arm of T5 and T6. The three-level inverter can effectively inhibit ground leakage current of the inverter, and has the advantages of high efficiency and simple modulating method, and the three-level inverter is suitable for a power supply inverter system which has strict ground leakage current, such as no-transformer type photovoltaic grid-connection inverter and the like.

The invention relates to a modulation method for an active neutral-point clamp type tri-level inverter. Based on a tri-level sine pulse-width modulation method, the modulation method of the invention obtains required pulse-width modulation signals by defining level switching manners of the active neutral-point clamp type tri-level voltage-source inverter, and designing conduction sequence of different switching elements according to different influences of the two switching manners on power consumption of the switching elements. The pulse-width modulation signals are used to control switching on / off of each switching element of the active neutral-point clamp type tri-level inverter, so that dc is converted into ac, and ac is provided for a load. The modulation method is suitable for large-power tri-level voltage-source inverters.

The invention discloses a three-level three-phase four-bridge arm converter which comprises a direct-current part, a converting part, a converting part controller, a fourth bridge arm and a fourth bridge arm controller, wherein the converting part is a diode clamp type three-level inverter, the fourth bridge arm is a T-type three-level structure, the exchange of energy at a direct-current side and an alternating-current side is realized by controlling the states of first three bridge arm power switching tubes of the converting part, and a neutral point voltage at the direct-current side is changed by controlling the state of a power switching tube of the fourth bridge arm to realize the balance of neutral point potential. The fourth bridge arm of the three-level three-phase four-bridge arm converter adopts a T-type three-level topology and omits 2 clamp diodes compared with the diode clamp-type three-level inverter, thus saving the cost, and being more balanced in power loss and higher in efficiency; the control of neutral point balance is not affected by a power factor, the modulation degree and a modulation strategy; and as the deviation permission range of the neutral point voltage at the direct-current side is controllable, the permission range can be adjusted according to actual working conditions to improve the efficiency of a system.

The invention discloses an ANPC type three-level inverter, a modulation method and electrical equipment. The modulation method comprises steps that, a leg voltage instruction stands t1, t2 and t3 switch state change moments during transition from a positive half cycle to a negative half cycle, from the t1 moment, a T3 and a T6 are turned on, and a T2 and a T5 are maintained to turn on; from the t2 moment, the T2 and the T5 are turned off; from the t3 moment, the T3 is turned off, and the T4 is turned on; the Vo sequentially stands t11, t12 and t13 moments during transition from a negative half cycle to a positive half cycle, from the t11 moment, the T2 and the T5 are turned on, the T3 and the T6 are maintained to turn on; from the t12 moment, the T3 and the T6 are turned off; from t13 moment, the T2 is turned off, and the T1 is turned on; except two time segments of t1-t3 and t11-t13, a traditional ANPC type three-level inverter modulation method is followed in other time, so generation of a relatively long commutation loop during turning off a switch tube near a zero crossing point of the leg voltage instruction can be avoided.

The invention is suitable for the field of power electronics, and relates to a neutral-point potential balance control device and method for a three-level inverter. The device comprises a voltage acquisition unit, a proportional-integral control unit, a pulse width control unit and a voltage regulating unit. According to the neutral-point potential balance control device provided by the invention, a control quantity is generated by detecting capacitor voltages above and below a bus in real time and performing proportional-integral control processing, and the pulse width modulation duty ratio of a voltage regulating unit power tube is regulated according to the control quantity. The neutral-point potential balance control device is simple in structure, and is easy and convenient for control realization; and a control effect is irrelevant to the modulation ratio and power factor of an inversion system, and neutral-point potential can be controlled in a relatively small range.

The invention provides a model prediction three-level direct torque control method based on state trajectory extrapolation. According to the method, a traditional hysteresis controller with direct torque control is replaced by a model prediction controller. The method includes the following steps: aiming at allowable switching vectors, determining a step-length prediction range for output trajectory extrapolation by using an internal state prediction model, and with average switching frequency of an inverter as a value function, solving an optimal switching vector in real time to act on the inverter directly according to limited time zone rolling optimization strategies of model prediction control. According to the model prediction three-level direct torque control method based on the state trajectory extrapolation, the switching frequency of an NPC three-level inverter can be reduced to about 300Hz, quick dynamic response capability and ideal current harmonic distortion characteristics can be obtained, and the method has broad application prospects in middle-high voltage and high power fields.