838 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 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.

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.

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 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 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 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 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 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.