68 results about "Three phase pwm rectifier" patented technology

The invention relates to a control method of three-phase voltage type PWM rectifier under unbalance voltage of a power grid, relates to the technical field of power electrons. The method comprises the following steps: detecting three-phase power grid voltage value, and transforming to be under a two-phase static coordinate system; carrying out digital filtering on an Alpha-axis voltage component and a Beta-axis voltage component under the two-phase static coordinate system by a positive-negative sequence filter, and obtaining the Alpha-axis positive-negative sequence component and Beta-axis positive-negative sequence component; calculating and obtaining the Alpha-axis and Beta-axis current instruction according to the Alpha-axis and Beta-axis positive-negative sequence voltage component under the given active and reactive power and two-phase static coordinate system; detecting three-phase alternating current, transforming to be under the two-phase static coordinate system, adopting a predicting current control method, calculating and obtaining Alpha-axis input voltage instruction and Beta-axis input voltage instruction of the alternating side under the two-phase static coordinate system. SVPWM modulation is adopted to obtain driving pulse. The control method eliminates direct current voltage harmonic component of three-phase PWM rectifier under the unbalance voltage of the power grid and realizes the operation of controlled power coefficient.

The invention discloses a multifunctional power grid simulator and a control method thereof. The main circuit of the simulator is characterized in that three mutually independent back-to-back systems are provided; the mutually independent back-to-back systems have a structure form that the input sides are three-phase PWM (Pulse-Width Modulation) rectifier, and the output sides are controllable single-phase PWM inverters for outputting voltage; mains supply is connected to the three-phase PWM inverters after the isolation of a three-phase transformer; and the single-phase PWM inverters are outputted by an LC (Inductor-Capacitor) filter. The invention as a power grid voltage generating device in a distributed power generating synchronization research can be used for simulating to output standard grid voltage and the like, and provides a grid environment as real as possible for a distributed power generating system synchronization research so as to satisfy the requirements for distributed powder generating researches.

The invention relates to a three phase PMW rectifier control technology under unbalanced power grid voltage and belongs to the power electronic technology field. Active power and reactive power given compensation values are obtained under a static coordinate through rectifier direct current side voltage, power grid voltage and power grid current, and using rectifier alternating current side voltage and power grid voltage, and delayed signals of the rectifier alternating current side voltage and power grid voltage. The compensation values plus original power given values on the basis of balanced power grid voltage serve as final power given values, then instruction values of the rectifier alternating current side voltage are obtained by using predicting direct power control method, and driving signals controlled by six switches are obtained through the decomposition of a space vector pulse width modulation (SVPMW). The method does not need the change of coordinate rotation, and is easy to be integrated into the existing control method under balanced power grid voltage. The method has the advantages of being small in computation, easy to achieve, good in robustness and the like, and can reduce the harmonic distortion of grid side currents while eliminating direct current voltage ripples.

The invention discloses a single-current feedback control method of a three-phase LCL filtering type PWM rectifier. Aiming at a conventional double-current feedback control active damping method, all that is required is to detect a current value on one side of a PWM rectification net, and a capacitance current is not required to be sampled, so that additional sensors are reduced, the reliability of a system is improved, and the hardware cost is reduced; a feedback coefficient of the current on one side of the net is adjusted in real time, so that the system damping is increased, and a resonance peak of an LCL filter is restrained; and a feedforward network voltage is introduced, and an input current on one side of the net is subjected to power decoupling control, so that the dynamic property of the system is further improved. The three-phase PWM rectifier has the advantages of high power factor, high response speed, high reliability, relatively simple design and the like.

The invention discloses an arc suppression coil device and method for compensating for an active component in single-phase grounding fault current. The device comprises a Z-type grounding transformer module with a secondary winding, a single-phase arc suppression coil module, a low-voltage reactor module controlled by a thyristor, a single-phase full-bridge inverter module, a three-phase PWM rectifier module and a controller module. The method includes the steps that the active component in the grounding current is compensated for by the arc suppression coil in the mode that a three-phase PWM rectifier is combined with a single-phase full-bridge inverter, when a single-phase grounding fault happens in a power distribution network, the single-phase full-bridge inverter module is controlled to compensate for the active component in the grounding current with the formula (please see the formula in the specification) as instruction current, an appropriate PWM control strategy is adopted for generating driving signals to adjust and control corresponding electric and electronic devices so that the electric and electronic devices can be controlled to output compensation current same to the active component current in magnitude and opposite to the active component current in phase, the active component in the grounding current is optimally compensated for, reliable and stable operation of the arc suppression coil is guaranteed, and the operation safety of the power distribution network is improved.

The invention discloses a two-phase inverted power system and a control method. DC side voltage is obtained by adopting a three-phase power width modulation (PWM) rectifier to realize a high voltage factor of a power grid side and reduce energy loss. Simultaneously, a two-phase inverter only comprises four power switching tubes, and compared with a conventional two-phase inverted power supply, the two-phase inverted power system cancels a switch arm to make the structure of the two-phase power supply simpler, greatly reduce cost and improve system reliability. The three-phase PWM rectifier adopts a double-closed loop control strategy consisting of a voltage outer loop and a current inner loop to realize high-precision control over the voltage of a DC side and the high-power factor control over the current of the power grid side. The double-closed loop control strategy consisting of voltage sharing outer loop control and output current inner loop control over two series-wound capacitors on the DC side realizes the rapid tracking of output current and the voltage sharing of the two capacitors on the DC side.

The invention relates to a three-ring control method of a three-phase PWM (Pulse-Width Modulation) rectifier for LCL (Lower Control Limit) filtering and belongs to the field of rectifier control. The three-ring control method is characterized in that an output voltage of a rectifier, a grid-side inductive current, an inductive current at the side of a rectifier bridge are respectively sampled by using a group of voltage detection transmitters and two groups of current detection transmitters so as to control an output direct-current voltage and a grid-side power factor of the three-phase PWM rectifier. The control method provided by the invention has the outstanding advantages that the output direct-current voltage of the three-phase PWM rectifier is controlled with high precision and good stability; the grid-side power factor is high; the capability of resisting voltage distortion interference of a power grid is strong; and a bridge arm switching tube is convenient to protect, the control method has high reliability and the like. Therefore, the control method provided by the invention is very suitable for controlling the three-phase PWM rectifier for the LCL filtering.

The invention discloses a control method for a three-phase PWM rectifier suitable for power grid waveform distortion. The control method for the three-phase PWM rectifier suitable for the power grid waveform distortion mainly includes that extracting a current reference signal under input voltage distortion and unbalanced disturbance, and actively injecting negative-sequence current, improved dead-beat inner current loop which is forecast through combining with linear extrapolation, and outer direct voltage loop performed with active disturbance rejection control. The control method for the three-phase PWM rectifier suitable for the power grid waveform distortion plays roles of inhibiting the harmonic wave of the input current of the PWM rectifier, injecting proper negative-sequence current to eliminate the secondary power pulse of the output direct current voltage of the PWM rectifier, improving the transient response of the output direct current voltage, and compensating the influences of all kinds of delay on the dead-beat control. The control method for the three-phase PWM rectifier suitable for the power grid waveform distortion is capable of obviously reducing the secondary wave of the output direct current voltage under the disturbance of the input harmonic wave and unbalanced voltage, improving the transient response speed of the PWM rectifier, reducing the transient offset of the direct current voltage, and improving the system control precision.

The invention discloses a three-phase power grid disturbance generating device and a control method thereof. The device comprises a three-phase multi-winding transformer, a power module array and an output filter which are connected sequentially, wherein the power module array comprises three groups of power modules corresponding to three-phase output; each power module comprises a three-phase PWM (pulse-width modulation) rectifier, a DC (direct-current) bus link and a single-phase H-bridge inverter which are connected sequentially; input of the three-phase PWM rectifiers is connected with secondary-side three-phase windings corresponding to the three-phase multi-winding transformer; each DC bus link comprises a DC capacitor group; output ends of the single-phase H-bridge inverters are cascaded to form device basic output; each group of power modules comprise at least one low-frequency disturbance generating power module for outputting fundamental waves or outputting the fundamental waves and harmonic waves as well as at least one high-frequency disturbance generating power module for outputting the harmonic waves. The device is controlled with the method. According to the method, the switching frequency of the at least one high-frequency disturbance generating power module is controlled to be not smaller than that of the at least one low-frequency disturbance generating power module. The device is small in size, low in cost and capable of meeting mobile, vehicle-mounted and on-site detection requirements.

The invention discloses a concatenated multilevel inverter circuit capable of realizing energy feedback and a control method. The circuit is formed by concatenating power units based on a three-phase uncontrolled rectifier circuit and power units based on a three-phase pulse width modulation (PWM) rectifier circuit. The control method provided by the invention comprises the following steps of: controlling the switching-on of insulated gate bipolar transistors of inverter circuits in the power units based on the three-phase uncontrolled rectifier circuit to make the feedback energy of a load not flow into intermediate direct current voltage circuits in the power units based on the three-phase uncontrolled rectifier circuit but directly flow into intermediate direct current voltage circuits in the power units based on the three-phase PWM rectifier circuit. The circuit provided by the invention can realize a load energy feedback power grid to achieve an energy saving effect, simultaneously simplifies the complexity of a topology structure of a power unit system and a control link to a certain extent and decreases the number of the insulated gate bipolar transistors, thereby decreasing the construction cost, and has high economic value.

The invention provides a light emitting diode (LED) centralized DC (direct-current) power supply system and operating methods thereof. The proposed DC power supply system comprises a three-phase AC (alternating-current) input interface, a DC power supply output interface, N+1 three-phase PWM (pulse width modulation) rectifier modules, LED cluster loads and a power supply management module. The proposed operating methods are described as following: the power supply management module adjusts the duty ratio of the three-phase PWM rectifier modules, based on the control signals formed by synthesizing the information about voltage and current of the positive and negative output buses, the three-phase AC input ends, control signals and output of the three-phase PWM rectifier modules, hence AC voltage of power grid can be directly converted into adjustable DC voltage by the PWM rectifier.

The invention discloses a multi-functional storage battery charging and discharging device and a control method thereof. The device adopts two-stage transformation. A front-stage unit adopts a three-phase PWM rectifier to obtain a DC-side voltage, the grid-side access current harmonics is reduced, the power factor is improved, and the energy loss is reduced; a rear-stage unit uses an interleaved parallel bidirectional half-bridge converter to greatly reduce the output filter inductance. The three-phase PWM rectifier adopts a double closed-loop control strategy of the voltage outer loop and thecurrent inner loop to realize high-precision control of the DC bus voltage and high-power factor control of the grid-side current; when the bidirectional half-bridge converter controls the output voltage, the double closed-loop control strategy of the voltage outer loop and the current inner loop is adopted to use the single loop control of the inner current loop during control of the output current; when a storage battery is charged, the control current is positive, and when the storage battery is discharged, the control current is negative; and when more power is required, the output ends of the two devices are switched to work in series or in parallel through a switch.

The invention discloses a three-phase pulse width modulation (PWM) rectifier soft starting system, which belongs to the technical fields of power electronics and current transformation. A two-way silicon controlled rectifier is connected between a three-phase power grid and a rectifier; at the moment of starting, a conduction angle of the two-way silicon controlled rectifier is gradually increased within a stipulated time until a full-conduction state is realized under the control of a controller; and in the process, an insulated gate bipolar transistor (IGBT) is in an off state, the rectifier is in a diode controlled rectification state due to the existence of fly-wheel diodes, the voltage of a DC bus is stably increased, PWM control is started after the voltage of the DC bus is stabilized, and the three-phase PWM rectifier may stably enter a normal working state. The system can start the rectifier on the basis of increasing the voltage of the bus to a certain value before the PWM rectifier works normally, and gently increase the voltage of the DC bus without relatively higher impact to effectively protect a power device.

The invention discloses a three-phase PWM rectifier control method based on deadbeat and triangular wave comparison, which belongs to the field of power electronic conversion technology and intelligent control. The control method of the invention mainly comprises steps of voltage outer loop, deadbeat control and triangular wave comparison control, wherein the voltage outer loop is a PI step; and the deadbeat control is current inner loop control. The control method is simple; and advantages of the triangular wave comparison control and the deadbeat control realize fixed frequency control with an input power factor 1, AC-side input current low harmonic and DC-side voltage stable tracking when switching frequency is low.

The invention provides an interleaved parallel high-frequency isolated three-phase PWM rectifier, comprising: an interleaved parallel three-phase PWM rectifier circuit; Three LLC resonant cavities, two ends of each resonant cavity are respectively connected to the midpoints of two bridge arms of each phase PWM rectifier circuit; Three high-frequency transformers, the primary side of each high-frequency transformer is connected with each LLC resonant cavity correspondingly; An output rectifier circuit is connected to the secondary side of the three high frequency transformers. The rectifier reduces the number of switching transistors, thereby improving the efficiency of the entire rectifier. The converter can make the input current well follow the input voltage and realize the function of power factor correction. By controlling the output voltage, the converter achieves stable DC voltage output. In addition, the converter has a high-frequency transformer, which can achieve electrical isolation.

The invention discloses a direct power control method of a three-phase PWM rectifier. According to the three-phase current and three-phase voltage of the network side of the three-phase PWM rectifier,the instantaneous active power and the instantaneous reactive power of the three-phase PWM rectifier are calculated to construct the average state space model of the three-phase PWM rectifier. A decoupling control signal is introduced into the average state space model of the three-phase PWM rectifier. Uncertain terms in the system are taken into account. A reactive power neural network adaptiveBackstepping controller and a neural network adaptive Backstepping controller of direct current output voltage are designed. Related parameters are input into the reactive power neural network adaptive Backstepping controller and the neural network adaptive Backstepping controller of direct current output voltage to acquire the corresponding output control rate. Coupling transformation is carriedout on the output control rate. The switching control signal of the three-phase PWM rectifier is acquired according to the SVPWM model. The control method provided by the invention has the advantagesof small calculation amount, simple parameter adjustment and good robustness.

The invention discloses a control method of a three-phase PWM (pulse width modulation) rectification based on novel model prediction control. The control method mainly consists of an outer voltage loop and a model prediction control step, wherein the outer voltage loop is a PI link, and the model prediction control is an inner current loop control. According to key points of the control method of the three-phase PWM rectifier, the algorithm is simplified on the basis of traditional finite set model prediction control, the switch actuation times is reduced, the switch frequency is reduced, the switch actions at two adjacent sampling moments are mutually associated to each other, a feedback characteristic is realized, and the switch action is not random and irregular. According to the control method of the three-phase PWM rectifier, the advantages of the finite model prediction control are maintained, the advantages such as rapidness in control algorithm and low switch loss can be achieved.

The invention discloses a method and system for eliminating three-phase rectifier harmonic waves based on repetitive control. The method comprises the steps that a first PI controller model and a repetitive controller model provided with a compensator and added with an attenuation link in a feedback loop are established, wherein the compensator is a PI controller model; three-phase current of a PWM rectifier is obtained, and coordinates are converted into current id and iq; the current id and the given value id* are input to the first PI controller model and the repetitive controller model after being subtracted, and a first value and a second value are respectively output; the current iq and the given value iq* are input to the first PI controller model and the repetitive controller model after being subtracted, and a third value and a fourth value are respectively output; the first value, the second value and harmonic disturbance are superposed to produce Ud; the third value, the fourth value and harmonic disturbance are superimposed to generate Uq; Ud and Uq coordinates are transformed into Ualpha and Ubeta; pulse modulation is conducted on the Ualpha and Ubeta, and the Ualpha and Ubeta are transmitted to a three-phase PWM rectifier IGBT switch tube. The system has very good inhibiting capacity and can reduce the dependence on models.

The invention discloses a multi-phase and high-power generation-conversion integrated system and a control method thereof. The multi-phase and high-power generation-conversion integrated system comprises a modular multilevel inverter and a multi-phase permanent magnet generator, wherein a three-phase structure is adopted by the modular multilevel inverter; each phase is formed by connecting an upper bridge arm and a lower bridge arm in series; each bridge arm is formed by connecting n sub-modules and a filter inductor in series; connection points of the filter inductors of the upper bridge arms and the lower bridge arms form output ends of the bridge arms of the corresponding phases to be connected to a public power network; each sub-module comprises a three-phase PWM rectifier, a capacitor and two series-connected IGBT tubes; 6n three-phase windings of the multi-phase permanent magnet generator are connected to AC ends of 6n three-phase PWM rectifiers of the modular multilevel inverter in a manner of one-to-one correspondence; and a DC output end of each three-phase PWM rectifier is connected with the corresponding capacitor in parallel and also connected with two ends of two corresponding series-connected IGBT tubes in parallel. The multi-phase and high-power generation-conversion integrated system has a modular structure design and a good control characteristic, and flexible connection between a power generation system and the power network is easy to implement.

The invention discloses a three-phase PWM rectifier based on multi-sliding-mode variable structure control. The rectifier comprises three portions of a three-phase PWM rectifier main circuit, a voltage outer loop and a current inner loop. The current inner loop adopts the sliding-mode variable structure control of input and output feedback linearization. An input current follows an input voltage and a distortion is small so that a system is guaranteed to operate in a unit power factor mode and possess a low harmonic wave content. The voltage outer loop adopts a sliding-mode variable structurecontrol strategy based on an exponential approach law so as to increase a starting speed of the system. A stable state characteristic and a dynamic characteristic are further improved, and system jitter can be effectively reduced. By using the control strategy, a disadvantage that input and output feedback linearization control excessively depends on an accurate system mathematics model is effectively overcome; and when a system parameter changes, high robustness can be maintained so that the rectifier is suitable for actual engineering application.

The invention discloses a phase sequence self-adaption control method of a three-phase PWM rectifier. The method comprises the steps that the positive phase sequence and the negative phase sequence ofnetwork voltage are accurately identified through an improved soft phase-locked loop, and the positive-sequence phase angle of the network voltage is accurately locked all the time; according to thepositive and negative phase sequences of the network voltage, the phase sequence of a control algorithm is adjusted, and the normal operation of equipment is achieved under the condition of the negative-sequence network voltage. By means of the control method, artificial judgment using the field network voltage phase sequence is omitted, the problem of the normal operation of the equipment under the condition of a wrong phase sequence is solved, the control method has a very high practicable value in the application field, and the application prospect is limitless.

A sliding mode variable structure direct power control method for a PWM rectifier discloses a sliding mode variable structure direct power control method for a PWM rectifier, including three parts: a three-phase PWM rectifier circuit, a direct power control, and a sliding mode variable structure control. Using the method proposed by the present invention to control the PWM rectifier can not only eliminate the disadvantages of the rectifier harmonics caused by the unfixed switching frequency in the direct power control of the traditional table look-up method, but also reduce the rotation coordinate transformation under the current closed-loop control method The instantaneous power error caused by the time improves the transient response performance of the system. At the same time, the control method has good robustness and static and dynamic performance.

The invention discloses an inductance separating type integrated vehicle-charging topological and inductive parameter identification method. The method comprises the following steps: when output endsa, b, c of an electrically driven converter of an interface alternating current motor are switched to a ground three-phase random inductor end, and the input and output of a bidirectional direct current converter are electrically isolated, combining power flow paths in the electrically driven and charging modes into one, and forming an equal-power integrated vehicle-charging system topology in which a three-phase network side inductor is separated from a PWM rectifier; after the random inductor is connected into a vehicle integrated charging rectifier, pre-charging a direct current bus capacitor; acquiring a three-phase voltage, current and direct current bus voltage instantaneous information of the network side, according to an instantaneous mathematical model of a three-phase static coordinate system of an uncontrolled rectifier, orderly building an instantaneous voltage loop equation of adjacent two-phase uncontrolled rectifiers; and a controlled rectification stage is based on a three-phase uncontrolled rectification instantaneous voltage loop equation, a controllable rectification stage is based on an integral mathematical model of the three-phase PWM rectifier under a two-phase static coordinate system, respectively performing on-line identification of an initial value and a fluctuation value of the three-phase random inductor by using the curve fitting and a recursive form of a least square method.