655 results about "PWM rectifier" patented technology

The invention relates to a modularized energy feedback traction power supply device and a control method thereof, wherein, the device comprises a multi-winding transformer, a plurality of PWM rectifier units and a central controller, wherein, the multi-winding transformer is provided with a primary winding and a plurality of secondary windings, and all of the secondary windings have the same connecting mode; each secondary winding of the transformer is connected with a PWM rectifier unit; the direct-current outputs of all the PWM rectifier units are connected to a direct-current bus of the general power supply device in serials. Double closed-loop control of voltage and current is adopted; an outer loop of direct-current voltage is arranged on the central controller and an inner loop based on synchronous rotating frame is arranged on each PWM rectifier unit. The power supply device is remarkably characterized by easy modularization, large capacity, bipolar energy transmission, high power factor, small current harmonic wave and stable direct-current voltage.

The invention provides a network voltage disturbance generating device, which comprises a three-phase bridge type PWM (Pulse Width Modulation) rectifier and a three-H-bridge three-phase four-wire-system PWM inverter, wherein the alternating current side of the rectifier is connected with an electric network through an L type filter; the direct current side of the rectifier is connected in series with the direct current side of the three-H-bridge three-phase four-wire-system PWM inverter; an LC filter is connected to the alternating current side of the three-H-bridge three-phase four-wire-system PWM inverter; the output end of the LC filter is connected with an isolation transformer; and the secondary side of the isolation transformer is connected with a load. The invention further provides a control method suitable for the device. Due to the adoption of the device provided by the invention, the simulation of a network voltage amplitude, frequency disturbance and an electric network harmonic phenomenon can be realized, bilateral flow of energy can be realized, and active energy transmitted by tested solar-powered grid-connected equipment is fed back to the electric network; and the control method is easy and convenient to implement, and a target reference value can be accurately tracked; and moreover, quick response and small steady-state errors are realized, so that electric network disturbance can be simulated accurately.

The invention discloses a fault tolerant control method for open circuit faults of a three-phase bridge PWM rectifier switching tube and belongs to the field of three-phase AC-DC (Alternating Current-Direct Current) conversion. The invention solves problems that multi-tube fault tolerant control is imperfect, the hardware cost is high and the like of the conventional fault tolerant scheme. According to the method, the characteristic that a local space voltage vector changes when a fault occurs to any switching tube of a three-phase bridge PWM rectifier is utilized; a PWM switching mode is corrected, i.e., a fundamental voltage vector is selected again and the action sequence and time is adjusted; and composition is conducted again to recover or approach an original rotary reference voltage vector, so that the normal operation of a system is maintained, and the fault tolerant control operation is achieved. According to the method disclosed by the invention, the effective fault tolerant control operation can be achieved when an open circuit fault occurs to a single switching tube and multiple switching tubes in the three-phase bridge PWM rectifier, and only a software algorithm is required. The method is simple and easy to achieve while no additional hardware cost is required.

The invention discloses an electric vehicle charging system with high power quality. A direct-current charger of the electric vehicle charging system is an electric vehicle charger on the basis of a voltage type PWM (pulse width modulation) rectifier, and a control system of the PWM rectifier is of a double-closed-loop control structure with a traditional outer PI (proportion integration) regulating voltage loop and an inner dead-beat control current loop. Harmonic current which is injected into a power grid by the electric vehicle charging system is reduced, and the power quality of the power grid is improved. Besides, an inverter link is added to the electric vehicle charging system, so that the electric vehicle charging system can be connected with a battery pack to charge the battery pack or can be connected with an air conditioning load for electric discharge according to load change conditions (namely a peak period, a valley period and the like) of the power grid, energy can flow in positive and negative directions, the electric vehicle charging system can run in a rectification state to receive the energy from a power-grid side, can also run in an inversion state to transmit the energy to the load, and runs in an approximate unity power factor state, and the utilization efficiency of power resources is improved.

The invention discloses a novel two-stage bidirectional energy storage converter control system and a control method thereof. An energy storage converter main circuit mainly comprises a three-phase voltage type PWM (Pulse Width Modulation) rectifier, a novel half bridge three-level push-pull bidirectional DC-DC converter, a charging-discharging buffer interface circuit for limiting battery charging current, and a battery pack module. A control system circuit mainly comprises a voltage and current sensor, a driving circuit, a protection circuit, a main controller, an SOC (State of Charge) detection module, a radiator, a buzzer, a man-machine interface, a communication interface circuit and a system auxiliary power supply. The alternating-current micro-grid power or voltage and the states of charge of energy storage batteries can be detected in real time, so that the running modes of each generating set and the energy storage converter in a micro-grid system are controlled flexibly, and the effects of 'filling peaks and clipping valleys' in a power system, smoothening power in a wind-solar hybrid micro-grid system and the like are achieved. Moreover, the control system has the advantages of high power density, small size, high efficiency, low harmonic content, high reliability, high self-control degree and the like.

A rectifier includes a switching circuit and a controller. The switching circuit is coupled between positive and negative buses and a plurality of input voltage sources. The switching circuit includes a plurality of pairs of switching devices. Each pair is associated with one of the input voltage sources. The controller includes first and second control loops operable to generate control signals for operating the pairs of switching devices to generate a potential across the positive and negative buses. The controller is further operable to estimate a line inductance seen by the rectifier based on at least one of the control signals and generate an inductance compensation gain factor for applying to the control loops based on the estimated line inductance.

The invention relates to an electric energy quality regulating system based on energy storing of a super capacitor, which belongs to the field of electric energy quality regulation technology and is characterized by comprising a three-phase voltage type PWM (Pulse Width Modulation) rectifier 3, a bidirectional DC/DC converter 4 and the super capacitor 5; the system is connected with a power network system 1 in parallel; during normal operation, the three-phase voltage type PWM rectifier 3 is used for stabilizing DC voltage and simultaneously realizing reactive harmonic compensation; the bidirectional DC/DC converter 4 is used for controlling the charging of the super capacitor 5; when the power network system 1 has short-circuit fault, the super capacitor 5 is used for controlling the output of stable DC voltage by the bidirectional DC/DC converter 4; and the three-phase voltage type PWM rectifier 3 is used for sending out reactive power to support the voltage of the power network system 1 and improve the voltage quality. The regulating system has the capabilities of reactive harmonic compensation and low-voltage crossing and reduces equipment redundancy. The super capacitor 5 has longer service life, thereby reducing the operating cost. The system can charge the super capacitor 5, thereby saving extra charging devices.

The invention discloses a model predication control method of a three-phase PWM (pulse width modulation) rectifier under unbalanced voltage. The technical scheme mainly includes that the model predication control method of three-phase PWM rectifier under unbalanced voltage includes: negating input active power and input reactive power which are obtained by computation, enabling negated values to pass through proportional resonant controllers, obtaining second harmonic compensation voltages under a two-phase rotating coordinate system by means of compensating voltage computation, then obtaining second harmonic compensation voltages under a two-phase static coordinate system by means of reverse Park transformation, compensating the second harmonic compensation voltages under the two-phase static coordinate system into output voltage subjected to traditional model predication control, enabling voltage vectors with the minimum absolute values, which are differences of current given values and current predication values, to serve as optimal voltage vectors by value function selection, and using the optimal voltage vectors as switching signals for controlling power devices. The model predication control method of the three-phase PWM rectifier under unbalanced voltage is capable of effectively inhibiting second harmonic fluctuation of input power of the rectifier under the condition of unbalanced power grid voltage, and is simple in control structure, short in system delay and capable of simultaneously eliminating secondary pulses of input active power and input reactive power of the system.

The invention relates to a hybrid parallel type high-voltage direct current traction power supply current transformer and a control method thereof. The hybrid parallel type high-voltage direct current traction power supply current transformer is characterized by comprising a set of pulse width modulation (PWM) rectifier units and a set of diode rectifier units, wherein both an input end of the PWM rectifier units and an input end of the diode rectifier units are connected with an alternating current electric network, and an output end of the PWM rectifier units and an output end of the diode rectifier units are connected in parallel to realize high-voltage direct current output. Because the PWM rectifier units and the diode rectifier units are connected in series, the direct current output voltage of the entire current transformer is improved, the power supply distance is prolonged, and the contact net loss is reduced. Meanwhile, equipment investment is reduced, and the reliability of a system is improved. The hybrid parallel type high-voltage direct current traction power supply current transformer and the control method thereof can be widely applied to urban railway transit traction power supply systems.

The invention discloses a symmetrical three-section voltage vector pulse width modulation method for a three-level PWM rectifier, which comprises the following steps: 1. voltage vector area division: dividing one sector according to every 60 degrees, setting up three small areas in each sector, and calculating by taking quadrant as a unit; 2. voltage vector synthesis: using the adjacent three-voltage vector synthesis of each area according to the areas divided in the step one; 3. voltage vector acting time calculation: calculating the acting time of each synthesized voltage vector of each area according to V-t characteristics; and 4. voltage vector pulse width modulation: utilizing the voltage vector acting time calculated in the step three to carry out the voltage vector pulse width modulation, i.e. realizing the voltage vector pulse width modulation by a DSP+CPLD three-level PWM rectifier system based on a logical approach. The method realizes the self-balancing of the voltage vector pulse width modulation; the voltage vector subareas are fewer, and the algorithm is simple.

The invention discloses a low-frequency PWM rectifier and compensation capacitor based wireless charging apparatus. The wireless charging apparatus comprises a rectifying circuit, a filtering voltage-stabilizing capacitor, an inversion power switch, a launching circuit resonant capacitor, a hall current sensor, a launching circuit resonant coil, a receiving circuit resonant coil, a compensation capacitor, a rectifying power switch, a resonant filtering capacitor, a resonant filtering inductor, a load resistor, a high frequency inversion driving circuit, a microprocessor, an analog-digital converter, a hall voltage sensor, a signal detection conditioning circuit and a PWM rectifier driving circuit. According to the wireless charging apparatus, the resonance of the launching circuit and the receiving circuit is realized; the direct current voltage output range of the charging apparatus can be adjusted by the compensation capacitor; meanwhile, the operating frequency and loss of the power switch device are greatly lowered; the operating frequency section of the system is expanded; and the design flexibility of the resonant coil is improved as well.

The invention discloses a magnetic coupling resonant wireless electric energy transmission device based on a low frequency PWM rectifier. The device comprises a rectifier, a voltage stabilizing capacitor, an inverter power switch, an emission circuit resonant capacitor, an emission circuit resonant coil, an emission circuit current sampling resistor, a receiving circuit resonant coil, a receiving circuit current sampling resistor, a rectifier power switch, a resonant filter capacitor, a resonant filter inductor, a load resistor, a transmitting end signal conditioning circuit, a transmitting end analog to digital converter, a transmitting end microprocessor, a transmitting end high frequency inverter driving circuit, an induction voltage detection coil, a receiving end signal conditioning circuit, a receiving end analog to digital converter, a receiving end microprocessor and a PWM rectifier driving circuit. According to the device, the resonance of an emission loop is ensured, the tracking of transmitting end working frequency, the resonance of a receiving circuit and the constant output of load voltage are realized, the requirement of working frequency by a power switch device is greatly reduced, and a space is provided for the device to raise power supply working frequency.

The invention discloses a PWM rectifier control method based on model prediction and voltage square control. The square of the output direct-current side voltage is controlled to serve as the given inner ring active current, the quick response of a controller is ensured through the linear relation between the square of the voltage and the active current, and the anti-disturbance capacity of a rectifier is further enhanced through the model prediction control of the inner ring current. The cost function of model prediction is quickly obtained through the finite set on-off state so that the control method can be easily achieved on a digital controller. The dynamic response and the anti-disturbance capacity of the whole controller can be enhanced through the selection of the weighting coefficient in the cost function and the coordination with the pre-charging soft start strategy. By means of the double-closed-loop control method, the quick response and the high anti-disturbance capacity for load disturbance are achieved while it is ensured that the alternating-current side of the rectifier reaches the unit power factor and the current total harmonic distortion rate reaches the national standard requirement. By means of the double-closed-loop control method combined with the voltage square model prediction control, the control over the unit power factor and the disturbance resistance of the three-phase voltage type PWM rectifier is achieved, and great reference value is provided for engineering.

The invention discloses a parameter adjusting method of a variable parameter PI adjuster. The parameter adjusting method comprises the following steps of determining an error between the current voltage of a DC (direct current) bus and a target voltage; determining the deviation state and the variation trend of the error and correspondingly adjusting a proportion adjusting coefficient Kp; according to the Kp and integral terms, outputting a parameter Ki and adjusting the final PI parameter. Therefore, the proportion adjusting coefficient Kp is adjusted correspondingly according to the deviation state and the variation trend of the error and the PI parameter is adjusted in the end; due to the fact that the Kp is adjusted according to the error, during the process of controlling a PWM (pulse-width modulation) rectifier through the parameter, dynamic properties and steady-state properties can be both guaranteed.

A PWM rectifier includes a main circuit unit carrying out AC-DC power conversion by PWM-control, a PWM control unit PWM-controlling the main circuit unit, a DC voltage detection unit detecting a DC voltage across a smoothing capacitor connected to the DC-side of the main circuit unit, a DC voltage storage unit storing respective DC voltages at the start and end times of an initial boost period during which the smoothing capacitor having been charged to an AC voltage peak value is further charged to a higher voltage, an input power calculation unit calculating input power flowing in from the AC-side based on an AC voltage and current, an integral power calculation unit calculating integral power from the input power over the initial boost period, and a capacitance calculation unit calculating the capacitance of the smoothing capacitor based on the respective DC voltages and the integral power.

The invention relates to an AC-DC-AC auxiliary converter of a motor train unit and a working process of the AC-DC-AC auxiliary converter. The auxiliary converter comprises a controller, a pre-charge circuit, a boosting transformer, an input filter circuit, a rectifier circuit, a discharge circuit, an inverter module, an output filter module and an output contactor, wherein the pre-charge circuit, the boosting transformer, the input filter circuit, the rectifier circuit, the discharge circuit, the inverter module, the output filter module and the output contactor are connected with the controller; when the auxiliary converter is started, the pre-charge circuit is charged; when charging voltage reaches a certain level, the pre-charge circuit is disconnected and the auxiliary converter works without resistance; when the auxiliary converter works normally, the auxiliary converter inputs three-phase AC and boosts the three-phase AC through the boosting transformer TR1; when input voltage is over a zero point, a PWM rectifier is started, output voltage reaches stable DC voltage through a unipolar four-quadrant double closed-loop control algorithm of the PWM rectifier; rated three-phase AC voltage is output through a voltage space vector SVPWM control mode of the inverter; and a load is provided with electricity through the output filter circuit and the output contactor. By the auxiliary converter and the working process thereof, the power supply reliability of the auxiliary converter can be improved.

The embodiment of the invention provides a PWM (Pulse-Width Modulation) rectifier controlling method and a PWM rectifier. The PWM rectifier controlling method is a passivity control method based on repeated control and compensation, and comprises the following steps: a control law of the PWM rectifier based on the interconnection and damping configuration of port controlled dissipation Hamilton models is obtained with a Lagrange-Charpy integral method; and a composite controller including repeated control and passive control is used as a controller of the PWM rectifier, and the passive control is compensated by the repeated control according to the control law so as to suppress periodic interference. According to the embodiment of the invention, PWM rectification of a unit power factor can be realized, and at the same time the harmonic interference of a power grid is better suppressed under the condition of not detecting load harmonic current so as to improve power quality. Compared with the conventional PWM rectifier, the PWM rectifier disclosed by the invention has the functions of harmonic suppression and reactive compensation under the condition of not increasing hardware cost.

The invention discloses a novel power quality control system with a fault current-limiting function and a control method thereof. The novel power quality control system with the fault current-limiting function comprises a three-phase H-leg PWM rectifier, a three-phase four-leg series converter, a thyristor controlled short-circuit branch, a thyristor controlled bypass reactance branch and a corresponding control method. The PWM rectifier and the three-phase four-leg series converter share one direct current side to achieve bidirectional energy conversion, the series converter compensates the fall, the raising and three-phase imbalance of the grid voltage and solves the quality problem of the harmonic voltage, at the same time, the system controls the series converter, the thyristor controlled short-circuit branch and the thyristor controlled bypass reactance branch to limit the current when various short-circuit faults occur on the grid, and thus the purposes of stabilizing the loaded supply voltage, improving power supply quality, protecting the grid and load equipment when short-circuit faults occur and improving the safety and stability of the electric power system are achieved.

The invention provides a disturbance generation device which is used for detecting the network access of a wind generating set and detecting and evaluating the grid-connected operation of a large-scale wind power station. The disturbance generation device generates various voltages for wind generator test, and comprises a low-frequency voltage disturbance device and a high-frequency voltage disturbance device, wherein the low-frequency voltage disturbance device is composed of a starting resistor, a reduction transformer, a filter, a parallel voltage source current converter module and a boosting transformer, and is used for realizing the function of low-frequency voltage disturbance; and the high-frequency voltage disturbance device is composed of a starting resistor, a rectifier transformer, a pulse-width modulation (PWM) rectifier module, a cascading H-bridge module and a filter, and is used for realizing the function of outputting second to twenty-fifth harmonic voltage, thereby realizing two-way flow of energy and meeting requirements of the wind generator for switching between a power-driven state or a power generation state.

The invention provides a direct power control method of a voltage source PWM (pulse width modulation) rectifier system. Based on an inner-loop power and outer-loop voltage control method adopted in a DPC (data processing control) method, set values of active power and reactive power are compared with actual values, and a voltage vector is selected by querying a switch list to control the on-off state of the PWM rectifier. According to the control method provided by the invention, a state variable marking the active power and the reactive power is added, the location of a space vector is redefined and a segmented switch list is constructed, thus enhancing the decoupling control on the active power and the reactive power and the response capability, and improving the power factor of the rectifier. The calculation and experiment results show that the grid side input current is sine and the instantaneous power dynamic and static control characteristics of the system are better.

The invention discloses an improved dead-beat control method for a pulse width modulation (PWM) rectifier at unbalance of voltage of a power grid. According to the technical scheme, the key point is that the improved dead-beat control method for the PWM rectifier at unbalance of voltage of the power grid comprises the following steps of: respectively obtaining an active power double-frequency voltage compensation item and a reactive power double-frequency voltage compensation item by a bandpass filter and a proportion and integration (PI) controller through compensation voltage calculation according to input active power and input reactive power; obtaining a reference value of input voltage of the converter by taking the voltage compensation items as inputs of a built voltage reference value calculation model; performing reversed Park conversion by taking the voltage position angle of the power grid as a conversion angle to obtain input voltage under a two-phase static coordinate system; and generating a switching signal for controlling a power device by performing space vector pulse width modulation on the voltage signal. By the method, the model of the PWM rectifier can be compensated in real time, the pulses of the input active power and the input reactive power of the PWM rectifier can be effectively suppressed, and the voltage fluctuation of a direct current bus can be reduced.

The invention discloses a multi-phase direct-drive permanent-magnet wind power generation variable current integrated system and a control method thereof. The system comprises a multi-phase direct-drive permanent-magnet wind power generator and a modular multilevel inverter, wherein the quantity of three-phase windings of the multi-phase direct-drive permanent-magnet wind power generator is 6n (n is equal to 1, 2, 3 and so on), the modular multilevel inverter comprises six three-phase bridge arms, each bridge arm comprises n sub-modules and a filter inductor, each sub-module comprises a PWM (Pulse Width Modulation) rectifier, two IGBTs (Insulated Gate Bipolar Transistors) and a capacitor, the two IGBTs are connected in series and then are connected in parallel with the capacitor and a DC side of the PWM rectifier, and an AC side of the PWM rectifier is connected with one of the three-phase windings of the multi-phase direct-drive permanent-magnet wind power generator. In the wind power generation system, modular series-parallel connection is performed on three-phase branches, each three-phase winding of the wind power generator is controlled, thus, maximum wind energy capturing and high-voltage direct grid connection of a multi-phase permanent-magnet synchronous motor can be achieved, and a grid-connection transformer is omitted.