41results about How to "Achieve sinusoidal" patented technology

The invention discloses a charging device for a tramcar super-capacitor, comprising two independently operating rectification voltage regulation circuits; the rectification voltage regulation circuits comprise LCL filter capacitor modules, PWM rectifier bridge modules and DC/DC convertor modules which are sequentially connected; the DC/DC convertor modules are connected to an isolation switch cabinet through clamping diodes; the invention also discloses a charging method for the tramcar super-capacitor, comprising: a constant current charging stage and a constant voltage charging stage, after the tramcar super-capacitor is charged to the set value, switching from the constant current charging stage to the constant voltage charging stage, taking the integral output value of a current PI regulator before switching as the integral initial value of a voltage PI regulator after switching, and realizing seamless switching of the two stages.

A novel power unit of a cascade unit comprises a DC voltage driver unit, a voltage lifting chopping part and an inverting part. The DC voltage drive of the power unit adopts a three-phase bridge type uncontrolled rectifier system, and two controllable IGBTs and two fast diodes are added at the DC side, thus forming a DC voltage lifting chopping circuit which can control the voltage at the DC link and broaden the scope of AC output voltage amplitude; an inverter adopts IGBT single-phase full bridge controllable output, and a fault bypass circuit is added at the output terminal of the inverter; and a rectifier transformer is of common wiring multi-winding type, and all secondary windings have the same wiring mode. A voltage lifting half-bridge and a neutral point in a filter capacitor set are connected with the neutral point in a harmonic current circuit to provide a channel for injecting zero sequence current so as to achieve the sinusoid of high power factor rectification and the input current.

The invention discloses a brushless direct current motor control system based on an electrolytic capacitor-free inverter and a control method. The method comprises the steps of detecting system input voltage, bus current, motor speed and a motor rotor position; carrying out error adjustment on given rotating speed and actual rotating speed; calculating bus given current according to the input voltage, speed ring output and a thin-film capacitor capacitance value; calculating bus error current, and carrying out PI adjustment, thus obtaining a duty ratio controlled by square wave PWM; obtaining a square wave PWM drive signal according to the duty ratio, the motor rotor position and a commutation logic; modulating the inverter for controlling a motor. According to the brushless direct current motor control system based on the electrolytic capacitor-free inverter and the control method provided by the invention, the application of the electrolytic capacitor-free inverter in the brushless direct current motor control system can be realized, a grid side high power factor is acquired, a control structure is simplified, and the system reliability is improved.

A single-phase five-level power factor correction circuit based on a hybrid H bridge comprises switching tubes Q1, Q2 and Q3. One side of an alternating-current power supply Vs is connected with an anode of a diode D1 and a cathode of a diode D2, and a connection node forms an end point b. The other side of the alternating-current power supply Vs is connected with one end of an inductor L, the other end of the inductor L is connected with the anode of a diode D3 and the cathode of a diode D4, and connection nodes form an end point a. The drain electrode of the switching tube Q3 is connected with the cathode of the diode D1, the cathode of the diode D3, the anode of the diode D7, the drain electrode of the switching tube Q1 and a connection node to form an end point c. The source electrodeof the switching tube Q3 is connected with the anode of a diode D2, the anode of a diode D4, the cathode of a diode D8 and the source electrode of a switching tube Q2, and the connection node forms anend point d. The source of the switching tube Q2 is connected with the drain of the switching tube Q1, and the connection node forms an end point n. The cathode of the diode D7 is connected with oneend of the capacitor C1, and a connection node forms an end point p. The negative electrode of the capacitor C2 is connected with the anode of the diode D8 and the connection node forms an end point m. And the endpoint a, the endpoint c, the endpoint d and the endpoint n form four ports of the hybrid H-bridge network structure. The circuit structure has the advantages of low cost, high reliability, simple control system design and the like.

Disclosed is a power unit of a harmonic injection direct-drive wind-power converter, comprising a rectifier circuit, a voltage booster chopper circuit and an inverter circuit. The rectifier circuit adopts three-phase bridge uncontrolled rectification mode; two controllable power tubes and two fast diodes are additionally arranged on the dc side to construct the dc voltage booster chopper circuit, so the voltage in dc link is controlled, and the energy is fed to grid under low wind speed through the voltage boosting on dc side. The inverter adopts three-phase half-bridge controllable output constructed by full-controllable power tubes. The neutral point of a voltage booster half bridge and a filter capacitor group is connected with the neutral point of a harmonic current injection circuit to provide a channel for the injection of zero-sequence current and ensure the high power factor rectification and input current to be sine, and avoid the power factor reduction of power generator and the oscillation of power generator torque.

The invention discloses a three-phase two-bridge arm three-level mixed rectifier. The mixed rectifier includes two rectifiers Z1, Z2, a voltage sampling circuit, a current sampling circuit, a protection circuit, a zero cross detection circuit, a DSP control module, a PWM drive circuit, wherein the rectifier Z1 includes eight IGBT switch tubes, two asymmetrical three-level rectifier bridge each ofwhich is composed of an upper and a lower capacitor, and a filter. The rectifier Z2 is a traditional three-phase boost PFC circuit. The mixed rectifier herein uses the aforementioned structure and adopts the double closed-loop control technology in such a manner that the voltage outer-loop uses PI control and the voltage inner-loop uses passivity-based control and constant frequency PWM control. The mixed rectifier is advantaged by the capability of suppressing harmonic waves that are injected to a power grid, realizing AC side current sinusoidal and unity power factor, and higher current tracking capability and stable system control, and can fast track the given value of a DC side voltage. According to the invention, the mixed rectifier is applicable to scenarios such as high-voltage DC transmission converter stations, wind power and solar energy development, electric vehicle charging piles that are characterized by high requirements and high efficiency.

A novel unidirectional three-phase three-level rectifier based on a soft switching technology comprises a unidirectional three-level rectifying loop, a resonant circuit, a buffer loop, a voltage sampling circuit, a current sampling circuit, a zero-crossing comparison circuit, a DSP control module and a PWM drive circuit, wherein the unidirectional three-phase three-level rectifying loop is composed of three rectifying bridge arms including six power switch tubes, so that the number of elements is effectively reduced, the structure is simplified, and the cost is reduced. The resonant loop is composed of a resonant inductor, a clamping capacitor, an auxiliary switch and the like, zero-voltage switching-on of main switches can be achieved, and switching loss and switching noise are effectively reduced. And the buffer loop is composed of six capacitors connected in parallel with the main switches, so that the turn-off process of the main switches can be softer. By the adoption of the structure, a double closed-loop control mode is adopted, a control method combining PI control and SVPWM is adopted for a current inner loop and a voltage outer loop, and therefore harmonic waves are effectively restrained, and alternating-current-side current sine, voltage stable output and grid-side unit power factor control are achieved.

The invention provides a multiphase permanent magnet reluctance motor, relates to the technical field of motors, and in particular relates to the multiphase permanent magnet reluctance motor. The invention solves the problems of low torque density, high peak current and high winding copper consumption of the existing switch reluctance motor, and the problems of large motor torque fluctuation and high vibration and noise, which are caused by the fact that the winding of each phase works in the switching state. According to the multiphase permanent magnet reluctance motor provided by the invention, permanent magnet excitation is introduced on the stator side; windings work in a full electric cycle and generate unidirectional torque, which improves the torque density of the motor; the motor is driven by bipolar current, which improves the winding utilization and reduces the copper consumption of the motor; the motor can be driven by a traditional inverter circuit; the driving system has the advantages of low cost and high practicability; sinusoidalization of winding flux linkage and counter emf is realized; and torque ripple and vibration and noise of the motor are reduced. The invention provides the motor.

The invention discloses a current source grid-connecting converter control method, comprising: subtracting a given DC voltage reference value from a sampled DC side outputted voltage to obtain a voltage error signal; via the control of a first PI regulator, obtaining a DC current reference value; comparing the sampled DC side outputted current with a current reference value to obtain a current error signal controlled by a second PI regulator, wherein the DC side outputted current is controlled by the feedback resonance; subtracting the two outputs to obtain a modulation signal amplitude; using the phase angle theta of the sampled grid voltage and the detected grid voltage; multiplying the modulation signal amplitude by the orthogonal unit signals sin theta and -cos theta to obtain the modulation signals M[alpha] and M[beta] in a two-phase stationary coordinate system; using a notch filter to filter the third harmonic wave in the modulation signals M[alpha] and M[beta] to obtain new modulation signals M[alpha] and M[beta]; then respectively calculating the amplitude m and the phase angle information; and through the space vector modulation method, generating the driving signals. The method of the invention can effectively reduce the double frequency pulsation at the direct current output side and realize the sine wave of the network side current at the same time.

The invention provides a three-phase APFC correction circuit and method and an air conditioner. The three-phase APFC correction circuit comprises: three-phase voltage sources for providing three-phasealternating current; three first bridge arms, wherein one end of each first bridge arm is connected with each of the three-phase voltage sources, and the other ends of at least two first bridge armsare connected with one resistor; and a processing circuit connected to at least two resistors for determining current flowing through the at least two resistor in one PWM period and further obtainingthe three-phase current of the three-phase alternating current. The sampling of the three-phase current is improved, and the three-phase current can be determined by the current on the at least two resistors, thereby avoiding the use of the current sensor, and achieving the sinusoidalization of the three-phase current while saving cost.

The invention provides a cascaded H-bridge converter control method under a power grid harmonic background, and provides an improved unit vector directional direct current control strategy under a natural coordinate system by taking improvement of the control performance of a converter under the power grid harmonic background as a target and taking a single-phase cascaded H-bridge converter as anobject so as to enable the output current power factor to be controllable, and the total harmonic distortion rate of the current to meet the requirements of a power grid. According to the control method, the fundamental frequency component of the power grid is rapidly extracted by using a delay signal cancellation method, and an ideal unit vector under a natural coordinate is solved for orientation, so that an accurate current reference value is obtained, and direct current control is carried out by using a proportional resonance controller with excellent performance, and the influence of theharmonic background on the control system is further eliminated through distortion voltage proportion feedforward.

The invention discloses a three-phase voltage type SVPWM rectifier, which comprises three parts: a main circuit of the SVPWM rectifier, decoupling control and SVPWM modulation. The three-phase voltage rectifier is an active and effective method to suppress harmonic pollution and improve power quality. It has the advantages of realizing sinusoidal input current at the grid side, high power factor, low harmonic pollution, constant DC voltage control, and bidirectional flow of energy. The present invention proposes to design the minimum capacitance value according to the maximum rising rate of the active current and the maximum falling rate of the DC voltage. The design of the rectifier control system is to realize the non-coupling and independent control of the active and reactive components of the rectifier grid side through the introduction of ip feed-forward compensation decoupling control.

The invention relates to an IGBT-based voltage-adjustable PWM rectifier topology, comprising a three-phase AC power supply, wherein the three-phase AC power supply is connected to an AC side filter circuit, the output end of the AC side filter circuit is connected to a full control device, the full control device comprises three groups of IGBTs, each group of IGBTs include two power switch tubes that are in reverse series connection, the output end of the full control device is connected to a diode rectifier bridge, the output end of the diode rectifier bridge is connected to the filter circuit, and the filter circuit is connected to the load. According to the IGBT-based voltage-adjustable PWM rectifier topology disclosed by the invention, the problem that a PWM rectifier cannot adjust thevoltage in the prior art can be solved, two trigger modes that are PWM and SVPWM are adopted, the DC output voltage can be adjusted by 0-100%, and in the SVPWM trigger mode, the grid-side sinusoidalcurrent can be realized, and the effects of small grid-side harmonic pollution and high grid-side power factor can be achieved.

The invention belongs to the technical field of electricity, and particularly relates to a DCM single-bridge-arm integrated split source inverter control method for a photovoltaic grid-connected occasion. The method comprises the steps: obtaining the output voltage and current of a photovoltaic cell, obtaining an input voltage reference through an MPPT algorithm, and achieving the MPPT through PIcontrol; obtaining a DC bus voltage, comparing the DC bus voltage with a reference, and outputting an amplitude instruction through PI control; obtaining power grid voltage, and calculating to obtainunit sinusoidal signals with the same frequency and phase as the power grid voltage; multiplying the unit sinusoidal signal by the amplitude instruction to obtain a sinusoidal reference; obtaining a grid current, comparing the grid current with a sine reference, and realizing sine and pure active output of the grid-connected current through PI control. By means of the method, the DCM single-bridge-arm integrated split source inverter can be applied to photovoltaic grid-connected occasions, output waveform overmodulation during light-load operation can be effectively avoided, and the output waveform quality is high. In addition, the invention provides an input filter inductor design method, which can ensure smooth implementation of the control method in the whole working range.