171 results about "Vienna rectifier" patented technology

The invention discloses a generator system for wind power generation and a variable speed control method; the system comprises a permanent magnetic synchronous generator of which the electrical energyoutput is connected with a Vienna rectifier device, and is characterized in that a stator winding of the permanent magnetic synchronous generator comprises two sets of triphase windings with electrical degree difference of 180 degrees and unconnected neutral points thereof; the Vienna rectifier device comprises two Vienna rectifiers with identical structure, which are in parallel connection withthe DC side with a central point O connected with a DC bus capacitance midpoint; the AC side is connected with the two triphase windings of the generator respectively; a Boost inductance of the Viennarectifier is directly provided by the leakage inductance of the windings of the generator; each Vienna rectifier device is controlled by a DSP controller to maintain the balance of the DC bus voltageby the phase current and line voltage collected in the AC side and the bus voltage collected in the DC side; and the variable speed control of the generator is realized by collecting the rotating speed of a fan and the current wind speed.

The invention discloses a controller used for a Vienna rectifier. The Vienna rectifier receives three-phase three-wire alternating-current input and generates three-level direct-current output on a positive bus, a negative bus and a zero line. The controller comprises an alternating-current phase detector, a voltage controller, a current reference generator, a current controller, a zero sequence modulator and a pulse-width modulation (PWM) generator and conducts controlling on a switch element of the Vienna rectifier. The controller can conduct controlling of voltage mean value on the positive bus and the negative bus and controlling on current waveform, and can restrain voltage unbalance of the positive bus and the negative bus in the Vienna rectifier.

The invention discloses a three-level VIENNA rectifier model prediction control system and method under a power grid unbalanced condition. The invention solves problems of the calculation of referencecurrent when the power network is unbalanced; the balance control of dc side voltage and DC side neutral point voltage; three-phase current zero-crossing distortion; control of unit power factor of grid current. The algorithm divides 25 voltage vectors into 6 sectors according to the current direction and 8 voltage vectors in each sector. Then five voltage vectors are selected according to the deviation of the neutral point voltage, and the optimal space voltage vector is obtained according to the value function, and the optimal space voltage vector controls the state of the switch transistor, so as to realize the control of the three-phase three-level VIENNA rectifier. The algorithm does not require the separation of positive and negative sequence of voltage and current, phase lock of voltage, current inner loop control module and modulation module when the power network is unbalanced.

The invention discloses a VIENNA rectifier neutral point potential alternating-direct-current component balance control method which can reduce design capacity of a capacitor on a direct-current side and a filter on an alternating-current side and save cost of a tri-level VIENNA rectifier. On the basis of common mode component injection modulation, a common mode component direct-current compensation coefficient and an alternating-current compensation coefficient are modified dynamically, so that the problem of neutral point unbalance of direct-current and alternating-current components is solved; more importantly, the method guarantees uniformity between triphase alternating-current side harmonic distortion rate and SVPWM while substantially inhibiting neutral point potential low-frequency oscillation in conventional modulation methods and improving quality of output power and can be popularized and applied in the field of battery testing, charging facilities and driving systems.

The invention provides a correction policy of current zero-crossing distortion applicable to all one-way three-phase rectifiers (including three-phase VIENNA rectifiers, three-phase bridgeless rectifiers and all star-connection cascaded three-phase rectifier topologies) based on single-period control. The policy specifically includes following steps: firstly, determining related parameters of a system, then calculating a current distortion initial point, a distortion time and a boundary condition, and finally calculating a parameter introduced compensation amount based on the above parameters.According to the policy, based on the characteristic of single-period direct current control, crossed injection is performed on the feedback of current phase-shift control signals, and superpositionis performed with an original phase-shift feedback amount so that zero-crossing distortion generated by current phase shift of the energy one-way flow three-phase rectifier is corrected without increasing the complexity of the system. According to the policy, the realization is simple, the reliability is high, an effective correction method is provided for the current zero-crossing distortion problem occurring in a single-period control process, and the application range of single-period control is extended.

The present invention provides a modular parallel three-level Vienna rectifier, a control system and a method. The present disclosure effectively suppresses the zero-sequence circulation of a system,and the waveform quality of the input current is improved remarkably, so the invention is suitable for the working conditions that the current distribution proportions of two three-level Vienna rectifier modules are equal and unequal and the input filter inductances are equal and unequal. The elimination of the zero-point distortion of the input current fully considers the influence of the filterinductor on the relative position of the voltage vector and the current vector. The effect of the input current zero-crossing distortion is better than that in a conventional method, and the total harmonic distortion rate of the input current is reduced.

A new single-phase hybrid three-level rectifier comprises a single-phase uncontrollable diode rectifier bridge, a filter, a single-phase VIENNA rectifier bridge, a voltage and current sampling circuit, and a signal conditioning circuit. Through employing the above structure and a single-period control algorithm, the rectifier is simple in control method, is simple in structure, and just needs to collect an output voltage and an input current. The rectifier is very high in robustness, is high in power density, is large in power factor, is stable in output voltage, and is high in system reliability. Compared with a conventional single-phase rectifier, the rectifier provided by the invention can greatly improve the conversion efficiency, is large in application range, can greatly reduce the voltage stress of a power switching tube through employing the three-level structure, and can save a large amount of material resources and financial resources.

The invention relates to a 60-degree coordinate system-based three-phase VIENNA rectifier and a control method, and specifically relates to a three-level VIENNA rectifier and a control method thereof. The invention aims to solve the problems of low power grid power factor, high grid side harmonic component and poor system stability in the prior art. The 60-degree coordinate system-based three-phase VIENNA rectifier includes an inductor group, a main circuit, a DSP control system, a drive module, a grid side voltage signal processing circuit, a grid side current signal processing circuit, a direct voltage sampling module and a load, the inductor group includes a first inductor, a second inductor and a third inductor, the main circuit includes a three-phase VIENNA rectifier circuit, a power grid is connected with an input end of the three-phase VIENNA rectifier circuit through the first inductor, the second inductor and the third inductor, and an output end of the three-phase VIENNA rectifier circuit is connected with the load. The device and the method provided by the invention improve the power factor of the power grid, improve system response speed, and enhance system stability.

The invention discloses a neutral-point-potential control method for a direct current side of a three-phase three-level rectifier and a neutral-point-potential control system for direct current side of the three-phase three-level rectifier, which are applied to digital one-cycle control. The principle of the control method is as follows: firstly collecting a current value of an input side of the rectifier and voltage values of an upper capacitor and a lower capacitor at the direct current side, then calculating an integral initial value of each period in the one-cycle control so as to control the duty ratio of a three-phase switch tube, thereby balancing the neutral-point-potential of the direct current side. A core control system is composed of a DSP and an FPGA. The DSP is mainly used for calculating a zero sequence duty ratio, carrying out PI control over the voltage differences of the upper capacitor and the lower capacitor at the direct current side, calculating the integral initial value of a single cycle, communicating with an upper computer, etc. The FPGA is mainly used for collecting data, judging failures, protecting, realizing the one-cycle control method and the like. The method has the characteristics that the algorithm is simple and easy to realize, the hardware cost is low and the control effect is excellent.

A power supply system and related method for providing a regulated DC output from an unregulated AC input includes a Vienna rectifier having power factor correction circuitry and a series resonant DC to DC converter to provide a regulated DC output. The power supply system further includes one or more compensator circuits coupled in feedback configuration to control the Vienna rectifier and / or the DC to DC converter and avoid a potentially dangerous over-voltage condition at the regulated DC output.

The invention discloses a method for optimizing the input current of a Vienna rectifier, belonging to the field of high power factor conversion devices. The method comprises the following steps of adopting a switching frequency optimization PWM method to establish three-phase reference voltage and generating basic modulation wave, calculating a voltage phase angle generated due to the existence of a filter and determining the scope of compensation, adding compensation voltage to the three-phase reference voltage, generating new modulation wave, allowing the new modulation wave and triangle wave double-carrier wave with same upper and lower amplitudes and phase to be in intersection, and finally obtaining PWM wave which controls the Vienna rectifier. According to the method, the current distortion caused by an LCL filter device can be reduced, thus the input current tracks input voltage, a power factor is improved, and the efficiency of the Vienna rectifier is improved.

The invention relates to a Vienna rectifier control method suitable for a network voltage disturbance situation, discloses an improved current tracking method based on repeated control specific to a three-phase four-wire-system rectifier, and mainly aims to overcome the defects of poor power quality and poor current tracking effect in conventional control. The Vienna rectifier control method is mainly characterized in that (1) voltage harmonic wave information is shielded by means of taking a phase-locked loop output signal as a current tracking signal specific to power grid background harmonics and periodical collapse; and (2) parallel connection of repeated control and conventional PI control is introduced, and repeated controller parameters are reasonably designed, thereby improving the current tracking effect. Compared with the prior art, the Vienna rectifier control method has the advantages that network side current quality is effectively improved, and a direct-current side voltage is kept stable.

The invention discloses a full-power wind power converter used for an electrically excited synchronous generator and belongs to the technical field of wind power generation. The full-power wind power converter comprises a motor side converter, a network side converter and two DC (direct current) side filtering capacitors C1 and C2, wherein the AC (alternating current) input end of the motor side converter is electrically connected with the electrically excited synchronous generator, the DC output end of the motor side converter is electrically connected with the DC bus side of the network side converter through the DC side filtering capacitors, and the AC side of the network side converter is connected with an electric network; the full-power wind power converter also comprises a DC chopper circuit which is connected with the DC bus of the network side converter in parallel; and the motor side converter is a two-quadrant three-level Vienna rectifier, the network side converter is a voltage-type three-level converter which is composed of a power device adopting controllable switches and is of a diode middle point clamping-type topological structure, and the DC side filtering capacitors C1 and C2 are connected in series and then connected with the DC side of the motor side converter in parallel. The full-power wind power converter provided by the invention has the beneficial effects that the distortion factor of the output voltage is effectively reduced, the loss is reduced, the output wave shape quality is good, the cost is saved, the maintenance is convenient.

The invention discloses a predictive control system and a method for reducing the common-mode voltage of a three-level VIENNA rectifier system, which are used for solving the problems of high common-mode voltage of the three-level VIENNA rectifier system in a wind power generation system, zero-crossing point distortion of an AC side current and unbalance of a DC side neutral point voltage. The algorithm limits the common-mode voltage of the system to a very low range. The coupling problem of current zero-crossing distortion and DC neutral-point voltage imbalance control is solved. By classifying the space voltage vectors, the computational complexity is greatly reduced. The algorithm does not need current inner loop controller and PWM modulation module, and avoids the design of complex controller and the selection of complex parameters. The system and method have characteristics of simpleness, directness and effectiveness, which makes the algorithm has high application value.

The invention discloses a compound full-power wind power converter, belonging to the technical field of wind power generation and comprising a machine-side converter, a grid-side converter and a direct-current-side filter capacitor, wherein the machine-side converter is formed by a two-quadrant three-level Vienna rectifier; the grid-side converter is formed by a voltage-type diode neutral point clamped type three-level converter adopting a power device with a controllable switch; the alternating-current input end of the Vienna rectifier is connected with a wind power generator, and the direct-current output end of the Vienna rectifier is connected with the direct-current bus side of the voltage-type diode neutral point clamped type three-level converter by the direct-current-side filter capacitor; and the alternating-current side of the voltage-type diode neutral point clamped type three-level converter is connected with a power grid. The compound full-power wind power converter has the beneficial effects that the system structure is optimized, the cost is reduced, the system maintenance is convenient, the system reliability is improved, variable-speed constant-frequency controls of an electrically excited synchronous generator, a permanent magnet synchronous generator and a rat-cage type asynchronous generator are effectively realized, high-quality electric energy is provided, and the reliability and the stability of a power grid system are improved.

The invention belongs to the technical field of electric power and electronic engineering and specifically relates to a control system and a control method of a three-phase three-level VIENNA rectifier. The provided control system and control method of a three-phase three-level VIENNA rectifier is aimed at solving the problem that the input current of three-phase PFC converter will produce large third harmonic component under the traditional one-cycle control theory. To solve the above technical problem, the invention provides the control system and control method of a three-phase three-levelVIENNA rectifier; the system attenuates the second harmonic component contained in the output signal of the voltage regulator and does not affect signals in other frequency bands. The invention effectively suppresses the large amplitude three-phase harmonic component of the three-phase input current and improves the quality of the rectifier input current waveform.

The invention discloses a clamp five-level back-to-back converter with flying capacitor auxiliary bridge arms. The converter comprises a 5L-Vienna rectifier, neutral-point balancing auxiliary bridge arms, and a 5L-NPC inverter, wherein the 5L-Vienna rectifier is used as a variable speed controller of a permanent magnet synchronous generator, and higher voltage-withstand grade can be realized by adopting a five-level structure; the number of original parts is reduced, the problem of straight-through short circuit does not exist, the reliability is improved, the unity power factor variable speed control strategy can be realized, and the influences of harmonic waves are reduced since the current of the generator can be controlled to be sine waves; in addition, an auxiliary circuit formed by two three-level flying capacitor auxiliary bridge arms, which are connected in series, is provided for cooperating with modifying of the SVM strategy of the 5L-Vienna rectifier to realize neutral-point balancing, the auxiliary bridges can provide an unbalanced current flow path, and the problem of direct current unbalance is solved by using a voltage clamp principle of a flying capacitor.

The invention relates to output voltage dynamic response optimization control applicable to a Vienna rectifier, mainly comprising the steps of system electrical signal sampling, voltage error signal compensation, load jump judgment, load feed-forward compensation, current error compensation, and PWM drive signal generation. Through output voltage dynamic response optimization control, load feed-forward control is realized, and the dynamic response property of output voltage is optimized. According to the invention, the load current is sampled. When the fluctuation of load current is less than a preset fixed value, feed-forward compensation calculation is not performed, and the output voltage is regulated completely by a traditional voltage loop. When the load jumps, the traditional voltage loop is compensated through load jump judgment and feed-forward compensation calculation. Double-loop control in the traditional control strategy is maintained, and optimization of dynamic response of output voltage is realized effectively.

The invention provides a current predication control method based on a single-phase Vienna rectifier. The method comprises the following steps: firstly, deducing a circuit equation of the single-phase Vienna rectifier according to Kirchoff's laws and a single-phase Vienna rectifier topological structure; carrying out discrete treatment on the obtained circuit equation to obtain a single-phase Vienna rectifier discrete state equation; calculating a TS(K+2) moment current reference value by utilizing a two-ordered Lagrange's interpolation method and estimating a power grid voltage sampling value by utilizing a linear extrapolation forecasting method; predicating reference current and a periodic average error to obtain next-beat output current; finally, predicating three components to obtain next-beat predicated reference voltage UaN. By adopting the control method provided by the invention, errors caused by delaying control can be eliminated as much as possible, and influences, caused by the delaying control, on current control are improved, so that third-order harmonic and total harmonic distortion problems of power grid current are effectively solved.

A double closed loop control method of a Vienna rectifier comprises a three-phase Vienna main circuit, a voltage outer-loop sliding-mode control part and a power inner-loop sliding-mode control part. An algorithm is simple in control structure and low in computational burden. The introduction of a voltage square feedback system makes the system have a good dynamic voltage tracking effect. When the system is started and subjected to a load sudden change, the double closed loop sliding-mode control improves the system response speed and improves the anti-interference performance of the system. Further, the double closed loop sliding-mode control algorithm can meet the control performance requirement of the system: the grid side is a unit power factor, the input current is high in sinusoidal degree and low in harmonic content, the output DC voltage is stable and small in ripple.

The invention discloses a control method for predicting a virtual flux linkage by a Vienna rectifier model. The method comprises the steps of firstly, sampling voltages of upper and lower capacitors of a direct-current side, and obtaining given power P* after a direct-current voltage increment obtained by direct-current voltage negative feedback passes through a PI controller; obtaining a three-phase input current iabc and a switch state Sabc at a moment k, and obtaining a virtual flux linkage psi g of a voltage of a network side at current moment and a phase angle omega t of the voltage of the network side through a virtual flux linkage observer; calculating a given value psi*s of a virtual flux linkage of a line; then, online predicting a virtual flux linkage psi s (k +1) of the line atthe moment (k+1) by the prediction model; and finally, obtaining an optimal voltage vector control switch bridge through a minimization value function, and controlling the virtual flux linkage of theline to track the given value so as to obtain an expected control effect. According to the method, a voltage sensor of an alternating-current side of a rectifier is effectively eliminated, so that theanti-interference performance of the system to the voltage disturbance of the network side is greatly improved while the system cost is reduced.

The invention discloses a control circuit of a three-phase Vienna rectifier and a discontinuous pulse width modulation method thereof. The control circuit includes a grid voltage sampling circuit, aninductor current sampling circuit, a bus voltage sampling circuit, a switching transistor driving circuit and a DSP control unit. The DSP control unit includes a first abc / dq converter, a second abc / dq converter, a phase locker, dq / [alpha][beta] converter, a DPWM controller, a hysteresis controller, a bus voltage PI regulator, an active current PI regulator and a reactive current PI regulator. Thediscontinuous pulse width modulation method finds out a redundant clamping mode in a vector space that has an opposite effect on a neutral point potential, and adjusts, in combination with the offsetdirection of the neutral point potential, the neutral point potential balance by switching the clamping mode. The control circuit can effectively adjust the neutral point potential balance, and has low switching loss and high converter efficiency.

The invention discloses a method for optimizing zero crossing point distortion of input current of Vienna rectifiers. The method comprises the steps of: obtaining an AC voltage amount input by a network-side rectifier through sampling DC-side voltage and a state of a switch tube; carrying out sampling to obtain voltage input by a power grid and carrying out phase-locked loop calculation to obtaina voltage phase difference; carrying out transformation on the obtained AC voltage amount and the voltage phase difference to obtain values under a dq coordinate; sampling current input by a three-phase power grid, carrying out Clark transformation to obtain a current component under an alpha beta coordinate system, and carrying out modulo operation to obtain a module of a current vector; respectively filtering the AC voltage amount and the current vector module through LPF, and outputting an identified inductance value via a divider; substituting the identified inductance value into the calculation of a distortion angle so as to obtain three-phase compensation voltage, and optimizing distortion current. The method is capable of improving the precision of calculation distortion angles of current input by Vienna rectifiers, enabling the input current to be same as reference voltage, and improving the efficiency of the Vienna rectifiers.

The invention discloses a prediction control method of a no-network-voltage sensor of a three-phase VIENNA rectifier. The method comprises the following steps: S1, carrying out Clarke transformation on a mathematical model of the three-phase VIENNA rectifier in a three-phase static coordinate system, and establishing the mathematical model of the three-phase VIENNA rectifier in a two-phase staticcoordinate system; S2, estimating a voltage of a power grid by adopting a virtual flux linkage algorithm; S3, replacing an integral term in the step S2 with a second-order low-pass filter; and S4, determining predicted values of ialpha and ibeta at a k+1th moment according to a minimum power tracking error to obtain alternating-current side voltage vectors Valpha and Vbeta, and obtaining a space vector modulation signal. The method has advantages that an actual power grid voltage can be accurately and quickly tracked without a network voltage sensor and a phase-locked loop, same-phase operation of a power grid voltage and current is kept and so on.

The invention discloses a virtual flux linkage-based three-phase Vienna rectifier predictive direct power control method. According to the method, a mathematic model of a Vienna rectifier under a two-phase static coordinate system is firstly established, and a cross compensation flux linkage observer is adopted to estimate a voltage value of a power grid; a predictive direct power model is deducedaccording to a dead beat prediction basic principle, and a Lagrange linear interpolation method is imported to estimate given values of active power and reactive power at a k+2 moment; and finally, aspace vector modulation technology is utilized to control a switch device of the rectifier. According to the method, a rotational coordinate transformation technology and a phase-locked loop technology do not need to be synchronized, and independent control for the active power and reactive power of the rectifier is directly realized under the two-phase static coordinate system, so that a relatively good control effect can be achieved under the condition that the power grid is unbalanced and distorted and has a relatively large harmonic content.

A sliding mode proportion resonance control method based on a three-phase Vienna rectifier is disclosed. The method is characterized by according to a Kirchhoff law and the topological structure of the three-phase Vienna rectifier, deducing a three-phase rectifier circuit equation; collecting the voltages Uc1 and Uc2 of the upper and lower capacitors of a direct current side, alternating current side currents ia, ib and ic and voltages Ua, Ub and Uc, adding the collected voltages Uc1 and Uc2 of the upper and lower capacitors of the direct current side and acquiring a total voltage Udc, using the difference value of the Udc and a direct current side voltage reference value Udcref to acquire a current reference value idref through a sliding mode controller, introducing into a formula: iqref=0, through 2s / 2r conversion, acquiring i alpha and i beta, carrying out 3s / 2r conversion on the alternating current side currents so as to acquire actual current values i alpharef and i betaref, then,subtracting the i alpharef and the i alpha, and the i betaref and the i beta, through proportion resonance control, acquiring usalpha and usbeta, and through the voltages Ua, Ub and Uc, acquiring theangle theta of a phase-locked loop; and introducing the usalpha, usbeta, a direct current side voltage udc, the alternating current side currents ia, ib and ic, and a middle point voltage signal intoa controller, and finally acquiring a Vienna rectifier switch on-off signal. In the invention, the robustness and the dynamic performance of the Vienna rectifier are increased, the reaction speed ofthe Vienna rectifier is increased too, a direct current side voltage fluctuation is reduced, simultaneously a good anti-load-disturbance capability is possessed.