54 results about "Voltage source inverter" patented technology

The invention discloses an open-phase self-fault-tolerant control method for a phase-shift-free dual three-phase permanent magnet synchronous motor. The method can automatically adjust a current distribution relation in the case of an open-phase fault and suppress torque pulsation in combination with neutral point voltage compensation. Comprising the following steps: driving two pairs of three-phase winding modules of the phase-shift-free DTP-PMSM in parallel by adopting two two-level three-phase voltage source inverters, and providing a mathematical model of the motor; current distribution is automatically adjusted; compensating the voltage of the neutral point, and calculating the offset of the fault module; the current is redistributed to suppress the torque ripple after the fault, and the secondary oblique wave component generated by the phase failure fault is eliminated; a current loop controller is improved through dead-beat predictive control; the speed ring controller is optimally designed into an improved sliding mode controller; an improved double-loop controller system is formed by combining improved sliding mode control and dead-beat prediction control, high-gain parameters are set to improve the dynamic response performance of the system, and a new self-fault-tolerant control system is formed.

The invention relates to a harmonic suppression and dynamic voltage compensation method based on a composite control series filter, and belongs to the field of power electronic technology and electric energy quality control. Harmonic current passing through a primary winding of a transformer and a sudden rising or falling signal of power supply voltage are extracted, and after the two signals are controlled and combined into a reference signal, a voltage source inverter (VSI) connected with a secondary side of the transformer in parallel shows a controllable voltage characteristic. The control parameters of the harmonic current can enable the transformer to present relatively large controllable impedance to harmonic waves, so that harmonic wave isolation is realized. In addition, the VSI compensates for the system voltage deviation by detecting the voltage drop. And finally, establishing a simulation model to verify that the series active power filter based on the control strategy can isolate harmonic waves and effectively compensate voltage deviation. Harmonic suppression and dynamic voltage compensation functions can be realized at the same time, and the power quality of a middle-high voltage system is improved.

The invention provides an active support control method for a single-phase cascaded optical storage grid-connected system, aiming at challenges caused by fluctuation, intermittency and reverse peak regulation of photovoltaic resources in a photovoltaic energy consumption process and the problem of insufficient active support capability of a micro-grid for a large power grid under the access of high power electronic equipment. The low-voltage photovoltaic units are boosted by inverter cascading, and each photovoltaic unit is equipped with stored energy to stabilize photovoltaic fluctuation. A grid-side current source inverter is controlled by a virtual synchronous generator (VSG), so that the active support of the inverter on a large power grid frequency is ensured; other voltage source inverters adopt power factor angle droop control, and an active power compensation item is introduced, so that self-synchronization between the inverters and accurate power equalization between energy storage units are ensured. Compared with a traditional control method, the method can control active power and reactive power at the same time, has frequency supporting capacity, is low in communication cost, and provides a new solution thought for the problem of large-scale photovoltaic grid connection.

This invention discloses a dual-variable symmetrical injection modulation method for a two-phase permanent magnet synchronous motor, belonging to the field of motor drive and control technology. The method includes the following steps: S1, setting motor start-up logic and soft-start parameters; S2, generating two-phase orthogonal line voltage commands; S3, dual-variable symmetrical injection; S4, PWM comparator register mapping and output; S5, periodic execution. This method requires no modification to the hardware topology of a standard three-phase voltage source inverter or the addition of additional circuit components, and can be directly deployed on existing mature hardware platforms. This allows the same three-phase inverter to be used to drive both three-phase and two-phase motors, achieving hardware platform reuse and standardization, significantly reducing system development and bill of materials costs, resulting in low hardware cost and strong versatility.

The present invention relates to a control system (20) and method for controlling the flow of current between a voltage source (22) and a multiphase motor or other application / load for controlling a multiphase motor (28). The control system includes, between each phase of the multiphase motor and the voltage source: a high-side diode (30A-C) and a high-side switch (34A-C) positioned in parallel between a positive terminal of the voltage source and the motor, wherein the high-side diode is reverse biased with respect to the positive terminal; and a low-side diode (32A-C) and a low-side switch (36A-C) positioned in parallel between a negative terminal of the voltage source and the motor, wherein the low-side diode is reverse biased with respect to the motor. The control system operates the high-side and low-side switches to provide efficient operation of the motor.

The invention discloses a zero common-mode voltage pulse width modulation method suitable for a dual three-phase permanent magnet synchronous motor. According to the combination relation between the common-mode voltage and the power device switch of the two-level voltage source inverter, the pulse duty ratio of each phase of the voltage source inverter is calculated based on a carrier pulse width modulation method, and the pulse duty ratio of each phase is adjusted in order according to the relation between the sum of the pulse duty ratios and 3, so that the sum of the adjusted duty ratios is 3. Then, on this basis, odd-even symmetrical PWM pulses are connected end to end and arranged for phase shifting based on the volt-second balance principle, so that even harmonics of common-mode voltage and phase current are eliminated. The method can effectively eliminate the common-mode voltage during operation of the permanent magnet synchronous motor, maintains the original steady state and dynamic performance, and has a good application prospect.

The application discloses a three-level inverter harmonic suppression method based on zero vector symmetrical reconstruction and spread spectrum composite modulation, and the method comprises the following steps: step 1, signal acquisition and voltage instruction acquisition; step 2, spread spectrum modulation parameter setting; step 3, basic vector action time calculation; step 4, zero vector symmetrical reconstruction of vector sequence; step 5, switch time calculation and register updating; and step 6, PWM signal generation and system closed loop operation. The application realizes full-band suppression of inverter output PWM harmonics by deeply fusing the zero vector symmetrical reconstruction technology and the spread spectrum modulation technology. The application can be applied to a permanent magnet synchronous motor driving system powered by a three-level voltage source inverter, can simultaneously suppress the PWM harmonic amplitude near the odd carrier frequency and the even carrier frequency, effectively reduces electromagnetic vibration and noise, and has extremely high application value in the field of high-power inverters and motor drives.

The application discloses a three-phase voltage source inverter, which comprises: inverter A, B and C three-phase upper and lower working bridge arms V a1 、 b1 、 c1 、 a2 、 b2 、 c2 , corresponding anti-association diodes VD a1 、 b1 、 c1 、 a2 、 b2 、 c2 , upper and lower bridge arm shunt switch devices S1 and S2, three-phase selective switch devices T a1 、 b1 、 c1 、 a2 、 b2 、 c2 in additional dynamic shunt branches; when the inverter AC side three-phase current has a phase with a maximum positive current, the T a2 、 b2 、 c2 corresponding to the additional dynamic shunt branch are turned on, and the S1 of the additional dynamic shunt branch is shunted in parallel to the phase with the maximum positive current; when a phase with a maximum reverse current exists, the T a1 、 b1 、 c1 corresponding to the additional dynamic shunt branch are turned on, and the S1 of the additional dynamic shunt branch is shunted in parallel to the phase with the maximum reverse current. The application reduces the overcurrent of the inverter working bridge arm switch device caused by AC system disturbance, and improves the operation reliability of the inverter.

The invention provides a second-order model-free predictive control method for a voltage source inverter, relates to the technical field of power electronic converter control, and solves the problem that model predictive control depends on model parameters, system parameters do not need to be considered, and only input and output of a system need to be considered. And the influence of parameter mismatch on a control system is greatly reduced. Therefore, the system has good steady-state performance, robust performance and anti-disturbance performance. The provided control scheme is economical, reliable and easy to implement.

The invention discloses a virtual two-port-based inverter impedance remodeling and network power flow control method. The virtual two-port-based inverter impedance remodeling and network power flow control method comprises a voltage source type inverter impedance remodeling method and a voltage source type inverter network power flow control method. According to the voltage source inverter impedance remodeling method, system impedance modeling is firstly analyzed, virtual two-port network parameters are designed, then a control signal is calculated and input into an original system, and impedance remodeling is completed; the voltage source type inverter network power flow control method comprises the steps of collecting data, building a line model, calculating power flow control parameters, calculating control signals, inputting the control signals into an original system, and completing power flow control. The invention discloses a virtual two-port-based inverter impedance remodeling and network power flow control method, and aims to solve the problems that parameters of existing virtual impedance control exceed an actual engineering achievable range in a strong negative impedance scene and parameter setting is complicated and stability and robustness are insufficient in an asymmetric impedance scene. According to the technical scheme of impedance remodeling, the problem is effectively solved by processing symmetric and asymmetric systems in a differentiated mode.

A system includes a first motor, a second motor, and a third motor, each respective motor comprising three phases. The system further includes a voltage source inverter circuit comprising multiple respective inverter legs. Each respective inverter leg coupled to drive at least one phase of at least one of the respective motors, with a first shared inverter leg coupled to drive a third phase of the first motor and drive a first phase of the second motor. A second shared inverter leg is coupled to drive a third phase of the second motor and a first phase of the third motor.

The application discloses a kind of double three-phase permanent magnet synchronous motor adaptive model-free predictive control methods with optimal virtual voltage vector, S1, the mathematical model of double three-phase permanent magnet synchronous motor is established, and the discrete state space prediction model is constructed;S2, establish hyperlocal model ULM, and design extended state observer ESO;The control gain parameters of hyperlocal model and the observer bandwidth of ESO are updated recursively online, and adaptive model-free predictive control AMFPC is formed;S3, construct the virtual voltage vector set for inhibiting harmonic current;The current of motor future time is predicted using updated AMFPC, and the optimal virtual voltage vector is selected from the virtual voltage vector set;The optimized vector is generated through the center symmetrical pulse width modulation mode to generate switching signal, to drive six-phase voltage source inverter, to control double three-phase permanent magnet synchronous motor.The application provides a promising solution for high-performance double three-phase permanent magnet synchronous motor drive system under complex working conditions.

A method is provided for characterizing junction temperatures of power diodes devices, each of the diode devices being one-to-one connected in antiparallel to each power semiconductor switching devices of a voltage source inverter having processing and measuring capability, the method including: an initialization stage, wherein a heater is thermally coupled with a heatsink and / or with a direct bonded copper element of the voltage source inverter; a temperature setting stage, wherein the temperature of the direct bonded copper element and / or the heatsink is increased up to a maximum operative temperature; a commissioning stage, wherein at each current pulse of a current pulses train sampled data are collected in a sampling period wherein the corresponding power semiconductor switching device connected with at least one of the power semiconductor diode devices is turned-off; an output stage, wherein the processor generates, from the sampled data, processed data for at least one of the power semiconductor diode devices.

The application discloses a high-speed permanent magnet synchronous motor position identification method, samples motor a, b, c three-phase currents, carries out Clarke transformation on the obtained currents to obtain the currents of alpha axis and beta axis on a two-phase static coordinate system, estimates the output voltage of alpha axis and beta axis according to the SVPWM conduction time calculated in the last control period, obtains a position estimation reference quantity by directly processing the current voltage, and uses a phase-locked loop to calculate the angle and speed of the position estimation reference quantity and thereby calculates motor position information, the application uses the output characteristics of a voltage source inverter to obtain a calculation formula not influenced by discretization errors, and improves the position identification precision under a low load frequency ratio.

The invention relates to a self-adaptive prediction control method and system for an LCL type active power filter, and the method comprises the following steps: introducing a self-adaptive weight, dynamically fusing a power supply current frequency domain detection component and a load current time domain detection component, and fusing frequency domain high-precision detection and time domain quick response detection through the self-adaptive weight. The limitation of a single detection mode is overcome, and the compensation precision and the response speed can be improved respectively under the steady-state and transient-state working conditions; the reference current is predicted in advance according to the digital control delay step size, an inverter voltage instruction is calculated in a reverse recursive mode according to the reference current, the inverter voltage instruction is corrected to obtain a final instruction, and the final instruction drives a voltage source inverter to output compensation current; according to the compensation current tracking error and the load power change rate, the self-adaptive weight, the outer ring prediction step length and the self-adaptive virtual damping coefficient are dynamically adjusted, and the overall adaptability of the system to complex working conditions is enhanced.

A stability detection method and system for grid-connected and grid-connected converters based on impedance modeling is proposed. This method determines the impedance matrix of the voltage source inverter based on a small-signal model of the voltage source inverter, and establishes a first impedance ratio, a second impedance ratio, and a third impedance ratio with the equivalent impedance matrix of the power grid. If the first impedance ratio does not satisfy the Nyquist stability criterion, the converter is determined to be in a negatively damped state; if the first impedance ratio satisfies the Nyquist stability criterion, the converter is determined to be in a positively damped or underdamped state. The product of the second and third impedance ratios is used as the oscillation damping coefficient. If the oscillation damping coefficient is less than zero, the converter is determined to be in a negatively damped stable state; if the oscillation damping coefficient is greater than or equal to zero and less than the critical damping coefficient, the converter is determined to be in an underdamped stable state; if the oscillation damping coefficient is greater than or equal to the critical damping coefficient, the converter is determined to be in a positively damped stable state. This method accurately describes the dynamic characteristics of the converter under nonlinear and large disturbance conditions.

The invention discloses a grid-connected converter direct-current side midpoint potential balance structure, and the structure comprises a direct-current circuit structure which comprises a direct-current positive electrode, a midpoint potential and a direct-current negative electrode; the multi-winding transformer is provided with a primary side winding and a secondary side winding, and the primary side winding is electrically connected to the direct current circuit structure between the direct current positive electrode and the midpoint potential and the direct current circuit structure between the midpoint potential and the direct current negative electrode through a primary side H-bridge inversion module; and the voltage source type inverter is electrically connected to the secondary side winding, so that an energy interaction channel is formed between the voltage source type inverter and the multi-winding transformer, and when the unbalanced magnetomotive force is generated, the secondary side winding generates a compensation current for the neutral point potential through the energy interaction channel. The primary side of the multi-winding transformer is connected with two capacitors on the direct current side, the secondary side of the multi-winding transformer is connected with the voltage source type inverter, current compensation is carried out on the offset neutral-point potential, the neutral-point potential can be automatically corrected, the development difficulty and delay of a balance algorithm are eliminated, and the adjusting speed and the balance capacity are improved.

The invention relates to the technical field of inverter fault diagnosis. The invention provides a voltage source inverter single-tube open-circuit fault diagnosis method based on a second derivative. The method comprises the steps of calculating an absolute value of a second derivative of each phase in three-phase current output by an inverter when the inverter operates; comparing the calculated absolute value of the second derivative of each phase with a set threshold value, and judging whether the inverter has an open-circuit I-type fault or an open-circuit II-type fault; and when the judgment result is yes, judging whether the inverter has a single-tube open-circuit fault or not by utilizing the symbolic characteristics of the second derivative of each phase in the three-phase current output by the inverter, and positioning a fault power tube. According to the invention, two types of single-tube open-circuit faults can be diagnosed, and the diagnosis reliability is improved.

The application discloses a three-phase two-level voltage source inverter, which comprises: inverter A, B and C three-phase upper and lower working bridge arms V a1 、 b1 、 c1 、 a2 、 b2 、 c2 , corresponding anti-association diodes VD a1 、 b1 、 c1 、 a2 、 b2 、 c2 , upper and lower bridge arm shunt switch devices S1 and S2, three-phase selective switch devices T a1 、 b1 、 c1 、 a2 、 b2 、 c2 in an additional dynamic shunt branch; when the inverter AC side three-phase current has a phase with a maximum positive current, the T a1 、 b1 、 c1 corresponding to the additional dynamic shunt branch are turned on, and the S1 of the additional dynamic shunt branch is shunted in parallel to the phase with the maximum positive current; when a phase with a maximum reverse current exists, the T a2 、 b2 、 c2 corresponding to the additional dynamic shunt branch are turned on, and the S2 of the additional dynamic shunt branch is shunted in parallel to the phase with the maximum reverse current. The application reduces the overcurrent of the inverter working bridge arm switch device caused by AC system disturbance, and improves the operation reliability of the inverter.

The application belongs to the technical field of electric power automation, and discloses a voltage source inverter outer loop limiting method, device, equipment and medium; the method comprises the following steps: S1, obtaining three preset parameters; S2, calculating the d-axis current component i d and the q-axis current component i q of the VSC injected current i according to the three parameters; S3, judging whether the setting of the three parameters meets a preset condition according to the d-axis current component i d and the q-axis current component i q ; if yes, entering step S4, otherwise, modifying the three parameters and entering step S2; S4, calculating the boundary constraint of the voltage source inverter outer loop limiting according to the three parameters meeting the preset condition; S5, controlling the d-axis current component i d and the q-axis current component i q of the VSC injected current i to be within the boundary constraint. The application designs an improved VSC outer loop limiting strategy, which improves the stability of the VSC grid-connected system while modifying the limiting boundary as little as possible, so as to fully utilize the power electronic equipment and improve the transient stability of the VSC grid-connected system.

The application discloses a specified harmonic compensation method of a hybrid active filter, which simulates a virtual capacitor for a voltage source inverter in a harmonic domain, and the capacitor value can be adaptively adjusted by a perturbation and observation method, so that the LC filter and the virtual capacitor can generate series resonance at a specified harmonic frequency, and the effect of a multi-tuned filter is achieved, thereby greatly improving the filtering characteristic of the LC single-tuned filter; the control method has the advantages of simple control structure, easy implementation and good filtering effect.

The invention relates to the technical field of inverters, in particular to a three-phase voltage source inverter which comprises a direct-current voltage source module, an MOSFET control module 1, an MOSFET control module 2, a phase-shifted full-bridge ZVS direct-current conversion module, a three-phase Buck-Boost inversion module and a load based on the two-stage three-phase voltage source inverter. The phase-shifted full-bridge ZVS direct-current conversion module is adopted in the input stage part, fluctuation of output voltage of a photovoltaic panel is restrained, stable operation can be further achieved, meanwhile, a switching tube of the module can achieve the functions of zero-voltage switching-on and zero-voltage switching-off, and the phase-shifted full-bridge ZVS direct-current conversion module has wide application prospects in the field of photovoltaic new energy power generation-energy storage. Compared with the prior art, the high-frequency inverter circuit has the advantages that the switching tube loss of the MOSFET under the high-frequency working condition is reduced, and the Buck-Boost inverter circuit adopted by the high-frequency inverter circuit has a buck-boost function and a larger voltage output range, so that the high-frequency inverter circuit can flexibly adapt to the power supply requirement of a load end and has a wide prospect in the field of photovoltaic inversion.

The utility model relates to the technical field of inverters, in particular to a three-phase inverter with a wide voltage output range based on diode clamping. The inverter based on the three-phase voltage source comprises a direct-current voltage source module, a Y-Inverter inversion module, an MOSFET (Metal-Oxide-Semiconductor Field Effect Transistor) control module and a PMSM (Permanent Magnet Synchronous Motor) load module. The power supply has the characteristics of wide output voltage range and low harmonic wave, and is very wide in application prospect. Compared with a conventional inverter, the inverter provided by the utility model employs a Y-type inversion structure, obtains wide-range voltage output, has better performance in the field of electric automobiles, can be compatible with voltage levels of various nominal batteries, and meanwhile, compared with a two-level inverter, the inverter provided by the utility model is smoother in output waveform, and is more stable in performance. The output voltage is close to sine waves, peripheral circuit interference is small, and the device is safer, more efficient, more stable and quite wide in application prospect.

This invention belongs to the field of inverter technology, specifically relating to a nonlinear control method for a three-phase voltage source inverter, including detecting inductor current I. Labc Detect the output voltage V oabc ; By transforming from the abc coordinate system to the αβ coordinate system, we obtain I Lαβ V oαβ ; Set the outer voltage loop parameter K2 and the inner current loop parameter K1; obtain the filter inductor current reference value through the outer voltage loop, input the current reference value into the inner current loop control, and obtain the inverter modulation signal S in the αβ coordinate. invx(x＝α,β) The modulated signal is transformed into an abc coordinate system as S. invz(z＝a,b,c) The invention outputs PWM drive signals for the inverter's switching devices via carrier modulation to drive the inverter to output three-phase AC power. This invention effectively solves the chattering problem caused by the sliding phase term in the current inner loop control, introduces a nonlinear control term, enhances the system's robustness, and enables the inverter to compensate for both low-order and high-order harmonic voltages.

A single-phase voltage source inverter and method including a main inverter circuit connected to an active power filter circuit, the main inverter circuit comprising an H-bridge circuit comprising a first leg and a second leg, the first leg comprising a first switch, a second switch, and the second leg comprising a third switch and a fourth switch, the active power filter circuit comprising a third leg comprising a fifth switch and a sixth switch, the main inverter circuit connected to a secondary side of a high frequency transformer and a grid filter in series, and adapted to be connected to an AC load, a primary of the high frequency transformer and a capacitor connected in series to the active power filter leg and an H-bridge leg.

The present invention relates to the field of electric power technology, and specifically discloses a method for analyzing the influence of reactive power droop control on the large-disturbance stability of VSG. The method is based on a basic control structure of a typical amplitude-phase controlled VSG scheme based on a second-order SG model implemented in a dq coordinate system. The control structure includes a distributed power supply, a three-phase voltage source inverter, a filter inductor, an AC bus, a power control loop, a virtual impedance control loop, a current control loop, and a PWM module. The method also provides an impedance large-disturbance stability boundary under a balance point condition during a voltage drop period when reactive power droop is considered, thereby broadening the impedance large-disturbance stability boundary of the system. Reactive power droop control helps to improve the large-disturbance stability of the system.

The application discloses a direct torque control method and system considering DC bus voltage imbalance, and relates to the field of motor control. The method comprises the following steps: determining the distribution law of voltage vectors in the fundamental wave alpha-beta subplane and the harmonic x-y subplane when the DC bus voltage is unbalanced; determining three groups of virtual vector groups according to the distribution law and a set condition; the set condition is that the distribution of three basic voltage vectors in the harmonic x-y subplane is greater than 180 degrees, and the three basic voltage vectors are composed of two large vectors and one medium vector in the fundamental wave alpha-beta subplane; obtaining the optimal virtual vector based on the three groups of virtual vector groups according to the DC bus voltage ratio, the sector K value, the system torque and the flux demand; sorting the switches in two two-level three-phase voltage source inverters according to the action time of the three basic vectors in a control period, obtaining the optimized switch sorting, and then controlling the voltage source inverters. The application can efficiently operate under the DC bus voltage imbalance.

The invention provides a hybrid cascaded energy storage converter control method and system. A nearest level approximation modulation strategy is adopted to enable a cascaded H-bridge converter to operate in a fundamental frequency switching mode, and PWM is adopted to enable a high-frequency two-level voltage source inverter to operate in a high-frequency switching mode to eliminate harmonic components brought by CHB. According to the hybrid modulation scheme, high-frequency and low-frequency switching frequencies are separated, and high-voltage large-scale energy storage and switching loss reduction are both considered. A hierarchical control strategy is adopted, and switching loss reduction, active power control, reactive power compensation and in-phase / inter-phase battery charge state equalization are realized at the same time, so that the hybrid cascade energy storage converter realizes SOC equalization of each battery in the hybrid cascade energy storage converter during high-voltage energy storage and reactive compensation, and safe and stable operation of the system is guaranteed.

The application provides a single-sensor phase current reconstruction three-phase voltage source inverter fault diagnosis method, solves the feasibility and diagnosis time of open-circuit fault diagnosis of the single-current sensor three-phase voltage source inverter, and comprises the following steps: firstly, analyzing the existing mechanism of the direct-current bus single-sensor current unobservable area, and the voltage vector synthesis mechanism under four types of faults, i.e. single-tube open circuit, different-phase same-side double-tube open circuit, different-phase different-side double-tube open circuit and same-phase double-tube open circuit; then, replacing the zero vector with two complementary effective voltage vectors, realizing reliable reconstruction of the fault phase current in the current unobservable area; finally, the inverter fault diagnosis method composed of three diagnosis criteria, i.e. the current vector phase angle, the average current vector modulus and the phase angle, realizes the fault diagnosis of the three-phase voltage source inverter under the single-current sensor. The application realizes the open-circuit fault diagnosis under the single-sensor phase current reconstruction, and the method can effectively and quickly locate the fault power tube.

The disclosure is directed to an island network detection method using a voltage-impressing converter, and includes determining the frequency and phase of a voltage curve of a sub-network connected to a network connection point of the converter, and generating a voltage curve using a bridge circuit of the converter with the determined frequency. The method also includes determining a correlation between a first temporal variation and a second temporal variation of an output exchanged by the converter with the sub-network, and detecting an island network if the determined correlation undershoots a specified correlation measurement.