14 results about "Power factor control" patented technology

The invention discloses a control method and device applied to a totem pole PFC. The method comprises the steps of obtaining an alternating current input voltage and an instantaneous current in real time; dividing a normal working mode, a dead zone transition mode and a soft start mode according to a comparison result of the alternating current input voltage and a first preset voltage threshold value and a comparison result of the instantaneous current and a first preset current threshold value; and correspondingly adjusting the opening and closing of the high-frequency bridge arm and the power-frequency bridge arm according to a normal working mode, a dead-zone transition mode and a soft start mode. According to the invention, a traditional single control mode is replaced, an accurate and differentiated control strategy is provided for the zero-crossing region, and refined and programmed management of the zero-crossing process is realized.

The invention discloses a nonlinear control method and device for a permanent magnet synchronous motor-converter system, and belongs to the technical field of permanent magnet synchronous motor control, and the method comprises the steps: designing the control rate of d-axis and q-axis currents of a permanent magnet synchronous motor based on a unity power factor control target; completing the design of a parameter adaptive controller of the control rate of d-axis and q-axis current based on a unity power factor control target; obtaining an estimation function expression of the q-axis inductance of the permanent magnet synchronous motor changing along with the actual d-axis and q-axis current values of the permanent magnet synchronous motor; correcting the control rate of the d-axis current and the q-axis current of the unity power factor control target obtained in the step 2 according to the obtained inductance change rule; and closed-loop control of the permanent magnet synchronous motor is completed. The unity power factor operation effect that the output reactive power of the permanent magnet power generation system is zero is achieved, and the active power density of the permanent magnet power generation system is improved.

The invention discloses a power grid adaptive direction distance protection method and system based on an apparent power supply, and the method comprises the steps: building a home terminal dynamic equivalent apparent power supply model based on a voltage phasor and a current phasor obtained through measurement at a protection installation part, and enabling the model to be defined by two key parameters, namely, an apparent power supply voltage amplitude and equivalent impedance; three-phase voltage and three-phase current at a protection installation position are collected in real time, positive sequence voltage is calculated through a symmetrical component method, and the real-time phase difference between the dynamic equivalent apparent power source at the terminal and the three-phase voltage and the three-phase current is calculated; comparing the real-time phase difference with a preset action interval; when the real-time phase difference is in a set action interval, judging that a fault is a forward fault, and starting a protection action; and otherwise, a reverse fault is determined, and latching protection output is carried out. According to the method, the dependence of traditional protection on fixed source impedance parameters is effectively overcome, multiple control strategies such as unit power factor control, low voltage ride through and negative sequence current suppression of the wind turbine generator are adaptively compatible, and the interference of harmonic waves and power fluctuation on protection is remarkably suppressed.

Topology of an isolated rectifier power converter, and a power factor control method, which belong to the technical field of power electronics. The topology comprises a voltage source, a rectifier circuit, a power conversion unit and a drive control circuit. The power conversion unit comprises n power conversion circuits connected in parallel. Each power conversion circuit comprises a clamping transistor, a transformer, a primary-side switching transistor and a secondary-side switching transistor, wherein a clamping transistor of an ith power conversion circuit is an active clamping transistor, and clamping transistors of the remaining (n-1) power conversion circuits are passive clamping transistors. The drive control circuit is used for determining a target on-time and target duty cycle of each primary-side switching transistor within one switching cycle, and generating, on the basis of the target on-time and the target duty cycle, a drive control signal for controlling each primary-side switching transistor, wherein under the action of the drive control signal, the waveform of an input alternating current flowing through the voltage source is consistent with the waveform of an alternating voltage.

The invention relates to a large current generating device and current transformer verification equipment, and relates to the field of extra-high voltage power supply equipment, and the large current generating device comprises a three-phase rectification unit, an IGBT full-bridge conversion unit, an isolation conversion transformer, a rear-end capacitance compensation unit and a control feedback unit. The three-phase rectification unit can convert three-phase alternating current into direct current, the IGBT full-bridge conversion unit is connected with the three-phase rectification unit and can convert the direct current into single-phase alternating current, and the input end of the isolation conversion transformer is connected with the IGBT full-bridge conversion unit and can increase the current of the single-phase alternating current and output large-current alternating current. The rear-end capacitance compensation unit is connected to the output end of the isolation conversion transformer to improve the power factor of the large-current alternating current, and the control feedback unit is arranged between the output end of the isolation conversion transformer and the IGBT full-bridge conversion unit, so that the output current can be improved, and the weight and the cost of the device can be reduced.

The application provides a distributed power balancing and voltage regulating method for a current control type converter cluster. The method belongs to the field of micro-grid control, and is based on reactive voltage droop and voltage amplitude control to generate a reference current amplitude of the parallel converter, so that each parallel converter outputs the same current amplitude; meanwhile, the phase of the current vector is determined by four-quadrant power factor control, so as to ensure that the output currents among the parallel converters are in the same phase state, and the load side currents are effectively superimposed and the maximum load current is obtained. In view of the harmonic problem caused by the access of a nonlinear load, the application further adopts harmonic virtual impedance control at a fundamental frequency and selected harmonic frequencies, and combines with the multi-resonance controller adjustment of the current loop to effectively reduce the amplitude of the equivalent harmonic impedance of the DG unit, so that the harmonic circulating current among the DGs is minimized, and the power quality at the point of common coupling (PCC) is improved.

The invention discloses a single-stage AC-DC converter control method, system, device and equipment and a storage medium, and belongs to the field of electric energy conversion, and the method comprises the steps: simplifying a duty ratio expression according to a whole power factor control strategy, and obtaining a simplified conduction duty ratio; determining a Taylor expansion point according to the simplified conduction duty ratio to obtain theoretical conduction time; timing is started from the switch conduction moment of the current switching period until demagnetization is detected to be finished, counting is carried out, a predicted value of the next switching period is obtained, and a conduction time predicted value of the next switching period is determined based on the theoretical conduction time; and determining the conduction time correction based on output voltage closed-loop control, and superposing the conduction time predicted value of the next switching period and the conduction time correction to obtain the final switching conduction time so as to realize control of the single-stage AC / DC converter. According to the invention, the equivalent switching frequency can be improved, the power density of switching power supply products is improved, the device stress is reduced, and the model selection cost is reduced.

The invention relates to the technical field of metro power supply system operation modes, in particular to a sharing-based metro power supply system operation method, and provides a reactive compensation scheme of a metro power supply system under the background of resource sharing of a main substation. The minimum reactive power compensation amount before and after resource sharing of the main substation under the condition that the PCC full-day power factor reaches the standard is calculated, and a reactive power compensation scheme comprising various reactive power compensation devices is provided. According to the scheme, on the basis that the minimum reactive power compensation amount before and after main substation resource sharing meets the compensation requirement, the installation capacity of the SVG and the electric reactor or the capacitor is determined with the minimum SVG capacity as the target, and the investment cost of a power supply system is reduced.

The invention belongs to the technical field of current transformer load test, and particularly relates to a current transformer load test device based on a PI regulator and a control method thereof, and the device comprises a DC power supply module, a PWM inversion module, an LCL voltage stabilization filtering module and a PWM rectification feedback module. An energy closed-loop path is constructed through a PWM rectification feedback module, a three-phase full-control MOSFET bridge and a unit power factor control strategy (setting q-axis modulation voltage Vgq = 0) are adopted, and a PI regulator with a proportionality coefficient Kp1 = 1.0 and an integral coefficient Ki1 = 0.8 is matched to accurately regulate grid-side d-axis current igd, so that rectification-side current and voltage are in the same phase, and the synchronous rectification efficiency is greatly improved; meanwhile, feedback energy is buffered through a direct-current bus capacitor Cdc, impact of energy fluctuation on a direct-current bus is avoided, and finally electric energy originally dissipated in a load test is efficiently fed back to the direct-current power supply module.

The application provides a current-mode PWM rectifier and a passive control method thereof, comprising a filter unit, a rectifier unit and a load unit connected in sequence; an input end of the filter unit is connected with a three-phase AC source, an output end of the filter unit is connected with an input end of the rectifier unit, a first output end of the rectifier unit is connected with an input end of the load unit, and a second output end of the rectifier unit is connected with an output end of the load unit; the filter unit is used for filtering high-order harmonics of the three-phase AC source received by the current-mode PWM rectifier on an AC side; the rectifier unit is used for rectifying a filtered voltage to obtain a rectified voltage; and the load unit is used for converting the received rectified voltage to realize energy output. The application can realize independent decoupling control of active power and reactive power and unit power factor control, can also be used for reactive power compensation function, and has the advantages of few control parameters, convenient debugging and strong anti-interference capability.

The present disclosure provides an air conditioner for improving a power factor. The air conditioner comprises: an inverter used to drive a motor; a load including the inverter; a power conversion circuit including a rectifying circuit, which rectifies an input alternating current voltage so as to generate a direct current voltage, and a power factor correction circuit, which supplies an output direct current voltage to the load on the basis of the direct current voltage; and a processor for power factor control of the power conversion circuit. The air conditioner may comprise: a phase estimator for acquiring phase information of the input alternating current voltage; a voltage controller that generates, on the basis of the output direct current voltage and a reference voltage, a first control signal for controlling the magnitude of the output direct current voltage; a partial switching controller that generates setting information for setting a switching period of a switch included in the power factor correction circuit; and a current controller that generates, on the basis of an input current of the power factor correction circuit and a reference current, a second control signal for controlling the switch in the switching period. The reference current can be generated on the basis of the phase information, the first control signal and the setting information.

A power factor control apparatus includes: a phase detection unit configured to detect the phase of an output signal outputted from an inverter, which was originally used to supply electric power to a first electric power supply target, to a second electric power supply target that is different from the first electric power supply target and connected with the inverter and an inverter control apparatus for controlling the inverter; a correction amount calculation unit configured to calculate a phase correction amount based on a power factor command value that is a power factor required by the second electric power supply target; and a correction processing unit configured to generate, based on the phase detected by the phase detection unit and the phase correction amount calculated by the correction amount calculation unit, a power factor control signal for controlling the power factor of electric power supplied to the second electric power supply target and output the generated power factor control signal to the inverter control apparatus.

The utility model discloses an active and reactive power flow allocation system of a multi-source system, which comprises a data acquisition assembly, a plurality of power supply nodes, a plurality of load nodes and a plurality of power transmission lines in the multi-source system, wherein the data acquisition assembly is in circuit connection with the plurality of power supply nodes, the plurality of load nodes and the plurality of power transmission lines; the data acquisition module is used for acquiring real-time data of voltage amplitudes, voltage phases, active power and reactive power of corresponding nodes and lines; the central processing assembly is connected with the data acquisition assembly and receives real-time data; a control signal input end of the power adjusting assembly is connected with a control signal output port of the central processing assembly, is also electrically connected with the plurality of power supply nodes, and adjusts active power output and reactive power output of the plurality of power supplies based on a power control instruction of the central processing assembly; the reactive power compensation assemblies are arranged at the load nodes respectively, the control ends of the reactive power compensation assemblies are connected with the central processing assembly, and power factors of the load nodes are adjusted based on power factor control signals of the central processing assembly.

This electronic device may comprise a display panel, and a power circuit for generating, from an alternating current signal, a power signal to be supplied to the display panel. The power circuit may comprise: a capacitor; a power factor conversion circuit connected to one end of the capacitor so as to control charging of the capacitor on the basis of the power factor of the alternating current signal; a direct current-direct current conversion circuit for generating the power signal on the basis of power charged in the capacitor; and a switching circuit for connecting one end of the capacitor to any one of a resistor or a ground node according to the voltage of the other end of the capacitor.