98results about How to "Suppress inrush current" patented technology

The invention provides a method for starting a flexible HVDC (high-voltage direct-current) system of a modularized multi-level converter, which is utilized to control a switch, a breaker, a converter and the like, so that the submodule voltage and DC voltage are ensured to reach rated values; and control strategies are formulated properly to restrain impulse currents generated in a charging process. By using the method, a charging control method is simplified, a modulation algorithm is optimized, the problem that a far-end converter submodule is short of capacitor voltages when an alternating-current system at one end charges two stations is solved, and the problem of the charging of a DC line is solved as well.

The invention discloses a soft start method of an LLC resonant converter. The LLC resonant converter comprises a bridge-type switching circuit, a resonance circuit, a transformer, a rectifying circuit and a filtering circuit which are all connected in sequence, wherein the resonance circuit is composed of a resonant inductor and a resonant capacitor connected in series. According to the method, the initialized duty ratio of a driving signal is D0, and the initialized driving frequency is f0, wherein the value of the D0 ranges from 0 to 15 percent, the value of the f0 ranges from 1.5fr to 2.5fr, and the fr is the resonant frequency. The duty ratio of the driving signal and the driving frequency respectively increase and decrease linearly along with time or respectively increase and decrease exponentially along with time, so that while the duty ratio of the driving signal increases to 50 percent, the driving frequency decreases to the resonance frequency fr, and soft start of the LLC resonant converter is achieved. Through the method, impact current occurring in the start process of the resonant circuit can be restrained, the start time is short, a driving circuit is easy to obtain, and cost is low.

The invention discloses an AC-DC LED drive circuit with a high power factor, which comprises an AC input voltage circuit, a rectifying circuit, a switch converting circuit, a current sampling resistance circuit, an output adjusting switch pipe circuit, a power factor correcting controller circuit, a current control circuit I, a current control circuit II, and the like. The AC-DC LED drive circuitwith a high power factor is characterized by leading the AC-DC high-power factor correcting circuit to be capable of providing constant current and rapid current-limiting protection in a dynamic state (starting, input overvoltage, input mutation, LED load output overcurrent, LED load output short circuit, load mutation, and the like) needed by steady normal operation of an LED and can realize theinput soft starting and reduce the input impact current. The invention has the advantages that: 1. the problem of rapid control of output load current is solved when the high-power factor control is realized; 2. the overvoltage and short circuit protection of a boosting circuit can be realized; 3. the soft starting of a driver is convenient to realize, and the input impact current is inhibited.

The invention discloses a control method and device for an alternating-current solid-state power controller with a current limiting function. Through control over a first power tube and a second power tube of a main branch circuit and a third power tube and a fourth power tube of a current limiting branch circuit, when loads are normally started, natural zero-voltage turn-on and natural zero-current turnoff of the alternating-current solid-state power controller are achieved within a half of power source period, when large-capacity capacitive loads or rectifier bridge loads with large-capacity filtering capacitance are started, current-limiting charging is firstly performed through the current-limiting branch circuit, and then the alternating-current solid-state power controlled is completely turned on; when a short circuit fault happens on the alternating-current solid-state power controller, the main branch circuit is firstly turned off to perform fault current limiting, and then the alternating-current solid-state power controller is turned off. Natural zero-voltage on-off of the alternating-current SSPC is achieved within the half of the power source period, besides, the control method and device have a high-power current-limiting function, capacity for carrying the capacitive loads and the rectifier bridge loads of the alternating-current SSPC is improved, and anti-interference capacity of short circuit protection of the alternating-current SSPC is improved.

The invention discloses a direct-current pre-excitation starting method for the VVVF (Variable Voltage Variable Frequency) control of an asynchronous motor under flux linkage control, belonging to the technical field of the starting control of asynchronous motors. The direct-current pre-excitation starting method for the VVVF control of the asynchronous motor under the flux linkage control is characterized in that an included angle for synthesizing an excitation current vector and a starting voltage vector in a starting process is 90 degrees; a current is decomposed according to a known voltage vector direction for the VVVF control to obtain a reactive current feedback value; and the reactive current feedback value is converted into a voltage regulation value by gain amplification to control the flux linkage. In the invention, the direct-current pre-excitation and the starting process are controlled sequentially by using a DSP (Digital Signal Processor) chip. The method has an inhibition effect on the peak current subsequently appearing in the starting process.

The invention discloses a thick-film magnetic isolation direct current solid-state power controller which comprises a power MOSFET (metal oxide semiconductor field effect transistor), a detection resistor, a power diode, a TVS (transient voltage suppressor) diode, a current conditioning circuit, a voltage detection circuit, a voltage state judgment circuit, a current state judgment circuit, an immediate trip circuit, an inverse time circuit, a short-circuit detection circuit, a driving circuit, a state synthetic circuit, a trip state latch circuit, a time delay reset circuit, a time sequence matching circuit, a DC / DC (direct current / direct current) isolated power supply, a first isolation circuit, a second isolation circuit, a third isolation circuit, a state feedback interface circuit, a control signal interface circuit and a power-on reset circuit. The circuit structure can optimize the electrical properties of the controller, reduce the volume and the weight, improve the reliability and is widely applied to civil low-voltage direct current power distribution systems, aviation, aerospace, tanks, automobiles, ships and other fields.

The present invention discloses a method and a circuit for restraining surge current of a DC electrical source. The method includes the steps as follows: a secondary electric power supply is connected to a power supply, and charges an energy storage unit through a constant-current source circuit; a voltage detection circuit drives a time delay circuit when the voltage detection circuit detects that the voltage of an energy storage capacitor in the energy storage unit reaches to a preset voltage value; the time delay circuit drives a switch unit to be opened slowly until the switch unit is fully conducted; the switch unit bypasses the constant-current source circuit and charges the energy storage unit. According to the technical scheme of the present invention, the impact current can be restrained, and the voltage drop of a slow startup switch during starting can be reduced.

The invention discloses a starting method of a multi-branch two-stage three-phase photovoltaic grid-connected inverter and belongs to the technical filed of photovoltaic grid-connected inverter control. A converter connected with a starting power supply changes from ring opening to duty ratio slow starting, a constant-voltage tracking method is used to find the maximum power point, the maximum power point is tracked through a perturbation and observation method, and other convertors and the inverter starts slow starting when direct-current bus voltage is larger than starting voltage of the inverter. By the method, instant impact current of Boost converter starting and inverter grid connection can be restrained, dynamic features of maximum power point tracking during starting can be improved, stableness of the direct-current bus voltage can be guaranteed, and bus overvoltage or undervoltage can be prevented.

The invention discloses an excitation state analysis-based low-voltage ride-through control method of a virtual synchronous power generator. The method comprises the steps of improving designs of droop characteristic, a reactive power ring and an active power ring by means of a reactive power adjustment principle of the synchronous power generator and a power grid which are connected in parallel,and the problems of excessive large reactive power increment, difficulty in preventing impact current and loop coupling reinforcement are effectively dealt with; and on the basis of no change on characteristic of the state analysis-based low-voltage ride-through control method of virtual synchronous power generator (VSG) system, an additional current ring is designed again, the under-excitation state running of an auxiliary system can be assisted during power grid fault period, an output current is adjusted, and a reactive power support is given out. A new directional method is employed, the transient process is accelerated, a control algorithm is not needed to be switched during the power grid fault period, a smooth switching strategy among states is also not needed to be added, and the low-voltage ride-through problem and the asymmetric drop of the power grid can be simultaneously dealt with.

The invention discloses an electric car power-grid voltage compensation method based on a virtual synchronous generator algorithm, and the method comprises the following steps: 1), employing the virtual synchronous generator algorithm for an electric car grid-connected interface, and carrying out the droop control based on P-f and Q-V; 2), obtaining the output frequency w and phase angle theta of the grid-connected interface through simulating a mechanical equation of a synchronous generator; 3), employing a voltage and current double-closed-loop control strategy based on the dp coordinate system for an electrical equation part; 4), adding virtual impedance control at the electrical equation part, wherein the virtual impedance comprises constant virtual impedance and transient virtual resistance; obtaining virtual voltage drop, and taking a voltage instruction E obtained at step 1) as a voltage ring d-axis instruction ed, wherein eq is equal to zero; respectively calculating the differences between the ed and eq and the virtual voltage drops vvd and vvq, and obtaining a voltage ring output voltage instruction (shown in the description); 5), obtaining a dq-axis modulation signal of the grid-connected interface through the output of a current ring at step 3), and obtaining a switching control signal of a converter switching network through coordinate conversion and PWM, so as to drive a switching network.

The invention discloses a voltage short interruption noise immunity promoting circuit of a transducer and the transducer. The voltage short interruption noise immunity promoting circuit comprises the alternating-current power supply input end, a charging circuit, a rectifying circuit, a PFC circuit, an electrolytic capacitor, an inverter circuit, a supply voltage interruption time detection circuit and a controller. The supply voltage interruption time detection circuit detects short interruption time of alternating-current supply voltage input by the alternating-current power supply input end, and outputs the detection result to the controller. The controller outputs corresponding control signals according to the received detection result and controls the charging circuit to charge the electrolytic capacitor. The promoting circuit can effectively restrain impact currents generated when the supply voltage returns to normal again from voltage short interruption and charges the electrolytic capacitor in the circuit, the level of short interruption noise immunity of the transducer is increased, the reliability of the transducer is improved, and the promoting circuit further has the advantage of being low in cost.

The invention relates to a power switch circuit (2000), wherein when the power supply is connected, first connecting the MOSFET (Q1) with large conductive resistance; after preset time, connecting MOSFET (Q2) with lower conductive resistance; therefore, the invention can use simple structure to restrain the impact current when connecting the power supply. And the invention can be used in battery power supply.

The invention discloses an impact current eliminating circuit which is applied to a switching power supply; two stages of delay circuits are used for controlling the soft start of a power switch tube so as to suppress the impact current during a starting process, so that the current of a light-emitting diode (LED) is maintained at a minimum value, and the impact of the impact current on the load of the LED is eliminated; in addition, the minimum communication voltage drop of the circuit is greatly reduced compared with that in the prior art; and consequently, the power loss is smaller, and the overall output power of the circuit is improved.

The invention relates to a protection circuit for preventing an LED from an impact. The protection circuit comprises a discharging capacitance and an LED load. Besides, the protection circuit is characterized in that: the protection circuit also comprises a field effect transistor, a first resistor, a second resistor, a first triode, a third resistor, and a fourth resistor; a resistance value of the second resistor is greater than or equal to a ratio of a threshold voltage of the first triode to a maximum breakdown current of the LED load; a drain electrode of the field effect transistor is connected with an output power supply cathode of an LED driver; one path of a source electrode of the field effect transistor is connected with a direct current power supply cathode of the LED driver through the second resistance; and the other path of the source electrode of the field effect transistor is connected with a base electrode of the first triode through the fourth resistance; an emitter electrode of the first triode is connected with the output power supply cathode of the LED driver; and one path of a grid of the field effect transistor is connected with a collector electrode of the first triode through the first resistance and the other path of the grid of the field effect transistor is connected with a direct current voltage through the third resistance. According to the invention, a low voltage field effect transistor is employed to carry out current limitation, so that a response speed of a whole circuit is fast and circuit power consumption is low; besides, an impact current from an LED driving power supply on a back stage LED load can be effectively inhibited as well as service life of the LED load can be prolonged.

The invention provides an effective method for reducing impact current of inverters in grid connection so that the inverters can switch to the grid-connected operating state from the independent operating state easily and effectively. According to the mechanism, if the voltages on the two sides of a grid connection switch have the same amplitude and phase in grid connection, voltage difference does not exist, and thus impact current cannot be generated; in independent operation, inversion voltage becomes higher and higher, impact on filter capacitors is reduced, and in grid connection, the voltages on the two sides of the grid connection switch are consistent, and generation of impact current is suppressed; after grid connection, because double-loop control is adopted and only a given current loop is switched, sudden change of current can be effectively reduced, and smooth transition is achieved.

The power input stabilizing circuit provides a first resistor at the input terminals to suppress impulse current. Then, the power passes through a power input limiting circuit including a non-polarity capacitor, a rectifier circuit formed by diodes, and a polarity capacitor so as to provide a current within a specific range to a load. A constant current circuit including a third resistor, a diode, a fourth resistor, and a transistor is then employed to stabilize the load current. The performance and durability of the electrical or electronic appliance using the power input stabilizing circuit are therefore enhanced significantly.

The invention discloses a starting method suitable for a solid-state transformer. According to the starting method suitable for the solid-state transformer, a system is pre-charged through a low-voltage side; the energy needed in starting all comes from a low-voltage direct current source; after a starting condition is satisfied, grid-connection operation is performed; by adoption of the starting method for the solid-state transformer, introduction of soft starting matched equipment is not required; instead, control can be performed by fully depending on device characteristic of the system, so that stable and impact-free starting of the system can be realized; and meanwhile, an impact current to the equipment and a power grid in the starting process also can be suppressed.

A direct-drive power generation control method for a sensorless permanent magnet motor. A full-order observer pole is moved to the left relative to a motor pole to obtain a unified feedback gain matrix, a method of setting estimated rotation speed initial value is adopted to allow the unified feedback gain matrix to adapt to the running of a rotated permanent magnet motor restarted in a sensorlessand the permanent magnet power generation control in the full working conditions. The rotated permanent magnet motor is restarted in the sensorless, the switching of the permanent magnet in the powergeneration process is controlled, and a method of setting the q-axis current reference value of a bus voltage regulator is adopted to suppress the impact current in the switching process. The direct-drive power generation control method can be stably operated in the total speed range, the feedback gain matrix does not need online switching in the restarted rotated permanent magnet motor and permanent magnet motor power generation running, and the switching impact current is small between different work conditions in the full speed range.

An AC elevator comprises power line (1), an inverter (3) operated by the power line (1) to generate AC power, and an electric motor driven by the AC power from the inverter (3). A power supply includes a rechargeable battery (E), a power circuit (10) for charging and discharging the battery, and a control circuit (9) for controlling the operation of the power circuit (10) to control the input voltage to the inverter (3). The power regenerated by the electric motor charges the battery (E), which in turn drives the inverter (3).

The invention relates to a power distribution network single-phase earth fault arc extinguishing method based on a phase-locked loop, and the method comprises the following steps: decomposing a collected zero-sequence voltage signal into two paths of orthogonal signals after a single-phase earth fault happens to a power distribution network, and carrying out the amplitude and phase decoupling of the signals in a dq coordinate system; controlling the q-axis component to be zero to obtain a zero-sequence voltage amplitude; converting the instantaneous angular frequency into a phase angle to obtain a zero-sequence voltage phase angle; and calculating a reference arc extinction injection current by using the obtained amplitude and phase of the zero-sequence voltage, calculating an injection compensation current according to the reference arc extinction injection current, and controlling the converter to inject the injection compensation current into the neutral point of the power distribution network. According to the invention, the phase and amplitude information of the target voltage can be accurately and quickly tracked, the compensation current is accurately output, the extinguishing of the arc is effectively promoted, and the steady-state performance of the arc extinguishing system is improved.

The invention provides a relay control method and device of a grid connected inverter. According to the method, after that the inversion voltage of the grid connected inverter reaches a stabilized state, the relay is controlled to be closed, and timing is started. In the period that the timing length does not reach a time threshold, if the detected practical value of the inversion current is greater than or equivalent to the current threshold, the practical value of the inversion current is reduced to the preset current range. When the timing length is greater than or equivalent to the time threshold, it is considered that the relay completes a closing motion, and then the grid connected inverter is stopped from the present work mode, such as the inverter is directed stopped from operation, or directly switched from the present work mode to a normal grid connected work mode. The inversion current of the grid connected inverter is controlled directly and thus, not influenced by the voltage quality of the power grid, and the impact current is inhibited when the relay is closed under the condition that the voltage quality of the power grid is not high.

The invention provides a multi-VSG inverter circulation suppression and fault processing control method and system, and the method comprises the steps: carrying out the compensation of each VSG inverter through employing a pre-synchronization control compensation method for each VSG inverter which completes the setting of a power parameter when the grid-connected switching is carried out through an off-grid mode until the grid-connected requirements are met; during steady-state operation after grid connection, if an asymmetric fault of a load occurs, connecting the current type inverter and the VSG inverter in parallel after power parameter setting and connecting the current type inverter and the VSG inverter into a power grid, and compensating for the unbalanced current, wherein the powerparameter of each VSG inverter is set based on the rated capacity of each VSG inverter. The multi-VSG inverter control method provided by the invention not only effectively ensures that the multi-VSGinverter can realize power distribution through parameter setting, but also can ensure synchronization with a power grid in a pre-synchronization process, can effectively suppress grid-connected impact current, improves electric energy quality, and realizes seamless switching between operation modes. And the problem of circulating current among the multiple VSG inverters is eliminated.

The present invention provides a device for inhibiting impact current. The device comprises a thyristor dimmer, a rectifier circuit, a capacitive load, a first resistor, a switch tube, a control unit and a regulation unit. The control unit can switch off the switch tube when a thyristor is switched on, in the conduction phase angle after the switch-on of the thyristor dimmer, the switch tube is switched on such that the resistor is in short circuit, and the switch-on speed of the switch tube is reduced through the regulation unit. Thus according to the device, the impact current brought to capacitive load by the dimming of the thyristor dimmer and the secondary impact current brought to the capacitive load by the switch-on of the switch tube can be inhibited, and the loss of the first resistor can be reduced as much as possible while the impact current is inhibited.

The invention discloses a dual-mode smooth transition control method of a PWM rectifier. According to the method, a modulation ratio soft start controller is additionally arranged between a double-closed-loop controller of the PWM rectifier and a PWM pulse signal generating module; a modulation ratio is gradually reduced to a steady state value from large to small when the PWM rectifier is startedthrough the modulation ratio soft start controller, so that a starting impact current of the PWM rectifier is inhibited; the structure of the modulation ratio soft start controller is divided into three parts; a mathematical model of the modulation ratio soft start controller meets a condition that k=0 before controllable rectification starting of the PWM rectifier; in a range between a startingmoment t0 and a starting termination moment t1, the mathematical model of the modulation ratio soft start controller meets a condition that k=k2-k1t, and the mathematical model of the modulation ratiosoft start controller meets a condition that k=1 after modulation ratio soft start is terminated; and the modulation ratio soft start controller is started in a segmented mode, so that the impact current generated at the starting moment of the PWM rectifier is completely eliminated, and the purpose of smooth transition is achieved.

The invention discloses a bidirectional DC / DC converter and a control method thereof. The bidirectional DC / DC converter comprises a coupling inductor, six switching tubes, three capacitors and a resonant inductor, wherein the first end of the coupling inductor serves as a low-voltage side anode, the second end of the coupling inductor is connected with the first switching tube and the first capacitor, the third end of the coupling inductor is connected with the third switching tube, the fourth switching tube and the second capacitor, the first end of the first switching tube is connected withthe second switching tube and the third capacitor as a cathode, the second end of the first switching tube is connected with the first capacitor, the second end of the first capacitor is respectivelyconnected with the third switching tube and the second switching tube, the second end of the third switching tube is respectively connected with the fourth switching tube and the second capacitor, thesecond end of the second capacitor is respectively connected with the resonant inductor and the sixth switching tube, the second end of the fourth switching tube is respectively connected with the fifth switching tube and the third capacitor, the second end of the resonant inductor is connected with the fifth switching tube, and the second end of the sixth switching tube serves as a high-voltageside anode. The bidirectional DC / DC converter of the invention has the advantages of high voltage conversion ratio, small device voltage stress, small ripple current and the like.

The invention discloses a power balancing device for an offshore wind power flexible direct current sending-out system and a control method. The high-reliability power balancing device is formed by connecting three parts in series, namely a switch stage, a trigger stage, an energy consumption stage and a controllable reactor. The switch stage is formed by connecting at least one fully-controlled high-power power electronic device and a lightning arrester MOA1 in parallel. The trigger stage is formed by connecting a plurality of thyristors in series, and the number of the thyristors is determined according to the voltage of the MMC port. The thyristor level and the lightning arrester MOA2 are connected in parallel to form a trigger level. The energy consumption stage is composed of a resistor. The controllable reactor is composed of a controllable power supply and a saturation coil. According to the invention, the power surplus in the operation process can be effectively realized, the alternating current fault ride-through of the system can be realized, the overvoltage level of the direct current system can be reduced in the fault ride-through process, and the impact current of thedevice in the switching process can be reduced.

A switching module for a corner capacitor bank, comprising an improved corner capacitor bank, four controllable switches K1, K2, K3, K4, two small inductors L1, L2, two capacitor precharging circuits 10, 20, and Controllable switch drive circuit; the invention is connected to the A, B, and C phase lines of the three-phase distribution network line, and can realize asynchronous compensation between the phases of AB, BC, and AC. Multiple modules can be used together to avoid under-compensation or over-compensation of reactive power. Compensation occurs. The controllable switch adopted in the present invention can accurately control the switching time of each capacitor, avoiding the generation of surge current, and the small inductance connected in series with the controllable switch and the capacitor pre-charging circuit connected in parallel with the controllable switch suppress the capacitor input The impact current that may be caused by the power grid, these two points prolong the service life of the module and ensure the safe operation of the entire device.

The invention discloses a surge suppression circuit for a switching power supply, and belongs to the technical field of power supplies. The circuit comprises an overvoltage surge suppression module, an under-voltage surge suppression module, a first filtering voltage stabilization module and a second filtering voltage stabilization module. An external power supply input is output after passing through the overvoltage surge suppression module, the first filtering voltage stabilization module, the under-voltage surge suppression module and the second filtering voltage stabilization module in sequence. The surge suppression circuit has high reliability and low power consumption, has a wide surge voltage suppression range, can adapt to various severe over-voltage and under-voltage surge power utilization environments, and enables equipment to be more reliable.

The invention discloses a power supply circuit for suppressing a startup instantaneous impact current. The power supply circuit comprises an input protection module, a rectification filtering module,a starting module and an output module; the input protection module is connected with the rectification filtering module and the starting module. The output module is connected with the rectificationfiltering module and the starting module, wherein the rectification filtering module is connected with a first thermistor in series; two ends of the first thermistor are connected with a self-lockingcircuit in parallel, the self-locking circuit is connected with the starting module, and after the output module outputs normally, the starting module controls the self-locking circuit to be conducted, so the first thermistor is short-circuited. The arrangement of the first thermistor can suppress the starting-up instantaneous impact current; through the arrangement of the self-locking circuit, after the first thermistor is short-circuited, the loss caused by the existence of the first thermistor can be avoided, so the power supply efficiency is improved; meanwhile, the problem that the impactcurrent is increased during startup due to the fact that the resistance value of the first thermistor is decreased is avoided, and product damage is prevented.