56results about How to "Eliminate inrush current" patented technology

An operation control method of a synchronization variable speed constant frequency wind generating set includes the strategies of AYC, synchronization control, low wind speed ceiling capacity follow control and high wind speed constant power control which includes the AYC, the synchronization control, the low wind speed ceiling capacity follow control and the high wind speed constant power control. An anemoscope and a wind vane measure the wind speed and wind direction information to generate a yaw deviation signal; a yaw motor is driven to execute left and right yaw according to the yaw direction and angle and limit the yaw velocity and meanwhile, the steering turns of the engine room are measured with the help of cables winding around a sensor, so as to execute safe untwist action, thus ensuring that the wind generating set realizes quick, accurate and safe effect of the wind wheel against wind. All the control strategies cooperate in work from the start to synchronization power generation according to the requirement of the set and external conditions, so as to ensure the safe and efficient operation of the wind generating set.

The invention discloses a one-frequency one-pump constant pressure water supply control system, which comprises a control unit (6) for controlling the operation of the system and controlling the output frequencies of frequency converters, a human-machine interface (7) for setting parameters of the system and monitoring operational data, the frequency converters (5a, 5b and 5c) for controlling the rotating speeds of water pump motors, and sensing instrument units (1, 3 and 4) connected with the control unit and used for acquiring external feedback information, wherein according to the control system, water pumps (2a, 2b and 2c) in a controlled pump group are matched with the frequency converters and controlled by adopting a common-frequency and common-speed control technology to implement constant pressure water supply.

The invention discloses a water supply equipment control system. The system comprises a plurality of water pumps, two frequency converters, a control unit, a switching group and a water pressure sensor; the control ends of the two frequency converters are connected to the control unit, and the output ends of the two frequency converters are connected to a node A; the input end of each water pump is connected with the switching group, and the switching group is respectively connected with the control unit and the node A; the control unit controls the operation of the switching group; the switching group controls conduction or cut-off of the input ends of the water pumps and the node A; and the water pressure sensor is connected with the control unit and used for detecting the water outlet pressure of a water using point. The invention also discloses a control method of the water supply equipment control system. The system has the advantages of realizing soft start and soft stop of the water pumps, eliminating the impact current when the water pumps are started, avoiding water hammer effect, stabilizing the water supply pressure, prolonging the service life and the reliability of the equipment and better ensuring the water using safety of a user.

The invention discloses a grid-connected startup method for a photovoltaic grid-connected inverter. The grid-connected startup method comprises the following steps of: a, keeping an off state of an alternating current switch; b, respectively detecting the bus voltage and power grid voltage through a direct current (DC) voltage sensor and an alternating current (AC) voltage sensor, and transmitting a detection result to a control circuit; c, judging whether the bus voltage is higher than the peak voltage of the power grid through the control circuit, and switching on the AC switch if the bus voltage is higher than the peak voltage of the power grid; d, calculating inverter modulation waves with the same frequency and phase as the power grid voltage through the control circuit according to the amplitude, phase and frequency of the detected power grid voltage; and e, judging whether the power grid voltage crosses the zero point through the control circuit, and if the power grid voltage crosses the zero point, applying the inverter modulation waves to the photovoltaic grid-connected inverter, starting the operation of the photovoltaic grid-connected inverter and starting the grid-connected operation. According to the method, the condition that high phase deviation occurs between the inverter voltage and power grid voltage can be effectively avoided, high impact current is avoided, and the stability of the system is guaranteed.

The invention discloses an oil electro-hydraulic and hydrostatic hybrid driving system. The functions of rapid starting, rapid braking, controlling minus grade to be at constant speed and energy-saving can be realized by adopting a concept of supplying oil for accelerated starting with a hydraulic assisted starting motor, a main hydraulic system and an energy storage system, and controlling the torque of a motor through a hydraulic energy accumulation system, and the overall installed power can be reduced while the climbing ability can be increased. By virtue of the assisted starting, the impulse current of the motor is mainly eliminated, not only can the rated power of electric elements be reduced, but also the working life of a storage battery and the mileage of the whole vehicle can be prolonged. By adopting the motor and a diesel engine as double power, the good starting acceleration performance can be realized, and good low-speed stepless regulation capability can also be achieved. The oil electro-hydraulic and hydrostatic hybrid driving system can be switched to a mechanical driving system in high-speed driving, so that the whole machine has higher driving efficiency. The diesel engine provides power for powerless batteryor high-speed driving on the ground, not only can the tail gas pollution in a tunnel be avoided, but also the intermittent driving of vehicles can be guaranteed.

The invention discloses a solar photovoltaic charge control device. A PWM signal drive component (6) comprises an RC low pass filter (61), a PWM chip (62) and a logic gate circuit (63) which are connected in series, and is used for providing drive signals of an auxiliary switch (31), a main switch (32) and a synchronous rectification switch (33) to a DC-DC conversion component (3) in time sequence according to PWM duty ratio signals of a microprocessor (5). The DC-DC conversion component (3) is composed of the main switch (32) with the two ends being connected with first resonance capacitors (C1) in parallel, the synchronous rectification switch (33) with the two ends being connected with second resonance capacitors (C2) in parallel, the auxiliary switch (31), a resonance inductor (Lr) and a filter inductor (Lf). The DC-DC conversion component (3) is used for sequentially enabling the synchronous rectification switch (33) to be turned off with zero current, the main switch (32) to be turned on with zero voltage and then turned off with quasi zero voltage according to set time of duty ratio, and the synchronous rectification switch (33) to be turned on with zero voltage and drop voltage of the synchronous rectification switch (33) at a steady state by not higher than 0.1 V. The solar photovoltaic charge control device can be widely applied to high-power photovoltaic electricity generation systems.

The invention provides a rectification and filtering device for suppressing power-on surge current. The rectification and filtering device comprises a first rectification circuit, a relay, a filtering capacitor and a zero-crossing conduction control circuit for detecting zero crossing points of an alternating current and controlling the relay. The relay comprises a coil and a contact point. A first end of the first rectification circuit is connected with one end of the contact point; the other end of the contact point is connected with one end of the filtering capacitor; the other end of the filtering capacitor and a second end of the first rectification circuit are grounded; the two ends of the coil are connected with the two ends of the zero-crossing conduction control circuit respectively; the other two ends of the zero-crossing conduction control circuit are connected with the two ends of the alternating current respectively; and the other two ends of the zero-crossing conduction control circuit are further connected with a third end and a fourth end of the first rectification circuit respectively. The invention also relates to a method by utilizing the device above. By applying the rectification and filtering device and method for suppressing the power-on surge current, the following beneficial effects can be achieved: the appearance of surge current can be completely eliminated, and hardware cost is reduced.

The invention discloses an impulse current inhibiting circuit and a supply circuit; when a constant current source is transformed into loaded state from unloaded state, a first control unit detects the output current of a main circuit of the constant current source and controls a first output switch to turn off and the main circuit of the constant current source to shutdown when the output current is no less than a predetermined current threshold value; a first discharge unit detects the predetermined parameter of the circuit and discharges an output capacitor when the predetermined parameter satisfies the discharge condition, namely the first discharge unit discharges the output capacitor when the impulse current exists in the supply circuit; the constant current source re-starts again at loaded state when the charge on the output capacitor is discharged to a certain degree, the voltage on the output capacitor slowly increases from a lower set value without occurring the impulse current. According to the technical scheme, the impulse current problem caused by the voltage instantaneous discharge on the output capacitor in the transformation process of the constant current source from unloaded state to loaded state is solved.

The invention provides a system for controlling the temperature of a continuous laser particle analyzer, which is used for temperature control of an avalanche photo diode (APD) fluorescent detection part in the continuous laser particle analyzer. The system comprises a heat insulation shell, a triethyl citrate (TEC) refrigerator, a thermistor and a control device. The TEC refrigerator is used for regulating the temperature of the APD; the thermistor is used for detecting the temperature of the ADP; and the control device is used for monitoring and controlling. The system meets the requirement of precise temperature control, can be used for heating and refrigerating, has short response time and is flexible and convenient to use.

The invention discloses a novel AC-DC-AC converter, which comprises a power frequency power supply, a rectification circuit, an inverter circuit and a resonance circuit. The AC-DC-AC converter is characterized by also comprising a fifth switch tube, inductors connected in series and a fifth diode, wherein the inverter circuit is provided with a sixth diode and a seventh diode. The invention also discloses a control method, which controls on and off states of each switch tube by changing an operating mode symbol xi and duty ratio d, wherein xi is equal to 0 or 1, when xi is equal to 0, Ton is conducting time of the fifth switch tube, and when xi is equal to 1, Ton is straight-through time of the same bridge arm in a bridge type inverter circuit and T is resonance cycle. The AC-DC-AC converter has the advantages that: a switch drive control circuit realizes the change of the operating mode and the adjustment of the duty ratio; the main circuit structure is simple, and DC filtering capacitance as well as impulse current in the process of starting circuits are eliminated; and the resonant current is controlled in constant amplitude when input voltage is changed in a large scale.

The invention relates to a starting control method and device of a flexible DC power transmission converter valve. The control method comprises the steps of putting a soft starting resistor, and charging sub-modules of a bridge arm; executing voltage-sharing sequencing operation on the sub-modules, removing a part of sub-modules in a bridge arm; and bypassing the soft starting resistor, and shutting all sub-modules which are not removed in the bridge arm and at least one sub-module which is removed so as to adjust a voltage of the bridge arm. By controlling the sub-modules which are removed involtage-sharing sequencing operation of an input part when the soft starting resistor is bypassed, a production condition that a phase step voltage is removed by the voltage of the bridge arm to damage an impact current can be adjusted, impact brought by bypassing the soft starting resistor is eliminated so as to prevent the impact current at an AC side, and the safety of a converter valve systemis ensured.

The invention discloses a power transformer capable of eliminating excitation surge, relates to the electrical field and is mainly used for eliminating an excitation surge phenomenon of a traditionaltransformer. The transformer comprises a transformer main body, wherein the transformer main body is integrated with a high-voltage winding and a low-voltage winding and is also integrated with an electronic converter and an auxiliary winding, the electronic converter comprises a converter A and a converter B, the converter A is used for achieving AC/DC conversion, the converter B is used for achieving DC/AC conversion, the converter A is electrically connected with the auxiliary winding, and the converter B is electrically connected with the low-voltage winding. According to a magnetism and demagnetism principle, the auxiliary winding is connected with the electronic converter to handle the excitation surge phenomenon of the transformer body; by magnetism and demagnetism operation on an iron core, the iron core stability of zero-distortion requirement of the transformer body is achieved, the links such as an external switch and residual magnetism measurement are omitted, and the magnetic field modulation is free from constraint of breaking and closing time.

The invention discloses a hierarchical voltage soft-start circuit for a three-phase voltage PWM rectifier and a control method thereof. The hierarchical voltage soft-start circuit comprises a seventh switch tube, an eighth switch tube, a first capacitor, a second capacitor, and a DSP (digital signal processor). A collector of the seventh switch tube is connected with the output end of an anode of a three-phase rectifier bridge and a collector of the eighth switch tube; an emitter of the seventh switch tube is connected with an anode of the first capacitor; an emitter of the eighth switch tube is connected with an anode of the second capacitor and one end of a load; a cathode of the second capacitor is connected with the output end of a cathode of the three-phase rectifier bridge, the other end of the load and a cathode of the first capacitor. The hierarchical voltage soft-start circuit has the advantages that soft starting is achieved by subjecting two ends of the first capacitor to hierarchical voltage charging and starting speed is high.

The invention discloses a double-power-supply switching device control method for inhibiting magnetizing inrush current of a load transformer. The control method is used for switching control of a double-power-supply switching device. The method comprises the following steps of (1) monitoring a power grid power supply, (2) judging whether the power grid power supply has a fault or not, (3) if the power grid power supply fails, stopping the driving signal of the frequently-used power supply switch, (4) detecting whether the frequently-used power switch is turned off or not, and (5) when the frequently-used power supply switch is turned off, turning on the standby power supply switch.

The invention provides a multi-port back-to-back suture-ring-free power conversion device and method, and belongs to the field of low-voltage power distribution network closed-loop power conversion, and the device is specifically characterized in that a series voltage compensator is connected with a parallel converter through a DC coupling capacitor; the two ends of the compensation side of the series voltage compensator are connected with a loop closing switch and a multi-port circuit breaker respectively; the other side of the loop closing switch is connected with the other multi-port circuit breaker; the number of ports of the multi-port circuit breaker is equal to that of the power supplies; the parallel voltage converter is used for maintaining the voltage of the common direct-current bus to be constant and performing harmonic compensation on load current; the alternating current side is connected to a load through an electricity-taking circuit breaker to take electricity; the series voltage compensator is used for providing compensation voltage and adjusting the amplitude and phase of the voltage at the output end of the loop closing switch; and the multi-port circuit breaker provides a plurality of transfer power supply lines for each power supply area. According to the invention, the cost is greatly reduced, the closed-loop power conversion device is simplified, the closed-loop impact current can be eliminated, and the power supply reliability is improved.