156results about How to "Avoid inrush current" patented technology

The invention discloses a soft start device that can realize linear control, which comprises a working circuit, a soft start circuit and a start control circuit; the working circuit comprises a DC power source, a load capacitance, a power tube and a feedback circuit which are connected between the DC power source and the load capacitance and also a soft start circuit and a start control circuit, and the power tube is provided with a control end; the soft start circuit comprises a voltage generator, the output voltage of which is increased gradually after start, and an error amplifier, the input end of which is connected with the output end of the voltage generator; the input end of the error amplifier is connected between the output end of the power tube and the ground, while the output end of the error amplifier is connected to the control end of the power tube; when the start control circuit detects that the start begins, the soft start circuit is set to be in normal working state and a feedback circuit is set to be in off working state. The adoption of the device of the invention can avoid surge current at the moment when the power source charges the load capacitance at the instance when the circuit is electrified, can repeatedly use the existing error amplifier in the original circuit structure and save the areas and energy consumption of chips.

The present invention discloses a control apparatus for a linear compressor which can vary a cooling force and prevent an inrush current. The control apparatus for the linear compressor includes a coil winding body laminated on the linear compressor, a first capacitor connected in series to the coil winding body, a capacitance varying unit being formed in a parallel structure to the first capacitor, and having a capacitor switch, and a control unit for inducing an output change of the linear compressor, by varying the whole capacitance of the control apparatus by controlling the capacitor switch.

The invention discloses an intelligent universal light modulator which comprises a main supply interface, a load interface, a light modulation circuit, a current zero crossing point detection circuit, a voltage zero crossing point detection circuit and a controller. The light modulation circuit is sued for controlling breakover time and interval within each mains supply period through the controller so as to achieve regulation on a load device. The current zero crossing point detection circuit is used for acquiring and inputting a current zero crossing point signal on a mains supply live wire to the controller. The voltage zero crossing point detection circuit is used for acquiring and inputting a voltage zero crossing point signal into the controller. The controller is used for analyzing the current zero crossing point signal and the voltage zero crossing point signal and judging whether a device connected to the load interface is a capacitive device or a sensitive device, controlling the light modulation circuit in a leading edge phase-cut mode when the device connected to the load interface is the sensitive device and controlling the light modulation circuit in a lagging edge phase-cut mode when the device connected to the load interface is the capacitive device.

An image fixing device for use in an image forming apparatus. The fixing device includes a fixing member which fixes a toner image on a recording medium at a nip area, a pressurizing member which pressures the recording medium toward the fixing member at the nip area, a carbon lamp which emits infrared rays, and a reflecting member which reflects the infrared rays to the nip area.

Disclosed is an apparatus and method for driving a plasma display panel (PDP) where a switch device can perform zero voltage switching in driving the PDP. The apparatus for driving the PDP includes a sustain-discharge unit including first through fourth switches respectively connected to both ends of a panel capacitor between a power source and ground, for sustaining a panel capacitor terminal voltage to be at a first or a second sustain-discharge voltage; a first charge and discharge unit including a first inductor, for increasing the voltage of the panel capacitor to the first sustain-discharge voltage and switching a first switch in a state of a zero voltage by half of a resonance current generated by the first inductor; and a second charge and discharge unit including a second inductor, for decreasing the voltage of the panel capacitor to the second sustain-discharge voltage and switching a third switch in a state of the zero voltage by half of a resonance current generated by the second inductor.

The embodiment of the invention discloses a method for switching variable frequency into power frequency. The method comprises the following steps: obtaining the phase sequence, the phase position and the frequency of a power frequency signal output by a second high voltage bus; judging whether the phase sequence of a variable frequency signal output by a frequency changer is consistent with the phase sequence of the power frequency signal or not; if the phase sequence of the variable frequency signal output by the frequency changer is consistent with the phase sequence of the power frequency signal, obtaining current active current, calculating a current frequency descent rate generated by switching under a current state according to the current active current, reference active current and a reference frequency descent rate, calculating attenuation frequency and a compensation phase position in a switching time according to the current frequency descent rate and the switching time, regulating the frequency of the variable frequency signal to be the sum of the attenuation frequency and the frequency of the power frequency signal, and regulating the phase lag compensation phase position of a phase position relative power frequency signal of the variable frequency signal; and controlling a second contactor to be switched off and a third contactor to be closed. The embodiment of the invention also discloses a frequency changer and a power switching system. According to the embodiment of the invention, impulse current can be avoided when a variable frequency way is changed into the power frequency.

The invention discloses a control method adopted during passing through a third rail non-electric interval. The control method comprises the following steps that the working conditions of a vehicle are obtained; when the vehicle is under the traction or zero-position working condition, a nest step is executed; when the voltage reduction rate of a middle busbar of the vehicle is up to a preset reduction rate, disconnection of a high-speed circuit breaker is controlled; a traction invertor is controlled to disconnect a short-circuit contactor; when it is detected that the voltage of the middle busbar is recovered to reach a normal value, the high-speed circuit breaker is closed. The invention further discloses a control system used during passing through the third rail non-electric interval. In addition, the invention further discloses an electrical vehicle provided with the control system. By the adoption of the control method, the middle busbar of the vehicle is prevented from suffering from larger impact current, and it is effectively ensured that the vehicle smoothly pass through the third rail non-electric interval.

In order to securely prevent, even where a boosting unit is provided, a rush current from arising when a contactor is turned on during a transient state, the voltage of a surge absorbing condenser is controlled so that the voltage difference between the power source capacitor and surge absorbing condenser falls in a predetermined range. The control is performed in the following manner: of the twovoltage source inverters of the AC-coupled bi-directional DC-DC converter composing a voltage converter as a boosting unit, only the one that is not connected in parallel with a power source capacitor is activated to perform a chopping operation while the generator is operated with the contactor off.

The invention discloses a relay zero-cross detection method and device and a relay zero-cross calibration method and device. The relay zero-cross detection method comprises the following steps: when a relay is turned on, monitoring the voltage phase of a controlled end of the relay; obtaining the time interval of adjacent two times of zero-cross of the voltage phase; and sending the time interval to the zero-cross calibration side of the relay. The relay is detected by setting the independent zero-cross detection device, and is free of requirement for product circuit; and meanwhile, the relay does not need to be screened again, so that the research and development time of the product can be effectively reduced, and the production cost of the product is reduced.

The invention discloses a PFM constant-current control circuit applied in AC-DC converters, which mainly solves the problem that: since constant current in the prior art needs a photocoupler and a secondary loop control circuit, the application circuit is complex, and the cost is high. The PFM constant-current control circuit comprises a first voltage/current conversion circuit, a voltage sampling and retaining circuit, a second voltage/current conversion circuit, a first current subtraction circuit and a second current subtraction circuit. The voltage sampling and retaining circuit samples the change of output voltage by means of the feedback of a resistor voltage-dividing end of an auxiliary winding of a flyback converter, the voltage/current conversion circuits and the current subtraction circuits are utilized to convert the sampled voltage change of the resistor voltage-dividing end into current change, the current, the output magnitude of which is in direct proportion to the frequency of an oscillator, is used as the working current of the oscillator of an AC-DC converter, and when the load is changed, the magnitude of input power is regulated in order to realize constant current. The PFM constant-current control circuit can simplify application circuits and reduce the system cost, and can be used in the designs of constant-current constant-voltage AC-DC converters.

The invention belongs to the technical field of electronics, and relates to a soft start and soft shutoff circuit for Buck converters. According to the circuit of the invention, during system powering-on, an SS-end soft start capacitor CSS is charged by a current source to generate a slowly rising slope voltage VSS_OUT, VSS_OUT is compared with a feedback voltage VFB to make VFB rise slowly with VSS_OUT, so that the output voltage rises slowly, and surge current and output voltage overshoot are avoided. The beneficial effects are as follows: a soft start/soft shutoff circuit for Buck converters is provided, and in the soft start stage, slow rise of the output voltage is ensured, and surge current is prevented; and in the soft shutoff stage, the output voltage drops slowly to shut off a chip slowly.

The invention discloses an automobile electrical system pre-charging circuit and method. An electronic control unit controller controls a direct-current converter to monitor voltage information of a boost recuperation system and an electrical operation loop through a CAN bus, the electronic control unit controller controls voltage information of a lithium battery through the CAN bus and calculates the voltage difference, under the condition of a large voltage difference, the need of pre-charging is judged, an electronic control unit controls the direct-current converter to increase the output voltage of a storage battery to a target value to pre-charge the electrical operation loop, pre-charging is completed, and the electronic control unit controls the lithium battery to close a relay, so that the lithium battery supplies power for the electrical operation loop. After pre-charging, as the voltage of the two terminals of the lithium battery is approximate to the voltage of the two terminals of the electrical operation loop, larger impact current is not generated, the impact current is avoided, the reliability of the circuit is guaranteed, and the service life of electrical appliances is prolonged.

The invention provides a wireless electric energy transmission system and a wireless electric energy transmission method. Through setting a multi-stage start circuit, a surge current of a transmitting terminal power frequency rectification filter circuit in a powered-on state is inhibited; through step-by-step opening of a duty ratio carried out by a transmitting terminal MCU, a surge current of an LC resonance circuit on an inversion loop is inhibited; through controlling an opening time sequence of a back-stage BUCK voltage stabilizing circuit, influence of load switching on system start is inhibited. The method is advantaged in that problems of the surface currents of the transmitting terminal power frequency rectification filter circuit and the LC resonance inversion circuit in the powered-on state and system stability and reliability of load switching in a start process can be effectively solved.

A circuit for preventing impulse current in microwave oven, which contains microprocessor for outputting power driving signal and main driving signal, first transistor, first relay, voltage stabilizing diode, said invention can switch on/off relay in minimum current to prevent the impulse current without use of switch breaker etc component, so eliminating the noise due to the use of breaker and raising the system performance.

The invention relates to a power supply self-protection system and a method of a hybrid electric vehicle, wherein the power supply self-protection system comprises a vehicle controller, a low-voltagedistribution box and a high-voltage distribution box; The whole vehicle controller is electrically connected with the low-voltage distribution box to control the low-voltage equipment to power up or power down according to the set sequence; The whole vehicle controller is electrically connected with the energy controller, and the high-voltage equipment is controlled to be powered on or off by theenergy controller. The high-voltage equipment is powered on after the low-voltage equipment is powered on through the control; After the high-voltage equipment is powered down, the low-voltage equipment is powered down in the set order. The invention avoids generating relatively large impulse current to the low-voltage circuit in the power-down process and damages the low-voltage equipment throughthe power supply self-protection. It avoids the possibility that the relay of the high-voltage system may be broken off by charging, which may cause the relay to adhere and lead to the vehicle failure. And by precharging, the power supply current of the high-voltage equipment is increased step by step, the current impact of the high-voltage equipment is reduced, and the high-voltage electric equipment is protected.

The invention discloses a loop closing electricity switching detection and control system. The loop closing electricity switching detection and control system comprises a power grid parameter detection module, a switching value detection module, a processor, a communication interface and a loop closing control module. The loop closing time is calculated by the processor according to a preset calculation rule after power grid parameters are acquired by the power grid parameter detection module, when the communication interface receives a loop closing command, the best loop closing time is selected according to the switching value of a loop closing breaker acquired by the switching value detection module to output a loop closing signal, and a loop closing controller controls the loop closing breaker to perform loop closing operation after receiving the loop closing signal. Because the loop closing detection and control detection and control system does not directly perform loop closing operation according to the loop closing command but selects the best loop closing time according to the loop closing command, and thus a large impact current can be avoided, explosion of the breaker, loop protection override trip and other accidents cannot be caused, and power supply reliability of a power distribution network can be guaranteed.

The invention is a capacitance equipotential-switching thyristor triggering circuit, including high- voltage thyristor, control optical coupler and auxiliary power supply, and adopting trigger current control triode, amplifier triode, voltage zero-passage detecting triode and trigger current by-pass triode. Its main circuit voltage is rectified and then applied on two ends of the high-voltage thyristor, the auxiliary power supply is a DC power supply derived from rectification and filtration of an AC power supply and applied on to a resistance connected with the collector of trigger current control triode so as to generate a trigger current for the high-voltage thyristor, and the high-voltage thyristor is triggered as the two conditions that the control optical coupler is switched on and that the main circuit voltage passes zero. It realizes the function of triggering by zero passage of the main circuit voltage at high voltage, needs no connection waiting time, and realizes the equipotential capacitance switching, and avoids the impact current as the capacitance is connected to the electric network.

The invention relates to a smooth switching and flexible quitting method and device for a voltage sag treatment device. When an energy storage converter is switched from a grid-connected mode to an off-grid mode for operation, the energy storage converter is enabled to output a voltage the same as a load voltage before sag through a voltage control loop in a control strategy, the mains supply is cut off from a power grid in cooperation with a thyristor gate pole control signal, and smooth switching of power supply of the mains supply to the energy storage converter is completed; when the energy storage converter is switched from the off-grid mode to the grid-connected mode, through the voltage control loop and an automatic synchronization control loop in the control strategy, the voltage of the energy storage converter and the voltage of the power grid are synchronized, a thyristor is triggered to be switched on, the current of the energy storage converter is slowly controlled to be reduced to the current during grid connection, and conversion between the energy storage converter and the power grid line is completed; and when the active power and the reactive power output by the energy storage converter are respectively smaller than threshold values, the energy storage converter flexibly exits. According to the invention, high-quality electric energy supply for a sensitive loadbefore and after sag is realized, and an energy storage converter is prevented from providing large impact current for the sensitive load.

The invention relates to an inverter, an inversion device, an inversion system and a switching method. The inverter comprises a three-phase inversion module and a switching control module. The three-phase inversion module is used for converting direct current into three-phase alternating current. The switching control module switches the three-phase inversion module phase by phase, so that impact current generated in switching of the inverter is avoided effectively, and impact-free switching is achieved.