30results about How to "Limit inrush current" patented technology

The invention relates to a power converter, which is composed of three bridge arms connected in parallel and then connected in parallel with a working capacitor; and between the midpoints of the first bridge arm and the second bridge arm, there is a commercial power input and an inductance connected in series, and the second bridge arm The primary side of the transformer is connected in series between the midpoint of the arm and the third bridge arm, and the negative side of the transformer is connected to the DC output circuit; the control terminals of the first bridge arm, the second bridge arm, and the third bridge arm are all connected to the control circuit The control signal is connected; wherein the control circuit selectively controls the conduction of the switch tube corresponding to the first bridge arm and the second bridge arm according to the detection result of the zero-crossing voltage input by the mains to perform power factor correction. The control circuit also detects the load The operating state parameters selectively control the conduction of the switch tube of the third bridge arm to output energy to the secondary side of the transformer so that the DC output circuit outputs DC; the present invention combines AC anti-surge, rectification and filtering, PFC conversion, DC / The DC is designed together, and only six switching tubes are used to complete the power conversion.

The invention provides a high-voltage battery discharge circuit and control method thereof, and belongs to the technical field of high-voltage battery solving the problem of poor safety in the prior art. The control method for the discharge circuit of the high-voltage battery comprises the following steps of: detecting whether the two ends of the capacitive load C1 are showed voltage, if so, recording the fault state as error I and alarming; if no voltage is showed, the pre-charging contactor K1 and the pre-charging contactor K4 are controlled to be closed simultaneously, detecting the voltageon the two ends of the capacitive load C1 in the suction process and recording the pre-charging time, and calculating the real-time rising rate of voltage on the two ends of the capacitive load C1 inthe unit time; if the rising rate is not within a preset range value, recording the fault state as an error II and alarming; If the rising rate is within a preset range value, the negative contactorK3 and the positive contactor K2 are controlled to be closed, the pre-charging contactor K1 and the pre-charging contactor K4 are disconnected, and the high-voltage battery discharging circuit entersa safe working mode. The high-voltage battery discharge circuit can improve the safety of the high-voltage battery.

A power-on surge current suppression circuit applied to a switching power supply is disclosed. The power-on surge current suppression circuit comprises an optional small-capacity filter capacitor C, an N-channel MOS tube Q, a current suppression resistor R, an outage leakage circuit, a rectifying filtering amplitude-limiting circuit and a power supply winding; the two ends of the current suppression resistor R are connected with the drain electrode and the source electrode of the N-channel MOS tube Q; the outage leakage circuit is connected between the grid electrode and the source electrode of the N-channel MOS tube Q; the rectifying filtering amplitude-limiting circuit and the power supply winding are serially connected and then connected between the grid electrode and the source electrode of the N-channel MOS tube Q; the drain electrode and the source electrode of the N-channel MOS tube Q are serially connected between a power frequency rectifier and a DC-DC converter; and the optional small-capacity filter capacitor C is connected between the positive end and the negative end of the power frequency rectifier. The surge current in the power-on moment is limited by the power-on surge current suppression circuit; the MOS tube is low in power consumption and high in starting speed; and the power-on surge current suppression circuit is short in time for allowing re-power-on.

The invention relates to a residual voltage estimate based seamless switching power supply method for a motor. A system adopted in the method comprises a working power supply and a standby power supply which are connected with the motor respectively, wherein a rectifier is connected between outputs of the working power supply and the standby power supply and is further connected with the motor through an inverter. The method comprises steps as follows: S1, modeling of residual voltage of an induction motor after power loss; S2, prediction of residual voltage of a bus of the motor; S3, predication of the initial value of the residual voltage of the bus of the induction motor after power loss: when the initial value of the residual voltage of the bus is smaller than rated voltage of the bus, a UPS (uninterrupted power supply) inverter is started and stabilized in a work state for supplying power to the induction motor; and S4, the phase of the residual voltage of the bus is compared with the phase of voltage of the standby power supply, and the standby power supply is put into use when the phase difference is smaller than 20 degrees. By means of the method, power can be supplied to an important load during power loss of electric supply, output voltage can be also initiatively adjusted, the standby power supply can be rapidly switched and put into use, impact to the load is avoided, and the instant impact current when the standby power supply is put into use can be effectively limited.

The invention belongs to the technical field of power semiconductor devices, and particularly relates to a semiconductor device with conduction voltage drop self-clamping and a preparation method thereof. Compared with a traditional fast recovery diode structure, the Zener diode structure capable of achieving self-clamping voltage drop is integrated, the first N-type polycrystalline silicon and the first P-type polycrystalline silicon are longitudinally and alternately arranged on the upper portion in the groove, the second N-type polycrystalline silicon and the second P-type polycrystalline silicon are transversely and alternately arranged on the lower portion in the groove, the device is integrated with the Zener diode in reverse parallel connection, and therefore the device can achieve self-clamping voltage drop. When large surge current is generated, the Zener breakdown characteristic can be used for clamping conduction voltage drop, so that the device is prevented from being damaged; by arranging the inverted T-shaped groove between the body region and the P-type heavily doped region, the P-type heavily doped region with relatively shallow junction depth can be shielded in a dynamic reverse recovery process, so that the P-type heavily doped region is effectively protected, and a reverse bias safe working area (RBSOA) of the device is increased.

The invention discloses a solution method for controlling overlarge magnetizing inrush current of a flexible direct-current connection transformer.A connection transformer is included, a phase selection closing device is arranged on a control loop of an incoming circuit breaker of the connection transformer, the phase selection closing device comprises A, B and C phases, when the connection transformer is in no-load closing, an MMC is connected, and when the first closing phase is the B phase, the closing fixed values alpha b of the A phase, the B phase and the C phase are equal to 90 DEG, the alpha c is equal to 120 DEG (240 DEG of the B phase), and the alpha a is equal to 90 DEG (330 DEG of the B phase); and when the connection transformer is not connected with the MMC during no-load closing and the first closing phase is the phase B, the closing fixed values of the phase A, the phase B and the phase C are alpha b = 90 DEG, alpha c = 90 DEG and alpha a = -90 DEG. According to the invention, the charging sequence operation sequence of the flexible valve group is changed, and the optimal closing angle of each phase is 90 DEG of each phase voltage. When the overlarge closing deviation of the circuit breaker is large, relatively large magnetizing inrush current cannot be caused.

The present invention relates to a novel busbar residual voltage maintaining device, which includes a bus protection reactor L, an explosive bridge body FSR, a first high-speed eddy current switch K0, a current-limiting damper RL and a second high-speed eddy-current switch K1, the current-limiting damper RL is connected in series with the mother protection reactor L and then connected in parallel with the explosive bridge body FSR, the first high-speed eddy current switch K0 is connected in parallel at both ends of the explosive bridge body FSR, and the incoming line end of the explosive bridge body FSR passes through the second high-speed eddy current switch K1 is connected to the incoming line end of the device, and the outgoing line termination of the explosive bridge body FSR is connected to the outgoing line end of the device. The present invention has the advantages of simple structure, safety and reliability, fast action, saving transformer investment and operation loss, etc., and can put into the mother protection reactor within 2ms, which is far faster than the 15ms switching speed of the mother protection reactor controlled by the circuit breaker in the current market; It can remove and isolate the short-circuit fault in time, prevent the further expansion of the short-circuit fault range, and effectively ensure that the busbar does not lose voltage when the feeder branch short-circuit fault occurs.

A dynamic damper (240) in a lighting driving circuit (200) for limiting an inrush current includes a damper circuit (242) and a timing circuit (241) comprising capacitor (1). The damper circuit is connected to the timing circuit. When an input voltage is provided to the dynamic damper, the capacitor begins to be charged and the capacitance-voltage of the capacitor rises. The damper circuit enters to a first working state and generates a dynamic damper resistor value. When the capacitance-voltage of the capacitor is greater than a first threshold voltage, the damper circuit enters to a second working state and the dynamic damper resistor value begins to decrease. When the capacitance-voltage of the capacitor is greater than a second threshold voltage, the damper circuit enters to a short-circuit state, and the dynamic damper resistor value decreases to zero to facilitate the normal work of the power source converter.

The invention discloses a soft start control device for a high-power motor. The soft start control device comprises a motor, an alternating current power supply, a rectifying circuit, a bidirectional thyristor, a unijunction transistor, a transformer, a sliding rheostat, a voltage-regulator tube, a fifth diode, a first resistor, a second resistor, a third resistor, a fourth resistor, a fifth resistor, a first capacitor and a second capacitor. According to the soft start control device, after the rectifying circuit performs rectification, current limitation is performed through the first resistor and after voltage stabilization, the large-capacity capacitors are charged; gradually-increasing (from small to large)of a turn-on angle of the bidirectional thyristor due to trigger pulses can be delayed through the discharge quantity of the sliding rheostat to the unijunction transistor; and even if the resistance value of the sliding rheostat is adjusted to a minimum value, the bidirectional thyristor cannot be connected fully immediately, thereby achieving the purpose of soft start. The speed of the soft start of the motor can be changed through adjusting the sliding rheostat. Through adopting soft start, a surge current of a cold motor can be limited, the motor can be prevented from being burned out, the service life of the motor can be prolonged and inconvenience caused by motor burning in work is reduced.

The invention provides a device interface protection circuit. The circuit comprises a first inductance module connected between the VBUS port of a device interface and the positive pole of a power supply, a second inductance module connected between the GND port of the device interface and the power supply ground, a gas discharge module connected between the VBUS port, the GND port and the protective ground, a gas discharge initiating module connected between the signal line port of the device interface, the positive pole of the power supply and the power supply ground to initiate the gas discharge module, and a bleed module arranged between the protective ground and the power supply ground. According to the device interface protection circuit provided by the invention, by constructing a common mode protection path and a differential mode protection path, the common mode and differential mode protection of the device interface can be smoothly realized; the problems of surge and electrostatic protection are solved; and the circuit has the advantages of high protection level, low clamp voltage and good reliability.

The invention discloses an asymmetric fault ride-through system and method for a three-phase four-wire system virtual synchronous generator, and the method comprises the steps: obtaining the voltage of a common coupling point of a power grid through an acquisition module when an asymmetric fault happens to the power grid, and enabling a fault type detection module to detect whether a correspondingphase breaks down or not according to the voltage of the common coupling point; and meanwhile, the internal potential selection module calculates a virtual impedance value according to the fault type, so that the virtual impedance module adds virtual impedance to the fault phase according to the virtual impedance value to limit the current of the fault phase, and the virtual impedance is removeduntil the fault phase returns to normal. And if the phase has no fault, an inertia link and a damping link are added through the virtual synchronous control module, so that the phase is kept stable. The technical problems that an existing three-phase three-wire system VSG technology has high requirements for a controller in engineering practice and is difficult to achieve in a high-power system are solved.

The embodiment of the invention discloses a slow start circuit and an LED power supply device, the LED power supply device is connected with an LED lamp string, and the LED power supply device comprises a power supply input circuit, a power supply control circuit and the slow start circuit; the power supply input circuit rectifies and filters commercial power and then outputs a first power supply voltage and a second power supply voltage; the slow start circuit performs internal power supply after stabilizing the first power supply voltage, and outputs a pulse width modulation signal to the power supply control circuit after delaying a preset time when detecting that the internal power exists; and the power supply control circuit converts the second power supply voltage into power supply voltage according to the pulse width modulation signal to supply power to the LED lamp string, and controls the LED lamp string to gradually brighten. Power supply to the LED lamp string is delayed through the slow start circuit, and the impact current when the LED lamp string is just powered on is limited; and the LED lamp string is gradually brightened, so that eyes can gradually adapt to the LED lamp string, and the lighting effect is milder. Therefore, the problem that an existing LED power supply module cannot be started slowly at fixed time to light an LED lamp is solved.

The invention discloses a current detection type current surge suppression circuit based on feedback and feedforward. The current surge suppression circuit comprises an energy storage capacitor, a feedforward acceleration circuit and a current detection type impedance control feedback circuit. Load current is decoupled through series connection of the current-limiting impedance and the charging capacitor, and heat consumption of the current-limiting impedance circuit is reduced; negative feedback regulation is realized through current detection, and surge current is limited; a feed-forward branch is introduced, so that the abnormal driving voltage of a switching tube in a power-on transient can be suppressed, the reliability of the circuit is improved, and surge current generated during secondary jump of the voltage after starting can also be suppressed; the combined use of the linear MOS tube and the switch MOS tube can reduce the impact current when the starting is completed, and the circuit can be realized only by using a discrete analog device and is simple.

The invention discloses a vehicle-mounted DC / DC converter input output protection circuit, which comprises an input output switch arranged at the input end and / or output end of the vehicle-mounted DC / DC converter, a fuse and a first capacitor respectively connected with the input output switch, a power supply battery connected with the fuse, and a soft start circuit respectively connected with the first capacitor and the power supply battery, wherein the soft start circuit, together with the power supply battery, the fuse, the input output switch and the first capacitor, forms a serial circuit. as the soft start circuit is connected, current-limiting protection can be carried out on the overall circuit, defects of damaged elements in the circuit and life loss caused by large impact current when the vehicle-mounted DC / DC converter is started or closed can be avoided, the overall vehicle fault rate and the maintenance cost are reduced, and reliability of the overall vehicle is improved. Additionally, the invention also provides a vehicle-mounted DC / DC converter input output protection method and an electric vehicle.

The embodiment of the invention discloses a slow start circuit and an LED power supply device. The LED power supply device is connected to an LED light string, and the LED power supply device includes a power input circuit, a power control circuit and a slow start circuit; the power input circuit rectifies and filters the mains power Then output the first power supply voltage and the second power supply voltage; the slow start circuit performs internal power supply after stabilizing the first power supply voltage, and outputs a pulse width modulation signal to the power supply control circuit after delaying the preset time when detecting that there is power inside; The power control circuit converts the second power supply voltage into a power supply voltage to supply power to the LED light string according to the pulse width modulation signal, and controls the LED light string to become brighter gradually. The power supply to the LED light string is delayed through the slow start circuit to limit the inrush current when the power is just turned on; the LED light string gradually becomes brighter, so that the eyes can gradually adapt, and the lighting effect is more gentle. Therefore, the problem that the existing LED power supply module cannot be started slowly and lighted at regular intervals is solved.

The invention relates to a switching circuit for an unmanned aerial vehicle. The switching circuit comprises a first switching unit, a current limiting unit, a second switching unit and a delay unit,wherein the input end, control end and output end of the first switching unit are correspondingly connected with an external power supply, a conduction unit and one end of the current limiting unit, the other end of the current limiting unit is connected with a load, the input end, control end and output end of the second switching unit are correspondingly connected with the external power supply,the conduction unit and the input end of the delay unit, and the output end of the delay unit is connected with the load. When the external power supply is required to supply power to the load, the conduction unit is switched on to provide a conduction voltage for the first switching unit and the second switching unit to connect the first switching unit and the second switching unit, the currentlimiting unit exists in a branch circuit where the first switching unit is located to limit a surge current generated immediately when the external power supply is turned on and, meanwhile, the delayunit exists in a branch circuit where the second switching unit is located, connected in parallel with the branch circuit to switch on the branch circuit where the second switching unit is located after a delay. Therefore, an input current is provided for the load after current and voltage stabilization.

A power supply method for seamless switching of motors based on residual voltage estimation: the system adopted in the method includes working and standby power supplies respectively connected to the motor, and a rectifier is connected between the output of the working and standby power supplies, and the rectifier is also connected through an inverter Motor; method: S1, modeling the residual voltage of the induction motor after de-energization; S2, predicting the residual voltage of the motor bus; S3, predicting the initial value of the residual voltage of the bus after the induction motor is de-energized, when the initial value of the residual voltage of the bus is less than the rated voltage of the bus , make sure to start the UPS inverter, so that the UPS inverter is stable in the working state of supplying power to the induction motor; S4, compare the phase of the bus residual voltage with the phase of the backup power supply voltage, and when the phase difference between the two is less than 20°, the backup Power on. The invention can not only provide short-term power supply for important loads when the mains power fails, but also actively adjust the output voltage, quickly switch the standby power supply to avoid impact on the load, and can effectively limit the instantaneous impact current of the standby power supply.

The invention discloses a control circuit for a paper shredder. The control circuit for the paper shredder comprises a paper feed detection circuit, a paper shredding delay control circuit, a starting delay control circuit, a feedback control circuit, a triggering control circuit, a switching circuit, a power circuit and a motor, wherein the paper feed detection circuit is used for detecting whether paper is placed into a paper shredding opening of the paper shredder or not; the paper shredding delay control circuit and the starting delay control circuit are used for controlling the stopping work delay time and the starting work delay time by changing the resistance value and the capacitance; the feedback control circuit is used for providing positive feedback for the starting delay control circuit; the triggering control circuit is used for controlling on-off of the switching circuit; the switching circuit is used for controlling the motor to operate or stop; the power circuit is used for supplying power to the other circuits of the paper shredder; and the motor is used for driving the paper shredder. According to the control circuit for the paper shredder, the paper shredding delay control circuit and the starting delay control circuit are arranged, the paper shredder can still work for a period of time after the tail of paper leaves the paper shredding opening, or the paper shredder can be stopped and then operate again under the condition that the tail of the paper is not completely shredded after paper-jam stopping caused by too much paper, and thus the paper can be completely shredded.

The invention relates to a power converter, which is composed of three bridge arms connected in parallel and then connected in parallel with a working capacitor; and between the midpoints of the first bridge arm and the second bridge arm, there is a commercial power input and an inductance connected in series, and the second bridge arm The primary side of the transformer is connected in series between the midpoint of the arm and the third bridge arm, and the negative side of the transformer is connected to the DC output circuit; the control terminals of the first bridge arm, the second bridge arm, and the third bridge arm are all connected to the control circuit The control signal is connected; wherein the control circuit selectively controls the conduction of the switch tube corresponding to the first bridge arm and the second bridge arm according to the detection result of the zero-crossing voltage input by the mains to perform power factor correction. The control circuit also detects the load The operating state parameters selectively control the conduction of the switch tube of the third bridge arm to output energy to the secondary side of the transformer so that the DC output circuit outputs DC; the present invention combines AC anti-surge, rectification and filtering, PFC conversion, DC / The DC is designed together, and only six switching tubes are used to complete the power conversion.

The invention discloses an input and output protection circuit of a vehicle-mounted DC converter, which comprises: an input and output switch arranged at the input end and / or the output end of the vehicle-mounted DC converter; a fuse and a first capacitor respectively connected with the input and output switches; a power supply battery connected; and a soft start circuit respectively connected with the first capacitor and the power supply battery, which together with the power supply battery, the fuse, the input and output switches and the first capacitor form a series circuit. By connecting the soft-start circuit, the present invention can perform current limiting protection on the entire circuit, avoid the defects of damage or life loss of components in the circuit caused by large inrush current when starting or shutting down the vehicle-mounted DC converter, and reduce the The failure rate and maintenance cost of the whole vehicle are reduced, and the reliability of the whole vehicle is improved. In addition, the present invention also provides an input and output protection method of a vehicle-mounted DC converter and an electric vehicle.

The invention relates to a DC power supply and a charging circuit thereof. The charging circuit of the DC power supply comprises a first voltage division unit, a control unit, a switch unit, a secondvoltage division unit, an energy storage unit and a shunt unit. The first voltage division unit is connected with a pre-stage circuit, the energy storage unit is connected with a post-stage circuit, and the second voltage division unit is connected with the energy storage unit. The control unit is connected with the first voltage division unit and the second voltage division unit, and is also connected with the control end of the switch unit; the first end of the shunt unit is connected with the pre-stage circuit, the second end of the shunt unit is connected with the energy storage unit, thefirst end of the switch unit is connected with the first end of the shunt unit, and the second end of the switch unit is connected with the second end of the shunt unit; and when the sampling voltageof the second voltage division unit is larger than that of the first voltage division unit, the control unit enables the switch unit to be closed, the shunt unit is short-circuited, energy consumptionof the shunt unit can be reduced, and power conversion efficiency is improved.

The invention provides a high-voltage battery discharge circuit and control method thereof, and belongs to the technical field of high-voltage battery solving the problem of poor safety in the prior art. The control method for the discharge circuit of the high-voltage battery comprises the following steps of: detecting whether the two ends of the capacitive load C1 are showed voltage, if so, recording the fault state as error I and alarming; if no voltage is showed, the pre-charging contactor K1 and the pre-charging contactor K4 are controlled to be closed simultaneously, detecting the voltageon the two ends of the capacitive load C1 in the suction process and recording the pre-charging time, and calculating the real-time rising rate of voltage on the two ends of the capacitive load C1 inthe unit time; if the rising rate is not within a preset range value, recording the fault state as an error II and alarming; If the rising rate is within a preset range value, the negative contactorK3 and the positive contactor K2 are controlled to be closed, the pre-charging contactor K1 and the pre-charging contactor K4 are disconnected, and the high-voltage battery discharging circuit entersa safe working mode. The high-voltage battery discharge circuit can improve the safety of the high-voltage battery.

The invention provides a relay protection circuit, including a control module and a conversion module, the control module includes a window unit, a first drive unit and a second drive unit; the conversion module includes a first conversion unit, a second conversion unit and The third conversion unit, the first drive unit includes a first drive speed control module and a relay drive module, the first drive speed control module outputs the first control signal to the relay of the first conversion unit by controlling the relay drive module; the second drive unit includes The second drive speed control module and the PFC drive module, the second drive speed control module outputs the second control signal to the PFC switch module of the second conversion unit by controlling the PFC drive module; the input end of the first conversion unit is connected to one end of the window unit The other end of the window unit outputs control signals to the first drive speed control module and the second drive speed control module. The improved circuit can limit the start-up inrush current and improve product reliability.

The invention discloses an intelligent adjustment system and an intelligent adjustment method for a power system. The intelligent adjustment system comprises a power quality acquisition unit, a host,an intelligent adjustment controller, a capacitor bank circuit breaker and a power capacitor bank. The power quality acquisition unit is used for acquiring power quality data and environment temperature and humidity data of a power system and sending the data to the host. The host is used for calculating and analyzing the electric energy quality data, judging the capacitance, reactance rate and switching-off and switching-on error time required by the power system and determining the switching-off and switching-on opportunity so as to send a corresponding adjustment instruction to the intelligent adjustment controller. The intelligent adjustment controller is used for controlling the power capacitor bank to adjust the capacitance and the reactance rate according to the adjustment instruction and carrying out switching-off and switching-on operation on the capacitor bank circuit breaker at preset time before the switching-off and switching-on opportunities according to the environment temperature and humidity. According to the invention, harmonic waves can be better suppressed, transient overvoltage can be suppressed, inrush current can be limited, and harmonic waves can be filtered, so that a power system is ensured, and safe and stable operation of a capacitor bank is protected.

The invention provides a bidirectional symmetrical resonant converter, and relates to the technical field of resonant converters. Comprising an alternating current-to-direct current control module, a first resonance adjustment module, a transformer L3, a second resonance adjustment module and a direct current-to-alternating current control module, the output end of the AC-DC control module is connected with the input end of the transformer L3 through the first resonance adjustment module. The output end of the transformer L3 is connected with the input end of the direct-to-alternating current control module through the second resonance adjusting module; and the input end of the alternating current-direct current control module is connected with the output end of the direct current-alternating current control module. According to the resonant converter, free conversion between direct current and alternating current can be achieved, the problems of low conversion efficiency and high heat loss of the resonant converter caused by an external circuit are avoided, the size of a power supply connected with the resonant converter is reduced due to reduction of energy consumption, and the convenience of movement and carrying is improved.

The invention relates to a switching circuit for an unmanned aerial vehicle. The switching circuit comprises a first switching unit, a current limiting unit, a second switching unit and a delay unit,wherein the input end, control end and output end of the first switching unit are correspondingly connected with an external power supply, a conduction unit and one end of the current limiting unit, the other end of the current limiting unit is connected with a load, the input end, control end and output end of the second switching unit are correspondingly connected with the external power supply,the conduction unit and the input end of the delay unit, and the output end of the delay unit is connected with the load. When the external power supply is required to supply power to the load, the conduction unit is switched on to provide a conduction voltage for the first switching unit and the second switching unit to connect the first switching unit and the second switching unit, the currentlimiting unit exists in a branch circuit where the first switching unit is located to limit a surge current generated immediately when the external power supply is turned on and, meanwhile, the delayunit exists in a branch circuit where the second switching unit is located, connected in parallel with the branch circuit to switch on the branch circuit where the second switching unit is located after a delay. Therefore, an input current is provided for the load after current and voltage stabilization.

A power-on surge current suppression circuit applied to a switching power supply is disclosed. The power-on surge current suppression circuit comprises an optional small-capacity filter capacitor C, an N-channel MOS tube Q, a current suppression resistor R, an outage leakage circuit, a rectifying filtering amplitude-limiting circuit and a power supply winding; the two ends of the current suppression resistor R are connected with the drain electrode and the source electrode of the N-channel MOS tube Q; the outage leakage circuit is connected between the grid electrode and the source electrode of the N-channel MOS tube Q; the rectifying filtering amplitude-limiting circuit and the power supply winding are serially connected and then connected between the grid electrode and the source electrode of the N-channel MOS tube Q; the drain electrode and the source electrode of the N-channel MOS tube Q are serially connected between a power frequency rectifier and a DC-DC converter; and the optional small-capacity filter capacitor C is connected between the positive end and the negative end of the power frequency rectifier. The surge current in the power-on moment is limited by the power-on surge current suppression circuit; the MOS tube is low in power consumption and high in starting speed; and the power-on surge current suppression circuit is short in time for allowing re-power-on.