62results about How to "Avoid thru" patented technology

The invention discloses a synchronous rectification switching power supply and a control circuit and a control method thereof. The switching power supply comprises a transformer, a primary circuit, and a secondary switching tube, wherein the primary circuit is electrically coupled to a primary winding of the transformer; and the secondary switching tube is electrically coupled between a secondary winding of the transformer and a load. The synchronous rectification control circuit is electrically coupled to a grid of the secondary switching tube, and comprises an integrating circuit, a first comparison circuit and a logic circuit, wherein the integrating circuit is electrically coupled to the secondary winding of the transformer, and is used for integrating end voltage of the secondary winding to generate an integrated signal; the first comparison circuit is electrically coupled to the integrating circuit and is used for comparing the integrated signal with a first threshold value; and the logic circuit is electrically coupled to the first comparison circuit and is used for switching off the secondary switching tube according to a comparison result of the first comparison circuit. The integral value of the end voltage of the secondary winding is compared with the threshold value, and the secondary switching tube is switched off according to the comparison result, so that the secondary switching tube can be switched off before a primary switching tube is switched on, and direct connection is effectively avoided.

The invention discloses an isolated switch converter as well as a controller and a control method thereof. The control method comprises the following steps of: sampling an output signal of the switch converter so as to generate a feedback signal; based on the difference between the feedback signal and a reference signal, generating a compensation signal; comparing the compensation signal with a modulation signal so as to generate a first comparison signal; detecting whether a primary switch tube is turned off, and then generating a primary turnoff detection signal; based on the primary turnoff detection signal and the first comparison signal, generating a secondary control signal to control a secondary switch tube; sending the first comparison signal to an isolating circuit so as to generate a synchronization signal isolated from the first comparison signal; based on the synchronization signal, generating a primary control signal to control the primary switch tube.

The invention discloses an ANPC type three-level inverter modulation method, and belongs to the technical field of electric power and electronics. The modulation method comprises the following steps:1, in the positive half cycle of a modulation voltage U<o>, when the output voltage is changed from +U<dc> / 2 to 0, two switching state changing moments of t<1> and t<2> pass by; at the t<1> moment, aT<2> tube is switched off, and at the t<2> moment, a T<3> tube is switched on; when the output voltage is changed from 0 to +U<dc> / 2, two switching state changing moments of t<3> and t<4> pass by; atthe t<3> moment, the T<3> tube is switched off, and at the t<4> moment, the T<2> tube is switched on; in the negative half cycle of the modulation voltage U<o>, the modulation method is correspondingto the abovementioned method; and 2, when the modulation voltage U<o> is in transition from the positive half cycle to the negative half cycle, four switching state changing moments of t<5>, t<6>, t<7> and t<8> pass by; at the zero-crossing point t<5> moment when the modulation voltage U<o> is changed from the positive half cycle to the negative half cycle, a T<1> tube is switched off; at the t<6>moment, T<2> and T<5> tubes are switched on; at the t<7> moment, T<3> and T<6> tubes are switched off; at the t<8> moment, the T<4> tube is switched on; and when the modulation voltage U<o> is in transition from the negative half cycle to the positive half cycle, the modulation method is corresponding to the abovementioned method. By virtue of the method provided by the invention, the problem ofbus capacitor short circuit in current conversion can be overcome; and in addition, a long current conversion circuit can be avoided in a position close to the zero crossing point of the modulation wave U<o>, so that the method has certain engineering practical value.

The invention relates to a drive circuit for preventing the oscillation of grid drive signals. The drive circuit is characterized by comprising a buffer circuit, an amplitude limiting circuit and a rapid discharge circuit, wherein the buffer circuit receives and processes a drive signal PWM (Pulse Width Modulation) and then outputs the signal to the amplitude limiting circuit; the amplitude limiting circuit processes the received signal and then respectively outputs the signal to the grid of an MOS (Metal Oxide Semiconductor) transistor and the rapid discharge circuit; and the rapid discharge circuit also receives the drive signal PWM. The drive circuit has the advantages of lowering the voltage change rate of the MOS transistor, decreasing the open surge in the opening process, reducing the impact and damage to the MOS transistor, improving the EMC (Electro Magnetic Compatibility) property of the whole switch power supply, decreasing the turnoff loss, effectively avoiding the abnormal oscillation of drive signals, protecting normal working states of the MOS transistor and the circuit, and the like.

The invention discloses a unified-winding bearingless motor. The motor is characterized in that the motor comprises a stator and a rotor. Each two adjacent teeth arranged on the stator forms one pair; and for the two pair of opposite teeth arranged on the periphery of the stator based on a phase difference of 180 degree for each phase, one group of windings is arranged on one pair of teeth; and two sets of windings of each phase are driven by a drive module. Besides, two position sensors for measuring a deviation position of a rotor are arranged on the stator; and a 90-degree phase difference exists between the two position sensors. In addition, the motor also includes a drive control system connected with the drive module. According to the invention, the structure is simple; the rotor is suspended; no mechanical wearing phenomenon occurs; no mechanical bearing supporting is required; the hardware structure is simple; and a bridge shoot-through problem can be solved.

The invention discloses a CO2 laser power supply intelligent controller developed based on a digital signal processor (DSP) TMS320LF2410. The quickness and the stability of laser energy can be realized by adopting a method of glow start constant-voltage control and work constant-current control. The invention provides an on-line discrimination method for laser power supply idle load, laser tube damage and other abnormal conditions and a drive signal isolating interlocking circuit aiming at the potential hazard for intervening and causing the straightway of a bridge type circuit. The inventionhas the advantages that: the laser output energy can be quickly and accurately stabilized by adopting the DSP to carry out constant-voltage and constant-current control on the laser power supply; thestraightway of an upper bridge arm and a lower bridge arm at abnormal state can be effectively avoided by directly using control signals of MOSFET (Metal-Oxide -Semiconductor Field Effect Transistor)tube grid electrodes of the upper bridge arm and the lower bridge arm as an interlocking signal source; and the laser source idle load, the damage of the laser tube and other abnormal conditions can be identified on line and the work of the power supply can be instantly stopped when the CO2 laser source is in open circuit and the damage of the laser tube and other abnormal conditions generate, thereby the phenomenon that the power supply is burnt down because the high voltage cannot be discharged in time can be effectively avoided.

The invention discloses a gate drive circuit without static power consumption, and belongs to the technical field of electronic circuits. A floating power supply ground module is used for generating afloating power supply ground signal and a high side reset signal, wherein a low voltage-high voltage level shifting module is used for shifting a low voltage driving signal of a front stage to a highvoltage side to control a high side power transistor; a high voltage-low voltage level shifting module is used for feeding back a high side signal of the floating power supply to a low side, and closing an input stage in the low voltage-high voltage level shift module through a logic control module to ensure that the gate drive circuit provided by the invention is free from static power consumption; and a drive output module drives the high side power transistor and a low side power transistor respectively by using the high side drive output unit and the low side drive output unit, and the logic control module provides logic control. The gate drive circuit is free from static power consumption, and meanwhile the problem of voltage resistance of a gate source is solved well.

The present invention discloses a three-phase dual-input inverter not having a bridge arm shoot-through risk. The three-phase dual-input inverter is composed of two independent input sources, nine switch tubes, seven diodes and six filtering inductors and has 48 working modes. When the inverter is located in any one mode, one of or both of an upper tube and a lower tube of a bridge arm is or are in reverse series connection with one diode in a topology, thereby avoiding a shoot-through structure, and being high in reliability. According to the present invention, the double input power supplies and the increased switch tubes S2, S5 and S8 and the diode D0 are utilized to form the five-level output having a very simple structure, the voltages of the double input sources Vin1 and Vin2 of a system are different, and by controlling, a purpose of supplying power to the inverter in a time-sharing manner is achieved. If the input source Vin1 is obtained by boosting the input source Vin2, a part of output power of the system comes from the input source Vin1 directly, and the other part comes from a boost unit, thereby realizing the single-stage transformation of the partial power, not only reducing the capacity of the boost unit, but also improving the efficiency of the system.

The invention discloses a control method for minimum current stress of a double active bridge DC-DC converter on the basis of consideration for a dead zone effect. The method comprises the following steps: constructing first and secondary side voltage waveforms and a current waveform passing by an inductor according to the magnitude relation of a dead zone proportion, an inner phase shifting angle, an outer phase shifting angle and a current zero-crossing-point position; constructing a power model according to the acquired voltage and current waveforms; and utilizing a genetic algorithm to analyze the parameter selection under the minimum current stress according to the established output power model and current stress model, and acquiring a minimal current stress optimizing strategy. According to the invention, for a voltage matching mode, the dead zone effect of DAB under double phase shifting strategy is analyzed in details, and a system switching characteristic and an output power model on the basis of consideration for the dead zone effect are acquired; on the basis, the genetic algorithm is utilized to acquire an optimization scheme for the minimal current stress; and finally, an experiment is adopted for verifying the theory.

The invention discloses a combined bidirectional DC-DC conversion circuit, belonging to an energy bi-directional flow DC-DC conversion technology. When energy is required to flow from a filter capacitor end of a first terminal to a filter capacitor end of a second terminal, the invention can automatically realize the operation of a step-down bridge arm circuit, and the step-up bridge arm circuit does not work. When energy is required to flow from the filter capacitor terminal of the second terminal to the filter capacitor terminal of the first terminal, the invention can automatically realizethe operation of the boost bridge arm circuit, and the buck bridge arm circuit is not operated. As two inductors are serially connected between the step-down bridge arm circuit and the step-up bridgearm circuit, the problem that two power switch transistors in the two bridge arm circuits are directly connected does not exist, and the reliability of the conversion circuit is greatly improved. At the same time, the use of independent diodes as freewheeling diodes is conducive to optimizing the design of power devices and improving the efficiency of the converter. The present invention is suitable for electric vehicles, fuel cells, photovoltaic power generation, wind power generation and other new energy supply systems requiring bidirectional energy flow.

The invention discloses a switch power supply and a rectifying circuit. The rectifying circuit comprises a first controllable switching tube, a second controllable switching tube, a third controllable switching tube, a fourth controllable switching tube, a first sampling comparison module, a second sampling comparison module, a first driving module and a second driving module. The four controllable switching tubes are respectively provided with an internal equivalent diode or an anti-parallel diode. The two sampling comparison modules are respectively used for conducting sampling on the positive half circle voltage and the negative half circle voltage and conducting comparison on the sampling voltage of the positive half circle of an alternating current power supply and the reference voltage value. The first driving module is used for controlling the switch-off of the second controllable switching tube and the third controllable switching tube when the sampling voltage of the positive half circle of the alternating current power supply is smaller than the reference voltage value. The second driving module is used for controlling the switch-off of the first controllable switching tube and the fourth controllable switching tube when the sampling voltage of the positive half circle of the alternating current power supply is smaller than the reference voltage value, and controlling the switch-on of the first controllable switching tube and the fourth controllable switching tube when the sampling voltage of the positive half circle of the alternating current power supply is larger than the reference voltage value. The switch power supply can improve the switching efficiency of the alternating current power supply and is simple in the control method.

The invention discloses a circulation-free three-phase double-Buck full-bridge inverter and a control strategy thereof, and belongs to the technical field of power electronic converters. The inverteris composed of two DC input voltage sources (VH, VL), twelve switching tubes (Sa1-Sa4, Sb1-Sb4, and Sc1-Sc4), eight diodes (Da1, Da2, Db1, Db2, Dc1, Dc2, DP and DN), six filter inductors (La, Lb, Lc,Lfa, Lfb and Lfc) and three alternating-current loads (Za, Zb and Zc). According to the invention, only by use of one inverter, it is achieved that two independent direct-current input sources supplypower for the alternating-current loads, and the functions of the two single-input inverters are achieved. The circulating-current-free three-phase double-Buck full-bridge inverter provided by the invention is free of bridge arm straight-through and switching tube body diode reverse recovery problems, and can work in a fixed-frequency circulation-free mode under a proposed control strategy, so that the reliability and the efficiency are high. The inverter and the control strategy are suitable for high-efficiency and high-reliability power supply application occasions such as new energy power generation and aviation airborne power supplies.

The invention discloses a high-reliability five-level three-phase dual-input inverter. One kind of three-phase dual-input inverter is composed of two independent input sources, twelve switch tubes, twelve diodes and six filtering inductors. The other kind of three-phase dual-input inverter is composed of two independent input sources, twelve switch tubes, eight diodes and six filtering inductors. When the inverter of the invention is in any mode, one of an upper arm and a lower arm is in reverse series connection with one of the diodes in the topology, and shoot-through can be avoided structurally, and reliability is high; multi-level output is realized by means of combination and conversion of the two input power sources and the switches; the voltages Vin1 and Vin2 of the two input sources of the system are different, so that power can be supplied for the inverter in a time-division manner through control; and if the voltages Vin1 and Vin2 are obtained through boosting, one part of the output power of the system comes from Vin1, the other part of the output power of the system comes from a boosting unit, and therefore, single-stage conversion of part of the power can be realized, and the capacity of the boosting unit can be decreased, and the efficiency of the system can be improved.

The invention discloses a controller for reversing of a series motor of a series electric vehicle, and relates to a controller for achieving reversing of a series motor. The controller controls conduction sequences of an MOS (metal oxide semiconductor) tube to substitute for a contactor to achieve reversing of the series motor, and comprises a hardware part and a software part, the hardware part is composed of a power circuit and a driving circuit, and the software part comprises a controller program, a regenerative feedback program and a flux-weakening speed regulating program. The controller overcomes the defects of low reversing speed of the contactor, loud noise and overlarge energy consumption due to long-time through large current.

The invention discloses a precoated sand mold for casting a stainless steel thin-walled workpiece. The precoated sand mold comprises a cover mold, at least one intermediate mold and a bottom mold, which are arranged in order from top to bottom, wherein casting cavities are formed between the adjacent molds; a communicated vertical runner is formed in the cover mold, the intermediate mold and the lower mold; one end of the vertical runner is arranged on a pouring gate on the cover mold, and the other end blocks the bottom mold; the vertical runner is communicated with a transverse runner; the transverse runner is communicated with the casting cavities through auxiliary runners; the casting runners are communicated with exhaust vents. With adoption of the precoated sand mold disclosed by the invention, the stainless steel casting with the thickness of 2-3 mm can be casted; the casting is not liable to crack; the finished product yield is high.

The invention discloses a three-phase four-bridge-arm inverter based on SiC MOSFET. The three-phase four-bridge-arm inverter comprises a main power circuit, a processor, a direct-current voltage acquisition circuit, a drive protection circuit, a current acquisition circuit and a load voltage acquisition circuit. The direct-current voltage acquisition circuit acquires direct-current input voltage in the main power circuit and feeds back the direct-current input voltage to the processor. The current acquisition circuit acquires load current in the main power circuit and feeds back the load current to the processor. The load voltage acquisition circuit acquires load voltage in the main power circuit and feeds back the load voltage to the processor. The processor outputs eight paths of controlsignals to the drive protection circuit, and the drive protection circuit generates four paths of upper bridge arm drive signals and four paths of lower bridge arm drive signals, wherein the upper bridge arm drive signals and the lower bridge arm drive signals of the same bridge arm are interlocked. The three-phase four-bridge-arm inverter based on the SiC MOSFET has the advantages of being highin driving frequency, high in response speed, small in peripheral component size, small in switching loss, small in heat productivity and the like.

The invention discloses an inverter upper bridge driving circuit. The inverter upper bridge driving circuit comprises a charging circuit and a driving circuit, wherein the charging circuit comprises afirst diode D1 and a first capacitor C2, the charging circuit is used for charging the first capacitor C2 through first power supplying voltage to provide second power supplying voltage through the first capacitor C2; the driving circuit comprises a first transistor Q2, a collector electrode of the first transistor Q2 is connected with a controlled end of an upper bridge transistor Q3 of a bridge-type inverter circuit, and the driving circuit is used for driving break-over or cut-off of the upper bridge transistor Q3 of the bridge-type inverter circuit through the second power supplying voltage output by the first capacitor C2. The inverter upper bridge driving circuit is simple, high in reliability, low in overall power and low in production cost; meanwhile, shoot-through of the upper bridge transistor Q3 and a lower bridge transistor Q5 can be avoided.

The invention relates to a bidirectional photovoltaic inverter based on high-frequency legs. The inverter is characterized by comprising at least one forward high-frequency N-cell leg, at least one backward high-frequency N-cell leg and two power-frequency P-cell legs in parallel connection, wherein each forward high-frequency N-cell leg is connected with one inductor to be used as the anode output end of a power supply, and each backward high-frequency N-cell leg is connected with one inductor to be used as the cathode output end of the power supply; and each forward / backward high-frequency N-cell leg is formed by connecting a diode with a high-frequency switch in series, and each power-frequency P-cell leg is formed by connecting a diode with a power-frequency switch in series. The inductors whose currents work in positive half waves are mutually coupled, and the inductors whose currents work in negative half waves are mutually coupled. The bidirectional photovoltaic inverter can be switched between a photovoltaic mode and an energy-storing mode at random, the size of the inverter is small, problems in direction connection can be avoided, current leakage can be effectively inhibited, the system frequency is increased, bidirectional power control is realized, and the capacity is easy to increase.

The invention discloses a dual-input bidirectional inverter with high reliability and high energy efficiency, and belongs to the technical field of a power electronic converter. The converter comprises two DC input voltage sources (V<in1>-V<in2>), six switch tubes (S1-S6), four diodes (D1-D4), two filtering inductors (L1-L2), a filtering capacitor (Co) and a load (Z<load>). Power is simultaneouslysupplied to an AC load or supplied to the AC load according to time from the two independent DC input sources only by the inverter, the functions of the two single-input inverters are achieved, and the inverter has the advantages of high integration, high efficiency and low cost. Each high-frequency switch bridge arm is formed by connecting a switch tube and a diode in series, the problem of bridge arm direct through is prevented, and high reliability is achieved; various levels can be generated in a middle point of the bridge arm, and the switch loss and the volume of a filter are favorablyreduced; and an output can work within four quadrants of a current voltage, and the application range is wider than that of a two-quadrant gird-connected inverter.

The invention discloses a CPLD-based brushless motor electronic commutation method. The method comprises the following steps: with a CPLD being an operation platform, receiving a direction signal output by a DSP and a Hall position signal of a motor; switching a PWM signal output by the DSP to an appropriate PWM control channel in real time to finish electronic commutation work of the motor; and meanwhile, according to a BIT signal output by the DSP and the motor Hall signal, judging and outputting a motor BIT self-checking signal in real time. Compared with the prior art, the method has the advantage and beneficial effects that motor rotation direction is judged in time and correct commutation of the motor is ensured; each path of PWM signal output by the CPLD controls a switch of one MOS transistor, thereby realizing PWM signal single-line injection; interfaces are simple; when the direction signal jumps, automatic insertion to a dead zone is realized, thereby preventing bridge arm direct connection; and reliability is high.

The invention is an interleaved two-transistor forward converter with phase-shift control. The converter includes a first transformer primary winding Lt1, a second transformer primary winding Lt2 anda transformer secondary winding Lt3, which are connected in parallel and share the same magnetic core. The turn ratio of the three windings is n: n: 1. A transformer secondary side rectifier unit is arectifier bridge composed of four diodes. The dotter terminal of the transformer secondary winding Lt3 is connected to the midpoint of one bridge arm of the rectifier bridge, and the undotted terminal is connected to the midpoint of the other bridge arm of the rectifier bridge. A filter capacitor C0 and a load R0 are connected in parallel with each other, connected in series with a freewheel inductor L0 and connected in parallel with a rectifier unit. L0>>Lr / n. Only one magnetic core is used, and the two primary windings are wound on the magnetic core and coupled to each other. Forward and reverse excitation of the magnetic core of the transformer realized, the utilization ratio of the magnetic core is improved, the power density of the converter is improved, and the volume of the outputfilter is reduced. Moreover, the circuit structure of the secondary winding side is optimized, and the topological reliability is improved.

The invention provides a voltage compensating device able to avoid thyristor direct connection, including compensating transformer T and thyristor bridge. Primary winding of T is composed of at leasttwo windings W1 and W2 respectively, their number of windings same; the thyristor bridge uses at least 8 single-way thyristors S1-4 and S5-8, divided into two groups to compose thyristor bridge groupH; S1 and S2 with the cathodes connected together are linked with header point of W1; S3 and S4 with the anodes connected together are linked with header point of W2; S5 and S6 with the cathodes connected together are linked with end point of W2; S7and S8 with the anodes connected together are linked with end point of W1.

The invention discloses an IGBT (Insulated Gate Bipolar Transistor) driving circuit with dead zone adjustment. The IGBT driving circuit comprises a slide rheostat R1, a first resistor R2, a second resistor R3, a third resistor R4, a fourth resistor R5, a fifth resistor R6, a sixth resistor R7, a seventh resistor R8, an eighth resistor R9, a ninth resistor R10, a tenth resistor R11, a first capacitor C1, a second capacitor C2, a third capacitor C3, a fourth capacitor C4, a fifth capacitor C5, a square-wave generator U1, a phase inverter U2, a photoelectric coupler U3 and a Schmidt phase inverter U4. According to the IGBT driving circuit, used components and parts are developed and reliable, low in cost and abundant in sources. The circuit provided by the invention is the IGBT driving circuit with the dead zone adjustment and can drive a large-power ultrasonic transducer; up-down bridge arm direct connection caused by a turn-off delay effect can be avoided effectively; and the reliability and the safety of the working of an IGBT module are improved.

The drive system includes DC power supply, polyphase bridge type inverter circuit controlled by controller, and driven polyphase AC motor. The DC power supply includes a positive pole, a negative pole, and a common end. The inverter circuit is in two phase's bridge type, and its buses of positive and negative sources are connected to positive and negative pole of DC power supply respectively. The motor is symmetrical motor in two phases, and common end of windings in two phases is connected to the common end. The other end of each phase winding is connected to middle point of each phase bridge arm. The controller outputs symmetrical modulation signal in two phases. The modulation is pulse width modulation of sine wave in unipolarity. Comparing with traditional system, the disclosed design possesses identical or better waveform of operating voltage and driving performance. The invention reduces feed through probability of bridge arm, and raises reliability of inverter circuit.

The invention discloses a power module driving circuit and an air conditioner, the power module driving circuit comprises a switch driving circuit and a power supply circuit for supplying power to the switch driving circuit, the switch driving circuit comprises at least one bridge arm formed by connecting switch tubes in series, and the power module driving circuit further comprises a fault-tolerant circuit connected between the switch driving circuit and the power supply circuit, and and the fault-tolerant circuit discharges the Miller current generated by the switching tube. Compared with the prior art, the Miller current is discharged through the fault-tolerant circuit, and the problem that the same bridge arm in the switch driving circuit is straight through and the power module is blown up is solved.

The invention discloses a secondary inverter driving circuit for an alternating current-direct current argon arc welding machine. The secondary inverter driving circuit comprises a triangular wave generation circuit, a chopper circuit and a time-delay circuit, wherein the triangular wave generation circuit is used for generating a triangular wave; the chopper circuit is connected with the output end of the triangular wave generation circuit and used for outputting a square wave with an adjustable duty ratio; and the time-delay circuit is connected with the output end of the chopper circuit and used for generating two driving signals with dead time.

The invention relates to an ISOP type direct-current distribution transformer and a control method thereof. The ISOP type direct-current distribution transformer comprises n cascaded sub-modules, wherein each sub-module comprises a double-Buck circuit, a half-bridge converter, a high-frequency transformer and a full-bridge converter; one end of the primary side of the high-frequency transformer isconnected with the double-Buck circuit, the other end is connected with the half-bridge converter, and the secondary side of the high-frequency transformer is connected with the full-bridge converter. According to the technical scheme provided by the invention, the n cascaded sub-modules are adopted, and each sub-module comprises a double-Buck circuit, a half-bridge converter, a high-frequency transformer and a full-bridge converter, the problems of low reliability and poor DC fault inhibition capability in the direct-current power distribution network in the prior art are solved, the fault processing capability is improved, the high-frequency operation is realized, the power density of the device is improved, and more convenient conditions are provided for the application of the direct-current power distribution network in the future.