43results about How to "Reduce voltage and current stress" patented technology

The invention discloses an electric automobile wireless charging method and system based on a double transmission-double picking mode. The electric automobile wireless charging method based on the double transmission-double picking mode comprises the steps of inputting direct current voltage into two inverter circuits; enabling an output end of the first inverter circuit to load high frequency alternating current to a first primary side transmitting coil through a first primary side resonance circuit so as to generate a high frequency magnetic field; generating electric energy after sensing the high frequency magnetic field through a first secondary side picking coil; inputting the electric energy into a first buck-boost converter through a first secondary side resonance circuit and a first rectification filter circuit; enabling an output end of the second inverter circuit to load high frequency alternating current to a second primary side transmitting coil through a second primary side resonance circuit to generate a high frequency magnetic field; generating electric energy after sensing the high frequency magnetic field through a second secondary side picking coil; inputting theelectric energy into a second buck-boost converter through a second secondary side resonance circuit and a second rectification filter circuit; converting the electric energy into load electric energyby using the two buck-boost converters; and outputting the load electric energy to a series-connected load.

The invention provides a wide-voltage-range output current feed converter, which comprises a primary side power circuit, a first secondary side rectification circuit, a second secondary side rectification circuit and a change-over switch circuit, wherein the primary side power circuit is connected to the first secondary side rectification circuit and the second secondary side rectification circuitthrough a main power transformer; the first secondary side rectification circuit and the second secondary side rectification circuit are respectively connected with the change-over switch circuit; and the change-over switch circuit adjusts the output ends to be connected in series or in parallel by controlling the on-off state. According to the change-over switch circuit, the output ends are adjusted to be connected in series or in parallel by controlling the on-off state, high-voltage small current is output during series connection, low-voltage large current is output during parallel connection, the wide-voltage-range output requirement of the converter is further met, voltage and current stress of components such as a main power switch tube, a transformer and an alternating-current inductor in the circuit design is small, and therefore the power density and the efficiency of the power source can be effectively improved.

The invention relates to a current path reconstruction type single-phase five-level rectifier. The rectifier comprises an alternating current power source VS, an inductor L, switching tubes S1, S2 andS3, diodes D1-D8, capacitors C1 and C2 and a load RL. According to the current path reconstruction type single-phase five-level rectifier of the invention, a plug-in diode uncontrolled rectifier bridge rectifying unit exists in the topological structure of the rectifier, the number of needed switches can be increased or decreased to a certain extent, switching tubes are applied to power factor correction, and therefore, on one hand, a circuit structure is simpler, and on the other hand, circuit control difficulty can be reduced. The rectifier can be widely applied to the field of single-phasesmall and medium-power rectifiers.

The invention relates to a SiC MOSFETE open-loop active driving circuit, and belongs to the technical field of circuit control. The circuit comprises a traditional driving circuit and an auxiliary circuit, the auxiliary circuit comprises a di/dt detection circuit and a shunting circuit, the di/dt detection circuit is used to determine ON and OFF states of a SiC MOSFETE, and transmits the signal obtained by determining to the shunting circuit, and the shunting circuit is used to shunt gate current of the SiC MOSFET via the signal of the di/dt detection circuit. According to the provided SiC MOSFETE open-loop active driving circuit, the shunting circuit and the di/dt detection circuit are added to the traditional SiC MOSFET driving circuit, the ON/OFF delay time is shortened, the switching loss is reduced, the active driving circuit is of open-loop operation, and the system cost and complexity are reduced.

The invention discloses a wireless charging receiving end load modulation switch zero-voltage asynchronous control method and a wireless charging receiving end load modulation switch zero-voltage asynchronous control circuit. The wireless charging receiving end load modulation switch zero-voltage asynchronous control method comprises the steps of: designing an asynchronous control circuit based onalternating voltage characteristics of a positive input end and a negative input end of a wireless charging receiving end; and using the asynchronous control circuit to drive and control two load modulation switches for asynchronously output, so that switching tubes connected with the load modulation switches are conducted when the corresponding alternating voltage is low. According to the wireless charging receiving end load modulation switch zero-voltage asynchronous control method, the asynchronous control circuit is designed based on the alternating voltage characteristics of the positiveinput end and the negative input end of the wireless charging receiving end, when the load modulation switches are driven to be switched on, the corresponding alternating voltage is low, namely zerovoltage is turned on, the corresponding switch tubes are further turned on when the corresponding alternating voltage is low instead of being turned on immediately after a load modulation signal is ready, and the voltage and current stress of the load modulation switch tube can be effectively reduced.

The invention discloses a coordination and protection method and device of DC grid having a resistive type superconductive current limiter. The resistive type superconductive current limiter is put into a fault discharging loop. The method comprises the steps of obtaining a first impedance scope of the resistive type superconductive current limiter when the fault discharging loop reaches to the over-damping state; obtaining a second impedance scope of the resistive type superconductive current limiter when the fault current of the fault discharging loop begins to be attenuated; obtaining a third impedance scope of the resistive type superconductive current limiter based on the movement time of a master breaker in a DC breaker; obtaining the impedance value of the resistive type superconductive current limiter based on the first impedance scope, the second impedance scope, and the third impedance scope. The invention is advantageous in that through selecting the impedance value of the superconductive current limiter, the fault current can be effectively inhibited; it can be guaranteed that the DC breaker can reliably turn off the fault current, and the voltage and current stress ofa switch member can be reduced.

The invention discloses a dynamic wireless electric energy constant power output system and an equivalent resistance control method thereof and relates to the technical field of dynamic wireless electric energy transmission. The system comprises a transmitting end and a receiving end, wherein the transmitting end comprises a transmitting coil Lp; the receiving end comprises a secondary side assembly 1 and a secondary side assembly 2 which are connected with a load R; the secondary side assembly 1 comprises a receiving coil Ls1 parallel to the transmitting coil Lp; the secondary side assembly 2comprises a receiving coil Ls2 parallel to the transmitting coil Lp; the receiving coil Ls1 and the receiving coil Ls2 each comprise a square coil with a side length of L; the transmitting coil Lp comprises a plurality of square coils with the side length of L in cascade connection; the receiving coil Ls1 and the receiving coil Ls2 are overlapped to form a secondary side coil assembly, and the length of the overlapped part is L/2. According to the system disclosed by the invention, the total power is averagely distributed in the receiving end of the secondary side assembly 1 and the receivingend of the secondary side assembly 2 in a moving process, voltage-current stress of a switching tube can be decreased, and constant output power of the system is ensured.

The invention discloses a power electronic transformer circuit, a power electronic transformer and a control method of the power electronic transformer; a multi-winding transformer is arranged among acascade H bridge and an inversion H bridge connected with a three-phase alternating current power grid, and a rectifying H bridge arranged at the input end of a direct current power grid; the input end of the multi-winding transformer is connected with H bridge modules connected from a three-phase alternating-current power grid; the input power of each H bridge module comprises a direct-current component and a secondary pulsation component, and the secondary pulsation power is in a rule of three-phase symmetry and negative sequence; after the multi-winding transformer is input from the threeH bridge modules, the output power of the multi-winding transformer is equal to the synthesis of input power of three ports according to the power balance relation, the secondary pulsation power is counteracted, and only the direct current component is transmitted to the direct current output end. A direct-current capacitor in the cascaded H bridge does not need to store pulse power, and the volume of the direct-current capacitor can be remarkably reduced, so that the size of the power electronic transformer is reduced, and the voltage and current stress of the power device is reduced.

The present discloses a control method of a LCC resonant DC-DC converter and a device thereof, used for controlling the LCC resonant DC-DC converter to realize zero-voltage soft switching operation in a wide input voltage range and a wide load range. According to the control method, by circuits controlling turn-on time and turn-off time of switch tubes of the LCC resonant DC-DC converter, the turn-on time and the turn-off time of the switch tubes vary with an input voltage and a load. The turn-on time and the turn-off time of the switch tubes are determined by an error value between an output voltage and a reference signal. Because a resonant current can not have an abrupt change, when any switch tube turns off, a body diode of the other switch tube immediately turns on, so that the switch tubes all work in a zero-voltage soft switching state. The control method of the LCC resonant DC-DC converter and the device thereof can reduce a switching frequency variation range of the conventional LCC resonant DC-DC converter and maintain the zero-voltage soft switching operation condition of the LCC resonant DC-DC converter in the wide input voltage range and the wide load range.

A simplified multilevel DC converter circuit structure comprises a dual input DC power supply, a power control module and an AC side low-pass filter, wherein each of the dual input DC power supply supplies half of the rated DC voltage to the power control module, and the power control module is composed of six power switches, and different switching combinations of each power switch are controlled to convert a DC voltage to an output of an AC voltage, and two of the power switches of the power control module perform a low-frequency switching twice every cycle of the output voltage, and the withstand voltage is equal to the input voltage, and the remaining power switches perform the switching by a high frequency, and the withstand voltage is only half of the input voltage, such that a multilevel voltage can be outputted, and a low harmonic AC waveform can be outputted from the AC side low-pass filter.

The invention discloses a lithium battery system with the self-repair function and a self-repair method thereof and belongs to the battery fault repairing field. The system includes a bidirectional DC/DC converter, a super capacitor bank, a processor, a battery detection module and a battery pack composed of multiple lithium batteries and multiple switches, wherein the super capacitor bank is usedfor providing power for the bidirectional DC/DC converter, the battery detection module is used for detecting status data of each lithium battery in the battery pack, the status data is faulty or normal, when the status data is faulty, the faulty lithium battery is replaced by the bidirectional DC/DC converter by controlling turn-on and turn-off of the multiple switches in the battery pack by theprocessor. The system is advantaged in that when a lithium battery fault occurs in the system, the external power supply of the system is abnormal, the self-repair function is for self-repairing external power supply abnormality of the system, after detecting the faulty lithium battery, the faulty lithium battery is replaced by the bidirectional DC/DC converter, so that the external power supplyof the system returns to normal, and the self-repair feature is achieved.

The invention provides an SCDAB-CLLLC composite direct-current transformer with a wide voltage regulation range and a control method thereof. A main circuit comprises a switched capacitor type bidirectional full-bridge DC/DC converter and a CLLLC type resonant converter which are cascaded in an input-series output-parallel manner, so the requirement on the transformation ratio of a high-frequency transformer is reduced, the voltage and current stress of an input side power device is reduced, and the voltage regulation range is wide. The controller takes a DSP as a core device and has the functions of overvoltage and overcurrent protection, phase shift control and frequency modulation control; the phase shift control is applied to the switched capacitor type bidirectional full-bridge DC/DC converter, and the frequency modulation control is applied to the CLLLC type resonant converter.