40results about How to "Reduce common mode current" patented technology

The invention discloses a common-mode voltage suppression method for a non-isolated T-shaped tri-level photovoltaic grid-connected inverter. The method comprises steps as follows: voltage of an upper capacitor C1 of a direct-current bus and voltage of a lower capacitor C2 of the direct-current bus are collected in real time to obtain an absolute value dUdc of voltage difference of the upper capacitor C1 and the lower capacitor C2 of the direct-current bus; whether dUdc is larger than dUref and whether Uc1 is larger than Uc2 are judged, so that a large and medium zero vector synthesis method, a large, medium and small vector synthesis method or a large and large zero vector synthesis method is selected and utilized for modulating the non-isolated T-shaped tri-level photovoltaic grid-connected inverter. The three vector synthesis methods are adopted to modulate the non-isolated T-shaped tri-level photovoltaic grid-connected inverter, so that the midpoint potential of the direct-current side of the tri-level inverter can be balanced, the amplitude and frequency of common-mode voltage change can be suppressed, accordingly, common-mode current of the non-isolated T-shaped tri-level photovoltaic grid-connected inverter is suppressed, and the efficiency, the size, the weight and the cost of a system are optimized.

An apparatus is provided for heating a hydrocarbon resource in a subterranean formation having a wellbore extending therein. The apparatus includes a radio frequency (RF) antenna configured to be positioned within the wellbore, a transmission line configured to be positioned in the wellbore and coupled to the RF antenna, and an RF source configured to be coupled to the transmission line. The apparatus also includes a balun configured to be coupled to the transmission line adjacent the RF antenna within the wellbore. The balun comprises a body defining a liquid chamber configured to receive a quantity of dielectric liquid therein.

A transformer capable of suppressing common mode current and a power converter thereof are provided. The transformer comprises a primary winding, a secondary winding, a magnet core and a shielding winding layer. The shielding winding layer has a first shielding winding and a second shielding winding. A voltage jump direction of the first shielding winding is constantly opposite to that of the second shielding winding. The shielding winding layer is coupled to a static terminal coupled with the primary winding or the secondary winding.

An electronic device comprising: a wiring substrate having a first power-supply wiring to which a first power-supply potential is applied and a second power-supply wiring to which a second power-supply potential lower than the first power-supply potential is applied; a microcomputer having first and second power-supply terminals in which the first power-supply terminal is connected to the first power-supply wiring and the second power-supply terminal is connected to the second power-supply wiring; and a connector connected to the first and second power-supply wirings, wherein an inductor element for correcting an impedance error of the first and second wirings is connected in series to either one of the first and second power-supply wirings. According to such configuration, unnecessary electromagnetic radiation posed by a common current can be suppressed.

The invention discloses an FPGA-based optical interface 1+1 protection isolated multi-service Ethernet optical transceiver, comprising an optical signal transceiving circuit, a power supply circuit and a signal enhancement circuit, wherein the signal enhancement circuit comprises a first coil and a second coil, a capacitor C1 is coupled between a node at which the first coil and the second coil are connected and the ground, the secondary of an input transformer is also coupled with a common mode inductor, the arranged common mode inductor can suppress the outward radiation of electromagnetic waves during high-speed signal transmission from interfering with the signal transmission of adjacent equipment, the arranged capacitor C1 serves as a tap capacitor and is combined with the power supply circuit to provide a function of a DC bias voltage or a power source, the common mode current and common mode voltage on a cable can also be reduced by providing a low-impedance reflux path of common mode noises on a differential line, and thus the arranged enhancement circuit can not only enhance optical signals and extend the transmission distance, but also isolate the two ends of the input transformer and further prevent lightning strikes.

The present invention belongs to the technical field of power electronics and provides a common mode current suppression circuit of a motor drive system for solving the interference of high frequency interference generated by a controllable rectifier and an inverter on a motor drive system and surrounding devices. The present invention includes three LC filter circuits, a transmission device and a micro control unit; the three LC filter circuits are respectively connected in series between the inverter output end and the motor input end, each LC filter circuit is formed by an adjustable inductor and a non-polar capacitor connected in series; the micro control unit controls the transmission device according to the frequency of the modulated wave signal output by the inverter; and the transmission device controls the inductance value of the adjustable inductor in each LC filter circuit separately by a sliding sheet, so that the driving current of the motor reaches the resonance in the LC filter circuit . The common mode current suppression circuit effectively suppresses the total conduction path of the common mode current to realize the common mode current suppression of the motor drive system, and ensures that the driving signal of the motor cannot be attenuated.

the invention provides a spatial vector modulation method of an indirect matrix converter. The method comprises the following steps of determining a first duty cycle of a zero vector of an inversion stage, selecting a plurality of turning periods in a modulation period, wherein the total time length of the plurality of turning periods is the product of the first duty ratio and the modulation period, taking the starting time of each turning period as the modulation time for the switching states of the rectifying stage and the inversion stage in each turning period, adjusting all the switches ofthe rectifying stage to be disconnected at the starting moment of each turning period, remaining all the switching states of the inversion stage unchanged; namely, disconnecting all the switches of the rectification stage to realize the introduction of a zero vector into the inversion stage, in the modulation process of the indirect matrix converter in a time period when a zero vector originallyneeds to be led into to the inversion stage. The switch state at the initial moments of the time periods at the inversion stage does not need to be adjusted, so that the frequency of the action of theswitch of the inversion stage is reduced on the basis of reducing the common mode current. The loss of the system is reduced.