166results about How to "Improve EMC performance" patented technology

The invention discloses an automatic testing system and an automatic testing method for the non-contact transmission characteristics of a millimeter waveband. The method comprises the following steps of: initializing the automatic testing system for the non-contact transmission characteristics of the millimeter waveband; calibrating the automatic testing system for the non-contact transmission characteristics of the millimeter waveband, and finishing a spatial transmission characteristic test under the condition of no element to be tested to obtain test information in a calibration state; finishing a transmission characteristic test under the condition that the element to be tested exists to obtain test information in a test state; obtaining the corresponding power information of a transmitter and a receiver under each frequency value; and subtracting power information obtained in the calibration state from power information obtained in the test state, and displaying a test curve of the transmission characteristics of the element to be tested. By the system and the method, a test in transmission characteristic parameters of 76 to 77GHz can be realized automatically, the problem of absence of millimeter wave testing means and testing equipment is solved, and the shortcomings of high cost, large volume, difficulties in automatic control and the like of testing equipment are overcome.

The invention relates to a fan drive circuit and a fan using the same. The fan drive circuit comprises a buck chopping drive circuit (1) used for converting input pulse width modulation signals into high-frequency rapid drive signals and a buck chopping main circuit (2) for controlling and outputting the fan drive voltage according to the high-frequency rapid drive signals. By implementing the fan drive circuit and the fan in the invention, the Buck drive circuit is adopted, thus improving efficiency of the fan drive circuit; the Buck main circuit adopts an MOS tube to drive over the ground, thus facilitating the control of the MOS tube; a Buck inductor is arranged on a negative busbar, and the positive and the negative poles of the fan are in a stable level, thus facilitating voltage detection of the fan, reducing copper sheet area of the jogging level greatly and improving EMC performance obviously; and meanwhile, the fan drive circuit and the fan in the invention also comprise a fan voltage detection unit and a fan fault detection unit, thus facilitating voltage detection and fault identification smoothly.

The invention relates to a reset circuit, which comprises a power-on reset circuit and a power-off reset circuit, wherein the power-on reset circuit comprises a first field-effect tube, a second field-effect tube, a third field-effect tube, a first two-input NAND gate, a second two-input NAND gate, a first NOT gate, a second NOT gate, a third NOT gate, a fourth NOT gate, an OR gate, a first capacitor, a second capacitor and a buffering delay module; and the power-off reset circuit comprises fourth to tenth field-effect tubes, a fifth NOT gate and a buffering module. The reset circuit can well execute a reset function, is simple, low in cost and high in electro magnetic compatibility (EMC), can be widely used in integrated circuits, particularly integrated circuits with strict requirements on cost control such as infrared circuits, as well as most microprogrammed control units (MCUs) and circuits with high requirements on anti-interference performance and EMC performance.

The invention discloses a low-cost input anti-overvoltage protection circuit capable of real-time monitoring the magnitude of an AC input voltage and controlling on-off of a switching device in a chopper circuit through a control circuit. When the AC input voltage is increased abnormally, the control circuit can quickly detect and control the switching device in the chopper circuit to be in the on-of state, maintain the energy storage capacitor voltage, so as to quickly and effectively protect a back stage circuit, prevent an energy storage capacitor and a switch tube of the back stage circuitfrom being damaged due to high voltage, and the back stage circuit can continue to work normally. Compared with the prior art, the anti-overvoltage protection circuit of the invention is applicable to the situation and the condition that the power network voltage abnormal overvoltage can occur caused by a grounding fault, and the like, the reaction speed is high, the circuit is simple and reliable, the cost is low, the EMC performance is excellent, the design is flexible, and the protective valve value can be adjusted.

The embodiment of the invention provides a mobile terminal and a device for improving the EMC performance of a mobile terminal display screen. The device comprises a first display screen FPC which is connected to a motherboard and a display driving chip, a second display screen FPC which is arranged at the left side of the first display screen FPC, a third display screen FPC which is arranged at the right side of the first display screen FPC, first conductive films which are arranged at the upper surfaces of the first display screen FPC, the second display screen FPC and the third display screen FPC and are connected to the second display screen FPC and the third display screen FPC and a whole machine EMC shielding ground signal end, second conductive films which are arranged at the lower surfaces of the first display screen FPC, the second display screen FPC and the third display screen FPC and are connected to the second display screen FPC and the third display screen FPC and the whole machine EMC shielding ground signal end, and an EMC shielding component which is arranged under the vertical direction of the projection area of the display driving chip and is connected to the whole machine EMC shielding ground signal end, the first conductive films and the second conductive films. According to the embodiment of the invention, the EMC performance of the display screen module and a whole machine can be greatly improved.

The invention provides an optical module for solving technical problems. The technical scheme includes that the optical module comprises a circuit board, an optical chip and an optical-chip driving chip; an upper and lower metal mesh layers are arranged on the circuit board, and the metal mesh layers are grounded; a high-speed signal line is sandwiched between the metal mesh layers, and the optical chip and the optical-chip driving chip are electrically connected through the high-speed signal line; multiple metal overholes communicated with the metal mesh layers are arranged around the high-speed signal line, and the metal mesh layers and the metal overholes form a shield cage to have the high-speed signal line shielded. Two ground planes and the metal overholes are ingeniously arranged on the circuit board to form the shield cage to have the high-speed signal line shielded, leakage of electromagnetic radiation of the high-speed signal line to the outside of the circuit board can be greatly reduced, and EMC (electro-magnetic compatibility) of the optical module can be effectively improved.

The invention discloses a thin-film capacitor integrating EMC and discharge functions and a motor controller thereof. The thin-film capacitor comprises a capacitor shell with a top seal and a bottom opening, and a heat dissipation upper cover and a water cooling bottom plate which are arranged at the upper and lower ends of the capacitor shell. A heat conduction insulation pad, a laminated busbarand an X capacitor core roll are sequentially arranged in the capacitor shell from bottom to top. The laminated busbar is provided with an EMC module comprising a Y capacitor, a bleeder resistor and aPCB, the capacitor shell is filled with an epoxy packaging adhesive to package the X capacitor core roll and the EMC module, and the surface of the capacitor shell is provided with a magnetic ring for an input terminal of the laminated busbar to pass through. When the thin-film capacitor is installed in the motor controller shell, the top and the bottom of the thin-film capacitor are both provided with cooling designs, and the water channel heat dissipation surface of the motor controller shell and the air cooling heat dissipation surface of the controller upper cover can be used for double-surface cooling at the same time.

A test setup for testing a contactless digital rotary joint integrated in a device requiring data transmission between a rotating part and a stationary part, the rotary joint further comprises a transmitter and a receiver. The transmitter has a transmitter amplifier, which is coupled to a pair of transmission lines, which are terminated by a pair of terminations. The transmission lines are differential transmission lines comprising a pair of conductors which is driven by differential signals from the transmitter amplifier. The receiver has a receiver antenna comprising a pair of antenna sections which are differentially operated and feed a differential signal to the receiver amplifier. A transmitter ground and a receiver ground are coupled to a common mode signal generator generating a common mode signal. A data source is coupled to the transmitter amplifier feeding a test signal into the transmitter amplifier, and a data sink is coupled to the receiver amplifier for receiving the test signal and generating a test result value. Also disclosed is a method for adjusting a contactless data link integrated in a device requiring data transmission between a rotating part and a stationary part.

The invention relates to the technology of ultrasonic power supplies and provides constant-power power supply with a high power factor and fast response to reduce system complexity and improve detection precision. To this end, the invention provides a constant-power driving power supply based on an ARM and a multiplier and a driving method, The constant-power driving power supply comprises a firstpart which is a driving circuit including a DDS chip, an integrated PWM wave control chip and an inversion amplification circuit; a second part which is a sampling matching circuit; a third part which is a signal conditioning circuit; and a fourth part which is a micro-control module formed by an ARM microprocessor and achieving constant-power control by adjusting the frequency and the duty ratioof a PWM wave. The invention is mainly applied to the design and manufacture of ultrasonic power supplies.

The invention discloses a radio-frequency coaxial connector which is used for transmitting a radio-frequency signal, wherein the radio-frequency coaxial connector comprises an outer conductor, a base, a dielectric body and an inner conductor, wherein the dielectric body is fastened to the inside of the outer conductor; one end of the inner conductor is fixed on the outer conductor through the dielectric body; the other end of the inner conductor is located in the base; the inner conductor comprises a body, a floating part, a connecting pipe and a plurality of elastic spring wires; the body is fastened to the inside of the dielectric body; the floating part is connected with the body through the connecting pipe; two opposite ends of each elastic spring wire are respectively fixed on the body and the floating part to establish a radio-frequency signal transmission channel; the elastic spring wires elastically deform to realize the position tolerance compatibility in the horizontal direction and the height direction; the floating part is located in the base; and radial runout of the radio-frequency coaxial connector is calibrated through deflection.

The invention discloses an input overvoltage protection circuit. The circuit is capable of monitoring the size of DC voltage after the rectification of AC input voltage in real time and controlling the on/off of a switching element in a chopper circuits through a sampling circuit. When the AC input voltage is abnormally high, the sampling circuit is capable of rapidly detecting and controlling theswitching element in the chopper circuit to be located in an on/off state and freely setting an on overvoltage protection threshold value and an off overvoltage protection threshold value to maintainthe voltage size of an energy storage capacitor, so as to rapidly and effectively protecting a post circuit, prevent an energy storage capacitor and a switch tube in the post circuit from being damaged by overvoltage and enable the post circuit to continue the normal work. The input overvoltage protection circuit is suitable for the condition or occasion of three-phase four-wire AC voltage inputor single-phase AC voltage input which possibly has grounding faults to cause abnormal overvoltage of power grids, is high in reaction speed, simple and reliable in circuit, low in cost, excellent inEMC performance and flexible in design, and is capable of adjusting the on overvoltage protection threshold value and the off overvoltage protection threshold value.

The invention discloses an automatic switching system of a power supply. The system is used for automatically switching an external power supply to an emergency power supply to realize uninterrupted power supply. The automatic switching system is characterized by comprising a power supply switching circuit; the power supply switching circuit comprises an emergency power supply bt1, a fuse f200, a fuse f201, a fuse f203, a mem2313 chip, a resistor r1, a resistor r2, a resistor r3, a resistor r4, a resistor r5, a resistor r6, a resistor r7, a resistor r8, a diode d1, a diode d2, a diode d3, a diode d4, a diode d6, a diode d5, a diode d200, a diode d201, a diode d210, a diode d211, an audion q1, a capacitor c10, a capacitor c200, a capacitor c211, a capacitor c201, a capacitor c222, an inductor l200, a switch s1 and an AT89S51 single-chip microcomputer. The power supply switching system is designed, and the external power supply can be automatically switched onto the emergency power supply under the condition that the external power supply is abnormal, so that uninterrupted power supply of the system is guaranteed.

The invention discloses an optical module, and the optical module comprises a circuit board which is provided with a high-speed transmission line, wherein one end of the transmission line is connected with a drive chip. The circuit board is provided with two ground planes, which are vertically opposite to each other. The high-speed transmission line is clamped between the two ground planes. The circuit board is also provided with a plurality of metal via holes around the high-speed transmission line, and the metal via holes enable the two ground planes to be communicated, and form a shielding cage with the two ground planes, wherein the shielding cage enables the high-speed transmission line to be shielded. The optical module can greatly reduce the electromagnetic radiation emitted by the high-speed transmission line to the outside of the circuit board, and can effectively improve the EMC performance.

The present invention relates to a wind turbine with an electrical machine wherein said electrical machine comprises a stator (702) with one or more electrical winding(s) (704), said electrical winding(s) being arranged to be connected to an electrical grid (760) by at least one cable (740) with at least one phase conductor (746), the at least one cable (740) comprises at least one return path (744) to conduct leakage currents, and at least one electrical shield (745), the stator being electrically isolated from a stator housing (701). The invention also relates to a method for minimizing stray currents in an electrical machine in a wind turbine.

When a main body of a sensor chip (1) is in a grounded state, a shield layer (71) constituting a shield electrode formed on a circuit layer (72) is grounded through a resistor (46).

The invention discloses an improved pressure transmitter. A connector component of a packaging structure of the improved pressure transmitter is connected with a boiler or a pressure container or a pressure pipeline to provide a pressure source for a sensitive element. The improved pressure transmitter is connected with an outer shell through a circuit board, carries out shielding on the circuit board, and improves the EMC performance. Meanwhile, the connector component and the outer shell are packaged through a split-body riveting connecting structure, the outer shell and an electrical insertion part are connected in a riveting mode, and a corresponding seal ring, the corresponding sensitive element and the corresponding circuit board are installed in the shell body. Due to the fact the simple packaging structure is adopted, the improved pressure transmitter is simple in structure, facilitates technology adjustment, and reduces manufacturing cost.

The invention discloses a control circuit of a simple double-power-supply changeover device. The control circuit is characterized in that when a frequently-used power supply is normal, a power supplying circuit of a reserve power supply is deenergized and does not work; an N phase of the frequently-used power supply and an N phase of the reserve power supply cannot be communicated at any time, so that the misoperation of a frontend residual current circuit-breaker caused by a current current-direction imbalance phenomenon resulting from the connection of voltage of two channels is avoided. A three-phase voltage loss detection circuit of the frequently-used power supply adopts a capacitive step-down circuit to replace a transformer, wherein a phase A voltage loss detection circuit of the frequently-used power supply is doubled as a power supplying circuit of the frequently-used power supply, and a gate circuit and a timer 555 integrated circuit are adopted as a logic control circuit instead of a microcontroller. The control circuit mainly has the following advantages that the whole circuit is simple, scientific and ingenious in structure, high in reliability, good in EMC (Electro-Magnetic Compatibility) and low in power consumption; the economical efficiency is high, the cost performance is high, the manufacturing is easy, the maintenance is convenient, the maintenance cost is low, and the control circuit is energy-saving and environment-friendly, thereby having relatively great popularization value.