47results about How to "Suppression of high frequency interference" patented technology

The invention discloses a signal subdividing method for a sine-cosine encoder. The method comprises the following steps of: sampling two paths of output signals, with a phase difference of 90 degrees, of a sine-cosine analogue signal to obtain sampling values A and B of the sine-cosine analogue signal; judging a quadrant with an angle Theta according to the sampling values A and B, specifically determining the angle Theta is in a first quadrant if A and B are both more than 0, determining the angle Theta is in a second quadrant if A is more than 0 and B is less than 0, determining the angle Theta is in a third quadrant if A and B are both less than 0 and determining the angle Theta is in a fourth quadrant if A is less than 0 and B is more than 0; subdividing the sine-cosine analogue signal according to a subdividing factor, setting hysteresis intervals at subdividing points, recording output values corresponding to each subdividing point in the range of 0 to 45 degrees and keeping theoutput value in the hysteresis intervals invariable; and looking up a table and outputting values 0 and 1 according to the quadrant with the angle Theta, a relative difference of absolute values of the sampling values and a tangent.

The invention relates to a method and a system for randomly switching alternating current. The system comprises a voltage detecting circuit, a current detecting circuit, a first switching circuit, a second switching circuit, a control circuit, a pulse width modulator (PWM) and an APFC circuit, wherein the first switching circuit is used for switching on or off a main power supply; the second switching circuit is used for switching on or off a reserve power supply; the control circuit is used for controlling the first switching circuit and the second switching circuit to switch on or off and transmitting a pulse signal to the PWM; the PWM is used for modulating an output dutyfactor according to the pulse signal transmitted by the control circuit; the APFC circuit is used for receiving the output dutyfactor of the PMW so as to control the output current, and thereby the linear rectification of the output current is realized to ensure the synchronization of the output voltage and the current phase of the APFC circuit. The state of the power supply can be automatically recognized by adopting the random switching so as to adapt to power supplies in different environments, and the switching time is greatly reduced and fixed. The current linear rectification can be randomly switched as alternating current to solve the peak interference brought by the random switching, and the power compensation is carried out to realize the minimum loss of circuit power.

The invention provides a power supply module for a mine safety monitoring sensor, and the module is integrally encapsulated by using epoxy resins. The power supply module includes a soft-start circuit, an anti-interference processing circuit, a first power output circuit and a second power output circuit. A power input end of the soft-start circuit is connected with a DC9-24.5V power supply when in use. A power input end of the anti-interference processing circuit is connected electrically with a power output end of the soft-start circuit. A power input end of the first power output circuit and the power input end of the second power output circuit are both connected electrically with a power output end of the anti-interference processing circuit. The power input end of the anti-interference processing circuit is the power output end thereof. A power output end of the first power output circuit outputs a +3V DC power supply. A power output end of the second power output circuit outputs a +5.5V DC power supply. The invention is applicable to the mine safety monitoring sensor, can effectively improve the anti-electromagnetic and anti-interference capabilities of the sensor, and solves the problem of proneness to restart when the sensor is under interference.

The invention belongs to the technical field of harmonic treatment, and provides a harmonic suppression circuit for an electromagnetic compatibility laboratory and a compensation method thereof. The circuit and the method thereof adopt two-stage tandem type active power filters connected in series in the forward direction, and a dry-type iron core reactor is connected in parallel between the tandem type active power filters and the power source end of a load. The dry-type iron core reactor is mainly used for restraining high-frequency interference with a frequency higher than 10 KHz, cannot influence the filter performance of the tandem type active power filters, is the major support equipment of a reactive compensation device in an electric system, can effectively restrain higher harmonic, limits the switching-on flashy current and switching overvoltage, improves the voltage waveform of the system, increases the power factor, and plays a greater function for the safe operation of a power capacitor and other electric equipment. Therefore, the dry-type iron core reactor connected in parallel connection guarantees the safe operation of other equipment in the electromagnetic compatibility laboratory, voltage change of inlets of all loads can be compensated, the detection reliability and accuracy in electromagnetic compatibility of the product can be improved.

The present invention relates to an EEG acquisition system, comprising an EMC protection circuit (100), used for receiving physiological signals on the surface of the forehead of a human body in real time, and converting the physiological signals into current signals; an instrument amplifier, used for receiving the processed EMC protection circuit the current signal, and amplify the current signal; the signal amplification circuit (200), is used to receive the current signal amplified by the instrumentation amplifier, and amplify the current signal again, so that the signal-to-noise ratio is further improved; AC coupling The circuit (300) is used to receive the re-amplified current signal, perform high-pass filtering and then couple to the instrument amplifier to form a coupling loop with high-pass filtering function. The invention enhances the stability of EEG signal acquisition, reduces the overall noise level, and greatly improves the signal-to-noise ratio of the overall acquisition circuit.