Device for eliminating current wave distortion in AC magnetic field when starting and stopping

Abstract

The invention discloses a device for eliminating current wave distortion in an alternating current magnetic field when starting and stopping, which comprises a distribution network power supply, an autotransformer, a bidirectional thyristor, a current booster and an induction coil connected in sequence, and a phase acquisition module connected to the output end of the autotransformer; a voltage acquisition module is connected to the output end of the autotransformer, the phase acquisition module and the voltage acquisition module are arranged in parallel, and the respective output ends of the phase acquisition module and the voltage acquisition module are Connected to the logic control module, an external control module for receiving external instructions is connected to the logic control module, and a control electrode for amplifying the control signal of the thyristor is arranged between the logic control module and the control pole of the bidirectional thyristor. A thyristor drive module, an auxiliary power supply connected to the thyristor drive module. The silicon controlled rectifier used to turn on and turn off the output current in the present invention turns on and turns off the AC sine wave current at 0 degrees and 180 degrees, and the waveform of the current starts and ends at 0 degrees or 180 degrees, so that turning on and off The current does not produce a large amount of current change when it is off.

Description

technical field [0001] The invention relates to the technical field of power frequency magnetic field immunity test, in particular to a device for eliminating current wave distortion in an AC magnetic field when starting and stopping. Background technique [0002] The existing power frequency magnetic field generating device conforming to IEC61000-4-8 and GB / T 17626.8 is random in phase when the AC current injected into the induction coil is turned on and off. If it is not turned on and off near 0 degrees and 180 degrees, and the load induction coil impedance of the current source is very small, there will be the following problems: [0003] 1. A large di / dt change rate, which is much higher than the di / dt change rate under power frequency, the strength of the power frequency magnetic field interference test depends on this change rate, which is equivalent to the beginning and end of the test An additional magnetic field strength much larger than the normal test is generate...

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Problems solved by technology

[0005] 3. Because of the inductive load of the inductive coil, the sharp rise and fall of current changes will cause overshoot / undershoot, which will cause waveform distortion and increase the severity of the test.

[0006] 4. Due to the existence of small parasitic capacitance, it will cause high-frequency oscillation of the current waveform under transient excitation

[0007] 5. If a mechanical switch is used to control on-off, electric sparks and electric arcs will be generated, resulting in instantaneous and instantaneous strong electromagnetic field radiation, which increases additional interference sources that are not related to the test, and the life of the mechanical switch is reduced due to electric sparks and electric arcs. short

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