Stepless and automatic voltage regulating and low-frequency low-current signal detecting circuit of variable-load phase advancer

Abstract

The invention discloses a stepless and automatic voltage regulating and low-frequency low-current signal detecting circuit of a variable-load phase advancer. The stepless and automatic voltage regulating and low-frequency low-current signal detecting circuit is characterized in that an electric network source is subjected to voltage reduction conversion via a compensation transformer; rotor current signals are sampled and detected via a Hall current sensor; voltage signals outputted by the Hall current sensor are transmitted to a filter circuit to be filtered; a trigger control circuit provides silicon-controlled rectifier triggering signals required by a rectifier circuit and an inversion circuit according to signals outputted by the filter circuit and controls on-off states of a silicon-controlled rectifier; the rectifier circuit rectifies and filters voltage formed after voltage reduction conversion of the compensation transformer; and the inversion circuit inverts direct-current voltage outputted by the rectifier circuit, outputs electric potential with the frequency the same as that of current of a rotor of a wound rotor type motor, and superposes the electric potential on the rotor of the wound rotor type motor via a phase advancing and withdrawing mechanism, so that the purpose of compensation is fulfilled.

Description

technical field [0001] The invention relates to a detection circuit, in particular to a stepless automatic voltage regulation and low frequency small current signal detection circuit in a variable load phase advancer. Background technique [0002] In our country, the load driven by large and medium-sized winding asynchronous motors used in large and medium-sized enterprises is not constant. When using variable load phase advancer for reactive power compensation, it is required that the variable load phase advancer can The level of the compensation potential is automatically adjusted according to the different conditions to achieve the purpose of accurate compensation. [0003] However, the existing variable load phase advancer adopts an AC-AC frequency conversion compensation method. Although this compensation method can automatically adjust the output potential level within a certain range, its adjustment range is limited. When the compensation potential adjustment range i...

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Problems solved by technology

[0003] However, the existing variable load phase advancer adopts an AC-AC frequency conversion compensation method. Although this compensation method can automatically adjust the output potential level within a certain range, its adjustment range is limited. In the case where the adjustment range of the compensation potential is required to be large, it is necessary to manually adjust the output AC voltage gear of the compensation transformer to meet the requirements, and the operation is troublesome.

At the same time, when the rotor Hall current sensor used in the phase advancer is running without load, that is, the frequency of the motor rotor current signal is very low and the amplitude is small, the output voltage signal is easily affected by external interference factors, resulting in The rotor current signal processed by the single-chip computer is distorted, which affects the abnormality of the SCR trigger signal output by the single-chip computer, so that the phase advancer cannot advance the phase or achieve a good compensation effect when the motor is no-load.

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