JPS63194530A - Noise filter for inverter equipment - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a filter for electromagnetic induction interference waves whose source is an inverter device.

[Conventional technology]

As a conventional noise filter of this type, one illustrated in the single-line circuit diagram of FIG. 3 is known. Sticking to Figure 3,
1 is an AC power supply, 2 is a filter circuit, and a reactor 21
and a capacitor 22. Reference numeral 3 denotes an inverter device, which includes a rectifier circuit 31, a capacitor 32, and an inverter 33. 4 is an inductive load such as an induction motor serving as a load of the inverter device 3; 5 is an AC input power supply line; and 6 is an inverter output power supply line. Adhering to the above configuration, the filter circuit 2 is configured to remove harmonics from the AC power source 1 due to input AC rectification from the AC power source 1 by the rectifier circuit 31.
Therefore, the frequency component of the harmonic to be blocked by the filter circuit 2 is determined by the frequency of the AC power source 1 and the rectification method of the rectifier circuit 31.

[Problem that the invention seeks to solve]

However, the frequency variable range of the output AC of the inverter 33 is far expanded compared to the frequency of the AC power source 1, and according to the frequency of the carrier wave for generating the inverter output AC and the carrier wave. - The harmonic frequencies generated when the input DC is switched by the converter 33 have extremely high values, and therefore, the circuit state between the AC power supply 1 and the inverter device 3 is It is not necessarily as shown in FIG. 3, but may vary depending on the stray capacitance, etc., which is affected by the shape and arrangement of the components of the inverter device 3 and the filter circuit 2, and the inverter 33 Various harmonics generated by this are induced into the electric line 5 and flow into the AC power supply 1, causing various electromagnetic induction disturbances.

In view of this, the present invention aims to provide a harmonic noise filter that prevents various harmonics generated from an inverter device from flowing out to an external circuit such as an AC power supply via the input/output circuit of the inverter device. It is something to do.

[Means for solving problems]

A low impedance circuit that targets harmful harmonics among various harmonics generated by the inverter device is provided in parallel to the inverter device as a high frequency shunt to an external circuit of the inverter device. That is, an inverter device is connected between an AC input terminal and an AC power source, and is comprised of an AC/DC converter circuit that converts input AC into the required DC, and an inverter that receives the DC output of the AC/DC converter and converts it into the required AC. a reactor connected between an AC output terminal of the inverter device and an input terminal of an inductive load of the inverter device, and a reactor connected between an AC input terminal of the inverter device and an input terminal of the inductive load. and a capacitor connected to the noise filter for an inverter device.

[Effect]

As mentioned above, in order to deal with harmful harmonics among various harmonics generated by an inverter device, a circuit with lower impedance than the coupling impedance including stray capacitance between the inverter device and its input/output circuit is constructed. The low impedance circuit is connected in parallel to the inverter device, and the low impedance circuit is actuated as a high frequency shunt for the input/output circuit of the inverter device with respect to the harmful harmonics, and the harmful harmonics are connected to the inverter device and the low impedance circuit. The harmful harmonics are prevented from flowing out to the external circuit by circulating the harmful harmonics into a closed circuit consisting of

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a single-line circuit diagram showing an embodiment of the present invention, and FIG. 2 is a single-line circuit diagram corresponding to FIG. 1 and illustrating an isometric circuit state for harmonic components whose generation source is an inverter device. In FIGS. 1 and 2, components having the same functions as those in the prior art embodiment shown in FIG. 3 are given the same reference numerals. In FIG. 1, the filter 2 on the side of the AC power source 1 of the inverter device 3 in FIG. 3 has been replaced by the filter 7 shown in FIG. The circuit shown in FIG. 1 is designed to isometrically eliminate harmonic components in the high frequency range that may cause electromagnetic induction interference among various harmonics generated by the inverter device 3. It can be converted as shown in the figure. FIG. 2 (herein, sh represents a harmonic power source in the high frequency range, and Csl and Cs2 represent the connection between the inverter device r!L3 and its input/output circuits 5 and 6, respectively, targeting the frequency band of sh). It is a wandering place between
Similarly, Cs3 is a stray capacitance corresponding to the uniformly constrained internal impedance of the harmonic power source Sh, and the capacitances Csl, Cs2, and Cs3 are all influenced by the shape and arrangement of the components of the inverter device 3 and filter 7. changes in response to Regarding the AC power supply 1, 11 indicates its internal resistance, 12 indicates its internal inductance, and regarding the inductive load 4, C41 indicates its internal resistance, 42
is inside.

In the sh frequency band, the internal reactances due to the internal inductances 12 and 42 are sufficiently large compared to the internal resistances 11 and 41, respectively. Therefore, as shown in FIG. 2, the series connection of the filter capacitor 73 and the reactor 72 is connected in parallel to the harmonic power supply circuit consisting of the power supply sh and the stray capacitance Cs3, and the stray capacitance Cs3 is Even if the capacitances Csl and Cs2 cannot be uniquely specified due to their nature, in the frequency band of the sh, the series-parallel composite impedance of the capacitance Cal, the filter flux actuator 1, and the internal impedance of the AC power supply 1, and the inductive The series combined impedance of the filter capacitor 73 and the reactor 72 is made sufficiently small with respect to both the internal impedance of the static load 4, and the 97 cotance of the reactor/l/72 is made sufficiently small compared to the reactance of the capacitance Cs2. By making it small, the series circuit of the filter capacitor 73 and the reactor 72 is connected to the circuit on the AC power supply 1 side including the electric line 5 and the inductive load 4 including the electric line 6.
A high frequency shunt is formed with respect to the harmonic power source for the circuit on the side, so that the harmful harmonic current caused by the power source Sh is transferred to the capacitor 73 of the filter 7.
The power source sh is circulated through the reactor 72 and the stray capacitor Cs3, and the harmful harmonic current is prevented from flowing to the AC power source side and the inductive load side.

Further, in FIG. 2, the direct transmission of commercial power from the AC power supply 1, which normally has a commercial frequency of 50 or 60 H2, to the inductive load circuit 4 via the reactor 71 and capacitor 73 of the filter 7 is as follows. Since the reactance of the capacitor 73 with respect to the commercial frequency becomes extremely large, it is suppressed to a practically negligible value.

〔Effect of the invention〕

According to the present invention, by adding a high frequency noise filter consisting of a reactor and a capacitor connected in series and parallel to the inverter device, harmonic currents that generate harmful electromagnetic interference from the inverter device as a source can be removed. The leakage to the AC power supply side and load side of the inverter device can be easily and inexpensively prevented.

[Brief explanation of the drawing]

FIG. 1 is a single-line circuit diagram showing an embodiment of the present invention, FIG. 2 is a single-line circuit diagram corresponding to FIG.
The figure is a single-line circuit diagram showing an embodiment of the prior art. DESCRIPTION OF SYMBOLS 1... AC power supply, 2... Filter, 3... Inverter device, 4... Inductive load, 5... Input power supply line, 6... Output power supply line, 7... Filter, 21...
・Reactor, 22... Capacitor, 31... Rectifier circuit, 32... Capacitor, 33... Inverter,
71.72...Reactor, 73...Capacitor.

Claims (1)

[Claims] 1) Connected between the AC input terminal of an inverter device and an AC power source, which consists of an AC/DC conversion circuit that converts input AC into the required DC and an inverter that receives the DC output of the AC/DC conversion circuit and converts it into the required AC. a reactor connected between the AC output terminal of the inverter device and an input terminal of the inductive load of the inverter device, and a reactor connected between the AC input terminal of the inverter device and the input terminal of the inductive load. A noise filter for an inverter device, comprising a capacitor connected between the noise filters.