CN217216361U

CN217216361U - Filter circuit for reducing capacity of relay

Info

Publication number: CN217216361U
Application number: CN202220352682.2U
Authority: CN
Inventors: 何树全; 武有强; 胡映娇; 杨浩; 邓仕方
Original assignee: Chengdu Shenlan High Technology Development Co ltd
Current assignee: Chengdu Shenlan High Technology Development Co ltd
Priority date: 2022-02-22
Filing date: 2022-02-22
Publication date: 2022-08-16
Anticipated expiration: 2032-02-22

Abstract

The utility model provides a reduce filter circuit of relay capacity relates to power electronics technical field, especially relates to the filtering technology in converter major loop. The filter circuit comprises a charging resistor R, a relay K, a capacitor C1 and a capacitor C2. After being connected in parallel with the charging resistor R, the relay K is connected in series with the capacitor C1 and the capacitor C2 to form a filter branch circuit, one end of the filter branch circuit is connected with the direct current + end of the rectifying circuit and the direct current P end of the inverter circuit, and the other end of the filter branch circuit is connected with the direct current-end of the rectifying circuit and the direct current N end of the inverter circuit. When the frequency converter normally works, the relay only flows through the ripple current of the filter capacitor, and the ripple current is much smaller than the current of the main loop, so that the capacity of the relay can be reduced more, and the cost of the relay is reduced.

Description

Filter circuit for reducing capacity of relay

Technical Field

The utility model relates to a power electronic technology field especially relates to the filtering technology in converter major loop.

Background

In a conventional filter circuit of a main loop of a frequency converter, a charging resistor and a relay of a filter capacitor are connected in parallel and then connected in series between a direct current + end of a rectifier circuit and a direct current P end of an inverter circuit, and two filter capacitors are connected in series and then connected in parallel at the direct current P end and the direct current N end of the inverter circuit. Before the frequency converter is electrified, the relay is in a disconnected state. After the frequency converter is electrified, the direct current output by the rectifying circuit charges the two filter capacitors connected in series through the charging resistor, after the charging is finished, the relay is closed, the charging resistor is in short circuit, and the frequency converter enters a normal working state. Because the load current of all inverter circuits flows through the relay when the frequency converter works normally, the capacity of the relay is usually larger, and the cost is higher.

Disclosure of Invention

In order to reduce the relay capacity, realize the reduction of cost, the utility model provides a reduce the filter circuit of relay capacity.

Reduce relay capacity's filter circuit includes charging resistor R, relay K, electric capacity C1, electric capacity C2. After the relay K is connected with the charging resistor R in parallel, the relay K is connected with the capacitor C1 and the capacitor C2 in series to form a filter branch, one end of the filter branch is connected with the direct current + end of the rectifying circuit and the direct current P end of the inverter circuit, and the other end of the filter branch is connected with the direct current-end of the rectifying circuit and the direct current N end of the inverter circuit.

Drawings

Fig. 1 is the filter circuit schematic diagram for reducing the capacity of the relay.

Fig. 2 is a schematic diagram of a conventional filter circuit of a frequency converter.

Detailed Description

With reference to the above drawings, the filter circuit of the present invention has the following specific embodiments:

with reference to fig. 2, in a conventional filter circuit of a main loop of a frequency converter, a charging resistor of a filter capacitor and a relay are connected in parallel and then connected in series between a dc + terminal of a rectifier circuit and a dc P terminal of an inverter circuit, and two filter capacitors are connected in series and then connected in parallel to the dc P terminal and the dc N terminal of the inverter circuit. Before the frequency converter is electrified, the relay is in a disconnected state. After the frequency converter is electrified, the direct current output by the rectifying circuit charges the two filter capacitors connected in series through the charging resistor, after the charging is finished, the relay is closed, the charging resistor is in short circuit, and the frequency converter enters a normal working state. Because the load current of all inverter circuits flows through the relay when the frequency converter works normally, the capacity of the relay is usually larger, and the cost is higher.

With reference to fig. 1, after the relay K is connected in parallel with the charging resistor R, the relay K is connected in series with the capacitor C1 and the capacitor C2 to form a filter branch, one end of the filter branch is connected to the dc + end of the rectifier circuit and the dc P end of the inverter circuit, the other end of the filter branch is connected to the dc-end of the rectifier circuit and the dc N end of the inverter circuit, and the relay is in a disconnected state before the frequency converter is powered on. After the frequency converter is electrified, the direct current output by the rectifying circuit charges the two filter capacitors connected in series through the charging resistor, although the direct current plus end of the rectifying circuit is also connected with the direct current P end of the inverter circuit at the same time, the frequency converter does not work normally during charging, a switching device of the inverter circuit is in a disconnected state, and the direct current has no influence. After charging, the relay is closed, the charging resistor is in short circuit, the frequency converter enters a normal working state, the ripple current of the filter capacitor only flows through the relay at the moment, and is much smaller than the current of the main loop, so that the capacity of the relay can be reduced more, and the cost of the relay is reduced.

The above description is only an application example of the present invention in the frequency converter, and not to limit the patent scope of the present invention, and all equivalent changes made by using the contents of the present specification and the accompanying drawings should be included in the patent protection scope of the present invention, and the equivalent changes include but not limited to the charging resistor R being connected in series or in parallel by a plurality of resistors, the relay K being connected in series or in parallel by a plurality of relays, 2 capacitors C1, C2 being reduced to 1 capacitor or being connected in series or in parallel by a plurality of capacitors.

Claims

1. A filter circuit for reducing the capacity of a relay comprises a charging resistor R, a relay K, a capacitor C1 and a capacitor C2, and is characterized in that: after being connected in parallel with the charging resistor R, the relay K is connected with the capacitor C1 and the capacitor C2 in series to form a filter branch, one end of the filter branch is connected with a direct current + end of the rectifying circuit and a direct current P end of the inverter circuit, and the other end of the filter branch is connected with a direct current-end of the rectifying circuit and a direct current N end of the inverter circuit.