JPH0811068Y2 - Inverter device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial field of application) The present invention relates to a wiring structure of a main circuit for suppressing a switching surge voltage generated in a switching element forming an inverse converter of an inverter device.

(Prior Art) Second example of a conventional main circuit wiring structure of an inverter device
Shown in the figure. In FIG. 2, 1 is a forward converter for converting an AC power supply into DC, 2a to 2c are smoothing capacitors for smoothing the DC output of the forward converter 1, and 3 is an inverse converter for inversely converting the DC output into an AC output. And is composed of a plurality of switching elements. Reference numerals 3a to 3c are pairs of switching elements that form the inverse converter 3, and each form one phase of the output of the inverter device. Further, 4a and 4b are main circuit DC bus bars having positive and negative potentials.

As shown in FIG. 2, the main circuit wiring of the conventional inverter device includes a forward converter 1, smoothing capacitors 2a to 2c, and switching element pairs 3a to 3c in a one-dimensional manner between a set of continuous DC buses 4a and 4b. It had a structure in which it was wired in parallel.

(Problems to be solved by the invention) In FIG. 2, the DC bus length between the switching element pair 3c and the smoothing capacitor 2c wired with the switching element pair 3c at the shortest distance is l ₁ , and similarly the switching element pair is 3b
And the DC bus length between the smoothing capacitor 2c and l _2, a DC bus length between the switching element pair 3a and the smoothing capacitor 2c and l _3,
If the DC bus length between the switching element pairs 3a-3b and between 3b-3c together with _{l 4, l 2 = l 1} + l 4 l 3 = a l ₁ + 2l _4, DC bus length of the shortest and the switching element pairs The DC busbar with the smoothing capacitor 2c connected by becomes longer by the length of the DC busbar connecting the switching element pair, and the DC busbar length up to the smoothing capacitor 2c becomes in order of the switching element pair 3c <3b <3a. There is a drawback that the inductance of the DC bus increases proportionally, and therefore the switching surge voltage generated in each switching element pair is proportional to the magnitude of the inductance and increases from 3c to 3a.

The present invention has been made to improve the above-mentioned drawbacks, and has a main circuit wiring structure that suppresses the switching surge voltage caused by the inductance of the DC bus generated in each switching element pair so as to be substantially equal. It is an object to provide an inverter device.

[Effects of the Invention] (Means for Solving Problems) The present invention is directed to a forward converter that converts an input from an AC power supply into a direct current, a plurality of smoothing capacitors that smoothes the direct current, and the smoothed direct current. Is formed by connecting each phase switching element pair and the smoothing capacitor correspondingly, and connecting them by a DC bus. In the above inverter device, the corresponding switching element pair and the connection point of the smoothing capacitor to each DC busbar are connected by a branch busbar.

(Operation) By connecting each switching element pair and smoothing capacitor that are placed in the shortest distance by the DC bus that is branched into multiple sets, the shortest wiring is possible for each switching element pair and the smoothing capacitor. Therefore, the switching surge voltage of each switching element pair due to the inductance caused by the DC bus length can be suppressed to the minimum.

(Embodiment) An embodiment of the present invention will be described below with reference to FIG. In FIG. 1, the same parts as those in FIG. 2 are designated by the same reference numerals, and the description thereof will be omitted. Also, FIGS. 1 and 2
In the figure, the arrangement of the forward converter 1, the smoothing capacitors 2a to 2c, and the switching element pairs 3a to 3c is the same. In the figure, 5a and 5b are switching element pair 3a and smoothing capacitor 2a.
Is a branch bus line branched from the DC bus lines 4a, 4b to connect with, and similarly, 6a, 6b is a DC bus line 4 for connecting the switching element pair 4b and the smoothing capacitor 2b.
It is a branch bus bar branched from a and 4b. Branch bus
5a and 5b branch from the connection point between the switching element pair 3a and the DC buses 4a and 4b, and are connected to the smoothing capacitor 2a arranged at the shortest distance from the switching element pair 3a. Branch bus
6a and 6b branch from the connection point between the switching element pair 3b and the DC buses 4a and 4b, and are connected to the smoothing capacitor 2b arranged at the shortest distance from the switching element pair 3b.

Each switching element pair 3a to 3c has an unnecessary electrical wiring length due to the wiring length between each switching element pair generated in the case of FIG. 2 which is an example of a conventional main circuit wiring structure having no branch busbar. You can avoid the increase.

In this way, each switching element pair is connected directly to the smoothing capacitor arranged at the shortest distance with respect to each switching element pair by using the branch bus, so that each switching element pair can be connected to the conventional main circuit wiring. Since the wiring length of the electric DC bus to the smoothing capacitor is shortened and the inductance is reduced, the switching surge voltage caused by the wiring length generated in each switching element pair can be suppressed to a small value.

[Effect of the Invention] According to the present invention, as is clear from the above description,
Even when a large number of switching element pairs are used, the switching element pairs that make up the inverse converter are independently connected to the smoothing capacitor placed at the shortest distance from the connection point with the DC bus, respectively, even when multiple switching element pairs are used. For the switching element pairs, it prevents unnecessary increase of the electrical DC bus length such as wiring length between each switching element pair, thus suppressing the switching surge voltage of each switching element pair caused by the inductance of the DC bus length to be small. can do.

[Brief description of drawings]

FIG. 1 is a main circuit wiring diagram showing an embodiment of the present invention.
FIG. 2 is a conventional main circuit wiring diagram. In the drawing, 1 is a forward converter, 2a to 2c are smoothing capacitors, 3 is an inverse converter, 3a to 3c are switching element pairs, 4a to 4b are DC buses, and 5a to 5b, 6a and 6b are branch buses.

Claims (1)

[Scope of utility model registration request] 1. A forward converter for converting an input from an AC power supply into a direct current, a plurality of smoothing capacitors for smoothing the direct current, and a pair of phase switching elements for converting the smoothed direct current into an alternating current and outputting the alternating current. In an inverter device formed by arranging each phase switching element pair and the smoothing capacitor respectively corresponding to each other and connecting them by a DC bus, the corresponding switching element pair and the smoothing capacitor are formed. An inverter device in which each of the connection points to the DC bus is connected by a branch bus.