JPH04322175A - Voltage type inverter - Google Patents

Abstract

PURPOSE:To obtain a voltage type inverter which does not burn out a current limiting resistor even when the initial charging is conducted under the condition that a DC circuit is short-circuitted by connecting in series a fuse to a current limiting resistor of an initial charging apparatus. CONSTITUTION:An initial charging apparatus 10 connectes in series a current limiting resistor 12 and a fuse and then connects these in parallel with a switch 11. This initial charging apparatus 10 is provided between a diode converter 1 and a capacitor 2. Here, when a DC circuit, namely the capacitor 2 or an inverse converter 4 realizes initial charging under the short-circuit condition, a heavy current continuously flows into the current limiting resistor 12, but since it is cooperated with the fuse 13, the fuse 13 blows out for the protection purpose before the current limiting resistor 12 burns. Thereby, a low cost and highly reliable voltage type inverter can be obtained.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a voltage type inverter having a diode converter, and more particularly to initial charging of a capacitor provided in a DC circuit.

0002

[Prior Art] Figure 3 shows, for example, the Mitsubishi Electric Technical Report (Vol. 6).
2, No. 6, 1988) is a simplified illustration of the transistor inverter shown in FIG. 9 of "All-Digital General-Purpose Inverter FR-Z Series". In the figure, 1 is a forward converter (hereinafter referred to as a diode converter), 2 is a capacitor, 3 is an inverse converter composed of a transistor and a diode, and 30 is a conventional initial charging device.
It is composed of a switch 11 and a current limiting resistor 12.

Next, the operation will be explained. After turning on the power,
The capacitor 2 is charged through the current limiting resistor 12, and after the capacitor 2 reaches a predetermined voltage, the switch 11 is closed and the inverter 3 starts operating.

0004

[Problems to be Solved by the Invention] In the conventional voltage type inverter, the initial charging device for the capacitor 2 is configured as described above, so that if the power is turned on with the capacitor 2 or the inverter 3 short-circuited, However, since the voltage of the capacitor 2 never reaches a predetermined value, a charging current continues to flow through the current limiting resistor 12, causing the current limiting resistor 12 to burn out. Particularly in high voltage inverters, it is difficult to protect the current limiting resistor 12.

The present invention has been made to solve the above-mentioned problems, and includes an initial charging device in which the current limiting resistor does not burn out even if initial charging is performed with the DC circuit short-circuited. The aim is to obtain a voltage-type inverter with high voltage.

[0006]

[Means for Solving the Problems] A voltage type inverter according to the present invention has a fuse connected in series to a current limiting resistor of an initial charging device.

[0007]

[Operation] In the present invention, the fuse connected in series with the current limiting resistor prevents the current limiting resistor from burning out when initial charging is performed with the DC circuit short-circuited.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. In FIG. 1, 4 is an inverter composed of a GTO and a diode, and 10 is an initial charging device according to the present invention, in which a current limiting resistor 12 and a fuse 13 are connected in series, and these are connected in parallel to a switch 11. Now, diode converter 1
and capacitor 2.

Next, the operation will be explained. The normal initial charging operation is the same as that of the conventional initial charging device 30, so a description thereof will be omitted. When the DC circuit, that is, the capacitor 2 or the inverter 4, performs initial charging in a short-circuited state, a large current continues to flow through the current-limiting resistor 12, but since it is coordinated with the fuse 13, the current-limiting resistor 12 The fuse 13 is fused and protected before it burns out.

Example 2. FIG. 3 is a diagram showing another embodiment of the present invention, in which the initial charging device 20 is provided on the AC side. In the figure, the initial charging device 20 includes switches 21 and 22.
, current limiting resistors 23 and 24, and fuses 25 and 26.

[0011]

As described above, according to the present invention, since a fuse is connected in series with the current limiting resistor of the initial charging device, a highly reliable voltage type inverter can be obtained at low cost.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram of a voltage type inverter equipped with an initial charging device according to an embodiment of the present invention.

FIG. 2 is a configuration diagram of a voltage type inverter equipped with an initial charging device according to another embodiment of the present invention.

FIG. 3 is a configuration of a voltage type inverter equipped with a conventional initial charging device.

[Explanation of symbols]

1 Diode converter 2 Capacitor 3
Inverter 4 composed of transistors and diodes Inverter 10, 20 composed of GTO and diodes Initial charging device 30 according to the present invention Conventional initial charging device 11, 21, 22 Switches 12, 23, 24 Current limiting Resistor 13, 25, 26 Fuse

Claims (1)

[Claims] Claim 1: In a voltage type inverter comprising at least a forward converter composed of diodes, a self-excited reverse converter, and a capacitor in the DC circuit, a resistor is used for initial charging of the capacitor in the DC circuit. A voltage type inverter characterized by having an initial charging device formed by connecting fuses in series and connecting them in parallel to a switch.