JP2002345258A - Inverter device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inverter device capable of performing initial charging of a main circuit capacitor (filtering capacitor) at a low cost and with high power efficiency. SOLUTION: A third winding is provided on a main transformer 2 installed on the input side of the inverter device. A commercial power supply 1 is applied to the filter capacitor C of the inverter device 30 through the third winding for initial charging.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an inverter device for initially charging a main circuit capacitor (smoothing capacitor) of an inverter device including a multiplex inverter device.

[0002]

2. Description of the Related Art A conventional inverter device is disclosed in
FIGS. 8 and 9 show an example configuration described in JP-A-00-50636.

In FIGS. 8 and 9, when performing initial charging, the smoothing capacitor 32 is initially charged by controlling the initial charging thyristor and the initial charging relay in the unit cells 31 to 39. That is, when the main switch 11 is turned on,
First, the smoothing capacitor 3 is connected via the current limiting resistor R13.
Charge 2. When a time several times as long as C · R elapses, the voltage becomes sufficient, and then the thyristor 14 (or relay) is turned on. In this case, each of the unit cells 31 to 3
9, the first charge control is performed.

[0004]

In the prior art, the cost (the cost of parts for the main circuit, the cost of wiring and the cost of parts for the control circuit and the cost of wiring) is always higher than the number of unit cells. Since the number is large, there is a problem that the burden increases. For example, in the case of the multiplex inverter shown in FIGS. 8 and 9, since there are nine unit cells, the cost is increased nine times and the cost is large.

Further, a thyristor causes a loss due to a voltage drop, so a relay is used instead. However, the relay has a dimensional difficulty in mounting in a unit cell, and also has a problem that the whole device becomes large. is there.

An object of the present invention is to provide an inverter device which can perform initial charging of a main circuit capacitor (smoothing capacitor) at low cost and with high power efficiency.

[0007]

A feature of the present invention is that a third winding is provided on a main transformer installed on the input side of an inverter device, and a commercial power supply is supplied via the third winding. That is, the voltage is applied to the smoothing capacitor of the inverter device to perform initial charging.

[0008]

FIG. 1 shows an embodiment of the present invention.
FIG. 2 shows an example of the inverter unit 30.

One embodiment shown in FIGS. 1 and 2 will be described in detail with reference to a time chart of FIG.

FIG. 1 shows an embodiment corresponding to claim 1, wherein a commercial AC power supply 1, a main switch 11, an auxiliary switch 12, a current limiting resistor (R) 13, a three-phase input side main transformer 2 and a three-phase Inverter unit 30 and three-phase AC motor (ACM) 4
It is composed of

FIG. 2 shows details of the three-phase inverter unit 30.
Shown in

The three-phase inverter unit 30 converts the three-phase AC power 103 into a variable frequency three-phase voltage 104 and outputs the same. That is, first, the three-phase AC power supply 103 is converted into a DC voltage (Vdc) 105 by the three-phase full-wave diode rectifier 31, and the DC voltage (Vdc) 105 is smoothed by the capacitor (C) 32.

The DC voltage (Vdc) 105 smoothed by the capacitor (C) 32 is converted by the transistor inverter 33 into 3
The electric motor (ACM) 4 is driven at a variable speed with the output voltage after being converted into the phase variable frequency output voltage 104 and output.

The initial charging of the smoothing capacitor (C) 32 in the three-phase inverter unit 30 will be described with reference to a time chart of FIG.

The initial charge is to store the voltage in the smoothing capacitor 32 before starting the operation of the three-phase inverter 30. If the main switch 11 is turned on without performing this operation, the non-voltage smoothing capacitor (C This is to prevent the commercial AC power supply 1 from being short-circuited at 32 and causing an excessive current to flow to damage the equipment.

The time at which the main switch 11 is turned on is t1
And At time t0 before this time t1, the auxiliary switch 12 is turned on. As a result, the power supply voltage is applied to the tertiary winding of the main transformer 2 and the DC voltage (Vd) is applied to the capacitor (C) 32 in the three-phase inverter unit 30 via the secondary output winding.
c) Charge 105. At this time, the current limiting resistor (R) 1
3, the current flowing into the smoothing capacitor (C) 32 is limited, so that an excessive current can be suppressed. In the normal operation state, the third winding is not used, and the resistance loss due to the current limiting resistor (R) 13 does not occur.

FIG. 4 shows an embodiment in which the present invention is applied to a multiplex inverter, and FIG. 5 shows an example of an inverter unit 30. 4 and 5 show an implementation corresponding to claim 2. FIG.

The embodiment shown in FIGS. 4 and 5 will be described in detail with reference to the time chart of FIG.

In FIG. 4, the multiplex inverter includes a commercial AC power supply 1, a main switch 11, an auxiliary switch 12, a current limiting resistor (R) 13, a three-phase input main transformer 2, a three-phase inverter unit 30, and a three-phase inverter. It comprises an AC motor (ACM) 4.

FIG. 5 shows details of the unit cells 41 to 49 of the three-phase inverter unit 30.

The three-phase inverter unit 30 converts the three-phase AC power supply 103 into a variable frequency three-phase voltage 104 and outputs it. The three-phase AC power supply 103 is supplied to the three-phase full-wave diode rectifier 31 in each of the unit cells 41 to 49 by a DC voltage (Vdc)
The DC voltage (Vdc) 105 is smoothed by the capacitor (C) 32. Smoothed DC voltage (V
dc) 105 is each of the unit cell inverters 41 to 49 and further includes a single-phase variable frequency voltage (U11 to 13, V11 to V11).
3, W11 to 13) are converted into 106, and then the three-phase variable AC voltage 10 obtained by serially adding the single-phase variable frequency voltage is added.
4 and drives a three-phase AC motor (ACM) 4.

Although the embodiment of FIG. 1 is a single-stage inverter, the embodiment of FIG. 3 has a multiplexed configuration of three stages per phase, so that a high-voltage three-phase variable AC output voltage 104 can be obtained. it can.

The need for initial charging of the smoothing capacitor (C) 32 in the multiplex inverter is the same as in FIG. That is, when viewed from the primary winding of the three-phase input main transformer 2, all inverters are inserted in parallel.

If the main switch 11 is turned on without operating the smoothing capacitor 32 to store the voltage before starting the operation of the three-phase inverter, the commercial AC power supply 1 is short-circuited by the non-voltage smoothing capacitor (C) 32. Become
Excessive current may flow and damage the equipment.

The operation of initially charging the smoothing capacitor (C) 32 will be described with reference to FIG. The time at which the main switch 11 is turned on is defined as t1. At t0 before this t1, the auxiliary switch is turned on. As a result, 3 of the main transformer 2
The capacitor (C) 3 in the unit cells 41 to 49 of the three-phase inverter unit 30 is transferred from the secondary winding via the secondary winding.
2 is charged with a DC voltage (Vdc) 105. At this time, the smoothing capacitor (C) 32 is controlled by the current limiting resistor 13R.
The current flowing into the circuit is limited, and an excessive current is prevented from flowing.

FIG. 7 shows an embodiment in which the present invention is applied to a general multiplex inverter. FIG. 7 shows an embodiment corresponding to the third aspect.

In FIG. 7, the power source to be initially charged is not the commercial power source but another arbitrary AC power source 3. In this case, the function of the initial charging can be easily obtained by changing the turns ratio of the third winding of the three-phase input main transformer 2 to a predetermined value. The current limiting resistor R13 may have any function other than the resistor as long as it can limit the current. For example, it is possible to use an inductance, an active current limiter, or a short-circuit reactance of a tertiary winding set larger. it can.

The initial charge is performed in this manner. Since the initial charge control thyristor in each unit cell can be eliminated, the power loss generated from the voltage drop of the thyristor element can be eliminated, and the efficiency of the entire apparatus can be reduced. Can be improved, the total wiring man-hour of the device can be reduced, and the cost of the entire device can be reduced.

Also, since the thyristor for initial charge control or the relay for initial charge control in each unit cell can be omitted, the main circuit of the thyristor or relay part and the on / off gate wiring of the thyristor gate or the on / off of the relay are provided. Since the coil wiring can be deleted, the wiring man-hour is reduced.

Furthermore, since the initial charge control thyristor element or the initial charge control relay in each unit cell can be eliminated, the cost of parts can be reduced.

[0031]

As described above, according to the present invention, the initial charge control thyristor in each unit cell can be eliminated, and the power loss generated from the voltage drop of the thyristor element can be eliminated, so that the efficiency of the entire apparatus can be reduced. Can be improved,
In addition, the total wiring man-hour of the apparatus can be reduced, and the cost of the entire apparatus can be reduced. When the present invention is used in a multiplex inverter device, its efficiency becomes remarkable.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing one embodiment of the present invention.

FIG. 2 is a configuration diagram of an example of a unit inverter cell in the embodiment of FIG.

FIG. 3 is a time chart for explaining the operation of the embodiment of FIG. 1;

FIG. 4 is a configuration diagram showing another embodiment of the present invention.

FIG. 5 is a diagram showing an example of a configuration of a unit inverter cell in the embodiment of FIG. 4;

FIG. 6 is a time chart for explaining the operation of the embodiment in FIG. 4;

FIG. 7 is a configuration diagram showing another embodiment of the present invention.

FIG. 8 is an example configuration diagram of a conventional device.

FIG. 9 is a configuration diagram of an example of a unit inverter cell of a conventional device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Commercial AC power supply 2 ... 3 phase input side main transformer 3 ... Another arbitrary AC power supply 4 ... 3 phase AC motor (ACM) 11 ... Main switch 12 ... Auxiliary switch 13 ... Current limiting resistor (R) 30 ... Three-phase inverter unit 31 Three-phase full-wave diode rectifier 32 Capacitor (C) 33 Transistor inverter 41-49 Unit cell 103 Three-phase AC power supply 104 Variable frequency three-phase voltage 105 Direct voltage (Vdc) 106 Single-phase variable frequency voltage

Claims (3)

[Claims] 1. An inverter device for generating a predetermined variable frequency power supply from a commercial power supply, wherein a third winding is provided on a main transformer installed on an input side of the inverter device, and the commercial power supply is connected to the third winding. An inverter device characterized in that it is applied to a smoothing capacitor of the inverter device via a line to perform initial charging. 2. An input-side main transformer having a plurality of (n-phase xm-stage) secondary windings and n-stage m-stage inverter cells is connected to output n-phase variable frequency power from a commercial power supply. In the multiplex inverter device, a third winding is provided on the input side main transformer, and the commercial power is applied to the main circuit capacitor of the unit inverter cell via the third winding to perform initial charging. An inverter device, characterized in that: 3. An inverter device for generating a predetermined variable frequency power supply from a commercial power supply or an arbitrary frequency power supply,
A third winding is provided on a main transformer installed on the input side of the inverter device, and the commercial power supply or an arbitrary frequency power supply or another power supply is connected to the main circuit of the inverter device via the third winding. An inverter device characterized in that it is applied to a capacitor to perform initial charging.