JP2004032998A - Inverter device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inverter device for performing an initial charge of a main circuit capacitor (a smoothing capacitor) at a low cost and with a good electric power efficiency. <P>SOLUTION: A third winding is provided in a main transformer 2 installed at an input side of the inverter device 30 and a commercial power supply 1 is applied onto the smoothing capacitor C of the inverter device 30 via the third winding to perform the initial charge. <P>COPYRIGHT: (C)2004,JPO

Description

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.

FIGS. 8 and 9 show an example configuration of a conventional inverter device described in JP-A-2000-50636.

In FIGS. 8 and 9, in performing the 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 32 is charged via the current limiting resistor R13. 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, initial charge control is performed in each of the unit cells 31 to 39.

The conventional technology always costs as many as the number of unit cells (component cost and wiring cost of the main circuit and component cost and wiring cost of the control circuit). Especially, in the case of a multiplex inverter, the number of unit cells is large, so the burden is large. Problem. 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.

サ イ Also, 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.

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

A feature of the present invention is that a third winding is provided on a main transformer installed on the input side of the inverter device, and commercial power is applied to the smoothing capacitor of the inverter device via the third winding. The reason is that initial charging is performed.

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

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

一 One embodiment shown in FIGS. 1 and 2 will be described in detail with reference to the 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 a three-phase AC motor (ACM) 4.

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

(3) The three-phase inverter unit 30 converts the three-phase AC power 103 into a variable frequency three-phase voltage 104 and outputs it. 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 into a three-phase variable frequency output voltage 104 by the transistor inverter 33 and output, and the motor (ACM) 4 is driven at a variable speed by the output voltage.

(4) 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 charging is to store the voltage in the smoothing capacitor 32 in advance before the operation of the three-phase inverter 30 is started. If the main switch 11 is turned on without performing this operation, the smoothing capacitor (C) 32 with no voltage is used. This is to prevent the commercial AC power supply 1 from being short-circuited, causing an excessive current to flow and damaging the equipment.

時刻 The time when the main switch 11 is turned on is set to t1. 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 capacitor (C) 32 in the three-phase inverter unit 30 is charged with the DC voltage (Vdc) 105 via the secondary output winding. At this time, the current flowing into the smoothing capacitor (C) 32 is limited by the current limiting resistor (R) 13, so that an excessive current can be suppressed. In the normal operation state, the third winding is not used, and no resistance loss due to the current limiting resistor (R) 13 occurs.

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

一 One 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 AC motor ( ACM) 4.

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

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

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

も Even in a multiplex inverter, the smoothing capacitor (C) 32 needs to be initially charged 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 the operation of storing the voltage in the smoothing capacitor 32 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. In such a case, an excessive current may flow to 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. Thereby, the DC voltage (Vdc) 105 is charged from the secondary winding to the capacitor (C) 32 in the unit cells 41 to 49 of the three-phase inverter unit 30 via the tertiary winding of the main transformer 2. At this time, the current flowing into the smoothing capacitor (C) 32 is limited by the current limiting resistor 13R, 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 initial charging function 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.

Initial charging is performed in this manner. However, 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, so that the efficiency of the entire apparatus 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.

Further, since the thyristor for initial charge control or the relay for initial charge control in each unit cell can be deleted, the main circuit of the thyristor or relay part and the thyristor gate on / off gate wiring or the relay on / off coil wiring are provided. Wiring man-hours can be reduced because they can be deleted.

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.

FIG. 1 is a configuration diagram showing one embodiment of the present invention. FIG. 2 is an example configuration diagram of a unit inverter cell in the embodiment of FIG. 1. 3 is a time chart for explaining the operation of the embodiment of FIG. FIG. 9 is a configuration diagram showing another embodiment of the present invention. FIG. 5 is an example configuration diagram of a unit inverter cell in the embodiment of FIG. 5 is a time chart for explaining the operation of the embodiment in FIG. FIG. 9 is a configuration diagram showing another embodiment of the present invention. It is an example block diagram of a conventional apparatus. It is an example block diagram of the unit inverter cell of the conventional apparatus.

Explanation of reference numerals

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 inverters 41-49 ... unit cell 103 ... 3-phase AC power supply 104 ... variable frequency 3-phase voltage 105 ... DC voltage (Vdc)
106: Single-phase variable frequency voltage

Claims (3)

In an inverter device that generates a predetermined variable frequency power supply from a commercial 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 is supplied via the third winding. An inverter device, wherein an initial charge is performed by applying the voltage to a smoothing capacitor of the inverter device. In a multiplex inverter device for connecting an input main transformer having a plurality of (n-phase xm stages) secondary windings and n-stage unit inverter cells to output n-phase variable frequency power from a commercial power supply, 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. Inverter device. In an inverter apparatus 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 apparatus, and the commercial power supply or the arbitrary frequency power supply or An inverter device, wherein another power source is applied to a main circuit capacitor of the inverter device via the third winding to perform initial charging.

Images