JPS62250876A - Voltage type inverter unit - Google Patents

Abstract

PURPOSE:To enable load feed to be executed normally and continuously even if temporary service interruption or the like is generated on a commercial power source, by setting a storage battery in parallel with a condenser smoothing direct current for output generated from a converter. CONSTITUTION:AC power from a commercial power source 1 is converted to DC power by a converter 3. On start, contactors 6, 13 are opened, and the DC power is currentlimited by a resistance 5, and an electrolytic capacitor 4 is electrically charged or charged with a storage battery 11 through a resistance 12. When the charge of the electrolytic capacitor 4 or the storage battery 11 is completed, then the contactors 6, 13 are closed. After that, a plurality of transistors 7 are switching-worked according to a specified sequence, and the AC voltage of variable voltage and variable frequency is obtained. When temporary service interruption or voltage drop is generated on the commercial power source 1, then the storage battery 11 is discharged, and so the terminal voltage of the electrolytic capacitor 4 is prevented from being suddenly lowered.

Description

[Detailed description of the invention] [Industrial application field] This invention relates to improvements in voltage source inverter devices.

[Conventional technology]

FIG. 3 shows the configuration of the main circuit of a conventional voltage source inverter device. In the figure, 1 is a commercial power supply (3-phase AC power supply), 3 is a converter formed by connecting six diodes 2 in a bridge connection, 4 is an electrolytic capacitor, and 5 is for limiting the charging rush during the initial charging of the electrolytic capacitor 4. , 6 is a short-circuit contactor, 9 is an inverter formed by bridge-connecting six transistors 7, 8 is a diode, 1
0 is an AC load such as an electric motor.

In this voltage source inverter device, AC power from a commercial power source 1 is converted into DC power by a converter 3. At startup, the contactor 6 is opened, and the DC power is current-limited by the resistor 5 to charge the electrolytic capacitor 4. When charging of the electrolytic capacitor 4 is completed, the contactor 6 is closed. Thereafter, the plurality of transistors 7 are switched according to a predetermined sequence to obtain an alternating current voltage with a variable voltage and a variable frequency.

[Problem that the invention seeks to solve]

In this conventional voltage source inverter device, if a momentary power outage or voltage drop occurs in the commercial power source 1, the voltage of the electrolytic capacitor 4 will suddenly drop and the inverter 9 will lose its normal operation. When the voltage decreases by 15% to 20%, the operation of the inverter 9 is instantly stopped to protect the inverter. For this reason, there was a problem in that the reliability was insufficient and the AC load 10 could not be applied to the type of AC load that does not like instantaneous power outages or voltage drops.

This invention was made in order to solve the above-mentioned conventional problems, and aims to provide a highly reliable voltage source inverter device that can continue to normally supply load power even if a momentary power outage occurs in the commercial power supply. purpose.

[Means to solve the problem]

In order to achieve the above object, this invention provides a storage battery in parallel with a capacitor.

[Effect]

In this invention, when a momentary power outage occurs in the commercial AC power source and the power supply from the commercial power source is cut off, power is automatically supplied from the storage battery, so that operation can be continued as is.

[Embodiments of the invention]

FIG. 1 shows an embodiment of the present invention, in which a storage battery 1) is inserted between the DC output terminals of a converter 3 via a current-limiting resistor 12, and a contactor 13 is connected in parallel to the resistor 12. It differs from the conventional one shown in FIG. 3 in that it is Since the other configurations are the same as those in FIG. 3, the same reference numerals are given and the explanation thereof will be omitted.

In this configuration, AC power from commercial power source 1 is converted to DC power by converter 3. At startup, the contactors 6 and 13 are opened, and the DC power is limited by the resistor 5 to charge the electrolytic capacitor 4.
Also, the storage battery 1) is charged through the resistor 12. When charging of the electrolytic capacitor 4 and storage battery 1) is completed, contact lenses and 13 are closed. Thereafter, the plurality of transistors 7 are switched according to a predetermined sequence to obtain an alternating current voltage with a variable voltage and a variable frequency.

When a momentary power outage or voltage drop occurs in the commercial power supply 1, the storage battery 1) is discharged, which prevents a sudden drop in the terminal voltage of the electrolytic capacitor 4, and allows the inverter 9 to continue operating normally. It becomes possible.

The above embodiment deals with a case where there is only one voltage source inverter device, but when multiple voltage source inverters are operated in parallel, one voltage source inverter device is commonly used for each voltage inverter device, as shown in Fig. 2. A storage battery 1) may be provided. In FIG. 2, a charger 15 charges a storage battery 1), and the output terminal of the storage battery 1) is connected between the DC terminals of the inverter 9 in each voltage type inverter via a contactor 13 and a diode 14. ing.

〔Effect of the invention〕

As explained above, even if there is a momentary power outage or a large voltage drop in the commercial power supply, this invention automatically starts power supply from the storage battery, ensuring normal operation of the inverter, compared to conventional methods. can improve reliability.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram showing an embodiment of the present invention, FIG. 2 is a circuit diagram showing another embodiment of the invention, and FIG. 3 is a circuit diagram showing a conventional voltage source inverter device. In the figure, 1 - commercial power supply, 3 - converter, 4 - electrolytic capacitor, 9 - inverter, 1) - storage battery, 13 - contactor, 15 - charger. In addition, in the figures, the same reference numerals indicate the same or corresponding parts.

Claims (2)

[Claims] (1) In a voltage source inverter device that includes a converter that converts commercial power to DC, a capacitor that smoothes the DC output from the converter, and an inverter that converts the smoothed DC to AC, a storage battery is installed in parallel with the capacitor. A voltage source inverter device comprising: (2) The voltage source inverter device according to claim 1, wherein the storage battery is common to a plurality of voltage source inverter devices.