JPS62217865A - Three-phase power receiving type inverter unit - Google Patents

Abstract

PURPOSE:To separate rectified voltage and smoothing DC voltage from each other and enable a device to be exactly protected from the abnormal state of an input power source if any, by providing one end of the output of a rectifier diode group, with a blocking diode, and by connecting the diodes to a smoothing condenser. CONSTITUTION:The AC voltage of input provided by a three-phase AC power source 4 is full-wave-rectified by a rectifier diode 1 group, and is fed to a smoothing condenser 2 via a blocking diode 9. Smoothed rectified voltage is fed to a motor 5 via an inverter section 3. In the meantime, from the output of the rectifier diode 1 group, rectified voltage is fed to a switching power circuit 6. The output voltage of the switching power circuit 6 is smoothed by a smoothing circuit 7, and when the smoothed voltage comes to a specified or less value, then the inverter section 3 is stopped by a reset circuit 8.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a three-phase power receiving type inverter device.

In particular, the present invention relates to a circuit suitable for detecting input voltage abnormality such as missing one phase and stopping inverter operation in an inverter device used to drive a compressor of an air conditioner or the like.

[Conventional technology]

Conventional main phase power receiving type inverter devices do not include a circuit for preventing phase loss due to poor connection between the three-phase AC power source and the power source side of the rectifier circuit. An example of this type of device is Utility Model Publication No. 57-49599. Further, a conventional device equipped with an open-phase prevention circuit is shown in FIG. In this device, a phase loss prevention relay 10 is provided on the input side of a three-phase AC power source to detect phase loss in the primary voltage caused by a poor connection on the input side of the power source.

[Problem that the invention seeks to solve]

Those not equipped with the circuit for preventing phase loss mentioned above.

There was a problem in that the system did not prevent operation in the event of an open phase, but instead operated with two phases. In addition, when an open phase prevention relay]O is provided, the input current of the inverter device flows, resulting in a large-scale installation, which poses a problem of installation space and an increase in cost.

An object of the present invention is to provide an inverter device equipped with a phase loss prevention circuit that does not require a large scale.

[Means for solving problems]

The above purpose is achieved by installing a blocking diode at one end of the output of the rectifier diode group and connecting it to a smoothing capacitor.
This is achieved by stepping down the rectified voltage using a switching power supply and inputting it to the reset circuit after smoothing, which makes it easy to distinguish between rectified voltage and smoothed DC voltage because it prevents reverse current due to discharge of the smoothing capacitor. be done.

[Effect]

The rectified voltage separated by the blocking diode becomes a DC voltage with little ripple during normal three-phase balanced human power, but when one phase is missing, it becomes the same as a single-phase full-wave rectified output, producing a large ripple voltage.

This rectified voltage is received and stepped down, and the control voltage of the inverter section is set to 1! ), the input voltage is approximately 50%
When this happens, oscillation is stopped, and in the case of an open-phase input, the control voltage stops coming out near the zero cross and the reset takes longer, preventing operation in an open-phase state.

〔Example〕

An embodiment of the present invention will be described below with reference to FIGS. 1, 2, and 3. FIG. 1 is a block diagram of a control circuit according to the present invention. The AC voltage input from the three-phase AC power supply 4 is rectified by a group of rectifying diodes, and is supplied to the smoothing capacitor 2 via a blocking diode 9. The smoothed rectified voltage is supplied to the inverter unit 3 as a DC voltage, converted into AC by appropriate switching, and output to the motor 5. On the other hand, since the side force voltage from the output of the first group of rectifier diodes has a switching waveform, it is smoothed by the smoothing circuit 7 and input to the reset circuit 8. When this smoothed voltage becomes less than a predetermined value, - from the reset circuit 8,
A reset signal is output and the inverter section 3 is stopped. Note that the blocking diode 9 is provided so that the charge stored in the smoothing capacitor 2 is not discharged via the switching power supply circuit 6. Therefore, the rectified voltage and the smoothed DC voltage can be clearly distinguished.

Figure 2 when a three-phase balanced voltage is input.

As shown in 1a, the rectified voltage is almost stabilized and remains at a level 1b or higher at which the switching power supply circuit 6 can perform oscillation operation. Therefore, the output 6a of the switching power supply circuit 6 repeats switching intermittently, is smoothed by the smoothing circuit 7, and the reset input voltage becomes stable.

However, if one phase of the AC power supply is missing, the imm lightning voltage 1a becomes the same as the single-phase rectified wave rectified waveform as shown in FIG. 3, and may become lower than level 1b. λdε
In the section where the voltage 1a is below the level 1b, switching of the switching power supply circuit 6 is stopped, resulting in intermittent oscillation as shown in 6a. Therefore, the input terminal 7a of the reset circuit decreases during this period and becomes below the reset level 7b, and a reset signal 8a is generated to stop the inverter section.

In this way, operation when one phase is missing can be prevented.

〔Effect of the invention〕

According to the present invention, a blocking diode is provided between the rectifier diode group and the smoothing capacitor to clearly separate the rectified voltage and the DC voltage, so that the rectified voltage can be detected when there is an input power supply abnormality such as an open phase. This function prevents excessive current from flowing into the inverter due to the influence of the power supply, and also prevents position detection due to DC voltage pulsations when the load is a DC motor. It has remarkable effects such as suppressing instability.

[Brief explanation of drawings]

FIG. 1 is a circuit configuration diagram of an embodiment of the present invention, and FIG. 2 is a circuit diagram of an embodiment of the present invention.
Operation waveform diagram of each part of the circuit during normal three-phase balanced input, Part 3
The figure shows the operating waveforms of each part of the circuit when one phase is lost.
FIG. 2 is a circuit configuration diagram of a conventional device. 1... Rectifier diode group, 2... Smoothing capacitor,
3... Inverter section, 4... Three-phase AC power supply, 5...
··motor. 6... Switching power supply circuit, 7... Smoothing circuit, 8
... Reset circuit, 9... Blocking diode. Dormitory 1 Nagi 2 Chona

Claims (1)

[Claims] 1. A group of bridge-connected rectifier elements, a smoothing capacitor that smoothes the rectified voltage, an inverter section that receives the DC voltage smoothed by the smoothing capacitor and sequentially performs switching control to output an AC voltage, and the rectifier A switching power supply circuit that generates a control voltage for the inverter section by inputting and switching a voltage, a smoothing circuit for smoothing the switching output of the switching power supply circuit, and a smoothing circuit that detects the output voltage of the smoothing circuit and outputs it to a predetermined value. A three-phase power receiving type inverter device having a reset circuit for stopping control of the inverter section in the following cases, characterized in that a blocking diode is provided between the rectifying element group and the smoothing capacitor. Inverter device.