JPH11206003A - Inverter device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a means for detecting open phase on the input side of an inverter device, which converts direct-current voltages obtained from a polyphase alternating-current power supply via a rectifying circuit and a smoothing capacitor into desired alternating-current voltage through an inverter and outputs the voltage. SOLUTION: Ripple components are extracted from the both-end voltages of the electrolytic capacitor 32 of an inverter device 5 through a voltage detector 51, which detects the both-end voltages and an open phase detecting means 52 or an open phase detecting means 53. The frequency or the repetition period of the ripple components is measured, and thereby failure of the phase of a three-phase alternating-current power supply 1' and disconnection state due to nonconformities in a circuit breaker 2 are detected.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an input-side open-phase detecting means of an inverter device.

[0002]

2. Description of the Related Art FIG. 4 is a circuit diagram showing a conventional example of this type of inverter device, wherein 1 is a three-phase AC power source such as a commercial power source, 2 is a circuit breaker, 3 is an inverter device, and 4 is an inverter device. An electric motor as a load of the device 3. The inverter device 3 shown in FIG. 4 includes, for example, a rectifier circuit 31 in which diodes are connected in a three-phase bridge, an electrolytic capacitor 32 as a smoothing capacitor, and a three-phase bridge in which, for example, a transistor and a diode are connected in anti-parallel. The inverter 33 includes a connected inverter 33, a control circuit 34 for controlling the output of the inverter 33 to be a three-phase AC voltage having a desired voltage and frequency, and an open-phase relay 35.

The open-phase relay 35 detects when the three-phase AC power supply 1 loses any phase for some reason or when the circuit breaker 2 is disconnected due to a mechanical failure or the like. The control circuit 34 sends an open phase signal to the control circuit 34 to stop the operation of the control circuit 34 by the open phase signal, thereby preventing, for example, overheating and deterioration of the rectifier circuit 31 and the electrolytic capacitor 32 due to the above state. The stop was displayed outside.

[0004]

The open-phase relay 35 of the conventional inverter device 3, which is constructed by a known technique, is relatively expensive, requires a large installation space, and reduces the size and cost of the inverter device. It was an inhibiting factor. An object of the present invention is to provide an inverter device that solves the above problems.

[0005]

According to the first invention, a DC voltage obtained from a polyphase AC power supply via a rectifier circuit and a smoothing capacitor is converted into an AC voltage having a desired voltage and frequency by an inverter. In the inverter device that supplies power to the load by monitoring the frequency or the repetition period of the ripple component included in the DC voltage, the absence of any phase of the AC power supply or the path from the AC power supply to the smoothing capacitor is monitored. And a disconnection detecting means for detecting the disconnection of the line.

In a second aspect based on the first aspect, the open-phase detecting means includes a filter circuit for extracting a ripple component included in the DC voltage, and a frequency measurement for measuring a frequency of an output of the filter circuit. It is assumed that the circuit comprises a circuit and an open-phase signal output circuit for outputting an open-phase signal to the outside when the measured frequency becomes equal to or lower than a predetermined value.
In a third aspect based on the first aspect, the open-phase detecting means includes a filter circuit for extracting a ripple component included in the DC voltage, and a Schmitt circuit for converting an output of the filter circuit into a square wave voltage. A counter circuit for measuring the repetition period of the square-wave voltage, and an open-phase signal output circuit for outputting an open-phase signal to the outside when the measured period becomes a predetermined value or more. .

According to the present invention, a new phase loss detecting means is provided in place of the phase loss relay provided in the conventional inverter device. In addition, as will be described later, the open phase detecting means can be easily realized by this digital control, and can contribute to downsizing and cost reduction of the device.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a circuit diagram of an inverter device showing an embodiment of the present invention, in which components having the same functions as those of the conventional circuit shown in FIG. ing. That is, the inverter device 5 shown in FIG. 1 includes a rectifier circuit 31, an electrolytic capacitor 32, an inverter 33,
In addition to the control circuit 34, a voltage detector 51 for insulating and detecting the voltage between both ends of the electrolytic capacitor 32, and an open-phase detecting means 52
Or, any one of the phase loss detecting means 53 is provided.

The voltage detector 51 shown in FIG. 1 detects that the voltage between both ends of the electrolytic capacitor 32 has risen to a specified value or more by regenerative electric power from the motor 4, for example, and uses a resistance discharge circuit (not shown) for suppressing this rise. It can be shared with a voltage detector for operation. FIG. 2 shows an open-phase detecting means 5 constituting an inverter device 5 according to a first embodiment of the present invention.
2 is a detailed circuit configuration diagram of FIG.

In FIG. 2, a DC component is removed from the detection value of the voltage detector 51 by a high-pass filter circuit 52a as a filter circuit. As a result, a ripple component of the voltage between both ends of the electrolytic capacitor 32 shown in FIG. Can be extracted.
When the inverter device 5 is in the normal state, the electrolytic capacitor 32
Has a ripple component having a frequency six times as high as the frequency of the three-phase AC power supply 1, but when the three-phase AC power supply 1 loses any phase for some reason, a circuit failure occurs due to a mechanical failure or the like. It is known that a ripple component having a frequency twice as high as the frequency of the three-phase AC power supply 1 is generated when any one of the phases of the circuit breaker 2 is disconnected.

That is, the frequency of the ripple component measured by the frequency measurement circuit 52b via the high-pass filter circuit 52a is normally 6 times the frequency of the three-phase AC power supply 1.
When the phase of the three-phase AC power supply 1 is lost, the frequency becomes twice the frequency of the three-phase AC power supply 1.
Therefore, the measured value which is the output of the frequency measurement circuit 52b is 3
When the frequency becomes twice as high as the frequency of the phase AC power supply 1, the phase loss signal output circuit 52c may detect this and send a phase loss signal to the control circuit 34 shown in FIG.

Instead of the high-pass filter circuit 52a, a band-pass filter for removing a DC component from the detected value of the voltage detector 51 and a noise component superimposed on the detected value due to the switching operation of the inverter 33. A filter circuit may be used. FIG. 3 is a detailed circuit configuration diagram of the open-phase detecting means 53 included in the inverter device 5 according to the second embodiment of the present invention.

In FIG. 3, a high-pass filter circuit 53 having the same function as the high-pass filter circuit 52a shown in FIG.
a, the ripple component of the voltage between both ends of the electrolytic capacitor 32 shown in FIG. 1 is extracted, and the waveform of the ripple component is converted into a square wave by the smit circuit 53b. Measure the time from to the next rise.

That is, the repetition cycle of the ripple component measured by the counter circuit 53c via the high-pass filter circuit 53a and the limit circuit 53b is normally 1/6 times the one cycle of the three-phase AC power supply 1. When one of the phases of the three-phase AC power supply 1 is missing, the value becomes 倍 of one cycle of the three-phase AC power supply 1. Therefore, when the measured value which is the output of the counter circuit 53c becomes 1/2 the value of one cycle of the three-phase AC power supply 1, the open-phase signal output circuit 5
3d may detect this and send an open phase signal to the control circuit 34 shown in FIG.

Instead of the high-pass filter circuit 53a, a band-pass filter for removing a DC component and a noise component superimposed on the detected value with the switching operation of the inverter 33 from the detected value of the voltage detector 51. A filter circuit may be used.

[0016]

According to the present invention, the voltage detector 51 is constituted by an A / D converter or the like, particularly when the digital control of the inverter device by the recent microcomputer is supported.
The digital value output from the D converter is taken into the microcomputer at a fixed period, the ripple component of the voltage across the electrolytic capacitor 32 is extracted from the change in the digital value, and the frequency or repetition period of the ripple component is measured inside the microcomputer. If the voltage detector 51 necessary for the operation of the above-described resistance discharge circuit is shared with the voltage detector 51, a new hardware circuit is not required for this inverter device. Since the open phase detecting means 52 or 53 can be realized, the size and cost of this type of inverter can be reduced.

[Brief description of the drawings]

FIG. 1 is a circuit configuration diagram of an inverter device showing an embodiment of the present invention.

FIG. 2 shows a first embodiment of the present invention, and is a partial detailed circuit diagram of the circuit configuration diagram shown in FIG. 1;

FIG. 3 shows a second embodiment of the present invention, and is a partially detailed circuit diagram of the circuit configuration diagram shown in FIG. 1;

FIG. 4 is a circuit configuration diagram of an inverter device showing a conventional example.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Three-phase alternating current power supply, 2 ... Circuit breaker, 3 ... Inverter device, 4 ... Electric motor, 5 ... Inverter device, 31 ... Rectifier circuit, 32 ... Electrolytic capacitor, 33 ... Inverter, 34 ...
Control circuits 34, 35: open-phase relay, 51: voltage detector,
52, 53... Open-phase detecting means.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI H02M 7/06 H02M 7/06 H 7/48 7/48 M

Claims (3)

[Claims] 1. An inverter device for converting a DC voltage obtained from a polyphase AC power supply via a rectifier circuit and a smoothing capacitor into an AC voltage having a desired voltage and frequency by an inverter and feeding the AC voltage to a load, wherein: An open-phase detecting unit is provided for detecting the absence of any phase of the AC power supply or the disconnection of the path from the AC power supply to the smoothing capacitor by monitoring the frequency or the repetition period of the ripple component included in the voltage. An inverter device, characterized in that: 2. The inverter device according to claim 1, wherein the open-phase detecting means extracts a ripple component included in the DC voltage, and a frequency measurement circuit that measures a frequency of an output of the filter circuit. And an open-phase signal output circuit for outputting an open-phase signal to the outside when the measured frequency becomes equal to or lower than a predetermined value. 3. The inverter device according to claim 1, wherein the open-phase detecting means includes a filter circuit for extracting a ripple component included in the DC voltage, and a Schmitt for converting an output of the filter circuit into a square wave voltage. A circuit, a counter circuit for measuring a repetition period of the square-wave voltage, and an open-phase signal output circuit for outputting an open-phase signal to the outside when the measured period becomes a predetermined value or more. An inverter device characterized by the above-mentioned.