Open-phase detecting method and apparatus

• US 20060186892A1
• Filed: 01/30/2006
• Published: 08/24/2006
• Est. Priority Date: 07/30/2003
• Status: Abandoned Application

• Current Assignee: Kabushiki Kaisha Yaskawa Denki
• Original Assignee: Kabushiki Kaisha Yaskawa Denki
• Inventors: Takahashi, Hajime, Hiramatsu, Kazuhiko
• Application Number:
  US11/341,855
• Publication Number:
  US 20060186892A1
• Time in Patent Office: Days
• US Class Current: 324/500
• CPC Class Codes: G01R 29/16 Measuring asymmetry of polyphase networks

Abstract

An open-phase detecting method wherein a simple hardware structure is used to achieve a reduced cost: the IRQ member is reduced to reduce the load on a CPU; the open phase detection is performed in two items, that is, a phase difference and a voltage sign to reduce the possibility of occurrence of erroneous detections; and any phase that is open can be also determined. In the method for detecting any open-phase of the power supply of a three-phase converter, a neutral point N1 is connected to a negative pole side bus N of the DC side output of the rectifying means; an end of the first resistor of each phase, which connects the first resistor to the second resistor of each phase, is connected to an AD converter via a high input impedance means of the respective phase to detect the voltage of the respective phase; the voltage of the respective phase is outputted to a CPU that serves as an open-phase detecting means; and an open phase is detected when the sings of two of the three line voltages determined based on the voltages of the respective phases are different from each other and a phase difference thereof exhibits a half-wave rectification waveform of 180°.

Claims

1. A method for detecting an open-phase of a power supply of a three-phase converter including a rectifying means for converting a three-phase AC power supply into a DC power supply, wherein one ends of respective phases of the three-phase AC power supply are connected to one ends of respective first resistors for respective phases, the other ends of the first registers are connected to one ends of respective second resistors for respective phases, and the three other ends of the second resistors are connected to each other, a connecting portion of the three other ends of the second resistors constituting a neutral point of a Y-connection, characterized in that

the neutral point is connected to a negative pole side bus of a DC side output of the rectifying means;

the other ends of the first resistors for respective phases, which connects the respective first resistors to the respective second resistors, are connected to respective AD converters via respective high input impedance means for the respective phases to detect the voltages of respective phases;

the voltages of respective phases are outputted to a CPU that serves as an open-phase detecting means; and

an open phase is detected when sings of two of the three-phase line voltages determined based on the voltages of respective phases are different from each other and a phase difference thereof exhibits a half-wave rectification waveform of 180°

.

2. The method for detecting an open-phase of a power supply of a three-phase converter as recited in claim 1, wherein the high input impedance means is a non-inverting amplifier circuit using an operational amplifier.

3. An open-phase detecting apparatus, comprising:

a rectifying circuit for converting a three-phase AC power supply into a DC power supply;

first resistors for respective phases, one ends of the first resistors being connected to respective phases of the power supply;

second resistors for respective phases, one ends of the second resistors being connected to the other ends of the respective first resistors, the three other ends of the second resistors being connected to each other, wherein a connecting portion of the three other ends of the second resistors constitutes a neutral point of a Y-connection;

high input impedance members for respective phases, each high input impedance member having an input terminal connected to the other end of each of the respective first resistors;

AD converters for respective phases, each AD converter having an input terminal connected to an output terminal of each of the respective high input impedance members; and

a CPU to which outputs of the two of the AD converters are inputted, the CPU serving as an open-phase detecting means,

wherein the neutral point of the Y-connection is connected to a negative pole side bus of a DC side output of the rectifying circuit, and

wherein the CPU discriminates that there is an open phase when the CPU detects that sings of two of the three-phase line voltages determined based on the voltages of the respective phases are different from each other and that a phase difference thereof exhibits a half-wave rectification waveform of 180°

.

4. The open-phase detecting apparatus as recited in claim 3, wherein the high input impedance means is a non-inverting amplifier circuit using an operational amplifier.