Life determination device for dc capacitor connected to DC side of rectifier

Patent metadata

Field	Value
Publication number	US-10564210-B2
Application number	US-201615063926-A
Country	US
Kind code	B2
Filing date	Mar 8, 2016
Priority date	Mar 10, 2015
Publication date	Feb 18, 2020
Grant date	Feb 18, 2020

Abstract

A life determination device for a DC capacitor includes: a current detecting unit that detects a current outputted from a rectifier; a voltage detecting unit that detects a voltage of the DC capacitor; an initial charging device that performs initial charging of the DC capacitor up to a predetermined voltage value with the current outputted from the rectifier; a current integrating unit that integrates the current detected by the current detecting unit during a period of the initial charging; a capacitance estimating unit that calculates an estimated capacitance of the DC capacitor from the current integration value, the predetermined voltage value, and the voltage of the DC capacitor prior to the initial charging; and life determination unit that determines whether the DC capacitor is at the end of its life based on an initial capacitance value of the DC capacitor in an unused state and the estimated capacitance.

First claim

What is claimed is:

1. A life determination device for a DC capacitor connected to a DC side of a rectifier, the life determination device comprising:
a current detecting unit that detects a current outputted from the rectifier;
a voltage detecting unit that detects a voltage applied to the DC capacitor;
an initial charging unit that performs initial charging of the DC capacitor up to a predetermined voltage value with the current outputted from the rectifier;
a current integrating unit that integrates, during a period of initial charging by the initial charging unit, the current detected by the current detecting unit and outputs the integrated current as a current integration value;
a capacitance estimating unit that calculates an estimated capacitance of the DC capacitor from the current integration value, the predetermined voltage value and the voltage of the DC capacitor detected by the voltage detecting unit prior to the initial charging; and
a life determination unit that determines whether the DC capacitor is at the end of its life based on a pre-measured initial capacitance value of the DC capacitor in an unused state and the estimated capacitance calculated by the capacitance estimating unit, wherein the current detecting unit is operatively coupled to an AC power supply by the rectifier and the initial charging unit performs initial charging of the DC capacitor with current supplied directly from the AC power supply through the rectifier to the initial charging unit until the DC capacitor reaches the predetermined voltage value.

2. The life determination device for the DC capacitor according to claim 1 , wherein the life determination unit determines that the DC capacitor is at the end of its life when the ratio of the estimated capacitance to the initial capacitance is lower than or equal to a preset reference ratio.

3. The life determination device for the DC capacitor according to claim 2 , wherein the life determination device further comprises a reference ratio setting unit that sets the reference ratio.

4. The life determination device for the DC capacitor according to claim 2 , wherein the life determination device further comprises an alarm signal outputting unit that outputs an alarm signal when the life determination unit determines that the DC capacitor is at the end of its life.

5. The life determination device for the DC capacitor according to claim 1 , wherein the life determination unit determines that the DC capacitor is at the end of its life when the estimated capacitance is smaller than or equal to a value obtained by multiplying the initial capacitance and the preset reference ratio.

6. The life determination device for the DC capacitor according to claim 1 , wherein the life determination device further comprises an initial capacitance storage unit in which is stored a pre-measured initial capacitance of the DC capacitor in an unused state.

Assignees

• Fanuc Corp

Inventors

• Yoshida Tomokazu

Classifications

• G01R31/00 Primary

  Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere ({measuring superconductive properties G01R33/1238;} testing line transmission systems H04B3/46; testing or measuring semiconductors or solid state devices during manufacture {H10P74/00}) · CPC title

• G01R31/64 Primary

  Testing of capacitors · CPC title

• G01R31/028 Primary

  Physics · mapped topic