# US 10,320,281 B2 · Converter apparatus having function of detecting failure of power device, and method for detecting failure of power device

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- Number: US 10,320,281 B2
- Document ID: US10320281B2
- Status: Granted
- Kind: B2
- Application number: 15/943,164
- Filed: 2018-04-02
- Published: 2018-10-11
- Granted: 2019-06-11
- Earliest claimed: 2017-04-07
- Assignees: Fanuc Corporation
- Applicants: Fanuc Corporation
- Inventors: Tomokazu Yoshida
- Web page: https://patentgrep.com/patent/US10320281B2

## CPC

- H02M 1/32: Means for protecting converters other than automatic disconnection
- G01R 31/00: 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})
- G01R 31/40: Testing power supplies (testing photovoltaic devices H02S50/10)
- G01R 31/52: Testing for short-circuits, leakage current or ground faults
- H02H 7/1203: {Circuits independent of the type of conversion}
- H02H 7/1225: {responsive to internal faults, e.g. shoot-through (avoiding shoot-through H02M1/38)}
- H02H 9/00: Emergency protective circuit arrangements for limiting excess current or voltage without disconnection
- H02J 7/00: Circuit arrangements for charging or discharging batteries or for supplying loads from batteries
- H02M 1/08: Circuits specially adapted for the generation of control voltages for semiconductor devices incorporated in static converters
- H02M 7/219: in a bridge configuration
- H02P 7/00: Arrangements for regulating or controlling the speed or torque of electric DC motors
- H02P 29/027: {the fault being an over-current}
- G01R 31/50: Testing of electric apparatus, lines, cables or components for short-circuits, continuity, leakage current or incorrect line connections (testing of sparking plugs H01T13/58)
- H02H 9/001: {limiting speed of change of electric quantities, e.g. soft switching on or off (progressive control of electronic switches for eliminating interferences H03K17/16)}
- H02J 7/345: {using capacitors as storage or buffering devices}
- H02M 1/0009: {Devices or circuits for detecting current in a converter}
- H02M 1/0025: {Arrangements for modifying reference values, feedback values or error values in the control loop of a converter}
- H02M: APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF (transformers H01F; dynamo-electric converters H02K47/00; controlling transformers, reactors or choke coils, control or regulation of electric motors, generators or dynamo-electric converters H02P)
- G01R: MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES (indicating correct tuning of resonant circuits H03J3/12)
- H02H: EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS (indicating or signalling undesired working conditions G01R, e.g. G01R31/00, G08B; locating faults along lines G01R31/08; emergency protective devices H01H)
- H02J: ELECTRIC POWER NETWORKS; CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02P: CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS

## Abstract

A converter apparatus includes: a converter for converting an AC voltage into a DC voltage; a DC link capacitor connected to the converter; a voltage detector for DC link voltage; a charging circuit for the DC link capacitor; a charging circuit controller for a switch connected with a charging resistor; a current detector for detecting a current of the converter; a turn-on controller for controlling the turning-on of power devices; a switch for connecting or disconnecting a power supply; a power supply monitor for monitoring a connection state of the power supply; a threshold value setter for setting a first or second threshold value; and a failure detector for determining the presence or absence of the failure of the power devices by a comparison between a current flowing upon turning on the power device, immediately after disconnection of the power supply, and the first or second threshold value.

## Claims

### Claim 1

A converter apparatus comprising:
a converter including a plurality of power devices, configured to convert an AC voltage supplied from a power supply into a DC voltage, and output the DC voltage;
a DC link capacitor connected to an output side of the converter;
a voltage detector configured to detect a voltage of the DC link capacitor;
a charging circuit disposed between the converter and the DC link capacitor, configured to charge the DC link capacitor;
a charging circuit controller configured to control a charging switch connected in parallel with a charging resistor in the charging circuit;
a current detector configured to detect a current flowing between the converter and the DC link capacitor;
a turn-on controller configured to control turning-on of the power devices of the converter;
a power switch configured to connect or disconnect between the power supply and the converter;
a power supply monitor configured to control switching of the power switch, and to monitor a connection state between the power supply and the converter by detecting a voltage to be inputted to the converter;
a threshold value setter configured to set a first threshold value or a second threshold value to determine a presence or an absence of a failure of the power devices; and
a failure detector configured to determine the presence or absence of the failure of the power devices by a comparison between the first threshold value or the second threshold value and a current flowing upon turning on at least one power device of the converter using electric charge of the DC link capacitor, immediately after the power switch disconnects the power supply from the converter and the charging switch is turned off.

### Claim 2 (depends on 1)

The converter apparatus according to claim 1, wherein when the turn-on controller turns on the at least one power device, the charging circuit controller controls the charging circuit such that an excessive current does not flow through the at least one power device.

### Claim 3 (depends on 1)

The converter apparatus according to claim 1, wherein the failure detector compares a current flowing upon concurrently turning on the power devices for an upper arm and a lower arm which are connected to the same phase of the converter with the first threshold value in order to detect the presence or absence of an open-circuit failure of the power devices for the upper arm and the lower arm.

### Claim 4 (depends on 1)

The converter apparatus according to claim 1, wherein the failure detector compares a current flowing upon turning on a power device for any one of an upper arm and a lower arm of the converter with the second threshold value in order to detect the presence or absence of a short-circuit failure of the power device for the other of the upper arm and the lower arm.

### Claim 5 (depends on 1)

The converter apparatus according to claim 1, wherein the threshold value setter can rewrite the first threshold value or the second threshold value based on a signal inputted from outside.

### Claim 6

A method for detecting a failure of a power device of a converter apparatus including:
a converter including a plurality of power devices, configured to convert an AC voltage supplied from a power supply into a DC voltage, and output the DC voltage;
a DC link capacitor connected to an output side of the converter;
a charging switch connected in parallel with a charging resistor and connected to the DC link capacitor;
a current detector configured to detect a current flowing between the converter and the DC link capacitor; and
a power switch configured to connect or disconnect between the power supply and the converter,
the method comprising:
connecting the power supply to the converter by closing the power switch;
charging the DC link capacitor;
controlling the power switch so as to turn the power switch into an open state, to disconnect the power supply from the converter;
detecting a current flowing between the converter and the DC link capacitor, immediately after the power supply is disconnected from the converter; and
determining a presence or an absence of a failure of the power devices by:
turning off the charging switch after the power switch is turned off to supply the electric charge from the DC link capacitor to the converter,
turning on at least one of the power devices of the converter, and
comparing current flowing through the converter to:
a first threshold value to determine the presence or absence of an open-circuit failure of the power devices, or
a second threshold value to determine the presence or absence of an short-circuit failure of the power devices.

### Claim 7 (depends on 6)

The method for detecting the failure of the power device according to claim 6, wherein when the power device is turned on, a charging circuit disposed between the converter and the DC link capacitor, for charging the DC link capacitor, is controlled so that an excessive current does not flow through the power device.

### Claim 8 (depends on 6)

The method for detecting the failure of the power device according to claim 6, wherein a current flowing upon concurrently turning on the power devices for an upper arm and a lower arm which are connected to the same phase of the converter is compared with the first threshold value, in order to detect the presence or absence of the open circuit failure of the power devices for the upper arm and the lower arm.

### Claim 9 (depends on 6)

The method for detecting the failure of the power device according to claim 6, wherein a current flowing upon turning on the power device for any one of an upper arm and a lower arm of the converter is compared with the second threshold value, in order to detect the presence or absence of the short-circuit failure of the power device for the other of the upper arm and the lower arm.

### Claim 10 (depends on 6)

The method for detecting the failure of the power device according to claim 6, wherein a threshold value setter can rewrite the first threshold value or the second threshold value based on a signal inputted from outside.