# US 2017/0288567 A1 · Power conversion device

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- Number: US 2017/0288567 A1
- Document ID: US20170288567A1
- Status: Published application
- Kind: A1
- Application number: 15/511,289
- Filed: 2015-08-05
- Published: 2017-10-05
- Earliest claimed: 2014-09-26
- Assignees: Daikin Industries, Ltd.
- Applicants: Daikin Industries, Ltd.
- Inventors: Yasutaka TAGUCHI; Junya MITSUI; Akira MORIGUCHI
- Web page: https://patentgrep.com/patent/US20170288567A1

## CPC

- H02M 7/1557: {with automatic control of the output voltage or current}
- F04B 35/04: the means being electric
- F04B 39/02: Lubrication (of machines or engines in general F01M)
- F04B 49/06: Control using electricity (regulating by means of floats actuating electric switches F04B49/04)
- F04B 49/103: {Responsive to speed}
- F04B 49/20: by changing the driving speed
- F24F 11/89: Arrangement or mounting of control or safety devices
- F25B 1/00: Compression machines, plants or systems with non-reversible cycle (F25B3/00, F25B5/00, F25B6/00, F25B7/00, F25B9/00 take precedence)
- F25B 13/00: Compression machines, plants or systems, with reversible cycle (defrosting cycles F25B47/02)
- F25B 49/022: {Compressor control arrangements}
- H02M 1/12: Arrangements for reducing harmonics from AC input or output
- H02M 1/32: Means for protecting converters other than automatic disconnection
- H02M 1/44: Circuits or arrangements for compensating for electromagnetic interference in converters or inverters
- H02M 5/458: using semiconductor devices only
- H02M 7/48: using discharge tubes with control electrode or semiconductor devices with control electrode
- H02P 6/06: Arrangements for speed regulation of a single motor wherein the motor speed is measured and compared with a given physical value so as to adjust the motor speed
- F04B 2203/0201: Current
- F04B 2203/0209: Rotational speed
- F25B 2600/021: Inverters therefor
- F25B 2600/0253: with variable speed
- F25B 2700/151: of the compressor motor
- H02M 1/123: {Suppression of common mode voltage or current}
- Y02B 30/70: Efficient control or regulation technologies, e.g. for control of refrigerant flow, motor or heating
- Y02B 40/00: Technologies aiming at improving the efficiency of home appliances, e.g. induction cooking or efficient technologies for refrigerators, freezers or dish washers
- 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)
- F04B: POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS (machines for liquids, or pumps, of rotary-piston or oscillating-piston type F04C; non-positive-displacement pumps F04D; pumping of fluid by direct contact of another fluid or by using inertia of fluid to be pumped F04F)
- F24F: AIR-CONDITIONING; AIR-HUMIDIFICATION; VENTILATION; USE OF AIR CURRENTS FOR SCREENING (removing dirt or fumes from areas where they are produced B08B15/00; vertical ducts for carrying away waste gases from buildings E04F17/02; tops for chimneys or ventilating shafts, terminals for flues F23L17/02)
- F25B: REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
- H02P: CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
- Y02B: CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS

## Abstract

A power converter including a compressor as a load includes a compensation current output (80) allowing compensation current (Ic), which compensates for leakage current (Ia), to flow. A controller (50) receives a detection signal from a rotational speed sensor (55) which senses the rotational speed of the compressor (CM). When the rotational speed has increased to a set rotational speed at which the leakage current (Ia) is lower than or equal to its limiting value (Lmax) (e.g., the limiting value specified under the Electrical Appliances and Materials Safety Act or by the IEC) in a state where the compensation current output (80) is off, the compensation current output (80) is switched from an on state to an off state. This may reduce the leakage current from the compressor with low power loss.

## Claims

### Claim 1

A power converter comprising:
a converter circuit (10) configured to convert alternating current into direct current; and
an inverter circuit (40) connected to the converter circuit (10), and configured to convert the direct current, into which the alternating current has been converted, into alternating current,
the power converter being configured to supply the alternating current, into which the direct current has been converted by the inverter circuit (40), to a compressor (CM),
the power converter further including:
a compensation current output (80) configured to output compensation current (Ic), which compensates for leakage current (Ia) leaking from the compressor (CM), to a current path through which the leakage current (Ia) flows; and
a controller (50) configured to switch between on and off operations of the compensation current output (80) according to a rotational speed of the compressor (CM).

### Claim 2 (depends on 1)

The power converter of claim 1, wherein
the controller (50) switches the compensation current output (80) from an on state to an off state when the rotational speed of the compressor (CM) has increased to a set rotational speed (Rlh, Rlc) at which the leakage current (Ia) is lower than or equal to a predetermined limiting value (Lmax) in a state where the compensation current output (80) is off.

### Claim 3 (depends on 2)

The power converter of claim 2, wherein
the compressor (CM) is disposed in a refrigerant circuit (90) which has cooling and heating operation modes, and
the controller (50) controls the set rotational speed (Rlh, Rlc) so that the set rotational speed (Rlc) in the cooling operation mode is different from the set rotational speed (Rlh) in the heating operation mode.