Current detecting device, air conditioning apparatus, correction constant calculating system and correction constant calculating method

• US 8,400,083 B2
• Filed: 10/21/2008
• Issued: 03/19/2013
• Est. Priority Date: 10/23/2007
• Status: Active Grant

• Current Assignee: Daikin Industries Ltd
• Original Assignee: Daikin Industries Ltd
• Inventors: Hashimoto, Masafumi, Shimatani, Keisuke, Ikeda, Motonobu, Yagi, Satoshi, Maeda, Hirohito
• Primary Examiner(s): Ip, Paul
• Application Number:
  US12/738,328
• Publication Number:
  US 20100211223A1
• Time in Patent Office: 1,610 Days
• Field of Search: 318/268, 318/434, 318/618, 318/723, 318/400.07, 318/801, 363/37, 363/97, 622/29, 622/30
• US Class Current: 318/268
• CPC Class Codes: F24F 11/47 Responding to energy costs
• CPC Class Codes: F24F 11/77 by controlling the speed of ventilators
• CPC Class Codes: H02M 1/0009 Devices or circuits for detecting current in a converter
• CPC Class Codes: H02P 2205/01 Current loop, i.e. comparison of the motor current with a current reference
• CPC Class Codes: H02P 27/06 using dc to ac converters or inverters H02P27/05 takes precedence
• CPC Class Codes: H02P 6/28 Arrangements for controlling current H02P6/10 takes precedence
• CPC Class Codes: Y02B 30/70 Efficient control or regulation technologies, e.g. for control of refrigerant flow, motor or heating

Abstract

A current detecting device includes a current leveling unit, a first wire and a current detecting unit. The current leveling unit is configured to level a drive current that is passed through a motor drive unit to drive a motor. The first wire is configured and arranged to carry flow of a motor current that has been passed through the motor and the drive current that has been leveled by the current leveling unit. The current detecting unit is configured to detect a sum of the motor current flowing on the first wire and the drive current that has been leveled flowing on the first wire.

Claims

1. A current detecting device connected to a motor device that includes a motor and a motor drive unit to drive the motor, the current detecting device comprising:

a second wire configured and arranged to carry flow of a drive current that is passed through the motor drive unit;

a third wire configured and arranged to carry flow of a motor current that has been passed through the motor;

a current leveling unit electrically connected to the second wire, the current leveling unit being configured to level the drive current on the second wire;

a first wire electrically connected to the current leveling unit, the first wire being configured and arranged to carry flow of

the motor current after flowing through the motor and

the drive current that has been leveled by the current leveling unit; and

a current detecting unit electrically connected to the current leveling unit and the first wire, the current detecting unit being configured to detect a sum of

the motor current flowing on the first wire and

the drive current that has been leveled flowing on the first wire.

2. The current detecting device according to claim 1, wherein

the current leveling unit has a resistor connected in series to the second wire and a capacitor connected to the second wire in parallel with respect to the resistor.

3. The current detecting device according to claim 1, further comprising

a storage unit electrically connected to the current detecting unit, the storage unit being configured to store a correction constant useable to correct a detection result obtained from the current detecting unit;

and

a motor current calculating unit electrically connected to the current detecting unit, the motor current calculating unit being configured to calculate the motor current flowing on the third wire on the basis of the correction constant stored in the storage unit and the detection result obtained from the current detecting unit.

11. The current detecting device according to claim 2, further comprising

a storage unit electrically connected to the current detecting unit, the storage unit being configured to store a correction constant useable to correct a detection result obtained from the current detecting unit;

and

a motor current calculating unit electrically connected to the current detecting unit, the motor current calculating unit being configured to calculate the motor current flowing on the third wire on the basis of the correction constant stored in the storage unit and the detection result obtained from the current detecting unit.

4. An air conditioning apparatus comprising:

a motor device, the motor device including a fan motor included in the motor device together with a motor drive unit, the fan motor being arranged and configured to have a motor current pass therethrough;

a current detecting device including

a second wire configured and arranged to carry flow of a drive current that is passed through the motor drive unit,

a third wire configured and arranged to carry flow of the motor current that has been passed through the motor,

a current leveling unit electrically connected to the second wire, the current leveling unit being configured to level the drive current on the second wire,

a first wire electrically connected to the current leveling unit, the first wire being configured and arranged to carry flow of

the motor current after flowing through the motor and

the drive current that has been leveled by the current leveling unit,

a current detecting unit electrically connected to the current leveling unit and the first wire, the current detecting unit being configured to detect a sum of

the motor current flowing on the first wire and

the drive current that has been leveled flowing on the first wire,

a storage unit electrically connected to the current detecting unit, the storage unit being configured to store a correction constant useable to correct a detection result obtained from the current detecting unit, and

a motor current calculating unit electrically connected to the current detecting unit, the motor current calculating unit being configured to calculate the motor current flowing on the third wire on the basis of the correction constant stored in the storage unit and the detection result obtained from the current detecting unit;

a fan configured to be rotated by the fan motor; and

a control unit electrically connected to the motor device, the control unit being configured to control a volume of air sent into a room from the fan on the basis of the motor current that has been calculated by the motor current calculating unit of the current detecting device.

5. A correction constant calculating system comprising:

a current detecting device connected to a motor device that includes a motor and a motor drive unit to drive the motor the current detecting device including

a second wire configured and arranged to carry flow of a drive current that is passed through the motor drive unit,

a third wire configured and arranged to carry flow of the motor current that has been passed through the motor,

a current leveling unit electrically connected to the second wire, the current leveling unit being configured to level the drive current on the second wire,

a first wire electrically connected to the current leveling unit, the first wire being configured and arranged to carry flow of

the motor current after flowing through the motor and

the drive current that has been leveled by the current leveling unit,

a current detecting unit electrically connected to the current leveling unit and the first wire, the current detecting unit being configured to detect a sum of

the motor current flowing on the first wire and

the drive current that has been leveled flowing on the first wire,

a storage unit electrically connected to the current detecting unit, the storage unit being configured to store a correction constant useable to correct a detection result obtained from the current detecting unit, and

a motor current calculating unit electrically connected to the current detecting unit, the motor current calculating unit being configured to calculate the motor current flowing on the third wire on the basis of the correction constant stored in the storage unit and the detection result obtained from the current detecting unit;

a power meter connected to the third wire of the current detecting device, the power meter being configured to measure the motor current flowing on the third wire; and

a correction constant calculating unit electrically connected to the current detecting device, the correction constant calculating unit being configured to calculate the correction constant on the basis of the detection result of the current detecting unit in the current detecting device and a measurement result obtained from the power meter,

the correction constant calculating unit being further configured to write the correction constant it has calculated in the storage unit of the current detecting device.

6. The correction constant calculating system according to claim 5, wherein

the correction constant calculating unit is further configured to perform operations of calculating and writing the correction constant before shipment of the current detecting device.

7. The correction constant calculating system according to claim 5, wherein

the correction constant calculating unit is further configured

to calculate the correction constant on the basis of the detection result of the current detecting unit and the measurement result of the power meter at a time when the motor is rotating and

to calculate the detection result of the current detecting unit at a time when the motor is not rotating.

12. The correction constant calculating system according to claim 6, wherein

the correction constant calculating unit is further configured

to calculate the correction constant on the basis of the detection result of the current detecting unit and the measurement result of the power meter at a time when the motor is rotating and

to calculate the detection result of the current detecting unit at a time when the motor is not rotating.

8. A correction constant calculating method using a current detecting device connected to a motor device that includes a motor and a motor drive unit to drive the motor, the current detecting device including

a second wire configured and arranged to carry flow of a drive current that is passed through the motor drive unit,

a third wire configured and arranged to carry flow of a motor current that has been passed through the motor,

a current leveling unit electrically connected to the second wire, the current leveling unit being configured to level the drive current on the second wire,

a first wire electrically connected to the current leveling unit, the first wire being configured and arranged to carry flow of

the motor current after flowing through the motor and

the drive current that has been leveled by the current leveling unit,

a current detecting unit electrically connected to the current leveling unit and the first wire, the current detecting unit being configured to detect a sum of

the motor current flowing on the first wire and

the drive current that has been leveled flowing on the first wire,

a storage unit electrically connected to the current detecting unit, the storage unit being configured to store a correction constant useable to correct a detection result obtained from the current detecting unit, and

a motor current calculating unit electrically connected to the current detecting unit, the motor current calculating unit being configured to calculate the motor current flowing on the third wire on the basis of the correction constant stored in the storage unit and the detection result obtained from the current detecting unit, the correction constant calculating method comprising:

connecting a power meter to the third wire;

measuring the motor current flowing on the third wire with the power meter;

calculating the correction constant using a correction constant calculating unit electrically connected to the current detecting device and the power meter on the basis of the detection result of the current detecting unit in the current detecting device;

calculating a measurement result obtained by the power meter using the correction constant calculating unit; and

writing the correction constant that has been calculated in the storage unit of the current detecting device.

9. The correction constant calculating method according to claim 8, wherein

the connecting of the power meter to the third wire, the measuring of the motor current flowing on the third wire, the calculating of the correction constant, the calculating of the measurement result and the writing of the correction constant are performed are performed before shipment of the current detecting device.

10. The correction constant calculating method according to claim 8, wherein

the correction constant is calculated on the basis of the detection result of the current detecting unit and the measurement result of the power meter at a time when the motor is rotating, and

the detection result of the current detecting unit is calculated at a time when the motor is not rotating.

13. The correction constant calculating method according to claim 9, wherein

the correction constant is calculated on the basis of the detection result of the current detecting unit and the measurement result of the power meter at a time when the motor is rotating, and

the detection result of the current detecting unit is calculated at a time when the motor is not rotating.