Electric power conversion device, compressor motor with the device, and air conditioner with the motor

• US 8,305,020 B2
• Filed: 02/19/2009
• Issued: 11/06/2012
• Est. Priority Date: 06/27/2008
• Status: Expired due to Fees

• Current Assignee: Hitachi Industrial Equipment Systems Company Limited (Hitachi, Ltd.), Hitachi, Ltd.
• Original Assignee: Hitachi Industrial Equipment Systems Company Limited (Hitachi, Ltd.), Hitachi, Ltd.
• Inventors: Suzuki, Takahiro, Notohara, Yasuo, Sakamoto, Kiyoshi
• Primary Examiner(s): Benson, Walter
• Assistant Examiner(s): DINH, THAI T
• Application Number:
  US12/388,762
• Publication Number:
  US 20090323232A1
• Time in Patent Office: 1,356 Days
• Field of Search: 318/400.21, 318/400.22, 318/400.26, 318/400.27, 318/722, 318/723, 318/724, 318/254.1, 318/434, 361/1, 361/2, 361/8, 361/22, 361/23, 361/31
• US Class Current: 318/400.21
• CPC Class Codes: H02M 1/0009 Devices or circuits for detecting current in a converter
• CPC Class Codes: H02M 1/32 Means for protecting converters other than automatic disconnection
• CPC Class Codes: H02M 7/53873 with digital control
• CPC Class Codes: H02M 7/5395 by pulse-width modulation

Abstract

The device is provided with an electric power conversion circuit including switching elements for converting a DC electric power to an AC electric power, a load connected to an output side of the electric power conversion circuit, means for detecting a current flowing through a DC side in the electric power conversion circuit, a voltage command value preparing means for controlling the operation of the switching elements in the electric power conversion circuit and a wire breaking detecting means. The wire breaking detection means judges a wire breaking in the load or an abnormality of any of the switching elements in the electric power conversion circuit by making use of a DC current detection value in a period when a current of maximum voltage phase or of voltage minimum phase of the electric power conversion circuit is flowing in a DC current.

Claims

1. An electric power conversion device comprising:

an electric power conversion circuit including switching elements for converting a DC electric power to an AC electric power,

a load connected to an output side of the electric power conversion circuit,

a DC current detecting means for detecting a current flowing through a DC side in the electric power conversion circuit, and

a control circuit for controlling the switching elements in the electric power conversion circuit,

characterized by further comprising a wire breaking detecting means that judges a wire breaking in the load or an abnormality of any of the switching elements in the electric power conversion circuit by making use of a value of DC current detected by the DC current detecting means during a time when a first current flows in a voltage maximum phase, which has the longest turn-on term in a duty cycle for upper arm switching elements of the electric power conversion circuit, which first current flows through the DC side in the electric power conversion circuit, or during a time when a second current flows in a voltage minimum phase, which has the shortest turn-on term in the duty cycle for the upper arm switching elements, which second current flows through the DC side in the electric power conversion circuit.

2. The electric power conversion device according to claim 1 characterized in that the wire breaking detecting means judges the wire breaking in the load or the abnormality of any of the switching elements in the electric power conversion circuit by making use of an integration value of the DC current detection value.

3. The electric power conversion device according to claim 1 characterized by further comprising an abnormality informing means for informing outside when the wire breaking detecting means judges the wire breaking in the load or the abnormality of any of the switching elements in the electric power conversion circuit.

4. The electric power conversion device according to claim 1 characterized by further comprising a stopping control means for stopping a voltage applying to a motor load being driven or a decelerating and stopping control means for stopping the motor after deceleration when the wire breaking in the load or the abnormality of any of the switching elements in the electric power conversion circuit is judged.

5. The electric power conversion device according to claim 1 characterized by being accommodated into a single package.

6. An electric power conversion device comprising:

an electric power conversion circuit including switching elements for converting a DC electric power to an AC electric power,

a load connected to an output side of the electric power conversion circuit,

a DC current detecting means for detecting a current flowing through a DC side in the electric power conversion circuit, and

a control circuit for controlling the switching elements in the electric power conversion circuit,

characterized in that the control circuit includes a voltage command value preparing means for outputting a voltage command value, the voltage command value preparing means alters the voltage command value in an integral multiple cycle of ½

of a cycle for controlling the switching elements in the electric power conversion circuit, and

characterized by further comprising a wire breaking detecting means that judges a wire breaking in the load or an abnormality of any of the switching elements in the electric power conversion circuit by making use of a value of DC current detected by the DC current detecting means, at the time when the voltage command value preparing means alters the voltage command value, in a period when a current of voltage maximum phase or of voltage minimum phase of the electric power conversion circuit is flowing in a DC current.

7. The electric power conversion device according to claim 6 characterized in that the voltage command value preparing means alters a d axis current command value when preparing the voltage command value, the wire breaking detecting means judges the wire breaking in the load or the abnormality of any of the switching elements in the electric power conversion circuit by making use of a value of DC current detected by the DC current detecting means, at the time when the voltage command value preparing means alters the d axis current command value, in the period when the current of voltage maximum phase or of voltage minimum phase of the electric power conversion circuit is flowing in the DC current.

8. The electric power conversion device according to claim 6 characterized in that the wire breaking detecting means judges the wire breaking in the load or the abnormality of any of the switching elements in the electric power conversion circuit by making use of a difference of values of DC current detected by the DC current detecting means before and after the voltage command value being altered by the voltage command value preparing means in a period when the current of voltage maximum phase or of voltage minimum phase of the electric power conversion circuit is flowing in the DC current.

9. The electric power conversion device according to claim 6 characterized in that the wire breaking detecting means judges the wire breaking in the load or the abnormality of any of the switching elements in the electric power conversion circuit by making use of an integration value of the values of DC current detected by the DC current detecting means in the period when the current of voltage maximum phase or of voltage minimum phase of the electric power conversion circuit is flowing in the DC current.

10. The electric power conversion device according to claim 6 characterized by further comprising an abnormality informing means for informing outside when the wire breaking detecting means judges the wire breaking in the load or the abnormality of any of the switching elements in the electric power conversion circuit.

11. The electric power conversion device according to claim 6 characterized by further comprising a stopping control means for stopping a voltage applying to a motor load being driven or a decelerating and stopping control means for stopping the motor after deceleration when the wire breaking in the load or the abnormality of any of the switching elements in the electric power conversion circuit is judged.

12. A compressor motor using an electric power conversion device, wherein the electric power conversion device comprising:

an electric power conversion circuit including switching elements for converting a DC electric power to an AC electric power,

a load connected to an output side of the electric power conversion circuit,

a DC current detecting means for detecting a current flowing through a DC side in the electric power conversion circuit,

a control circuit for controlling the switching elements in the electric power conversion circuit, and

a wire breaking detecting means that judges a wire breaking in the load or an abnormality of any of the switching elements in the electric power conversion circuit by making use of a value of DC current detected by the DC current detecting means during a first time when a first current flows in a voltage maximum phase, which has the longest turn-on term in a duty cycle for upper arm switching elements of the electric power conversion circuit, which first current flows through the DC side in the electric power conversion circuit, or during a time when a second current flows in a voltage minimum phase, which has the shortest turn-on in the duty cycle for upper arm switching elements, which second current flows through the DC side in the electric power conversion circuit.

13. An air conditioner characterized by being provided with the compressor motor according to claim 12.