Motor driving device including electric storage device

• US 9,054,620 B2
• Filed: 07/16/2013
• Issued: 06/09/2015
• Est. Priority Date: 07/17/2012
• Status: Active Grant

• Current Assignee: Fanuc Corporation
• Original Assignee: Fanuc Corporation
• Inventors: Niwa, Masakazu, Sakai, Koujirou
• Primary Examiner(s): Leykin, Rita
• Application Number:
  US13/943,419
• Publication Number:
  US 20140021888A1
• Time in Patent Office: 693 Days
• Field of Search: 320/109, 320/127, 320/118, 320/104, 320/123, 320/128, 320/129, 320/132, 307/9.1, 318/139, 318/803, 318/800, 340/636.1, 340/636.13, 340/636.15, 340/636.16, 340/636.17, 340/636.19, 361/212, 361/229, 361/225, 361/213, 327/533, 327/531
• US Class Current: 1/1
• CPC Class Codes: H02J 1/108 using diodes blocking reverse current flow H02J1/12 takes precedence
• CPC Class Codes: H02J 9/061 for DC powered loads
• CPC Class Codes: H02P 2201/09 Boost converter, i.e. DC-DC step up converter increasing the voltage between the supply and the inverter driving the motor
• CPC Class Codes: H02P 27/00 Arrangements or methods for the control of AC motors characterised by the kind of supply voltage of two or more motors H02P5/00; of synchronous motors with electronic commutators H02P6/00; of DC motors H02P7/00; of stepping motors H02P8/00
• CPC Class Codes: H02P 27/06 using dc to ac converters or inverters H02P27/05 takes precedence
• CPC Class Codes: H02P 29/032 Preventing damage to the motor, e.g. setting individual current limits for different drive conditions

Abstract

A motor driving device includes a rectifier, an inverter connected to a DC link on a DC side of the rectifier, a power failure detecting unit for detecting a power failure on the alternating side of the rectifier, an electric storage device connected to the DC link, a charging unit that possesses a voltage boosting function of charging the electric storage device by direct current power at the DC link, a discharging unit that causes direct current power stored in the electric storage device to be discharged to the DC link, and a control unit that causes the charging unit to operate when the power failure detecting unit does not detect a power failure, or before start of motor drive, and causes the discharging unit and the inverter to operate when the power failure detecting unit detects a power failure.

Claims

1. A motor driving device comprising:

a rectifier that rectifies alternating current power supplied from an alternating current side to output direct current power;

an inverter that is connected to a direct current link on a direct current side of the rectifier and that mutually transforms electric power between direct current power at the direct current link and alternating current power that is driving electric power for a motor or electric power regenerated in the motor;

a power failure detecting unit for detecting a power failure on the alternating current side of the rectifier;

an electric storage device that is connected to the direct current link and that includes a capacity for storing direct current power;

a charging unit that possesses a voltage boosting function of charging the electric storage device to a voltage higher than a direct current voltage at the direct current link and that has a circuit device having a small current rating smaller than a rating needed to charging the electric storage device during drive control of the motor when a power failure is not occurring;

a discharging unit for making a short-circuit between the electric storage device and the direct current link to cause direct current power stored in the electric storage device to be discharged to the direct current link; and

a control unit that outputs a charging command for causing the charging unit to operate before drive of the motor is started, and outputs a discharging command for causing the discharging unit to operate and a predetermined motor driving command for causing the inverter to operate when the power failure detecting unit detects a power failure on the alternating side of the rectifier.

2. The motor driving device according to claim 1, wherein the predetermined motor driving command causes the inverter to invert direct current power at the direct current link into alternating current power allowing the motor to perform operation predetermined to be performed when a power failure occurs on the alternating side.

3. The motor driving device according to claim 2, further comprising:

a regenerated electric power consuming unit including an electric resistance and a switch that closes and opens an electric path between the electric resistance and the direct current link, wherein when receiving an electric resistance consuming start command, the switch closes the electric path, and when receiving an electric resistance consuming stop command, the switch opens the electric path; and

a direct current voltage detecting unit detecting a direct current voltage at the direct current link,

wherein when the power failure detecting unit detects a power failure on the alternating side of the rectifier, when a direct current voltage detected by the direct current voltage detecting unit is higher than a first threshold, the control unit transmits the electric resistance consuming start command to the regenerated electric power consuming unit, and when the direct current voltage detected by the direct current voltage detecting unit is lower than a second threshold that is less than the first threshold, the control unit transmits the electric resistance consuming stop command to the regenerated electric power consuming unit.