Power transducer

• US 8,531,140 B2
• Filed: 01/23/2013
• Issued: 09/10/2013
• Est. Priority Date: 03/10/2008
• Status: Active Grant

• Current Assignee: Hitachi Industrial Equipment Systems Company Limited (Hitachi, Ltd.)
• Original Assignee: Hitachi Industrial Equipment Systems Company Limited (Hitachi, Ltd.)
• Inventors: Ibori, Satoshi, Uchino, Yoshihiro, Watanabe, Hiroshi, Hiraga, Masahiro
• Primary Examiner(s): DUDA, RINA I
• Application Number:
  US13/747,574
• Publication Number:
  US 20130127382A1
• Time in Patent Office: 230 Days
• Field of Search: 318/375, 318/376, 318/727, 318/800, 318/801, 318/803
• US Class Current: 318/375
• CPC Class Codes: H02M 1/32 Means for protecting converters other than automatic disconnection
• CPC Class Codes: H02M 5/458 using semiconductor devices only
• CPC Class Codes: H02P 3/14 by regenerative braking
• CPC Class Codes: H02P 3/22 by short-circuit or resistive braking

Abstract

The performance of a power transducer is improved while efficiently using a power semiconductor also by managing the permissible duty factor of the power semiconductor in the regenerative braking circuit provided in the power transducer. The user is allowed to set, through an operation panel provided on the power transducer, the resistance value of the regenerative braking resistor for thermally consuming the rotational energy generated during motor deceleration. The power transducer performs the steps of: calculating the current which flows in the regenerative braking circuit from the resistance value setting; obtaining the generation loss of the power semiconductor in the regenerative braking circuit with the calculated current value; and determining the permissible duty factor of the power semiconductor from the obtained generation loss.

Claims

1. A power transducer which outputs alternating current power having a variable voltage and variable frequency, the power transducer comprising:

a converter for rectifying the AC voltage of an AC power supply to convert it to a DC voltage;

a DC intermediate circuit for having a regenerative braking circuit;

a drive circuit for driving the regenerative braking circuit; and

an inverter for converting the DC voltage of the converter to an AC voltage,

wherein the drive circuit compares a first permissible duty factor of a regenerative braking resistor of the regenerative braking circuit and a second permissible duty factor of a power semiconductor of the regenerative braking circuit.

2. The power transducer according to claim 1,

wherein the first permissible duty factor is able to be set.

3. The power transducer according to claim 1,

wherein the second permissible duty factor is obtained by a generating loss of the power semiconductor.

4. The power transducer according to claim 1,

wherein the generating loss is obtained by a detected voltage of the DC intermediate circuit.

5. The power transducer according to claim 1,

wherein when a cumulative operating time of the regenerative braking circuit reaches either the first permissible duty factor or the second permissible duty factor whichever is smaller, the power semiconductor is disconnected.

6. The power transducer according to claim 1,

wherein if both the first permissible duty factor and the second permissible duty factor are 100% or more, the drive circuit can operate continuously.

7. The power transducer according to claim 2,

wherein if the set first permissible duty factor is not greater than predetermined threshold, the driving circuit is prohibited to operate the regenerative braking circuit.