Jian Zhi Chen

Address:

9525 SW Fwy, Houston, TX 77074

VIN:

JTMZF33V195005237

Make:

TOYOTA

Model:

RAV4

Year:

2009

Address:

7002 Brody Ln, Houston, TX 77083

VIN:

1GCGG25VX71236721

Make:

CHEVROLET

Model:

EXPRESS CARGO

Year:

2007

US Patent:

7492058, Feb 17, 2009

Filed:

Feb 19, 2007

Appl. No.:

11/676460

Inventors:

Jian Chen - Katy TX, US

Assignee:

Toshiba International Corp. - Houston TX

International Classification:

H02J 7/00
H02J 9/00
H02J 3/00
G05D 3/12

US Classification:

307 64, 307 82, 700286

Abstract:

In the preferred embodiments, an uninterruptible power supply has multiple UPS modules connected in parallel. Each module has an AC-DC-AC converter and a subcontroller for controlling the operation of the AC-DC-AC converter. A single current sensor senses a total aggregate current flowing from all the modules. Each subcontroller can detect an input voltage, output voltage, and DC bus voltage of each module. Also, each module has unique operating characteristics (e. g. , efficiency curve and a responsiveness coefficient K). Operating characteristics data are stored in a memory accessible by the subcontroller. Based on the voltage and current measurements, and the operating characteristics of each module, the subcontrollers perform calculations to determine a DC bus voltage target (unique for each module) that results in each module providing the same output current. Accordingly, only one current sensor is needed, and, consequently, the cost of the UPS device can be reduced.