Electric power converting apparatus

• US 5,587,891 A
• Filed: 06/07/1995
• Issued: 12/24/1996
• Est. Priority Date: 06/04/1992
• Status: Expired due to Term

• Current Assignee: Hitachi, Ltd.
• Original Assignee: Hitachi, Ltd.
• Inventors: Nakata, Kiyoshi, Suzuki, Masato, Yasuda, Kouji, Toyota, Eiichi, Terunuma, Mutsuhiro, Nakamura, Kiyoshi, Tanamachi, Tokunosuke, Tsutsui, Yoshio
• Primary Examiner(s): Wong, Peter S.
• Assistant Examiner(s): Riley, Shawn
• Application Number:
  US08/479,030
• Time in Patent Office: 566 Days
• Field of Search: 363/41, 363/42, 363/43, 363/95, 363/98, 318/811, 388/811
• US Class Current: 363/41
• CPC Class Codes: B60L 2200/26 Rail vehicles
• CPC Class Codes: B60L 2210/20 AC to AC converters
• CPC Class Codes: B60L 2220/12 Induction machines
• CPC Class Codes: B60L 9/22 polyphase motors
• CPC Class Codes: H02M 7/487 Neutral point clamped inverters
• CPC Class Codes: H02M 7/5395 by pulse-width modulation
• CPC Class Codes: Y02T 10/72 Electric energy management in electromobility

Abstract

An electric power converting apparatus equipped with a 3-level PWM control in which the output voltage can be continuously and smoothly controlled from zero to a maximum voltage. The electric power converting apparatus includes a multi-pulse generating unit arranged for a dipolar modulation, a unipolar modulation, and an overmodulation; a 1-pulse generating means; and a unit for controlling the transfer operation among these modulation regions.

Claims

1. An electric power converting apparatus for converting a DC voltage into AC phase voltages having 3-leveled potentials, for driving an AC motor, said electric power converting apparatus comprising:

first means for receiving the DC voltage and producing therefrom an AC voltage in a unipolar modulation mode, to produce a series of output pulses such that each half period of the fundamental wave of an output AC voltage of said electric power converting apparatus is represented by a series of single polarity pulses;

second means for receiving the DC voltage and producing therefrom an AC voltage in an overmodulation mode, to produce a series of output pulses such that each half period of the fundamental wave of the output AC voltage of said electric power converting apparatus is represented by a series of single polarity pulses filled up in the center by a plurality of pulses of the single polarity;

third means for receiving the DC voltage and producing therefrom an AC voltage in a 1-pulse mode, to produce an output pulse such that a half period of the fundamental wave of the output AC voltage of said electric power converting apparatus is represented by a single pulse having the same polarity as said half period; and

output means for switching among said first, second, and third, means to change the modulation mode among the unipolar modulation mode, the overmodulation mode, and the 1-pulse mode.