Power unit

• US 6,320,356 B1
• Filed: 02/17/2000
• Issued: 11/20/2001
• Est. Priority Date: 03/03/1999
• Status: Expired due to Term

• Current Assignee: Honda Giken Kogyo Kabushiki Kaisha (Honda Motor Company)
• Original Assignee: Honda Giken Kogyo Kabushiki Kaisha (Honda Motor Company)
• Inventors: Eguchi, Hiroyuki, Shimizu, Motohiro, Asai, Koichi
• Primary Examiner(s): Ponomarenko, Nicholas
• Application Number:
  US09/506,061
• Time in Patent Office: 642 Days
• Field of Search: 322/27, 322/28, 363/10, 363/161, 290/40.B
• US Class Current: 322/27
• CPC Class Codes: H02M 5/271 from a three phase input voltage

Abstract

A power unit is provided which is capable of controlling electric current to be supplied to a load connected to the power unit, in a flexible manner in dependence on a load condition. Postive and negative converters of a cycloconver are connected to three-phase output windings of a three-phase generator and connected in an antiparallel manner to each other for generating a single-phase alternating current to be supplied to the load. A firing angle control device causes the positive and negative converters to be alternately switched to operate every half a repetition period of the single-phase alternating current, to thereby cause the cycloconverter to generate the single-phase alternating current. A desired wave-forming circuit forms a desired waveform of a drive signal input to the firing angle control device, for causing the firing angle control device to drive the positive and negative converters, such that the output single-phase alternating current has a desired alternating current waveform. An amplitude control circuit changes a shape of the desired waveform in dependence on variation in the load so as to stabilize an output voltage of the cycloconverter. An amplitude-limiting circuit limits amplitude of the desired waveform to a smaller value when the output voltage of the cycloconverter becomes equal to or lower than a predetermined value.

Claims

1. A power unit comprising:

a generator having three-phase output windings;

a pair of variable control bridge circuits connected to said three-phase output windings of said generator and connected in an antiparallel manner to each other to form a cycloconverter for generating a single-phase alternating current to be supplied to a load;

a bridge drive circuit for causing said variable control bridge circuits to be alternately switched to operate every half a repetition period of said single-phase alternating current, to thereby cause said cycloconverter to generate said single-phase alternating current;

desired wave-forming means for forming a desired waveform of a drive signal input to said bridge drive circuit, for causing said drive bridge circuit to drive said variable control bridge circuits, such that said output single-phase alternating current has a desired alternating current waveform;

waveform-changing means for changing a shape of said desired waveform in dependence on variation in said load so as to stabilize an output voltage of said cycloconverter; and

amplitude-limiting means for limiting amplitude of said desired waveform to a smaller value when said output voltage of said cycloconverter becomes equal to or lower than a predetermined value.

2. A power unit according to claim 1, including comparison means for comparing between said output voltage of said cycloconverter and a desired output voltage, and

wherein said waveform-changing means changes said shape of said desired waveform from a sinusoidal one to a rectangular one when said load increases, based on results of comparison by said comparison means.

3. A power unit according to claim 2, wherein said waveform-changing means changes said shape of said desired waveform from said sinusoidal one to said rectangular one to an increasing degree as said load increases.

4. A power unit according to claim 2, wherein said amplitude-limiting means limits said amplitude of said desired waveform to an even smaller value when said load becomes nearly short-circuited.