Apparatus for controlling the parallel operation of an A-C output converter for a commercial power source including a circuit for simulating output current for test purposes

• US 4,703,193 A
• Filed: 08/28/1986
• Issued: 10/27/1987
• Est. Priority Date: 08/30/1985
• Status: Expired due to Term

• Current Assignee: Mitsubishi Denki Kabushiki Kaisha (Mitsubishi Electric Corporation)
• Original Assignee: Mitsubishi Denki Kabushiki Kaisha (Mitsubishi Electric Corporation)
• Inventors: Kawabata, Takao
• Primary Examiner(s): Shoop, Jr., William M.
• Assistant Examiner(s): Logan, Sharon D.
• Application Number:
  US06/901,273
• Time in Patent Office: 425 Days
• Field of Search: 307/66, 307/64, 307/45, 307/46, 307/83, 307/87, 323/246, 323/244, 323/241
• US Class Current: 307/66
• CPC Class Codes: H02J 9/062 for AC powered loads

Abstract

An apparatus for controlling the parallel operation of a commercial power source and an A-C output converter in which the A-C output converter of a variable voltage and a variable frequency is connected and operated in parallel with the commercial power source; an impedance element is provided between said commercial power source and an output terminal of at least one phase which represents an internally generated voltage of the A-C output converter, the impedance element being connected in parallel with an output impedance of a main circuit of the A-C output converter, and the voltage and frequency of the A-C output converter being controlled so that a current that flows through said impedance element assumes a predetermined value.

Claims

1. An apparatus for controlling the parallel operation of a commercial power source and an A-C output converter of a variable voltage and a variable frequency said apparatus comprising simulated output current detecting circuit means including an impedance element provided between said commercial power source and an output terminal of at least one phase which represents an internally generated voltage of the A-C output converter, said impedance element being connected in parallel with an output impedance of a main circuit of the A-C output converter which is connected at an output to the commercial power source, said simulated output current detecting circuit means including means operable independently of the main circuit to selectively activate said detecting circuit means and cause a simulated output current to flow through said impedance element, and means for controlling the voltage and frequency of the A-C output converter so that the simulated output current that flows through said impedance element assumes a predetermined value.

2. An apparatus for controlling the operation of a commercial power source and an A-C output converter in which the A-C output converter of a variable voltage and a variable frequency is connected and operated in parallel with the commercial power source, said apparatus comprising an impedance element provided between the commercial power source and an output terminal of at least one phase which represents an internally generated voltage of the A-C output converter, said impedance element comprising an insulating transformer and a reactor, said impedance element being connected in parallel with an output impedance of a main circuit of the A-C output converter, said apparatus further comprising simulated output current detecting circuit means including means for combining a representative value of the internally generated voltage and a voltage of the commercial power source and causing a simulated output current to flow through said impedance element, said insulating transformer and said reactor having an impedance angle substantially equal to an impedance angle of the output impedance of the main circuit, and means for controlling the voltage and frequency of the A-C output converter so that the simulated output current that flows through said impedance element assumes a predetermined value.

3. An apparatus for controlling the parallel operation of a commercial power source and an A-C output converter in which the A-C output converter of a variable voltage and a variable frequency is connected and operated in parallel with the commercial power source, said apparatus comprising an impedance element provided between the commercial power source and an output terminal of at least one phase which represents an internally generated voltage of the A-C output converter, said impedance element being connected in parallel with an output impedance of a main circuit of the A-C output converter, said apparatus further comprising simulated output current detecting circuit means including means for causing a simulated output current to flow through said impedance element, means for decomposing the current that flows through said impedance element into a component that changes mainly with change of voltage and a component that changes mainly with change of phase, and means for controlling the voltage and the frequency of the A-C output converter so that the respective components assume predetermined values and the simulated output current that flows through said impedance element assumes a predetermined value.--;

4. An apparatus for controlling the parallel operation of a commercial power source and an A-C output converter in which the A-C output converter of a variable voltage and a variable frequency is connected and operated in parallel with the commercial power source, said apparatus comprising an impedance element provided between said commercial power source and an output terminal of at least one phase which represents an internally generated voltage of the A-C output converter, said impedance element being connected in parallel with an output impedance of a main circuit of the A-C output converter to the commercial power source via a transformer, and means for controlling the voltage and the frequency of the A-C output converter so that a simulated output current that flows through said impedance element assumes a predetermined value.