Power converter

• US 20030128561A1
• Filed: 11/05/2002
• Published: 07/10/2003
• Est. Priority Date: 03/30/2001
• Status: Active Grant

• Current Assignee: Mitsubishi Denki Kabushiki Kaisha (Mitsubishi Electric Corporation)
• Original Assignee: Mitsubishi Denki Kabushiki Kaisha (Mitsubishi Electric Corporation)
• Inventors: Azuma, Satoshi, Sanada, Kazunori
• Granted Patent: US 6,720,675 B2
• Time in Patent Office: Days
• US Class Current: 363/65
• CPC Class Codes: H02J 2207/20 Charging or discharging characterised by the power electronics converter
• CPC Class Codes: H02J 7/02 for charging batteries from ac mains by converters
• CPC Class Codes: H02M 1/32 Means for protecting converters other than automatic disconnection
• CPC Class Codes: H02M 7/219 in a bridge configuration
• CPC Class Codes: H02M 7/23 arranged for operation in parallel H02M7/2176 takes precedence

Abstract

In a power conversion apparatus having a plurality of AC power supplies, even if an abnormality occurs in any one of the AC power supplies and loads that are respectively connected to two capacitors are not balanced, voltages of the two capacitors are balanced.

In the power conversion apparatus of the present invention, in the case where an abnormality occurs in a first or second AC power supply, a first reactor is connected to a second reactor in series, a battery supplies energy to the two capacitors, and a current flowing to the first reactor is controlled by the series body of a first switching means. In this manner, there is controlled a voltage difference between the two capacitors.

Claims

1. A power conversion apparatus comprising:

a first AC/DC conversion means constructed by connecting a first AC power supply, a first reactor, and a series body of a first switching means in series;

a second AC/DC conversion means constructed by connecting a second AC power supply, a second reactor, and a series body of a second switching means in series;

two capacitors connected in series, an interconnection point of the two capacitors being connected to one end of each of the two AC power supplies, and the two capacitors receiving energy supplied by DC voltages obtained by the first and second AC/DC conversion means;

a load that is respectively connected to the two capacitors; and

a battery connected to the two capacitors that are connected in series,

wherein the power conversion apparatus comprises;

a first switch means that is connected between the first AC power supply and the first reactor, connects the first reactor to the first AC power supply if the first and second AC power supplies operate normally, and connects the first reactor to a connection point between the second reactor and the series body of the second switching means if one of the first and second AC power supplies operates abnormally;

a second switch means that is connected between the second AC power supply and the second reactor, connects the second reactor to the second AC power supply if the first and second AC power supplies operate normally, and connects the first reactor and the second reactor in series by connecting the second reactor to an interconnection point between the capacitors if one of the first and second AC power supplies operates abnormally; and

a control apparatus that controls a voltage difference between the two capacitors, wherein;

if the first and second AC power supplies operate normally, the control apparatus controls a current flowing to the first reactor using the series body of the first switching means to perform AC/DC conversion and controls a current flowing to the second reactor using the series body of the second switching means to perform AC/DC conversion; and

if one of the first and second AC power supplies operates abnormally, the control apparatus has the battery supply energy to the two capacitors and controls the current flowing to the first reactor using the series body of the first switching means.

2. A power conversion apparatus comprising:

a first AC/DC conversion means constructed by connecting a first AC power supply, a first reactor, and a series body of a first switching means in series;

a second AC/DC conversion means constructed by connecting a second AC power supply, a second reactor, and a series body of a second switching means in series;

two capacitors connected in series, an interconnection point of the two capacitors being connected to one end of each of the two AC power supplies, and the two capacitors receiving energy supplied by DC voltages obtained by the first and second AC/DC conversion means;

a load that is respectively connected to the two capacitors;

and a battery connected to the two capacitors that are connected in series,

wherein the power conversion apparatus comprises;

a first switch means that is connected between the first AC power supply and the first reactor;

a second switch means that is connected between the second AC power supply and the second reactor;

a third switch means that is connected between a connection point between the first switch means and the first reactor, and a connection point between the second reactor and the series body of the second switching means;

a fourth switch means that is connected between a connection point between the second switch means and the second reactor, and an interconnection point between the capacitors;

a series body of a fifth switch means and a first filter capacitor that is connected between a connection point between the third switch means and the first reactor, and an interconnection point between the capacitors;

a second filter capacitor that is connected between a connection point between the fourth switch means and the second reactor, and an interconnection point between the capacitors; and

a control apparatus that controls a voltage difference between the two capacitors, wherein;

if the first and second AC power supplies operate normally, the control apparatus turns on the first switch means, the second switch means, and the fifth switch means and turns off the third switch means and the fourth switch means, so that a current flowing to the first reactor is controlled using the series body of the first switching means to perform AC/DC conversion, a high-frequency current flowing to the first reactor is absorbed using the first filter capacitor, a current flowing to the second reactor is controlled using the series body of the second switching means to perform AC/DC conversion, and a high-frequency current flowing to the second reactor is absorbed using the second filter capacitor; and

if one of the first and second AC power supplies operate abnormally, the control apparatus turns off the first switch means and the second switch means, sets a voltage of the second filter capacitor to approximately zero through switching of the series body of the second switching means, sets a current of the first reactor to approximately zero through switching of the series body of the first switching means, turns on the third switch means and the fourth switch means, turns off the fifth switch means, connects the first reactor to a connection point between the second reactor and the series body of the second switching means, and connects the first reactor to the second reactor in series, so that energy is supplied to the two capacitors using the battery and a current flowing to the first reactor is controlled using the series body of the first switching means.

3. A power conversion apparatus comprising:

a first AC/DC conversion means constructed by connecting a first AC power supply, a first reactor, and a series body of a first switching means in series;

a second AC/DC conversion means constructed by connecting a second AC power supply, a second reactor, and a series body of a second switching means in series;

two capacitors connected in series, an interconnection point of the two capacitors being connected to one end of each of the two AC power supplies, and the two capacitors receiving energy supplied by DC voltages obtained by the first and second AC/DC conversion means;

a load that is respectively connected to the two capacitors; and

a battery connected to the two capacitors that are connected in series,

wherein the power conversion apparatus comprises;

a first switch means that is connected between the first AC power supply and the first reactor;

a second switch means that is connected between the second AC power supply and the second reactor;

a third switch means that is connected between a connection point between the first switch means and the first reactor, and a connection point between the second reactor and the series body of the second switching means;

a fourth switch means that is connected between a connection point between the second switch means and the second reactor, and an interconnection point between the capacitors;

a first filter capacitor that is connected between a connection point between the third switch means and the first reactor, and an interconnection point between the capacitors;

a second filter capacitor that is connected between a connection point between the fourth switch means and the second reactor, and an interconnection point between the capacitors; and

a control apparatus that controls a voltage difference between the two capacitors, wherein;

if the first and second AC power supplies operate normally, the control apparatus turns on the first switch means and the second switch means and turns off the third switch means and the fourth switch means, so that a current flowing to the first reactor is controlled using the series body of the first switching means to perform AC/DC conversion, a high-frequency current flowing to the first reactor is absorbed using the first filter capacitor, a current flowing to the second reactor is controlled using the series body of the second switching means to perform AC/DC conversion, and a high-frequency current flowing to the second reactor is absorbed using the second filter capacitor; and

if one of the first and second AC power supplies operate abnormally, the control apparatus turns off the first switch means and the second switch means, sets a voltage of the first filter capacitor to approximately zero through switching of the series body of the first switching means, sets a voltage of the second filter capacitor to approximately zero through switching of the series body of the second switching means, turns on the third switch means and the fourth switch means, connects the first reactor to a connection point between the second reactor and the series body of the second switching means, and connects the first reactor to a parallel connection body of the second reactor and the first filter capacitor in series, so that energy is supplied to the two capacitors using the battery and a current flowing to the first reactor is controlled using the series body of the first switching means.