Direct AC power converting apparatus

• US 9,065,353 B2
• Filed: 04/20/2007
• Issued: 06/23/2015
• Est. Priority Date: 04/24/2006
• Status: Active Grant

• Current Assignee: Daikin Industries Ltd
• Original Assignee: Daikin Industries Ltd
• Inventors: Sakakibara, Kenichi
• Primary Examiner(s): Berhane, Adolf
• Assistant Examiner(s): LEE III, HENRY E
• Application Number:
  US12/298,060
• Publication Number:
  US 20090086515A1
• Time in Patent Office: 2,986 Days
• Field of Search: 363 34- 37, 363/55, 363/40, 363/44, 363/45, 363 47- 50, 363/52, 363 5601- 5612, 363 60- 62
• US Class Current: 1/1
• CPC Class Codes: H02M 1/342 Active non-dissipative snubbers
• CPC Class Codes: H02M 1/346 Passive non-dissipative snubbers
• CPC Class Codes: H02M 5/4585 having a rectifier with controlled elements
• CPC Class Codes: H02P 3/18 for stopping or slowing an ac motor
• CPC Class Codes: Y02B 70/10 Technologies improving the efficiency by using switched-mode power supplies [SMPS], i.e. efficient power electronics conversion e.g. power factor correction or reduction of losses in power supplies or efficient standby modes

Abstract

Capacitors are connected in series between a first DC link section and a second DC link section when the capacitors are charged by a regenerative current derived from an inverter section. During discharge, as first, second switching circuits turn on, the capacitors are discharged with those capacitors connected in parallel between a first DC link section and a second DC link section.

Claims

1. A direct AC power converting apparatus comprising:

a converter section configured to convert a three-phase AC input voltage into a DC voltage that includes AC voltage components superimposed on DC voltage components;

an inverter section configured to convert the DC voltage from the converter section into a specified three-phase AC output voltage;

a first DC link section on an anode side and a second DC link section on a cathode side that are configured to connect the converter section and the inverter section to each other; and

a clamp circuit connected between the first DC link section and the second DC link section, the clamp circuit having at least two capacitance elements, wherein the AC input voltage is converted into the AC output voltage by the converter section and the inverter section without generating any smoothed DC voltage,

a first period when the capacitance elements are charged by a regenerative current derived from the inverter section and a second period when the capacitance elements are discharged are sequentially repeated, and

in the clamp circuit,

the capacitance elements are connected in series between the first DC link section and the second DC link section when the capacitance elements are charged by a regenerative current derived from the inverter section, and

the capacitance elements are connected in parallel between the first DC link section and the second DC link section when the capacitance elements are discharged.

2. The direct AC power converting apparatus as claimed in claim 1. wherein

the clamp circuit includes

a first capacitance element having one end connected to the first DC link section;

a second capacitance element having one end connected to the second DC link section;

a diode element connected in forward direction between another end of the first capacitance element and another end of the second capacitance element;

a first switching circuit connected between a connecting point of the diode element and the second capacitance element and the first DC link section, the first switching circuit turning on during discharge of the second capacitance element; and

a second switching circuit connected between a connecting point of the diode element and the first capacitance element and the second DC link section, the second switching circuit turning on during discharge of the first capacitance element.

3. The direct AC power converting apparatus as claimed in claim 1, wherein

the clamp circuit includes

a first capacitance element having one end connected to the first DC link section;

a second capacitance element having one end connected to the second DC link section;

a first diode element connected in forward direction between another end of le first capacitance element and another end of the second capacitance element;

a second diode element connected in reverse direction between a connecting point of the first diode element and the second capacitance element and the first DC link section; and

a third diode element connected in reverse direction between a connecting point of the first diode element and the first capacitance element and the second DC link section.

4. The direct AC power converting apparatus as claimed in claim 1, wherein

the clamp circuit includes

a first capacitance element having one end connected to the first DC link section;

a first diode element having one end connected to another end of the first capacitance element;

a second capacitance element having one end connected to another end of the first diode element;

a second diode element having one end connected to another end of the second capacitance element;

a third capacitance element having one end connected to another end of the second diode element and having another end connected to the second DC link section;

a third diode element connected in reverse direction between a connecting point of the first diode element and the first capacitance element and the second DC link section;

a fourth diode element connected in reverse direction between a connecting point of the first diode element and the second capacitance element and the first DC link section;

a fifth diode element connected in reverse direction between a connecting point of the second diode element and the second capacitance element and the second DC link section;

and

a sixth diode element connected in reverse direction between a connecting point of the second diode element and the third capacitance element and the first DC link section, wherein

the first diode element is connected in forward direction between the first capacitance element and the second capacitance element, and

the second diode element is connected in forward direction between the second capacitance element and the third capacitance element.