Multilevel inverter

• US 8,159,840 B2
• Filed: 03/19/2009
• Issued: 04/17/2012
• Est. Priority Date: 03/20/2008
• Status: Active Grant

• Current Assignee: LS Industrial Systems Company Limited
• Original Assignee: LS Industrial Systems Company Limited
• Inventors: Yun, Hong Min
• Primary Examiner(s): Han, Jessica
• Application Number:
  US12/407,159
• Publication Number:
  US 20090237962A1
• Time in Patent Office: 1,125 Days
• Field of Search: 363 34- 37, 363 39- 43
• US Class Current: 363/39
• CPC Class Codes: H02M 1/0009 Devices or circuits for detecting current in a converter
• CPC Class Codes: H02M 1/0077 Plural converter units whose outputs are connected in series
• CPC Class Codes: H02M 5/458 using semiconductor devices only
• CPC Class Codes: H02M 7/49 Combination of the output voltage waveforms of a plurality of converters

Abstract

The present invention relates to a multilevel inverter comprising: a converter unit converting an inputted AC power source to a direct current (DC) power source; a film capacitor rectifying the DC power source converted by the converter unit; an inverter unit converting the rectified DC power source to a three-phase current in response to a pulse width modulation (PWM) control signal and outputting the current; a current detector detecting a current outputted from the inverter unit; a power cell main controller generating a voltage instruction and a voltage instruction using the detected current; and a PWM controller generating the pulse width modulation (PWM) control signal using the voltage instruction and frequency instruction.

Claims

1. A multilevel inverter, comprising:

a converter unit configured for converting an input alternating current (AC) power source to a direct current (DC) power source;

a film capacitor configured for rectifying the DC power source;

an inverter unit configured for;

converting the rectified DC power source to a three-phase current in response to a pulse width modulation (PWM) control signal; and

outputting the current;

a current detector configured for detecting the current output from the inverter unit;

a power cell main controller configured for generating a voltage instruction and a frequency instruction using the current detected by the current detector;

a PWM controller configured for generating the PWM control signal using the voltage instruction and frequency instruction; and

a phase shift transformer configured for outputting power to the input AC power source,

wherein the phase shift transformer has a predetermined inductance value, and

wherein a relation between the predetermined inductance value of the phase shift transformer and a capacitance value of the film capacitor is 1;

3.

2. The multilevel inverter of claim 1, further comprising an input transformer, configured for outputting a power source to the AC power source, the input transformer having a plurality of tabs at a secondary wiring side using a zigzag connection or an extended delta connection.

3. The multilevel inverter of claim 2, wherein the inverter unit includes one selected from the group consisting of metal oxide field effect transistors (MOSFET), insulated gate bipolar transistors (IGBT) and gate turn-off (GTO) thyristors.

4. The multilevel inverter of claim 1, wherein the inverter unit includes one selected from the group consisting of metal oxide field effect transistors (MOSFET), insulated gate bipolar transistors (IGBT) and gate turn-off (GTO) thyristors.

5. The multilevel inverter of claim 1, wherein a harmonic cut-off frequency by switching at the inverter unit is within a scope of ⅕

to ½

of a switching frequency utilized by the inverter unit.

6. The multilevel inverter of claim 5, wherein the harmonic cut-off frequency by the switching at the inverter unit is 200 Hz to 500 Hz when the switching frequency is 1 kHz.