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A vector control system using a neutral‐point‐clamped voltage‐source pwm inverter
Author(s) -
Ogasawara Satoshi,
Sawada Tadashi,
Abe Keiichi,
Akagi Hirofumi
Publication year - 1993
Publication title -
electrical engineering in japan
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.136
H-Index - 28
eISSN - 1520-6416
pISSN - 0424-7760
DOI - 10.1002/eej.4391130509
Subject(s) - control theory (sociology) , inverter , voltage , controller (irrigation) , capacitor , pulse width modulation , voltage source , harmonic , voltage controller , voltage divider , transformer , computer science , engineering , electrical engineering , physics , control (management) , acoustics , artificial intelligence , agronomy , voltage droop , biology
This paper describes a vector control system of an induction machine using a neutral‐point‐clamped voltage‐source inverter (NPC‐VSI) that is one of the double series‐connected inverters. The NPC‐VSI is able to output five‐level step‐shaped line‐to‐line voltage without output transformers or reactors, and it may reduce harmonic currents corresponding to torque ripples. However, the NPC‐VSI has a problem in that excessive high voltage is applied to switching devices when a neutral point of two dc capacitors of the NPC‐VSI varies from the center of the dc link voltage, because the neutral point is floating. This paper proposes also a current controller to which the space vector theory is applied. This can reduce harmonic currents to one‐fourth those of a conventional voltage‐source inverter using six switching devices, and regulate the neutral point potential within a preset range. To simplify the current controller, information about voltage space vectors is given from the vector controller to the current controller. The validity of the current controller is confirmed by a prototype using an induction machine of 2.2 kW.