Control device of neutral-point-clamped power converter apparatus, and control method of neutral-point-clamped power converter apparatus

• US 9,780,692 B2
• Filed: 10/12/2015
• Issued: 10/03/2017
• Est. Priority Date: 10/20/2014
• Status: Active Grant

• Current Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Original Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Inventors: Hasegawa, Ryuta, Ishizuki, Teruyuki, Fujita, Takashi
• Primary Examiner(s): Benitez, Gustavo Rosario
• Application Number:
  US14/880,550
• Publication Number:
  US 20160111975A1
• Time in Patent Office: 722 Days
• CPC Class Codes: H02M 1/0064 Magnetic structures combining different functions, e.g. storage, filtering or transformation
• CPC Class Codes: H02M 7/487 Neutral point clamped inverters

Abstract

According to one embodiment, there is provided a control device of a neutral-point-clamped power converter apparatus including a converter configured to convert current which were obtained by passing a d-axis current and a q-axis current of a rotating coordinate system through a filter having a time constant which is greater than an inverse number of a fundamental wave frequency of a three-phase currents, to three-phase currents, and a controller configured to calculate, based on the three-phase currents converted, a zero-phase voltage instruction value for controlling voltages into which a DC input voltage is divided at a neutral point, as an instruction value which is superimposed on three-phase voltage instruction values.

Claims

1. A control device of a neutral-point-clamped power converter apparatus, comprising:

a 3-phase/2-phase converter configured to convert three-phase currents flowing to three-phase loads, which are driven by the neutral-point-clamped power converter apparatus that is connected to a DC power supply having three potentials and is capable of outputting voltages of three levels, to a d-axis current and a q-axis current of a rotating coordinate system;

a 2-phase/3-phase current converter configured to convert a d-axis filter current and a q-axis filter current, which were obtained by passing the d-axis current and the q-axis current through a filter having a time constant which is greater than an inverse number of a fundamental wave frequency of the three-phase currents, to three-phase currents;

a neutral-point potential controller configured to calculate, based on the three-phase currents converted by the 2-phase/3-phase current converter, a zero-phase voltage instruction value for controlling voltages into which a DC input voltage is divided at a neutral point of the power converter apparatus, as an instruction value which is superimposed on three-phase voltage instruction values for the power converter apparatus; and

a 2-phase/3-phase voltage converter configured to convert a d-axis filter voltage instruction value and a q-axis filter voltage instruction value, which were obtained by passing a d-axis voltage instruction value and a q-axis voltage instruction value of the rotating coordinate system through a filter having a time constant which is greater than an inverse number of a fundamental wave frequency of the three-phase voltage instruction values, to three-phase voltage instruction values,

wherein the neutral-point potential controller is configured to calculate the zero-phase voltage instruction value by calculating a zero-phase voltage feedforward instruction value for controlling the voltages into which the DC input voltage is divided at the neutral point, based on the three-phase currents converted by the 2-phase/3-phase current converter and the three-phase voltage instruction values converted by the 2-phase/3-phase voltage converter.

2. The control device of the neutral-point-clamped power converter apparatus of claim 1, wherein the neutral-point potential controller is configured to calculate a zero-phase voltage feedback instruction value, based on a difference between a high-potential-side voltage and a low-potential-side voltage which are divided at the neutral point, and a sign of the zero-phase voltage feedforward instruction value, and configured to calculate the zero-phase voltage instruction value, based on the zero-phase voltage feedback instruction value and the zero-phase voltage feedforward instruction value.

3. A control device of a neutral-point-clamped power converter apparatus, comprising:

a 3-phase/2-phase converter configured to convert three-phase currents flowing to three-phase loads, which are driven by the neutral-point-clamped power converter apparatus that is connected to a DC power supply having three potentials and is capable of outputting voltages of three levels, to a d-axis current and a q-axis current of a rotating coordinate system;

a 2-phase/3-phase current converter configured to convert a d-axis filter current and a q-axis filter current, which were obtained by passing the d-axis current and the q-axis current through a filter having a time constant which is greater than an inverse number of a fundamental wave frequency of the three-phase currents, to three-phase currents;

a neutral-point potential controller configured to calculate, based on the three-phase currents converted by the 2-phase/3-phase current converter, a zero-phase voltage instruction value for controlling voltages into which a DC input voltage is divided at a neutral point of the power converter apparatus, as an instruction value which is superimposed on three-phase voltage instruction values for the power converter apparatus; and

a 2-phase/3-phase voltage converter configured to convert a d-axis filter voltage instruction value and a q-axis filter voltage instruction value, which were obtained by passing a d-axis voltage instruction value and a q-axis voltage instruction value of the rotating coordinate system through a filter having a time constant which is greater than an inverse number of a fundamental wave frequency of the three-phase voltage instruction values, to three-phase voltage instruction values,

wherein the neutral-point potential controller is configured to calculate the zero-phase voltage instruction value, based on

(a) signs of the three-phase currents converted by the 2-phase/3-phase current converter,

(b) signs of the three-phase voltage instruction values converted by the 2-phase/3-phase voltage converter, and

(c) a difference between a high-potential-side voltage and a low-potential-side voltage which are divided at the neutral point.

4. A control method of a neutral-point-clamped power converter apparatus which is connected to a DC power supply having three potentials and is capable of outputting voltages of three levels, the method comprising:

converting three-phase currents flowing to three-phase loads, which are driven by the power converter apparatus, to a d-axis current and a q-axis current of a rotating coordinate system;

converting a d-axis filter current and a q-axis filter current, which were obtained by passing the d-axis current and the q-axis current through a filter having a time constant which is greater than an inverse number of a fundamental wave frequency of the three-phase currents, to three-phase currents;

calculating, based on the converted three-phase currents, a zero-phase voltage instruction value for controlling voltages into which a DC input voltage is divided at a neutral point of the power converter apparatus, as an instruction value which is superimposed on three-phase voltage instruction values for the power converter apparatus;

converting a d-axis filter voltage instruction value and a q-axis filter voltage instruction value, which were obtained by passing a d-axis voltage instruction value and a q-axis voltage instruction value of the rotating coordinate system through a filter having a time constant which is greater than an inverse number of a fundamental wave frequency of the three-phase voltage instruction values, to three-phase voltage instruction values; and

calculating, based on the converted three-phase currents and the converted three-phase voltage instruction values, the zero-phase voltage instruction value by calculating a zero-phase voltage feedforward instruction value for controlling the voltages into which the DC input voltage is divided at the neutral point.

5. A control method of a neutral-point-clamped power converter apparatus which is connected to a DC power supply having three potentials and is capable of outputting voltages of three levels, the method comprising:

converting three-phase currents flowing to three-phase loads, which are driven by the power converter apparatus, to a d-axis current and a q-axis current of a rotating coordinate system;

converting a d-axis filter current and a q-axis filter current, which were obtained by passing the d-axis current and the q-axis current through a filter having a time constant which is greater than an inverse number of a fundamental wave frequency of the three-phase currents, to three-phase currents;

calculating, based on the converted three-phase currents, a zero-phase voltage instruction value for controlling voltages into which a DC input voltage is divided at a neutral point of the power converter apparatus, as an instruction value which is superimposed on three-phase voltage instruction values for the power converter apparatus;

converting a d-axis filter voltage instruction value and a q-axis filter voltage instruction value, which were obtained by passing a d-axis voltage instruction value and a q-axis voltage instruction value of the rotating coordinate system through a filter having a time constant which is greater than an inverse number of a fundamental wave frequency of the three-phase voltage instruction values, to three-phase voltage instruction values; and

calculating the zero-phase voltage instruction value, based on

(a) signs of the converted three-phase currents,

(b) signs of the converted three-phase voltage instruction values, and

(c) a difference between a high-potential-side voltage and a low-potential-side voltage which are divided at the neutral point.