Control device of AC motor

Patent metadata

Field	Value
Publication number	US-10608561-B2
Application number	US-201515741787-A
Country	US
Kind code	B2
Filing date	Jul 10, 2015
Priority date	Jul 10, 2015
Publication date	Mar 31, 2020
Grant date	Mar 31, 2020

Abstract

Provided is a control device of an AC motor, including: an inverter including a switching element; switching control means for controlling the switching element; and phase detection means for detecting a rotor phase of an AC motor, wherein the switching control means controls the switching element so that a voltage waveform of the inverter has half-wave symmetry in an interval of a width centering on a fundamental voltage phase of 180 deg±180 deg, the switching control means controls the switching element so that a harmonic voltage phase of the inverter becomes variable on the basis of a fundamental voltage-rotor phase difference which is a difference between a fundamental voltage phase and the rotor phase of the AC motor, and the switching control means controls the switching element so that a harmonic voltage amplitude of each order of the inverter is inversely proportional to the order.

First claim

The invention claimed is:

1. A control device of an AC motor, comprising:
an inverter including a switching element;
switching control means for controlling the switching element; and
phase detection means for detecting a rotor phase of an AC motor,
wherein the switching control means controls the switching element so that a voltage waveform of the inverter has half-wave symmetry in an interval of a width centering on a fundamental voltage phase of 180 deg±180 deg,
the switching control means controls the switching element so that a harmonic voltage phase of the inverter becomes variable on the basis of a fundamental voltage-rotor phase difference which is a difference between a fundamental voltage phase and the rotor phase of the AC motor,
the switching control means controls the switching element so that a harmonic voltage amplitude of each order of the inverter is inversely proportional to the order, and
the switching control means controls the switching element so that a (6n−1)-th harmonic voltage phase ϕ (6n−1) and a (6n+1)-th harmonic voltage phase ϕ (6n+1) of the inverter and the fundamental voltage-rotor phase difference ϕ satisfy (Expression 15), wherein
(6n −1)ϕ 6n−1 −(6n+1)ϕ 6n+1 −2ϕ=±2kπ  (Expression 15).

2. The control device of an AC motor according to claim 1 , wherein the switching control means controls the switching element so that a (6n−1)-th harmonic voltage amplitude V 6n−1 and a (6n+1)-th harmonic voltage amplitude (ϕ) 6n+1 of the inverter satisfy (Expression 14), wherein

V

6
⁢
n

-
1

6
⁢
n

-
1

=

V

6
⁢
n

+
1

6
⁢
n

+
1

.

(

Expression
⁢

⁢
14

)

3. The control device of an AC motor according to claim 1 , wherein the switching control means controls the switching element so as to reduce a parameter Q of (Expression 19) with respect to any integer N, wherein

Q
=

∑

n
=
1

N

⁢

⁢

{

(

V

6
⁢
n

+
1

6
⁢
n

+
1

)

2

+

(

V

6
⁢
n

-
1

6
⁢
n

-
1

)

2

-

2
⁢

V

6
⁢
n

-
1

⁢

V

6
⁢
n

+
1

Assignees

• Hitachi Ltd

Inventors

• Sumita Satoshi
• Iwaji Yoshitaka

Classifications

• H02M1/12 Primary

  Arrangements for reducing harmonics from AC input or output · CPC title

• H02P21/05

  specially adapted for damping motor oscillations, e.g. for reducing hunting · CPC title

• H02M7/53871

  with automatic control of output voltage or current · CPC title

• H02P29/50

  Reduction of harmonics · CPC title

• H02P6/16 Primary

  Circuit arrangements for detecting position · CPC title