Virtual voltage injection-based speed sensor-less driving control method for induction motor

Patent metadata

Field	Value
Publication number	US-11081992-B2
Application number	US-201816772160-A
Country	US
Kind code	B2
Filing date	May 25, 2018
Priority date	May 15, 2018
Publication date	Aug 3, 2021
Grant date	Aug 3, 2021

Abstract

A virtual voltage injection-based speed sensor-less driving control method for an induction motor is provided. First, a virtual voltage signal is injected into a motor flux linkage and rotating speed observer so that there is a difference between an input of the motor flux linkage and rotating speed observer and a command input of the motor. Then, based on any type of the motor flux linkage and rotating speed observer, a motor flux linkage rotation angle and a motor rotor speed are estimated, and the induction motor is driven to run normally with a certain control strategy (such as vector control). Then, based on a signal designed according to this method and injected only into the motor flux linkage and rotating speed observer, the induction motor driven by a speed sensor-less control system for the induction motor may be ensured to output 150% of a rated torque when running at a motor low synchronous rotating speed and a motor zero synchronous rotating speed, and the stability thereof may be kept for a long time.

First claim

What is claimed is:

1. A virtual voltage injection-based speed sensor-less driving control method for induction motor, wherein in the method, based on an existing speed sensor-less drive system for induction motor, a virtual voltage injection module is added between stator voltage command input values u sα and u sβ and flux linkage observer stator voltage input values u* sα and u* sβ of a motor in an αβ coordinate system, or a virtual voltage injection module is added between stator voltage command input values u sd and u sq and flux linkage observer stator voltage input values u* sd and u* sq of the motor in a dq coordinate system, and the method comprises the following steps:
S1. calculating k based on a parameter of an induction motor, wherein k is a proportional relationship in the virtual voltage injection module;
S2. multiplying the stator voltage command input values u sα and u sβ of the motor in the αβ coordinate system by the proportional relationship k respectively to obtain the flux linkage observer stator voltage input values u* sα and u* sβ in the αβ coordinate system; or multiplying the stator voltage command input values u sd and u sq of the motor in the dq coordinate system by the proportional relationship k respectively to obtain the flux linkage observer stator voltage input values u* sd and u* sq in the dq coordinate system;
the operation is equivalent to injecting u sα_inj and u sβ_inj on the basis of u sβ and u sβ , wherein u sα_inj =(k−1)u sα u sβ_inj =(k−1)u sβ to satisfy u* sα =u sα_inj +u sα =ku sα , u* sβ =u* sβ_inj +u* sβ =ku sβ ,
in the formula, u sα_inj is a virtual voltage injection value under an α-axis,
and u sβ_inj is a virtual voltage injection value under a β-axis;
or the operation is equivalent to injecting u sd_inj and u sq_inj on the basis of
u sd and u sq , wherein u sd_inj =(k−1) u sd u sq_inj =(k−1)u sq to satisfy u* sd =u sd_inj =u sd =ku sd , u* sq =u sq_inj +u* sq =ku sq ,
in the formula, u sd_inj is a virtual voltage injection value under a d-axis, and
u sq_inj is a virtual voltage injection value under a q-axis;
S3. constructing a dynamic mathematical model of a flux linkage observer based on u* sα and u* sβ or u* sd and u* sd ;
S4. observing an induction motor rotor speed {circumflex over (ω)} r using a rotating speed observer and observing a rotation angle θ of a rotor flux linkage using the flux linkage observer based on the dynamic mathematical model of the flux linkage observer:
S5. implementing a control of speed sensor-less induction motor rotating speed and torque by using the observed rotor speed {circumflex over (ω)} r for a rotating speed PI adjustment module and the flux linkage observer and using the observed rotor flux linkage rotation angle θ for a 2-phase synchronous rotation coordinate/2-phase static coordinate conversion module;
wherein the αβ coordinate system is a 2-phase static coordinate system and the dq coordinate system is a 2-phase synchronous rotation coordinate system;
wherein step S5 comprises the following steps:
S 501 , performing a rotating speed PI control after taking a difference with a corresponding rotating speed command ω* r using the observed induction motor rotor speed {circumflex over (ω)} r as a feedback value of the rotating speed PI adjustment module;
S 502 , using the observed flux linkage rotation angle θ for a coordinate conversion calculation in a 2-phase synchronous rotation coordinate/2-phase static coordinate conversion module;
S 503 , using an output i* sq of the rotating speed PI adjustment module as a command of a q-axis current PI adjustment module and using an output i* sd of a flux linkage current command given module as a command of a d-axis current PI adjustment module; inputting induction motor two-phase currents i U and i V obtained by sampling via a current sensor to a 3-phase static coordinate/2-phase static coordinate conversion module, and then outputting i s to the 2-phase synchronous rotation coordinate/2-phase static coordinate conversion module, and lastly obtaining a d-axis current i sd and a q-axis current i sq in the 2-phase synchronous rotation coordinate system, and performing a current PI control after using the obtained d-axis current and q-axis current as feedback values of a d-axis current PI regulator and a q-axis current PI regulator respectively and taking a difference with corresponding flux linkage current commands i* sd and i* sq ;
S 504 , inputting outputs u sd and u sq of the d-axis and q-axis current PI adjustment modules to the 2-phase synchronous rotation coordinate/2-phase static coordinate conversion module, which converts a motor input voltage command in the 2-phase synchronous rotation coordinate system to a motor input voltage command u s in the 2-phase static coordinate system;
S 505 , outputting u s to a voltage space vector pulse width modulation module to generate a switching signal for controlling switching devices SA,SB,SC, thereby achieving an object of controlling induction motor speed and torque.

2. The driving control method of claim 1 , wherein the virtual voltage injection module is implemented by an adder, a multiplier, or a combination thereof.

3. The driving control method of claim 1 , wherein a calculation formula of the proportional relationship k in step S1 is as follows:

k
=

p
⁢

R
r

⁢

L
m

L
r

+
1

wherein p is a constant greater than zero, and is obtained based on a stability degree of induction motor speed and torque; R r is an induction motor rotor resistance; L m is an induction motor mutual inductance; and L r is an induction motor rotor side inductance.

4. The driving control method of claim 1 , wherein the dynamic mathematical model of the flux linkage observer constructed based on u* sα and u* sβ in step S3 is as follows:

{

d
dt

⁢

x
→

^

=

A
1

⁢

x
→

^

+

Assignees

• Univ Huazhong Science Tech
• Harbin Inst Technology

Inventors

• Sun Wei
• Xu Dianguo

Classifications

• H02P21/04 Primary

  specially adapted for very low speeds · CPC title

• H02P21/13 Primary

  Observer control, e.g. using Luenberger observers or Kalman filters · CPC title

• H02P21/18

  Estimation of position or speed · CPC title

• H02P27/12

  pulsing by guiding the flux vector, current vector or voltage vector on a circle or a closed curve, e.g. for direct torque control · CPC title

• H02P21/28

  Stator flux based control · CPC title