Servo control strategy and system for simultaneously eliminating counter- electromagnetic force (CEMF) and load torque disturbances

Patent metadata

Field	Value
Publication number	US-10411628-B2
Application number	US-201716304622-A
Country	US
Kind code	B2
Filing date	Jan 16, 2017
Priority date	Dec 27, 2016
Publication date	Sep 10, 2019
Grant date	Sep 10, 2019

Abstract

A servo control strategy and system eliminates CEMF and load torque disturbances. The total disturbance at electrical portion is estimated using extended state observer based on a nominal model of armature winding with measured voltage impressed across two endpoints of armature winding and the measured armature current. The total disturbance at electrical portion is partially counteracted by feed-forward compensation. The remaining CEMF disturbance is eliminated with the aid of armature current feedback regulation. The electrical disturbance can be totally eliminated at inner loop of the system by combining feed-forward control with current feedback control. The total disturbance at mechanical portion is estimated using extended state observer based on a nominal model of drive system with measured armature current and actual speed. The total disturbance at mechanical portion is partially counteracted by feed-forward compensation. The remaining load torque disturbance is eliminated with the aid of feedback regulation of speed.

First claim

The invention claimed is:

1. A servo control method for simultaneously eliminating counter electromagnetic force (CEMF) disturbance and load torque disturbance in a drive system, comprising:
adopting different disturbance estimation methods for CEMF disturbance and load torque disturbance; and
simultaneously eliminating the CEMF disturbance and the load torque disturbances including:
eliminating the CEMF disturbance for different speeds of a rotor of the drive system at an electrical portion through an inner loop of a cascade structure; and
eliminating the load torque disturbance caused by a load and load changes at a mechanical portion through an outer loop of the cascade structure,

wherein the CEMF disturbance at the electrical portion and the torque disturbance at the mechanical portion lie in different time scales,
wherein:
eliminating CEMF disturbance at the electrical portion includes building a state space model of armature winding of an armature of the drive system including the CEMF disturbance, establishing an extended state space model describing the electrical portion using the state space model of armature winding in combination with features of the CEMF disturbance, constructing a first extended state observer for estimating the CEMF disturbance using the extended state space model of the electrical portion and nominal values of parameters of the armature winding, and obtaining, by the first extended state observer, all electrical disturbances including the CEMF disturbance using voltage applied to two endpoints of the armature winding, an actual armature current, and a nominal model of the armature winding; and
eliminating the torque disturbance at the mechanical portion includes building a state space model of the drive system, establishing an extended state space model describing the mechanical portion using the state space model of the drive system in combination with features of the load torque disturbance, constructing a second extended state observer for estimating the load torque disturbance using the extended state space model of the mechanical portion and nominal values of parameters of the drive system, and obtaining, by the second extended state observer, information of all mechanical disturbances including the load torque disturbance using applied armature current, rotor speed from an encoder or a rotary resolver of the drive system, and a nominal model of the drive system.

2. The servo control method for simultaneously eliminating CEMF disturbance and load torque disturbance according to claim 1 , wherein the inner loop is established from a detected current and the first extended state observer; in the inner loop, current is regulated with a feedback control; and the CEMF disturbance is eliminated by feed-forward control.

3. The servo control method for simultaneously eliminating CEMF disturbance and load torque disturbance according to claim 1 , wherein deviation of a given current from actual armature current is sent to a current regulator; and output of the current regulator is added to the CEMF disturbance estimated by the first extended state observer to provide a given armature voltage.

4. The servo control method for simultaneously eliminating CEMF disturbance and load torque disturbance according to claim 3 , wherein the current regulator is an anti-integral saturation PI type controller, and a remained part of the CEMF disturbance is eliminated using of the PI type controller.

5. The servo control method for simultaneously eliminating CEMF disturbance and load torque disturbance according to claim 1 , wherein the outer loop is established from a detected rotor speed and the second extended state observer; in the outer loop, rotor speed is regulated with a feedback control; and the load torque disturbance is eliminated by feed-forward control.

6. The servo control method for simultaneously eliminating CEMF disturbance and load torque disturbance according to claim 5 , wherein deviation of a given speed from an actual speed is sent to a speed regulator; and output of the speed regulator is added to an equivalent current converted from the load torque disturbance estimated by the second extended state observer to provide given armature current.

7. A servo control system capable of simultaneously eliminating influence of counter electromagnetic force (CEMF) disturbance and influence of load torque disturbance in a drive system, comprising:
a cascade structure that includes an inner loop and an outer loop,
wherein the inner loop includes a current regulator and a first extended state observer; the first extended state observer estimates total CEMF disturbance at an electrical portion based on a nominal value model of a armature winding of an armature of the drive system using voltage applied to two endpoints of the armature and an actual armature current; and the first extended state observer performs feed-forward compensation in combination with the current regulator to eliminate the total CEMF disturbance;
the outer loop includes a speed regulator and a second extended state observer; the second extended state observer estimates total torque disturbance at a mechanical portion based on a nominal value model of the drive system using measured armature current and an actual speed of a rotor of the drive system; and the second extended state observer performs feed-forward compensation in combination with the speed regulator to eliminate the total load torque disturbance;
wherein the cascade structure controls the inner loop and the outer loop to simultaneously eliminate the CEMF disturbance and the load torque disturbance.

8. The control system according to claim 7 , wherein the nominal value model of the armature winding is obtained from nominal values of armature inductance and resistance; and
the nominal value model of the drive system is obtained from nominal values of total inertia and stick-slip damping coefficient of the drive system.

9. The control system according to claim 7 , wherein control parameters of the first extended state observer are determined according to desired cutoff frequency of current loop, armature inductance and resistance; and
control parameters of the second extended state observer are determined according to the desired cutoff frequency of speed loop, total inertia and stick-slip damping coefficient of the drive system.

Assignees

• Univ Shandong

Inventors

• Liu Jinbo

Classifications

• H02P23/12

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

• H02P6/182

  using back-emf in windings · CPC title

• H02P6/34 Primary

  Modelling or simulation for control purposes · CPC title

• H02P21/13

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

• H02P21/0003 Primary

  Control strategies in general, e.g. linear type, e.g. P, PI, PID, using robust control · CPC title