Control method of PI controller

• US 7,085,611 B2
• Filed: 08/06/2003
• Issued: 08/01/2006
• Est. Priority Date: 10/23/2002
• Status: Expired due to Term

• Current Assignee: Samsung Electronics Co. Ltd.
• Original Assignee: Samsung Electronics Co. Ltd.
• Inventors: Yoo, Ho-sun, Seok, Jul-ki
• Primary Examiner(s): Paladini, Albert W.
• Assistant Examiner(s): Kosowski, Alexander
• Application Number:
  US10/634,788
• Publication Number:
  US 20040083249A1
• Time in Patent Office: 1,091 Days
• Field of Search: 700/41, 700/28, 318609-610, 388/906, 706/14
• US Class Current: 700/41
• CPC Class Codes: G05B 11/42 for obtaining a characteristic which is both proportional and time-dependent, e.g. P. I., P. I. D.
• CPC Class Codes: G05B 13/021 in which a variable is automatically adjusted to optimise the performance
• CPC Class Codes: G05B 13/024 in which a parameter or coefficient is automatically adjusted to optimise the performance

Abstract

A control method of a PI controller which selectively performs a proportional control and a proportional/integral control, the method includes Fourier transforming an output of the PI controller, calculating a spectral energy ratio of the transformed output of the PI controller of at a reference frequency for all frequency regions, performing the proportional control in response to the calculated spectral energy ratio exceeding a predetermined reference ratio, and the proportional/integral control in response to the spectral energy ratio being the predetermined reference ratio or less. Accordingly, a PI controller utilizing the method can easily detect a switching point between a proportional control and a proportional/integral control, independent of species and states of a system thereof.

Claims

1. A control method of a PI controller which selectively performs a proportional control and a proportional/integral control, the method comprising:

Fourier transforming an output of the PI controller;

calculating a spectral energy ratio of the transformed output of the PI controller at a reference frequency for all frequency regions; and

performing the proportional control in response to the calculated spectral energy ratio exceeding a predetermined reference ratio, and the proportional/integral control in response to the calculated spectral energy ratio being equal to the predetermined reference ratio or less.

2. The control method of the PI controller according to claim 1, wherein the reference frequency includes a corner frequency in a frequency response of a driving part controlled by the PI controller.

3. The control method of the PI controller according to claim 2, wherein the corner frequency f_T satisfies the following relationship:

$f_T=\frac{\mathrm{Bm}}{\mathrm{Jm}}$

in response to a transfer function (G(s)) of the driving part being

$\frac{1}{\mathrm{Jm}\times <br><br>s+\mathrm{Bm}},$

 

where B_m and J_m are friction and inertia affecting the driving part, respectively.

4. The control method of the PI controller according to claim 2, wherein the Fourier transforming of the output comprises discrete Fourier transforming the output of the PI controller.

5. The control method of the PI controller according to claim 2, wherein the Fourier transforming of the output comprises fast Fourier transforming the output of the PI controller.

6. The control method of the PI controller according to claim 4, wherein the spectral energy ratio (R) satisfies the following relationship:

$R={\int <br><br>}_{\mathrm{wc}}^{\mathrm{\infty <br><br>}}<br><br>{<br><br>X<br><br>\left(k\right)<br><br>}^2<br><br>d<br><br>w/{\int <br><br>}_0^{\mathrm{\infty <br><br>}}<br><br>{<br><br>X<br><br>\left(k\right)<br><br>}^2<br><br>d<br><br>w,k=0,1,2<br><br><br><br>\mathrm{\dots <br><br>}<br><br>$

where W_c is the reference frequency and X(k) is a Fourier transform in an Nth period of the output of the PI controller.

7. The control method of the PI controller according to claim 5, wherein the spectral energy ratio (R) satisfies the following relationship:

$R={\int <br><br>}_{\mathrm{wc}}^{\mathrm{\infty <br><br>}}<br><br>{<br><br>X<br><br>\left(k\right)<br><br>}^2<br><br>d<br><br>w/{\int <br><br>}_0^{\mathrm{\infty <br><br>}}<br><br>{<br><br>X<br><br>\left(k\right)<br><br>}^2<br><br>d<br><br>w,k=0,1,2<br><br><br><br>\mathrm{\dots <br><br>}$

where W_c is the reference frequency and X(k) is a Fourier transform in an Nth period of the output of the PI controller.

8. The control method of the PI controller according to claim 4, wherein the output of the PI controller in every control period is a discrete signal and a series of non-periodic values.

9. The control method of the PI controller according to claim 2, further comprising:

applying a velocity order value to operate the driving part; and

performing the proportional control in an initial transient state of the driving part.

10. A control method of a PI controller which selectively performs a proportional control and a proportional/integral control, the method comprising:

Fourier transforming an output of the PI controller; and

detecting a switching point between the proportional-control and the proportional/integral control by analyzing a spectral energy of the transformed output of the PI controller for a reference frequency.

11. The method according to claim 10, further comprising:

calculating a spectral energy ratio of the transformed output of the PI controller at the reference frequency for all frequency regions;

performing the proportional control in response to the calculated spectral energy ratio exceeding a predetermined reference ratio, and the proportional/integral control in response to the calculated spectral energy ratio being equal to the predetermined reference ratio or less.

12. The method according to claim 11, wherein the reference frequency includes a corner frequency in a frequency response of a driving part controlled by the PI controller.

13. The method according to claim 12, wherein the corner frequency f_T satisfies the following relationship:

$f_T=\frac{\mathrm{Bm}}{\mathrm{Jm}}$

in response to a transfer function (G(s)) of the driving part being

$\frac{1}{\mathrm{Jm}\times <br><br>s+\mathrm{Bm}},$

 

where B_m and J_m are friction and inertia affecting the driving part, respectively.

14. The method according to claim 12, wherein the spectral energy ratio (R) satisfies the following relationship:

$R={\int <br><br>}_{\mathrm{wc}}^{\mathrm{\infty <br><br>}}<br><br>{<br><br>X<br><br>\left(k\right)<br><br>}^2<br><br>d<br><br>w/{\int <br><br>}_0^{\mathrm{\infty <br><br>}}<br><br>{<br><br>X<br><br>\left(k\right)<br><br>}^2<br><br>d<br><br>w,k=0,1,2<br><br><br><br>\mathrm{\dots <br><br>}$

where W_c is the reference frequency and X(k) is a Fourier transform in an Nth period of the output of the PI controller.

15. A PI controller which selectively performs a proportional control and a proportional/integral control, comprising:

a proportional controller;

an integral controller; and

a switching part which switches the integral controller on/off, wherein the PI controller performs one of the proportional control and the proportional/integral control according to a spectral energy of a Fourier transformed output of the PI controller for a reference frequency.

16. The PI controller according to claim 15, wherein the PI controller performs the proportional control where a spectral energy ratio of the Fourier transformed output, which is calculated at the reference frequency for all frequency regions, exceeds a predetermined reference ratio, and performs the proportional/integral control where the spectral energy ratio is equal to the predetermined reference ratio or less.

17. The PI controller according to claim 16, wherein the reference frequency includes a corner frequency in a frequency response of a driving part controlled by the PI controller.

18. The PI controller according to claim 17, wherein the corner frequency f_T satisfies the following relationship:

$f_T=\frac{\mathrm{Bm}}{\mathrm{Jm}}$

in response to a transfer function (G(s)) of the driving part being

$\frac{1}{\mathrm{Jm}\times <br><br>s+\mathrm{Bm}},$

 

where B_m and J_m are friction and inertia affecting the driving part, respectively.

19. The PI controller according to claim 17, wherein the spectral energy ratio (R) satisfies the following relationship:

$R={\int <br><br>}_{\mathrm{wc}}^{\mathrm{\infty <br><br>}}<br><br>{<br><br>X<br><br>\left(k\right)<br><br>}^2<br><br>d<br><br>w/{\int <br><br>}_0^{\mathrm{\infty <br><br>}}<br><br>{<br><br>X<br><br>\left(k\right)<br><br>}^2<br><br>d<br><br>w,k=0,1,2$

where W_c is the reference frequency and X(k) is a Fourier transform in an Nth period of the output of the PI controller.

20. A driving system comprising:

a driving part;

a PI controller which selectively performs a proportional control and a proportional/integral control of the driving part according to a spectral energy of a Fourier transformed output of the PI controller for a reference frequency.

21. The driving system according to claim 20, wherein the PI controller performs the proportional control where a spectral energy ratio of the Fourier transformed output, which is calculated at the reference frequency for all frequency regions, exceeds a predetermined reference ratio, and performs the proportional/integral control where the spectral energy ratio is equal to the predetermined reference ratio or less.

22. The driving system according to claim 20, wherein:

the reference frequency includes a corner frequency in a frequency response of the driving part controlled by the PI controller, and

the corner frequency f_T satisfies the following relationship;

$f_T=\frac{\mathrm{Bm}}{\mathrm{Jm}}$

in response to a transfer function (G(s)) of the driving part being

$\frac{1}{\mathrm{Jm}\times <br><br>s+\mathrm{Bm}},$

 

where B_m and J_m are friction and inertia affecting the driving part, respectively.

23. The driving system according to claim 20, wherein the spectral energy ratio (R) satisfies the following relationship:

$R={\int <br><br>}_{\mathrm{wc}}^{\mathrm{\infty <br><br>}}<br><br>{<br><br>X<br><br>\left(k\right)<br><br>}^2<br><br>d<br><br>w/{\int <br><br>}_0^{\mathrm{\infty <br><br>}}<br><br>{<br><br>X<br><br>\left(k\right)<br><br>}^2<br><br>d<br><br>w,k=0,1,2<br><br><br><br>\mathrm{\dots <br><br>}$

where W_c is the reference frequency and X(k) is a Fourier transform in an Nth period of the output of the PI controller.

24. The driving system according to claim 20, further comprising an inverter which receives a torque order value signal of the PI controller, transforms the torque order value into an analog signal, and outputs the analog signal to the driving part.

25. The driving system according to claim 20, wherein the PI controller detects a switching point between the proportional control and the proportional/integral control, independent of species and states of the system.

26. A PI controller which selectively performs a proportional control and a proportional/integral control, comprising:

a proportional controller;

an integral controller; and

a switching part which switches the integral controller on/off, wherein the PI controller determines a switching point between the proportional control and the proportional/integral control, independent of species and states of a system having the PI controller, according to a spectral energy of a Fourier transformed output of the PI controller for a reference frequency.