Control apparatus and method for linear synchronous motor
The start timing of the pole position inference process of the linear motor installed vertically is delayed by a predetermined time after instruction of brake release. For example, from (1) increasing of the thrust instruction value of an ASR control system up to a predetermined value, (2) the movement (falling) distance of the moving part, or (3) the moving (falling) speed of the moving part, the release condition of the brake is detected and moreover after a predetermined time, the inference process of the pole position is started. The inference process of the pole position of a synchronous motor is fit to the release timing of a brake and a malfunction of the inference process and a runaway (falling in the vertical drive) of a moving part are prevented.
The present application claims priority from Japanese application serial no. 2004-249856, filed on Aug. 30, 2004, the content of which is hereby incorporated by reference into this application.
FIELD OF THE INVENTIONThe present invention relates to a control method and apparatus suitable for a linear synchronous motor and more particularly for a linear synchronous motor having a brake for stopping and retaining a moving part moving vertically.
BACKGROUND OF THE INVENTIONWhen driving a synchronous motor, pole position information is essential and mostly using a pole position detector, pole position information is obtained. However, for the purpose of saving the mounting space of the pole position detector and reducing the cost, an art requiring no pole position detector has been developed. For example, in Japanese Patent Laid-open No. 2003-88165, to a control apparatus for a synchronous motor formed as a speed control system, the same speed instruction is input twice, and the first instruction controls the motor only by a q-axial current, and the second instruction controls the motor only by a d-axial current. An art for inferring the pole position from a ratio of the magnitude between the q-axial current and the d-axial current when the speed is fixed is disclosed. Further, the patent document describes that when a runaway is detected during the inference process of the pole position, the speed instruction is instantaneously reduced substantially to zero, and in a motor having a brake, the brake is applied.
SUMMARY OF THE INVENTIONIn the prior art aforementioned, for example, in a system using a brake having a large operation delay, the inference process is started in the state that the brake is still being applied and a problem arises that the pole position cannot be inferred normally. Further, when the brake response is fast inversely, particularly in a system driving vertically, when the brake is released excessively earlier than the inference process of the pole position, a danger of falling (runaway) is accompanied. Moreover, since detection itself of falling (runaway) is executed during the inference process of the pole position, the detection of the falling (runaway) condition is delayed and a problem arises that an increase in the moving part falling (runaway) distance is caused.
In an aspect of the present invention, an inference process of the pole position is started at timing after a brake release instruction is issued to the brake for stopping and retaining the moving part of the synchronous motor.
In a preferred embodiment of the present invention, the release of the brake is instructed, and then after a predetermined time lag, the inference process of the pole position is started.
In another preferred embodiment of the present invention, using a speed control system (ASR control system) for the synchronous motor, a speed instruction ωM* thereof is practically reduced to 0, and when a thrust instruction value T* obtained by the ASR control system reaches a predetermined value Tr or after a lapse of a predetermined time after the instruction value reaches the predetermined value Tr, the inference process of the pole position is started.
Furthermore, in still another preferred embodiment of the present invention, when the movement (falling) distance θr of the moving part of the synchronous motor or the movement (falling) speed ωr reaches a predetermined value or after a lapse of a predetermined time after it reaches the predetermined value, the inference process of the pole position is started.
According to the preferred embodiments of the present invention, regardless of differences in the release time of an individual brake, the lubrication condition of the rail at each stop position, and the release time due to a change with time, the pole position inference process can be started simultaneously with release of the brake.
Further, failure in the pole position inference due to start of the inference process in the state that the brake is still being applied, excessive falling (movement) of the moving part due to impossible immediate start of the pole position inference process after release of the brake, and failure in the pole position inference due to it can be prevented.
Other objects and features of the present invention are described hereunder along with preferred embodiments.
BRIEF DESCRIPTION OF THE DRAWINGS
Hereinafter, the detailed embodiments of the present invention will be explained with reference to the accompanying drawings.
The brake release and pole position inference start timing controller 17 inputs a start signal ST and the movement distance θM of the moving part 6 or the moving speed ωM or the thrust instruction value T*. And, the controller 17 outputs the pole position inference process start flag ES and also a brake apply and release instruction BRK for a brake drive unit 20 and an ASR control system ON instruction ASRON for activating an ASR control system 21 enclosed by a dashed line. A 2-phase/3-phase coordinate conversion unit 19, using the post-correction electrical angle θE, converts the 2-phase instruction voltages Vq* and Vd* to 3-phase voltage instruction values Vu*, Vv* and Vw* and outputs them to the PWM inverter 2.
The control block drawn shows only the controllers activated in pole position inference and during the actual operation after end of the inference process, a control system composed of a large loop of a position servo control system not drawn is formed generally.
In the drive system, a rail 22 for linear movement of the moving part 6 is used also as a subject to which a brake shoe of a brake 18 is pressed at the time of braking. Buffers 231 and 232 at the upper and lower ends ease a shock when the moving part 6 reaches the ends of the moving area.
When starting the synchronous motor 1 having no pole position sensor, it is necessary to perform first the pole position inference process. As described above, unless the brake is released at appropriate timing, the inference process is started in the brake retaining state and a problem arises that a normal pole position inference process cannot be performed. Further, for example, in a system for driving vertically, when the brake is released extremely earlier than start of the process of the pole position inference means 16, falling (runaway) is caused and it is already described that a problem arises that the falling (runaway) distance is increased due to the detection delay. Therefore, the completion time of release of the brake 18 must coincide with the start time of the inference process of the pole position inference means 16.
This embodiment uses a means for providing a time adjustment parameter td1 and delaying the start of the pole position inference process by the designated time td1 for the brake release instruction. In the processing flow shown in
When the start process 30 is started, firstly, “ASR control system ON and brake release instruction issue” at Step 31 is executed unconditionally. At Step 31, an ASR control system ON signal ASRON is set in the on state and the ASR control system 21 enclosed by the dashed line in
As mentioned above, the processing flow shown in
As mentioned above, according to this embodiment, failure in the pole position inference due to start of the inference process in the brake retaining state, excessive falling of the moving part due to impossible immediate start of the pole position inference process after release of the brake, and failure in the pole position inference due to it can be prevented.
In the first embodiment, the time adjustment parameter td1 is provided and a means for delaying the start of the pole position inference process by the designated time td1 for the brake release signal is used. Therefore, it is effective when the time from issue of the brake release instruction to actual reduction of the brake retaining force Fbr to zero is always fixed. However, due to frictional wear of the brake shoe of the brake 18, a difference in the lubrication condition for each part of the rail 22 which is a subject to which the brake shoe is pressed, and variations in each article, the operation delay of the brake varies in the short term or the long term or with each article.
Therefore, in the second embodiment of-the present invention, after issue of the brake release instruction, the condition that the brake retaining force is reduced sufficiently is indirectly detected from the thrust instruction value T* and the start timing of the pole position inference process is decided.
The processing flow shown in
As mentioned above, the processing flow shown in
As mentioned above, according to this embodiment, regardless of differences in the release time of an individual brake, the lubrication condition of the rail at each stop position, and the release time due to a change with time, the pole position inference process can be started simultaneously with release of the brake. By doing this, failure in the pole position inference due to start of the inference process in the brake retaining state, excessive falling of the moving part due to impossible immediate start of the pole position inference process after release of the brake, and failure in the pole position inference due to it can be prevented.
In this embodiment, the same function as that of the embodiment shown in
As explained above, the processing flow shown in
As explained above, according to this embodiment, regardless of differences in the release time of an individual brake, the lubrication condition of the rail at each stop position, and the release time due to a change with time, the pole position inference process can be started simultaneously with release of the brake. By doing this, failure in the pole position inference due to start of the inference process in the brake retaining state, excessive falling of the moving part due to impossible immediate start of the pole position inference process after release of the brake, and failure in the pole position inference due to it can be prevented.
Further, at Step 71 shown in
In the aforementioned embodiment, after issue of the brake release instruction, the state that the brake retaining force is reduced sufficiently is detected indirectly from detection results of the falling distance or the falling speed in the ASR control system ON state, thus the start timing of the pole position inference process is decided. On the other hand, in this embodiment, the concerned state is detected using detection results of the falling distance or the falling speed in the ASR control system OFF state.
Similarly to the processing flow shown in
As explained above, the processing flow shown in
Here, how to decide the designated time td4 will be explained. Incidentally, how to decide the predetermined thrust value Tr is the same as that of the second embodiment and how to decide the predetermined movement distance θr or the predetermined moving speed ωr is the same as that of the third embodiment. In this embodiment, the pole position inference process is executed while changing only the designated time td4 and the designated time td4 obtaining a best result is adopted.
As explained above, according to this embodiment, regardless of differences in the release time of an individual brake, the lubrication condition of the rail at each stop position, and the release time due to a change with time, the pole position inference process can be started simultaneously with release of the brake. By doing this, failure in the pole position inference due to start of the inference process in the brake retaining state, excessive falling of the moving part due to impossible immediate start of the pole position inference process after release of the brake, and failure in the pole position inference due to it can be prevented.
Claims
1. A control apparatus for a synchronous motor comprising a PWM power converter for driving said synchronous motor, a brake for stopping and retaining a moving part of said synchronous motor, a brake drive unit for generating a drive signal for instructing said brake to apply or release, and pole position inference means for inferring a pole position of said synchronous motor, wherein said pole position inference means has timing control means for starting said inference process after instruction of brake release to said brake by said drive signal.
2. A control apparatus for a synchronous motor according to claim 1, wherein said timing control means has means for starting said inference process by said pole position inference means after a predetermined time from generation of said drive signal for instructing said brake release.
3. A control apparatus for a synchronous motor according to claim 1, wherein said pole position inference means has speed instruction means for generating a speed instruction of said moving part which is practically zero before starting said inference process and a speed controller for calculating a thrust instruction value from a relationship between said speed instruction and a speed detection value obtained from a movement distance signal of said moving part and controlling said power converter and said timing control means has means for starting said inference process by said pole position inference means after generation of said drive signal for instructing said brake release in accordance with excess of said thrust instruction value over a predetermined value.
4. A control apparatus for a synchronous motor according to claim 3, wherein after said thrust instruction value exceeds said predetermined value, furthermore after a lapse of a predetermined time, said pole position inference means has means for starting said inference process.
5. A control apparatus for a synchronous motor according to claim 1, wherein said pole position inference means has speed instruction means for generating a speed instruction of said moving part which is practically zero before starting said inference process and a speed controller for calculating a thrust instruction value from a relationship between said speed instruction and a speed detection value obtained from a movement distance signal of said moving part and controlling said power converter and said timing control means has means for starting said inference process by said pole position inference means after generation of said drive signal for instructing said brake release in accordance with excess of a movement distance of said moving part over a predetermined value.
6. A control apparatus for a synchronous motor according to claim 5, wherein after said movement distance exceeds said predetermined value, furthermore after a lapse of a predetermined time, said pole position inference means has means for starting said inference process.
7. A control apparatus for a synchronous motor according to claim 1, wherein said pole position inference means has speed instruction means for generating a speed instruction of said moving part which is practically zero before starting said inference process and a speed controller for calculating a thrust instruction value from a relationship between said speed instruction and a speed detection value obtained from a movement distance signal of said moving part and controlling said power converter and said timing control means has means for starting said inference process by said pole position inference means after generation of said drive signal for instructing said brake release when said thrust instruction value exceeds a predetermined value or a movement distance of said moving part exceeds a predetermined value, in accordance with excess of either of said values over said predetermined value.
8. A control apparatus for a synchronous motor according to claim 7, wherein after said either exceeds said predetermined value, furthermore after a lapse of a predetermined time, said pole position inference means has means for starting said inference process.
9. A control apparatus for a synchronous motor according to claim 1, wherein said pole position inference means has speed instruction means for generating a speed instruction of said moving part which is practically zero before starting said inference process and a speed controller for calculating a thrust instruction value from a relationship between said speed instruction and a speed detection value obtained from a movement distance signal of said moving part and controlling said power converter and said timing control means has means for starting said inference process by said pole position inference means after generation of said drive signal for instructing said brake release in accordance with excess of a movement distance of said moving part over a predetermined value when said speed controller is not functioned.
10. A control apparatus for a synchronous motor according to claim 1, wherein said pole position inference means has speed instruction means for generating a speed instruction of said moving part which is practically zero before starting said inference process and a speed controller for calculating a thrust instruction value from a relationship between said speed instruction and a speed detection value obtained from a movement distance signal of said moving part and controlling said power converter and said timing control means has means for starting said inference process by said pole position inference means after generation of said drive signal for instructing said brake release in accordance with excess of a movement distance and/or a speed of said moving part over a predetermined value.
11. A control method for a synchronous motor including a PWM power converter for driving said synchronous motor, a brake for stopping and retaining a moving part of said synchronous motor, a brake drive unit for generating a drive signal of said brake, and pole position inference means for inferring and calculating a pole position of said synchronous motor, comprising a step of instructing brake release to said brake and a step of starting a pole position inference process by said pole position inference means after instruction of said brake release.
12. A control method for a synchronous motor according to claim 11, further comprising a step of starting said inference process by said pole position inference means after a predetermined time from generation of said drive signal for instructing said brake release.
13. A control method for a synchronous motor according to claim 11, further comprising a step of generating a speed instruction of said moving part which is practically zero before starting said inference process by said pole position inference means, a step of calculating a thrust instruction value from a relationship between said speed instruction and a speed detection value obtained from a movement distance signal of said moving part and controlling said power converter, and a step of starting said inference process by said pole position inference means after generation of said drive signal for instructing said brake release in accordance with excess of said thrust instruction value over a predetermined value.
14. A control method for a synchronous motor according to claim 11, further comprising a step of generating a speed instruction of said moving part which is practically zero before starting said inference process by said pole position inference means, a step of calculating a thrust instruction value from a relationship between said speed instruction and a speed detection value obtained from a movement distance signal of said moving part and controlling said power converter, and a step of starting said inference process by said pole position inference means after generation of said drive signal for instructing said brake release in accordance with excess of a movement distance of said moving part over a predetermined value.
15. A control method for a synchronous motor according to claim 11, further comprising a step of generating a speed instruction of said moving part which is practically zero before starting said inference process by said pole position inference means, a step of calculating a thrust instruction value from a relationship between said speed instruction and a speed detection value obtained from a movement distance signal of said moving part and controlling said power converter, and a step of starting said inference process by said pole position inference means after generation of said drive signal for instructing said brake release when said thrust instruction value exceeds a predetermined value or a movement distance of said moving part exceeds a predetermined value, in accordance with excess of either of said values over said predetermined value.
16. A control method for a synchronous motor according to claim 15, further comprising a step of, after said either exceeds said predetermined value, furthermore after a lapse of a predetermined time, starting said inference process by said pole position inference means.
17. A control apparatus for a linear synchronous motor comprising a PWM power converter for driving said linear synchronous motor, a brake for stopping and retaining a moving part of said linear synchronous motor, a brake drive unit for generating a drive signal for instructing said brake to apply or release, and pole position inference means for inferring and calculating a pole position of said synchronous motor, wherein said pole position inference means has timing control means for starting said inference process after instruction of brake release to said brake by said drive signal.
18. A control apparatus for a linear synchronous motor according to claim 17, wherein said timing control means has means for starting said inference process by said pole position inference means after a predetermined time from generation of said drive signal for instructing said brake release.
19. A control apparatus for a linear synchronous motor according to claim 17, wherein said pole position inference means has speed instruction means for generating a speed instruction of said moving part which is practically zero before starting said inference process and a speed controller for calculating a thrust instruction value from a relationship between said speed instruction and a speed detection value obtained from a movement distance signal of said moving part and controlling said power converter and said timing control means has means for starting said inference process by said pole position inference means after generation of said drive signal for instructing said brake release in accordance with excess of said thrust instruction value over a predetermined value.
20. A control apparatus for a linear synchronous motor according to claim 17, wherein said linear synchronous motor is arranged so that said moving part vertically moves up and down and said timing control means has means for starting said inference process by said pole position inference means after generation of said drive signal for instructing said brake release in accordance with excess of a movement distance and/or a speed of said moving part over a predetermined value.
Type: Application
Filed: Aug 29, 2005
Publication Date: Mar 2, 2006
Inventors: Hirokazu Nagura (Hitachi), Hiromi Inaba (Hitachinaka), Toshifumi Yoshikawa (Hitachinaka), Hironori Ohashi (Narashino), Yuri Takano (Narashino), Masaki Sugiura (Tokyo)
Application Number: 11/215,553
International Classification: H02P 3/08 (20060101);