1. Field of the Invention
The present invention relates to a method for controlling operating of a Switched Reluctance Motor (SRM), particularly, to a method for controlling operating of a SRM to drive the SRM according to a phase under the normal condition in case a noise is inputted from the outside.
2. Description of the Background Art
FIG. 1 is a schematic view showing 6/4 and 12/8 structures of a conventional Switched Reluctance Motor (SRM) in accordance with the conventional art.
As shown in FIG. 1, a conventional SRM is composed of a SRM having 6/4 and 12/8 structures and a circuit for operating the SRM and detecting a current flowing in the respective phases applied to a winding in the SRM. Here, the circuit will be described with reference to FIG. 2 as follows.
FIG. 2 is a circuit diagram for detecting a current applied to the conventional SRM.
As shown in FIG. 2, the circuit for detecting the current applied to the SRM includes switching devices Q1 to Q6 connected to respective windings LA, LB and LC in the SRM in a row, diodes D1 to D6 connected to the respective windings LA, LB and LC in a row and resisters Rd1, Rd2 and Rd3 for sensing the current flowing in the switching devices Q2, Q4 and Q6.
On the other hand, there are two methods for detecting the noise inputted to a position sensor in the SRM. The one method is sensing a speed change of the SRM and the other method is sensing the current flowing in the SRM. Hereinafter, the two methods will be described.
First, in case of sensing the noise inputted to the position sensor in the SRM from the outside as a speed change of the SRM, the phase applied to the winding in the SRM is shifted until the SRM becomes a normal Revolutions Per Minute (RPM). At this time, the phase is shifted in the method that the B phase is turned on in case the A phase must be turned on and the C phase is turned on in case the B phase must be turned on (A phase-B phase, B phase-C phase and C phase-A phase). Namely, under the condition that the SRM is operated normally, the RPM rotates normally by excitating a magnetic phase and in case a noise is inputted, the RPM is decreased. At this time, the phase is shifted to the next phase after judging whether there is an error by sensing the RPM. Here, the process is performed repeatedly until the RPM is operated normally.
On the other hand, in case the noise is sensed by detecting the current applied to the SRM, a phase current flowing in respective phases applied to the winding in the SRM is detected. Whether the phases are excitated or not is judged by comparing the detected value and the standard value. In case the magnetic phase is not excitated, the SRM is operated shifting the phases one by one.
FIG. 3 is a view illustrating in case a sensor signal is correctly recognized or in case the sensor signal is incorrectly recognized when the current applied to the SRM is detected.
As shown in FIG. 3, the increased amount of current is appeared to be different according to the sensor signal outputted from the position sensor for detecting the position of the rotor in the SRM. Namely, the current values in case the sensor signal is recognized correctly and in case the sensor signal is recognized incorrectly are very different. At this time, it is judged whether the sensor signal is recognized correctly or not by comparing the current value detected in operating the SRM and the standard current value. If the sensor signal is recognized incorrectly, the SRM is operated shifting the phases one by one and the operation is repeated until the sensor signal is recognized normally.
However, in the conventional method for controlling operating of the SRM, the standard value must be determined sensing the speed of the SRM or the current flowing in the SRM to sense the input of the noise. The standard RPM or standard current value must be set in case the operation speed of the SRM is changed or the voltage applied to the SRM is changed by external circumstances. Particularly, in case the speed of the SRM must be changed according to the status of load, there occurs a problem that setting of the standard value (a standard RPM or a standard current value) is difficult.
Also, in the conventional method for controlling operating of the SRM, there occurs a problem that the SRM is stopped if inertia of load is small in case the SRM is operated shifting the phase when the noise is inputted in the SRM.
Also, in the conventional method for controlling operating of the SRM, the three current sensing resisters must be connected to the circuit for detecting the current applied to the SRM to sense the current flowing in the SRM and accordingly, a plurality of analogue/digital ports must be allotted thus to increase the load in a microcomputer (not shown).
Therefore, an object of the present invention is to provide a method for controlling operating of a Switched Reluctance Motor (SRM) capable of operating the SRM according to a phase under the normal condition in case a noise is inputted to a position sensor in the SRM from the outside.
To achieve these and other advantages and in accordance with the purpose of the present invention, as embodied and broadly described herein, there is provided a method for controlling operating of a SRM having a rate of poles of a stator and a rotor as 6/4 or 12/8, including the steps of generating a sensor signal at every mechanical angle to sense whether the respective phases applied in the SRM are commutated and operating the SRM by consequently turning on each applied phase in SRM at the point of detecting a rising edge of the sensor signal and turning off the phase at the point of detecting a falling edge of the next sensor signal.
The foregoing and other objects, features, aspects and advantages of the present invention will become more apparent from the following detailed description of the present invention when taken in conjunction with the accompanying drawings.