TWI291518B - System and method for controlling servo motor - Google Patents

Abstract

The system and method for controlling servo motor consists of a servo motor, a driver, and a switch module. The driver supplies the power for the servo motor and accepts the revolution feedback signal of the servo motor for controlling. The switch module is used for changing the power connection between the driver and the servo motor. When the servo motor decreases its speed the switch module breaks both the power and the revolution feedback control between the servo motor and the driver. Moreover, this servo motor control system includes possibly another one speed reducing device by discharging the servo motor for speeding up the deceleration.

Description

1291518 IX. DESCRIPTION OF THE INVENTION: TECHNICAL FIELD OF THE INVENTION The present invention relates to a motor control system and method, and more particularly to a servo motor control system and method. [Prior Art] Fig. 1 is a schematic diagram of a conventional servo motor control system. A servo motor control system 10 includes a controller 11, a driver 丨2 and a _ servo motor 13. The controller 11 provides a control signal to the driver 12, and the driver 12 supplies power to the servo motor 13 according to the voltage magnitude of the control signal, thereby driving the servo motor 13 to rotate. The servo motor 13 converts its rotational speed into a signal while rotating and returns it to the drive 12 for feedback control. The servo motor 13 and the driver 12 are connected by a power line 14 and a drill-back signal line 15. The power line 14 transmits the power required to drive the servo motor 13, and the feedback signal line 15 transmits the φ speed feedback signal of the servo motor 13 to the driver 12. When the speed of the servo motor 13 is reduced (or braking), it is still equivalent to a generator because it is still rotating. Therefore, when the speed feedback control is performed, the large voltage and large current generated by the servo motor 丨3 are likely to be transmitted to The drive 12 burns it. SUMMARY OF THE INVENTION It is an object of the present invention to provide a servo motor control system and method that avoids burnout of a controller in the servo motor control system and that can perform precise servo motor speed control.

89506.DOC 1291518

To achieve the above object, the present invention discloses a servo motor control system including a servo motor, a driver and a switch module. The driver is used to provide power to the feeding motor and can be controlled by the speed feedback signal of the servo motor. The switch module is used to switch the power connection between the driver and the servo motor. When the servo motor accelerates or maintains a constant speed, the switch module electrically connects the driver and the servo motor (ie, supplies power to the servo motor), and performs rotational speed feedback control of the servo motor. The servo motor is different. When the servo motor is decelerating, the switch module makes an open circuit between the driver and the servo motor (ie, no power is supplied to the servo motor), and suspends the speed feedback control between the servo motor and the driver (ie, the servo motor does not Output speed feedback signal to the drive). The servo motor control system described above may further include a deceleration device for discharging the servo motor to accelerate the deceleration of the servo motor. When the feeding motor is decelerating, the switch module will electrically conduct the discharge between the servo motor and the speed reducing device. [Embodiment] Referring to Fig. 2, a servo motor control system 2 includes a 21, a driver 22, a controller 23, a switch module 24, and a ==29. The motor 21 is used to drive a load 30, such as a wafer boat loaded with a wafer in this embodiment. The switch module 24 includes a first changer 25 and a switcher 26 for switching electrical connections between the servo motor 21, the actuator 22 and the deceleration 29 . The reduction gear unit 29 includes a two-phase rectifier 27 and a resistor 28 for discharging the servo motor 21. The controller 23 is connected to the driver 22 and the first and second

The 506.DOC C34298 89506 1291518 switches 25, 26 are used to provide signals for control. The power lines 221 and 223 are connected to the driver 22 and the first switch 25 and the first switch 25 and the servo motor 21, respectively, for supplying power to the servo motor 21. A signal return line 222 is coupled to the servo motor 21 and the driver 22 for transmitting the speed feedback signal of the servo motor 21 to the driver 22 for control. One end of the two-phase rectifier 27 is electrically connected to the second switch 26, and the other end is connected in series with a resistor 28 for discharging. The controller 23 may be a programmable logic controller (programmable Logic c〇ntr〇Uer; PLC), and the first and first switches 25 and 26 may employ electromagnetic switches such as relays. When the servo motor 21 accelerates, the first switch 25 is switched to a position where the servo motor 21 and the driver 22 are closed (electrically conductive). At this time, the driver 22 can drive the driving power source through the power line (2). 223 is delivered to the servo motor 21. In addition, the second switch 26 is switched to a position where the servo motor 21 and the three-phase rectifier 27 are disconnected, and the servo motor 21 transmits its rotational speed feedback signal to the driver for feedback control, thereby adjusting Reach the required speed. When the child servo motor 21 wants to perform deceleration (or brake), the first switch 25 cuts off the power supply of the storage motor 21, and the servo motor 21 sends a power supply interrupted by the j feedback signal line 222. The signal informs the driver 22, and then the servo feedback of the servo horse is aborted (four), that is, the servo motor 2 1 no longer outputs a speed feedback signal to the driver 22. In addition, the second switch 26 is switched to a position such that the 祠 horse $ and the three-phase rectifying 詻 27 are electrically connected, so that the three-phase voltage of the servo motor 21 is controlled by the two-phase screed 27 Converted to two phases, and then connected in series to the three-phase

89506.DOC C34298 895〇6 1291518 The resistor 28 is discharged at the 27-end of the mud. Since the servo motor is still rotating when decelerating and is equivalent to a generator, if the above-described discharge mechanism is not used and the speed feedback control is turned off, the deceleration of the servo motor 21 is slow, and the driver 22 may be unable to withstand the The feedback signal line 222 transmits a large current and burns. For example, the output voltage of a typical PLC controller is approximately 〇_ι〇ν. It is assumed that the controller 23 outputs a 5 V signal to the driver 22, at which time the driver 22 will generate about 1 amp of amps to drive the servo motor 21 to accelerate to a speed of about 4000 revolutions per minute. If the speed of the servo motor η is to be reduced, the switch module 24 will cause the driver 22 and the servo motor 2 to be disconnected, the servo motor 21 and the three-phase rectifier 27 to be electrically connected for discharging, and the motor rotation speed is suspended. Give feedback. When the sensor (not shown) on the servo motor detects that the servo motor 21 has decelerated to a predetermined speed, 'a signal will be sent to the controller 23, and the switch module 24 is controlled by the controller 23. The electrical conduction between the driver 22 and the servo motor 21 is reformed to provide a suitable power source (e.g., 2V) to the servo motor 21. The function of the switch module 24 can be summarized as follows: when the servo motor 2i accelerates or maintains a constant speed, the switch module 24 forms a path to provide power to the servo motor 21. Conversely, when the servo motor 21 is decelerating, the switch module 24 cuts off the power path of the servo motor 21 and turns on the path in which the servo motor 21 is discharged. Actually, the switch module 24 of the present invention is not limited to the type and type, and can be used for the present invention as long as it can meet the above-described switching action. In practical applications, if the deceleration efficiency of the servo motor 21 is not considered, only

89506.DOC C34298 1291518 In order to prevent the drive 22 from being burned, the reduction gear 29 may be omitted. In the present embodiment, the servo stirrup 21 is applied to a wafer spin dryer to drive the wafer to rotate to achieve the effect of spin drying. The servo motor 21 is placed horizontally in response to the need to rotate the cassette for loading the wafer. In order to avoid the problem that the servo motor 21 is horizontally placed to cause deformation of the motor central shaft due to load during rotation, the servo motor 21 may employ a hollow servo motor. In addition, the servo motor 21 can be of a brushless type to avoid contamination due to dust generated by friction of the carbon brush. For the control flow of the present invention, it can be summarized as shown in the flow chart shown in FIG. When the servo motor starts to start, it supplies power to drive the servo motor and perform speed feedback control. When the servo motor will accelerate, the control voltage of the servo motor is increased and the speed feedback control is simultaneously performed to achieve the required speed. When the servo motor is decelerating, the servo motor is turned off and discharged, and the servo motor's speed feedback control is suspended. If the servo motor is to be turned off, the stop action will be directly performed. Otherwise, when the servo motor speed is reduced to the predetermined speed, the servo motor power supply is re-supplied and the speed feedback control is performed. The technical content and technical features of the present invention are disclosed above, but those skilled in the art can still make various substitutions and modifications without departing from the spirit and scope of the invention. Therefore, the scope of the present invention is not limited by the embodiment of the invention, and the invention is intended to cover various alternatives and modifications without departing from the scope of the invention. [Simple description of the map]

89506.DOC C34298 8 such as 6 1291518 The present invention will be described in accordance with the following drawings, wherein: Fig. 1 is a schematic view of a conventional servo motor control system; and Fig. 2 is a schematic view of the servo motor control system of the present invention; 3 shows the servo motor control flow of the present invention. [Main component symbol description] 10 Servo motor control system 11 Controller 12 Driver 13 Servo motor 14 Power cable 15 Feedback signal line

89506.DOC 10- C34298 8〇ς〇6

Claims (1)

1291518 X. Patent application scope: 1 · A servo motor control system, including: a motor; - the driver ' is used to supply the power of the servo motor, and can perform speed feedback control for the motor; Λ a switch module connecting the servo motor and the driver; wherein when the feeding motor is decelerating, the switch module cuts off the driver • (4) to the power supply of the feeding motor and stops the feeding motor and the driver Speed feedback control. 2. If you apply for a patent scope! The item of the motor control (4) is a deceleration device that discharges the servo motor. 3. The feeding motor control system of claim 2, wherein when the servo motor is decelerated, the switch module electrically connects the feeding motor and the subtracting device to discharge the servo motor. 4. The feeding motor control system of claim 2, wherein the φ speed reducing device comprises: - a three-phase rectifier 'for converting the three-phase voltage of the motor to two phases; and a resistor, string Connected to the three-phase rectifier for discharge. 5' The servo motor control system of claim 4, wherein the switch module comprises: a first switch for switching a power connection between the servo motor and the driver; and a first switch 詻' for switching The servo motor and the three-phase rectifier are connected to 89506.DOC • C34298 895〇6 -1 - 1291518. 6. The feeding motor control system of the patent application scope 1 includes a controller for controlling the driver and the switch module. 7. The servo motor control system of claim 6, wherein the controller is a programmable logic controller. Λ 8·If you order the patent scope! The ship's motor control system, wherein the feed motor is a hollow brushless servo motor. 9. For example, please apply for a patent! The ship's motor control system is applied to the wafer spin dryer. 10. A servo motor control method comprising the steps of: providing power to a feeding motor and performing rotational speed feedback control of the servo motor when the motor accelerates or maintains a constant speed; and when the feeding motor is decelerating, Turn off the power of the feeding motor and stop the motor speed feedback control. 11. The method of claim 1, wherein the servo horse reduction 1 comprises - the following steps: discharging the servo motor. 12. The servo motor control method of claim 1 (), wherein when the servo motor is decelerated to a predetermined speed, the method further comprises the following steps: re-providing the power of the servo motor and performing the servo motor Speed feedback control. 89506.DOC C34298 89506 -2 -