JPWO2008093485A1 - Motor control device - Google Patents

Abstract

Provided is a small, light, and low-cost motor control device that can support SEMI-F47. A converter unit (2) for converting an AC power source into a DC power source, a smoothing capacitor (5) connected in parallel with the DC power source, and an inverter unit (3) for converting the DC power source into an AC power source and driving a motor. A position / speed control unit (11) for generating a speed command from the position command and the motor position, and generating a first torque command from the speed command and the motor speed, and converting the torque command into a current command to generate a current command And a torque control unit (13) for generating a PWM gate signal from the motor current, and a voltage shortage when it is detected that the DC voltage of the DC power supply has dropped below a predetermined voltage. A voltage detector (14) that generates a warning signal and outputs it to the host controller, and generates a second torque command by limiting the first torque command to the torque limit signal of the host controller. Torque limiting unit to (12), comprising a.

Description

  The present invention relates to a motor control device capable of continuing operation even when a power source has an instantaneous power failure.

There is a standard called SEMI-F47 for semiconductor manufacturing equipment. SEMI-F47 is a standard related to the ability of devices and systems to operate normally even if an instantaneous power failure or input power supply voltage drops, and does not stop even if the input power supply voltage drops, and therefore no recovery operation is required. It is required to keep operating.
FIG. 5 is a diagram showing the power supply voltage and the operation duration time for the SEMI-F47. In FIG. 5, the vertical axis represents the ratio (%) of the rated voltage, and the horizontal axis represents the time (seconds) during which the motor is continuously operated. As can be seen from FIG. 5, in the SEMI-F47 standard, the time that the motor must continue to operate without stopping even if the input power supply voltage decreases is determined by the ratio to the rated voltage. For example,
(1) If the voltage drops to 50-70% of the rated ratio, it must be operated for at least 0.05 seconds.
(2) If the voltage drops to 70-80% of the rated ratio, it must be operated for at least 0.2 seconds.
(3) If the voltage drops to 80-90% of the rated ratio, it must be operated for at least 1 second.
(4) When the voltage drops by 90% or more in the rated ratio, it must be operated for at least 10 seconds.
It is stipulated.

Patent Document 1 discloses a motor control device that copes with a power supply voltage drop. When an instantaneous power failure or abnormal voltage drop occurs during motor operation, the motor and the load can be restored to the state before the power failure without impacting the control device, motor, and load so that stable motor operation can be performed. . The speed command signal and the motor speed signal are compared to obtain a current command signal, and the motor is controlled at a variable speed based on a comparison output signal between the current command signal and the motor current signal. If an instantaneous power failure or abnormal voltage drop occurs, the maximum value of the current command signal is decreased according to the abnormal time during the occurrence of power supply abnormality. In addition, after the power is restored, the current command signal maximum value is increased for a predetermined time to restore the state before the occurrence of the abnormality. Input the output of the DC power supply to the input resistance through a switch that closes the circuit during a power failure (during power failure) and use it as the input current of the integration capacitor of the integrator. The output signal of the integrator increases during integration, and after power recovery, a discharge resistor is connected through a switch closed by power recovery provided at both ends of the integration capacitor, and a discharge time constant determined by the integration capacitor and discharge resistance. It is configured to decrease by.
FIG. 6 shows a block diagram of a motor control apparatus that copes with SEMI-F47.
In FIG. 6, 1 is a three-phase AC power source, 2 is a converter unit, 3 is an inverter unit, 4 is a motor, 5 is a smoothing capacitor, and constitutes a main circuit. Further, 11 is a position / speed control circuit, 12 is a torque limiting unit, 13 is a torque control unit, 14 is a voltage detection unit, and 14 is a current detector, and constitutes a control circuit.
Reference numeral 20 denotes a host controller. The host controller 20 generates a position command for each control time and outputs it to the motor control device. The position control unit of the position / speed control circuit unit 11 generates a speed signal from the position command and the motor position signal. Further, the speed control unit of the position / speed control circuit unit 11 generates a first torque command from the speed command and the motor speed signal. The torque limiter 12 limits the first torque command with a settable maximum torque, and generates a second torque limit signal. The torque control unit 13 converts the second torque command into a current command, generates a voltage command from the current command and the motor current signal, and generates a PWM gate signal from the voltage command. The PWM gate signal supplies a voltage to the motor 4 by driving the power device of the inverter unit 3. The current detector 15 detects the current of the motor 4 and generates a motor current signal.

Next, the operation of the motor control device 60 when the power supply is abnormal will be described.
FIG. 7 is a time chart for explaining the operation of the motor control device of FIG. In FIG. 7, it is assumed that the input power source (A) is normal at time T0, is instantaneously shut off at time T1, and is restored at time T6. In the previous example corresponding to SEMI-F47, the DC voltage generated by the converter unit 2 is gradually reduced from time T1 at 280 V at time T1 to 165 V at time Tstop, and the alarm signal S15 is output to the host controller for control. Had stopped.
However, in order to make the motor control device 60 compatible with SEMI-F47, the capacity of the smoothing capacitor is changed from the small capacity C1 to the large capacity C2 (C1 <C2), so that the voltage drop is alleviated and the motor is not stopped even at time T6. It was. Referring to FIG. 7, when the smoothing capacitor is C1, the DC voltage drops at a steep slope α1 and reaches 165V to stop control, and at C2, it drops at a gentle slope α3 and does not reach 165V even at time T6. Therefore, it is possible to continue operation and satisfy SEMI-F47.
JP 58-58884 A

As described above, according to the conventional SEMI-F47-compliant motor control device, the operation can be continued without stopping the motor even if the power supply voltage decreases, but a large-capacity smoothing capacitor is required. There has been a problem that the apparatus is large, heavy, and expensive.
The present invention was made to solve these problems, and can be operated without stopping the motor when the power supply voltage is lowered without using a large-capacity smoothing capacitor, and is small and lightweight. Therefore, an object is to provide a low-cost motor control device.

In order to solve the above problems, the following configuration is adopted.
The invention according to claim 1 is a converter unit that converts an AC power source into a DC power source, a smoothing capacitor connected in parallel with the DC power source, an inverter unit that converts the DC power source into an AC power source and drives a motor, A position / speed control unit that generates a speed command from the position command and the motor position, and generates a first torque command from the speed command and the motor speed, and converts the torque command into a current command to generate a current command. And a torque control unit that generates a PWM gate signal from the motor current, and a voltage shortage warning signal when it is detected that the DC voltage of the DC power supply has dropped below a predetermined voltage. And a second torque by limiting the first torque command to the torque limit signal of the host controller. A torque limiting unit for generating a decree and is characterized in that it comprises.
According to a second aspect of the present invention, in the motor control device according to the first aspect, the host controller generates a predetermined torque limit signal and outputs it to the motor control device when an undervoltage warning signal is input. It is.
According to a third aspect of the present invention, in the motor control device according to the first aspect, when the voltage detection unit detects that the DC voltage has dropped below a predetermined voltage, it generates a voltage shortage warning signal and outputs it to the host controller. At the same time, a torque limit signal is generated and output to the torque limiter.
According to a fourth aspect of the present invention, in the motor control device according to the first aspect, when a load is applied due to an external factor, the torque limit signal is set to be equal to or greater than the holding torque.
According to a fifth aspect of the present invention, in the motor control device according to the first aspect, the torque limit signal divides the DC voltage into arbitrary N-stage levels, and sets a torque limit time corresponding to the level of the DC voltage. It is characterized by providing.

  With the above configuration, even if the main circuit power supply voltage is lowered, it is detected that the voltage is lowered to a predetermined voltage, and the torque is limited to reduce the energy consumption in the motor. A smoothing capacitor is not required, and a small, lightweight, and low-cost motor control device can be provided.

It is a block diagram of the motor control apparatus which concerns on Example 1 of this invention. 3 is a time chart for explaining the operation of the motor control device according to the first embodiment. It is a block diagram of the motor control apparatus which concerns on Example 2 of this invention. 6 is a time chart for explaining the operation of the motor control device according to the second embodiment. It is a diagram explaining the content of SEMI-F47. It is a block diagram of the conventional motor control apparatus. It is a time chart explaining operation | movement of the conventional motor control apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 AC power supply 2 Converter part 3 Inverter part 4 Motor 5 Smoothing capacitor 10 Motor controller 11 which concerns on Example 1 of this invention Position / speed control part 12 Torque control part 13 Torque control part 14 Voltage detection part 15 Current detector 16 Position Detector 20 Host controller 100 Motor control apparatus according to Embodiment 2 of the present invention

  Hereinafter, Embodiment 1 and Embodiment 2 of the present invention will be described in detail with reference to the drawings.

Embodiment 1 of the present invention will be described in detail with reference to FIGS.
FIG. 1 is a block diagram of a motor control apparatus according to Embodiment 1 of the present invention.
In FIG. 1, 1 is a three-phase AC power source, 2 is a converter unit, 3 is an inverter unit, 4 is a motor, 5 is a smoothing capacitor, and constitutes a main circuit. A motor control device 10 according to the present invention includes a control circuit in addition to the main circuit. The control circuit includes a position / speed control 11, a torque limit diagram 12, a torque control unit 13, a voltage detection unit 14, and a current detector 15. Note that 16 is a position detector, and 20 is a host controller.
The voltage detection unit 14 receives a DC voltage detection signal S11 and monitors the power supply, and outputs an abnormality detection signal S12 to the host controller 20 if abnormal. In addition, a predetermined voltage that is an undervoltage threshold is set by a parameter, and when the DC voltage drops below the predetermined voltage, an undervoltage warning S12 is generated and output to the host controller 20. Furthermore, the voltage detection unit 14 can select whether the upper controller 20 or the servo control device 10 executes torque limitation at the time of undervoltage by parameter setting.

Next, the schematic operation of position / speed control will be described.
The motion control host controller 20 generates a position command S1 and outputs it to the motor control device. The position control unit of the position / speed control circuit unit 11 generates a speed signal from the position command S1 and the motor position signal S6. The speed control unit of the position / speed control circuit unit 11 generates the first torque command S2 from the speed command and the motor speed signal. The torque limiter 12 limits the first torque command S2 with the torque limit signal S13 of the host controller 20, and generates a second torque limit signal S3. The torque control unit 13 converts the second torque command into a current command, generates a voltage command from the current command and the motor current signal S5, and generates a PWM gate signal S4 from the voltage command. The PWM gate signal drives the power device of the inverter unit 3 to supply a voltage to the motor 4 and cause a current to flow. The current detector 15 detects the current of the motor 4 and generates a motor current signal S5.

Next, the operation of the motor control device according to the first embodiment will be described.
FIG. 2 is a time chart for explaining the operation of the motor control device.
In FIG. 2, it is assumed that the input power source (A) is normal at time T0, instantaneously shut off at time T1, and restored at time T6. The DC voltage generated by the converter unit 2 gradually decreases from time T1 at 280V at time T1, and generates an undervoltage warning signal S12 at time T2 when it reaches 200V and outputs it to the host controller 20. Upon receiving the undervoltage warning signal, the host controller 20 enters the undervoltage warning state mode at time T3, and outputs a torque limit signal to the motor control device at time T4. When receiving the torque limit signal, the torque limiter generates a second torque command by limiting the first torque command with the torque limit signal. When the torque limit is applied, the motor consumes less energy, and the DC voltage that has fallen at the steep slope α1 will drop at the slow slope α2 (α1> α2) from time T5 and drop to 165 V or less at time T6. There is no alarm stop. Since the power supply returns to the normal state at time T6, the DC voltage also increases, and when the voltage becomes 200 V or more at time T7, the output of the undervoltage warning signal is stopped. The host controller 20 exits from the undervoltage warning state mode at time T8 and cancels the torque limit signal at time T9. The motor control device returns to a normal operation state when the torque limit signal is canceled. Since the control power is supplied from the uninterruptible power supply, it does not become abnormal even when the power is abnormal. In addition, it is desirable to consider a delay of one cycle of the power supply in terms of voltage detection function. Furthermore, on the vertical axis, care should be taken not to limit the torque below the holding torque of the brake in order to prevent the falling phenomenon.

Thus, according to the present invention, paying attention to the fact that the gradient of the main circuit DC voltage drop is determined by the output power of the motor, the gradient is made gentle by reducing the motor output power by limiting the torque when the voltage drops. The time until the motor stops reaching 165V can be lengthened. Accordingly, it is possible to continue operation at a low torque without stopping the motor easily and at low cost, and SEMI-F47 can be supported. In addition, it is not necessary to use a large-capacity smoothing capacitor only when the power supply is abnormal, and it is possible to prevent the apparatus from becoming large, heavy, and expensive.
In addition, there is a strong demand for semiconductor manufacturing users to avoid expensive materials because they will not only take a long time to recover when the motor stops once the power supply voltage drops. Accordingly, it is desired to develop a system that continues to rotate the motor even if the output power of the motor is slightly reduced, and the present invention can meet this demand easily and at low cost.

Next, a second embodiment of the present invention will be described with reference to FIGS.
In FIG. 3, the same reference numerals as those in FIG. The second embodiment differs from the first embodiment in that the host controller 20 generates the torque limit signal S13 in the first embodiment, whereas the voltage detector 14 generates the torque limit signal S14 in the second embodiment. That is. When the DC voltage drops below a predetermined value, the voltage detector 14 generates an undervoltage warning signal S12 and outputs it to the host controller 20 and simultaneously generates a torque limit signal S14 and outputs it to the torque limiter 12. On the other hand, the host controller 20 that has received the voltage shortage warning signal S12 does not give a position command that consumes power to the motor control device, or issues a deceleration command to regenerate the motor power to the motor control device. Do not consume power.

Next, the operation of the motor control device according to the second embodiment will be described with reference to FIG.
It is assumed that the input power source (A) is normal at time T0, instantaneously cut off at time T1, and restored at time T6. The DC voltage generated by the converter unit 2 gradually decreases from time T1 at 280 V at time T1. The voltage detection unit 14 generates an undervoltage warning signal S12 at time T2 when 200 V is exceeded and outputs it to the host controller 20 and simultaneously generates a torque limit signal S14 and outputs it to the torque limiter 12. The subsequent operation is the same as in the first embodiment.

  As described above, according to the second embodiment, it is possible to continue the operation at a low torque without stopping the motor by limiting the torque when the power supply voltage is lowered, without a host controller. In addition, SEMI-F47 can be handled easily and at low cost. Therefore, it is not necessary to use a large-capacity smoothing capacitor when the power is shut off, and the apparatus can be prevented from becoming large, heavy, and expensive.

  It is also possible to limit the torque by providing an arbitrary N-stage (N = 1, 2, 3,...) Level of the torque limit signal according to the DC voltage drop level. Furthermore, it is possible to provide torque limit and speed limit by providing an N stage level torque limit signal and a speed limit signal according to the DC voltage level. Depending on the state of the power supply, the operation speed of the system can be reduced and the operation can be continued in conjunction with the host system.

  According to the present invention, even if the main circuit power supply voltage is lowered, it is detected that the voltage is lowered to a predetermined voltage, and the torque is limited to reduce the energy consumption in the motor. Since the operation can be continued even if an instantaneous power failure occurs, it can be applied to general industrial uses other than the semiconductor industry. In applications where the line speed is allowed to be reduced, the effect is further enhanced if the rotational speed is lowered.

Claims (5)

A main circuit comprising a converter unit for converting an AC power source into a DC power source, a smoothing capacitor connected in parallel with the DC power source, and an inverter unit for converting the DC power source into an AC power source and driving a motor,
A position / speed control unit that generates a speed command from the position command and the motor position, and generates a first torque command from the speed command and the motor speed; a PWM gate that converts the torque command into a current command and converts the current command and the motor current In a motor control device comprising a control circuit comprising a torque control unit that generates a signal,
When detecting that the DC voltage of the DC power supply has dropped below a predetermined voltage, a voltage detection unit that generates a voltage shortage warning signal and outputs it to the host controller, and limits the first torque command to the torque limit signal of the host controller. And a torque limiter that generates the second torque command.   The motor controller according to claim 1, wherein the host controller generates a predetermined torque limit signal and outputs the torque limit signal to the motor controller when an undervoltage warning signal is input.   The voltage detector generates a voltage shortage warning signal when detecting that the DC voltage has dropped below a predetermined voltage, and outputs it to the host controller, and also generates a torque limit signal and outputs it to the torque limiter. The motor control device according to claim 1.   2. The motor control device according to claim 1, wherein when a load is applied due to an external factor, the torque limit signal is set to a holding torque or more.   The torque limit signal divides the DC voltage into arbitrary N levels (N = 1, 2, 3,...), And provides a torque limit level and a torque limit time corresponding to the level of the DC voltage. The motor control device according to claim 1.

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