JP5370724B2 - Motor control device with safe stop circuit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a motor controller equipped with a safety shutdown circuit, which can improve safety by allowing a higher-level device outside the motor controller to more quickly and surely detect an abnormal state of the safety shutdown circuit before the motor controller is driven. <P>SOLUTION: A safety shutdown circuit 150 is equipped with external motor shutdown switches 7 and 8, a plurality of three-state buffers 5 and 6 for shutting down a PWM signal in linkage with the motor shutdown switches 7 and 8, and monitor circuits 151 and 152 so configured as to allow a higher-level device to determined an abnormality of the safety device. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to a motor control device used in a robot system, a machine tool device, and the like, and more particularly to a motor control device that detects a failure of a safety stop circuit provided for realizing high safety.

In general, motor control devices must reliably prevent motor runaway due to breakage or failure due to some factors such as circuits, etc. Also, from the dangerous operation of the machine moving parts fastened to the motor due to motor runaway There is a technical problem of reducing the machine risk and making the machine safer to protect people.
In order to solve this general technical problem, the motor control device according to the first prior art is related to a safety device for an inverter control motor used as a power source for a machine, and in particular, reliably prevents motor runaway. It is related to a safety device for an inverter-controlled motor that is capable of providing a contactor between a motor and an inverter that controls electric power supplied to the motor, and when the motor is locked out, the contactor is opened. It is characterized in that contactor control means for cutting off power supply to the motor is provided "(for example, Patent Document 1).
In addition, the motor control device in the second prior art is “related to an emergency stop device for a motor in a robot, a machine tool, various industrial machines, etc., in particular, even if a short circuit occurs between the contacts of the emergency stop switch due to some failure. Even if the cable connecting the relay etc. is broken, it is related to the emergency stop device that reliably performs the emergency stop of the motor. Even if the cable connecting the switch, relay, etc. breaks, the emergency stop of the motor is surely performed, and if an abnormality such as a failure occurs, the power supply voltage will not be applied to the motor again. The object is to obtain an emergency stop device for a motor that allows a user to identify an abnormal location "(for example, Patent Document 2).

FIG. 4 is a schematic configuration diagram of a motor control device in the first prior art. In the figure, 100 is an inverter, 102 is a DC bus, 103 is a smoothing capacitor, 104 to 109 are power transistors, 110 is a contactor, 111 is a motor, 112 is a base drive circuit, 113 is an inverter on / off command circuit, and 114 is a current command device. 115 is an inverter on / off request signal synthesis circuit, 116 is a host controller, and 117 is a contactor open / close signal generation circuit.
When the contactor 110 is inserted between the motor 111 and the inverter 100 and there is a release request from the lockout switch to the contactor, the sub-inverter on / off request signal is turned off and the inverter on / off request signal is changed to off. Turn off. Thereafter, the contactor drive coil drive signal is turned off, the contactor 110 is opened via the contactor drive coil 118, the motor current is cut off, and the free run is stopped.

In order to solve the above problem, the present invention is as follows.
According to a first aspect of the present invention, there is provided a gate drive circuit for driving an inverter unit that converts direct current into alternating current in response to a motor drive command from an external host device, and PWM generation for generating a PWM signal to be given to the gate drive circuit A motor control device comprising a circuit, a safety stop circuit interposed between the gate drive circuit and the PWM generation circuit, wherein the safety stop circuit includes a plurality of external motor stop switches and the plurality of motor stops A plurality of three-state buffers that cut off the PWM signal in conjunction with a switch, and a monitoring circuit configured so that the host device can determine an abnormality of the safety device itself with a single output signal. It is what.
According to a second aspect of the present invention, the monitoring circuit according to the first aspect of the present invention is configured such that the monitoring circuit according to the first aspect inputs one logic circuit that inputs at least one output signal of each of the plurality of three-state buffers, and the one logic. comprising a one semiconductor element for on-off operation based on the output signals by inputting the output signal of the circuit, wherein the host system, before driving the motor controller, one output signal of said one semiconductor element Based on the above, the abnormality of the safety device itself can be determined.
According to a third aspect of the invention, the host device according to the first aspect of the invention is based on a combination of an on / off state of the plurality of motor stop switches and an on / off state of one output signal of the monitoring circuit. Thus, the abnormality of the safety device itself can be determined.
According to a fourth aspect of the present invention, the safety stop circuit according to the first aspect of the present invention can hold the state where the plurality of motor stop switches are opened.
According to a fifth aspect of the present invention, the safety stop circuit according to the first aspect of the present invention includes two of the three-state buffers in series and two of the motor stop switches. The motor stop switch is connected to each other, and when both of the motor stop switches are closed, the PWM signal is passed.
According to a sixth aspect of the present invention, in the safety stop circuit according to the first aspect of the present invention, when the motor stop switch is open, the enable terminal of the three-state buffer linked to the motor stop switch is set to High. The output state is high impedance, and the PWM signal is cut off .

However, since the motor control devices in the first and second prior arts use a mechanical contact switch such as a contactor, a contact installation space is required, space saving cannot be achieved, and the larger the capacity, the more one by one. Since the members are expensive and the cost cannot be reduced, there is a problem that the equipment cost increases. Further, since the contact point is a mechanical contact, there are problems such as contact failure due to life and welding of the contact.
In view of such problems, the applicant of the present application aims to provide a motor control device including a safety stop circuit that can omit a contactor, achieve space saving, and reduce the total system cost. (Application number: PCT / JP2008 / 056881). The applicant's proposal (hereinafter referred to as the motor control device in the third prior art) is “a PWM generation that generates a gate drive circuit that drives an inverter unit that converts direct current into alternating current and a PWM signal that is applied to the gate drive circuit” In a power converter having a safety stop circuit interposed between the circuit and the external power cut-off terminal and a PWM signal cut-off circuit that cuts off the PWM signal in conjunction with the external power cut-off terminal, A power conversion device that cuts off a PWM signal to the gate drive circuit by turning off the PWM signal cut-off circuit when the external power cut-off terminal is in an open state. " In this configuration, a safety stop circuit is provided so that the gate drive signal from the external terminal to the inverter can be cut off by hardware. (For example, refer to Patent Document 3).

FIG. 3 is a schematic configuration diagram of a motor control device according to the third prior art. In the figure, 50 is a safety stop circuit, 1 is a PWM generation circuit, 2 is a PWM signal a, 3 is a PWM signal b, 4 is a PWM signal c, and 5 is a cut-off circuit for cutting off the 2 PWM signal a. A three-state buffer, 6 is a three-state buffer for functioning as a blocking circuit for blocking three PWM signals b, 51 and 52 are two enable terminals of the three-state buffer 5, 61 and 62 are three-state buffers 6 Two enable terminals, 7 and 8 are motor stop switches, 9 and 10 are phototransistors, 11 is a gate drive circuit, 12 is an inverter unit (three-phase inverter circuit), IP5 is a 5V power supply, and IP24 is a 24V power supply.
The motor stop switches 7 and 8 are provided outside the motor control device, and open and close in conjunction with each other.
The PWM generation circuit 1 generates and outputs a motor drive PWM signal a (2) by comparison with a carrier which is a carrier wave signal (not shown). Two three-state buffers 5 and 6 are provided between the PWM generation circuit 1 and the gate drive circuit 11. The three-state buffers 5 and 6 have two enable terminals 51 and 52 and 61 and 62, respectively, and only when the signal levels of both terminals 51 and 52 and 61 and 62 are both low (L). The input PWM signal a (2) can be output. The opening and closing of the gates of the two three-state buffers 5 and 6 are configured in conjunction with the motor stop switches 7 and 8. Note that the motor control device in the third prior art is different from the motor control device in the first or second prior art in that the motor power source is installed in the power converter software even if the contactor is not provided outside the power converter. Double three-state buffers 5 and 6 that operate with logic that switches the input PWM signal using the open / close signal from the motor stop switches 7 and 8 as a control signal, which can be cut off without intervention, and the phototransistor 9 includes a switching hardware circuit including motor stop switches 7 and 8 for inputting an open / close signal to the three-state buffers 5 and 6 via 9 and 10 and a circuit capable of maintaining the state.

Next, the operation of the safety stop circuit 50 of the motor control device in the third prior art will be described. First, when the motor stop switch 7 or 8 is opened, the signal from the phototransistor 9 or 10 is cut off, and the enable terminal 51 or 61 of the three-state buffer 5 or 6 becomes high, and the gate is turned on. The output state of the 3-state buffer 5 or 6 becomes high impedance, and the PWM signal a (2) input from the PWM generation circuit 1 or the PWM signal b (3) input from the 3-state buffer 5 is cut off. I can do it. Further, the state of the 3-state buffers 5 and 6 can be monitored by the CPU, and processing such as stopping the output of the PWM signal a (2) can be performed when an abnormality is detected.
JP 2001-251867 A (page 2-4, FIG. 1) Japanese Patent No. 3506590 (page 5-6, FIG. 1) Japanese Patent Application No. 2008-056881 (page 5-7, FIG. 1)

The motor control device in the third prior art includes the safety stop circuit 50 and can solve the problems in the motor control device in the first or second prior art. The abnormality is detected by monitoring the internal CPU and processing such as stopping the PWM signal is performed, and the motor control device is driven by the host device outside the motor control device in the abnormal state of the safety stop circuit itself. Could not be detected directly before. In order to quickly detect an abnormality in the motor control device when using the motor control device, it is desired that the host device on the user side of the motor control device can detect it.
The present invention has been made in view of such problems, and in a motor control device equipped with a safety stop circuit, before driving the motor control device, the abnormal state of the safety stop circuit itself is detected outside the motor control device. It is an object of the present invention to provide a motor control device including a safety stop circuit that can be reliably detected earlier by a host device and can improve safety.

In order to solve the above problems, the present invention is configured as follows.
A motor control device according to one aspect of the present invention generates a gate drive circuit that drives an inverter unit that converts direct current into alternating current in response to a motor drive command from an external host device, and generates a PWM signal to be given to the gate drive circuit A motor control device including a PWM generation circuit, and a safety stop circuit interposed between the gate drive circuit and the PWM generation circuit,
The safety stop circuit is configured so that an external motor stop switch, a plurality of three-state buffers that cut off the PWM signal in conjunction with the motor stop switch, and the host device can determine abnormality of the safety device itself A motor control device including the monitoring circuit is applied.

  According to the first to seventh aspects of the present invention, before the motor control device is driven, the abnormal state of the safety stop circuit itself can be detected more quickly and reliably by the host device outside the motor control device. Can be increased. Furthermore, the reliability of the entire system using the motor control device can be improved.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a schematic configuration diagram of a motor control device including a safety stop circuit according to the present invention. In the figure, the configuration denoted by the same reference numeral as in FIG. 3 has the same effect, and thus detailed description thereof is omitted. 150 is a safety stop circuit, 53 is a terminal not used in the PWM signal 3 of the 3-state buffer 5, 63 is a terminal not used in the PWM signal 4 of the 3-state buffer 6, 152 is an unused terminal 53, 63 Reference numeral 151 denotes a logic circuit that performs a logical operation on the output of the phototransistor. Although 9, 10 and 151 have been described by way of example of phototransistors, they may be photocouplers.
The present invention differs from the third prior art motor control device in FIG. 3 in that it includes a logic circuit 152 and a phototransistor 151, and uses unused terminals 53 and 63 of the three-state buffers 5 and 6. The output signal is a part in which the phototransistor 151 is turned on / off via the logic circuit 152 and the output of the phototransistor 151 is output to the outside of the motor control device. The other part performs the same circuit operation as the motor control device of the third prior art and has the same effect as that.

Next, the operation of the safety stop circuit shown in FIG. 1 will be described.
When the motor stop switches 7 and 8 are open (OPEN), if the safety stop circuit 150 is in a steady state (normal), the signals from the phototransistors 9 and 10 are cut off and the enable terminals of the three-state buffers 5 and 6 (Enable) 51 and 61 become high, the gate closes, the output state of the three-state buffers 5 and 6 becomes high impedance, the PWM signal a (2) input from the PWM generation circuit 1, and the three-state The PWM signal b (3) input from the buffer 5 can be cut off. In this case, the output of the terminal 53 of the 3-state buffer 5 and the output of the terminal 63 of the 3-state buffer 6 are both high (High) output, the output of the logic circuit 152 is high (High) output, and the phototransistor 151 is in the on state, Based on an operation table to be described later, the host device outside the motor control device can detect that the safety stop circuit 150 is in a steady state (normal).

  Similarly, when the motor stop switches 7 and 8 are closed (CLOSE), if the safety stop circuit 150 is in a steady state (normal), the signals from the phototransistors 9 and 10 are turned on, and the three-state buffer 5 Enable terminals (Enable) 51 and 61 of 6 and 6 become Low, the gate is opened, the PWM signal a (2) inputted from the PWM generation circuit 1 from the 3-state buffers 5 and 6, and the 3-state buffer are opened. The PWM signal b (3) input from the buffer 5 can be output.

  Here, when the phototransistor 9 is in an abnormal state in the short state (the phototransistor 10 is normal), even if the motor stop switch 7 is open (OPEN), the enable terminal 51 becomes low (Low). When the gate is opened, the terminal 53 of the 3-state buffer 5 becomes a low output. The output of the logic circuit 152 becomes a low output because the terminal 53 becomes a low output, and the phototransistor 151 is in an off state, that is, based on an operation table described later, the host device outside the motor control device It can be detected that the stop circuit 150 is in an abnormal state.

  Similarly, when the phototransistor 10 is in an abnormal state in the short state (the phototransistor 9 is normal), the enable terminal 61 is low even when the motor stop switch 8 is open (OPEN). Then, the gate is opened, and the terminal 63 of the 3-state buffer 6 becomes Low output. The output of the logic circuit 152 is a low output because the terminal 63 becomes a low output, and the phototransistor 151 is in an off state, that is, based on an operation table described later, the host device outside the motor control device It can be detected that the stop circuit 150 is in an abnormal state.

  Further, when the phototransistor 9 is in an open state (the phototransistor 10 is normal), the enable terminal 51 becomes high (high) even if the safety stop switch 13 is closed (CLOSE). Is closed and the output state of the 3-state buffer 5 becomes high impedance, and the PWM signal a (2) inputted from the PWM generation circuit 1 can be cut off.

  Similarly, when the phototransistor 10 is in an open state (the phototransistor 9 is normal), even if the safety stop switch 13 is closed (CLOSE), the enable terminal 61 is high (High). Thus, the gate is closed and the output state of the 3-state buffer 6 becomes high impedance, and the PWM signal b (3) inputted from the PWM generation circuit 1 can be cut off.

FIG. 2 is an operation table showing the on / off state of the phototransistor 151 in the normal / abnormal state of the safety stop circuit 150. The motor stop switch state, the on / off state of the phototransistor 151, and the motor energization state signal are combined. This shows that the upper / lower device outside the motor control device can detect the normal / abnormal state of the safety stop circuit 150.
The motor energization state signal is a signal that indicates to the host device that the motor control device has conventionally been in a state in which the motor control device can energize the motor by a separately provided configuration. Specifically, when the power supply of the main circuit (power unit) is on and no error is output, the motor control device is in a state where the motor can be energized.
First, when the motor stop switches 7 and 8 are opened (OPEN, ON) before driving the motor control device, the host device outside the motor control device monitors the on / off state of the phototransistor 151. If the phototransistor 151 as shown in FIG. 2 is on, the safety stop circuit is in a steady state (normal), that is, if the phototransistors 9 and 10 are normal, or if the phototransistor 151 is off, the safety stop circuit Is in an abnormal state, that is, an abnormal state in which the phototransistor 9 or 10 is in the short state, can be detected by the host device outside the motor control device.

  Next, when the motor stop switches 7 and 8 are closed (CLOSE, OFF) before driving the motor control device, the motor energization state signal is monitored by the host device outside the motor control device, so that FIG. If the motor energization state signal is on, the safety stop circuit is in a steady state (normal), that is, if the phototransistors 9 and 10 are normal, or if the motor energization state signal is off, the safety stop The host device outside the motor control device can detect that the circuit is in an abnormal state, that is, an abnormal state in which the phototransistor 9 or 10 is in the open state.

Schematic configuration diagram of a motor control device provided with a safety stop circuit according to the present invention Operation table showing on / off state of phototransistor in normal / abnormal state of safety stop circuit Schematic configuration diagram of a motor control device in the third prior art Schematic configuration diagram of a motor control device according to the first prior art Schematic configuration diagram of a motor control device in the second prior art

Explanation of symbols

1 PWM generation circuit 2 PWM signal a
3 PWM signal b
4 PWM signal c
5 3-state buffer for shutting off PWM signal a 6 3-state buffer 7 for shutting off PWM signal b Motor stop switches 9, 10, 151 Phototransistor 11 Gate drive circuit 12 Inverter section (3-phase inverter circuit)
152 Logic circuit 16 Safety circuit abnormality detection signal 51, 52 Enable terminal 53 of 3-state buffer 5 Signal 61, 62 not used in 3-state buffer 5 Enable terminal 63 of 3-state buffer 6 Not used in 3-state buffer 6 Signal 150 Safety stop circuit IP5 5V power supply IP24 24V power supply

Claims (6)

A gate drive circuit that drives an inverter unit that converts direct current to alternating current in response to a motor drive command from an external host device, a PWM generation circuit that generates a PWM signal to be applied to the gate drive circuit, the gate drive circuit, and the gate drive circuit A motor control device including a safety stop circuit interposed between PWM generation circuits,
The safety stop circuit, external and a plurality of motor stop switch, a plurality of 3-state buffers for blocking the PWM signal in conjunction with said plurality of motor stop switch, the host system is an abnormality of the safety device itself 1 And a monitoring circuit configured to be able to make a judgment based on one output signal . The monitoring circuit of each of the plurality of 3-state buffers and off operation based on at least one and one logic circuit for receiving the output signal, said output signal by inputting the output signal of said one logic circuit 1 Two semiconductor elements, and
Said host device, before driving the motor control device, according to claim 1, characterized in that to be able to determine an abnormality of the safety device itself based on one of the output signals of said one semiconductor element Motor control device with safety stop circuit. The host device can determine an abnormality of the safety device itself based on a combination of an on / off state of the plurality of motor stop switches and an on / off state of one output signal of the monitoring circuit. A motor control device comprising the safety stop circuit according to claim 1. The motor control device having the safety stop circuit according to any one of claims 1 to 3, wherein the safety stop circuit can hold a state in which the plurality of motor stop switches are opened.   The safety stop circuit includes two three-state buffers in series and two motor stop switches. The three-state buffer and the motor stop switch are connected to each other, and both the motor stop switches are closed. 5. The motor control device having a safety stop circuit according to claim 1, wherein the PWM signal is allowed to pass in a state. When the motor stop switch is open, the safety stop circuit sets the enable terminal of the three-state buffer linked to the motor stop switch to High, sets the output state to high impedance, and cuts off the PWM signal. The motor control apparatus provided with the safety stop circuit of any one of Claims 1-5.

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