JPH08149870A - Emergency stopping circuit of synchronous motor - Google Patents

Abstract

PURPOSE: To contract largely the decelerating time of a synchronous motor in the case of emergency, by switching its dynamic-braking controlling circuit to its dynamic braking circuit when the motor currents can not be made con stant. CONSTITUTION: A dynamic-braking controlling circuit 19b opens a main-circuit connecting switch in the case of emergency, and concurrently, and turns on the transistors of a synchronous motor 1, so that the voltage induced in the synchronous motor 1 produces a constant motor current to decelerate the motor at a given rate. Further, when the motor current can not be made constant due to the reductions of the induced voltages, the dynamic-braking controlling circuit 19b is switched to a dynamic braking circuit 14. Thereby, in the early time of the emergency, the synchronous motor 1 is decelerated while the motor currents are made constant by the dynamic-braking controlling circuit 19b, and then, after the motor current can not be made constant, the motor is stopped while its power supply lines are short-circuited through resistors by the dynamic braking circuit 14.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement of an emergency stop circuit of a synchronous motor used in machine tools and conveyors.

[0002]

2. Description of the Related Art Generally, in a machine tool or a transfer device using a synchronous motor, a state in which it is difficult to drive them (an external emergency stop switch is pressed, an abnormality occurs in a drive circuit, and a protection circuit operates). When the power is cut off, etc.), the synchronous motor is immediately stopped immediately.

FIG. 7 is a conventional overall configuration diagram centering on a drive circuit for a synchronous motor. In the figure, 1 is a machine tool,
Servo motor composed of a synchronous electric motor used in a carrier device, 2 is a servo amplifier for driving and controlling the servo motor 1,
Reference numeral 3 is an encoder for detecting the speed / position of the servo motor 1. Electric power from the power source buses R, S, and T is used as a diode stack 5 that constitutes a converter unit, an a contact 20 of a main circuit connection relay RA1 that is a main circuit connection switch that is normally closed, a smoothing capacitor 6, and an inverter. It is supplied to the servo motor 1 through the transistor module 7 which constitutes a part in order. Reference numeral 11 denotes a control circuit including a CPU and its peripheral circuits, which is a part of the speed position detection circuit 18
The motor control circuit 12 which receives the feedback signal from the current detector 21 sends a command signal to the base circuit 9 to drive the transistor module 7. The servo motor 1 is driven by the motor current generated thereby. A power supply circuit 8 generates a control power supply 43, a relay excitation power supply 44, and base power supplies BUP, BVP, BWP, BN. An undervoltage detection circuit 22 generates a UV signal 47 when the power is shut off or a power failure is detected. 15 is an external emergency stop signal generation circuit, which is an external emergency stop switch 4
When is pressed, an external emergency stop signal 40 is sent to the control circuit 11 through the hot line 14.

When an alarm signal is generated from the alarm detection circuit 23, the control circuit 11 has an undervoltage detection circuit 22.
When the UV signal 47 is generated from the external emergency stop signal generation circuit 15 or the external emergency stop signal 40 is transmitted from the external emergency stop signal generation circuit 15, the EMG signal 41 is generated, and the emergency stop sequence control circuit 16 causes the motor control circuit 12 to generate the EMG signal 41. Stop,
The a-contact 20 of the main circuit connection relay RA1 is opened to cut off the power supply, the b-contact 10 of the dynamic brake relay RA2 is closed to operate the dynamic brake circuit 14, and the servomotor 1 is stopped emergency. 31a,
31b and 31c are braking resistors of the dynamic brake circuit 14 that short-circuit the power supply line.

8 and 9 show a dynamic brake circuit 14
It is a figure which shows operation | movement. Servo motor 1 rotation speed Nr /
When rotating at min, an emergency stop is applied and the b-contact 10 of the dynamic brake relay RA2 is closed, and the wiring diagram shown in FIG. 8 is obtained. Reference numerals 30a, 30b, 30c are armature resistors of the servomotor 1. At this time, the servo motor 1 applies the induced voltages VU, VV, VW to the U, V, W phases.
Occurs, currents IU, IV, and IW flow, and torque proportional to the currents is generated in the direction of deceleration, and the servomotor 1 stops. At this time, the following relational expression holds. N: Servo motor speed (r / min) N0: Speed at which maximum torque is generated (r / min) I: Motor current (A) IMAX: Maximum current during dynamic brake operation (A) f: Motor current frequency ( Hz) KE: Induced voltage constant (V / [r / m
in]) KT: Torque constant (Nm / A) R1: Armature resistance (Ω) R2: Dynamic brake resistance (Ω) L: Armature inductance (L) P: Number of poles TB: Deceleration torque (Nm) J: Inertia (Kgm2) COS Φ: Power factor

[0006]

[Equation 1]

FIG. 9 (a) is a diagram showing the relationship between the motor rotation speed and time during operation of the dynamic brake circuit. As shown in equation (4), the deceleration torque depends on the rotation speed N, and after the maximum torque is generated at the rotation speed N0, the rotation speed N
The deceleration torque TB also decreases with the decrease. Therefore,
The slope that slows down also decreases. FIG. 9B
Is the relationship between the U-phase current IU and time, and FIG. 9C shows IU, I
It shows the relationship between the current I, which is the full-wave of V and IW in three phases, and the time. The waveform has a peak at N0 r / min immediately after the start of deceleration and has a waveform that attenuates.

Generally, the servo motor 1 is a synchronous motor, and the magnet is demagnetized when an excessive current flows through the synchronous motor. Even when using a dynamic brake circuit, the
As shown in (c), the dynamic brake resistors 31a and 31 are arranged so that the current flowing through the motor does not exceed the demagnetizing current.
It is necessary to select the resistance value R2 of b and 31c. With R2 selected in this way, there is a problem that the deceleration torque becomes smaller as the rotation speed N becomes smaller, and the deceleration time from the start of deceleration to the stop becomes longer. In order to solve this problem, in the conventional technique (Japanese Patent Laid-Open No. 4-21377), as shown in FIG. 10, a first dynamic brake circuit 14b for braking in a high speed deceleration region and a first dynamic brake circuit 14b for low speed deceleration region braking. The second dynamic brake circuit 14c and the rotation speed detection circuit 18 are provided, and the first dynamic brake circuit 14b is switched to the second dynamic brake circuit 14c in accordance with the rotation speed of the servo motor, and the deceleration time from the deceleration start to the stop is reduced. Some are trying to shorten.

[0009]

As described above, the conventional dynamic brake circuit, which is an emergency stop circuit, has a problem that the deceleration time from deceleration start to stop becomes long. Even in the conventional dynamic brake circuit in which the dynamic brake circuit has multiple stages as shown in FIG. 10, the current flowing through the motor has a peak as shown in FIG. 11 (a), and the deceleration time cannot be shortened that much. .

Further, as shown in FIG. 12 (a), if the deceleration is abrupt, the transported object may fall down, causing a problem, or the machine shown in FIG.
As shown in 2 (b), slow deceleration causes various problems due to collision of workpieces, such as machines, but various deceleration patterns are required depending on the application. The stop circuit has a problem that only a fixed deceleration pattern determined by the dynamic brake resistor R2 and the inertia J can be obtained. It is an object of the present invention to provide an emergency stop circuit for a synchronous motor that can significantly reduce the deceleration time in an emergency, and further provide an emergency stop circuit for a synchronous motor that can adjust the deceleration time according to the application of the machine. It is intended to provide a stop circuit.

[0011]

An emergency stop circuit of a synchronous motor according to the present invention is a main circuit for cutting off power supply to a transistor module for driving a synchronous motor using a three-phase power source of U, V and W phases. In an emergency stop circuit of a synchronous motor having a circuit connection switch and a dynamic brake circuit for stopping the synchronous motor by short-circuiting a power supply line in an emergency, the main circuit connection switch is opened in an emergency, and the transistor module is used. The positive (P) side or negative (N) side U, V, W phase transistors corresponding to the U, V, W phases of the synchronous motor are simultaneously turned on, and the induced voltage generated in the synchronous motor is used. Then, the electric motor current is kept constant and the dynamic brake control circuit for controlling the deceleration of the synchronous motor at a constant inclination, and the induced voltage is reduced to reduce the electric motor current. Wherein it from the dynamic brake control circuit that provided a switching circuit for switching to the dynamic braking circuit when no longer become a constant current. Further, the dynamic brake control circuit is provided with a watchdog detection circuit for detecting an inoperable state, and the switching circuit to which the watchdog signal generated from this is input operates the dynamic brake circuit. Further, the dynamic brake control circuit is provided with an undervoltage detection circuit for detecting a decrease in power supply voltage, and the dynamic brake circuit is operated by a switching circuit to which a detection signal generated from this is input. Further, the dynamic brake control circuit is configured such that the motor current can be adjusted to a constant current according to the use of the machine connected to the synchronous motor, and the deceleration time is variable.

[0012]

According to the present invention, in the initial state of an emergency, the dynamic brake control circuit utilizes the induced voltage generated in the synchronous motor to make the electric motor current a constant current, and the synchronous motor is decelerated and controlled at a constant inclination. After that, after the induced voltage decreases and the electric motor current does not become a constant current, the dynamic brake circuit causes the power supply line to short-circuit by resistance to cause deceleration and stop. Further, according to the present invention, when the watchdog detection circuit detects an inoperable state of the dynamic brake control circuit in an emergency, the dynamic brake circuit is operated by the switching circuit to decelerate and stop the synchronous motor. Further, according to the present invention, when the undervoltage detection circuit detects a decrease in the power supply voltage of the dynamic brake control circuit in an emergency, the dynamic brake circuit is operated by the switching circuit to decelerate and stop the synchronous motor. Further, according to the present invention, since the dynamic brake control circuit can adjust the motor current to a constant current according to the application of the machine connected to the synchronous motor and the deceleration time is variable, Objects will not fall down or the workpiece will not collide.

[0013]

【Example】

Example 1. Next, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is an overall configuration diagram centering on the drive circuit of the synchronous motor. The dynamic brake control circuit 19b, the base signal changeover switch 25, the watchdog detection circuit 13, and the base are mainly used in the conventional example of FIG. 7 having the same basic configuration. The cutoff switch 24b of the circuit control power supply 43 is added. Here, parts of the same configuration described in the conventional example of FIG. 7 are denoted by the same reference numerals, and detailed description thereof will be omitted. The cutoff switch 24b is opened and controlled when the undervoltage detection circuit 22 detects a drop in the power supply voltage (for example, power cutoff due to a power failure) or when the watchdog detection circuit 13 detects a disabled state due to CPU runaway. The power supply 43 is shut off to disable the base circuit 9, the a-contact 20 of the main circuit connecting relay RA1 is opened to shut off the power supply, and the b-contact 10 of the dynamic brake relay RA2 is closed. To activate the dynamic brake circuit 14.
In the sixteen emergency stop sequence control circuit, an external emergency stop signal 40 is issued from the external emergency stop signal generation circuit 15,
Alternatively, when the alarm detection circuit 23 detects an abnormality in the servo amplifier 2 and the EMG signal 41 is input, the motor control circuit 12 is stopped and the base signal changeover switch 25 is operated to activate the dynamic brake control circuit 1.
Activate 9b. FIG. 2 shows the base signal changeover switch 25.
3 is a configuration diagram showing details of a base circuit 9 and FIG. The base signal changeover switch 25 is the emergency stop sequence control circuit 1
When the EMG signal is input via 6, the base signal U
P, VP and WP are switched from the base signal from the motor control circuit 12 to the base signal from the dynamic brake control circuit 19b, and the base signals UN, VN and WN are turned off.
Then, the control on the P side of the U, V and W phases of the transistor module 7 is switched to the dynamic brake control circuit 19b. FIG. 3 is a control block diagram of the dynamic brake control circuit 19b. Dynamic brake control circuit 19
b, current detection signals IU, IV from the current detector 21
, IW are input. However, Iw is-(IU + IV
) Can be used. The input current detection signals IU, IV, IW are rectified by the rectifier circuits 50a, 50b, 50c.
Then, only the value on the positive side of the current value is extracted and added by the adder 51 to generate a three-wave rectified signal I of current. IDB is a target value of the current value of the motor flowing during the dynamic brake operation set in advance as a parameter, and IRA is the target value of the current that decelerates and finally closes the b contact 10 of the dynamic brake relay RA2. , The values for which the parameters are set in advance. The comparator 52a compares the three-wave rectified signals I and IDB, and when I is smaller than IDB, a signal for simultaneously turning on the P side of the U, V, and W phases of the transistor module 7, and when I is larger than IDB, the transistor is turned on. U of module 7,
A signal that simultaneously turns off the P side of the V and W phases
Generates a DBP signal 45 delayed by DT μsec.
Input to the base signal changeover switch 25. Further, the comparator 52b compares IRA with IRA, and when I becomes smaller than IRA, an RA20FF signal 42a for closing the b-contact 10 of the dynamic brake RA2 is generated and input to the emergency stop sequence control circuit 16. As a result, the control circuit of the dynamic brake relay RA2 (not shown) of the emergency stop sequence control circuit 16 is activated, and the contact 10
To release. Also, the dynamic brake control circuit 1
9b has gates 54a and 54b which are closed only when the EMG signal 41 is established, and the dynamic brake control circuit 19b is cut off during normal operation.

FIG. 4 is a diagram for explaining the operating principle of the present invention, and FIG. 4 (a) shows induced voltages for generating U, V, and W phases when the rotation speed of the motor is Nr / min. And the frequency of each voltage can be expressed by the above-mentioned formula (3). When the dynamic brake control circuit 19b simultaneously turns on the P sides of the U, V, and W phases of the transistor module 7, for example, in the section of FIG. 4 (a) -I), when viewed from the neutral points of the U, V, and W phases. VU and VW are positive values, and VV is a negative value. Therefore, through the transistor and the diode,
An electric current flows through a route as shown in (b) -I). Similarly, in each region of II) to VI) of FIG. 4A, the currents IU and IV are routed through the paths of II) to VI) of FIG. 4B.
, IW flows. The current value at this time can be expressed by the following equation, and the resistance value R2 of the conventional dynamic brake resistor is set to 0.
It is the same as when

[0015]

[Equation 2]

FIG. 5 shows a dynamic brake control circuit 19
It shows the relationship between the DBP signal 45 generated by b and the motor current I. After the motor current I crosses IDB upwards D
The transistor module 7 is turned off after a delay of T μsec.
Then, the operation of turning on the transistor module 7 is repeated with a delay of DT μsec after the downward crossing. Since the motor has an armature inductance L and there is a time constant for increasing and decreasing the current, the motor current I has a sawtooth waveform centered on IDB as shown in FIG. FIG. 6 shows the relationship between the motor rotation speed N and the motor current I and the time when this control is carried out. As shown in FIG. 6 (b), the current value is constant in IDB, and the constant torque is constant. Since the vehicle decelerates with, the vehicle decelerates with a constant inclination as shown in FIG. When the motor current I is further reduced and becomes smaller than IRA, the contact 10 of the dynamic brake relay RA2 is closed.
Also, by setting IDB so as to match the allowable value IP of the current that can flow in the servomotor 1, deceleration can be performed in the shortest time, and the setting of IDB can be set according to the application of the machine connected to the servomotor 1. The deceleration time can also be adjusted by changing it.

[0017]

According to the present invention, the switch for connecting the main circuit is opened in an emergency, and the positive side or negative side transistors corresponding to the U, V and W phases of the synchronous motor of the transistor module are simultaneously turned on. Then, using the induced voltage generated in the synchronous motor, the motor current is made constant current, and the dynamic brake control circuit that decelerates and controls the synchronous motor at a constant inclination, and the induced voltage decreases and the motor current becomes constant current. A switching circuit is provided to switch the dynamic brake control circuit from the dynamic brake control circuit to a dynamic brake circuit that stops the synchronous motor by resistance short-circuiting the power supply line when it is no longer possible. The time can be shortened. Also, by providing a watchdog detection circuit,
It is possible to operate the dynamic brake circuit in place of the abnormal dynamic brake control circuit due to the runaway of the CPU in the drive circuit of the synchronous motor to operate the dynamic brake circuit to decelerate and stop the synchronous motor, thereby improving safety. Further, by providing the undervoltage detection circuit, the dynamic brake circuit can be operated in place of the abnormal dynamic brake control circuit due to a power failure or the like, and safety can be improved. Further, by providing a dynamic brake control circuit capable of adjusting the electric motor current to a constant current according to the application of the machine connected to the synchronous motor, an appropriate deceleration pattern can be selected according to the application.

[Brief description of drawings]

FIG. 1 is an overall configuration diagram of an embodiment of the present invention.

FIG. 2 is a detailed configuration diagram of a main part of the embodiment of the present invention.

FIG. 3 is a control block diagram showing an example of implementation of a dynamic brake control circuit of the present invention.

FIG. 4 is a diagram showing the operating principle of the embodiment of the present invention.

FIG. 5 is an operating characteristic diagram of the embodiment of the present invention.

FIG. 6 is a diagram showing changes in the speed and motor current of the servo motor when the control according to the embodiment of the present invention is performed.

FIG. 7 is an overall configuration diagram of a conventional example.

FIG. 8 is an explanatory diagram of an operation principle of a dynamic brake circuit.

FIG. 9 is a diagram showing changes in speed and motor current of a servo motor when a dynamic brake circuit is activated.

FIG. 10 is a configuration diagram of a conventional two-stage dynamic brake circuit.

FIG. 11 is a diagram showing changes in motor current and motor speed when a conventional two-stage dynamic brake circuit operates.

FIG. 12 is a diagram illustrating a problem of the conventional technique.

[Explanation of symbols]

1 servo motor (synchronous motor), 2 servo amplifier,
3 encoder, 4 external emergency stop switch, 5 diode stack, 6 smoothing capacitor, 7 transistor module, 8 power supply circuit, 9 base circuit, RA2
Dynamic brake relay, 10 Dynamic brake relay contacts, 11 Control circuit, 12 Motor control circuit, 13 Watchdog circuit, 14 Dynamic brake circuit, 15 External emergency stop signal generation circuit, 1
6 Emergency stop sequence control circuit, 18 Speed position detection circuit, 19b Dynamic brake control circuit, RA1
Main circuit connection relay, 20 Main circuit connection relay contact, 21 Current detector, 22 Undervoltage detection circuit, 23
Watchdog detection circuit, 24b control power cutoff switch for base, 25 base signal changeover switch, 30a-
c Motor armature resistance, 31a-i Dynamic brake resistance, 40 External emergency stop signal, 41 EMG signal, 43 Control power supply, 44 Relay excitation power supply, 45
DBP signal, 47 UV signal, 50a, b, c rectifier,
51 adder, 52a, b comparator, 53 delay device, 5
4a, b Output gate.

Claims (4)

[Claims] 1. A main circuit connecting switch for interrupting power supply to a transistor module for driving a synchronous motor using a U-, V-, and W-phase three-phase power supply, and a power supply line for resistance short-circuiting in an emergency. In an emergency stop circuit of a synchronous motor having a dynamic brake circuit for stopping the synchronous motor, the main circuit connecting switch is opened in an emergency, and the positive sides corresponding to the U, V, and W phases of the synchronous motor of the transistor module, respectively. , Or the negative side transistor is turned on at the same time, the induced voltage generated in the synchronous motor is used to make the electric motor current a constant current, and a dynamic brake control circuit for controlling the deceleration of the synchronous motor at a constant inclination and the induced voltage are When the motor current decreases and the motor current does not become a constant current, the dynamic brake control circuit outputs the dynamic brake current. An emergency stop circuit for a synchronous motor, which is provided with a switching circuit for switching to a brake circuit. 2. A dynamic brake control circuit is provided with a watchdog detection circuit for detecting an inoperable state, and the dynamic brake circuit is operated by a switching circuit to which a watchdog signal generated therefrom is input. Item 1. An emergency stop circuit for a synchronous motor according to item 1. 3. A dynamic brake control circuit is provided with an undervoltage detection circuit for detecting a decrease in power supply voltage, and the switching circuit to which a detection signal generated from this is input operates the dynamic brake circuit. An emergency stop circuit for a synchronous motor according to claim 1. 4. The dynamic brake control circuit is characterized in that the motor current is adjustable to a constant current according to the application of the machine connected to the synchronous motor, and the deceleration time is variable. Item 1. An emergency stop circuit for a synchronous motor according to item 1.