JP2002291268A - Motor control system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a motor control system capable of easily braking the motor at abnormal condition and capable of promptly switching the motor from braking to power driving even if start instruction is generated when braking. SOLUTION: The motor control system converts a dc power to an ac power of variable frequency and variable voltage according to the operation instruction, is connected to an inverter 109 and a servomotor 111 connected to output of the inverter 109, converts the ac power source to the dc power source, switches off from on three-shape full wave rectifier circuit 150, thyristor 152 connected via a resister 154 to output of three-shape full wave rectifier circuit 150 and the inverter 109 according to an abnormal instruction, and is provided with a gate circuit 156 generating a gate signal after a predetermined time delay from generation of the abnormal instruction and a control portion 200 giving operation instruction to the inverter 109 after turning on transistors Tr4-Tr6 of the inverter 109 for predetermined time according to the normal reset signal generated within the predetermined time from generation of the gate signal.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a motor control system in which a motor is braked based on an abnormal command, and then a normal return command is generated during the braking, whereby the motor can be smoothly switched from braking to power running. It is about.

[0002]

2. Description of the Related Art A conventional motor control system will be described with reference to FIG. In FIG. 5, the motor control system 1 has a three-phase AC power supply 3 to which an input of a three-phase full-wave rectifier circuit 5 is connected,
The output of the three-phase full-wave rectifier circuit 5 is connected to a capacitor 7 and an inverter 9 for generating a three-phase variable voltage variable frequency.
1. While being connected to one end of the resistors Ru, Rv, Rw,
The other ends of the resistors Ru, Rv, and Rw are connected to the normally closed contacts 13a to 13a.
Star connection is made via 13c.

The operation of the motor control system configured as described above will be described with reference to FIG. Three-phase full-wave rectifier circuit 5
To convert the three-phase AC power supply 3 into a DC power supply to obtain a DC power supply in which the pulsating voltage is smoothed by the capacitor 7. Now, when a start command is input, the normally closed contacts 13a to 13
13c is released from the closed state, and the resistors Ru to Rw connected to the servomotor 11 are released. Then, the DC voltage is converted into an AC voltage by the inverter 9 to drive the servomotor 11.

Here, if an abnormal command occurs due to a power failure of the three-phase AC power supply 3 while the servomotor 11 is rotating, the inverter 9 is turned off based on the abnormal command, and the normally closed contacts 13a to 13c are opened. Closed, servo motor 1
By applying the voltage generated from No. 1 to the resistors Ru to Rw and flowing a current, the energy generated from the servomotor 11 is consumed by the resistors Ru to Rw, and the servomotor 11 is rapidly braked and stopped. Note that, when the normally closed contacts 13a to 13c are closed, when the inverter 9 performs a voltage conversion operation, a large current flows through the resistors Ru to Rw, so that an operation command of the inverter 9 is not input. .

When a start command is input while the servo motor 11 is braking as described above, the normally closed contact 1
The current is cut off by opening 3a to 13c from the closed state, and the inverter 9 is operated to switch the servo motor 11 from the braking to the power running operation promptly.

[0006]

However, the resistance R
The currents flowing through u to Rw are transferred to mechanical normally closed contacts 13a to 13
c, the normally closed contacts 13a to 13c
There is a problem that maintenance such as replacement due to the life of the 13c has to be performed, which is complicated. In order to eliminate such maintenance, it is conceivable to replace the normally closed contacts 13a to 13c with semiconductor switches. However, simply replacing it with a triac, for example,
A power supply voltage of a gate circuit that generates a gate signal such as a triac at the time of a power outage disappears and a gate signal cannot be continuously generated, and the triac cannot be continuously turned on, so that the servomotor 11 cannot be braked. there were. Further, the triac and the like that have once been turned on cannot be turned off unless the voltage between the terminals is zero or a reverse voltage is applied.
During this time, the triac cannot be turned off. Therefore, there is a problem that it is difficult to quickly switch the servo motor 11 from braking to power running.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and it is possible to easily brake a motor even in the event of an abnormality, and to quickly switch the motor from braking to power running even if a start command is issued during the braking. A switchable motor control system is provided.

[0008]

A motor control system according to a first aspect of the present invention includes a second switching unit connected to a first switching unit, and has a DC control function based on an operation command. Inverting means for converting a power supply into an AC power supply of a variable frequency variable voltage, a motor connected to the output of the inverse converting means, and a rectifying means connected to the motor and converting the AC power supply to a DC power supply, A control rectifier connected to the output of the rectifier through a resistor and turned on based on a gate signal to flow a current, and not turned off unless the current falls below a predetermined value. A signal generating means for generating the gate signal with a predetermined time delay from the generation of the abnormal command, and a signal generating means for generating the gate signal within a predetermined time from the generation of the abnormal command; A first control unit that gives the operation command to the inverse conversion unit after turning on the first or second switching unit of the inverse conversion unit for a predetermined time based on the normal return command. It is assumed that. According to such a motor control system, the signal generation unit turns off the inverse conversion unit from on based on the abnormality command, and generates a gate signal with a predetermined time delay from the generation of the abnormality command to turn on the control rectification unit, The generated energy of the motor is consumed by the resistance to brake the motor. Therefore, after the control rectifier is turned on, the control rectifier is not turned off unless the current falls below a predetermined value, so that the gate signal does not continue to be generated continuously, and the motor can be quickly braked even during a power failure. In addition, the control unit turns on the first or second switching unit of the inverse conversion unit for a predetermined time based on the normal return signal, and sets the input voltage of the rectification unit to zero, thereby immediately reducing the current flowing through the control rectification unit. After turning off, an operation command is given to the inverse conversion means to drive the servo motor. Therefore, there is an effect that the motor can be easily braked even in the event of an abnormality, and the motor can be quickly switched from braking to power running even if a start command is issued during the braking.

[0009] A motor control system according to a second aspect of the present invention comprises:
In the first invention, a rotation number detecting means for detecting a rotation number of the motor, a storage means for storing a predetermined rotation number of the motor, and the rotation number stored in the storage means based on a normal return command And a comparison means for generating an output signal by comparing the detected rotation number with the rotation number detected by the rotation number detection means, and generating an output signal by using the output signal instead of the first control means. And a second control unit for turning on the first or second switching unit of the inverse conversion unit for a predetermined time based on the control signal and then giving an operation command to the inverse conversion unit. According to such a motor control system, the value of the current flowing when the first or second switching unit of the inverse conversion unit is turned on based on the operation command of the second control unit is related to the rotation speed of the motor. The rotation value taking into account the rated current of the switching unit is stored in the storage unit, and the comparison unit compares the rotation value detected by the rotation speed detection unit with the rotation value of the storage unit. When the voltage is lower, the output signal is generated, and the first or second switching unit is turned on. Therefore, there is an effect that overcurrent protection of the first or second switching unit can be performed.

[0010] A motor control system according to a third aspect of the present invention comprises:
In the first invention, current detection means for detecting a current of the motor, storage means for storing a predetermined current value, and the current value and the current detection means stored in the storage means based on a normal return command A comparing means for generating an output signal by comparing the detected current value with the detected current value and generating the output signal, and the inverse conversion based on the output signal instead of the first control means. After turning on the first or second switching unit of the means for a predetermined time, there is provided a second control means for giving an operation command to the inverse conversion means. According to such a motor control system, the first or second reverse conversion means is controlled based on the operation command of the control means.
The storage unit stores a current value in consideration of the rated current of the switching unit, and the comparison unit compares the current value detected by the current detection unit with the current value of the storage unit. When the voltage is lower, the output signal is generated, and the first or second switching unit is turned on. Therefore, there is an effect that overcurrent protection of the first or second switching unit can be performed.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment 1 One embodiment of the present invention will be described with reference to FIG. FIG. 1 is an overall configuration diagram of a motor control system according to an embodiment of the present invention.
In FIG. 1, a motor control system 100 is connected to a three-phase AC power supply 103 and obtains a DC power supply Ed, a capacitor 107 connected to an output of the rectification circuit 105, and an operation command from a control unit 200. An inverter 109 for generating a variable voltage and variable frequency based on the (start command), and a three-phase full-wave rectifier circuit 1 as a rectifier connected to the output of the inverter 109
50, synchronous servo motor 111 and servo motor 1
Current sensors 131u and 131 for detecting a current flowing through
1v, a thyristor 152 as a control rectifier connected in series with a brake resistor 154 to an output of the three-phase full-wave rectifier circuit 150, and a part of a signal generator for applying a pulse signal (gate signal) to a gate of the thyristor 152. And a gate circuit 156 to be formed.

The inverter 109 is connected in parallel with upper transistors Tr _{1 to} Tr ₃ and diodes D _{1 to} D _{3 serving} as a first switching unit, and is connected in series to the first switching unit. 2, the lower transistors Tr _{4 to} Tr ₆ and the diodes D _{4 to} D ₆ are connected in parallel.

The gate circuit 156 is connected to the positive side of the power supply via a resistor 160 to one end of the primary side of a pulse transformer 158, the other end is grounded via a transistor 162, and the base of the transistor 162 is normally connected to the ground. ,
When a positive signal voltage (high voltage) is applied and the signal voltage changes from high to low due to a power failure or the like, the transistor 1
62 is turned off, and a pulse voltage is applied to the thyristor 15 via the pulse transformer 158 with a delay of several milliseconds from the off.
It is configured to be applied to two gates.

An encoder 113 for detecting the rotation angle の of the servomotor 111 is fixed to the axis of the servomotor 111, and the output of the encoder 113 is
And the output of the control unit 200 is given to the input of the inverter 109.

The control unit 200 includes an input I / F 202 for receiving the detected angle Θ of the encoder 113, a CPU 204,
ROM 206, RAM 208 as storage means, output I
/ F210. ROM 208 is CPU 20
4 stores a control program to be executed, that is, a program corresponding to the flowchart of FIG. 3 described later, and the RAM 208 is formed so as to also provide the CPU 204 with a work area.

When the inverter 109 is turned off while the servo motor 111 is rotating, the following voltage is generated at the terminal of the servo motor 111. Vm = k · ω (V) (1) where, k: induced voltage constant (V · s / rad), ω: angular velocity (rad / s), and thyristor 152 and brake resistor 154 The flowing average current Is (A) is given by the following equation. Is = 1.35 · k · ω / (R _m + R _b + jωL) (2) where R _m : winding resistance value between the servo motor terminals (Ω) R _b : brake resistance Resistance value (Ω) L: Armature inductance between servo motor terminals (H) After the thyristor 152 is turned on, the current Is becomes equal to or less than the holding current Ih, so that the thyristor 152 is turned off.

Also, when the servo motor 111 is performing dynamic braking,
That is, when the inverter 109 is turned on by the normal recovery signal while the thyristor 152 is on, the DC power source Ed supplies the brake resistor 15 of the three-phase full-wave rectifier circuit 150.
Excessive current flows through 4. Therefore, the servo motor 11
When the normal return signal is input from the control unit 200 during the power generation braking of 1 and the servo motor 111 is to be immediately run, the thyristor 152 is once turned off from on,
Inverter 109 must be operated.

Therefore, the lower transistors _Tr4 to _Tr4
By turning on _Tr6 , the three-phase full-wave rectifier circuit 150 is turned on.
By making the input voltage of the thyristor 152 almost zero,
, The thyristor 152 is turned off and the inverter 109 is turned on. Even given the on command to the upper side of the transistor _T r1 _{through T r3,} the collector of the transistor _T r1 _{through T r3} capacitor 107 is charged is a voltage Ed,
You can not turn on the transistor _T r1 _{~T r3.} this is,
If the capacitor 107 is not provided, it can be turned on.

On the other hand, the lower transistors _Tr4 to _Tr4 .
T _r6, the maximum peak current _{I tp} flowing through the diode _D 4 ~D ₆ (A) is the following formula also contemplates transients when turned from off of the transistor _T r4 _{through T r6.} I _tp = 2 ^1/2 · 2 · Vm / {(3) ^1/2 · (R _m / 2 + jωL / 2)} (3) When the above equation (1) is substituted into the equation (3), the following equation is obtained. Holds. ^{_{I tp = 2 1/2 · 4k ·}} ω n / {(3) 1/2 · (R m + jωL)} ··· (4) In addition, the transistor _T r4 _{through T r6,} diodes _D 4 ~
Each _I tn the rated current of the D _6, if _I dn (A), must satisfy the following formula when turning the transistor _T r4 _{through T r6.} I _tn , I _dn > I _tp (5)

However, the inverter 109 and the servo motor
Depending on the combination of 111, power generation of servo motor 111
In the braking, the above (3) may not be satisfied. did
As a result, the rotation speed of the servo motor 111 decreases,
Rotational speed N of servo motor 111 satisfying equation (3)_xTo
The rotation speed N_xUnless lower than
Transistor T_r4~ T_r6Is configured not to turn on.
Generally, the transistor T_r4~ T_r6Rated current I_tn
Than diode D₄~ D₆Rated current I_dnIs small
Therefore, the following equation is established. I_dn> 2^1/2・ 4k ・ ω_n/ ｛(3)^1/2・ (R_m+ JωL)｝ · (6) By rearranging equation (6), the following equation is established. ω_x<I_dn・ 3^1/2・ (R_m+ JωL) / (2^1/2・ 4 ・ k) ・ ・ (7) ω_x<I_dnA where A = 3^1/2・ (R_m+ JωL) / (2^1/2・
4 · k) Also, the angular velocity ω of the servomotor 111_x(Rad / s) and times
Rolling speed N_x(Min^-1) Is given by the following equation. ω_x= 2π · p · N_x/ 120 (8) where p is the number of pole pairs of the servomotor 111. By substituting (8) into the above equation (7), the following equation is obtained.
You. 2π · p · N_x/ 120 <I_dn・ AN_x<15.3^1/2・ I_dn・ (R_m+ JωL) / (2^1/2· Π · p) (9) The rotation speed value N_xAnd the rotational speed value N_x
Lower rotational speed value N _nThe keyboard in advance (shown
) Is stored in the RAM 208.

The motor control system configured as described above
The system will be described with reference to FIGS. Figure 2 shows an inverter
109 lower transistor T_r4~ T_r6Turn on
FIG. 3 is a circuit diagram when the servo motor 111 is braked.
6 is a flowchart showing the operation of the first embodiment. First, the CPU 20
4 is an abnormal command when the servo motor 111 is operating.
Judge whether an emergency stop command as
CPU 204 emergency stop at time Ts
When a command is issued, the transistor T
_r1~ T_r6Are all turned off (step S303), and
Sometimes, the transistor 162 in the gate circuit 156
The pulse is turned off by shutting off the current
A pulse voltage is generated on the primary side of the lance 158. Emergency stop
A few milliseconds after the generation of the stop command, that is, time t1
And the pulse voltage Vp from the secondary side of the pulse transformer 158
Is generated and the thyristor 152 is turned on, and the servo motor
The induced voltage generated from 111 is a three-phase full-wave rectifier circuit 150
Thyristor 152, brake resistor 15
4 and the servomotor 111 performs power generation braking.
The CPU 204 inputs the rotation angle の of the encoder 113
Read via I / F 202, servo motor 111
It is determined whether or not it is rotating (step S305).

In step S305, the servo motor
If the CPU 111 is not stopped, the CPU 204
When the motor 111 is performing dynamic braking,
Within a predetermined time from the stop command, a normal return command is input to I / F 20
2 is determined (step S307).
Interval T₂Then, the normal return command is input to the input I / F 202.
Then, the CPU 204 determines a predetermined rotation speed value N_xWhen
Rotation angle of encoder 113 input to control unit 200
The time change Δ 時間 / Δt of Θ is calculated to calculate the servo motor 11
1 is obtained, and Na> N_xJudge whether or not
(Step S307). Note that t is time. Na
<N_x, The lower truck in the inverter 109
Transistor T_r4~ T _r6Turn on all servo motors
The induced voltage generated from the transistor 111_r4~ T
_r6, Diode D₄~ D₆As shown in FIG. 2 through
Current as shown by solid line Ius, dashed line Ivs, and dotted line Iws
Flows through the input power of the three-phase full-wave rectifier circuit 150.
The current flowing through the thyristor 152 becomes zero when the pressure is almost zero.
Time t₃To turn off the thyristor 152 (step
Step S309), time t₄Turns on the inverter 109
Operate the servo motor 111 by powering.
(Step S311).

In the above embodiment, the servo motor
The rotation angle of 111 is detected by the encoder 113,
CPU 204 is a transistor T_r4~ T_r6, Daioh
Do D ₄~ D₆The current flowing through the motor is indirectly converted to the rotational speed Na.
Rotation speed value N obtained by calculation based on
_xCompared with the detection of the current sensors 131u and 131v
The current value Ia and the transistor T_r4~ T_r6, Daioh
Do D₄~ D₆Predetermined tolerance based on the rated current of
It may be compared with the current value Ix. Also, the servo motor 11
Although the synchronous type is described in FIG.
Even if the inverter 109 is turned off while 1 is rotating,
Since a residual voltage is generated based on electrical energy,
It goes without saying that the embodiment can be applied.

[Brief description of the drawings]

FIG. 1 is an overall configuration diagram of a motor control system according to an embodiment of the present invention.

FIG. 2 is a circuit diagram when a lower transistor of an inverter in the motor control system shown in FIG. 1 is turned on.

FIG. 3 is a flowchart showing a braking operation of a servo motor in the motor control system according to FIG. 1;

FIG. 4 is a time chart showing a braking operation of a servo motor in the motor control system according to FIG. 1;

FIG. 5 is an overall configuration diagram of a conventional motor control system.

[Explanation of symbols]

109 Inverter (inverting means), 111 Servo motor, 113 Encoder (rotation speed detecting means), 131
u, 131v current sensor (current detection means), 150
Three-phase full-wave rectifier (rectifier), 152 thyristor (control rectifier), 208 RAM (storage).

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 5H530 AA02 CC06 CD24 CD32 DD03 DD13 DD16 EE03 5H576 CC05 DD05 HA02 HB01 JJ03 LL07 LL22 LL45 MM02 MM13

Claims (3)

[Claims] 1. A second switching device connected to a first switching unit.
Inverting means for converting a DC power supply into an AC power supply with a variable frequency variable voltage based on an operation command, a motor connected to an output of the inverse converting means, and a motor connected to the motor. A rectifying means for converting an AC power supply into a DC power supply, connected to an output of the rectifying means via a resistor, turned on based on a gate signal to flow a current, and the current must be less than a predetermined value. A control rectifier that does not turn off, a signal generator that turns the inverse converter from on to off based on an abnormal command, and that generates the gate signal with a predetermined time delay from the generation of the abnormal command; After turning on the first or second switching section of the inverse conversion means for a predetermined time based on a normal return command generated within a predetermined time from Motor control system comprising: the first control means for providing a decree, the. 2. A rotation speed detecting means for detecting a rotation speed of the motor, a storage device for storing a predetermined rotation speed value of the motor, and the storage device stored in the storage device based on the normal return command. A comparison unit that generates an output signal by comparing a rotation value and a rotation value detected by the rotation number detection unit with a detected rotation value being lower, instead of the first control unit, After turning on a first or second switching unit of the inverse conversion means for a predetermined time based on the output signal, a second control means for giving the operation command to the inverse conversion means. The motor control system according to claim 1. 3. A current detection means for detecting a current of the motor, a storage means for storing a predetermined current value, and the current value and the current detection stored in the storage means based on the normal return command. A comparing means for generating an output signal by comparing a current value detected by the means with a detected current value, and generating an output signal based on the output signal instead of the first control means. 2. The control device according to claim 1, further comprising: a second control unit configured to supply the operation command to the inverse conversion unit after turning on the first or second switching unit of the inverse conversion unit for a predetermined time. 3. Motor control system.