JPH0426386A - Driving apparatus for sewing machine motor - Google Patents

Abstract

PURPOSE:To protect a discharge means from an overvoltage without using a fuse by a method wherein discharge by the discharge means is stopped if the continuation period of the discharge exceeds a predetermined period and, further, current application to the respective phase windings of a sewing machine motor by a current applying means is stopped. CONSTITUTION:A discharge means 9 which discharges electrical charge stored in a storing means if the output voltage of a DC power supply exceeds a predetermined voltage and a stopping means 13 which stops the discharge by the discharge means 9 and, further, stops current application to the respective phase windings of a sewing machine motor M by a current applying means 7 if the continuation period exceeds a predetermined period are provided. In other words, the discharge is stopped before the discharge means 9 is thermally breakdown by the extension of the discharge period. Further, as the sewing machine motor M is turned from a rotating state to a free-running state, the sewing machine motor M is temporarily stopped by loads from respective moving mechanisms of the dewing machine driven by the dewing machine motor M. With this constitution, the discharge means 9 can be protected from an over-voltage without using a fuse.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a driving device for a sewing machine motor.

[Prior Art] Conventionally, as a driving device for a sewing machine motor, a sewing machine motor is driven by generating DC from an AC power supply and by intermittent energization of each phase winding of the motor from a DC power supply at a predetermined cycle and sequence. Or braking (so-called inverter operation)
What it does is known. When braking (with this type of drive device), magnetic energy is accumulated in the phase windings due to the power generation action of the sewing machine motor. The voltage is regenerated in the capacitor attached to the DC power supply, and a discharge circuit is provided to discharge the charge in the capacitor in a timely manner to prevent the voltage of the DC power supply from rising too much.

For example, if the battery is discharged for a few milliseconds, the voltage of the DC power supply will drop below the limit voltage.

By the way, in sewing factories, etc., the voltage of the AC power supply that feeds one sewing machine motor rises above the rated voltage due to the influence of power receiving and distribution equipment → other cage-type induction motors.As a result, the voltage of the DC power supply exceeds the limit voltage. te' may rise. In such a case, the charge accumulated in the comparators is much larger than the regenerative charge mentioned above, and the power supply voltage will drop below the limit voltage unless a leap discharge lasts for several hundred milliseconds to several seconds. There is no.

If the discharge time becomes longer in this way, there is a risk that the discharge circuit will be damaged by heat, so it has been considered to protect the discharge circuit by installing a fuse that melts due to overcurrent and forcibly stopping the discharge.

[Problem to be solved by the invention] However, the drive device with the above-mentioned protective fuse added (more
Every time a fuse blows out, you have to stop the sewing machine motor and replace the fuse, which is very time-consuming and can interfere with sewing work if the AC power supply voltage rises frequently. Therefore, it is an object of the present invention to provide a sewing machine motor drive device that can protect a discharge circuit from overvoltage without relying on fuses.

[Means for Solving the Problems] The gist of the present invention is to provide a DC power source that rectifies AC input from an AC power source, smooths it using a power storage means, and outputs DC; An energizing means for energizing the windings; a control means for driving or braking the sewing machine motor by controlling the energization timing of the first energizing means; and a control means for driving or braking the sewing machine motor by controlling the energizing timing of the first energizing means; In a sewing machine motor drive device that includes a power regeneration means that regenerates electric power to the power storage means, when the output voltage of the DC power source exceeds a predetermined voltage value, a discharge means that discharges the electric charge accumulated in the power storage means; A driving device for a sewing machine motor, comprising a stop means for stopping the discharging by the discharging means and stopping energization of each phase winding of the sewing machine motor by the energizing means when the duration of the period exceeds a predetermined period. be.

[Function] According to the sewing machine motor drive device of the present invention configured as described above, when the sewing machine motor is braked by the power control means, the magnetic energy accumulated in the phase winding is transferred by the power regeneration means. The electric charge is regenerated into the electric storage means and the electric charge in the electric storage means increases, so that the voltage of the DC power supply exceeds a predetermined voltage value.Then, the discharge means discharges the electric charge of the electric storage means, and as a result, the electric charge of the DC power supply increases. The output voltage quickly drops]. However, if for some reason the voltage of the AC power source rises above the rated value, the charge stored in the storage means is far greater than the regenerative charge, and even if the discharge means discharges the charge, the DC The output voltage of the power supply does not easily drop, and the duration of discharge by the discharge means exceeds a predetermined period.Then, the stop means stops the discharge by the discharge means, and also stops the energization means from energizing each phase winding of the sewing machine motor. In other words, the discharge will stop before the discharge period becomes longer and the discharge means is thermally destroyed, and the sewing machine motor changes from a rotating state to a free-running state due to the stoppage of electricity, so the sewing machine motor (upper sewing machine The load from each movement mechanism of the sewing machine driven by the motor (2) will be temporarily stopped. Also, if the voltage of the AC power supply rises above the rated value while the sewing machine motor is stopped, the discharge means will be thermally destroyed in the same way. (before the second discharge is stopped).

[Example code] Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is an electric circuit diagram showing a sewing machine motor drive device to which Yoshiki's invention is applied.

As shown in the figure, the drive device 1 f, t, a DC power supply 5 that rectifies the AC input from the AC power supply 3 to create DC;
An energizing circuit 7 for energizing the AC motor M for driving the sewing machine; a discharging circuit 9 that is provided between the DC power source 5 and the energizing circuit 7 and discharges when the voltage of the DC power source 5 exceeds a limit voltage; and an energizing circuit The main parts include an energization control section 11 that controls the timing of energization of the AC motor M by 7, and a stop circuit 13 that stops the discharge and energization when the voltage of the DC power source 5 exceeds the limit voltage for a predetermined period of time. ing.

The AC power source 3 is connected to the DC power source 5 via an electromagnetic switch MC.

In this embodiment, the capacitor 5b corresponds to the above-mentioned power storage means.

The energizing circuit 7 (so-called inverter) includes six power transistors (hereinafter simply referred to as transistors) that turn on/off energization to each phase winding Lu, Lv, Lw of the AC motor M: Tru, Try, Trw, Trx.
, T ry, T rz, and each phase winding mu, Lv, L
6 commutating diodes D1 for regenerating charge from w
It consists of ~D6, transistors Tru and Trx.
The phase winding Lu is connected to the connection point Pu between the transistors Trv and Try, the phase winding Lv is connected to the connection point Pv between the transistors Trv and Try, and the phase winding Lv
A phase winding Lw is connected to a connection point Pw between rw and Trz, respectively.

In this embodiment, the free commutation diodes D] to D6 correspond to power regeneration means.

Discharge circuit 9 (a series circuit consisting of a parallel circuit of a power consumption resistor R1 and a diode D10, a fuse F for circuit protection, and a transistor Trd for switching), when the transistor Trd is turned on, the charge accumulated in the capacitor 5b is However, from the power consumption resistor R1 to the transistor Tr
d and is consumed by causing the power consuming resistor R1 to generate heat.

Energization control unit 11 (in a predetermined sequence, base 1 switching pulses US of transistors Tru to Trz)
- ZB is output to each phase winding Lu, Lv of AC motor M,
The rotation of the AC motor M is controlled by controlling the timing of energization to Lw. For example, when driving an AC motor M (transistor Tru/Try is ON, then Tru
-Trzh<ON (Other transistors are OFF, same below) - Transistor Trv"Trz is ON1 Then Trv-Trxh<ON=Transistor TrW-TrX
is turned on, then TrW-Try is turned on, and each transistor Tru”T is turned on with a phase difference of 120 degrees.
Controls rz drive.

On the other hand, when braking an AC motor (Yotransistor T
rx-Trv is ON, then Trx-Trw is ON (other transistors are OFF, the same applies hereafter) - transistor T
ry-Trw is ON, then Try-Tru is ON-transistor TrZ-Tru is ON, then T"z-Tr
The driving of each transistor Tru-Trz is controlled with a phase difference of 120 degrees in a circular order in which v is ON. In other words, braking is performed by rotating the AC motor M in the reverse direction.

Further, when a signal S3 (described later) is input from the energization control unit 11 (Yo) flip-flop FF, all the transistors Trtr"Trz are turned off to stop the energization of the AC motor M.

Note that the configuration of the energization control section 11 is well known for inverter control, so the details will be omitted.

The stop circuit 13 is operated by a comparator OP that compares the voltage V[)C of the DC power source 5 detected by the detection resistor R2 with a predetermined limit voltage V ref of the DC power source 5, and a determination signal S1 from the comparator OP. A timer circuit T that starts counting a predetermined time limit, a flip-flop FF to which a time-up signal S2 of the timer circuit T is input, a comparator OP, and a control flop F.
It is composed of an AND circuit AND to which signals S from F (inverted Q terminal) and S3 are input, and a relay circuit RL operated by signal S3 from the inverted Q terminal of flip-flop FF.

Flip-flop FFIL When the time-up signal S2 (High level) of the timer circuit T is input, it becomes L.
The ow active signal S3 is output to the AND circuit AND and the energization control unit]1. Note that the signal S3 returns to High level by the reset signal.

Logical product circuit ANDLL Signals S1 and S3 from comparator OP and foot flop FF are both High
level, that is, when the power supply voltage VDC exceeds the limit voltage V ref, a 1Hgh active output signal 5stop (hereinafter referred to as a stop signal) is output to the transistor Trd of the discharge circuit 9, and It is output to the relay circuit RL via the logic circuit LOG. After that, when the time limit elapses and the time-up signal S2 is input from the timer circuit T to the flip-flop FF, the output signal S3 of the flip-flop FF becomes Low.
The output level of the AND circuit AND also becomes Low.

Relay circuit RL [i Flip-flop FF to Lo
When a signal of level W is input, it is activated after a short delay time, and the AC power supply 3 is cut off by opening the electromagnetic switch MC.

Next, the operation of the 1-mi drive device 1 will be explained.

When the AC motor M is being braked by the energization control unit] 1 (the companion AC motor M enters the generation mode and the phase windings Lu,
Magnetic energy is accumulated in Lv and Lw. This magnetic energy becomes an electric charge and is regenerated to the capacitor 5b by the commutating diodes D1 to D6. More electric charge is accumulated in the capacitor 5b. As a result, power supply voltage VDC exceeds limit voltage Vref. Then, the output signal of the logical product circuit AND (hereinafter referred to as a stop signal) S 5toph<
Since the level becomes High (the level of the logic signal S3 from the flip-flop FF is High), the transistor Trdh (ON L) discharges. When the power supply voltage VDC falls below the limit voltage V ref due to the discharge, the transistor Trd The discharge time (for example, Tf) is on the order of several milliseconds.

However, for example, the voltage of the AC power supply 3 rises above the rated value due to the influence of the power receiving and distribution equipment in the factory and the squirrel cage induction motor, and as a result, the power supply voltage V[)C becomes the limit voltage V ref
The charge accumulated in the capacitor 5b is much larger than the regenerated charge, and even if it is discharged,
It may take hundreds of milliseconds to several seconds for the DC to drop below the limiting voltage V ref.

When the discharge time becomes longer in this way (if the discharge time exceeds the time limit time), the logic signal S3 of the flip-flop FF becomes Low level, so the AND circuit AN
The stop signal S of D becomes 5toph<Low level. Therefore, when the transistor Trd reaches 0FFt, the discharge stops, and the output signal S3 of the flip-flop FF is input to the energization control section 11. Based on this signal S3,
The energization control unit 11 stops all energization by the energization circuit 7. Furthermore, after a short delay time, the relay circuit RL operates to open the electromagnetic switch MC and cut off the AC power supply 3.

Then, the charge accumulated in the capacitor 5b is transferred to the protective resistor 5.
c, the DC voltage is gradually discharged and becomes the limiting voltage V ref
It goes down below. During this time, each transistor Tru-Trz
A voltage exceeding the limit voltage V ref is applied to Tr and Trd, but as a general characteristic of transistors, the withstand voltage when OFF is sufficiently higher than when ON, so each transistor Tr
There is no problem with u-Trz and Trd.

Then, the rotating AC motor M stops temporarily due to the load from the movement mechanism (the path shown in the figure) of the sewing machine.

As explained above, in this embodiment, when the discharge time exceeds the time limit, the discharge is stopped, the energization of the AC motor M is stopped, and the AC power supply 3 is cut off, so that the discharge circuit 9
is protected, and fuse F will not blow out. Also, when the AC motor M is stopped (2. The voltage of the AC power supply 3 rises above the rated value, and the power supply voltage VDC becomes the limit voltage V ref
Even when this exceeds the limit, the discharge circuit 9 is protected in the same manner as during braking, and the fuse F does not blow out.

Therefore, after confirming that the voltage of the AC power supply 3 has dropped, the AC power supply 3 is turned on again (i) The AC motor M can be redriven, and the operation of the sewing machine can be resumed promptly.

Also, when the voltage of the AC power supply 3 suddenly rises abnormally and the voltage of the DC power supply 5 also far exceeds the limit voltage V ref, an overcurrent flows into the discharge circuit 9, but at this time the timer T is in the middle of timing. Since the transistor Trd is ONL, the fuse F blows due to overcurrent, and the discharge circuit 9
and protects the energizing circuit 7. Therefore, in this embodiment, depending on the rising state of the voltage of the AC power source 3, the protective function by stopping the discharge and stopping the energization and the protective function by blowing out the fuse F are respectively exhibited, so that the discharge circuit 9 and the energizing circuit 7 is protected, and the fuse F does not blow out frequently.

[Effects of the Invention] As detailed above, the sewing machine motor drive device of the present invention kinks (when the duration of the L discharge exceeds a predetermined period, the discharge is stopped and the energization to each phase winding of the sewing machine motor is stopped. Therefore, the discharge means is protected.

[Brief explanation of drawings]

FIG. 1 is an electric circuit diagram showing a driving device for a sewing machine motor according to an embodiment. ]... Drive device 3... AC power supply 5... DC power supply 5b... Capacitor 7... Energizing circuit 9...
・Discharge circuit 11... energization control section] 3.
...Stop circuit M...AC motor D1-D6...Commuting diodes Lu, Lv, Lw...Phase winding OP...
...Comparator T...Timer

Claims (1)

[Scope of Claims] A DC power source that rectifies alternating current input from an alternating current power source, smoothes it with a power storage means, and outputs direct current; an energizing means that energizes each phase winding of a sewing machine motor from the direct current power source; A control means for driving or braking the sewing machine motor by controlling the energization timing of the means, and regenerating the magnetic energy stored in the windings of each phase as a charge in the electricity storage means when the control means brakes the sewing machine motor. power regeneration means;
A sewing machine motor drive device comprising: a discharge means for discharging the electric charge accumulated in the electricity storage means when the output voltage of the DC power source exceeds a predetermined voltage value; and a discharge means for discharging the electric charge accumulated in the electricity storage means; A driving device for a sewing machine motor, comprising: stopping means for stopping the discharging by the discharging means and stopping energization of the windings of each phase of the sewing machine motor by the energizing means when the energizing means exceeds the threshold.