JP2014042688A - Dc power-supplied sewing machine and method for driving motor of the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent electric discharge at a power switch, which is caused by DC power supply.SOLUTION: A DC power-supplied sewing machine includes: a motor 61 serving as a driving source of sewing operation; a controller 7 generating an operation command to the motor; a mechanical-type power switch 13; a motor driver circuit 6 capable of being switched between a driving state in which a driving current from the supply by a DC power source is supplied to the motor and a regenerative state in which regenerative power from the motor is output to the supply side of the DC power source in response to a command from a control circuit; and a detector 11 detecting a disconnection state of the power switch or electric discharge between contacts due to the disconnection. When the disconnection state of the power switch or the electric discharge between the contacts due to the disconnection is detected, the controller performs control to temporarily switch the motor driver circuit from the driving state to the regenerative state or from the regenerative state to the driving state.

Description

  The present invention relates to a sewing machine in which DC power feeding is performed and a motor driving method thereof.

  FIG. 11 is a block diagram showing a power supply state of a facility such as a garment factory where a plurality of sewing machines 100 are installed. These sewing machines 100 are individually provided with a power supply circuit 102 having an AC / DC conversion circuit that converts AC power supplied from an AC power supply 101 into DC power by a rectifying unit that rectifies AC power and a smoothing unit that smoothes the AC power. Is converted into a DC power source and a sewing operation is performed (for example, Patent Document 1).

  However, in an environment where multiple sewing machines such as the above garment factory are used, installing a power circuit that individually converts AC to DC increases the manufacturing cost. A power supply circuit for conversion is prepared, and it is considered that one power supply circuit supplies DC power to a plurality of DC power supply type sewing machines.

JP 2001-38086 A

However, when using a mechanical power switch that is turned on and off by contact and release of the contacts, the DC power-feed sewing machine generates arc discharge between the contacts when the switch is disconnected, and current flows between the contacts. There was a problem of continuing.
When such a discharge phenomenon occurs, a high temperature is generated between the contacts, the contacts are significantly deteriorated, and the durability is greatly impaired.

  An object of the present invention is to prevent discharge of a power switch in DC power feeding.

  According to the first aspect of the present invention, there is provided a motor which is a driving source for operations relating to sewing, a control unit which generates an operation command for the motor, and a connection and disconnection from a DC power supply source outside the sewing machine to a power supply destination inside the sewing machine. And a mechanical power switch that switches between two contact points, and a driving state in which a driving current based on a DC power supply is supplied to the motor and a regenerative power from the motor is output to the DC power supply source side. In a DC power supply sewing machine including a motor driver circuit that can switch a regeneration state according to a command from the control circuit, the control unit includes a detection unit that detects a discharge state between the contact points due to a disconnection state or disconnection of the power switch, When the disconnection state of the power switch or the discharge between the contacts due to the disconnection is detected, the motor driver circuit is temporarily stopped. Characterized in that said performing control for switching the drive state to the regenerative state or from the regeneration state from the driving state to.

  According to the second aspect of the present invention, there is provided a motor that is a driving source for operations relating to sewing, a control unit that generates an operation command for the motor, and a connection and disconnection from a DC power supply source outside the sewing machine to a power supply destination inside the sewing machine. And a mechanical power switch that switches between two contact points, and a driving state in which a driving current based on a DC power supply is supplied to the motor and a regenerative power from the motor is output to the DC power supply source side. In a DC power supply sewing machine comprising a motor driver circuit capable of switching between a regenerative state and a command of the control circuit, the control unit periodically and temporarily drives the motor driver circuit during the rotation of the motor. Control for switching from the regenerative state to the driving state from the regenerative state.

  According to a third aspect of the present invention, there is provided a motor that is a driving source for operations relating to sewing, a control unit that generates an operation command for the motor, and a connection and disconnection from a DC power supply source outside the sewing machine to a power supply destination inside the sewing machine. And a mechanical power switch that switches between two contact points, and a driving state in which a driving current based on a DC power supply is supplied to the motor and a regenerative power from the motor is output to the DC power supply source side. In a DC power supply sewing machine including a motor driver circuit that can switch a regenerative state according to a command of the control circuit, a detection step of detecting a discharge state between the contact points due to a disconnection state of the power switch or a disconnection of the power switch When a discharge between the contacts due to a state or disconnection is detected, the motor driver circuit is temporarily switched to the driving state. Characterized in that it comprises a driving state switching step of switching from al regeneration state or the regeneration state to the drive state.

The invention according to claim 4 is a motor that is a driving source for operations related to sewing, a control unit that generates an operation command for the motor, and a connection and disconnection from a DC power supply source outside the sewing machine to a power supply destination inside the sewing machine. And a mechanical power switch that switches between two contact points, and a driving state in which a driving current based on a DC power supply is supplied to the motor and a regenerative power from the motor is output to the DC power supply source side. In a DC power supply sewing machine comprising a motor driver circuit capable of switching between a regenerative state and a command of the control circuit,
During the rotation of the motor, the motor driver circuit is periodically and temporarily switched from the driving state to the regenerative state or from the regenerative state to the driving state.

When the power switch is disconnected, the contact surface tip between the contacts gradually decreases and the resistance value increases when the power switch is disconnected, causing the contact temperature to rise, generating metal gas due to high temperature, and current flows through this. It is caused by that.
According to the first and third aspects of the present invention, when the disconnection by the power switch or the discharge between the contacts due to the disconnection is detected, the control unit temporarily changes the motor driver circuit from the driving state to the regenerative state or from the regenerative state. By controlling to switch to, the ionized metal gas floating between the remote contacts of the power switch will not receive acceleration when the voltage between the contacts is reversed, and part of it will be pushed back to the source, causing a sudden current. Since there is no path, the discharge is immediately interrupted.

  In the configuration of claims 2 and 4, the control unit periodically controls the motor driver circuit from the driving state to the regenerative state or from the regenerative state to the driving state, so that the power switch is disconnected. Even if a discharge occurs between contacts, the ionized metal gas floating between the contacts that are separated from the power switch will not be accelerated by the reverse voltage between the contacts, and some will be pushed back to the source. Since the current path suddenly disappears, the discharge is immediately interrupted.

As described above, according to the inventions of the above claims, even when DC power is supplied to the sewing machine, the discharge can be avoided or quickly eliminated when the power switch is disconnected. It is possible to suppress the deterioration of the contact of the power supply and improve the durability of the power switch.
In addition, since the problem of occurrence of discharge of the power switch due to direct current power supply can be solved, it is possible to use a power switch having a relatively inexpensive mechanical contact. Further, since it is possible to perform DC power supply to the sewing machine, for example, when a plurality of sewing machines are used at a single location, a power supply circuit that performs conversion from AC to DC can be shared by the plurality of sewing machines. For this reason, the individual sewing machine does not require an AC / DC conversion circuit, and the manufacturing cost of the sewing machine can be reduced.

It is explanatory drawing which shows schematic structure of the sewing system to which the direct current power supply sewing machine is applied. It is a block diagram which shows the main control structure of a direct current feeding sewing machine. It is a circuit diagram which shows the specific structure of an IPM driver. It is explanatory drawing which shows the control signal which a control part performs with respect to an IPM driver at the time of acceleration and constant speed rotation of a servomotor. It is explanatory drawing which shows the control signal which a control part performs with respect to an IPM driver at the time of the deceleration rotation of a servomotor. It is a flowchart which shows the power-off control at the time of the power switch cut-off by a control part. It is a circuit diagram of the discharge experiment circuit which can produce arc discharge between the contacts of a power switch. It is the diagram which showed the voltage change of the both ends at the time of the power switch disconnection by the discharge experiment circuit of FIG. It is explanatory drawing which shows the control signal which a control part performs with respect to an IPM driver at the time of acceleration and constant speed rotation of a servomotor in order to prevent discharge. It is explanatory drawing which shows the control signal which a control part performs with respect to an IPM driver at the time of the deceleration rotation of a servomotor in order to prevent discharge. It is a block diagram which shows the power supply state of facilities, such as a sewing factory in which the some sewing machine is installed.

[First embodiment]
Hereinafter, the DC power supply sewing machine 1 according to the first embodiment will be described.
FIG. 1 is an explanatory diagram showing a schematic configuration of a sewing system 50 to which the DC power feeding sewing machine 1 is applied. As shown in FIG. 1, the sewing system 50 converts AC power supplied from a plurality of DC power supply sewing machines 1 and a commercial AC power supply 51 into DC power, and outputs the DC power to each DC power supply sewing machine 1. A common power supply 2 as a power supply circuit and a DC power supply line 3 that electrically connects each DC power supply sewing machine 1 and the common power supply 2 are provided. The common power source 2 is provided with an AC / DC conversion circuit 21 and a regenerative power storage unit 22. The plurality of DC power supply sewing machines 1 are connected to the common power supply 2 in parallel.
The storage unit 22 is a large-capacity capacitor capable of storing regenerative power from a plurality of DC power supply sewing machines 1.

[DC powered sewing machine]
FIG. 2 is a block diagram showing a main control configuration of the DC power supply sewing machine 1 as the electronic apparatus according to the present invention. As shown in FIG. 2, the DC power supply sewing machine 1 is provided with a positive terminal 4 and a negative terminal 5 to which a DC power supply line 3 drawn from the common power supply 2 is connected. The negative terminal 5 is grounded. The DC power supply sewing machine 1 includes a servo motor 61 as a sewing motor that is a sewing drive source, an IPM (Intelligent Power Module) driver 6 as a motor driver circuit for driving the servo motor 61, and an IPM driver 6. The control unit 7 that controls the servo motor 61, the operation panel 8 that inputs various operation instructions to the control unit 7, and the operation instruction for operating the IPM driver 6 to the control unit 7 are input. Two contacts for connecting and disconnecting the pedal 9, the power supply 10 for the control section for supplying power to the control section 7, and the common power supply 2 outside the sewing machine to the power supply destination inside the sewing machine via the plus terminal 4 Comparison as a detection unit that detects a potential difference between two contact points of the mechanical power switch 13 and the power switch 13 that are switched by the contact / separation operation of A road 11, a capacitor 12 for stabilizing the DC voltage is provided.

FIG. 3 is a circuit diagram showing a specific configuration of the IPM driver 6. As shown in FIG. 3, the servo motor 61 includes a U-phase coil 611, a V-phase coil 612, and a W-phase coil 613.
The IPM driver 6 includes a U-phase high-side driver 621 and a U-phase low-side driver 631 connected to the U-phase coil 611, and a V-phase high-side driver 641 and a V-phase low-side driver 651 connected to the V-phase coil 612. And a V-phase high-side driver 661 and a U-phase low-side driver 671 connected to the W-phase coil 613. Each of the high-side drivers 621, 641, 661 and the low-side drivers 631, 651, 671 includes an FET, and free-wheeling diodes 622, 642, 662, 632, 652, 672 are connected in parallel to each other.
Further, the drains of the high-side drivers 621, 641, and 661 are connected to the power supply positive electrode side of the IPM driver 6, and the sources are connected to the corresponding coils 611, 612, and 613, respectively.
The drains of the low-side drivers 631, 651, 671 are connected to the corresponding coils 611, 612, 613, respectively, and the sources are connected to the power supply negative electrode side (ground) of the IPM driver 6.
The high side drivers 621, 641, 661 and the low side drivers 631, 651, 671 are switched ON / OFF (connected / disconnected) in accordance with an operation command signal input from the control unit 7.

  The control unit 7 includes a CPU that performs various processes based on the program, various control programs, a ROM that stores data used in the program, programs and data read from the ROM, and various instructions input from the operation panel 8. A RAM serving as a work area for a CPU that executes a program based on an operation instruction or the like input from the pedal 9 is provided.

  For example, when an operation instruction is input from the pedal 9, the control unit 7 activates the IPM driver 6. At this time, the control unit 7 sets a target speed based on the depression amount of the pedal 9 and controls the IPM driver 6 so that the rotation speed of the servo motor 61 becomes the target speed. For example, when the depression amount of the pedal 9 increases, the control unit 7 controls the IPM driver 6 so that the servo motor 61 accelerates. When the depression amount of the pedal 9 decreases, the control unit 7 causes the servo motor 61 to decelerate. The IPM driver 6 is controlled.

Here, the operation control performed on the IPM driver 6 by the control unit 7 during acceleration / constant speed rotation and deceleration rotation of the servo motor 61 will be described with reference to FIGS.
In addition, although the electric current supplied to the bases of the drivers 621 to 671 of the respective phases of the IPM driver 6 can be driven even by alternating current, they are illustrated by rectangular waves in the examples of FIGS.
The servo motor 61 is driven from the U-phase coil 611 to the V-phase coil 612, from the V-phase coil 612 to the W-phase coil 613, and from the W-phase coil 613 to the U-phase coil 611. The state in which a current flows is repeated in order to perform rotational driving in the positive direction. In addition, a drive current flows from the U-phase coil 611 to the W-phase coil 613, a drive current flows from the W-phase coil 613 to the V-phase coil 612, and a drive current flows from the V-phase coil 612 to the U-phase coil 611. The state is repeated in order, and the rotation drive in the reverse direction is performed.

FIG. 4 shows control signals for the drivers 621, 631, 641, and 651 when the servo motor 61 is accelerated in the forward direction or rotated at a constant speed (acceleration / constant speed control). Here, the operation of the IPM driver 6 will be described by taking as an example a period during which current flows from the U-phase coil 611 to the V-phase coil 612. In this period, since no current flows through the W-phase coil 613, the drivers 661 and 671 connected to the W-phase coil 613 remain OFF and are not shown in FIG.
When the U-phase high-side driver 621 and the V-phase low-side driver 651 are turned on, and all others are turned off, a current flows from the U-phase coil 611 of the servo motor 61 to the V-phase coil 612 (solid arrow in FIG. 3). The magnetic flux generated by the two coils 611 and 612 and the magnetic flux generated by the magnet of the motor rotor are repulsive (or attractive), and the servo motor 61 is accelerated in the forward rotation direction.
At this time, since the rotational acceleration force is determined by the magnitude of the current flowing through the coils 611 and 612 of each phase, ON and OFF with respect to the U-phase high-side driver 621 or the V-phase low-side driver 651 at a predetermined duty ratio. The desired current value is controlled by switching using PWM or the like repeatedly (in FIG. 4, PWM control is performed on the U-phase high-side driver 621).
In addition, a control for flowing a drive current from the V-phase coil 612 to the W-phase coil 613 (the V-phase high-side driver 641 and the W-phase low-side driver 671 are turned on) and the W-phase coil 613 according to the advance of the mechanical phase of the motor shaft. In the same manner, the control for causing the drive current to flow from to the U-phase coil 611 (the W-phase high-side driver 661 and the U-phase low-side driver 631 are turned on) is sequentially performed.

Next, FIG. 5 shows control signals for the drivers 621, 631, 641, and 651 when the servo motor 61 is decelerated and rotated in the forward direction (regenerative control). Also in this case, the operation of the IPM driver 6 will be described by taking as an example the period during which the circulating current flows from the V-phase coil 612 to the U-phase coil 611. Also in this case, since current does not flow through the W-phase coil 613 during the synchronization, the drivers 661 and 671 remain OFF, and the illustration in FIG. 5 is omitted.
When the U-phase low-side driver 631 is turned on and all others are turned off, the circulating current flows through the path from the V-phase coil 612 to the U-phase coil 611, the U-phase low-side driver 631, and the V-phase low-side driver 651. A path is formed (dotted arrow in FIG. 3), and the electric current generated by the rotational motion of the motor circulates. Also in this case, the U-phase low-side driver 631 is turned on and off by switching using PWM, and the magnitude of the circulating current is adjusted.
Also in this case, according to the advance of the mechanical phase of the motor shaft, control is performed so that a circulating current flows from the W-phase coil 613 to the V-phase coil 612 (V-phase low-side driver 651 is ON), and the U-phase coil 611 to the W-phase coil 613. The control for flowing the circulating current to the W phase (the W-phase low-side driver 671 is turned on) is executed in order.

The servo motor 61 is decelerated by the circulating current, and energy is sequentially accumulated in the coils 611, 612, and 613. This accumulated energy is regenerated to the power source whenever the low-side driver that is turned on is switched. For example, when the low-side driver that is turned on is switched from the U-phase low-side driver 631 to the V-phase low-side driver 651, the U-phase coil 611 is connected to the power supply side through the free-wheeling diode 622. Washed away. That is, the regenerative current is returned to the external common power source 2 through the power switch 13.
Similarly, when the W-phase low-side driver 671 is turned on, the regenerative current by the V-phase coil 612 is returned to the common power source 2, and when the U-phase low-side driver 631 is turned on by the W-phase coil 613. The regenerative current is returned to the common power source 2.

Next, drive state switching control executed by the control unit 7 when the power switch 13 is disconnected will be described based on the flowchart of FIG.
This drive state switching control is for preventing an arc discharge phenomenon that occurs between the two contacts when one contact of the power switch 13 is separated from the contact state with respect to the other contact.
This drive state switching control is executed when the power switch 13 is disconnected. However, the control unit power supply 10 has a capacitor so that it can be executed even when the power supply from the common power supply 2 is cut off. It has. That is, the control unit 7 executes the drive state switching control by the electric power stored in the capacitor in the control unit power supply 10.

In this drive state switching control, the discharge cutoff time is set in advance to the control unit 7 by the operation panel 8, and the control unit 7 stores the set discharge cutoff time in a storage unit (memory) (not shown) ( Step S1). The discharge interruption time is a time for which the control unit 7 continuously executes a process (described later) for avoiding arc discharge from the moment when the power switch 13 is turned off.
The setting of the discharge interruption time does not have to be performed every time the power-off control is executed, and may be omitted if it is already set.

  Next, the control unit 7 determines whether or not the power switch 13 is disconnected (OFF / open state) (step S3: detection step). The disconnection of the power switch 13 is detected by the comparison circuit 11. That is, while the power switch 13 is connected, there is almost no potential difference between both sides of the power switch 13. On the other hand, when the power switch 13 is turned off, a large potential difference occurs between both ends of the power switch 13. Even if arc discharge occurs and current flows at both ends of the power switch 13, a large electric resistance is generated between the contacts, so that a certain potential difference is generated between both ends of the power switch 13. Will occur. Therefore, the comparison circuit 11 uses a value smaller than these potential differences as a threshold value, and inputs a detection signal to the control unit 7 when a potential difference exceeding the threshold value occurs at both ends of the power switch 13. The control unit 7 can determine whether the power switch 13 is disconnected based on the presence or absence of a detection signal from the comparison circuit 11. The comparison circuit 11 outputs a detection signal to the control unit 7 via a photocoupler (not shown), and has a structure in which a direct connection between the external power source and the control unit 7 is avoided.

When the OFF of the power switch 13 is detected, the control unit 7 determines whether or not the servo motor 61 is rotating (step S5). Since the servo motor 61 rotates by inputting a control signal to the IPM driver 6, the control unit 7 determines whether or not the servo motor 61 is rotating depending on whether or not the control signal is currently input. be able to.
When the servo motor 61 is not rotating, the amount of current flowing through the power switch 13 is small and arc discharge does not occur. Therefore, the process is terminated without performing control for preventing arc discharge.

If the servo motor 61 is rotating, the control unit 7 determines whether the servo motor 61 is in a regenerative state (step S7). Whether or not regeneration is performed can be determined by whether the control unit 7 is executing acceleration / constant speed control or regeneration control.
When the servo motor 61 is regenerating, the control unit 7 executes the acceleration / constant speed control only for the above-described discharge interruption time, and controls the IPM driver 6 so as to return to the original regeneration control again ( Step S11: driving state switching step). Then, the process ends.
Further, when the servo motor 61 is not regenerating, that is, when accelerating or at a constant speed, the control unit 7 controls the IPM driver 6 so that the regenerative control is executed for the discharge interruption time described above and returned. (Step S9: Drive state switching step). Then, the process ends.

[Technical effects of the embodiment of the invention]
In the DC-powered sewing machine 1, when the disconnection by the power switch 13 is detected, the control unit 7 temporarily accelerates the IPM driver 6 from the regenerative state to the regenerative state from the regenerative state or from the regenerative state. Since the drive state switching control for switching to the drive state is performed, the current flows in the reverse direction in a state where a discharge can occur between the contacts of the power switch 13, so that the occurrence of the discharge can be prevented or quickly eliminated.
In addition, the temporary switching between the driving state and the regenerative state described above is executed for a preset discharge interruption time, so that proper discharge is performed until the contacts of the power switch 13 are separated by a sufficient distance to avoid discharge. It is possible to maintain the prevention effect.
Even when DC power is supplied to the DC power supply sewing machine 1, the discharge can be avoided or quickly eliminated when the power switch 13 is disconnected. Durability can be improved.
As a result, it is possible to use the power switch 13 provided with a relatively inexpensive mechanical contact in the DC power supply sewing machine 1.
Further, since it is possible to perform DC power supply to the DC power supply sewing machine 1, the common power source 2 that performs conversion from AC to DC in the sewing system 50 can be shared by a plurality of DC power supply sewing machines 1, and individual DC power supplies can be shared. It is possible to realize a low-cost sewing system that does not require an AC / DC conversion circuit in the power feeding sewing machine 1.

[Others]
In the DC power supply sewing machine 1, the case where a three-phase servo motor is mounted is exemplified, but the type of the motor may be any type capable of performing regenerative control.
Further, in the processing after step S7 shown in FIG. 6, the acceleration / constant speed control and the regenerative control are switched only once, but the acceleration is accelerated during the discharge interruption period with a period sufficiently shorter than the discharge interruption period. -Switching between constant speed control and regenerative control may be repeated.

[Second Embodiment]
In the first embodiment, it is assumed that a discharge can occur when the servo motor 61 is rotationally driven when the power switch 13 is cut off, and an arc discharge is actually generated between the contacts of the power switch 13. Although the case where drive state switching control for switching between regenerative control and drive control is executed regardless of whether or not the DC power supply sewing machine 1 is actually subjected to arc discharge between the contacts of the power switch 13 is illustrated. It is good also as a structure which performs drive state switching control which switches regenerative control and drive control after detecting this.

FIG. 7 is a circuit diagram of a discharge experiment circuit 200 capable of causing arc discharge between the contacts of the power switch 201. The discharge experimental circuit 200 includes a DC power source 203 for flowing a load current to a predetermined load 202, a power switch 201 having the same structure as the power switch 13 provided between the DC power source 203 and the load 202, A measurement resistance element 204 connected in parallel to the power switch 201 and a detector (not shown) that detects a potential difference at both ends of the power switch 201 by the measurement resistance element 204 are provided.
The DC power supply voltage was set to 20 [V], the current value flowing through the circuit was set to 2 [A], and the potential difference at both ends of the resistance element for measurement 204 when the power switch 201 was cut off was recorded. The results are shown in the diagram of FIG.

When the power switch is turned off, the contact area of the contact gradually decreases and finally the contact leaves, but the electrical resistance increases as the contact area decreases. If a current flows through this contact, the amount of heat generated increases due to an increase in resistance, and part of the contact evaporates and ionizes, forming a current path as a conductive gas. The arc discharge phenomenon occurs at the contact point based on the principle that current continues to flow between the contact points through the conductive gas.
Therefore, as shown in FIG. 8, when the power switch 201 is connected, the potential difference is almost 0, and when the power switch 201 is completely disconnected, the potential difference is 20 [V], which is a DC power supply voltage. When the power switch 201 is turned off, the contact area between the contacts decreases, so that the resistance value increases and the voltage suddenly increases from 0 [V] to a constant voltage value less than 20 [V]. Since the metal evaporates only from the portion with the high resistance value of the contact, the current continues to pass through the portion with the high resistance value during the discharge, so that the voltage between the contacts during the discharge hardly changes.
Therefore, the DC power supply sewing machine 1 also measures in advance the voltage (referred to as the discharge voltage Va) at both ends of the power switch 13 when the arc discharge of the power switch 13 occurs, and between a predetermined voltage range V1 to V2 including this discharge ( When a voltage satisfying V1 <Va <V2) is detected by the comparison circuit 11, the discharge avoidance process may be executed assuming that a discharge has been detected.

  Specifically, in the flowchart in FIG. 6, the detection voltage at both ends of the power switch 13 is between the voltage ranges V1 to V2 instead of the detection process of the disconnection state (OFF / open state) of the power switch 13 in step S3. In such a case, the control is performed so as to proceed to the processing after step S5, so that the regenerative control and the drive control are performed after detecting that the arc discharge is actually generated between the contacts of the power switch 13. It is possible to realize the DC power-feed sewing machine 1 that executes the drive state switching control for switching between the two. If a voltage greater than V2 is detected in step S3, it is desirable to terminate the process as it is, assuming that the power supply has been cut off without causing a discharge.

  As described above, the DC power-feed sewing machine 1 obtains the same effect as that in the case of detecting the disconnection state of the power switch 13 described above, and actually, regenerative control and drive control only when arc discharge occurs in the power switch 13. It is possible to execute the driving state switching control for switching between the two, and it is possible to avoid the driving state switching control being executed until no discharge has occurred.

[Third embodiment]
In the first and second embodiments, the case where the cutting of the power switch 13 or the occurrence of discharge is detected and the drive state switching control for switching between regenerative control and drive control is executed is exemplified. A configuration may be adopted in which disconnection of the switch 13 or detection of discharge is omitted, and drive state switching control is periodically executed during acceleration / constant speed and regeneration of the servo motor 61.

Specifically, FIG. 4 shows control signals for the drivers 621, 631, 641, 651 when the servo motor 61 is accelerated and driven at a constant speed (acceleration and constant speed control) in the first embodiment. On the other hand, when the drive state switching control is executed periodically, as shown in FIG. 9, the U-phase high-side driver 621 is turned on in pulses to maintain acceleration or constant speed. When the phase low-side driver 651 is continuously turned on, the IPM driver 6 is controlled so that the V-phase low-side driver 651 is also turned off so that a regenerative state occurs periodically (longer than the PWM cycle). To do.
As a result, all the drivers 621, 631, 641, 651 are temporarily turned OFF, and a regenerative current is periodically generated from the servo motor 61 during acceleration / constant speed control, and the power switch 13 is turned on during acceleration / constant speed control. Even when disconnected, the regenerative current generated periodically can suppress discharge.

  Further, FIG. 5 shows control signals for the drivers 621, 631, 641, 651 when the servo motor 61 is rotated at a reduced speed (regenerative control) in the first embodiment. When the drive state switching control is executed, as shown in FIG. 10, when only the U-phase low-side driver 631 is turned on in a pulsed manner to decelerate, it is periodically (longer than the PWM cycle). The IPM driver 6 is controlled so that the U-phase high-side driver 621 and the V-phase low-side driver 651 are turned on so that an acceleration / constant speed state is generated in a cycle). As a result, the U-phase high-side driver 621 and the V-phase low-side driver 651 are turned on, the V-phase high-side driver 641 and the U-phase low-side driver 631 are turned off, and a drive current periodically flows to the servo motor 61 that is performing regenerative control. Even when the power switch 13 is disconnected during the regeneration control, the periodically generated drive current can suppress the discharge.

Note that it is desirable that the one execution time of the drive state switching control is the above-described discharge interruption time, but as shown in FIGS. 9 and 10, when PWM control is being performed, the ON period or OFF is performed. You may perform according to a period.
Moreover, the execution cycle of the drive state switching control can increase the execution efficiency of the discharge prevention of the power switch 13 when the frequency is increased. However, since the output of the motor is reduced as the frequency increases, the execution efficiency of the discharge prevention is increased. It is necessary to set appropriately considering the balance between the motor output efficiency and the motor. In the above example, it is desirable to perform it once every 10 [MS].

  As described above, the DC power supply sewing machine 1 obtains the same effect as that in the case of detecting the cut state of the power switch 13 or the arc discharge described above, and eliminates the need for detecting the cut state of the power switch 13 or the arc discharge. It is possible to simplify the apparatus and the control.

1 DC power supply sewing machine 2 Common power supply (DC power supply source outside the sewing machine)
6 IPM driver (motor driver circuit)
7 Control Unit 10 Control Unit Power Supply 11 Comparison Circuit (Detection Unit)
13 Power Switch 21 Conversion Circuit 22 Accumulation Unit 50 Sewing System 51 AC Power Supply 61 Servo Motor

Claims (4)

A motor that is a driving source for operations related to sewing,
A control unit for generating an operation command for the motor;
A mechanical power switch that switches connection and disconnection from the DC power supply source outside the sewing machine to the power supply destination inside the sewing machine by the contact operation of the two contacts;
A motor driver circuit capable of switching between a driving state in which a drive current based on a DC power supply is supplied to the motor and a regenerative state in which regenerative power from the motor is output to the DC power supply source side according to a command from the control circuit; In the DC power supply sewing machine provided,
A detector that detects a discharge state between the contacts due to a disconnected state or disconnection of the power switch;
The control unit is configured to temporarily switch the motor driver circuit from the driving state to the regenerative state or from the regenerative state to the driving state when a discharge state between the contact points due to the cut state of the power switch or the disconnection is detected. A DC-powered sewing machine characterized by A motor that is a driving source for operations related to sewing,
A control unit for generating an operation command for the motor;
A mechanical power switch that switches connection and disconnection from the DC power supply source outside the sewing machine to the power supply destination inside the sewing machine by the contact operation of the two contacts;
A motor driver circuit capable of switching between a driving state in which a drive current based on a DC power supply is supplied to the motor and a regenerative state in which regenerative power from the motor is output to the DC power supply source side according to a command from the control circuit; In the DC power supply sewing machine provided,
The control unit performs control to switch the motor driver circuit from the driving state to the regenerative state or from the regenerative state to the driving state periodically and temporarily during rotation of the motor. . A motor that is a driving source for operations related to sewing, a control unit that generates an operation command for the motor, and a connection and disconnection from the DC power supply source outside the sewing machine to the power supply destination inside the sewing machine. A mechanical power switch that switches according to operation; a driving state in which a driving current based on a DC power supply is supplied to the motor; and a regenerative state in which regenerative power from the motor is output to the DC power supply source side. In a motor driving method of a DC power supply sewing machine having a motor driver circuit that can be switched by a command,
A detection step of detecting a discharge state between the contacts due to a disconnected state or disconnection of the power switch;
A drive state switching step of temporarily switching the motor driver circuit from the drive state to the regenerative state or from the regenerative state to the drive state when a discharge state between the contact points due to a cut state or a disconnection of the power switch is detected; A method for driving a motor of a DC-fed sewing machine, comprising: A motor that is a driving source for operations related to sewing, a control unit that generates an operation command for the motor, and a connection and disconnection from the DC power supply source outside the sewing machine to the power supply destination inside the sewing machine. A mechanical power switch that switches according to operation; a driving state in which a driving current based on a DC power supply is supplied to the motor; and a regenerative state in which regenerative power from the motor is output to the DC power supply source side. In a motor driving method of a DC power supply sewing machine having a motor driver circuit that can be switched by a command,
A method for driving a motor of a DC-powered sewing machine, wherein the motor driver circuit is periodically and temporarily switched from the drive state to the regenerative state or from the regenerative state to the drive state during rotation of the motor.