JP2021065004A - Servo dc power supply system and motor control unit - Google Patents

Abstract

To provide a servo DC power supply system that can prevent voltage oscillation of a power supply path.SOLUTION: A device is used which comprises: an inverter circuit for converting a supplied direct current into an alternating current for driving a servo motor; and a filter circuit that stabilizes the direct current supplied from a power supply path and supplies the current to the inverter circuit, the filter circuit detecting a variation in voltage or a variation in current of the power supply path, and adjusting the impedance of the filter circuit based on a result of detection so as to prevent the variation in voltage or the variation in current of the power supply path, as motor control units of a servo DC power supply system including a DC power supply, the plurality of motor control units, and a power supply path for distributing and supplying power from the DC power supply to the plurality of motor control units.SELECTED DRAWING: Figure 1

Description

The present invention relates to a servo DC power feeding system and a motor control device.

In factories and the like, a system in which a plurality of servomotors are PWM-driven by a plurality of servo drivers arranged at remote locations (a system composed of a robot and its control device, etc.) is used. In such a system, the switching speed cannot be increased in order to reduce the radiation noise from the long cable between the servomotor and the servodriver, and a large number of cables are required for the connection between the servomotor and the servodriver. There is a problem such as.

A device (hereinafter referred to as a motor control device) in which the converter is removed from the servo driver is placed near each servo motor, and a configuration is adopted in which power is supplied from one DC power supply to multiple inverter circuits via a DC bus. By doing so, the above problem can be prevented from occurring. However, in a system adopting this configuration, the LC circuit on the DC bus side and the inverter circuit side may interfere with each other to oscillate the voltage of the DC bus (see, for example, Non-Patent Document 1).

Masashi Yokoo, Keiichiro Kondo, "Design Method for Damping Control System of Vector Controlled Induction Motor Drive System in DC Electric Railway Vehicles", Institute of Electrical Engineers of Japan D, Vol.135 No.6 pp.622-631 (2015)

The present invention has been made in view of the above problems, and provides a DC power supply, a plurality of motor control devices for controlling servomotors, and a power supply path for distributing and supplying power from the DC power supply to a plurality of motor control devices. An object of the present invention is to provide a technique capable of suppressing the oscillation of voltage in a power supply path in a servo DC power supply system including the above.

The servo DC power supply system according to one aspect of the present invention includes a DC power supply, a plurality of motor control devices, and a power supply path for distributing and supplying power from the DC power supply to the plurality of motor control devices. Then, each motor control device of the servo DC power supply system stabilizes the DC supplied by the inverter circuit for converting the supplied DC into an AC for driving the servo motor and the DC supplied by the power supply path. A filter circuit that supplies to the inverter circuit, and detects voltage fluctuations or current fluctuations in the power supply path, and based on the detection results, the self-filter circuit so that the voltage fluctuations or current fluctuations in the power supply path are suppressed. It is provided with a filter circuit for adjusting the impedance of the inverter.

Oscillation of the voltage in the power supply path occurs when the impedance on the motor side (the portion composed of the inverter circuit and the servomotor) is smaller than the impedance on the power supply side (power supply path side). Therefore, according to the servo DC supply system having the above configuration, it is possible to suppress the oscillation of the voltage in the power supply path.

Further, the motor control device for controlling the servo motor according to one aspect of the present invention is supplied by an inverter circuit for converting the supplied direct current into alternating current for driving the servo motor and a power supply path. It is a filter circuit that stabilizes the direct current and supplies it to the inverter circuit, detects voltage fluctuations or current fluctuations in the power supply path, and suppresses voltage fluctuations or current fluctuations in the power supply path based on the detection results. As described above, a filter circuit for adjusting the impedance of the own filter circuit is provided.

By using this motor control device, it is possible to construct a servo DC supply system in which the oscillation of the voltage of the power supply path is suppressed (the voltage of the power supply path is difficult to oscillate).

The configuration of the filter circuit of the motor control device is not particularly limited. For example, the filter circuit supplies the power supply to the series connection body of the capacitor and the variable resistor arranged between the positive side power line and the negative side power line in the motor control device and the resistance value of the variable resistor. A control unit that controls based on the detection result of the voltage fluctuation or the current fluctuation of the road may be provided. Further, the filter circuit sets the variable resistance inserted in one of the positive wiring and the negative wiring connecting the pair of input terminals and the pair of output terminals and the resistance value of the variable resistance to the one. A control unit that controls the voltage fluctuation or the current fluctuation so as to be suppressed may be provided based on the detection result of the voltage fluctuation or the current fluctuation of the wiring. When adopting these configurations, the variable resistor may be a transistor controlled by the control unit to operate in the active region.

According to the present invention, oscillation of voltage in a power supply line in a servo DC power supply system including a DC power supply, a plurality of motor control devices, and a power supply path for distributing and supplying power from the DC power supply to the plurality of motor control devices. Can be suppressed.

FIG. 1 is an explanatory diagram of a schematic configuration of a servo DC power supply system according to an embodiment of the present invention. FIG. 2 is an explanatory diagram of a schematic configuration of a motor control device in a servo DC power feeding system. FIG. 3A is an explanatory diagram of an equivalent circuit of the servo DC power supply system. FIG. 3B is an explanatory diagram of an equivalent circuit of the servo DC power supply system. FIG. 4 is a diagram for explaining an unstable region of the equivalent circuit shown in FIG. 3B. FIG. 5 is a diagram for explaining the function of the filter circuit. FIG. 6 is an explanatory diagram of another configuration example of the filter circuit.

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

FIG. 1 shows a schematic configuration of a servo DC power supply system according to an embodiment of the present invention.
As shown in the figure, the servo DC power supply system according to the present embodiment is a system in which the DC power supply 30 and the plurality of motor control devices 10 are connected by a power supply path 35.

The DC power supply 30 is a power supply that outputs a predetermined DC voltage. FIG. 1 shows a device that converts three-phase AC from a three-phase AC power source 50 into a DC voltage as a DC power source 30, and the DC power source 30 is a device that converts a single-phase AC into a DC voltage. You may. Further, even if the DC power supply 30 is a rectifier circuit in which a diode is combined (for example, a full-wave rectifier circuit), the DC power supply 30 is a rectifier circuit in which a diode is combined (for example, a full-wave rectifier circuit). Alternatively, it may be an AC-DC converter (for example, a power supply regeneration converter) in which a switching element is used. Further, the DC power supply 30 may be a secondary battery.

The motor control device 10 is a device that controls a servomotor 40 (hereinafter, also simply referred to as a motor 40) in accordance with commands (position command, speed command, etc.) from a higher-level device such as a PLC (Programmable Logic Controller). Details of the motor control device 10 will be described later.

The power supply path 35 is a power supply path in which a plurality of power cables are combined so that the electric power (current) from the DC power supply 30 can be distributed and supplied to each motor control device in the servo DC power supply system. As shown in the figure, a smoothing capacitor 18 is usually provided at a connection portion (between the power supply terminals of each motor control device 10) of the power supply path 35 with each motor control device 10.

FIG. 2 shows the configuration of the motor control device 10 used in the servo DC power supply system according to the present embodiment. As shown in the figure, the motor control device 10 includes an inverter circuit 11, a control unit 12, and a filter circuit 13.

The inverter circuit 11 is a circuit for converting the DC voltage from the DC power supply 30 input via the filter circuit 13 and the power supply path 35 into three-phase AC. The inverter circuit 11 has a configuration in which a U-phase leg, a V-phase leg, and a W-phase leg are connected in parallel between the positive side power line 15p and the negative side power line 15m, and is a motor. The control device 10 is provided with a current sensor 28 for measuring the output current of each leg of the inverter circuit 11.

The control unit 12 is a unit that controls the inverter circuit 11 by PWM (Pulse Width Modulation) in accordance with a command from a host device (PLC or the like). The control unit 12 is composed of a processor (microcontroller, CPU, etc.) and its peripheral circuits. The control unit 12 contains signals from each current sensor 28 and an encoder 41 (absolute encoder or incremental encoder) attached to the motor 40. A signal or the like from the encoder) is input.

The filter circuit 13 is a circuit that stabilizes the direct current input to the own filter circuit 13 and supplies it to the inverter circuit. As shown in the figure, the filter circuit 13 includes a series connection of a capacitor 23 and a transistor 24 arranged between a power line 15p on the plus side and a power line 15m on the minus side, and a vibration voltage detection circuit 21 and a drive circuit. It has 22 and.

The drive circuit 22 is a circuit that applies a voltage to the gate of the transistor 24, which causes the transistor 24 to operate in the active region (linear region), in response to the control signal from the vibration voltage detection circuit 21.

The vibration voltage detection circuit 21 detects a voltage fluctuation (voltage change amount within a predetermined time) of the power line 15p, and when a voltage fluctuation equal to or higher than a predetermined threshold value is detected, the resistance of the transistor 24 increases. This is a circuit for changing the level of the control signal to the drive circuit 22. The vibration voltage detection circuit 21 has a function of changing the level of the control signal to the drive circuit 22 according to an instruction from the host device, and a state in which it can be considered that there is no voltage fluctuation of the power line 15p continues for a specified time. It also has a function of changing the level of the control signal to the drive circuit 22 in the direction in which the resistance of the transistor 24 decreases.

The servo DC power supply system according to the present embodiment has the configuration described above. Therefore, according to the servo DC power supply system, it is possible to suppress the oscillation of the voltage of the power supply path 35.

Specifically, in the servo DC power supply system having the configuration shown in FIG. 1, the impedance on the motor side (the portion composed of the plurality of motor control devices 10 and the plurality of motors 40) is expressed as Zm, as shown in FIG. 3B. It can be represented by an equivalent circuit.

In FIG. 3B, L ₁ is the inductance of the power supply path 35, and r _L is the series resistance of _{L 1.} Further, C ₁ is the combined capacitance of the capacitance of the power supply path 35 and the capacitance of the smoothing capacitor 18, and r _C is the series resistance of _{C 1.}

_{The peak value Zo-peak} of the output impedance on the DC power supply 30 side in this equivalent circuit (FIG. 3B) is represented by the following equation.

Then, as schematically shown in FIG. 4, when "Z _o-peak >Zm" is established, the voltage of the power supply path 35 becomes unstable. Therefore, if the _Zo-peak value is reduced, it is possible to prevent the voltage of the power supply path 35 from becoming unstable (oscillating).

As described above, the filter circuit 13 is provided in front of the inverter circuit 11 of each motor control device 10 (FIG. 2) of the servo DC power supply system.

The filter circuit 13 has a configuration in which the resistance of the transistor 24 is controlled by the vibration voltage detection circuit 21 to a resistance at which the voltage of the power supply path 35 does not become unstable. Therefore, in the servo DC power supply system according to the present embodiment, as schematically shown in FIG. 5, the Zoo _{-peak value (Zo-peak} value) is higher than that in the system in which the servo control device without the filter circuit 13 is used. The maximum value of the output impedance on the power supply 30 side including the filter circuit 13) can be lowered. As a result, it is possible to prevent the voltage of the power supply path 35 from becoming unstable (oscillating).

《Transformation form》
The servo DC power supply system according to the above-described embodiment can be modified in various ways. For example, the power supply path 35 has a configuration different from that shown in FIG. 1 as long as the power (current) from the DC power supply 30 can be supplied to all the motor control devices 10 in the servo DC power supply system. It may be. Further, as the filter circuit 13, a circuit having a configuration different from that described above may be used. For example, instead of the transistor 24 of the filter circuit 13 (FIG. 2), a plurality of resistors and a selector for inserting one of these resistors between one end of the capacitor 23 and the power line 15 m on the minus side are provided. You may. Further, the circuit having the configuration shown in FIG. 6, that is, between the transistor 24 inserted in the power line 15p on the positive side, the vibration voltage detection circuit 21 and the drive circuit 22 for controlling the resistance of the transistor 24, and the power line 15p, 15m. A circuit composed of the capacitors 23 arranged in the above may be adopted as the filter circuit 13. The filter circuit 13 having the configuration shown in FIG. 6 may be transformed into a circuit in which the transistor 24 is inserted in the power line 15p on the minus side. Further, the vibration voltage detection circuit 21 may be a circuit for detecting the current fluctuation of the power line 15p or the power line 15m.

Further, when the voltage of the power supply path 35 fluctuates, the current flowing through the power supply path 35 also fluctuates. Then, if the current fluctuation is suppressed, the voltage fluctuation is suppressed. Therefore, the filter circuit 13 detects the current fluctuation of the power supply path 35, and the impedance of the own circuit is suppressed so that the current fluctuation is suppressed. It may be an adjustable circuit. After making the filter circuit 13 in each motor control device 10 a circuit whose threshold value can be set from the outside, the servo DC power supply system is transformed into a system operated while adjusting the threshold value set in each filter circuit. You can leave it.

<< Appendix 1 >>
A servo including a DC power supply (30), a plurality of motor control devices (10), and a power supply path (35) that distributes and supplies power from the DC power supply (30) to the plurality of motor control devices (10). In the DC power supply system
Each of the plurality of motor control devices (10)
An inverter circuit (11) for converting the supplied direct current into alternating current for driving the servo motor (40), and
A filter circuit (13) that stabilizes the direct current supplied by the power supply line (35) and supplies it to the inverter circuit (11), and detects voltage fluctuations or current fluctuations in the power supply line (35). Based on the detection result, the filter circuit (13) that adjusts the impedance of the own filter circuit (13) so that the voltage fluctuation or the current fluctuation of the power supply path (35) is suppressed.
To prepare
Servo DC power supply system.

<< Appendix 2 >>
A motor control device (10) that controls a servomotor (40).
An inverter circuit (11) for converting the supplied direct current into alternating current for driving the servomotor (40), and
A filter circuit (13) that stabilizes the direct current supplied by the power supply line (35) and supplies it to the inverter circuit (11) by detecting voltage fluctuations or current fluctuations in the power supply line (35). Based on the detection result, the filter circuit (13) that adjusts the impedance of the own filter circuit (13) so that the voltage fluctuation or current fluctuation of the power supply path (35) is suppressed.
(10).

10 Motor controller 11 Inverter circuit 12 Control unit 15p Plus side power line 15m Negative side power line 18 Smoothing capacitor 21 Vibration voltage detection circuit 22 Drive circuit 23 Capacitor 24 Transistor 25 Inductor 28 Current sensor 30 DC power supply 35 Power supply path 40 Servo motor 41 Inverter 50 Three-phase AC power supply

Claims (5)

In a servo DC power supply system including a DC power supply, a plurality of motor control devices, and a power supply path for distributing and supplying power from the DC power supply to the plurality of motor control devices.
Each of the plurality of motor control devices
An inverter circuit for converting the supplied direct current into alternating current for driving the servo motor,
A filter circuit that stabilizes the direct current supplied by the power supply path and supplies it to the inverter circuit. It detects voltage fluctuations or current fluctuations in the power supply line, and based on the detection result, the voltage of the power supply line. A filter circuit that adjusts the impedance of its own filter circuit so that fluctuations are suppressed, and
To prepare
Servo DC power supply system. A motor control device that controls a servo motor.
An inverter circuit for converting the supplied direct current into alternating current for driving the servomotor, and
A filter circuit that stabilizes the direct current supplied by the power supply line and supplies it to the inverter circuit. It detects voltage fluctuations or current fluctuations in the power supply line, and based on the detection result, voltage fluctuations in the power supply line. Or, a filter circuit that adjusts the impedance of its own filter circuit so that current fluctuations are suppressed,
A motor control device equipped with. The filter circuit
A series connection of a capacitor and a variable resistor arranged between the positive power line and the negative power line in the motor control device, and
A control unit that controls the resistance value of the variable resistor based on the detection result of voltage fluctuation or current fluctuation of the power supply path.
To prepare
The motor control device according to claim 2. The filter circuit
A variable resistor inserted in one of the positive and negative wirings that connects the pair of input terminals and the pair of output terminals,
A control unit that controls the resistance value of the variable resistor so that the voltage fluctuation or the current fluctuation is suppressed based on the detection result of the voltage fluctuation or the current fluctuation of the one wiring.
To prepare
The DC power supply device according to claim 2. The variable resistor is a transistor controlled by the control unit to operate in the active region.
The motor control device according to claim 3 or 4.

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