JP2005253213A - Method and device for controlling multi-axis motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a motor control device for efficient regeneration even with multi-axis configuration. <P>SOLUTION: The motor control device in regenerative operation outputs a regeneration on signal, while another motor control device performs regenerative operation when receives the regeneration on signal. So the regenerative processes of all motor control devices occur at the same time, and the load of a regenerative process circuit comes to be uniform for efficient operation. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to regenerative processing when a single-axis motor control device has a multi-axis configuration.

FIG. 6 shows a conventional example in which a conventional single-axis motor control device is connected in multiple axes.
In FIG. 6, reference numeral 210 denotes a controller for controlling the servo device, 201, 202 and 203 are servo control devices, 204, 205 and 206 are motors, and 207, 208 and 209 are encoders. Furthermore, 211 is a three-phase power source and is connected to the external terminals R, S, and T of the servo devices 201, 202, and 203. Reference numeral 212 denotes a rectifier circuit in the servo control device 201, reference numeral 213 denotes an inverter, and reference numeral 214 denotes a control circuit. 215 is a regenerative transistor, 216 is a regenerative resistor, 217 is a smoothing capacitor, 218 is an inrush current prevention circuit, 219 is a dynamic brake (DB) circuit, 220 is a current detector, 221 is a CPU and an ASIC. A DC power source smoothed by a capacitor at the output of the rectifier circuit of the servo control device is output to the external terminals P and N, and the terminals P and N are connected between the servo devices.

  Next, the operation will be described. When the motor is decelerated from a high rotational speed, or when the load is reduced, the motor operates as a generator. When the motor prints as a generator, the current flows back through the loop of the inverter transistor, motor, and diode, and flows from the DC power source to the motor through the freewheel mode (dotted line in FIG. 2) and the transistor, motor, transistor. The time in the back mode (dotted line in FIG. 2) for returning from the motor to the DC power source through the diode, motor, and diode is longer than the time in the drive mode (solid line in FIG. 2). For this reason, the smoothing capacitor is charged more than the discharging current, and the DC voltage of the smoothing capacitor increases. When the DC voltage becomes higher than the predetermined first voltage, the CPU + ASIC in block 221 enables the regeneration on signal to turn on the regeneration transistor 215. When the regenerative energy is large and the DC voltage VDC rises and exceeds a predetermined overvoltage (VOV), the drive signal of the inverter 213 and the regenerative transistor 215 is turned off, the dynamic brake circuit 219 is turned on, and the motor terminal Is short-circuited electronically with a resistor and stopped, and an overvoltage alarm is output to the outside through the interface. Normally, when the regenerative transistor is turned on, the DC voltage decreases. When the DC voltage becomes lower than the second voltage VLW, the regeneration on signal is invalidated and the regeneration transistor 215 is turned off.

  Next, a case where a multi-axis motor control device is configured by driving a plurality of single-axis motor control devices will be described. In the configuration of the multi-axis motor drive device, the P side and the N side of all the motor control devices are connected to each other, the DC power supply is made common, and the load as the DC power supply is averaged. A motor controller having a large capacity uses a power rectifier diode and a voltage smoothing capacitor having a capacity corresponding to the motor controller, so that a direct current corresponding to the rated capacity of the motor controller almost flows. In addition, the multi-axis motor drive device instantaneously has both power running and regenerative shafts. By using a common DC power supply, it can be handled as the total amount of power for all axes. Can be consumed again, and the regenerative processing power is reduced, resulting in power saving.

  However, the first voltage and the second voltage vary depending on the motor control device, and there arises a problem that the regenerative power is concentrated on a specific axis. FIG. 5 is an example in which two-axis motor control devices are connected in multiple axes, and is a simulation when the first voltage VUP and the second voltage VLW are changed. The first voltage on the first axis is 381V, the second voltage is 371V, the first voltage on the second axis is 380V, the second voltage is 370V, and the voltage on the second axis is low. Concentrate on the axis. Generally, the regenerative power is concentrated on the motor control device having the lowest first voltage VUP. Depending on the operation mode, the regenerative power of all axes is concentrated on a specific single-axis motor control device.

Patent Document 1 is a conventional technique in which regeneration processing of a motor control device that is normally used on one axis is averaged on all axes. This prior art will be described with reference to FIG.
In FIG. 3, 101 is a power source, 102A to 102C are control devices, 103 is a converter circuit, 104 is a regenerative circuit, 105 is an inverter circuit, 106 is a motor, 107 is a regenerative circuit drive base circuit, 108 is a CPU, 109 is a PN voltage. A detection circuit, 110 is a P terminal, and 111 is an N terminal. Reference numeral 117 denotes a CPU of the controller, 118 denotes an output interface of the controller, and 119 denotes an input interface of the controller. Each PN terminal from 102A to 102C is connected to the control device.

  Next, the operation will be described. In the conventional technology, the regenerative load unit on the shaft must be installed as a whole to rebalance the regenerative load, which not only requires space but also increases the system price and is uneconomical. In order to solve this problem, each control device shares the PN voltage, thereby improving the regenerative processing capacity of the entire system and allowing the regenerative circuits provided in each axis system control device to operate equally. Thus, the difference in regenerative load consumption between motor control devices is minimized.

  A regenerative method for a motor control system includes a regenerative circuit and a terminal that exhibits a PN voltage, and controls a plurality of control devices that control a motor of a plurality of axes corresponding to each of the plurality of axes, and each of the control devices. A system regenerative method comprising a system controller, wherein all control devices share a PN voltage, and regenerative load data having a level corresponding to the regenerative load obtained in each of the control devices is transferred to the system controller. The controller evaluates the level of the regenerative load data, generates a command to increase the regenerative circuit operation level for the control device corresponding to the larger regenerative load data, and the control device corresponding to the smaller regenerative load data. In this case, a command to lower the regenerative circuit operation level is generated.

JP 11-89285 A

However, the conventional motor control device requires a system controller, and requires a lot of information transmission between the system controller and the control device. The system controller must evaluate the level of regenerative load data, It took time and the configuration was complicated.
The present invention has been made in view of such problems, and the motor control device during the regenerative operation outputs a regenerative on signal, and the other motor control devices receive the regenerative on signal and perform a regenerative operation. Provided is a multi-axis motor control method and apparatus in which the regeneration processing of all motor control devices operates simultaneously, the load of the regeneration processing circuit is made uniform, and the operation can be performed efficiently.

  The present invention according to claim 1 includes a rectifier circuit that rectifies an AC power source to convert it into a DC voltage, a PWM inverter that converts the DC voltage into an AC voltage, and a first voltage having a predetermined upper limit voltage. When it exceeds, turn on the regenerative transistor connected in series with the regenerative resistor, and when it becomes below the second voltage of the predetermined lower limit voltage, the main circuit consisting of the regenerative processing circuit that turns off the regenerative transistor, and the controller of the host system A control circuit that performs position control, speed control, and current control using position or speed commands as input, position data of the position detector coupled to the motor and motor current, and current data as feedback is provided. In the multi-axis motor control method of the motor control device used in the motor, the multi-axis motor control device is configured by connecting multiple units at the DC voltage site. If the regenerative on signal that indicates whether the regenerative transistor of each axis is on or off is ON even in one of a plurality of control devices, the regenerative transistors of all the control devices are turned on. Is.

  According to a second aspect of the present invention, in the motor control method according to the first aspect, a regeneration ON signal of each axis is output to the outside, and the regeneration ON signals of a plurality of control devices are connected to each other to form a wired OR. If at least one of the regeneration on signals of the plurality of control devices is on, the regeneration transistors of all the control devices are turned on.

  A third aspect of the present invention provides the motor control method according to the first or second aspect, further comprising regenerative resistance temperature estimating means for estimating a temperature of the regenerative resistance, wherein the regenerative resistance estimated temperature exceeds a preset first temperature. In this case, a regeneration on inhibition signal is generated to inhibit the regeneration transistor from turning on, and the regeneration on inhibition signal is canceled when the regeneration resistance temperature falls below the second temperature.

  According to a fourth aspect of the present invention, there is provided a rectifier circuit that rectifies an AC power source to convert it into a DC voltage, a PWM inverter that converts a DC voltage into an AC voltage, and a first voltage having a predetermined upper limit voltage. When the value exceeds, the regenerative transistor connected in series with the regenerative resistor is turned on, and when the voltage falls below the second voltage of the predetermined lower limit voltage, the main circuit comprising the regenerative processing circuit that turns off the power element, and the host system It is equipped with a control circuit that receives position or speed commands from the controller, detects position data of the position detector coupled to the motor and the motor current, and uses the current data as feedback to perform position control, speed control, and current control. In a motor control device used for one axis, a multi-axis motor control device is configured by connecting a plurality of the motor control devices at a DC voltage site. A means for outputting a regenerative on signal that indicates whether the regenerative transistor of each axis is on or off, a means for connecting the regenerative on signals of a plurality of control devices to each other to form a wired OR, and a plurality of means If at least one of the control devices of the control device has a regenerative on signal, the control device includes means for turning on the regenerative transistors of all the control devices.

  According to the motor control method of the present invention, when one of the motor control devices during the regenerative operation is turned on, the regenerative on signal is output, and the other motor control devices receive the regenerative on signal and perform the regenerative operation. Therefore, the regenerative processing of all the motor control devices operates simultaneously, the load of the regenerative resistance is averaged, and an efficient control method and apparatus for a multi-axis motor can be provided.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 is a block diagram showing an embodiment of a multi-axis motor control device of the present invention. In FIG. 1, 1, 2, and 3 are motor control devices, 4, 5, and 6 are motors, 7, 8, and 9 are encoders, 10 is a controller that controls each motor control device, and 11 is a three-phase power source. 12 is a rectifier, 13 is an inverter, and 14 is a control board. Reference numeral 15 denotes a regenerative transistor, 16 a regenerative resistor, 17 a smoothing capacitor, 18 an inrush current prevention circuit, 19 a DB (dynamic brake circuit), and 20 a current detection circuit. Further, 21 is a CPU + ASIC, 22 is a switch, 23 is a pull-up resistor, 24 is an inversion logic, and 25 is an AND logic.

  Next, the operation will be described. The three-phase power supply 11 supplies power to the power input terminals of the motor control devices 1, 2, and 3. The motor control device 1 receives a three-phase power supply and converts alternating current into direct current with a rectifier. When the power is turned on, since the electric charge is not charged in the smoothing capacitor, a large current rushes into the smoothing capacitor 17. For this reason, the inrush prevention circuit 18 limits the current with a resistor. When the limited current charges the smoothing capacitor and rises to a predetermined voltage, the control circuit 14 turns on the switch of the inrush prevention circuit 18 and shorts the resistance of the inrush prevention circuit 18. The DC voltage converted to DC is supplied to the inverter 13 and output to the external terminals P and N. The inverter 13 is driven by the PWM gate signal of the control circuit 14 and applies a DC voltage to the motor 4 by PWM. When the PWM voltage is received, the current flows according to the rotation speed and the motor constant, the torque corresponding to the torque constant is generated, and the motor rotates according to the load torque and the moment of inertia.

The current detector 29 detects a three-phase current and feeds it back to the control circuit 14. The encoder 7 is directly connected to the motor and feeds back the rotational position of the motor to the control circuit 14. The control circuit 14 is composed of electronic components such as a CPU, ASIC, and discrete components, and controls an inrush current prevention circuit and a regenerative processing circuit. Further, the control circuit 14 receives the position command and the speed command from the controller 10 of the host system, and controls the inverter at every control sampling time so that the motor follows the command and operates. The position control means of the control device 14 receives the position command of the controller 10 and the position feedback of the encoder, and controls the position deviation to obtain a speed command. The speed conversion means of the control device 14 sets the position feedback position data as speed data by dividing the difference between the position data of one sampling before and the current position data by the sampling time to obtain speed data. The speed control means controls the deviation between the speed command and the speed feedback to obtain a torque command. The current control means multiplies the torque command by a coefficient to obtain a q-axis current command, and sets the d-axis current command to zero in normal control. The coordinate conversion means converts the three-phase feedback current into a dq axis current. The current control means performs a PID process on the deviation between the dq axis current command and the dq axis current feedback to generate a dq axis voltage command. The coordinate conversion means converts the dq-axis voltage command into UVW three-phase coordinates to generate a U-axis voltage command, a V-axis voltage command, and a W-axis voltage command. The PWM generation means converts the three-phase voltage command into a pulse signal that drives the gate of the inverter. The inverter receives the gate signal, turns on and off the switching element, and supplies a PWM voltage to the motor.

  Next, the regenerative processing operation according to the present invention will be described. When the motor decelerates from a high rotational speed, or when the polarity of the motor rotation direction and the motor torque direction are different, such as when the load is lowered, the motor generates power, and some of the generated power is generated by friction load or motor If it is consumed by electrical loss (Joule loss) but the generated power is large, it regenerates power to the inverter. FIG. 2 shows the route through which the inverter current flows for the motor U phase and V phase. The solid line is the drive mode route that flows from the DC power supply to the motor, the dotted line is the back mode route that returns from the motor to the power supply, and the alternate long and short dash line is the freewheel mode route in which the motor is short-circuited regardless of the power supply. During power running, the drive mode and freewheel mode are alternately repeated, and the power is directed from the power source to the motor, and during regenerative operation, the drive mode or freewheel mode and back mode are alternately repeated, and the power is averaged by the motor. It is regenerated from the power source. During the regenerative operation, the back mode current charges the smoothing capacitor, and the voltage of the smoothing capacitor rises. The regenerative processing circuit monitors the DC voltage of the smoothing capacitor so that the voltage of the smoothing capacitor does not exceed the withstand voltage of the component. Insert into the to discharge the charge of the smoothing capacitor. When the DC voltage drops due to the discharge and reaches the lower limit voltage, the regeneration transistor is turned off to stop the discharge. Even if the discharge is stopped, the DC voltage rises again if the power generated by the motor is still large. Thereafter, the same operation is repeated until there is no power generation.

  In the present invention, when using multiple axes, the external terminals P and N are connected to each other, and the external terminal R indicating a regeneration on signal is connected. If the regenerative transistor is turned on even in one of the multiple axes, the regenerative on signals are connected to each other by a wired OR, so that the regenerative transistors on the other axes are also turned on, and all the regenerative transistors operate in the same manner. In this way, the configuration is simpler than that of Patent Document 1, and it is possible to avoid a load from being concentrated on a single-axis regenerative processing circuit when connected to multiple axes as in the prior art.

Next, Example 2 will be described. The second embodiment is configured to prevent abnormal overheating of the regenerative resistor of the first embodiment, and is applied to each motor control device. This will be described with reference to FIG. FIG. 3 is a flowchart for preventing abnormal overheating. Processing is performed at each control sampling time. Step ST1 checks the state of the regenerative transistor. If the regenerative transistor is on, the process proceeds to step ST2, and if it is off, the process proceeds to step ST4. In step ST2, a DC voltage is read, and the process proceeds to step ST3. In step ST3, the loss of the regenerative resistance is calculated from the DC voltage and the regenerative resistance value. The calculation formula is Formula (1).
P = Vdc * Vdc / R (1)
In step ST4, since the regenerative resistor is off, P = 0 is set.

In step ST5, a temperature rise value is calculated using a heat equivalent circuit of a regenerative resistor. FIG. 5 shows a heat equivalent circuit of a regenerative resistor fixed to the fin. 70 is a generated loss P, 71 is a thermal resistance R1 between the resistor and the resistance outer skin, 72 is a thermal resistance R2 between the resistance outer skin and the fin, and 73 is between the fin and the atmosphere. Thermal resistance R3. Reference numeral 74 denotes a heat capacity C1 of the resistor and the outer skin, and 75 denotes a heat capacity C2 of the fin. The value of temperature rise θ is calculated using equation (2).
θ = P * R ₁ + θ ₁ + θ ₂ (2)
Here, θ is a temperature rise value, and P is a loss of regenerative resistance. Further, t1, t2, θ1, and θ2 can be expressed by the following equations.
t ₁ = 2C ₁ C ₂ R ₂ R ₃
/ (C ₁ (R ₂ + R ₃ ) + C ₂ R ₂ + √ (C ₁ ² (R ₂ + R ₃ ) ² ) -4C ₁ C ₂ R ₂ R ₃ )
(3)
t ₂ = 2C ₁ C ₂ R ₂ R ₃
/ (C ₁ (R ₂ + R ₃ ) + C ₂ R ₂ −√ (C ₁ ² (R ₂ + R ₃ ) ² ) −4C ₁ C ₂ R ₂ R ₃ )
(4)
θ ₁ = θ ₁₀ * exp (−t _s / t ₁ ) +
_{P (1-exp (-t s} / t 1)) (C 2 R 2 R 3 - (R 2 + R 3) t 1) / (t 2 -t 1)
(5)
θ ₂ = θ ₂₀ exp (−t _s / t ₂ ) +
_{P (1-exp (-t s} / t 2)) (C 2 R 2 R 3 - (R 2 + R 3) t 2) / (t 1 -t 2)
(6)
Here, θ ₁₀ and θ ₂₀ are temperature rise values before one sampling.

In step ST6, the temperature increase value θ is compared with a predetermined first temperature. If the temperature rise value is large, the process proceeds to step ST7, and if small, the process proceeds to step ST8. Step ST7 forcibly turns off its own regenerative processing circuit even if the regenerative signal is turned on from its own motor control device. This is done by blocking the AND in FIG. 1 from the CPU + ASIC. Step ST8 compares the temperature rise value θ with the second temperature. If temperature rise value (theta) is lower than 2nd temperature, it will progress to step ST9, and if higher, it will progress to step ST10. Step ST9 cancels the forced off of the regeneration processing circuit. Therefore, if the regeneration processing transistor is on, the regeneration processing transistor is turned on again. Step ST10 maintains the state before one sampling.
In the case where the single-axis motor control device is configured with multiple axes, only the regenerative resistor whose temperature is higher than the first temperature is turned off, so that the utilization rate of the regenerative processing resistor can be increased.

  In the present invention, the motor control device during the regenerative operation outputs a regenerative on signal, and the other motor control devices receive the regenerative on signal to enter the regenerative operation, and the regenerative processing of all the motor control devices operates simultaneously. Since the load of the regenerative processing circuit is made uniform and efficient operation is possible, it can be applied to multi-axis applications such as general industrial machines, robots, and machine tools.

The block diagram which shows Example 1 of this invention Diagram showing current flow in regenerative operation The flowchart which shows Example 2 of this invention. Operation time chart of regenerative transistor in the case of two axes according to the present invention Regenerative resistor equivalent circuit Configuration diagram of conventional example 1 Operation time chart 1 of a regenerative transistor in the case of two axes in the conventional example Operation time chart 2 of regenerative transistor in the case of two axes in the conventional example Operation time chart 3 of regenerative transistor in the case of two axes in the conventional example Configuration diagram of Conventional Example 2

Explanation of symbols

1, 2, 3 Motor control device 4, 5, 6 Motor
7, 8, 9 Encoder 10 Controller 11 Three-phase power supply 12 Rectifier 13 Inverter 14 Control circuit 15 Regenerative transistor 16 Regenerative resistor 17 Smoothing capacitor 18 Inrush current prevention circuit 19 DB circuit 20 Current detector 21 CPU + ASIC
22 switch 23 pull-up resistor 24 inversion logic 25 AND logic value 31 power supply line 32 P terminal connection line 33 N terminal connection line 34 controller connection line 35 R terminal connection line 70 loss source 71 thermal resistance R1
72 Thermal resistance R2
73 Thermal resistance R3
74 Heat capacity C1
75 Heat capacity C2
76 Resistance resistor 77 Resistance outer skin 78 Fin

Claims (4)

A rectifier circuit that rectifies an AC power source to convert it to a DC voltage, a PWM inverter that converts the DC voltage to an AC voltage, and a regenerative resistor that is connected in series when the DC voltage exceeds a predetermined first upper limit voltage. When the regenerative transistor is turned on and the voltage falls below the second voltage of the predetermined lower limit voltage, the position or speed command is input from the main circuit comprising the regenerative processing circuit that turns off the regenerative transistor and the host system controller. , A motor control device that includes a control circuit that detects position data and motor current of the position detector coupled to the motor and performs position control, speed control, and current control using the current data as feedback, and is normally used on one axis In the multi-axis motor control method of
A multi-axis motor control device is configured by connecting a plurality of units at the DC voltage site,
If the regenerative on signal indicating whether the regenerative transistor of each axis is on or off, even if one of the plurality of control devices is on, the regenerative transistors of all the control devices are turned on. Multi-axis motor control method.   The regeneration on signal of each axis is output to the outside, the regeneration on signals of a plurality of control devices are connected to each other to form a wired OR, and at least one regeneration on signal of the plurality of control devices is on. Then, the multi-axis motor control method according to claim 1, wherein the regenerative transistors of all the control devices are turned on.   Regenerative resistance temperature estimating means for estimating the temperature of the regenerative resistance is provided, and when the regenerative resistance estimated temperature exceeds a preset first temperature, a regeneration on inhibition signal is generated to turn on the regeneration transistor. 3. The multi-axis motor control method according to claim 1, wherein the regenerative on prohibition signal is canceled when the regenerative resistance temperature falls below the second temperature. A rectifier circuit that rectifies the AC power source and converts it to a DC voltage, a PWM inverter that converts the DC voltage to an AC voltage, and a regenerative resistor connected in series when the DC voltage exceeds a predetermined upper limit voltage The regenerative transistor is turned on, and when the voltage becomes equal to or lower than a second voltage of a predetermined lower limit voltage, a position or speed command is input from a main circuit comprising a regenerative processing circuit that turns off the power element, and a host system controller And a control circuit that detects position data and motor current of the position detector coupled to the motor and performs position control, speed control, and current control using the current data as feedback, and is normally used for one axis. In the device
A multi-axis motor control device is configured by connecting a plurality of the motor control devices at the DC voltage site,
Means for outputting a regeneration on signal that indicates whether the regeneration transistor of each axis is on or off;
Means for connecting the regeneration on signals of the plurality of control devices to each other to form a wired OR;
A multi-axis motor control device comprising: means for turning on the regenerative transistors of all the control devices if the regenerative on signal is valid even in one of the plurality of control devices.

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