JP2849266B2 - Servo control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a servo control device for controlling driving of a motor by inverter control.

[0002]

2. Description of the Related Art Conventionally, a servo control device for controlling the driving of a motor by inverter control has a regenerative discharge resistor for consuming kinetic energy regenerated by the control device when stopping the motor. FIG. 3 is a circuit diagram illustrating a configuration of an inverter control unit that performs power control of a general servo control device. This servo control device has a servo control device main body 1. The servo control device main body 1 has a power control unit 2 for controlling a motor, and a heating detection detected by an output of a thermal reed switch 3 inside the servo control device main body. It has a circuit 4 and a regenerative discharge control circuit 5 for controlling each part. The power control unit 2 further includes a rectifier diode bridge 7 and a smoothing capacitor 8 that convert an AC current supplied from an AC power supply 6 into a DC current, and an internal device that consumes kinetic energy of the motor 9 that is regenerated when the motor 9 is stopped. Turns on the power supply to the regenerative discharge resistor 10 and the internal regenerative discharge resistor 10,
It has a transistor 11 that is turned off, and a rectifier inverter bridge 12 that converts a DC current converted by the rectifier diode bridge 7 and the smoothing capacitor 8 into an AC current and sends the AC current to the motor 9. The servo control device main body 1 has terminal groups 13, 14, 15, 16, and 17. Terminal 1
The terminals 3 and 14 are connected to the internal regenerative discharge resistor 10, the terminal 15 is connected to a line connecting the rectifier diode bridge 7 and the rectifier inverter bridge 12, and the terminals 16 and 1 are connected to each other.
Reference numeral 7 is connected to the thermal reed switch 3, the terminals 14 and 15 are connected by a connection 18, and the terminals 16 and 17 are connected by a connection 19. Further, as shown in FIG.
An external regenerative discharge resistor unit 20 having an external regenerative discharge resistor having a desired resistance value and a permissible loss can be connected to the outside as necessary to secure a desired regenerative power consumption capability. The external regenerative discharge resistance unit 20 has terminal groups 21, 22, 23, and 24. Terminal 21, 2
Between the two, the external regenerative discharge resistors 25 and 26 having the same resistance value as the internal regenerative discharge resistor 10 and having only several times the allowable loss.
Are connected in parallel, and a thermal reed switch 27 for detecting heat in the external regenerative discharge resistance unit 20 is connected between the terminals 23 and 24. When the external regenerative discharge resistance unit 20 is connected to the servo control device body 1, the connections 18 and 19 are cut off, the terminals 13 and 21 are connected by the connection 28, the terminals 15 and 22 are connected by the connection 29, and the terminal 16 is connected. And 23 are connected by a connection 30, and the terminals 17 and 24 are connected by a connection 31.

Next, the operation will be described. The AC current supplied from the AC power supply 6 is exchanged into a DC voltage by the rectifying diode bridge 7 in the power control unit 2 and the smoothing capacitor 8. Numeral 12 denotes an inverter bridge composed of a group of power switching elements such as power transistors, which gives an arbitrary drive current to the motor 9 by controlling ON / OFF of these. FIG. 5 is a time chart showing the motor speed, motor torque, and motor output when the motor 9 is accelerated / decelerated by the servo control device shown in FIG. Servo control apparatus, by outputting a driving current corresponding to the motor acceleration torque + T _a, the motor starts accelerating operation in the positive direction. t _a is the acceleration time of the motor, at which time the motor reaches a predetermined speed W ₀ . In the constant speed operating time t _0, the current corresponding to the load torque + T _e is from servo controller, is supplied to the motor. When the constant speed operation time ends, the servo control device outputs a current corresponding to the motor deceleration torque, and the motor starts the deceleration operation. Here, assuming that the deceleration time is equal to the acceleration time, the deceleration torque T
_d is the J, when the supply inertia of the motor and the load, and _{T d = -J (W 0 /} t a) + T e. Further, from the accelerated _{conditions, T a = J (W 0} / t a) + T e So, after all, deceleration torque T _{d is, T d = -T a +2 ·} T e = - a (T _a -2T _e) . Motor, after the stop, through the rest time of t _s,
Repeated operation of a series of operations was defined as one cycle time t _c so far. The motor output P in FIG. 5C is represented by a relational expression P = T · W with the motor speed W and the motor torque T (see FIG. 5B). This indicates that the motor is operating as a generator during the deceleration operation in which the motor output has a positive sign. Effective torque T _c in one cycle time t _c is the rated torque of the motor and T _m, T _c
The relationship of ≦ T _m holds. Thus, where _{T m ≧ T c = {(} T a 2 · t a + T e 2 · t 0 + T d 2 · t d) / t c} 1/2, the _{T e T e = βT m (} β is replacing the _{constant), T m ≧ {(T} a 2 · t a + (βT m) 2 (t 0 -t s -2t a) + (T a -2 βT m) 2 · t a) / t c ｝ ^1/2 . By transforming this into an equation, the stop operation duty t _a
/ _Tc is t _a / t _c ≦ {(T _m ² −β ² T _m ² ) / 2 (T _a −βT _m ) ² } + ｛(β ² T _m ² ) / 2 (T _a −β T ^{_{m) 2} t s / t}} c t a / t c ≦ (1-β 2 + β 2 t s / t c) / 2 {(T a / T m) -β} 2 = {1-β 2 (t _c− t _s ) / t _c ｝ / 2 ｛(T _a / T _m ) −β｝ ² (1) The area U (shaded area) of the motor output waveform at the time of deceleration shown in FIG. 5C is represented by the following equation. However,
Integral range is from t ₁ to t _2.

[0004] U = ∫Pdt = 1/2 ( P d · t a) ... (2) an area U of the motor output waveform, the motor becomes a generator,
It is the amount of energy that regenerates kinetic energy, including load, to the servo controller. The kinetic energy regenerated is
In the power control unit 2 of FIG. 3, the form is changed to the electrostatic energy of the capacitor 8. Assuming that the capacitor voltage at t = t ₁ at the start of motor deceleration is V ₀ and the capacitance of the capacitor is C, the capacitor voltage V at t = t ₂ at motor stop is ・ · C (V ² −V ₀ ²⁾ = is represented by _{1/2 · P d · t} a, the capacitor voltage as a result rises.

In FIG. 3, a regenerative discharge control circuit 5 is a hysteresis circuit having a capacitor voltage as input and having two threshold voltages V ₁ and V ₂ (where V ₁ > V ₂ ). When the voltage V is V> V ₁
Then, by turning on the discharge transistor 11, the electrostatic energy of the capacitor 8 is discharged and consumed through the internal regenerative discharge resistor 10 inside the servo control device main body 1. After that, when V> V ₂ , the transistor OF
It has a function of performing the F operation and stopping the discharging operation. (1)
Wherein (2) and from the time chart of FIG. 5, the loss P _R of the regenerative discharge resistor 10 _{is, P R = U / t c} = 1/2 · P d · t a / t c ≦ {1-β 2 become _{(t c -t s) / t} c} / 4 {(T a / T m) -β} 2 · P d ... (3). Here, since it is _{Pd = Td · W 0 = (} Ta -2βTm) W 0 = {(Ta / Tm) -2β} Tm · W 0, when the W ₀ and the rated motor speed, motor rated output P _m is , P because becomes _m = T _m · W _0, the substituting these into equation (3), to represent the P _R at _{P m, P R ≦ {1} -β 2 (t c -t s) / t c {/ 4} (T _a / T _m ) −β} ² · P _d = {1−β ² (t _c −t _s ) / t _c } / 4} (T _a / T _m ) −β} ^2. {(T _a / T _m ) −2β} · P _m (4) For example, as general numerical values, T _a / T _m = 3, β =
0.3, substituting _{(t c -t s) / tc} = 1/2 in equation ^{_{(4), P R ≦ (1-0.3 2 ·}} 0.5) / 4 (3-0.3) ² · (3-0.6) P _m . This indicates that, when the acceleration / deceleration operation is performed under the condition of the rated torque and the rated speed, a discharge regenerative resistor having an allowable loss close to 10% of the rated output of the motor is required. However, as shown in the above equation, even in a servo control device having the same driving capability, the discharge regenerative resistance is required by the difference in the rated output of the applied motor and the motor speed at the time of constant speed running determined by the application. The allowable loss changes greatly. Therefore, in consideration of the cost and size of the servo control device, the optimum configuration is taken into consideration, and the servo control device body usually has a capacity of a fraction of the required maximum allowable loss at the maximum motor capacity to be applied. For applications exceeding this capacity by installing a regenerative discharge resistor having a regenerative discharge resistance, an external regenerative discharge resistor unit having a large permissible loss is installed outside the control device body, and a corresponding system configuration is adopted. Further, the resistance value R of the regenerative discharge resistance is determined by the instantaneous loss V
² / R is, since it is necessary to set larger than the instantaneous maximum regenerative power P _d of the motor, it can be uniformly determined.

In FIG. 3, overheating of the regenerative discharge resistor 10 inside the control device main body is detected by a thermal reed switch 3 and an overheating detecting circuit 4 which receives the output as an input. When overheating is detected, the overheating detecting circuit 4 stops the operation of the rectifier inverter bridge 12, stops the regenerative operation of the motor 9, and prevents the control device from causing an abnormal rise in temperature. In applications where overheat detection occurs, it is necessary to increase the allowable loss by installing an external discharge resistance unit. Therefore, as shown in FIG.
External regenerative discharge resistance unit 20
Connect. When the external regenerative discharge resistance unit 20 is connected, the connection 18 on the servo control device main body 1 side is removed, and the servo control device main terminals 13 and 15 and the terminals 21 and 22 of the external discharge resistance unit 20 are connected to the connection 28,
If connected by 29, the external regenerative discharge resistors 25 and 26 can be operated as regenerative discharge resistors of the servo controller.
Further, the thermal reed switch 27 for detecting overheating of the external regenerative discharge resistors 25 and 26 disconnects the connection 19 on the control device main body 1 side, and the control device main body side terminals 16 and 17 and the terminals 23 and 23 of the external regenerative discharge resistance unit 20. If the terminals 24 are connected by the connection lines 30 and 31, respectively, the overheat state of the external regenerative discharge resistors 25 and 26 can be detected by the overheat detection circuit 4 in the servo control device main body 1.

[0007]

However, in the conventional example described above, when the external regenerative discharge resistor unit is attached,
The regenerative discharge resistance and the internal thermal reed switch inside the servo control device main body cannot be used, and the utilization efficiency of parts is degraded in terms of the system as a whole. In addition, providing a thermal reed switch for overheating detection on the external regenerative regenerative resistor unit is difficult in design because the selection of the operating temperature and the mounting location and mounting method are complexly related. There is a problem that the number of connection lines with the apparatus main body increases.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a servo control device for connecting an external biodischarge resistance unit to a servo control device as required. It is an object of the present invention to provide a servo control device capable of improving the use efficiency of components as a whole and simplifying the connection between an external regenerative discharge resistance unit and a control device main body.

[0009]

SUMMARY OF THE INVENTION A servo control device according to the present invention includes a servo control device main body for consuming kinetic energy regenerated from a motor by an internal regenerative discharge resistor. In accordance with a servo control device that connects a regenerative discharge resistor group having a predetermined resistance value and a permissible loss to the outside of the servo control device main body in accordance with the servo control device main body, the internal regenerative discharge resistance of the servo control device main body and the external regenerative discharge resistance are secured. A discharge resistor group is connected in series or in parallel.

[0010]

In the servo control device according to the present invention, the internal regenerative discharge resistor and the external regenerative discharge resistor group of the servo control device main body are connected in series or in parallel. At this time, by detecting overheating of the internal regenerative discharge resistors, the use load ratio of all regenerative discharge resistors can be limited, and overheating can be prevented. The utilization efficiency of components in the entire control device is improved, and the simplification of interconnection is realized.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing one embodiment of the present invention in correspondence with FIG. 3, and the same components are denoted by the same reference numerals and description thereof will be omitted. In the present embodiment, the lead-out terminals for connection between the servo control device main body 1 and the external regenerative discharge unit 20 are the lead-out terminals 13, 14, from the internal regenerative discharge resistor 10 installed in the control device main body 1 to the outside. No. 15 does not have a terminal for drawing out from the overheat detecting thermal reed switch 3 to the outside.

When the external regenerative resistor unit 20 is connected, as shown in FIG. 2, the connection 18 on the servo controller main unit 1 side is removed, and the terminals 13, 14, 15 of the controller main unit are connected by the connections 32, 33, 34. By connecting to the terminals 35, 36, 37 of the external regenerative discharge unit, the external regenerative discharge resistors 38, 39 can be operated as the regenerative discharge resistors of the servo controller. Here, the resistance values and the allowable loss of the external regenerative discharge resistors 124 and 125 are determined by the following method.

(A) Determination of resistance value According to the connection system shown in FIG. 2, the external regenerative discharge resistor 38 is connected in series to the internal regenerative discharge resistor 10 in the control device body 1, and 39 is connected in parallel. Will be. Resistance value of the regenerative discharge resistor 10,38,39 respectively R, and R _1, R _2. Since these combined resistance values are equal to R, R
Assuming that ₂ = αR, R ₁ is determined as follows. R = R · R ₂ / (R + R ₂ ) + R ₁ = {R · R ₂ + R ₁ (R + R ₂ )} / (R + R ₂ ) = {αR ² + R ₁ R (1 + α)} / (1 + α) R = {αR + R ₁ (1 + α)｝ / (1 + α) Therefore, R ₁ = R / (1 + α) (5) R ₂ = αR (6) (b) Determination of permissible loss Next, the internal discharge regeneration of the servo control device body 1 Consider the acceleration / deceleration operation condition of the motor in which the overheat detection thermal reed switch 3 operates when only the resistor 10 is applied. The total ON time of the discharge transistor in one cycle operation is t _s , the one cycle time is t _c , and the ON duty is γ _s
(Γ _s = t _s / t _c ), _assuming that the ON-time regenerative discharge resistance is i, the loss P _RSL of the internal regenerative discharge resistance is P _RSL = i ² · R · γ _s (7) Similarly, consider the acceleration / deceleration operation of the motor when the external regenerative discharge resistor is connected. Assuming that the ON duty during one cycle operation is γ, the power consumptions P _RS , P _R1 , and R _R2 of the regenerative discharge resistors 10, 38, and 39 are expressed by the following equations (5) and (6): P _RS = ｛αR / ( ^{R + αR) i} 2 ·} R · γ = α 2 / (1 + α) 2 · i 2 · R · γ ... (8) P R1 = i 2 · R 1 · γ = 1 / (1 + α) · i 2 · R · γ (9) R _R2 = {αR / (R + αR) i} ² · R · γ = α / (1 + α) ² i ² · R · γ (10) Here, when the thermal reed switch for detecting overheating of the internal regenerative discharge resistor 10 operates, the ON duty is set to γ.
_{If 0} , the loss of the internal regenerative discharge resistor 10 at this time is equal to the equation (7), so that i ² · R · γ _s = α ² / (1 + α) ² · i ² · R · γ ₀ γ ₀ = ( 1 + α) ² / α ² · γ _s (11) is established.

Therefore, the power consumption P _R1L and R _R2L of the external regenerative discharge resistor at this time are as follows from equations (7) to (11).

P _R1L = 1 / (1 + α) · i ² · R · γ ₀ = 1 / (1 + α) · (1 + α) ² / α ² · i ² · R · γ _s = (1 + α) / α ² · i ² · R · γ _s = (1 + α) / α ² · P _RSL (12) R _R2L = α / (1 + α) ² · i ² · R · γ ₀ = α / (1 + α) ² · (1 + α) ² / α ² · i ² · R · γ _s = 1 / α · i ² · R · γ _s = 1 / α · P _RSL (13) Thus, the total power consumption of the regenerative discharge resistor is P _RL = P _RSL + P _R1L + R _R2L = (1+ (1 + α) / α ² + 1 / α) P _RSL = {(1 + α) / α} ² · P _RSL (14), and servo control is performed by connecting an external regenerative discharge resistance unit. the allowable regenerative electric power of the device {(1 + α) / α } increases to ^double.

That is, when the regenerative power consumption capability P _RL required of the servo control device exceeds the allowable loss P _RSL of the regenerative discharge resistance inside the control device main body, the following formula obtained by modifying the formula (14) is obtained. α = 1 / {(P _RL / P _RSL ) ^1/2 -1} (15), the corresponding α is calculated, and the resistance values R ₁ , R of the external regenerative discharge resistance unit 20 are calculated based on this α. ₂ is determined by the equations (5) and (6). In addition, since these maximum allowable losses can be limited by the values obtained from the equations (12) and (13), if the resistance of the rated power that provides an appropriate use load factor is determined based on the temperature rise of the resistance, etc. It will be good.

[0017]

As described above, according to the present invention,
When the external regenerative discharge resistor unit is installed, the resistance group in the unit is configured to be connected in series or parallel to the internal regenerative discharge resistor inside the servo controller. Can be. Also,
The individual resistance value and allowable loss of the external regenerative discharge resistance unit are uniquely determined from the relational expression between the magnitude of the regenerative power consumption required for the servo control device and the resistance value and allowable loss of the regenerative discharge resistor inside the control device. The maximum loss of the external regenerative discharge resistor group, that is, the temperature rise can also be limited only by preventing the overheating of the internal regenerative discharge resistor from being detected. Accordingly, it is not necessary to attach a thermal reed switch for overheat detection to the external regenerative discharge resistance unit, and the configuration of the external regenerative discharge resistance unit can be simplified, and the connection with the inside of the control device body can be simplified. be able to.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of a servo control device according to an embodiment of the present invention.

FIG. 2 is a diagram showing a connection between a servo control device main body according to the present embodiment and an external regenerative discharge resistance unit.

FIG. 3 is a block diagram showing a configuration of a conventional servo control device.

FIG. 4 is a diagram showing a connection between a conventional servo control device main body and an external regenerative discharge resistance unit.

FIG. 5 is a time chart showing the operation of the conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Servo controller main body 3 Thermal reed switch 4 Heat detection circuit 5 Regenerative discharge control circuit 6 AC power supply 7 Rectifier diode bridge 8 Smoothing capacitor 9 Motor 10 Internal regenerative discharge resistor 12 Rectifier inverter bridge 38, 39 External regenerative discharge resistor 18, 32, 33, 34 connection

Claims (1)

(57) [Claims] 1. A servo control device main body for consuming kinetic energy regenerated from a motor by an internal regenerative discharge resistor, and controls the driving of the motor and, if necessary, a predetermined resistance value and a tolerance outside the servo control device main body. In a servo control device that secures a desired regenerative power consumption capability by connecting an external regenerative discharge resistor group for loss, the internal regenerative discharge resistor of the servo controller body and the external regenerative discharge resistor group are connected in series or in parallel. A servo control device, comprising: