JPS6031429Y2 - DC motor control device - Google Patents

Description

[Detailed description of the invention] This invention relates to static Leonard control that performs the torque direction of a DC motor by switching the field current, and particularly relates to a control device for a DC motor that prevents a steep rise in current after switching. .

A conventional DC motor control device of this kind will be explained with reference to the block diagram of FIG.

In the figure, 10 is a speed reference, and a deviation signal between this speed reference 1o and a speed feedback signal 13 of the DC motor 12 obtained from the speed generator 11 is applied to a speed control circuit 14 that performs an integral operation. is applied to the current ratio limiting circuit 16 via the current reference switching circuit 15, and the output of this current ratio limiting circuit 16 is applied to the analog switch 1.
7 and the current control circuit to the voltage limiting circuit 19 in sequence.

A capacitor 29 is connected to the connection point between the analog switch 17 and the current control circuit 18 to generate a discharge voltage that cancels out the residual deviation of the integral quantity from the speed control circuit 14.
An analog switch 30 is connected in parallel to 9, and when the analog switch 30 is closed, a discharge is generated to suppress the inrush current of the armature.

Voltage limiting circuit 19 controls the output of control rectifier 20 in accordance with the output of current control circuit 18 .

The current of the motor 12 is detected by a current detector 21, and is applied as a current feedback signal to the current control circuit 18 via the analog switch 17, as well as to a forward/reverse torque switching logic circuit (hereinafter simply referred to as a logic circuit) 22, which will be described later. do.

On the other hand, the field winding 23 is connected to the control rectifier 24 and the control rectifier 2
5, these control rectifiers 24, 25 connect the field current control circuit 35 to the field current reference 26.
and the current feedback signal 28 from the current detector 27 are applied.

The output signal of the current detector 27 is applied to the logic circuit 22, and further the output signal of the speed control circuit 14 is applied to the logic circuit 22.

Therefore, the logic circuit 22 of the lever throttles the controlled rectifier 24 or 25 that is operating under the condition that the armature current becomes zero, and the gate of the controlled rectifier 24 or 25 that operates under the condition that the field current becomes zero. A command is given to turn off the control rectifier 24 or 25 on the small operation side for a predetermined time period, and the analog switches 17 and 30 are controlled to open and close.

With this configuration, when the analog switch 17 is closed and the analog switch 30 is closed, the control rectifier 24 is operated again, and the field winding 23 is excited in the positive direction, and the direction of the torque is reversed. When the command to do so, that is, the speed reference 10 is lowered, the armature current Ia becomes zero.

This command throttles the control rectifier 24.

Analog switch 17 is then open, 30 is open, and the phase of controlled rectifier 20 is biased to the negative side.

Furthermore, the gate of the control rectifier 24 is cut off under the condition that the field current is zero, the gate cutoff and the throttle of the control rectifier 25 are released, the control rectifier 25 starts operating, and the field current in the opposite direction gradually increases. go.

When the field current value reaches a constant field weakening value IfT, the analog switch 30 is closed, the phase restriction is released, and the analog switch 17 is closed again to utilize the armature-side control rectifier 20.

By the way, in such a configuration, the DC motor 1
2 is a rectification problem that limits the rise time of the current.

For this reason, during conventional control, a current ratio limiting circuit 16 is inserted between the current reference switching circuit 15 and the analog switch 17, which suppresses the rise of the current by limiting the current ratio. It is not possible to reliably suppress the steep rise of .

There are two possible reasons for this.

That is, the first reason is that the field switching time is long and the speed deviation input to the speed control circuit 14 is integrated during the switching period and has a value such that the speed control circuit 14 is saturated.

This integrated value is opposite in polarity to the polarity before entering the field switching command, but in the field switching method described above, the armature current is in one direction, and the current reference is switched by the current reference switching circuit 15. Therefore, when field switching diameter control is utilized, a voltage in the phase advance direction is always applied.

Therefore, if the current is left as it is, the rise of the current will be steep.

Next, the second reason is that due to field switching, the back electromotive force of the DC motor 12 changes from 10E to -E, and the phase of the first ignition pulse after switching is a value corresponding to the back electromotive force -E, that is. -E must be a value that is ahead of E by a voltage corresponding to the proportional amount of speed deviation.

Therefore, the final stage output just before the control is applied is the DC motor 12.
It is desirable that the voltage be a negative voltage corresponding to the back electromotive force -E, and if this value is not appropriate, there is a possibility that current will rush.

In order to solve the problem based on the first reason mentioned above, conventionally, if a voltage is applied to the current control circuit 18 during field switching so that the final stage output is throttled, the capacitor of the integrator of the speed control circuit 14 will cancel the charged forward voltage.

When the analog switch 30 is closed and the control is utilized, the discharge voltage of the capacitor 29 cancels out the voltage of opposite polarity from the speed control circuit 14, and the deviation is applied to the final stage output between the capacitor and the ignition phase. Things don't go smoothly.

However, in the circuit shown in Figure 1, essentially after the field switching, a value that is a voltage that is proportional to the speed deviation is applied to the final stage output from the back electromotive force of the DC motor, and the current after the field switching is not applied to the final stage output. is not determined.

In order to solve the problem based on the second reason mentioned above, an analog switch 32 is provided in parallel with the conventional current control circuit 18, and the back electromotive force of the DC motor 12 is input during field switching, and this voltage is applied to the current control circuit. A so-called voltage memory method is adopted in which the voltage is transmitted to the final stage output on a one-to-one basis through 18.

This idea was devised in view of these circumstances, and aims to short-circuit the input and output of the speed control circuit that performs integral operation during field switching to ensure that the residual deviation in the integral amount immediately after switching is zero. It is an object of the present invention to provide a control device for a DC motor that can stabilize the rise of current.

An embodiment of this invention will be described below with reference to the block diagram of FIG.

Here, only the parts that are different from FIG. 1 will be explained.

That is, this invention provides an analog switch 33 that short-circuits the speed control circuit 14' during field switching, and also uses a separate forward/reverse torque switching detection circuit 34 to transmit the forward/reverse torque switching signal, which was previously served by the output of the speed control circuit 14. This is done by the detected speed deviation signal.

The speed control circuit 14' includes a resistor 14'-2 and a capacitor 1 in parallel with the speed control amplifier 14'-1 as shown in FIG.
A series circuit with 4'-3 is connected, and the speed control amplifier 14
The two input terminals of '-1 each have a resistor of 14'-4,
A speed reference signal 10 and a speed feedback signal 13 are input via 14'-5.

When the speed reference signal 10 is positive, it becomes a forward rotation command, and when the speed feedback signal 13 is negative, it becomes a forward rotation command, and the current reference switching circuit 15 operates according to this command.

Note that 33 in the figure is the aforementioned analog switch.

The forward/reverse torque switching detection circuit 34 has a diode 34-2 connected in parallel to an inverter 34-1 as shown in FIG. 4, and a resistor 34-3.
-4, a speed reference signal and a speed feedback signal are input.

When the speed reference signal is negative, it becomes a forward rotation command, and when the speed feedback signal is positive, it becomes a forward rotation command, and this command is sent to the inverter 3.
4-1 becomes a switching logic signal, and when this signal is 1, a positive torque acts on the motor 12, and when the switching logic signal is "099", a reverse torque acts on the motor 12.

In this way, in this invention, the output of the speed control circuit 14 is only the current reference for minor current control, and the forward/reverse torque switching signal, which conventionally served as the output of the speed control circuit 14, is detected by the forward/reverse torque switching detection circuit 34. The reason for carrying the speed deviation signal is as follows.

That is, when switching from normal torque to reverse torque as a normal/reverse torque switching signal, the detection sensitivity must be made dull.

This is necessary to prevent field switching from occurring immediately when the speed overshoots or when the load on the motor 12 is light.

In order to satisfy this requirement, the military control volume 35 in the speed control circuit configured as shown in FIG. 5 is slightly shifted to the negative side so that when it reaches (+) 0, the polarity is switched.

Therefore, for example, when the speed deviation when switching from forward rotation acceleration to forward rotation deceleration is input to the speed control amplifier 36, the switching logic signal (point B in the figure) changes from 1 to 0, and the field is switched. At this time, since the analog switch 33 of the speed control amplifier 36 is closed, its output becomes (-)0, and since the force control of the speed control amplifier 36 is shifted to the negative side, the switching logic signal, that is, the signal at point B is Switches from O to 1.

This is because one speed control circuit cannot operate these two conflicting functions.

According to this invention described above, the output of the speed control circuit is used as the current reference for the next-stage current minor control, and the analog switch 33 is used to short-circuit the speed control circuit during field switching, that is, the amount of residual deviation after field switching. Since it is set to 0, it is possible to stably suppress the rise of the current after field switching.

Figure 6 is a time chart to explain this.
(a) shows the speed standard, (b) shows the motor speed, (C) shows the armature current, and (d) shows the field. As is clear from this, the rise of the armature current after field switching is It can be kept stable.

[Brief explanation of drawings]

Fig. 1 is a block diagram of a conventional DC motor control device, Fig. 2 is a block diagram showing an embodiment of the DC motor control device according to this invention, and Fig. 3 is a concrete diagram of the speed control circuit of the same embodiment. 4 is a circuit diagram of the forward/reverse torque switching detection circuit of the same embodiment, and FIG. 5 is a specific circuit diagram of a conventional speed control circuit.
FIG. 6 is a time chart for explaining the operation of this device. 10...Speed reference, 11...Speed generator, 12...DC motor, 13...Speed feedback signal, 14'... Speed control circuit, 15.
...Current reference switching circuit, 16...Current ratio limiting circuit, 18...Current control circuit, 19...
...Voltage limiting circuit, 20, 24, 25...
Control rectifier, 22...Logic circuit, 23...
... Field winding, 21, 27 ... Current detector, 17, 30. 32, 33 ... Analog switch, 34 ... Forward/reverse torque switching detection circuit.

Claims (1)

[Scope of utility model registration request] A speed control circuit that uses a speed deviation signal between a speed reference and a speed feedback signal as a current reference for a current minor control circuit in the next stage in a stationary Leonard device in which the direction of torque is controlled by switching the direction of a field current. a first opening/closing element that short-circuits this speed control circuit during field switching to zero the residual deviation amount after field switching; and a forward/reverse torque switching element that detects a forward/reverse torque switching command based on the speed deviation signal. The phase of the detection circuit and the control rectifier on the field side that is in operation under the condition that the armature current becomes zero when switching the torque direction is narrowed down.
and a field control circuit that cuts off the gate of the control rectifier under the condition that the field current becomes zero and gives a command to make use of another control rectifier on the field side that is in an inoperable state, and a second The armature uses the control rectifier on the armature side when the field current reaches a certain field weakening value by applying the back electromotive force of the DC motor as the final stage output in a 1:1 ratio through the operation of the switching element. A DC motor control device consisting of a control circuit.