JPS5820229B2 - Electric motor control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a motor control device using a transistor servo amplifier suitable for speed control of a relatively large capacity DC motor.

A circuit diagram of this type of control device is shown in FIG.

In Figure 1, A is the terminal to which the pulse width modulation input is applied, and this terminal is positive (hereinafter, positive potential is referred to as '1'', O potential is referred to as W).
! 091), the transistor Q5 is turned on, so the transistor Q1 is turned off, and at this time, the transistor Q2 is turned on, so that the terminal X of the motor MO becomes OV.

On the other hand, terminal B is the inverted output of terminal A input through impark I, so at this time terminal B becomes 0'', transistor Q6 is off, transistor Q3 is on, and transistor Q4 is off, so the motor MO Terminal Y is 100
■It becomes.

Next, when the terminal A becomes 0'', the X terminal becomes 100■, and the X terminal becomes OV.

Therefore, in order to stop the motor MO by motor control, as shown in Fig. 2a, for example, the widths of 0" and °1" of the pulse width modulation input A with a frequency of IKHz should be made the same, and the widths of the terminals X, Y In the first half of IKHz, the potential of terminal X is 100■,
Terminal is 0■, terminal X=OV, terminal Y=100V in the second half
This occurs continuously, and an IKHz alternating current rectangular wave is applied to the motor.

In other words, since its DC voltage component is 0, the motor is at IKH.
It does not respond to the alternating current at z, so the motor is stopped.

Here, as shown in Figure 2, the 1" period of terminal A is 0".
(Then, the period in which terminal bias, the motor MO rotates.

Assuming that this rotation is normal rotation, in order to reverse rotation, 1" of terminal A must be
The period of 0'' may be made shorter than the period of 0''.

That is, as a DC component, the terminal X is biased toward the 100 cm side, and the terminal Y is biased toward the OV side, so that the motor rotates in reverse.

The control circuit shown in FIG. 1 has the following drawbacks.

One of them is the final stage transistor Q1 to drive a large capacity DC motor. Q2. Q3. Since the collector resistor of Q4 needs to turn on and off a large current, the base current of these also needs to be large, and the base current control transistor Q that controls this base current
5. Since the collector resistance of Q6 must vary from 0V to 100V, transistors Q5 and Qe require very large power transistors and are uneconomical.

Moreover, the voltage loss of the collector resistance also becomes large.

Second, the moment the terminal A changes from 0'' to 1'', the transistor Q1 changes from on to off, and the transistor Q1 changes from on to off.
Transistor Q1.2 should change from off to on, but due to the switching delay of the transistor, transistor Q1 cannot turn off immediately and remains on for the charge accumulation time. In Q2, the power supply of 100cm is shortened and damaged.

The same thing can happen with transistors Q3 and Q4 when terminal A changes from 1'' to 0''.

Furthermore, the final stage transistor Q1. Q2. When the motor current flowing through Q3゜Q4 exceeds the allowable value of these transistors, these transistors are no longer completely on.
It cannot be turned off, increasing heat loss and destroying the transistor.

Furthermore, the circuit shown in FIG. 1 requires four high-power transistors as the final stage transistor, which is uneconomical.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a motor control device using a transistor servo amplifier that is suitable for controlling a relatively large-capacity motor and can prevent transistor breakdown accidents.

In order to achieve this objective, a motor control device according to an embodiment of the present invention includes a controlled motor, a first DC power source, and a first DC power source.
a first switching transistor constituting a closed circuit of the controlled motor, the first DC power supply and the second switching transistor;
A transistor servo amplifier constitutes a closed circuit, and includes a second switching transistor connected in series to the first transistor, and the first output changes from 1'' to 0'', and after a short period of time, the other output changes. changes from 0" to 1",
A pulse width modulation circuit that generates two rectangular wave outputs with a phase difference of 180 degrees, and the output transformer for each output transformer. and has two phase difference outputs of the pulse width modulation circuit as inputs, and when these inputs are 1'', an output of a frequency sufficiently higher than the input frequency is generated in the secondary winding of each of the output transformers. a base current drive circuit, the first and second base currents and the output of the drive circuit are rectified by first and second rectifiers, respectively, and the first and second base currents are rectified by the first and second rectifiers.
The base of each transistor is driven by each rectified output.

According to such a device, firstly, each output can drive the base of each transistor with a large current at a low voltage, so as in the device shown in FIG. 1, a large power transistor (Q5. There is no need to use Q6) in the base current drive circuit.

Second, by selecting the minute time to correspond to the charge accumulation time when each final stage transistor switches off, it is possible to prevent the series-connected transistors from being on at the same time, thereby preventing a power supply short-circuit. This can prevent damage to transistors or devices due to

Further, circuit means may be provided to detect overcurrent from a common current path of the first and second closed circuits and shut off the output of the base current drive circuit for a predetermined period of time, thereby preventing damage to each transistor due to overcurrent. I can do it.

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

As shown in FIG. 3, the control device of the present invention includes a pulse width modulation circuit 1 and base current drive circuits 2a and 2b.

It is composed of current control limiting circuits 3, 4 and a final stage 1 helange amplifier 5.

Ql and Q2 of the servo amplifier 5 are final stage power NPN transistors, and Ql and Q2 are respectively connected in series as shown in the figure.

The collector of Q2 is connected to the positive terminal of DC power supply E1, for example, 100cm, and the emitter of Q2 is connected to the negative terminal of DC power supply E2, for example, 100cm. Connect to ground.

The emitter of the transistor Q1 and the collector of Q2 are connected, and a reactor L and a motor M are connected between this point and the ground.
Insert a series circuit of O and resistor R3.

Also, transistor Q1. A rectifier D1.Q2 with the polarity shown is connected between the collector and emitter of D1.Q2. D2 is provided.

Each of these rectifiers prevents reverse voltage from being applied to transistors Qt and Q2.

Each transistor Q1. Resistors R1R2 are inserted between the base and emitter of Q2, and the base side is the positive terminal,
A bridge type full wave rectifier S1. A pair of DC output terminals of S2 are connected.

Next, the secondary winding K of the transformer T1 of the base current drive circuit 2a (details will be described later) is connected to the AC input terminal of the rectifier S1, and the secondary winding M of the transformer T2 of the base current drive circuit 2b is connected to the AC input terminal of the rectifier S1. Connect to the AC input terminal of rectifier S2.

Further, the other terminal of the resistor R3 whose terminal is connected to the ground potential is connected to each input terminal C, D of the current limiting circuit 3.4.

The output terminal v1 of the current limiting circuit 3 is connected to the input terminal 2 of the base current 1 driving circuit 2a, and the output terminal W1 of the current limiting circuit 4 is connected to the input terminal W2 of the base current driving circuit 2b.

Each input terminal X1X2 of base current drive circuit 2a, 2b
For example, rectangular wave power (X) of 10 KHz with the same interval between 1'' and 0'' is supplied to.

Next, the output terminal A1 of the pulse width modulation circuit 1 is connected to the input terminal A2 of the base current drive circuit 2a, and the output terminal B1 of the pulse width modulation circuit 1 is connected to the input terminal B of the base current 1 drive circuit 2b.
Connect to 2.

An input terminal R of the pulse width modulation circuit 1 is supplied with a triangular wave VR of, for example, IKHz, which is symmetrical in positive and negative directions, and a control DC voltage VB is applied to an input terminal E.

The pulse width modulation circuit 1 is constructed as shown in FIG.

In Figure 4, 11 is a Schmitt trigger circuit, which adds the triangular wave to the R terminal and the DC voltage to the E terminal in analog form, and when it is positive, the output Y is 1'', and when it is negative, it is 0''. It is something.

Numerals 12 and 13 are NAND circuits whose output is 0'' only when all inputs are 1'', and whose output is 1'' when any of the inputs is 0''.

Also, 14, 15, and 16 are inverter circuits, and the input is 1"
When , the output is fl Oll, and when the input is 0'', the output is 11 plus.

What is the output at point X of the circuit consisting of resistor R101, rectifier D1o, and capacitor ctot? ! When the voltage changes from 151 to 0, the rectifier DIOI instantly sets the G point potential to 0'', and the G point remains 0'' while the X point is 0''.

When the penalty point potential changes from 0'' to 1'', the capacitor Cl0I is charged through the resistor R1ot, and the ``G'' point potential becomes 1'' after a certain period of time, and then? While the i'AI'' point is II 1 ff+, the IT Gff1 point is 1''.

Similarly, resistor R7. 2. The circuit consisting of current generator D1o2 and capacitor ClO2 has a point from 0'' to 111
The °H" point changes from "011" to "1" with a time delay reaching It.

The operation of this pulse width modulation circuit 1 is as follows.

When the DC voltage now applied to terminal E is Ov, IKHz
Depending on the sign of the triangular wave, the Schmitt trigger circuit 11
The output ``Y'' changes as shown by Y in FIG. 5a.

At time A in Fig. 5a, the output Y changes from 0'' to 1'', the output of the inverter 14 becomes 0'', the output B1 of the NAND circuit 13 changes to 91111, and the time has returned for a certain period of time. Since the H'' point becomes n 1 H, the point 70 becomes ex Ost from this point on.

At this time, point G also immediately becomes 0''. B1 remains at 1'''.

After that, at time C, the output of the Schmitt trigger circuit 11 is 1.
The output of the NAND circuit 12 changes from `` to 0'' and the output of the NAND circuit 12 becomes 1.
'', the output of the NAND circuit 12 changes to 1'', and the output of the inverter 14 changes to 1''.

After this, at time 2, which is a certain period of time, the T G l" point becomes 1", so the white point becomes 0" from this time.

Then, at time E, the output t+y'' becomes 1'' again, and thereafter the same operation is repeated at a cycle of IKHz.

The output +1 A1 ff+ of the inpark 15 and the output "Bl" of the inverter 16 become the inverter waveforms of A1 and B1, respectively, as AI and Bl in FIG. 5a.

That is, when the control DC pressure is 0■, the outputs of the output terminals Al and Bl are at 1'' for the same amount of time, and their phases are 180° different, so that the outputs A1 and B1 are never 1'° at the same time. After a certain period of time after the output ++ A I +1 goes from 1'' to 0'', the output e+ B 111 goes down from '0'' to '11', and the output IT B 1 +1 goes from 1'' to 0''.
After a certain period of time, the output u A 1 ++ becomes ゛0
Please note here that it becomes 1″ from PA.

Next, when the control DC voltage applied to terminal E is positive,
As shown in Figure 5, the input of the Schmitt l-IJ Gar circuit 11 is biased to the positive side, so the output II
” becomes longer, so the output “A1” becomes “1”.
The period during which the output "B1" becomes "1" is longer than the period during which the output "B1" becomes "1".

n Al '91. The period in which both "B1" become "0" is the same as in the case of figure a.

Moreover, when the control voltage is negative, contrary to the above, the period when the output "A1" is "1" becomes short, and the period when the output "B1" is "1" becomes long.

By changing the control DC voltage in this manner, a pulse width modulated output can be obtained.

These modulated outputs "A1" and B1'' are given to the base current drive circuit 2a t 2b.

Next, the base current 1 drive circuits 2a and 2b will be explained with reference to FIG.

Note that since these two circuit configurations and operations are completely similar, only the circuit 2a will be described below for convenience.

In this circuit 2a, either input terminal A2 or V2 is 0.
'', or when both are 0'', no output is generated at the secondary winding K, which is the output terminal.

The output terminal is insulated from ground potential by a transformer T1.

22 and 23 in Figure 6 are NAND circuits, and all inputs are °1
The output is 0 only when the input is 0, and the output is 1 when any of the inputs is 0, and 21 is an inverter circuit whose output is 0 when the input is 1. ′
, when the input is 0'', the output is 1''.

The operation of this base current drive circuit 2a is as follows.

Input terminal A2. When both V2 are “1”, 10K
Hz rectangular wave input ■When X is "1", the output of the NAND circuit 22 is °°0", transistor Q201 is off, Q20
5 is on.

On the other hand, the output of the inverter 21 is 0'', so the output of the NAND circuit 22 is 1'', and the transistor Q202 is on.
Since Q204 is off, the primary winding CT of transformer T1
The voltage of the power source E3 is applied between -P.

Next, when the rectangular wave power (X) becomes zero, the transistor Q203 is turned off, the transistor Q204 is turned on, and the voltage of the power source E3 is applied between the primary windings CT and Q of the transformer T1.

In this way, 1,0KH given to input terminal X1
Every time the square wave of z changes alternately between 1'' and 0'', the voltage of the power source E3 is alternately applied between the primary windings CT and P and between CT and Q of the transformer T1, so that the secondary 10K to winding terminal K
A square wave output of Hz is obtained.

Also, terminal A2. ■If either of 2 is not 1'', the output of NAND circuits 22 and 23 becomes 1'', and the transistor Q
201 t Q202 is on, transistor Q203
t Q204 is turned off and no output voltage is produced at the secondary winding terminal K.

10KHz is applied to the output terminal K of this base current drive circuit 2a.
When a rectangular wave of
A DC voltage is generated between the base and emitter of the transistor Q1, thereby turning on the transistor Q1.

Further, when a 10 KHz waveform is not generated at the output terminal K, the transistor Q is turned off.

The resistor R1 is used to completely turn off the transistor Q1 at this time, that is, to set the pace emitter voltage to O.

On the other hand, the base current is 10KH at the output terminal M of the drive circuit 2b.
When a square wave output of z occurs, the M terminal output is rectified by bridge rectifier S2 to apply a voltage between the base and emitter of transistor Q1 to turn it on.

When a 10 KHz rectangular wave is not generated at the output terminal M, the transistor Q2 is turned off.

The purpose of the resistor R2 is to completely turn off the transistor Q2 at this time, that is, to set the voltage between the base and emitter to O■.

Next, based on the above, the output V1. of the current limiting circuit 3.4. The overall operation of the circuit shown in FIG. 3 will be explained assuming that W1 is "1".

Note that the current limiting circuits 3 and 4 will be described later.

When the output A1 of the pulse width modulation circuit 1 is "1", a rectangular wave output is generated in the secondary winding K of the base current drive circuit 2a, so the transistor Q1 is on, and when the output A1 is 0", the transistor Q1 is turned on. is turned off.

Furthermore, when the output B1 of the pulse width modulation circuit 1 is ``1'', a rectangular wave output is generated in the secondary winding M of the base current drive circuit 2b, so the transistor Q2 is turned on and the output B1 is 0.
'', the transistor Q2 is turned off.

Let us now explain the case of FIG. 5a where the control DC voltage VB of the pulse width modulation circuit 1 is OV.
1 is '0'' and Bl is also 0'', so transistor Q, ,
Q2 is off, A1 is '1' and Bl is 0 from the beginning of the period to the beginning of the period.
'', transistor Q1 turns on and +10
Current flows in the direction of the arrow in the motor MO through the 0V terminal → transistor Q1 → reactor L → motor MO → resistor R3 → ground point.

In period HAR2, both transistors Qt and Q2 are off, and in periods 2 to E, A1 is '0'' and B1 is °°1'', so transistor Q2 is turned on, and the ground point → resistor R3 → motor MO → Reactor L→Transistor Q2→
A current flows through the -100■ terminal to the motor MO in the opposite direction to the arrow.

In periods 1~C and 2~E, the direction of the current flowing through the motor MO is opposite, but since the periods are the same, the DC component applied to the motor is equal, and the motor does not respond to the high frequency of IKHz, so the motor stops. are doing.

A reactor L connected in series with the motor is inserted to reduce the alternating current component of the motor current.

Next, to explain the case shown in Figure 5 when the control DC voltage VE of the pulse width modulation circuit 1 is positive, the period in which the output A1 is 1'' is longer than the period in which the output B1 is 1''. Since the length is long, the DC component of the current flowing through the motor MO flows in the direction of the arrow by the difference between these periods (proportional to the control DC voltage), so the motor MO rotates forward and its rotational speed is proportional to the control DC voltage.

Conversely, when the control DC voltage VE of the pulse width modulation circuit 1 is negative, the 1'' period of the output A1 is shorter than the 1'' period of the output B1, so the electric current in the direction opposite to the arrow is long in the motor MO. After a period of time, the motor MO reverses, the speed of which is proportional to the control voltage.

In this manner, by controlling the control DC voltage E applied to the pulse width modulation circuit 1, forward/reverse rotation, variable speed, and stop control of the motor are performed.

Next, the current limiting circuits 3 and 4 will be explained.

The circuits 3 and 4 are transistors Q of a transistor servo amplifier 5.

If a current exceeding the rated current flows through Q2, it will be damaged, so the current value is limited so that the transistor current does not exceed the rated value.

That is, during the period when the output AI of the pulse width modulation circuit 1 is 1'', the transistor Q1 is turned on, and this transistor Q1
All current flowing through resistor R3 flows through resistor R3.

When this current exceeds the rated current of the transistor, the input voltage of the current limiting circuit 3 exceeds a constant positive voltage value.

Then, the output voltage ■1 of this circuit 3 becomes 0''',
The output of the base current 5 drive circuit 2a becomes 0'', turning off the transistor Q1, and the current flowing through the transistor Q1 is set to 0 to protect it from exceeding the rated current of the transistor.

On the other hand, the transistor Q2 is turned on while the output B1 of the pulse width modulation circuit 1 is "1'', and the current flowing through the transistor Q2 flows through the resistor R3.

When this current exceeds the rated current of the transistor, the input voltage of the current limiting circuit 4 exceeds a constant voltage value of negative potential.

Then, the output voltage W1 of this circuit 4 becomes 0, the output of the base current 1 drive circuit 2b becomes 0, and the transistor Q2 is turned off to protect it from exceeding the rated current of the transistor Q2. .

An example of the current control circuit 3 operating in this manner is shown in FIG. 7, and an example of the limiting circuit 4 is shown in FIG. 8.

When the input voltage at the input terminal C exceeds a certain value in FIG. becomes 0''.

Therefore, transistor Q1 is turned off.

As a result, the potential at point C decreases, but even if the potential at point C decreases, the potential of capacitor C401 remains the same as that of resistor R402J.
Since the discharge gradually occurs through R403, the output (1) of the Schmitt trigger circuit 31 remains at "0" for a certain period of time.

Then, after a certain period of time, the potential of the capacitor C401 decreases to the predetermined value, so that the output ■1 of the Schmitt trigger circuit 31 becomes N1? again. 1, which allows transistor Q1 to turn on.

This delay in operation is due to the current limiting circuit cutting off the current for a certain period of time to sufficiently lower the current value.

Next, the output B1 of the pulse width modulation circuit 1 is e+ 1 j
When the transistor Q2 is in the ON state and the Q2 current exceeds the rated current value during the period l, the input voltage at the input terminal of the current limiting circuit 4 in FIG. 8 exceeds a certain negative value, the rectifier D50
The capacitor C501 is suddenly charged through the resistor R5o1, and the output W1 of the Schmitt trigger 41 becomes 0''.

Thus, transistor Q2 is turned off.

As a result, the potential at point D changes toward O, but capacitor C
Since the potential of 501 is gradually discharged through the resistor R5o2, the output W1 of the Schmitt trigger circuit 41 remains constant for a certain period of time.
remains at 0゛'.

After a certain period of time, when the potential of the capacitor C501 drops to the expected value, the Schmitt trigger circuit 41 outputs W again.
1 becomes 1'', which returns transistor Q2 to normal operation where it can turn on.

Next, the above invention will be explained in detail.

When the motor MO has a relatively large capacity, the final stage transistor Q1. In order to turn on Q2, the base current of these transistors needs to be very large (assumed to be 3A for the sake of explanation), but on the other hand, the driving voltage between the base and emitter of these transistors must be about 2. is sufficient, so the outputs of the base current drive circuits 2a, 2b and the transformers T1. It is sufficient for the secondary winding voltage of T2 to be about 2.

Therefore, in the present invention, the base current drive circuit 2 a t 2
b is the transformer T1.b along the two sides shown in FIG. The primary voltage is stepped down by T2 and generated on the secondary side.

For example, if the voltage of the power source E3 in FIG. 6 is 24V, the turns ratio of the transformer T1 may be 24V:2V.

Therefore, the capacitance of the transistors Q203 t Q204 in FIG. 6 is a collector withstand voltage of 24VX2, and the collector current capacity is 3A/24/2=0.25A.

On the other hand, in the conventional circuit shown in FIG. 1, the collector breakdown voltage of the base driving transistors Q5 and Qa is 100μ or more, and the collector current is required to be 3A.Comparing the power capacity, the present invention has a power capacity of 24-VX2XO125A/100VX compared to the conventional circuit.
3A=1/2.5 is sufficient.

The present invention is not limited to the circuit shown in FIG. 3, but also the circuit shown in FIGS.
As shown in Figure 0, a combination of NPN, PNPNPN transistor, Q2, or replacing the NPN type transistor in Figures 3, 9, and 10 with a PNP type transistor, and replacing the PNP type transistor with an NPN type transistor. Power supply E1. It can be applied to those with different polarity of E2.

Furthermore, as shown in FIGS. 11 and 12, the current capacity of the servo amplifier can be increased by using a circuit in which transistors Q1 and Q3 are connected in parallel, and transistors Q2 and Q4 are connected in parallel.

FIG. 11 shows the bridge type rectifier S1. This is a system in which two transistors are driven in parallel by S2, and FIG. 12 shows the transformers T1. T2 no 2
In this method, L, M, and N are prepared as two windings on the next side, and the base current of each transistor is driven by these.

In addition, as shown in FIGS. 11 and 12, a large capacity servo amplifier can be made by connecting not only two but three or more transistors in parallel.

Also, each transistor in FIGS. 11 and 12 is similar to that in FIGS.
As shown in Fig. 0, it can also be obtained by a combination of PNP type and NPN type transistors.

According to the present invention described above, it is possible to provide a motor control device using a transistor servo amplifier that is suitable for driving a relatively large-capacity motor and can eliminate accidents such as damage to transistors.

[Brief explanation of the drawing]

FIG. 1 is a wiring diagram showing an example of a conventional motor control circuit, FIG. 2 a and b are pulse waveform diagrams for explaining the operation of the motor control circuit, and FIG. 3 is a diagram showing an example of the present invention. A circuit diagram of a motor control device, FIG. 4 is a wiring diagram showing an example of a pulse width modulation circuit used in the device of the present invention, FIGS. 5 a and b are explanatory diagrams of the operation of the circuit in FIG. A wiring diagram showing an example of the base current drive circuit used in the device of the invention, FIGS. 7 and 8 are wiring diagrams showing an example of the current limiting circuit used in the device of the invention, and FIGS. FIG. 3 is a circuit diagram showing a modification of the transistor servo amplifier used in the device of FIG. MO...Controlled motor, Q1 to Q4...
・Motor control transistor, Q5. Q6...
Base driving transistor, ■... Inverter, 1... Pulse width modulation circuit, 2 a, 2 b
...Base current drive circuit, 3.4...
Current limiting circuit, 5...transistor servo amplifier, 11...Schmitt trigger circuit, 12.
13...Nand circuit, 14-16...
Inverter, 21... Impark, 22, 23
...Nand circuit, 31,41...Schmitt trigger circuit.

Claims (1)

[Scope of Claims] 1. A first closed loop that connects a first DC power source to a controlled motor via a first switching transistor to flow a current in a first direction to the controlled motor; The controlled motor is connected to the controlled motor through a second switching transistor to alternately form a second closed loop in which a current in a second direction flows through the controlled motor. (a) a pulse width modulation circuit that generates first and second pulse outputs that have a phase difference of 180° and are pulse width modulated; (b) the first and second pulse outputs that are pulse width modulated; (c) first and second base current drive circuits each receiving the second pulse output and forming a high frequency output during its pulse width interval, and transmitting the high frequency output through the respective output transformers; The DC output obtained by rectifying the high frequency output sent from the first and second base current drive circuits is applied to the bases of the first and second switching transistors as an ON control signal. A motor control device comprising first and second rectifiers that alternately turn on two switching transistors.