JP3069507B2 - DC motor controller - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a DC motor controller for controlling the speed and torque of a DC motor.

[0002]

2. Description of the Related Art In recent years, DC motor controllers of a chopper type or a switching power supply type have been generally used because of their advantages of being small and lightweight. For example, a magnetic amplifier using an amorphous metal as a core material is used on the secondary side of the transformer, and a switching element connected to the primary side of the transformer is switched at a constant cycle (on-duty is made constant), and the magnetic amplifier is reset. Switching regulators in which the output can be varied by variably controlling the magnitude of the current have been conventionally proposed (Japanese Patent Publication No. 6-67187, Japanese Utility Model Publication No. 6-67187).
JP-A-2472 and JP-A-5-328715), a DC motor control device as described above is realized by connecting a DC motor as a load to such a switching regulator. The DC motor control device using such a switching regulator has advantages such as being capable of independent control of multiple outputs and being easy to insulate the control unit from the high voltage unit on the primary side of the transformer. doing.

FIG. 3 is a circuit diagram showing a switching regulator described in Japanese Patent Publication No. 6-67187.
In this switching regulator, a transformer T is connected to both ends of an unstable DC power supply E via a main switching element QM.
Connect the primary winding n _1, by switching operation of the main switching element QM in self-excited oscillation circuit 10 at a predetermined frequency, to obtain an AC output on the secondary side of the transformer T. The secondary winding n ₂ of the transformer T has a magnetic amplifier ML,
A rectifier diode D ₂ and a choke coil LF are connected in series with a load (DC motor) (not shown).
A smoothing capacitor CF in parallel with the load between the secondary windings n ₂ ,
Commutating diode D ₃ is is connected. Incidentally, the commutation diode D ₃ is for regenerating the stored energy of the choke coil LF to the smoothing capacitor CF.

[0004] Here, the magnetic amplifier ML is a main switching device.
During the ON period of the element QM, the secondary winding n of the transformer T_TwoInduced
Output voltage V for a certain period of time.₀Is constant
It is controlled so that The above control is output
Voltage V₀The detection signal Vs of the error amplifier and the reference voltage generation
Input to the control circuit 11 composed of
Reset current from the sensor CF via the switching element QR.
This is done by supplying a stream. Es of the control circuit 11
An auxiliary power supply that supplies electric power,
And output voltage V₀May be supplied from Also,
Capacitor C_Two, Capacitor C_ThreeAnd resistance R_Two, Resistance R_ThreeIs
A rectifier diode D_TwoAnd roll
Current diode D _ThreeProvided to suppress surge voltage of
is there. Here, the control circuit 11 compares the ratio with the detection signal Vs.
The reference voltage to be compared can be changed by an external command.
With the magnetic amplifier ML via the switching element QR
By changing the magnitude of the reset current supplied,
Output voltage V₀Can be varied, and the output voltage V
₀To the DC motor to operate the motor and
The rotation speed of the DC motor is detected using a
The output signal of the control circuit 11 is appropriately processed to
If the command value to change the reference voltage is
Regulators can be applied to DC motor controllers.
it can.

[0005]

In the above-described conventional configuration, the reset current supplied to the magnetic amplifier ML is controlled by the control circuit 11 to turn on and off the switching element QR that operates using the voltage across the smoothing capacitor CF as a power supply. It is variable. That is, the base current is supplied from the smoothing capacitor CF to the switching element QR, and the control circuit 11 adjusts the base current to vary the reset current.

However, when controlling a DC motor as a load, the output voltage V ₀ may be varied to be reduced to almost zero, and when the output voltage V ₀ becomes extremely low, switching is performed. Since a sufficient base current is not supplied to the element QR, the on / off control of the switching element QR by the control circuit 11 becomes unstable. In other words, there has been a problem that the DC output supplied to the DC motor cannot be reduced to substantially zero in order to control the DC motor stably.

SUMMARY OF THE INVENTION An object of the present invention is to provide a DC motor control device capable of varying a DC output supplied to a DC motor to substantially zero, thereby enabling stable control of the DC motor. It is something to offer.

[0008]

According to a first aspect of the present invention, there is provided a power supply unit for supplying an AC output through a transformer, and an inductance value varies according to a magnitude of a reset current. A magnetic amplifier having characteristics and connected to the secondary side of the transformer, a reset current supply unit for supplying a reset current to the magnetic amplifier, and an AC output of a power supply unit supplied via the magnetic amplifier is converted into a DC output. A converter section, a detection section for detecting an operation state such as a rotation speed and a torque of a DC motor operated by a DC output from the converter section, and a desired operation state based on the operation state detected by the detection section. A control unit that outputs a control signal for controlling the control signal, and a reset current that uses the control signal from the control unit as operating power and varies the magnitude of the reset current according to the control signal. Characterized in that a variable portion.

According to a second aspect of the present invention, in the first aspect, a light emitting diode which emits light in response to a control signal from the control unit, and a reset current supplied to the magnetic amplifier from a reset current supply unit optically coupled to the light emitting diode. The reset current variable section is constituted by a photocoupler including a phototransistor inserted into the path. According to a third aspect of the present invention, in the first aspect of the present invention, an exciting coil excited by a control signal from the control unit, and supply of a reset current from the reset current supply unit to the magnetic amplifier magnetically coupled to the exciting coil. A reset current variable section is constituted by a magnetoresistive element inserted in the path.

According to a fourth aspect of the present invention, in the first to third aspects of the present invention, a correction means for correcting the control signal such that a change in the DC output of the converter section with respect to the control signal has linearity is provided in the control section. It is characterized by.

[0011]

According to the configuration of the first aspect of the present invention, the power supply unit for supplying an AC output via the transformer is connected to the secondary side of the transformer with the characteristic that the inductance value changes according to the magnitude of the reset current. A magnetic amplifier, a reset current supply unit that supplies a reset current to the magnetic amplifier, a converter unit that converts an AC output of a power supply unit supplied through the magnetic amplifier into a DC output, and a DC output from the converter unit. A detecting unit for detecting an operating condition such as a rotation speed or a torque of an operating DC motor; and a control unit for outputting a control signal for controlling the DC motor to a desired operating condition based on the operating condition detected by the detecting unit. And a reset current variable unit that changes the magnitude of the reset current according to the control signal with the control signal from the control unit as operating power,
Even if the DC output of the converter section is substantially zero, the reset current variable section can be operated, and the DC section of the converter section supplied to the DC motor by the control section is changed to an arbitrary value from substantially zero to the maximum rating. be able to.

According to a second aspect of the present invention, a light emitting diode which emits light in response to a control signal from the control unit, and is optically coupled to the light emitting diode and inserted into a reset current supply path from the reset current supply unit to the magnetic amplifier. Since the reset current variable section is constituted by the photocoupler including the phototransistor, the control section is insulated from the magnetic amplifier, the reset current supply section, and the converter section, and the power supply of the control section can be supplied from the power supply section.

According to a third aspect of the present invention, there is provided an excitation coil which is excited by a control signal from the control unit, and a reset current supply path which is magnetically coupled to the excitation coil and which supplies a reset current from the reset current supply unit to the magnetic amplifier. Since the reset current variable section is constituted by the inserted magnetoresistive element, the control section is insulated from the magnetic amplifier, the reset current supply section, and the converter section, and the power of the control section can be supplied from the power supply section.

According to the configuration of the fourth aspect of the present invention, the control unit is provided with correction means for correcting the control signal so that the change in the DC output of the converter unit with respect to the control signal has linearity. Unnecessary fluctuations and vibrations of the rotation speed and torque of the DC motor due to the non-linearity of the change in the DC output can be suppressed.

[0015]

An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a circuit configuration diagram showing the present embodiment. A DC motor control device according to the present embodiment includes a power supply unit 1 that uses a DC power supply E as a power supply and supplies an AC output to a secondary side of a transformer T.
Transformer T having two primary windings n ₁ and n ₁ ′ on the secondary side
When a magnetic amplifier ML in series with the secondary winding n ₂ of the transformer T, an AC output generated in the secondary side of the connected transformer T to the secondary winding n ₂ of the transformer T through the magnetic amplifier ML Unit 2 that converts the DC power into a DC output and supplies the load to DC motor M, a reset current supply unit 3 that supplies a reset current to magnetic amplifier ML, and DC motor M
Detecting section 4 for detecting an operating condition such as a rotation speed and a torque of the motor
A control unit 5 for outputting a control signal for controlling the DC motor M to a desired operation state based on the operation state detected by the detection unit 4, and a control signal from the control unit 5 as an operation power. And a reset current varying unit 6 that varies the magnitude of the reset current according to the reset current. Since the basic configuration of the present embodiment is substantially the same as the basic configuration of the conventional control device shown in FIG. 3, the same parts are denoted by the same reference numerals.

[0016] and the power supply unit 1 is the main switching element QM, and a self-oscillation circuits 1a, and connected in series with the opposite ends of the primary winding n ₁ of the transformer T with the DC power source E to the main switching elements QM, self- on the main switching element QM at a predetermined frequency by the oscillation circuits 1a, and off operation, but to interrupt the direct current flowing in the primary winding n _1. Further, one end of the second primary winding n ₁ ′ of the transformer T is connected to a diode D
₁ is connected to the negative side of the DC power supply E, and a capacitor C ₁ and a resistor R are connected in parallel with the main switching element QM.
_The main switching element Q
The current flowing through the primary winding n ₁ when M is turned off is transferred to the second primary winding n _{1 through} the path of the capacitor C ₁ → resistance R ₁ → diode D ₁ → second primary winding n ₁ ′. ₁ 'to flow.

The magnitude of the reset current is determined by the magnetic amplifier ML.
It has the characteristic that the inductance value changes according to
Secondary winding n of transformer T_TwoAre connected in series to one end.
Converter unit 2 is connected in series to magnetic amplifier ML.
Rectifier diode D_TwoAnd choke coil LF and smoothing coil
Capacitor CF and rectifier diode D_TwoAnd choke coil
LF connected in parallel with the smoothing capacitor CF
Commutation diode D_ThreeAnd this commutation diode D_ThreeProtect
C that constitutes a snubber circuit _TwoAnd resistance R_Two
And a rectifier diode D_TwoRecovers
A snubber circuit to absorb surge voltage
Capacitor C to be formed_ThreeAnd resistance R _ThreeAnd a series circuit of
ing.

The reset current supply unit 3 is to supply to the magnetic amplifier ML the current induced in the secondary winding n ₂ of the transformer T as a reset current, magnetic amplifier connection point of the choke coil LF and a smoothing capacitor CF are those composed by connecting via the connection line 7 ML and the connection point of the rectifier diode D _2. A phototransistor PT is inserted into the connection line 7, and the phototransistor PT is optically coupled to a light-emitting diode LD whose light emission amount is adjusted by the control unit 5, so that a photocoupler PC is formed.
Are formed, and the photocoupler PC serves as the reset current variable unit 6. That is, the amount of light emission is adjusted by varying the drive current flowing through the light emitting diode LD by the control unit 5, thereby changing the collector-emitter resistance of the phototransistor PT inserted into the connection line 7 to change the magnitude of the reset current. Can be changed.

The detecting section 4 detects the rotational speed of the DC motor M, and is constituted by, for example, a rotary encoder. The control unit 6 includes a speed signal processing unit 5a that calculates the rotation speed (the number of rotations) of the DC motor M based on the pulse-like speed signal output from the detection unit 4, and a speed setting for setting a desired rotation speed. Unit 5b, a signal indicating the current rotation speed of the DC motor M output from the speed signal processing unit 5a and a signal indicating the target rotation speed set in the speed setting unit 5b are compared, and the difference is determined. A comparing unit 5c for outputting a signal, a correcting unit 5d for correcting an output signal of the comparing unit 5c, a D / A converting unit 5e for converting the signal corrected by the correcting unit 5d into an analog voltage, and a D / A conversion A voltage-current converter 5f that converts an analog voltage output from the unit 5e into a current and supplies the current to the light emitting diode LD.

Next, the operation of the power supply unit 1, converter unit 2, and magnetic amplifier ML will be briefly described. In addition,
The basic operation is common to the operation of the conventional example shown in FIG. First, turn on the main switching element QM at a predetermined frequency by the self-oscillation circuit 1a in the power supply unit 1, is off operation, is interrupted the current flowing through the primary winding n ₁ of the transformer T, 2 primary side of the transformer T To induce AC output. Then, adjusted by varying the inductance value of the magnetic amplifier ML that the duty ratio of the AC output which is input from the secondary side of the transformer T to the converter unit 2, which is connected to the secondary winding n ₂ at the reset current . Further, the converter unit 2
Rectifies and smoothes the AC output supplied via the magnetic amplifier ML and stabilizes the AC output before supplying it to the DC motor M. As described above, the DC output V ₀ supplied from the converter unit 2 to the DC motor M can be varied by changing the magnitude of the reset current supplied to the magnetic amplifier ML.

Then, the overall operation of the DC motor control device of the present embodiment will be described with reference to the flowchart of FIG. In the present embodiment, the control unit 5 is configured by a microcomputer, and the operation described below
The processing is performed by executing a program stored and held in the microcomputer in advance. First, as described above, the speed pulse is fetched from the detection unit 4 to the control unit 5 (S1), and the speed signal processing unit 5a determines the current rotation speed of the DC motor M from the pulse interval of the speed pulse (hereinafter referred to as the current value). ) Is calculated (S
2), the current value is input to the comparison unit 5c. On the other hand, a desired rotation speed (hereinafter referred to as a set value) set by the speed setting unit 5b is taken from the speed setting unit 5b (S
3) The comparison unit 5c compares the current value with the current value (S4).
If the current value is larger than the set value, that is, if it is desired to decelerate from the current rotational speed, the output of the comparing unit 5c (hereinafter, referred to as a command value) is increased (S4), and conversely, Is smaller than the set value, that is, when it is desired to accelerate from the current rotational speed, a calculation for decreasing the command value is performed (S5, S6). Further, the comparison unit 5c
The command value output from the control unit 5d is added with a constant correction value by the correction unit 5d (S7), and the corrected command value is converted into an analog voltage by the D / A conversion unit 5e (S8), and the voltage / current conversion unit 5f Is converted into a current (S9) and supplied to the light emitting diode LD of the photocoupler PC (S1).
0).

Here, the magnitude of the current supplied to the light emitting diode LD is proportional to the magnitude of the command value, and if the current supplied to the light emitting diode LD increases, the on-resistance of the phototransistor PT ( The collector-emitter resistance decreases and the reset current increases. Conversely, if the current supplied to the light emitting diode LD decreases, the on-resistance of the phototransistor PT increases and the reset current decreases. As a result, if the command value increases, the inductance of the magnetic amplifier ML increases and the DC motor M
The DC output supplied to the DC motor M decreases and the rotational speed of the DC motor M decreases. Conversely, when the command value decreases, the inductance of the magnetic amplifier ML decreases and the DC output supplied to the DC motor M increases. As a result, the rotation speed of the DC motor M increases.

Also, due to the non-linearity between the input and output of the voltage-current converter 5f of the control unit 5 and the photocoupler PC, the change of the DC output V ₀ of the converter 2 with respect to the command value has a linearity. In this embodiment, linearity is secured between the command value and the final DC output V ₀ of the converter unit 2 by adding a correction value to the command value output from the comparison unit 5c. It is so. Note that such correction arithmetic processing is performed by executing a stored program in the control unit 5 including a microcomputer.

In the above configuration, the reset current variable section 6 (photocoupler PC) that varies the magnitude of the reset current is
Control signal supplied to the light emitting diode LD of the input side from the control unit 5 (current) and the operating power, moreover, since the source of the reset current is secondary winding n ₂ of the transformer T, the converter unit Even if the DC output V _{0 of the} second device is substantially zero, the reset current variable unit 6 can be controlled by the control unit 5 to supply the reset current to the magnetic amplifier ML.
As a result, the DC voltage V ₀ of the converter unit 2 supplied to the DC motor M by the control unit 5 can be changed to an arbitrary value from substantially zero to the maximum rating, and when the DC motor M is operated at a constant speed. Also, appropriate control can be performed regardless of the load condition of the DC motor M. Further, in this embodiment, since the photocoupler PC is used for the reset current variable unit 6, the control unit 5 and the converter unit 2, the magnetic amplifier ML, and the DC motor M are electrically insulated. The operation power of the control unit 5 can be obtained from the power supply unit 1. In this case, there is no need to provide an independent power supply on the secondary side of the transformer T, and there is an advantage that the circuit configuration can be simplified and the entire device can be downsized.

In this embodiment, the reset current variable unit 6
Although the photocoupler PC is used in the first embodiment, for example, a magnetoresistance element may be inserted into the connection line 7 and an excitation coil magnetically coupled to the magnetoresistance element may be used. As in the case described above, the magnetoresistive element does not require an operating power source, and the magnetoresistive element and the exciting coil can be electrically insulated. be able to. In this embodiment, the case where the detection unit 4 detects the rotation speed of the DC motor M to perform the speed control has been described. However, the torque control is performed by using the torque sensor instead of the rotary encoder in the detection unit 4. Is also possible.

[0026]

According to the first aspect of the present invention, there is provided a power supply unit for supplying an AC output via a transformer, and having a characteristic that an inductance value changes in accordance with a magnitude of a reset current, and is connected to a secondary side of the transformer. A magnetic amplifier, a reset current supply unit that supplies a reset current to the magnetic amplifier, a converter unit that converts an AC output of a power supply unit supplied through the magnetic amplifier into a DC output, and a DC output from the converter unit. A detecting unit for detecting an operating condition such as a rotation speed or a torque of an operating DC motor; and a control unit for outputting a control signal for controlling the DC motor to a desired operating condition based on the operating condition detected by the detecting unit. And a reset current variable unit that changes the magnitude of the reset current according to the control signal using the control signal from the control unit as operating power. Even if the force is substantially zero, the reset current variable unit can be operated, and the DC output of the converter unit supplied to the DC motor by the control unit can be changed to an arbitrary value from substantially zero to the maximum rating, Even when the DC motor is operated at a constant speed, there is an effect that appropriate control can be performed irrespective of the load condition of the DC motor.

According to a second aspect of the present invention, there is provided a light emitting diode which emits light in response to a control signal from a control unit, and a phototransistor optically coupled to the light emitting diode and inserted into a reset current supply path from the reset current supply unit to the magnetic amplifier. Since the reset current variable section is configured by the photocoupler composed of the following, the control section is insulated from the magnetic amplifier, the reset current supply section, and the converter section, and the power supply of the control section can be supplied from the power supply section. There is an effect that the size can be reduced.

According to a third aspect of the present invention, there is provided an exciting coil which is excited by a control signal from a control unit, and which is magnetically coupled to the exciting coil and inserted into a reset current supply path from the reset current supply unit to the magnetic amplifier. And the control section is insulated from the magnetic amplifier, the reset current supply section and the converter section,
The power of the control unit can be supplied from the power supply unit, and the size of the entire device can be reduced.

According to the fourth aspect of the present invention, since the control section is provided with a correction means for correcting the control signal so that the change in the DC output of the converter section with respect to the control signal has a linearity, the DC output of the converter section with respect to the control signal is provided. There is an effect that unnecessary fluctuation and vibration of the rotation speed and torque of the DC motor due to the non-linearity of the change can be suppressed.

[Brief description of the drawings]

FIG. 1 is a circuit block diagram showing one embodiment of the present invention.

FIG. 2 is a flowchart illustrating an operation of the embodiment.

FIG. 3 is a circuit configuration diagram showing a conventional example.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 power supply unit 2 converter unit 3 reset current supply unit 4 detection unit 5 control unit 6 reset current variable unit ML magnetic amplifier T transformer

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-5-328715 (JP, A) JP-A-1-321889 (JP, A) JP-A-50-76715 (JP, A) 67187 (JP, B2) Jiko 62472 (JP, Y2) (58) Fields investigated (Int. Cl. ⁷ , DB name) H02P 5/00-5/26 H02P ⁷ /00-7/34 H02M 3/28 H03F 9/00

Claims (4)

(57) [Claims] 1. A power supply unit for supplying an AC output via a transformer, a magnetic amplifier having a characteristic that an inductance value changes according to a magnitude of a reset current and connected to a secondary side of the transformer, A reset current supply unit for supplying a reset current to the amplifier, a converter unit for converting an AC output of a power supply unit supplied through a magnetic amplifier to a DC output, and a rotation speed of a DC motor operated by the DC output from the converter unit And a control unit for outputting a control signal for controlling the DC motor to a desired operating condition based on the operating condition detected by the detecting unit, and a control from the control unit. A DC motor control device, comprising: a reset current variable unit that changes a magnitude of a reset current according to a control signal using a signal as operation power. 2. A photocoupler, comprising: a light emitting diode that emits light in response to a control signal from a control unit; and a phototransistor optically coupled to the light emitting diode and inserted into a reset current supply path from a reset current supply unit to a magnetic amplifier. 2. The DC motor control device according to claim 1, wherein the reset current variable section is configured by: 3. An exciting coil excited by a control signal from a control unit, a magnetoresistive element magnetically coupled to the exciting coil and inserted into a reset current supply path from a reset current supply unit to a magnetic amplifier. 2. The DC motor control device according to claim 1, wherein the reset current variable section is configured by the following. 4. The control unit according to claim 1, further comprising a correction unit configured to correct the control signal so that a change in the DC output of the converter unit with respect to the control signal has a linearity.
The DC motor control device according to any one of the preceding claims.