JP2973267B2 - Drive device for DC motor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a driving device for a DC motor.

[0002]

2. Description of the Related Art In recent years, DC motors used in VTRs and tape recorders and the like, particularly DC brushless motors, have a gentle current gradient for phase switching to obtain quiet and smooth rotation, and electrically correct torque ripple. In many cases, a drive device having a function of performing the above operation is used. For example, JP-A-61-
No. 142986 (hereinafter abbreviated as Document 1) discloses that the sum of the output in the inflow direction and the sum of the output in the outflow direction of the preamplifier are compared, and the difference is fed back to the offset adjustment terminal of the preamplifier. A method for removing the influence of the offset and the third harmonic of the Hall element, and comparing the sum of the output of the power amplifier and the output control signal, or the sum of the output control signal and the output of the preamplifier in the inflow direction, and using the difference, A method of suppressing the effect of sensitivity variation of the Hall element by controlling the amplification degree of the preamplifier or the supply voltage of the Hall element, and adding the output of the comparator of the offset adjustment loop of the Hall element to the output control signal. A method for reducing torque ripple is shown.

In order to control the output torque of the motor, a transistor and a resistor are connected in series with the motor, the current flowing through the motor is detected by the voltage across the resistor, and the control input voltage and the voltage across the resistor are detected. Compare the voltage with a differential amplifier,
It is common practice to control the motor current by controlling the base current of a transistor connected in series to the motor based on the output, and to control the output torque of the motor.

At this time, instead of directly comparing the control input voltage with the voltage across the resistor, the control input voltage Vc is once compared with the reference voltage Vt, and the level is shifted. It is common to make a comparison.

FIG. 10 is a block diagram showing a circuit configuration of such a DC motor driving device, and FIG. 11 shows an example of each characteristic.

In FIG. 10, the control input voltage Vc applied to the control input terminal 701 is the circuit power supply voltage Vcc
The reference voltage Vt obtained by dividing the voltage by 3, 24 is connected to the non-inverting input terminal of the preamplifier 700 (differential amplifier) connected to the inverting input terminal, and the output current Io is input to the resistor 22. Is done. The control amplifier 800 compares the voltage with the voltage generated in the resistor 21 by the motor current Im of the motor 40.

The output current circuit of the control amplifier 800 is connected to the base of the transistor 30,
A motor current control loop for controlling the motor current Im of the motor 40 connected to the collector 30 by the control input voltage Vc.

FIG. 11A shows the characteristics of the control input voltage (Vc) versus the motor current (Im), and FIG. 11B shows the characteristics of the motor current / rotational speed (N) versus the output torque (T). .

[0009]

However, in the method disclosed in the above document 1, a comparator and an amplifier need to be provided in the loop to form a feedback loop, and the circuit portion is formed into a one-chip integrated circuit (IC). in addition to a large chip area必, the main by when, in order to stabilize the operation of the feedback loop, the first problem that requires many external components for phase compensation I C outside was there.

In order to control a motor having a small moment of inertia or a motor whose rotation speed sampling interval cannot be made sufficiently small, the slope of the transfer characteristic shown in FIG. Is desirable.

However, if the transfer characteristic is set as shown in characteristic 2, even if the maximum value Vc max of the control input voltage Vc is applied, the starting torque of the motor decreases as shown by characteristic 2 in FIG. There was a second problem of getting lost.

SUMMARY OF THE INVENTION It is an object of the present invention to solve the first problem and to provide a DC motor drive device capable of suppressing torque ripple with a simpler circuit and fewer external parts than conventional ones.

[0013]

Means for Solving the Problems The present invention is converted, in order to solve the first problem, a means to generate a torque command current corresponding to the control input, the torque command current into a voltage
And the sum of the currents flowing through the stator windings
Means for generating an example voltage, and changing the torque command current.
Proportional to the sum of the converted voltage and the current flowing through the stator winding
Means for comparing output voltages and generating an output current command current
When the fixed amplifying the first current distribution means for distributing the output current command electrostatic <br/> current in response to the output of the magnetoelectric converting element, an output current of the first current distribution means, corresponding To the secondary winding
Current amplifying means for supplying a current to the stator winding
Generates a torque ripple correction command current proportional to the total current .
And a torque corresponding to the output of the magnetoelectric conversion element.
Second current distribution means for distributing the ripple correction command current
When, with a torque ripple correction signal generating means for combining the torque ripple correction signal from the output and torque ripple correction command current of the second current distribution means, said torque command current and the output current of the torque ripple correction signal generating means To <br/>.

[0014] The present invention also relates to the above rotor magnet.
Generates a trapezoidal wave with a flat part with an electrical angle of 60 degrees corresponding to the position
And a resistor for converting the torque command current into a voltage.
And proportional to the sum of the currents flowing through the stator windings
Means for generating a voltage and converting the torque command current
Voltage proportional to the sum of the voltage and the current flowing through the stator winding
Means for comparing the pressures and generating an output current command current;
The first to distribute the output current command current in proportion to the trapezoidal wave
Current distribution means, and the output current of the first current distribution means
To amplify the current and supply current to the corresponding stator winding.
Current amplifying means and the sum of the currents flowing through the stator windings.
Means for generating an example torque ripple correction command current;
The torque ripple correction command current is divided in proportion to the trapezoidal wave.
A second current distribution means to be distributed;
Torque ripple from output and torque ripple correction command current
A torque ripple correction signal generating means for synthesizing the correction signal.
An output signal of the torque ripple correction signal generating means.
Is added to the output signal of the torque command current generating means .

[0015]

According to the present invention, by means of the above-described structure,
Can be suppressed torque ripple with a simple circuit and fewer external components than the conventional and that Do.

[0016]

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

(Embodiment 1) FIG. 1 is a block diagram showing a circuit configuration of a DC motor driving apparatus according to a first embodiment of the present invention.

In FIG. 1, Hall elements 1, 2, and 3 are arranged on a stator (not shown) at an electrical angle of 120 ° from each other. These are connected to the input terminals of the output type Hall signal amplifiers 100, 200 and 300, respectively. Hall signal amplifier 100, 200, 30
Outputs of 0 are input terminals 401, 402, 403 of the logarithmic compression circuit 400.
, And logarithmically compressed output voltages are respectively supplied to a first distribution circuit (1) 500 and a second distribution circuit (2) 900
It is connected to the. The first distribution circuit (1) 500 converts the current input to the output current command terminal 501 in proportion to the voltage of the input terminals 401 to 403 of the logarithmic compression circuit 400, and outputs the output terminals 505 to 507.
And input terminals 601-60 of the power amplifier 600 from 508-510
3 and 604-606.

FIG. 2 shows a logarithmic compression circuit 400 in FIG.
FIG. 3 is a circuit diagram showing an example of a first distribution circuit (1) 500, which is a circuit in which a basic analog multiplication circuit has a three-differential configuration and further supports signals in both positive and negative directions. Due to the nature of the three-phase sine wave, one of the three diodes and transistors is always reverse biased and is in an off state, and operates as a normal multiplier, and is proportional to the voltage ratio of the input terminals 401 to 403. Output current command terminal
Distribute the current of 501 and output terminals 505-507 and 508-510
Output to

Next, the power amplifier 600 shown in FIG. 1 has a current discharge terminal 60 for discharging a current equal to the output current in the suction direction.
7, the current discharge terminal 607 is connected to one end of the resistor 21 and generates a voltage in the resistor 21 that is proportional to the motor current. The output of the power amplifier 600 is connected to the stator windings 4, 5, and 6, and supplies a current to the stator windings corresponding to the position of the rotor magnet to generate a rotating torque for the motor.

The voltage applied to the control input terminal 701 is level-shifted and current-converted by the preamplifier 700, input to the resistor 22, and compared with a voltage proportional to the motor current generated in the resistor 21 by the control amplifier 800. The output signal proportional to the error is output to the output current command terminal of the first distribution circuit (1) 500.
An output current control loop is formed by being applied to 501.

The current detection circuit 1100, together with the resistor 21, generates a current proportional to the motor current, and the output current command terminal 901 of the second distribution circuit (2) 900 and the waveform synthesis circuit 100
The current is supplied to the 0 output current command terminal 1001.
The output of the second distribution circuit (2) 900 is connected to the waveform synthesizing circuit 1000 to generate a torque ripple correction signal, and the torque ripple correction signal is guided to the resistor 22 and after being added to the output of the preamplifier 700. It becomes an input of the control amplifier 800 and forms a torque ripple correction loop.

The operation of the DC motor driving apparatus constructed as described above will be described with reference to FIG. 1, FIG. 3, FIG. 4, and FIG.

First, FIG. 3 shows the second distribution circuit (2) 900 of FIG.
3A and 3B are operation waveform diagrams illustrating operations when there is no feedback by the waveform synthesizing circuit 1000. The output voltages of the Hall elements 1 to 3 are converted into currents by the Hall signal amplifiers 100 to 300, and FIG. Are input to the input terminals 401 to 403 of the logarithmic compression circuit 400 in FIG. FIG. 3B shows the voltages at the output terminals 404 to 406 of the logarithmic compression circuit 400. As described above, the first distribution circuit (1) 500 distributes the current of the output current command terminal 501 in proportion to the voltage of the input terminals 401 to 403 of the logarithmic compression circuit 400. 3 (c),
The current of FIG. 3D is output from the output terminals 505 to 507. Therefore, the output terminals 608 to 610 of the power amplifier 600 are connected as shown in FIG.
Is obtained. FIG. 3 (f) shows the output torque, which is about 14
Contains 100% torque ripple.

FIG. 4 is an operation waveform diagram of each part in FIG. 1 when feedback is applied by the second distribution circuit (2) 900 and the waveform synthesis circuit 1000, and FIGS. These are the same as 3 (a) and (b). FIG. 4C shows the voltage waveform at the output terminal 1002 of the waveform synthesizing circuit 1000 shown in FIG. Therefore, the power amplifier
4 (d) is obtained at the output terminals 608 to 610 of the 600.
The ripple of the output torque shown by (e) is about 2% or less.

FIG. 5 shows the second distribution circuit (2) 900 in FIG.
FIG. 6 is a circuit diagram showing an example of a waveform synthesizing circuit 1000, and FIG. 6 is an operation waveform diagram of each part in FIG.

FIG. 6A shows the power amplifier 60 when there is no feedback by the waveform synthesizing circuit 1000 corresponding to the electrical angle shown in the upper part.
0, and (b) shows currents I21-I23 and I34-I flowing through transistors T21-T23 and T34-T36 to be described later.
36, (c) shows the transistors T25 to T27 and T31 to
The currents I25-I27 and I31-I33 flowing through T33, (d) are the currents I43-I45 flowing through the transistors T43-T45, (e)
Are the currents I46-I flowing through the transistors T46-T48.
48, (f) shows the current I4 flowing through the transistors T41 and T52.
1 and I52, (g) are output currents of the power amplifier 600 when the feedback by the waveform synthesizing circuit 1000 is applied.

Now, referring to FIG.
11, T12, T13, T21, T22, T23, T25, T26, T27
Has twice the emitter area of the other transistors, and the transistors T14 and T15 have three times the emitter area of the other transistors.
The current flowing through each transistor, I14 and I15 are 1.11 of I11.
Five times, I24 and I28 become 0.5 times the current of I11. I34 obtained by distributing I15 by transistors T34, T35 and T36,
I35, I36 and I21, I22, I23 are subtracted to obtain I43, I44,
I45 is obtained in the same manner as I46, I47 and I48. Further, by subtracting I43, I44 and I45 from I24, I41 becomes I28
I52 is obtained by subtracting I46, I47 and I48 from. I41
And I52 are added and output to the output terminal 1002 to become a torque ripple correction signal. This torque ripple correction signal is added to the output signal of the preamplifier 700 of FIG. 1 to generate the voltage shown in FIG. 4C at the resistor 22 of FIG. A ripple suppressing effect can be obtained.

(Embodiment 2) Embodiment 1 shows a case where the Hall elements 1 to 3 for detecting the position of the rotor magnet are used, and a magneto-electric conversion element is assumed. However, the current waveform shown in FIG. If possible, a magnetoelectric conversion element is not necessarily required. For example, if a trapezoidal wave having a flat portion having an electrical angle of 60 ° corresponding to the position of the rotor magnet can be generated by the method disclosed in JP-A-3-89890, the method shown in FIGS. As a result, a torque ripple correction signal can be obtained, so that a torque ripple suppression effect similar to that shown in FIG.

[0030] (Comparative Example) FIG. 7 is a block diagram showing a circuit configuration of a motor driving device in a comparative example of the real施例of the present invention. This shows a means for performing stable control without reducing the starting torque even in a motor having a small moment of inertia or a motor whose rotation speed sampling interval cannot be made sufficiently small.

In FIG. 7, the control input voltage Vc applied to the control input terminal 711 is obtained by changing the circuit power supply voltage Vcc to the resistors 23, 3
The reference voltages Vt1 and Vt2 produced by dividing the voltages by 5, 24 are connected to the non-inverting input terminals of preamplifiers (current output differential amplifiers) 710 and 720 connected to the inverting input terminals, respectively. I2 and I3 are input to resistor 22;
Motor 40 with control amplifier 800 (error amplifier, differential amplifier)
Is compared with the voltage generated in the resistor 21 by the motor current Im. The output current of control amplifier 800 is transistor 3
0, and forms a motor current control loop for controlling the motor current Im of the motor 40 connected to the collector of the transistor 30 with the control input voltage Vc.

FIG. 8 shows a characteristic diagram of the motor current (Im) and the output currents I2 and I3 of the preamplifier in FIG. 7, (a) is a characteristic diagram of the control input voltage (Vc) versus the motor current (Im), (b) is a characteristic diagram of the control input voltage (Vc) versus the output currents I2 and I3 of the preamplifier.

In the circuit diagram of the comparative example shown in FIG.
Since this control loop operates with a current obtained by adding I2 and I3, the control input voltage Vc and the motor current Im are equal to the characteristic 2 in FIG.
The relationship is as shown in FIG.

Comparing the characteristic 2 with the characteristic of the conventional control circuit represented by the characteristic 1, since the inclination is smaller than the characteristic 1 near the normal operating point Iop, the sampling interval of the motor or the rotational speed having a small moment of inertia is small. Is not sufficiently reduced, the characteristic is suitable for motor speed control in which the ripple of the control input voltage cannot be completely removed. If the inflection point It of the characteristic is set higher than the maximum operating point, the control input voltage V
For the maximum value Vcmax of c, a motor current Imax equal to or more than the characteristic 1 can be obtained, and a good control characteristic can be obtained without a decrease in the starting torque.

The same effect can be obtained even if the characteristic of the preamplifier 720 is changed to the characteristic indicated by I3 in FIG.

Although the description has been made with reference to an example of one transistor, it goes without saying that the present invention can be applied to an apparatus for driving a motor using a plurality of transistors in a power amplifier as shown in FIG.

[0037]

As described in the foregoing, according to the DC motor evening driving device of the present invention, it is possible to suppress the torque ripple in a simple circuit and fewer external components than the traditional.

[0038]

[Brief description of the drawings]

FIG. 1 is a block diagram showing a circuit configuration of a motor drive device according to a first embodiment of the present invention.

FIG. 2 is a circuit diagram showing an example of a logarithmic compression circuit and a first distribution circuit (1) in FIG.

FIG. 3 is an operation waveform diagram of each unit for explaining an operation when there is no feedback by a second distribution circuit (2) and a waveform synthesis circuit in FIG. 1;

FIG. 4 is an operation waveform diagram of each section for explaining an operation when feedback is applied by a second distribution circuit (2) and a waveform synthesis circuit in FIG. 1;

FIG. 5 is a circuit diagram showing an example of a second distribution circuit (2) and a waveform synthesis circuit in FIG.

FIG. 6 is an operation waveform diagram of each section for explaining the operation of the second waveform synthesis circuit (2) and the waveform synthesis circuit in FIG. 5;

7 is a block diagram showing a circuit configuration of a motor driving device in a comparative example of the real施例of the present invention.

FIG. 8 is a graph showing a relationship between a control input voltage and a motor current in FIG. 7;
(a) and control input voltage vs. output current characteristics of the preamplifier
(b).

9 is a diagram (a) of another control input voltage versus motor current characteristic and a diagram (b) of a control input voltage versus output current of the preamplifier in FIG. 7;

FIG. 10 is a block diagram showing a circuit configuration of a conventional motor driving device.

11A and 11B are a control input voltage-motor current characteristic diagram and an output torque-motor current / rotation speed characteristic diagram (b) of the motor drive device of FIG.

[Explanation of symbols]

1,2,3… Hall element, 4,5,6… Stator winding,
40… motor, 100,200,300… Hall signal amplifier,
400: logarithmic compression circuit, 500: first distribution circuit (1), 50
1,901,1001 ... output current command terminal, 600 ... power amplifier, 607 ... current discharge terminal, 700,710,720 ... preamplifier, 800 ... control amplifier, 900 ... second distribution circuit (2),
1000: Waveform synthesis circuit, 1100: Current detection circuit.

Continuation of the front page (72) Inventor Yasunori Terai 2--18 Keihanhondori, Moriguchi-shi, Osaka Sanyo Electric Co., Ltd. (56) References JP-A-3-89890 (JP, A) JP-A-5-83983 (JP, A) JP-A-61-295891 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) H02P 6/10

Claims (2)

(57) [Claims] 1. A DC motor driving device comprising a three-phase stator winding, a rotor magnet, and three magneto-electric conversion elements for detecting a position of the rotor magnet, wherein a torque corresponding to a control input is provided. means for generating a command current, the
A resistor for converting a torque command current into a voltage, and the stator
Means for generating a voltage proportional to the sum of currents flowing through windings
And a voltage obtained by converting the torque command current and the stator winding.
Compare the voltage proportional to the sum of the currents flowing through the
Means for generating the current command current and the output of the magnetoelectric conversion element.
First current distribution means for distributing the output current command current in response, and amplifying the output current of the first current distribution means,
A current amplifying means for supplying current to the stator windings corresponding, means for generating a torque ripple correction command current proportional to the total sum of the currents flowing through the front Symbol stator winding, the output of the magnetoelectric converting element A second current distribution means for distributing a torque ripple correction command current correspondingly; and a torque ripple correction signal generating means for synthesizing a torque ripple correction signal from an output of the second current distribution means and the torque ripple correction command current. The output voltage of the torque ripple correction signal generating means.
Driving device for a DC motor, characterized by comprising adding a flow to said torque command current. 2. A drive device for a DC motor having a three-phase stator winding and a rotor magnet, wherein a trapezoidal wave having a flat portion having an electrical angle of 60 degrees corresponding to the position of the rotor magnet is generated. Means for converting the torque command current into a voltage.
And the sum of the currents flowing through the stator windings
Means for generating a proportional voltage; and
The ratio between the converted voltage and the total current flowing through the stator winding
Means for comparing output voltages and generating an output current command current
A first current distribution unit that distributes the output current command current in proportion to the trapezoidal wave; and amplifies an output current of the first current distribution unit to supply a current to the corresponding stator winding. Current amplifying means, and the total current flowing through the stator windings.
Means for generating a torque ripple correction command current proportional to the sum, second current distribution means for distributing the torque ripple correction command current in proportion to the trapezoidal wave, and an output of the second current distribution means and torque ripple. A torque ripple correction signal generating means for synthesizing a torque ripple correction signal from the correction command current is provided, and an output signal of the torque ripple correction signal generating means is added to an output signal of the torque command current generating means. Drive device for DC motor.