JPH07118935B2 - Motor control device - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a motor controller for a portable tape recorder, a video tape recorder, or the like.

2. Description of the Related Art Generally, in a recording / reproducing apparatus such as a tape recorder, a motor for driving a recording medium is controlled so that a relative speed of a rotating unit with respect to a fixed unit of the motor rotates at a constant speed.

However, in a portable recording / reproducing device, the device itself, that is, the main body to which the stator of the motor is attached is shaken by an external force, so that the relative speed of the fixed part of the motor and the rotating part, that is, the rotational speed, is the motion of the main body of the device. It has the drawback of fluctuating due to

Generally, the torque T applied to the rotating part and each speed Wmo of the rotating part
There are the following relationships.

T = Jm · dWmo / dt (1) where Jm is the moment of inertia of the rotating part. If the angular velocity of the fixed part of the motor due to disturbance is Wo and the relative angular velocity of the rotating part with respect to the fixed part is Wm = Wmo-Wo, equation (1) can be expressed as follows.

T = Jm ・ dWm / dt ＋ Jm ・ dWo / dt (2) Generally, a constant speed controlled motor controls the torque T of the motor so that Wm becomes constant, that is, in the formula (2), Jm ・ dWo / dt will act as a disturbance.

Conventionally, as a method of suppressing the fluctuation of the relative speed due to such a disturbance, a method of utilizing mechanical inertia balance has been used. That is, the two rotating bodies are coupled so as to rotate in mutually opposite directions so as to cancel the torque that changes the relative speed.

Problems to be Solved by the Invention However, when this method is used in a recording / reproducing apparatus,
There is a drawback that the mechanism becomes complicated and the weight and shape increase. Therefore, in particular, in the recording / reproducing apparatus having a plurality of motors such as a video tape recorder having a capstan motor for driving the tape and a cylinder motor for driving the rotary head, the above-mentioned conventional technique is hardly used.

Means for Solving the Problems A capstan motor controlled so as to obtain a constant rotation speed, a rotation shaft that is oriented in the same direction as the rotation shaft of the capstan motor, and mechanically the capstan motor. A cylinder motor that is supported on the same base material as the motor and that is controlled to obtain a constant rotation speed that has a higher frequency response than the capstan motor, and an electric signal that controls the rotation speed of the cylinder motor. The generated torque is detected by converting the torque into a torque using the constant of the cylinder motor, and the generated torque detected is the disturbance torque generated by the movement of the apparatus main body to which the capstan motor and the cylinder motor are attached. And the disturbance torque component is separated from the capstan motor by using a constant of the capstan motor. An electric signal for controlling the rotation speed, that is, an external compensation signal, is converted into an external compensation signal, and a disturbance compensation signal generating means for generating the disturbance compensation signal is provided, and the disturbance compensation signal which is an output signal of the disturbance compensation signal generating means is provided. The motor is controlled by adding it to a torque command signal for controlling the rotation speed of the capstan motor.

Effect The present invention is configured as described above, and in the capstan motor, the influence of disturbance on the relative speed between the fixed part and the rotating part,
That is, it is possible to reduce the second term of the above equation (2), Jm · dWo / dt.

Embodiment An embodiment of the motor control device of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing an embodiment of the present invention. In FIG. 1, reference numeral 101 denotes a capstan motor (hereinafter referred to as a first motor), and its rotation speed Wmo1 is detected by a frequency generator (hereinafter referred to as FG) 102. The output of the FG 102 is converted into a voltage according to the rotation speed by a frequency-voltage converter (hereinafter referred to as F / V converter) 103, and is guided to a servo amplifier 104. The servo amplifier 104 compares and amplifies the reference voltage 105 corresponding to the reference rotation speed with the output voltage of the F / V converter 103 to generate an error voltage. The error voltage is guided to the driver 106 via the adder 117. The driver 106 detects the motor current by the current detection resistor 107 and drives the motor 101 with a current according to the error voltage.

Similarly, 108 indicates a cylinder motor (hereinafter referred to as a second motor), and its rotation speed Wmo2 is detected by the FG 109. The output of the FG 109 is converted into a voltage according to the rotation speed by the F / V converter 110 and guided to the servo amplifier 111. The servo amplifier 111 compares and amplifies the reference voltage 112 corresponding to the reference rotation speed with the output voltage of the F / V converter 110 to generate an error voltage. The driver 113 detects the motor current with the current detection resistor 114, and the motor 10 outputs a current according to the error voltage.
Drive eight

The voltage generated in the current detection resistor 114 according to the current flowing in the motor 108 is guided to the disturbance detection circuit 115, and a predetermined voltage V
After subtracting s116, it is amplified and a disturbance correction signal C is output. The disturbance correction signal C is guided to an adder 117 provided between the servo amplifier 104 and the driver 106 of the first motor speed control feedback loop, added to the error signal output from the servo amplifier 104, and then added to the driver 106. Added.

Next, the operation of the motor control device configured as described above will be described. FIG. 2 is a control block diagram of the motor control device shown in FIG. The FG 102 and the F / V converter 103 that detect the rotation speed Wmo1 of the first motor are represented by a block 201. The servo amplifier 104 is represented by an addition point 202 and a block 203, and is compared and amplified with the reference voltage Vr1.
The error voltage is led to the electro-mechanical conversion portion of the driver 106 and the motor 101 represented by block 204 via an addition point 217. The voltage-current conversion gain in the driver 106 is represented by gm1,
This is equal to the reciprocal of the resistance value Rd1 of the current detection resistor 107. A value obtained by subtracting the load torque TL1 from the torque T1 generated by the motor 101 is added to the moment of inertia of the motor 101 and the load represented by the block 206 as an additional torque. The torque is converted into a speed in block 206, and a difference from the speed of the motor fixed portion, that is, a rotation speed Wmo1 is generated.

Similarly, FG109 that detects the rotation speed Wmo2 of the second motor
And the F / V converter 110 is represented by block 208. The servo amplifier 111 is represented by an addition point 209 and a block 210, and the reference voltage Vr2
And amplified. The error voltage is guided to the driver 113 represented by block 211 and converted into the current 12 with the voltage-current conversion gain gm2 equal to the reciprocal of the resistance value Rd2 of the current detection resistor 114. The current 12 is converted to torque T2 at the electro-mechanical conversion portion of the motor 108, represented by block 212. The torque T2 generated by the motor 108 minus the load torque TL2 is added as the acceleration torque to the moment of inertia of the motor 108 and the load represented by the block 214. The torque is converted to speed in block 214, and the difference with the speed of the motor fixed part,
That is, the rotation speed Wmo2 is generated.

The current 12 is converted into a voltage proportional to the current 12 by the current detection resistor 114 of the block 218, and after subtracting the predetermined voltage Vs at the addition point 219, it is multiplied by G in the block 216 to obtain the disturbance correction signal C.
Becomes

First, the rotation speed Wmo1 of the first motor when there is no disturbance correction signal C is expressed as follows using the s variable of the Laplace transform.

Wmol = {(w1 / Kf1) ・ Vr1− (1 / J1) ・ TL1−s ・ Wo} / (s + w1) …… (3) where w1 is represented by Kf1, Ka1, gm1, and Kt1 / J1. It is the response (angular) frequency of the speed control feedback loop of the first motor. In the parentheses of the numerator of the formula (3), the third term represents the fluctuation of the rotation speed caused by the shaking of the apparatus body described above.

FIG. 3 shows a Bode diagram of the transfer function from the rotational angular velocity Wo of the main body to the rotational velocity Wmo1. As is clear from FIG. 3, at a frequency lower than the response (angular) frequency w1 of the speed control feedback loop, the degree of influence from its transmission, that is, disturbance is reduced by the action of the servo, but at a frequency higher than w1. , Wo
The fluctuation of is reflected as a disturbance as it is. In order to improve this, the feedback gain of the speed control feedback loop must be increased, that is, w1 must be increased. But w1
Cannot be raised above a certain value due to restrictions such as FG frequency.

On the other hand, the current I2 flowing through the second motor is expressed as follows.

I2 = {(Ka2 ・ gm2 ・ s) ・ Vr2 ＋ (w2 / Kt2) ・ TL2 ＋ w2 ・ J2 / Kt2 ・ s ・ Wo} / (s + w2) …… (4) where w2 is Kf2 / Ka2 ・ gm2 ・ Kt2 It is the response (angular) frequency of the speed control feedback loop of the second motor represented by / J2. If the second motor is controlled at a constant speed,
The speed command voltage Vr2 is constant. Further load torque T
L2 also hardly changes as long as the load is constant. Therefore, the fluctuation of the current I2 flowing through the second motor corresponds to the fluctuation of the rotation speed Wo of the apparatus body. This current I2 can be detected by the current detection resistor 114.

Next, Vs and G are selected as follows.

Vs = (w2 / Kt2) ・ TL2 / (W2 ・ gm2) …… (5) G ＝ (J1 / J2) ・ (Kt2 / Kt1) ・ (gm2 / gm1) …… (6) Then the disturbance correction signal C Is as follows:

C = {J1 / (gm1 ・ Kt1)} ・ {w2 / (s + w2)} ・ s ・ Wo
(7) The rotation speed Wmo1 of the first motor when the disturbance correction signal C is expressed by equation (7) is expressed as follows.

Wmo1 = {(w1 / Kf1) ・ Vr1− (1 / J1) ・ TL1-s ・ Wo + gm1 ・ Kt1 / J1 ・ C} / (s + w1) = {(w1 / Kf1) ・ Vr1− (1 / J1) ・TL1-s ・ Wo + s ・ Wo ・ w2 / (s + w2)} / (s + w1) (8) Rotational angular velocity Wo of the main body when the correction signal C is added to FIG.
Shows the Bode diagram of the transfer function from to the rotation speed Wmo1. The frequency at which the fluctuation of Wo appears as a disturbance is the response (angular) frequency w1 of the speed control feedback loop of the first motor to the response (angular) frequency w2 of the speed control feedback loop of the second motor.
Is rising. Furthermore, at frequencies below the response frequency w1 of the speed control feedback loop of the first motor, the effect of disturbance is reduced in proportion to the square of the frequency.

EFFECTS OF THE INVENTION As described above, according to the present invention, it is possible to reduce fluctuations in the rotational speed of the motor that occur with the swing of the apparatus body without increasing the weight or volume due to the addition of mechanical elements. .

[Brief description of drawings]

FIG. 1 is a block diagram showing a motor control device according to an embodiment of the present invention, and FIG. 2 is a control block diagram of the device shown in FIG.
3 and 4 are Bode plots showing the transfer function from the disturbance to the rotation speed. 101 …… first motor, 102 …… FG, 103 …… F / V converter,
104 ... Servo amplifier, 105 ... Reference voltage, 106 ... Driver, 107 ... Current detection resistance, 108 ... Second motor, 109
…… FG, 110 …… F / V converter, 111 …… Servo amplifier, 112
...... Reference voltage, 113 …… Driver, 114 …… Current detection resistor,
115 ... Disturbance signal detection circuit, 116 ... Voltage source, 117 ... Adder.

Claims (1)

[Claims] 1. A capstan motor controlled so as to obtain a constant rotational speed, a rotary shaft facing in the same direction as the rotary shaft of the capstan motor, and mechanically identical to the capstan motor. Supported by the base material of
A cylinder motor having a frequency response higher than that of the capstan motor and controlled to obtain a constant rotation speed, and an electric signal for controlling the rotation speed of the cylinder motor are converted into torque using a constant of the cylinder motor. The generated torque is detected by separating the disturbance torque component generated by the movement of the apparatus main body to which the capstan motor and the cylinder motor are attached from the detected generated torque, and the constant of the capstan motor is set to A disturbance compensation signal generating means for generating the disturbance compensation signal by converting the disturbance torque component into an electric signal for controlling the rotation speed of the capstan motor, that is, a disturbance compensation signal. The disturbance compensation signal, which is the output signal of the means, controls the rotation speed of the capstan motor. A motor controller, characterized in that the plus the torque command signal for.