KR100223178B1 - The servo control method and the appratus of dc motor - Google Patents

Abstract

The present invention relates to a servo control method and apparatus for a DC motor, comprising the steps of: adaptively adjusting a bias value with respect to an offset value in order to cancel a phase change amount generated by an offset value of a system; And adding the bias value adaptively adjusted with respect to an offset value to the speed and phase control amount, and detecting a phase change amount generated by a servo control method of the DC motor. A bias adjuster for adaptively outputting a bias value for canceling this; And a bias input unit which adds a bias value input from the bias adjustment unit to the speed and phase control amounts. According to the present invention, the bias value can be adaptively inputted according to the system in order to cancel the phase change caused by the offset value that varies depending on the system, so that the phase change caused by the offset in the arbitrary system exceeds the allowable range. The influence can be prevented.

Description

Servo control method of DC motor and its device

The present invention relates to a servo control method and apparatus for a DC motor, and in particular, a bias value for detecting a phase change due to an offset caused by a characteristic difference of a DC motor and offsetting it is adaptively input. .

1 is a block diagram of a servo control apparatus of a DC motor used for a VTR.

The rotation speed of the DC motor is sensed by the frequency generator 10, and the rotation speed of the motor is converted into a voltage in the F / V converter 11, and the difference between the motor speed and the reference speed is output. The output speed difference is amplified by the first amplifier 12 to be a speed control amount. On the other hand, the integrator 13 integrates the speed error amount per one revolution of the motor and outputs the phase error amount. The phase detector 14 outputs the difference between the phase error amount and the reference phase. The first lag filter 15 is a compensator used to supplement the output characteristics of the phase detector. The difference between the phase error amount and the reference phase is compensated by the first lag filter 15 and then amplified by the second amplifier 16 to become a phase control amount. The speed control amount and phase control amount are added by an adder. The added speed control amount and phase control amount are amplified by the third amplifier 18 after the characteristics are compensated by the second lag filter 17. The amplified control amount causes the DC motor 19 to rotate at an appropriate speed.

On the other hand, consider a case where an offset (a value including a torque offset and an electrical offset) is applied by the characteristic difference of the DC motor.

FIG. 2 is a block diagram when an offset is applied to the servo control device of the DC motor of FIG. 1 by the characteristic difference of the DC motor.

As shown in Fig. 2, when an offset of ΔT is applied to the torque load variation T _L , the offset value is the transfer function 20 R / Kt (where R is the electric resistance of the motor and Kt is the torque of the motor). Is added to the speed and phase control amount in the second adder 21. When the offset ΔT is applied and the speed change of the motor is Δω, Δω can be obtained by using the final value theory as shown in Equation 1 below.

[Equation 1]

In Equation 1, 1 + G ₀ = 1 + G ₃ · G _M (G _{F /} VG ₁ + 1 / sG _{P /} DG ₂ ), approximated to 1 + G ₀ ≒ 1 /s.G _{P /} DG ₂ G ₃ G _M. Where G ₁ , G ₂ , and G ₃ are the gains of the first amplifier 12, the second amplifier 16, and the third amplifier 18, respectively, and G _M is the gain of the DC motor 19. _{F / V} represents the gain in the F / V converter, and G _{P / D} represents the gain in the phase detector 14, respectively.

Substituting 1 + G ₀ ≒ 1 / s G _{P / D} G ₂ G ₃ G _M into Equation 1, the following Equation 2 is obtained.

[Equation 2]

As shown in Equation 2, the constant speed control is possible because Δω approaches 0 due to the 1 / s term of the Laplace transform of the offset ΔT.

On the other hand, when the offset ΔT is applied, the phase change Δθ can be obtained by the following equation (3).

[Equation 3]

As shown in Equation 3, a phase change of Δθ is caused by the offset ΔT, and G, which is a gain of the phase detector 14, the first amplifier 12, and the second amplifier 16, in order to reduce Δθ. _{P / D} , G ₂ , and G ₃ should be increased. However, due to the stability of the servo system, these gains cannot be increased more than a certain amount. Therefore, in the related art, a method in which a bias input of an appropriate value is provided so that Δθ, which is a phase change due to an offset, falls within the allowable range.

3 is a block diagram of a servo control apparatus for a DC motor including a bias input unit according to the prior art.

As shown in FIG. 3, the bias input unit 30 is conventionally set, and a bias value for canceling Δθ is set and inputted, and the bias value is added to the speed and phase control amount in the third adder 31. Since the speed and phase control amount to which the bias value is added are digital data, they are modulated to the analog control amount from which the carrier signal is removed by passing through the pulse width modulator 32 and the low pass filter 33. The bias value input by the bias input unit 30 causes the phase change Δθ generated due to the offset ΔT to fall within the allowable range.

However, the conventional method described above cannot change the bias value set once. The offset ΔT may vary slightly for each motor and depending on the configured system. Nevertheless, in the conventional method, since the bias value is set to be the same, the phase change due to the offset is different depending on the product. In some cases, the phase change may not be within the allowable range due to the input bias value. In this case, the position of the head switch according to the phase change Δθ affects the screen of the VTR.

The present invention is to solve the problems of the prior art as described above, the present invention is to provide an apparatus that can adaptively input the bias value to cancel the phase change caused by the offset. In more detail, since the offset value varies from motor to motor and depends on the configured system, the system detects the phase change caused by the offset in each system and inputs a bias value capable of canceling the phase change.

1 is a block diagram of a servo control apparatus for a DC motor used in a VTR;

FIG. 2 is a block diagram when an offset is applied to the servo control device of the DC motor of FIG. 1 by the characteristic difference of the DC motor; FIG.

3 is a block diagram of a servo control apparatus for a DC motor including a bias input unit according to the prior art;

4 is a block diagram of a servo control apparatus for a DC motor according to an embodiment of the present invention;

5 is a flowchart for explaining the operation of the bias adjustment unit shown in FIG.

Explanation of symbols on the main parts of the drawings

10: frequency generator 11: F / V converter

12: first amplifier 13: integrator

14 phase detector 15 first lag filter

16: second amplifier 17: second lag filter

18: third amplifier 19: DC motor

20: R / Kt transfer function 21: second adder

30, 41: bias input unit 31: third adder

32: pulse width modulator 33: LPF

40: bias adjustment unit

In order to achieve the above object, in the servo control method of the DC motor to sense the speed of the DC motor to calculate the speed control amount and phase control amount, and to control the motor by the speed and phase control amount, the characteristics of the DC motor Sensing an offset value of the amount of phase change caused by the difference and adaptively adjusting a bias value to cancel the offset value; And adding the bias value adaptively adjusted with respect to an offset value to the speed and phase control amount.

In addition, the present invention is to detect the speed of the DC motor to calculate the speed control amount and phase control amount, and in the servo control apparatus of the DC motor for controlling the motor by the speed and phase control amount, which is generated by the characteristic difference of the DC motor A bias adjuster for sensing an offset value of a phase change amount and adaptively outputting a bias value for canceling the offset value; And a bias input unit which adds a bias value input from the bias adjustment unit to the speed and phase control amounts.

Hereinafter, with reference to the accompanying drawings, a preferred embodiment of the present invention will be described in detail.

4 is a block diagram of a servo control apparatus of a DC motor according to an embodiment of the present invention.

As shown in Fig. 4, the bias adjusting unit 40 is connected to the output terminal of the phase detector 14 of the servo control apparatus of the DC motor according to the prior art, and the bias input unit 41 is connected to the output terminal of the bias adjusting unit 40. Is connected. In addition, the structure and function of each part are the same as that of the servo control apparatus of the DC motor by a prior art.

The phase detector 14 detects the phase change Δθ generated by the offset value ΔT of the system. The bias adjustment unit 40 reads Δθ sensed by the phase detection unit 14 and outputs a bias value ΔB that can cancel this. The bias input unit 41 inputs to the third adder 31 such that the bias value ΔB output from the bias adjustment unit 40 is added to the speed and phase control amount.

As shown in Equation 3, when the offset value of the system is ΔT, the phase change Δθ is (R / K _t ) / (G _{P / D} · G ₂ · G ₃ ) · ΔT, so that the bias adjustment unit 40 When the bias value ΔB is output such that Δθ = 0, and the bias input unit 41 outputs the bias value ΔB to the third adder 31 so that the bias input is added to the speed and phase control amount, the DC motor is driven by the speed and phase control amount to which the bias value is added. By controlling, the phase change caused by the offset can be canceled out.

5 is a flowchart for explaining the operation of the bias adjustment unit 40.

The bias adjustment part 40 changes a bias value until the average of phase shift (DELTA) (theta) by an offset falls within 0 to an allowable range. In detail, first, the phase change Δθ caused by the offset is read from the phase sensor 14 (step 51). The mean is calculated by summing the already added phase changes Δθ that have been read in the previous step (step 52). Since Δθ includes a sign, the average can be obtained by summing. It is determined whether the calculated average value is within the allowable range α from 0 (step 53). If it is not within the allowable range, the bias value is changed (step 54) and the above steps are repeated until it is within the allowable range. If the calculated average value is within the allowable range, the current bias value is output (step 55).

The DC motor servo control method according to the present invention as described above is not used during normal operation. Since the offset value is set differently for each system, the bias value is calculated by operating in a test mode of a set production process such as a VCR. The calculated bias value can be stored in the microprocessor or in an E ² PROM. In addition, the bias value is calculated by operating only when the offset value of the system is changed, such as when a part of a product is replaced during use. This can be detected and operated at the user's option or automatically.

The servo control method and apparatus thereof of a DC motor according to the present invention can adaptively input a bias value according to a system in order to cancel a phase change due to an offset value that varies depending on the system. Therefore, according to the present invention, it is possible to prevent the phase change caused by the offset in any system from affecting the image quality beyond the allowable range. Servo control method and apparatus thereof for a DC motor according to the present invention are applicable not only to the VTR but also to systems (eg, CDROM, tape decoder, disk driver, DVD, etc.) for controlling the speed and phase using the DC motor. It is possible.

Claims (5)

In the servo control method of the DC motor to sense the speed of the DC motor to calculate the speed control amount and phase control amount, and to control the motor by the speed and phase control amount, Detecting an offset value of the amount of phase change caused by the characteristic difference of the DC motor and adaptively adjusting a bias value to cancel the offset value; And And adding the bias value adaptively adjusted to an offset value to the speed and phase control amount. The method of claim 1, wherein adaptively adjusting the bias value with respect to an offset value Sensing the amount of phase change generated by the offset value; Calculating an average value by adding the sensed phase change amount; Determining whether the average value of the calculated phase change amounts is within an allowable range; And If the average value of the phase change amount is not within the allowable range by the above step, the above-described steps are repeated after changing the bias value, and if the average value of the phase change amount is within the allowable range, the current bias value is achieved. Servo control method of a DC motor, characterized in that. 3. The servo control method of claim 1 or 2, wherein the servo control method of the DC motor is used after a test step of a manufacturing process of a system using a DC motor and replacement of parts during use. In the servo control apparatus of a DC motor for sensing the speed of the DC motor to calculate the speed control amount and phase control amount, and to control the motor by the speed and phase control amount, A bias adjuster which senses an offset value of a phase change amount caused by a characteristic difference of a DC motor and adaptively outputs a bias value for canceling the offset value; And And a bias input unit which adds a bias value input from the bias adjustment unit to the speed and phase control amounts. The servo control apparatus of claim 4, wherein the bias adjustment unit calculates an average value of the amount of phase change generated by the offset value and adjusts and outputs the bias value so that the average value is within an allowable range.