JP2003079171A - Offset automatic adjustment equipment of motor drive circuit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide offset automatic adjustment equipment of motor drive circuit which detects offset of a motor drive circuit for driving a motor and performs automatic adjustment. SOLUTION: The offset automatic adjustment equipment is provided with a control means comprising a detection resistor 30 for detecting a current flowing in a motor 600, a control part 10, etc., a power-amplifying part 20 for amplifying power of a signal from a control part 10, an A/D conversion part 50 for detecting the output voltage of the control part 10, a digital operator 60 and a D/A conversion part 70 which adjust an output of the A/D conversion part 50, and a switch 80 arranged between the control part 10 and the detection resistor 30. The control part 10 performs feedback control in order to set a current detected by the detection resistor 30 to be a prescribed value.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automatic offset adjusting device for a motor drive circuit for driving a motor used for speed control or position control in industrial equipment, machine tools, etc., and more particularly to detecting an offset voltage of the motor drive circuit. , A device for automatic adjustment.

[0002]

2. Description of the Related Art Generally, a motor is often used as an actuator for controlling a table or the like in industrial equipment, machine tools, etc. Since the motor generates torque and force depending on current, the motor drive circuit is a motor. It is often configured to detect current and perform feedback control.

FIG. 7 is a schematic configuration diagram showing an example of a motor drive circuit according to a conventional example. The drive circuit 700 detects the motor current flowing through the motor 600 with the detection resistor 730, amplifies the signal with the amplifier 740, inputs the difference from the current command value to the control unit 710, and outputs the command value and the detected motor current signal. A control signal is generated so as to be equal to each other, and power amplification is performed by the power amplification unit 720 to drive the motor 600. By the motor drive circuit 700 controlling the motor current,
A desired torque or force is obtained in the motor 600.

At this time, the motor current detection circuit of the amplifier 740, the current command circuit to which the current command value is input, and the control section 7 for amplifying the difference between the current command value and the motor current signal.
When the offset is superimposed on the circuit of 10, the motor output torque or force does not become zero with respect to the current command value zero, and there is a problem that the motor output torque or force is generated depending on the offset of each circuit. there were.

Since the offset of each circuit is small and difficult to detect, in the conventional example, the current command value is set to zero and the voltage across the motor 600 is measured by a measuring device such as a tester, and the value is adjusted to zero. The voltage 750 is adjusted and added to adjust the offset voltage of the motor drive circuit 700.

[0006]

However, in the above-mentioned prior art, since the voltage across the motor during operation becomes a large voltage, even if the automatic offset measuring circuit is added, the minute voltage across the motor generated by the offset can be accurately measured. It could not be detected well and was difficult to automate. As a result, the offset adjustment of the motor drive circuit requires a human measurement step and an adjustment step, which takes a long time for adjustment, resulting in a high cost.

Further, in the conventional technique, since it is not automated, it is not possible to adjust the change in the offset of each circuit due to temperature, aging, etc., and there is a problem that an accurate offset adjustment cannot be performed.

In view of these problems, the present invention is an automatic offset adjusting device for a motor drive circuit used for controlling a table or the like in industrial equipment, machine tools, etc., which shortens the adjustment time and reduces the cost. The purpose is to provide a device. It is a further object of the present invention to provide a more accurate offset automatic adjustment device for a motor drive circuit by automatically detecting and adjusting changes in offset due to temperature, aging, and the like.

[0009]

In order to achieve the above object, an automatic offset adjusting apparatus for a motor drive circuit according to the present invention is an automatic offset adjusting apparatus for a motor drive circuit for driving a motor. A motor current detecting means for detecting a current flowing through the motor; a control means for performing feedback control to bring the current detected by the motor current detecting means to a predetermined value; and power amplification of a signal from the control means. Offset voltage detecting means for detecting the output voltage of the control means, offset voltage adjusting means for adjusting the output of the offset voltage detecting means, and between the control means and the motor current detecting means. And a switch provided in.

With the above arrangement, in the present invention, the offset voltage of the motor current detection means and the offset voltage of the control means for performing feedback control can be detected with high sensitivity by the offset voltage detection means for detecting the output voltage of the control means. Therefore, it becomes possible to automatically adjust the offset of the motor drive circuit by adjusting the output of the offset voltage detecting means to, for example, zero by the offset voltage adjusting means. Therefore, according to the present invention, it is possible to configure the automatic offset adjusting device for the motor drive circuit, which can reduce the adjustment time and reduce the cost.

In the present invention, in the automatic offset adjusting device for the motor drive circuit, it is preferable that the predetermined value in the control means is, for example, zero, and the output of the power amplification means is shut off by the switch. The offset voltage adjusting means may adjust the output of the offset voltage detecting means (for example, adjust the output of the offset voltage detecting means to be zero).

With the above structure, in the present invention, when the predetermined value in the control means is zero, the output of the power amplification means is cut off by the switch for cutting off the output of the power amplification means, and the offset voltage of the motor current detection means is The offset voltage of the control means for performing feedback control can be detected with high sensitivity by the offset voltage detection means for detecting the output voltage of the control means, and the output of the offset voltage detection means is adjusted to, for example, zero by the offset voltage adjustment means. It is possible to automatically adjust the offset of the motor drive circuit. Therefore, according to the present invention, it is possible to configure a more accurate offset automatic adjustment device for a motor drive circuit by adjusting changes in offset due to temperature, aging, and the like.

Further, in the present invention, whether or not the automatic offset adjusting device of the motor drive circuit drives at least one of a power source section, an oscillating section, and an integrating section in conjunction with opening and closing of the switch. ON / OFF
It is preferable that the offset of the motor drive circuit is automatically adjusted by inputting an OFF signal.
Further, the motor may be a linear motor.

According to the present invention, even in the drive circuit of the linear motor which is driven by a large amount of power, the predetermined value in the control means is zero, and the switch for cutting off the output of the power amplification means is used to switch the power amplification means. With the output cut off,
The offset voltage adjusting unit is configured to adjust the output of the offset voltage detecting unit to zero, so that the offset voltage of the motor current detecting unit and the offset voltage of the control unit for performing feedback control are controlled by the control unit. It becomes possible to detect with high sensitivity by the offset voltage detecting means for detecting the output voltage of the motor, and it is possible to automatically adjust the offset of the motor drive circuit by adjusting the output of the offset voltage detecting means to zero by the offset voltage adjusting means. .

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below. (First Embodiment) FIG. 1 is a schematic configuration diagram of an automatic offset adjusting apparatus for a motor drive circuit according to an embodiment of the present invention. The drive circuit 100 detects the motor current flowing through the motor 600 with the detection resistor 30, amplifies the signal with the amplifier 40, and inputs the difference from the current command value to the control unit 10,
A control signal is generated so that the command value and the detected motor current signal become equal, and power amplification is performed by the power amplification unit 20 to drive the motor 600. The drive circuit 100 controls the motor current to obtain a desired motor output torque or force in the motor 600.

The control unit 10 may be composed of, for example, an amplifier 40 having a very high gain. The power amplification unit 20 varies depending on the type of the motor 600 and the required output torque or force.
It may be composed of discrete components such as an S-FET, or an integrated power amplifier may be used. In addition, the power amplification unit 20 has a PWM (Pulse Width Modulati
On) power may be amplified.

When the offset of the motor drive circuit 100 is automatically adjusted, the current command value is zero, and the output of the power amplification section 20 is cut off by the switch 80. An offset voltage detecting means for detecting an offset voltage is connected to the output of the control unit 10, and this detecting means is constituted by an A / D converter 50 as shown in FIG. 1, for example. A / D
The digital calculator 60 calculates an offset adjustment voltage so that the offset voltage detected by the converter 50 becomes zero, and this signal is added to the preceding stage of the control unit 10 through the D / A converter 70. The digital calculator 60 may be an inexpensive microcomputer. Control unit 10
By adjusting the offset voltage of 1 to zero, the offset of the motor drive circuit can be automatically adjusted.

The offset voltage and the automatic offset adjustment method in each circuit will be described in more detail. FIG. 2 is a schematic block diagram of the automatic offset adjusting apparatus for a motor drive circuit according to the embodiment of the present invention shown in FIG. 1, in which an offset voltage generated in each circuit is added.

In the figure, V_os1 Is the motor current detection
Is the equivalent input offset voltage of the amplifier 40 in the circuit
It V_os2 Is the equivalent input offset voltage of the controller 10.
is there. V_os3 Is the equivalent input when the current command value is input
It is an offset voltage. V_{os Four} Is the power amplification unit 20, etc.
Input offset voltage. The control unit 10 has been described above.
As such, it usually has a very high gain. Its value is for
Depending on the way, gain of about 10 to 1000 times
Have.

[0020] In general, in the feedback control, the offset voltage (V _os1) and equivalent input offset voltage of the control unit 10 (V _os2) and the command value input of the offset voltage of the feedback signal detection unit (V _os3) is offset in the control output On the other hand, the offset voltage superimposed on the output stage of the control unit 10, that is, the equivalent input offset voltage (V _os4 ) of the power amplification unit 20 is suppressed by the high gain of the control unit 10 while _{causing an error} , and thus the offset of the control output. It can be ignored as an error.

Therefore, the offset of the motor drive circuit of the present invention is
Also in the automatic control device,
Force offset voltage (V_os4 ) Is a high value of the control unit 10.
It is suppressed by the gain and the offset of the motor drive circuit output is
There is no problem as an error. Must be detected and adjusted
The offset voltage that must be obtained is V_os1 , V_os2 , V
_os3 Is.

In this embodiment, when the offset automatic adjustment is performed, the output of the power amplification section 20 is shut off by the switch 80. As a result, the effect of the equivalent input offset voltage V _os4 of the power amplification unit 20 is removed, and the equivalent input offset voltage V _os1 of the amplifier 40 in the motor current detection circuit is removed.
Is amplified by the amplifier 40 and the control unit 10 with a high gain and detected by the A / D converter 50. In addition, when such automatic offset adjustment is performed, since it is amplified with a high gain of the control unit 10, a minute offset voltage V _{os1 is obtained.}
Can be detected with high sensitivity.

[0023] By the current command value inputted to the motor drive circuit 100 to zero, and the equivalent input offset voltage V _os3 when the current command value is input, and the equivalent input offset voltage V _os2 the control unit 10 The signal is amplified by the control unit 10 with high gain and detected by the A / D converter 50. Further, since the control unit 10 is amplified with a high gain, the minute offset voltages V _os2 and V _os3 can be detected with high sensitivity.

In the present embodiment, the digital calculator 60 calculates the offset adjustment voltage so that the offset voltage detected by the A / D converter 50 becomes zero, and the D / A
The offset is added to the previous stage of the control unit 10 through the converter 70, and the offset of the motor drive circuit 100 can be automatically adjusted.

As described above, the predetermined value in the control means,
That is, the current command value is zero, and the output of the power amplification unit 20 is shut off by the switch 80, and the digital calculator 60, which is the offset voltage adjusting means, and the A / D, which is the offset voltage detecting means, by the D / A converter 70. It is arranged to make adjustments so that the output of the converter 50 is zero. By this, the offset voltage of the motor current detection means and the offset voltage of the control means for performing feedback control are
It is possible to detect the output voltage of the control means with high sensitivity by the offset voltage detection means, and it is possible to automatically adjust the offset of the motor drive circuit by adjusting the output of the offset voltage detection means to zero by the offset voltage adjustment means. Becomes

Therefore, according to the present embodiment, it is possible to configure the automatic offset adjusting device for the motor drive circuit which can shorten the adjustment time and reduce the cost.

In this embodiment, since the offset voltage of the motor drive circuit 100 is automatically adjusted while the power amplifier 20 is cut off, the type of the motor 600, the required output torque or force, and the power amplification of the motor drive circuit 100 are performed. Part 2
The present invention can be applied to any motor 600 and power amplifier 20 configuration regardless of the zero configuration.

(Second Embodiment) In the present embodiment, another example of the configuration of the power amplification section in each of the above-described embodiments is shown in FIG.
Shown in. The power amplification unit 20 includes a switch 80A that cuts off input to the power amplification unit 20, a power amplification power supply 22 that supplies power to the power amplification unit 20, and an on-power switch for turning on / off the power amplification power supply 22. It may be configured by an ON / OFF signal. The signal from the control unit 10 is cut off by the switch 80A and the power amplification power supply 22 is also turned off, so that the output of the power amplification unit 20 is completely cut off and the offset voltage of the motor drive circuit is automatically adjusted. You can

(Third Embodiment) In the present embodiment, another example of the configuration of the power amplification section in each of the above-described embodiments is shown in FIG.
Shown in. The power amplification unit 20A illustrated in FIG. 4 is an example of a power amplification unit using PWM. The PWM generates a PWM signal having a pulse width according to the control signal by an oscillating unit 25 that oscillates at a constant frequency and a comparing unit 26 that compares the control signal from the control unit 10 with the oscillation signal from the oscillating unit 25. To do. Normally, the signal generated by the oscillator 25 is a triangular wave signal, and the comparator 26 is composed of a comparator.

The generated PWM signal is power-amplified by the PWM power amplification unit 27 and the power supply 22 for the power amplification unit, and is filtered by the filter unit 29 as necessary to drive the motor 600 (see FIG. 1 or FIG. 2). To do.

In general, the PWM power amplifier 27 is composed of power discrete components such as power MOS-FET.

In this case, an ON / OFF signal for stopping the operation of the oscillator 25 or a comparator 2
The power amplifier 20 with the switch 28 for shutting off the output of
The output of A is completely cut off, and the offset voltage of the motor drive circuit can be automatically adjusted.

(Fourth Embodiment) In this embodiment, another example of the configuration of the control unit in each of the above-described embodiments is shown in FIG. In the figure, the control unit 10A has a high proportional gain 1
2 and an integrator 14, and proportional-integral control is performed.

When automatic offset adjustment of the motor drive circuit is performed, the integrator 14 is configured to be shut off by an ON / OFF (ON / OFF) signal, and the output voltage of the control unit 10A is controlled by the A / D converter 50. By the detection, the offset voltage of the motor current detection means and the offset voltage of the control means for performing feedback control can be detected with high sensitivity by the offset voltage detection means for detecting the output voltage of the control means. Thus, the output of the offset voltage detecting means can be adjusted to zero and the offset of the motor drive circuit can be automatically adjusted.

In this embodiment, when the predetermined value in the control means is zero, that is, the current command value is zero, the output of the power amplifying means is cut off by the switch for cutting off the output of the power amplifying means, and the offset voltage adjusting means offsets the output. Adjustment may be made so that the output of the voltage detection means becomes zero.

In general, the predetermined value in the control means of the motor drive circuit, that is, the current command value is a signal for performing speed control or position control using the motor as an actuator, and the speed control or position control is performed. The computer for controlling outputs the current command value to the motor drive circuit. Therefore, whether or not the current command value is zero can be easily output as a signal from the computer. In the present embodiment, the power amplification unit switch 80 shuts off the output of the power amplification unit 20 in synchronization with this signal, thereby performing a feedback control of the offset voltage of the motor current detection unit of the amplifier 40 and the control unit 10. Offset voltage of the control means A for detecting the output voltage of the control means
The offset voltage detecting means of the D / D converter 50 can detect it with high sensitivity.
It becomes possible to automatically adjust the offset of the motor drive circuit by adjusting the output of the offset voltage detecting means to zero by the offset voltage adjusting means of the converter 70.

The state in which the predetermined value in the control means of the motor drive circuit is zero, that is, the current command value is zero, may be generated in sequence by a computer that performs speed control or position control, or temperature and time may be observed. However, it may be configured to generate as needed.

Therefore, according to this embodiment, it is possible to adjust a change in offset due to temperature, aging, etc., and to configure a more accurate automatic offset adjusting device for the motor drive circuit.

(Fifth Embodiment) The motor driven by the motor drive circuit of each of the above embodiments may be a linear motor. In this embodiment, the motor 600 used
As an example (see FIG. 1 or 2), a linear motor is shown in FIG. In the same figure, a structural example of a two-phase linear motor is shown in (a), and its electrical equivalent circuit is shown in (b).

As shown in FIG. 6A, in the linear motor, the permanent magnets 510 arranged at a certain magnetic pole pitch and the yoke 5 are arranged.
20 and the α-phase winding 530 through which the drive current flows, and the β-phase winding 540, it is possible to obtain a horizontal force proportional to the drive current.

The electrical equivalent circuit shown in FIG. 6B is
It is represented by an equivalent resistance 560 and an equivalent inductor 570. In a large thrust linear motor capable of obtaining a force of several [N] to several hundred [N], the equivalent resistance 560 is several tens [Ω], the equivalent inductor 570 is several tens [mH], and the required driving current is several [ A] to several tens of [A]. Therefore, the voltage across the motor during driving is a very large voltage of several tens [V] to several hundreds [V].

On the other hand, the offset voltage of each part of the drive circuit is a minute voltage of about several mV, but the automatic offset voltage adjustment device for the motor drive circuit of the present embodiment cuts off the output of the power amplification part 20. Since adjustment is performed in the
Accurate automatic adjustment of the offset voltage can be performed even in a motor drive circuit that drives a linear motor that requires a large drive current and a large drive voltage. This is extremely effective when performing precise stage control and the like using a large thrust linear motor.

Therefore, according to the present embodiment, even in the drive circuit of the linear motor which is driven by a large amount of electric power, when the predetermined value in the control means is zero, the power is cut off by the switch for cutting off the output of the power amplification means. With the output of the amplifying means cut off, the offset voltage adjusting means adjusts the output of the offset voltage detecting means to zero. Due to this, in the present embodiment,
The offset voltage of the motor current detection means and the offset voltage of the control means for performing feedback control can be detected with high sensitivity by the offset voltage detection means for detecting the output voltage of the control means, and the offset voltage detection means by the offset voltage adjustment means. It becomes possible to automatically adjust the offset of the motor drive circuit by adjusting the output of 0 to zero.

The above-described automatic offset adjusting apparatus for a motor drive circuit according to the embodiment of the present invention includes a motor current detecting means for detecting a current flowing through the motor and a control means for performing feedback control so that the detected current has a predetermined value. When,
Offset voltage detecting means for detecting the output voltage of the control means, and offset voltage for adjusting the output of the offset voltage detecting means to zero. The adjusting unit and the switch for cutting off the output of the power amplifying unit are provided. Then, the predetermined value in the control means is set to zero, and the output of the offset voltage detecting means is zero by the offset voltage adjusting means in a state where the output of the power amplifying means is shut off by the switch that shuts off the output of the power amplifying means. It is configured to make adjustments such that

According to the above configuration, the offset voltage of the motor current detection means and the offset voltage of the control means for performing feedback control can be detected with high sensitivity by the offset voltage detection means for detecting the output voltage of the control means. It becomes possible to automatically adjust the offset of the motor drive circuit by adjusting the output of the offset voltage detecting means to zero by the offset voltage adjusting means. Therefore, according to the present invention, it is possible to obtain the offset automatic adjustment device for the motor drive circuit, which can reduce the adjustment time and reduce the cost.

Also, in the automatic offset adjusting apparatus for the motor drive circuit according to the embodiment of the present invention, when the predetermined value in the control means is zero, the output of the power amplification means is shut off by the switch that shuts off the output of the power amplification means. Then, the offset voltage adjusting means is configured to adjust the output of the offset voltage detecting means to zero.

According to the above configuration, the offset voltage of the motor current detection means and the offset voltage of the control means for performing feedback control can be detected with high sensitivity by the offset voltage detection means for detecting the output voltage of the control means. It becomes possible to automatically adjust the offset of the motor drive circuit by adjusting the output of the offset voltage detecting means to zero by the offset voltage adjusting means. Therefore, according to the present invention, a more accurate automatic offset adjusting device for a motor drive circuit can be obtained by automatically detecting and adjusting a change in offset due to temperature, aging, and the like.

Further, the motor to be driven in the automatic offset adjusting apparatus for the motor drive circuit according to the embodiment of the present invention may be a linear motor.

According to the above structure, even in the drive circuit of the linear motor which is driven by a large amount of power, when the predetermined value in the control means is zero, the switch for cutting off the output of the power amplification means is used to switch the power amplification means. With the output cut off, the offset voltage adjusting means adjusts the output of the offset voltage detecting means to zero. With this configuration, the offset voltage of the motor current detection unit and the offset voltage of the control unit that performs feedback control can be detected with high sensitivity by the offset voltage detection unit that detects the output voltage of the control unit. It becomes possible to automatically adjust the offset of the motor drive circuit by adjusting the output of the offset voltage detecting means to zero.

[0050]

As described above, according to the present invention,
An automatic offset adjusting device for a motor drive circuit that can reduce the adjustment time and cost can be obtained. Further, according to the present invention, it is possible to obtain a more accurate offset automatic adjustment device for a motor drive circuit by adjusting changes in offset due to temperature, aging, and the like. Further, according to the present invention, it is possible to apply to any configuration of the motor and the power amplification unit, regardless of the type of the motor, the required output torque or force, and the configuration of the power amplification unit of the motor drive circuit. It is possible to provide an automatic offset adjusting device for a motor drive circuit having high performance.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of an automatic offset adjustment device for a motor drive circuit according to an embodiment of the present invention.

FIG. 2 is a diagram in which an offset voltage generated in each circuit is added to the schematic configuration diagram of the offset automatic adjustment device for the motor drive circuit shown in FIG.

FIG. 3 is a diagram showing a configuration example of a power amplification unit of a motor drive circuit according to an embodiment of the present invention.

FIG. 4 is a diagram showing another configuration example of the power amplification unit of the motor drive circuit according to the embodiment of the present invention.

FIG. 5 is a diagram showing a configuration example of a control unit of the motor drive circuit according to the embodiment of the present invention.

6A and 6B are diagrams illustrating a two-phase linear motor according to an embodiment of the present invention, FIG. 6A is a configuration example of a two-phase linear motor, and FIG. 6B is an electrical equivalent of the two-phase linear motor. Each circuit is shown.

FIG. 7 is a schematic configuration diagram showing an example of a motor drive circuit according to a conventional example.

[Explanation of symbols]

10, 10A, 710: control unit, 12: proportional gain, 1
4: integrator, 20, 20A, 720: power amplifier, 2
2: power supply for power amplification section, 25: oscillation section, 26: comparison section,
27: PWM power amplification unit, 28, 80, 80A: switch, 29: filter unit, 30, 730: detection resistor, 4
0, 740: amplifier, 50: A / D conversion, 60: digital calculator, 70: D / A conversion, 100: drive circuit, 6
00: motor, 610: permanent magnet, 620: yoke, 6
30: α phase winding, 640: β phase winding, 660: equivalent resistance, 670: equivalent inductor, 700: conventional drive circuit, 750: adjustment voltage.

Claims (4)

[Claims] 1. An automatic offset adjusting device for a motor drive circuit for driving a motor, wherein the motor drive circuit detects a motor current detecting means for detecting a current flowing through the motor, and a current detected by the motor current detecting means. An offset voltage detection unit for detecting the output voltage of the control unit, and an offset voltage detection unit, which include a control unit that performs feedback control to obtain a predetermined value, and a power amplification unit that power-amplifies a signal from the control unit. An automatic offset adjusting device for a motor drive circuit, comprising: an offset voltage adjusting means for adjusting the output of the means; and a switch provided between the control means and the motor current detecting means. 2. The automatic offset adjusting device of the motor drive circuit adjusts the output of the offset voltage detecting means by the offset voltage adjusting means in a state where the output of the power amplifying means is shut off by the switch. The automatic offset adjusting device for a motor drive circuit according to claim 1. 3. An automatic offset adjustment device for the motor drive circuit is operative to switch at least one of a power supply section, an oscillating section, and an integrating section to be driven in conjunction with opening and closing of the switch. 3. The automatic offset adjusting device for a motor drive circuit according to claim 1, wherein the offset of the motor drive circuit is automatically adjusted by inputting a / OFF signal. 4. The automatic offset adjusting device for a motor drive circuit according to claim 1, wherein the motor is a linear motor.