JPH02241384A - Controller for motor - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Industrial Field of Application] The present invention eliminates nonlinearity caused by a dead zone including a motor that performs position control, its driver section, and the motor's load section, thereby achieving good motor control. It is something.

[Summary of the Invention] The present invention provides a motor control device that performs position control, etc., in which the drive output of the motor is gradually reduced before using the motor, including the motor, its driver section, and its load section. When the motor reaches a certain rotation speed, the drive output at that time is held as a bias value, and the bias value is added to the drive output when the motor is in use to control the motor. This eliminates nonlinearity caused by dead zones including the driver section and load section, making it possible to obtain good motor control characteristics.

[Prior art] Conventionally, motors that perform position control, such as motors that drive robots, etc., have used switch circuits that can be energized in both forward and reverse rotation directions, and the energization has been controlled using PWM (pulse width modulation).
Control and control its rotation.

FIG. 4 is a configuration diagram of a conventional motor control device using PWM switch control. 102 is a switch circuit, 103 is a motor, and 104 is a current feedback circuit. The PWM generating section 101 includes a computing unit 101a that converts an analog position command signal into an analog signal em' for PWM duty control, a triangular wave generating circuit 101b that generates a reference triangular wave signal, and a triangular wave generating circuit 101b that converts the triangular wave signal into an analog signal em'. The comparator 101c compares the signals and outputs a PWM signal. Switch circuit 102
are four switching elements Q, such as power transistors,
Q, , Q, , Q, are connected in a bridge configuration between the power supply VCC)1 and the ground, and the motor 103 is connected between the switching element connection points in the middle.

One diagonally positioned set of switch elements Q8. Q4 controls energization in the forward rotational direction by its conduction, and the switch elements Q, , Q3 of the other diagonally positioned pair control energization in the reverse rotational direction by their conduction. The switch circuit +02 has a logic circuit 102a, and from the PWM signal output from the comparator 101c, the PWM signals are in an inverse relationship with each other.
Create a W M + signal and a PW M2 signal. This PWM signal is output to switch elements Q, Q, which instruct energization in the forward rotation direction, and the PWM signal is output to switch elements Q*, Q- which instruct energization in the reverse rotation direction. PWM signal and PWM signal are the same.
Since there is a relationship between the PWM signal and its inversion, the motor 103
The motor is always energized alternately in both rotational directions, and acceleration, deceleration, and stopping of the motor are controlled depending on the magnitude of the duty. The current feedback circuit 104 detects the current flowing through the current detection resistors R, , R, inserted in both the current flowing directions of the switch circuit 102, and outputs the current flowing through the arithmetic unit 1.
Current feedback is applied to the input side of the position command signal of 01a.

In the conventional example described above, the computing unit 101a outputs 0■, which is the center of symmetry of the triangular waveform in the triangular wave signal, as the analog signal em' in response to the stop position command signal, and the PWM signal output from the comparator 1olc. Set the duty to 50%. Therefore, both the PWM signal and the PWM signal have a signal waveform with a duty (offset duty) of 50%. In other words, electricity is alternately applied equally in the forward and reverse directions to bring the device into a stopped state. Next, during acceleration in the positive direction, a negative potential is output from the calculation "lt-101a" as the analog signal es', and the PWM signal output from the comparator 101c has a duty of 50.
% or more. Therefore, the PWM signal has a duty of 5.
0% or more, and the duty of the PWM signal becomes 50% or less. In other words, if more current is applied in the forward rotation direction, 1. It rotates in the forward direction while relatively reducing the amount of current flowing in the opposite direction. Also, during acceleration in the reverse direction, the analog signal ea'
By outputting a positive potential as , the current is increased in the reverse rotation direction, contrary to the case of forward acceleration, and the current is relatively reduced in the forward direction to accelerate in the reverse direction.

FIG. 5 shows a control characteristic diagram of the motor in the conventional example. The horizontal axis is the PWM duty X [
%], and the vertical axis is the effective torque. As can be seen from this characteristic diagram, the driver section of the motor 103 consisting of the motor 103 and the switch circuit 102 shown in FIG. exists. Because of this dead zone, PWM duty X becomes X<X as shown in (a). In the case of , the effective torque that actually moves the motor is 0, the motor does not rotate, and as shown in (b), the motor starts rotating only when X>XO, and from this point on it is possible to control the motor. Become. In the above-mentioned conventional technology, by constantly applying PWM duty of 50% as an offset duty, including when stopped, the above-mentioned dead zone appears smaller, and by applying the above-mentioned current feedback, nonlinearity due to the dead zone can be reduced. I was only compensated.

[Problems to be Solved by the Invention] However, the conventional motor control device described above has the following problems.

(1) The dead zone including the motor and its driver section is the P required to escape the dead zone in the characteristic diagram in Figure 2.
WM Duty X. If h<x o≦50%, it appears to disappear, but XO is not necessarily such a value, and when the motor load is included, this X. changes, and when we consider changes over time, xo > 5o
%, and there is a possibility that the influence of the dead zone cannot be fundamentally removed. Therefore, good motor control characteristics cannot be obtained, nonlinear vibrations occur, and many parameter adjustments are required to eliminate the nonlinear vibrations.

(2) In conventional PWM control, current continues to flow through the motor 103 alternately in the forward and reverse directions with a duty of 50%, not only during acceleration/deceleration but also when stopped, which consumes a large amount of power. The motor 103 and switch circuit 1
02 etc. has a problem with a large amount of heat generation. Further, even when acceleration/deceleration is performed in one rotational direction, current is applied to the other rotational direction, which is inefficient.

(3) When current feedback is used, the circuit around the motor becomes complicated and the number of adjustments increases.

The present invention was devised to solve the above-mentioned problems, and can eliminate nonlinearity due to dead zones including the motor, driver section, and load section, and can obtain good motor control characteristics. The purpose of the present invention is to provide a motor control device.

[Means for Solving the Problems] The configuration of the motor control device of the present invention that achieves the above object is as follows: Before using the motor, the motor, the driver section of the motor, and the load section of the motor are included in advance. means for gradually increasing the drive output for the motor at predetermined time intervals; means for detecting the rotation speed of the motor within the predetermined time; and means for detecting the rotation speed of the motor within the predetermined time period; The present invention is characterized in that it includes a determining means that uses the drive output as a bias value, and a means that adds the bias value to the drive output when the motor is used.

[Operation] Before using the motor, the present invention gradually increases the drive output of the motor, including the motor, its driver section, and its load section, and when the motor reaches a certain rotation speed, The drive output at that time is held as a bias value, and the bias value is added to the drive output when the motor is in use to control the motor, and the dead zone including the motor, driver section, and load section is automatically detected. Remove that nonlinearity.

[Example] Hereinafter, an example of the present invention will be described in detail based on the drawings.

FIG. 1 is a block diagram showing the configuration of an embodiment of the present invention. This embodiment takes as an example a case where a servo system motor is driven by PWM control using digital processing. Although the PWM control in this embodiment can be performed by purely analog processing, it is more practical to implement it by digital processing due to fluctuations due to temperature, element variations, and other factors.

1 is a PWM generation section that generates a PWM signal; 2 is a switching logic section that switches the direction of conduction of the PWM signal; SW;
,SW,,SW3. SW is a switch element forming the switch circuit 3; 4 is a motor whose rotation is controlled by the switch circuit 3; 5 is a rotation detector (FG) for the motor 4, which is composed of an encoder etc. and also serves as servo control; 6 is a rotation detector (FG) for the motor 4; This is a bias generating means incorporating each functional means according to the present invention.

As described below, the bias generating means 6 is connected to the motor 4.
Before performing servo control, the dead zone including the motor 4, the driver section such as the switch circuit 3, and the load section (not shown) of the motor 4 is automatically detected based on the detection signal of the rotation detector 5. It has a function of determining a bias value for cancellation and adding it to control data during servo control of the motor 4. The control data is given from a servo control system (not shown), and includes a sign signal that instructs the current direction of the motor 4, and control data (absolute value) that instructs the duty of a predetermined PWM signal to generate the necessary torque. Consists of.

The PWM generator 1 includes a D/A converter 11 that converts control data to which a bias value has been added by the bias generator 6 into an analog signal e, a triangular wave generator circuit 12 that generates a reference triangular wave signal, and a triangular wave generator circuit 12 that generates a reference triangular wave signal. A comparator 13 that compares the signal with the analog signal e and creates a PWM signal.
Karasei le. In this embodiment, the duty of the PWM signal increases as the analog signal e increases.

Next, the switching logic section 2 performs two two-man-powered AND operations.
It consists of (AND) logic circuits 21 and 22, one input of each is connected to the PWM signal from the PWM generator 1, and the other input of the AND logic circuit 21 is connected to the sign signal of the control data. , and the other input on the AND logic circuit 22 side is connected to a signal obtained by inverting the sine signal by an inverter 23. The output of the AND logic circuit 21 is connected to the input terminal (SW, , SW,) of the switch circuit 3 that energizes the motor 4 in the forward rotation direction, and the output of the AND logic circuit 21 is
The output of 2 is connected to the input side (SW, , SW S ) of a switch circuit 3 that energizes the motor 4 in the reverse rotation direction.

The switch circuit 3 includes four switch elements SW1 to SW
4, the set of switch elements SW and SW t are connected in series, and the set of switch elements SW s and SW4 are connected in series between the m source Vcc and one ground, and the switch elements SW + and A motor 4 is connected between the connection point with S W t and the connection point between switch elements SW3 and SW4. For example, each switch element has a power M with good high frequency characteristics.
Using O8FETs (field effect transistors), the gate terminals of the pair of switch elements sw, , sw on one diagonal position are connected to the output of the multiple AND logic circuit 21, and The gate terminals of the sets of switch elements sw, , sw are connected to the output of the AND logic circuit 22. The set of switch elements SW, , SW, energizes the motor 4 in the forward rotation direction by the PWM signal output of the AND logic circuit 21, and the set of switch elements SW, , SW3 conducts the AND
The PWM signal output from the logic circuit 22 energizes the motor 4 in the reverse rotation direction.

The bias generating means 6 includes a counter 61 that counts rotation detection pulses of the motor 4 from the rotation detector 5 at fixed time intervals, a comparator 62 that detects when the count of the counter 61 reaches a predetermined value, and a comparator 62 that detects when the count of the counter 61 reaches a predetermined value. An incrementing means 63 that gradually increases the bias value step by step until the bias value is reached, a register 64 that holds the bias value, and the bias value of the register 64 is added to the control data (or may be subtracted depending on the polarity of the PWM section 1). arithmetic unit 65
Equipped with. The bias generating means 6 is activated before the servo start of the servo control system, and is activated when the servo control system is turned on, for example, or for bias setting in this embodiment.
Two operation modes are provided, and the operation mode is activated when servo control is temporarily interrupted and bias setting is performed according to the instruction of the operation mode.

The sign signal of the control data that instructs when setting the bias may be a value that instructs either the forward rotation side or the reverse rotation side. The functions of each part of the bias generating means 6 described above are performed by a CPU (for example, CXP801 manufactured by Sony Corporation) configured with an ASIC (Application Specification Integrated Circuit).
16, etc.), it is also possible to implement it in a form that also includes functions such as a PWM generator.

The operation of the embodiment configured as above will be described.

FIG. 2 is a flowchart showing the operation of this embodiment, and FIG. 3 is an explanatory diagram of the operation in a graph of dead zones.

In Fig. 3, the horizontal axis is the PWM signal duty X [%
], and the vertical axis shows the effective torque. In addition, the right side of the graph shows the characteristics on the forward rotation side when the switching elements SW, SW, are conductive, and the left side of the graph shows the characteristics of the switching elements SW, SW,
, sw, are shown in FIG.

First, the operation of this embodiment will be explained. Immediately before entering servo control, the PWM generator 1 on the forward rotation side (or reverse rotation side)
The incrementing means 63 gradually increases (increments) the duty of the PWM signal output from the incrementing means 63. The PWM signal whose duty has been set to a certain value by the incrementing means 63 as shown in (2) in FIG. Electricity is applied in the direction of rotation indicated by the signal. The rotation detection pulses of the rotation detector 5 are counted for a certain period of time after this energization, and it is determined whether the count value has reached a certain value. If the count value has not reached a certain value, as shown in FIGS. Again, the incrementing means 63 increases the duty step by step and energizes. In this way, the motor 4 escapes from the dead zone including the threshold level of the motor 4 and the switch circuit 3 and the load section of the motor 4 and starts rotating, and the count value of the counter 61 indicating the number of rotations reaches a certain value. If it is determined and detected, the duty x0 at that time is held and used as a bias (offset) to be added to control data in PWM control during subsequent servo control. The above is an example of the bias setting operation, and then servo control is started.

In this way, in this embodiment, the offset duty X required to escape the dead zone after the driver section and motor is
. can be automatically detected and automatically added to the control data, eliminating the apparent dead zone. The dead zone, which includes the driver section such as the motor 4 and the switch circuit 3, and the load of the motor 4, changes depending on the size of the load, the environment, changes over time, etc., so the bias setting of this embodiment should be adjusted every time just before the servo start. Alternatively, if it is performed when necessary, such as every predetermined period of time, good servo characteristics can be obtained without performing conventional current feedback.

In addition, in the above embodiment, one rotation direction (normal rotation side)
Although we have shown the case where bias setting is only performed for
The average of these values may be calculated, or the larger bias value may be adopted and used for subsequent servo control. Also,
The present invention is applicable to motor control other than PWM control. As described above, the present invention can be applied in various ways and can take various embodiments in accordance with its gist.

[Effects of the Invention] As is clear from the above description, the motor control device of the present invention provides the following effects.

(1) No power supply feedback is required, which is advantageous in terms of hardware maintenance and adjustment 2 assembly.

(2) The dead zone is automatically detected, so if the load changes,
Even if there is a change over time, good servo characteristics can be obtained.

(3) Completely digital servo that does not include analog (current feed back) can be realized.

(4) When designing a servo, it can be designed as a pure linear system, making it easier to design.

(5) Since it is no longer necessary to compensate for the dead zone by alternately applying a 50% PWM signal to the driver section in both rotational directions when the motor is stationary, power consumption can be significantly reduced.

[Brief Description of the Drawings] Fig. 1 is a block diagram showing the configuration of an embodiment of the present invention, Fig. 2 is a flowchart showing the operation of this embodiment, Fig. 3 is an operation explanatory diagram showing a dead zone as a graph, and Fig. 3 is a flowchart showing the operation of this embodiment. FIG. 4 is a configuration diagram of a conventional motor control device, and FIG. 5 is a diagram of motor control characteristics of the conventional example. 3... Switch circuit, 4... Motor, 5... Rotation detector, 6... Bias generation means, 61... Counter, 62... Comparator, 63... Increment means, 64... ...Register, 65... Arithmetic unit.

Claims (1)

[Claims] (1) means for gradually increasing the drive output to the motor at fixed time intervals, including the motor, the driver section of the motor, and the load section of the motor before using the motor; means for detecting the number of rotations within a certain period of time; means for determining the drive output as a bias value when the detected number of rotations is equal to or greater than a predetermined value; and means for adding the bias value to the drive output when the motor is in use. A motor control device comprising: means.