JP3944354B2 - Motor control device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a motor control device that is used in a spindle drive motor of a machine tool and the like and uses a phase modulation resolver for detecting the speed and position of the spindle drive motor.
[0002]
[Prior art]
A conventional motor control apparatus using a phase modulation resolver for motor speed detection and position detection will be described with reference to the drawings. As is well known, for example, when a two-phase AC signal that is 90 degrees out of phase is applied as an excitation signal to a set of orthogonal stator windings of a resolver, the resolver rotor winding has a rotation angle equal to the rotation angle. An AC feedback signal that changes phase can be obtained.
[0003]
As a first conventional example, FIG. 2 shows a block diagram of a motor control device when the frequency of the excitation signal is kept constant during motor control. In FIG. 2, a resolver 11 includes a stator winding 9 and a rotor winding 10. The excitation signal generator 3 receives a constant periodic reference signal output from the counter means 1 and generates a two-phase sine wave excitation signal that is 90 degrees out of phase with each other. This is an excitation signal generating means for outputting to the stator winding 9. The rectangular wave conversion circuit 8 is a means for processing the feedback signal output from the rotor winding 10 of the resolver into a rectangular wave after processing by the differential amplifier 7. The latch circuit 4 is means for latching the output value of the counter means 1 by the rising edge of the feedback signal converted into the rectangular wave. The latched count value is processed by the CPU 12 to calculate the phase difference.
[0004]
The phase difference is calculated as follows. In FIG. 2, the period T of the excitation signal of the resolver can be expressed as Equation (1), where Tclk is the period of the reference clock of the counter means.
[Expression 1]
T = 2 ^ n × Tclk (1)
In Equation (1), 2 ^ n represents 2 to the nth power, and n represents a valid bit of the counter.
[0005]
Next, FIG. 3 shows the excitation signal, the feedback signal, and the rectangular feedback signal. 3A shows the output value of the counter means 1, and FIG. 3B shows the excitation signal. (C) shows the feedback signal, and (d) shows a signal obtained by making the feedback signal (c) rectangular. Here, the output value (a) of the counter means 1 is latched at the rising edge of the feedback signal (d) converted into the rectangular wave. From the latched count value N, the CPU 12 in FIG. 2 calculates the phase difference θ between the excitation signal and the feedback signal according to the equation (2).
[Expression 2]
θ = 360 ° × N / 2 ^ n (2)
Here, it can be seen from Equation (2) that n indicates the phase resolution, and the resolution increases as n increases, but at the same time, the excitation period becomes longer than in Equation (1).
[0006]
Next, as a second conventional example, FIG. 5 shows a block diagram of a motor control device when the frequency of the excitation signal is varied in accordance with the detected speed value of the motor. The same components as those shown in FIG. 2 are denoted by the same reference numerals, and the description thereof will be omitted because it is redundant. In FIG. 5, an excitation signal generator 3 is an excitation signal generating unit that varies the frequency of the excitation signal based on the speed detection signal output from the speed detector 13. Further, the excitation signal generating means 3 outputs a ref signal representing the excitation signal frequency to the angle detector 14. For example, 2 ^ n in Expression (1) is output as a ref signal. The angle detector 14 calculates the phase difference θ between the excitation signal and the feedback signal according to the mathematical expression (2) based on the ref signal from the excitation signal generation circuit 3.
[0007]
[Problems to be solved by the invention]
In these conventional motor control devices described above, the phase of the rotor of the motor can be detected using a phase modulation type resolver, whereby the speed and position of the motor can be detected. However, in the motor controller of the first conventional example described above, the reference clock Tclk of the counter means 1 is constant and the frequency 1 / T of the excitation signal is constant, so that the detection frequency, that is, the phase of the motor can be detected. There is a problem that the upper limit of the rotation speed and the detection resolution are fixed. That is, in order to detect the motor phase up to the high-speed rotation region, it is necessary to increase the frequency 1 / T of the excitation signal. That is, it is necessary to reduce n in Equation (1). However, if n is reduced, 2 ^ n in Equation (2), which is the full count value of the counter means when calculating the phase difference, is reduced, so that the detection resolution is lowered. . In order to increase the detection resolution in the low-speed rotation region, it is necessary to increase n, but to increase n, it is necessary to decrease the frequency 1 / T of the excitation signal, and if the frequency of the excitation signal is decreased The phase detection range in the high-speed rotation region is narrowed.
[0008]
As an application example, in a spindle motor used in a machine tool such as a lathe, the motor control device of the first conventional example is often used for motor phase detection. At this time, when the spindle is controlled at a high speed and at a very low speed, that is, when the motor position is controlled and the spindle angle is varied at a low speed, the phase of the spindle motor is detected in the high-speed rotation region. However, there is a problem of increasing the phase detection resolution in the low-speed rotation region.
[0009]
Further, when the motor control device of the second conventional example described above adopts a method of varying the excitation frequency shown in FIG. 5 according to the detected motor speed, the above problem seems to be solved. Problem arises. That is, when the frequency of the excitation signal is varied, the excitation signal is distorted when the frequency is varied. Further, since the phases of the excitation signal and the feedback signal are not the same phase, continuity in the phase difference between the excitation signal and the feedback signal is lost when the excitation frequency is varied. Therefore, when the excitation frequency is varied during the control of the motor, there is a problem that an error in the phase detection value becomes large when the excitation frequency is varied. Further, the method of varying the excitation frequency according to the detected motor speed is more expensive than the method of not varying the excitation frequency, and causes a problem in terms of cost in constructing the motor control system.
[0010]
The object of the present invention is to solve the above-mentioned problems and problems, and to increase the phase detection resolution when controlling the motor in the low-speed rotation region, and to increase the excitation frequency when controlling the motor in the high-speed rotation region. An object of the present invention is to provide an inexpensive and inexpensive motor control device.
[0011]
[Means for Solving the Problems]
The motor control apparatus according to the present invention in order to achieve the above object, the motor control device using a phase modulation type resolver for detecting the speed and position of the motor, a plurality of periodic reference signal of the excitation signal for exciting the resolver a counter means for generating and outputting, in response to the speed command to the motor, when the speed command is lower selects a low excitation frequency reference periodic signal when the speed command is higher the more the high excitation frequency periodic reference signal An excitation cycle selection means for selecting from among the cycle reference signals , and outputting as an excitation cycle reference signal , an excitation signal generation means for generating an excitation signal for the resolver by receiving an output signal of the excitation cycle selection means, and a resolver characterized by comprising a latch means for latching a count value of said counter by a feedback signal.
The motor control device according to the present invention is a counter that generates and outputs a plurality of period reference signals of excitation signals for exciting the resolver in a motor control device using a phase modulation resolver that detects the speed and position of the motor. Means for selecting a period reference signal for exciting the resolver from the plurality of period reference signals according to a motor winding command, and outputting the selected period reference signal as an excitation period reference signal. An excitation signal generating unit that receives an output signal and generates an excitation signal of the resolver, and a latch unit that latches a count value of the counter by a feedback signal of the resolver.
[0012]
In this way engagement makes the chromophore at the distal end over motor controller of the present invention, the counter means outputs a plurality of periodic reference signals, the excitation period selection means selects one of the periodic reference signal from the plurality of periodic reference signal excitation since a configuration capable of outputting a periodic reference signal, the speed command also depending on the winding command motors, switches the excitation frequency of the resolver, a high phase detection resolution when controlling the motor in the low speed region, When the motor is controlled in the high-speed rotation region, by increasing the excitation frequency, it becomes possible to increase the phase resolution of the motor and expand the phase detection range of the motor according to the control range of the motor.
[0013]
In addition, since the excitation frequency is switched in advance of motor control in accordance with the speed command, motor control mode, winding command, etc., phase detection without changing the excitation frequency during motor speed control is possible. The error does not affect the control.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings. FIG. 1 is a block diagram of an embodiment of a motor control device according to the present invention. The same components as those of the conventional motor control device shown in FIG. 2 are denoted by the same reference numerals, and the description thereof will be omitted because it is redundant. In FIG. 1, the counter means 1 outputs a plurality of period reference signals. The excitation cycle selection means 2 selects one cycle reference signal from the plurality of cycle reference signals before control in accordance with the speed command of the motor to be controlled, and outputs the excitation cycle reference signal. If the speed command ω * is low, the excitation frequency is lowered and the period reference signal is selected so that the count value 2 ^ n per period of the excitation signal increases. When the speed command ω * is high, the period reference signal is selected so that the excitation frequency is increased and the count value 2 ^ n per period of the excitation signal is decreased. The excitation signal generating means 3 generates an excitation signal for the resolver 11 in accordance with the excitation cycle reference signal output based on the period reference signal selected by the excitation cycle selection means 2 in accordance with the speed command ω *. The resolver 11 excited by the excitation signal outputs a feedback signal corresponding to the phase of the motor. The feedback signal is converted into a rectangular wave by the rectangular wave conversion circuit 9 and the output of the counter 1 is latched by the latch circuit 4 at the rising edge of the feedback signal converted into the rectangular wave. Thereby, the speed and position of the motor are detected via the CPU 12, and the motor is controlled.
[0015]
FIG. 4 shows an operation example of the excitation cycle selection means 2. When the speed command ω * is in the range of 0 to ω1, the excitation cycle selection means 2 outputs the excitation cycle reference signal whose excitation frequency is f1. Further, in the region where the speed command is ω1 to ω2 and the region where ω2 is greater than or equal to ω2, the excitation cycle selection means 2 outputs the excitation cycle reference signal whose excitation frequencies are f2 and f3.
[0016]
Further, the excitation cycle reference signal is output according to the control mode signal instead of the speed command ω *. That is, as shown in FIG. 4, in the high precision control mode, the excitation cycle selection means 2 outputs the excitation cycle reference signal with the excitation frequency f1, and in the high speed control mode, the excitation cycle selection means 2 has the excitation frequency f3. The excitation cycle reference signal is output.
[0017]
Further, in the case of selecting the excitation frequency according to the winding selection command using the winding switching motor, when the winding command for selecting the low-speed winding is given, the excitation cycle selection means 2 has the excitation frequency selected. The excitation cycle reference signal f1 is output. When a winding command for selecting a high-speed winding is given, the excitation cycle selection means 2 outputs the excitation cycle reference signal with an excitation frequency of f2.
[0018]
【The invention's effect】
Thus, in the motor control apparatus for a motor according to the present invention, the counter means outputs a plurality of cycle reference signals, and the excitation cycle selection means responds to the speed command, the motor control mode, or the motor winding command. Since one cycle reference signal is selected from the plurality of cycle reference signals and an excitation cycle reference signal is output, the excitation signal generating means generates an excitation signal for exciting the resolver. When the excitation frequency of the resolver is switched and the motor is controlled in the low-speed rotation region, the phase detection resolution is high, and when the motor is controlled in the high-speed rotation region, the excitation frequency is increased so that The phase resolution of the motor can be increased and the phase detection range of the motor can be expanded.
[0019]
In addition, since the excitation frequency is switched in advance of motor control in accordance with the speed command, motor control mode, winding command, etc., phase detection without changing the excitation frequency during motor speed control is possible. The error does not affect the control.
[0020]
According to the motor control device of the present invention, since the frequency of the excitation signal is made variable in accordance with the motor speed command or control mode or the motor winding command, the resolution in the low speed range, which has been impossible in the past, is improved. Thus, a system capable of speeding up the phase detection range can be constructed at low cost.
[Brief description of the drawings]
FIG. 1 is a block diagram of an embodiment of a motor control device according to the present invention.
FIG. 2 is a block diagram of a motor controller of a first conventional example.
FIG. 3 is a waveform diagram of each signal of the motor control device shown in FIGS. 1 and 2;
FIG. 4 is an example of an excitation frequency selection operation in an embodiment of the motor control device according to the present invention.
FIG. 5 is a block diagram of a motor controller of a second conventional example.
[Explanation of symbols]
2 ^ n count value, θ phase difference, Tclk reference clock, T cycle, ω speed command, 1 counter means, 2 excitation cycle selection means, 3 excitation signal generation means, 4 latch means, 5, 6 buffer, 7 differential amplifier , 8 Rectangular wave conversion circuit, 9 stator winding, 10 rotor winding, 11 resolver, 12 CPU, 13 speed detector, 14 angle detector.

Claims (2)

The motor control device using a phase modulation type resolver for detecting the speed and position of the motor, a counter means for the periodic reference signal generates plural output of the excitation signal for exciting the resolver, according to the speed command to the motor When the speed command is low, a reference period signal with a low excitation frequency is selected. When the speed command is high, a period reference signal with a high excitation frequency is selected from the plurality of period reference signals and output as an excitation period reference signal. An excitation cycle selection unit; an excitation signal generation unit that receives an output signal of the excitation cycle selection unit and generates an excitation signal of the resolver; a latch unit that latches a count value of the counter by a feedback signal of the resolver; A motor control device comprising: The motor control device using a phase modulation type resolver for detecting the speed and position of the motor, a counter means for the periodic reference signal generates plural output of the excitation signal for exciting the resolver, the windings command motors depending periodic reference signal for exciting the resolver by Ri selection among said plurality of periodic reference signal and an excitation cycle selection means for outputting the excitation cycle reference signal, and inputs the output signal of the excitation cycle selection means, said A motor control device comprising: excitation signal generating means for generating an excitation signal for a resolver; and latch means for latching a count value of the counter by a feedback signal of the resolver .

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