JPH04101692A - Dc brushless motor controller - Google Patents

Abstract

PURPOSE:To realize constant output field weakening control by previously correcting the decrement of amplitude and the phase lag corresponding to the rotational speed based on a command value. CONSTITUTION:A command current operating means 11 calculates a command current i1* based on a torque command T* and a speed operating means 12 calculates a rotational speed omega based on a position signal of a motor. Reciprocals of motor control characteristics i1/i1* are previously stored as torque command amplitude correction coefficients Ki, in the form of table data for each rotational speed range, in a amplitude correction coefficient data table 13 whereas phase lags thetad are previously stored, in the form of table data for each rotational speed range, in a phase correction data table 14. When the speed operating means 12 calculates the rotational speed omega of motor, the rotational speed is inputted to the amplitude correction coefficient data table 13 and the phase correction data table 14 and then a correction coefficient Ki and a correction amount thetad are read out.

Description

DETAILED DESCRIPTION OF THE INVENTION A. Field of Industrial Application The present invention relates to a control device for a DC brushless motor, and particularly to a control device for a DC brushless motor having a permanent magnet field.

B1 Summary of the Invention The present invention provides a control device for a DC brushless motor having a permanent magnet field, in which a control unit includes a speed calculation means for calculating a rotation speed from a position signal of the motor, and a data table corresponding to the rotation speed. By providing a field weakening control means and a processing means that corrects the amplitude and phase of the torque command using their outputs, it is possible to prevent the controllability of PI calculation from deteriorating due to the influence of motor induced voltage in a high rotation speed region, It provides technology that enables constant output control of field weakening, similar to DC machines and induction machines.

C3 Conventional technology Traditionally, DC brushless motors use a permanent magnet field in the rotor, detect the magnetic pole position of the rotor, and use the position signal to ensure that the stator's primary current and magnetic flux are always orthogonal. The primary current is controlled to That is, by controlling the motor current and motor induced voltage so that they are in the same phase, characteristics similar to those of a DC machine are realized.

FIG. 4 is a circuit configuration diagram showing an example of a control device for a DC brushless motor. As shown in the figure, the motor control device includes a three-phase inverter 42 that controls the rotational speed of a DC brushless motor 41 using three-phase current, an absolute encoder 43 that detects the magnetic pole position of the motor 41, and a motor position signal. .

The three-phase inverter 42 includes an inverter gate 45 and a gate drive unit 46 that drives the gate 45 according to the gate signal, and the three-phase inverter 42 includes a control unit 44 that issues gate signals based on motor current and torque commands. Ia, Ib and Ic are output to the motor 41,
A current sensor 47 is provided for the current 1a Ic, and the detected motor current is fed back to the control section 44. As described above, the control unit 44 outputs a gate signal based on the motor current, the motor position signal, and the torque command.

FIG. 5 is a configuration diagram showing an example of the control section 44 of the above device. In the figure, 50 is a CPU of the control section.

51 is a D/A converter, 52 is a phase calculator, 53 is an adder, 54 is a trigonometric function data table, 55 is a programmable timer, 56 is a PI amplifier, 57 is a triangular wave oscillator, and 58 is a comparator. In the figure, signals are transmitted by the tental data bus in the portions indicated by double lines.

A torque command is input to the CPU 50, and a motor position signal φ from an absolute encoder 43 shown in FIG. 4 is also taken in via a programmable timer 55. The CPU 50 compares the motor position signal φ with the torque command and outputs a command current ■1 and its phase signal θ. The phase signal θ and the motor position signal φ are digitally calculated by phase calculators 52a and 52b, respectively, and then added by an adder 53, and then stored in a trigonometric function data table 54.
It is output as a two-phase sine value. On the other hand, the command current (1) is multiplied by the two-phase sine wave value via the D/A converters 51a, 51b, and 51c, and then multiplied by the detected currents Ia and Ic by the current sensor 47 shown in FIG. PI amplifiers 56a and 56b integrate the respective signals.

Three phases are obtained from the outputs Va and Vc of the PI amplifiers 56a and 56b, and vb obtained by adding their negative values, and these three
The gate signal is obtained by comparing the phase output with the triangular wave Tri from the triangular wave oscillator 57 by the comparator 58.

D1 Problems to be Solved by the Invention However, the conventional motor control device has the following problems.

As mentioned above, DC brushless motors use the rotational position signal detected by the absolute encoder to ensure that the current flowing through the motor is orthogonal to the magnetic flux, or in other words, that the motor current and motor induced voltage are in phase. Is it possible to obtain the same characteristics as a DC machine by controlling the
This current control uses a control section based on PI calculation and PWM control approximating a sine wave to reduce harmonic loss.
When using PI calculation, controllability deteriorates due to the influence of motor induced voltage in a region where the rotational speed is high, and the actual current amplitude decreases with respect to the current command. FIG. 6 is a characteristic diagram showing the relationship between rotation speed, current amplitude, and phase, and shows the amplitude ratio 1 of current command value i and actual current detection value 11 with respect to rotation speed (%).
1/11'' and phase delay θd. As is clear from the figure, the current control characteristics deteriorate as the rotation speed increases.

In addition, in a DC brushless motor with a permanent magnet field, the field is fixed, so the induced voltage of the motor increases in proportion to the increase in rotation speed, and unlike DC machines and induction machines, the field weakens and produces a constant output. It was impossible to control and difficult to apply at high speeds.

The present invention was created in view of these problems, and
A control device for DC brush 1-nos motors that prevents the controllability of PI calculation from deteriorating due to the influence of motor induced voltage in high rotational speed regions and enables constant output control of field weakening similar to DC machines and induction machines. is intended to provide.

E8 Means for Solving the Problems The means for solving the above problems in the present invention include a three-phase inverter that current controls the rotational speed of a DC brushless motor, a gate drive unit that drives each gate of the inverter, and a motor. A motor control device includes a control section that issues a gate signal to the drive unit based on a position signal, motor current, and torque command, and a speed calculation means that calculates a rotation speed from the motor position signal, and a phase calculation means that corresponds to the rotation speed. A control device for a DC brushless motor in which a control unit includes a phase correction data table that outputs a delay and an amplitude correction coefficient data table that outputs an amplitude correction coefficient of a torque command corresponding to a rotational speed, and similarly, The control section includes a speed calculation means that calculates the rotational speed from a motor position signal, a field-weakening control means that outputs a current component in a field-weakening state according to the rotational speed, and a field-weakening control means that outputs a current component in a field-weakening state according to the rotational speed. It is also preferable to include current amplitude processing means and current phase processing means for correcting the phase.

F3 action The present invention focuses on the fact that the deterioration of the characteristics of the current control section corresponds to the rotation speed, and corrects the decrease in amplitude and the delay in phase according to the rotation speed using a command value in advance. Based on. That is, the amplitude of the current command is set to be large in consideration of the decrease, and the phase is set to be advanced. Corrections for each rotation speed can be made by approximating pre-measured characteristics with a straight line or an nth-order function, or by creating a data table of correction amounts for each rotation speed. realizable.

Further, by providing a field weakening control means, when the speed exceeds the rating, the current component of a predetermined phase is set to a negative value to suppress an increase in motor voltage. Although the current amplitude and phase at this time can be calculated theoretically, this can be easily realized by creating sine wave data obtained by adding the phase signal and the position signal in a data table in the ROM.

G. Embodiments Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a configuration diagram of an embodiment of the present invention.

In the figure, 10 is a CPU of the control section, command current calculation means 11. Speed calculation means 12. It includes an amplitude correction coefficient data table 13 and a phase correction data table 14.

The CPU10 corresponds to the CPU50 of the control unit shown in FIG. 5, receives a position signal via a programmable timer 55, outputs a command current signal 1 to the D/A converter 51a, and outputs a command current signal 1 to the D/A converter 51a. The phase signal is output to.

The command current calculation means J1 calculates the command current 11'' from the torque command T'', and the speed calculation means 12 calculates the rotational speed ω from the motor position signal. The amplitude correction coefficient data table 13 contains the motor control characteristics i, /
The reciprocal of i,'' is set as 1 for the torque command amplitude correction coefficient, and table data is stored in advance for each rotation speed range. Convert it into data and store it in advance.

Here, when the speed calculation means 12 calculates the rotational speed ω of the motor, the value ω is input to both the amplitude correction coefficient data table 13 and the phase correction data table 14, and the
The positive coefficient is 1 and the correction amount θd is read out. As a result, the amplitude of the current command output from the CPU I O is: i, =i, ゞXKi = (T''/Kt) XKi - (1)
becomes. However, T″ is a torque command, and Kt is an l·lux constant.

The phase correction amount θd is added to the signal φ detected from the absolute encoder, and the two-phase sine wave value corresponding to the phase signal φ' is output from the trigonometric function data table 54 shown in FIG. become.

These command currents 1a and ic are, as already mentioned,
A sine wave approximation PWM with triangular wave comparison is used for inverter control. The amplitude of the actual current decreases according to the current control characteristics, and the phase is delayed by θd, so 1b=i]'' 5in(φ-2/3π) −(3
)jc=il'' 5in (φ+2/3π) According to the above principle and configuration, even in the high rotational speed region, the amplitude will be the same as the command value, and the phase will be controlled to match the rotor position (induced voltage phase). It will be done.

The output of the motor always becomes the torque according to the command value, achieving linear torque control over the entire range.

FIG. 2 is a configuration diagram showing another embodiment of the present invention.

In the figure, reference numeral 20 denotes a CPU of the control section, and command current calculation means 21. Speed calculation means 222 field weakening control means 23. Current amplitude correction means 24. A current phase correction means 25 is provided.

The CPU 20 corresponds to the CPU 50 of the control section shown in FIG. 5, receives a position signal via the programmable timer 55, outputs a command current signal 1 to the D/A converter 51a, and outputs a command current signal 1 to the D/A converter 51a. The phase signal is output to.

The command current calculation means 21 calculates the command current IQ from the torque command T-, and the speed calculation means 22 calculates the rotational speed ω from the motor position signal. Each of these means has the same function as in the first embodiment.

By the way, in the equations of torque and voltage of a DC brushless motor, when the d-q axes are set as shown in FIG. 3, the following is the induced voltage. Further, the winding current 11 is T=K t
A i q (k qm) −(
5). However, R+Lp: transient impedance of the armature, Δ: number of magnetic flux linkages caused by the field of the armature winding, n: number of pole pairs, ω: rotational angular velocity, Kt: torque constant. Here, considering a steady state with a relatively high rotational speed, R(nωmL, p=0, so Vd= -nω
L iq −(6)Vq=e o
+nωL i d −(7)Vl =J
Vd2+Vq2... (8) is derived from the above equation (4). However, eo=nωΔ.

Normally, tr is controlled to i d = 0, or (7)
By controlling 1d using equations and equations (8), the terminal voltage V
It is clear that 1 can be controlled.

In this case, the torque does not depend on 1d according to equation (5). When the coordinates are exchanged into three-phase coordinates, i a=i lOs
in (φ10) ib=il・5in (φ10-2/
3π) −(10)ic=il−sin(φ+θ+
2/3π), the torque can be controlled by iq, and id
When is set to a negative value, field weakening control that reduces 1 becomes possible.

In this embodiment, the detected value ω of the speed calculating means 22 is input to the field weakening control means 23, and 1d is set to zero during normal operation within the rated speed, and id is set to a negative value when the speed exceeds the rated speed. By doing so, field weakening control is performed to suppress the increase in motor voltage. At this time, the finger-\i lightning current amplitude and phase output by the command current calculation means 21 are as follows:
Current amplitude correction means 24 and seven current levels (■ correction means 25 (
9) and output from the CPU 20 as an amplitude signal 11 and a phase signal θ. This phase signal θ and the signal φ detected from the absolute encoder are added, and a two-phase sine wave corresponding to the phase signal φ' is output from the trigonometric function data table 54 shown in FIG. The calculation of equation (10) is performed by the D/A converter, as in the first embodiment and the conventional example.

As described above, in this embodiment, by performing field weakening control, the induced voltage of the motor is suppressed from increasing, and operation at a speed higher than the rated speed is enabled.

■1 Effect of the Invention As described above, the present invention prevents the controllability of PI calculation from deteriorating due to the influence of motor induced voltage in the high rotational speed region, and reduces the field weakening in the same way as DC motors and induction motors. A DC brushless motor control device capable of constant magnetic output control can be provided.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of one embodiment of the present invention, FIG. 2 is a block diagram of another embodiment of the present invention, and FIG. 3 is an explanatory diagram of another embodiment.
FIG. 4 is a block diagram of a general motor control device, FIG. 5 is a block diagram of a control section, and FIG. 6 is a characteristic diagram of motor control. 1.0, 20.50... CPU, 11.21-... Command current calculation means, 1.2.22... Speed djI calculation means, 13... Amplitude j:Ij positive coefficient cheetah table, 14
...Phase correction data table, 23.. Field weakening control means, 24.. Current amplitude correction means, 25. Current phase correction means, 41.. Motor, 42.-3 phase inverter, 43.
- Absolute encoder, 44... Control section, 45
- Inverter gate, 46 gate drive unit, 17... - current sensor, 5I... D/A converter, 52... phase calculator, 53... adder, 54...
- Trigonometric function data table, 55... Programmable timer 56... PI amplifier, 57... Triangular wave oscillator. λDCPU Figure 1 Configuration diagram of an embodiment of the present invention

Claims (2)

[Claims] (1) A three-phase inverter that current controls the rotational speed of a DC brushless motor, a gate drive unit that drives each gate of the inverter, and a control unit that issues gate signals to the drive unit based on motor position signals, motor current, and torque commands. A motor control device comprising: a speed calculation means for calculating the rotational speed from a motor position signal; a phase correction data table for outputting a phase delay corresponding to the rotational speed; A control device for a DC brushless motor, wherein the control unit includes an amplitude correction coefficient data table that outputs an amplitude correction coefficient. (2) A three-phase inverter that current controls the rotational speed of the DC brushless motor, a gate drive unit that drives each gate of the inverter, and a control unit that issues gate signals to the drive unit based on motor position signals, motor current, and torque commands. A motor control device comprising: a speed calculation means for calculating the rotational speed from a motor position signal; a field-weakening control means for outputting a current component in a field-weakening state according to the rotational speed; 1. A control device for a DC brushless motor, wherein the control unit includes a current amplitude processing means and a current phase processing means for correcting the amplitude and phase of a command.