JPS6260489A - Controller for brushless motor - Google Patents

Abstract

PURPOSE:To improve control performance while enhancing the resolving power of the detection of a position by mounting a phase compensating circuit compensating the phase of a commutation signal. CONSTITUTION:A phase compensating circuit 13 outputs phase compensating signals Va-Vc compensating the phase of commutation signals CSa-CSc on the basis of a speed detecting signal etg and current detecting signals iao-ico. Consequently, the phase of the commutation signals is compensated collectively by the compensation of the phase of the commutation signals CSa-CSc by the phase compensating signals Va-Vc. Accordingly, the effect of various phase lags is compensated extending over the whole speed range to high speed from low speed of a brushless motor.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an improvement in a control device for a brushless motor.

(Conventional Technique #I) Brushless motors do not have brushes that wear out, have no commutator that requires maintenance, etc., have a long vI, and have control performance comparable to that of conventional DC type F17I machines.
Widely used as a control motor for machine tools, etc.

This brushless motor uses a field pole made of a permanent magnet as a rotor, and an armature winding as a stator winding. For example, a three-phase AC armature current is passed through the stator winding, and the main magnetic flux of the field pole and this This is an electric motor that generates rotational force in the rotor using an armature current that is perpendicular to the main magnetic flux.

Therefore, in this electric motor, it is necessary to sequentially select a predetermined armature winding that generates the maximum torque in accordance with the rotational position of the rotor, and to cause armature current to flow through the winding.

For this selection, an armature current conversion control signal (hereinafter referred to as a commutation signal) using a position detection signal from a rotational position detector is usually used. As a rotational position detector, one using a resolver is widely used. For example, the resolver detector disclosed in Japanese Patent Application Laid-Open No. 54-33985 is configured so that it can detect the rotational speed at the same time as the rotational position. ing.

Figure 3 shows an example in which the above detector is applied to a servo system for position and speed control. Represents a position and speed detector. Third
In the figure, there are 8 three-phase brushless electric motors 2 and a resolver 3.
are connected, and the two-phase excitation signal e of this resolver 3
, eb and the output signal e. is input to the detection circuit 4, and the detection circuit 4 outputs a position detection signal eps and a speed detection signal etg. The position detection signal e ps is output as a voltage signal proportional to the rotation angle of the motor rotor. The commutation signal generation circuit 5 has a well-known circuit configuration, such as a combination of a comparator, a logic circuit, and the like. This commutation signal generation circuit 5 generates three-phase commutation signals C81 to C83 that perform an armature current conversion function to select a predetermined armature winding that generates maximum torque according to the rotation angle of the rotor. Occur.

On the other hand, the addition point 6 is supplied with the position command signal e and the above-mentioned O position detection signal e os, and from the addition point 6, Δ
eo=e,. A differential voltage of −e ps is output as a speed command signal. This speed command signal Δe and the speed detection signal etg are supplied to the addition point 7, and the addition point 7 outputs a difference voltage signal of Δe−Δe−etg. This differential voltage signal Δe is supplied to an amplifier 8, and the amplifier 8 outputs a voltage signal e subjected to a proportional-integral operation based on the differential voltage signal Δe.

This voltage signal e is converted by a conversion circuit 9 into a current i corresponding to a predetermined current command value. This current signal i and the above-mentioned commutation signals C81 to C83 are input to the distribution circuit 10, and from the distribution circuit 10, the commutation signal C8
Current command signals 18 to ic are output by converting the current signal i into a required three-phase signal based on signals 1 to C83. These current command signals 18 to ic are transmitted to current detectors 118 to 11
Armature current detection signal i of motor 2 detected by C
,. The current command signal 1 is compared with ~'co, respectively.
The respective differences between lc and current detection signal 'ao-'co are input to the power conversion circuit 12. Power conversion circuit 12
Then, these input signals are amplified, and the amplified signals convert the power from the power source into PWM mode through the power switch circuit.
The armature current is modulated and passed through each phase of the electric 8 machine 2.

(Problems to be Solved by the Invention) However, in the method described above in which the commutation signal is generated from the position detection signal e ps of the resolver position and speed detector 1, various phase delays listed below occur. There was a problem.

(2) Phase delay of the commutation signal based on the zumbling period of the resolver 3.

■, Phase delay in the generation process of the word-of-mouth signal.

(2) Phase delay of the electric current due to the inductance of the armature winding of the motor 2.

■, Phase delay in armature current control due to various time constants in the control loop.

■, Phase delay of armature current due to armature reaction.

In particular, when the electric motor 2 rotates at high speed or under heavy load, the various phase delays described above are significant, resulting in a problem in that control performance is significantly degraded.

The details of the causes of the various phase delays enumerated above are as follows.

(2) A phase delay of the T-John signal based on the sampling period of the resolver 3.

Generally, the resolver 3 samples position data every one cycle (half cycle or multiple cycles in some cases) of the excitation frequency, so it cannot extract continuous position data like an encoder. Therefore, the position data P between the position data P1 at a certain sampling time and the position data P2 at the next sampling time. It is not possible to generate a commutation signal based on the position data P2, and a commutation signal based on the position data P2 must be used. Therefore, in this case, a delay angle occurs due to the position data difference p2-po, and this delay angle causes a phase delay in the commutation signal.

■, Phase delay in the generation process of the word-of-mouth signal.

When a commutation signal is generated based on the position detection signal e DS, time is required for the calculation process, and a phase delay of the commutation signal occurs based on this processing time.

(2) Phase delay of armature current due to intagactance of armature winding of motor 2.

The armature winding of the motor 2 includes intagactance, which causes a delay in the inflow of armature current with respect to the current command signal. In particular, this effect becomes greater when the electric motor n2 rotates at high speed.

■, Phase delay in armature current control due to various time constants in the control loop.

The control circuit includes various signal processing circuits such as a comparator, a current amplification circuit, and a PWM circuit, and the signal processing circuits of these circuits cause a delay in the control signal.

■, Phase delay of armature current due to armature reaction.

When an armature current is passed through the motor 2, the main magnetic field is disturbed by the armature magnetic field, causing a shift in the neutral axis. Therefore, the current command signal @i −, ,
Measures such as shifting the phase of io are required.

In addition to the various phase delay problems described above, conventional devices also have the following problems. In other words, by using a multi-pole resolver 3 (limited to resolvers capable of absolute position detection) in accordance with the number of poles of the multi-pole electric motor 2, it is theoretically possible to increase the resolution of position detection. . However, when using a multipolar resolver 3, the electric g12
Since the electrical angular frequency is higher than the mechanical angular frequency of
When various phase delays occur as in conventional equipment,
The impact will be greater. For this reason, in the conventional device, when a multi-pole resolver 3 is used, the influence of the delay angle is so great that it is not practical.

The present invention was made in view of the above-mentioned conventional problems, and its purpose is to correct the effects of various phase delays including the phase delay of commutation signals, improve control performance, and improve the resolution of position detection. An object of the present invention is to provide a control TG+ device for a brushless motor that can increase the TG+ of a brushless motor.

(Means for Solving the Problems) The configuration of the present invention for solving the above problems will be described below with reference to FIG. 1, which corresponds to an embodiment.

A control device for a brushless motor according to the present invention includes a position and speed detector 1 connected to a rotor of a brushless motor 82 to be controlled to detect the rotational position and rotational speed of the rotor.
, current detectors 11 to 11o that detect the armature current of the motor 2 and output a current detection signal, an amplifier 8 that amplifies the difference voltage between the speed command signal and the speed detector number, and the position and speed a commutation signal generating circuit 5 that generates a commutation signal for controlling the switching of the armature current of the motor 2 based on the position detection signal from the detector 1;
The electric motor is driven by a difference signal between a current command signal obtained based on the output signal of the amplifier 8 and the commutation signal and the current detection signal! A brushless electric type control device having a power conversion circuit 12 that supplies an armature current to a power converter 12, and a phase correction circuit 13 that corrects the phase of the commutation signal based on the speed detection signal and the current detection signal. It is something.

(Operation of the Invention) In the brushless motor control device configured as described above, the phase correction circuit 13 functions to correct the phase of the commutation signal based on the speed detection signal and the current detection signal. Since the various phase delays described above vary with variations in the rotational speed of the motor 2 or the armature current, the above-mentioned phase correction of the commutation signal can adjust the entire speed range of the motor 2 from low speed to high speed. Over time, the influence of the various phase delays on the armature 7I5 flow control is well corrected, and the control performance of the armature current is significantly improved. As a result, it is also possible to use a multipolar resolver to improve the resolution of rotational position detection.

(Example of Actual Flow) Hereinafter, embodiments of the present invention will be described in detail based on the drawings.

FIG. 1 is a block diagram showing an embodiment of the present invention. In this figure, the same parts as those of the conventional device shown in FIG. 3 are given the same reference numerals, and the explanation thereof will be omitted.

As shown in FIG. 1, in this embodiment, the phase correction signals ■, ~ which correct the phases of the commutation signals O8, ~C8C, based on the speed detection signal etg and the current detection signal 'ao"""co are used. Phase correction circuit 1 that outputs vc
3 is provided. Thereby, the effects of the various phase delays described above are corrected all at once by correcting the phases of the commutation signals C8a to C8c using the phase correction signals V, to vC.

Among the various phase delays described above, the phase delay (3) varies depending on the rotational speed of the electric motor 2, but the delay angle is within a certain range. Further, the phase lag (■) is proportional to the rotational speed of the resolver 3, and the phase lag (2) and the phase lag (2) vary depending on the rotational speed of the electric motor 2. Furthermore, the phase delay of (2) varies depending on the magnitude of the armature current.

Therefore, regarding the phase delays of ■ to ■ above, the electric current lj[2
The optimum correction angle is determined according to the rotation speed of , and the optimum correction angle for the phase lag (2) is determined according to the magnitude of the armature current. Therefore, in this embodiment, the electric vJ machine 2
The optimum correction angle according to the rotational speed and armature current is set in advance by the phase correction circuit 13, and the above
The influence of the phase delay of is collectively corrected by phase correction of the commutation signals cs - cso using the phase correction signals V, .about.Vo. This makes it possible to correct the effects of various phase delays over the entire speed range of the brushless motor from low speed to high speed.

Next, the commutation signal generation circuit 5 in this embodiment
A specific example of the configuration and operation of the phase correction circuit 13 will be explained with reference to FIG. Blocks 5 and 13 in FIG. 2 constitute a commutation signal generation circuit and a phase correction circuit, respectively. The aforementioned current detection signals 'ao to 'co are input to the 1/V converter 13a, and are converted into voltage signals vao""co based on a predetermined conversion rate. In addition, the aforementioned speed detection signal e (a is V/V
The signal is input to the converter 13b and converted into a voltage signal tg based on a predetermined conversion rate. The above voltage signal ■ao~■C
8 and the voltage signal vtg are input to the adder 13G, and the addition output ffi pressure V (-V +V), V,
(=V, o+Vtg) a ao t
g, V (=Voo+Vtg) are added to the adder/subtractor 5b as a phase correction signal. This phase correction signal represents the phase correction angle.

On the other hand, a signal V-v3 designating the energization position of each phase current of the armature is outputted from the setting device 5a and added to the adder/subtractor 5b. The adder/subtractor 5b is set to perform an addition operation when the electric motor 2 is in a normal rotation state, and to perform a subtraction operation when the electric motor 2 is in a reverse rotation state.

and a signal (V, +Va) in the case of addition operation.

(V2+V,), (V3+VC) are output, and in the case of subtraction operation, the signals (V-V), (V2-V,)a, (V3-Vo> are output and added to the comparator 5C. Based on the input signal of and the position detection signal Ops, community signals cs to csc are output with required phase correction.

In the embodiment described above, the speed detection signal etg is obtained from the detection circuit 4 based on the signal from the resolver 3, but a speed detector such as an encoder is separately used to obtain the speed detection signal et, + You may also obtain

Furthermore, the embodiments described above are examples in which the control device of the present invention is applied to a servo system for position and speed control.
The present invention is not limited to this, but can also be applied to a servo system that only controls speed.

(Effects of the Invention) As described above, according to the present invention, the phase of the commutation signal is corrected by including a phase correction circuit that corrects the phase of the commutation signal based on the speed detection signal and the current detection signal. This makes it possible to satisfactorily correct the effects of various phase delays on armature current control over the entire speed range from low speed to high speed of the brushless motor. As a result, the linearity of the speed-torque characteristic and the torque current characteristic is significantly improved over the entire speed range, and good armature current control can be performed.

Further, according to the present invention, since the effects of the various phase delays described above are corrected, a multipolar resolver can be used for rotational position detection, and the resolution of rotational position detection can be improved.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention, FIG. 2 is a block diagram showing a configuration example of a commutation signal @ generation circuit and a phase correction circuit used in the present invention, and FIG. 3 is a block diagram showing a configuration example of a commutation signal @ generation circuit and a phase correction circuit used in the present invention. It is a block diagram showing an example of a device. DESCRIPTION OF SYMBOLS 1... Position and speed detector, 2... Brushless motor, 5... Commutation signal generation circuit, 8... Amplifier, 9... Conversion circuit, 10... Distribution circuit, 118
~11C...Current detector, 12...Power conversion circuit・
13-゛. Phase correction circuit. Difficulty 2 Father

Claims (2)

[Claims] (1) A position and speed detector connected to the rotor of the brushless motor to be controlled to detect the rotational position and rotational speed of the rotor, and a position and speed detector that detects the armature current of the motor and outputs a current detection signal. a current detector, an amplifier for amplifying the voltage difference between the speed command signal and the speed detection signal, and a commutation for converting and controlling the armature current of the motor based on the position detection signals from the position and speed detectors. a commutation signal generating circuit that generates a signal; and a commutation signal generation circuit that is driven by a difference signal between a current command signal obtained based on the output signal of the amplifier and the commutation signal and the current detection signal to supply an armature current to the motor. What is claimed is: 1. A control device for a brushless motor having a power conversion circuit, comprising: a phase correction circuit that corrects the phase of the commission signal based on the speed detection signal and the current detection signal. (2) The phase correction circuit includes: a voltage converter that converts the speed detection signal into a voltage signal at a predetermined ratio; a current/voltage converter that converts the current detection signal into a voltage signal at a predetermined ratio; Claim 1 comprising an adder that adds the output voltages of both converters to output a phase correction signal and inputs the phase correction signal to the commutation signal generation circuit.
A control device for a brushless electric motor as described in .