JPH0767299B2 - Brushless motor controller - Google Patents

Description

TECHNICAL FIELD The present invention relates to an improvement of a control device for a brushless electric motor.

(Prior Art) A brushless motor has features such as no brush to be consumed and no commutator requiring maintenance. Moreover, since it has the same control performance as a conventional DC motor, it controls machine tools. Widely used as an electric motor for motor vehicles. This brushless motor uses a field pole composed of permanent magnets as a rotor,
The armature winding is used as a stator winding, and for example, a three-phase AC armature current is passed through this stator winding, and a rotating force is applied to the rotor by the main magnetic flux of the field pole and the armature current orthogonal to this main magnetic flux. It is an electric motor to generate.

Therefore, in this 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 apply an armature current to the winding. This choice is usually
An armature current conversion control signal (hereinafter referred to as a commutation signal) using the position detection signal from the rotational position detector is used. As the rotational position detector, one using a resolver is widely used.For example, the resolver detector disclosed in Japanese Patent Laid-Open No. 54-33985 is configured so that the rotational speed can be detected simultaneously with the rotational position. ing.

FIG. 3 shows an example in which the above detector is applied to a servo system for position and speed control, and block 1 in FIG.
The part of represents a resolver position and speed detector for detecting the above-mentioned rotation position and rotation speed. In FIG. 3, a resolver 3 is connected to a three-phase brushless motor 2, and two-phase excitation signals e _a and e _{b of} this resolver 3 are connected.
And the output signal e _c are input to the detection circuit 4 and the detection circuit 4
Outputs a position detection signal e _ps and a speed detection signal e _tg . The position detection signal e _ps is output as a voltage signal proportional to the rotation angle of the motor rotor. The committing signal generating circuit 5 has a well-known circuit configuration, for example, a combination of a comparator and a logic circuit. This commutation signal generation circuit 5 is a three-phase commit signal that performs an armature current conversion action for selecting a predetermined armature winding that generates maximum torque according to the rotation angle of the rotor.
Generates CS _{1 to} CS ₃ .

On the other hand, the addition point 6 is supplied with the position command signal e _co and the position detection signal e _ps, and from the addition point 6, Δe _o = e _co −e _ps
Is output as a speed command signal. The speed command signal Δe _o and the speed detection signal e _tg are supplied to the addition point 7, and the difference voltage signal Δe = Δe _o −e _tg is output from the addition point 7. The difference voltage signal Δe is supplied to the amplifier 8, and the amplifier 8 outputs the voltage signal e which is proportional-integral-operated based on the difference voltage signal Δe. This voltage signal e
Is a current i corresponding to a predetermined current command value by the conversion circuit 9.
Is converted to. The current signal i and the commutation signals CS _{1 to} CS ₃ are input to the distribution circuit 10, and the distribution circuit 10 outputs the current signal i based on the commutation signals CS _{1 to} CS _3.
Is converted into a required three-phase signal, and current command signals i _{a to} i _c are output. These current command signals i _{a to} i _c are applied to the current detector 11
The current command signals i _{a to} i _c are compared with the armature current detection signals i _{ao to} i _{co of} the electric motor 2 detected by a to 11c, respectively.
And the respective current detection signals i _{ao to} i _co are input to the power conversion circuit 12. The power conversion circuit 12 amplifies these input signals, PWM-modulates the electric power from the power source through the power switch circuit by the amplified signal, and supplies an armature current to each phase of the electric motor 2.

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

． Phase delay of the commit signal based on the sampling period of the resolver 3.

． Phase lag in the process of generation of commit signal.

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

． Phase lag of 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 motor 2 is rotating at high speed or under heavy load, the above-mentioned various phase delays are remarkable, and as a result, there is a problem that the control performance is significantly deteriorated.

The causes of the various phase delays listed above will be described in detail below.

． Phase delay of the commit signal based on the sampling period of the resolver 3.

In general, the resolver 3 is a method of sampling the position data for each excitation frequency of one cycle (half cycle or a plurality of cycles depending on the case), so that continuous position data cannot be taken out like the encoder. Therefore, it is not possible to generate a commit signal based on the position data P _c between the position data P ₁ at a certain sampling time point and the position data P ₂ at the next sampling time point, and the position data P ₂ There is no choice but to use a commit signal based on. Therefore, in this case, a delay angle is generated due to the difference P ₂ −P _c of the position data, and this delay angle causes a phase delay in the commit signal.

． Phase lag in the process of generation of commit signal.

In the case of generating the commutation signal based on the position detection signal e _ps , it takes time in the arithmetic processing process, and a phase delay of the commutation signal occurs based on this processing time.

． Phase lag of the armature current due to the inductance of the armature winding of the motor 2.

The armature winding of the electric motor 2 includes ing tactance, which causes a delay in the inflow of the armature current with respect to the current command signal. Especially, when the electric motor 2 rotates at a high speed, the influence thereof becomes large.

． Phase lag of 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 a control signal is delayed due to the signal processing time of these circuits.

． Phase delay of armature current due to armature reaction.

When an armature current is passed through the electric motor 2, the main magnetic field is disturbed by the armature magnetic field, and the neutral axis is displaced. Therefore, it is necessary to take measures such as shifting the phases of the current command signals i _{a to} i _c by the angle of the neutral axis.

In addition to the various phase delay problems described above, the conventional device has the following problems. That is, by using the multipolar resolver 3 (limited to the resolver capable of absolute position detection) in accordance with the number of poles of the multipolar electric motor 2, it is possible in principle to increase the position detection resolution. . However, when the multi-pole resolver 3 is used, the electrical angular frequency becomes higher than the mechanical angular frequency of the electric motor 2, so that when various phase delays occur as in the conventional device, the influence thereof becomes large. . Therefore, in the conventional device, when the multi-pole resolver 3 is used, there is a problem that the influence of the delay angle is large and it cannot be put to practical use.

The present invention has been made in view of the above-mentioned conventional problems, and an object thereof is to correct the influence of various phase delays including the phase delay of a commit signal, improve the control performance, and improve the resolution of position detection. It is to provide a controller for a brushless electric motor that can improve

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

The present invention is directed to a position / speed detector 1 for detecting the rotational position and rotational speed of a rotor based on the output of a resolver connected to the rotor of a brushless motor 2 to be controlled;
A current detector 11 _a to 11 _c which outputs a current detection signal by detecting the armature current, the speed command signal and a position and speed detector 1
An amplifier 8 for amplifying a differential voltage from a speed detection signal output from the motor, and a commutation signal for converting and controlling the armature current of the electric motor 2 based on the position detection signal output from the position and speed detector 1. Electric power for supplying an armature current to the electric motor 2 driven by the generated commutation signal generation circuit 5 and the difference signal between the current command signal and the current detection signal obtained based on the output signal of the amplifier 8 and the commutation signal. A controller of a brushless motor having a conversion circuit 12 is targeted for improvement. Further, the present invention is characterized in that a phase correction circuit for correcting the phase delay of the committing signal based on the sampling period of the resolver based on the speed detection signal and the current detection signal is provided.

(Operation of the Invention) In the brushless motor control device having the above-described configuration, the phase correction circuit 13 has a function of correcting the phase of the committing signal based on the speed detection signal and the current detection signal. Since the various phase delays described above fluctuate with changes in the rotation speed of the electric motor 2 or the armature current, the electric motor 2 is corrected by the phase correction of the above-mentioned commit signal.
The effect of the various phase delays on the armature current control is satisfactorily corrected over the entire speed range from low speed to high speed, and the control performance of the armature current is significantly improved. As a result, the resolution of rotational position detection can be increased by using a multi-pole resolver.

(Example) Hereinafter, an example of the present invention is described in detail based on a drawing.

FIG. 1 is a block diagram showing an embodiment of the present invention. In FIG. 1, the same parts as those of the conventional device shown in FIG.

As shown in FIG. 1, in the present embodiment, the phase correction signal V _a for correcting the phases of the commutation signals CS _{a to} CS _c based on the speed detection signal _etg and the current detection signals i _{ao to} i _co. ~
A phase correction circuit 13 that outputs V _c is provided. Thus, the effects of various phase delay described above, the phase correction of committing station signal CS _a to CS _c by the phase correction signal V _a ~V _c, and corrects collectively.

Among the various phase delays described above, the phase delay f varies depending on the rotation speed of the electric motor 2, but the delay angle is within a certain range. Further, the phase delay of is proportional to the rotation speed of the resolver 3, and the phase delay of and the phase delay of fluctuate depending on the rotation speed of the electric motor 2. Furthermore, the phase delay of f varies with the magnitude of the armature current.

Therefore, for the phase delays (1) to (3), the optimum correction angle is determined according to the rotation speed of the electric motor 2, and for the phase delays (1) to (5), the optimum correction angle is determined according to the magnitude of the armature current. Therefore, in this embodiment, the optimum correction angle corresponding to the rotational speed and armature current of the motor 2 is set in advance by the phase correction circuit 13, a phase correction signal V _a ~ the influence of the phase delay of the ~ The commit signals CS _{a to} CS _c are phase-corrected by V _c so that they are collectively corrected. 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 the present embodiment
A specific configuration example of the phase correction circuit 13 and its operation will be described with reference to FIG. Blocks 5 and 13 in FIG.
Are portions that respectively constitute the commutation signal generation circuit and the phase correction circuit. The above-mentioned current detection signals i _ao ~ i
_co is input to the I / V converter 13a and converted into voltage signals V _{ao to} V _co based on a predetermined conversion rate. Further, the speed detection signal e _tg described above is input to the V / V converter 13b and converted into a voltage signal V _tg based on a predetermined conversion rate. Above voltage signal V _ao
~ V _co and the voltage signal V _tg are input to the adder 13c, and the added output voltages V _a (= V _ao + V _tg ), V _b (= V _bo + V _tg ), V _c (= V
_co + V _tg ) is added to the adder / subtractor 5b as a phase correction signal. This phase correction signal represents the phase correction angle.

On the other hand, it applied to the adder-subtracter 5b is output a signal V ₁ ~V ₃ that specifies the current position of each phase current of the armature from the setter 5a.
The adder / subtractor 5b is set to perform an adding operation when the electric motor 2 is in the normal rotation state and perform a subtracting operation when the electric motor 2 is in the reverse rotation state. Then, in the case of addition operation, the signal (V ₁ + V _a ),
Outputs (V ₂ + V _b ), (V ₃ + V _c ), and outputs signals (V ₁ −V _a ), (V ₂ −V _b ), (V ₃ −V _c ) in the case of subtraction operation. Add to comparator 5c. Comparator 5c is on the basis of the position detection signal e _ps with these input signals, and outputs the required phase corrected committed station signal CS _a to CS _c.

In addition, the embodiment described above is an example 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, and can be applied to a servo system only for speed control.

(Effects of the Invention) As described above, according to the present invention, the phase correction circuit that corrects the phase delay of the commutation signal based on the sampling cycle of the resolver based on the speed detection signal and the current detection signal is provided. Since the phase of the rotation signal is corrected, the effect of various phase delays on the armature current control can be corrected well over the entire speed range of the brushless motor from low speed to high speed. As a result, the linearity of the speed-torque characteristic and the torque-current characteristic are significantly improved over the entire speed range, and good armature current control can be performed.

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

[Brief description 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 conventional brushless motor controller. It is a block diagram showing an example of. 1 ... Position and speed detector, 2 ... Brushless electric motor,
5 ... Commutation signal generation circuit, 8 ... Amplifier, 9
...... Conversion circuit, 10 ...... Distribution circuit, 11a to 11c ...... Current detector, 12 ...... Power conversion circuit, 13 ...... Phase correction circuit.

 ─────────────────────────────────────────────────── --- Continuation of the front page (72) Inventor Tadashi Tadashi 1-15-1 Kita-Otsuka, Toshima-ku, Tokyo Yamayo Denki Co., Ltd. (72) Inventor Takeshi Ogawa 1-1-15 Kita-Otsuka, Toshima-ku, Tokyo No. 1 Sanyo Denki Co., Ltd. (72) Inventor Johei Yamamoto 1-15-15 Kitaotsuka, Toshima-ku, Tokyo Sanyo Denki Co., Ltd. (56) Reference JP-A-57-177288 (JP, A) ) JP-A-57-85591 (JP, A) JP-A-60-261386 (JP, A) JP-A-62-37081 (JP, A)

Claims (2)

[Claims] 1. A position / speed detector for detecting a rotational position and a rotational speed of a rotor of a brushless motor to be controlled based on an output of a resolver connected to the rotor, and an armature current of the motor. And a current detector that outputs a current detection signal, an amplifier that amplifies a voltage difference between the speed command signal and the speed detection signal output from the position and speed detector, and an amplifier that outputs the position and speed detector A commit signal generating circuit for generating a commit signal for controlling the conversion of the armature current of the electric motor based on a position detection signal, and a current command signal obtained based on the output signal of the amplifier and the commit signal. And a power conversion circuit that supplies an armature current to the electric motor by being driven by a difference signal between the electric current detection signal and the electric current detection signal. Te, the phase delay of the committing station signal based on the sampling period of the resolver, the control device for a brushless motor, characterized by comprising a phase correction circuit for correcting, 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, and a current / voltage converter that converts the current detection signal into a voltage signal at a predetermined ratio. 2. The control of the brushless motor according to claim 1, further comprising: an adder for adding the output voltages of the both converters to output a phase correction signal and inputting the phase correction signal to the committing signal generation circuit. apparatus.