JP2003189666A - Brushless dc motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a brushless DC motor whose operation quality can be improved by a simple construction. <P>SOLUTION: This brushless DC motor 11 has a built-in drive circuit 19 by which a phase angle during rotation is controlled. There is provided an optimum phase angle setting voltage generating circuit 40 including a coefficient circuit 41 which determines a relation between a speed command voltage PG and an optimum phase angle setting voltage Vθ, which sets a phase angle realizing a predetermined optimum operational conditions of a revolution corresponding to the speed command voltage PG. The coefficient circuit 41 applies the coefficient. operation to the inputted speed command voltage PG to output the optimum phase angle setting voltage Vθ. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a brushless DC motor having a built-in drive circuit and controlling the phase angle by the drive circuit.

[0002]

2. Description of the Related Art FIG. 3 shows a brushless DC motor (hereinafter referred to as a motor) 11 with a built-in drive circuit, which is the basis of the present invention.
FIG. 4 is a block diagram showing the electrical configuration of FIG.
2 is a sectional view of FIG.

A motor 11 having a basic structure of the present invention will be described below with reference to FIGS. 3 and 4.

In FIG. 4, a motor 1 with a built-in drive circuit
1 is a wiring board 12 and a stator 13 molded resin 14
And a rotor 16 provided on the inner circumference of the mold frame 15 and the like. The rotor 16 has a magnet 17
Is provided.

Further, on the wiring board 12, there is provided a hall sensor 18 for detecting the magnetism generated by the magnet 17 provided on the rotor 16 to detect the rotational position and the rotational speed of the rotor 16. ing.

Further, in the motor 11 constituted by the three-phase winding as an example, three Hall sensors 18 are arranged in the vicinity of the outer periphery of the rotor 16 at every 120 ° so that the motor 11 can operate properly. It is located at a position where torque is generated.

In FIG. 3, electronic circuit components for driving the motor 11 are mounted on the wiring board 12 to form a drive circuit 19.

The drive circuit 19 is mainly composed of a logic circuit 20 composed of an IC (integrated circuit), an inverter circuit 24 including a switching transistor section 21 and a diode section 22. Each end bundle of the three-phase winding 23 is connected to each transistor 21a of the transistor section 21 and each diode 22a of the diode section 22.

Further, in order to prevent the control unit from being destroyed due to the overload of the motor 11 and the current being in the overcurrent state, the transistor group in the lower stage of the transistor section 21 is grounded, for example, from 1 Ω. A current limiting resistor Rf of about 0.5Ω is connected in series.

In the drive circuit 19, the logic circuit 20 turns on the switching transistor portion 21 of the inverter circuit 24 in response to the speed command voltage PG input from the outside.
Alternatively, it is turned off to supply the winding current. In addition, the rotation speed of the rotor 16 is detected by the hall sensor 18, and the logic circuit 20 performs feedback control corresponding to the speed command voltage PG.

The hall sensor 18 of such a motor 11
It is known that, due to the reaction of the rotor 16 and the like, the optimum installation position of the above item 1 differs depending on the load current and the like.

Further, in the above-described motor 11, the installation position of the hall sensor 18 is preset to an optimum position on the wiring board 12 according to the load used. Therefore, it is difficult to deal with the fluctuation of the load torque. On the other hand, regarding a motor with a built-in motor drive IC whose phase angle is adjustable, in order to determine the optimum phase angle in the vicinity of the load of use of the motor, the phase angle setting voltage corresponding to the optimum phase angle is A phase angle setting voltage generating circuit that divides and obtains the reference voltage is assumed.

FIG. 7 shows a conventional phase angle setting voltage generating circuit 2
5 is a circuit diagram of FIG.

The phase angle setting voltage generating circuit 25 is connected in series with resistors R3 and R4 to a fixed voltage Vcc of 5V or 7.5V obtained from the internal power source of the IC, and divides the divided voltage of Vcc. Used as a voltage for adjusting the phase angle.

[0015]

However, in such a phase angle setting voltage generating circuit 25, the phase angle adjusting voltage is constant.

For this reason, when the phase angle of the motor 11 in the rotating state deviates from the optimum rotating state, the phase angle becomes too advanced or delayed, noise is generated, and the efficiency is expected to decrease.

Particularly, in the case of a fan load torque such as an outdoor unit motor of an air conditioner, there is a relationship represented by a quadratic curve between the rotational speed and the torque as shown in FIG. Further, even in the case of a fan motor in which the number of revolutions used is set in multiple stages, the optimum phase angle corresponding to the number of revolutions in each stage is one point. Therefore, when viewed from the entire rotational speed range of the motor 11, it is assumed that the efficiency and the noise state deteriorate in the phase angle range other than the optimum phase angle.

The present invention has been made to solve such a problem, and an object thereof is to provide a brushless DC motor capable of improving operation quality with a simple structure.

[0019]

According to a first aspect of the present invention, there is provided a brushless DC motor having a drive circuit for controlling a rotation speed and a phase angle during rotation, wherein the drive circuit is the brushless DC. Coefficient means for determining the relationship between the optimum phase angle setting voltage of the phase angle for realizing the optimum operating conditions at the rotation speed corresponding to the speed command voltage for commanding the rotation speed of the motor, and the coefficient means based on the speed command voltage An optimum phase angle setting voltage generating means for outputting the calculated optimum phase angle setting voltage, and a brassless DC motor.

The brushless DC motor according to claim 1, wherein the coefficient means of the invention of claim 2 is a voltage dividing circuit including a resistance element.

[0021]

[Operation] According to the brushless DC motor of the present invention, the rotation speed and the phase angle during rotation are controlled by the built-in drive circuit. When the speed command is input to the optimum phase angle setting voltage generating means, the coefficient means performs a coefficient operation on the speed command voltage and outputs the optimum phase angle setting voltage.

This optimum phase angle setting voltage corresponds to a phase angle that realizes a predetermined optimum operating condition at the rotation speed corresponding to the speed command voltage.

Therefore, with such a simple structure of the coefficient means, the optimum phase angle corresponding to the used torque can be set, and the efficiency and noise reduction of the brushless DC motor can be realized. The operation quality can be improved.

Further, according to the invention of claim 2, since the coefficient means is a voltage dividing circuit including a resistance element, the arrangement of the resistors used in the existing drive circuit is changed to change the coefficient. Can be dealt with and the configuration becomes simple.

[0025]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A brushless DC motor (hereinafter referred to as a motor) 11 according to the present invention will be described with reference to FIGS.

FIG. 1 is a block diagram of an optimum phase angle setting voltage generation circuit 40 according to an embodiment of the present invention provided in the drive circuit 19, and FIG. 2 is an optimum phase angle setting voltage generation circuit 40.
2 is a circuit diagram showing a configuration example of a coefficient circuit 41 included in FIG.
FIG. 3 is a block diagram showing the electrical configuration of the motor 11 with a built-in drive circuit, which is the basis of the present invention.
5 is a cross-sectional view of the motor 11, FIG. 5 is a graph showing the relationship between the rotational speed of the motor 11 and the magnitude of load torque, and FIG. 6 is a graph showing the characteristics of the motor 11 according to the present embodiment. .

FIG. 3 and FIG. 4 show the basic structure of the present invention, which has already been described, and a repetitive description thereof will be omitted. The reference numerals used in the description of FIGS. 3 and 4 are also used in the following description.

The optimum phase angle setting voltage generation circuit 40 receives the speed command voltage PG and outputs the signal line 42 as it is, and the speed command voltage PG is input to calculate the coefficient and output the optimum phase angle setting voltage. And a coefficient circuit 41 for As an example of the coefficient circuit 41, as shown in FIG. 2, there is included a case including a series circuit of resistance elements of resistors R1 and R2 for dividing the speed command voltage PG between it and the ground potential.

When the motor 11 of this embodiment is used to drive an outdoor unit fan of an air conditioner, for example, the motor 1
When the load of No. 1 has torque characteristics such that the rotation speed of the fan increases and the load also increases when the speed command voltage PG increases, there is a graph between the rotation speed of the fan and the magnitude of the load torque. It is known that there is a quadratic curve relationship as shown in FIG.

The phase angle when driving the motor 11 is conventionally set corresponding to the load torque. On the other hand, in the present embodiment, the phase angle setting voltage PG when the phase angle that can realize the optimum efficiency or low noise state is set from the rotation state of the fan is investigated in advance. Such a voltage is set as the optimum phase angle setting voltage Vθ, and this optimum phase angle setting voltage Vθ is set.
And an approximate straight line L as shown in FIG. 6A from the relationship between the above-mentioned optimum efficiency and the phase angle that can realize the low noise state.
Determine one.

In order to realize this phase angle, a recent straight line L2 shown in FIG. 6 (2) is determined from the relationship between the speed command voltage PG input from an external control device and the phase angle. These approximate straight lines L1 and L2 are combined to create an approximate straight line L3 showing the relationship between the speed command voltage and the optimum phase angle setting voltage shown in FIG. 6 (3). If the coefficient circuit 41 has a coefficient corresponding to the inclination of the approximate straight line L3, the optimum phase angle setting voltage Vθ can be obtained from the speed command voltage PG in a circuit manner.

In this embodiment, since the coefficient circuit 41 is composed of the voltage dividing circuit of the resistors R1 and R2 as described above, the expression for determining the optimum phase angle setting voltage Vθ obtained with respect to the speed command voltage PG. Vθ = PG × R2 / (R1 + R2) (1) The coefficient R2 / (R1 + R2) (2) in (1) corresponds to the slope of the above-described approximate straight line L3 in FIG. The resistance values of R1 and R2 may be selected.

The optimum phase angle setting voltage Vθ output from the optimum phase angle setting voltage generation circuit 40 is input to the logic circuit 20 of FIG. 3 and controlled to a phase angle corresponding to the optimum phase angle setting voltage Vθ. It

In this way, according to this embodiment, the phase angle suitable for the rotational speed of the motor 11 and the load torque can be set, so that the efficiency of the motor 11 is improved and the noise is reduced. be able to.

That is, when the speed command voltage changes, the optimum phase angle setting voltage Vθ changes correspondingly, and the optimum phase angle is obtained.

Further, according to this embodiment, even if the load deviates from the load corresponding to the fixed phase angle set for a predetermined load torque, the optimum efficiency is obtained with respect to the deviated load. Alternatively, since the optimum phase angle setting voltage corresponding to the phase angle that realizes noise reduction is generated from the coefficient circuit 41, the motor 1 can be operated even under various operating conditions.
It is possible to improve the efficiency of 1 and reduce noise.

Further, in the present embodiment, since the coefficient circuit 41 is composed of the resistors R1 and R2, it is not necessary to add new parts, and specifically, the fixed optimum as shown in FIG. This can be realized by changing the arrangement of the resistance elements used to generate the phase angle setting voltage Vθ, and the configuration can be simplified.

When a load such as a fan connected to the motor 11 is changed, it can be dealt with only by changing a combination of the resistors R1 and R2 having resistance values corresponding to the fan load torque.

[0039]

According to the invention of claim 1, when the speed command voltage is inputted to the optimum phase angle setting voltage generating means, the coefficient means converts the speed command voltage and outputs the optimum phase angle setting voltage. I did it. This makes it possible to set the optimum phase angle corresponding to the torque used by a simple structure such as coefficient means, improve the efficiency of the brushless DC motor, and reduce the noise, thereby improving the operation quality. Can be improved.

Further, according to the invention of claim 2, since the coefficient means is a voltage dividing circuit including a resistor,
This can be dealt with by changing the arrangement of the resistors used in the existing drive circuit, and the configuration becomes simple.

[Brief description of drawings]

FIG. 1 is a block diagram of an optimum phase angle setting voltage generation circuit provided in a drive circuit according to an embodiment of the present invention.

FIG. 2 is a circuit diagram showing a configuration example of a coefficient circuit included in an optimum phase angle setting voltage generation circuit.

FIG. 3 is a block diagram showing the electrical configuration of a brushless DC motor with a built-in drive circuit, which is the basis of the present invention.

FIG. 4 is a sectional view of a motor.

FIG. 5 is a graph showing the relationship between the number of rotations of the motor and the magnitude of load torque.

FIG. 6 is a graph showing the characteristics of the motor according to the present embodiment.

FIG. 7 is a circuit diagram of a phase angle setting voltage generation circuit 25.

[Explanation of symbols]

11 Brushless DC motor 12 wiring board 16 rotor 18 Hall sensor 19 Drive circuit 40 Optimum phase angle setting voltage generator 41 coefficient circuit R1, R2 resistance

Claims (2)

[Claims] 1. A brushless DC motor having a drive circuit for controlling a rotation speed during rotation and a phase angle, wherein the drive circuit corresponds to a speed command voltage for commanding a rotation speed of the brushless DC motor. Coefficient means for determining the relationship between the phase angle and the optimum phase angle setting voltage that realizes the optimum operating condition at the rotation speed, and an optimum means for outputting the optimum phase angle setting voltage calculated by the coefficient means on the basis of the speed command voltage. A brassless DC motor, comprising: a phase angle setting voltage generating means. 2. The brushless DC motor according to claim 1, wherein the coefficient means is a voltage dividing circuit including a resistance element.