JP2000069788A - Brushless motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an energy-saving and low-noise brushless motor by using a brushless structure for a DC motor and optimally controlling the switching timing of the armature coil current. SOLUTION: A stator 3 is provided with armature coils 4a-4f. Outside the stator 3, a rotor 1 with main magnets 2 is disposed. A sensor magnet 5 is installed on a shaft 6 rotating integrally with the rotor 1 at an angle of delay which reduces resonance sound. Hall elements devices IC1-3 are disposed on the inner surface of the stator 3 to detect the direction of a magnetic field generated by the sensor magnet 5. An advance angle controlling means receives a sensor signal and calculates the rotational speed of the motor from the cycle of detection of a change in the direction of the magnetic field, When the rotational speed becomes constant, the advance angle controlling means outputs an advance angle variable for advance angle control. Then, a timing controlling means receives the sensor signal and the advance angle variable and then makes an advance angle control to control the current switching timing of MOSFETs (Q1-Q6) through a motor driving circuit 13.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an outer rotor type brushless D suitable for driving a blower fan for a vehicle.
The present invention relates to a brushless motor in which a switching timing of a current flowing through an armature coil in a C motor is optimized.

[0002]

2. Description of the Related Art Conventionally, a motor mounted on a vehicle such as an automobile, for example, a motor for rotating a blower fan used in an air conditioner switches the direction of an electric current flowing through an armature coil using a commutator and a brush. DC motors have been used.

In this conventional DC motor mounted on a vehicle, a battery of the vehicle is used as a power supply, and the DC motor is driven by a constant voltage power supply.
For this reason, in the rotation control of the DC motor using the brush, the power supply voltage is divided by a voltage dividing resistor and used. For example, when the battery voltage is 12 V and the DC motor is driven at 3 V, the remaining 9 V is applied to the voltage dividing resistor and is consumed as heat. For this reason, the power consumed by the voltage dividing resistor is wasted and energy efficiency is not good. Further, the sliding noise caused by the brush caused noise.

[0004]

However, when the DC motor has a brushless structure and the rotation of the power supply voltage is variable (pulse width control) and the rotation is controlled, the current flowing through the armature coil is switched from the detection position of the rotor magnetic pole. Depending on the timing, the torque generation efficiency changes. Also, the loudness of the beat sound due to the resonance between the motor and the storage case changes according to the switching timing.

The switching timing at which the torque generation efficiency is maximized is different from the switching timing at which the beat noise is minimized. The beat noise increases when the efficiency is prioritized, and the efficiency decreases when the beat noise is reduced. .

SUMMARY OF THE INVENTION It is an object of the present invention to provide an energy-saving and low-noise brushless motor in which a DC motor used for a blower fan or the like has a brushless structure and an armature coil current switching timing is optimally controlled.

[0007]

In order to solve the above-mentioned problems, a brushless motor according to the present invention is used in a storage case for driving a fan of a blower, and has an outer rotor type in which an armature is arranged on the inner peripheral side of the motor. Switching device (Q) for switching the current flowing through the armature coil (4) disposed on the stator (3).
1 to Q6) and the field permanent magnet (2) attached to the rotor (1), and integrally attached to the rotor (1) at a delay angle at which the resonance between the motor and the storage case is minimized. And a sensor magnet (5) indicating the rotational position of the rotor (1), and attached to the stator (3),
A magnetic sensor (IC1 to IC3) for detecting a direction of a magnetic field by the sensor magnet (5), and a magnetic field direction change detection from the magnetic sensors (IC1 to IC3).
The rotation speed of the rotor (1) is calculated, and when the rotation speed reaches a predetermined constant speed, the advance angle control for advancing the delay angle of the sensor magnet (5) with respect to the field permanent magnet (2) is performed. Advancing angle control means (12a) for outputting the advancing amount of the magnetic field, detecting a change in the magnetic field direction from the magnetic sensors (IC1 to IC3) and receiving the advancing amount, and performing advancing control according to the advancing amount The switching element (Q1
To Q6), and timing control means (12b) for controlling the current switching timing.

According to the above configuration, until the rotation speed of the motor reaches a certain speed, the resonance sound between the motor and its storage case is delayed with respect to the rotation position of the field permanent magnet at a small delay angle, and the current of the switching element is reduced. The switching timing is controlled, and after reaching a certain speed, the advance angle is controlled.

Further, the advance angle control means (12a)
When the rotation speed of the rotor (1) is low, the amount of advance of the delay angle is controlled to be small, and when the rotation speed of the rotor (1) is high, the amount of advance of the delay angle is controlled to be large. Control is performed with priority given to high efficiency when the motor is rotating at high speed.

Further, the advance angle control means (12a) smoothly changes the advance amount of the delay angle in accordance with the rotational speed of the rotor (1), so that switching is performed in accordance with the rotational speed of the motor. The current switching timing of the element is smoothly changed.

[0011]

In the brushless motor according to the first aspect of the present invention, until the rotation speed of the motor reaches a certain speed,
Since the resonance between the motor and its storage case is at a small delay angle with respect to the rotational position of the field permanent magnet, the current switching timing of the switching element is controlled. For example, when the rotation is unstable, the rotation can be controlled with low noise, and when the rotation speed is higher than a certain speed, the switching timing of the current flowing through the armature coil can be optimally controlled in consideration of motor efficiency and noise.

In the brushless motor according to the second aspect of the present invention, when the motor in which noise is relatively problematic rotates at a low speed, priority is given to low noise rather than high efficiency. When the motor whose efficiency is of high concern rotates at high speed, control is performed with priority given to high efficiency over low noise, so that a brushless motor with low energy consumption and low noise can be provided.

In the brushless motor according to the third aspect of the present invention, the current switching timing of the switching element is smoothly changed with respect to the rotational position of the field permanent magnet in accordance with the rotational speed of the motor. Change is gentle and smooth rotation can be obtained.

In the brushless motor according to the fourth or fifth aspect of the present invention, since the sensor magnet has a plurality of pairs of N poles and S poles, or a plurality of magnetic sensors are arranged, the rotor has one rotor. A change in the direction of the magnetic field can be detected a plurality of times during rotation, and even if the rotation speed of the rotor changes, high-speed response and fine-grained timing control can be performed following the change.

[0015]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a bottom view of a brushless motor according to the present invention as viewed from below. FIG. 1A shows a configuration example in which torque generation efficiency is improved, and FIG. 1B shows a configuration example in which noise is reduced. The brushless motor according to the present embodiment is used for driving a fan of a vehicle air conditioner, and is a three-phase two-pole wound outer rotor type brushless DC motor. The rotor is provided with a permanent magnet for field.

On the stator 3, armature coils 4a to 4f are arranged in three phases with the respective protruding portions 3a to 3f as cores, and main magnets (permanent magnets for field) 2 are provided at 90-degree intervals outside the armature coils 4a to 4f. Provided rotor 1 is arranged. The sensor magnet 5 indicating the rotational position of the rotor 1 has two pairs of N poles and S poles arranged at an equal angle with respect to the rotation center of the rotor 1 and is attached to a shaft 6 that rotates integrally with the rotor 1. . Hall ICs 1 to 3 (magnetic sensors) for detecting the direction of the magnetic field generated by the sensor magnet 5 are uniformly arranged on the inner periphery of the stator 3 at intervals of 120 degrees.

In the brushless DC motor, the generated torque changes depending on the timing of switching the current flowing through the armature coils 4a to 4f from the detection position of the main magnet 2. When the sensor magnet 5 indicating the rotational position of the rotor 1 is attached to the shaft 6 at a delay angle of 30 degrees with respect to the main magnet 2 as shown in FIG. 1A, the generated torque becomes largest and the efficiency is improved. FIG. 1 (b)
When the delay angle is 42 degrees as shown in FIG. 7, the beating sound (resonance sound) due to the resonance between the vibration frequency of the motor and the natural vibration frequency of the motor housing case is minimized. In the present embodiment, the sensor magnet 2 is moved to the shaft 6 at a delay angle of 42 degrees.
Attached to. Here, indicates a coil in which a current path is short and a current twice as large as that of the other armature coils flows. Indicates a position where a forward rotation torque is generated by the repulsive force between the armature coil 3c (3f) and the main magnet 2, and indicates a position where a reverse torque is generated by the repulsive force between the armature coil 3a (3d) and the main magnet 2.

FIG. 2 is a block diagram of a control circuit of the brushless motor according to the present embodiment. The sensor signal detection circuit 11 receives the detection of a change in the magnetic field direction of the sensor magnet 5 from the Hall ICs 1 to 3, generates respective inversion signals, and inputs the inverted signals together with the non-inversion signal to the microcomputer 12 as sensor signals consisting of six signals. I do. This is because the microcomputer 12 used in the present embodiment detects only the falling edge of the input signal and converts the rising edge to the falling edge for detection. In the processing in the microcomputer 12, the advance angle control means 12a receives the sensor signal, calculates the rotation speed of the motor from the period of the magnetic field direction change detection, and sets the rotation speed to a predetermined constant speed. When it reaches, an advance amount for advance control for increasing the delay angle of the sensor magnet 5 with respect to the field permanent magnet 2 is output. Next, in the timing control means 12b, the sensor signal, the advance amount,
And a rotation instruction signal (PWM signal) for instructing rotation of the motor from an air-conditioning control device (not shown).
The current switching timing of SFETs (switching elements) Q1 to Q6 is controlled.

FIG. 3A is a timing chart when the advance control of the control circuit of the brushless motor according to the present embodiment is not performed, and FIG. 3B shows the MOSFETs (Q1 to Q1) controlled at this timing. The connection relation of Q6) is shown.
Since the sensor magnet 5 has the N pole and the S pole arranged at every 90 degrees, the magnetic field direction change detection signal from the Hall IC changes for two periods during one rotation of the rotor 1. Thus, the timing of the rotation of the rotor can be controlled twice as finely. Further, by arranging three Hall ICs at equal intervals, it is possible to control the rotation of the rotor three times more precisely. Based on the detection of a change in the magnetic field direction from the Hall ICs 1 to 3 arranged at equal intervals, the MOSFETs (Q1 to Q6) are turned on / off a total of 12 times while the rotor 1 makes one rotation, and turned on.
Depending on the combination of the FETs, the armature coils 4a to 4f
Switch the direction of the current flowing through.

FIG. 4A shows the rotor rotational position, and FIG.
Is the Hall IC signal and MOS used for the control at that time.
4 shows a correspondence relationship with a conduction state of an FET. Rotor rotation angle 0
In the case of the temperature, the signal from the Hall IC 3 is used, and the MOSFE
T (Q1) and (Q5) become conductive. MOSFET
(Q1) is on the power supply side and the MOSFET (Q5) is on the ground side, and a voltage is applied between the connection point U and the connection point V.

FIG. 5 is a diagram showing the energized state of each coil when the Hall IC 3 is switched and the position of the sensor magnet 5 with respect to the main magnet 2 depending on the delay angle. MOSFE
T (Q1) and (Q5) are turned on, the U side (Q1) becomes the power supply voltage, and the V side (Q5) is grounded. Current path S1 is U side (+) → coil 4f → coil 4c → V side (GND)
Assuming that the current path S2 is U side (+) → coil 4e → coil 4b → coil 4a → coil 4d → V side (GND), the current value is doubled because the resistance value of the current path S1 is half. (Of FIG. 1). A particularly strong repulsive force is generated between the coil whose current value is doubled and the main magnet 2 as compared with the other coils, and a strong rotational torque for canceling the reverse torque is generated.

FIG. 6A shows a case where the rotor rotation angle is 30 degrees, and FIG. 6B shows a Hall IC used for control at that time.
The correspondence between the signal and the conduction state of the MOSFET is shown. When the rotor rotation angle is 30 degrees, the MOSFETs (Q3) and (Q5) are turned on using the signal from the Hall IC1. MOSFET (Q3) is the power supply side, MOSFET
(Q5) is on the ground side, and a voltage is applied between the connection point W and the connection point V.

FIG. 7 is a diagram showing the energized state of each coil when the Hall IC 1 is switched and the position of the sensor magnet 5 with respect to the main magnet 2 due to the delay angle. MOSFE
T (Q3) and (Q5) are turned on, the W side (Q3) becomes the power supply voltage, and the V side (Q5) is grounded. Current path S3 is U side (+) → coil 4a → coil 4d → V side (GND)
Assuming that the current path S4 is U side (+) → coil 4b → coil 4e → coil 4f → coil 4c → V side (GND), the current value is doubled because the current path S3 has a half resistance value. .

FIG. 8 is based on the signal from the Hall IC.
5 is a timing chart for outputting an output switching control signal of a MOSFET, wherein (a) shows an input signal from a sensor (Hall IC) and (b) shows a gate signal of the MOSFET.

SAH and SAL shown in (a) indicate a signal from the Hall IC 1 and its inverted signal, respectively. Similarly, SBH and SBL are output from Hall IC2, respectively.
SCH and SCL indicate a signal from the Hall IC 3 and its inverted signal, respectively. With these six signals, the timing can be finely controlled every 30-degree rotation of the rotor.

(B) shows a gate signal output to the MOSFET at the time of the advance control, AT, BT, and CT denote the gates for the high-side (power side), and AB, BB, and CB denote the gates for the low-side (ground side) MOSFET. Indicates a signal. In the present embodiment, the timing of the gate signal of the MOSFET is controlled by the fall of the six signals of the sensor input. In this case, corresponding to the fall of each sensor signal,
Timing corresponding to the next fall (30 of rotor 1)
(Equivalent to degree rotation), and on / off control of the gate signal of the MOSFET is performed. At that time, the rotation speed of the rotor is calculated from the time between the falling edges of the sensor signal, and the advance amount for the advance control corresponding to the rotation speed is obtained. Then, when on / off control of the gate signal of the MOSFET is performed, advance control is performed in accordance with the advance amount and timing control is performed. The same control can be performed by using the rising edge of the sensor signal.

FIGS. 9A and 9B show the relationship between the advance control amount and the number of revolutions of the motor. FIG. 9A shows the advance amount in degrees.
(B) represents the amount of advance in time. As shown in (a), the advance amount is set to 0 until the rotation speed of the motor is 1800 rpm,
MOS with a mechanically fixed delay angle D (for example, 42 degrees)
On / off control of the output of the FET. This is because, for example, when the motor is started, the rotation speed of the motor is not stable, the rotation speed of the rotor is calculated from the time between the falling edges of the sensor signal, and the advance angle control corresponding to the rotation speed is performed. This is because the prediction control for predicting the next fall from the detection of the fall of the sensor signal causes a deviation from the actual rotation speed, and the advance amount does not match the actual rotation speed. That is, if the advance angle control is performed while the rotation speed is not stable, the rotation torque fluctuates and causes rotation unevenness, so that a mechanically fixed delay angle, that is, low noise is obtained until a certain rotation speed is reached. The output of the MOSFET is on / off controlled by the delay angle, and the advance angle control is not performed.

When the number of revolutions of the motor reaches 1800 rpm, advance angle control is started, and the delay angle is linearly and smoothly changed continuously from D to D-8 until 2500 rpm. If the delay angle is suddenly changed, the rotational torque also changes suddenly, causing rotation unevenness. To avoid this, the delay angle is smoothly and continuously changed. Motor rotation speed is 250
At 0 rpm or more, an 8 degree advance control is performed, and the delay angle is set to D-
8 (34 degrees).

Under the software control of the microcomputer, in order to perform the control according to the above-mentioned rotation speed, the advance angle control corresponding to the motor rotation speed shown in (b) is performed. First, since the advance angle control is not performed until the motor rotation speed reaches 1800 rpm, when the falling edge of the sensor signal is detected, the output of the MOSFET is turned on / off immediately after the detection.

When the motor rotation speed reaches 1800 rpm, advance angle control is started, and as shown in FIG.
A sensor signal is received at every 0-degree rotation, and a timing corresponding to the next fall (corresponding to 30-degree rotation of the rotor 1) is predicted to turn on / off the gate signal of the MOSFET. That is, the motor rotation speed is 1800 rpm (period: 3
At 3.3 msec), the time required for the rotor to rotate 30 degrees is 2.78 msec. At 2500 rpm (period: 24 msec), the time required for the rotor to rotate 30 degrees is 2 msec. After the time required for this 30-degree rotation has elapsed, the MO
On / off control of the gate signal of the SFET. 2500
At the time of rpm, in order to perform the 8-degree advance control, the advance time by software is set to (2-0.533) msec.

FIG. 10 shows the relationship between the delay angle of the sensor magnet 5 with respect to the main magnet 2 and the noise level. When the rotation speed is 2400 rpm, the beat sound component due to the delay angle is masked due to the influence of the blowing sound, and the noise level becomes constant. When the rotation speed is 900 rpm, the blowing sound becomes smaller, so that the beat sound component becomes relatively large, and the noise becomes smaller as the delay angle becomes larger. For this reason, particularly in the low rotation speed region, the effect of reducing the noise by increasing the delay angle is great.

FIG. 11 shows the relationship between the delay angle of the sensor magnet 5 with respect to the main magnet 2 and the motor efficiency. When the delay angle is about 30 degrees, the motor efficiency becomes maximum, and as a result, the rotational torque becomes maximum. In consideration of the relationship between the delay angle and the noise level, in the high rotation speed region, the noise does not change even if the delay angle is changed. Obtainable.

From the above, when the rotation speed of the rotor is low, the amount of advance of the delay angle is controlled to be small, and when the rotation speed of the rotor is high, the amount of advance of the delay angle is controlled to be large. Can be controlled at the optimum ratio.

FIG. 12 shows the motor speed and its noise.
The change of the relationship with the delay angle with the next component is shown. For example, 10
At 00 rpm, that is, at 16.7 revolutions per second, the twelfth-order component becomes 200 Hz, and the resonance between the motor and its storage case maximizes the beat sound. Further, when the number of revolutions is further increased, the blowing sound becomes louder than the beat sound, and the sound is masked.

FIG. 13 is a graph showing the relationship between the motor speed and its noise.
The change of the relationship with the delay angle with the next component is shown. For example, 50
At 0 rpm, ie, 8.3 revolutions per second, the 24th order component is 2
00 Hz, and the beating sound is maximized due to the resonance between the motor and its storage case. Further, when the number of revolutions is further increased, the blowing sound becomes louder than the beat sound, and the sound is masked.

As described above, by using the brushless motor of the present invention for driving the fan of the air conditioner for a vehicle, low noise is obtained when air conditioning is started or at a low rotation speed, that is, at low rotation speed, that is, at a high rotation speed. In other words, when the air volume is large, energy-saving and high-torque torque can be obtained by high-efficiency operation, and this can be controlled to an optimal ratio by the number of revolutions to obtain a comfortable air-conditioning environment.

Although the present embodiment has been described as a brushless motor for driving a blower fan of a vehicle air conditioner, the present invention can be similarly applied to, for example, a radiator cooling fan of a vehicle engine. It can also be used for blower fans and the like.

[Brief description of the drawings]

FIG. 1 is a bottom view of a brushless motor according to the present invention;
(A) is a figure which shows the example of a structure which improves torque generation efficiency, (b) is a figure which shows the example of a structure which becomes low noise.

FIG. 2 is a block diagram of a control circuit section of the brushless motor of the present invention.

FIG. 3A is a timing chart of a control circuit section of a brushless motor, and FIG. 3B is a diagram illustrating a connection relation of MOSFETs.

4A is a rotor rotational position, and FIG. 4B is a Hall IC.
FIG. 3 is a diagram illustrating a correspondence relationship between a signal and a conduction state of a MOSFET.

FIG. 5 shows the energized state of each coil when switching the Hall IC 3;
It is a figure showing a position by a delay angle of a sensor magnet to a main magnet.

FIG. 6A shows a case where the rotor rotation angle is 30 degrees,
(B) is a diagram showing the correspondence between the Hall IC signal and the conduction state of the MOSFET.

FIG. 7 shows the energized state of each coil when the Hall IC 1 is switched,
It is a figure showing a position by a delay angle of a sensor magnet to a main magnet.

8A is a timing chart showing an input signal from a sensor (Hall IC), and FIG. 8B is a timing chart showing a gate signal of a MOSFET.

9A and 9B are diagrams illustrating an advance angle control amount with respect to the number of rotations of a motor, wherein FIG. 9A is a diagram illustrating an advance angle amount by an angle, and FIG. 9B is a diagram illustrating an advance angle amount by a time.

FIG. 10 is a diagram illustrating a relationship between a delay angle of a sensor magnet with respect to a main magnet and a noise level.

FIG. 11 is a diagram illustrating a relationship between a delay angle of a sensor magnet with respect to a main magnet and motor efficiency.

FIG. 12 is a diagram showing a relationship between a motor rotation speed and a twelfth-order component of the noise.

FIG. 13 is a diagram showing a relationship between a motor rotation speed and a 24th-order component of the noise.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... rotor, 2 ... main magnet (field permanent magnet), 3 ... stator, 4a-f ... armature coil, 5 ... sensor magnet, 6 ... shaft, 11 ... sensor signal detection circuit, 12 ... microcomputer, 13 ... Motor drive circuit, IC1-3 ... Hall IC (magnetic sensor), ... 2
Coil where current is flowing twice, ... forward rotation torque generation position, ... reverse torque generation position.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Tsuyoshi Sekine 5-24-15 Minamidai, Nakano-ku, Tokyo Calsonic Corporation (72) Inventor Eiji Takahashi 5-24-15 Minamidai, Nakano-ku, Tokyo Calsonic F term in reference company (reference) 5H560 AA01 BB04 BB08 DA03 DA19 DB20 EA05 EB01 ED02 FF04

Claims (5)

[Claims] An outer rotor type brushless DC motor which is used in a storage case for driving a fan of a blower and has an armature disposed on an inner peripheral side of the motor, wherein an armature coil (4) disposed on a stator (3) is provided. ) (Q1-Q6) for switching the current flowing through
The rotor (1) is integrally attached to the rotor (1) at a delay angle with respect to the field permanent magnet (2) attached to the rotor (1) at a delay angle at which resonance noise between the motor and the housing case is minimized. Sensor magnet (5) indicating rotation position of 1)
And a magnetic sensor (I) attached to the stator (3) and detecting a direction of a magnetic field by the sensor magnet (5).
C1 to IC3) and the detection of the change in the magnetic field direction from the magnetic sensors (IC1 to IC3), calculates the rotation speed of the rotor (1), and when the rotation speed reaches a predetermined constant speed,
An advancing control means (12a) for outputting an advancing amount for advancing control for advancing a delay angle of the sensor magnet (5) with respect to the field permanent magnet (2); and the magnetic sensors (IC1 to IC3). The timing control means (1) controls the current switching timing of the switching elements (Q1 to Q6) by performing the magnetic field direction change detection and the advance amount, and performing the advance control according to the advance amount.
2b). A brushless motor comprising: 2. The advance angle control means (12a) controls the amount of advance of the delay angle to be small when the rotation speed of the rotor (1) is low, and controls the amount of advance of the delay angle to be large when the rotation speed is high. The brushless motor according to claim 1, wherein the brushless motor is used. 3. The advance angle control means (12a) smoothly changes the advance amount of the delay angle according to the rotation speed of the rotor (1). A brushless motor. 4. The sensor magnet according to claim 1, wherein a plurality of pairs of north poles and south poles are arranged at an equal angle with respect to a rotation center of the rotor. 3. The brushless motor according to 3. 5. The magnetic sensor (IC1 to IC3)
5. The brushless motor according to claim 1, wherein a plurality of the brushless motors are arranged around the stator at an equal angle.