JPH07194173A - Fan motor - Google Patents

Abstract

PURPOSE:To miniaturize a fan motor so as to reduce the size of the indoor and outdoor units of a room air-conditioner and omit the mold of a fan motor mounted on the outdoor unit for protecting a substrate from rain water to reduce the cost of the fan motor. CONSTITUTION:In a fan motor for a room air-conditioner housing a rotor having permanent magnets and a stator in a case, a detector circuit 35 which detects the rotation of the rotor, peripheral circuit 15' which processes the output signal of the circuit 35, and inverters 1-6 which drive the rotor in accordance with the output signal of the circuit 15' are provided outside the motor case and the fan motor is electrically connected to the inverters. A neodymium magnet can be used for the magnets of the rotor. Since a printed circuit board, heat radiating fin, one-chip inverter, etc., are arranged outside the motor case, the fan motor can be miniaturized. In addition, no circuit is mounted on the printed board, the need of a waterproofing mold can be eliminated and the cost of the fan motor can be reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a motor suitable for driving a fan of a room air conditioner, and more particularly to a brushless motor capable of variable speed control.

[0002]

2. Description of the Related Art A high-voltage one-chip three-phase inverter (hereinafter referred to as a "high-voltage one-chip inverter" for controlling the rotation speed of a motor by directly using a voltage obtained by rectifying and smoothing a commercial AC voltage of 100 (V) as a power supply voltage. , Called a one-chip inverter) was developed. This one-chip inverter is extremely small compared to the conventional discrete inverter, and it can be built into the motor.

The element structure of this one-chip inverter is
As shown in FIG. 7A, polysilicon (Poly-S) is used.
Based on i), the area of each phase is partitioned into a high breakdown voltage by means of dielectric isolation, that is, the SiO ₂ phase, and a circuit for one phase is formed in each area. FIG. 7B is a plan view showing the layout of each element of this one-chip inverter. As is clear from this figure, six switching transistors 1 as main elements, a recovery diode 2 for turning off the switching transistor 1 connected between the collector and the emitter of each switching transistor 1, and each switching transistor 1 are turned on. , A logic circuit 6 for forming a switching signal for turning off, a drive circuit 3 for turning on / off each switching transistor 1 by this switching signal, and a current flowing through the switching transistor 1 are detected to prevent destruction of the IC due to overcurrent. The overcurrent protection circuit 5 for preventing and the internal power supply 4 circuit are integrated into one IC. I of this one-chip inverter
The size of the C element is 4.3 mm in the vertical direction and 5.8 mm in the horizontal direction.

In such a one-chip inverter,
As the switching transistor 1, a lateral IGBT (In
The newly developed high-speed diode, which can be realized in the same process as the lateral IGBT, has been adopted because the occupied area has been greatly reduced compared to the conventional power MOSFET by developing and adopting the simulated gate bipolar transistor. By significantly reducing the current, the switching loss of the switching transistor 1 due to the reverse recovery current is significantly reduced. In addition, by incorporating a power supply circuit, only one external power supply is required to drive the switching transistor 1, which is a power element, and by incorporating an overcurrent protection circuit 5, excessive current generated by load short-circuiting, etc. It is designed to prevent the destruction of the IC due to. Furthermore, the inverter frequency is higher than the audible frequency.
The frequency is set to kHz so that the noise of the motor can be significantly reduced.

FIG. 8 is a block diagram showing a conventional example of a fan motor using such a one-chip inverter. 1 is a switching transistor, 2 is a recovery diode, 3 is a drive circuit, 4 is an internal power supply circuit, 5 Is an overcurrent protection circuit, 6 is a logic circuit, 7A, 7B, 7C
Is a Hall element sensor, 8 is a sensor amplifier, 8a is an adjustment resistor for the sensor amplifier, 9 is a rotation speed signal forming circuit, 10 is a speed correction circuit, 11 is a PWM (pulse width modulation) signal forming circuit, and 12 is a starting current limiting circuit. , 13 is an oscillation circuit, 14 is a stator, 15 is the above-mentioned one-chip inverter, and 16 is an external power supply. As shown in FIG.
When a commercial AC voltage of (V) is applied, this external power source 16
DC voltage is applied to each circuit. This allows
The oscillation circuit 13 is activated and the PWM signal forming circuit 11 generates a PWM signal at a predetermined cycle. The logic circuit 6 is this PW
A three-phase switching signal is generated from the M signal, and the drive circuit 3 sequentially turns on and off the switching transistors 2 in accordance with the switching signal. As a result, a current flows in each coil provided in the stator 14 in a predetermined direction, the rotor (not shown) starts rotating, and the motor starts.

At the time of starting this motor, the starting current limiting circuit 1
2 is PW so that the starting current flowing through each switching transistor 2 does not become excessive based on the current detection result.
The duty ratio of the PWM signal is adjusted by controlling the M signal forming circuit 11.

The six switching transistors 1 are designated as Q ₁ , Q ₂ , Q ₃ , Q ₄ , Q ₅ , and Q _6, and the recovery diodes 2 connected to them are designated as D ₁ , D ₂ , D ₃ , and D _{4, respectively.} , D ₅ , D ₆
Then, the collectors of the switching transistors Q _{1 to} Q ₃ are connected to the + terminal of the external power supply 16, and the emitters of the switching transistors Q _{4 to} Q ₆ are connected to the − terminal of the external power supply 16. Further, the emitter of the switching transistor Q _{1 and} the collector of the switching transistor Q ₄ are connected to the first coil provided in the stator 14,
Hereinafter, the emitter of the switching transistor Q _{2 and} the collector of the switching transistor Q ₅ are connected to the second coil, and the emitter of the switching transistor Q _{3 and} the collector of the switching transistor Q ₆ are connected to the third coil.

The drive circuit 3 sequentially turns on the switching transistors Q ₁ , Q ₂ , and Q ₃ by 120 ° in terms of electrical angle, and also chops the PWM signals in units of 120 ° in terms of electrical angle, and sequentially turns on the switching transistor Q _4. ,
To turn on the Q _5, Q _6. The driving timing of the switching transistor Q ₁ to Q ₆ shown FIG. In the figure,
The switching transistor Q ₄ turns on and off with the same period and duty ratio as the PWM signal during the period from the latter half of the on period of the switching transistor Q ₂ to the first half of the on period of the switching transistor Q ₃ , and the switching transistor Q ₅ becomes the switching transistor Q ₃ From the latter half of the ON period of the switching transistor Q _{1 to} the _first half of the ON period of the switching transistor Q ₁ , and the switching transistor Q ₆ from the latter half of the ON period of the switching transistor Q ₁ to the first half of the ON period of the switching transistor Q ₂ . It turns on and off for the same period.

When the motor is started as described above, the Hall element sensors 7A, 7B and 7C detect the rotation of the rotor, and as shown by 7A, 7B and 7C in FIG. It produces a rotor position signal having a phase difference of 120 ° in angle and a width of 180 ° in electrical angle. These rotor position detection signals are amplified by the sensor amplifier 8 adjusted to a predetermined gain, processed such as waveform shaping, supplied to the logic circuit 6, and generated by one of the rotor position signals, for example, the Hall element sensor 7A. The rotor position signal is supplied to the rotation speed signal forming circuit 9, and the rotation speed signal representing the rotation speed of the rotor is formed by the frequency or cycle thereof. If the Hall element sensors 7A, 7B, and 7C are Hall ICs, the sensor amplifier 8 and the sensor amplifier adjusting resistor 8a are unnecessary. This rotation speed signal is supplied to the speed correction circuit 10 and compared with the rotation speed according to a speed command from the outside to form a speed correction signal corresponding to the difference between them. With this speed correction signal, PW
The duty ratio of the PWM signal output from the M signal forming circuit 11 is controlled. The logic circuit 6 receives the electrical angle 12 from the three-phase rotor position signal supplied from the sensor amplifier 8.
According to the commutation signal for sequentially turning on and off the switching transistors Q ₁ , Q ₂ , and Q _3, which are also 120 ° out of phase with each other at 0 °, the PWM signal forming circuit 11 having the timing relationship described in FIG. The same period as the PWM signal of
A switching signal having the same duty is formed and sent to the drive circuit 3.

Thus, the energization time of each coil provided in the stator is controlled according to the duty ratio of the PWM signal corrected by the speed correction signal from the speed correction circuit 10, and the rotation speed of the rotor is controlled by the external circuit. The speed is controlled so as to match the number of revolutions.

In this way, the rotation speed of the rotor is determined by the duty ratio of the PWM signal, and the rotation speed of the motor can be changed by changing this duty ratio.

FIG. 10 is an exploded perspective view showing an example of a conventional motor in which the one-chip inverter having the circuit structure shown in FIG. 8 is mounted. 17 is an upper case, 18 is a stator core, 19 is a coil, 20 is a shaft hole, 21A, 2
1B and 21C are supports, 22 is a shaft, 23A and 23
B is a bearing, 24 is a rotor, 25 is a printed wiring board, 2
6 is a heat sink, 27A, 27B and 27C are screws, 28 is a lead wire, 29 is a lower case, 30A, 30B, 30C, 3
Reference numeral 0D is a motor fixing hole, 31 is a drawing hole, 32 is a shaft hole, 33 is a screw, and 34A, 34B and 34C are motor fixing holes.

In the figure, a cylindrical stator core 18 having a coil 19 wound by a slot provided on the inner surface of the upper case 17 is fitted. A shaft hole 20 is provided at the center of the upper surface of the upper case 17, and a motor fixing hole 34A is provided from the lower end of the outer peripheral surface thereof.
34B and 34C (the other one is not shown) are provided. Further, on the outer peripheral portion of the lower surface of the stator core 18, support members 21A, 21B, 21C on a bar that protrude downward are fixed at equal intervals.

The outer peripheral surface of the rotor 24 is covered with a ferrite magnet having a thickness of about 2 mm, and the shaft 22 penetrating its center is integrated. A bearing 23A is fixed to a portion above the shaft 22, and a bearing 23B is also fixed to a lower end surface of the shaft 22. A printed wiring board 25, through which the shaft 22 penetrates, is arranged between the rotor 24 and the bearing 23B.

The lower case 29 is provided with a shaft hole 32 at the center of its bottom surface and an outlet 31 on its side surface, and motor fixing holes 30A, 30 at the outwardly projecting portions of its upper end.
B, 30C and 30D are provided.

The circuit shown in FIG. 8 is formed on the upper surface of the printed wiring board 25, and the Hall element sensors 7A, 7B,
7C, the one-chip inverter 15, etc. are mounted, and the heat dissipation plate 26 is arranged on the side surface of the printed wiring board 25 as the heat dissipation of the one-chip inverter 15. The terminals of the circuit conductor pattern of the printed wiring board 25 are connected to the lead wires 28.

The rotor 24 is inserted inside the stator core 18 together with the shaft 22, and the bearing 23A is attached to the upper case 1.
It is fixed to the inner upper surface of 7. By mounting the rotor 24, the upper portion of the shaft 22 passes through the shaft hole 20 of the upper case 17 and projects to the outside. The printed circuit board 25 is fixed to the support tools 21A, 21B, 21C protruding from the lower surface of the stator core 18 by screws 27A, 27B, 27C. The lower case 29 is attached to the upper case 17 so as to seal the printed circuit board 25, the stator core 18, and the like. This attachment is performed by the motor fixing hole 34 of the upper case 17.
Lower case 2 in A, 34B, 34C, 34D (not shown)
It can be fixed by aligning the motor fixing holes 30A, 30B, 30C and 30D of 9 and tightening the screw 33 through these holes. In this case, the bearing 23B at the lower end of the shaft 22 is fixed in the shaft hole 32 of the lower case 29, and the lead wire 28 is led out from the inside of the lower case 29 through the outlet 31.

FIG. 11 is a back electromotive force position detection circuit diagram, and FIG.
2 shows the waveform of each part of the counter electromotive force position detection circuit. The point where the emitter of the switching transistor Q _{1 and} the collector of the switching transistor Q ₄ are connected to the first coil provided in the stator 14 is A, and the emitter of the switching transistor Q _{2 and} the collector of the switching transistor Q ₅ are second. The point connected to the coil is B, and the point where the emitter of the switching transistor Q _{3 and} the collector of the switching transistor Q ₆ are connected to the third coil is C.
And At points A, B, and C, the number 1 due to the back electromotive force is
Since the voltage of 00V is generated, the resistance of R1 and R2 and C1
The voltage is divided by a low-pass filter consisting of a capacitor of, and a triangular wave with a phase delayed by 90 ° like point D is created. Point B,
A triangular wave with a phase delayed by 90 ° is also created at point C, but points A, B, and C are waveforms with a phase shift of 120 °. This waveform is combined by the resistors R4, R5, and R6 for the three phases to form a composite wave like the voltage at point E. This composite wave has a waveform three times as long as the original triangular wave. There is. A voltage comparison between the D point voltage waveform and the E point voltage waveform is performed by a comparator, and a rotor position detection signal having an electrical angle of 180 ° width such as the F point voltage is obtained. This signal is the same as the rotor position detection signal output from the Hall element or Hall IC. Such a back electromotive force position detection circuit is already used in a drive inverter of a room air conditioner compressor equipped with a DC motor.

[0019]

When a one-chip inverter is built in a fan motor as a motor drive circuit,
Since a high power element such as a switching transistor serves as a heating element, the temperature of the one-chip inverter becomes high, and there are adverse effects such as deterioration of characteristics and deterioration of reliability. Therefore, it is necessary to provide a radiation fin on the one-chip inverter. However, even if the one-chip inverter is small,
When the heat radiation fin, the hall element, and the printed circuit board are housed in the motor case, the size of the motor is inevitably increased. In recent room air conditioners, indoor and outdoor units are downsized, and fan motors are also required to be downsized. However, there is a problem that the motor case for the drive circuit becomes large. Further, with respect to the fan motor mounted in the outdoor unit, it is necessary to mold the entire substrate in order to protect the substrate from rain, which also leads to an increase in cost.

Further, the Hall IC converts the magnetic flux of the rotor into a voltage to detect the position of the rotor. However, if the gap with the magnet in the rotor is large, the magnetic flux detection becomes difficult. Further, when the positional relationship between the three Hall ICs and the stator winding is deviated, the rotation signal supplied from the stator winding and the magnetic poles of the magnets in the rotor do not match, and the phases are deviated so that the magnetizing position of the normal magnet is shifted. May not be energized, resulting in drive failure or reduced efficiency. Therefore, when mounting the Hall IC, it is difficult to manage the manufacturing process.

The counter electromotive force position detection circuit differs from the Hall element or Hall IC in that if the Hall element is used when the motor is started, even if the rotor is not rotating, the position of the magnet of the rotor is signaled in advance. Since it is input to the rotation speed signal forming circuit as described above, it can be started by inputting each signal of Q _{1 to} Q ₆ described in FIG. 7 to the switching transistor 2. However, the position detection circuit 35 is a method of detecting the position of the rotor by the back electromotive force generated in the winding of the stator. Therefore, since the rotor is not rotating at the time of start-up, the counter electromotive force is not generated, and it is not known at what timing the signals Q _{1 to} Q ₆ shown in FIG. 9 should be input to the switching transistor 2.

Further, the back electromotive force position detection circuit is used in a room air conditioner compressor equipped with a DC motor, but the load rising curve at start-up is constant. However, in the case of the fan motor, the inertia and load fluctuation of the motor are larger than those of the compressor, and the synchronous operation control at the same start-up as the compressor causes step out and stops.

[0023]

In order to solve the above-mentioned problems, the present invention arranges only a rotor having a permanent magnet and a stator in a motor case to miniaturize the motor and detects the rotational position of the rotor. A detection circuit, a peripheral circuit that processes the output signal of the detection circuit, and a one-chip inverter that rotationally drives the rotor according to the output signal of the peripheral circuit are arranged outside the case, and the fan motor and the one-chip inverter are electrically connected. Connect to.

Further, if the Hall element is used for detecting the rotor position, the printed circuit board or the substrate on which the Hall element is mounted must be molded, resulting in cost increase. Therefore, the Hall element sensor is used as a means for detecting the rotor position. A back electromotive force position detection circuit that does not require is used.

Further, during the synchronous operation at the time of starting the fan motor, the phase difference between the drive signal and the position detection signal of the actual rotation speed detected by the back electromotive force is compared, and the increase time of the rotation speed is changed according to the phase difference. Inverter control means is provided.

[0026]

A detection circuit for detecting the rotational position of the rotor, a peripheral circuit for processing the output signal of the detection circuit, and a one-chip inverter for rotationally driving the rotor according to the output signal of the peripheral circuit are arranged outside the case, By arranging only the rotor and the stator in the motor case, the size of the motor can be reduced. In addition, by using the counter electromotive force position detection circuit that does not require the Hall element sensor as the rotor position detection means, the substrate and the substrate mold in the motor are removed, and the conventional Hall IC positioning setting becomes unnecessary. Cost reduction can be achieved.

[0027]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIG. FIG. 1 is a circuit block diagram. A position detection circuit 35 that detects the rotational position of the rotor, a rotation speed setting circuit 36 that processes the output signal of the position detection circuit 35, and the rotor is rotated according to the output signals of the peripheral circuits. It is composed of a one-chip inverter 15 'that is driven. The basic circuit operation is to detect the position of the rotor by the back electromotive force generated in the stator winding and input the signal to the rotation speed setting circuit 36 as an output signal of the position detection circuit 35. In the rotation speed setting circuit 36, the target rotation speed is compared with the actual rotation speed obtained by the position detection circuit 35. If the target rotation speed is not reached, a voltage corresponding to the difference between the rotation speeds is set. It is input to the PWM forming circuit 11 of the one-chip inverter 15 ', and the rotation speed is corrected so that the target rotation speed is obtained. Further, the rotation speed setting circuit 36 inputs the signal of the position detection circuit 35 to the logic circuit 6 of the one-chip inverter 15 '. A microcomputer may be used as the rotation speed setting circuit 36.

As described in the conventional example, even if the rotor is not rotating if the Hall element is used at the time of starting the motor, the position of the magnet of the rotor is previously input as a signal to the rotation speed signal forming circuit. 7A, 7B described in 8,
Enter the rotor position signal of the Hall IC sensor 7C to the logic circuit 6 of the one-chip inverter 15 ', it could be activated by entering from the logic circuit 6 to each signal of Q ₁ to Q ₆ to the switching transistor 2. However, the position detection circuit 35 is a method of detecting the position of the rotor by the back electromotive force generated in the winding of the stator. Therefore, since the rotor is not rotating at the time of startup, the counter electromotive force is not generated and it is not known at what timing the signals Q _{1 to} Q ₆ shown in FIG. 8 should be input to the switching transistor 2.

FIG. 2 shows a starting pattern diagram. First, since the DC motor has a starting torque, it is necessary to supply a starting current equal to or higher than the starting torque between the two phases of the stator at the time of starting. This time depends on the time constant determined by the resistance and inductance constants of the stator winding of the motor, but there is no problem if it is about 300 ms. After that, since the DC motor using the permanent magnet is also a synchronous machine, the signals of Q _{1 to} Q ₆ shown in FIG. 8 are gradually input to the switching transistor 2 in the stator winding wound in three phases. Then, the rotor rotates in synchronization with the cycle. When rotating to some extent, the counter electromotive force described in FIG. 11 is generated in each phase, and a position detection signal is obtained. Therefore, if the synchronous operation is switched to the position detection operation by the back electromotive force when a sufficient position detection signal is obtained, stable rotation speed control becomes possible.

Conventionally, the compressor for controlling the number of revolutions equipped with a DC motor uses the above-mentioned counter electromotive force position detection circuit.
Since the load increase at startup of the compressor is a constant curve proportional to the number of revolutions, the acceleration of the number of revolutions at the time of synchronous operation was, for example, 350 revolutions / sec. However, in the case of a fan motor, since the load is blades or a sirocco fan, inertia and load fluctuations are large, and the motor does not follow up and stops in the same rotational speed acceleration time during synchronous operation as the compressor, and stops.

FIG. 3 shows the phase difference between the drive signal and the back electromotive force and the triangular wave waveform in the position detection circuit. The drive signal waveform is shown by a solid line, the back electromotive force waveform (induced voltage waveform) is shown by a dotted line, the triangular wave obtained from the drive signal is shown by a solid line, and the triangular wave obtained from the back electromotive force is shown by a dotted line. Here, the drive signals are Q _{1 to} Q shown in FIG. 9 for driving the switching transistors in the drive circuit 3 from the rotor position signal input to the logic circuit 6 of the one-chip inverter 15 ′ from the rotation speed setting circuit 36 during the synchronous operation. ₆ signals.
(A) shows the case where the phase of the back electromotive force and the drive signal match, (b) shows the case where the phase of the back electromotive force is behind the drive signal, and (c) shows the back electromotive force of the drive signal. The waveform when the phase is advanced is shown. When the phase of the back electromotive force coincides with the phase of the drive signal of (a), the phase of the triangular wave coincides, but the phase of the back electromotive force is delayed with respect to the drive signal as shown in (b). In this case, the phase of the counter electromotive force of the triangular wave is also delayed by α. When the phase of the counter electromotive force is advanced with respect to the drive signal in (c), the phase of the counter electromotive force is similarly advanced by β. Therefore, when α and β are deviated from each other by an electrical angle of 60 ° or more, a step out occurs and the motor stops. FIG. 4A shows a starting characteristic at the time of phase correction, and FIG. 4B shows a starting characteristic without phase correction. Without phase correction, as shown in Fig. 4 (b), the rotation of the motor is caused by the fact that the phase of the back electromotive force does not match the drive signal immediately after the motor starts to rotate and the fan motor load fluctuates. The number rises erratically. Eventually the phase difference α
Or β increases with time and becomes an electrical angle of 6
The point deviated by 0 ° or more is t2. Although this point is the step out point, since the load of the fan motor is the blade or the sirocco fan, the fan motor has a large inertia and rotates by inertia until t3, and then stops. Therefore, as shown in FIG. 4A, if the phase amount of the delay or lead of the back electromotive force phase with respect to the drive signal is detected and the phase correction is performed so as to change the increase time of the rotation speed according to the phase amount, the load It can be driven without stopping even if there is a fluctuation in the value or the inertia of the fan.

FIG. 5 shows a flow chart of the phase correction control. First, it is detected whether or not there is a phase difference between the drive signal and the back electromotive force, and if there is no phase difference, the rotation speed is increased according to a preset rotation speed acceleration rate. If there is a phase difference, it is detected whether the back electromotive force is behind or ahead of the drive signal. If it is advancing, the amount of advance phase is detected, and control is performed to increase the rotation speed acceleration rate according to the amount of advance phase.
This control can be performed by increasing the cycle of the position detection signal input from the rotation speed setting circuit 36 to the logic circuit 6 of the one-chip inverter 15 '. At this time, the rotation speed command voltage input from the rotation speed setting circuit 36 to the PWM forming circuit 11 of the one-chip inverter 15 ′ may be a preset voltage, but may be increased according to the lead phase amount. If it is delayed, the delay phase amount is detected, and the rotational speed acceleration rate according to the delay phase amount is controlled to be lowered. This control can be performed by lowering the cycle of the position detection signal input from the rotation speed setting circuit 36 to the logic circuit 6 of the one-chip inverter 15 '.

FIG. 6 shows the phase and gain characteristics of the position detection circuit. Based on the position detection circuit of FIG.
Ω, R2 47 kΩ, C1 1.5 μF, C2 2.2
When μF is used and the phase characteristics are calculated, it is 20 at 500 rotations.
The phase advances by 12 °, and advances by 12 ° at 1000 revolutions. Therefore, even if a phase difference occurs between the drive signal and the back electromotive force and the phase is corrected, the phase created from the back electromotive force in the position detection circuit is advanced, so the phase accompanying the phase difference between the regular drive signal and the back electromotive force No correction is made. So R1, R
The constants of 2, C1 and C2 are changed to change to a circuit in which the phase does not advance even at low speed rotation, or the rotation speed setting circuit 36 performs control to correct the lead phase at each rotation speed of the position detection circuit. By doing so, even if there is a change in load or inertia of the fan, driving can be performed without stopping. In the present embodiment, the configuration of the position detection circuit of FIG. 11 is the first-stage filter of R1, R2, C1 and the second-stage filter of C2, R4. You may insert a circuit and perform high frequency cutting with a chopper.

The main magnet for the rotor is usually ferrite or a mixture of ferrite and plastic, but a neodymium magnet having a high magnetic flux density may be used.

[0035]

As described above, according to the present invention, since only the rotor and the stator are housed in the motor case, the space for accommodating the conventional printed circuit board, heat radiation fins, one-chip inverter, etc. is eliminated, and the motor is miniaturized. it can.
Further, since there is no circuit to be mounted on the printed circuit board, a mold for waterproofing due to rain is not required and cost can be reduced. Further, if a neodymium magnet having a high magnetic flux density is adopted as the magnet of the rotor, the size of the motor can be further reduced.

[Brief description of drawings]

FIG. 1 is a block diagram of a fan motor drive circuit according to an embodiment.

FIG. 2 is a starting pattern diagram of the fan motor drive circuit according to the embodiment.

FIG. 3 is a waveform diagram showing a phase difference between a drive signal and a back electromotive force of the fan motor drive circuit and a triangular wave waveform in the position detection circuit according to the embodiment.

FIG. 4 is a graph diagram showing a starting characteristic at the time of phase correction and a starting characteristic without a phase correction of the fan motor drive circuit according to the embodiment.

FIG. 5 is a flowchart of phase correction control of the fan motor drive circuit according to the embodiment.

FIG. 6 is a graph showing the phase and gain characteristics of the position detection circuit of the fan motor drive circuit according to the embodiment.

FIG. 7 is a diagram showing an element structure of a conventionally known one-chip inverter and a layout of the one-chip inverter element.

FIG. 8 is a circuit diagram showing an example of a fan motor using a conventionally known one-chip inverter.

FIG. 9 is a drive timing chart of switching transistors Q _{1 to} Q ₆ .

FIG. 10 is an exploded perspective view of a conventional motor mounted with a one-chip inverter.

FIG. 11 is a circuit diagram of a position detection circuit diagram.

FIG. 12 is a waveform chart of each part of the position detection circuit.

[Explanation of symbols]

 1 Switching Transistor 2 Recovery Diode 3 Drive Circuit 4 Internal Power Supply Circuit 5 Overcurrent Protection Circuit 6 Logic Circuit 11 PWM (Pulse Width Modulation) Signal Forming Circuit 12 Starting Current Limiting Circuit 13 Oscillation Circuit 14 Stator 15 'New One-Chip Inverter 16 External Power Supply 17 Upper Case 18 Stator Core 19 Coil 22 Shaft 23A, 23B Bearing 24 Rotor 25 Printed Wiring Board 29 Lower Case 35 Position Detection Circuit 36 Rotation Speed Setting Circuit

Claims (2)

[Claims] 1. A back electromotive force position detection circuit for detecting a rotational position of a rotor by a back electromotive force generated in a stator winding in a fan motor including a rotor having a permanent magnet and a stator in a case, and the detection. A peripheral circuit that processes an output signal of the circuit and an inverter that controls the rotational drive of the rotor according to the rotor position signal and the rotational speed command voltage output from the peripheral circuit are arranged outside the case, and the fan motor At the time of synchronous operation at the time of start-up, an inverter control means for comparing the phase difference between the drive signal and the position detection signal of the actual rotation speed detected by the back electromotive force and changing the increase time of the rotation speed according to the phase difference is provided. A fan motor characterized by that. 2. The inverter according to claim 1, wherein the inverter is
A fan motor, which is a one-chip inverter formed into a monolithic IC.