JPH05137375A - Brushless motor - Google Patents

Abstract

PURPOSE:To variably control in ON/OFF duty of a PWM signal a rotating speed of a motor even if a DC voltage to be externally supplied is constant by providing PWM signal generating means, speed error signal generating means, and high speed switching means. CONSTITUTION:An output signal of a rotor position sensor 6 is logically processed by commutation signal generating means 9, and output to a switching power element 7. Simultaneously, a rotating speed command signal received externally by speed error signal generating means 4 is compared with a rotating speed signal obtained from a speed sensor 5 to obtain a speed error signal. An ON/OFF duty PWM signal responsive to the error signal is generated by the means 2 in a high frequency, and high speed switching means 3 switches a constant DC voltage to be externally supplied in response to the PWM signal. Smoothing means 1 smoothes the switched DC voltage, applies the voltage to the element 7 and varies the speed of a brushless motor.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a brushless motor used as a drive source for a blower fan of a home air conditioner or the like.

[0002]

2. Description of the Related Art In recent years, in air conditioners such as home air conditioners, it has become mainstream to control the capacity of a compressor. Correspondingly, it is also required to adjust the amount of air blown to the heat exchanger in a wide variety of stages. In place of the induction motor as a fan drive source that has been conventionally used to satisfy these demands, speed adjustment is required. A method of operating an easy brushless motor with a DC power supply is adopted. On the other hand, there is a strong demand for a lighter, thinner and smaller motor of this type. A conventional brushless motor drive system has the configuration shown in the block diagram of FIG. 3, and a brushless motor A having a built-in drive circuit is driven by a DC power supply B such as a switching power supply and is rotated by varying the output voltage of the DC power supply B. The speed is variable.

[0003]

However, in the above-mentioned conventional configuration, a DC power source of variable voltage is required to drive the brushless motor, which hinders the space saving of the drive system for the consumer of the brushless motor. It is a factor. Further, even if the cost of the motor is suppressed to the minimum, the total cost becomes higher than that of the conventional induction motor because of that.

The present invention solves the above-mentioned conventional problems, and an object of the present invention is to provide a brushless motor that saves space and costs by incorporating a portion for varying the voltage of the DC power supply into the motor.

[0005]

In order to achieve the above object, a brushless motor of the present invention, a printed wiring board on which a drive circuit and a control circuit are mounted, a stator winding, and a rotor position sensor are electrically insulated. A stator and a permanent magnet rotor are integrally formed of a synthetic resin, and the drive circuit includes a switching power element section for switching the motor current and a means for generating a signal for driving the switching power element section. Means for obtaining a speed error signal by comparing the rotation speed command signal with a rotation speed signal obtained from a rotor position sensor or a separately provided speed sensor, and an on-off duty PWM (pulse width modulation) signal according to the speed error signal Means, a means for switching a DC voltage supplied from the outside according to the PWM signal, and a switched DC power source. Smoothing to and a means for applying to the switching power element portion.

[0006]

With the above structure, the rotation speed of the motor is PW even if the DC voltage supplied from the outside is constant.
It can be varied by controlling the on / off duty of the M signal.

[0007]

(Embodiment 1) A first embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a system block diagram of a brushless motor according to a first embodiment of the present invention. In FIG. 1, reference numeral 1 is a smoothing means composed of a smoothing diode D1, a smoothing capacitor C1 and a smoothing coil L1, 2 is a PWM signal generating means, 3 is a high speed switching means, 4 is a speed error signal generating means, and 5 is a speed. A sensor, 6 is a rotor position sensor, 7 is a switching power element unit consisting of 6 switching power elements and 6 diodes reversely connected to each, 8 is a switching power element driving means, and 9 is a commutation signal generation. Means 10 is a drive signal generating means comprising a switching power element driving means 8 and a commutation signal generating means 9, and 11 is a control comprising a smoothing means 1, a PWM signal generating means 2, a high speed switching means 3 and a speed error signal generating means 4. A circuit, 12 is a drive circuit including a switching power element section 7 and a drive signal generating means 10. In the figure, the portion A on the right side is the portion inside the motor integrally molded with resin, and the portion B on the left side is the portion outside the motor.

With the above configuration, the output signal of the rotor position sensor 6 is logically processed by the commutation signal generating means 9, and the output signal is transmitted to the switching power element driving means 8 to send the commutation signal to the switching power element section 7. The speed error signal is output and the speed error signal is obtained by comparing the rotation speed command signal received from the outside by the speed error signal generating means 4 with the rotation speed signal obtained from the speed sensor 5, and the speed error signal is generated by the PWM signal generating means 2. A PWM signal with an on-off duty corresponding to the signal is generated at a high frequency, the high speed switching means 3 switches a constant DC voltage supplied from the outside according to the PWM signal, and the smoothing means 1 smoothes the switched DC voltage. By applying the voltage to the switching power element section 7, the speed of the brushless motor is changed. The rotation speed signal can be obtained by combining the output of the rotor position sensor 6 instead of the speed sensor 5.

Second Embodiment Next, a second embodiment of the present invention will be described with reference to the drawings. FIG. 2 is a system block diagram of the brushless motor of the second embodiment of the present invention. The same members as those in FIG. 1 are designated by the same reference numerals and the description thereof will be omitted. Reference numeral 13 is a drive voltage control means which replaces the speed error signal generation means 4 of FIG. With this configuration, the output signal of the rotor position sensor 6 is logically processed by the commutation signal generation means 9, the output signal is transmitted to the switching power element drive means 8, and the commutation signal is output to the switching power element section 7. The drive voltage control means 13 compares the drive command signal received from the outside with the voltage applied to the switching power element section 7 to obtain an error signal, and the PWM signal generation means 2 turns on / off the PWM signal according to the error signal. The duty is changed, the direct-current voltage supplied from the outside is switched at high speed by the high-speed switching means 3 according to the PWM signal output, and the smoothed direct-current voltage is applied to the switching power element section 7. By doing so, the speed of the brushless motor can be changed.

[0010]

As described above, the following effects can be obtained by using the configuration of the present invention. (1) Since the customer side does not need a variable voltage DC power supply for driving the motor, space saving and cost reduction of the system can be realized.
(2) Since the size of the smoothing capacitor and the smoothing coil can be reduced by increasing the frequency of the PWM signal, the circuit can be built in the motor.

[Brief description of drawings]

FIG. 1 is a system block diagram of a brushless motor according to a first embodiment of the present invention.

FIG. 2 is a system block diagram of a brushless motor according to a second embodiment of the present invention.

FIG. 3 is a system block diagram of a conventional brushless motor.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 smoothing means 2 PWM signal generating means 3 high speed switching means 4 speed error signal generating means 5 speed sensor 6 rotor position sensor 7 switching power element section 8 switching power element driving means 9 commutation signal generating means 10 drive signal generating means 11 control Circuit 12 Drive circuit 13 Drive voltage control means

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yuji Dohi 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (72) Sosei Yamamoto, 1006 Kadoma, Kadoma City, Osaka Matsushita Electric Industrial Co.

Claims (3)

[Claims] 1. A printed wiring board on which a drive circuit and a control circuit are mounted, a stator winding, and a rotor position sensor are integrally formed of synthetic resin having electrical insulation, and a stator and a permanent magnet rotor are provided. The drive circuit includes a switching power element unit that switches the motor current and a unit that generates a signal for driving the motor power, and the control circuit uses a rotation speed command signal input from the outside and a rotor position sensor or a speed sensor separately provided. A means for obtaining a speed error signal by comparing the obtained rotation speed signal, a means for generating a PWM (pulse width modulation) signal with an on-off duty according to the speed error signal, and a DC voltage supplied from the outside according to the PWM signal And a means for smoothing the switched DC voltage and applying it to the switching power element section. Brushless motor. 2. A printed wiring board on which a drive circuit and a control circuit are mounted, a stator winding, and a rotor position sensor are integrally formed of synthetic resin having electric insulation, and a stator and a permanent magnet rotor are provided. The drive circuit includes a switching power element unit for switching the motor current and a unit for generating a signal for driving the motor power unit, and the control circuit has an on-off duty PW corresponding to a rotation speed command signal input from the outside.
A brushless motor having means for generating an M signal, means for switching a DC voltage supplied from the outside according to a PWM signal, and means for smoothing the switched DC voltage and applying the smoothed DC voltage to the switching power element section. .. 3. A means for changing the ON / OFF duty of the PWM signal according to an error signal obtained by comparing a DC voltage applied to the switching power element section with a rotation speed command signal input from the outside. Item 2. The brushless motor according to item 2.