JPS62201047A - Brushless motor - Google Patents

Abstract

PURPOSE:To obtain a small-sized, thin-type brushless motor of low cost, by installing an intergrated circuit monolithically containing a motor control circuit and a portion detecting sensor to the position corresponding to an electric angle necessary for commutation. CONSTITUTION:To a print substrate 15 integrally provided to a stator core 11 an integrated circuit 21 where a Hall sensor and a motor control circuit are built in is installed so as to position at an electric angle just necessary for commutation. The above-mentioned Hall sensor detects the position of a rotor magnet 22 provided face to face a stator coil 12. A motor control circuit feeds a drive current selectively to each phase of the stator coil 12 in accordance with the position of the rotor magnet 22 thus detected. At the same time, it controls the torque equivalently impressed to the rotor magnet 22 so as to work in the same rotating direction at all times and to continue the rotation. Consequently, the number of parts can be reduced as a drive circuit of the stator coil 12 need not be made as a separate entity.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Field of Application) The present invention relates to a brushless motor that generally has a small starting torque and is mainly used for constant speed rotation, and particularly relates to an integrated circuit with a built-in Hall element. Incorporate into the motor to make it smaller i
This invention relates to a J-shaped brushless motor.

(Prior Art) In recent years, with the spread of ultra-compact and thin headphone stereos, compact integrated video cameras, and the like, flat, low-cost motors have been required. A flat brushless motor is essential in the form up to authority, but with the conventional concept, an increase in cost was unavoidable.

The simplification and cost reduction of the brushless motor system is achieved by devising the W magnetism of the rotor magnet, although it is a two-phase half-wave motor with one Hall element, as seen in, for example, U.S. Patent No. 4,211,963. There are motors that are cleverly designed to prevent the occurrence of a dead center where the torque becomes zero. However, even though there is only one Hall element, a complicated electronic circuit is still provided separately to control the motor, and it has not reached the point where it can compete with brushed motors in terms of cost.

FIG. 3 shows an example of such a conventional brushless motor system, in which three sets of two-phase stator coils 12 are installed in the stator body 11, six in total. Further, a Hall element 13 for position detection is also attached to the stator main body 11. Such a stator body 11
is connected to the stator coil 1 via seven wires 14.
It is electrically connected to the electronic circuit board 15 on which the second drive circuit is configured.

The breakdown of the seven wires 14 is as follows:
2 for current supply to the Hall element 13,
There are two for the Hall voltage detection signal. The electronic circuit board 15 includes an integrated circuit 16 for a motor control circuit constituting a drive circuit for the stator coil 12, and a semi-fixed resistor 17 for speed adjustment. and some chip parts 18 are installed. The chip components 18 are chip power transistors, resistors, capacitors, etc. Note that 19 in the figure is a leader line for power supply. Further, although not particularly illustrated, a rotor magnet magnetized into, for example, six poles is provided opposite the stator coil 12.

In a brushless motor having such a configuration, a commutation timing signal is obtained by the Hall element 13 for detecting a magnetic field, and rotational torque is obtained by alternately turning on and off each phase of the stator coil 12. The Hall element 13 for detecting the magnetic field is made of germanium (Ge), silicon (Si), indium antimonide (InSb), indium arsenide (InAs), etc., and as in the above-mentioned configuration, the stator coil 12 It was provided separately from the drive circuit.

As described above, the conventional brushless motor system is quite complex and has a considerable difference in cost compared to the conventional brushed motor, making it difficult to adopt it in the popular set described above. Further, since the electronic circuit section required the area of the substrate 15, it was difficult to miniaturize the device.

In addition, sensorless systems that do not have special position sensors such as Hall elements currently exist, and although they are seen as promising in terms of cost, they require time to position during startup, and have some problems with the motor's startup characteristics. Because of this, its uses are limited. This system uses the induced electromotive force generated by the coil itself to detect the rotor position.
When the rotor is stopped, there is no way to detect its position, and the above-mentioned starting operation is required.

(Problems to be solved by the invention) The present invention has been made in view of the above points.
This provides a low-cost brushless motor.

[Structure of the Invention] (Means for Solving the Problems) That is, in the brushless motor according to the present invention, the above-mentioned structure of the substrate integrally provided in the main body to which at least two-phase stator coils are attached is provided. At a position where the relative positional relationship with the stator coil corresponds to the electrical angle required for commutation,
It is equipped with a monolithic integrated circuit that includes a motor control circuit and a sensor for position detection.

(Function) In the brushless motor configured as described above, the position detection sensor of the integrated circuit chip detects the position of the rotor magnet, and the motor control circuit detects the position of the rotor magnet detected by the sensor. A driving current is selectively applied to each phase of the stator coil according to the position of the magnet, and the rotor magnet is controlled so that the torque equivalently applied to the rotor magnet always acts in the same direction of rotation to continue rotation. Therefore, there is no need to configure the drive circuit for the stator coil separately, and the number of parts can be reduced.

(Example) An example of the present invention will be described below with reference to the drawings. 1st
The figure shows its configuration, and a stator body 11 is equipped with two-phase stator coils 12 in which every other winding is connected in series. Further, a printed circuit board 15 is integrally provided on the stator main body 11. An integrated circuit 21 sealed in a flat package is mounted on this substrate 15. This integrated circuit 21 has a built-in Hall sensor, and the chip is mounted on the substrate 15 so as to be at exactly the electrical angle position required for commutation.

The lead frame of this integrated circuit 21 is made of a non-magnetic material so as not to generate torque unevenness. On the chip of this integrated circuit 21 are a Hall element for magnetic field detection and an amplifier for amplifying the Hall voltage.

A power transistor, a detection circuit for an induced voltage proportional to the speed from the stator coil 12, a reference voltage generator, a voltage comparator, etc. are integrated. The substrate 15 also includes:
A semi-fixed resistor 17 for speed adjustment and an external chip capacitor 18 are also installed. Note that 19 in the figure is a lead wire for power supply and grounding.

Also, facing the stator coil 12, as shown in FIG.
As shown in the figure, the rotor magnet 1 is magnetized into 6 poles.
-22 is provided. This rotor magnet 22 is partly specially magnetized to avoid torque dead center, but since the principle is based on US Pat. No. 4,211,963, etc., it will not be discussed here. In addition, the same figure (
b) The middle 23 is a back plate configured to rotate together with the rotor 22, and is made of a material with high magnetic permeability.

If power is supplied to the brushless motor having such a configuration from the lead wire 19, the speed adjustment semi-fixed resistor 1
The motor rotates at the speed set by 7.

FIG. 2 is a diagram showing an internal equivalent circuit of the integrated circuit 21. In the figure, 30 is a Hall element formed within the integrated circuit 21, and 31 is a diode that serves both to optimize the bias of the transistor and to compensate for the temperature of the Hall element 30.

32 is a gain amplifier including a positive feedback circuit as disclosed in Japanese Patent Publication No. 53-17029, which amplifies the Hall voltage. 33 is a relay amplifier that further amplifies the Hall voltage, but here it is already in switching operation. The operating current is determined by the output of a voltage comparator 34, which will be described later.

35 and 36 are power transistors, and stator coils 12. , 122 are driven alternately. 37 is a constant current power supply section. This is a feedback type constant current circuit,
Its value is determined by the thermal voltage and resistance caused by the difference (ratio) in current density of the transistors.

This constant current circuit 37 is designed to ensure that the operation starts.
Contains starter circuit.

34 is a voltage comparator, which compares the potential difference between the reference voltage from the reference voltage generator (point 38) and point 39, which generates a voltage proportional to the induced voltage from the stator coil 12, until the potential difference becomes zero. A feedback circuit is formed so that The semi-fixed resistor 17 for speed adjustment and the smoothing capacitor 181 are connected to the point 39 outside the integrated circuit 21.

Further, 40 is an induced voltage detection section of the stator coil 12. The coil 12 is connected to the power transistors 35 and 3.
6 is off, and when no current flows through the coil 12, a current proportional to the induced voltage is derived and supplied to the point 39. This detection section 40 uses a lateral PNP transistor with a high VBE reverse breakdown voltage so that the VBH reverse breakdown voltage does not become a problem.

The capacitor 182 is for limiting the frequency characteristics of the speed control loop to suppress oscillation. This is an external component that may not necessarily be required depending on the loop gain setting.

The transistor 41 has a thermal shutdown-like function. Chip temperature can be detected with a simple configuration of just one element. That is, the voltage applied between the pace emitters is a voltage proportional to the thermal voltage VT, and has a temperature characteristic of about +0.4%/°C. Also, since the VBE of the transistor has a temperature characteristic of about -2 mV/'C1, or about -0.3%/°C, it is equivalently 0.4+0.3-0.7%/°C. The temperature gradient will be detected, and the temperature detection sensitivity is high. The detection point to which the base is connected uses the voltage across the emitter resistor of the starter circuit of the constant current source mentioned above, so the number of elements can be reduced without disturbing the starter circuit's grip, which is cut off except during startup. can.

By adopting such a circuit configuration, an integrated circuit circuit with fewer external components can be constructed. Therefore, the motor can be made ultra-small, thin, and low-cost, making it possible to achieve a cost comparable to the conventional combination of a brushed motor and an electronic governor. In addition, since there is no unstable brush, assembly is easy without special know-how, there is little variation in rotational speed over time due to brush wear, etc., and the product has a long life.

[Effect of the invention] As detailed above, according to the present invention, the device is small.

It can be made thin and low cost.

[Brief explanation of drawings]

FIG. 1 shows the configuration of a brushless motor according to the present invention, in which (a) is a plan view, (b) is a side view, and FIG. 2 is a concrete diagram of an integrated circuit applied to the brushless motor of the present invention. The internal equivalent circuit diagram, FIG. 3, is a diagram showing a conventional brushless motor. DESCRIPTION OF SYMBOLS 11... Stator main body, 12... Stator coil, 15... Printed circuit board, 21... Integrated circuit chip, 22... Rotor magnet.

Claims (1)

[Claims] a stator coil of at least two phases; a multi-pole magnetized rotor magnet disposed opposite to the stator coil; and a drive current selectively applied to each phase of the stator coil depending on the position of the rotor magnet. Along with flowing,
The rotor magnet is equipped with an integrated circuit chip in which a position detection sensor and a motor control circuit are monolithically integrated to control the rotor magnet so that the torque equivalently applied to the rotor magnet always acts in the same direction of rotation and continues rotation; The integrated circuit chip is arranged at a position where the relative positional relationship with the stator coil of a circuit board provided integrally with the main body to which the stator coil is attached corresponds to each electrical position necessary for commutation. A brushless motor featuring