JP2014023285A - Normally and reversely rotatable dc brushless motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To inexpensively provide a single-phase full-wave rectification type or two-phase half-wave rectification type DC brushless motor normally and reversely rotating by a DC current by a simple control.SOLUTION: A single-phase full-wave rectification type or two-phase half-wave rectification type DC brushless motor is provided with: a position sensor detecting a magnetic pole position of a magnet that is a rotor; and two output paths for a magnetic pole detection signal from the position sensor to a switching element. The DC brushless motor controls on/off of a switching element by an output of the magnetic pole detection signal from the position sensor to change an electric conduction direction to a coil wound around a stator. In the DC brushless motor, an output path for the magnetic pole detection signal is preliminarily defined for an S-pole or N-pole magnetic pole signal detected firstly by the position sensor after electric conduction, and a switching mode control circuit outputting a signal for determining the output path for the magnetic pole detection signal on the basis of the magnetic pole signal. The DC brushless motor switches the output path for the magnetic detection signal on the basis of the signal outputted from the switching mode control circuit to determine a rotation direction of the rotor, and can normally and reversely rotate.

Description

  The present invention relates to a single-phase full-wave rectification type or two-phase half-wave rectification type DC brushless motor that rotates in both forward (CW) and reverse (CCW) directions with a direct current (DC) current without using a brush and a commutator. About.

  The DC brushless motor is obtained by replacing the functions of the brush and commutator of a conventional brush motor with a switching element such as a semiconductor and a control circuit for controlling the driving thereof. Compared with a brush motor, the DC brushless motor is superior in that it has a longer life, can be miniaturized, and can be assembled in a variety of shapes, and is highly efficient, easy to control, and driven quietly. For example, it is rapidly spreading to CD / DVD-ROM drives, hard disks, refrigerators, air conditioners and the like.

  As shown in FIG. 1, the DC braless motor is used for a fan 1 that blows air to cool a heating element 3 such as an electric device that generates heat in accordance with a drive housed in a casing 2 such as a case or a container. Their uses are expanding. The fan 1 energizes the coil wound around the stator of the motor 1a in the forward and reverse directions, whereby the permanent magnet, which is a rotor, rotates, and the fin 1b rotates accordingly to form an air flow (wind). To do. The fin 1b is integrated with the rotor. The wind is sucked from the intake port 2a and exhausted from the exhaust port 2b. The rotor may be inside or outside the stator.

  However, the conventional single-phase full-wave rectification type or two-phase half-wave rectification type DC brushless motor can be rotated only in one direction. Therefore, together with the wind sucked into the housing 2, dust, such as dust, is accumulated over time in the slit 4 of the mesh, dust-proof net, etc. disposed on the wind inlet 2a or the wind of the fan 1, There were problems such as a decrease in cooling efficiency, a failure of the heating element, and a cause of ignition.

  On the other hand, in the case of a three-phase DC brushless motor, the direction of rotation can be controlled by controlling the energization timing to the coil. For example, it is disclosed in Patent Document 1. By reversing the direction of rotation, the wind also flows in the opposite direction. Therefore, the dust accumulated in the slit 4 can be regularly scattered to reduce or prevent the accumulation of dust. In addition, such a three-phase DC brushless motor capable of forward and reverse rotation exhibits the same effect even in the case of local cooling inside the apparatus, not as a system fan that exhausts or intakes the entire inside of the apparatus. That is, in the case of local cooling, it is possible to reduce and prevent dust accumulated in the heat sink portion.

  Patent Document 2 discloses a DC brushless motor and a fan. The invention of Patent Document 2 is a DC brushless motor capable of forward and reverse rotation, and includes an inverting circuit capable of inverting the output signal of the Hall element 2 while being input to the drive IC 1 by the control signal C. By providing an inverting circuit capable of reversing the energization of the coils 4 and 5 connected in series or reversing the direction of the current applied to the Hall element by the control signal C, the coils connected in series are connected. The energization of the coil can be reversed.

JP-A-6-70578 JP-A-2005-261140

  However, a three-phase DC brushless motor is more expensive to manufacture and more complicated to control than a single-phase full-wave rectification type or two-phase half-wave rectification type DC brushless motor. In addition, the single-phase full-wave rectification type, two-phase half-wave rectification type DC brushless motor can be connected to the power supply in the reverse direction or the existing circuit in the reverse direction. It cannot be rotated in both directions from the outside.

  However, in Patent Document 2, since the level of the control signal C is detected and the output signal of the Hall element 2 is switched, the control and circuit are complicated, and the manufacturing cost is high.

  FIG. 2 shows a conventional single-phase full-wave rectification type DC brushless motor 1c (a single coil is alternately supplied with positive and negative currents (A)) and a two-phase half-wave rectification type DC brushless motor 1d (B: The cross-sectional schematic diagram of the bifilar winding) is shown.

  N and S are the N pole and S pole of the magnet 6, and here, the combined product of the permanent magnet 6 and the magnet yoke 6a becomes the rotor. That is, when the motor is used as a fan motor, the fin 1b is connected to the combined product of the magnet 6 and the magnet yoke 6a.

  The stator 5 has four poles and each pole has a T shape, and the tip of the T shape is called poles 5a and 5b. The stator 5 is fixed or integrally formed on the frame of the fan 1 or the like. In the hole of the stator 5, the rotating shaft 5c of the rotor including the magnet 6 is rotatably held.

  A coil 7 (7a) is wound around the shaft-like portion of the stator 5. The magnet 6 rotates by alternately applying a reverse current to the coil 7 (7a). Switching of the energization direction is controlled by sensing the position of the magnetic pole of the magnet 6 with a position sensor 8 fixed to the stator 5 and inputting the magnetic pole detection signal to a circuit (output path 10) for controlling the switch element.

  The position sensor 8 is arranged so as not to come to the magnetic pole boundary 6b so that the restart after the motor stops smoothly. The torque applied to determine the stop point of the motor is called cogging (cogging torque). If the stop point angle due to cogging is a 4-pole motor, it is designed to be 22.5 ° in the forward direction and the maximum value of cogging torque is ½ of the maximum torque generated by the magnet and coil when rotating. Ideal.

  This 22.5 ° is an angle in a mechanical angle in which one rotation of the magnet 6 is 360 °. If the angle at which the magnet 6 rotates and the positional relationship of the magnetic poles reaches the same position as the original position is 360 ° in electrical angle, the mechanical angle is 180 °. The cogging angle is ideally 45 ° in electrical angle, and the cogging angle varies depending on the number of magnetic poles of the motor. For example, in a 2-pole motor, the electrical angle and the mechanical angle are the same, so the cogging angle is 45 ° even in the mechanical angle.

  Next, FIG. 3 shows a block diagram of a conventional typical single-phase full-wave rectification type DC brushless motor drive IC. A position sensor 8 (H: Hall element) detects the magnetic pole of the magnet 6, and based on the magnetic pole detection signal, the direction of the current flowing through the coil 7 is reversed by driving the switching element 9 in accordance with the switching of the magnetic pole. IN + and IN- mean that if there is a magnetic pole, the output is output, and if there is no magnetic pole, both are not output. With respect to the middle of the applied voltage to the Hall element H, it is output as + and −, and the magnitude thereof is the same.

  Next, FIG. 4 shows an ideal combined torque during normal rotation (forward rotation) in a conventional single-phase full-wave or two-phase half-wave rectification type DC brushless motor. Since the torque value obtained by synthesizing the magnetic field torque and the cogging torque is positioned at + at all angles, it can be seen that CW rotation occurs without any dead point wherever it is stopped.

  On the other hand, FIG. 5 shows a combined torque when the conventional single-phase full-wave or two-phase half-wave rectification type DC brushless motor is set in the reverse rotation mode by an electric circuit. In this case, as is apparent from FIG. 5, there is a place where torque (in this case, CW torque) opposite to the rotation direction (in this case, the CCW direction) is generated, and a dead center is generated. Further, compared with the forward rotation, the fluctuation of the synthesized torque becomes very large, and the vibration of the motor is large, which is extremely problematic.

  Next, the cogging torque and the stop point will be described with reference to FIG. Since the cogging torque is as shown in FIG. 6A, the sum is zero. Therefore, in a rotating motor, the motor torque at the time of forward rotation and reverse rotation has the same value. During reverse rotation, the torque during rotation does not become smaller.

  FIG. 6B shows a stable stop point, and FIG. 6C shows an unstable stop point. At the stable stop point, when the magnet 6 rotates to CW, the torque of CCW works and returns to the stop point, and even if it tries to rotate to CCW, it returns to the original position and is stable. At an unstable stop point, when the magnet 6 rotates to CW, the same CW torque works, and the magnet 6 rotates and stops at the next stable stop point.

  As can be seen from the schematic cross-sectional view shown in FIG. 6 (B), it normally stops at a stable stop point (solid line circle in (A)), but the probability of stopping at an uneasy stop point is not zero. However, even if the motor stops at an unstable stop point (broken line circle in (B)) with a normal motor, the position sensor 8 is not positioned at the boundary of the magnetic pole of the magnet 6 and thus starts rotating without any problem.

  The present invention provides a simple control and low cost for a single-phase full-wave rectification type or two-phase half-wave rectification type DC brushless motor that rotates in both forward and reverse directions with a direct current without using a brush and a commutator. It is intended to be provided by.

In order to solve the above problems, the present invention provides:
(1)
There are two position sensors that detect the magnetic pole position of the magnet that is the rotor and the output path of the magnetic pole detection signal from the position sensor to the switching element, and the on / off of the switching element is controlled by the output of the magnetic pole detection signal of the position sensor. In the single-phase full-wave rectification type DC brushless motor that changes the energization direction to the coil wound around the stator or the two-phase half-wave rectification type DC brushless motor that switches the energization coil among the two-phase coils wound around the stator,
An output path of the magnetic pole detection signal is determined in advance for the S pole or N pole magnetic pole signal detected by the position sensor for the first time after energization, and a signal for determining the output path of the magnetic pole detection signal based on the magnetic pole signal. A DC mode capable of forward and reverse rotation, comprising a switching mode control circuit for outputting, switching an output path of the magnetic detection signal based on a signal output from the switching mode control circuit, and determining a rotation direction of the rotor The configuration is a brushless motor.
(2)
The configuration of the DC brushless motor capable of forward / reverse rotation described in (1) is characterized in that the cogging angle is 90 ° in electrical angle.

  In the DC brushless motor capable of rotating in the forward and reverse directions of the present invention (hereinafter sometimes simply referred to as “motor”), the rotor may be arranged either inside or outside the starter. The position sensor can be exemplified by a Hall element, but is not limited to the Hall element as long as it can detect and output the same function, that is, the magnetic pole position of a magnet such as a permanent magnet. In addition, the switching element includes a semiconductor. Further, the circuit only needs to add a mechanism for switching the input (hereinafter also referred to as an output path) to the circuit for controlling the switching element from the position sensor and a control circuit for controlling the same to the conventional circuit.

  It is preferable that the change of the rotation direction is not automatically changed by the operator and is automatically performed in conjunction with the normal operation of the operator. For example, an internal timer is provided in the control circuit of the mechanism that rotates in reverse for several tens of seconds, or switches the output path in conjunction with turning on or off the drive power source or fan of the heating element, and the rotation direction can be changed periodically. Alternatively, reverse rotation may be performed for a predetermined time after turning on / off the driving power source of the heating element. Of course, a mechanism that changes only the rotation direction of the motor as intended by the operator may be used.

  The present invention can simplify the circuit by detecting the pole type and switching the output path from the position sensor to the switching element, or by changing the energization direction to the coil wound around the stator. A low-cost, single-phase full-wave rectification type or two-phase half-wave rectification type DC brushless motor that rotates forward and reverse can be provided. Therefore, it is possible to provide a single-phase full-wave rectification type or two-phase half-wave rectification type DC brushless motor that rotates in both forward and reverse directions more simply and cheaply than a three-phase DC brushless motor.

  Conventionally, when a fan that uses a motor that rotates only in one direction is used for cooling air to a heat generating part such as an electric device for a long time, there is a problem that dust accumulates in the suction part and the like. can do. In particular, by interlocking with the on / off of the drive power supply of the electrical equipment, for example, when the drive power supply is turned off, the airflow in the opposite direction is kept until the motor stops by mechanically changing the connection of the output path in the reverse direction. It becomes possible, and the dust adsorbed on the suction part can be blown off. When the drive power supply is turned on next time, air blowing in the direction of blowing air to the heating element is performed by switching the connection of the output path. In conjunction with the driving of the electrical equipment, no special operation is required, and dust on the suction portion of the cooling air can be cleaned, which is convenient for the user.

It is explanatory drawing of the usage example of a fan. It is a cross-sectional schematic diagram of a conventional DC brushless motor. It is a block diagram of the conventional DC brushless motor (FIG. 1 (A)). It is a figure which shows the ideal synthetic | combination torque at the time of normal rotation (forward rotation) in the conventional DC brushless motor. In a conventional DC brushless motor, it is a figure which shows the synthetic | combination torque when it sets to reverse rotation mode by an electric circuit. It is a figure which shows a cogging torque and a stop point. It is a block diagram of Example 1 (single phase full wave rectification type DC brushless motor). It is a block diagram of Example 2 (two-phase half-wave rectification type DC brushless motor). Example 3 is a schematic cross-sectional view of a DC brushless motor capable of forward / reverse rotation that has been modified so that the resultant torque has the same waveform by rotating in both forward and reverse directions by changing the stator shape. It is a figure which shows the synthetic | combination torque and stop point at the time of forward / reverse rotation in the case of FIG. 9 is a diagram showing the range of change in the combined torque during forward rotation when the maximum value of the cogging torque is designed to be small. Example 4 is a schematic cross-sectional view of a DC brushless motor capable of forward / reverse rotation in another form in which the stator shape is changed so that the combined torque has the same waveform by rotation in both forward and reverse directions.

  Hereinafter, the present invention will be described in detail with reference to the drawings.

  FIG. 7 is a circuit block diagram of a DC brushless motor capable of forward and reverse rotation in the single-phase full-wave rectification type DC brushless motor according to the present invention. FIG. 7A shows the circuit connection during forward rotation, and FIG. 7B shows the circuit connection during reverse rotation.

In FIG. 3, the output path 10 of the magnetic pole detection signal, which is the position signal of the magnetic pole of the magnet 6 detected by the position sensor 8, is crossed (replaced), so that it can be rotated in both forward and reverse directions. The control circuit or the like is a conventional general single-phase full-wave rectification type or 2 except for a switching mechanism (mechanical connection or electrical connection) of the output path 10 and a control circuit (switching mode control circuit) for controlling the output path 10. This is the same as a phase half-wave rectification type DC brushless motor.

  The timing of switching is the on / off of the drive power of the heating element (starting and ending of the electrical equipment), in conjunction with the normal operation of the person, the internal timer, or the rotor sensor first detected by the magnetic sensor when the power is turned on Depending on the type of magnetic pole, it can be rotated automatically and regularly or intentionally and irregularly with a forced switch. If it is a fan provided with such a motor, the wind for cooling will be generated in the reverse direction and it will be useful for scattering of the accumulated dust, reduction of dust, and prevention.

  FIG. 8 is a circuit block diagram of a DC brushless motor capable of forward and reverse rotation in the two-phase full-wave rectification type DC brushless motor according to the present invention. FIG. 8A shows circuit connections during forward rotation, and FIG. 8B shows circuit connections during reverse rotation. The forward / reverse rotation control is the same as that of the conventional two-phase full-wave rectification type DC brushless motor except that the output path 10 of the magnetic pole detection signal from the position sensor 8 is replaced and a switching mode control circuit is provided. The switching mechanism of the output path 10 and the switching mode control circuit are the same as those in the first embodiment. same as below.

  Next, FIG. 9 is changed to the stator 12a in which the notch 12b is provided in the stator 5 of FIG. 2, and a DC brushless capable of forward and reverse rotation with a cogging angle of 45 ° mechanical angle (electrical angle 90 °). A schematic diagram of the motor 12 is shown. The notch 12b is formed by recessing the center of both poles 5a and 5b of each pole of the stator 12a in a V shape in the direction of the rotation axis 5c (the same applies to the stators 11a and 14a). FIG. 9A shows a stable stop point, and FIG. 9B shows an unstable stop point. Reference numeral 6b is a magnetic pole boundary when stopped at a stable stop point, and reference numeral 6c is a magnetic pole boundary when stopped at an unstable stop point. With such a shape, the combined torque during forward rotation in FIG. 10A and reverse rotation in FIG. 10B shows the same waveform.

  Further, compared to the case where a conventional DC motor (FIG. 2) is employed, the output path 10 can be replaced to reduce the torque fluctuation range of the combined torque during reverse rotation. Further, there is no angle at which negative torque (torque to rotate in reverse) is generated at all angles. In addition, if the maximum value of the cogging torque is designed to be small as shown in FIG. 11, the fluctuation range can be reduced as in the combined torque of FIG.

  However, if the cogging torque is made too small, the influence of mechanical friction cannot be ignored, so there is a possibility that it will not stop at a stable stop point when the motor is stopped, and it is necessary to adjust the design value by the motor to be designed. .

  In general, the smaller the motor, the closer the cogging torque and the torque in the opposite direction to prevent rotation due to friction, making it more difficult to stop at a stable stopping point where it is originally desired to stop. Therefore, there is a limit to reducing the cogging torque.

  If the cogging torque is not affected by friction and stops at the stable stopping point shown in FIG. 9A, when the motor is energized, the electromagnetic torque generated at that time becomes maximum and the motor starts rotating smoothly.

  On the other hand, the probability of stopping at an unstable stop point shown in FIG. Even when energized in the state of FIG. 9B, the magnet 6 may not rotate because the electromagnetic torque is zero.

  As a method of avoiding such danger, a circuit that intentionally reverses the coil energization direction when the motor is not rotating is provided by a mechanism that detects the rotation of the magnet built in the drive IC. When energized, a magnetic field torque is generated, and if the magnet is vibrated, it can be separated from an unstable stop point and rotated.

  Next, as shown in FIG. 12, the cogging angle is 45 ° in mechanical angle (electrical angle 90 °) as in Example 63, and the forward / reverse direction includes a stator 13a of another form in which the combined torque during forward and reverse rotation has the same waveform. A schematic diagram of the rotatable DC brushless motor 13 is shown.

  When the stator 13a is stopped at a stable stop point, the tips of the poles 5a and 5b on the position sensor 8 between the poles 5a and 5b are cut out. That is, in the stator 5 of FIG. 2, the left and right two poles out of the four poles on the upper, lower, left and right sides are inverted to the line object. Even with this shape, the composite torque waveform is not shown here, but the composite torque waveform during forward and reverse rotation is the same waveform, and the torque fluctuation is the same as in the third embodiment as compared with the case where the conventional stator 5 is employed. The width becomes smaller.

DESCRIPTION OF SYMBOLS 1 Fan 1a Motor 1b Fin 1c Single phase full wave rectification type DC brushless motor 1d Two phase half wave rectification type DC brushless motor 2 Housing 2a Suction port 2b Exhaust port 3 Heating element 4 Slit 5 Stator 5a Pole 5b Pole 5c Rotating shaft 6 Magnet 6a Magnet yoke 6b Magnetic pole boundary
6c Magnetic pole boundary 7 Coil 7a Coil 8 Position sensor 9 Switching element 10 Output path 12 DC brushless motor 12a capable of forward / reverse rotation 12b Notch 13 DC brushless motor 13a capable of forward / reverse rotation Stator

Claims (2)

There are two position sensors that detect the magnetic pole position of the magnet that is the rotor and the output path of the magnetic pole detection signal from the position sensor to the switching element, and the on / off of the switching element is controlled by the output of the magnetic pole detection signal of the position sensor. In a single-phase full-wave rectification type DC brushless motor that changes the energization direction to the coil wound around the stator or a two-phase half-wave rectification type DC brushless motor that switches the energization coil among the two-phase coils wound around the stator,
An output path of the magnetic pole detection signal is determined in advance for the S pole or N pole magnetic pole signal detected by the position sensor for the first time after energization, and a signal for determining the output path of the magnetic pole detection signal based on the magnetic pole signal. A DC mode capable of forward and reverse rotation, comprising a switching mode control circuit for outputting, switching an output path of the magnetic detection signal based on a signal output from the switching mode control circuit, and determining a rotation direction of the rotor Brushless motor. The DC brushless motor capable of forward and reverse rotation according to claim 1, wherein the cogging angle is 90 ° in electrical angle.

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