JPH07222485A - Brushless motor - Google Patents

Abstract

(57) [Abstract] [Purpose] An object of the present invention is to provide a brushless motor used in various home appliances, which suppresses a sudden change in the drive coil current at the time of switching energization and has a small vibration. A multi-phase motor drive coil, a permanent magnet rotor, a position detector that detects the position of the permanent magnet rotor, and an energization switching circuit that outputs an energization switching signal according to the output of the position detector. And a switching element group that switches energization of the motor drive coil in accordance with the energization switching signal,
By making the current flowing through the motor drive coil a stepwise pseudo sine wave, it is possible to suppress a sudden change in the drive coil current at the time of switching the energization and to realize a brushless motor with small vibration.

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 in home electric appliances such as air conditioners and water heaters.

[0002]

2. Description of the Related Art In recent years, household appliances such as air conditioners and water heaters have been improved in performance and functionality, and along with this, brushless motors having excellent controllability have been adopted as motors used in these appliances. Is increasing.

Conventional brushless motors include the following. A conventional brushless motor will be described below with reference to the drawings.

FIG. 5 is a block diagram of a conventional brushless motor. In FIG. 5, reference numerals 1, 2 and 3 are motor drive coils, and 20 is a permanent magnet rotor. Position detecting means 3
0b is composed of the Hall element group 70 and the position detecting magnet 100, and outputs a signal corresponding to the position of the permanent magnet rotor 20. The position detection signal output from the position detection means 30b is input to the energization switching circuit 40b. The energization switching circuit 40b logically processes the position detection signal and outputs an energization switching signal. The switching element group 50 drives the brushless motor by switching the energization of the motor drive coil according to the energization switching signal.

Now, a method of energizing the drive coil in the conventional brushless motor will be described.

FIG. 6 is a block diagram of a position detecting means in a conventional brushless motor. In FIG. 6, 71,
Reference numerals 72 and 73 denote Hall elements, which form the Hall element group 70 in FIG. In addition, the hall elements 71, 72, 7
3 are arranged at intervals of 60 degrees. A magnet 100 for position detection is magnetized to have four poles. Hall element 7
1, 72, 73 output a position detection signal High or Low according to the magnetized pole of the position detection magnet 100.

FIG. 7 shows a time chart of the outputs of the Hall elements 71, 72 and 73. Hall elements 71, 72, 73
Are arranged at an interval of 60 degrees from each other, and the position detecting magnets 10
Since 0 is magnetized to 4 poles, the Hall element 71,
The outputs of 72 and 73 have a phase difference of 60 degrees.

The position detection signals output from the Hall elements 71, 72, 73 are input to the energization switching circuit 40b and subjected to logic processing. The energization switching circuit 40b logically processes the position detection signal to output the energization switching signals UH, VH, WH, UL, VL and WL shown in FIG.

Energization switching signals UH, VH, WH, U
L, VL, and WL are input to the switching element group 50,
The switching element group 50 has energization switching signals UH, V
Each drive coil 1, according to H, WH, UL, VL, WL
Switching the energization of 2 and 3.

As a result, the drive coil 1 has I shown in FIG.
A rectangular wave-shaped current such as u flows. Also, a current having a similar waveform flows through the drive coils 2 and 3.

The brushless motor is driven by a rectangular wave-shaped current flowing through the drive coils 1, 2, and 3.

However, when a brushless motor is driven by a rectangular wave-shaped current such as Iu shown in FIG. 7, a torque change corresponding to the number of energization switchings per rotation occurs due to a rapid change in current when energization switching occurs. The resulting vibration occurs. As a countermeasure, there is known a method in which a switching element is used in the active region at the time of switching energization, the current flowing through the drive coil is smoothly changed, torque unevenness is reduced, and vibration is suppressed. An example of such a method is:
JP-A-5-68395 can be mentioned.

[0013]

However, in the conventional brushless motor, the switching element is used in the active region in order to generate or suppress the vibration due to the torque unevenness caused by the rapid current change at the time of switching the energization. As a result, the switching loss of the switching element becomes large and the output is restricted due to heat generation, which is a problem.

The present invention solves the above-mentioned problems of the prior art. By suppressing a sudden change in the drive coil current at the time of switching the energization and reducing the torque unevenness without increasing the switching loss of the switching element, the vibration of the vibration is reduced. It is intended to provide a small brushless motor.

[0015]

To achieve this object, a brushless motor according to the present invention comprises a motor drive coil having a plurality of phases, a permanent magnet rotor, six Hall elements, and two position detecting magnets. It comprises a position detecting means consisting of, an energization switching circuit, and a switching element group.

[0016]

With this configuration, it is possible to reduce torque unevenness and vibration by suppressing abrupt changes in the drive coil current during energization switching without increasing the switching loss of the switching element.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram of a brushless motor according to an embodiment of the present invention. In FIG. 1, 1, 2 and 3 are motor drive coils, and 20 is a permanent magnet rotor. The position detecting means 30a includes a Hall element group 60, a first position detecting magnet 80, and a second position detecting magnet 90, and outputs a signal according to the position of the permanent magnet rotor 20. The position detection signal output from the position detection means 30a is input to the energization switching circuit 40a. The energization switching circuit 40a logically processes the position detection signal and outputs an energization switching signal. The switching element group 50 drives the brushless motor by switching the energization of the motor drive coil according to the energization switching signal.

Now, a method of energizing the drive coil of the brushless motor in one embodiment of the present invention will be described.

FIG. 2 is a block diagram of the position detecting means of the brushless motor in one embodiment of the present invention. In FIG. 2, 20 is a permanent magnet rotor. 61, 62, 63,
Reference numerals 64, 65 and 66 denote Hall elements, which constitute the Hall element group 60 in FIG. Hall elements 61, 62, 6
3 are arranged at an interval of 60 degrees from each other, and Hall elements 64,
65 and 66 are also arranged at intervals of 60 degrees. 8
0 is a magnet for the first position detection, which is magnetized to 4 poles.
Is a second position detecting magnet and is magnetized to 8 poles. Also,
Misalignment 89 between the magnetized boundary surface 80a of the first position detecting magnet 80 and the magnetized boundary surface 90a of the second position detecting magnet 90.
b is the angular deviation 1 between the Hall element 61 and the Hall element 64.
Equal to 4b. The Hall elements 61, 62, 63 output the position detection signal High or Low according to the magnetized pole of the second position detection magnet 90. In addition, the hall elements 34, 35, and 36 detect the position detection signal High or Lo according to the magnetized pole of the first position detecting magnet 80.
Output w.

FIG. 3 shows Hall elements 61, 62, 63, 6
The time chart of the output of 4,65,66 is shown.

The Hall elements 61, 62, 63 are 60 apart from each other.
Since the second position detecting magnet 90 is magnetized to have eight poles, the Hall elements 61, 62, 6
Each output of 3 has a phase difference of 30 degrees.

Since the Hall elements 64, 65, 66 are arranged at an interval of 60 degrees from each other and the first position detecting magnet 80 is magnetized to have four poles, the Hall elements 64, 6 are provided.
The outputs of 5 and 66 have a phase difference of 60 degrees.

Hall elements 61, 62, 63, 64, 6
The position detection signals output by 5 and 66 are input to the energization switching circuit 40a and subjected to logic processing. The energization switching circuit 40a logically processes the position detection signal to energize the switching signals UH, VH, WH, UL, V shown in FIG.
Outputs L and WL.

Energization switching signals UH, VH, WH, U
L, VL, and WL are input to the switching element group 50,
The switching element group 50 has energization switching signals UH, V
Each drive coil 1, according to H, WH, UL, VL, WL
Switching the energization of 2 and 3.

The energization switching signals UH, VH, WH,
According to UL, VL, and WL, the energization modes of the drive coils 1, 2, and 3 are the three modes shown in FIG.

Mode 1 is a case where one switching element on the power supply voltage _VDC side is turned on and two switching elements on the ground side are turned on as shown in FIG.
Current of Iua shown in FIG. Mode 2 is shown in FIG.
As shown in (b), the switching element on the power supply voltage _VDC side is 1
When one unit is turned on and one switching element on the ground side is turned on, the current Iub of FIG. 3 flows through the drive coil 1. Mode 3 is a case where two switching elements on the power supply voltage _VDC side are turned on and one switching element on the ground side is turned on, as shown in FIG.
Iuc current flows.

As described above, the current flowing through the drive coil is
Since three values of Iua, Iub, and Iuc in FIG. 3 are taken, the current waveform becomes a stepwise pseudo sine wave like Iu shown in FIG.

As a result, since the current flowing through the drive coil changes in three steps, the rapid change in the current flowing through the drive coils 1, 2, and 3 at the time of switching the energization is suppressed, and the torque unevenness is reduced to drive the motor. Vibration at time can be reduced. Further, since the switching element is used in the saturation region, the switching loss is equivalent to that in the rectangular wave drive, and the output limitation due to heat generation is eliminated.

In the configuration of the brushless motor according to the embodiment of the present invention shown in FIGS. 1 and 2, the permanent magnet rotor 20 is described as having four poles. Even in this case, the same effect can be obtained.

Further, in the configuration of the brushless motor in the embodiment of the present invention shown in FIGS. 1 and 2, the position detecting means 3 is used.
0a is the hall element 61, 62, 63, 64, 65, 66
Although the first position detecting magnet 80 and the second position detecting magnet 90 are used, the same effect can be obtained even if the Hall element is replaced with a Hall IC.

[0032]

As described above, according to the present invention, the position detecting means of the brushless motor comprises the Hall element or six Hall ICs, the first position detecting magnet and the second position detecting magnet.
The position detection signal output from the position detection means is logically processed by the energization switching circuit, and the energization switching signal output from the energization switching circuit causes the switching element group to switch energization of the motor drive coil to drive the brushless motor. It is possible to realize an excellent brushless motor in which torque unevenness is reduced by suppressing sudden changes in the current flowing through the drive coil, vibration during motor driving is small, and output is not restricted by heat generated by switching loss. .

[Brief description of drawings]

FIG. 1 is a configuration diagram of a brushless motor according to an embodiment of the present invention.

FIG. 2 is a configuration diagram of position detecting means of a brushless motor according to an embodiment of the present invention.

FIG. 3 is a time chart of a position detection signal, an energization switching signal, and a motor drive current waveform according to an embodiment of the present invention.

FIG. 4 is a conduction mode diagram of a drive coil according to an embodiment of the present invention.

FIG. 5 is a block diagram of a conventional brushless motor.

FIG. 6 is a configuration diagram of a position detecting means of a conventional brushless motor.

FIG. 7 is a time chart of a position detection signal, an energization switching signal, and a motor drive current waveform of a conventional example

[Explanation of symbols]

 1, 2 and 3 drive coil 20 permanent magnet rotor 30a position detection means 40a energization switching circuit 50 switching element group 60 hall element group 61, 62, 63, 64, 65, 66 hall element 80 first position detection Magnet 90 Second position detection magnet

Claims (3)

[Claims] 1. A multi-phase motor drive coil, a permanent magnet rotor, position detecting means for detecting the position of the permanent magnet rotor, and energization for outputting an energization switching signal according to the output of the position detector. In a brushless motor including a switching circuit and a switching element group that switches energization of the motor drive coil according to the energization switching signal, a current flowing in the motor drive coil is a stepwise pseudo sine wave. And brushless motor. 2. A brushless motor according to claim 1, wherein the position detecting means comprises a magnet and a Hall element. 3. A brushless motor according to claim 1, wherein the position detecting means comprises a magnet and a Hall IC.