JP2982445B2 - Brushless motor - Google Patents

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 an air conditioner or the like, and more particularly to a brushless motor having a motor lock countermeasure.

[0002]

2. Description of the Related Art A conventional brushless motor drive system has a configuration shown in the block diagram of FIG. 2, in which a motor unit A having a drive circuit unit 7 is operated by a DC power supply unit B such as a switching power supply. , The rotational speed of the brushless motor is varied. Hereinafter, an example of a conventional brushless motor drive system will be described with reference to the drawings. The DC power supply unit B converts the commercial power supply 1 into a rectifying and smoothing unit 3.
After rectifying and smoothing, the transformer 4 and the switching power element 10
And a DC-DC converter unit constituted by the voltage control means 11 to change the DC voltage into a variable DC voltage.
Control the rotation speed of the motor 6 connected to the power element group 5 which opens and closes in response to the energization switching signal. In the voltage control means 11 of the DC-DC converter, the output voltage is controlled according to the rotation speed command signal from the rotation speed command unit 2, but the output voltage of the current detection means 9 is further input, and The switching power element 10 is controlled so as not to flow, and when a current higher than the overcurrent setting flows, the switching power element 10 is turned off to reduce the DC output voltage so that a current higher than the set value does not flow. .

[0003]

In the above-described conventional brushless motor drive system, when the motor is locked due to a failure of a bearing or the like, a current of an overcurrent set value constantly flows through the motor, and The heat generated by the drive circuit increases. To prevent this, a lock detection means for the motor is provided to cut off the output of the DC power supply when the motor is locked, thereby suppressing the heat generation of the motor and the drive circuit. However, in such a system, since it is not known whether the motor has locked and the system has stopped, the system remains stopped until the user of the air conditioner notices an abnormality in the room temperature. Further, if the microcomputer of the system goes out of control, the lock of the motor cannot be detected, and there is a problem that heat generation becomes large and the life of the motor is shortened.

An object of the present invention is to solve the above-mentioned conventional problems and to provide a brushless motor in which safety is improved by taking measures against motor lock while reducing system cost.

[0005]

In order to achieve the above object, a brushless motor according to the present invention comprises a motor current detecting means, an output voltage of the motor current detecting means, and a reference voltage. An open / close type current limiting means having an open / close cycle of an audible frequency is provided, wherein when the voltage is higher, the energization of the motor is interrupted and the motor is energized again after a certain period of time.

[0006]

With the above arrangement, when the motor is locked, the motor current is chopped at an audible frequency by the open / close type current limiting means, and an audible frequency electromagnetic sound is generated from the motor.
Notifies that the motor is locked.

[0007]

An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram of a drive system of a brushless motor according to the present invention. The driving DC power supply unit B rectifies and smoothes the commercial power supply 1 with the rectifying / smoothing unit 3 and then controls the output voltage in the DC-DC converter unit including the transformer 4, the switching power element 10, and the voltage control unit 11. ing. The motor section A performs logic processing on a signal from the rotor position sensor in the drive circuit section 7 to open and close the switching power element group 5. In the overcurrent protection, the motor current is detected by the current detection resistor 9, and the output voltage of the current detection resistor 9 is compared with the current limit level by the current limiting circuit 8. If the output voltage of the current detection resistor 9 is higher, the switching power The power supply to the motor is cut off by turning off the element group 5 and the power supply is started again after a certain time has elapsed. That is, the current limiting circuit 8 includes switching type current limiting means for opening and closing the switching power element group 5 in such a manner. Here, by setting the switching time of energization so that the switching frequency of the switching power element group 5 during the overcurrent operation is in the audible range, the motor is electromagnetically vibrated by the switching current when the motor is locked, and electromagnetic noise is generated. The alarm sounds when the motor is locked. Further, when the frequency of the electromagnetic sound is made to coincide with the resonance frequency of the motor, the sound becomes louder, and the effect as the lock alarm sound increases. As an embodiment of the present invention, the switching power element group 5, the drive circuit unit 7, and the switching
The stator is formed by integrating the rotor position sensor, the printed circuit board on which the one-chip IC and the current detecting means are mounted, the stator core, and the stator winding with resin. Are all effective forms for improving reliability.

[0008]

According to the present invention as described above, the following effects can be obtained.

1. When the motor is locked, the electromagnetic noise generated by the motor current becomes a lock alarm to notify that the system is in an abnormal state, so that the system abnormality can be quickly detected, and the safety and reliability of the system are improved.

[0010] 2. Since the DC power supply does not require a current detecting means, the cost of the power supply is reduced, and the space and cost of the system can be reduced.

[Brief description of the drawings]

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

FIG. 2 is a block diagram of a conventional brushless motor drive system.

[Explanation of symbols]

 Reference Signs List 5 switching power element group 6 motor 7 drive circuit section 8 current limiting circuit (open / close type current limiting means) 9 current detecting resistor (motor current detecting means)

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) H02P 6/12 H02K 11/00

Claims (1)

(57) [Claims] 1. A motor current detecting means, a DC power supply whose output voltage is controllable, a group of switching power elements for supplying to a motor while opening and closing a current from the DC power supply, and a signal of a rotor position sensor. a driving circuit unit for opening and closing the switching power device group in accordance with the motor locked
The motor current is larger than the specified value due to abnormal operation such as
Rotor position switching power element group when it becomes Ku
A non-energized irrespective of the signal of the location sensor, again the switching power device when the <br/> motor current by energization is greater than the predetermined value again in accordance with a signal again the rotor position sensor after a predetermined time has elapsed Group to rotor position
A brushless motor including an open / close type current limiting unit that protects the motor and the drive circuit from destruction due to overcurrent by repeating an operation of de-energizing irrespective of the signal of the power supply. A brushless motor characterized in that the frequency is a period that becomes an audible frequency.