JP2001178175A - Brushless-motor drive system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a brushless-motor drive system which reduces power consumption in standby and driving. SOLUTION: Hall ICs as commutation sensors 1, 2, 3 are attached to a brushless motor 8. Electric power is supplied by the power-supply line 10 and the ground line 11 of an inverter power-supply device 7. A transistor 12 is incorporated on the power-supply line 10 so as to be used as the cutoff device of the power-supply line. A microcomputer 13 inside the inverter power-supply device 7 is used as a state judgment device which judges whether the brushless motor is currently driven or in standby. It outputs a power-supply cutoff signal which turns on/off the transistor 12, the supply of the electric power is cut off, and the power consumption of the brushless-motor drive system is reduced in standby of the 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 drive system for controlling a brushless motor having a commutation sensor used for detecting a rotational position to a desired rotational speed by an inverter device.

[0002]

2. Description of the Related Art Conventionally, an induction motor has been used as a drive source for various industrial equipment, and a part of the motor has been controlled in rotational speed by an inverter device.

[0003] In recent years, there has been a demand for energy saving due to a reduction in environmental load, and an efficient brushless motor has been controlled from an induction motor by an inverter device so that the rotation speed becomes a desired value. It was necessary to detect the rotational position of the motor. Further, as the speed control of the speed control of the brushless motor is advanced, the control cycle is also increased.

[0004] As shown in FIG.
Commutation sensors 31, 32 attached to
The sensors 33 and the encoder sensors 34, 35, and 36 of the encoder 39 added in applications requiring higher-precision speed control are constantly supplied with power from the inverter power supply 7 for driving the brushless motor. .

Each sensor is connected to an inverter power supply 37.
The power supply lines are connected in parallel with each other, and the supplied power increases in proportion to the number of sensors.

[0006]

In the above-described brushless motor drive system, it is usually necessary to detect the output from the commutation sensor when controlling the speed of the brushless motor only when the brushless motor is rotating. For example, the sensor output is not used for speed control even when the sensor output is detected when the brushless motor is stopped, unless it is a special purpose that requires information such as the rotation angle when the brushless motor is stopped.

In the conventional brushless motor drive system, power is always supplied to the sensor without distinction between driving and standby of the brushless motor, and wasteful power is consumed during standby when the brushless motor is not driven. It can be said that.

[0008] In conventional applications, the ratio of the standby time to the drive time in the motor operation cycle is very short, and thus the power consumption during the standby has been neglected.

However, in applications where the standby state occupies most of the operation cycle, such as elevators and electric shutters, the power consumption is determined by the power consumption of the brushless motor drive system during standby. Therefore, it can be said that reduction of power consumption is indispensable from the recent trend of energy saving.

An object of the present invention is to solve the above-mentioned conventional problems, and an object of the present invention is to provide a brushless motor drive system that reduces power consumption during standby and further during driving.

[0011]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides a commutation sensor used for detecting a rotational position of a brushless motor, and a breaking device inserted on a power supply line for supplying the commutation sensor. A state determining device for determining whether the brushless motor is currently in a driving state or a standby state in response to a motor operation / stop command from the outside, and outputting the result as a signal; and a result of the state determining device indicating that the brushless motor is in a standby state. If so, the judgment device inputs a power cutoff signal to the cutoff device, cuts off a power supply line and stops power supply to the commutation sensor, and can reduce power consumption during standby. it can.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In order to solve the above-mentioned problems, the present invention provides a commutation sensor used for detecting a rotational position of a brushless motor, a breaking device inserted on a power supply line for supplying the commutation sensor, A state determination device that receives a motor operation / stop command from the outside, determines whether the brushless motor is currently in a driving state or a standby state, and outputs a signal indicating the result, and the result of the state determination device indicates that the brushless motor is in a standby state. If so, the determination device is a brushless motor drive system that inputs a power cutoff signal to the cutoff device, cuts off a power line, and stops supplying power to the commutation sensor.

[0013] Also, an input / output insulated photosensor as a sensor added to the brushless motor, a constant current device for controlling a forward current of a light emitting diode as an input part of the photosensor to a constant value, and the photosensor And a power supply for supplying a current to the plurality of photosensors in series with the power supply line.

The brushless motor drive system according to claim 2, wherein the photo sensor is a commutation sensor used for detecting a rotational position.

Further, the brushless motor drive system according to claim 1 or 2 is used for an application in which a standby time occupies most of an operation cycle of an elevator or an electric switchgear.

As described above, the driving time of the brushless motor driving system and the stand-by state are determined, and the power supply to the commutation sensor is cut off during the stand-by state, so that the power consumption becomes zero.

Also, a plurality of light emitting diodes at the input part of the photosensor are connected in series, and the current supplied to each sensor is made the same by a constant current device. In this case, the power consumption can be reduced.

Further, by using a photo sensor as a commutation sensor indispensable for the brushless motor drive system, power consumption can be reduced both when the brushless motor is driven and during standby.

Further, the power consumption can be further reduced by using the brushless motor drive system in an application in which the standby state occupies most of the operation cycle.

[0020]

Embodiments of the present invention will be described below with reference to the drawings.

(Embodiment 1) In FIG. 1, Hall ICs are attached to the brushless motor 8 as the commutation sensors 1, 2, and 3, and power is supplied from a power supply line 10 and a ground line 11 of an inverter power supply 7. I have. The transistor 12 is on the power line 10 and is used as a power line cutoff device.

A microcomputer 13 inside the inverter power supply 7 is used as a state determination device for determining whether the brushless motor is currently in a driving state or a standby state, and outputs a power supply cutoff signal for turning on / off the transistor 12. . While driving the brushless motor 8, the microcomputer 13 turns on the transistor 12 to turn on the commutation sensors 1, 2, 3
Power supply to the transistor and the transistor 1
2 by turning off the commutation sensor 1,
Cut off the power supply to a few.

The transistor 12 is connected to the power line 10
It is not necessary to be on the ground line 11 and it may be on the ground line 11. The device for interrupting the power supply from the inverter power supply 7 to the commutation sensors 1, 2 and 3 is not limited to a transistor, but is a mechanical switch such as a relay. May be. Further, the state determination device is not limited to the microcomputer, and may be configured by combining logic circuits.

An experimental result when the brushless motor drive system of the present invention is used for driving a garage shutter will be described below.

Hall IC as commutation sensor
Motor is equipped with Hall I on three brushless motors
When a conventional inverter power supply device having no transistor for shutting off the power supply line to C is used, the power consumption of the brushless motor drive system during motor standby is 850 mW, and there is a transistor for shutting off the power supply line to the Hall IC of the present invention. However, when the power to the Hall IC was cut off during the motor standby, the power consumption of the brushless motor drive system was 700 mW.

Since the brushless motor is driven only when the vehicle enters and leaves, and the rest is a standby time, if the garage shutter is used ten times a day and one use time is one minute,
The driving time of one day is 10 minutes, and the remaining 23 hours and 50 minutes are waiting time.

Therefore, the conventional power consumption is 20.4.
Wh, the power consumption of the present invention is 16.8 Wh, and the daily power consumption can be reduced by 3.6 Wh (18%).

(Embodiment 2) In FIG. 2, the sensors 21, 22, 2 for commutation of a brushless motor 28 are shown.
An input / output insulated photo sensor (photo interrupter) is used for each of the sensors 3, 25, and 26 of the encoder 29. Six light emitting diodes, which are input portions of each sensor, are connected in series on a power supply line. A constant current circuit 3 for connecting and keeping the forward current of the light emitting diode constant
Connected to 0.

The constant current circuit 30 includes a transistor, a zener diode, and a resistor. The current value supplied from the inverter power supply 27 is equal to the current value supplied to each sensor.

For example, assuming that the current flowing through the light emitting diode is 10 mA, 60 mA is required in the conventional structure for supplying power to the parallel sensor. However, according to the present invention, 10 mA is sufficient, and when the brushless motor is driven. Power consumption can be reduced to 1/6.

The present invention is effective for a brushless motor drive system having only a commutation sensor, and does not necessarily need to have an encoder sensor.
It is only necessary to connect three photosensors as commutation sensors in series.

Alternatively, photo sensors for three commutation sensors and three photo sensors for three encoder sensors may be connected in series and connected in parallel. Further, the constant current circuit may be composed of only a resistor.

Further, when the first embodiment and the second embodiment are combined (the Hall IC which is the commutation sensor of the first embodiment is replaced with the photosensor of the second embodiment, the photosensors are connected in series to form a constant current device). Connection), a brushless motor drive system that constantly reduces the sensor power consumption of the brushless motor during driving and standby.

[0034]

As apparent from the above embodiment, claim 1
According to the described invention, the power consumption of the brushless motor drive system in which the brushless motor is in the standby state can be reduced.

According to the second and third aspects of the present invention,
Since the power supplied to the photo sensor can be reduced during driving of the brushless motor and during standby, power consumption of the brushless motor driving system can be reduced.

Furthermore, if the brushless motor drive system of the present invention is used for applications that occupy a large part of the operation cycle such as elevators and automatic switches, the sensor power consumption of the brushless motor can be reduced at all times, contributing to energy saving of equipment. it can.

[Brief description of the drawings]

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

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

FIG. 3 is an explanatory diagram of a conventional brushless motor drive system.

[Explanation of symbols]

1, 2, 3 Commutation sensor (Hall IC) 7 Inverter power supply 8 Brushless motor 9 Encoder 10 Power supply line 12 Transistor (interrupting device) 13 Microcomputer (Status judgment device) 21, 22, 23 Photo sensor (Commutation sensor) 24, 25, 26 Photosensor (encoder) 30 Constant current device

Claims (4)

[Claims] 1. A commutation sensor used for detecting a rotational position of a brushless motor, a cut-off device inserted on a power supply line supplied to the commutation sensor, and a brushless motor which receives a motor operation / stop command from the outside. Is a driving state or a standby state, and outputs a signal as a result of the determination.If the result of the state determining apparatus is that the brushless motor is in the standby state, the determination apparatus shuts off the power cutoff signal. A brushless motor drive system that inputs to the device, shuts off the power line, and stops supplying power to the commutation sensor. 2. An input / output insulated photosensor as a sensor added to a brushless motor, a constant current device for controlling a forward current of a light emitting diode as an input unit of the photosensor to be constant, and the photosensor. A brushless motor drive system comprising: a power supply for supplying a current to the power supply line; and a plurality of light emitting diodes of the photosensors connected in series to the power supply line. 3. The brushless motor drive system according to claim 2, wherein the photo sensor is a commutation sensor used for detecting a rotational position. 4. The brushless motor drive system according to claim 1, wherein the system is used for an application such as an elevator or an electric switchgear, wherein the standby time occupies most of the operation cycle.