JP2003319689A - Motor controller - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce vibration occurring in a motor controller which outputs a pulse width modulation drive signal to a brushless DC motor and controls the rotational condition of the brushless DC motor. <P>SOLUTION: This motor controller 2 outputs the pulse width modulation drive signal to the brushless DC motor 1, controls the rotational condition of the DC motor 1, and outputs a drive signal which permits a duty to increase gradually, thus starting the motor moderately. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a motor control device for controlling the rotating state of a brushless DC motor.

[0002]

2. Description of the Related Art Conventionally, a brushless DC motor (hereinafter referred to as a motor) has been used for driving a fan of an outdoor unit of an air conditioner.

A motor control device for controlling the rotation of such a motor generates a PWM pulse wave having a duty corresponding to a predetermined rotation speed PWM (pulse width modulation).
A generation circuit, a gate drive circuit that generates a gate drive signal based on the PWM pulse wave, and a drive signal that is generated by modulating the power supply voltage according to the duty of the PWM pulse wave based on the gate drive signal. And an inverter circuit for outputting to a motor.

[0004]

In the conventional motor control device, when the motor is started, as shown in FIG. 5, a PWM pulse wave having a reference duty corresponding to a steady rotation speed is generated to drive the motor.

However, since the motor is driven at the reference duty when the motor is started, the motor immediately starts to rotate, but at that time, a relatively large vibration is generated in the motor due to the reaction of the sudden start.

As a result, the noise is increased, and a large load is applied to the mounting portion of the motor due to the vibration, and the strength of the mounting portion is decreased over time, and the noise is increased.

In order to prevent such a problem,
A specification for increasing the strength of the mounting portion is required, which leads to an increase in the size of the configuration and an increase in the number of parts.

Further, when the motor is started in a state of being locked by an external load or the like, the locked state is detected after the start, the output of the drive signal is stopped, and the motor stop process is performed. After that, the motor is restarted.

Therefore, as shown in FIG. 6, the processes of start-up, motor lock, drive signal output stop, and motor stop are repeated, which also causes a problem that the vibration of the motor increases.

The present invention has been made to solve the above problems, and an object thereof is to provide a motor control device capable of significantly reducing the vibration generated by the motor.

[0011]

According to a first aspect of the present invention, a motor control device outputs a pulse width modulation type drive signal to a motor to control the rotation state of the motor. When the motor is started, the duty is gradually increased. The drive signal is output to the motor to start the motor.

A motor control device according to a second aspect of the present invention outputs a pulse width modulation type drive signal to the motor to control the rotation state of the motor, and detects that the duty of the drive signal exceeds a predetermined reference level. When detected, the drive signal whose duty is gradually reduced is output to the motor to stop the rotation of the motor.

[0013]

[Operation] In the motor control device according to the first aspect, when the motor is started, the drive signal for which the duty is gradually increased is output to the motor to start the motor, so that the motor may suddenly start rotating from the stopped state. Therefore, the vibration at the time of starting the motor can be suppressed as much as possible.

When the motor control device according to the second aspect detects that the duty of the drive signal exceeds a predetermined reference level, the motor control device outputs a drive signal whose duty is gradually reduced to the motor to stop the rotation of the motor.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION One embodiment of the present invention is shown in FIGS.
Will be described with reference to.

(1) Electrical Configuration of Motor Control Device 2 The electrical configuration of the motor control device 2 will be described below with reference to FIG.

A brushless DC motor (hereinafter referred to as a motor) 1 is, for example, a three-phase motor and includes u-phase, v-phase,
It has w-phase coils 3, 4, and 5. The motor 1 is provided with a magnetic pole detection element 6 composed of a Hall element for detecting a magnetic pole change of each phase, and outputs a position signal SP.

The motor controller 2 comprises an inverter circuit 7 for supplying a drive signal to the motor 1 and a controller 8.
A power supply voltage V is supplied to the inverter circuit 7 via a power supply line 9.
m is supplied, and the power supply voltage from the power supply line 9 is supplied to the control unit 8 via the regulator circuit 10.

The position signal SP from the magnetic pole detecting element 6 is input to the control unit 8 composed of a microcomputer, and the waveforms of the position signal SP for each phase are combined to form the phase and cycle of the position signal SP for each phase. Further, the mutual phase difference and the traveling direction of the phase are detected, and the rotation speed and the rotation position of the motor 1 are calculated.

An overcurrent detection circuit 11 is connected between the inverter circuit 7 and the ground potential, the output of the overcurrent detection circuit 11 is detected by the overcurrent protection circuit 12, and an overcurrent detection signal is sent to the control unit 8. Is output. An overvoltage protection circuit 13 is also connected to the control unit 8. A start / stop signal Vs supplied from an external control device and a speed command signal corresponding to the design rotation speed are input to the control unit 8.

The control unit 8 includes a PWM generator circuit (not shown) for generating a PWM pulse wave having a duty corresponding to a predetermined rotation speed, and a gate drive circuit for generating an energization signal based on the PWM pulse wave. (Not shown) are included. The energization signal is input to the inverter circuit 7 to control on / off of a switching element such as a power transistor included in the inverter circuit 7.

Further, the control section 8 uses the position signal SP from the magnetic pole detecting element 6 and the speed command signal to rotate the motor 1 calculated by the position signal SP and the design rotation speed instructed by the speed command signal. Servo control is performed on the rotation speed of the motor 1 so as to eliminate the deviation from

(2) Operation content of the motor control device 2 Referring to FIGS. 2 to 4 together, the motor control device 2 will be described below.
The operation of will be described.

In step a1 of FIG. 2, the control unit 8 waits for the start / stop signal Vs to input a drive command signal. When this determination is affirmative, the control unit 8 reads the position signal SP from the magnetic pole detection element 6 and detects the rotation speed and the rotation position of the motor 1 in step a2.

At step a3, the controller 8 outputs to the inverter circuit 7 a predetermined relatively low energization signal of the duty D1 shown in FIG.

Thereafter, in step a4, it is determined whether the motor 1 is in the locked state. This determination is to determine the locked state when the duty of the drive signal under the servo control exceeds a lock reference duty that is a predetermined reference level while the energization signal remains unchanged. If this determination is negative, then step a
The motor rotation process from 1 to step a4 is repeated.

Here, in this embodiment, the motor rotation processing,
Particularly, when the steps a3 to a4 proceed, the cycle t
When 0, the timer interrupt is executed periodically. The processing executed by the interrupt is shown in steps a5 to a7. At step a5, it is determined whether or not the current duty exceeds the duty command value corresponding to the speed command signal. If this judgment is negative, step a
In 6, the duty is increased by the duty D1 as an example, the interrupt processing ends, and the processing returns to the main processing. Hereinafter, as long as the determination in step a5 is negative, the processing in steps a1 to a6 is repeated, and the duty gradually increases as shown in the period T1 in FIG.

When the determination is affirmative in step a5, it means that the duty has reached the duty command value corresponding to the speed command signal, and the process moves to step a7, in which the duty D1 is decreased as an example. This interrupt processing ends, and the processing returns to the main processing. Hereinafter, as long as the determination in step a5 is affirmative, the processing in steps a1 to a7 is repeated, and the duty is gradually reduced as shown in the period T2 in FIG.

In this way, the motor 1 is started with the duty of the changing mode that gradually increases, and when the predetermined duty command value is reached, the servo control for maintaining the duty is executed. Note that the duty D1 and the cycle t0
Are stored in the control unit 8 in advance.

If it is determined in step a4 that the motor 1 is in the locked state, the process proceeds to step a.
8, the duty is the duty D1 as an example.
Is reduced only. In step a9, a predetermined fixed time is waited, and in step a10, it is judged whether the duty becomes 0 or not. If this judgment is negative,
The processes of steps a8 to a10 are repeated until the duty becomes 0. When the duty becomes 0 in step a10, the motor 1 is stopped. When it is determined that the motor 1 has stopped, the motor 1
Will be restarted.

If the motor 1 continues to be in the locked state, the motor 1 is, as shown in FIG.
The above-described gentle start and gentle stop are repeated.

In the present embodiment, when the motor 1 is started, the rotation speed of the motor 1 is increased in an energization mode in which the duty is gradually increased. This prevents the motor 1 from suddenly starting to rotate when the motor 1 is started. Therefore, a relatively large vibration is prevented from being generated in the motor 1 at the time of start-up, noise is suppressed, and a large load is applied to the mounting portion of the motor due to the vibration. In addition, it is possible to suppress noise, eliminate the need to increase the strength of the attachment site, reduce the size of the configuration, and reduce the number of parts.

Further, in this embodiment, when it is detected that the duty of the drive signal exceeds the lock reference duty, the motor 1 is judged to be in the locked state, and the drive signal whose duty is gradually reduced is output to the motor 1. The rotation of the motor 1 is stopped.

As a result, when the motor 1 tries to start in the locked state, or when the motor 1 is locked during rotation and the locked state is not recovered, the motor 1 suddenly goes into an output stop state from the state where the starting torque is applied. Alternatively, it is possible to prevent a situation in which the output is suddenly changed from the rotating state and then the starting process is performed to repeat this cycle. This also makes it possible to suppress the vibration of the motor 1 as much as possible.

(Modification) Steps a6 and a
The amount of decrease or increase of the duty in step 7, step a8, etc. is not limited to the same change amount D1 as in the above-described embodiment, but different values may be appropriately selected.

[0036]

As described above, according to the motor control device of the first aspect, at the time of starting the motor, the drive signal whose duty is gradually increased is output to the motor to start the motor. As much as possible,
Noise can be suppressed. Further, by suppressing the vibration, it is possible to suppress the mechanical strength of the mechanical portion of the motor, and it is possible to reduce the configuration and reduce the number of parts.

According to the motor control device of the second aspect, when it is detected that the duty of the drive signal exceeds the predetermined reference level, the drive signal whose duty is gradually reduced is output to the motor to stop the rotation of the motor. Let

This prevents a situation where the motor output is suddenly stopped from the state where the starting torque is applied to the motor when the motor is about to start in the locked state. Also by this, vibration of the motor can be suppressed as much as possible, noise can be suppressed, the configuration can be downsized, and the number of parts can be reduced.

[Brief description of drawings]

FIG. 1 is a block diagram showing an electrical configuration of a motor control device 2 according to an embodiment of the present invention.

FIG. 2 is a flowchart showing an operation example of the present embodiment.

FIG. 3 is a waveform diagram showing an operation example of the present embodiment.

FIG. 4 is a waveform diagram showing another operation example of the present embodiment.

FIG. 5 is a waveform diagram showing an operation example of a conventional technique.

FIG. 6 is a waveform diagram showing another operation example of the conventional technique.

[Explanation of symbols]

1 motor 2 Motor control device 6 Magnetic pole detection element 7 Inverter circuit 8 control unit 9 power lines

Claims (2)

[Claims] 1. A motor control device for controlling a rotational state of a brushless DC motor by outputting a pulse width modulation type drive signal to a brushless DC motor, wherein a drive signal whose duty is gradually increased is output when the brushless DC motor is started. A motor control device characterized by the above. 2. A motor controller for controlling a rotation state of a brushless DC motor by outputting a pulse width modulation type drive signal to a brushless DC motor, and detecting that the duty of the drive signal exceeds a predetermined reference level. Then, the motor control device is characterized by outputting a drive signal whose duty is gradually reduced to stop the rotation of the brushless DC motor.