JP2002078375A - Motor controller and control method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a motor driver which can conduct correct switching operation of a current at driving, without complicating the structure of a sensorless motor, and to provide a method of driving the same motor driver. SOLUTION: A positive reverse circuit 40 for controlling the rotating direction of a motor 200 and a coil position detecting circuit 50 for detecting the position of coil, based on an inverse electromotive force are provided. Thereby, a motor drive direction is set in the reverse direction with the reversible rotation circuit 40, when the motor is driven. A drive current is generated in the prescribed timing and is then supplied to the coil. After the position of coil has been detected with a coil position detection circuit 50; the drive direction of motor is set to the normal direction with the reversible rotation circuit 40; and a drive current is generated in the prescribed timing and is then supplied to the coil. When the coil position is detected accurately with the coil position detection circuit 50, the drive current supplied to the coil is controlled, based on the detected position for the normal drive.

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 driving a sensorless motor, and more particularly to a motor control device capable of reliably starting the sensorless motor and improving the success rate of starting.

[0002]

2. Description of the Related Art A brushless motor, which is widely used today, detects an armature coil arranged as a stator (stator), a magnet as a rotor (rotating element), and a coil position detection (rotor phase detection). And the like. In a brushless motor, there are many parts that require accuracy, such as the arrangement of a stator, a rotor, and a Hall element, so that it is difficult to reduce the size and simplify the assembly. For this reason, a so-called sensorless motor, in which a rotor detecting Hall element of a brushless motor is eliminated, is often used as a drum motor in a magnetic tape recording apparatus.

In such a sensorless motor, the position of the rotor is detected by using the induced voltage of the coil instead of the Hall element signal and detecting the back electromotive force. However, since the induced voltage of the coil is output only when the rotor is rotating, the drive circuit needs a mechanism for forcibly rotating the rotor only at startup.

The driving of the sensorless motor is performed by controlling the direction of the current flowing through the winding of the coil and the timing thereof by a driving IC. When the magnetic field inside the motor is changed, and a rotor composed of permanent magnets (magnets) is placed in this magnetic field, the rotor is dragged around by the magnetic field, but when controlling a sensorless motor with multiple coils, It is necessary for the drive IC to correctly determine which current flows in which coil during driving, that is, how to switch the coil drive current.

[0005]

However, in the case of using the conventional starting method in which the motor is simply started only in the normal rotation direction, even if a voltage change is applied to the coil during the starting processing of the motor, the driving IC is not used. The back electromotive force of the coil could not be detected properly, and the coil position (rotor phase) could be erroneously detected. As a result, the switching of the current flowing through the coil and the rotation of the rotor do not match, and the motor may fail to start due to the inertial force of the rotor trying to stop.

[0006] In order to avoid such a failure in starting the sensorless motor, there has conventionally been a method of accurately detecting the coil position by using a phototransistor, a Hall element, or the like to ensure the start of the motor. However, in these methods, components that are not directly required for driving the motor are used, so that the structure of the motor is complicated, the volume of the motor is increased, and the manufacturing cost is disadvantageously increased.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an object of the present invention is to make it possible to correctly switch a current at the time of startup without complicating the structure of a sensorless motor and to surely improve the success rate of startup. It is an object of the present invention to provide a motor driving device and a driving method thereof.

[0008]

In order to achieve the above object, a motor control device of the present invention is a motor control device for controlling a brushless motor, comprising: a rotation direction control means for controlling a rotation direction of the motor; Based on the back electromotive force generated in the coil of the motor, a coil position detecting means for detecting the position of the coil, when starting the motor,
The rotation direction control means sets the starting direction of the motor to the reverse direction, generates a drive current at a predetermined timing, supplies the drive current to the coil, and detects the position of the coil by the coil position detection means. When the starting direction of the motor is set to the normal rotation direction by the rotation direction control means, the drive current is generated at a predetermined timing and supplied to the coil, and when the position of the coil is detected by the coil position detection means And control means for controlling a drive current supplied to the coil based on the detected position.

Further, the present invention preferably has timing control means for controlling the supply timing of the drive current supplied to the coil at the time of starting.

[0010] In the present invention, preferably, there is provided switching means for controlling a drive current supplied to the coil based on the detected position of the coil.

In the present invention, preferably, the control means repeats the control for starting the motor in the reverse direction and then in the normal direction until the position of the coil is reliably detected. Do.

A motor control method according to the present invention is a motor control method for controlling a brushless motor, wherein when starting the motor, the starting direction of the motor is set to a reverse direction, and at a predetermined timing. Generating a drive current and supplying it to the coil of the motor;
Detecting the position of the coil based on the back electromotive force generated in the coil, setting the start direction of the motor to the normal rotation direction, generating a drive current at a predetermined timing, and supplying the drive current to the coil A step of detecting a position of the coil, and a step of controlling a drive current supplied to the coil based on the detected coil position and supplying the current to the coil.

In the present invention, preferably, the control for starting the motor in the reverse rotation direction and then in the normal rotation direction is repeated until the position of the coil is reliably detected.

[0014]

FIG. 1 is a block diagram showing one embodiment of a motor driving device according to the present invention. As illustrated, the motor drive device 100 of the present embodiment includes a start control circuit 1
0, a timing control circuit 20, a switching circuit 30,
It comprises a forward / reverse rotation circuit 40, a rotor position detection circuit 50, an output drive circuit 60, and an external capacitor 70. Hereinafter, the configuration and function of each part of the motor drive device will be described.

The start control circuit 10 is a circuit for determining the timing of current switching to each coil when the motor is started. At startup, the startup control circuit 10 determines the constant of the externally connected capacitor 70, for example, the capacitor 7
Switching is controlled at a timing determined by the capacitance value of 0.

The timing control circuit 20 is a circuit for determining the timing of current switching based on the result of detection of the rotor position. The switching circuit 30 includes a motor 200
The current supplied to each of the coils (coils U, V, W) is determined. The switching circuit 30 includes the timing control circuit 20
The levels of the currents I _U , I _V, and I _W output to the coils U, V, W are determined at the timing set by
For example, respective currents are determined such that I _U is at a high level, I _V is at a middle level, and I _W is at a low level.

The forward / reverse rotation circuit 40 is a circuit for controlling the rotation direction of the motor. The rotor position detection circuit 50 is a circuit that detects the position of the rotor by detecting the back electromotive force of the coil. As shown, the rotor position detection circuit 50
Inputs coil U of the motor 200, V, the counter electromotive force generated by the W voltage U _in, as V _in and W _in, in accordance with these voltages, the counter electromotive force induced in the coil U, V, W Is detected, and the position of the rotor is detected according to the result. The output drive circuit 60 includes the switching circuit 30
A predetermined current is output to the coil determined by the above.

The above-described motor control device 10 of the present embodiment
0 indicates that when starting the sensorless motor, the motor is not started only in the normal rotation direction as in the conventional method, and the coil is reliably driven by alternately driving the motor in the normal rotation direction and the reverse rotation direction during the startup processing. Is detected, and current switching to a plurality of coils is correctly performed according to the detection result, thereby realizing stable start-up of the motor.

If the motor drive device 100 can correctly detect the position of the coil during the motor start-up process, it is possible to correctly switch the current to the coil, so that the motor can be expected to start stably. .
Here, it should be noted that, in the case of a sensorless motor, when the distance between the permanent magnet of the rotor and the coil of the stator is large, it is difficult to detect the back electromotive force of the coil. There is a phase of the rotor that is likely to fail to start due to erroneous detection and consequent failure to switch current correctly.

In order to avoid this, in the motor driving device 100 of the present embodiment, the start-up process is not terminated without reliably detecting the coil position, and the coil position, that is, the phase of the rotor is surely determined in the start-up process. After it is determined that the detection can be performed, the driving is switched to the normal driving in the normal rotation direction. Here, the steady driving refers to a normal driving for switching a current to the coil based on the rotation timing of the rotor.

A processing procedure for performing the above-described activation processing is shown by a flowchart of FIG. Hereinafter, control at the time of startup of the motor control device of the present embodiment will be described with reference to FIGS. 1 and 2.

As shown in FIG. 1, in the motor 200, the coils U, V and W are symmetrically arranged. FIG.
In the above, the coils U, V, and W are connected by a so-called star connection method, but the present invention is not limited to this connection method, and can be applied to other connection methods. In the star connection method, the coils U, V, and W are arranged symmetrically with respect to the structure of the motor. Therefore, in the following description, it is essential to replace the coils U, V, and W with each other. There is no change.

In the starting process, in order to forcibly rotate the stopped rotor, its current switching is performed in accordance with the timing set by the starting control circuit 10 and the timing control circuit 20 (step S00).
1).

First, the starting direction is set to the reverse direction by the forward / reverse circuit 40 (step S002). next,
The coil position is detected by the rotor position detection circuit 50 (step S003). Detection of the coil position, for example, as shown in FIG. 1, and input by the rotor position detection circuit 50, the coil U, V, coil voltage U _in generated by counter electromotive force is W, the V _in and W _in, these This is performed by detecting the phase of each coil according to the amplitude and phase of the voltage.

The voltage to be supplied to each coil is determined according to the result of the coil position detection (step S00).
4). For example, here, the voltages applied to the coils U, V, and W are set to high, medium, and low, respectively. By applying a drive voltage to the coil, a coil current flows and a magnetic field is generated. For this reason, when the rotor to which the permanent magnet is attached rotates in the reverse rotation direction, a back electromotive force is generated from the coil in a direction in which the relative movement between the coil and the permanent magnet is to be stopped.

Next, the method of starting the motor is switched, and the starting direction is set to the normal direction by the normal / reverse circuit 40 (step S005). And coil U,
The voltages applied to V and W are set to low, medium, and high, respectively (step S006). Switching the rotation direction in this way is performed by the relative movement between the permanent magnet attached to the rotor that has started to rotate in the reverse rotation direction and the coil whose voltage setting has been switched in the forward rotation direction. The counter electromotive force generated in the direction in which the relative movement with respect to the coil is stopped is larger than that in the case where the voltage is set while the coil is in the reverse rotation direction.
This is to make it easy to detect the coil position of 0.

Next, it is determined whether or not the coil position has been detected (step S007). As a result of the determination, when the coil position is detected, the process proceeds to the next step S008, and when the coil position is not detected, the process returns to the step S002, and the starting direction of the motor is set to the reverse rotation direction. The position of the coil is detected.

The above-described processing is repeated from step S002 to step S006 until the position of the coil is detected, so that the coil position can be reliably detected. In addition, the above-described steps S002 to S00
6, the number of repetitions set in advance is set as a fixed value, and the motor control circuit 100 sets the number of steps S002 to S0 within the number of times of the fixed value at startup.
The process up to 06 is repeatedly executed, and the position of the coil can be reliably detected.

After the coil position is detected, the coil position information is output to the timing control circuit 20 by the rotor position detection circuit 50 (step S008). In the timing control circuit 20, current switching timing is set based on the rotor position information (step S009). Then, according to the timing set by the timing control circuit 20, the switching circuit 3
0 outputs a control signal for switching the drive current supplied to the coil to the output drive circuit 60. In response, the output drive circuit 60 supplies a predetermined drive current to each of the coils U, V, and W.

By the above-described starting process, the position of the coil can be reliably detected, current switching can be performed correctly, and stable motor driving can be realized. Compared to traditional boot methods, you can avoid boot failures,
The motor can be started reliably.

[0031]

As described above, according to the motor control device and the control method thereof of the present invention, the coil position of the motor can be reliably detected at the time of starting, and accordingly, the coil current can be correctly detected at the time of starting. Switching can be performed, and an improvement in the activation success rate can be realized. Further, according to the present invention, when compared with a method that improves the motor start success rate by detecting the position of the coil using elements that are not directly necessary for driving the motor, such as a Hall element and a phototransistor, according to the present invention. According to the motor control device of the present invention, elements not directly required for driving the motor can be omitted, the structure of the motor can be simplified, miniaturization and weight reduction can be easily realized, and motor design and manufacturing costs can be reduced. There are advantages.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing one embodiment of a motor control device according to the present invention.

FIG. 2 is a flowchart illustrating a process when the motor control device is started.

[Description of Signs] 100: Motor control device, 10: Start control circuit, 20:
Timing control circuit, 30 ... switching circuit, 40 ...
Forward / reverse rotation circuit, 50: rotor position detection circuit, 60: output drive circuit, 70: capacitor, 200: motor.

Claims (6)

[Claims] 1. A motor control device for controlling a brushless motor, comprising: rotation direction control means for controlling a rotation direction of the motor; and detecting a position of the coil based on a back electromotive force generated in a coil of the motor. When the motor is started, the starting direction of the motor is set to the reverse direction by the rotation direction control means, and a drive current is generated at a predetermined timing and supplied to the coil. After detecting the position of the coil by the position detecting means, the rotation direction control means sets the starting direction of the motor to the normal rotation direction, generates the driving current at a predetermined timing, and supplies the driving current to the coil. When the position of the coil is detected by the coil position detecting means, the drive power supplied to the coil is determined based on the detected position. Motor control device and a control means for controlling. 2. The motor control device according to claim 1, further comprising timing control means for controlling a timing of supplying a drive current to be supplied to said coil at the time of starting. 3. Based on the detected position of the coil,
2. The motor control device according to claim 1, further comprising switching means for controlling a drive current supplied to said coil. 4. The motor control device according to claim 1, wherein the control means repeatedly starts the motor in the reverse direction and then starts the motor in the normal direction until the position of the coil is detected. . 5. A motor control method for controlling a brushless motor, comprising the steps of: when starting the motor, setting a starting direction of the motor to a reverse direction; and generating a driving current at a predetermined timing to generate the motor. Supplying the current to the coil, detecting the position of the coil based on the back electromotive force generated in the coil, setting the start direction of the motor to the normal rotation direction, and driving the drive current at a predetermined timing. Generating and supplying to the coil; detecting the position of the coil; and controlling a drive current supplied to the coil based on the detected coil position and supplying the current to the coil. Motor control method. 6. The motor control method according to claim 5, wherein the control of starting the motor in the reverse direction and then starting the motor in the normal direction is repeated until the position of the coil is reliably detected.