JP2005110368A - Motor driving unit, integrated circuit, and motor driving method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To switch a gain for outputting a control signal. <P>SOLUTION: A motor driving unit, which has a drive transistor for supplying a coil with a coil current, and a control circuit for outputting a control signal for controlling the action of the above drive transistor, according to an instruction signal directing the rotational speed of a motor, is equipped with a gain switching means which switches a gain for outputting the above control signal set in the above control circuit, according to whether the value of the above instruction signal is larger or smaller than a predetermined value. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a motor driving device, an integrated circuit, and a motor driving method.

For example, a motor driver that drives and controls a motor that rotates an optical disk includes a drive transistor that supplies a coil current to the coil, and a control signal that controls the operation of the drive transistor in accordance with an instruction signal that instructs the rotation speed of the motor. And a control circuit for outputting. In particular, the control circuit has a normal rotation logic for applying a normal rotation torque to the motor and a reverse rotation logic for applying a reverse rotation torque to the motor. In other words, when the optical disk is stopped from the mode in which data is recorded on the optical disk or data is reproduced from the optical disk, the motor driver switches from the forward rotation logic to the reverse rotation logic and sends a control signal corresponding to the magnitude of the instruction signal. Output, decelerate the motor and finally stop. Specifically, when the motor driver outputs a control signal in the reverse rotation logic, the motor receives the reverse rotation torque and decelerates, and when the motor driver prohibits the control signal in the reverse rotation logic at an appropriate timing, the motor does not reverse. Will stop.
JP 2000-228020 A

  Since a set of a disc player or the like having the motor driver described above executes a plurality of operation sequences, it is desirable that the time for stopping the motor is as short as possible. However, in the motor driver, although the magnitude of the control signal corresponds to the magnitude of the instruction signal, since the gain of the control signal is constant, it is difficult to shorten the time for stopping the motor. As a result, there is a problem that the time for the set to execute a plurality of operation sequences becomes long.

  SUMMARY An advantage of some aspects of the invention is that it provides a motor driving device, an integrated circuit, and a motor driving method capable of switching a gain for outputting a control signal.

  The main invention for solving the above problems is to output a control signal for controlling the operation of the drive transistor in response to an instruction signal for instructing the rotational speed of the motor and a drive transistor for supplying a coil current to the coil A control circuit configured to output the control signal set in the control circuit according to whether the value of the instruction signal is larger or smaller than a predetermined value. Gain switching means for switching the gain for this purpose.

  According to the present invention, the gain for outputting the control signal set in the control circuit is switched according to whether the value of the instruction signal is larger or smaller than a predetermined value. This allows the motor to quickly transition to a different mode.

  At least the following matters will become apparent from the description of this specification and the accompanying drawings.

=== Configuration of Motor Drive Device ===
The motor drive device of the present invention will be described with reference to FIG. FIG. 1 is a circuit block diagram for explaining a motor drive device of the present invention. In this embodiment, the motor driven by the drive device is a motor having a sensor (for example, a hall element) for detecting the position of the rotor, but is not limited to this. For example, it may be a sensorless motor.

The U-phase coil 2, the V-phase coil 4, and the W-phase coil 6 are star-connected and wound around a stator with a phase difference of 120 electrical degrees.
The NPN bipolar transistor 8 is a source transistor for supplying a coil current from the power supply VCC to the U-phase coil 2, and the NPN bipolar transistor 10 is a sink for supplying a coil current from the U-phase coil 2 to the ground VSS. It is a transistor. The collector-emitter paths of these transistors 8 and 10 are connected in series between the power supply VCC and the ground VSS, and the collector-emitter connection of these transistors 8 and 10 is connected to one end of the U-phase coil 2.
The NPN bipolar transistor 12 is a source transistor for supplying a coil current from the power supply VCC to the V-phase coil 4, and the NPN bipolar transistor 14 is for supplying a coil current from the V-phase coil 4 to the ground VSS. This is a sink transistor. The collector-emitter paths of these transistors 12 and 14 are connected in series between the power supply VCC and the ground VSS, and the collector-emitter connection of these transistors 12 and 14 is connected to one end of the V-phase coil 4.
Further, the NPN bipolar transistor 16 is a source transistor for supplying a coil current from the power supply VCC to the W-phase coil 6, and the NPN bipolar transistor 18 is for supplying a coil current from the W-phase coil 6 to the ground VSS. This is a sink transistor. The collector-emitter paths of these transistors 16, 18 are connected in series between the power supply VCC and the ground VSS, and the collector-emitter connection of these transistors 16, 18 is connected to one end of the W-phase coil 6.
When the transistors 8, 10, 12, 14, 16, and 18 are turned on and off at appropriate timing, the motor supplies a coil current to the U-phase coil 2, the V-phase coil 4, and the W-phase coil 6. It rotates in the direction (for example, normal rotation). As a result, a coil voltage having a phase difference of 120 electrical degrees appears at one end of the U-phase coil 2, the V-phase coil 4, and the W-phase coil 6. As the source transistor and the sink transistor, not only a bipolar transistor but also a MOSFET can be used.

  The Hall elements 20, 22, and 24 are provided at the outer peripheral position of the rotor that generates a phase difference of 120 degrees in electrical angle, and have a phase difference of 120 degrees in electrical angle according to the change of the magnetic pole when the rotor rotates. A sine wave Hall signal is output. This hall signal is a signal indicating the rotational position of the rotor. The hall amplifier 26 amplifies a hall signal having a minute amplitude. In particular, the hall amplifier 26 amplifies the amplitude of the hall signal until logic processing based on the hall signal becomes possible in the control circuit at the subsequent stage.

  In the drive logic 28, one of a normal rotation logic for applying a normal rotation torque to the motor or a reverse rotation logic for applying a reverse rotation torque to the motor is set in accordance with an instruction from a microcomputer or the like. Specifically, when the forward rotation logic is set, the drive logic 28 is configured in the appropriate order to give the forward rotation torque to the motor according to the amplification signal of the hall amplifier 26 indicating the rotation position of the rotor. A logic signal for turning on / off 12, 14, 16, 18 is output. In addition, when the reverse logic is set, the drive logic 28 has the transistors 8, 10, 12, 14 in an appropriate order for applying reverse torque to the motor according to the amplification signal of the hall amplifier 26 indicating the rotational position of the rotor. , 16 and 18 are output as logic signals. The pre-driver 30 outputs a drive signal (control signal) for turning on / off the transistors 8, 10, 12, 14, 16, 18 in accordance with a logic signal from the drive logic 28. Thereby, the coil current is supplied to the U-phase coil 2, the V-phase coil 4, and the W-phase coil. Note that the drive logic 28 and the pre-driver 30 are control circuits.

  The gain switching circuit 32 (gain switching means) sets the forward rotation logic or the reverse rotation logic in the drive logic 28 according to the magnitude of the input voltage VIN (instruction signal) from the microcomputer or the like, and the drive signal to the pre-driver 30. The gain is set. For example, when the input voltage VIN> the reference voltage V <b> 1, the gain switching circuit 32 sets the normal rotation logic in the drive logic 28 and sets the gain A in the pre-driver 30. Further, when the reference voltage V2 (predetermined value) <input voltage VIN <reference voltage V1, the gain switching circuit 32 sets the reverse logic in the drive logic 28 and sets the gain A in the predriver 30. Further, the gain switching circuit 32 sets the gain B that is larger than the gain A in the pre-driver 30 while the reverse logic is set in the drive logic 28 when the input voltage VIN ≦ the reference voltage V2. As a result, the reverse torque of the motor changes using the reference voltage V2 as a threshold value.

  The resistor 34 converts the coil currents of the U-phase coil 2, the V-phase coil 4, and the W-phase coil 6 into a voltage VZ through the transistors 10, 14, and 18 on the source side. The voltage VZ generated by the resistor 34 is a voltage proportional to the rotation speed of the motor, and can be used as information for controlling the rotation speed of the motor.

=== Example of gain switching circuit ===
A gain switching circuit used in the motor drive device of the present invention will be described with reference to FIG. FIG. 2 is a circuit block diagram for explaining a gain switching circuit used in the motor drive device of the present invention. Note that the gain switching circuit in FIG. 2 is merely an example, and the present invention is not limited to this. The gain switching circuit may be any circuit as long as the gain of the pre-driver 30 can be switched.

  The gain switching circuit 32 includes NPN bipolar transistors 102 and 104 that are differentially connected, PNP bipolar transistors 106, 108, 110, and 112 that are current mirror connected, a comparator 114, and an NPN bipolar transistor 116 in series. Resistors 118 and 120 to be connected and an amplifier 122 are included.

  The transistors 102 and 104 operate according to the difference between the input voltage VIN and the reference voltage V1. That is, the collector-emitter currents of the transistors 102 and 104 increase / decrease in proportion to the input voltage VIN. The comparator 114 outputs a high level or a low level depending on the magnitude of the input voltage VIN and the reference voltage V2. The transistor 116 is turned on / off according to the output of the comparator 114. That is, the transistor 116 is turned on when the input voltage VIN> the reference voltage V2, and is turned off when the input voltage VIN ≦ the reference voltage V2. The resistor 118 has a value for setting the gain A. The resistors 118 and 120 have a value for setting the gain B. The amplifier 122 controls the drive logic 28 and the pre-driver 30 according to the difference between the voltage VG generated at the resistor 118 and the voltage VZ.

=== Operation of Motor Drive Device ===
The operation of the motor drive device of the present invention will be described with reference to FIGS. FIG. 3 is a diagram showing gain switching characteristics of the motor drive device of the present invention. In FIG. 3, the horizontal axis represents the input voltage VIN supplied to the gain switching circuit 32, and the vertical axis represents the drive signal output from the pre-driver 30. Specifically, when the input voltage VIN is between the voltages VA and VB, the pre-driver 30 outputs a zero drive signal regardless of the input voltage VIN. When the input voltage VIN is between the voltages VB and VC, the pre-driver 30 outputs a drive signal that is proportional to the input voltage VIN with a gain A. When the input voltage VIN is between the voltages VA and VD, the pre-driver 30 outputs a drive signal with a gain A that is inversely proportional to the input voltage VIN. Further, when the input voltage VIN is between the voltages VD and VE, the pre-driver 30 outputs a drive signal having a gain B and inversely proportional to the input voltage VIN. Further, when the input voltage VIN is larger than the voltage VC or smaller than the voltage VE, the pre-driver 30 outputs a drive signal having a constant value (current limit value) regardless of the input voltage VIN. The reference voltage V1 is a substantially intermediate voltage between the voltages VA and VB, and the reference voltage V2 is the voltage VD.

  Hereinafter, an operation sequence for stopping the motor will be described.

≪Input voltage VIN> Reference voltage V1≫
The drive logic 28 is set to the normal rotation logic when the gain switching circuit 32 detects that the input voltage VIN> the reference voltage V1. The drive logic 28 is a logic for turning on and off the transistors 8, 10, 12, 14, 16, and 18 in an appropriate order to give a normal rotation torque to the motor in accordance with the amplified signal of the hall amplifier 26 indicating the rotational position of the rotor. Output a signal. Further, since the comparator 114 outputs a high level and the transistor 116 is turned on, both ends of the resistor 120 are short-circuited. That is, the voltage VG is determined only by the resistor 118 according to the input voltage VIN. The pre-driver 30 outputs a drive signal that changes with a gain A in order to turn on and off the transistors 8, 10, 12, 14, 16, and 18. As a result, the motor rotates in response to the forward rotation torque.

<< Reference voltage V2 <Input voltage VIN <Reference voltage V1 >>
In order to stop the motor, the input voltage VIN starts to drop from a value that is greater than the voltage VB. The drive logic 28 is set to reverse logic when the gain switching circuit 32 detects that the input voltage VIN <reference voltage V1. The drive logic 28 is a logic signal for turning on and off the transistors 8, 10, 12, 14, 16, and 18 in an appropriate order to give reverse rotation torque to the motor according to the amplified signal of the hall amplifier 26 indicating the rotational position of the rotor. Is output. Further, since the comparator 114 outputs a high level and the transistor 116 is turned on, both ends of the resistor 120 are short-circuited. That is, the voltage VG is determined only by the resistor 118 according to the input voltage VIN. The pre-driver 30 outputs a drive signal that changes with a gain A in order to turn on and off the transistors 8, 10, 12, 14, 16, and 18. As a result, the motor receives the reverse torque and decelerates.

≪Input voltage VIN ≦ reference voltage V2≫
In order to stop the motor, the input voltage VIN further decreases from the voltage V2. Since the comparator 114 outputs a low level and the transistor 116 is turned off, both ends of the resistor 120 are not short-circuited. That is, the voltage VG is determined by the resistors 118 and 120 according to the input voltage VIN. The pre-driver 30 outputs a drive signal that changes with a gain B in order to turn on and off the transistors 8, 10, 12, 14, 16, and 18. As a result, the motor decelerates in a short time in response to the reverse torque larger than the reverse torque. The motor drive device stops the operation of the pre-driver 30 according to the value of the voltage VZ generated by the resistor 34. As a result, the motor stops without reversing.
As described above, the motor driving device according to the present invention can effectively stop the motor in a short time by switching the gain of the pre-driver 30, and is thus effective for a set of a disc player or the like that executes a plurality of operation sequences.

=== number of reference voltages V2 ===
In this embodiment, the single reference voltage V2 is set to the potential difference of the input voltage VIN that is inversely proportional to the drive signal. However, the present invention is not limited to this. For example, a plurality of reference voltages V2 may be set to the potential difference of the input voltage VIN that is inversely proportional to the drive signal. That is, a plurality of comparators 114, transistors 116, and resistors 120 may be provided. Thereby, the gain of the pre-driver 30 can be switched a plurality of times to effectively stop the motor.

=== Value of the reference voltage V2 ===
In the present embodiment, the reference voltage V2 is a fixed value, but is not limited to this. For example, the reference voltage V2 may be a variable value according to specifications such as a set and a motor. Thereby, the timing which switches the gain of the predriver 30 can be changed, and a motor can be stopped effectively.

=== Integrated circuit ===
In this embodiment, the motor driving device may be an integrated circuit formed on a silicon wafer. Thereby, the optical disk medium, the hard disk medium, the flexible disk medium, and the like can be effectively incorporated into a set using the optical disk medium, the hard disk medium, the flexible disk medium, and the like. Furthermore, the integrated circuit may have an external terminal for setting the reference voltage V2. Accordingly, the motor can be effectively stopped by appropriately changing the reference voltage V2.

=== Motor drive method ===
The transistors 8, 10, 12, 14, 16, and 18 that supply coil currents to the U-phase coil 2, the V-phase coil 4, and the W-phase coil 6, and the input voltage VIN that indicates the rotation speed of the motor In a motor drive device having a drive logic 28 for outputting a drive signal for controlling operations of 10, 12, 14, 16, 18 and a pre-driver 30, a reference voltage having a predetermined value of the input voltage VIN A motor driving method that switches the gain for outputting the driving signal set to the pre-driver 30 depending on whether V2 is larger or smaller than the value can also be realized.

=== Other Embodiments ===
As mentioned above, although the motor drive device, integrated circuit, and motor drive method concerning this invention were demonstrated, said description is for making an understanding of this invention easy, and does not limit this invention. The present invention can be changed and improved without departing from the gist thereof, and the present invention includes the equivalents.

  The reference voltage V2 may be set singly or in plural to the potential difference of the input voltage VIN that is proportional to the drive signal. Thereby, the motor can be effectively accelerated to a predetermined speed.

It is a circuit block diagram for demonstrating the motor drive device of this invention. It is a circuit block diagram for demonstrating the gain switching circuit used for the motor drive device of this invention. It is a figure which shows the gain switching characteristic of the motor drive device of this invention.

Explanation of symbols

2 U-phase coil 4 V-phase coil 6 W-phase coil 8, 10, 12, 14, 16, 18 Transistor 28 Drive logic 30 Pre-driver 32 Gain switching circuit 114 Comparator 116 Transistor 118, 120 Resistance 122 Amplifier

Claims (7)

In a motor drive device comprising: a drive transistor that supplies a coil current to the coil; and a control circuit that outputs a control signal for controlling the operation of the drive transistor in response to an instruction signal that instructs the rotation speed of the motor.
A gain switching means for switching a gain for outputting the control signal set in the control circuit according to whether the value of the instruction signal is larger or smaller than a predetermined value;
A motor driving device comprising:   The gain switching means has the predetermined value from when the motor is decelerated until it stops, and when the instruction signal reaches a predetermined value, the gain is changed from small to large. The motor drive device according to claim 1, wherein the motor drive device is switched.   The motor driving apparatus according to claim 1, wherein the predetermined value is plural.   The motor driving apparatus according to claim 1, wherein the predetermined value is variable.   5. An integrated circuit obtained by integrating the motor driving device according to claim 1.   6. The integrated circuit according to claim 5, further comprising an external terminal for setting the predetermined value. In a motor drive device comprising: a drive transistor that supplies a coil current to the coil; and a control circuit that outputs a control signal for controlling the operation of the drive transistor in response to an instruction signal that instructs the rotation speed of the motor.
Switching a gain for outputting the control signal set in the control circuit, depending on whether the value of the instruction signal is larger or smaller than a predetermined value;
The motor drive method characterized by the above-mentioned.

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