JP2008086118A - Motor starting system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a motor starting system where motor driving torque becomes constant even if power voltage changes. <P>SOLUTION: Prescribed power voltage is applied to a motor driver part, and an output signal is outputted and supplied from a speed control signal generating part for generating speed control voltage which is inversely proportional to power voltage as an I/F signal. A speed control signal selector part switches the signal to the speed control signal inputted from outside after a motor is started with the speed control signal generating part for generating the speed control signal corresponding to power voltage until the motor is completely started. The speed control signal is supplied to a comparator as control voltage for PWM conversion with a sawtooth wave and is supplied to the motor driver part as power which is inversely proportional to power voltage. The motor driver part feeds back a motor starting recognition signal being an inner signal to the speed control signal selector part. When the motor is judged to be completely started, the speed control signal selector part controls motor rotation speed by speed control voltage from outside. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a motor start system, and more particularly to a digital motor start system.

  Conventionally, there is a pulse width modulation method for changing the ON / OFF ratio of a pulse signal as a DC motor control method. In this method, speed control is performed by a pulse width modulation (PWM) signal. For example, if ON and OFF are equal to 50%, the average value is 50% of the amplitude. If ON is 70% and OFF is 30%, the average value is 70% of the amplitude. Thus, since the average value changes by changing the ON / OFF ratio, the rotation speed is monitored to change the ON / OFF ratio (pulse width) to obtain a constant rotation speed.

  In a PWM motor drive device, there are a power supply voltage, a speed control signal (PWM Duty), a commutation cycle, and a motor load (characteristic) as elements for starting the motor. When the motor load is determined, an optimum commutation cycle is set from the load characteristics (see, for example, Patent Document 1).

  However, especially in portable devices that use batteries as the power supply voltage, the power supply voltage always decreases, so it is ideal to set and input an optimal speed control signal to start the motor at that voltage. .

  FIG. 4 shows the configuration of a conventional motor starting system.

  In FIG. 4, a predetermined power supply voltage 43 is applied to a motor driver unit 42 that is connected to a motor 41 to control forward rotation / reverse rotation / braking / stopping, and an I / F signal 44 and a PWM signal 45 Have been supplied. The PWM signal 45 is generated by comparing the external input speed control signal 46 and the sawtooth wave 47 by the comparator 48. For example, the motor driver unit 42 includes a digital signal processing unit and a pre-driver unit.

However, in the conventional motor start system, there is no correlation between the power supply voltage and the speed control voltage, and the motor start power (ratio between the power supply voltage and the PWM duty) varies with each start. Sex changed and became unstable. In particular, there is a problem that the motor startability at a low voltage is lowered.
JP-A-9-19179

  An object of the present invention is to provide a motor starting system in which the motor driving torque is constant even when the power supply voltage changes.

  According to one aspect of the present invention, there is provided a motor starting system that controls the rotational speed of a motor by a PWM signal, the means for varying the speed control signal in accordance with the power supply voltage, and the means for PWM converting the speed control signal. And a means for making the power supplied to the motor constant, expressed by the ratio between the power supply voltage and the PWM duty, and a motor starting system.

  According to another aspect of the present invention, a power supply voltage, a speed control signal generating means for generating a speed control voltage inversely proportional to the power supply voltage, an output from the speed control signal generating means, and an external speed control A speed control signal selection means for inputting a signal and selectively outputting one, a PWM conversion comparator for inputting a speed control signal selected by the speed control signal selection means and generating a PWM signal, and the power supply voltage And a motor driver that inputs the PWM signal and controls driving of the motor.

  The motor driver generates a motor start confirmation signal, and after the motor starts, the signal is supplied to the speed control signal selection means to select an external speed control signal.

  According to the present invention, a motor starting system is provided in which the motor driving torque is constant even when the power supply voltage changes.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 shows the configuration of a motor start system according to an embodiment of the present invention.

  The motor starting system shown in FIG. 1 is generally composed of a motor 1, a motor driver unit 2, a speed control signal generation unit 3, a speed control signal selector unit 4, and a comparator 5.

  A predetermined power supply voltage 6 is applied to a motor driver unit connected to the motor 1 to control forward rotation, reverse rotation, braking, stop, and the like, and an output signal from the speed control signal generation unit 3 is an I / F signal 7. Is supplied and supplied. The speed control signal generator 3 generates a speed control voltage that is inversely proportional to the power supply voltage.

  The speed control signal selector 4 is supplied with an internally generated speed control signal 8 and an external input speed control signal 9 that are outputs from the speed control signal generator 3. The speed control signal selector 4 includes a speed control signal generator 3 for generating a speed control signal 8 corresponding to the power supply voltage 6 until the motor 1 is completely started, and an external device after the motor is started. The input speed control signal 9 is switched.

  Here, the speed control signal 8 is supplied to the comparator 5 together with the sawtooth wave 10 as a control voltage for PWM conversion, and the PWM signal 12 converted by the PWM is converted to a power inversely proportional to the power supply voltage by the comparator. To be supplied.

  The motor driver unit 2 feeds back a motor activation confirmation signal 12 that is an internal signal to the speed control signal selector unit 4. When it is determined that the motor 1 is completely started, the speed control signal selector unit 4 performs motor rotation speed control using an external speed control voltage.

  With this configuration, the speed control signal selector 4 selects a speed control voltage that is inversely proportional to the power supply voltage generated by the speed control signal generator 3 until the motor is started, and the motor driver 2 As a PWM signal, the power (voltage ratio) at the time of starting the motor is constant even if the power supply voltage changes.

  After the motor is started, the external speed control signal 9 is selected by the speed control signal selector unit 4 according to the motor start confirmation signal, so that the motor speed can be controlled by the external speed control signal.

  Next, the relationship between the power supply voltage and the speed control signal in the motor starting system according to the embodiment of the present invention will be described with reference to FIG.

  When the power supply voltage changes, the speed control signal generator 3 generates a speed control signal (DC voltage) so that the power (voltage ratio) input to the motor 1 is constant.

  That is, for example, when the power supply voltage decreases, the speed control signal (DC voltage) output according to the decrease of the power supply voltage increases. The power (voltage ratio) input to the motor can be switched by command input from the external interface. That is, in FIG. 2, any one of (A), (B), and (C) is selected by a command.

  Next, as an embodiment, a portable device using, for example, a battery as a power supply voltage suitable for applying the motor starting system of the present invention will be briefly described.

  FIG. 3 is a block diagram showing the configuration of a portable DVD / CD player to which the motor starting system of the present invention is applied.

  In FIG. 3, the portable DVD / CD player 300 includes a power supply circuit 301, and an optical disk 302 on which video signals and / or audio signals, control signals, and the like are recorded is rotationally controlled by a motor driver 303. Since the motor driver 303 is servo-controlled by the servo processor 304 and is configured as described above, the power (voltage ratio) input to the motor (not shown) is constant even when the power supply voltage changes. Such a DC voltage is generated. Laser light 306 is irradiated onto the recording surface of the optical disc 302 from an optical pickup 305 equipped with a red laser. The reflected light is taken into the RFAMP 307 via the optical pickup 305, amplified after photoelectric conversion. The modulation output from the RFAMP 307 is fed back to the servo processor 304 and supplied to the DVD demodulation / correction unit 308 and CD demodulation / correction unit 309. The DVD demodulation / correction unit 308 and the CD demodulation / correction unit 309 include a memory 310 for working for demodulation processing and correction processing. The signal demodulated from the modulated signal by the DVD demodulation / correction unit 308 and error-corrected is supplied to the MPEG2 video decoder 311 and the AC-3 audio decoder 312. The MPEG2 video decoder 311 and the AC-3 audio decoder 312 include a memory 313 for working for decoding processing. In the MPEG2 video decoder 311, the MPEG2 compressed MPEG2 stream is decoded and supplied to the signal processing circuit 314 and the DA converter 315. The video (video) signal that has been subjected to predetermined processing by the signal processing circuit 314 is supplied to the LCD driver 316. The liquid crystal panel 317 is driven by the LCD driver 316, and an image is displayed on the liquid crystal panel 317. The analog-converted video signal is output to the video output terminal 318. In the AC-3 audio decoder 312, the Dolby AC-3 audio signal is decoded and supplied to the DA converter 319. The analog-converted audio signal is output to the audio output terminal 320.

  A series of processing in each demodulation / correction unit and each decoder described above is controlled by a control microcomputer 322 connected via an internal bus 321. A memory card 324 may be connected to the internal bus 321 via a memory card I / F 323. Further, the control microcomputer 322 is connected with a fluorescent display tube microcomputer 326 for controlling a display 325 made of, for example, a fluorescent display tube.

  According to the embodiment of the present invention, when the motor is started, since the ratio between the power supply voltage and the speed control signal (voltage) is constant, the drive torque input to the motor even if the power supply voltage changes (decreases). Becomes constant, and the motor can be reliably started. In addition, even if the load characteristics of the motor change, a driving torque suitable for the load characteristics can be input to the motor, so that adjustment with an external component is not required, so that a significant improvement in efficiency can be achieved in terms of cost.

  The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope of the invention described in the claims, and these are also included in the scope of the present invention. Needless to say.

It is a figure which shows the structure of the motor starting system which concerns on embodiment of this invention. It is explanatory drawing which shows the relationship between the power supply voltage and speed control signal in embodiment of this invention. It is a block diagram which shows the structure of the portable DVD / CD player to which the motor starting system of this invention is applied. It is a figure which shows the structure of the conventional motor starting system.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Motor, 2 ... Motor driver part, 3 ... Speed control signal generation part, 4 ... Speed control signal selector part, 5 ... Comparator, 6 ... Power supply voltage, 7 ... -I / F signal, 8 ... Internally generated speed control signal, 9 ... External input speed control signal, 10 ... Sawtooth wave, 11 ... PWM signal, 12 ... Motor start confirmation signal.

Claims (5)

A motor starting system that controls the rotational speed of a motor by a PWM signal,
Means for varying the speed control signal in accordance with the power supply voltage; means for PWM converting the speed control signal;
Expressed by the ratio of the power supply voltage and PWM duty, means for making the power supplied to the motor constant,
A motor starting system comprising: A motor starting system that controls the rotational speed of a motor by a PWM signal,
A motor start system comprising means for switching a speed control signal for generating the PWM signal during start-up of the motor and after start-up. Means for generating a plurality of the power supplied to the motor;
2. The motor starting system according to claim 1, wherein switching means can be made by command input from an external interface. Power supply voltage,
Speed control signal generating means for generating a speed control voltage inversely proportional to the power supply voltage;
An output from the speed control signal generating means, an external speed control signal is inputted, and a speed control signal selecting means for selectively outputting either one,
A PWM conversion comparator that inputs the speed control signal selected by the speed control signal selection means and generates a PWM signal;
A motor starting system comprising a motor driver for inputting the power supply voltage and the PWM signal and controlling driving of the motor.   5. The motor start system according to claim 4, wherein the motor driver generates a motor start confirmation signal, and after the motor starts, the signal is supplied to the speed control signal selection means to select an external speed control signal.

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