JP4230743B2 - Motor drive device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a motor drive device, and more particularly to a digital sensorless motor drive device.
[0002]
[Prior art]
FIG. 5 shows a block diagram of a conventional digital sensorless motor rotating device that is driven without using a position sensor.
[0003]
The motor drive control circuit 101 includes an interface unit 103, a signal synchronization unit 104, a timing generation unit 105, a back electromotive force detection unit 106, an energized phase control unit 107, a comparator signal processing unit 108, a PWM signal synthesis unit 109, and a pre-driver unit 110. It is composed of
[0004]
The motor drive control circuit 101 generates an energization waveform and rotates the motor 102. That is, the energization waveforms generated by the motor drive control circuit 101 are sequentially applied to the star-connected three-phase energization layers U, V, and W in order to rotate the rotor (not shown).
[0005]
An energization waveform generated by the motor drive control circuit 101 is shown in FIG. The motor 102 is rotated by sequentially switching energized phases according to the position of the rotor.
[0006]
However, in the energization waveform shown in FIG. 6, the current rises or falls at the time of switching the energized phase, which causes noise. Since this noise becomes a rotation sound of the motor 102, if this motor 102 is used for audio or the like, the rotation noise sound of the motor 102 becomes a problem.
[0007]
Therefore, in order to reduce the rotation noise sound of the motor, a motor driving device as shown in FIG. 7 is used (for example, see Non-Patent Document 1).
[0008]
The motor drive control circuit 201 of the motor drive device includes an nBitDAC (Digital to Analog Converter) unit 211, a selector and an AMP unit 212 in addition to the circuit configuration of the motor drive control circuit 101 of FIG.
[0009]
The motor drive control circuit 201 generates the energization waveform shown in FIG.
[0010]
In the motor drive control circuit 201, after the energized phase switching waveform is taken in as a digital waveform, it is modulated at the energized phase switching timing and converted into an analog signal by DA (Digital to Analog) to convert the energized waveform into a sine waveform. (FIG. 8).
[0011]
Since the energization waveform converted into a sine waveform as shown in FIG. 8 reduces the input voltage at the time of switching the energization phases U, V, and W, it is possible to reduce motor rotation noise.
[0012]
[Non-Patent Document 1]
“TOSHIBA Data Book Motor IC” published by Toshiba Semiconductor Corporation, September 2001, p. 805-820
[0013]
[Problems to be solved by the invention]
However, since the normal DAC unit 211 and the AMP unit 212 in the motor drive control circuit 201 shown in FIG. 7 have a very large circuit scale, the circuit scale of the motor drive control circuit 201 becomes large.
[0014]
For this reason, the motor drive current sine circuit for converting the digital waveform into a sine wave by DA conversion must be an IC different from the motor drive control circuit.
[0015]
Therefore, an object of the present invention is to provide a motor drive device that suppresses an increase in circuit scale of a motor drive control circuit and realizes reduction of motor rotation noise.
[0016]
[Means for Solving the Problems]
In order to solve the above-described problems, the present invention includes a period measurement counter and a delay counter for performing phase shift of a motor drive signal input from an interface unit, and a timing formation unit that forms various count data. a logic circuit including a current phase control circuit for generating a first current waveform signal count data and the motor driving signal Toka et input and the rotational speed detection signal from the forming unit, the count data and formed by said timing forming section Staircase wave generating means for generating a speed control signal including a staircase-like inclination from the rotation speed detection signal formed by the logic circuit, a first energization waveform signal generated by the logic circuit, and the staircase waveform generation By means of the speed control signal generated by the means, a second energization waveform having a staircase with rising and falling edges is generated. To provide a motor drive device that includes a PWM signal combining unit.
[0017]
With the above solution, the second energization waveform having a gentle slope with rising and falling edges can be formed, so that reduction in motor rotation noise can be realized. Further, since the second energization waveform forming means performs digital processing, an increase in circuit scale can be suppressed.
[0018]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 is a block diagram of a motor driving apparatus showing an example of an embodiment of the present invention. An energization waveform generated by the motor drive control circuit 1 shown in FIG. 1 is shown in FIG.
[0019]
The energization waveform shown in FIG. 2 controls the three energized phases U, V, and W that are star-connected in order to rotate the rotor (not shown), and the motor 2 rotates.
[0020]
In the motor drive control circuit 1, the interface unit 3 receives a motor drive signal output from a microcomputer or the like (not shown). The signal synchronization unit 4 is a circuit that synchronizes the motor drive signal.
[0021]
The timing forming unit 5 includes a period measurement counter and a delay counter, and is a circuit that forms various count data.
[0022]
The back electromotive detection unit 6 is a circuit that detects a back electromotive wave included in the first energization waveform signal. The energization phase control unit 7 is a circuit that generates a motor rotation number detection signal (hereinafter referred to as “FG (Feedback Generation) signal”) and a first energization waveform signal. The FG signal is a control signal for controlling the rotation speed of the motor, and is a signal generated together with the first energization waveform signal.
[0023]
The comparator signal processing unit 8 is a comparator circuit that compares the terminal voltage with the reference voltage.
[0024]
A PWM (Pulse Width Modulation) signal synthesizer 9 is a circuit that synthesizes a second energization waveform from the PWM signal and the first energization waveform.
[0025]
The pre-driver unit and the driver unit 10 are driver circuits that cause a current to flow in the energized phase through the second energized waveform.
[0026]
The control wave generator 11 is a circuit that forms several counter waveforms from the FG signal and count data.
[0027]
The staircase wave generation unit 12 is a circuit that forms a staircase waveform from the counter waveform formed in the control wave generation unit 11.
[0028]
Next, an example of a method for forming a second energization waveform in the motor drive control circuit 1 of FIG. 1 will be described with reference to the flowchart shown in FIG. 3 and the waveform diagram shown in FIG.
[0029]
First, the first count data calculated by the timing forming unit 5 is taken into the control wave generating unit 11 (step 1).
[0030]
Next, the first count data taken in is calculated again at an arbitrary timing to generate second count data. The arbitrary timing and the second count data are held by the control wave generator 11 (step 2).
[0031]
In the present embodiment, the second count data is obtained by dividing the first count data into four, and the arbitrary timing is the timing of the fourth division closest to the falling edge of the FG signal.
[0032]
The division width of the second count data corresponds to the start point of the staircase waveform described later. Therefore, if the number of divisions is reduced, the output of the staircase waveform starts earlier, and conversely, if the number of divisions is increased and the division width is reduced, the output start of the staircase waveform is delayed. Therefore, it is not limited to dividing into four as in the present invention, and it is necessary to determine the number of divisions in accordance with each motor driving device.
[0033]
Next, the first count data is recalculated to generate third count data. This third count data is also held by the control wave generator 11 (step 3).
[0034]
The third count data in this embodiment is obtained by further dividing the count of the second count data into four.
[0035]
The number of divisions of the third count data corresponds to the number of steps in the step waveform described later. Therefore, when the number of divisions is increased, the number of steps in the staircase waveform is increased and the resolution of the inclination is increased. Conversely, when the number of divisions is small, the number of steps in the staircase waveform is reduced, the resolution of the slope is low, and the slope becomes rough. Therefore, it is not limited to dividing into 4 like this invention.
[0036]
Next, the rising edge of the next cycle of the FG signal that has taken in the first count data is detected, and the fourth division closest to the arbitrary timing of the second count data, that is, the falling edge of the FG signal is detected. From the count timing, the timing of the third count data is counted four times (step 4).
[0037]
Next, the falling edge of the FG signal is detected, and the timing of the third count data is counted four times (step 5).
[0038]
Next, in order to generate four steps in the data counted before and after the fall of the FG signal, the data counted as 1, 2, 3, 4, 3, 2, 1 is converted into 3-bit data (STAIR1, STAIR2, STAIR4 ) As output from the control wave generator 11 (step 6).
[0039]
Next, the voltage is switched from the 3-bit data (STAIR1, STAIR2, STAIR4) output from the control wave generator 11, and a staircase voltage is generated from the staircase generator 12 (step 7).
[0040]
The staircase wave generator 12 combines the generated staircase voltage and the speed control signal to generate a staircase speed control signal.
[0041]
Note that the slope of the staircase can be adjusted by controlling the voltage value of the staircase wave. That is, when the voltage value is set large, the staircase slope becomes steep, but when the voltage value is set small, the staircase slope becomes gentle. This staircase voltage value can be controlled by inputting a staircase tilt control signal from the interface unit 3 to the staircase wave generator 12.
[0042]
The second energization waveform shown in FIG. 2 can be generated by synthesizing the stepped wave speed control signal and the first energization waveform output from the energization phase control unit 7 by the PWM signal synthesis unit 9. (Step 8).
[0043]
This second energization waveform is input to the three energization phases U, V, and W via the pre-driver unit 10 (step 9).
[0044]
Since the rise of the second energization waveform shown in FIG. 2 is a gentle rise due to the staircase wave, the input voltage can be lowered as in the case of the sine wave. Therefore, the motor rotation noise can be reduced.
[0045]
In addition, since the second energization waveform is generated by digital processing, there is no need for a DAC or an amplifier, and an increase in circuit scale can be suppressed.
[0046]
【The invention's effect】
As described above in detail, the present invention can provide a motor drive device that suppresses an increase in circuit scale of a motor drive control circuit and realizes a reduction in motor rotation noise.
[Brief description of the drawings]
FIG. 1 is a block diagram of a motor driving apparatus showing an example of an embodiment of the present invention.
FIG. 2 is a waveform diagram showing energization waveforms formed by the motor drive device of FIG. 1;
FIG. 3 is a flowchart showing a procedure for forming the energization waveform of FIG. 2;
FIG. 4 is a waveform diagram showing a procedure for forming a staircase wave.
FIG. 5 is a block diagram of a conventional motor driving apparatus.
6 is a waveform diagram showing energization waveforms formed by the motor drive device of FIG. 5. FIG.
FIG. 7 is a block diagram of a motor drive device that forms a sine wave energization waveform of the prior art.
8 is a waveform diagram showing a sine wave energization waveform formed by the motor drive device of FIG. 7; FIG.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Motor drive control circuit 2 ... Motor 3 ... Interface part 4 ... Signal synchronization part 5 ... Timing formation part 6 ... Back electromotive force detection part 7 ... Energized phase control part 8 ... Comparator signal processor 9 ... PWM signal synthesizer 10 ... Pre-driver and driver 11 ... Control wave generator 12 ... Stair wave generator

Claims (5)

A timing forming unit for forming various count data, including a period measurement counter and a delay counter for performing phase shift of a motor drive signal input from the interface unit;
A logic circuit including a current phase control circuit for generating count data and the motor driving signal Toka et first energization waveform signal and the rotational speed detection signal inputted from the timing formation unit,
Staircase wave generating means for generating a speed control signal including a staircase-like inclination from the count data formed by the timing forming unit and the rotation speed detection signal formed by the logic circuit;
A PWM signal for generating a second energization waveform with rising and falling steps having a staircase-like inclination based on the first energization waveform signal generated by the logic circuit and the speed control signal generated by the staircase waveform generation means. A motor driving device including a combining unit. The speed control signal including the step-like inclination generated by the step wave generation means is:
2. The motor drive device according to claim 1, wherein the motor drive device is a speed control signal having a step-like slope following a falling edge of the rotation speed detection signal generated by the logic circuit. The staircase wave generation means is composed of a control wave generation unit and a staircase wave generation unit,
The control wave generator is
Means for taking in the first count data calculated by the timing forming section in a first cycle of the rotation speed detection signal;
Means for generating and holding second count data obtained by dividing the first count data by n;
Means for generating and holding third count data obtained by dividing the first count data by m;
First counting means for detecting a rising edge of a second period of the rotation speed detection signal and counting third count data from an arbitrary timing of the second count data;
A second counting means for detecting a falling edge of a second period of the rotational speed detection signal and counting third count data from the falling edge;
The step wave generator is
Means for generating a staircase voltage from the first and second counting means;
2. The motor driving apparatus according to claim 1, further comprising means for synthesizing the stepped wave voltage and the speed control signal to generate a speed control signal including the stepped inclination.   2. The motor drive according to claim 1, wherein the second energization waveform is output from the interface unit, and the inclination can be controlled by a step inclination control signal for controlling a voltage value of the second energization waveform. apparatus.   5. The motor driving device according to claim 1, wherein the motor rotates by applying a voltage of the second energization waveform to an energization phase of the motor.

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