JP4574898B2 - Motor drive device and blower - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a motor drive device that drives a DC brushless motor with an inverter.
[0002]
[Prior art]
FIG. 14 is a circuit configuration diagram of a conventional brushless DC motor driving device disclosed in, for example, Japanese Patent Laid-Open No. 63-316688, and FIG. 15 is a timing diagram for explaining the operation thereof. In FIG. 14, 50 is a DC power supply, 51 is a switching circuit composed of transistors Q1 to Q6, 52 is a control circuit for the switching circuit 51, a microcomputer having a memory 53 and a CPU 54, 55r, 55s and 55t are motor windings, H1, H2, and H3 are detection outputs of the Hall IC.
[0003]
The operation will be described with reference to FIG. FIG. 15B shows ON / OFF of the transistors Q1 to Q6. The addition angle data T is added to the conduction angle data T120 according to the motor speed, and the motor is driven at the conduction angle of T120 + T. To do.
[0004]
Japanese Patent Application Laid-Open No. 3-284188 discloses a technique similar to that of the conventional brushless DC motor driving apparatus (not shown). Japanese Patent Application Laid-Open No. 3-284188 is intended to arbitrarily energize from 120 degrees to 180 degrees.
[0005]
FIG. 16 is an operation timing chart of another conventional brushless DC motor driving circuit disclosed in Japanese Patent Laid-Open No. 10-66375. This shows a technology that has a timing circuit that detects a timing from 120 degrees to 180 degrees, and gradually reduces the on-duty at the end of energization to reduce motor noise.
[0006]
[Problems to be solved by the invention]
The technique disclosed in Japanese Patent Laid-Open No. 63-316688 expands the conduction angle by adding the addition angle to the conduction angle of 120 degrees in accordance with the rotational speed of the motor. As a result, the motor noise can be reduced by a certain amount. However, as long as the motor has a mechanical resonance, the noise reduction effect cannot be obtained when it matches the resonance frequency.
[0007]
Also, the technique disclosed in Japanese Patent Laid-Open No. 3-284188 is similar to the above, and the motor noise can be reduced by a certain amount. However, since the motor has mechanical resonance, it matches the resonance frequency. In addition, noise reduction effects cannot be obtained.
[0008]
Furthermore, the techniques disclosed in Japanese Patent Laid-Open Nos. 63-316688 and 3-284188 reduce the noise by increasing the energization angle. Therefore, there is a possibility that the motor operates at a rotational speed different from the rotational speed to be reduced.
[0009]
Furthermore, if the increased energization angle is controlled to be reduced by the rotation speed increased by the expansion, the rotation speed becomes unstable, and unstable rotation speed fluctuation makes a roaring sound and a new noise is generated. It is possible to do.
[0010]
Further, the technique disclosed in Japanese Patent Laid-Open No. 10-66375 is intended to reduce the motor noise by increasing the conduction angle from 120 degrees and further gradually decreasing the on-duty at the end of energization. If this technique is used, it has an effect of further reducing noise than the above, but when the DC motor is used as a fan motor only at the end of energization, the absolute amount of the suppression level is high, so that the noise level is insufficient.
[0011]
The present invention has been made to solve the above-described problems. Even when a DC brushless motor is used as a fan motor, the noise from the motor is greatly reduced to a noise level that does not cause a problem in practice. An object is to obtain a motor drive device that can be reduced to a minimum.
[0012]
[Means for Solving the Problems]
A motor drive device according to the present invention is a motor drive device that drives a motor at a constant rotational speed by PWM control by sequentially switching stator coils energized by an inverter based on the rotational position of a rotor of a DC brushless motor. There is provided an inverter control means for performing PWM control so that the energization width for energizing the stator coil is changed with respect to a predetermined reference width, and the fluctuation of the rotation speed of the motor accompanying the change in the energization width is suppressed to achieve a desired rotation speed. It is characterized by that.
[0013]
Further, the inverter control means changes the energization phase for energizing the stator coil with respect to a predetermined reference phase.
[0014]
The predetermined reference width is set according to the absolute level of motor noise.
[0015]
Further, the predetermined reference width is set to 120 degrees, and the energization width is increased.
[0016]
Further, the predetermined reference width is 120 degrees, and when the motor rotation speed is high, the energization width is reduced.
[0017]
Further, the predetermined reference width is set to 135 degrees or 150 degrees, and the energization width is enlarged or reduced.
[0018]
Also, when the energizing width to the stator coil is expanded from the predetermined reference width by the inverter control means, the PWM on ratio during the expanding period is higher than the PWM on ratio during the non-expanding period. Is controlled to be smaller.
[0019]
Further, when the energization width to the stator coil is expanded from the predetermined reference width by the inverter control means, the rate at which the PWM is turned on during the expansion period is gradually large at the rising time and gradually at the falling time. It is characterized in that the control is performed so that the ratio of turning on the PWM during the period not in the expansion period becomes the upper limit.
[0020]
Further, the ratio of turning on the PWM during the expanding period changes to a trapezoidal shape.
[0021]
Further, the ratio of turning on the PWM during the expanding period changes in a staircase pattern.
[0022]
Further, the inverter control means is characterized in that the energization width to the stator coil is changed at an asymmetrical ratio with respect to a predetermined reference width.
[0023]
The inverter control means controls the energization phase so that the motor is driven efficiently.
[0024]
Further, the inverter control means outputs a mute pulse for motor noise suppression during a period when the inverter control means is changing from a predetermined reference width.
[0025]
In addition, the inverter control means outputs a mute pulse for motor noise suppression to either the upper or lower switch element group during a period when it changes from a predetermined reference width, and to the other switch element group Is characterized by gradually changing the ON ratio of PWM.
[0026]
A motor drive device according to the present invention is a motor drive device that drives a motor at a constant rotational speed by PWM control by sequentially switching stator coils energized by an inverter based on the rotational position of a rotor of a DC brushless motor. When the rotational speed matches the mechanical resonance frequency of the motor, the energization width for energizing the stator coil of the motor is changed with respect to a predetermined reference width, and the energization phase for energizing the stator coil of the motor is changed to a predetermined reference Inverter control means for changing the phase with respect to the phase and performing PWM control so as to obtain a desired rotational speed is provided.
[0027]
In addition, the inverter control means advances the energization phase to the stator coil from the predetermined reference phase when the motor rotation speed matches the mechanical resonance frequency of the motor, and when it does not match, the predetermined reference phase or the predetermined reference Control is made so that the phase is delayed from the phase.
[0028]
The inverter control means controls the motor to a desired number of rotations by enlarging the energization width to the stator coil beyond a predetermined reference energization width when the rotation speed of the motor matches the mechanical resonance frequency of the motor. It is characterized by that.
[0029]
The mechanical resonance frequency of the motor is not limited to a motor composed of a motor stator, rotor, etc., but also to a load having a moment of inertia connected via a motor fixing support member and a motor shaft. The mechanical resonance frequency is determined by the synthesis of any natural frequency that contacts the transmission path through which the generated force is transmitted.
[0030]
Further, when the inverter control means has a motor pole pair number P, a motor rotational speed f [Hz], and a mechanical resonance frequency N [Hz], N = 2n · P · f (n = 1, 2,... Integer) In this case, it is determined that the rotational speed of the motor matches the mechanical resonance frequency of the motor.
[0031]
The blower according to the present invention is characterized in that the motor drive device according to any one of claims 1 to 19 is used as a drive device for a fan motor.
[0032]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings.
Embodiment 1 FIG.
FIGS. 1 to 11 are diagrams showing the first embodiment, FIG. 1 is a circuit block diagram showing the configuration of a motor drive device, FIG. 2 is an operation waveform diagram, FIGS. 3 and 4 are motor schematic diagrams, and FIG. FIG. 6 is a schematic diagram of a motor, FIG. 7 is a waveform diagram showing a phase angle difference, and FIGS. 8 to 11 are PWM image waveform diagrams.
In FIG. 1, 1 is an inverter having switch elements 1a to 1f, 2 is a capacitor, 3 is a motor that is a DC brushless motor, 4 is a hall sensor that detects the magnetic pole position of the rotor of the motor 3, and 5 is an inverter 1 It is a microcomputer that controls.
[0033]
Next, the operation will be described. The inverter 1 shown in FIG. 1 controls the phase of the stator in order to drive the motor 3. As shown in FIG. 2, only two of the six switch elements 1 a to 1 f constituting the inverter 1 are turned on. In FIG. 2, Hi is on, Lo is off, and the upper numerical value indicates the electrical angle at the rotor position of the motor 3.
[0034]
As shown in FIG. 2, the energization method for driving the motor 3 by controlling the inverter 1 is generally called 120-degree rectangular wave energization, and is a widely known technique. In this 120-degree energization method, the phase to be energized is switched every 120 degrees, so that torque ripple occurs in the motor 3 and electromagnetic noise is generated from the motor 3.
[0035]
When the motor 3 is used as a fan motor for a blower, this electromagnetic noise becomes a very disturbing sound. The present invention is a technique for suppressing this electromagnetic noise.
[0036]
As shown in FIG. 3, for example, when the position angle of the rotor is 0 to 30 degrees, currents flow from the W phase to the V phase because 1e and 1d are on. In the case of 30 to 60 degrees, since 1a and 1d are on, a current flows from the U phase to the V phase as shown in FIG.
[0037]
As described above, in the 120-degree energization method, current flows in two of the three phases, and no current flows in the remaining one phase. The motor 3 generates torque when a current flows. However, when the current is cut in this way, torque is not generated during this period. Therefore, a ripple is generated in the torque, and noise is generated from the generated torque ripple.
[0038]
Thus, by enlarging the energization width to be energized from 120 degrees, reducing the period during which no phase current flows and reducing the torque ripple means that the energization width is expanded. A shaded portion shown in FIG. 5 is a period of energization width to be expanded. As can be seen from FIG. 5, the number of switch elements that are turned on is increased from two to three during the expansion period, and during the expansion period of the energization width from 0 degrees to 60 degrees, the U phase and Current flows from the W phase toward the V phase.
[0039]
Hu, Hv, and Hw shown in FIG. 5 are the outputs of the hall sensor 4, but the relationship between the output of the hall sensor 4 and the energization angle is the positional relationship of the peak phase when the energization width is not enlarged. It is desirable not to change. The peak of the energization angle in FIG. 5 is the positions of 90 degrees and 270 degrees in the case of the U phase.
[0040]
Further, FIG. 7 shows a phase relationship diagram when the energization width is 120 degrees. 1a-fw indicates a leading phase with respect to 1a in FIG. 2, and 1a-de indicates a lagging phase. In the case of 120-degree energization, there is no change even if the leading phase and the lagging phase are set by the peak phase angle as shown in FIG. However, when the phase relationship is set by the edge, when the energization width is changed, the energization phase cannot be controlled to be constant unless the energization width is changed according to the changed energization width. If the control is based on the phase relationship of the peak angle, the energization phase angle can be controlled regardless of the change in the energization width, and this can be realized without changing the control.
[0041]
Here, regarding the relationship between the lead phase and the delay phase, the efficiency of the normal motor 3 is higher when the control is performed with the lead phase. However, when the energization width is 120 degrees, the way of cutting off the current is steep, the torque ripple generated in that case is large, and the noise tends to increase. In the case of the lag phase, the current increases due to the inductance component of the motor 3, and the current is gradually cut, so that the noise tends to be reduced.
[0042]
However, since it is better to operate with high efficiency, it is necessary to determine the phase to be energized while comparing efficiency and noise. In addition, since the energization width reduces torque ripple, more efficient operation is possible when the energization phase is varied depending on the energization width.
For example, when 120-degree energization is performed, the U-phase is energized in a 120-degree section from a 30-degree phase to 150 degrees. The angle of 30 degrees to 150 degrees is determined by the position of the rotor of the motor, and is actually an angle calculated from the output of the hall sensor 4. Here, the control of the lead phase angle means that, for example, if the lead angle is 10 degrees with 120 degree energization, the U phase is energized during the position angle of the rotor from 20 degrees to 140 degrees. 10 degrees advance at is energized from 5 degrees to 155 degrees. When the energization width is expanded, the energization phase is not set to the same 10 degrees, but is set to another value, for example, 15 degrees advance, and the energization phase angle is also changed with the change of the energization width.
[0043]
Thus, when the energization width is expanded while maintaining the positional relationship of the phase difference, the rotation speed of the motor 3 increases if the PWM is constant. Since the speed increases as the energization width increases, the control is performed by the inverter control means of the microcomputer 5 so that the PWM is decreased and the rotational speed is set to a predetermined speed.
[0044]
In this case, since there is a risk of hunting due to interference between control of the rotational speed and the energization width, it is necessary to perform speed control by PWM so as to keep the rotational speed constant as in the present invention.
[0045]
In FIG. 5, 120-degree energization is described as the reference energization width, but the reference energization width is not limited to 120 degrees, and there is no problem with the 135-degree reference energization width. The reference energization width is set according to the absolute level of noise of the motor 3, and the energization width may be reduced by setting the reference to 135 degrees.
[0046]
When the rotational speed is high, the current flowing to the motor 3 increases, and the torque ripple may be suppressed even if the energization width is not wide due to the inductance component of the motor 3. In this case, it may be reduced. Moreover, since the operation | movement in the inverter 1 is reduced by reducing, it also has the advantage that the heat_generation | fever of the inverter 1 is suppressed.
[0047]
A method for enlarging the energization width will be described with reference to FIG. As a matter of course, PWM control is performed both during and outside the expansion period. The on-duty, which is the on ratio of the PWM, may be the same value, but the meaning of expansion is that the torque ripple is reduced, so that the time change rate (di / dt) of the current flowing through the motor 3 is more gradual. Torque ripple is small.
[0048]
FIG. 8 shows an image of the on-duty of the phase voltage PWM output. During the expansion period, the PWM is controlled so that the on-duty is gradually increased at the rise and gradually decreased at the fall.
As shown in FIG. 8, the PWM duty changes to a trapezoidal shape, thereby having a low noise effect more than energization width expansion.
[0049]
Further, gradually changing the PWM on-duty as described above requires very high-speed control, leading to an increase in cost. Furthermore, when the motor 3 rotates at a high speed, it does not have a trapezoidal shape unless PWM is performed at a high frequency. For this reason, the same effect as described above can be achieved by gradually changing the shape of a trapezoidal shape without gradually changing to a trapezoidal shape. Further, when the motor 3 is a motor having a large inductance component such as a fan motor, the same effect as that of the trapezoidal shape can be obtained even in the step shape.
[0050]
Next, in FIG. 5, the period of expansion is expanded symmetrically with respect to the case of not expanding. This is because the motor 3 can be operated more efficiently if the relationship between the phase in the energization phase of the stator of the motor 3 and the phase in the magnetic pole position of the rotor is kept the same. This is because the phase can be easily matched if the phase control is used.
[0051]
However, although it does not expand symmetrically in the front-rear direction and is related to the characteristics of the motor 3, it may be possible to reduce noise by making the expanded part asymmetrical in the front-rear direction as shown by the arrows in FIG. In this case, by controlling the phase relationship so that the motor 3 is driven efficiently, the efficiency is not deteriorated and further noise reduction can be realized.
[0052]
Furthermore, as shown in FIG. 10, a silencing pulse is output instead of outputting PWM during the expansion period. Thereby, the processing capability of the microcomputer can be reduced. The mute pulse is output so that a sound that cancels the noise component generated from the motor 3 is generated. In FIG. 10, it is output only in the latter half of the expansion period, but it goes without saying that it has the same or better effect even if it is output before and after. It goes without saying that there is no problem with the first half alone.
[0053]
FIG. 11 is a combination of the silencing pulse in FIG. 10 and the trapezoidal PWM in FIG. In the case of rectangular wave driving, if either the upper arm (1a, 1c, 1e in FIG. 1) or the lower arm (1b, 1d, 1f in FIG. 1) is PWMed, all the upper and lower arms are PWMed. It is generally known that
[0054]
FIG. 11 considers the technique of PWM on only one side. In the case of PWM on only one side, the PWM can be controlled in a trapezoidal shape during the expansion period on the arm side on which PWM is superimposed, but the arm that is not superimposed Since there is one element that is PWMed on the side, PWM control during the expansion period cannot be performed. Therefore, the rotation speed is controlled so that low noise driving is performed by outputting a trapezoidal shape on the arm side where PWM is superimposed and outputting a mute pulse on the arm side where PWM is not superimposed.
[0055]
In this case, since the voltage output by the upper and lower arms changes, if the speed is not controlled, hunting of the rotational speed occurs, and noise with a frequency different from the rectangular wave may occur. In the present invention, the current-carrying width is increased while controlling the rotation speed to a desired value to reduce noise, so that the above problem does not occur and noise reduction can be realized.
[0056]
Embodiment 2. FIG.
12 and 13 are diagrams showing the second embodiment, FIG. 12 is a circuit block diagram showing the configuration of the motor drive device, and FIG. 13 is a perspective view of the indoor unit of the air conditioner.
In FIG. 12, reference numeral 6 denotes a position detection unit that detects a counter electromotive voltage generated by the rotor of the motor, and the other components are the same as those in FIG. In FIG. 1, the position detection by the Hall sensor 4 and the position detection by the counter electromotive voltage in FIG. 12 are used as the rotor position detection method. However, these are not essential problems with the present invention, and neither of them is a problem. It will not be. 1 is equivalent to the position detection by the back electromotive force, and FIG. 12 is equivalent to the position detection by the Hall sensor 4.
[0057]
In the first embodiment, the energization width and the energization phase are controlled according to the rotation speed of the motor 3, but in this embodiment, the energization width and the energization phase are determined by the motor 3 and the mechanical resonance frequency connected thereto. Is intended to be variable.
[0058]
As shown in FIG. 13, the motor 3 is attached to the indoor unit 10 of the air conditioner, and although not shown, a support member that fixes the motor 3 fixes the motor 3. Since the motor 3 is a fan motor, it is connected to the fan 11 via the motor shaft 12. As the fan 11 rotates, the air is blown from the air outlet 13 and the air direction is adjusted by the damper 14.
[0059]
As described above, the fan motor has not only the natural frequencies of the stator and the rotor of the motor 3 itself, but also the natural frequencies of each connected member, the torsional resonance between the motor shaft 12 and the fan 11, the wind The mechanical resonance frequency is determined by the combination of the road and the resonance caused by the air volume.
[0060]
Here, if the mechanical resonance frequency and the frequency of the motor 3 that is the excitation source coincide with each other, a large vibration is generated even if the excitation force is weak, resulting in noise, and no matter how the excitation force is reduced by electrical control, the noise It is difficult to reduce the level.
[0061]
Since these mechanical resonance frequencies are originally made clear for each product, the rotational speed of the motor 3 in that region is jumped, and control is performed so that the rotational frequency of the motor 3 does not coincide with the mechanical resonance frequency. This is a generally known method.
[0062]
However, in pursuit of energy saving, skipping the mechanical resonance frequency is contrary to energy saving. If it does not coincide with the mechanical resonance, the motor 3 can be operated at a low frequency and the energy consumption can be reduced, but the motor 3 is operated at a high frequency by skipping the rotation speed due to noise, and the energy consumption is reduced. It is because it will increase.
[0063]
The present invention does not cause a frequency jump with the mechanical resonance frequency, but changes the generated vibration frequency level of the motor that is the excitation source to change the vibration peak frequency to a frequency that does not match the mechanical resonance frequency. The object is to reduce the noise of the motor 3 without making it variable and frequency jumping.
[0064]
As shown in the waveform diagram of FIG. 7, the phase angle is controlled. If the phase angle coincides with the resonance frequency, the energization width is controlled to be enlarged as much as possible in the lead phase. This is because it is possible to drive at an operating point with higher efficiency when controlled by the lead phase, and therefore the phase current flowing through the motor 3 can be small. If it does not match the resonance, even if the current is somewhat large, it is less noise to reduce the influence of torque ripple.However, if it matches the resonance point, noise is generated even with a slight torque ripple, so the current is reduced. Controlling with the lead phase results in lower noise.
[0065]
Furthermore, the fifth harmonic component of the phase current can be suppressed by enlarging the energization width with the advance phase angle. Since the fifth-order component of the phase current has a significant effect on noise generation due to current distortion, it is matched with the mechanical resonance frequency by controlling the energization width at an advanced phase angle that can suppress the fifth-order component of the phase current. In the case of the rotational speed, the noise can be reduced.
[0066]
However, in the case of a rotational speed that matches the mechanical resonance frequency, it is not effective to simply increase the energization width or to advance the phase angle to the phase angle. By controlling both at the same time, the effect of reducing noise to a frequency that matches the mechanical resonance frequency can be exhibited.
[0067]
Furthermore, the condition that the mechanical resonance frequency and the rotation frequency coincide with each other will be described. Assuming that the rotation frequency of the motor 3 serving as the excitation source is f [Hz], the motor 3 generates vibration that peaks at an electrical frequency that is an integral multiple of f. As described above, since the motor 3 is a vibration source, the generated vibration is transmitted to the external structure and converted into noise. At that time, when the natural resonance frequency and vibration coincide with the structure itself, the noise becomes larger.
[0068]
Therefore, the fact that the rotation frequency f of the motor 3 matches the resonance frequency means that a frequency that is an integer multiple of f matches the resonance frequency, but not all the integer multiples of f become noise. Since the present invention is a rectangular wave drive, the distortion of the current flowing through the motor 3 tends to be a vibration.
[0069]
The current distortion component is usually composed of odd-order components, and in particular, the fifth-order and seventh-order components are mainly used. Vibration is generated by combining the odd order of the current and the fundamental order component of the magnetic flux of the rotor. Therefore, the vibration of the even-numbered component that is a composite of the odd-order current and the first-order magnetic flux is large. Since the above is the electrical frequency, when the number of pole pairs P of the motor 3 is multiplied and the frequency of 2n · P · f coincides with the mechanical resonance frequency N, the above control is performed.
[0070]
By using the motor drive device of the motor 3, the inverter 1, and the microcomputer 5 configured as described above as a motor drive device for a blower, an inexpensive and highly efficient motor drive device can also be used for a blower application that requires low noise. Can be provided. In particular, the present invention employs a DC brushless motor that has been avoided from the noise aspect in the field of fan motors that are indispensable for air conditioning, such as air conditioner indoor units, outdoor units, ventilation fans, air purifiers, and dehumidifiers. It makes it possible.
[0071]
【The invention's effect】
The motor drive device according to the present invention changes the energization width for energizing the stator coil of the motor with respect to a predetermined reference width, suppresses fluctuations in the rotational speed of the motor due to the change in the energization width, and achieves a desired rotational speed Thus, by providing the inverter control means for PWM control, it is possible to reduce the torque ripple and reduce the noise while suppressing the fluctuation of the rotation speed of the motor.
[0072]
Further, the inverter control means can arbitrarily set the motor efficiency and noise by changing the energization phase for energizing the stator coil with respect to the predetermined reference phase.
[0073]
In addition, the predetermined reference width is set according to the absolute level of the noise of the motor, so that the absolute level of the noise can be made a certain level or less.
[0074]
In addition, by setting the predetermined reference width to 120 degrees and enlarging the energization width, it is possible to reduce torque ripple and reduce noise.
[0075]
Also, when the predetermined reference width is 120 degrees and the motor rotation speed is high, the heat generation of the inverter can be reduced by reducing the energization width.
[0076]
Further, by setting the predetermined reference width to 135 degrees or 150 degrees and enlarging or reducing the energization width, it is possible to reduce torque ripple and reduce noise, or to reduce heat generation of the inverter.
[0077]
Also, when the energizing width to the stator coil is expanded from the predetermined reference width by the inverter control means, the PWM on ratio during the expanding period is higher than the PWM on ratio during the non-expanding period. By controlling so that the motor is also reduced, fluctuations in the rotational speed of the motor can be reduced.
[0078]
Further, when the energization width to the stator coil is expanded from the predetermined reference width by the inverter control means, the rate at which the PWM is turned on during the expansion period is gradually large at the rising time and gradually at the falling time. By reducing the torque ripple to a lower limit and controlling the PWM turn-on rate during periods not in the expansion period to be the upper limit, the noise can be reduced.
[0079]
Further, the ratio of turning on the PWM during the expanding period changes to a trapezoidal shape, so that the noise can be reduced more than the energization width expansion.
[0080]
In addition, the PWM turn-on ratio during the expanding period changes in a staircase shape, and thus the same effect as in the case of changing to a trapezoidal shape can be obtained. In particular, when the motor is a motor having a large inductance component, such as a fan motor, the effect similar to that of the trapezoidal shape is obtained even in a stepped shape.
[0081]
Further, the inverter control means has the same effect as the control of the energization phase by changing the energization width to the stator coil at a rate asymmetrical with respect to the predetermined reference width.
[0082]
In addition, the inverter control means controls the energization phase so that the motor is driven efficiently, thereby further reducing noise without deteriorating the efficiency.
[0083]
Further, the inverter control means can reduce the processing capacity of the microcomputer by outputting a mute pulse for motor noise suppression during a period when the inverter control means is changing from a predetermined reference width.
[0084]
In addition, the inverter control means outputs a mute pulse for motor noise suppression to either the upper or lower switch element group during a period when it changes from a predetermined reference width, and to the other switch element group Can gradually reduce the processing capability of the microcomputer by changing the PWM ON ratio.
[0085]
The motor drive device according to the present invention changes the energization width for energizing the stator coil of the motor with respect to a predetermined reference width when the rotational speed of the motor coincides with the mechanical resonance frequency of the motor, and the stator of the motor. By providing inverter control means for performing PWM control so that the energization phase for energizing the coil is changed with respect to a predetermined reference phase to achieve a desired rotational speed, noise can be reduced without skipping the resonance frequency.
[0086]
In addition, the inverter control means advances the energization phase to the stator coil from the predetermined reference phase when the motor rotation speed matches the mechanical resonance frequency of the motor, and when it does not match, the predetermined reference phase or the predetermined reference By controlling the phase behind the phase, the phase current can be reduced, the torque ripple can be reduced, and the noise can be reduced.
[0087]
The inverter control means controls the motor to a desired number of rotations by enlarging the energization width to the stator coil beyond a predetermined reference energization width when the rotation speed of the motor matches the mechanical resonance frequency of the motor. Thus, the fifth harmonic component of the phase current can be reduced.
[0088]
The mechanical resonance frequency of the motor is not limited to a motor composed of a motor stator, rotor, etc., but also to a load having a moment of inertia connected via a motor fixing support member and a motor shaft. The resonance of the motor peripheral member can be suppressed by the mechanical resonance frequency determined by the synthesis of any natural frequency that contacts the transmission path through which the generated force is transmitted.
[0089]
Further, when the inverter control means has a motor pole pair number P, a motor rotational speed f [Hz], and a mechanical resonance frequency N [Hz], N = 2n · P · f (n = 1, 2,... Integer) In this case, by determining that the rotational speed of the motor matches the mechanical resonance frequency of the motor, the processing frequency of the microcomputer can be reduced by specifying the resonance frequency.
[0090]
The blower according to the present invention provides a low-noise blower by using the motor drive device according to any one of claims 1 to 19 as a fan motor drive device.
[Brief description of the drawings]
FIG. 1 is a circuit block diagram illustrating a configuration of a motor drive device according to a first embodiment.
FIG. 2 is a diagram illustrating the first embodiment and is an operation waveform diagram;
FIG. 3 shows the first embodiment and is a schematic diagram of a motor.
FIG. 4 shows the first embodiment and is a schematic diagram of a motor.
FIG. 5 is a diagram illustrating the first embodiment and is an operation waveform diagram;
FIG. 6 shows the first embodiment and is a schematic diagram of a motor.
7 shows the first embodiment and is a waveform diagram showing a phase angle difference. FIG.
FIG. 8 is a diagram showing the first embodiment and is an image waveform diagram of PWM.
FIG. 9 is a diagram illustrating the first embodiment, and is a PWM image waveform diagram;
FIG. 10 is a diagram illustrating the first embodiment, and is a PWM image waveform diagram;
FIG. 11 is a diagram illustrating the first embodiment, and is a PWM image waveform diagram;
12 is a circuit block diagram showing a configuration of a motor drive device according to the second embodiment. FIG.
FIG. 13 is a diagram showing the second embodiment and is a perspective view of the indoor unit of the air conditioner.
FIG. 14 is a circuit configuration diagram of a conventional brushless DC motor driving apparatus.
FIG. 15 is an operation waveform diagram of a conventional brushless DC motor driving apparatus.
FIG. 16 is an operation timing chart of another conventional brushless DC motor drive circuit.
[Explanation of symbols]
1 Inverter, 2 capacitor, 3 motor, 4 Hall sensor, 5 microcomputer, 6 position detector.

Claims (9)

In a motor drive device that switches a stator coil energized by an inverter in order based on the rotational position of a rotor of a DC (Direct Current) brushless motor and drives the motor at a constant rotational speed by PWM (Pulse Width Modulation) control.
Inverter control for PWM control so that the energization width for energizing the stator coil of the motor is changed with respect to a predetermined reference width, and the fluctuation of the rotation speed of the motor accompanying the change of the energization width is suppressed to achieve a desired rotation speed. With means,
The inverter control means outputs a pulse for motor noise suppression during a period when the inverter control means changes from a predetermined reference width. In a motor drive device that switches a stator coil energized by an inverter in order based on the rotational position of a rotor of a DC (Direct Current) brushless motor and drives the motor at a constant rotational speed by PWM (Pulse Width Modulation) control.
Inverter control for PWM control so that the energization width for energizing the stator coil of the motor is changed with respect to a predetermined reference width, and the fluctuation of the rotation speed of the motor accompanying the change of the energization width is suppressed to achieve a desired rotation speed. With means,
The inverter control means outputs a pulse for motor noise suppression to either the upper or lower switch element group during a period of time changing from a predetermined reference width, and gradually to the other switch element group. A motor drive device characterized by changing the on ratio of PWM. 3. The motor driving apparatus according to claim 1, wherein the inverter control means changes the energization phase for energizing the stator coil with respect to a predetermined reference phase. In the motor drive device for switching the stator coil energized by the inverter in order based on the rotational position of the rotor of the DC brushless motor and driving the motor at a constant rotational speed by PWM control,
When the rotational speed of the motor matches the mechanical resonance frequency of the motor, the energization width for energizing the stator coil of the motor is changed with respect to a predetermined reference width, and the energization for energizing the stator coil of the motor A motor driving apparatus comprising: inverter control means for performing PWM control so that a phase is changed with respect to a predetermined reference phase to obtain a desired rotation speed. When the rotational speed of the motor coincides with the mechanical resonance frequency of the motor, the inverter control means advances the energization phase to the stator coil from the predetermined reference phase, and when not coincident, the predetermined reference phase or the predetermined 5. The motor driving device according to claim 4 , wherein the motor driving device is controlled so as to be delayed from the reference phase. When the rotational speed of the motor matches the mechanical resonance frequency of the motor, the inverter control means controls the motor to a desired rotational speed by enlarging the energization width to the stator coil beyond a predetermined reference energization width. The motor driving device according to claim 5, wherein The mechanical resonance frequency of the motor is not limited to a single motor composed of a stator, a rotor, etc. of the motor, but is also connected to a support member for fixing the motor, a load having a moment of inertia connected through the motor shaft, and the load. generating Te contacts the transmitted by the transmission path of force that is mechanical resonance frequency determined by the synthesis of any of the natural frequency of the motor driving device according to any one of claims 4 to 6, wherein. When the inverter control means has a pole pair number P of the motor, a motor rotation speed f [Hz], and a mechanical resonance frequency N [Hz],
N = 2n.P.f (n = 1, 2,... Integer)
Case, the motor driving apparatus according to claim 4, wherein the rotational speed of the motor and determines that matches the mechanical resonance frequency of the motor. The motor driving device according to any one of claims 1 to 8, blower characterized by using as the drive of the fan motor.

Images