JP6925497B2 - Vacuum cleaner - Google Patents

Description

The present invention relates to a vacuum cleaner equipped with a single-phase motor driven by a motor drive device.

Single-phase motors have the following advantages over three-phase motors with three phases.
(1) While it is necessary to use a three-phase inverter for a three-phase motor, a single-phase inverter having a simpler configuration than a three-phase inverter may be used for a single-phase motor.
(2) A three-phase inverter using a full-bridge inverter requires six switching elements, whereas a single-phase motor can be composed of four switching elements even if a full-bridge inverter is used.
(3) Due to the above-mentioned features (1) and (2), the device using the single-phase motor can be downsized as compared with the device using the three-phase motor.

Due to the above characteristics, in a cordless vacuum cleaner equipped with a battery, there are many application examples of a single-phase motor from the viewpoint of miniaturization.

The electric vacuum cleaner includes, as basic components, an electric blower for generating suction force, a suction port for sucking dust, and a dust collecting chamber for collecting the sucked dust. In addition to these, the vacuum cleaner of Patent Document 1 below is provided with an optical floor surface detection sensor that detects the type of floor surface to be cleaned. Examples of floor surface types include carpets, tatami mats, and flooring. The floor surface detection sensor of Patent Document 1 includes a wheel for detecting the floor surface, a holding frame for the wheel, two photo switches, and a light-shielding portion for shielding the optical axis of one of the two photo switches. It also has a light-shielding lever for shielding the optical axis of the other photo switch.

The vacuum cleaner of Patent Document 1 controls to automatically switch the operation mode of the vacuum cleaner according to the detection information of the floor surface. The floor surface detection information in Patent Document 1 is information on whether or not the floor surface is a carpet, the floor surface is a board floor or a tatami floor, or the suction port body is separated from the floor surface. be.

Japanese Unexamined Patent Publication No. 2-52620

Due to the diversification of lifestyles in recent years, the function of detecting the type of floor surface to be cleaned is recognized as an indispensable component. However, as shown in Patent Document 1, the method using the optical floor surface detection sensor uses a large number of parts and has a complicated structure. As a result, the conventional vacuum cleaner has a problem that the design and manufacturing cost increases, and the reliability decreases due to the increase in the number of parts. Therefore, it is desired to realize a function of detecting the floor surface type without using an optical floor surface detection sensor.

The present invention has been made in view of the above, and an object of the present invention is to obtain an electric vacuum cleaner capable of detecting a floor surface type without using an optical floor surface detection sensor.

In order to solve the above-mentioned problems and achieve the object, the vacuum cleaner according to the present invention includes a single-phase motor, a motor drive device for driving the single-phase motor, and a suction tool for sucking dust. The motor drive device determines the rotation speed of the single-phase motor based on the single-phase inverter that applies an AC voltage to the single-phase motor, the position sensor that outputs the position sensor signal indicating the rotor magnetic pole position of the single-phase motor, and the position sensor signal. It is provided with a calculation unit that calculates and calculates the opening ratio of the gap generated between the suction port of the suction tool and the cleaning surface based on the calculated change in the rotation speed. When the aperture ratio is within the first range, the amplitude value of the AC voltage is set to the first value, and when the aperture ratio is within the second range, the amplitude value of the AC voltage is different from the first value. Is the value of.

According to the vacuum cleaner according to the present invention, there is an effect that the floor surface type can be detected without using an optical floor surface detection sensor.

Basic configuration diagram of a vacuum cleaner including a motor drive device according to an embodiment A block diagram showing a configuration of a motor drive system including a motor drive device according to an embodiment. Circuit configuration diagram of the single-phase inverter shown in FIG. A block diagram showing a carrier comparison unit realized by the processor shown in FIG. 2 and a carrier generation unit shown in FIG. A block diagram showing in detail the configurations of the carrier comparison unit and the carrier generation unit shown in FIG. A time chart showing waveform examples of the positive voltage command, the negative voltage command, the pulse width modulation (PWM) signal, and the inverter output voltage shown in FIG. The figure which shows the change of the inverter output voltage according to the modulation factor A block diagram showing a functional configuration for calculating the advance phase input to the carrier comparison unit shown in FIGS. 4 and 5. The figure which shows an example of the calculation method of the advance angle phase in embodiment The position sensor signal output from the position sensor shown in FIG. 2, the rotor mechanical angle which is the angle from the reference position of the rotor shown in FIG. 2, and the reference phase which is the phase obtained by converting the rotor mechanical angle into the electric angle. The figure which shows the relationship with the voltage command shown in FIG. The figure which shows the time change of the voltage amplitude command in embodiment The figure which is provided for the explanation of the definition of the aperture ratio in an embodiment. The figure which provides the explanation of the control method of the voltage command in an embodiment. The figure which provides the explanation of the calculation method of the aperture ratio in an embodiment. The figure provided for the explanation of the advance angle phase control method in an Embodiment. Schematic cross-sectional view showing a schematic structure of a MOSFET (Metal-Oxide-Semiconductor Field-Effective Transistor) that can be used as a switching element shown in FIG. The first figure which shows the path of the motor current by the polarity of the inverter output voltage output from the single-phase inverter shown in FIG. The second figure which shows the path of the motor current by the polarity of the inverter output voltage output from the single-phase inverter shown in FIG. FIG. 3 shows a path of a motor current depending on the polarity of the inverter output voltage output from the single-phase inverter shown in FIG. The figure for demonstrating the modulation control in the motor drive device which concerns on embodiment.

Hereinafter, the vacuum cleaner according to the embodiment of the present invention will be described in detail with reference to the drawings. The present invention is not limited to the following embodiments.

Embodiment.
FIG. 1 is a basic configuration diagram of a vacuum cleaner according to an embodiment. Further, FIG. 2 is a block diagram showing a functional configuration when the vacuum cleaner according to the embodiment is viewed as a motor drive system. As shown in FIG. 1, the vacuum cleaner 1 includes a suction port body 63, an extension pipe 62, and a vacuum cleaner main body 6. The suction port 63 is for sucking dust and dirt (hereinafter, simply abbreviated as “dust”) on the surface to be cleaned such as the floor surface together with air. A suction port 69 that opens downward is formed on the lower surface of the suction port body 63. The suction port body 63 sucks dust together with air from the suction port 69. The extension pipe 62 is connected between the suction port body 63 and the vacuum cleaner main body 6, and is composed of a straight member having a hollow tubular shape.

The vacuum cleaner main body 6 is for separating dust from the air taken in and discharging the air from which the dust has been removed. The vacuum cleaner main body 6 houses a motor driving device 2, an electric blower 64, and a dust collecting chamber 65. The motor drive device 2 is a device for driving the electric blower 64, and the electric blower 64 has a single-phase motor (not shown) and blades directly connected to the single-phase motor to generate a high-speed air flow. Air containing dust is sucked from the suction port 69 by the high-speed airflow generated by driving the electric blower 64. The dust collecting chamber 65 is for separating dust from air containing dust and temporarily storing the separated dust.

Further, the vacuum cleaner main body 6 is provided with an operation unit 66 and a battery 67. The operation unit 66 is intended to be held and operated by the user of the vacuum cleaner 1, and the operation unit 66 is provided with an operation switch (not shown) for the user to operate the operation of the vacuum cleaner 1. ing. The battery 67 is a DC power source that supplies DC power to the motor drive device 2.

As shown in FIG. 2, the motor driving device 2 is connected to a battery 67 which is a power source and a single-phase motor 12 provided in the electric blower 64 shown in FIG. A voltage sensor 20 is provided between the battery 67 and the motor drive device 2. A current sensor 22 is provided between the motor drive device 2 and the single-phase motor 12. An example of the single-phase motor 12 is a brushless motor. The motor drive device 2 supplies AC power to the single-phase motor 12 to drive the single-phase motor 12. The voltage sensor 20 is a sensor that detects the _{DC voltage Vdc} applied from the battery 67 to the motor drive device 2. The position sensor 21 is a sensor that detects the rotor magnetic pole position, which is the magnetic pole position of the rotor 12a built in the single-phase motor 12. The current sensor 22 is a sensor that detects the motor current, which is the current flowing through the single-phase motor 12.

The vacuum cleaner 1 may be configured to have a plurality of operation modes. One of the plurality of operation modes is the "normal operation mode", and the other one of the plurality of operation modes is the "save operation mode". The "normal operation mode" is an operation mode in which the motor is operated at the motor rotation speed during normal operation. The "save operation mode" is an operation mode in which power consumption is suppressed by setting the motor rotation speed lower than the motor rotation speed during normal operation.

Switching between the "normal operation mode" and the "save operation mode" may be performed by a changeover switch (not shown) or by controlling the motor drive device 2 according to the remaining battery level.

In the present embodiment, the voltage sensor 20 _{detects the DC voltage V dc} , but the detection target is not limited to the _{DC voltage V dc.} The detection target may be the inverter output voltage, which is the output voltage of the motor drive device 2. The "inverter output voltage" is synonymous with the "motor applied voltage" described later.

Further, the position sensor 21 may be any one as long as it can detect the position of the rotor magnetic pole. It may be a position detection element such as a Hall IC or a Hall element, or a circuit that detects the rotor magnetic pole position from a motor-induced voltage. The motor-induced voltage is a voltage induced in a winding (not shown) in the stator 12b of the single-phase motor 12.

Next, the internal configuration of the motor drive device 2 will be described. As shown in FIG. 2, the motor drive device 2 includes a single-phase inverter 11, a control unit 25, an analog-digital converter 30, and a drive signal generation unit 32.

The single-phase inverter 11 is connected to the single-phase motor 12 and applies an AC voltage to the single-phase motor 12. The analog-digital converter 30 converts analog data, which is _{a DC voltage Vdc detected by the voltage sensor 20, into digital data.} Further, the analog-digital converter 30 converts the analog data of the motor current detected by the current sensor 22 into digital data.

The control unit 25 generates pulse width modulation (PWM) signals Q1, Q2, Q3, and Q4, which are signals for controlling the motor current to a sine wave. The drive signal generation unit 32 generates a drive signal for driving the switching element in the single-phase inverter 11 based on the PWM signals Q1, Q2, Q3, and Q4 output from the control unit 25.

The control unit 25 generates PWM signals Q1, Q2, Q3, and Q4 based on the DC voltage converted by the analog-digital converter 30 and the position sensor signal which is the rotation position detection signal output from the position sensor 21. do. The position sensor signal is a binary digital signal that changes according to the direction of the magnetic flux generated by the rotor 12a.

Next, the internal configuration of the control unit 25 will be described. The control unit 25 includes a processor 31, a carrier generation unit 33, and a memory 34.

The processor 31 is a processing unit that performs various operations related to PWM control and advance angle control. The functions of the carrier comparison unit 38 and the advance angle phase calculation unit 44, which will be described later, are realized by the processor 31. The processor 31 may be referred to as a CPU (Central Processing Unit), a microprocessor, a microcomputer, or a DSP (Digital Signal Processor).

A program read by the processor 31 is stored in the memory 34. The memory 34 is used as a work area when the processor 31 performs arithmetic processing. The memory 34 is generally a non-volatile or volatile semiconductor memory such as a RAM (Random Access Memory), a flash memory, an EPROM (Erasable Programmable ROM), or an EEPROM (registered trademark) (Electrically EPROM). Details of the configuration of the carrier generation unit 33 will be described later.

The drive signal generation unit 32 converts the PWM signals Q1, Q2, Q3, and Q4 output from the processor 31 into drive signals for driving the single-phase inverter 11 and outputs the PWM signals to the single-phase inverter 11.

When the single-phase motor 12 is a brushless motor, a plurality of permanent magnets (not shown) are arranged in the circumferential direction on the rotor 12a of the single-phase motor 12. These plurality of permanent magnets are arranged so that the magnetizing directions are alternately reversed in the circumferential direction, and form a plurality of magnetic poles of the rotor 12a. A winding (not shown) is wound around the stator 12b of the single-phase motor 12 and arranged. Hereinafter, the winding of the stator 12b will be referred to as a "stator winding". The alternating current flowing through the stator winding corresponds to the "motor current" described above. In the present embodiment, it is assumed that the number of magnetic poles of the rotor 12a is 4 poles, but the number of magnetic poles of the rotor 12a may be other than 4 poles.

FIG. 3 is a circuit configuration diagram of the single-phase inverter shown in FIG. The single-phase inverter 11 has a plurality of bridge-connected switching elements 51, 52, 53, 54. Each of the two switching elements 51 and 53 located on the high potential side is referred to as an upper arm switching element. Each of the two switching elements 52 and 54 located on the low potential side is referred to as a lower arm switching element. The connection end 11a between the switching element 51 and the switching element 52 and the connection end 11b between the switching element 53 and the switching element 54 form an AC end in the bridge circuit. A single-phase motor 12 is connected to the connection ends 11a and 11b.

For each of the plurality of switching elements 51, 52, 53, 54, a MOSFET which is a metal oxide film semiconductor field effect transistor is used. MOSFET is an example of FET (Field-Effective Transistor).

The switching element 51 is formed with a body diode 51a connected in parallel between the drain and the source of the switching element 51. The switching element 52 is formed with a body diode 52a connected in parallel between the drain and the source of the switching element 52. The switching element 53 is formed with a body diode 53a connected in parallel between the drain and the source of the switching element 53. The switching element 54 is formed with a body diode 54a connected in parallel between the drain and the source of the switching element 54. Each of the plurality of body diodes 51a, 52a, 53a, 54a is a parasitic diode formed inside the MOSFET and is used as a freewheeling diode.

At least one of the plurality of switching elements 51, 52, 53, 54 is not limited to a MOSFET formed of a silicon-based material, but is formed of a wide bandgap semiconductor such as silicon carbide, gallium nitride-based material, or diamond. It may be a MOSFET.

In general, wide bandgap semiconductors have higher withstand voltage and heat resistance than silicon semiconductors. Therefore, by using a wide bandgap semiconductor for at least one of the plurality of switching elements 51, 52, 53, 54, the withstand voltage resistance and allowable current density of the switching element are increased, and the semiconductor module incorporating the switching element is incorporated. Can be miniaturized. Further, since the wide bandgap semiconductor has high heat resistance, it is possible to reduce the size of the heat radiating portion for radiating the heat generated in the semiconductor module. Further, the wide bandgap semiconductor can simplify the heat dissipation structure that dissipates the heat generated in the semiconductor module.

FIG. 4 is a block diagram showing a carrier comparison unit realized by the processor shown in FIG. 2 and a carrier generation unit shown in FIG. FIG. 5 is a block diagram showing in detail the configurations of the carrier comparison unit and the carrier generation unit shown in FIG. As described above, the function of generating the PWM signals Q1, Q2, Q3, and Q4 can be realized by the carrier generation unit 33 and the carrier comparison unit 38 shown in FIG.

In FIG. 4, the carrier comparison unit 38 is input with the advance angle controlled advance phase θ _{v used when generating the voltage command V m} described later and the reference phase θ _e. The reference phase θ _e is a phase obtained by converting the _{rotor mechanical angle θ m} , which is an angle from the reference position of the rotor 12a, into an electric angle. Here, the "advance angle phase" represents the "advance angle" which is the "advance angle" of the voltage command in terms of phase. Further, the "advance angle" referred to here is a phase difference between the motor applied voltage applied to the stator winding by the single-phase inverter 11 and the motor-induced voltage induced in the stator winding. When the voltage applied to the motor is ahead of the voltage induced by the motor, the "advance angle" takes a positive value. The motor-induced voltage is a signal synchronized with the output signal of the position sensor 21. Therefore, the "advance angle" is also the phase difference between the position sensor signal and the motor applied voltage. Information on the motor applied voltage is required for the calculation of the advance phase θ _v , but the motor current may be used instead of the motor applied voltage. That is, the phase difference between the position sensor signal and the motor current may be defined as the "advance angle".

Further, the carrier comparison unit 38 contains the advance angle phase θ _v , the reference phase θ _e , the carrier generated by the carrier generation unit 33, the DC voltage V _dc, and the amplitude value of the voltage command V _m. The voltage amplitude command V * is input. The carrier comparison unit 38 generates PWM signals Q1, Q2, Q3, and Q4 based on the carrier, the advance phase θ _v , the reference phase θ _e , the DC voltage V _{dc, and the voltage amplitude command V *.}

As shown in FIG. 5, a carrier frequency f _C [Hz], which is a carrier frequency, is set in the carrier generation unit 33. At the tip of the arrow of the carrier frequency f _C , as an example of the carrier waveform, the waveform of the triangular wave carrier moving up and down between “0” and “1” is shown. The PWM control of the single-phase inverter 11 includes synchronous PWM control and asynchronous PWM control, but in the case of asynchronous PWM control, it is not necessary to control the carriers to be synchronized with _{the advance phase θ v.}

As shown in FIG. 5, the carrier comparison unit 38 includes an absolute value calculation unit 38a, a division unit 38b, a multiplication unit 38c, a multiplication unit 38d, an addition unit 38e, a multiplication unit 38f, a comparison unit 38g, a comparison unit 38h, and an output inversion unit. It has 38i and an output inversion unit 38j.

The absolute value calculation unit 38a calculates the absolute value | V * | of the voltage amplitude command V *. In the division unit 38b, the absolute value | V * | is divided by _{the DC voltage V dc detected by the voltage sensor 20.} The battery voltage, which is the output voltage of the battery 67, fluctuates as the current continues to flow, but by _{dividing the absolute value | V * | by the DC voltage V dc} , the motor applied voltage does not decrease due to the decrease in the battery voltage. In addition, the modulation factor can be increased.

In the multiplication unit 38c, a sine value of “θ _e + θ _v ” obtained by adding the advance phase θ _{v to the reference phase θ e is calculated.} The calculated _{sine value of "θ e} + θ _v " is multiplied by the output of the division unit 38b. The multiplier unit 38d, 1/2 is multiplied by the voltage command _{V m} is the output of the multiplication unit 38c. In the addition unit 38e, 1/2 is added to the output of the multiplication unit 38d. In the multiplication unit 38f, "-1" is multiplied by the output of the addition unit 38e. The output of the addition unit 38e is input to the comparison unit 38g as _{a voltage command V m1} on the positive side for driving the two switching elements 51, 53 of the upper arm among the plurality of switching elements 51, 52, 53, 54. , the output of the multiplication unit 38f is input to the comparison unit 38h as a voltage command _{V m2} of the negative side for driving the two switching elements 52, 54 of the lower arm.

In the comparison unit 38 g, the voltage command V _{m1 on the} positive side and the amplitude of the carrier are compared. The output of the comparison unit 38g is the PWM signal Q1 to the switching element 51, and the output of the output inversion unit 38i that inverts the output of the comparison unit 38g is the PWM signal Q2 to the switching element 52. Similarly, in the comparison unit 38h, the voltage command V _m2 on the negative side and the amplitude of the carrier are compared. The output of the comparison unit 38h is the PWM signal Q3 to the switching element 53, and the output of the output inversion unit 38j, which is the inverted output of the comparison unit 38h, is the PWM signal Q4 to the switching element 54. The output inverting unit 38i does not turn on the switching element 51 and the switching element 52 at the same time, and the output inverting unit 38j does not turn on the switching element 53 and the switching element 54 at the same time.

FIG. 6 is a time chart showing examples of waveforms of the positive side voltage command, the negative side voltage command, the PWM signal, and the inverter output voltage shown in FIG. In FIG. 6, in order from the top, _{the waveform of the voltage command V m1 on the positive side output from the addition unit 38e, the waveform of the voltage command V m2} on the negative side output from the multiplication unit 38f, and the PWM signals Q1, Q2, The waveforms of Q3 and Q4 and the waveform of the inverter output voltage are shown. By using the voltage commands V _m1 and V _m2 , PWM signals Q1, Q2, Q3 and Q4 are generated. The motor drive device 2 shown in FIG. 2 uses PWM signals Q1, Q2, Q3, and Q4 to control a plurality of switching elements 51, 52, 53, and 54 in the single-phase inverter 11, as shown in FIG. An inverter output voltage as shown, that is, a PWM-controlled voltage pulse, is applied to the single-phase motor 12.

The modulation method used when generating the PWM signals Q1, Q2, Q3, and Q4 is bipolar modulation that outputs a voltage pulse that changes at a positive or negative potential, and voltage that changes at three potentials every half cycle of the power supply. Unipolar modulation is known to output a pulse, that is, a voltage pulse that changes to a positive potential, a negative potential, and a zero potential. The waveform shown in FIG. 6 is due to unipolar modulation. In the motor drive device 2 of the present embodiment, any modulation method may be used. In applications where it is necessary to control the motor current waveform to a more sinusoidal wave, it is preferable to adopt unipolar modulation having a lower harmonic content than bipolar modulation.

FIG. 7 is a diagram showing a change in the inverter output voltage according to the modulation factor. The upper part of FIG. 7 shows the voltage command V _m when the modulation factor = 1.0, and the carrier and the inverter output voltage. In the middle part of FIG. 7, the voltage command V _m , the carrier, and the inverter output voltage when the modulation factor = 1.2 are shown. In the lower part of FIG. 7, the voltage command V _m , the carrier, and the inverter output voltage when the modulation factor = 2.0 are shown.

As described with reference to FIG. 5, the voltage command V _m1 on the positive side is compared with the amplitude of the carrier in the comparison unit 38g, and the voltage command V _m2 on the negative side is compared with the amplitude of the carrier in the comparison unit 38h. When the voltage commands V _m1 and V _m2 are larger than the carrier amplitude, the switching element of the single-phase inverter 11 is turned on. When the voltage commands V _m1 and V _m2 are smaller than the carrier amplitude, the switching element of the single-phase inverter 11 is turned off. By these operations, the PWM-controlled inverter output voltage as shown in FIG. 6 is applied to the single-phase motor 12.

There are various definitions of the modulation factor, but in this specification, the ratio of the voltage amplitude command V * to the carrier amplitude, that is, "voltage amplitude command V * / carrier amplitude" is defined as the modulation factor. do. The upper part of FIG. 7 shows a waveform when the modulation factor is 1.0, but the same waveform is obtained when the modulation factor is less than 1.0. When the modulation factor is less than 1.0, the inverter output voltage is generated according to the carrier frequency, so that the inverter output voltage also outputs a voltage pulse corresponding to the carrier frequency.

On the other hand, when the modulation factor exceeds 1.0, the waveforms are as shown in the middle and lower portions of FIG. When the modulation factor exceeds 1.0, it is called "overmodulation", and the region where the modulation factor exceeds 1.0 is called "overmodulation region". In the overmodulation region, since the voltage command V _m exceeds the carrier amplitude, there is a section in which the inverter drive signal cannot be generated according to the carrier frequency. In this section, the inverter output voltage is fixed to a positive power supply voltage or a negative power supply voltage, so that the inverter output voltage can obtain a larger output voltage than when the modulation factor is 1.0.

Next, problems when using a battery as a power source and countermeasures will be described.

A battery is a structure in which the properties of internal impedance appear. Therefore, the battery output voltage changes greatly depending on the current output from the battery. Specifically, it is known that when a current of 20 [A] is passed through a battery of 20 [V], the battery output voltage drops to about 17 [V]. Further, it is known that when the above-mentioned modulation factor is in the region of 1.0 or more, the number of output voltage pulses is reduced, which causes a problem that the output voltage cannot be accurately obtained with respect to the _{voltage command V m.} Has been done. Further, it is known that the voltage output from the battery also pulsates because the battery current becomes a pulsating current due to the influence of switching by the single-phase inverter 11. If these problems are controlled so that the advance angle is not set to a constant value but is changed sequentially, the variation in the voltage applied from the battery to the single-phase inverter 11 and the voltage output by the single-phase inverter 11 Both variations can be suppressed.

Next, the advance angle control in the present embodiment will be described. FIG. 8 is a block diagram showing a functional configuration for calculating the advance phase input to the carrier comparison unit shown in FIGS. 4 and 5. The function for calculating the advance phase θ _v can be realized by the rotation speed calculation unit 42 and the advance phase calculation unit 44 as shown in FIG.

The rotation speed calculation unit 42 calculates the rotation speed ω of the single-phase motor 12 based on the position sensor signal detected by the position sensor 21. Further, the rotation speed calculation unit 42 calculates a reference phase θ _{e obtained} by _{converting the rotor mechanical angle θ m} , which is an angle from the reference position of the rotor 12a, into an electric angle. The advance angle phase calculation unit 44 calculates the advance angle phase θ _v based on the rotation speed ω and the reference phase θ _e calculated by the rotation speed calculation unit 42 and the position sensor signal.

FIG. 9 is a diagram showing an example of a method of calculating the advance angle phase in the embodiment. The horizontal axis of FIG. 9 indicates the rotation speed N, and the vertical axis of FIG. 9 indicates the advance phase θ _v . When expressing the rotation speed in the unit of [rpm], the notation of "N" is used. As shown in FIG. 9, the advance phase θ _v can be determined by using a function in which the _{advance phase θ v} increases with respect to the increase in the rotation speed N. Further, in FIG. 9, the advance angle adjustment width Δθdel indicates a variation range of the mounting position of the position sensor 21. In the example of FIG. 9, the advance phase θ _v is determined by a linear function of the first order, but the function is not limited to the linear function of the first order. A function other than the linear linear function of the first order may be used as long as the _{advance phase θ v} is the same or increases as the rotation speed N increases.

FIG. 10 shows the position sensor signal output from the position sensor shown in FIG. 2, the rotor mechanical angle which is an angle from the reference position of the rotor 12a shown in FIG. 2, and the phase obtained by converting the rotor mechanical angle into an electric angle. It is a figure which shows the relationship between a certain reference phase, and the voltage command shown in FIG. At the bottom of FIG. 10 _{, a single-phase motor 12 in which the rotor mechanical angles θ m} when the rotor 12a is rotated clockwise is 0 °, 45 °, 90 °, 135 °, and 180 ° is shown. .. The rotor 12a of the single-phase motor 12 is provided with four magnets. Four teeth 12b1 are provided on the outer circumference of the rotor 12a. When the rotor 12a rotates clockwise, a position sensor signal corresponding to the _{rotor mechanical angle θ m is detected.} The control unit 25 calculates the _{reference phase θ e} converted into the electric angle according to the detected position sensor signal.

_{The voltage command V m} shown as “Example 1” in the middle part of FIG. 10 is a voltage command when the advance phase θ _v = 0. When the advance phase θ _v = 0, a sinusoidal voltage command V _m having the same phase as the reference phase θ _e is output. The amplitude of the voltage command V _m at this time is determined based on the voltage amplitude command V * described above.

_{The voltage command V m} shown as “Example 2” in the middle part of FIG. 10 is a voltage command when the advance phase θ _v = π / 4. When the advance phase θ _v = π / 4, _{the sinusoidal voltage command V m} advanced by π / 4, which is a component of the advance phase θ _v , is output _{from the reference phase θ e.}

Next, how to give the voltage amplitude command V * will be described. FIG. 11 is a diagram showing a time change of the voltage amplitude command V * in the embodiment. In the present embodiment, the voltage amplitude command V * is an operation mode that changes stepwise with time as shown in the figure. Specifically, first, a constant first voltage V ₁ set in advance is given at the time of startup. In startup period, the first voltage V ₁ is maintained. In the acceleration section, the voltage amplitude command V * is increased so that a preset acceleration rate can be obtained. After accelerating, when shifting to the stationary operation section, the rise of the voltage amplitude command V * is stopped. In the stationary operation section, the voltage amplitude command V * at the time of acceleration stop is maintained. As a result, in the stationary operation section, a constant second voltage V _{2 larger than the first voltage V 1} is given. That is, in the present embodiment, the voltage amplitude command V * is controlled to be constant in the start-up section and the stationary operation section. In the start-up section, the _{time τ1 for applying the first voltage V 1} can be set to an arbitrary time in consideration of the stable time of the control system.

Next, the effect of the constant voltage amplitude command V * will be described. By keeping the voltage amplitude command V * constant in the stationary operation section, the following effects can be obtained.

(1) Even when the load changes suddenly, a constant voltage command can be output based on the phase detected from the position sensor signal.
(2) Since the voltage amplitude is not affected even when the rotation speed fluctuates, the output voltage can be kept stable.

In the case of the vacuum cleaner 1, the “load” referred to here means a closed state of the suction port body 63. The closed state of the suction port body 63 is related to the gap formed between the suction port body 63 and the floor surface which is the cleaning surface. This gap can be defined by the concept of "aperture ratio". The details of the aperture ratio will be described later.

By the way, in the constant rotation speed control implemented in a general vacuum cleaner, an overcurrent may flow in the motor. The reason why the overcurrent flows is that the current fluctuates abruptly because the rotation speed is kept constant when the load fluctuates. More specifically, when the constant rotation speed control is performed when the transition from the "light load state", that is, the "load torque is small state" to the "heavy load state", that is, the "load torque is large state", it is the same. This is because the motor output torque must be increased in order to maintain the rotation speed, and the amount of change in the motor current becomes large.

On the other hand, in the present embodiment, as described above, the voltage amplitude command V * is controlled to be constant in the stationary operation section. Here, when the voltage amplitude command V * is constant, the voltage amplitude command V * does not change when the load becomes heavy, so that the rotation speed of the motor decreases as the load torque increases. Even if the rotation speed of the motor decreases, a sudden change in the motor current and an overcurrent can be prevented, so that a sudden change in the rotation speed of the motor can be suppressed. This makes it possible to realize a vacuum cleaner that rotates stably.

In the case of an electric vacuum cleaner, the load torque increases as the rotation speed of the blades, which is the load of the single-phase motor, increases, and also as the diameter of the air passage increases. The diameter of the air passage means the width of the suction port of the suction port body in the case of an electric vacuum cleaner as an example. When the suction port is wide, for example, when nothing is in contact with the suction port, a force for sucking wind is required, so that the load torque when the blades are rotating at the same rotation speed becomes large. On the other hand, when the suction port is narrow, for example, when the suction port is in contact with some object and is blocked, the force for sucking the wind is not required, so the load when the blades are rotating at the same rotation speed. The torque becomes smaller.

Next, the aperture ratio will be described. FIG. 12 is a diagram for explaining the definition of the aperture ratio in the embodiment. Here, the "aperture ratio" in the embodiment is a percentage representing the degree of the gap formed between the suction port 69 of the suction port body 63 shown in FIG. 1 and the cleaning surface. FIG. 12 schematically shows the suction port body 63 of the vacuum cleaner 1 shown in FIG. 1, the extension pipe 62 connected to the suction port body 63, and the air passage 72 in the extension pipe 62. There is. The solid arrows in the figure indicate the air flow. In FIG. 12, the suction port of the suction port body 63 is not indicated by a reference numeral.

As shown on the left side of FIG. 12, a state in which the suction port of the suction port body 63 is closed by the floor surface 76 is defined as an aperture ratio = 0%. The sealed state is a state in which air does not flow. On the other hand, as shown on the right side of FIG. 12, the case where the suction port of the suction port body 63 is not in contact with the floor surface 76 is defined as the aperture ratio = 100%. In the center of FIG. 12, an intermediate state between the two, that is, an aperture ratio = 50% is shown.

The aperture ratio also changes depending on the type of floor surface. In addition to the floor surface type, the aperture ratio changes depending on the suction mode such as when the suction port is clogged with dust or when the suction port sucks the curtain. Therefore, in the present specification, the range of the aperture ratio according to the floor surface type or the suction mode is defined as follows.

-Opening ratio when the suction port of the suction port body 63 is clogged with a suction material: 0 to 10%
-Opening ratio when the floor surface 76 is a carpet: 10 to 50%
-Aperture ratio when the floor surface 76 is flooring: 50 to 80%
-Opening ratio when the suction port of the suction port body 63 is away from the floor surface 76: 80 to 100%

The aperture ratio according to the floor surface type or suction mode is affected by the structure of the suction port of the vacuum cleaner or the degree of dust clogging at the suction port. Therefore, the numerical values shown here are merely examples.

As described above, in the present embodiment, the voltage amplitude command V * is controlled to be constant during the steady operation. When this control is performed, the rotation speed of the single-phase motor 12 changes according to the load fluctuation. From the opposite point of view, the load fluctuation can be indirectly observed by observing the rotation speed of the single-phase motor 12. Here, the load fluctuation appears as a result of the fluctuation of the aperture ratio. The variation of the aperture ratio is a variation of the floor surface type or a variation of the suction mode. Therefore, by observing the motor rotation speed, it is possible to recognize the fluctuation of the floor surface type or the fluctuation of the suction mode. That is, by controlling the present embodiment in which the voltage amplitude command V * is constant, it is possible to incorporate control according to the floor surface type and the suction mode.

FIG. 13 is a diagram provided for explaining a method of controlling a voltage command according to an embodiment. The horizontal axis of FIG. 13 indicates the rotation speed N, and the vertical axis of FIG. 13 indicates the advance phase θ _v and the voltage amplitude command V *.

In the example of FIG. 13, the control region according to the rotation speed and the aperture ratio is divided into four regions from region 1 to region 4. Region 1 assumes a state where the opening ratio is 80% to 100%, that is, the suction port 63 does not touch the floor surface. Region 2 assumes a case where the aperture ratio is 50% to 80%, that is, the floor surface is flooring. Region 3 assumes a case where the aperture ratio is 10% to 50%, that is, the floor surface is a carpet. The region 4 assumes a case where the opening ratio is 0% to 10%, that is, a state where the suction port body 63 is sealed, or a case where the suction port body 63 is clogged with a suction material.

The advance phase θ _v changes as shown by the thick broken line in FIG. 13 as the rotation speed N increases. Then, the voltage amplitude command V * is set according to the rotation speed N.

The transition from region 1 to region 2 takes place when the aperture ratio falls below the threshold of 80% between the regions. When the aperture ratio is less than 80%, it is considered that the suction port body 63 of the vacuum cleaner 1 has moved from the state where the suction port body 63 of the vacuum cleaner 1 does not touch the floor surface 76 to the floor surface 76 which is the flooring. In this case, the rotation speed N is further increased by changing the voltage amplitude command V * from the first command value Vc1 to the second command value Vc2. The second command value Vc2 is larger than the first command value Vc1. At this time, as described above, the advance angle phase θ _v is increased by the inclination value K as the rotation speed N increases. The transition from the area 2 to the area 1 is also performed in the same manner. The transition from the region 2 to the region 1 is performed when the aperture ratio exceeds the threshold value of 80% between the regions.

The transition from region 2 to region 3 takes place when the aperture ratio falls below the threshold of 50% between the regions. When the aperture ratio is less than 50%, it is considered that the suction port 63 of the vacuum cleaner 1 has moved from the flooring to the carpet. Carpets require more suction than flooring. Therefore, the rotation speed N is further increased by setting the voltage amplitude command V * to a larger value. Specifically, the voltage amplitude command V * is changed from the second command value Vc2 to the third command value Vc3. The third command value Vc3 is larger than the second command value Vc2. Further, as the rotation speed N increases, the advance angle phase θ _v is also increased by the inclination value K. By changing the voltage amplitude command V * from the second command value Vc2 to the third command value Vc3, the suction force can be further increased. The transition from the area 3 to the area 2 is also performed in the same manner. The transition from region 3 to region 2 takes place when the aperture ratio exceeds the threshold of 50% between the regions.

The transition from region 3 to region 4 takes place when the aperture ratio falls below the threshold of 10% between the regions. When the opening ratio is less than 10%, it is assumed that the suction port 63 is clogged with suction material during cleaning of the carpet. When the attracted material is clogged, the value of the voltage amplitude command V * is reduced in order to reduce the rotation speed N. Specifically, the voltage amplitude command V * is changed from the third command value Vc3 to the fourth command value Vc4. The fourth command value Vc4 is smaller than the first command value Vc1. Further, in order to reduce the rotation speed N, the advance angle phase θ _v is reduced by the inclination value “−K”. By changing the voltage amplitude command V * to the fourth command value Vc4, it is possible to suppress an increase in the rotation speed N and suppress unnecessary heat generation in the single-phase motor 12. The transition from the area 4 to the area 3 is also performed in the same manner. The transition from the region 4 to the region 3 is performed when the aperture ratio exceeds the threshold value of 10% between the regions.

The example shown in FIG. 13, that is, the example of changing the voltage amplitude command V * according to the aperture ratio is an example, and the present invention is not limited to this. The magnitude relationship of the voltage command value may be changed depending on the application. Further, when there are a plurality of operation modes of the product, the above-mentioned first to fourth command values may have a plurality of values for each operation mode.

Further, in the above description, the transition between the region 1 and the region 2, the transition between the region 2 and the region 3, and the transition between the region 3 and the region 4 have been described, but the transition between the region 1 and the region 3 has been described. A transition between regions, a transition between regions 1 and 4, and a transition between regions 2 and 4 can also occur. The transition from the area 1 to the area 3 is performed when the upper limit value of the aperture ratio range in the area 3 is 50%, and the aperture ratio falls below the threshold value. The transition from the region 3 to the region 1 is performed when the lower limit value of the aperture ratio range in the region 1 is 80%, and the aperture ratio exceeds the threshold value. The transition from the area 1 to the area 4 is performed when the upper limit value of the aperture ratio range in the area 4 is 10%, which is the threshold value, and the aperture ratio falls below the threshold value. The transition from the region 4 to the region 1 is performed when the lower limit value of the aperture ratio range in the region 1 is 80%, and the aperture ratio exceeds the threshold value. The transition from the area 2 to the area 4 is performed when the upper limit value of the aperture ratio range in the area 4 is 10%, which is the threshold value, and the aperture ratio falls below the threshold value. The transition from the area 4 to the area 2 is performed when the lower limit value of the aperture ratio range in the area 2 is 50%, and the aperture ratio exceeds the threshold value.

Next, a method of calculating the aperture ratio will be described. FIG. 14 is a diagram provided for explaining a method of calculating the aperture ratio in the embodiment.

FIG. 14 shows three curves composed of “Vc1”, “Vc2” and “Vc3” shown in FIG. 13 with respect to the voltage amplitude command V * that changes according to the aperture ratio. The range of the aperture ratio is as in the above example. In addition, "no floor surface" means a state in which the suction port body 63 is separated from the floor surface 76.

In FIG. 14, when the rotation speed is less than N1, the voltage amplitude command V * = Vc1 and the operating point moves on the thick solid line L1. When the rotation speed N1 is reached, the voltage amplitude command V * = Vc2 is set, and the operating point moves on the thick solid line L2. At this time, the rotation speed N reaches N2. When the rotation speed is N2 or more and less than N3, the operating point moves on the thick solid line L2. When the rotation speed N3 is reached, the voltage amplitude command V * = Vc3 is set, and the operating point moves on the thick solid line L3. At this time, the rotation speed N reaches N4. At a rotation speed of N4 or higher, the operating point moves on the thick solid line L3.

As described above, when the rotation speed N is changed, the relationship of the voltage amplitude command V * with respect to the aperture ratio changes. Therefore, the relationship between the rotation speed N and the voltage amplitude command V * is grasped in advance and held in a table (not shown) in the control unit 25. In the example shown in FIG. 14, the voltage amplitude command V * = Vc1 is obtained when the rotation speed is smaller than N1 and the aperture ratio = 100% to 80%. Similarly, when the rotation speeds are N1 to N3, the aperture ratio is 80% to 50%, and the voltage amplitude command V * = Vc2. Further, when the rotation speed is N3 or more, the aperture ratio is 50% to 10%, and the voltage amplitude command V * = Vc3. When the number of revolutions suddenly rises or falls, the number of revolutions becomes higher than the number of revolutions after the sudden rise, and the number of revolutions may become smaller than the number of revolutions after the sudden drop. The aperture ratio does not correspond to the thick solid line of 14. Based on the rotation speed ω calculated by the rotation speed calculation unit 42 shown in FIG. 8, the aperture ratio can be determined by referring to the table in which the relationship between the aperture ratio, the rotation speed N, and the voltage amplitude command V * is held. The corresponding voltage amplitude command V * can be calculated.

In the example of FIG. 13, _{the slope for increasing the advance phase θ v} is constant, and the voltage amplitude command V *, which is a constant value within the aperture ratio range, is output according to the aperture ratio range. , Not limited to this. The voltage amplitude command V * may be constant, and the slope for increasing the _{advance phase θ v may be changed.} Hereinafter, this method will be described with reference to FIG. That is, FIG. 15 is a diagram provided for explaining the method of controlling the advance phase in the embodiment.

In FIG. 15, the transition from region 1 to region 2 occurs when the aperture ratio falls below the threshold of 80% between the regions. At this time, the voltage amplitude command V * is not changed _{, and the slope for increasing the advance phase θ v} is changed from the first slope value K1 to the second slope value K2. The first slope value K1 and the second slope value K2 are both positive. Further, the second inclination value K2 is larger than the first inclination value K1. The transition from the area 2 to the area 1 is also performed in the same manner. The transition from the region 2 to the region 1 is performed when the aperture ratio exceeds the threshold value of 80% between the regions. At this time, _{the slope for increasing the advance phase θ v} is changed from the second slope value K2 to the first slope value K1.

The transition from region 2 to region 3 takes place when the aperture ratio falls below the threshold of 50% between the regions. Also at this time, the voltage amplitude command V * is not changed _{, and the slope for increasing the advance phase θ v} is changed from the second slope value K2 to the third slope value K3. The second slope value K2 and the third slope value K3 are both positive. Further, the third inclination value K3 is larger than the second inclination value K2. The transition from the area 3 to the area 2 is also performed in the same manner. The transition from region 3 to region 2 takes place when the aperture ratio exceeds the threshold of 50% between the regions. At this time, _{the slope for increasing the advance phase θ v} is changed from the third slope value K3 to the second slope value K2.

The transition from region 3 to region 4 takes place when the aperture ratio falls below the threshold of 10% between the regions. Also at this time, the voltage amplitude command V * is not changed _{, and the slope for increasing the advance phase θ v} is changed from the third slope value K3 to the fourth slope value K4. The fourth slope value K4 is negative. The transition from the area 4 to the area 3 is also performed in the same manner. The transition from the region 4 to the region 3 is performed when the aperture ratio exceeds the threshold value of 10% between the regions. At this time, _{the slope for increasing the advance phase θ v} is changed from the fourth slope value K4 to the third slope value K3.

The example shown in FIG. 15, _{that is, the example of changing the inclination value of the advance angle phase θ v} according to the aperture ratio is an example, and the present invention is not limited to this. The magnitude relationship of the slope value of the advance angle phase θ _v in each region may be changed depending on the application. Further, when there are a plurality of operation modes of the product, the above-mentioned first to fourth inclination values may have a plurality of values for each operation mode.

Further, in the above description, the transition between the region 1 and the region 2, the transition between the region 2 and the region 3, and the transition between the region 3 and the region 4 have been described, but the transition between the region 1 and the region 3 has been described. A transition between regions, a transition between regions 1 and 4, and a transition between regions 2 and 4 can also occur. The transition from the area 1 to the area 3 is performed when the upper limit value of the aperture ratio range in the area 3 is 50%, and the aperture ratio falls below the threshold value. The transition from the region 3 to the region 1 is performed when the lower limit value of the aperture ratio range in the region 1 is 80%, and the aperture ratio exceeds the threshold value. The transition from the area 1 to the area 4 is performed when the upper limit value of the aperture ratio range in the area 4 is 10%, which is the threshold value, and the aperture ratio falls below the threshold value. The transition from the region 4 to the region 1 is performed when the lower limit value of the aperture ratio range in the region 1 is 80%, and the aperture ratio exceeds the threshold value. The transition from the area 2 to the area 4 is performed when the upper limit value of the aperture ratio range in the area 4 is 10%, which is the threshold value, and the aperture ratio falls below the threshold value. The transition from the area 4 to the area 2 is performed when the lower limit value of the aperture ratio range in the area 2 is 50%, and the aperture ratio exceeds the threshold value.

Next, the effect of the advance angle control will be described. _{First, if the advance angle phase θ v} is increased according to the increase in the rotation speed N, the rotation speed range can be widened. When the advance phase θ _{v is set} to 0, the rotation speed N is saturated at the point where the motor applied voltage and the motor induced voltage are balanced. In order to further increase the rotation speed N, the advance angle phase θ _v is advanced and the magnetic flux generated in the stator 12b due to the armature reaction is weakened to suppress the motor-induced voltage and increase the rotation speed N. Therefore, by selecting the advance phase θ _{v according} to the rotation speed N, a wider rotation speed region can be obtained.

Next, the effect of providing the advance angle adjustment width Δθdel for the advance angle control will be described. First, by providing the advance angle adjustment width Δθdel, even if the position sensor 21 is displaced during manufacturing or the sensitivity characteristic deviation peculiar to the position sensor 21 occurs, the position is adjusted by the advance angle adjustment width Δθdel. It is possible to correct deviations or characteristic deviations. Thereby, a stable specific rotation speed N can be obtained. Further, since the correction of the misalignment or the characteristic misalignment can be omitted from the manufacturing process, it is possible to suppress the occurrence of a cost for correcting or adjusting the misalignment or the characteristic misalignment.

As described above, according to the advance angle control according to the present embodiment, when the aperture ratio of the suction port 63 is in the first range, the voltage amplitude command V * is kept constant and the rotation speed N is increased. _{The advance angle phase θ v} , which is the advance angle of the voltage command, is increased accordingly. This control enables stable driving in a wide rotation speed range. Further, by providing the advance angle adjustment width Δθdel, it is possible to suppress the influence on the rotation speed N even when the position sensor 21 is displaced.

Further, according to the advance angle control according to the present embodiment, when the aperture ratio of the suction port body 63 changes from the first range to the second range, the voltage amplitude command V * corresponds to the first range. The first command value is changed to the second command value corresponding to the second range. As a result, it is possible to control according to the variation of the floor surface type or the variation of the suction mode, and it is possible to obtain a preferable suction force according to the aperture ratio. Changing the voltage amplitude command V * from the first command value corresponding to the first range to the second command value corresponding to the second range is to change the voltage amplitude command V * from the single-phase inverter 11 to the single-phase motor 12. It is equivalent to changing the applied voltage from the first amplitude value corresponding to the first range to the second amplitude value corresponding to the second range.

When the advance phase θ _v is set by a function according to the rotation speed N, the rotation speed can be changed by changing the slope of the straight line or the curve indicated by the function. That is, when the opening ratio of the suction port body 63 is in the first range, _{the inclination of the straight line or the curve representing the advance angle phase θ v} is set to the first inclination value, and the opening ratio of the suction port body 63 is the second. In the case of a range, the slope of a straight line or curve representing _{the advance phase θ v is set as the second slope value.} As a result, the calculation of the advance phase θ _v can be performed quickly. When the function representing the advance phase θ _v is a curve, the slope of the tangent line at the control point of the curve can be used.

Next, the loss reduction method in the present embodiment will be described with reference to the drawings of FIGS. 16 to 19. FIG. 16 is a schematic cross-sectional view showing a schematic structure of a MOSFET. FIG. 16 illustrates an n-type MOSFET. FIG. 17 is a first diagram showing a path of a motor current depending on the polarity of the inverter output voltage output from the single-phase inverter shown in FIG. FIG. 18 is a second diagram showing a path of a motor current depending on the polarity of the inverter output voltage. FIG. 19 is a third diagram showing a path of a motor current depending on the polarity of the inverter output voltage.

In the case of an n-type MOSFET, as shown in FIG. 16, a p-type semiconductor substrate 80 is used. A source electrode 82, a drain electrode 83, and a gate electrode 84 are formed on the semiconductor substrate 80 having the p-type region 81. High-concentration impurities are ion-implanted into the portions in contact with the source electrode 82 and the drain electrode 83 to form an n-type region 85. Further, in the p-type semiconductor substrate 80, an oxide insulating film 86 is formed between the portion where the n-type region 85 is not formed and the gate electrode 84. That is, the oxide insulating film 86 is interposed between the gate electrode 84 and the p-type region 81 in the semiconductor substrate 80.

When a positive voltage is applied to the gate electrode 84, electrons are attracted to the interface between the p-type region 81 and the oxide insulating film 86 in the semiconductor substrate 80 and are negatively charged. Where the electrons are gathered, the density of the electrons is higher than that of the holes, and they are n-typed. This n-type portion serves as a current passage and is called a channel. The example of FIG. 16 is an example when the n-type channel 87 is formed. In the case of a p-type MOSFET, a p-type channel is formed.

When the polarity of the inverter output voltage is positive, as shown by the thick solid line (a) in FIG. 17, the current flows into the single-phase motor 12 through the channel of the switching element 51 which is the upper arm of the first phase, and the first phase It flows out of the single-phase motor 12 through the channel of the switching element 54, which is a two-phase lower arm. When the polarity of the inverter output voltage is negative, as shown by the thick broken line (b) in FIG. 17, the current flows into the single-phase motor 12 through the channel of the switching element 53 which is the upper arm of the second phase. , Flow out from the single-phase motor 12 through the channel of the switching element 52, which is the lower arm of the first phase.

Next, the current path when the inverter output voltage is zero, that is, when the zero voltage is output from the single-phase inverter 11, will be described. When the inverter output voltage becomes zero after the positive inverter output voltage is generated, no current flows from the power supply side as shown by the thick solid line (c) in FIG. 18, and the single-phase inverter 11 and the single-phase motor 12 It becomes a reflux mode in which the current flows back and forth between them. At this time, since the direction of the current flowing immediately before the single-phase motor 12 does not change, the current flowing out from the single-phase motor 12 is the channel of the switching element 54 which is the lower arm of the second phase and the channel of the first phase. It returns to the single-phase motor 12 through the body diode 52a of the switching element 52 which is the lower arm. When the inverter output voltage becomes zero after the negative inverter output voltage is generated, the direction of the current flowing immediately before is opposite, so that the current flows back as shown by the thick broken line (d) in FIG. The direction of the current is reversed. Specifically, the current flowing out of the single-phase motor 12 passes through the body diode 51a of the switching element 51, which is the upper arm of the first phase, and the channel of the switching element 53, which is the upper arm of the second phase. Return to the single-phase motor 12.

As described above, in the reflux mode in which the current flows back between the single-phase motor 12 and the single-phase inverter 11, a current flows through the body diode in either one of the first phase and the second phase. In general, it is known that the conduction loss is smaller when the current is passed through the channel of the MOSFET than when the current is passed in the forward direction of the diode. Therefore, in the present embodiment, in the reflux mode in which the reflux current flows, the MOSFET on the side having the body diode is controlled to be turned on in order to reduce the current flowing through the body diode.

In the reflux mode, the switching element 52 is controlled to be ON at the timing when the reflux current shown by the thick solid line (c) in FIG. 18 flows. With this control, as shown by the thick solid line (e) in FIG. 19, most of the reflux current flows on the channel side of the switching element 52 having a small resistance value. As a result, the semiconductor loss in the switching element 52 is reduced. Further, the switching element 51 is controlled to be turned on at the timing when the reflux current shown by the thick broken line (d) in FIG. 18 flows. With this control, as shown by the thick broken line (f) in FIG. 19, most of the reflux current flows on the channel side of the switching element 51 having a small resistance value. As a result, the semiconductor loss in the switching element 51 is reduced.

As described above, the loss of the switching element can be reduced by controlling the MOSFET on the side having the body diode to be turned on at the timing when the reflux current flows through the body diode. For this reason, the shape of the MOSFET is a surface mount type so that heat can be dissipated on the substrate, and if necessary, a part or all of the switching element is formed of a wide bandgap semiconductor to generate heat of the MOSFET only on the substrate. Achieve a structure that suppresses. If heat can be dissipated only by the substrate, a heat sink is not required, which contributes to the miniaturization of the inverter and can lead to the miniaturization of the product.

In addition to the above-mentioned heat dissipation method, by installing the substrate in the air passage, a further heat dissipation effect can be obtained. By installing the substrate in the air passage, the semiconductor element on the substrate can be dissipated by the wind generated by the electric blower, so that the heat generation of the semiconductor element can be significantly suppressed.

The vacuum cleaner 60 is a product in which the motor rotation speed fluctuates from 0 [rpm] to 100,000 or more [rpm]. When the single-phase motor 12 drives a product that rotates at high speed in this way, the control method according to the above-described embodiment is suitable. By keeping the voltage amplitude command V * constant and _{changing the advance phase θ v} according to the rotation speed, it is possible to respond to a sudden load change while expanding the rotation speed drive range from the low speed to the high speed rotation region. Further, since the motor current is controlled to be a sine wave by PWM control, highly efficient driving can be performed, so that a long operation time can be expected.

FIG. 20 is a diagram for explaining modulation control in the motor drive device of the present embodiment. The relationship between the number of revolutions and the modulation factor is shown on the left side of the figure. Further, on the right side of the figure, a waveform of the inverter output voltage when the modulation factor is 1 or less and a waveform of the inverter output voltage when the modulation factor exceeds 1 are shown. Generally, the load torque of a rotating body increases as the number of rotations increases. Therefore, it is necessary to increase the motor output torque as the rotation speed increases. Further, in general, the motor output torque increases in proportion to the motor current, and it is necessary to increase the inverter output voltage in order to increase the motor current. Therefore, the rotation speed can be increased by increasing the modulation rate and increasing the inverter output voltage.

Next, the rotation speed control in the present embodiment will be described. In the following description, an electric blower is assumed as a load, and the operating range of the electric blower is classified as follows.
(A) Low speed rotation range (low rotation speed range): 0 [rpm] to 80,000 [rpm]
(B) High-speed rotation range (high rotation speed range): 80,000 [rpm] or more

The region sandwiched between the above (A) and the above (B) is a gray zone, and may be included in the low speed rotation range or included in the high speed rotation range depending on the application.

First, control in the low speed rotation range will be described. In the low speed rotation range, PWM control is performed with the modulation factor set to 1 or less. By setting the modulation factor to 1 or less, the motor current can be controlled to be a sine wave, and the efficiency of the motor can be improved. When operating at the same carrier frequency in the low-speed rotation range and the high-speed rotation range, the carrier frequency becomes the carrier frequency that matches the high-speed rotation range, so that the PWM pulse tends to increase more than necessary in the low-speed rotation range. .. Therefore, a method of lowering the carrier frequency and lowering the switching loss in the low speed rotation range may be used. Further, by varying the carrier frequency in synchronization with the rotation speed, the pulse number may be controlled so as not to change according to the rotation speed.

Next, control in the high-speed rotation range will be described. In the high speed rotation range, the modulation factor is set to a value larger than 1. By making the modulation factor larger than 1, the increase in the switching loss can be suppressed by reducing the number of switchings performed by the switching element in the inverter while increasing the inverter output voltage. Here, when the modulation factor exceeds 1, the motor output voltage increases, but the number of switchings decreases, so that there is a concern about current distortion. However, during high-speed rotation, the reactance component of the motor becomes large and the di / dt, which is the change component of the motor current, becomes small. Become. Therefore, in the high-speed rotation range, the modulation factor is set to a value larger than 1, and control is performed to reduce the number of switching pulses. By this control, an increase in switching loss can be suppressed and high efficiency can be achieved.

As described above, the boundary between the low speed rotation range and the high speed rotation range is ambiguous. Therefore, the control unit 25 is set with a first rotation speed that determines the boundary between the low-speed rotation range and the high-speed rotation range, and the control unit 25 sets the rotation speed of the motor or load when the rotation speed is equal to or less than the first rotation speed. The modulation factor may be set to 1 or less, and when the rotation speed of the motor or load exceeds the first rotation speed, the modulation factor may be set to exceed 1.

The configuration shown in the above-described embodiment shows an example of the content of the present invention, can be combined with another known technique, and is one of the configurations without departing from the gist of the present invention. It is also possible to omit or change the part.

1 Electric vacuum cleaner, 2 Motor drive device, 6 Vacuum cleaner body, 11 Single-phase inverter, 11a, 11b connection end, 12 Single-phase motor, 12a rotor, 12b stator, 12b1 teeth, 20 voltage sensor, 21 position sensor, 22 current Sensor, 25 control unit, 30 analog digital converter, 31 processor, 32 drive signal generator, 33 carrier generator, 34 memory, 38 carrier comparison unit, 38a absolute value calculation unit, 38b division unit, 38c, 38d, 38f multiplication Unit, 38e addition unit, 38g, 38h comparison unit, 38i, 38j output inversion unit, 42 rotation speed calculation unit, 44 advance phase calculation unit, 51, 52, 53, 54 switching element, 51a, 52a, 53a, 54a body Diode, 62 Extension tube, 63 Suction port, 64 Electric blower, 65 Dust collection chamber, 66 Operation unit, 67 Battery, 69 Suction port, 72 Air passage, 76 Floor surface, 80 Semiconductor substrate, 81 p-type region, 82 Source Electrode, 83 drain electrode, 84 gate electrode, 85 n type region, 86 oxide insulating film.

Claims (8)

An electric vacuum cleaner including a single-phase motor, a motor drive device for driving the single-phase motor, and a suction tool for sucking dust.
The motor drive device is
A single-phase inverter that applies an AC voltage to the single-phase motor,
A position sensor that outputs a position sensor signal indicating the rotor magnetic pole position of the single-phase motor, and a position sensor that outputs a position sensor signal.
The rotation speed of the single-phase motor is calculated based on the position sensor signal, and the opening ratio of the gap formed between the suction port of the suction tool and the cleaning surface is calculated based on the calculated change in the rotation speed. Calculation unit and
With
When the aperture ratio is within the first range, the amplitude value of the AC voltage is set to the first value, and when the aperture ratio is within the second range, the amplitude value of the AC voltage is the first value. A vacuum cleaner with a second value that is different from. An electric vacuum cleaner including a single-phase motor, a motor drive device for driving the single-phase motor, and a suction tool for sucking dust.
The motor drive device is
A single-phase inverter that applies an AC voltage to the single-phase motor,
A position sensor that outputs a position sensor signal indicating the rotor magnetic pole position of the single-phase motor, and a position sensor that outputs a position sensor signal.
A current sensor that detects the motor current flowing through the single-phase motor, and
The rotation speed of the single-phase motor is calculated based on the position sensor signal, and the opening ratio of the gap formed between the suction port of the suction tool and the cleaning surface is calculated based on the calculated change in the rotation speed. Calculation unit and
With
By controlling the advance angle, which is the phase difference between the motor current and the position sensor signal,
The advance angle has a slope that increases as the rotation speed of the single-phase motor increases.
When the aperture ratio is in the first range, the inclination of the advance angle is the first inclination value, and when the aperture ratio is in the second range, the inclination of the advance angle is the first inclination value. A vacuum cleaner with a different second slope value. An electric vacuum cleaner including a single-phase motor, a motor drive device for driving the single-phase motor, and a suction tool for sucking dust.
The motor drive device includes a single-phase inverter that applies an AC voltage to the single-phase motor.
When the opening ratio of the gap formed between the suction port of the suction tool and the cleaning surface is within the first range, the rotation speed of the single-phase motor is the first rotation speed and the amplitude value of the AC voltage. Is the first value,
When the aperture ratio is within the second range, the rotation speed of the single-phase motor is a second rotation speed different from the first rotation speed, and the amplitude value of the AC voltage is the same as the first value. Is a different second value electric vacuum cleaner. An electric vacuum cleaner including a single-phase motor, a motor drive device for driving the single-phase motor, and a suction tool for sucking dust.
The motor drive device is
A single-phase inverter that applies an AC voltage to the single-phase motor,
A position sensor that outputs a position sensor signal indicating the rotor magnetic pole position of the single-phase motor, and a position sensor that outputs a position sensor signal.
With
By controlling the advance angle, which is the phase difference between the voltage applied to the motor and the position sensor signal,
The advance angle has a slope that increases as the rotation speed of the single-phase motor increases.
When the opening ratio of the gap formed between the suction port of the suction tool and the cleaning surface is within the first range, the rotation speed of the single-phase motor is the first rotation speed and the inclination of the advance angle is The first slope value,
When the opening ratio is within the second range, the rotation speed of the single-phase motor is a second rotation speed different from the first rotation speed, and the inclination of the advance angle is the same as the first inclination value. Is a vacuum cleaner with a different second tilt value. It has a plurality of aperture ratio ranges, and the upper limit value or the lower limit value of the aperture ratio range is set as a threshold value, and each time the aperture ratio exceeds or falls below the threshold value, the amplitude value of the AC voltage or the advance angle is set. The electric vacuum cleaner according to claim 2 or 4, wherein the inclination value is changed. The vacuum cleaner according to claim 2, 4 or 5, wherein the AC voltage amplitude value or the advance angle inclination value has a plurality of values for each operation mode. The single-phase inverter includes a plurality of switching elements and has a plurality of switching elements.
The vacuum cleaner according to any one of claims 1 to 6, wherein at least one of the plurality of switching elements is made of a wide bandgap semiconductor. The vacuum cleaner according to claim 7, wherein the wide bandgap semiconductor is silicon carbide, gallium nitride, or diamond.

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