JP6889166B2 - Motor drive, electric blower, and vacuum cleaner - Google Patents

Description

The present invention relates to a motor drive device, an electric blower including the motor drive device, and a vacuum cleaner.

Single-phase inverters may be used in products that require high-speed rotation and miniaturization, such as vacuum cleaners and hand dryers. A single-phase inverter can generally drive a motor by controlling the current polarity to be switched according to the switching of the rotor magnetic poles, but in that case, the harmonic component is superimposed on the current, resulting in motor iron loss. Increases and efficiency deteriorates.

Japanese Patent No. 5524925

Patent No. 5524925 proposes a method of freewheeling the winding when the motor current exceeds a threshold value and controlling the motor current in a rectangular wave shape. In this case, harmonics other than the frequency of the output current are superimposed on the motor current, which causes an increase in iron loss of the motor.

The present invention has been made to solve the above problems, and an object of the present invention is to provide a highly efficient motor drive device suitable for products that require high-speed rotation and miniaturization.

The present invention is a motor drive device for driving a single-phase motor driven by single-phase alternating current by electric power applied from a storage battery, and includes an inverter for driving the single-phase motor. The inverter includes a first semiconductor element and a second semiconductor element connected in series, and a third semiconductor element and a fourth semiconductor element connected in series. The first semiconductor element and the second semiconductor element, and the third semiconductor element and the fourth semiconductor element are connected in parallel. The single-phase motor is connected between the first semiconductor element and the second semiconductor element and between the third semiconductor element and the fourth semiconductor element. The lower the voltage of the storage battery, the wider the pulse width of the voltage applied to the single-phase motor.

According to the present invention, the efficiency is improved by controlling the current in a sinusoidal shape in the low speed region by performing PWM, and the switching loss is reduced by reducing the number of pulses in the high speed region to improve the efficiency. Is possible. By increasing the efficiency, the energy saving of the product is improved, and if the product is powered by a battery, the operating time can be extended.

It is a figure which shows the structure of the motor drive device which concerns on embodiment of this invention. It is a figure which showed the circuit configuration example of the inverter in embodiment. It is a circuit diagram which showed the structure which generates the drive signal in the drive signal generation part of FIG. It is a waveform diagram which showed the output example of the voltage command value Vm *, the inverter drive signals Q1 to Q4, and the output voltage Vm. It is a waveform figure which shows the inverter output voltage when the modulation factor is 1. It is a waveform figure which shows the inverter output voltage when the modulation factor is 1.2. It is a waveform figure which shows the inverter output voltage when the modulation factor is 2. It is a figure which showed the current path which flows in a motor by the voltage pulse output by an inverter. It is a figure which shows the relationship of the modulation rate with respect to the rotation speed. It is a figure which shows an example of the structure of the electric vacuum cleaner to which the motor drive device of embodiment is applied. It is a figure which shows an example of the structure of the hand dryer to which the motor drive device of embodiment is applied.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Hereinafter, a plurality of embodiments will be described, but it is planned from the beginning of the application that the configurations described in the respective embodiments are appropriately combined. The same or corresponding parts in the drawings are designated by the same reference numerals, and the description thereof will not be repeated.

[Configuration of motor drive]
FIG. 1 is a diagram showing a configuration of a motor drive device according to an embodiment of the present invention. The motor drive device 1 is connected to a power source 10 which is a storage battery and an inverter 11 which is connected to the motor 12 and drives the motor 12 by the power applied from the power source 10 which is a storage battery, and a motor which is an AC current flowing through the motor 12. The current detection unit 20 that detects the current, the rotation detection unit 21 that detects the rotation position of the rotor of the motor 12, the power supply voltage detecting means 22 that detects the voltage applied from the power supply 10, the motor current and the rotor rotation position. A control unit 15 for controlling the inverter 11 is provided based on the above. The control unit 15 includes an analog-to-digital converter 30, a processor 31, and a drive signal generation unit 32.

The control unit 15 of the inverter 11 generates an analog signal for driving the motor 12 based on the detection results of the current detection unit 20 for detecting the motor current and the rotation detection unit 21 for detecting the rotor rotation position. The analog signal detected by the current detection unit 20 is converted into a digital signal by the analog-digital converter 30 and read by the processor 31. The processor 31 drives the motor 12 based on the digital signal read from the analog-digital converter 30, the rotor rotation position detected by the rotation detection unit 21, and the power supply voltage detected by the power supply voltage detecting means 22. A drive signal is generated and output to the inverter 11. The inverter 11 drives the motor 12 based on the drive signal output from the drive signal generation unit 32.

FIG. 2 is a diagram showing an example of a circuit configuration of an inverter according to an embodiment. As an example, a circuit configuration of a single-phase inverter using four semiconductor elements is shown.

As shown in FIG. 2, the inverter 11 is composed of a plurality of semiconductor elements 51 to 54 constituting the upper and lower arms, and the first semiconductor element 51 and the second semiconductor element 52 are a positive electrode power supply wiring 50P and a negative electrode power supply. It is connected in series with the wiring 50N. The positive electrode power supply wiring is wiring connected to the positive electrode of the power supply 10, and the negative electrode power supply wiring is wiring connected to the negative electrode of the power supply 10. The third semiconductor element 53 and the fourth semiconductor element 54 are connected in series between the positive electrode power supply wiring 50P and the negative electrode power supply wiring 50N. The third semiconductor element 53 and the fourth semiconductor element 54, which are connected in series, are connected in parallel. Further, the first semiconductor element 51 corresponds to the first upper arm, and the second semiconductor element 52 corresponds to the first lower arm. The third semiconductor element 53 corresponds to the second upper arm, and the fourth semiconductor element 54 corresponds to the second lower arm. The semiconductor elements 51 to 54 are on / off controlled based on the drive signal output from the drive signal generation unit 32 of the control unit 15.

Further, the semiconductor elements 51 to 54 are MOSFETs, and include semiconductor switching elements 51a to 54a and body diodes 51b to 54b connected in antiparallel to the semiconductor switching elements 51a to 54a. The first semiconductor element 51 includes a first semiconductor switching element 51a and a first body diode 51b, and the second semiconductor element 52 includes a second semiconductor switching element 52a and a second body diode 52b. The third semiconductor element 53 includes a third semiconductor switching element 53a and a third body diode 53b, and the fourth semiconductor element 54 includes a fourth semiconductor switching element 54a and a fourth body diode 54b.

One of the features of this embodiment is that the inverter 11 is composed of the minimum four elements required to drive the single-phase motor. By reducing the number of elements as much as possible in this way, it is possible to achieve miniaturization and weight reduction. Further, when performing unipolar modulation, positive, zero, and negative voltages can be output to the motor side.

In the example of this embodiment, the switching element in the semiconductor element is illustrated as a MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor), but the present embodiment is not limited to this, and other IGBTs (Insulated Gate Bipolar Transistor) are shown. ) And other semiconductor switching elements can also be used.

[Explanation of PWM control]
In this embodiment, PWM control (Pulse Width Modulation) is used when the motor 12 is driven by the inverter 11. PWM control is a modulation method that changes the width of the output voltage pulse to modulate it, and is generally often used when driving a three-phase motor. However, in the present embodiment, the single-phase motor is PWM-controlled. The method of doing this will be described.

FIG. 3 is a circuit diagram showing a configuration in which a drive signal is generated in the drive signal generation unit 32 of FIG. The inverter 11 is generally a semiconductor element provided in the inverter 11 by comparing the triangular wave carrier voltage value Vc and the voltage command value Vm * that controls the output voltage of the inverter 11 in the drive signal generation unit 32 inside the control unit. A signal for driving 51 to 54 is generated.

With reference to FIG. 3, the drive signal generation unit 32 includes a multiplication circuit 34, comparators 35 and 36, and inverting circuits 37 and 38.

The multiplication circuit 34 multiplies the voltage command value Vm * that controls the output voltage of the inverter 11 by -1 to invert the sign of the voltage command value Vm *. The comparator 35 compares the voltage command value Vm * with the voltage value Vc of the carrier signal, and outputs the inverter drive signals Q1 and Q2. The comparator 36 compares the inverted value of the voltage command value Vm * output from the multiplication circuit 34 with the voltage value Vc of the carrier signal, and outputs the inverter drive signals Q3 and Q4. The inverting circuits 37 and 38 invert the codes of the inverter drive signals Q1 and Q3 output from the comparators 35 and 36, respectively. The inverter drive signals Q1 to Q4 are signals for controlling the on / off of the semiconductor elements 51 to 54.

The inverter drive signals Q1 and Q2 output from the comparator 35 are Q1 = H (High) and Q2 = L (Low) if Vm *> Vc, and Q1 = L and Q2 = H if Vm * <Vc. It becomes. Further, the inverter drive signals Q3 and Q4 output from the comparator 36 are Q3 = H and Q4 = L if −Vm *> Vc, and Q3 = L and Q4 = H if −Vm * <Vc. ..

FIG. 4 is a waveform diagram showing an output example of the voltage command value Vm *, the inverter drive signals Q1 to Q4, and the output voltage Vm. In FIG. 4, the voltage command value Vm *, the inverted value −Vm *, the inverter drive signals Q1 to Q4, and the motor output voltage Vm are shown in order from the top. As a result of controlling the inverter drive signals Q1 to Q4 as shown in FIG. 4, the voltage Vm applied to the motor 12 is controlled to three values of positive output voltage + Vo, output voltage 0, and negative output voltage −Vo. (Unipolar control).

Next, how the inverter output voltage changes when the modulation factor changes will be described. FIG. 5 is a waveform diagram showing the inverter output voltage when the modulation factor is 1. FIG. 6 is a waveform diagram showing the inverter output voltage when the modulation factor is 1.2. FIG. 7 is a waveform diagram showing the inverter output voltage when the modulation factor is 2.

The ratio of the amplitude of the inverter voltage command Vm * and the triangular wave carrier voltage value Vc (inverter voltage command / triangular wave carrier amplitude) is defined as the modulation factor. When this modulation factor is 1 or less, the inverter drive signals Q1 to Q4 are generated according to the frequency of the triangular wave carrier Vc. Therefore, as shown in FIG. 5, the inverter output voltage Vm which is the voltage applied to the motor 12 Also, a voltage pulse corresponding to the carrier frequency is output.

On the other hand, when the modulation factor exceeds 1, (hereinafter, referred to as an overmodulation region), as shown in FIGS. 6 and 7, a section in which the inverter voltage command value Vm * exceeds the amplitude of the triangular wave carrier voltage value Vc occurs. To do. In this section, the inverter drive signal corresponding to the frequency of the triangular wave carrier is not generated, and the inverter output voltage is fixed to positive output voltage + Vo or negative output voltage-Vo, so that the output is larger than when the modulation factor is 1. It becomes possible to obtain a voltage.

[Inverter current path]
FIG. 8 is a diagram showing a current path flowing through the motor by the voltage pulse output by the inverter. When a positive voltage pulse is output from the drive signal generation unit 32 to the inverter 11, a current flows through the motor 12 in the current path via the semiconductor switching elements 51a and 54a shown in FIG. 8A. Next, when the zero voltage pulse is output, the current path passes through the semiconductor switching elements 52a and 54a shown in FIGS. 8 (b) or 8 (d) or the current path passes through the semiconductor switching elements 51a and 53a. A current flows through the motor 12. This is a mode in which no current flows from the power supply side and the current returns between the motor and the inverter.

Similar to the above, when a negative voltage pulse is output from the drive signal generator 32 to the inverter 11, it becomes a current path via the semiconductor switching elements 53a and 52a shown in FIG. 8C, and the voltage pulse is positive. A current flows through the motor 12 in the opposite flow to the time.

[Explanation to reduce the flow time of the body diode]
In FIGS. 8 (b) and 8 (d), in the mode in which the current recirculates between the motor and the inverter, the semiconductor switching element of either of the phases is turned on to turn on the body diodes 51b, 53b or the body diode 52b. , 54b can shorten the flow time. In general, it is known that passing a current through a semiconductor switching element reduces conduction loss as compared with passing a current through a body diode connected in antiparallel to the semiconductor switching element. Therefore, the loss can be reduced by shortening the time flowing through the body diodes 51b to 54b.

In particular, by using the semiconductor element provided in the inverter as a MOSFET, it is possible to control the flow back to the semiconductor switching element, which is a MOSFET, without passing through the body diode when recirculating between the inverter and the motor. At this time, since the target MOSFET must be turned on in order for the current to flow from the source side to the drain side of the MOSFET, control is performed to turn on the recirculating element at the time of recirculation (FIG. 8 (b). ) And FIG. 8 (d)). Generally, in a MOSFET, it is possible to reduce the conduction loss by passing a current on the FET side rather than conducting it through the body diode. Therefore, by using a MOSFET as a semiconductor element, the loss at reflux is reduced. It becomes possible.

A wide bandgap semiconductor may be used as the semiconductor switching element. By using a wide bandgap semiconductor (for example, SiC) as the semiconductor switching element, the on-resistance becomes smaller than that of a silicon semiconductor (Si), and heat generation can be further suppressed.

[Suppression of heat generation and simplification of heat dissipation structure]
The loss of a semiconductor element is determined from the total value of the conduction loss generated when a current flows through the semiconductor element and the switching loss generated when the semiconductor switches. A semiconductor element generates heat due to an increase in the above loss due to an increase in current. As a countermeasure, it is common practice to attach a metal (heat sink) having high thermal conductivity to the surface of the element to improve heat dissipation. However, if a heat sink is attached, heat dissipation can be improved, but the installation space for attaching the heat sink is increased, so that it is difficult to apply to small products. In addition, since the weight of the heat sink increases, it is difficult to apply it to products that require weight reduction.

As described above, by shortening the time flowing through the body diode, it is possible to reduce the conduction loss at the time of reflux and suppress the heat generation of the element. Therefore, the shape of the MOSFET can be changed to a surface mount type with good heat dissipation to the substrate, and the temperature rise of the MOSFET can be suppressed only by the substrate. In this way, the heat sink becomes unnecessary, which contributes to the miniaturization of the substrate.

In addition to the heat dissipation method in which the element is surface-mounted on the substrate, further heat dissipation effect can be obtained by installing the substrate in the air passage. For example, it is used for an electric blower that generates an air flow, and the temperature rise of the semiconductor element can be significantly suppressed by dissipating heat from the semiconductor element on the substrate by the wind generated by the electric blower. Such an electric blower is mounted on a vacuum cleaner or a hand dryer, which will be described later in FIGS. 10 and 11.

In this way, it is possible to dissipate the heat of the semiconductor element only by dissipating heat to the substrate and heat to the air, and it is possible to configure the device without a heat sink and realize a compact and lightweight product.

[Relationship between rotation speed and modulation rate]
FIG. 9 is a diagram showing the relationship of the modulation factor with respect to the rotation speed. Since the load torque of the rotating body increases as the rotation speed increases, it is necessary to increase the motor output torque. Generally, the motor output torque increases in proportion to the motor current, and it is necessary to increase the output voltage of the inverter in order to increase the motor current. Therefore, it is possible to increase the rotation speed without difficulty by increasing the modulation rate and the inverter output voltage.

Since the modulation factor is proportional to the motor rotation speed, in the present embodiment, the motor is controlled so that the modulation factor becomes larger than 1 at a rotation speed of 100,000 rpm or more.

This is because when the motor is operated at an operating point of 100,000 rpm or more, the motor iron loss increases, so the number of switchings per cycle of the electric angle is reduced, and the reduction in switching loss is suppressed to suppress the reduction in motor efficiency. I need to let you. Therefore, in FIG. 9, the point where the modulation factor exceeds 1 is set to 100,000 rpm or more. This makes it possible to carry out control that suppresses an increase in switching loss during high-speed rotation.

More specifically, in the high-speed region (for example, 100,000 rpm or more), the output voltage of the inverter is increased by making the modulation factor larger than 1, and the number of switchings performed by the semiconductor element in the inverter is reduced. This makes it possible to suppress an increase in switching loss. When the modulation factor exceeds 1, the motor output voltage increases, but the number of switchings decreases, so that there is a concern about distortion of the motor current. However, since the reactance component of the motor becomes large during high-speed rotation, the amount of change (di / dt) of the current flowing through the motor per hour becomes small.

On the other hand, in the low speed region (for example, 0 to 70,000 rpm), the modulation factor is controlled to 1 or less to control the current to a sine wave to improve the efficiency of the motor. When a common carrier frequency is used in the low speed region and the high speed region, the carrier frequency matched to the high speed region is adopted, so that the number of PWM pulses tends to be larger than necessary in the low speed region. Therefore, in the low speed region, a method of reducing the switching loss may be adopted by using a carrier frequency lower than the carrier frequency used in the high speed region. Further, by changing the carrier frequency according to the change of the rotation speed, the configuration may be such that the number of pulses per one cycle of the electric angle does not change even if the rotation speed changes.

Further, when the motor is rotating at a high speed, the reactance of the motor increases, so that the rise of the current corresponding to the voltage pulse becomes gentle. Therefore, even when the voltage pulse is reduced during high-speed rotation, it is possible to perform control approaching a sine wave. That is, since the current distortion is smaller at high speed rotation than at low speed rotation, the influence on the waveform distortion is small. Therefore, at the time of high-speed rotation, it is possible to suppress an increase in switching loss and improve efficiency by reducing the number of switching pulses.

[Explanation of PWM pulse]
The voltage pulse of the inverter output voltage is determined by comparing the triangular wave carrier voltage value Vc and the voltage command value Vm *. During high-speed rotation, the frequency of the voltage command value Vm * also increases, and the number of voltage pulses output during one cycle of the electrical angle decreases, so that the effect of the output voltage pulses on the distortion of the current waveform also increases. Generally, when an even-numbered voltage pulse is applied, even-order harmonics are superimposed, and the symmetry of the positive and negative waveforms is lost. Therefore, in order to bring the motor current waveform closer to a sine wave in which the content of harmonics is suppressed, in the present embodiment, the number of output voltage pulses is controlled to be an odd number during the electric angle half cycle.

In order to control the number of output voltage pulses to be odd during high-speed rotation, there is a method of synchronizing the triangular wave carrier with the motor rotation speed. Further, when performing control using the rotation speed as a command value in the product specifications, there is a method of determining the carrier frequency in advance with respect to the rotation speed command. However, in the present embodiment, the control is not limited to this as long as the number of output voltage pulses is an odd number.

Further, it is desired to reduce the voltage pulse in order to reduce the switching loss at the time of high-speed rotation. Generally, it is known that a sine wave can be controlled by inputting a voltage pulse of 5 times or more during an electric angle half cycle. Therefore, it is preferable to set the number of pulses to 5 when performing sine wave PWM control, and to control so that the number of voltage pulses output by the inverter is 5 or less in overmodulation control.

Further, when generating the output voltage pulse, there is a control that all the pulses are executed with a fixed width, but in order to generate a sine wave having a smaller harmonic content, in this embodiment, the center of the electric half cycle. The inverter is controlled so that the closer to is, the wider the pulse width is.

Further, when the power supply voltage of the power supply 10 which is a storage battery drops, there is a concern that the output voltage also drops. Therefore, when the rotation of the motor 12 is not to be reduced, such as during high-speed rotation, and the value of the power supply voltage detected by the power supply voltage detecting means 22 is reduced, the modulation factor is increased to widen the pulse width of the output voltage pulse. By doing so, the inverter output voltage is increased, that is, the lower the voltage of the power supply 10, the wider the pulse width of the output voltage pulse is, thereby suppressing the decrease in the output voltage, suppressing the decrease in the rotation speed, and increasing or constant the rotation speed. It is possible to maintain the number of rotations of the inverter without difficulty.

In addition, as the modulation method used when generating the inverter drive signal, bipolar modulation that outputs voltage pulses to both positive and negative potentials and voltage pulses with positive / zero and negative / zero every half cycle of the electrical angle are applied. The output unipolar modulation is known.

In bipolar modulation, the motor voltage is output at two levels of -V and + V, whereas in unipolar modulation, it is output at three levels of -V, 0 and + V. During the half cycle of the motor current (0 to 180 °), pulses are generated at 2 levels for bipolar modulation and 3 levels for unipolar modulation, so unipolar modulation is smaller when compared in terms of current di / dt. Become. Therefore, the harmonic content at the time of switching is smaller in the unipolar modulation. Therefore, in the present embodiment, control is performed using unipolar modulation, which is considered to be able to control a sine wave having a lower harmonic content.

[Summary of motor drive]
The motor drive device of the present embodiment described above will be summarized again with reference to FIGS. 1 and 2. The motor drive device 1 drives a single-phase motor 12 that is driven by single-phase alternating current. The motor drive device 1 includes an inverter 11 that drives the single-phase motor 12 and a control unit 15 that controls the inverter 11.

The inverter 11 is connected in series between the first upper arm 51 and the first lower arm 52 connected in series between the positive electrode power supply wiring 50P and the negative electrode power supply wiring 50N, and between the positive electrode power supply wiring 50P and the negative electrode power supply wiring 50N. Includes a second upper arm 53 and a second lower arm 54 that are connected.

The single-phase motor 12 is connected between the first connection point between the first upper arm 51 and the first lower arm 52 and the second connection point between the second upper arm 53 and the second lower arm 54. ..

The control unit 15 controls the inverter so as to output a voltage pulse to the single-phase motor so that the pulse width becomes wider as it is closer to the center in the electric angle half cycle. The first upper arm 51, the first lower arm 52, the second upper arm 53, and the second lower arm 54 are body diodes 51b connected in antiparallel to the semiconductor switching elements 51a to 54a and the semiconductor switching elements 51a to 54a, respectively. Includes ~ 54b. When the control unit 15 outputs a zero voltage, the semiconductor elements of the first upper arm 51 and the second upper arm 53 are simultaneously conducted, or the semiconductor elements of the first lower arm 52 and the second lower arm 54 are simultaneously conducted. Make it conductive and reduce the flow time of the body diode.

In general, it is possible to reduce the conduction loss by passing a current on the FET side rather than conducting it through the body diode. Therefore, it is possible to reduce the loss at the time of reflux by controlling as described above. It becomes.

Preferably, the control unit 15 controls the inverter 11 so as to generate an odd number of voltage pulses in the inverter 11 during the electric angle half cycle. As a result, even-order harmonics can be avoided from being superimposed, the symmetry of the positive and negative waveforms is less likely to be broken, and a sinusoidal current is likely to be generated.

[Product application example]
The effects of the actual product application examples in the present invention will be described below. As electrical equipment, a vacuum cleaner and a hand dryer will be described in particular.

[Example of application to vacuum cleaner]
FIG. 10 is a diagram showing an example of a configuration of a vacuum cleaner to which the motor drive device of the embodiment is applied. The vacuum cleaner 61 includes an extension pipe 62, a suction port 63, an electric blower 64, a dust collecting chamber 65, an operation unit 66, a power supply 10 which is a storage battery, and a sensor 68. The electric blower 64 includes the motor drive device 1 described in the embodiment. The vacuum cleaner 61 drives the electric blower 64 by the power supply 10 which is a storage battery, sucks the dust from the suction port 63, and sucks the dust into the dust collecting chamber 65 through the extension pipe 62. At the time of use, the operation unit 66 is held to operate the vacuum cleaner 61.

When driving a motor that performs high-speed rotation such as an electric vacuum cleaner, the motor drive rotation speed range is wide. Therefore, as shown in this embodiment, the motor drive speed exceeds 1 in the high rotation speed region. By doing so, it is possible to reduce the switching loss in the high rotation speed region. In addition, since it can be driven with high efficiency, it is possible to expect a longer operating time, and it is possible to contribute to miniaturization and weight reduction by reducing heat dissipation parts.

[Example of application to hand dryer]
FIG. 11 is a diagram showing an example of a configuration of a hand dryer to which the motor drive device of the embodiment is applied. The hand dryer shown in FIG. 11 includes a casing 71, a hand detection sensor 72, a water receiving portion 73, a drain container 74, a cover 76, a sensor 77, and an intake port 78. Here, the sensor 77 is either a gyro sensor or a motion sensor. The hand dryer has an electric blower (not shown) in the casing 71. The hand dryer has a structure in which water is blown off by blowing air from an electric blower by inserting a hand into the hand insertion portion 79 above the water receiving portion 73, and water is stored from the water receiving portion 73 into the drain container 74. There is.

When driving a motor that performs high-speed rotation such as a hand dryer, the motor drive rotation speed range is wide. Therefore, as shown in this embodiment, the motor is driven with a modulation factor exceeding 1 in the high rotation speed region. Therefore, it is possible to reduce the switching loss in the high rotation speed region. In addition, since it can be driven with high efficiency, it is possible to reduce power consumption, and it is possible to contribute to miniaturization and weight reduction by reducing heat dissipation parts. If it is small, the restrictions on the installation location can be eliminated and the range of application can be expanded.

Although the electric blower described in this embodiment is described in the case where it is mounted on an electric vacuum cleaner and a hand dryer, it is not limited to the electric vacuum cleaner, but is not limited to the electric vacuum cleaner, but also a hand dryer, an incinerator, a crusher, a dryer, a dust collector, and a printing machine. , Cleaning machine, confectionery machine, tea making machine, woodworking machine, plastic extruder, cardboard machine, packaging machine, hot air generator, object transportation, dust absorption, general blower / exhaust, OA equipment, etc. If there is, it is not limited to this.

The embodiments disclosed this time should be considered to be exemplary in all respects and not restrictive. The scope of the present invention is shown by the claims rather than the description of the embodiments described above, and is intended to include all modifications within the meaning and scope equivalent to the claims.

1 motor drive, 10 power supply, 11 inverter, 12 motor, 15 control unit, 20 current detector unit, 21 rotation detector, 30 digital converter, 31 processor, 32 drive signal generator, 34 multiplication circuit, 35, 36 comparator , 37,38 Inverting circuit, 50N negative electrode power supply wiring, 50P positive electrode power supply wiring, 51, 52, 53, 54 semiconductor element, 61 electric vacuum cleaner, 62 extension tube, 63 suction port, 64 electric blower, 65 dust collection chamber, 66 operation unit, 68,77 sensor, 71 casing, 72 hand detection sensor, 73
Water receiver, 74 drain container, 76 cover, 78 air intake, 79 hand insertion part.

Claims (5)

A motor drive device that drives a single-phase motor driven by single-phase alternating current with electric power applied from a storage battery.
An inverter for driving the single-phase motor,
It is provided with a control unit that generates a drive signal of the inverter.
The inverter
The first semiconductor element and the second semiconductor element connected in series,
Including a third semiconductor element and a fourth semiconductor element connected in series,
The first semiconductor element and the second semiconductor element, the third semiconductor element and the fourth semiconductor element are connected in parallel, and the third semiconductor element and the fourth semiconductor element are connected in parallel.
The single-phase motor is connected between the first semiconductor element and the second semiconductor element and between the third semiconductor element and the fourth semiconductor element.
The control unit outputs a control signal for the first to fourth semiconductor elements based on the comparison result between the command value and the triangular wave carrier signal.
Wherein the control unit, while the so that to generate an electrical angle odd voltage pulse to the inverter during a half cycle, the single by the voltage of the battery to generate said command value so as to increase the modulation factor as lower phase of the motor voltage applied pulse width wide to Rutotomoni, by the rotational speed of the single-phase motor generates said command value so as to increase the modulation factor than 1 when exceeding the first rotational speed A motor drive device that reduces the number of switching pulses of the first to fourth semiconductor elements. The motor drive device according to claim 1, wherein the first to fourth semiconductor elements are surface-mounted on a substrate and do not use a heat radiating material other than the substrate. The motor drive device according to claim 1 or 2, wherein the first to fourth semiconductor elements are wide bandgap semiconductors. An electric blower comprising the motor driving device according to any one of claims 1 to 3. A vacuum cleaner comprising the electric blower according to claim 4.

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