WO2018047274A1

WO2018047274A1 - Motor drive device, electric fan, and electric vacuum cleaner

Info

Publication number: WO2018047274A1
Application number: PCT/JP2016/076452
Authority: WO
Inventors: 裕次 ▲高▼山; 有澤　浩一; 酒井　顕
Original assignee: 三菱電機株式会社
Priority date: 2016-09-08
Filing date: 2016-09-08
Publication date: 2018-03-15
Also published as: JP6889166B2; JPWO2018047274A1

Abstract

A motor drive device drives a single phase motor (12) by the power applied from a power supply (10) that is a storage battery, said single phase motor (12) being driven by a single phase alternating current. The motor drive device is provided with an inverter (11) for driving the single phase motor (12), wherein said inverter (11) makes the pulse width of an output voltage pulse wider as the voltage of the power supply (10) decreases, thereby suppressing the lowering of the output voltage and suppressing the lowering of the number of rotations to easily perform increasing of the number of rotations or maintaining of a constant number of rotations.

Description

Motor drive device, electric blower, and vacuum cleaner

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 downsizing, such as vacuum cleaners and hand dryers. A single-phase inverter can generally drive a motor by controlling the current polarity according to the switching of the rotor magnetic poles. In this case, the motor iron loss is caused by superimposing harmonic components on the current. Increases and efficiency decreases.

Japanese Patent No. 5524925

In Japanese Patent No. 5524925, a method is proposed in which when the motor current exceeds a threshold value, the winding is freewheeled and the motor current is controlled 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 the iron loss of the motor.

The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a high-efficiency motor driving device suitable for products that require high-speed rotation and downsizing.

The present invention is a motor driving device for driving a single-phase motor driven by single-phase alternating current with 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 pulse width of the voltage applied to the single phase motor becomes wider as the voltage of the storage battery becomes lower.

According to the present invention, by implementing PWM, the efficiency is improved by controlling the current in a sine wave shape in the low speed region, and the switching loss is reduced by reducing the number of pulses in the high speed region, thereby improving the efficiency. Is possible. By improving efficiency, the energy saving of the product is improved, and the operation time can be extended if the product uses a battery as a power source.

It is a figure which shows the structure of the motor drive device which concerns on embodiment of this invention. It is the figure which showed the circuit structural example of the inverter in embodiment. FIG. 2 is a circuit diagram illustrating a configuration for generating a drive signal in the drive signal generation unit of FIG. 1. FIG. 5 is a waveform diagram showing an output example of a voltage command value Vm *, inverter drive signals Q1 to Q4, and an output voltage Vm. It is a wave form diagram which shows an inverter output voltage in case a modulation factor is 1. FIG. It is a wave form diagram which shows an inverter output voltage in case a modulation factor is 1.2. It is a wave form diagram which shows an inverter output voltage in case a modulation factor is 2. FIG. It is the figure which showed the electric current path which flows into a motor with the voltage pulse output by the inverter. It is a figure which shows the relationship of the modulation factor with respect to a rotational speed. It is a figure which shows an example of a structure of the vacuum cleaner to which the motor drive device of embodiment was applied. It is a figure which shows an example of a structure of the hand dryer to which the motor drive device of embodiment was 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. However, it is planned from the beginning of the application to appropriately combine the configurations described in the embodiments. In the drawings, the same or corresponding parts are denoted by the same reference numerals, and description thereof will not be repeated.

[Configuration of motor drive unit]
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 that is a storage battery and a motor 12, and is an inverter 11 that drives the motor 12 by power applied from the power source 10 that is a storage battery, and a motor that is an alternating current that flows through the motor 12. A current detector 20 for detecting a current; a rotation detector 21 for detecting the rotational position of the rotor of the motor 12; a power supply voltage detecting means 22 for detecting a voltage applied from the power supply 10; a motor current and a rotor rotational position; The control part 15 which controls the inverter 11 based on is provided. The control unit 15 includes an analog / 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 that drives the motor 12 based on the detection results of the current detection unit 20 that detects the motor current and the rotation detection unit 21 that detects the rotor rotation position. The analog signal detected by the current detector 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 rotational position detected by the rotation detection unit 21, and the power supply voltage detected by the power supply voltage detection 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 generator 32.

FIG. 2 is a diagram illustrating a circuit configuration example of the inverter according to the 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 includes a plurality of semiconductor elements 51 to 54 that constitute upper and lower arms, and the first semiconductor element 51 and the second semiconductor element 52 include a positive power supply wiring 50P and a negative power supply. The wiring 50N is connected in series. The positive power supply wiring is a wiring connected to the positive electrode of the power supply 10, and the negative power supply wiring is a 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 power supply wiring 50P and the negative power supply wiring 50N. The third semiconductor element 53 and the fourth semiconductor element 54 connected in series are connected in parallel. 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 generator 32 of the controller 15.

The semiconductor elements 51 to 54 are MOSFETs, and include semiconductor switching elements 51a to 54a and body diodes 51b to 54b connected in reverse parallel 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, 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 the present embodiment is that the inverter 11 is composed of at least four elements necessary for driving a single-phase motor. Thus, miniaturization and weight reduction can be achieved by reducing the number of elements as much as possible. When performing unipolar modulation, positive, zero, and negative voltages can be output to the motor side.

In this embodiment, the switching element in the semiconductor element is illustrated as a MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor). However, the present embodiment is not limited to this, and other IGBTs (Insulated Gate Bipolar Transistors). The semiconductor switching element such as) can also be implemented.

[Description of PWM control]
In the present embodiment, when the motor 12 is driven by the inverter 11, PWM control (Pulse Width Modulation) is used. PWM control is a modulation method that modulates by changing the width of the output voltage pulse, and is generally used when driving a three-phase motor. In this embodiment, PWM control is performed on a single-phase motor. How to do will be described.

FIG. 3 is a circuit diagram showing a configuration for generating a drive signal in the drive signal generator 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 with the voltage command value Vm * for controlling the output voltage of the inverter 11 in the drive signal generator 32 inside the controller. Signals for driving 51 to 54 are generated.

Referring to FIG. 3, the drive signal generation unit 32 includes a multiplication circuit 34,

comparators

35 and 36, and

inversion circuits

37 and 38.

The multiplication circuit 34 inverts the sign of the voltage command value Vm * by multiplying the voltage command value Vm * that controls the output voltage of the inverter 11 by -1. The comparator 35 compares the voltage command value Vm * with the voltage value Vc of the carrier signal, and outputs 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 inverter drive signals Q3 and Q4.

Inversion circuits

37 and 38 invert the signs of inverter drive signals Q1 and Q3 output from

comparators

35 and 36, respectively. The inverter drive signals Q1 to Q4 are signals for controlling 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. 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, a voltage command value Vm *, an inversion value −Vm *, inverter drive signals Q1 to Q4, and a motor output voltage Vm are shown in order from the top. As a result of the inverter drive signals Q1 to Q4 being controlled as shown in FIG. 4, the voltage Vm applied to the motor 12 is controlled to three values: a positive output voltage + Vo, an output voltage 0, and a negative output voltage −Vo. (Unipolar control).

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

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 taken as the modulation rate. When this modulation factor is 1 or less, inverter drive signals Q1 to Q4 are generated according to the frequency of the triangular wave carrier Vc, so that the inverter output voltage Vm, which is the voltage applied to the motor 12, as shown in FIG. Also, a voltage pulse corresponding to the carrier frequency is output.

On the other hand, when the modulation rate exceeds 1 (hereinafter referred to as an overmodulation region), a section where the inverter voltage command value Vm * exceeds the amplitude of the triangular wave carrier voltage value Vc occurs as shown in FIGS. 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 the positive output voltage + Vo or the negative output voltage −Vo. A voltage can be obtained.

[Inverter current path]
FIG. 8 is a diagram showing a current path flowing through the motor by the voltage pulse output from the inverter. When a positive voltage pulse is output from the drive signal generator 32 to the inverter 11, a current flows through the motor 12 through a current path that passes through the

semiconductor switching elements

51a and 54a shown in FIG. Next, when a zero voltage pulse is output, the current path passes through the

semiconductor switching elements

52a and 54a or the current path passes through the

semiconductor switching elements

51a and 53a shown in FIG. 8B or 8D. A current flows through the motor 12. This is a mode in which current does not flow from the power source side, and current flows back between the motor and the inverter.

Similarly to the above, when a negative voltage pulse is output from the drive signal generator 32 to the inverter 11, the current path passes through 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 reverse flow.

[Explanation of reducing body diode flow time]
8B and 8D, in the mode in which current flows between the motor and the inverter, by turning on one of the semiconductor switching elements of each phase, the

body diodes

51b, 53b or the body diode 52b are turned on. , 54b can be shortened. In general, it is known that the conduction loss is reduced when a current is passed through the semiconductor switching element, compared to when a current is passed through a body diode connected in antiparallel to the semiconductor switching element. Therefore, it is possible to reduce the loss by shortening the time flowing through the body diodes 51b to 54b.

In particular, by using a MOSFET as the semiconductor element provided in the inverter, it is possible to control the current to flow through the semiconductor switching element that is a MOSFET without passing through the body diode when refluxing between the inverter and the motor. At this time, since the target MOSFET must be turned on in order to pass a current from the source side to the drain side of the MOSFET, control is performed to turn on the element to be recirculated in accordance with recirculation (FIG. 8B). ) And FIG. 8 (d)). In general, MOSFETs can reduce conduction loss by flowing a current to the FET side rather than conducting to a body diode. Therefore, by reducing the semiconductor element to a MOSFET, the loss at reflux is reduced. It becomes possible.

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

[Reduction of heat generation and simplification of heat dissipation structure]
The loss of the semiconductor element is determined from the total value of the conduction loss that occurs when current flows through the semiconductor element and the switching loss that occurs when the semiconductor switches. A semiconductor element generates heat due to an increase in the loss due to an increase in current. As a countermeasure, it is common to increase heat dissipation by attaching a metal (heat sink) having high thermal conductivity to the surface of the element. However, if a heat sink is attached, the heat radiation performance can be improved, but the installation space for attaching the heat sink increases, so that it is difficult to apply to a small product. Further, since the weight of the heat sink is increased, it is difficult to apply to a product that is required to be reduced in weight.

As described above, by shortening the time flowing through the body diode, it is possible to reduce the conduction loss during reflux and to suppress the heat generation of the element. For this reason, it becomes possible to make the shape of the MOSFET a surface-mount type with good heat dissipation to the substrate, and to suppress the temperature rise of the MOSFET only by the substrate. This eliminates the need for a heat sink and contributes to downsizing of the substrate.

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

In this way, the heat of the semiconductor element can be released only by the heat radiation to the substrate and the heat radiation to the air, and the device can be configured without a heat sink to realize a small and light product.

[Relationship between rotational speed and modulation rate]
FIG. 9 is a diagram showing the relationship of the modulation rate to the rotation speed. As the rotational speed increases, the load torque of the rotating body increases, so it is necessary to increase the motor output torque. In general, the motor output torque increases in proportion to the motor current, and the increase in the motor current requires an increase in the output voltage of the inverter. Therefore, it is possible to increase the rotation speed without difficulty by increasing the modulation rate and increasing the inverter output voltage.

Since the modulation rate is proportional to the motor rotation speed, in this embodiment, the motor is controlled so that the modulation rate is greater 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 switching per one electrical angle cycle is reduced, and the switching loss is reduced to suppress the reduction in motor efficiency. It is necessary to let Therefore, in FIG. 9, the point where the modulation rate exceeds 1 is set to 100,000 rpm or more. As a result, it is possible to perform control while suppressing an increase in switching loss during high-speed rotation.

More specifically, in the high-speed region (for example, 100,000 rpm or more), the number of switching operations performed by the semiconductor elements in the inverter is reduced while increasing the output voltage of the inverter by increasing the modulation rate above 1. As a result, an increase in switching loss can be suppressed. When the modulation factor exceeds 1, the motor output voltage increases, but the number of switching times decreases, so there is a concern about distortion of the motor current. However, since the reactance component of the motor increases during high-speed rotation, the amount of change (di / dt) per hour of the current flowing through the motor decreases.

On the other hand, in a low speed region (for example, 0 to 70,000 rpm), by controlling the modulation rate to 1 or less, the current is controlled to be a sine wave, and the motor efficiency is improved. 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, and therefore the number of PWM pulses tends to be more than necessary in the low speed region. Therefore, in the low speed region, a technique of reducing the switching loss by using a carrier frequency lower than the carrier frequency used in the high speed region may be adopted. Further, by changing the carrier frequency in accordance with the change in the rotation speed, the number of pulses per electrical angle cycle may not change even if the rotation speed changes.

Also, when the motor rotates at a high speed, the reactance of the motor increases, so that the current rise corresponding to the voltage pulse becomes gentle. Therefore, even when the voltage pulse decreases at the time of high speed rotation, it is possible to carry out control approaching a sine wave. That is, the current distortion is smaller during high-speed rotation than during low-speed rotation, and thus the influence on waveform distortion is small. Therefore, by increasing the number of switching pulses during high-speed rotation, an increase in switching loss can be suppressed and higher efficiency can be achieved.

[Description of PWM pulse]
The voltage pulse of the inverter output voltage is determined by comparing the triangular wave carrier voltage value Vc with 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 electrical angle period decreases, so that the influence of the output voltage pulse on the distortion of the current waveform also increases. In general, when an even number of voltage pulses are applied, even-order harmonics are superimposed, and the symmetry of the positive and negative waveforms is lost. Therefore, in order to make the motor current waveform approach a sine wave in which the harmonic content is suppressed, in the present embodiment, the number of output voltage pulses is controlled to be an odd number during the electrical angle half cycle.

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

Also, in order to reduce switching loss during high speed rotation, it is desirable to reduce the voltage pulse. In general, it is known that a sine wave can be controlled by putting voltage pulses five times or more in an electrical angle half cycle. Therefore, it is preferable to perform control so that the number of pulses when performing sine wave PWM control is 5, and in overmodulation control, the voltage pulse output from the inverter is 5 or less.

In addition, when generating an output voltage pulse, there is a control in which all pulses are performed with a fixed width, but in order to generate a sine wave with a smaller harmonic content, in this embodiment, the center of the electrical half cycle is generated. The inverter is controlled so that the pulse width becomes wider as it is closer to.

Also, when the power supply voltage of the power supply 10 that is a storage battery is lowered, there is a concern that the output voltage may also be lowered. Therefore, when the value of the power supply voltage detected by the power supply voltage detecting means 22 is reduced when it is not desired to reduce the rotation of the motor 12, such as during high-speed rotation, the modulation rate is increased and the pulse width of the output voltage pulse is increased. In this way, the inverter output voltage is increased, that is, the pulse width of the output voltage pulse is widened as the voltage of the power supply 10 becomes lower, thereby suppressing the decrease in the output voltage, suppressing the decrease in the rotational speed, and increasing or maintaining the rotational speed. The number of rotations can be maintained without difficulty.

The modulation method used when generating the inverter drive signal includes bipolar modulation that outputs voltage pulses to both positive and negative potentials, and voltage pulses with positive / zero and negative / zero at every half electrical angle cycle. 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 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 with current di / dt. Become. Therefore, the harmonic content at the time of switching is smaller in unipolar modulation. Therefore, in the present embodiment, control is performed using unipolar modulation, which can be controlled to a sine wave with a lower harmonic content.

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

The inverter 11 includes a first upper arm 51 and a first lower arm 52 connected in series between the positive power supply wiring 50P and the negative power supply wiring 50N, and in series between the positive power supply wiring 50P and the negative power supply wiring 50N. A second upper arm 53 and a second lower arm 54 connected to each other are included.

The single-phase motor 12 is connected between a first connection point between the first upper arm 51 and the first lower arm 52 and a 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 electrical 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 respectively composed of the semiconductor switching elements 51a to 54a and the body diode 51b connected to the semiconductor switching elements 51a to 54a in antiparallel. To 54b. When outputting the zero voltage, the control unit 15 makes the semiconductor elements of the first upper arm 51 and the second upper arm 53 conductive at the same time, or makes the semiconductor elements of the first lower arm 52 and the second lower arm 54 simultaneously. Energize to reduce body diode flow time.

In general, it is possible to reduce conduction loss by flowing current to the FET side rather than conducting to the body diode. Therefore, it is possible to reduce loss when returning by controlling as described above. It becomes.

Preferably, the control unit 15 controls the inverter 11 such that an odd number of voltage pulses is generated in the inverter 11 during an electrical angle half cycle. As a result, even-order harmonics can be prevented from being superimposed, and the symmetry of the positive and negative waveforms is not easily lost, and a sine wave current is likely to be generated.

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

[Example of application to a vacuum cleaner]
FIG. 10 is a diagram illustrating 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 collection chamber 65, an operation unit 66, a power supply 10 that 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 that is a storage battery, performs suction from the suction port body 63, and sucks dust into the dust collection chamber 65 through the extension pipe 62. In use, the operation unit 66 is held and the electric vacuum cleaner 61 is operated.

When driving a motor that performs high-speed rotation, such as a vacuum cleaner, the motor-driven rotation speed range is wide. Therefore, as shown in the present embodiment, the motor is driven exceeding a modulation factor of 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 the drive can be performed with high efficiency, it is possible to expect a longer operation time, and it is possible to contribute to a reduction in size and weight by reducing heat radiation components.

[Example of application to hand dryer]
FIG. 11 is a diagram illustrating 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 receiver 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 human 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 with an electric blower by inserting a hand into the hand insertion portion 79 at the top of the water receiving portion 73 and water is accumulated from the water receiving portion 73 to the drain container 74. Yes.

When driving a motor that performs high-speed rotation, such as a hand dryer, since the motor-driven rotation speed range is wide, as shown in the present embodiment, the motor is driven at a modulation rate exceeding 1 in the high rotation speed region. Thus, it is possible to reduce the switching loss in the high rotation speed region. In addition, since high-efficiency driving is possible, reduction of power consumption can be expected, and reduction of heat dissipation parts can contribute to reduction in size and weight. If it is small, restrictions on the installation location are eliminated, and the application range can be expanded.

In addition, although the electric blower described in the present embodiment is described as being mounted on a vacuum cleaner and a hand dryer, it is not limited to a vacuum cleaner, but a hand dryer, an incinerator, a pulverizer, a dryer, a dust collector, a printing machine , Products equipped with electric blowers such as cleaning machines, confectionery machines, tea making machines, woodworking machines, plastic extruders, cardboard machines, packaging machines, hot air generators, object transportation, dust collection, general air supply / exhaust air, OA equipment, etc. If there is, it is not limited to this.

The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is shown not by the above description of the embodiments but by the scope of claims, and is intended to include all modifications within the meaning and scope equivalent to the scope of claims.

1 motor drive device, 10 power supply, 11 inverter, 12 motor, 15 control unit, 20 current detection unit, 21 rotation detection unit, 30 digital converter, 31 processor, 32 drive signal generation unit, 34 multiplication circuit, 35, 36

comparator

37, 38 Inversion circuit, 50N negative power supply wiring, 50P positive power supply wiring, 51, 52, 53, 54 semiconductor element, 61 vacuum cleaner, 62 extension pipe, 63 suction port, 64 electric blower, 65 dust collection chamber, 66 operation part, 68, 77 sensor, 71 casing, 72 hand detection sensor, 73 water receiving part, 74 drain container, 76 cover, 78 inlet, 79 hand insertion part.

Claims

A motor driving device for driving a single-phase motor driven by a single-phase alternating current with electric power applied from a storage battery,
An inverter for driving the single-phase motor;
The inverter is
A first semiconductor element and a 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,
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 motor drive device in which the pulse width of the voltage applied to the single-phase motor becomes wider as the voltage of the storage battery becomes lower.
The motor drive device according to claim 1, wherein an odd number of voltage pulses are generated in the inverter during an electrical angle half cycle.
3. The motor driving apparatus according to claim 1, wherein the first to fourth semiconductor elements are surface-mounted on a substrate and do not use a heat dissipation material other than the substrate.
The motor driving apparatus according to any one of claims 1 to 3, wherein the first to fourth semiconductor elements are wide band gap semiconductors.
An electric blower comprising the motor drive device according to any one of claims 1 to 4.
A vacuum cleaner comprising the electric blower according to claim 5.