WO2017077574A1

WO2017077574A1 - Control device for single-phase ac motor

Info

Publication number: WO2017077574A1
Application number: PCT/JP2015/080933
Authority: WO
Inventors: 裕次 ▲高▼山; 和徳畠山; 崇山川; 篠本　洋介
Original assignee: 三菱電機株式会社
Priority date: 2015-11-02
Filing date: 2015-11-02
Publication date: 2017-05-11
Also published as: JP6410957B2; JPWO2017077574A1

Abstract

In the present invention, first and second magnetic sensors (24A, 24B) are disposed at positions separated from each other along the rotation direction of a rotor of a single-phase AC motor (10). In a starting process for causing the rotor in a stationary state to start in a first direction, a controller (16) drives the rotor by applying a driving voltage having a first polarity from an inverter (14) to a stator. The controller (16) detects the rotation direction of the rotor on the basis of signals detected by the first and second magnetic sensors (24A, 24B) when the rotor is in the stationary state and when the rotor is rotating. When the rotation direction of the rotor is detected as a second direction opposite to the first direction, the controller (16) inverts the first polarity of the driving voltage to a second polarity.

Description

Single-phase AC motor controller

This invention relates to a control device for a single-phase AC motor.

Some products, such as vacuum cleaners and hand dryers, that use a single-phase AC motor as the drive source rotate the single-phase AC motor in only one direction due to product specifications. Some of these products are required to start a single-phase AC motor from a stopped state in a short time.

Some control devices for controlling the rotation of such a single-phase AC motor include a magnetic sensor that detects the magnetic pole position of the rotor in order to detect the rotation direction of the rotor of the single-phase AC motor. As a magnetic sensor, a Hall IC (Integrated Circuit) is generally used. The Hall IC is an IC in which a magnetic sensor element using the Hall effect and a circuit that converts an output signal of the element into a digital signal are contained in one package.

In the above control device, in order to rotationally drive the single-phase AC motor only in one direction, a device for starting the stationary single-phase AC motor in the one direction is devised.

For example, Japanese Patent No. 5469730 (Patent Document 1) discloses a method of starting a motor in the forward rotation direction. In Patent Document 1, one Hall IC for detecting the magnetic pole position of the rotor of the motor is used.

In Patent Document 1, when starting the motor, the controller first excites the windings to generate a positive excitation torque based on the detection signal output by the Hall IC when the motor is stationary. Let If the edge of the detection signal is detected within the first period during excitation, it is determined that the rotor is rotating in the forward rotation direction. If the edge of the detection signal is not detected within the first period, it is determined that the rotor is rotating in the reverse direction.

In Patent Document 1, the first period is set to a time sufficient for the rotor to rotate over a mechanical angle (N is the number of magnetic poles) of at least 360 ° / N from a stationary state.

Japanese Patent No. 5469730

The above-mentioned Patent Document 1 is configured to detect the rotation direction of the rotor by detecting the edge of the detection signal of one magnetic sensor. Therefore, it is necessary to set the first period, which is the time necessary for detecting the rotation direction of the rotor, to a time sufficient for an edge to appear in the detection signal. Therefore, there is a problem that it is difficult to start the motor in a short time.

Also, depending on individual variations of the magnetic sensor mounting accuracy or motor constants (winding inductance, winding resistance, etc.), the detection signal edge may not be detected within a predetermined first period. As a result, there is a possibility that the motor cannot be started or that the rotor rotates in the reverse direction. In this case, it is necessary to change the setting of the first period in consideration of the mounting position of the magnetic sensor and the motor constant. However, if the first period becomes longer, it takes more time to detect the rotation direction of the motor, and as a result, it becomes more difficult to start up in a short time.

The present invention has been made in view of the above, and an object thereof is to provide a control device for a single-phase AC motor that can be started in a short time of the single-phase AC motor.

A control device for a single-phase AC motor according to an aspect of the present invention is a control device for a single-phase AC motor including a rotor provided with a plurality of magnetic poles and a stator for generating a rotating magnetic field. The control device includes an inverter configured to apply a drive voltage of the single-phase AC motor to the stator, first and second magnetic sensors that detect the magnetic pole position of the rotor, and a controller. The controller is configured to control the inverter based on detection signals of the first and second magnetic sensors. The first and second magnetic sensors are arranged at positions separated from each other along the rotation direction of the rotor. The controller is configured to execute an activation process for activating the stationary rotor in the first direction. In the startup process, the controller drives the rotor by applying a first polarity voltage from the inverter to the stator. The controller detects the rotation direction of the rotor based on the detection signals of the first and second magnetic sensors when the rotor is stationary and when the rotor is rotating. The controller reverses the first polarity of the voltage to the second polarity when it is detected that the rotation direction of the rotor is the second direction opposite to the first direction.

According to an embodiment of the present invention, it is possible to provide a control device for a single-phase AC motor that can start the single-phase AC motor in a short time.

It is a figure which shows schematic structure of the control apparatus of the single phase alternating current motor according to embodiment of this invention. It is a schematic block diagram of the single phase alternating current motor in FIG. It is a block diagram which shows the control structure of the control apparatus of the single phase alternating current motor according to this Embodiment. It is a figure which shows typically a mode that the positional relationship of a rotor and a magnetic sensor changes temporally. It is a figure which shows the waveform of the position detection signal which the magnetic sensor shown in FIG. 4 outputs. It is a figure which shows the logic table | surface of the position detection signal which the magnetic sensor shown in FIG. 4 outputs. It is a figure for demonstrating the flow of the starting process for starting a rotor in a 1st direction. It is a timing chart corresponding to the flow of the starting process shown to Fig.7 (a). It is a timing chart corresponding to the flow of the starting process shown in FIG.7 (b). It is a flowchart for demonstrating the starting process according to this Embodiment. It is a schematic block diagram of the vacuum cleaner to which the control apparatus shown in FIG. 1 is applied. It is a block diagram which shows the control structure of the electric blower shown in FIG. It is a schematic block diagram of the hand dryer to which the control apparatus shown in FIG. 1 is applied.

Embodiments of the present invention will be described in detail with reference to the drawings. The same or corresponding parts in the drawings are denoted by the same reference numerals and description thereof will not be repeated.

[Configuration of control device for single-phase AC motor]
FIG. 1 is a diagram showing a schematic configuration of a control device for a single-phase AC motor according to an embodiment of the present invention.

Referring to FIG. 1, a control device 100 that controls a single-phase AC motor 10 includes a power source 12, an inverter 14, a controller 16, an analog-digital converter (ADC) 18, a gate driver 20, and a current sensor 22. And

magnetic sensors

24A and 24B.

The single-phase AC motor 10 is a single-phase AC synchronous motor, for example, a surface magnet type synchronous motor. FIG. 2 is a schematic configuration diagram of the single-phase AC motor 10 in FIG.

Referring to FIG. 2, single-phase AC motor 10 includes a rotor 2 and a stator 3. The rotor 2 has a plurality of magnetic poles. The rotor 2 is provided with a permanent magnet.

The stator 3 includes a stator core 4 and a stator coil 6 wound around the teeth 5 of the stator core 4. The stator 3 covers the periphery of the rotor 2. The rotor 2 is rotationally driven by the rotating magnetic field generated by the stator 3.

In the present embodiment, a control device 100 that controls the single-phase AC motor 10 in which the number of magnetic poles of the rotor 2 is 4 and the number of teeth 5 of the stator 3 is 4 will be described. However, the number of magnetic poles and the number of teeth of the single-phase AC motor 10 to which the present invention is applied are not limited thereto.

Referring to FIG. 1 again, power supply 12 is a DC power supply, for example, a power storage device configured to be chargeable / dischargeable. The power source 12 is not limited to a DC power source, and may be a converter that converts a single-phase AC voltage supplied from a single-phase AC power source into a DC voltage. In this case, the converter can include, for example, a diode bridge rectifier circuit constituted by four diodes and a smoothing capacitor.

The inverter 14 is a single phase inverter. The inverter 14 converts a DC voltage supplied from the power supply 12 through the power lines PL and NL into a driving voltage for the single-phase AC motor 10 and applies it to the stator 3 (stator coil 6) of the single-phase AC motor 10. Further, the inverter 14 can apply a drive voltage having a positive or negative polarity to the stator 3 of the single-phase AC motor 10 in a startup process for starting the rotor 2 in a stationary state. The configuration of the inverter 14 will be described in detail with reference to FIG.

The current sensor 22 detects a current (hereinafter also referred to as “motor current”) flowing through the stator coil 6 of the single-phase AC motor 10. The ADC 18 converts the detection signal of the current sensor 22 that is an analog signal into a digital signal. The digitally converted detection signal is input to the controller 16.

Magnetic sensors

24A and 24B detect the magnetic pole position of the rotor 2 of the single-phase AC motor 10. Detection signals from the

magnetic sensors

24A and 24B are input to the controller 16. In the following description, the detection signal of the magnetic sensor 24A (first magnetic sensor) is also referred to as “position detection signal SA”. The detection signal of the magnetic sensor 24B (second magnetic sensor) is also referred to as “position detection signal SB”. As the

magnetic sensors

24A and 24B, hall ICs can be typically used.

As shown in FIG. 1, the magnetic sensor 24 A and the magnetic sensor 24 B are arranged at positions separated from each other along the rotation direction of the rotor 2. Therefore, a phase difference corresponding to the angular interval between the magnetic sensor 24A and the magnetic sensor 24B is generated between the position detection signal SA and the position detection signal SB.

The controller 16 is configured based on a processor including a CPU and a memory (not shown), and controls the operation of the entire control device 100 of the single-phase AC motor 10. For example, the controller 16 generates a control signal for controlling the inverter 14 based on the detection signal of the current sensor 22 and the position detection signals SA and SB of the

magnetic sensors

24A and 24B.

The gate driver 20 controls switching of a plurality of semiconductor switching elements (see FIG. 3) constituting the inverter 14 according to the control signal generated by the controller 16.

FIG. 3 is a block diagram showing a control configuration of control device 100 of single-phase AC motor 10 according to the present embodiment.

Referring to FIG. 3, power supply 12 (FIG. 1) supplies DC voltage Vdc to power lines PL and NL. When the DC voltage Vdc is supplied from the power source 12, the inverter 14 converts the DC voltage Vdc into a single-phase AC voltage and drives the single-phase AC motor 10 according to a drive signal from the gate driver 20.

The inverter 14 includes four semiconductor switching elements Q1 to Q4, and four diodes D1 to D4 connected in parallel to these semiconductor switching elements in the reverse bias direction, respectively. In the example of FIG. 3, each of the semiconductor switching elements Q1 to Q4 is configured by a MOSFET (Metal Oxide Semiconductor Field Effect Transistor), but may be an IGBT (Insulated Gate Bipolar Transistor) or a bipolar transistor.

As a material constituting each semiconductor switching element, a wide band gap semiconductor having a larger band gap than silicon can be employed. The wide band gap semiconductor is preferably any of silicon carbide, gallium nitride-based material, and diamond.

The semiconductor switching elements Q1, Q2 are connected in series between the power line PL and the power line NL. Connection node N1 of semiconductor switching elements Q1, Q2 is connected to stator coil 6 of single-phase AC motor 10. Semiconductor switching elements Q3 and Q4 are connected in series between power line PL and power line NL and in parallel with the whole of semiconductor switching elements Q1 and Q2 connected in series. Connection node N2 of semiconductor switching elements Q3, Q4 is connected to stator coil 6 of single-phase AC motor 10.

Next, the operation of the inverter 14 will be briefly described.
Gate driver 20 is electrically connected to the gate terminals of semiconductor switching elements Q1-Q4. The gate driver 20 controls switching of the semiconductor switching elements Q1 to Q4.

Specifically, the gate driver 20 controls the control voltage applied to the gate terminal of each semiconductor switching element in response to a control signal from the controller 16. Depending on the magnitude of the control voltage, each semiconductor switching element is in a conductive state (on state) or a non-conductive state (off state).

When the semiconductor switching elements Q1 and Q4 are turned on and the semiconductor switching elements Q2 and Q3 are turned off, a positive DC voltage (+ Vdc) is applied to the stator coil 6. On the other hand, when the semiconductor switching elements Q2, Q3 are turned on and the semiconductor switching elements Q1, Q4 are turned off, a negative DC voltage (−Vdc) is applied to the stator coil 6. Note that when all of the semiconductor switching elements Q1 to Q4 are turned off, the voltage applied to the stator coil 6 is zero. In the following description, the voltage applied to the stator coil 6 of the single-phase AC motor 10 (drive voltage of the single-phase AC motor 10) is also referred to as “motor voltage Vm”.

When the single-phase AC motor 10 is in operation, the ON state of the semiconductor switching elements Q1 and Q4 and the ON state of the semiconductor switching elements Q2 and Q3 are alternately repeated, so that the motor voltage Vm becomes + Vdc and −Vdc. Switch alternately. Thereby, a rotating magnetic field is generated in the stator 3.

(Variable speed control of single-phase AC motor)
The controller 16 includes an activation processing unit 30, a speed control unit 32, a current control unit 34, and a PWM (Pulse Width Modulation) control unit 36.

When the single-phase AC motor 10 is driven, the speed control unit 32, the current control unit 34, and the PWM control unit 36 cooperate with each other to control the rotational speed of the single-phase AC motor 10 (hereinafter, “variable speed control”). Also called). Hereinafter, the variable speed control of the single-phase AC motor 10 will be briefly described.

The speed control unit 32, the current control unit 34, and the PWM control unit 36 are configured to feedback control the rotational speed of the single-phase AC motor 10 based on the target value of the rotational speed.

Specifically, the speed control unit 32 receives the position detection signals SA and SB of the

magnetic sensors

24A and 24B, and receives a speed command ω * indicating a target value of the rotational speed. The speed control unit 32 detects the magnetic pole position and the rotational speed of the rotor 2 based on the position detection signals SA and SB of the

magnetic sensors

24A and 24B. The speed control unit 32 calculates the target value of the motor current by performing PI (proportional and integral) control on the deviation between the speed command ω * and the rotation speed detection value.

The current control unit 34 receives a current command i * indicating a target value of the motor current, receives a detection signal of the current sensor 22, and receives position detection signals SA and SB of the

magnetic sensors

24A and 24B. The current control unit 34 determines the phase of the motor current using the magnetic pole position of the rotor 2 obtained from the position detection signals SA and SB. The current control unit 34 calculates the target value of the voltage to be applied to the single-phase AC motor 10 by performing PI control on the deviation between the current command i * and the detected motor current value. The current control unit 34 outputs a voltage command v * indicating the target value of the voltage applied to the single-phase AC motor 10 to the PWM control unit 36.

The PWM control unit 36 generates a control signal for PWM control of the semiconductor switching elements Q1 to Q4 constituting the inverter 14 based on the voltage command v *. The PWM control unit 36 outputs the generated control signal to the gate driver 20.

The configuration of the feedback control configured by the speed control unit 32, the current control unit 34, and the PWM control unit 36 is a general one. However, in this embodiment, since the magnetic pole position of the rotor 2 is detected using the two position detection signals SA and SB, the magnetic pole position is detected at a finer timing than when a single position detection signal is used. can do. Therefore, the magnetic pole position detection accuracy can be increased.

Since the responsiveness of the feedback control is improved by increasing the magnetic pole position detection accuracy, the rotational speed of the single-phase AC motor 10 can be made to follow the speed command ω *. In particular, when the single-phase AC motor 10 is accelerated, the rotational speed can be made to follow the speed command ω * in the process of increasing the speed command ω *. As a result, it is possible to suppress the occurrence of vibration in the single-phase AC motor 10 due to fluctuations in the output torque of the single-phase AC motor 10.

(Start process)
In the operation stop state of the single-phase AC motor 10, the activation processing unit 30 performs an activation process for activating the stationary rotor 2 in the first rotation direction. In the present embodiment, the “first rotation direction” is the forward rotation direction (clockwise), and the “second rotation direction” opposite to the first rotation direction is the reverse rotation direction (counterclockwise). . The “first rotation direction” may be the reverse rotation direction, and the “second rotation direction” may be the normal rotation direction.

Hereinafter, the activation process will be described.
In the startup process, the startup processing unit 30 first acquires the position detection signals SA and SB of the

magnetic sensors

24A and 24B when the rotor 2 is stationary. Next, the motor voltage Vm having the first polarity is applied to the stator coil 6 of the single-phase AC motor 10. When the stator coil 6 is energized, the stator 3 is excited. The first polarity may be a positive polarity or a negative polarity.

When the stator 3 is excited, the rotor 2 is activated by the magnetic force (attraction force and repulsive force) generated between the teeth 5 of the stator 3 and the magnetic poles of the rotor 2. The activation processing unit 30 detects the rotation direction of the rotor 2 based on the position detection signals SA and SB when the rotor 2 is stationary and when the rotor 2 is rotating.

When it is detected that the rotation direction of the rotor 2 is the normal rotation direction (first rotation direction), the activation processing unit 30 applies a motor voltage Vm composed of a single-phase AC voltage to the stator coil 6 in that state. . Thereby, the rotor 2 rotates in the normal rotation direction by the rotating magnetic field generated by the stator 3.

On the other hand, when it is detected that the rotation direction of the rotor 2 is the reverse rotation direction (second rotation direction), the activation processing unit 30 temporarily stops the application of the motor voltage Vm, and then the first polarity is A motor voltage Vm having a different second polarity is applied to the stator coil 6. Since the direction of the magnetic force is switched by reversing the polarity of the motor voltage Vm, the rotor 2 starts to rotate in the direction opposite to the previous rotation direction, that is, the forward rotation direction. When it is detected that the rotation direction of the rotor 2 is switched to the normal rotation direction, the activation processing unit 30 applies a motor voltage Vm composed of a single-phase AC voltage to the stator coil 6. Thereby, the rotor 2 rotates in the normal rotation direction by the rotating magnetic field generated by the stator 3.

In the present embodiment, in the start-up process, from when the first polarity voltage is applied to the single-phase AC motor 10 in the operation stop state until the rotation direction of the rotor 2 is detected to be the normal rotation direction. Is defined as “start-up time”. As will be described later, control device 100 for a single-phase AC motor according to the present embodiment realizes a reduction in startup time.

(Detection of rotor rotation direction)
Hereinafter, the principle of the method for detecting the rotational direction of the rotor 2 according to the present embodiment will be described with reference to FIGS.

FIG. 4 is a diagram schematically illustrating a state in which the positional relationship between the rotor 2 and the

magnetic sensors

24A and 24B transitions in time when the rotor 2 of the single-phase AC motor 10 rotates in the forward rotation direction.

In the example of FIG. 4, the magnetic sensor 24A is arranged at a position where the rotation angle (mechanical angle) of the rotor 2 is 0 °. The magnetic sensor 24B is disposed at a position where the rotation angle (mechanical angle) of the rotor 2 is 45 °. That is, the magnetic sensor 24 A and the magnetic sensor 24 B are arranged on the same circle around the rotation axis 1 of the rotor 2 with an angular interval of 45 °.

In FIG. 4, the rotor 2 rotates in the forward direction. 4A to 4E show the rotor 2 and the

magnetic sensors

24A and 24B when the rotation angle (mechanical angle) of the rotor 2 is 0 °, 45 °, 90 °, 135 °, and 180 °, respectively. Represents the positional relationship. Since the number of magnetic poles of the rotor 2 is 4, a mechanical angle of 180 ° corresponds to an electrical angle of 360 °.

When the magnetic sensor 24A detects a magnetic flux line extending from the magnetic pole of the rotor 2 toward the outer circumferential direction, that is, when the N pole of the rotor 2 is detected, the magnetic sensor 24A outputs a position detection signal SA of logic level “1”. On the other hand, when the magnetic sensor 24A detects a magnetic flux line extending in the inner circumferential direction from the magnetic pole of the rotor 2, that is, when the S pole of the rotor 2 is detected, the magnetic sensor 24A outputs a position detection signal SA of logic level “0”. To do.

Similarly to the magnetic sensor 24A, the magnetic sensor 24B outputs a position detection signal SB having a logic level “1” when detecting the N pole of the rotor 2, and outputs a logic level “0” when detecting the S pole of the rotor 2. The position detection signal SB of “” is output.

FIG. 5 is a diagram showing waveforms of the position detection signals SA and SB output from the

magnetic sensors

24A and 24B shown in FIG. In FIG. 5, the timing shown in FIGS. 4A to 4E, that is, the timing at which the rotation angle (mechanical angle) of the rotor 2 becomes 0 °, 45 °, 90 °, 135 °, and 180 °, respectively, Shown with an arrow.

Referring to FIG. 5, each of position detection signals SA and SB is alternately switched between “1” and “0” at an interval of 90 ° mechanical angle (corresponding to an interval of 180 ° electrical angle). . The position detection signal SA is “0” when the rotation angle of the rotor 2 is 0 ° to 90 ° (states of FIGS. 4A to 4C), and when the rotation angle is 90 ° to 180 ° (FIG. 4). 4 (c) to (e)), “1”. The position detection signal SB is obtained when the rotation angle of the rotor 2 is 0 ° to 45 ° (the state shown in FIGS. 4 (a) to (b)) and when the rotation angle is 135 ° to 180 ° (FIG. 4 (d) to ( The state of e) is “1”, and is “0” when the rotation angle is 45 ° to 135 ° (the states of FIGS. 4B to 4D).

In the example of FIG. 4, the magnetic sensor 24 A and the magnetic sensor 24 B are arranged at an angular interval of 45 ° along the rotation direction of the rotor 2. Therefore, in the waveform diagram of FIG. 5, the position detection signal SA and the position detection signal SB have a phase difference of 45 ° mechanical angle. Since the number of magnetic poles of the rotor 2 is 4, the phase difference corresponds to a phase difference of an electrical angle of 90 ° (= 45 ° × 4/2). Thereby, combinations of logic levels that can be taken by the position detection signals SA and SB when the rotor 2 is rotating can be summarized in four ways as shown in FIG.

FIG. 6 is a diagram showing a logical table of the position detection signals SA and SB output from the

magnetic sensors

24A and 24B shown in FIG. In FIGS. 5 and 6, the states of FIGS. 4A to 4B are represented as [1], the states of FIGS. 4B to 4C are represented as [2], and FIG. The states of (d) to (d) are represented as [3], and the states of FIGS. 4 (d) to (e) are represented as [4]. FIG. 6 shows combinations of position detection signals SA and SB in each of these four states [1] to [4].

Referring to FIG. 6, when the combination of position detection signals SA and SB is represented as (SA, SB), (SA, SB) is (0, 1) in state [1] and in state [2]. (0, 0), (1, 0) in state [3], and (1, 1) in state [4].

For example, when the stationary rotor 2 is in the state [1] and the rotor 2 rotates in the forward rotation direction, the state of the rotor 2 changes from [1] → [2] → [3] → [4] → Transition is made in the order of [1] → [2]. On the other hand, when the rotor 2 rotates in the reverse direction, the state of the rotor 2 changes in the order of [1] → [4] → [3] → [2] → [1] → [2].

Here, it is assumed that the stationary rotor 2 is in the state [2]. In this case, when the rotor 2 rotates in the forward rotation direction, the state of the rotor 2 changes from [2] to [3]. On the other hand, when the rotor 2 rotates in the reverse direction, the state of the rotor 2 changes from [2] to [1]. In other words, the state of transition after the stationary state varies depending on the rotation direction of the rotor 2. Therefore, if the state of the rotor 2 when stationary (hereinafter also referred to as an “initial state”) and the next transition state can be grasped, the rotation direction of the rotor 2 is the normal rotation direction or the reverse rotation direction. Can be detected.

Specifically, the initial state of the rotor 2 can be detected from (SA, SB) when the rotor 2 is stationary. When the stationary rotor 2 is started, first, one of the position detection signals SA and SB is switched according to the rotation direction. If it is possible to grasp which position detection signal is switched first, the rotation direction of the rotor 2 can be detected. According to this, the rotation direction of the rotor 2 can be detected at the timing when the first position detection signal is switched after the rotor 2 starts to rotate.

If this is applied when the initial state is the state [2], (SA, SB) in the initial state (= [2]) is (0, 0). If the rotation direction is the normal rotation direction, the position detection signal SA is first switched from “0” to “1”. On the other hand, if the rotation direction is the reverse rotation direction, the position detection signal SB is first switched from “0” to “1”. In any rotation direction, the first position detection signal is switched until the rotor 2 rotates 45 ° from the stationary state. Therefore, the rotation direction of the rotor 2 can be detected until the rotor 2 rotates 45 ° from the stationary state.

As described above, in the present embodiment, by using the position detection signals of the plurality of magnetic sensors, the rotation direction of the rotor 2 is detected by capturing the timing at which one of the plurality of position detection signals is switched. be able to. According to this, as in the prior art using the position detection signal of one magnetic sensor, the start-up process of the rotor 2 can be performed stably without being affected by the mounting accuracy of individual magnetic sensors and variations in motor constants. Can do.

Also, the rotational direction of the rotor 2 can be detected in a shorter time compared to the prior art described in Patent Document 1. The reason will be described below.

In the prior art, when the switching of the detection signal of the magnetic sensor is detected during the first period after exciting the stator coil, it is determined that the rotor is rotating in the forward rotation direction. On the other hand, if the detection signal switching is not detected during the first period, it is determined that the rotor is rotating in the reverse direction. This first period is set to a time sufficient to rotate over a mechanical angle of at least 360 ° / number of magnetic poles from when the rotor is stationary. That is, when the number of magnetic poles of the rotor is 4, the maximum rotation angle (mechanical angle) of the rotor from when the stationary rotor starts to rotate until the rotation direction is detected is 90 °.

On the other hand, in this embodiment, when the mechanical rotation period of the rotor 2 is a mechanical angle of 360 °, the number of magnetic poles of the rotor 2 is 4, so that one cycle of each position detection signal is a mechanical angle of 180 °. Become. Since the phase difference between the position detection signal SA and the position detection signal SB is 45 ° (mechanical angle), any one of the position detection signals is switched at every mechanical angle of 45 ° within the one cycle. Therefore, the rotation angle of the rotor 2 from when the stationary rotor 2 starts to rotate until the rotation direction is detected is 45 ° at the maximum. It can be seen that the rotation angle of the rotor 2 until the rotation direction is detected is less than half compared to the above-described conventional technology. Thereby, the time from when the rotor 2 starts to rotate until the rotation direction is detected can be reduced to less than half. As a result, the single-phase AC motor can be started up in a short time.

(Arrangement of magnetic sensor)
Next, the arrangement of the

magnetic sensors

24A and 24B will be described. In the following description, it is assumed that the magnetic sensor 24A is disposed at a position where the rotation angle (mechanical angle) of the rotor 2 is 0 °, as in FIG. The number of magnetic poles of the rotor 2 is P. A suitable position of the magnetic sensor 24B in this state will be described.

In the present embodiment, as shown in the waveform diagram of FIG. 5, by providing a phase difference between the position detection signal SA and the position detection signal SB, the timing at which the position detection signal SA is switched, and the position detection The timing at which the signal SB is switched is different. In this way, the rotation direction of the rotor 2 can be detected based on the transition of the combination of the position detection signals SA and SB caused by the rotation of the rotor 2.

In order to change the switching timing between the position detection signal SA and the position detection signal SB, at least the magnetic sensor 24B needs to be arranged at a position other than the position satisfying “180 × n / (P / 2)”. (N is an integer of 1 or more and P or less). The position satisfying “180 × n / (P / 2)” corresponds to the timing at which the position detection signal SA is switched. Therefore, the rotational direction of the rotor 2 can be detected by disposing the magnetic sensor 24B at a position other than the position.

More preferably, the magnetic sensor 24B is spaced apart from the magnetic sensor 24A by an angular interval of “180 × {1+ (2n−1)} / P” on the same circle centered on the rotation axis 1 of the rotor 2. It is. If it does in this way, in addition to the detection of the rotation direction of the rotor 2, the detection accuracy of the magnetic pole position of the rotor 2 can be improved.

For example, when the number of magnetic poles P = 4, the magnetic sensor 24B is preferably disposed at any position of 45 °, 135 °, 225 °, and 315 °. The example of FIG. 4 shows a case where the magnetic sensor 24B is disposed at a 45 ° position.

In this manner, a phase difference of 45 ° or 135 ° can be provided between the position detection signal SA and the position detection signal SB. A phase difference of 45 ° mechanical angle corresponds to a quarter cycle of the position detection signals SA and SB. The phase difference with a mechanical angle of 135 ° corresponds to 3/4 period of the position detection signals SA and SB. Therefore, the switching timing between the position detection signal SA and the position detection signal SB is different by a quarter period.

According to this, the controller 16 detects the switching of the position detection signal four times in total every ¼ period while the rotor 2 makes one rotation (mechanical angle 360 °). Therefore, it is possible to detect the magnetic pole position of the rotor 2 at a finer timing than when a single position detection signal is used. As a result, the magnetic pole position detection accuracy can be increased.

(Details of startup processing)
Next, details of the activation process according to the present embodiment will be described with reference to FIGS.

FIG. 7 is a diagram for explaining a flow of activation processing for activating the rotor 2 in the first direction (forward rotation direction). FIG. 7A shows the flow of the starting process when the rotor 2 starts to rotate in the normal rotation direction from the initial state due to the excitation of the stator 3. FIG. 7B shows a processing flow when the rotor 2 starts to rotate in the reverse rotation direction from the initial state due to the excitation of the stator 3. FIG. 8 is a timing chart corresponding to the flow of the startup process shown in FIG. FIG. 9 is a timing chart corresponding to the flow of the activation process shown in FIG.

7A and 7B, the rotating magnetic field generated in the stator 3 is represented by a region divided into four parts with the rotor 2 as the center. The arrangement of the

magnetic sensors

24A and 24B is the same as that shown in FIG. Further, for ease of explanation, the first state applied to the stator 3 (stator coil) while the initial state of the rotor 2 is made common between FIG. 7 (a) and FIG. 7 (b). The polarity of the motor voltage Vm having a different polarity is made different.

7A, assume that the rotor 2 is in an initial state at time tA. In the initial state, the rotor 2 is stationary at a position shifted from 0 ° by a predetermined angle in the forward rotation direction. Thereby, the magnetic force generated by the excitation of the stator 3 can be converted into the rotational force of the rotor 2. Such a stationary state can be realized, for example, by adjusting the gap between the teeth of the stator 3 and the rotor.

In the example of FIG. 7, the initial state of the rotor 2 is the state [1] of FIG. Therefore, in the

magnetic sensors

24A and 24B, (SA, SB) is (0, 1) (see FIG. 8).

7A and 8, in the initial state, activation processing unit 30 applies motor voltage Vm having the first polarity from inverter 14 to the stator coil. In FIG. 7A, the “first polarity” is a positive polarity. Activation processing unit 30 controls inverter 14 such that semiconductor switching elements Q1, Q4 are turned on and semiconductor switching elements Q2, Q3 are turned off. Accordingly, a positive DC voltage (+ Vdc) is applied to the stator coil as the motor voltage Vm.

When the stator 3 is excited by receiving the motor voltage Vm (= + Vdc), the rotor 2 rotates in the forward rotation direction (clockwise) by the magnetic force generated between the magnetic field generated in the teeth of the stator 3 and the magnetic pole of the rotor 2. Begin to.

At time tB, when the rotation angle of the rotor 2 reaches 45 °, the position detection signal SB of the magnetic sensor 24B is switched from “1” to “0” as shown in FIG. The activation processing unit 30 detects that the rotation direction of the rotor 2 is the forward rotation direction based on the first switching of the position detection signal SB after the rotor 2 starts to rotate.

When it is detected that the rotation direction of the rotor 2 is the normal rotation direction, the activation processing unit 30 determines that the rotor 2 is rotating in a desired rotation direction. Therefore, at time tC, activation processing unit 30 supplies motor voltage Vm, which is a single-phase AC voltage, from inverter 14 to the stator coil.

Note that the polarity of the motor voltage Vm at the time tC is the same as the first polarity in order to continuously rotate the rotor 2 in the forward rotation direction. Thereby, after time tC, the rotor 2 rotates in the normal rotation direction by receiving the motor voltage Vm and generating a rotating magnetic field in the stator 3.

On the other hand, in FIG. 7B, the first polarity is a negative polarity. Activation processing unit 30 controls inverter 14 such that semiconductor switching elements Q2 and Q3 are turned on and semiconductor switching elements Q1 and Q4 are turned off. As a result, a negative DC voltage (−Vdc) is applied to the stator coil as the motor voltage Vm.

Referring to FIG. 7B and FIG. 9, at time tA, start-up processing unit 30 applies a negative polarity motor voltage Vm (= −Vdc) from inverter 14 to the stator coil. In FIG. 7B, since the polarity of the motor voltage Vm is different from that in FIG. 7A, the magnetic field generated in the teeth of the stator 3 is reversed with respect to FIG. 7A. As a result, the rotor 2 starts to rotate in the reverse direction (counterclockwise).

When the rotation angle of the rotor 2 becomes 0 ° at time tB, the position detection signal SA of the magnetic sensor 24A is switched from “0” to “1” as shown in FIG. The activation processing unit 30 detects that the rotation direction of the rotor 2 is the reverse rotation direction based on the first switching of the position detection signal SA after the rotor 2 starts to rotate.

When it is detected that the rotation direction of the rotor 2 is the reverse rotation direction, the activation processing unit 30 determines that the rotor 2 is rotating in a direction opposite to the desired rotation direction. Therefore, the activation processing unit 30 temporarily stops the application of the motor voltage Vm to the stator coil by controlling the inverter 14 so that the semiconductor switching elements Q1 to Q4 are all turned off.

Since the application of the motor voltage Vm is stopped, the magnetic field generated in the stator 3 disappears, so the rotor 2 tries to return to the initial state. Therefore, the rotor 2 starts to rotate in the normal rotation direction. As a result, at time tC, the rotation angle of the rotor 2 again becomes 0 °, and the position detection signal SA is switched from “1” to “0”.

When the switching of the position detection signal SA is detected at time tC, the activation processing unit 30 applies the second polarity motor voltage Vm (that is, the positive polarity motor voltage Vm) from the inverter 14 to the stator coil. ) Is applied. As a result, a magnetic field similar to that shown in FIG.

At time tD, when the rotor 2 returns to the initial state, the rotor 2 continues to rotate in the normal rotation direction due to the magnetic force generated between the magnetic field generated in the teeth of the stator 3 and the magnetic poles of the rotor 2. At time tE, when the rotation angle of the rotor 2 reaches 45 °, the position detection signal SB of the magnetic sensor 24B is switched from “1” to “0” as shown in FIG. The start processing unit 30 detects that the rotation direction of the rotor 2 is the forward rotation direction based on the first switching of the position detection signal SB after the polarity of the motor voltage Vm is reversed to the second polarity. .

When it is detected that the rotation direction of the rotor 2 is the normal rotation direction, the activation processing unit 30 determines that the rotor 2 is rotating in a desired rotation direction. Therefore, at time tE, activation processing unit 30 applies motor voltage Vm, which is a single-phase AC voltage, from inverter 14 to the stator coil. At this time, the activation processing unit 30 continues to rotate the rotor 2 in the forward rotation direction, so that the polarity of the motor voltage Vm at the time tE is the same as the second polarity. Thereby, after time tC, the rotor 2 rotates in the forward direction by receiving the motor voltage Vm and generating a rotating magnetic field in the stator 3.

As described above, when the activation processing unit 30 applies the motor voltage Vm having the first polarity to the stator coil of the single-phase AC motor 10 at time tA, the rotation angle of the rotor 2 from time tA is 45 °. The rotation direction of the rotor 2 can be detected at time tB less than.

In the example of FIG. 7A, since the rotation direction detected at time tB is the normal rotation direction, the activation time is the time from time tA to time tB. In the case of FIG. 7A, the rotor 2 can be driven in the normal rotation direction immediately after time tB.

On the other hand, in the example of FIG. 7B, since the rotation direction of the rotor 2 detected at time tB is the reverse rotation direction, the polarity of the motor voltage Vm is reversed to the second polarity at time tC. Therefore, at time tE when the rotation angle of the rotor 2 from time tC becomes 45 °, it can be detected that the rotation direction of the rotor 2 is the normal rotation direction. That is, in the case of FIG. 7B, the activation time is the time from time tA to time tE. Thereby, after time tE, the rotor 2 can be driven in the forward rotation direction.

As described above, according to the present embodiment, the rotation direction of the rotor 2 can be detected in a short time after the rotation of the rotor 2 starts. As a result, the activation time can be shortened.

In addition, although illustration is omitted, in the single-phase AC motor 10, when the abnormality that the rotor 2 does not rotate has occurred, the position detection signals SA and SB are not switched even when the motor voltage Vm is applied. Can happen. In such a case, if the motor voltage Vm is continuously applied, the stator coil may be overheated due to the direct current flowing through the stator coil. As a result, the stator 3 may be burned out.

In order to protect the stator 3 from overheating, for example, a temperature detection element (such as a thermistor) is installed around each semiconductor switching element of the inverter 14 to detect overheating and stop the operation of the inverter 14. Can do. Alternatively, when the state in which the position detection signals SA and SB are not switched continues for a predetermined time, a method of stopping the operation of the inverter 14 can be adopted.

FIG. 10 is a flowchart for illustrating a startup process according to the present embodiment.
Referring to FIG. 10, when starting single-phase AC motor 10, controller 16 first receives position detection signals SA and SB of

magnetic sensors

24A and 24B when rotor 2 is stationary in step S01. get. Thereby, the initial state of the rotor 2 can be grasped.

In step S02, the controller 16 applies the motor voltage Vm having the first polarity to the stator coil 6 of the single-phase AC motor 10. As a result, the rotor 2 of the single-phase AC motor 10 is started.

If the position detection signals SA and SB of the

magnetic sensors

24A and 24B when the rotor 2 is rotating are acquired in step S03, the controller 16 detects the position detection signal when the rotor 2 is stationary in step S04. Based on SA and SB and position detection signals SA and SB when the rotor 2 is rotating, the rotation direction of the rotor 2 is detected. Here, the controller 16 can detect the rotation direction of the rotor 2 by grasping the initial state of the rotor 2 and the next transition state from the position detection signals SA and SB.

In step S05, the controller 16 determines whether or not the rotation direction of the rotor 2 is the first rotation direction. When the rotation direction of the rotor 2 is the first rotation direction (YES in S05), the controller 16 proceeds to step S05 and applies the motor voltage Vm, which is a single-phase AC voltage, to the stator coil 6. Thereby, the rotor 2 is driven in the first rotation direction.

On the other hand, when the rotation direction of the rotor 2 is not the first rotation direction (NO in S05), the controller 16 proceeds to step S07 and turns off all the semiconductor switching elements Q1 to Q4 of the inverter 14. Thus, application of the motor voltage Vm to the stator coil 6 is stopped. Thereby, the rotor 2 starts to rotate in the first rotation direction so as to return to the initial state.

Subsequently, the controller 16 applies the motor voltage Vm having the second polarity to the stator coil 6 in step S08. Further, returning to step S05, the controller 16 detects the rotation direction of the rotor 2 based on the position detection signals SA and SB. If it is determined in step S05 that the rotation direction of the rotor 2 is the first rotation direction, the controller 16 applies a motor voltage Vm, which is a single-phase AC voltage, to the stator coil 6 in step S06. Thus, the rotor 2 is driven in the first rotation direction.

(Application example)
Next, an application example of the control device for the single-phase AC motor according to the present embodiment will be described. Below, the example (refer FIG. 11 and FIG. 12) which applied the control apparatus 100 shown in FIG. 1 to a vacuum cleaner, and the example (refer FIG. 13) which applied the control apparatus 100 to the hand dryer are demonstrated.

(1) Vacuum cleaner FIG. 11 is a schematic configuration diagram of a vacuum cleaner to which the control device 100 shown in FIG. 1 is applied.

Referring to FIG. 11, a vacuum cleaner 61 according to the present embodiment includes an extension pipe 62, a suction port body 63, an electric blower 64, a dust collection chamber 65, an operation unit 66, a power supply 12, and a sensor. 68. Electric blower 64 includes single-phase AC motor 10 and control device 100 shown in FIG.

The electric blower 64 drives the single-phase AC motor 10 as a blower motor. When the single-phase AC motor 10 is driven to rotate, suction air is generated. Due to the suction air, dust on the surface to be cleaned (not shown) is sucked into the suction port body 63 together with air.

The air containing dust is conveyed to the dust collection chamber 65 through the extension pipe 62. Dust in the air is collected in the dust collection chamber 65. The air in which the dust is collected passes through a filter (not shown) and then reaches the electric blower 64. Thereafter, the air passes through the internal passage and is discharged to the outside from an exhaust port (both not shown).

In the example of FIG. 11, the power supply of the control device 100 is the same as the power supply 12 of the vacuum cleaner 61. Further, the controller 16 of the control device 100 is configured to be able to control the operation of the entire vacuum cleaner 61.

The operation unit 66 includes a power switch 66a and an acceleration switch 66b (see FIG. 12). The power switch 66 a is a switch for switching between power supply and shut-off from the power supply 12 to each part of the vacuum cleaner 61. The acceleration switch 66b is a switch for accelerating the single-phase AC motor 10 in the electric blower 64 from a low speed rotation speed to a steady rotation speed. The low-speed rotation speed refers to a rotation speed that is 1/10 or less of the steady-state rotation speed. For example, when the steady rotation speed is 100,000 rpm, the low speed rotation speed is 10,000 rpm or less.

When the acceleration switch 66b is turned on by the user while the single-phase AC motor 10 is driven at a low rotational speed, the control device 100 causes the rotational speed of the single-phase AC motor 10 to reach a steady rotational speed. The variable speed control of the rotational speed described in FIG. 3 is executed. In this variable speed control of the rotational speed, the acceleration (hereinafter also referred to as “acceleration rate”) until the rotational speed reaches the steady rotational speed from the low rotational speed can be adjusted.

Sensor 68 detects the movement of the vacuum cleaner 61 or the movement of a person. As the sensor 68, for example, a gyro sensor or a human sensor can be used. A detection signal from the sensor 68 is input to the controller 16.

Next, the operation of the electric blower 64 (single-phase AC motor 10) in the vacuum cleaner 61 will be described with reference to FIG. FIG. 12 is a block diagram showing a control configuration of the electric blower 64.

First, when the power switch 66a is turned on by the user, the main circuit of the vacuum cleaner 61, the control device 100, the sensor 68, and the like are activated by receiving power from the power source 12.

Sensor 68 is, for example, a gyro sensor. The sensor 68 detects the movement of the electric vacuum cleaner 61 and outputs a detection signal to the controller 16 of the control device 100.

Specifically, the gyro sensor can detect the movement of the vacuum cleaner 61 that occurs when the vacuum cleaner 61 is used by being attached to the vacuum cleaner 61. The main body always moves immediately before using the vacuum cleaner 61. By detecting the movement immediately before use by the sensor 68, the electric blower 64 (single-phase AC motor 10) can be started before the acceleration switch 66b is turned on, as described below.

The controller 16 starts the single-phase AC motor 10 using the detection signal of the sensor 68 as a trigger, and drives the single-phase AC motor 10 at a low speed. In addition, when starting the single phase alternating current motor 10, the controller 16 performs the starting process mentioned above. Thereby, the rotor 2 of the single-phase AC motor 10 can be started in a desired rotation direction (first rotation direction) in a short time. When the rotor 2 is activated, the controller 16 accelerates the single-phase AC motor 10 to a low speed.

When the acceleration switch 66b is turned on during driving at a low rotational speed, the controller 16 accelerates the single-phase AC motor 10 to a steady rotational speed. When the acceleration switch 66b is turned on before the power switch 66a, when the power switch 66a is turned on, the controller 16 immediately turns on the single-phase AC motor 10 after the start-up process. Accelerate to rotational speed.

When the acceleration switch 66b is turned off during driving at the normal rotation speed, the controller 16 drives the single-phase AC motor 10 by decelerating it to a low speed without stopping the driving of the single-phase AC motor 10. to continue. By continuing to drive at a low rotational speed, it is possible to prevent the dust collected in the dust collection chamber 65 from being discharged from the suction port 63 through the extension pipe 62.

As described above, in electric vacuum cleaner 61 according to the present embodiment, when power switch 66a is turned on, single-phase AC motor 10 is driven at a low rotational speed using the detection signal of sensor 68 as a trigger. Thereby, when the user actually uses the vacuum cleaner 61, the time from when the acceleration switch 66b is turned on until the single-phase AC motor 10 reaches the steady rotational speed can be shortened.

For example, the time from when the power supply is started until the single-phase AC motor 10 reaches a low speed (for example, 2000 rpm) is 1 second, and from the low speed to the steady speed (for example, 100,000 rpm). Assume that the time to reach is 0.4 seconds. In this case, it takes 1.4 seconds from the start of power supply until the single-phase AC motor 10 reaches the steady rotational speed. In the present embodiment, when the acceleration switch 66b is turned on, the single-phase AC motor 10 is already driven at the low speed. Therefore, when the user actually uses the vacuum cleaner 61, the single-phase AC motor 10 can reach the steady rotational speed in only 0.4 seconds after the acceleration switch 66b is turned on.

On the other hand, in order to start the single-phase AC motor 10, it is necessary to generate a larger torque than when the single-phase AC motor 10 is rotating in a steady state. Therefore, it is necessary to flow a large motor current through the single-phase AC motor 10. However, when the motor current is increased, the power consumption increases and the amount of heat generated in the components including the single-phase AC motor 10 and the power source 12 also increases. For example, when the power source 12 is a power storage device such as a secondary battery, the continuous operation time of the vacuum cleaner 61 is shortened by increasing the power consumption. In addition, an increase in the amount of heat generated by the component may impair the reliability of the component.

In order to solve such a problem, it is effective to reduce the acceleration rate when starting the single-phase AC motor 10. By reducing the acceleration rate, a steep rise in the motor current can be suppressed, so that it is possible to prevent an increase in power consumption and the amount of heat generated by components.

In the present embodiment, the startup time can be shortened by performing the above startup process. Therefore, it is possible to prevent the time required for starting the single-phase AC motor 10 from being extended due to the reduction of the acceleration rate at the time of starting.

Further, according to the present embodiment, since the variable speed control of the single-phase AC motor 10 is executed using the two position detection signals SA and SB, the detection accuracy of the magnetic pole position of the rotor 2 can be improved. As a result, the responsiveness of variable speed control can be improved. Therefore, when the variable rate is lowered, it is possible to suppress the occurrence of vibration in the single-phase AC motor 10 due to the fluctuation of the output torque of the single-phase AC motor 10.

In the vacuum cleaner 61, even when the single-phase AC motor 10 is accelerated from a low speed to a steady speed, power consumption due to acceleration can be suppressed by reducing the acceleration rate. Also at this time, since the responsiveness of the variable speed control is good, the occurrence of vibration in the single-phase AC motor 10 can be suppressed.

(2) Hand dryer FIG. 13 is a schematic configuration diagram of a hand dryer to which the control device 100 shown in FIG. 1 is applied. Hand dryer 70 according to the present embodiment is a device for drying hands by applying dry air to hands wet with water after the user has washed their hands.

Referring to FIG. 13, hand dryer 70 according to the present embodiment includes casing 71, hand insertion portion 72, water receiving portion 73, drain container 74, cover 76, sensor 77, and intake port 78. Is provided.

The casing 71 forms a concave space for inserting a user's hand, that is, a hand insertion portion 72. The water receiving part 73 receives water droplets splashed from the wet hand of the user. The drain container 74 is detachably attached to the casing 71 and accumulates water droplets received by the water receiving portion 73. The cover 76 is coupled to the casing 71 and constitutes the front surface of the hand dryer 70.

In the casing 71, an electric blower (not shown) and a sensor 77 are mounted. The electric blower includes a single-phase AC motor 10 and a control device 100 shown in FIG. The controller 16 of the control device 100 is configured to be able to control the operation of the entire hand dryer 70.

The electric blower drives the single-phase AC motor 10 as a blower motor. When the single-phase AC motor 10 is driven to rotate, dry air is generated. The dry air is blown out toward a manual insertion portion 72 from a blower opening (not shown) provided in the casing 71.

Sensor 77 detects that the user has approached hand dryer 70. The sensor 77 further detects that the user's hand has been inserted into the hand insertion portion 72. As the sensor 77, for example, a human sensor can be used. A detection signal of the sensor 77 is input to the controller 16 of the control device 100.

Next, the operation of the electric blower (single-phase AC motor 10) in the hand dryer 70 will be described.

The electric blower is in a standby state in which the driving of the single-phase AC motor 10 is stopped when the user is not approaching the hand dryer 70. In the standby state of the electric blower, the sensor 77 detects whether or not a person has approached the hand dryer 70. When detecting that a person has approached the hand dryer 70, the sensor 77 outputs a detection signal to the controller 16 of the control device 100.

The controller 16 starts the single-phase AC motor 10 using the detection signal of the sensor 77 as a trigger, and drives the single-phase AC motor 10 at a low speed. In addition, when starting the single phase alternating current motor 10, the controller 16 performs the starting process mentioned above. Thereby, the rotor 2 of the single-phase AC motor 10 can be started in a desired rotation direction (first rotation direction) in a short time. When the rotor 2 is activated, the controller 16 accelerates the single-phase AC motor 10 to a low speed.

When the sensor 77 detects that the user's hand has been inserted into the hand insertion portion 72 during driving at a low rotational speed, the controller 16 accelerates the single-phase AC motor 10 to a steady rotational speed.

When the user's hand is removed from the manual insertion portion 72 during driving at the steady rotation speed, the controller 16 rotates the single-phase AC motor 10 at a low speed for a predetermined time without stopping the driving of the single-phase AC motor 10. Continue to drive at a reduced speed. When the next user's hand is inserted into the hand insertion unit 72 during the predetermined time, the controller 16 accelerates the single-phase AC motor 10 to a constant rotational speed again. On the other hand, when it is not detected that a person has approached the hand dryer 70 during the predetermined time, the controller 16 stops the single-phase AC motor 10 and puts the electric blower in a standby state.

In the hand dryer 70 according to the present embodiment, the single-phase AC motor 10 is driven at a low rotational speed with a detection signal indicating that the user has approached the hand dryer 70 as a trigger. Thereby, when a user's hand is inserted in the hand insertion part 72, the time until the single-phase AC motor 10 reaches a steady rotational speed can be shortened.

Further, similarly to the electric vacuum cleaner 61 shown in FIG. 11, the hand dryer 70 also requires a large motor current in order to start the single-phase AC motor 10. A large motor current may cause an increase in power consumption and an increase in the amount of heat generated by components. According to the present embodiment, the startup time can be shortened by performing the startup process. Thereby, since it can suppress that a big motor current flows for a long time, as a result, the increase in the power consumption and the emitted-heat amount at the time of starting can be suppressed.

In the above embodiment, the configuration in which the control device 100 of the single-phase AC motor 10 according to the present embodiment is applied to a vacuum cleaner and a hand dryer has been described. It can be widely applied to products using a phase AC motor as a drive source. For example, incinerator, pulverizer, dryer, dust collector, printing machine, cleaning machine, confectionery machine, tea making machine, woodworking machine, plastic extruder, corrugated board machine, packaging machine, hot air generator, OA equipment, general air supply / exhaust air The present invention can be applied to products including an electric blower.

The present invention includes any combination of a plurality of embodiments, modification of any component included in any embodiment, or any combination included in any embodiment within the scope described in the claims. The components of can be omitted.

It should be considered that the embodiments disclosed herein are illustrative and non-restrictive in every respect. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

1 rotating shaft, 2 rotor, 3 stator, 4 stator core, 5 teeth, 6 stator coil, 10 single phase AC motor, 12 power supply, 14 inverter, 16 controller, 18 ADC, 20 gate driver, 22 current sensor, 24A, 24B magnetism Sensor, 30 Start processing unit, 32 Speed control unit, 34 Current control unit, 36 PWM control unit, 61 Vacuum cleaner, 62 Extension pipe, 63 Suction port, 64 Electric blower, 65 Dust collection chamber, 66 Operation unit, 66a Power switch, 66b acceleration switch, 68, 77 sensor, 70 hand dryer, 71 casing, 72 manual insertion part, 73 water receiving part, 74 drain container, 76 cover, 78 intake, 100 control device, Q1-Q4 semiconductor switching element , D1-D4 da Ord.

Claims

A control device for a single-phase AC motor,
The single-phase AC motor is
A rotor provided with a plurality of magnetic poles;
A stator for generating a rotating magnetic field,
The control device includes:
An inverter configured to apply a driving voltage of the single-phase AC motor to the stator;
First and second magnetic sensors for detecting a magnetic pole position of the rotor;
A controller configured to control the inverter based on detection signals of the first and second magnetic sensors;
The first and second magnetic sensors are arranged at positions spaced apart from each other along the rotation direction of the rotor,
The controller is configured to execute a starting process for starting the rotor in a stationary state in a first direction;
In the startup process, the controller
A first polarity voltage is applied to the stator from the inverter to drive the rotor;
Detecting the rotation direction of the rotor based on the detection signals of the first and second magnetic sensors when the rotor is in the stationary state and when the rotor is rotating; and
A single-phase AC motor that reverses the first polarity of the voltage to a second polarity when the rotation direction of the rotor is detected to be a second direction opposite to the first direction. Control device.
The detection signal is configured to switch a logic level between two values according to the magnetic pole position,
The controller first applies the drive voltage having the first polarity to the stator, and then at a timing at which the logic level of the detection signal of one of the first and second magnetic sensors is switched first. The control device for a single-phase AC motor according to claim 1, wherein the rotation direction of the rotor is detected.
3. The single-phase AC motor according to claim 2, wherein the detection signal of the first magnetic sensor and the detection signal of the second magnetic sensor are shifted from each other by a quarter cycle in the timing at which the logic level is switched. Control device.
When the number of magnetic poles of the rotor is P and n is an integer between 1 and P, the first magnetic sensor and the second magnetic sensor are on the same circle with the rotation axis of the rotor as the center. , 180 × {1+ (2n−1)} / P. The control device for a single-phase AC motor according to claim 1, which is arranged at an angular interval of 180 × {1+ (2n−1)} / P.
A current sensor for detecting a current flowing through the stator;
The controller according to any one of claims 1 to 4, wherein the controller executes variable control of the rotational speed of the rotor based at least on the detection signals of the first and second magnetic sensors and the detection signal of the current sensor. The control apparatus of the single phase alternating current motor described in the term.