Method and device for controlling permanent magnet motor, and ceiling fan

Abstract

In a method for controlling a permanent magnet motor provided with a converter unit (3) for converting an AC input voltage into a DC voltage, an inverter unit (5) for converting the DC voltage into an AC voltage, a permanent magnet motor (6), and a control unit (MCU (8)) for controlling the inverter unit in order to control the rotational speed of the permanent magnet motor (6), the control unit detects the AC input voltage, and controls the inverter unit in order to control the rotational speed of the permanent magnet motor (6). The amount of change in the peak value or the effective value of the AC input voltage is measured, and when the amount of change is a negative value and the absolute value of the amount of change exceeds a predetermined threshold value, the rotational speed of the permanent magnet motor (6) is suppressed. When suppressing the rotational speed of the permanent magnet motor (6), control is performed on the basis of a table indicating a predetermined relationship between the AC input voltage and the rotational speed.

Description

Technical Field

[0001] The present invention relates to a control method for a permanent magnet motor, a control device, and a ceiling fan. Background Art

[0002] Conventionally, ceiling fans using simple-structured and inexpensive induction motors have been widely used. However, in recent years, devices using high-efficiency and energy-saving permanent magnet motors have become mainstream.

[0003] The rotation speed of an existing induction motor is determined according to the magnitude of an AC input power supply. Therefore, to adjust the rotation speed, it is necessary to use a regulator switch or the like to lower the voltage of the AC input power supply. On the other hand, a permanent magnet motor can convert the AC input power supply into DC on the converter side and into AC of a desired period on the inverter side to control the rotation speed.

[0004] Patent Document 1 discloses a ceiling fan including: an EC motor (Electronically Commutated Motor) for driving a plurality of fan blades; and a motor controller configured to determine the rotor position using a back electromotive force EMF (Electro-Motive Force) and configured to apply pressure to the motor according to the rotor position and a predetermined command.

[0005] Prior Art Documents

[0006] Patent Documents

[0007] Patent Document 1: Japanese Patent Application Laid-Open No. 2013-526260 Summary of the Invention

[0008] Problems to be Solved by the Invention

[0009] When considering replacement from an induction motor to a permanent magnet motor, a structure that enables speed adjustment using a permanent magnet motor while a regulator used in the induction motor is installed is required.

[0010] Therefore, when a permanent magnet motor is used in a state where a regulator is used, in a country or region where the AC input changes rapidly, the supply power is unstable, and thus there is a problem of becoming an uncontrollable state.

[0011] The present invention is a solution proposed to solve the above problems, and an object thereof is to provide a control method for a permanent magnet motor, a control device, and a ceiling fan that can be appropriately controlled even when the AC input voltage is unstable.

[0012] Means for Solving the Problems

[0013] To achieve the above object, the present invention provides a control method for a permanent magnet motor, the permanent magnet motor comprising: a converter unit that converts an AC input voltage into a DC voltage; an inverter unit that converts the DC voltage into an AC voltage; a permanent magnet motor; and a control unit that controls the inverter unit to control the rotational speed of the permanent magnet motor. The control method of the permanent magnet motor is characterized in that the control unit detects the AC input voltage, measures the change amount of the peak value or the effective value of the AC input voltage, and controls the rotational speed of the permanent magnet motor when the change amount is a negative value and the absolute value of the change amount exceeds a predetermined threshold value.

[0014] Other aspects of the present invention will be described in the embodiments described hereinafter.

[0015] Effects of the Invention

[0016] According to the present invention, appropriate control can be achieved even when the AC input voltage is unstable. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1A FIG. is a diagram showing the overall structure of a ceiling fan using a permanent magnet motor.

[0018] Figure 1B FIG. is a diagram showing the relationship between the AC input voltage peak value and the frequency command value.

[0019] Figure 2A FIG. is a diagram showing an example of current limiting using a regulator as a current limiter.

[0020] Figure 2B FIG. is a diagram showing the time change of the control frequency and the input voltage peak value when there is a power shortage.

[0021] Figure 3 FIG. is a diagram showing an outline of the control method of the permanent magnet motor according to the first embodiment.

[0022] Figure 4 FIG. is a diagram showing the relationship between the AC input voltage peak value and the control frequency according to the first embodiment.

[0023] Figure 5 FIG. is a flowchart showing the speed control process according to the first embodiment.

[0024] Figure 6 FIG. is a diagram showing an example of control applying the speed control process according to the first embodiment.

[0025] Figure 7A FIG. is a diagram showing the time change of the control frequency and the input voltage peak value before applying the first embodiment.

[0026] Figure 7B It is a diagram showing the time change of the control frequency and the peak input voltage after applying this embodiment.

[0027] Figure 8A It is a diagram showing the relationship between the peak AC input voltage and the frequency command value in the second embodiment (AC200Vrms).

[0028] Figure 8B It is a diagram showing the relationship between the peak AC input voltage and the frequency command value in the second embodiment (AC220Vrms).

[0029] Figure 8C It is a diagram showing the relationship between the peak AC input voltage and the frequency command value in the second embodiment (AC240Vrms). Detailed Embodiment

[0030] Hereinafter, a mode for implementing the present invention (hereinafter referred to as "embodiment") will be described with appropriate reference to the accompanying drawings.

[0031] <Existing Problems>

[0032] First, the problems when initially installing a permanent magnet motor on an existing power supply device will be described.

[0033] In a certain country or region, the system voltage supplied to users is 220V - 240V, but currently the power supply is in short supply and power outages occur frequently. In such a country or region, unstable voltage becomes a problem. The voltage tends to be low during the morning and night when the electrical demand is high, and conversely, the voltage becomes abnormally high during the day and other times. In addition, even during the same daytime period, it is normal for the voltage to fluctuate frequently. In this embodiment, a control method for a permanent magnet motor that can be appropriately controlled even when the AC input voltage is unstable is proposed in such a country or region.

[0034] Figure 1A It is a diagram showing the overall structure of the ceiling fan 7 using the permanent magnet motor 6. Figure 1B It is a diagram showing the relationship between the peak AC input voltage and the frequency command value. Figure 2A It is a diagram showing an example of current limiting using a regulator as a current limiter. Figure 2B It is a diagram showing the time change of the control frequency and the peak input voltage during power shortage.

[0035] Used Figure 1AThe ceiling fan 7 of the permanent magnet motor 6 shown has: a converter section 3 that converts an AC input voltage into a DC voltage; a capacitor 4; an inverter section 5 that converts the DC voltage into an AC voltage; a permanent magnet motor 6; and an MCU 8 (control section) that controls the inverter section in order to control the rotational speed of the permanent magnet motor. A ceiling fan 7 is connected to the rotating shaft of the permanent magnet motor 6. As a power supply device, since it is in a state where the existing induction motor has been removed, it has a regulator 2, which is a current limiter with variable resistance, that takes the AC power supply 1 as an input. In the ceiling fan that uses the permanent magnet motor 6, power is supplied via the regulator 2. The MCU 8 detects the AC voltage via a voltmeter 9 and issues a speed control command for the permanent magnet motor 6 to the inverter section 5. In addition, MCU is the abbreviation of Micro Controller Unit.

[0036] Here, the resistance of the regulator 2 varies according to each switch. The ceiling fan 7 with the structure using the permanent magnet motor 6 determines the speed based on the input voltage value detected by the MCU 8. In a state where the user side has not notified the MCU 8 side of the specified switch of the regulator 2, when maintaining speed control, when the detected AC input voltage peak value is high and the power supplied to the motor is limited by the current limit of the regulator 2, the balance of power consumption between the power supply side and the motor side collapses, the input voltage drops suddenly, and it falls into a state where the motor cannot be controlled. The top priority is to solve problems such as the narrowing of the motor control drive range.

[0037] In Figure 2A the switch 21 of the regulator 2, it becomes a dial type that is off (OFF) with SW1 to 5. Referring to the relationship 22 between the SW and the resistance, the resistance value of SW1 is set to be the highest and the resistance value of SW5 is smaller.

[0038] Figure 1B shows the relationship between the AC input voltage peak value and the frequency command value. The MCU 8 sets the maximum rotational speed, that is, the frequency command value F max , in the case of AC200Vrms and SW5. Additionally, in the case of AC200Vrms and SW1, it sets the minimum rotational speed, that is, the frequency command value F min . Even when the AC power supply 1 rises sharply due to the instability of the system voltage, it is set to maintain the maximum rotational speed. That is, in the case of AC240Vrms and SW5, it sets the maximum rotational speed, that is, the frequency command value F max , and additionally, even in the case of AC240V effective value and SW1, it is also set to the maximum rotational speed, that is, the frequency command value F max . This setting example is shown as Figure 2A the frequency command value 23.

[0039] Normally, the device determines the set value while maintaining the system voltage. Therefore, in the case where the AC power supply 1 suddenly rises (for example, from AC200Vrms to 240Vrms), the MCU8, as Figure 2B shown, from the current frequency towards the frequency target, (1) the rotational speed increases, (2) the power balance between the input and output collapses at the part where power supply is insufficient, and (3) if power cannot be supplied, the input voltage drops suddenly. As a result, there is a problem that the motor cannot be controlled.

[0040] 《First Embodiment》

[0041] In this embodiment, a solution to the above problem is shown.

[0042] Figure 3 It is a diagram showing an outline of the control method of the permanent magnet motor 6 of the first embodiment. In this embodiment, a control for achieving the balance between the power supply on the converter unit 3 side and the power demand on the inverter unit 5 side is proposed.

[0043] The control method of the permanent magnet motor 6 of this embodiment is a control method of a permanent magnet motor having a converter unit 3 that converts an AC input voltage into a DC voltage, a capacitor 4, an inverter unit 5 that converts the DC voltage into an AC voltage, a permanent magnet motor 6, and an MCU8 (control unit) that controls the inverter unit 5 to control the rotational speed of the permanent magnet motor 6. The MCU8 detects the AC input voltage via a voltmeter 9, measures the change amount of the peak value or the effective value of the AC input voltage, and limits the rotational speed to a speed at which the motor can be controlled in the case of power shortage. In addition, the control device 10 includes: an inverter unit 5 that converts the DC voltage into an AC voltage; an MCU8 that controls the inverter unit 5 to control the rotational speed of the permanent magnet motor 6; and a voltmeter 9.

[0044] As a result of various studies, as a method for detecting power shortage, it is characterized in that when the change amount of the AC input voltage is a negative value and the absolute value of the change amount of the AC input voltage exceeds a predetermined threshold, the rotational speed of the permanent magnet motor 6 is suppressed.

[0045] Figure 4 It is a diagram showing the relationship between the peak value of the AC input voltage and the control frequency of the first embodiment. In the state where the AC power supply 1 is 200Vrms, in the case of suddenly rising to 240Vrms, if the frequency is directly controlled, the power supply and demand balance will collapse. Previously, the frequency command value was limited to the minimum frequency command value F min . Thus, the power supply and demand balance is maintained. In this embodiment, when controlling the rotational speed of the permanent magnet motor 6, based on Figure 4It is controlled by a numerically predetermined table representing the relationship between the AC input voltage and the rotational speed (frequency command value).

[0046] Figure 5 It is a flowchart showing the speed control process S50 of the first embodiment. The MCU8 measures the peak value of the AC input voltage (step S51) and compares it with the previously detected voltage (step S52). The MCU8 determines whether the determination condition that the voltage change amount ΔV (=V i+1 -V i ) is negative (ΔV < 0) and whether the absolute value of ΔV exceeds ΔVac (threshold value) (|ΔV| > ΔVac) is satisfied (step S53).

[0047] When the determination condition is satisfied (step S53, yes), the MCU8 decelerates the rotational speed (step S54) and returns to step S51. On the other hand, when the determination condition is not satisfied (step S53, no), the MCU8 does not perform any restriction and returns to step S51 as normal. The above process is implemented at each control time ΔT.

[0048] Figure 6 It is a diagram showing an example of the control of the speed control process applying the first embodiment Figure 5 . The horizontal axis is time and the vertical axis is the peak value of the AC input voltage. At each of the times t1, t2, t3, ···, the peak values of the AC input voltage V1, V2, V3, ··· are measured. The MCU8 determines at each time whether the determination condition shown in step S53 of Figure 5 is satisfied.

[0049] At time t5, (1) if it is determined that ΔV = V5 - V4 is negative and |ΔV| > ΔVac, the rotational speed is decelerated. Then, (2) by decelerating the rotational speed, the balance between power supply and demand is maintained and the power is restored.

[0050] The specific sequence is further described.

[0051] (1) The input voltage is detected, and thereby the input voltage change amount is measured.

[0052] It is measured once within every 1 ms. The average value of 16 or more times is passed through a 1000 - ms filter to calculate the voltage value Vi.

[0053] (2) The change amount between Vi and the previous voltage value V i－1 is calculated.

[0054] If the input voltage change amount ΔV = V i－1 -V i is negative and the threshold value is ΔVac (=2.5 V or more), check whether |ΔV| > ΔVac is exceeded.

[0055] (3) In case of exceeding, decrease the rotation speed of the motor.

[0056] Since the motor power is restored, the rotation speed of the motor becomes smaller. That is, the required power of the motor becomes less. The control frequency drops below 13.33 Hz.

[0057] (4) Then, decrease the speed until the input voltage change amount ΔV becomes below the threshold value ΔVac, and after it becomes below the threshold value ΔVac, abort this process.

[0058] Figure 7A It is a graph showing the time change of the control frequency and the input voltage peak value before applying the first embodiment. Figure 7B It is a graph showing the time change of the control frequency and the input voltage peak value after applying this embodiment.

[0059] Figure 7A In the case of, the control frequency of the MCU8 rises from the current frequency toward the frequency target. At the power supply shortage part, the power balance between input and output collapses. If power cannot be supplied, the input voltage drops suddenly. As a result, there is a problem that the motor cannot be controlled.

[0060] Figure 7B In the case of, although the control frequency rises from the current frequency toward the frequency target, the MCU8 can limit the speed to the rotation speed at which the motor can operate. In addition, by limiting the rotation speed according to the change amount of the voltage, the input voltage peak value is immediately restored.

[0061] <Effect>

[0062] (1) It is possible to re - establish the rotation speed control method of the permanent magnet motor in countries or regions with unstable voltages.

[0063] (2) It is possible to meet the existing structural requirements without adding components and increasing costs.

[0064] (3) It is possible to detect the sign of the state where the motor cannot be controlled based on the voltage amount and perform control.

[0065] In addition, in this embodiment, the case where the system voltage is 220V - 240V has been described, but the control range can be set according to the situation of that country or region.

[0066] <<Second Embodiment>>

[0067] In the first embodiment, control is performed based on one table showing the relationship between the AC input voltage and the rotation speed (frequency command value). In the second embodiment, a method of controlling based on multiple tables will be described. Figure 4 Based on

[0068] Figure 8A It is a diagram showing the relationship between the peak value of the AC input voltage and the frequency command value in the second embodiment (AC200Vrms). Figure 8B It is a diagram showing the relationship between the peak value of the AC input voltage and the frequency command value in the second embodiment (AC220Vrms). Figure 8C It is a diagram showing the relationship between the peak value of the AC input voltage and the frequency command value in the second embodiment (AC240Vrms).

[0069] In the second embodiment, there are multiple tables corresponding to the AC input voltage in the MCU8. The MCU8 controls based on a table representing the relationship between the Figures 8A - 8C predetermined AC input voltage and the rotational speed (frequency command value) in numerical form.

[0070] When the user sets the regulator 2 to the state of SW1 and the system voltage is unstable and the AC power supply 1 rises from 200V to 240V, the MCU8 transfers from the table based on Figure 8A to the table based on Figure 8C and commands the inverter unit 5 with the frequency command value. Similarly, when the system voltage is unstable and the AC power supply 1 rises from 200V to 220V, the MCU8 transfers from the table based on Figure 8A to the table based on Figure 8B and commands the inverter unit 5 with the frequency command value. Thus, appropriate control can be achieved even when the AC input voltage is unstable. Also, when the system voltage is unstable and the AC power supply 1 drops from 240V to 220V, the MCU8 transfers from the table based on Figure 8C to the table based on Figure 8B and commands the inverter unit 5 with the frequency command value.

[0071] The control method, control device, and hanging electric fan of the permanent magnet motor of the present embodiment described above have the following characteristics.

[0072] (1) A control method for a permanent magnet motor, the permanent magnet motor comprising: a converter unit 3 that converts an AC input voltage into a DC voltage; an inverter unit 5 that converts the DC voltage into an AC voltage; a permanent magnet motor 6; and a control unit (such as the MCU8) that controls the inverter unit 5 to control the rotational speed of the permanent magnet motor 6. The control unit detects the AC input voltage, measures the change amount of the peak value or the effective value of the AC input voltage, and controls the rotational speed of the permanent magnet motor when the change amount is a negative value and the absolute value of the change amount exceeds a predetermined threshold. Thus, the permanent magnet motor in areas with unstable voltage can be appropriately controlled.

[0073] (2)In the control method of the permanent magnet motor in (1) above, when suppressing the rotational speed of the permanent magnet motor 6, it is controlled based on a table showing the relationship between a predetermined AC input voltage and the rotational speed.

[0074] (3)In the control method of the permanent magnet motor in (1) above, the AC input voltage is the voltage of an AC power supply passing through a current limiter with variable resistance, i.e., a regulator.

[0075] (4)A control device 10 includes: an inverter section 5 that converts a DC voltage into an AC voltage; and a control section that controls the inverter section 5 to control the rotational speed of the permanent magnet motor 6. The control section detects the AC input voltage, measures the change amount of the peak value or the effective value of the AC input voltage, and suppresses the rotational speed of the permanent magnet motor when the change amount is a negative value and the absolute value of the change amount exceeds a predetermined threshold. Thus, the permanent magnet motor in an area with unstable voltage can be appropriately controlled.

[0076] (5)A ceiling fan (e.g., ceiling fan 7) equipped with the control device 10 described in (4) above can be provided.

[0077] Description of symbols

[0078] 1 - AC power supply, 2 - Regulator, 3 - Converter section, 4 - Capacitor, 5 - Inverter section, 6 - Permanent magnet motor, 7 - Ceiling fan (ceiling fan), 8 - MCU (control section), 9 - Voltmeter, 10 - Control device, 21 - Switch, 22 - Relationship between SW and resistance, 23 - Frequency command value, S50 - Speed control process.

Claims

1. A control method for a permanent magnet motor, the permanent magnet motor comprising: A converter section that converts an AC input voltage into a DC voltage; An inverter section that converts the DC voltage into an AC voltage; A permanent magnet motor; and A control section that controls the inverter section in order to control the rotational speed of the permanent magnet motor, The control method for the permanent magnet motor is characterized in that, The control section detects the AC input voltage, Measures the change amount of the peak value or the effective value of the AC input voltage, When the change amount is a negative value and the absolute value of the change amount exceeds a predetermined threshold, controls the rotational speed of the permanent magnet motor.

2. The control method for the permanent magnet motor according to claim 1, characterized in that, When suppressing the rotational speed of the permanent magnet motor, it is controlled based on a table showing the relationship between the predetermined AC input voltage and the rotational speed.

3. The control method for the permanent magnet motor according to claim 1, characterized in that, The AC input voltage is the voltage of an AC power supply passing through a current limiter with variable resistance, i.e., a regulator.

4. A control device, comprising: An inverter section that converts a DC voltage into an AC voltage; and A control section that controls the inverter section in order to control the rotational speed of a permanent magnet motor, The control device is characterized in that, The control section detects an AC input voltage, Measures the change amount of the peak value or the effective value of the AC input voltage, When the change amount is a negative value and the absolute value of the change amount exceeds a predetermined threshold, controls the rotational speed of the permanent magnet motor.

5. A ceiling fan, characterized in that, It is equipped with the control device according to claim 4.

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