JP4383576B2 - Vacuum cleaner and inverter device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a vacuum cleaner configured to drive a dust collecting fan with a brushless motor, and an inverter device for driving the brushless motor.
[0002]
[Prior art]
In recent years, brushless motors with a wide variable speed range and high motor efficiency have been adopted for motors used in home appliances. Driving this brushless motor with an inverter device improves usability and reduces power consumption. The improvement of the performance is aimed at.
[0003]
For example, in a vacuum cleaner, conventionally, a fan is driven by an AC commutator motor. However, since the fan of the vacuum cleaner is required to have a wide range of variable speed, the variable speed capability of the AC commutator motor may be insufficient. Therefore, in recent years, as disclosed in, for example, JP-A-63-95884, JP-A-63-249488, JP-A-7-337067, and the like, a fan is controlled by an inverter device. The one configured to be driven by a motor has been proposed.
[0004]
Hereinafter, the configuration of a general inverter device used in home appliances and the like will be briefly described with reference to FIG.
In FIG. 4 showing the electrical configuration of the inverter device, the inverter device 1 includes a DC power supply circuit 2, an inverter main circuit 3, and a control circuit 4. Among them, the DC power supply circuit 2 includes a power factor improving reactor 6 connected to one power supply line of an AC power supply 5 (for example, a single-phase 100 V commercial power supply), and both power supply lines of the AC power supply 5 through the reactor 6. And a smoothing capacitor 8 connected between the rectified output terminals of the diode bridge 7. The inverter main circuit 3 is configured as a well-known voltage source inverter in which IGBTs 9a to 9f and freewheeling diodes 10a to 10f are connected in a three-phase bridge, and the output terminal of the inverter main circuit 3 has a winding 11u of the brushless motor 11. ~ 11w terminals are connected.
[0005]
The brushless motor 11 is provided with position detection elements 12u to 12w that detect the rotational position of the rotor and output it as a position signal. The waveform synthesis circuit 13 synthesizes the energization signals Dup to Dwn generated by the energization signal generation circuit 14 based on the position signal and the PWM signal generated by the PWM circuit 15 based on the voltage command, and is PWM-controlled energization signal. Fup to Fwn are obtained, and the energization signals Fup to Fwn are applied to the gates of the IGBTs 9a to 9f via the drive circuit 16.
[0006]
With the above configuration, the three-phase AC voltage corresponding to the voltage command is applied to the windings 11u to 11w of the brushless motor 11, and the brushless motor 11 to which various loads (for example, fans) in the home appliance are connected is rotationally driven. It has become so.
[0007]
[Problems to be solved by the invention]
In the above configuration, in order to obtain a DC voltage from the AC voltage of the AC power supply 5 in the DC power supply circuit 2, the power factor improving reactor 6 and the smoothing capacitor 8 are required. However, the volume and weight of the reactor 6 and the volume of the capacitor 8 are large, which causes the volume and weight of the entire device to increase. In particular, in a device that is used while being moved, such as a vacuum cleaner, there has been a problem that an increase in volume and weight deteriorates the usability of the user.
[0008]
The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a small and light vacuum cleaner, and a small and light inverter device applicable to general electric equipment using a brushless motor. Is to provide.
[0009]
[Means for Solving the Problems]
In order to achieve the above object, a vacuum cleaner according to claim 1 includes a fan, a brushless motor that has a plurality of windings and drives the fan, and an inverter device that drives the brushless motor. Configured,
The inverter device includes position detection means for detecting a rotational position of a rotor of the brushless motor, rectification means for outputting a full-wave rectified voltage obtained by full-wave rectification using an AC power supply, and an AC power supply. A zero-cross point detecting means for detecting a zero-cross point of the voltage, and an energization width that is effective for a period of time that is synchronized with the AC power supply voltage and has a width corresponding to the voltage command, based on the detected zero-cross point and the voltage command An energization width signal generating means for generating a signal, and energization for generating an energization signal for energizing the windings of the plurality of phases based on the detected rotational position of the rotor in a period in which the energization width signal is valid A signal generation unit; and an inverter main circuit that receives the full-wave rectified voltage output from the rectification unit and energizes the windings of the plurality of phases based on the energization signal. Made is characterized in that is.
[0010]
According to this configuration, the inverter main circuit energizes the windings of the brushless motor using the full-wave rectified voltage obtained by the full-wave rectification of the AC power supply voltage by the rectifier as the input voltage. The reactor and the smoothing capacitor for the purpose of improving the power factor and the like inserted between the means are not necessary. Thereby, a vacuum cleaner can be reduced in size and weight, and a user's convenience improves .
[0011]
In this case, the inverter device includes a zero-cross point detecting unit that detects a zero-cross point of the AC power supply voltage, and a width that is synchronized with the AC power-supply voltage based on the detected zero-cross point and the voltage command and that corresponds to the voltage command. And an energization width signal generating unit that generates an energization width signal that is valid for a period of time. The energization signal generation unit is configured to generate an energization signal during a period in which the energization width signal is valid.
[0012]
According to this configuration, the energization signal generating means synchronizes with the AC power supply voltage based on the detected zero cross point, generates an energization signal for a period according to the voltage command, and energizes the windings of the brushless motor. Therefore, a voltage corresponding to the voltage command is applied to the windings, and the brushless motor can be driven to be variable.
[0013]
Moreover, in order to achieve the said objective, the inverter apparatus described in Claim 2 is an inverter apparatus which drives the brushless motor which has a multiphase winding,
Rectifying means for outputting a full-wave rectified voltage obtained by full-wave rectifying the voltage with an AC power supply as input, zero-cross point detecting means for detecting a zero-cross point of the AC power supply voltage, and the detected zero-cross point and voltage And an energization width signal generating means for generating an energization width signal that is valid for a period of time having a width corresponding to the voltage command based on the command, and a rotational position of a rotor of the brushless motor. An energization signal for energizing the windings of the plurality of phases is generated based on the position detection means to detect, the energization width signal and the detected rotational position of the rotor during a period in which the energization width signal is valid. An energization signal generating means for performing an operation, and an inverter main circuit for receiving the full-wave rectified voltage output from the rectifying means and energizing the windings of the plurality of phases based on the energization signal. Made is characterized in that is.
[0014]
According to this configuration, the voltage applied to the winding of the brushless motor can be controlled to a value according to the voltage command by the same operation as described above, and the inverter and the smoothing capacitor are not required. It can be reduced in size and weight.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of a vacuum cleaner according to the present invention will be described with reference to FIGS. 1 to 3.
FIG. 2 shows a schematic cross-sectional view of a vacuum cleaner. In FIG. 2, a brushless motor 22 and an inverter device 23 for driving the brushless motor 22 are provided in a main body 21 of the vacuum cleaner, and a rotating shaft 22 a of the brushless motor 22 is used for collecting dust. A fan 24 is attached. In the main body 21, a dust collection chamber 26 is provided between the hole 21 a communicating with the suction port 25 and the fan 24. Furthermore, the operation part (not shown) of the vacuum cleaner is provided with, for example, an operation switch, a stop switch, and a capacity variable switch that can set the suction force in a plurality of stages (for example, four stages). The main body 21 is provided with a pair of wheels 27 and 27 so that the main body 21 can be easily moved.
[0016]
The dust sucked together with the air from the suction port 25 by the rotation of the fan 24 is collected in the dust collecting chamber 26 by the dust collecting action of a filter (not shown) provided in the main body 21. The purified air passes through the inside of the brushless motor 22 and contributes to cooling of the brushless motor 22, and is then discharged from the rear portion of the main body 21 to the outside.
[0017]
Next, the electrical configuration of the inverter device 23 housed in the main body 21 will be described with reference to FIG. The inverter device 23 includes a rectifier circuit 28 as a rectifier, an inverter main circuit 29, and a control circuit 30. The rectifier circuit 28 is composed of, for example, a diode bridge 28a, an AC power supply 31 (for example, a single-phase 100V commercial power supply) is connected to the AC input terminal, and a positive power supply line 32p and a negative side are connected to the rectified output terminal. An inverter main circuit 29 is connected through a power line 32n. Here, as one feature of the inverter device 23, no power factor improving reactor is inserted between the AC power supply 31 and the rectifier circuit 28, and the positive power supply line 32p and the negative power supply line 32n are inserted. No smoothing capacitor is connected between the two.
[0018]
The inverter main circuit 29 is configured by connecting switching elements such as IGBTs 33a to 33f and free-wheeling diodes 34a to 34f connected in parallel to the IGBTs 33a to 33f in directions in which the energization directions are opposite to each other, respectively. Yes. The output terminals 35u, 35v, and 35w of the inverter main circuit 29 are connected to the terminals of the windings 22u, 22v, and 22w of the brushless motor 22, respectively.
[0019]
The brushless motor 22 includes a stator 22s (see FIG. 2) around which windings 22u, 22v, and 22w are wound, and a rotor 22r (see FIG. 2) in which permanent magnets are disposed. In order to detect the rotational position of 22r, for example, three position detecting elements 36u, 36v and 36w (corresponding to the position detecting means in the present invention) made up of Hall elements are provided. Position signals Su, Sv, Sw (see FIG. 3) having a high level or a low level corresponding to the rotational position of the rotor 22r are output from the position detection elements 36u, 36v, 36w.
[0020]
The control circuit 30 for controlling the inverter main circuit 29 is configured as follows mainly with a microcomputer. That is, the energization signal generation circuit 37 as the energization signal generation means inputs the position signals Su, Sv, Sw, and performs a logical operation on them to perform the energization signals Dup, Dun, Dvp, Dvn, Dwp according to the 120 ° energization method. , Dwn (see FIG. 3). The zero-cross point detection circuit 38 serving as a zero-cross point detection means detects a zero-cross point with respect to the AC voltage of the AC power supply 31, and outputs a pulse-like zero-cross signal that becomes a high level at the time of detection.
[0021]
Whenever the zero cross point is detected, the energization width signal generation circuit 39 as the energization width signal generating means generates an energization width signal Son that becomes a high level as an effective level from the zero cross point by a width corresponding to the voltage command Sv. Generate. The waveform synthesis circuit 40 that constitutes the energization signal generation means together with the energization signal generation circuit 37 generates the energization signals Gup to Gwn by synthesizing the generated energization signals Dup to Dwn and the energization width signal Son. The energization signals Gup to Gwn are applied to the gates of the IGBTs 33a to 33f via the drive circuit 41. In the energization signals Dup to Dwn and the energization signals Gup to Gwn, the high level corresponds to turning on the IGBTs 33a to 33f, and the low level corresponds to off.
[0022]
Next, the operation of this embodiment will be described with reference to FIG.
When the stop switch of the operation part of the vacuum cleaner is turned on, a voltage command Sv with an output voltage of 0% is given from the operation part to the energization width signal generation circuit 39, and when the operation switch of the operation part is turned on, the operation part A predetermined voltage command Sv between 0% and 100% of the output voltage is given to the energization width signal generation circuit 39 according to the state of the variable capacity switch. In this case, the higher the suction capability is, the larger the voltage command value becomes. When the maximum capability is set among the four steps of variable capability, for example, 100% voltage command Sv, that is, the inverter main circuit 29 outputs it. The maximum voltage to be obtained is commanded. When the voltage command Sv is 0%, the signal width of the energization width signal Son is 0. Therefore, the waveform synthesis circuit 40 prohibits the output of the energization signals Gup to Gwn, and the windings 22u, 22v, 22w. The power supply to is stopped.
[0023]
FIG. 3 shows waveforms at various parts when the voltage command value increases every half cycle of the AC power supply 31. In FIG. 3, for example, the AC voltage of the AC power supply 31 having a frequency of 50 Hz or 60 Hz is full-wave rectified by the rectifier circuit 28 to become a full-wave rectified voltage. The energization width signal generation circuit 39 generates an energization width signal Son that becomes a high level only for a time width corresponding to the voltage command Sv, starting from the zero cross point, every half cycle of the AC power supply 31 to which the zero cross signal is input. The high level (effective level) width (energization width) of the energization width signal Son is calculated by the following equation.
Energizing width [sec] = voltage command value x (1 / power frequency) / 2 (1)
However, voltage command value: 0 (0%) to 1 (100%)
[0024]
In FIG. 3, the case where period 1 is “minimum capacity” is shown, the case where period 4 is “maximum capacity”, and the case where periods 2 and 3 are these intermediate abilities are shown. In the period 4 that is “maximum capacity”, the energization width is equal to the time interval between the zero cross points (that is, the half cycle of the AC power supply voltage) based on the equation (1).
[0025]
On the other hand, the energization signal generation circuit 37 corresponds to the rotational position of the rotor 22r, and the energization signals Dup, Dun, Dvp according to the 120 ° energization method are based on the position signals Su, Sv, Sw shifted from each other by 120 °. , Dvn, Dwp, Dwn. Then, the waveform synthesis circuit 40 logically multiplies the energization width signal Son and the energization signals Dup to Dwn, so that the energization width signal Son is equal to the energization signals Dup to Dwn during the period when the energization width signal Son is at a high level. During the period when the energization width signal Son is at the low level, energization signals Gup to Gwn that are at the low level are generated. These energization signals Gup to Gwn are respectively applied to the gates of the IGBTs 33a to 33f through the drive circuit 41, and a three-phase AC voltage is applied to the winding terminals of each phase of the brushless motor 22. Accordingly, currents iu, iv, and iw having amplitudes (indicated by two-dot chain lines in FIG. 3) corresponding to the magnitude of the full-wave rectified voltage flow through the windings 22u, 22v, and 22w.
[0026]
That is, the energization width corresponding to the voltage command Sv is determined according to the equation (1), and energization is performed by the 120 ° energization method within the energization width period (period when the energization width signal Son is at a high level). Energization is prohibited outside the width period (period when the energization width signal Son is at a low level). Thus, the average voltage applied to the windings 22u to 22w is determined according to the voltage command Sv, so that the brushless motor 22 can be driven at a variable speed.
[0027]
As described above, according to the present embodiment, the inverter device 23 is configured to energize the brushless motor 22 using the full-wave rectified voltage of the AC power supply 31 as an input to the inverter main circuit 29. The reactor 6 and the capacitor 8 used in the inverter device 1 having the configuration (see FIG. 4) are not required, and the inverter device 23 can be reduced in size and weight. As a result, the vacuum cleaner is reduced in size and weight, improving usability and reducing the cost.
[0028]
The inverter device 23 determines the energization width according to the voltage command Sv every half cycle in synchronization with the AC power supply voltage, and energizes the windings 22u to 22w only during the energization width starting from the zero cross point. It is configured. That is, the inverter device 23 can vary the voltage applied to the windings 22u to 22w without performing PWM. Thereby, the brushless motor 22 can be driven at a variable speed over a wide range. Since the energization width signal Son and the AC power supply voltage are synchronized, the monotonic increase of the output voltage of the inverter main circuit 29 with respect to the voltage command Sv is secured, and the controllability of the voltage is good.
[0029]
Further, since PWM is not required for voltage control, generation of switching noise due to switching of the inverter main circuit 29 is small, and occurrence of radio wave interference can be suppressed. In addition, since the switching loss is reduced, the heat sinks of the IGBTs 33a to 33f and the free wheel diodes 34a to 34f can be reduced in size. Furthermore, there is an advantage that harmonic currents associated with PWM do not flow through the AC power supply 31.
[0030]
The present invention is not limited to the embodiment described above and shown in the drawings, and can be expanded or changed as follows.
The inverter device 23 is suitable for, for example, household appliances and electric devices used while moving, in addition to a vacuum cleaner.
The inverter device 23 may be configured to receive a speed command and generate a voltage command Sv from the speed command value and a speed detection value obtained based on the position signals Su, Sv, Sw.
[0031]
It is possible to provide a capacitor that functions as a noise filter or a snubber or a capacitor for the purpose of removing external noise entering from the AC power supply 31 between the positive power supply line 32p and the negative power supply line 32n. It does not deviate from the purpose. Similarly, a reactor or a capacitor for a normal mode filter or a common mode filter may be provided between the rectifier circuit 28 and the AC power supply 31.
[0032]
The starting point of the effective level (high level) of the energization width signal Son is not limited to the zero cross point, and for example, it may be the time when a time corresponding to the voltage command Sv has elapsed from the zero cross point. The energization width may be set so as to spread around the center point between the zero cross points (the maximum point of the full-wave rectified voltage). Furthermore, the energization width may be divided and set between the zero cross points (within the half cycle of the AC power supply 31).
[0033]
The calculation method of the energization width based on the voltage command Sv is not limited to the equation (1). For example, the voltage command value and the output voltage of the inverter main circuit 29 are linear in consideration of the full-wave rectified voltage. An arithmetic method may be used.
[0034]
【The invention's effect】
As described above, the inverter device mounted in the vacuum cleaner of the present invention drives the brushless motor using the full-wave rectified voltage obtained by full-wave rectification of the AC power supply voltage as the input of the inverter main circuit, so that the power factor is improved. For example, a reactor and a smoothing capacitor are not required. Therefore, the inverter device and thus the vacuum cleaner can be reduced in size and weight, and the usability of the vacuum cleaner is improved.
[Brief description of the drawings]
FIG. 1 is an electrical configuration diagram of an inverter device showing an embodiment of the present invention. FIG. 2 is a schematic cross-sectional view of a vacuum cleaner. FIG. 3 is a waveform diagram of each part for explaining the operation of the inverter device. Fig. 4 Fig. 4 Equivalent to Fig. 1 showing the prior art.
22 is a brushless motor, 22r is a rotor, 22u, 22v and 22w are windings, 23 is an inverter device, 24 is a fan, 28 is a rectifier circuit (rectifier means), 29 is an inverter main circuit, and 36u, 36v and 36w are position detections. Elements (position detection means), 37 is an energization signal generation circuit (energization signal generation means), 38 is a zero cross point detection circuit (zero cross point detection means), 39 is an energization width signal generation circuit (energization width signal generation means), and 40 is It is a waveform synthesis circuit (energization signal generation means).

Claims (2)

With fans,
A brushless motor having a plurality of windings and driving the fan;
An inverter device for driving the brushless motor,
The inverter device is
Position detecting means for detecting the rotational position of the rotor of the brushless motor;
Rectifying means for outputting a full-wave rectified voltage obtained by full-wave rectifying the voltage with an AC power supply as input,
Zero-cross point detection means for detecting the zero-cross point of the AC power supply voltage;
On the basis of the detected zero cross point and the voltage command, an energization width signal generating unit that generates an energization width signal that is valid for a period of time that is synchronized with the AC power supply voltage and has a width corresponding to the voltage command ;
An energization signal generating means for generating an energization signal for energizing the windings of the plurality of phases based on the detected rotational position of the rotor in a period in which the energization width signal is valid ;
An electric vacuum cleaner comprising: an inverter main circuit that receives a full-wave rectified voltage output from the rectifying means and energizes the plurality of windings based on the energization signal. In an inverter device for driving a brushless motor having a multi-phase winding,
Rectifying means for outputting a full-wave rectified voltage obtained by full-wave rectifying the voltage with an AC power supply as input,
A zero-cross point detecting means for detecting a zero-cross point of the AC power supply voltage,
On the basis of the detected zero cross point and the voltage command, an energization width signal generating unit that generates an energization width signal that is valid for a period of time that is synchronized with the AC power supply voltage and has a width corresponding to the voltage command ;
Position detecting means for detecting the rotational position of the rotor of the brushless motor;
On the basis of the energization width signal and the detected rotational position of the rotor, energization signal generating means for generating an energization signal for energizing the windings of the plurality of phases in a period in which the energization width signal is valid ;
An inverter device comprising: an inverter main circuit that receives a full-wave rectified voltage output from the rectifying means and energizes the plurality of windings based on the energization signal .

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