JP2008018006A - Vacuum cleaner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve circuit efficiency and to improve suction power in an inverter cleaner loaded with a brushless motor. <P>SOLUTION: The electric constant of the brushless motor 3 is optimally designed so as to maximize the voltage capacity factor of an inverter part 4 in the case that a DC voltage is boosted so as to improve the power factor of an AC power source 1 compared to the case of not performing boosting by the booster circuit of a converter part 2 under the condition that power consumption is a prescribed value set beforehand. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a vacuum cleaner, and more particularly to a vacuum cleaner using a brushless motor driven by an inverter.

  In conventional vacuum cleaners, in order to achieve a high suction force with a compact shape, a high efficiency, commutator motor that rotates at a high speed exceeding 20000 rpm and a high suction speed generate a large suction air volume and vacuum pressure. A blower integrated with a suction fan is used. In the commutator motor, since the rotor is a winding-type armature, a brush fixed to a commutator that is provided in the armature and rotates at high speed contacts and supplies current.

  In the field of household vacuum cleaners, improvement of “suction work rate = vacuum degree × air volume × 0.01666 (W)” based on JIS as a performance index of a vacuum cleaner has been promoted for many years. The suction work rate has reached 500W or more. As a result, the power consumption of the vacuum cleaner has reached about 1000W.

  It is possible to obtain a higher suction work rate by increasing the power consumption, but from the viewpoint of energy saving, safety and breaker capacity, the increase in power consumption beyond the current level of household vacuum cleaners has reached its limit. Therefore, the improvement of the suction work rate has come to the limit.

  Carbon brushes are used in commutator motors of vacuum cleaners. Since the brush and the commutator are in contact with each other, the brush is consumed as it is operated, and the carbon fine particles that are scraps of the brush are scattered. In order not to release carbon debris outside the vacuum cleaner, it is necessary to install a filter for removing carbon debris in the exhaust part of the suction fan motor.

  Since the installation of a filter for removing carbon debris is a cost increase factor, it is conceivable to install a brushless motor instead of the commutator motor as a countermeasure not depending on such a filter. If a brushless motor is used, it is obvious that the carbon fine particles do not scatter. Patent Document 1 discloses a vacuum cleaner using a brushless motor.

In vacuum cleaners, the relationship between power consumption and suction power is roughly
Suction work rate = power consumption × total efficiency Here, total efficiency = circuit efficiency × motor efficiency × fan efficiency.
Even if the limit of power consumption is 1000 W, it is possible to improve the suction work rate by improving the overall efficiency represented by the product of circuit efficiency, motor efficiency, and fan efficiency.

  In FIG. 10, an example of the experimental result of the efficiency and suction | inhalation work rate of each part of a commutator motor cleaner and a brushless motor cleaner (conventional example) when power consumption is 1000W is shown.

  In order to rotate the brushless motor at high speed, it is necessary to drive the brushless motor with a high frequency power source. For this reason, an inverter power source is required that rectifies an AC voltage supplied from an AC power source and converts it into a DC voltage and then converts the DC voltage to a high-frequency AC voltage. As described above, since AC / DC conversion is performed by the inverter power supply, the circuit efficiency of the drive power supply unit of the brushless motor is usually lower than the circuit efficiency of the commutator motor drive circuit.

  Brushless motors have higher motor efficiency than commutator motors with comparable output, but the overall efficiency decreases because the reduction in circuit efficiency is greater than the improvement in motor efficiency, and the power consumption is limited to a fixed value. , The suction work rate decreases.

  In the example of FIG. 10, there is a difference of about 15% between 98% and 83% in both circuit efficiency, so if the vacuum cleaner equipped with the commutator motor has a suction power of 500 W, a brushless motor is installed. In a vacuum cleaner, it will drop to about 425W.

  Even in the actual examples of vacuum cleaners that are currently being sold, vacuum cleaners with a power consumption of about 1000W and those with commutator motors that have a suction power of over 500W are the mainstream, while brushless motors are installed. In the vacuum cleaner, the suction work rate stays below 500W.

  Patent Document 2 discloses a brushless motor suitable for a vacuum cleaner. As a brushless motor, a brushless DC motor having a region that is operated at a chopper control continuity of 100% is provided to easily prevent overload operation, and further, high-speed rotation due to an abnormal rotation command value of the control device. It is intended to prevent this.

  Further, in Patent Document 2, as an effect of the invention other than the prevention of the high-speed rotation, since the conduction rate is close to 100% in the vicinity of the allowable input upper limit value, which is a region where the load becomes large, harmonic components generated due to current interruption are reduced. Therefore, it is disclosed that the system efficiency including the inverter device and the brushless DC motor is in the best state, and the efficiency can be increased on the high load side, for example, heat generation can be reduced.

  However, since this patent document 2 does not describe a specific measure for improving the circuit efficiency as an example, a person skilled in the art is a vacuum cleaner with power consumption of about 1000 W, which is equivalent to a vacuum cleaner equipped with a commutator motor. A suction power exceeding 500 W cannot be easily realized.

Patent Document 3 discloses a power supply device that rectifies an alternating current power source and converts it into direct current with a simple circuit configuration without using an alternating current command waveform, and particularly improves power factor. That is, a current ratio that regulates the operation of the switching element used in the power factor correction circuit is created based on the product of the coefficient set in accordance with the load status information and the power supply current information, and switching is performed at the current ratio. The element is operating.
Japanese Examined Patent Publication No. 4-63685 (third column, eleventh row to fourth column, eleventh row, FIG. 2) Japanese Patent No. 3039558 (5th column, 23rd row to 6th column, 8th row, FIG. 4) JP-A-3-230759 (page 6, upper right column, first line to lower right column, fifth line, FIGS. 1 and 2)

  Therefore, the electric constant of the brushless motor is set so that the voltage utilization factor of the inverter unit becomes maximum when the DC voltage is boosted by the booster circuit of the converter unit under the condition that the power consumption is a predetermined value set in advance. There is a problem to be solved in terms of optimization design.

  The object of the present invention is to improve the overall efficiency by improving circuit efficiency in a vacuum cleaner equipped with a clean brushless motor that is inverter-controlled and eliminates the carbon dust scattering of the commutator motor. This is to achieve a suction power equivalent to or higher than that of a vacuum cleaner employing a child motor.

  In order to achieve the above object, an electric vacuum cleaner according to the present invention includes an electric blower having a blower fan and a brushless motor that drives the blower fan, a control unit for controlling the brushless motor, and an AC power supply. A converter unit that rectifies the AC voltage supplied from the converter and converts it into a DC voltage, and a power source unit that includes an inverter unit that converts the DC voltage into an AC voltage and supplies the AC voltage to the brushless motor. In the vacuum cleaner, the electric constant of the brushless motor is set so that the voltage utilization rate of the inverter unit is substantially maximized under an operating load condition in which the power consumption of the brushless motor becomes a predetermined power consumption value during operation of the vacuum cleaner. In addition to the optimization design, the converter unit is provided with a booster circuit to boost the DC voltage by the booster circuit. It is characterized by performing the power factor correction sources.

  According to this electric vacuum cleaner, when the power consumption of the vacuum cleaner is controlled so as to be a predetermined value that is a rated value adopted for the performance evaluation of the vacuum cleaner, the voltage utilization rate of the inverter unit becomes maximum. Thus, the circuit efficiency at the rated load of the brushless motor is improved by designing the electric constants of the brushless motor in an optimized manner, that is, by designing the winding shape, the number of turns, and the positional relationship between the magnet and the winding. Further, the converter unit employs a booster circuit to boost the DC voltage, thereby improving the power factor of the AC power supply and improving the circuit efficiency.

  The inverter unit controls the rotational speed of the brushless motor by the PWM method, and the brushless motor is designed so that the electric constant of the brushless motor is maximized at a PWM duty ratio of 100%. Improve circuit efficiency at rated load.

  In addition, the converter unit performs voltage doubler rectification and improves circuit efficiency by adopting a booster circuit configuration in which an AC power supply is forcibly short-circuited through a reactor connected in series on the power supply side.

  Furthermore, specifically, the inductance of the reactor is set to 1 to 3 mH.

  The predetermined power consumption value is 1000 W.

  According to the vacuum cleaner of the present invention, by using a brushless motor, there are problems with a conventional vacuum cleaner using a commutator motor, such as a problem that the life of the brush is short and a problem that carbon dust is generated. Can be resolved. Further, by using a brushless motor, the motor efficiency can be improved as compared with a conventional vacuum cleaner using a commutator motor.

  Since the power source power factor can be greatly improved by the booster circuit, the inductance of the reactor can be reduced as compared with the conventional brushless motor cleaner without the booster circuit, so that the reactor can be reduced in weight and size. Therefore, the weight of the vacuum cleaner can be reduced as compared with the conventional brushless motor vacuum cleaner.

  Furthermore, by designing the electric constant of the motor so that the voltage utilization factor of the inverter is maximized at the DC voltage at which the power source power factor becomes the highest in the full load state with the preset maximum power consumption, Compared with the brushless motor vacuum cleaner, the circuit efficiency can be greatly improved.

  In addition, when the PWM control method is adopted for the inverter part in the vacuum cleaner according to the present invention, by setting the PWM duty ratio to 100%, the effect of the circuit surface such as reduction of switching loss of the inverter part and reduction of switching noise can be achieved. In addition, since the waveform approximates a sine wave, the harmonic component generated by switching is reduced, and the motor iron loss can be reduced and the motor efficiency can be improved.

  In the vacuum cleaner according to the present invention, when the booster circuit is forcibly short-circuited with an AC power supply, the booster circuit can be realized with a simple configuration. In addition, while a method called an active filter method generally performs switching at a high frequency, the present invention is a method of performing switching once during a half cycle of the power supply, and switching loss is reduced. I can plan.

  In addition, the present invention has a lower power factor in a half load state where the power consumption is about 500 W than the active filter method, but a power source in a full load state where the preset maximum power consumption is about 1000 W. Power factor is not much different. Therefore, it can be said that this is a method that places importance on the driving performance at the maximum power consumption, which is the measurement condition of the display suction work rate in the vacuum cleaner.

  By using the boosting circuit to be short-circuited and setting the inductance of the reactor to 1 to 3 mH, the power factor can be improved, and the reactor can be reduced in size and weight. Therefore, compared with the conventional brushless motor cleaner, the circuit efficiency can be improved, and the cleaner can be reduced in size and weight.

  Furthermore, a large suction performance can be exhibited by using approximately 1000 W of power consumption equivalent to that of a general commutator motor cleaner.

  As described above, the brushless motor cleaner of the present invention greatly improves the circuit efficiency compared with the conventional brushless motor cleaner, and the motor efficiency can be improved by setting the PWM duty ratio to 100%, so the suction work rate is greatly improved. can do. Further, assuming that the fan efficiency of the conventional commutator motor cleaner and the brushless motor cleaner of the present invention are equivalent, the brushless motor cleaner of the present invention can obtain the suction work rate equivalent to that of the conventional commutator motor cleaner. At the same time, it can solve the problems of the motor life limitation due to the brush life or the generation of carbon fines, which has been a problem with conventional commutator motor cleaners, and has high suction performance, long life, and clean exhaust. A vacuum cleaner can be realized.

[Example 1]
FIG. 1 shows a brushless motor driving device for a vacuum cleaner. A reactor 7 connected in series to the AC power source 1, a first rectifier 9 connected to a subsequent stage of the reactor 7 and composed of a diode bridge circuit, and connected in parallel to the first rectifier 9 and connected to the AC power source 1 A booster circuit is constituted by the first switching element 10 and the first drive circuit 11 that are opened in a short circuit.

  The voltage doubler capacitors 16a and 16b are composed of a series body of a second rectifier 15 connected to the subsequent stage of the booster circuit and the reactor 7 and formed of a diode bridge circuit, and a capacitor connected in parallel to the DC side of the second rectifier 15. The converter part 2 is comprised from these.

  A motor drive circuit is composed of an inverter unit 4 that is driven by applying a rotating magnetic field to the brushless motor 3 using a DC voltage generated in the converter unit 2 as a power source, and a second drive circuit 14 of the inverter unit 4.

  Here, the inverter unit 4 includes second switching elements 13u to 13z that are three-phase bipolar connected, a flywheel diode, and the like. Specifically, 13u is an IGBT connected to the upper side of the U phase, 13v is an IGBT connected to the upper side of the V phase, 13w is an IGBT connected to the upper side of the W phase, 13x is an IGBT connected to the lower side of the U phase, and 13y is IGBTs 13z connected to the lower side of the V phase are IGBTs connected to the lower side of the W phase.

  The microcomputer 6 as an arithmetic control means detects the output signal of the zero cross point detection circuit 8 of the AC power supply, the output signal of the magnetic pole position detection circuit 5 of the brushless motor 3, and the voltage across the series body of the voltage doubler capacitors 16a and 16b. A first drive that inputs an output signal of the DC voltage detection circuit 12 and a brushless motor operation control command from a host controller (not shown), performs a predetermined control calculation, and opens the first switching element 10 of the booster circuit in a short circuit. An operation signal output to the circuit 11 and an operation signal output to the second drive circuit 14 that drives the brushless motor 3 by PWM are performed.

  Next, the detailed operation of the converter unit 2 will be described. Since the converter unit 2 with the first switching element 10 left open is a normal voltage doubler rectifier circuit, when the voltage of the AC power supply 1 is 100 V, the obtained DC voltage is theoretically 100 × 1.41. X2 = 282 (V).

  However, since there is a voltage drop of the reactor 7 or the like, the voltage is about 230 V when the brushless motor 3 is driven. Further, in the converter unit 2 in which the first switching element 10 remains open, the input current from the AC power supply 1 remains in the capacitor input type, so that the peak value of the input current is high and the circuit power factor is poor. At the same time, harmonic current is also generated.

Therefore, the power factor is improved using a booster circuit. The operation of the booster circuit will be described with reference to FIG. The zero-crossing point of the input voltage is detected by the zero-crossing detection circuit 8, and the first switching element 10 is short-circuited after a preset delay time T ₁ of about 500 μs.

Furthermore, after the short time _{T 2,} to open the first switching element 10. Thereafter, the next zero cross point is detected, and this operation is repeated. Since the degree of boosting of the short circuit and the time T ₂ the longer the DC voltage is increased, to increase or decrease the short time T ₂ as detected DC voltage becomes a target DC voltage set in advance by the DC voltage detection circuit 12. With this short circuit opening control of the first switching element 10, an efficient operation that suppresses the peak value of the input current is performed, and the power factor that increases the energization phase angle of the input current (the conduction time during the half cycle of the power supply frequency) is increased. Perform improved driving.

  FIG. 3 shows the characteristics of the booster circuit of this embodiment. These are experimental results representing the relationship between the DC voltage, the short-circuit time, the power factor, and the input current when the brushless motor 3 is driven so that the input power is kept constant at 1000 W in the 100 V AC power supply 1.

  As shown in FIG. 3A, the DC voltage can be increased by increasing the short circuit time. When the DC voltage is controlled to about 250 V, the power factor becomes maximum (see FIG. 3B) and the input current becomes minimum (see FIG. 3C). The smaller the current, the smaller the loss generated by the electrical resistance of the reactor 7 and the second rectifier 15 that are components through which the input current flows, so the circuit efficiency of the converter unit 2 is improved. That is, in this case, the target DC voltage may be set in advance as 250V.

  Next, the reactor 7 will be described in detail. FIG. 4 is a result of experiments using several types of reactors having different inductances (reactor characteristic diagram).

  FIG. 4A shows the relationship between the reactor inductance and the power factor of power when the power consumption is 1000 W and there is no booster circuit and when there is a booster circuit. In the case of a conventional brushless motor cleaner without a booster circuit, it was necessary to increase the inductance of the reactor in order to increase the power factor. However, when the booster circuit is used, the overall power supply power Since the rate can be greatly improved, the inductance of the reactor can be reduced as compared with a conventional brushless motor cleaner without a booster circuit.

  FIG. 4B shows the relationship between the reactor inductance and the power source power factor with the power consumption as a parameter when a booster circuit is used. From the figure, in order to obtain a high power factor of 90% or more in a full load state with power consumption of about 1000 W, the reactor inductance should be approximately 1 mH or more. On the other hand, in order to obtain a high power factor of 90% or more in a half load state with power consumption of about 500 W, the reactor inductance needs to have a value of approximately 6 mH or more.

  Considering application to general vacuum cleaners, the power source power factor in the full load state is important, and even if the power factor drops slightly in the half load state, the power consumption itself is not large, so the input current The absolute value of is small, the influence on the power harmonics and the heat generation of the power cord are small, and there is no particular problem.

  In order to increase the inductance, it is necessary to increase the number of turns of the reactor in proportion to the inductance. However, if the core size of the reactor is constant, it is necessary to reduce the cross-sectional area by reducing the wire diameter. The winding resistance increases in proportion to the square of the inductance, and thus the copper loss increases. Alternatively, if the core size of the reactor is increased to avoid thinning the wire diameter, the exciting current increases with the expanded core size, thus increasing the iron loss. Thus, if inductance is enlarged, the copper loss and iron loss of a reactor will increase, and circuit efficiency will fall.

  However, although the above is compared with the case where the input current is constant, the power source power factor generally increases as the inductance increases, so the input current decreases for the same output, and the reduction in circuit efficiency is mitigated.

  FIG. 4C shows the relationship between the inductance of the reactor in the full load state (power consumption 1000 W) and the circuit efficiency. From the figure, the circuit efficiency is maximized at about 3 mH.

  Next, FIG. 4D shows the relationship between the inductance and the weight of the reactor. In order to increase the inductance of the reactor, the reactor tends to increase in size and weight, but considering the burden and operability during transportation of the vacuum cleaner, the reactor also needs to be lighter and smaller.

  4C and 4D, in the case of a household vacuum cleaner of 1000 W class, it is desirable that the inductance of the reactor is approximately 1 to 3 mH in consideration of both circuit efficiency and weight.

  Next, the detailed operation of the inverter unit 4 will be described. Electric power for operating the brushless motor for a vacuum cleaner is supplied from an AC power source 1 connected to the motor driving device. The AC input is converted to DC by the converter unit 2 and input to the inverter unit 4. The microcomputer 6 calculates and generates a PWM waveform for driving the brushless motor 3 using the position signal from the rotor position detector 5 and outputs it to the second drive circuit 14.

  Therefore, the PWM waveform is converted into an IGBT drive voltage, and IGBT switching of 13u, 13v, 13w, 13x, 13y, and 13z is performed. Thus, by supplying electric power from the inverter unit 4 to the brushless motor 3, the brushless motor 3 is rotationally driven to operate the cleaner.

  Here, the inverter unit 4 is a 120-degree conduction type PWM inverter, and the relationship between the rotor position signal and the inverter drive signal is as shown in FIG. The microcomputer 6 creates an inverter drive signal based on the rotor position signal. For example, when the rising edge of the rotor position signal Hu is detected, the inverter drive signal turns on the switching element on the upper side of the U phase (13u in FIG. 1). Next, when the rising edge of Hv is detected, the switching element 13u on the upper side of the U phase is turned off, and the switching element 13v on the upper side of the V phase is turned on.

  When a falling signal of Hw is detected, the switching element 13z on the lower side of the W phase is commutated from the switching element 13y on the lower side of the V phase. Thus, every time the edge of the rotor position signal is detected, the switching elements of the inverter circuit are sequentially commutated to drive the brushless motor.

  Further, in order to control the rotation speed and torque, the motor applied voltage and current are controlled by superimposing PWM chopping on the drive signal. In other words, by applying PWM modulation to the DC voltage, when the PWM duty ratio is small, the motor applied voltage becomes small and the motor output becomes small. Conversely, when the PWM duty ratio is large, the motor applied voltage also increases and the motor output also increases.

Here, the motor applied voltage, DC voltage and PWM duty ratio are:
Motor applied voltage (V) = DC voltage (V) x PWM duty ratio x K
There is a relationship. K is a proportionality constant obtained from the energization width of the drive signal,
K = energization angle / 180.

  Therefore, in the 120-degree conduction type PWM inverter of this embodiment, K = 120/180 = 2/3.

  From this relationship, the voltage utilization rate of the inverter section is maximized when the PWM duty ratio is 100% (1.0).

  In the case of a brushless motor driving device that does not have a booster circuit in the converter unit, when the PWM duty ratio reaches 100%, the motor applied voltage cannot be increased any more, and the motor output reaches the limit. The relationship between the rotor position signal and the inverter drive signal when the PWM duty ratio is 100% is as shown in FIG.

  On the other hand, in the case of a brushless motor driving apparatus having a booster circuit in the converter as in this embodiment, the motor applied voltage is increased by boosting the DC voltage with the booster circuit even after the PWM duty ratio reaches 100%. It is possible to increase the motor output.

However, as shown in FIG. 3, if the DC voltage is boosted greatly, the circuit efficiency of the converter section decreases. Therefore, the boosting of the DC voltage should be in a range where the power factor does not decrease.
Considering the circuit efficiency of the converter unit, when the DC voltage is 250 V, the maximum value of the motor applied voltage is
Motor applied voltage maximum value (V) = 250 (V) × 1.0 × 2 / 3≈167 (V)
It becomes.

  Next, the brushless motor will be described in detail. FIG. 7 shows electric constants of two brushless motors, motor A and motor B. The motor A is an example of a conventional brushless motor for a vacuum cleaner, and the motor B is a brushless motor for a vacuum cleaner of this embodiment.

  The motors A and B have the same shape and the same material except that the number of windings of the stator is different. Since the number of turns of the motor B is about twice that of the motor A, the induced voltage constant, inductance, and winding resistance are both about twice.

  In addition, an experiment was performed with a combination of the brushless motor driving circuit shown in FIG. 8 and the brushless motor shown in FIG. 7, and the experimental results when the PWM duty ratio (conduction ratio) was 100% at the maximum or the power consumption was 1000 W were obtained. As shown in FIG.

  Since the circuit A is a full-wave rectifier circuit, when the voltage of the AC power supply is 100 V, the obtained DC voltage is theoretically the maximum value of the power supply voltage 100 × 1.41 = 141 (V). However, due to the voltage drop of the reactor, etc., it becomes about 115V when the brushless motor is driven.

  As described for the converter unit 2, the circuit B has a DC voltage of 250 V due to the voltage doubler rectifier circuit and the booster circuit.

  Experiment No. 1 is an example of a conventional inverter cleaner. 4 is the inverter cleaner of this embodiment. Experiment No. 2 and No. 3 is reference data.

  Experiment No. 1 and Experiment No. 4, the induced voltage constant of the motor B is about twice that of the motor A, so the motor applied voltage is about twice, but conversely, the motor current is about ½. Here, the loss of the inverter unit 4 is more influenced by the increase / decrease of the motor current than the increase / decrease of the motor applied voltage. When the motor current becomes about ½, the loss of the inverter unit also becomes about ½. Therefore, the circuit efficiency is also improved.

  In addition, Experiment No. With the combination of 2, the matching between the motor and the circuit is poor, and the PWM duty ratio reaches 100% (1.0) at a power consumption of 500 W, and the output cannot be increased any more. Therefore, Experiment No. When the motor drive device of the combination of 2 is mounted on the vacuum cleaner, the maximum value of the suction work rate is smaller than that of other combinations.

  Furthermore, Experiment No. With the combination of 3, since the PWM duty ratio has not reached 100%, it is possible to further increase the rotational speed, obtain a large power consumption, and realize a large suction work rate. Considering the risk of breakers falling when a product other than a vacuum cleaner is used at the same time with the same AC power source when performing the operation, further increase in power consumption is not desirable for household appliances.

  When compared with the same power consumption of 1000 W, Experiment No. The circuit efficiency of No. 3 is shown in Experiment No. 4 is much inferior to 4, so the suction power is also the same as that of Experiment No. 3 is Experiment No. Less than 4.

  Thus, the preset maximum consumption when the voltage utilization factor of the inverter section is maximum (PWM duty ratio 100% in this embodiment) at the DC voltage (250 V in this embodiment) with the best power factor. If the electric constant of the motor is optimized and designed so that the electric power (1000 W in this embodiment) is obtained, the circuit efficiency can be greatly improved as compared with the conventional example.

  Further, by setting the PWM duty ratio to 100% (1.0), in addition to circuit effects such as switching loss reduction and switching noise reduction of the inverter section, motor current ripple caused by switching is caused by motor current ripple. Iron loss can be reduced and motor efficiency can be improved.

  FIG. 10 shows an example of the experimental results of the efficiency and suction power of each part of the commutator motor cleaner, the brushless motor cleaner (conventional example), and the brushless motor cleaner (this embodiment). According to this embodiment, the circuit efficiency is greatly improved as compared with the conventional example. (In FIG. 10, it is improved from 83% to 93%.)

  That is, the difference in circuit efficiency (5% in FIG. 10) between the commutator motor cleaner and the brushless motor cleaner (this embodiment) is smaller, and the motor efficiency is higher for the brushless motor than for the commutator motor (FIG. 10). Therefore, if the fan efficiency is equivalent (65% in FIG. 10), the brushless motor cleaner (this example) has the same suction power (FIG. 10) as the commutator motor cleaner. Then, about 540 W) is obtained.

[Example 2]
In the first embodiment, the converter unit performs voltage doubler rectification, and the booster circuit is a booster circuit that forcibly short-circuits the AC power supply via a reactor connected in series on the power supply side. A method generally called an active filter method as disclosed in 3 may be used.

  This is based on a switching high-frequency PWM signal in which the converter unit performs full-wave rectification, and a reactor and a step-up chopper circuit are provided between the full-wave rectifier circuit and the inverter unit, and controls the accumulation and release of energy with respect to the reactor. By controlling the switching on and off of the switch, control is performed so that a current proportional to the input voltage flows through the input line, and power factor improvement and boosting are performed. In addition, if other parts such as the inverter unit and the brushless motor are made the same as in the first embodiment, the same effect as in the first embodiment can be obtained.

[Example 3]
In the first embodiment, the inverter unit is a 120-degree conduction type PWM inverter, but the conduction width need not be limited to 120 degrees, and may be a 150-degree conduction type PWM inverter.

Similarly to the 120-degree conduction type PWM inverter, the 150-degree conduction type PWM inverter also maximizes the inverter voltage utilization when the PWM duty ratio is 100% (1.0), and considers the circuit efficiency of the converter part. When the DC voltage is 250V, the maximum value of the motor applied voltage is
150-degree conduction type motor applied voltage maximum value (V) =
250 (V) × 1.0 × 150 / 180≈208 (V)
It becomes.

  Thus, the maximum motor applied voltage (for example, 208 V) of the 150-degree conduction type PWM inverter having a wider conduction width than the 120-degree conduction type PWM inverter is the maximum motor applied voltage (for example, 167 V) of the 120-degree conduction type PWM inverter. Therefore, the electric constant of the motor may be optimized and designed so that the power consumption in the full load state preset in this condition (1000 W in the first embodiment) is obtained. Specifically, the number of winding turns may be made larger than that of the motor B in FIG.

  Furthermore, the inverter unit may be a 180 degree sine wave PWM inverter instead of a 120 degree conduction type PWM inverter. In this case, the voltage utilization rate of the inverter unit is maximized when the modulation rate is 100%, but the maximum power consumption (1000 W in the first embodiment) set in advance under the condition of the maximum motor applied voltage at this time is obtained. What is necessary is just to optimize the electrical constant of the motor.

  For other parts such as the converter section, the same effects as those of the first embodiment can be obtained if they are the same as those of the first embodiment.

[Example 4]
In the first embodiment, by increasing the number of winding turns as compared with the conventional example, the power factor of the AC power supply is better than that in the case where the boosting circuit of the converter unit does not perform boosting at a predetermined value of power consumption. When the DC voltage is boosted, the electric constant of the brushless motor is optimized and designed so that the voltage usage rate of the inverter is maximized. The design is not limited to the linearity or the number of turns, and the design may be optimized by adjusting the induced voltage constant by changing the amount or type of the rotor magnet.

  In addition, if other parts such as the converter unit and the inverter unit are the same as those in the first embodiment, the same effects as those in the first embodiment can be obtained.

  In addition, this invention is not limited to the said embodiment, Of course, many corrections and changes can be added to the said embodiment within the scope of the present invention.

The electric vacuum cleaner which concerns on this invention WHEREIN: The figure which shows schematic structure of the brushless motor drive device for vacuum cleaners. The figure for demonstrating operation | movement of the pressure | voltage rise circuit of the vacuum cleaner which concerns on this invention. The figure which shows the characteristic of the pressure | voltage rise circuit of the vacuum cleaner which concerns on this invention. The figure for demonstrating the reactor used for the booster circuit of this invention. The figure which shows the relationship between the rotor position signal and inverter drive signal in this invention. The figure which shows a rotor position signal and an inverter drive signal in case the PWM duty ratio in this invention is 100%. The figure which shows the electrical constant of a prior art example, this invention, and a brushless motor. The figure which shows the structure of the drive circuit of a prior art example, this invention, and a brushless motor. The figure which shows the experiment result of the brushless motor drive of a prior art example and this invention. The figure which shows an example of the experimental result of the efficiency and suction | inhalation work rate of each part of a commutator motor cleaner, a brushless motor cleaner (conventional example), and a brushless motor cleaner (this invention).

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 AC power supply 2 Converter part 3 Brushless motor 4 Inverter part 5 Magnetic pole position detection circuit 6 Microcomputer 7 Reactor 8 Zero cross point detection circuit 9 1st rectifier 10 1st switching element 11 1st drive circuit 12 DC voltage detection circuit 13u-13z 2nd Switching element 14 Second drive circuit 15 Second rectifier 16a, 16b Voltage doubler capacitor

Claims (5)

An electric blower having a blower fan and having a built-in brushless motor for driving the blower fan;
A control unit for controlling the brushless motor;
A converter unit that rectifies an AC voltage supplied from an AC power source and converts it into a DC voltage; and a power source unit that includes an inverter unit that converts the DC voltage into an AC voltage and supplies the AC voltage to the brushless motor;
In the vacuum cleaner with
In addition to optimizing the electric constant of the brushless motor so that the voltage utilization rate of the inverter is substantially maximized under the operating load condition in which the power consumption of the brushless motor becomes a predetermined power consumption value during operation of the vacuum cleaner. ,
A vacuum cleaner characterized in that a booster circuit is provided in the converter section and the DC voltage is boosted by the booster circuit to improve the power factor of the AC power supply. The inverter unit controls the rotation speed of the brushless motor by a PWM control method,
2. The electric vacuum cleaner according to claim 1, wherein the electric constant of the brushless motor is designed so that the voltage utilization rate of the inverter is maximized when the PWM duty ratio is 100%. The converter unit performs voltage doubler rectification,
3. The electric circuit according to claim 1, wherein the booster circuit is a booster circuit for forcibly short-circuiting the AC power supply via a reactor connected in series to the AC power supply side of the power supply unit. Vacuum cleaner.   The vacuum cleaner according to claim 3, wherein an inductance of the reactor is 1 to 3 mH. The vacuum cleaner according to any one of claims 1 to 4, wherein the predetermined power consumption value is 1000W.