JP2020032258A - Vacuum cleaner - Google Patents

Abstract

To realize high efficiency in a vacuum cleaner mounting an electric blower for receiving power supply from a power storage device.SOLUTION: A control device (5) calculates a first power loss to be generated in a vacuum cleaner when an AC motor (4) is driven by selecting boosting operation and a second power loss to be generated in the vacuum cleaner when the AC motor (4) is driven by selecting non-boosting operation. When the first power loss is larger than the second poser loss, the control device (5) controls a boosting converter (2) and an inverter (3) so as to drive the AC motor (4) by performing the non-boosting operation. When the first power loss is smaller than the second power loss, the control device (5) controls the boosting converter (2) and the inverter (3) so as to drive the AC motor (4) by performing the boosting operation.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a vacuum cleaner.

  2. Description of the Related Art An electric vacuum cleaner including a power storage device and an electric blower that receives power supplied from the power storage device and generates a suction force is known. For example, Japanese Patent Laying-Open No. 2015-342 (Patent Document 1) discloses a vacuum cleaner provided with a motor that receives power supplied from a battery and drives an impeller of a suction source. According to this, an inverter is provided between the battery and the motor. The inverter converts a DC voltage supplied from a battery into an AC voltage for driving a motor.

  In the above vacuum cleaner, when the motor is driven at a high rotation speed, the back electromotive force increases and the induced voltage increases, so that the voltage (required voltage) to be applied to the motor increases. Therefore, the required voltage may exceed the outputtable voltage of the inverter, so-called voltage saturation may occur.

  With respect to such voltage saturation, for example, Japanese Patent Application Laid-Open No. 2004-135835 (Patent Document 2) discloses a vacuum cleaner configured to increase the outputtable voltage of an inverter by using a boost converter. Is disclosed.

JP 2015-342 A JP-A-2004-135835

  The vacuum cleaner described in Patent Literature 2 is configured to switch between a non-boost operation mode in which the boost converter is not operated and a boost operation mode in which the boost converter is operated. In the non-boosting operation mode, the electric blower is driven by the output voltage of the battery. On the other hand, in the boost operation mode, the electric blower is driven by the output voltage boosted by the boost converter. In Patent Literature 2, the non-boosting operation mode is set when the weak operation button is operated, and the boosting operation mode is set when the strong operation button is operated.

  In the configuration disclosed in Patent Document 2 in which the output voltage of the boost converter is converted into an AC voltage by an inverter to drive the electric blower, each component of the vacuum cleaner according to the voltage level of the output voltage of the boost converter. Power loss changes. Therefore, the efficiency of the whole vacuum cleaner also changes.

  However, Patent Document 2 does not disclose or suggest controlling the boost converter in consideration of the efficiency of the entire vacuum cleaner.

  Therefore, a main object of the present invention is to achieve high efficiency in a vacuum cleaner equipped with an electric blower that receives power supply from a power storage device.

  A vacuum cleaner according to an aspect of the present invention includes an electric blower that generates a suction force. The vacuum cleaner includes an AC motor, a power storage device, a boost converter, an inverter, and a control device. The AC motor is configured to drive an electric blower. The boost converter is configured to boost a DC voltage received from the power storage device. The inverter is configured to convert an output voltage of the boost converter into an AC voltage for driving the AC motor. The control device is configured to control the boost converter and the inverter. The boost converter is configured to selectively execute a boost operation and a non-boost operation. The step-up operation is an operation in which a step-up rate indicated by a ratio of an output voltage to a voltage of a power storage device is higher than 1. The non-boost operation is an operation in which the boost ratio is fixed at one. In the case where the required suction force is generated in the electric blower, the control device is configured to control the first electric power loss that occurs in the vacuum cleaner when the AC motor is driven by selecting the boost operation and the AC motor that is selected by the non-boost operation. And the second electric power loss that occurs in the vacuum cleaner when is driven. When the first power loss is larger than the second power loss, the control device controls the boost converter and the inverter such that the non-boost operation is performed to drive the AC motor. On the other hand, when the first power loss is smaller than the second power loss, the control device controls the boost converter and the inverter to drive the AC motor by performing the boost operation.

  According to one aspect of the present invention, high efficiency can be realized in a vacuum cleaner equipped with an electric blower that receives power supply from a power storage device.

It is a figure which shows the whole structure of the vacuum cleaner according to Embodiment 1 of this invention. FIG. 3 is a block diagram illustrating a configuration of a power supply unit. FIG. 3 is a circuit diagram showing a configuration of a boost converter and an inverter. FIG. 3 is a functional block diagram illustrating a control configuration related to control of a boost converter in the vacuum cleaner according to the first embodiment. 5 is a flowchart illustrating control of a boost converter in the vacuum cleaner according to the first embodiment. It is a figure explaining control of a boosting rate at the time of boost operation. FIG. 13 is a functional block diagram illustrating a control configuration related to control of a boost converter in a vacuum cleaner according to a second embodiment. 9 is a flowchart illustrating boost rate control in the vacuum cleaner according to the second embodiment. FIG. 13 is a functional block diagram illustrating a control configuration related to control of a boost converter in a vacuum cleaner according to a third embodiment. It is a figure for explaining a temperature rise operation performed by a control device. 13 is a flowchart illustrating a temperature increasing operation performed in the vacuum cleaner according to the third embodiment.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the drawings, the same or corresponding portions have the same reference characters allotted, and description thereof will not be repeated.

Embodiment 1 FIG.
(Structure of vacuum cleaner)
FIG. 1 is a diagram showing an overall configuration of a vacuum cleaner 100 according to Embodiment 1 of the present invention. FIG. 1A is a front view of the vacuum cleaner 100, and FIG. 1B is a side view of the vacuum cleaner 100.

  FIG. 1 shows a stick cleaner as an example of the vacuum cleaner 100. The vacuum cleaner 100 is not limited to a stick cleaner, and may be, for example, a canister-type vacuum cleaner configured by connecting an extension pipe to a cleaner main body having an electric blower, a dust collecting unit, and a power supply unit.

  Referring to FIG. 1A, vacuum cleaner 100 includes power supply unit 104, electric blower 106, dust collection chamber 108, extension pipe 111, and suction unit 112. The power supply unit 104, the electric blower 106, and the dust collection chamber 108 are housed in a housing 110. A handle 102 is connected to one end of the housing 110. An extension tube 111 is connected to the other end of the housing 110.

  Power supply unit 104 includes battery B and substrate 116. Battery B is shown as a typical example of a power storage device configured to be rechargeable. Battery B is, for example, a secondary battery such as a nickel-metal hydride battery or a lithium-ion battery. As the power storage device, an electric double layer capacitor or the like can be used.

  The board 116 implements a motor drive device that drives the electric blower 106 using the electric power stored in the battery B, as described later. The board 116 includes a power converter for converting DC power supplied from the battery B into AC power for driving the electric blower 106.

  The electric blower 106 is arranged on a ventilation path 113 provided in the housing 110. The electric blower 106 receives electric power from the battery B and draws it into the ventilation passage 113 to apply a negative pressure. The electric blower 106 drives an AC motor (see FIG. 2) as a blower motor.

  The dust collection chamber 108 communicates with the extension pipe 111. The suction section 112 is connected to a distal end of the extension tube 111. The suction unit 112 sucks dust on the surface to be cleaned from the suction port 114.

  When the AC motor is driven, the electric blower 106 generates a suction negative pressure. Due to the suction negative pressure, dust on the surface to be cleaned is sucked into the suction portion 112 together with air. The air containing the dust is conveyed to the dust collection chamber 108 through the extension pipe 111. Dust in the air is collected in the dust collection chamber 108. The air from which the dust is collected flows through the ventilation passage 113, passes through a filter (not shown), and reaches the electric blower 106. Thereafter, the air is discharged from the exhaust port to the outside of the housing 110 through the ventilation passage 113.

  The handle 102 is provided with an operation unit 13 and a display unit 14. The operation unit 13 includes a plurality of operation switches for driving the electric blower 106 by a motor driving device described later. The plurality of operation switches include an operation switch for starting or stopping suction cleaning and an operation switch for switching various operation modes. The operation switches for switching the operation mode include, for example, operation switches for switching the suction force generated in the electric blower 106, such as strong operation, medium operation, and weak operation.

  The display unit 14 displays the operation state of the electric vacuum cleaner 100 (operation mode, state of the battery B (charge state), and the like). As will be described later, the display unit 14 is configured to display an indication when the operation is stopped to prevent the battery B from overheating. In addition, the display unit 14 is configured to, when the vacuum cleaner 100 is started, perform a temperature raising operation for raising the temperature of the battery B and display a message to that effect. In addition, the display unit 14 is not limited to the form installed on the handle 102, and may be provided at another position.

(Configuration of power supply unit)
Next, the configuration of the power supply unit 104 in FIG. 1 will be described with reference to FIGS.

  Referring to FIG. 2, substrate 116 is provided between battery B and AC motor 4 of electric blower 106, and forms a motor driving device that receives AC power from battery B and drives AC motor 4. I do.

  Specifically, substrate 116 includes power switch 6, boost converter 2, inverter 3, and control device 5. Power switch 6 is provided between battery B and boost converter 2. The power switch 6 is on / off controlled based on a control signal φs1 from the control device 5. The power switch 6 electrically connects the battery B to the boost converter 2 in an on (conducting) state, and electrically disconnects the battery B from the boost converter 2 in an off (cut off) state. When an operation switch for starting suction cleaning is operated in the operation unit 13, the power switch 6 is turned on, and when an operation switch for stopping suction cleaning is operated, the power switch 6 is turned off.

  Boost converter 2 controls output voltage (= voltage between positive electrode line PL2 and negative electrode line NL) Vdc based on control signal φc from control device 5 in accordance with voltage command value Vdc *. With respect to voltage VB of battery B, boost converter 2 controls output voltage Vdc in a range of Vdc ≧ VB. That is, boost converter 2 has a function of boosting voltage VB of battery B.

  Inverter 3 is connected between boost converter 2 and AC motor 4. Inverter 3 is configured to convert output voltage Vdc of boost converter 2 into an AC voltage for driving AC motor 4 based on control signal φi from control device 5. For example, control device 5 generates control signal φi such that the output torque of AC motor 4 is controlled according to the torque command value.

  The AC motor 4 is, for example, a three-phase permanent magnet type synchronous motor including a rotor in which permanent magnets are embedded. The AC motor 4 is configured such that one ends of three coils of U, V, and W phases (not shown) are commonly connected to a neutral point. The AC motor 4 generates a torque for rotationally driving the electric blower 106. In addition, in the example of FIG. 2, the AC motor 4 is configured by a three-phase AC motor, but may be a single-phase AC motor.

  FIG. 3 is a circuit diagram showing a configuration of boost converter 2 and inverter 3.

  Referring to FIG. 3, boost converter 2 is configured by a so-called boost chopper circuit. Specifically, boost converter 2 includes a reactor L1, a semiconductor switching element (hereinafter, also simply referred to as "switching element") Q7, diodes D7 and D8, a capacitor C1, and a bypass switch 16.

  Reactor L1 has one end connected to positive line PL1, and the other end connected to an anode of diode D8. The canode of diode D8 is connected to positive line PL2. Switching element Q7 has a collector connected to a connection node between reactor L1 and diode D8, and an emitter connected to negative line NL. Diode D7 is connected in anti-parallel to switching element Q7. ON / OFF of the switching element Q7 is controlled by a control signal φc from the control device 5. Capacitor C1 is connected between positive electrode line PL2 and negative electrode line NL. Capacitor C1 smoothes the AC component of the voltage fluctuation between positive electrode line PL2 and negative electrode line NL.

  The bypass switch 16 is electrically connected in parallel with the reactor L1. On / off of the bypass switch 16 is controlled based on a control signal φs2 from the control device 5. Bypass switch 16 connects positive electrode line PL1 to the anode of diode D8 while bypassing reactor L1 in the on state.

  Boost converter 2 is configured to selectively execute a boost operation and a non-boost operation. In the boost operation, boost converter 2 is controlled to turn on / off switching element Q7. Specifically, in the ON period Ton of the switching element Q7, energy is accumulated in the reactor L1 by forming a current path through the battery B-reactor L1-switching element Q7. On the other hand, in the OFF period Toff of the switching element Q7, a current path is formed via the battery B, the reactor L1, the diode D8, and the capacitor C1. Thus, the energy stored in reactor L1 during ON period Ton is supplied to capacitor C1. Thus, voltage VB of battery B is boosted and output between positive electrode line PL2 and negative electrode line NL.

  Boost converter 2 can control the boost ratio by controlling the duty ratio of switching element Q7 (the ratio of ON period Ton to switching cycle T (= Ton + Toff)). The boosting rate is represented by a ratio (= Vdc / VB) of output voltage Vdc of boosting converter 2 to voltage VB of battery B.

  Control device 5 controls on / off of switching element Q7 according to the duty ratio calculated based on the detected values of voltages VB and Vdc and voltage command value Vdc *. Specifically, when output voltage Vdc is lower than voltage command value Vdc *, output voltage Vdc can be increased by increasing the duty ratio. On the other hand, when the output voltage Vdc is higher than the voltage command value Vdc *, the voltage Vdc can be reduced by reducing the duty ratio. As described above, in the step-up operation, Vdc *> VB is set, and the step-up ratio can be made higher than 1 by the on / off control of the switching element Q7.

  On the other hand, in the non-step-up operation, the AC motor 4 is controlled in a state of Vdc = VB without stepping up by the step-up converter 2. That is, in the non-boost operation, the boost ratio is fixed at 1. In the non-step-up operation, the switching element Q7 is fixed to be off, so that the power loss in the step-up converter 2 is reduced.

  In the non-boosting operation, the bypass switch 16 is further fixed to ON. Thus, the voltage VB of the battery B is supplied to the inverter 3 through the bypass switch 16 and the diode D8. By sending the current to the inverter 3 without passing through the reactor L1, the power loss in the boost converter 2 is further reduced as compared with the case where the switching element Q7 is fixed off.

  Inverter 3 has a circuit configuration of a three-phase inverter. Inverter 3 includes a U-phase arm, a V-phase arm, and a W-phase arm connected in parallel between positive electrode line PL2 and negative electrode line NL. U-phase arm includes switching elements Q1 and Q2 connected in series between positive electrode line PL2 and negative electrode line NL. V-phase arm includes switching elements Q3 and Q4 connected in series between positive electrode line PL2 and negative electrode line NL. W-phase arm includes switching elements Q5 and Q6 connected in series between positive electrode line PL2 and negative electrode line NL. The midpoint of each phase arm is connected to each phase coil of AC motor 4.

  When DC voltage Vdc is supplied from boost converter 2, inverter 3 converts DC voltage Vdc to AC voltage by switching operation of switching elements Q1 to Q6 in response to control signal φi from control device 5, and converts the AC voltage to 4 is driven.

  As the switching elements Q1 to Q7, for example, an IGBT (Insulated Gate Bipolar Transistor), a MOS (Metal Oxide Semiconductor) transistor, or the like can be used. Diodes D1 to D7 are connected in antiparallel to switching elements Q1 to Q7, respectively.

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

  Returning to FIG. 2, power supply unit 104 further includes voltage sensors 7, 8, 9, current sensors 10, 11, temperature sensor 12, and rotation angle sensor 15.

  Voltage sensor 7 detects voltage VB of battery B (hereinafter, also referred to as battery voltage) and outputs the detected value to control device 5. Voltage sensor 8 detects output voltage Vdc of boost converter 2 and outputs the detected value to control device 5. Output voltage Vdc corresponds to the DC link voltage of inverter 3. Voltage sensor 9 detects an applied voltage Vm to AC motor 4 (hereinafter, also referred to as a motor voltage), and outputs the detected value to control device 5.

  Current sensor 10 detects current IB flowing through battery B (hereinafter, also referred to as battery current) and outputs the detected value to control device 5. Temperature sensor 12 detects temperature TB of battery B (hereinafter, also referred to as battery temperature) and outputs the detected value to control device 5. Current sensor 11 detects a current Im (hereinafter, also referred to as a motor current) flowing through AC motor 4, and outputs a detected value to control device 5.

  Rotation angle sensor 15 detects rotor rotation angle θ of AC motor 4 and outputs the detected value to control device 5. Control device 5 can calculate rotation speed Nm of AC motor 4 based on rotation angle θ. The rotation angle sensor may be omitted by directly calculating the rotation angle θ from the motor voltage Vm or the motor current Im.

  The control device 5 is configured based on a processor including a CPU (Central Processing Unit) and a memory (not shown), and performs an arithmetic process using a detection value of each sensor based on a map and a program stored in the memory. It is configured as follows. Alternatively, at least a part of the control device 5 may be configured to execute a predetermined numerical / logical operation process by hardware such as an electronic circuit.

  Control device 5 controls boost converter 2 and inverter 3 based on an operation command input from operation unit 13, a detection value of each sensor, and the like. That is, control device 5 generates control signals φc and φs2 based on the operation command and the detection value of each sensor, and outputs them to boost converter 2. Further, control device 5 generates control signal φi based on the operation command and the detection value of each sensor, and outputs it to inverter 3.

  Here, as described above, boost converter 2 is configured to selectively execute a boost operation and a non-boost operation. Control device 5 selectively performs a boosting operation and a non-boosting operation in accordance with power loss generated in vacuum cleaner 100 for control of boost converter 2. Hereinafter, control of boost converter 2 in control device 5 will be described.

(Control of boost converter)
FIG. 4 is a functional block diagram illustrating a control configuration related to control of boost converter 2 in vacuum cleaner 100 according to the first embodiment. Each functional block described in the functional block diagrams described below including FIG. 4 is realized by hardware or software processing by the control device 5.

  Referring to FIG. 4, control device 5 includes a power loss calculation unit 20, a voltage command value generation unit 22, and a switching control unit 24.

  When receiving the operation command from the operation unit 13, the power loss calculation unit 20 is required to cause the electric blower 106 to generate the suction force specified by the operation command (hereinafter, also referred to as “required suction force”). The output (rotation speed × torque) of the AC motor 4 is set.

  For example, when an operation switch for setting a strong operation is operated on operation unit 13, power loss calculation unit 20 sets an output request to AC motor 4 to an output corresponding to the strong operation mode. On the other hand, when the operation switch for the middle operation setting is operated on the operation unit 13, the power loss calculation unit 20 sets the output request to an output corresponding to the middle operation mode. Further, when the operation switch for weak operation setting is operated on the operation unit 13, the power loss calculation unit 20 sets the output request to an output corresponding to the weak operation mode. The output request in the weak operation mode is the smallest, and the output request in the strong operation mode is the largest.

  When an output request to AC motor 4 is set in response to an operation command from operation unit 13, power loss calculation unit 20 calculates voltage command value Vdc * in accordance with the set output request.

  In the AC motor 4, when the rotation speed and / or the torque increases, the back electromotive force increases and the induced voltage increases, so that the required voltage increases. Accordingly, output voltage Vdc of boost converter 2 needs to be set higher than this required voltage. On the other hand, boosting of boost converter 2 has a limit, and output voltage Vdc has an upper limit. Therefore, power loss calculating section 20 sets voltage command value Vdc * within a voltage range from the required motor voltage (induced voltage) to the maximum output voltage of boost converter 2. Voltage command value Vdc * is set higher than battery voltage VB (Vdc *> VB). That is, boost converter 2 performs a boost operation.

  Note that as the output request for the AC motor 4 increases, the required motor voltage (induced voltage) increases. Therefore, the required motor voltage corresponding to the output request in the strong operation mode is higher than the required motor voltage corresponding to the output request in the weak operation mode. In an operation mode in which the required motor voltage is equal to or lower than the battery voltage VB, the output voltage Vdc can be set to the battery voltage VB. That is, boost converter 2 can execute a non-boost operation.

  Next, power loss calculating section 20 estimates power loss Ploss in vacuum cleaner 100 when AC motor 4 is driven according to the output request.

  In the estimation of the power loss Ploss, the power loss calculation unit 20 selects the step-up operation and drives the AC motor 4 to drive the power loss Ploss1 in the vacuum cleaner 100 (hereinafter, also referred to as “step-up power loss”). ) Is calculated. Boost power loss Ploss1 corresponds to the power loss in vacuum cleaner 100 when voltage command value Vdc * is set higher than voltage VB of battery B.

  The power loss calculation unit 20 calculates a power loss Ploss2 (hereinafter, also referred to as “non-boosting power loss”) generated in the electric vacuum cleaner 100 when the non-boosting operation is selected and the AC motor 4 is driven. . The non-step-up power loss Ploss2 corresponds to the power loss in the vacuum cleaner 100 when the voltage command value Vdc * is set to VB.

  Next, the calculation of the boosted power loss Ploss1 and the non-boosted power loss Ploss2 will be described in detail.

[1] Calculation of Boost Power Loss Ploss1 The power loss calculating unit 20 calculates the power loss Pbat in the battery B, the power loss Pcon in the boost converter 2, and the power in the inverter 3 when the AC motor 4 is driven by selecting the boost operation. By summing the loss Pinv and the power loss Pmot in the AC motor 4, a boosted power loss Ploss1 is calculated. That is, the boost-time power loss Ploss1 is represented by the following equation.

Ploss1 = Pbat + Pcon + Pinv + Pmot (1)
The power loss calculator 20 calculates each of the power losses Pbat, Pcon, Pinv, and Pmot by using the voltage command value Vdc * and the detection value of each sensor by the following method.

  Power loss Pbat in battery B is mainly Joule loss due to internal resistance, and is represented by Rbat · IB2 using internal resistance value Rbat and battery current IB. The internal resistance value Rbat changes depending on the battery temperature TB. Generally, the lower the battery temperature TB, the higher the internal resistance value Rbat.

  Here, the battery current IB at the time of the boost operation is obtained by superimposing the ripple current (AC component) on the average current (DC component). The ripple current increases according to the voltage difference | Vdc−VB | between the output voltage Vdc and the battery voltage VB.

  The power loss Pbat is represented by the sum of the power loss proportional to the square of the average current and the power loss proportional to the square of the ripple current. Among them, the power loss proportional to the square of the average current corresponds to the output power of the battery B, that is, the power supplied to the AC motor 4, and therefore does not change depending on the output voltage Vdc. On the other hand, the power loss proportional to the square of the ripple current increases as the voltage difference | Vdc−VB | increases.

  Therefore, for power loss Pbat, a power loss Pbat with respect to voltage command value Vdc * can be calculated by creating a map using battery temperature TB and voltage difference | Vdc-VB | as parameters in advance.

  Power loss Pcon in boost converter 2 is mainly the sum of switching loss Pconsw in switching element Q7 and loss Pconline due to wiring impedance including reactor L1 (Pcon = Pconsw + Pconline). Note that the wiring impedance is determined by the material (resistivity), cross-sectional area, and wiring length of the wiring constituting boost converter 2.

  The switching loss Pconsw is indicated by the product of the power loss per switching and the switching frequency. That is, the switching loss Pconsw becomes a value proportional to the switching frequency, and increases as the switching frequency increases. Further, under the same switching frequency, the switching loss of the switching element Q7 increases in accordance with the increase of the output voltage Vdc, so that the switching loss Pconsw increases.

  The loss Pconline due to the wiring impedance increases as the current passing through the boost converter 2 (that is, the battery current IB) increases and as the output voltage Vdc increases. When the ripple current in the battery current IB increases, the loss depending on the square of the current increases, so that the loss Pconline changes depending on the voltage difference | Vdc−VB |.

  Therefore, the power loss Pcon depends on the switching frequency and the square of the battery current IB. As described above, the average current of the battery current IB does not change depending on the output voltage Vdc. Therefore, the ripple current, that is, the voltage difference | Vdc−VB | may be mainly considered as the power loss Pcon. Therefore, the power loss Pcon with respect to voltage command value Vdc * can be calculated by creating in advance a map using the switching frequency of boost converter 2 and voltage difference | Vdc−VB | as parameters.

  Power loss Pinv in inverter 3 is mainly the sum of switching loss Pinvsw in switching elements Q1 to Q6 and loss Pinvline due to wiring impedance (Pinv = Pinvsw + Pinvline). The wiring impedance is determined by the material (resistivity), cross-sectional area, and wiring length of the wiring forming the inverter 3.

  The switching loss Pinvsw becomes a value proportional to the switching frequency of the inverter 3 similarly to the switching loss Pconsw described above. At the same torque output, the switching voltage of each switching element increases according to the increase of the output voltage Vdc, so that the switching loss Pinvsw increases. The loss Pinvline due to the wiring impedance increases as the current passing through the inverter 3 (that is, the motor current Im) increases. Therefore, under the same torque output, the motor current Im decreases as the output voltage Vdc increases, so that the loss Pinvline decreases.

  Therefore, with respect to the power loss Pinv, the power loss Pinv for the voltage command value Vdc * can be calculated by creating a map using the switching frequency of the inverter 3 and the output voltage Vdc as parameters in advance.

  The power loss Pmot in the AC motor 4 is the sum of the copper loss caused by the current flowing through the coil winding of each phase and the iron loss caused by a change in the magnetic flux of the iron core. Under the same torque output, the copper current decreases as the motor current Im decreases as the output voltage Vdc increases. Power loss Pmot can generally be estimated based on the operating state (rotational speed and torque) of AC motor 4. For example, by obtaining the relationship between the operating state and output voltage Vdc of AC motor 4 and the power loss in AC motor 4, the power loss based on the output request to AC motor 4 and voltage command value Vdc * is determined. A map for estimating Pmot can be set.

  In this manner, power loss calculating section 20 uses at least one of the operating state of AC motor 4, output voltage Vdc, battery voltage VB, battery temperature TB, and switching frequency in boost converter 2 and inverter 3 as parameters. , Power loss Pbat, Pcon, Pinv, Pmot can be estimated.

  For example, the power loss calculation unit 20 previously creates a map using the battery temperature TB and the voltage difference | Vdc−VB | as parameters, and refers to the map to determine the power loss Pbat at the voltage command value Vdc *. calculate. The power loss calculating unit 20 creates a map in which the voltage difference | Vdc−VB | and the switching frequency of the boost converter 2 are parameters in advance, and refers to the map to determine the power at the voltage command value Vdc *. Calculate the loss Pcon.

  The power loss calculation unit 20 further prepares a map in which the operating state of the AC motor 4, the output voltage Vdc, and the switching frequency of the inverter 3 are parameters in advance, and refers to the map to obtain the voltage command value Vdc *. Is calculated. In addition, power loss calculation unit 20 previously creates a map using the operating state of AC motor 4 and output voltage Vdc as parameters, and calculates power loss Pmot at voltage command value Vdc * by referring to the map. I do.

  When each of the power losses Pbat, Pcon, Pinv, and Pmot is calculated by the above-described method, the power loss calculating unit 20 substitutes the calculated power loss into the equation (1) to obtain the boosted power loss. Calculate Ploss1.

[2] Calculation of Non-Boosting Power Loss Ploss2 The power loss calculating unit 20 calculates the power loss Pbat of the battery B, the power loss Pcon of the boost converter 2, and the inverter 3 when the non-boost operation is selected and the AC motor 4 is driven. , And the power loss Pmot in the AC motor 4 are summed to calculate the non-boosting power loss Ploss2. That is, the non-step-up power loss Ploss2 is expressed by the following equation.

Ploss2 = Pbat + Pcon + Pinv + Pmot (2)
When the voltage command value Vdc * is set to the battery voltage VB (Vdc * = VB), the power loss calculation unit 20 uses the voltage command value Vdc * and the detection value of each sensor to perform the power loss Pbat by the following method. , Pcon, Pinv, and Pmot are calculated.

  Since the battery current IB during the non-boost operation is only the average current (DC component), the power loss Pbat during the non-boost operation is represented by the product of the internal resistance value Rbat and the square of the average current. Therefore, regarding the power loss Pbat, the average current (DC), that is, the operation state of the AC motor 4 and the battery temperature TB are prepared in advance as a map, so that the power loss relative to the voltage command value Vdc * (= VB) Pbat can be calculated.

  The power loss Pcon in the non-step-up operation is represented by the loss Pconline due to the wiring impedance because the switching element Q7 is fixed off (Pcon = Pconline). This loss Pconline includes conduction loss in the bypass switch 16. Power loss Pcon can also be calculated based on the average current of battery B, that is, the operating state of AC motor 4.

  As for the power loss Pinv, Pmot, similarly to the boosted power loss Ploss1, the power loss Pinv, Pmot at the voltage command value Vdc * is determined by referring to a map using the operating state of the AC motor 4 and the output voltage Vdc as parameters. Can be calculated.

  When each of the power losses Pbat, Pcon, Pinv, and Pmot is calculated by the above-described method, the power loss calculating unit 20 substitutes the calculated power loss into Expression (2) to obtain the non-boosted power. Calculate the loss Ploss2.

  When receiving the boosted power loss Ploss1 and the non-boosted power loss Ploss2 calculated by the power loss calculator 20, the voltage command value generator 22 compares the two power losses Ploss1 and Ploss2. When the boosted power loss Ploss1 is smaller than the non-boosted power loss Ploss2 (Ploss1 <Ploss2), the voltage command value generation unit 22 selects the boosting operation. In this case, voltage command value generating section 22 sets voltage command value Vdc * to a voltage corresponding to an output request to AC motor 4 and higher than battery voltage VB.

  On the other hand, when the non-boosting power loss Ploss2 is smaller than the boosting power loss Ploss1 (Ploss1> Ploss2), the voltage command value generation unit 22 selects the non-boosting operation. In this case, voltage command value generating section 22 sets voltage command value Vdc * to battery voltage VB.

  That is, voltage command value generating section 22 sets final voltage command value Vdc * based on the smaller voltage command value of boosted power loss Ploss1 and non-boosted power loss Ploss2. Thereby, voltage command value Vdc * is set such that output voltage Vdc that minimizes the power loss of vacuum cleaner 100 as a whole is obtained.

  Switching controller 24 generates control signals φs2 and φc for boost converter 2 according to voltage command value Vdc * set by voltage command value generator 22. Specifically, when Vdc *> VB, the switching control unit 24 generates the control signal φc so that the output voltage Vdc becomes equal to the voltage command value Vdc *. The switching control unit 24 further generates a control signal φs2 for fixing the bypass switch to off. In boost converter 2, the duty ratio of switching element Q7 is set in response to control signal φc, and the boost ratio is in accordance with the duty ratio.

  On the other hand, when Vdc * = VB, the switching control unit 24 generates the control signal φc so as to fix the switching element Q7 to the off state. The switching control unit 24 further generates a control signal φs2 for fixing the bypass switch to ON. Boost converter 2 supplies battery voltage VB to inverter 3 via a bypass switch and a diode.

  Switching control unit 24 further generates control signal φi for inverter 3 according to voltage command value Vdc *. By switching control of inverter 3 according to control signal φi, an AC voltage for outputting a torque according to the output request is applied to AC motor 4.

  FIG. 5 is a flowchart illustrating control of boost converter 2 in vacuum cleaner 100 according to the first embodiment.

  Referring to FIG. 5, control device 5 sets an output request (rotation speed × torque) to AC motor 4 in step S01 in accordance with the required suction force specified by the operation command. In step S02, control device 5 calculates the motor required voltage in accordance with the induced voltage of AC motor 4 according to the output request to AC motor 4. The required motor voltage is set to be equal to or higher than the induced voltage of AC motor 4.

  Subsequently, in step S03, control device 5 sets voltage command value Vdc * in a voltage range from the required motor voltage obtained in step S02 to the maximum output voltage of boost converter 2. Voltage command value Vdc * is set higher than battery voltage VB (Vdc *> VB). In step S03, a voltage command value Vdc * for boost operation is set.

  Next, in step S04, control device 5 determines whether or not the required motor voltage determined in step S02 is lower than or equal to battery voltage VB. When the required motor voltage is higher than the battery voltage VB (NO in S04), the process proceeds to step S08, and the boost operation is selected. This is because, if the required motor voltage is higher than the battery voltage VB, driving the AC motor 4 with the output voltage Vdc = VB causes voltage saturation.

  On the other hand, when the required motor voltage is equal to or higher than the battery voltage VB (when YES is determined in S04), the control device 5 determines in step S05 that the power loss in the vacuum cleaner 100 at the voltage command value Vdc * set in step S03, That is, the step-up power loss Ploss1 is calculated. In step S05, control device 5 controls power loss Pbat in battery B at voltage command value Vdc *, power loss Pcon in boost converter 2 at voltage command value Vdc *, and power loss in inverter 3 at voltage command value Vdc *. Power loss Pmot in AC motor 4 at Pinv and voltage command value Vdc * is calculated. Then, control device 5 calculates boosted power loss Ploss1 by summing the calculated power losses Pbat, Pcon, Pinv, and Pmot.

  Subsequently, in step S06, control device 5 calculates a power loss in vacuum cleaner 100 at voltage command value Vdc * = VB, that is, a non-boosting power loss Ploss2. In step S05, control device 5 calculates power loss Pbat in battery B, power loss Pcon in boost converter 2, power loss Pinv in inverter 3, and power loss Pmot in AC motor 4 when Vdc * = VB. I do. Then, the control device 5 calculates the non-boosting power loss Ploss2 by summing the calculated power losses Pbat, Pcon, Pinv, and Pmot.

  In step S07, control device 5 compares boosted power loss Ploss1 calculated in step S05 with non-boosted power loss Ploss2 calculated in step S06. If the boosted power loss Ploss1 is smaller than the non-boosted power loss Ploss2 (YES in step S07), the control device 5 proceeds to step S08 and selects boosting operation. Control device 5 sets voltage command value Vdc * used for driving AC motor 4 to voltage command value Vdc * set in step S03.

  On the other hand, if the boosted power loss Ploss1 is equal to or greater than the non-boosted power loss Ploss2 (NO in S07), the control device 5 proceeds to step S09 and selects the non-boosted operation. Control device 5 sets voltage command value Vdc * used for driving AC motor 4 to battery voltage VB.

  Subsequently, control device 5 proceeds to step S10, and generates control signals φs2, φc for boost converter 2 and control signal φi for inverter 3 according to voltage command value Vdc * set in step S08 or S09. Boost converter 2 supplies voltage Vdc according to voltage command value Vdc * to inverter 3 by on / off operation of switching element Q7 in response to control signal φc. Inverter 3 drives AC motor 4 in accordance with a required output by turning on / off switching elements Q1-Q6 in response to control signal φi.

  As described above, according to the vacuum cleaner according to Embodiment 1, when the required suction force is generated in the electric blower, the entire vacuum cleaner is based on the estimation of the power loss during boosting and the power loss during non-boosting. The boosting operation and the non-boosting operation can be selectively executed so that the power loss of the battery is reduced. Thereby, the efficiency of the whole vacuum cleaner can be improved. As a result, in the vacuum cleaner, the continuous use time per charge can be extended.

Embodiment 2 FIG.
In the second embodiment, a description will be given of control of the boosting rate during the boosting operation in vacuum cleaner 100 according to the first embodiment. Therefore, detailed description of the configuration of electric vacuum cleaner 100 (FIGS. 1 to 3) and common portions with the first embodiment, such as selection of boost operation and non-boost operation in control device 5, will not be repeated.

  FIG. 6 is a diagram illustrating control of the boosting rate during the boosting operation. FIG. 6 shows a relationship between each of output voltage Vdc of boost converter 2, battery voltage VB, and boost rate (Vdc / VB), and the remaining capacity (battery capacity) of battery B. The relationship shown in FIG. 6 is based on the discharge characteristics when battery B is a lithium ion battery.

  Referring to FIG. 6, at the time of boost operation, voltage command value Vdc * is set corresponding to an output request (rotation speed × torque) to AC motor 4 according to the required suction force. Voltage command value Vdc * is set to voltage V1 higher than battery voltage VB (V1> VB). Control device 5 generates control signal φc based on voltage command value Vdc * and the detection values of voltage sensors 7 and 8 so that output voltage Vdc of boost converter 2 becomes equal to voltage command value Vdc *.

  Boost converter 2 supplies voltage Vdc obtained by boosting voltage VB supplied from battery B to inverter 3. During the step-up operation, the battery voltage VB changes depending on the battery capacity. In the horizontal axis of FIG. 6, MAX indicates an upper limit value of a preset management range of the battery capacity, and MIN indicates a lower limit value of the management range. When the battery capacity is at the upper limit value MAX, the battery voltage VB indicates the maximum value VB1. When the battery capacity decreases from the upper limit value MAX, the battery voltage VB also decreases from the maximum value VB1. When the battery capacity is equal to the threshold Th, the battery voltage VB = VB2. When the battery capacity falls below the threshold Th, the battery voltage VB further decreases from VB2.

  The rate of decrease of the battery voltage VB with respect to the battery capacity is higher when the battery capacity is lower than the threshold Th than when the battery capacity is higher than the threshold Th. The rate of decrease in battery voltage VB with respect to battery capacity indicates the amount of decrease in battery voltage VB per unit capacity.

  Using the rate of decrease of the battery voltage VB with respect to the battery capacity, the temporal change rate of the battery voltage VB when the boosting operation is performed while maintaining the battery current IB (discharge current) constant, that is, the battery voltage VB within a unit time Focusing on the amount of change, it can be understood that when the battery capacity falls below the threshold Th, the temporal change rate of the battery voltage VB increases.

  Here, a case where the boosting operation is executed with the boosting rate fixed at a constant value will be considered. In FIG. 6, as indicated by a broken line, the boosting rate is fixed at V1 / VB1 based on battery voltage VB1 when the battery capacity is at upper limit value MAX and voltage command value Vdc * = V1.

  When the boosting rate is constant (= V1 / VB1), when the battery voltage VB decreases as the battery capacity decreases, the output voltage Vdc of the boosting converter 2 also decreases. As a result, as shown by the broken line in FIG. 6, the output voltage Vdc becomes a voltage lower than V1 which is the voltage command value Vdc *. Therefore, as the battery capacity decreases, the output of the AC motor 4 does not satisfy the output request, and as a result, the suction force generated by the electric blower 106 also decreases.

  As described above, when the boosting operation is performed with the boosting rate fixed at a constant value, there is a problem that the suction power of the vacuum cleaner 100 decreases as the battery capacity of the battery B decreases. As a result, the user may feel dissatisfied with the unintended decrease in the suction force.

  Therefore, in the vacuum cleaner according to the second embodiment, the boosting rate is changed according to the battery capacity so that output voltage Vdc is constant with respect to the battery capacity. Specifically, as shown by the solid line in FIG. 6, when the voltage command value Vdc * is set to V1, the boost rate is set higher as the battery capacity decreases. According to this, the boost rate (= V1 / VB2) when the battery capacity is at the threshold Th is set higher than the boost rate (= V1 / VB1) when the battery capacity is at the upper limit value MAX.

  By doing so, the output voltage Vdc can be maintained at V1 which is the voltage command value Vdc * within the range of the battery capacity from the upper limit value MAX to the threshold value Th. Therefore, even if the battery capacity decreases, the output of AC motor 4 satisfies the output requirement, and as a result, the suction force of vacuum cleaner 100 can be maintained.

  However, when the battery capacity falls below the threshold Th, the rate of decrease of the battery voltage VB with respect to the battery capacity increases. Therefore, in order to keep the output voltage Vdc at V1, the boosting rate is further increased, and the discharge current of the battery B is increased. Thereby, the overdischarge of the battery B may occur. Further, if the use of the battery B is continued in this state, the output voltage Vdc becomes unstable, and as a result, the rotation speed of the AC motor 4 may fluctuate. Further, the output voltage Vdc sharply decreases due to overdischarge of the battery B, which may cause the vacuum cleaner 100 to malfunction.

  Therefore, when the battery capacity falls below the threshold value Th during execution of the above-described boosting rate control, the control device 5 stops the boosting operation. Specifically, control device 5 fixes switching element Q7 to off. At this time, the control device 5 may fix the switching element Q7 to off and turn on the bypass switch. Therefore, when the battery capacity is lower than the threshold Th, the boost rate becomes 1, and the output voltage Vdc becomes equal to the battery voltage VB.

  The control device 5 further stops the operation of the inverter 3. By stopping the driving of the AC motor 4, the discharging of the battery B is stopped. Thus, overdischarge of the battery B can be prevented.

  FIG. 7 is a functional block diagram illustrating a control configuration related to control of boost converter 2 in vacuum cleaner 100 according to the second embodiment. Control device 5 in vacuum cleaner 100 according to the second embodiment is obtained by adding battery capacity estimation unit 26 to control device 5 shown in FIG.

  The battery capacity estimation unit 26 estimates the battery capacity of the battery B based on the battery voltage VB detected by the voltage sensor 7. Specifically, the battery capacity estimation unit 26 estimates the battery capacity based on the magnitude of the battery voltage VB and / or the rate of change of the battery capacity with time. Specifically, the battery capacity estimating unit 26 estimates the battery capacity from the detection value of the voltage sensor 7 using a map or a mathematical expression indicating the relationship between the battery voltage VB and the battery capacity as shown in FIG.

  Voltage step-up value generation unit 22 sets voltage instruction value Vdc * in response to an output request to AC motor 4 during boost operation. The switching control unit 24 changes the boosting rate with respect to the set voltage command value Vdc * according to the battery capacity estimated by the battery capacity estimating unit 26. Specifically, since the battery voltage VB decreases in accordance with the decrease in the battery capacity (see FIG. 6), the voltage command value generation unit 22 increases the boost rate in response to the decrease in the battery capacity. As a result, under the same voltage command value Vdc *, the boost rate when the detection value VB of the voltage sensor 7 is the first value is higher than the first value of the detection value VB of the voltage sensor 7. It becomes higher than the boost rate at the second value.

  Thereby, boost converter 2 can continue to supply voltage Vdc that matches voltage command value Vdc * to inverter 3 irrespective of a decrease in battery capacity. Therefore, the output shortage of AC motor 4 is suppressed, and electric blower 106 can generate a suction force according to the required suction force.

  Further, when the battery capacity estimated by the battery capacity estimating unit 26 falls below the threshold Th, the switching control unit 24 stops the boost operation and stops the operation of the inverter 3 to prevent overdischarge of the battery B. .

  When the boost operation and the operation of the inverter 3 are stopped to prevent the battery B from overheating, the control device 5 causes the display unit 14 to display the fact. This prevents the user from feeling unexpectedly that the operation of the vacuum cleaner 100 has stopped.

  FIG. 8 is a flowchart illustrating boost rate control in vacuum cleaner 100 according to the second embodiment.

  Referring to FIG. 8, control device 5 determines in step S11 whether boost operation is selected in boost converter 2 or not. When the boost operation is not selected, that is, when the non-boost operation is selected (NO in S11), the control device 5 skips the subsequent processing.

  On the other hand, when the boost operation is selected (YES in S11), control device 5 receives the detected value of battery voltage VB from voltage sensor 7 in step S12. Then, in step S13, control device 5 estimates the battery capacity of battery B based on the detected value of battery voltage VB.

  Subsequently, in step S14, control device 5 determines whether or not the battery capacity is equal to or greater than threshold value Th. If the battery capacity is equal to or greater than threshold value Th (YES in S14), control device 5 proceeds to step S15, and sets voltage command value Vdc * in response to the output request to AC motor 4.

  Next, in step S16, control device 5 generates control signals φs2 and φc for boost converter 2 and control signal φi for inverter 3 according to voltage command value Vdc * set in step S15. At this time, control device 5 generates control signal φc such that the boosting rate increases in response to the decrease in battery capacity.

  Boost converter 2 supplies voltage Vdc according to voltage command value Vdc * to inverter 3 by on / off operation of switching element Q7 in response to control signal φc. Inverter 3 drives AC motor 4 in accordance with a required output by turning on / off switching elements Q1-Q6 in response to control signal φi.

  On the other hand, when the battery capacity is smaller than the threshold Th (NO in S14), the control device 5 stops the boosting operation in step S17 and stops the operation of the inverter 3 in step S18.

  As described above, according to the vacuum cleaner according to the second embodiment, at the time of the boosting operation, the boosting when battery voltage VB is the first value with respect to the voltage command value set based on the required suction force. The rate is set higher than the boost rate when the battery voltage VB is a second value higher than the first value. By doing so, the boost converter 2 can continue to supply the voltage Vdc that matches the voltage command value to the inverter 3 irrespective of the decrease in battery capacity. As a result, the AC motor 4 is driven according to the output request, so that the suction force of the vacuum cleaner can be maintained. Therefore, the user's dissatisfaction due to the unintended decrease in the suction force can be eliminated.

  In addition, since the output voltage Vdc of boost converter 2 can be kept within a predetermined range by the boost ratio control, inverter 3 and AC motor 4 need only be designed based on the applied voltage corresponding to the predetermined range. . For example, even when a reactor having a large current dependence of the characteristic value is used, the characteristic value can be set to an optimum value in the predetermined voltage range, so that the efficiency of the vacuum cleaner can be improved.

  Further, under the same output of the AC motor 4, the output voltage Vdc is higher than in the case where the boosting rate is reduced in accordance with the decrease in the battery capacity, so that the power loss in the inverter 3 and the AC motor 4 is reduced. can do.

Embodiment 3 FIG.
The discharge characteristics of a secondary battery typically used as the battery B decrease as the battery temperature decreases. Therefore, if the vacuum cleaner 100 is started when the battery temperature is low, the output of the AC motor 4 may be insufficient and a suction force equal to the required suction force may not be generated.

  Therefore, when the battery temperature is low, it is necessary to immediately raise the temperature of the battery B when the vacuum cleaner 100 is started. In the third embodiment, a description will be given of a heating operation for increasing the temperature of battery B. Note that detailed description of the configuration of vacuum cleaner 100 (FIGS. 1 and 2) and common parts with the first embodiment, such as selection of boost operation and non-boost operation in control device 5, will not be repeated.

  FIG. 9 is a functional block diagram illustrating a control configuration related to control of boost converter 2 in vacuum cleaner 100 according to the third embodiment. Control device 5 in vacuum cleaner 100 according to the third embodiment is obtained by adding battery capacity estimating unit 26 and temperature increasing control unit 28 to control device 5 shown in FIG.

  When an operation switch for starting suction cleaning is operated on the operation unit 13 (FIG. 1), the temperature rise control unit 28 raises the temperature of the battery B based on the battery temperature TB detected by the temperature sensor 12. It is determined whether or not to perform a temperature raising operation for the purpose. Specifically, when the battery temperature TB is lower than a predetermined lower limit (the lower limit temperature TBL in FIG. 10), the temperature raising control unit 28 determines that the temperature raising operation is to be performed. The temperature raising control unit 28 instructs the voltage command value generation unit 22 to perform a temperature raising operation.

  When receiving the instruction from the temperature increase control unit 28, the voltage command value generation unit 22 performs the temperature increase operation so that the battery voltage TB becomes equal to or higher than the lower limit temperature TBL. FIG. 10 is a diagram for explaining the temperature increasing operation performed by the control device 5. FIG. 10 shows changes in output voltage Vdc of boost converter 2 and battery temperature TB after the timing when the operation switch for starting suction cleaning is turned on.

  Referring to FIG. 10, at time t1 when the operation switch is turned on, if battery temperature TB is lower than lower limit temperature TBL, a temperature increasing operation is started. In the temperature increasing operation, boost converter 2 is controlled to execute the voltage increasing operation.

  Specifically, voltage command value generating section 22 (FIG. 9) sets voltage command value Vdc * to a predetermined voltage V2 higher than battery voltage VB. Assuming that voltage command value Vdc * set based on an output request to AC motor 4 is voltage V1, voltage V2 is set lower than voltage V1. That is, voltage command value Vdc * for the temperature raising operation is set lower than voltage command value Vdc * for the normal operation.

  Switching control unit 24 generates control signals φs2 and φc for controlling boost converter 2 according to voltage command value Vdc * set by voltage command value generation unit 22. The switching control unit 24 generates the control signal φc so that the output voltage Vdc becomes equal to the voltage command value Vdc *. The switching control unit 24 further generates a control signal φs2 for fixing the bypass switch 16 (FIG. 3) to OFF. In boost converter 2, the duty ratio of switching element Q7 is set in response to control signal φc, and the boost ratio is in accordance with the duty ratio.

  When boost converter 2 performs a boost operation, a ripple current (AC component) is generated in battery B. The ripple current increases according to the voltage difference | Vdc−VB | between the output voltage Vdc and the battery voltage VB. The generation of the ripple current causes the internal resistance of the battery B to generate heat, so that the temperature of the battery B increases. That is, in the temperature increasing operation, the temperature of the battery B is increased from the inside by performing the pressure increasing operation.

  Therefore, if the ripple current is increased, that is, if the voltage difference | Vdc−VB | is increased, the temperature of battery B can be effectively increased. However, in a secondary battery represented by a lithium ion battery or a nickel hydride battery, the internal resistance generally increases as the temperature decreases. Therefore, when the ripple current is increased, the voltage generated in the internal resistance increases, and the voltage of the secondary battery may exceed the upper limit voltage allowed for safety and durability. Therefore, during the temperature increasing operation, the voltage command value Vdc * is set so that the ripple current becomes maximum within a range where the voltage of the battery B does not exceed the upper limit voltage. Thus, the temperature of the battery B can be increased without imposing a burden on the battery B. However, the output voltage Vdc during the heating operation is lower than the voltage V1 that should be output, so that the output of the AC motor 4 is limited.

  When the temperature of the battery B rises due to the heating operation and the battery temperature TB becomes equal to or higher than the lower limit temperature TBL (time t3), the control device 5 ends the heating operation and shifts the vacuum cleaner 100 to the normal operation. In normal operation, boost converter 2 supplies voltage Vdc (= V1) to inverter 3 according to voltage command value Vdc *. Inverter 3 drives AC motor 4 according to the required output.

  Furthermore, during execution of the normal operation, when battery temperature TB rises and reaches a predetermined upper limit (upper limit temperature TBH in FIG. 10) (time t4), control device 5 stops the boost operation and operates inverter 3 To stop. Thus, overheating of the battery B is prevented.

  FIG. 11 is a flowchart illustrating a temperature increasing operation performed in vacuum cleaner 100 according to the third embodiment.

  Referring to FIG. 11, control device 5 determines in step S21 whether or not an operation switch for starting suction cleaning in operation unit 13 has been turned on. When it is determined that the operation switch is not turned on (NO in S21), the control device 5 skips the subsequent processing.

  On the other hand, if it is determined that the operation switch has been turned on (YES in S21), control device 5 receives the detected value of battery temperature TB from temperature sensor 12 in step S22. Control device 5 determines in step S23 whether battery temperature TB is lower than predetermined lower limit temperature TBL. If the battery temperature TB is lower than the lower limit temperature TBL (YES in S23), the control device 5 proceeds to step S24 and executes the temperature raising operation. Control device 5 causes boost converter 2 to execute a boost operation, thereby raising the temperature of battery B.

  On the other hand, if the battery temperature TB is equal to or higher than the lower limit temperature TBL (NO in S23), the control device 5 proceeds to step S25, and executes the normal operation. Control device 5 controls boost converter 2 according to a voltage command value Vdc * corresponding to a required output to AC motor 4.

  Control device 5 determines in step S26 whether battery temperature TB is higher than predetermined upper limit temperature TBH. When battery temperature TB is equal to or lower than upper limit temperature TBH (NO in S26), control device 5 skips the subsequent processing.

  On the other hand, when battery temperature TB is higher than upper limit temperature TBH (YES in S26), control device 5 proceeds to step S27 and stops the boost operation. Control device 5 further stops the operation of inverter 3 in step S28.

  During execution of the temperature increasing operation, boost converter 2 supplies inverter 3 with voltage V2 lower than voltage V1 corresponding to the output request to AC motor 4. For this reason, a decrease in the suction force due to the insufficient output of the AC motor 4 may occur, giving the user a sense of discomfort. Therefore, the control device 5 displays on the display unit 14 (FIG. 1) that the temperature raising operation is being performed, so that the decrease in the suction force is temporary until the temperature of the battery B increases. To the user. This can prevent the user from feeling uncomfortable.

  Further, when stopping the boosting operation and the operation of inverter 3 to prevent overheating of battery B, control device 5 causes display unit 14 to indicate that. Thus, it is possible to prevent the user from feeling that the operation of the vacuum cleaner 100 has stopped unexpectedly.

  Note that, in the above embodiment, the electric vacuum cleaner including the AC motor that drives the electric blower by receiving the supply of power from the electric storage device has been described, but the present invention is not limited to the electric vacuum device, and may be applied to an electric storage device. It can be widely applied to products using an AC motor driven by stored electric power as a driving source. For example, the present invention can be applied to a product including an electric blower such as a hand dryer.

  It should be understood that the embodiments disclosed herein are illustrative in all aspects and not restrictive. 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.

2 step-up converter, 3 inverter, 4 AC motor, 5 control device, 6 power switch, 7, 8, 9 voltage sensor, 10, 11 current sensor, 12 temperature sensor, 13 operation unit, 14 display unit, 15 rotation angle sensor, Reference Signs List 16 bypass switch, 20 power loss calculation unit, 22 voltage command value generation unit, 24 switching control unit, 26 battery capacity estimation unit, 28 heating control unit, 100 vacuum cleaner, 102 handle, 104 power supply unit, 106 electric blower , 108 dust collection chamber, 110 housing, 112 suction section, 113 ventilation path, 114 suction port, 116 substrate, B battery, L1 reactor, C1 capacitor, Q1-Q7 switching element, D1-D8 diode.

Claims (9)

An AC motor configured to drive the electric blower,
A power storage device,
A boost converter configured to boost a DC voltage received from the power storage device,
An inverter that converts an output voltage of the boost converter into an AC voltage for driving the AC motor;
A control device configured to control the boost converter and the inverter,
The boost converter selectively executes a boost operation in which a boost ratio indicated by a ratio of the output voltage to a voltage of the power storage device is higher than 1, and a non-boost operation in which the boost ratio is fixed at 1. Is composed of
A vacuum cleaner that increases the boosting rate in response to a decrease in the remaining capacity of the power storage device during the boosting operation. Further comprising a voltage sensor for detecting the voltage of the power storage device,
The control device is configured to detect the boosting rate when the detected value of the voltage sensor is a first value with respect to a voltage command value set based on the required suction force during the boosting operation. The vacuum cleaner according to claim 1, wherein the boosting rate is higher than the pressure increase rate when the value is a second value higher than the first value. The control device estimates the remaining capacity of the power storage device based on a detection value of the voltage sensor during the boost operation.
The vacuum cleaner according to claim 2, wherein when the remaining capacity falls below a predetermined threshold, the boost operation is stopped and the operation of the inverter is stopped. When generating the required suction force in the electric blower,
A first power loss that occurs in the vacuum cleaner when the AC motor is driven by selecting the boost operation, and a first power loss that occurs in the vacuum cleaner when the AC motor is driven by selecting the non-boost operation. And calculating the second power loss,
When the first power loss is larger than the second power loss, the boost converter and the inverter are controlled so as to execute the non-boost operation and drive the AC motor.
4. The boost converter and the inverter according to claim 1, wherein when the first power loss is smaller than the second power loss, the boost converter and the inverter are controlled so as to execute the boost operation to drive the AC motor. The vacuum cleaner according to claim 1. The control device includes:
By summing the power loss in the power storage device, the power loss in the boost converter, the power loss in the inverter, and the power loss in the AC motor when the boosting operation is selected to drive the AC motor, Calculate the power loss of 1
The power loss in the power storage device when the non-boost operation is selected and the AC motor is driven, the power loss in the boost converter, the power loss in the inverter, and the power loss in the AC motor are summed up. The vacuum cleaner according to claim 4, wherein the second power loss is calculated. The boost converter includes:
A boost chopper circuit having a reactor and a switching element;
A bypass switch electrically connected in parallel to the reactor,
The vacuum cleaner according to any one of claims 1 to 5, wherein the control device supplies the voltage of the power storage device to the inverter by turning on the bypass switch when the non-boost operation is selected. . Further comprising a temperature sensor for detecting the temperature of the power storage device,
The control device includes:
If the detected value of the temperature sensor is lower than a predetermined lower limit at the time of starting the vacuum cleaner, perform a temperature increasing operation of increasing the temperature of the power storage device by the pressure increasing operation,
If the detected value of the temperature sensor exceeds the predetermined lower limit during the execution of the heating operation, the heating operation is terminated, and the boost converter and the inverter are so controlled that the electric blower generates a required suction force. The vacuum cleaner according to claim 1, wherein the vacuum cleaner is controlled. The control device is configured to control an output voltage of the boost converter according to a voltage command value during the boost operation.
The vacuum cleaner according to claim 7, wherein the voltage command value at the time of the temperature increasing operation is set to be lower than the voltage command value set based on a required suction force. 9. The controller according to claim 7, wherein when the detected value of the temperature sensor becomes higher than a predetermined upper limit during operation of the vacuum cleaner, the controller stops the boost operation and stops the operation of the inverter. 10. An electric vacuum cleaner according to claim 1.

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