JPWO2018025344A1 - Electric vacuum cleaner - Google Patents

Abstract

The control device (5) drives the AC motor (4) by selecting the first power loss that occurs in the vacuum cleaner when the AC motor (4) is driven by selecting the boost operation and the non-boosting operation. A second power loss that sometimes occurs in the vacuum cleaner is calculated. When the first power loss is larger than the second power loss, the control device (5) performs the non-boosting operation to drive the AC motor (4), so that the boost converter (2) and the inverter (3 ) To control. On the other hand, when the first power loss is smaller than the second power loss, the control device (5) performs the boost operation to drive the AC motor (4), so that the boost converter (2) and the inverter ( 3) is controlled.

Description

  The present invention relates to a vacuum cleaner.

  2. Description of the Related Art A vacuum cleaner is known that includes a power storage device and an electric blower that generates a suction force when power is supplied from the power storage device. For example, Japanese Patent Laying-Open No. 2015-342 (Patent Document 1) discloses a vacuum cleaner including 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 the battery into an AC voltage for driving the motor.

  In the above vacuum cleaner, when the motor is driven at a high rotational speed, the counter electromotive force increases and the induced voltage becomes high, so that the voltage (required voltage) to be applied to the motor becomes high. Therefore, there is a case where so-called voltage saturation occurs in which the necessary voltage exceeds the output possible voltage of the inverter.

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

Japanese Patent Laid-Open No. 2015-342 JP 2004-135835 A

  The vacuum cleaner described in Patent Document 2 is configured to switch between a non-boosting operation mode in which the boost converter is not operated and a boosting 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 Document 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 for driving the electric blower by converting the output voltage of the boost converter into the AC voltage by the inverter as disclosed in Patent Document 2, each component of the vacuum cleaner is operated according to the voltage level of the output voltage of the boost converter. The power loss changes. Therefore, the efficiency of the entire vacuum cleaner also changes.

  However, Patent Document 2 does not disclose or suggest that the boost converter is controlled 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 supply of electric power from a power storage device.

  An electric vacuum cleaner according to an aspect of the present invention is equipped with an electric blower that generates 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 the electric blower. The boost converter is configured to boost a DC voltage received from the power storage device. The inverter is configured to convert the 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 the step-up rate indicated by the ratio of the output voltage to the voltage of the power storage device is higher than 1. The non-boosting operation is an operation in which the boosting rate is fixed to 1. When the required suction force is generated in the electric blower, the control device selects the first power loss generated in the vacuum cleaner when the AC motor is driven by selecting the boost operation, and the AC motor by selecting the non-boosting operation. And the second power loss that occurs in the vacuum cleaner when the is driven. When the first power loss is larger than the second power loss, the control device controls the boost converter and the inverter to perform the non-boosting operation 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 so as 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 supply of electric power 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. It is a block diagram which shows the structure of a power supply part. It is a circuit diagram which shows the structure of a boost converter and an inverter. It is a functional block diagram explaining the control structure regarding control of the step-up converter in the electric vacuum cleaner according to Embodiment 1. 6 is a flowchart illustrating control of a boost converter in the electric vacuum cleaner according to the first embodiment. It is a figure explaining the control of the pressure | voltage rise rate at the time of pressure | voltage rise operation. It is a functional block diagram explaining the control structure regarding control of the boost converter in the vacuum cleaner according to Embodiment 2. It is a flowchart explaining the pressure | voltage rise rate control in the vacuum cleaner according to Embodiment 2. It is a functional block diagram explaining the control structure regarding control of the boost converter in the vacuum cleaner according to Embodiment 3. It is a figure for demonstrating the temperature rising operation performed by a control apparatus. It is a flowchart explaining the temperature rising operation performed in the vacuum cleaner according to Embodiment 3.

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

Embodiment 1 FIG.
(Configuration of vacuum cleaner)
1 is a diagram showing an overall configuration of an electric 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 electric vacuum cleaner 100. The vacuum cleaner 100 is not limited to a stick cleaner, and may be a canister type vacuum cleaner configured by connecting an extension pipe to a vacuum cleaner body having an electric blower, a dust collecting unit, and a power source unit, for example.

  Referring to FIG. 1A, the vacuum cleaner 100 includes a power supply unit 104, an electric blower 106, a dust collection chamber 108, an extension pipe 111, and a suction unit 112. The power supply unit 104, the electric blower 106, and the dust collection chamber 108 are accommodated in the 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. The battery B is a secondary battery such as a nickel metal hydride battery or a lithium ion battery, for example. An electric double layer capacitor or the like can be used as the power storage device.

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

  The electric blower 106 is disposed on a ventilation path 113 provided in the housing 110. The electric blower 106 receives supply of electric power from the battery B and applies a negative pressure to the ventilation path 113. The electric blower 106 drives an AC electric motor (see FIG. 2) as a blower motor.

  The dust collection chamber 108 communicates with the extension pipe 111. The suction portion 112 is connected to the distal end portion of the extension pipe 111. The suction part 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 negative suction pressure, dust on the surface to be cleaned is sucked into the suction portion 112 together with air. The air containing 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 in which dust is collected flows through the ventilation path 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 path 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 switch for switching the operation mode includes an operation switch 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 (charged state), etc.). As will be described later, the display unit 14 is configured to display the fact when the operation is stopped to prevent overheating of the battery B. Moreover, the display part 14 is comprised so that that may be displayed, when performing the temperature rising operation for heating up the battery B at the time of starting of the vacuum cleaner 100. FIG. In addition, the display part 14 is not limited to the form installed in the handle 102, You may provide in another position.

(Power supply configuration)
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 electric motor 4 of electric blower 106, and constitutes a motor drive device that drives AC electric motor 4 when supplied with electric power from battery B. To 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 φs 1 from the control device 5. Power switch 6 electrically connects battery B to boost converter 2 in the on (conducting) state, and electrically disconnects battery B from boost converter 2 in the off (shut-off) state. When the operation switch for starting the suction cleaning is operated in the operation unit 13, the power switch 6 is turned on, and when the operation switch for stopping the suction cleaning is operated, the power switch 6 is turned off.

  Boost converter 2 controls output voltage (= voltage between positive line PL2 and negative line NL) Vdc according to voltage command value Vdc * based on control signal φc from control device 5. With respect to voltage VB of battery B, boost converter 2 controls output voltage Vdc within a range of Vdc ≧ VB. That is, the boost converter 2 has a function of boosting the voltage VB of the 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 so that the output torque of AC electric 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 by commonly connecting one end of three coils (not shown) of U, V, and W phases to a neutral point. The AC motor 4 generates torque for rotationally driving the electric blower 106. 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 the anode of diode D8. The node of diode D8 is connected to positive line PL2. Switching element Q7 has a collector connected to a connection node of reactor L1 and diode D8, and an emitter connected to negative electrode line NL. Diode D7 is connected in antiparallel to switching element Q7. The switching element Q7 is turned on / off 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 voltage fluctuation between positive line PL2 and negative line NL.

  The bypass switch 16 is electrically connected to the reactor L1 in parallel. The bypass switch 16 is on / off controlled based on a control signal φs <b> 2 from the control device 5. In the on state, bypass switch 16 bypasses reactor L1 and connects positive line PL1 to the anode of diode D8.

  Boost converter 2 is configured to selectively execute a boosting operation and a non-boosting operation. In step-up operation, step-up 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 via 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 through the battery B-reactor L1-diode D8-capacitor C1 is formed. Thereby, the energy stored in the reactor L1 in the ON period Ton is supplied to the capacitor C1. In this way, the voltage VB of the battery B is boosted and output between the positive line PL2 and the negative 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 step-up rate is indicated by the ratio (= Vdc / VB) of output voltage Vdc of boost converter 2 to voltage VB of battery B.

  Control device 5 controls on / off of switching element Q7 in accordance with the duty ratio calculated in accordance with the detected values of voltages VB and Vdc and voltage command value Vdc *. Specifically, when the output voltage Vdc is lower than the voltage command value Vdc *, the 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 lowered by reducing the duty ratio. Thus, in the step-up operation, Vdc *> VB is set, and the step-up rate can be made higher than 1 by the on / off control of the switching element Q7.

  On the other hand, in non-boosting operation, AC motor 4 is controlled in a state of Vdc = VB without boosting by boosting converter 2. That is, in the non-boosting operation, the boosting rate is fixed at 1. In the non-boosting operation, since the switching element Q7 is fixed off, the power loss in the boost converter 2 is reduced.

  Further, in the non-boosting operation, the bypass switch 16 is fixed to ON. Thereby, the voltage VB of the battery B is supplied to the inverter 3 through the bypass switch 16 and the diode D8. By sending a current to the inverter 3 without going through the reactor L1, the power loss in the boost converter 2 is further reduced as compared with the above-described fixed off state of the switching element Q7.

  The 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, 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. An intermediate point of each phase arm is connected to each phase coil of AC motor 4.

  When the DC voltage Vdc is supplied from the boost converter 2, the inverter 3 converts the DC voltage Vdc into an AC voltage by the switching operation of the switching elements Q <b> 1 to Q <b> 6 in response to the control signal φi from the controller 5. 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 constituting each switching element, a wide band gap semiconductor having a larger band gap than silicon can be employed. The wide band gap semiconductor is preferably any of silicon carbide, gallium nitride-based material, and diamond.

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

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

  The rotation angle sensor 15 detects the rotor rotation angle θ of the AC motor 4 and outputs the detected value to the control device 5. The control device 5 can calculate the rotational speed Nm of the AC motor 4 based on the rotational angle θ. Note that 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 (not shown) including a CPU (Central Processing Unit), a memory, and the like, and performs arithmetic processing using detection values from each sensor based on a map and a program stored in the memory. Configured as follows. Alternatively, at least a part of the control device 5 may be configured to execute predetermined numerical / logical operation processing by hardware such as an electronic circuit.

  The control device 5 controls the boost converter 2 and the inverter 3 based on the operation command input from the operation unit 13 and the detection value of each sensor. That is, control device 5 generates control signals φc and φs2 based on the operation command and the detection values of the sensors, and outputs them to boost converter 2. 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, step-up converter 2 is configured to selectively execute the step-up operation and the non-step-up operation. The control device 5 selectively performs boosting operation and non-boosting operation according to the power loss generated in the vacuum cleaner 100 for controlling the 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 electric 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 the power loss calculation unit 20 receives an operation command from the operation unit 13, the power loss calculation unit 20 is necessary to cause the electric blower 106 to generate a suction force specified by the operation command (hereinafter also referred to as “request suction force”). The output (rotation speed x torque) of the AC motor 4 is set.

  For example, when the operation switch for strong operation setting is operated in the operation unit 13, the power loss calculation unit 20 sets the output request to the AC motor 4 to an output corresponding to the strong operation mode. On the other hand, when the operation switch for intermediate operation setting is operated in the operation unit 13, the power loss calculation unit 20 sets the output request to an output corresponding to the intermediate operation mode. Moreover, when the operation switch for weak driving setting is operated in the operation part 13, the power loss calculating part 20 sets an output request | requirement to the output corresponding to weak driving 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 for the AC motor 4 is set according to the operation command from the operation unit 13, the power loss calculation unit 20 calculates a voltage command value Vdc * corresponding to the set output request.

  In the AC motor 4, when the rotational speed and / or torque is increased, the back electromotive force is increased and the induced voltage is increased, so that the required voltage is increased. Accordingly, output voltage Vdc of boost converter 2 needs to be set higher than this necessary voltage. On the other hand, there is a limit to the boosting of boosting converter 2, and the output voltage Vdc has an upper limit value. Therefore, power loss calculation unit 20 sets voltage command value Vdc * within the 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.

  In addition, a motor required voltage (induced voltage) becomes high, so that the output request | requirement with respect to the AC motor 4 becomes large. Therefore, the motor required voltage corresponding to the output request in the strong operation mode is higher than the motor required voltage corresponding to the output request in the weak operation mode. If the operation mode is such that 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. In other words, boost converter 2 can perform non-boosting operation.

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

  In the estimation of the power loss Ploss, the power loss calculator 20 selects the power loss Ploss1 (hereinafter also referred to as “power loss during boosting”) in the vacuum cleaner 100 when the AC motor 4 is driven by selecting the boost operation. .) Is calculated. The power loss Ploss1 during boosting corresponds to the power loss in the vacuum cleaner 100 when the voltage command value Vdc * is set higher than the voltage VB of the battery B.

  In addition, the power loss calculation unit 20 calculates a power loss Ploss2 (hereinafter also referred to as “non-boosting power loss”) that occurs in the vacuum cleaner 100 when the AC motor 4 is driven by selecting the non-boosting operation. . The non-boosting power loss Ploss2 corresponds to the power loss in the vacuum cleaner 100 when the voltage command value Vdc * = VB is set.

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

[1] Calculation of Boosting Power Loss Ploss1 The power loss calculating unit 20 selects the boost operation and drives the AC motor 4. The power loss Pbat in the battery B, the power loss Pcon in the boost converter 2, and the power in the inverter 3 The power loss Ploss1 during boosting is calculated by summing the loss Pinv and the power loss Pmot in the AC motor 4. That is, the step-up power loss Ploss1 is expressed by the following equation.

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

The power loss Pbat in the battery B is mainly Joule loss due to the internal resistance, and is represented by Rbat · IB ² using the internal resistance value Rbat and the 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 during the boost operation is obtained by superposing the ripple current (alternating current component) on the average current (direct current 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 these, 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, power loss Pbat with respect to voltage command value Vdc * can be calculated by creating a map with battery temperature TB and voltage difference | Vdc−VB | as parameters.

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

  The switching loss Pconsw is represented 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. Also, under the same switching frequency, the switching loss Pconsw increases as the switching voltage of the switching element Q7 increases in accordance with the increase in the output voltage Vdc.

  The loss Pconline due to the wiring impedance increases as the passing current (that is, the battery current IB) of the boost converter 2 increases and 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. Therefore, 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, as the power loss Pcon, the ripple current, that is, the voltage difference | Vdc−VB | Therefore, the power loss Pcon with respect to the voltage command value Vdc * can be calculated by creating in advance a map using the switching frequency of the boost converter 2 and the voltage difference | Vdc−VB | as parameters.

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

  The switching loss Pinvsw is a value proportional to the switching frequency of the inverter 3 as in the case of the switching loss Pconsw. When the same torque is output, the switching loss Pinvsw increases as the switching voltage of each switching element increases in accordance with the increase in the output voltage Vdc. The loss Pinvline due to the wiring impedance increases as the passing current of the inverter 3 (that is, the motor current Im) increases. Therefore, under the same torque output, since the motor current Im decreases as the output voltage Vdc increases, the loss Pinvline decreases.

  Therefore, for the power loss Pinv, the power loss Pinv with respect to 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.

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

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

  For example, the power loss calculation unit 20 creates a map with the battery temperature TB and the voltage difference | Vdc−VB | as parameters in advance, and refers to the map to obtain the power loss Pbat at the voltage command value Vdc *. calculate. In addition, the power loss calculation unit 20 creates a map using the voltage difference | Vdc−VB | and the switching frequency of the boost converter 2 as parameters in advance, and by referring to the map, the power at the voltage command value Vdc * is obtained. The loss Pcon is calculated.

  The power loss calculation unit 20 further creates a map using the operating state of the AC motor 4, the output voltage Vdc, and the switching frequency of the inverter 3 as parameters in advance, and refers to the map so that the voltage command value Vdc * The power loss Pinv at is calculated. Further, the power loss calculation unit 20 creates a map using the operating state of the AC motor 4 and the output voltage Vdc as parameters in advance, and calculates the power loss Pmot at the voltage command value Vdc * by referring to the map. To do.

  When each of the power losses Pbat, Pcon, Pinv, and Pmot is calculated by the above-described method, the power loss calculation unit 20 substitutes each calculated power loss into the formula (1), thereby increasing the power loss during boosting. Calculate Ploss1.

[2] Calculation of Non-boosting Power Loss Ploss2 The power loss calculating unit 20 selects the non-boosting operation and drives the AC motor 4, the power loss Pbat in the battery B, the power loss Pcon in the boost converter 2, and the inverter 3 Is summed with the power loss Pinv at, and the power loss Pmot at the AC motor 4 to calculate the non-boosting power loss Ploss2. That is, the non-boosting 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-boosting operation is only the average current (DC component), the power loss Pbat during the non-boosting operation is represented by the product of the internal resistance value Rbat and the square of the average current. Therefore, for the power loss Pbat, a power loss with respect to the voltage command value Vdc * (= VB) is created in advance by creating a map using the average current (DC), that is, the operating state of the AC motor 4 and the battery temperature TB as parameters. Pbat can be calculated.

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

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

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

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

  That is, the voltage command value generation unit 22 sets the final voltage command value Vdc * based on the smaller voltage command value of the boosting power loss Ploss1 and the non-boosting power loss Ploss2. Thus, the voltage command value Vdc * is set so that the output voltage Vdc is obtained so that the power loss of the entire vacuum cleaner 100 is minimized.

  Switching control unit 24 generates control signals φs 2 and φc for boost converter 2 in accordance with voltage command value Vdc * set by voltage command value generation unit 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 step-up converter 2, the duty ratio of switching element Q7 is set in response to control signal φc, and the step-up rate is in accordance with the duty ratio.

  On the other hand, when Vdc * = VB, switching control unit 24 generates control signal φc so as to fix switching element Q7 off. The switching control unit 24 further generates a control signal φs2 for fixing the bypass switch 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 in accordance with voltage command value Vdc *. When the inverter 3 is subjected to switching control according to the control signal φi, an AC voltage for outputting torque according to the output request is applied to the AC motor 4.

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

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

  Subsequently, in step S03, control device 5 sets voltage command value Vdc * within the 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 boosting operation is set.

  Next, in step S04, the control device 5 determines whether or not the required motor voltage obtained in step S02 is equal to or lower than the 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, voltage saturation occurs when the AC motor 4 is driven in the state of the output voltage Vdc = VB.

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

  Subsequently, in step S06, the control device 5 calculates a power loss in the vacuum cleaner 100 at the 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 at Vdc * = VB, power loss Pcon in boost converter 2, power loss Pinv in inverter 3, and power loss Pmot in AC motor 4. To 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, the control device 5 compares the step-up power loss Ploss1 calculated in step S05 with the non-step-up power loss Ploss2 calculated in step S06. When the power loss Ploss1 during boosting is smaller than the power loss Ploss2 during non-boosting (when YES is determined in step S07), the control device 5 proceeds to step S08 and selects the boosting operation. Control device 5 sets voltage command value Vdc * used for driving AC electric motor 4 to voltage command value Vdc * set in step S03.

  On the other hand, when the boosting power loss Ploss1 is greater than or equal to the non-boosting power loss Ploss2 (NO determination in S07), the control device 5 proceeds to step S09 and selects the non-boosting 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 and φc for boost converter 2 and control signal φi for inverter 3 in accordance with 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 the on / off operation of switching element Q7 in response to control signal φc. Inverter 3 drives AC electric motor 4 according to the required output by the on / off operation of switching elements Q1 to Q6 in response to control signal φi.

  As described above, according to the vacuum cleaner according to the first embodiment, 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 step-up operation and the non-step-up operation can be selectively executed so that the power loss of the power supply is reduced. Thereby, the efficiency of the whole vacuum cleaner can be improved. As a result, the continuous use time per charge can be lengthened in the vacuum cleaner.

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

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

  Referring to FIG. 6, during boost operation, voltage command value Vdc * is set in response to an output request (rotational speed × torque) to AC motor 4 according to the required suction force. Voltage command value Vdc * is set to a 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 is 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 boost operation, the battery voltage VB varies depending on the battery capacity. In the horizontal axis of FIG. 6, MAX represents an upper limit value of a preset battery capacity management range, and MIN represents a lower limit value of the management range. When the battery capacity is 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 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.

  Note that 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 compared to when the battery capacity is larger than the threshold Th. The decrease rate of the battery voltage VB with respect to the battery capacity indicates the decrease amount of the battery voltage VB per unit capacity.

  Using the rate of decrease of the battery voltage VB with respect to the battery capacity, the rate of change over time of the battery voltage VB when the boosting operation is executed while keeping the battery current IB (discharge current) constant, that is, the battery voltage VB within a unit time When it is noted that the amount of change in the battery voltage VB falls below the threshold Th, it is understood that the temporal change rate of the battery voltage VB increases.

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

  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 boost converter 2 also decreases. As a result, as indicated by a broken line in FIG. 6, the output voltage Vdc is lower than V1 that is the voltage command value Vdc *. Therefore, when 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 arises a problem that the suction force 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 reduction in 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 a solid line in FIG. 6, when the voltage command value Vdc * = V1, the boost rate is set higher as the battery capacity decreases. According to this, the boosting rate (= V1 / VB2) when the battery capacity is the threshold Th is set higher than the boosting rate (= V1 / VB1) when the battery capacity is the upper limit value MAX.

  In this way, the output voltage Vdc can be kept 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 the AC motor 4 satisfies the output requirement, and as a result, the suction force of the 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 step-up rate is further increased, and the discharge current of the battery B is increased. Thereby, 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 rotational speed of the AC motor 4 may fluctuate. Furthermore, when the output voltage Vdc is suddenly decreased due to overdischarge of the battery B, the vacuum cleaner 100 may be erroneously operated.

  Therefore, when the battery capacity falls below the threshold value Th during the above-described step-up rate control, the control device 5 stops the step-up operation. Specifically, control device 5 fixes switching element Q7 off. At this time, control device 5 may fix switching element Q7 off and turn on the bypass switch. Therefore, when the battery capacity is lower than the threshold value Th, the step-up rate is 1, and the output voltage Vdc is 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 discharge of the battery B is stopped. Thereby, 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 electric vacuum cleaner 100 according to the second embodiment. Control device 5 in electric 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 temporal change rate of the battery capacity. Specifically, the battery capacity estimation unit 26 estimates the battery capacity from the detection value of the voltage sensor 7 using a map or a mathematical expression showing the relationship between the battery voltage VB and the battery capacity as shown in FIG.

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

  Thus, boost converter 2 can continue to supply voltage Vdc that matches voltage command value Vdc * to inverter 3 regardless of the decrease in battery capacity. Therefore, since the shortage of output of the AC motor 4 is suppressed, the 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 the battery B from being overdischarged. .

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

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

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

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

  Subsequently, in Step S14, the control device 5 determines whether or not the battery capacity is equal to or greater than the threshold value Th. When the battery capacity is equal to or greater than the threshold Th (when YES is determined in S14), the control device 5 proceeds to step S15 and sets the voltage command value Vdc * in response to the output request to the 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 in accordance with voltage command value Vdc * set in step S15. At this time, the control device 5 generates the control signal φc so that the boosting rate increases in response to the decrease in the battery capacity.

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

  On the other hand, when the battery capacity is smaller than the threshold Th (NO determination in S14), the control device 5 stops the boost 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, during boosting operation, 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 made higher than the boost rate when the battery voltage VB is a second value higher than the first value. Thus, boost converter 2 can continue to supply voltage Vdc that matches the voltage command value to inverter 3 regardless of the decrease in battery capacity. Thereby, since AC motor 4 is driven according to an output demand, the suction force of a vacuum cleaner can be maintained. Therefore, the dissatisfaction of the user due to the unintended reduction of the suction force can be solved.

  Further, since the output voltage Vdc of the boost converter 2 can be kept within a predetermined range by the boost rate control, the inverter 3 and the AC motor 4 may be designed based on the applied voltage corresponding to the predetermined range. . For example, even when a reactor whose characteristic value has a large current dependency is used, the characteristic value can be set to an optimum value for the predetermined voltage range, so that the efficiency of the vacuum cleaner can be improved.

  Further, when the output of the AC motor 4 is the same, the output voltage Vdc is higher than when the step-up rate is decreased according to 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.
A secondary battery typically used as the battery B has a reduced discharge characteristic when 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 quickly raise the battery B when the vacuum cleaner 100 is activated. In the third embodiment, a temperature raising operation for raising the temperature of battery B will be described. Detailed description will not be repeated with respect to the common parts of Embodiment 1 such as the configuration of vacuum cleaner 100 (FIGS. 1 and 2) and selection of boosting operation and non-boosting operation in control device 5.

  FIG. 9 is a functional block diagram illustrating a control configuration related to control of boost converter 2 in electric 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 estimation unit 26 and temperature increase control unit 28 to control device 5 shown in FIG.

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

  When the voltage command value generation unit 22 receives an 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 raising operation executed 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, when battery temperature TB is lower than lower limit temperature TBL, the temperature raising operation is started. In the temperature raising operation, boost converter 2 is controlled to execute the boost operation.

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

  Switching control unit 24 generates control signals φs 2 and φc for controlling boost converter 2 in accordance with 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 step-up converter 2, the duty ratio of switching element Q7 is set in response to control signal φc, and the step-up rate is in accordance with the duty ratio.

  When boost converter 2 performs the boost operation, ripple current (alternating current 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. When the ripple current is generated, the internal resistance of the battery B generates heat, so that the temperature of the battery B rises. That is, in the temperature rising operation, the battery B is heated from the inside by executing the pressure increasing operation.

  Therefore, if the ripple current is increased, that is, if the voltage difference | Vdc−VB | is increased, the battery B can be effectively heated. However, a secondary battery represented by a lithium ion battery or a nickel metal hydride battery generally has an increased internal resistance value when the temperature is lowered. For this reason, when the ripple current is increased, the voltage generated in the internal resistance is increased, and the voltage of the secondary battery may exceed the upper limit voltage allowed for safety and durability. Therefore, during the temperature raising 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. Thereby, the temperature of battery B can be raised without imposing a burden on battery B. However, since the output voltage Vdc during the temperature raising operation is lower than the voltage V1 that should be output, the output of the AC motor 4 is limited.

  When the battery B is heated by the temperature raising 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 temperature raising operation and shifts the vacuum cleaner 100 to the normal operation. In normal operation, boost converter 2 supplies voltage Vdc (= V1) according to voltage command value Vdc * to inverter 3. The inverter 3 drives the AC motor 4 according to the required output.

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

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

  Referring to FIG. 11, in step S <b> 21, control device 5 determines whether or not an operation switch for starting suction cleaning is turned on at operation unit 13. When it is determined that the operation switch is not turned on (NO determination 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. In step S23, the control device 5 determines whether or not the battery temperature TB is lower than a predetermined lower limit temperature TBL. When battery temperature TB is lower than lower limit temperature TBL (when YES is determined in S23), control device 5 proceeds to step S24 and executes a temperature raising operation. Controller 5 raises the temperature of battery B by causing boost converter 2 to perform a boost operation.

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

  In step S26, control device 5 determines whether or not battery temperature TB is higher than a predetermined upper limit temperature TBH. When the battery temperature TB is equal to or lower than the upper limit temperature TBH (NO determination in S26), the control device 5 skips the subsequent processing.

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

  During the temperature raising operation, boost converter 2 supplies inverter 3 with voltage V2 lower than voltage V1 corresponding to the output request to AC motor 4. Therefore, the suction force is reduced due to insufficient output of the AC motor 4, which may give the user a sense of discomfort. Therefore, the control device 5 displays the fact that the temperature raising operation is being performed on the display unit 14 (FIG. 1), so that the reduction of the suction force is temporary until the battery B rises in temperature. This is notified to the user. Thereby, the discomfort given to a user can be prevented.

  Furthermore, the control device 5 also displays that on the display unit 14 when stopping the boosting operation and the operation of the inverter 3 to prevent the battery B from overheating. Thereby, it can prevent a user feeling that the driving | operation of the vacuum cleaner 100 stopped unexpectedly.

  In the above-described embodiment, the electric vacuum cleaner provided with the AC motor that receives the supply of electric power from the power storage device and drives the electric blower has been described, but the present invention is not limited to the vacuum cleaner, The present invention can be widely applied to products using an AC motor driven by stored electric power as a drive source. For example, the present invention can be applied to a product including an electric blower such as a hand dryer.

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

  2 boost 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, DESCRIPTION OF SYMBOLS 16 Bypass switch, 20 Power loss calculating part, 22 Voltage command value production | generation part, 24 Switching control part, 26 Battery capacity estimation part, 28 Temperature rising control part, 100 Vacuum cleaner, 102 Handle, 104 Power supply part, 106 Electric blower , 108 Dust collection chamber, 110 Housing, 112 Suction part, 113 Ventilation path, 114 Suction port, 116 Substrate, B battery, L1 reactor, C1 capacitor, Q1-Q7 switching element, D1-D8 diode.

Claims (8)

A vacuum cleaner equipped with an electric blower that generates suction force,
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 the 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 step-up converter selectively performs a step-up operation in which the step-up rate indicated by the ratio of the output voltage to the voltage of the power storage device is higher than 1, and a non-step-up operation in which the step-up rate is fixed to 1. Composed of
In the case where the required suction force is generated in the electric blower, the control device is
A first power loss that occurs in the vacuum cleaner when the booster operation is selected and the AC motor is driven, and a first power loss that occurs in the vacuum cleaner when the non-boost operation is selected and the AC motor is driven Calculate the second power loss,
When the first power loss is larger than the second power loss, the boost converter and the inverter are controlled to execute the non-boosting operation to drive the AC motor,
An electric vacuum cleaner that controls the boost converter and the inverter to execute the boost operation and drive the AC motor when the first power loss is smaller than the second power loss. 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 AC motor is driven with the boost operation selected. Calculate the power loss of 1
By summing the power loss in the power storage device when the AC motor is driven by selecting the non-boosting operation, the power loss in the boost converter, the power loss in the inverter, and the power loss in the AC motor, The vacuum cleaner according to claim 1, wherein the second power loss is calculated. The boost converter includes:
A step-up chopper circuit having a reactor and a switching element;
A bypass switch electrically connected in parallel to the reactor,
3. The vacuum cleaner according to claim 1, wherein the control device supplies the voltage of the power storage device to the inverter by turning on the bypass switch when the non-boosting operation is selected. A temperature sensor for detecting the temperature of the power storage device;
The control device includes:
When the detection value of the temperature sensor is lower than a predetermined lower limit at the time of starting the vacuum cleaner, a temperature raising operation for raising the temperature of the power storage device by the boosting operation is performed,
When the detected value of the temperature sensor exceeds the predetermined lower limit during the temperature raising operation, the temperature raising operation is terminated and the electric blower generates the required suction force and the boost converter and the The vacuum cleaner of Claim 1 which controls an inverter. The control device is configured to control the output voltage of the boost converter according to a voltage command value during the boost operation,
The vacuum cleaner according to claim 4, wherein the voltage command value during the temperature raising operation is set to be lower than the voltage command value set based on the required suction force.   The said control apparatus stops the said pressure | voltage rise operation and the operation | movement of the said inverter, if the detected value of the said temperature sensor becomes higher than a predetermined | prescribed upper limit value at the time of the driving | operation of the said vacuum cleaner. The vacuum cleaner as described in. A voltage sensor for detecting a voltage of the power storage device;
In the step-up operation, the control device determines the step-up rate when the detected value of the voltage sensor is a first value with respect to the voltage command value set based on the required suction force, The vacuum cleaner according to claim 1, wherein a detected value is higher than the step-up rate when the second value is higher than the first value. The control device estimates a 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 7, wherein when the remaining capacity falls below a predetermined threshold, the boost operation is stopped and the operation of the inverter is stopped.

Images