JP2017189430A - Charge/discharge protection system and charging type vacuum cleaner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a charge/discharge protection system capable of protecting a secondary battery performing large current charge/discharge from high temperature.SOLUTION: The charge/discharge protection system according to the present invention comprises: a protection element that is provided on a wiring for performing charge/discharge on a secondary battery and cuts off the wiring according to a cut-off signal; temperature detection means that is also provided on the wiring and detects a temperature of the secondary battery; temperature comparison means that compares a detection temperature detected by the temperature detection means with a threshold temperature and, when the detection temperature changes from a temperature lower than the threshold temperature to that higher than the threshold temperature, outputs an abnormal temperature signal; and protection means for outputting the cut-off signal depending on the abnormal temperature signal output by the temperature comparison means. A charging type vacuum cleaner according to the present invention mounts the charge/discharge protection system.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a charge / discharge protection system and a rechargeable vacuum cleaner.

  Patent Document 1 discloses a method of interrupting a charge / discharge path with a thermal fuse in order to protect a secondary battery from a high temperature.

JP 2003-70705 A

  When a large current flows during charging / discharging of the secondary battery, the current value flowing through the charging / discharging path may exceed the rated current value of the thermal fuse. In this case, the method shown in Patent Document 1 cannot protect the secondary battery from high temperatures.

  The present invention has been made to solve the above-described problems. The objective of this invention is obtaining the charge / discharge protection system which can protect the secondary battery which charges / discharges a large current from high temperature.

A charge / discharge protection system according to the present invention is provided on a wiring for charging / discharging a secondary battery, and a protection element that blocks the wiring in response to a cutoff signal, and a temperature detection that detects the temperature of the secondary battery. A temperature comparison means that compares the detected temperature detected by the temperature detection means with a threshold temperature, and outputs an abnormal temperature signal when the detected temperature changes from a temperature lower than the threshold temperature to a higher temperature; and Protection means for outputting the shut-off signal in response to the abnormal temperature signal output by the temperature comparison means.
The rechargeable vacuum cleaner according to the present invention is equipped with the charge / discharge protection system.

  In the charge / discharge protection system and the rechargeable vacuum cleaner according to the present invention, the temperature of the secondary battery is detected as a detected temperature by the temperature detecting means. When the detected temperature changes from a temperature lower than the threshold temperature to a higher temperature, the protection means outputs a cutoff signal. As a result, the wiring for charging / discharging is interrupted by the protective element. According to the present invention, it is not necessary to provide a thermal fuse in the charge / discharge path. Therefore, even when a large current flows due to charge / discharge, the secondary battery can be protected from a high temperature.

It is a side view of the main body of the rechargeable vacuum cleaner which concerns on Embodiment 1 of this invention. It is the side view and sectional drawing of the rechargeable vacuum cleaner which concern on Embodiment 1 of this invention. 1 is a circuit block diagram of a charge / discharge protection system according to Embodiment 1 of the present invention. It is a timing chart explaining operation | movement of the charging / discharging protection system which concerns on Embodiment 1 of this invention.

  A charge / discharge protection system and a rechargeable vacuum cleaner according to an embodiment of the present invention will be described with reference to the drawings. The same or corresponding components are denoted by the same reference numerals, and repeated description may be omitted.

Embodiment 1 FIG.
FIG. 1 is a side view of a rechargeable vacuum cleaner body according to Embodiment 1 of the present invention. The rechargeable vacuum cleaner main body 100 includes an electric blower 104, a secondary battery 50, and a secondary battery protection system mounting board 90. When the rechargeable vacuum cleaner main body 100 is in operation, the secondary battery 50 is in a discharged state. The motor of the electric blower 104 is rotated by electric power supplied by the discharge of the secondary battery 50. Suction air is generated by the rotation of the motor. Due to the suction air, the dust on the floor surface is sucked into the suction port body 106 together with the air. The secondary battery protection system mounting board 90 is equipped with a charge / discharge protection system for protecting the secondary battery 50 from a temperature rise caused by the discharge of the secondary battery 50.

  FIG. 2 is a side view and a cross-sectional view of the rechargeable vacuum cleaner according to Embodiment 1 of the present invention. In FIG. 2, the rechargeable vacuum cleaner 300 shows a state where the rechargeable vacuum cleaner main body 100 is attached to the charging stand 200. The charging stand 200 includes a power cable 202. When the rechargeable vacuum cleaner main body 100 is attached to the charging stand 200, the power cable 202 and the secondary battery 50 are electrically connected. Therefore, the secondary battery 50 is charged by connecting the power cable 202 to the external power source. The secondary battery protection system mounting board 90 is equipped with a charge / discharge protection system for protecting the secondary battery 50 from a temperature rise accompanying charging of the secondary battery 50.

  FIG. 3 is a circuit block diagram of the charge / discharge protection system according to Embodiment 1 of the present invention. FIG. 3 shows a circuit block diagram of the charge / discharge protection system 10 in a discharged state. The secondary battery 50 generates a power supply voltage VDD. The positive electrode of the secondary battery 50 is connected to one end of the electric blower 104 that is a load. The other end of the electric blower 104 is connected to the negative electrode of the secondary battery 50. The negative electrode of the secondary battery 50 is connected to the reference power supply GND. Therefore, the power supply voltage VDD is supplied from the secondary battery 50 to the electric blower 104. The charge / discharge protection system 10 is connected between the electric blower 104 and the secondary battery 50.

  The charge / discharge protection system 10 includes a secondary battery protection system mounting substrate 90 and temperature detection means 21. The secondary battery protection system mounting substrate 90 includes a protection element on the wiring for charging and discharging the secondary battery 50. Here, the wiring for charging and discharging the secondary battery 50 is a wiring for connecting the electric blower 104 and the secondary battery 50.

  In the present embodiment, the protection element includes a charge protection element 40 and a discharge protection element 42. The charge protection element 40 and the discharge protection element 42 are n-channel MOSFETs. The source of the charge protection element 40 is connected to the electric blower 104. Further, the drain of the charge protection element 40 is connected to the drain of the discharge protection element 42. The source of the discharge protection element 42 is connected to the negative electrode of the secondary battery 50. Therefore, when the charge protection element 40 or the discharge protection element 42 is turned off, the wiring for charging / discharging is interrupted.

  The charge / discharge protection system 10 includes temperature detection means 21. The temperature detection unit 21 detects the temperature of the secondary battery 50. In the present embodiment, the temperature detection means 21 is a thermistor. The temperature detection means 21 is disposed in the vicinity of the secondary battery 50 so that the temperature of the secondary battery 50 can be detected. Further, the temperature detection means 21 may be arranged so as to be in contact with the secondary battery 50.

  The detected temperature detected by the temperature detecting means 21 is compared with a threshold temperature in the temperature comparing means 20. The threshold temperature is a temperature set to protect the secondary battery 50. One end of the temperature detection means 21 is connected to the positive electrode of the secondary battery 50. The other end of the temperature detection means 21 is connected to one end of the resistance element 22 provided in the temperature comparison means 20 and the inverting input terminal of the comparator 28. The other end of the resistance element 22 is connected to the reference power supply terminal 73. The reference power supply terminal 73 is a terminal for connecting the temperature comparison means 20 to the reference power supply GND. According to this configuration, the input voltage Vin obtained by dividing the power supply voltage VDD by the temperature detection means 21 and the resistance element 22 is input to the inverting input terminal of the comparator 28. Further, the other end of the temperature detecting means 21 is connected to a reference power supply terminal 73 via a capacitor 23.

  Furthermore, one end of the resistance element 24 is connected to one end of the temperature detection means 21. One end of the resistance element 25 and the non-inverting input terminal of the comparator 28 are connected to the other end of the resistance element 24. The other end of the resistance element 25 is connected to the reference power supply terminal 73. Therefore, the voltage V 1 obtained by dividing the power supply voltage VDD by the resistance element 24 and the resistance element 25 is input to the non-inverting input terminal of the comparator 28. The voltage V1 is a first threshold voltage. Further, the other end of the resistance element 24 is connected to the reference power supply terminal 73 via the capacitor 26.

  The comparator 28 outputs Low when the input voltage Vin exceeds the first threshold voltage V1. The positive power supply terminal of the comparator 28 is connected to one end of the resistance element 24. The negative power supply terminal of the comparator 28 is connected to the reference power supply terminal 73. A capacitor 27 is connected between the positive power supply terminal and the negative power supply terminal of the comparator 28. The output terminal of the comparator 28 is connected to the non-inverting input terminal via the resistance element 29.

  The comparator 28 and the resistance element 29 constitute a comparator 128 with hysteresis. In the comparator 128 with hysteresis, the threshold voltage V2 for changing the output from Low to Hi is set lower than the first threshold voltage V1 for changing the output from Hi to Low. The temperature comparison means 20 is comprised from the above.

  The reference power supply terminal 73 of the temperature comparison unit 20 is connected to the source of the second switching element 61 and the drain of the third switching element 67. The drain of the second switching element 61 is connected to a wiring that connects the charge protection element 40 and the discharge protection element 42. The source of the third switching element 67 is connected to a wiring that connects the discharge protection element 42 and the reference power supply GND. The third switching element 67 forms a ground bypass means 68.

  The output terminal of the comparator 28 is further connected to the cathode of the Zener diode 62, the positive electrode of the capacitor 63, the gates of the first switching element 36, the fourth switching element 64 and the fifth switching element 65. The anode of the Zener diode 62 and the negative electrode of the capacitor 63 are connected to the reference power supply GND. The first switching element 36 and the fifth switching element 65 are n-channel MOSFETs. The fourth switching element 64 is a p-channel type MOSFET.

  The source of the first switching element 36 is connected to the reference power supply GND. The drain of the first switching element 36 is connected to the charge / discharge enable / disable control terminal 31 of the control IC 30. The positive electrode of the secondary battery 50 is connected to the power supply terminal 32 of the control IC 30. For this reason, the power supply voltage VDD is an operating power supply for the control IC 30. The reference power supply terminal 33 of the control IC 30 is connected to the reference power supply GND.

  The cutoff signal output terminal 34 of the control IC 30 is connected to the discharge protection element 42 and the gate of the second switching element 61. The cutoff signal output terminal 35 of the control IC 30 is connected to the gate of the charge protection element 40. On / off of the charge protection element 40, the discharge protection element 42, and the second switching element 61 is controlled by the control IC 30. The first switching element 36 and the control IC 30 constitute a protection means 39.

  The source of the fourth switching element 64 is connected to the positive electrode of the secondary battery 50 via the resistance element 69. The drain of the fourth switching element 64 is connected to the drain of the fifth switching element 65. The source of the fifth switching element 65 is connected to the reference power supply GND. The fourth switching element 64 and the fifth switching element 65 constitute current consumption suppression means 66.

  The fourth switching element 64 and the fifth switching element 65 form a CMOS circuit. The output of the CMOS circuit is connected to the positive electrode of the capacitor 71, the cathode of the Zener diode 72, and the gate of the third switching element 67. The negative electrode of the capacitor 71 and the anode of the Zener diode are connected to the reference power supply GND.

  FIG. 4 is a timing chart for explaining the operation of the charge / discharge protection system according to Embodiment 1 of the present invention. In FIG. 4, the first stage of the timing chart shows the input voltage Vin to the comparator 28 in the temperature comparison means 20. The second stage shows the output voltage of the temperature comparison means 20 at point A in FIG. The third row shows the input voltage of the charge / discharge control terminal 31 at point B in FIG. The fourth stage shows the input voltage of the ground bypass means 68 at the point C in FIG. The fifth row shows the gate input voltages of the charge protection element 40, the discharge protection element 42, and the second switching element 61 at point D in FIG. The sixth row shows the load applied voltage applied between EF in FIG.

  The operation of the charge / discharge protection system 10 during discharge will be described with reference to FIG. At the time of discharging, the power supply voltage VDD is applied between E and F. At this time, the load is in a power supply state. Due to the discharge of the secondary battery 50, the temperature of the secondary battery 50 rises. Along with this, the resistance value of the temperature detecting means 21 which is a thermistor changes. As a result, the input voltage Vin of the comparator 28 increases.

  Here, the first threshold voltage V1 is adjusted to be equal to the input voltage Vin when the temperature detected by the temperature detecting means 21 reaches the threshold temperature. For this reason, when the temperature detected by the temperature detecting means 21 exceeds the threshold temperature, the input voltage Vin becomes larger than the first threshold voltage V1. As a result, the comparator 28 becomes a Low output. At this time, the voltage at point A decreases. Here, the Low output of the comparator 28 becomes an abnormal temperature signal.

  Due to the voltage drop at point A, the first switching element 36 is turned off. As a result, the voltage at point B rises to the internal power supply voltage of the control IC 30. The change in voltage at point B is input to the charge / discharge enable / disable control terminal 31 as abnormal temperature information.

  The control IC 30 outputs a cutoff signal from the cutoff signal output terminal 34 in accordance with the abnormal temperature information. As a result, among the points D, the gate input voltage of the discharge protection element 42 decreases. As a result, the discharge protection element 42 is turned off. Therefore, the wiring for discharging the secondary battery 50 is cut off. As a result, the voltage between E and F decreases. As a result, the charge / discharge protection system 10 is in a power supply stop state with respect to the load. From the above, the charge / discharge protection system 10 is in a battery temperature protection state during discharge.

  In the present embodiment, the operation of the charge / discharge protection system 10 when the secondary battery 50 is discharged has been described. At the time of charging, an external power source is connected between E and F. During charging, when the temperature of the secondary battery 50 rises and the detected temperature exceeds the threshold temperature, the comparator 28 outputs an abnormal temperature signal. As a result, the control IC 30 outputs a cutoff signal from the cutoff signal output terminal 35. Therefore, the gate input voltage of the charge protection element 40 decreases at the point D. As a result, the charge protection element 40 is turned off. Therefore, the wiring for charging the secondary battery 50 is interrupted, whereby the charge / discharge protection system 10 enters a battery temperature protection state during charging.

  In addition, during charging / discharging in which the secondary battery 50 is in a normal state, the second switching element 61 is on and the third switching element 67 is off. For this reason, the reference power supply terminal 73 of the temperature comparison means 20 is connected to the wiring connecting the charge protection element 40 and the discharge protection element 42. In contrast, when an abnormal temperature signal is output during discharge, a cutoff signal is output from the cutoff signal output terminal 34. For this reason, the voltage of D point falls. As a result, the gate input voltage of the second switching element 61 decreases. Accordingly, the second switching element 61 is turned off. Furthermore, the output of the current consumption suppression means 66, which is a CMOS circuit, increases due to the voltage drop at point A. As a result, the voltage at point C increases. Accordingly, the third switching element 67 is turned on. As a result, when the abnormal temperature signal is output, the reference power supply terminal 73 of the temperature comparison unit 20 is connected to the wiring that connects the discharge protection element 42 and the negative electrode of the secondary battery 50.

  Therefore, even if the wiring for charging / discharging is interrupted by the protective element, the temperature comparison means 20 is connected to the reference power supply GND via the ground bypass means 68. The second switching element 61, the consumption current suppression unit 66 and the ground bypass unit 68 form a ground switching unit 160. In the present embodiment, the drain of the second switching element 61 is connected to a wiring that connects the charge protection element 40 and the discharge protection element 42. On the other hand, the drain of the second switching element 61 may be connected to a wiring that connects the charge protection element 40 and the load.

  As another method of protecting the secondary battery from high temperature, a method of interrupting the charge / discharge path with a thermal fuse is conceivable. However, when the current flowing through the charging / discharging path becomes a large current of 15 A or more during charging / discharging, the current value may exceed the rated current value of the thermal fuse. In this case, a thermal fuse cannot be used to interrupt the charge / discharge path. Here, in the present embodiment, the wiring for charging and discharging is interrupted by turning off the protection element that is a MOSFET.

  In addition, the temperature fuse may vary greatly in the temperature at which it is blown. Therefore, in order to protect the secondary battery, it is necessary to set a low threshold temperature for determining the abnormal temperature in consideration of the fusing temperature variation. In contrast, in the present embodiment, a thermistor is used as the temperature detecting means 21. In general, a thermistor has a smaller variation in detection temperature than a thermal fuse. For this reason, the threshold temperature can be set higher than in the case of the thermal fuse.

  Also, in the secondary battery charge / discharge protection system, once the secondary battery temperature rises to the threshold temperature, it is necessary to continue the protection state even if the secondary battery temperature subsequently decreases. The Here, the charge / discharge protection system 10 according to the present embodiment includes a comparator 128 with hysteresis. As indicated by an arrow 82, in the comparator 128 with hysteresis, the threshold voltage V2 for changing the output from Low to Hi is set lower than the first threshold voltage V1 for changing the output from Hi to Low.

  When the temperature detected by the temperature detection means 21 exceeds the threshold temperature, the output of the temperature comparison means 20 at point A changes from Hi to Low. At this time, an abnormal temperature signal is output. Thereafter, even if the detected temperature falls below the threshold temperature, the output does not change from Low to Hi in the range of Vin> V2. For this reason, the Low output is maintained in the range of Vin> V2.

  Therefore, by setting V2 sufficiently low, the output of the abnormal temperature signal can be held. In the present embodiment, V2 is set lower than the value of Vin before the temperature of secondary battery 50 rises. For this reason, it is possible to keep the wiring for charging / discharging in a disconnected state even after the temperature of the secondary battery 50 is lowered. From the above, as shown by the arrow 81 in FIG. 4, even after the battery temperature protection state is reached, the protection state can be continued even if the temperature of the secondary battery 50 falls below the threshold temperature.

  Moreover, when the voltage of the secondary battery 50 falls to a predetermined value, the charge / discharge protection system 10 enters an overdischarge protection state. The overdischarge protection state is a state for preventing the secondary battery 50 from being overdischarged. In the overdischarge protection state, the temperature comparison means 20 is not necessary. For this reason, when the charge / discharge protection system 10 enters the overdischarge protection state, it is necessary to reduce the current consumed by the temperature comparison means 20 in order to suppress the voltage drop of the secondary battery 50.

  On the other hand, in the present embodiment, when the charge / discharge protection system 10 is in the overdischarge protection state, the discharge protection element 42 and the second switching element 61 are shut off. Further, the third switching element 67 is cut off before it enters the overdischarge protection state. Accordingly, in the overdischarge protection state, the ground of the temperature comparison means 20 is in an open state. As a result, the current consumed by the temperature comparison means 20 can be reduced. In addition, since the consumption current suppressing means 66 for holding the third switching element 67 in the cut-off state is configured by a CMOS circuit, the consumption current of the entire charge / discharge protection system 10 can be suppressed.

  Further, when the charge / discharge protection system 10 is in an abnormal battery temperature state, the third switching element 67 is turned on. Here, the abnormal battery temperature state is a state in which an abnormal temperature signal is output. When the secondary battery 50 is not charged in the abnormal battery temperature state and the power supply voltage VDD decreases, the charge / discharge protection system 10 enters an overdischarge protection state. When the charge / discharge protection system 10 enters the overdischarge protection state, the discharge protection element 42 is shut off. Here, since the gates of the discharge protection element 42 and the second switching element 61 are connected, when the discharge protection element 42 is cut off, the second switching element 61 is also cut off at the same time. According to this configuration, when the charge / discharge protection system 10 changes from the abnormal battery temperature state to the overdischarge protection state, the negative electrode of the secondary battery 50 is connected to the third switching element 67, the second switching element 61, and the charge protection element 40. The path bypassed to the load via is blocked. Therefore, when the charge / discharge protection system 10 changes from the abnormal battery temperature state to the overdischarge protection state, it is possible to prevent the load from being discharged. For this reason, when the second switching element 61 is cut off, the charge / discharge protection system 10 can continue the overdischarge protection state so as not to be in a dischargeable state with respect to the load.

  In the present embodiment, the charge protection element 40 and the discharge protection element 42 are connected in series on the same wiring. In the wiring for charging and discharging, the charge protection element 40 is disposed on the load side, and the discharge protection element 42 is disposed on the secondary battery side. As a modified example, the discharge protection element 42 may be disposed on the load side, and the charge protection element 40 may be disposed on the secondary battery side.

  In this embodiment, two protection elements are arranged on the wiring for charging / discharging. If the detected temperature exceeds the threshold temperature during charging, the charge protection element 40 is cut off. Further, when the detected temperature exceeds the threshold temperature during discharge, the discharge protection element 42 is shut off. On the other hand, one protective element may be arranged on the wiring for charging / discharging. In this case, the interruption during charging and discharging is performed by the same protection element. Further, a wiring for charging and a wiring for discharging may be provided separately. In this structure, the charge protection element 40 is connected to the wiring for charging, and the discharge protection element 42 is connected to the wiring for discharging.

  Further, the protection means 39 includes the first switching element 36 and the control IC 30. Here, the protection means 39 may have another configuration as long as it has a function of outputting a cutoff signal in response to the abnormal temperature signal. For example, the protection means 39 may be one control IC. In addition, in the present embodiment, the configuration in which the charge / discharge protection system 10 is mounted on the rechargeable vacuum cleaner 300 has been described. Can also be applied.

  As a modification of the present embodiment, the charge / discharge protection system 10 may have a function of cutting off the wiring for discharging when the voltage generated by the secondary battery 50 is reduced. The charge / discharge protection system 10 in this modification includes a voltage detection circuit that detects the power supply voltage VDD. In addition, the charge / discharge protection system 10 according to the present modification includes a wiring for charging and a wiring for discharging separately.

  The detection voltage detected by the voltage detection circuit is notified to the control IC 30. When the detected voltage decreases to the second threshold voltage, the control IC 30 outputs a cutoff signal from the cutoff signal output terminal 34. The 2nd threshold voltage said here is a threshold value for the charging / discharging protection system 10 to change to an overdischarge protection state so that the secondary battery 50 may not reach an overdischarge state. The second threshold voltage per one secondary battery 50 is, for example, 3.0 V or less. The discharge protection element 42 cuts off the wiring for discharging according to the cut-off signal. As a result, the charge / discharge protection system 10 enters an overdischarge protection state in which the discharge path to the load is blocked. According to this modification, it is possible to suppress the discharge current when the power supply voltage VDD decreases without the secondary battery 50 being charged. In the overdischarge protection state, the wiring for charging is not interrupted. Therefore, in the overdischarge protection state, the discharge to the load is cut off and the current consumption is suppressed to the minimum, but the charging is possible. For this reason, it becomes possible to keep the period until the secondary battery 50 will be in an overdischarged state long. Therefore, it is possible to ensure a long period during which the user can safely charge the secondary battery 50 until it reaches the overdischarged state.

DESCRIPTION OF SYMBOLS 10 Charge / discharge protection system, 300 Rechargeable vacuum cleaner, 20 Temperature comparison means, 21 Temperature detection means, 30 Control IC, 36 1st switching element, 39 Protection means, 40 Charge protection element, 42 Discharge protection element, 50 Secondary Battery, 128 comparator with hysteresis, 160 ground switching means

Claims (10)

A protective element that is provided on the wiring for charging and discharging the secondary battery, and shuts off the wiring in response to a shutoff signal;
Temperature detecting means for detecting the temperature of the secondary battery;
A temperature comparison unit that compares the detected temperature detected by the temperature detection unit with a threshold temperature, and outputs an abnormal temperature signal when the detected temperature changes from a temperature lower than the threshold temperature to a higher temperature;
Protection means for outputting the cutoff signal in response to the abnormal temperature signal output by the temperature comparison means;
A charge / discharge protection system comprising:   The charge / discharge protection system according to claim 1, wherein the temperature comparison unit holds the abnormal temperature signal when the detected temperature changes from a temperature higher than the threshold temperature to a lower temperature.   The charge / discharge protection system according to claim 2, wherein the temperature comparison unit includes a comparator with hysteresis for comparing an input voltage corresponding to the detected temperature with a first threshold voltage corresponding to the threshold temperature.   The charge / discharge protection system according to claim 1, wherein the temperature detection unit is a thermistor. The protective means is
A first switching element that outputs abnormal temperature information in response to the abnormal temperature signal output by the temperature comparing means;
A control IC that outputs the cutoff signal in response to the abnormal temperature information output by the first switching element;
The charge / discharge protection system according to any one of claims 1 to 4, further comprising:   The said protection element is equipped with the charge protection element which interrupts | blocks the wiring for charging the said secondary battery according to the said interruption | blocking signal which the said protection means outputs, The any one of Claims 1-5 characterized by the above-mentioned. The charge / discharge protection system according to 1.   The said protection element is provided with the discharge protection element which interrupts | blocks the wiring for discharging the said secondary battery according to the said interruption | blocking signal which the said protection means outputs. The charge / discharge protection system according to 1.   The reference power supply terminal of the temperature comparison means is connected to a load that connects the protection element with a load that receives power supply from the secondary battery at the time of charging and discharging, and at the time of outputting the abnormal temperature signal, the protection element and the The charge / discharge protection system according to any one of claims 1 to 7, further comprising a ground switching unit that connects to a wiring that connects a negative electrode of the secondary battery.   The charging according to claim 7, wherein the discharge protection element cuts off a wiring for discharging the secondary battery when a voltage generated by the secondary battery is lower than a second threshold voltage. Discharge protection system.   The rechargeable vacuum cleaner carrying the charging / discharging protection system of any one of Claims 1-9.

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