Refrigerating box and battery charging and discharging circuit thereof

Abstract

The utility model discloses a refrigerated container and a battery charging and discharging circuit thereof, which comprise a rechargeable battery, a first load and a second load, the voltage of the first load is higher than that of the rechargeable battery, the voltage of the second load is higher than that of the first load, and the battery charging and discharging circuit further comprises an isolating circuit. The isolating circuit comprises a PMOS (P-channel Metal Oxide Semiconductor) tube, and a first diode and a second diode which are arranged in parallel; the positive electrode of the first diode and the positive electrode of the second diode are connected with a first load; the negative electrode of the first diode, the negative electrode of the second diode and the source electrode of the PMOS tube are all connected with the second load, and the drain electrode of the PMOS tube is connected with the rechargeable battery. When the refrigeration box is powered off, the rechargeable battery is discharged, and the PN junction of the PMOS tube can prevent the voltage and / or current of the first load and the second load from flowing to the rechargeable battery, so that electronic components in the rechargeable battery cannot be damaged, the rechargeable battery can operate normally, and subsequent use of the refrigeration box cannot be affected.

Description

Technical Field

[0001] The utility model relates to the technical field of refrigeration, in particular to a refrigerated box and a battery charging and discharging circuit thereof. Background Art

[0002] In the field of medical refrigeration equipment, the storage conditions of many drugs and vaccines need to be controlled between 2°C and 8°C. Therefore, many refrigeration enterprises in the industry have developed various models and categories of medical refrigerated box products. Moreover, medical refrigerated boxes are used in medical places. In addition to meeting the requirement of uniform temperature, due to their special use, such as the need to provide alarm protection during power outages to prevent drug deterioration caused by untimely treatment.

[0003] In the early stage, the commonly used method in the industry was to additionally add a lead-acid battery as a backup power source. When the medical refrigerated box was operating normally, the main power supply would also charge the backup power source. In this way, when the main power supply was cut off due to an accident, the medical refrigerated box could still be powered by the backup power source. The disadvantage of this scheme was that it occupied a large space and was too bulky.

[0004] Therefore, to solve the problem of large occupied space, existing enterprises use lithium batteries as the backup power source for medical refrigerated boxes. Lithium batteries have the characteristics of small volume and high energy density. However, the voltage of lithium batteries is generally lower than the load voltage inside the medical refrigerated box. Therefore, when the main power supply is cut off and the medical refrigerated box can only be powered by the backup power source, the lithium battery may be "back-fed" by the voltage or current of the load, resulting in damage to the electronic components inside the lithium battery and affecting the subsequent use of the medical refrigerated box. Summary of the Utility Model

[0005] In view of this, the utility model provides a refrigerated box and a battery charging and discharging circuit thereof, which are used to solve the problem that the rechargeable battery inside the refrigerated box in the prior art is easily "back-fed" by the voltage or current of the load, resulting in damage to the electronic components inside the lithium battery.

[0006] The technical solution of the utility model is a battery charging and discharging circuit of a refrigerated box, which includes a rechargeable battery, a first load and a second load with a voltage higher than that of the rechargeable battery, and the voltage of the first load is higher than that of the second load. The battery charging and discharging circuit further includes an isolation circuit, and the isolation circuit includes a PMOS transistor, and a first diode and a second diode connected in parallel;

[0007] The positive electrodes of the first diode and the second diode are both connected to the first load; the negative electrode of the first diode, the negative electrode of the second diode and the source electrode of the PMOS transistor are all connected to the second load, and the drain electrode of the PMOS transistor is connected to the rechargeable battery;

[0008] Wherein, when the refrigerator is powered off, the rechargeable battery discharges, and the PN junction of the PMOS transistor can block the voltage and / or current of the first load and the second load from flowing to the rechargeable battery.

[0009] Further, the battery charging and discharging circuit further includes a driving circuit for controlling the on / off of the PMOS transistor.

[0010] Further, the driving circuit includes a first resistor, a second resistor, a third resistor, a fourth resistor, a first triode, and a zener diode;

[0011] The base of the first triode is respectively connected to the first end of the first resistor and the first end of the third resistor, and the second end of the first resistor is connected to the first control port of the MCU;

[0012] The collector of the first triode is connected to the first end of the second resistor, and the second end of the second resistor, the positive pole of the zener diode, and the first end of the fourth resistor are all connected to the gate of the PMOS transistor; the source of the PMOS transistor, the negative pole of the zener diode, and the second end of the fourth resistor are all connected to the power supply pin of the second load;

[0013] The emitter of the first triode and the second end of the third resistor are grounded.

[0014] Further, at least one fifth resistor is provided between the PMOS transistor and the rechargeable battery, and the fifth resistor is used to limit the charging current flowing to the rechargeable battery.

[0015] Further, the battery charging and discharging circuit further includes a control circuit for reducing the power consumption of the fifth resistor when the rechargeable battery is discharging.

[0016] Further, the control circuit includes a first relay, a second triode, a sixth resistor, and a third diode;

[0017] The emitter of the second triode is grounded, the base of the second triode is connected to the second control port of the MCU in series with the sixth resistor, the collector of the second triode is respectively connected to the positive pole of the third diode and the positive pole of the coil of the first relay, and the negative pole of the coil of the first relay and the negative pole of the third diode are both connected to the power supply pin of the second load;

[0018] The common terminal of the first relay is connected between the PMOS transistor and the fifth resistor, and the normally open terminal of the first relay is connected between the rechargeable battery and the fifth resistor.

[0019] Further, the battery charging and discharging circuit further includes a first detection circuit for detecting the voltage of the rechargeable battery, and the first detection circuit includes a seventh resistor, an eighth resistor, and a first capacitor;

[0020] The second terminal of the seventh resistor is connected to the rechargeable battery, and the first terminal of the seventh resistor, the first terminal of the eighth resistor, and the first terminal of the first capacitor are all connected to the first AD port of the MCU;

[0021] The second terminal of the first capacitor and the second terminal of the eighth resistor are both grounded.

[0022] Further, the battery charging and discharging circuit further includes a second detection circuit for detecting the voltage of the first load, and the second detection circuit includes a ninth resistor, a tenth resistor, and a second capacitor;

[0023] The first terminal of the ninth resistor is connected to the first load, and the second terminal of the ninth resistor, the second terminal of the tenth resistor, and the first terminal of the second capacitor are all connected to the second AD port of the MCU;

[0024] The second terminal of the second capacitor and the first terminal of the tenth resistor are both grounded.

[0025] Further, the battery charging and discharging circuit further includes an alarm circuit, and the alarm circuit includes a second relay, a third capacitor, a fourth diode, and a connection terminal for connecting to a remote alarm system;

[0026] The positive pole of the coil of the second relay, the first terminal of the third capacitor, and the positive pole of the fourth diode are all connected to the output terminal of the MCU, and the negative pole of the coil of the second relay, the second terminal of the third capacitor, and the negative pole of the fourth diode are all connected to the power supply pin of the second load;

[0027] The normally closed terminal of the second relay is connected to pin 1 of the connection terminal, the common terminal of the second relay is connected to pin 2 of the connection terminal, and the normally open terminal of the second relay is connected to pin 3 of the connection terminal.

[0028] The present utility model also provides a refrigerated box, and the refrigerated box includes the above-mentioned battery charging and discharging circuit.

[0029] Compared with the prior art, the present utility model has at least the following beneficial effects:

[0030] The present utility model uses an isolation circuit to prevent the residual voltage or current of the first load and the second load from flowing to the rechargeable battery, so as to ensure that the electronic components inside the rechargeable battery will not be damaged, the rechargeable battery can operate normally, and it will not affect the subsequent use of the refrigerated box. Description of the Drawings

[0031] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which this utility model belongs; the terms used in the specification of this application herein are only for the purpose of describing specific embodiments and are not intended to limit this utility model; the terms "comprising" and "having" and any variations thereof in the specification and claims of this utility model and the above-mentioned drawings are intended to cover non-exclusive inclusion. The terms "first", "second", etc. in the specification and claims of this utility model or the above-mentioned drawings are used to distinguish different objects and are not used to describe a specific order.

[0032] To more clearly illustrate the technical solutions in the embodiments of this utility model, the following will briefly introduce the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of this utility model. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0033] Figure 1 It is the circuit diagram of the battery charging and discharging circuit of this utility model;

[0034] Figure 2 It is the circuit diagram of the alarm circuit of this utility model;

[0035] Figure 3 It is the block diagram of the battery charging and discharging circuit of this utility model.

[0036] Reference numerals:

[0037] 10. Rechargeable battery;

[0038] 20. First load;

[0039] 30. Second load;

[0040] 40. Isolation circuit;

[0041] 50. Drive circuit;

[0042] 60. Relay control circuit;

[0043] 70. First detection circuit;

[0044] 80. Second detection circuit;

[0045] 90. Alarm circuit. Detailed implementation manners

[0046] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present utility model more clear and understandable, the present utility model will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present utility model and are not used to limit the present utility model. Thus, a feature pointed out in this specification will be used to illustrate one of the features of one embodiment of the present utility model, rather than implying that each embodiment of the present utility model must have the illustrated feature. In addition, it should be noted that this specification describes many features. Although certain features may be combined to show possible system designs, these features may also be used in other combinations not specifically described. Thus, unless otherwise stated, the described combinations are not intended to be limiting.

[0047] The principle and structure of the present utility model will be described in detail below with reference to the accompanying drawings and embodiments.

[0048] Embodiment 1

[0049] In the prior art, lithium batteries are generally used as the backup power supply for the refrigerated box. Lithium batteries have the characteristics of small volume and high energy density. However, the voltage of lithium batteries is generally lower than the load voltage in the refrigerated box. Therefore, when the main power supply is cut off and the refrigerated box can only rely on the backup power supply, the lithium battery may be "backfed" by the voltage or current of the load, resulting in damage to the electronic components inside the lithium battery and affecting the subsequent use of the refrigerated box.

[0050] To solve the above problems, referring to the attached Figure 1 and 3 , the present utility model proposes a battery charging and discharging circuit for a refrigerated box, including a rechargeable battery 10, a first load 20 and a second load 30 with voltages higher than that of the rechargeable battery 10, and the voltage of the first load 20 is higher than that of the second load 30. The battery charging and discharging circuit further includes an isolation circuit 40, and the isolation circuit 40 includes a PMOS transistor U1, and a first diode D1 and a second diode D2 connected in parallel;

[0051] The positive poles of the first diode D1 and the second diode D2 are both connected to the +13.3V pin of the first load 20; the negative poles of the first diode D1 and the second diode D2 and the source electrode of the PMOS transistor U1 are all connected to the +12V pin of the second load 30, and the drain electrode of the PMOS transistor U1 is connected to the rechargeable battery 10;

[0052] Wherein, when the refrigerated box is powered off, the rechargeable battery 10 discharges, and the PN junction of the PMOS transistor U1 can block the voltage and / or current of the first load 20 and the second load 30 from flowing to the rechargeable battery 10.

[0053] It should be noted that in this embodiment, the refrigerated box is exemplified by a medical refrigerated box, the first load 20 in this embodiment is exemplified by a 13.3V fan load, and the second load 30 in this embodiment is exemplified by a 12V relay load.

[0054] The refrigerated box is also provided with an MCU. When the refrigerated box is operating normally, the main power supply also provides a power supply voltage to the first load 20 and the second load 30, and the main power supply also supplies power to the MCU to enable the MCU to turn on the PMOS transistor U1, so that the +13.3V pin of the first load 20 can charge the rechargeable battery 10; and there is also a parasitic diode in the PMOS transistor U1 (this parasitic diode is equivalent to a PN junction), the positive pole of the parasitic diode is connected to the drain of the PMOS transistor U1, and the negative pole of the parasitic diode is connected to the source of the PMOS transistor U1.

[0055] In this way, when the main power supply in the refrigerated box is powered off due to an accident, causing the refrigerated box to rely only on the rechargeable battery 10 for power supply, at this time the output voltage of the first load 20 is zero and the first load 20 does not work; and the MCU controls the PMOS transistor U1 to disconnect due to the power off, so at this time the residual voltage or current of the first load 20 and the second load 30 cannot "back-feed" to the rechargeable battery 10 through the PMOS transistor U1, that is, the residual voltage or current of the first load 20 and the second load 30 cannot flow to the rechargeable battery 10 through the PMOS transistor U1, so as to ensure that the electronic components inside the rechargeable battery 10 will not be damaged, and further ensure that the rechargeable battery 10 can operate normally and will not affect the subsequent use of the refrigerated box. And the first diode D1 and the second diode D2 can also block the voltage or current of the second load 30 from flowing to the first load 20.

[0056] When the rechargeable battery 10 discharges, the discharge current is divided into two paths after passing through the parasitic diode of the PMOS transistor U1. One path of the discharge current flows to the second load 30 to enable the second load 30 to continue operating after being powered on; the other path, due to the presence of the first diode D1 and the second diode D2, causes the discharge current to not flow to the first load 20, and the first load 20 remains in a powered-off state.

[0057] It should be noted that in this embodiment, the rechargeable battery 10 is exemplified by 6 3.7V lithium batteries, and 3 lithium batteries are connected in series, with a total of 2 groups. The total capacity of the rechargeable battery 10 is 5200mAh. Of course, the total capacity of the rechargeable battery 10 can also be selected as other values according to the actual situation, which is not limited here.

[0058] Among them, to ensure that the PMOS transistor U1 can control the on / off of the PMOS transistor U1 according to whether the refrigerated box is powered off, referring to the attached Figure 3 , the battery charging and discharging circuit of the present utility model further includes a driving circuit 50, and the driving circuit 50 is used to control the on / off of the PMOS transistor U1.

[0059] Specifically, referring to the attached Figure 1 , the drive circuit 50 includes a first resistor R1, a second resistor R2, a third resistor R3, a fourth resistor R4, a first triode Q1, and a zener diode ZD1;

[0060] The base of the first triode Q1 is respectively connected to the first end of the first resistor R1 and the first end of the third resistor R3, and the second end of the first resistor R1 is connected to the first control port BC of the MCU;

[0061] The collector of the first triode Q1 is connected to the first end of the second resistor R2, and the second end of the second resistor R2, the positive electrode of the zener diode ZD1, and the first end of the fourth resistor R4 are all connected to the gate of the PMOS transistor U1; the source of the PMOS transistor U1, the negative electrode of the zener diode ZD1, and the second end of the fourth resistor R4 are all connected to the +12V pin of the second load 30;

[0062] The emitter of the first triode Q1 and the second end of the third resistor R3 are grounded.

[0063] In this way, when the refrigerator is running normally, the MCU will output a high-voltage signal to the first triode Q1, and the voltage of this high-voltage signal is higher than the dead zone voltage of the base-emitter voltage (Vbe) of the first triode Q1 to turn on the first triode Q1. After the first triode Q1 is turned on, it will pull down the gate voltage of the PMOS transistor U1. When the gate voltage of the PMOS transistor U1 is low enough to its conduction threshold, the PMOS transistor U1 will conduct. In this way, the voltage of the +13.3V pin of the first load 20 will charge the rechargeable battery 10 through the first diode D1, the second diode D2, and the PMOS transistor U1; similarly, when the main power supply in the refrigerator is powered off due to an accident, resulting in the refrigerator relying only on the rechargeable battery 10 for power supply, at this time the MCU will not output a high-voltage signal to the first triode Q1, resulting in the first triode Q1 being in an off state at this time, and then resulting in the PMOS transistor U1 also being in an off state, and then resulting in the residual voltage or current of the first load 20 and the second load 30 at this time not being able to "backfeed" to the rechargeable battery 10 through the PMOS transistor U1 to ensure that the rechargeable battery 10 can operate normally and will not affect the subsequent use of the refrigerator.

[0064] Among them, to limit the charging current flowing from the +13.3V pin of the first load 20 to the rechargeable battery 10, referring to the attached Figure 1 , at least one fifth resistor R5 is also provided between the PMOS transistor U1 and the rechargeable battery 10.

[0065] It should be noted that there is only one fifth resistor R5 between the PMOS transistor U1 and the rechargeable battery 10 in this embodiment, and the fifth resistor R5 is preferably a current-limiting resistor.

[0066] Among them, when the rechargeable battery 10 discharges, in order to reduce the power consumption of the fifth resistor R5, referring to the appendix Figure 1 and 3 , the battery charge and discharge circuit further includes a control circuit 60, and the control circuit 60 is used to reduce the power consumption of the fifth resistor R5 when the rechargeable battery 10 discharges.

[0067] Specifically, referring to the appendix Figure 1 , the control circuit 60 includes a first relay K1, a second triode Q2, a sixth resistor R6, and a third diode D3;

[0068] The emitter of the second triode Q2 is grounded. The base of the second triode Q2 is connected to the second control port DC of the MCU in series with the sixth resistor R6. The collector of the second triode Q2 is respectively connected to the positive pole of the third diode D3 and the positive pole of the coil of the first relay K1. The negative pole of the coil of the first relay K1 and the negative pole of the third diode D3 are both connected to the +12V pin of the second load 30;

[0069] The common terminal of the first relay K1 is connected between the PMOS transistor U1 and the fifth resistor R5, and the normally open terminal of the first relay K1 is connected between the rechargeable battery 10 and the fifth resistor R5.

[0070] In this way, when the refrigerator is powered off and the rechargeable battery 10 is discharging, due to the large power consumption of the second load 30, the MCU will output a high voltage signal to the second triode Q2. The voltage of this high voltage signal is higher than the dead zone voltage of the base-emitter voltage (Vbe) of the second triode Q2 to turn on the second triode Q2. After the second triode Q2 is turned on, it will cause the first relay K1 to close, resulting in a short circuit of the fifth resistor R5, thereby reducing the power consumption of the fifth resistor R5.

[0071] It should be noted that when the rechargeable battery 10 is in the charging state, the MCU will not output a high voltage signal to the second triode Q2 to turn off the second triode Q2, and then turn off the first relay K1 to ensure that the rechargeable battery 10 can be stably charged.

[0072] Among them, referring to the appendix Figure 2 , the battery charge and discharge circuit further includes an alarm circuit 90, and the alarm circuit 90 includes a second relay K2, a third capacitor C3, a fourth diode D4, and a connection terminal CN1 for connecting to a remote alarm system;

[0073] The positive pole of the coil of the second relay K2, the first end of the third capacitor C3, and the positive pole of the fourth diode D4 are all connected to the output terminal OUT of the MCU. The negative pole of the coil of the second relay K2, the second end of the third capacitor C3, and the negative pole of the fourth diode D4 are all connected to the +12V pin of the second load 30.

[0074] The normally closed end of the second relay K2 is connected to pin 1 of the connection terminal CN1. The common end of the second relay K2 is connected to pin 2 of the connection terminal CN1. The normally open end of the second relay K2 is connected to pin 3 of the connection terminal CN1.

[0075] It should be noted that the remote alarm system includes a buzzer and an alarm light, and the remote alarm system is a prior art, so no more details will be given here.

[0076] When the main power supply in the refrigerator compartment is powered off due to an accident, or the battery voltage of the rechargeable battery 10 is lower than the preset value, or the load voltage of the first load 20 is lower than the preset value, the MCU controls the second relay K2 to close, so that the current passes through the connection terminal CN1, thereby activating the remote alarm system, that is, the alarm light on the display board of the refrigerator compartment flashes, and the flashing frequency is: 0.5s (on) - 0.5s (off). The power-off alarm light is always on, and the buzzer sounds for 3 minutes every cycle.

[0077] It should be noted that after the main power supply in the refrigerator compartment of this embodiment is powered off due to an accident, the fully charged rechargeable battery 10 can ensure that it can still alarm effectively for a long time within 48 hours after the power-off.

[0078] Among them, referring to the attached Figure 1 and 3 , the battery charge and discharge circuit further includes a first detection circuit 70 for detecting the voltage of the rechargeable battery 10. The first detection circuit 70 includes a seventh resistor R7, an eighth resistor R8, and a first capacitor C1.

[0079] The second end of the seventh resistor R7 is connected to the positive pole of the rechargeable battery 10. The first end of the seventh resistor R7, the first end of the eighth resistor R8, and the first end of the first capacitor C1 are all connected to the first AD port AD - BAT of the MCU.

[0080] The second end of the first capacitor C1 and the second end of the eighth resistor R8 are both grounded.

[0081] In this way, when the refrigerator is just out of the factory and powered on for the first time, the MCU can collect the battery voltage of the rechargeable battery 10 through the first AD port AD - BAT, and judge whether the battery voltage exceeds the set first threshold voltage. If the battery voltage exceeds the first threshold voltage, the rechargeable battery 10 stops charging.

[0082] If the battery voltage does not exceed the first threshold voltage, the MCU also needs to determine whether the charging time of the rechargeable battery 10 exceeds the set first threshold time;

[0083] If the charging time does not exceed the first threshold time, the rechargeable battery 10 continues to charge;

[0084] If the charging time exceeds the first threshold time, even if the battery voltage has not exceeded the first threshold voltage yet, the rechargeable battery 10 still needs to stop charging to prevent overcharging of the rechargeable battery 10; however, if the charging time exceeds the first threshold time and the battery voltage is still lower than the second threshold voltage, the MCU controls the second relay K2 to close, so that the current passes through the connection terminal CN1, thereby activating the remote alarm system to remind the user that the rechargeable battery 10 of the refrigerator has a fault and needs to be repaired as soon as possible to ensure the subsequent normal operation of the refrigerator.

[0085] Then, after the rechargeable battery 10 stops charging, the MCU also needs to determine whether the battery voltage is lower than the third threshold voltage;

[0086] If the battery voltage is lower than the third threshold voltage, the rechargeable battery 10 needs to be charged again according to the above steps;

[0087] If the battery voltage is not lower than the third threshold voltage, the rechargeable battery 10 does not need to be charged.

[0088] And when the refrigerator is just out of the factory, the battery voltage of the rechargeable battery 10 in the refrigerator is higher than the fourth threshold voltage. If the refrigerator is left unused for a long time after leaving the factory, the MCU will detect whether the battery voltage is higher than the fourth threshold voltage and whether the duration reaches the second threshold time;

[0089] If the battery voltage is higher than the fourth threshold voltage and the duration reaches the second threshold time, then the MCU controls the second relay K2 to close, so that the current passes through the connection terminal CN1, thereby activating the remote alarm system to remind the user that the rechargeable battery 10 of the refrigerator has a fault and needs to be repaired as soon as possible to ensure the subsequent normal operation of the refrigerator.

[0090] It should be noted that the first threshold voltage is preferably 11.7V, the second threshold voltage is preferably 10V, the third threshold voltage is preferably 11V, the fourth threshold voltage is preferably 9V, the first threshold time is preferably 10H, and the first threshold time is preferably 5s. And the MCU re-detects every 10H.

[0091] Among them, referring to the appendix Figure 1 and 3, the battery charging and discharging circuit further includes a second detection circuit 80 for detecting the voltage of the first load 20, and the second detection circuit 80 includes a ninth resistor R9, a tenth resistor R10, and a second capacitor C2;

[0092] The first end of the ninth resistor R9 is connected to the 13.3V pin of the first load 20, and the second end of the ninth resistor R9, the second end of the tenth resistor R10, and the first end of the second capacitor C2 are all connected to the second AD port AD-13.3V of the MCU;

[0093] The second end of the second capacitor C2 and the first end of the tenth resistor R10 are both grounded.

[0094] In this way, the MCU can collect the load voltage of the first load 20 through the second AD port AD-13.3V, and determine whether the load voltage is lower than the set fifth threshold voltage;

[0095] If the load voltage is lower than the fifth threshold voltage, the MCU controls the second relay K2 to close, so that the current passes through the connection terminal CN1, thereby activating the remote alarm system to remind the user that the rechargeable battery 10 of the refrigerator needs to be repaired as soon as possible to ensure the normal operation of the refrigerator. At this time, the MCU will send data such as the power outage time and the compartment temperature to the EEPROM in the refrigerator for the EEPROM to record for subsequent maintenance personnel to view.

[0096] If the load voltage is not lower than the fifth threshold voltage, the rechargeable battery 10 continues to discharge.

[0097] It should be noted that the fifth threshold voltage is preferably 8V.

[0098] Embodiment 2

[0099] The present invention also proposes a refrigerator, and the refrigerator includes the above-mentioned battery charging and discharging circuit.

[0100] In this way, when the main power supply in the refrigerator is powered off due to an accident, resulting in the refrigerator relying only on the rechargeable battery 10 for power supply, at this time, the output voltage of the first load 20 is zero and the first load 20 does not work; and the MCU controls the PMOS transistor U1 to disconnect due to the power outage. Therefore, the residual voltage or current of the first load 20 and the second load 30 at this time cannot "backflow" to the rechargeable battery 10 through the PMOS transistor U1, that is, the residual voltage or current of the first load 20 and the second load 30 cannot flow to the rechargeable battery 10 through the PMOS transistor U1, thereby ensuring that the electronic components inside the rechargeable battery 10 will not be damaged, and further ensuring that the rechargeable battery 10 can operate normally and will not affect the subsequent use of the refrigerator. And the first diode D1 and the second diode D2 can also block the voltage or current of the second load 30 from flowing to the first load 20.

[0101] Moreover, when the rechargeable battery 10 discharges, the discharge current is divided into two paths after passing through the parasitic diode of the PMOS transistor U1. One path of the discharge current flows to the second load 30 to power on the second load 30 to continue operating; the other path, due to the presence of the first diode D1 and the second diode D2, causes the discharge current not to flow to the first load 20, and the first load 20 remains in a powered-off state.

[0102] Obviously, the embodiments described above are only a part of the embodiments of the present invention, rather than all of the embodiments. The accompanying drawings show the preferred embodiments of the present invention, but do not limit the patent scope of the present invention. The present invention can be implemented in many different forms. On the contrary, the purpose of providing these embodiments is to make the understanding of the disclosed content of the present invention more thorough and comprehensive. Although the present invention has been described in detail with reference to the foregoing embodiments, for those skilled in the art, they can still modify the technical solutions described in the foregoing specific embodiments, or perform equivalent replacements on some of the technical features. Any equivalent structure directly or indirectly using the content of the specification and drawings of the present invention in other related technical fields is similarly within the scope of the patent protection of the present invention.

Claims

1. The battery charge and discharge circuit of a refrigerator, comprising a rechargeable battery (10), a first load (20) and a second load (30) with voltages higher than that of the rechargeable battery (10), and the voltage of the first load (20) is higher than that of the second load (30), characterized in that, The battery charging and discharging circuit further includes an isolation circuit (40), and the isolation circuit (40) includes a PMOS transistor, and a first diode and a second diode connected in parallel; The positive electrodes of the first diode and the second diode are both connected to the first load (20); the negative electrode of the first diode, the negative electrode of the second diode, and the source electrode of the PMOS transistor are all connected to the second load (30), and the drain electrode of the PMOS transistor is connected to the rechargeable battery (10); Wherein, when the refrigerator power is cut off, the rechargeable battery (10) discharges, and the PN junction of the PMOS transistor can block the voltage and / or current of the first load (20) and the second load (30) from flowing to the rechargeable battery (10).

2. The battery charging and discharging circuit of the cooler according to claim 1, wherein The battery charging and discharging circuit further includes a driving circuit (50), and the driving circuit (50) is used to control the on and off of the PMOS transistor.

3. The battery charging and discharging circuit of the cooler according to claim 2, characterized in that, The driving circuit (50) includes a first resistor, a second resistor, a third resistor, a fourth resistor, a first triode, and a zener diode; The base of the first triode is respectively connected to the first end of the first resistor and the first end of the third resistor, and the second end of the first resistor is connected to the first control port of the MCU; The collector of the first triode is connected to the first end of the second resistor, and the second end of the second resistor, the positive electrode of the zener diode, and the first end of the fourth resistor are all connected to the gate of the PMOS transistor; the source electrode of the PMOS transistor, the negative electrode of the zener diode, and the second end of the fourth resistor are all connected to the power supply pin of the second load (30); The emitter of the first triode and the second end of the third resistor are grounded.

4. The battery charging and discharging circuit of the refrigerated box according to claim 1, characterized in that, At least one fifth resistor is further provided between the PMOS transistor and the rechargeable battery (10), and the fifth resistor is used to limit the charging current flowing to the rechargeable battery (10).

5. The battery charging and discharging circuit of the refrigerator box according to claim 4, characterized in that The battery charging and discharging circuit further includes a control circuit (60), and the control circuit (60) is used to reduce the power consumption of the fifth resistor when the rechargeable battery (10) is discharging.

6. The battery charging and discharging circuit of the cooler according to claim 5, characterized in that The control circuit (60) includes a first relay, a second triode, a sixth resistor, and a third diode; The emitter of the second triode is grounded, the base of the second triode is connected to the second control port of the MCU in series with the sixth resistor, and the collector of the second triode is respectively connected to the positive electrode of the third diode and the positive electrode of the coil of the first relay, and the negative electrode of the coil of the first relay and the negative electrode of the third diode are both connected to the power supply pin of the second load (30); The common terminal of the first relay is connected between the PMOS transistor and the fifth resistor, and the normally open terminal of the first relay is connected between the rechargeable battery (10) and the fifth resistor.

7. The battery charging and discharging circuit of the cooler according to claim 1, characterized in that, The battery charging and discharging circuit further includes a first detection circuit (70) for detecting the voltage of the rechargeable battery (10), and the first detection circuit (70) includes a seventh resistor, an eighth resistor, and a first capacitor; The second terminal of the seventh resistor is connected to the rechargeable battery (10), and the first terminal of the seventh resistor, the first terminal of the eighth resistor, and the first terminal of the first capacitor are all connected to the first AD port of the MCU; The second terminal of the first capacitor and the second terminal of the eighth resistor are both grounded.

8. The battery charging and discharging circuit of the cooler according to claim 1, characterized in that, The battery charging and discharging circuit further includes a second detection circuit (80) for detecting the voltage of the first load (20), and the second detection circuit (80) includes a ninth resistor, a tenth resistor, and a second capacitor; The first terminal of the ninth resistor is connected to the first load (20), and the second terminal of the ninth resistor, the second terminal of the tenth resistor, and the first terminal of the second capacitor are all connected to the second AD port of the MCU; The second terminal of the second capacitor and the first terminal of the tenth resistor are both grounded.

9. The battery charging and discharging circuit of the refrigerator according to claim 1, characterized in that, The battery charging and discharging circuit further includes an alarm circuit (90), and the alarm circuit (90) includes a second relay, a third capacitor, a fourth diode, and a connection terminal for connecting to a remote alarm system; The positive electrode of the coil of the second relay, the first terminal of the third capacitor, and the positive electrode of the fourth diode are all connected to the output terminal of the MCU, and the negative electrode of the coil of the second relay, the second terminal of the third capacitor, and the negative electrode of the fourth diode are all connected to the power supply pin of the second load (30); The normally closed terminal of the second relay is connected to pin 1 of the connection terminal, the common terminal of the second relay is connected to pin 2 of the connection terminal, and the normally open terminal of the second relay is connected to pin 3 of the connection terminal.

10. Refrigerator, characterized in that, The refrigerator includes the battery charging and discharging circuit according to any one of claims 1-9.

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