Charging and discharging control circuit applied to sodium ion battery and electric vehicle

Abstract

The invention discloses a charging and discharging control circuit applied to a sodium ion battery and an electric vehicle, and the circuit comprises an external positive electrode end and an external negative electrode end; the actual battery pack and the simulation battery are arranged on an electric connection path between the external positive electrode end and the external negative electrode end; and the main control switch can control the access working condition of the simulation battery in the circuit through opening and closing. By adjusting the main control switch, the simulation battery is short-circuited or connected to a circuit, so that the simulation battery is subjected to bypass charging or boost charging in the charging process, and is subjected to bypass discharging or boost discharging in the discharging process. The sodium-ion battery is matched with a charger and a load, so that the battery has a certain intelligent charging and discharging function. The boost cost is reduced, and the DC / DC efficiency is improved. The method can be applied to battery systems of different voltage platforms to achieve the purpose of supplementing the output voltage of the battery.

Description

Technical Field

[0001] The present invention relates to the technical field of sodium ion battery packs, and in particular to a charge and discharge control circuit and an electric vehicle applied to a sodium ion battery. Background Art

[0002] In recent years, the problem of energy shortage has continued to intensify, and the development of sodium-ion batteries has become a current research hotspot. The low cost and safety of sodium ions are more suitable for current electric two-wheeled vehicles and low-speed electric vehicles. The core power source of electric vehicles is power batteries, and single cells are generally connected in series and parallel to meet the output voltage and output capacity requirements. However, due to the large difference between the charging and discharging voltage range of sodium-ion battery packs and the voltage range required for the actual operation of electric vehicles, in actual use, in order to fully charge and discharge the battery, a DC-DC converter that adapts to a wide range of input and output is required. The current technology used is to use traditional BOOST circuits or isolated boost topologies to achieve boost to match the motor drive circuit. This solution is just a simple superposition of the circuit and does not achieve the effect of simplifying the circuit and reducing costs.

[0003] Prior art, such as the U.S. invention patent application with publication number US20180226816A1, discloses a battery protection circuit module, including a first positive terminal and a first negative terminal electrically connected to the electrode terminals of a bare battery cell, a second positive terminal and a second negative terminal, which are electrically connected to a charger or an electronic device, a single field effect transistor, including a drain terminal, a source terminal, a gate terminal and a well terminal, wherein the drain terminal is electrically connected to the first negative terminal, the source terminal is electrically connected to the second negative terminal, and a protection integrated circuit (P-IC) for controlling the charging and discharging of the bare battery cell by controlling the gate terminal to control whether the single field effect transistor is turned on and by controlling the bias voltage of the well terminal using an internal switch. Summary of the invention

[0004] The purpose of the present invention is to provide a charge and discharge control circuit and electric vehicle for sodium ion batteries that reduces the number of power devices, improves efficiency, reduces heat generation, reduces costs, allows energy to flow in both directions, enables the output to have the original charge and discharge characteristics of the battery, and enhances replacement adaptability.

[0005] The technical solution adopted by the present invention to solve the above technical problems is: a charge and discharge control circuit and electric vehicle applied to sodium ion batteries, including: an external positive terminal and an external negative terminal; and, an actual battery pack and a simulated battery arranged on the electrical connection path between the external positive terminal and the external negative terminal; and a main control switch that can be opened and closed to control the simulated battery to access the working condition in the circuit. By adjusting the main control switch, the simulated battery is short-circuited or connected to the circuit, so that the simulated battery is bypassed or boosted during the charging process, and bypassed or boosted during the discharging process. The power of DC-DC is reduced, and the integration of battery protection circuit and boost circuit can simplify the circuit structure, reduce the number of power devices, improve efficiency, reduce costs, and energy can flow in both directions, and have the original charge and discharge characteristics of the battery. The present invention matches the sodium ion battery with the charger and the load, so that the battery has a certain intelligent charge and discharge function. Reduce the boost cost and improve the DC / DC efficiency. It can be applied to battery systems with different voltage platforms to achieve the purpose of supplementing the battery output voltage. In order to optimize the above technical solution, the measures taken also include: there is a load between the external positive terminal and the external negative terminal; the main control switch and the simulated battery are located in different branches electrically connected in parallel. When the main control switch is turned on, the simulated battery is short-circuited, and thus does not participate in the charging or discharging condition in the entire circuit. The simulated battery is a first switch filter circuit and a second switch filter circuit coupled via a transformer device. The transformer device preferably uses a flyback transformer, and this scheme is an implementation method of an isolated simulated battery circuit. The first switch filter circuit contains a first capacitor and a third switch that form an electrical connection loop with one side of the inductor device; the two ends of the first capacitor are electrically connected to the positive and negative poles of the actual battery pack respectively; the first switch filter circuit also contains a third capacitor and a first switch that form an electrical connection loop with the other side of the inductor device; one end of the third capacitor is electrically connected to the external positive terminal, and the other end of the third capacitor is electrically connected to the actual battery pack. That is, the simulated battery of the present technical solution is close to the external positive terminal, and an isolated simulated battery circuit is used. For example, during boost discharge, the first switch filter circuit takes power from the actual battery pack, and then the second switch filter circuit composed of the flyback transformer, the third capacitor and the first switch can output the coupled voltage superimposed with V1 to P+. The first switch filter circuit contains a first capacitor and a third switch that form an electrical connection loop with one side of the inductor device; the two ends of the first capacitor are electrically connected to the positive and negative electrodes of the actual battery pack respectively; the first switch filter circuit also contains a third capacitor and a first switch that form an electrical connection loop with the other side of the inductor device; one end of the third capacitor is electrically connected to the external negative terminal, and the other end of the third capacitor is electrically connected to the actual battery pack. That is, the simulated battery of the present technical solution is close to the external negative terminal, and an isolated simulated battery circuit is used. The two pins of the first capacitor of the first switch filter circuit take power from the actual battery pack, and then pass through the second switch filter circuit composed of the flyback transformer, the third capacitor and the first switch to electrically connect the positive pin of the third capacitor to the negative electrode of the actual battery pack, and the negative pin of the third capacitor to the external negative terminal. The first switch filter circuit contains a first inductor, a third switch and a third capacitor connected as an electrical connection loop; the node between the first inductor and the third switch is connected to the external negative terminal via the first switch; the node between the third switch and the third capacitor is electrically connected to the external positive terminal; the node between the first inductor and the third capacitor is electrically connected to the external positive terminal via the actual battery pack. This scheme is an implementation method of a non-isolated simulated battery circuit, and the simulated battery is close to the external positive terminal. In the simulated battery discharge state, the switch tubes Q1 and Q3 are complementary and alternately turned on. The larger the duty cycle of the switch tube Q1, the higher the simulated battery output voltage, and Q3 is in synchronous rectification mode. In the simulated battery charging state, the switch tubes Q1 and Q3 are complementary and alternately turned on. The larger the duty cycle of the switch tube Q3, the higher the simulated battery input voltage, and Q1 is in synchronous rectification mode.The first switch filter circuit contains a first inductor, a third switch and a third capacitor connected as an electrical connection loop; the node between the first inductor and the third switch is connected to the external positive terminal via the first switch; the node between the third switch and the third capacitor is electrically connected to the external negative terminal; the node between the first inductor and the third capacitor is electrically connected to the external positive terminal via the actual battery pack. This scheme is an implementation method of a non-isolated simulated battery circuit, and the simulated battery is close to the external negative terminal. When the main control switch is disconnected, the discharge voltage between the external positive terminal and the external negative terminal is the sum of the actual battery pack output voltage and the simulated battery output voltage. When the battery voltage V1> the actual required output voltage Vout, Q2 is turned on, U1 does not work, and the battery U2 directly outputs the voltage V1 to the load Rload through the P+ / P- port. As. Figure 1 The DC / DC simulation battery output in U1 is in bypass state and does not participate in external discharge. When the battery voltage V1 < the actual required output voltage Vout, Q2 is turned off, DC / DC starts working, and the output voltage is recorded as V2. As the battery voltage continues to drop during the discharge process, the DC / DC output voltage continues to rise, and the total output voltage is Vout=V1+V2. The target voltage output reaches the load. As the battery discharge voltage drops, V1 and V2 output voltages continue to rise to ensure that the Vout voltage is output according to actual requirements. When the main control switch is closed, the discharge voltage between the external positive terminal and the external negative terminal is the actual output voltage of the battery pack. Bypass charging: When the external charger charges the battery, Q2 is turned on, the DC / DC stops working, and the current forms a loop through "P+–Q2–battery pack–P-" to achieve the purpose of charging the battery. At the same time, the external charger can be a constant voltage power supply to control the charging voltage and current through DC / DC to achieve the purpose of charging the battery according to the specific charge and discharge curve of the battery. Power boost charging: When the external charger charges the battery, such as Figure 4 As shown, Q2 is closed, and the DC / DC simulated battery can also work in reverse. The 3 and 4 ports of the simulated battery input V2, V2 = V3-V1. The battery pack is charged through the 1 and 2 ports output V1, and the current charges the battery pack through V1. The above description of the simulated battery can be referred to as DCDC or DC / DC.

[0006] The present invention also provides an electric vehicle equipped with a charge and discharge control circuit for a sodium ion battery.

[0007] Since the present invention adopts: an external positive terminal and an external negative terminal; and an actual battery pack and a simulated battery arranged on the electrical connection path between the external positive terminal and the external negative terminal; and also has a main control switch that can be opened and closed to control the simulated battery to access the working condition in the circuit. By adjusting the main control switch, the simulated battery is short-circuited or connected to the circuit, so that the simulated battery is bypassed or boosted during the charging process, and bypassed or boosted during the discharging process. The power of DC-DC is reduced, and the integration of battery protection circuit and boost circuit can simplify the circuit structure, reduce the number of power devices, improve efficiency, reduce costs, and energy can flow in both directions, and have the original charging and discharging characteristics of the battery. The present invention matches the sodium ion battery with the charger and the load, so that the battery has a certain intelligent charging and discharging function. Reduce the boosting cost and improve the DC / DC efficiency. It can be applied to battery systems with different voltage platforms to achieve the purpose of supplementing the battery output voltage. Therefore, the present invention has the advantages of reducing the number of power devices, improving efficiency, reducing heat, reducing costs, and energy can flow in both directions, so that the output has the original charging and discharging characteristics of the battery and improving replacement adaptability. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 This is a schematic diagram of the structure of a circuit module simulating a battery at the positive end of Example 1 of the present invention; Figure 2 This is a schematic diagram of bypass discharge state of embodiment 1 of the present invention; Figure 3 This is a schematic diagram of the boost discharge state of Embodiment 1 of the present invention; Figure 4 This is a schematic diagram of bypass charging state of Embodiment 1 of the present invention; Figure 5 This is a schematic diagram of the boost charging state of Embodiment 1 of the present invention; Figure 6 The relationship between the actual battery pack and the simulated battery voltage in Example 1 of the present invention; Figure 7 This is a schematic diagram of the timing state of the output voltage V3 according to Embodiment 1 of the present invention; Figure 8 The actual battery pack voltage V1 and the charging curve of Q2 in the bypass state in Example 1 of the present invention; Fig. 9 The actual battery pack voltage V1 boost charging curve of Example 1 of the present invention; Fig.10 This is a schematic diagram of an isolated simulated battery circuit (positive end) module according to Embodiment 2 of the present invention; Fig.11 This is a schematic diagram of the structure of an isolated simulated battery circuit (positive terminal) according to Embodiment 2 of the present invention; Fig.12 This is a schematic diagram of the structure of a non-isolated simulated battery circuit (positive terminal) according to Embodiment 3 of the present invention; Fig.13 This is a schematic diagram of the structure of a non-isolated simulated battery circuit (positive terminal) according to Embodiment 3 of the present invention; Fig.14 This is a schematic diagram of the switch operating state in the discharge state of embodiment 3 of the present invention; Fig.15 This is a schematic diagram of the structure of a circuit module simulating a battery at the negative end according to Embodiment 4 of the present invention; Fig.16 This is a schematic diagram of the structure of an isolated simulated battery circuit (negative terminal) according to Embodiment 4 of the present invention; Fig.17 This is a schematic diagram of the structure of a non-isolated simulated battery circuit (negative terminal) according to Example 5 of the present invention. DETAILED DESCRIPTION

[0009] The present invention is further described in detail below in conjunction with the attached examples.

[0010] Explanation of the accompanying figures: simulated battery U1, actual battery pack U2, first switch Q1, main control switch Q2, third switch Q3, external positive terminal P+, external negative terminal P-, load Rload, first switch filter circuit M1, second switch filter circuit M2, first capacitor C1, third capacitor C3, transformer device T1.

[0011] Example 1: Reference Figures 1 to 9 , a charge and discharge control circuit and electric vehicle applied to sodium ion batteries, including, wherein: including: an external positive terminal P+ and an external negative terminal P-; and, an actual battery pack U2 and a simulated battery U1 arranged on the electrical connection path between the external positive terminal P+ and the external negative terminal P-; and also having a main control switch Q2 that can control the simulated battery U1 to access the working condition in the circuit by opening and closing. By adjusting the main control switch Q2, the simulated battery U1 is short-circuited or connected to the circuit, so that the simulated battery U1 is bypass charged or boosted charged during the charging process, and bypass discharged or boosted discharged during the discharging process. The power of DC-DC is reduced, and the integration of battery protection circuit and boost circuit can simplify the circuit structure, reduce the number of power devices, improve efficiency, reduce costs, and energy can flow in both directions, and have the original charge and discharge characteristics of the battery. The present invention matches the sodium ion battery with the charger and the load, so that the battery has a certain intelligent charge and discharge function. Reduce the boost cost and improve the DC / DC efficiency. It can be applied to battery systems of different voltage platforms to achieve the purpose of supplementing the battery output voltage.

[0012] There is a load Rload between the external positive terminal P+ and the external negative terminal P-; the main control switch Q2 and the simulated battery U1 are located in different branches of the parallel electrical connection. When the main control switch Q2 is turned on, the simulated battery U1 is short-circuited, and thus does not participate in the charging or discharging condition in the entire circuit.

[0013] Example 2: Reference Figures 10 to 11 In this embodiment, based on the above embodiment, the simulated battery U1 is a first switch filter circuit M1 and a second switch filter circuit M2 coupled via a transformer device T1. The transformer device T1 preferably uses a flyback transformer. This solution is an implementation method of an isolated simulated battery circuit.

[0014] The first switch filter circuit M1 includes a first capacitor C1 and a third switch Q3 that form an electrical connection loop with one side of the inductor device T1; the two ends of the first capacitor C1 are electrically connected to the positive electrode and the negative electrode of the actual battery pack U2 respectively; the first switch filter circuit M1 also includes a third capacitor C3 and a first switch Q1 that form an electrical connection loop with the other side of the inductor device T1; one end of the third capacitor C3 is electrically connected to the external positive terminal P+, and the other end of the third capacitor C3 is electrically connected to the actual battery pack U2. That is, the simulated battery U1 of the present technical solution is close to the external positive terminal P+, and an isolated simulated battery circuit is used. For example, during boost discharge, the first switch filter circuit M1 takes power from the actual battery pack U2, and then the second switch filter circuit M2 composed of the flyback transformer, the third capacitor C3 and the first switch Q1 can output the coupled voltage after superimposing V1 to P+.

[0015] Example 3: Reference Figures 12 to 13 , this embodiment is a non-isolated, positive electrode solution based on the above embodiment, that is, the first switch filter circuit M1 contains a first inductor L1, a third switch Q3 and a third capacitor C3 connected as an electrical connection loop; the node between the first inductor L1 and the third switch Q3 is connected to the external negative terminal P- through the first switch Q1; the node between the third switch Q3 and the third capacitor C3 is electrically connected to the external positive terminal P+; the node between the first inductor L1 and the third capacitor C3 is electrically connected to the external positive terminal P+ through the actual battery pack U2. This solution is an implementation method of a non-isolated simulated battery circuit, and the simulated battery U1 is close to the external positive terminal P+. In the simulated battery discharge state, the switch tubes Q1 and Q3 are complementary and alternately turned on. The larger the duty cycle of the switch tube Q1, the higher the simulated battery output voltage, and Q3 is in the synchronous rectification mode. In the simulated battery charging state, the switch tubes Q1 and Q3 are complementary and alternately turned on. The larger the duty cycle of the switch tube Q3, the higher the simulated battery input voltage, and Q1 is in the synchronous rectification mode. In the simulated battery discharge state, the switch tubes Q1 and Q3 are alternately turned on complementary, and the larger the duty cycle of the switch tube Q1, the higher the simulated battery output voltage, and Q3 is in synchronous rectification mode. In the simulated battery charging state, the switch tubes Q1 and Q3 are alternately turned on complementary, and the larger the duty cycle of the switch tube Q3, the higher the simulated battery input voltage, and Q1 is in synchronous rectification mode.

[0016] Example 4: Reference Figures 15 to 16, this embodiment is changed into an isolation and negative pole scheme based on the above embodiment, that is, the first switch filter circuit M1 contains a first capacitor C1 and a third switch Q3 which form an electrical connection loop with one side of the inductor device T1; the two ends of the first capacitor C1 are electrically connected to the positive pole and the negative pole of the actual battery pack U2 respectively; the first switch filter circuit M1 also contains a third capacitor C3 and a first switch Q1 which form an electrical connection loop with the other side of the inductor device T1; one end of the third capacitor C3 is electrically connected to the external negative pole terminal P-, and the other end of the third capacitor C3 is electrically connected to the actual battery pack U2. That is, the simulated battery U1 of this technical solution is close to the external negative pole terminal P-, and an isolated simulated battery circuit is adopted. The two pins of the first capacitor C1 of the first switch filter circuit M1 take power from the actual battery pack U2, and then pass through the second switch filter circuit M2 composed of the flyback transformer, the third capacitor C3 and the first switch Q1, and the positive pin of the third capacitor C3 is electrically connected to the negative pole of the actual battery pack U2, and the negative pin of the third capacitor C3 is electrically connected to the external negative pole terminal P-.

[0017] Example 5: Reference Fig.17 , this embodiment is a non-isolated, negative pole solution based on the previous embodiment, the first switch filter circuit M1 contains the first inductor L1, the third switch Q3 and the third capacitor C3 connected as an electrical connection loop; the node between the first inductor L1 and the third switch Q3 is connected to the external positive terminal P+ through the first switch Q1; the node between the third switch Q3 and the third capacitor C3 is electrically connected to the external negative terminal P-; the node between the first inductor L1 and the third capacitor C3 is electrically connected to the external positive terminal P+ through the actual battery pack U2. This solution is an implementation method of a non-isolated simulated battery circuit, and the simulated battery U1 is close to the external negative terminal P-.

[0018] In summary, further technical solutions are described. When the main control switch Q2 is disconnected, the discharge voltage between the external positive terminal P+ and the external negative terminal P- is the sum of the actual battery pack U2 output voltage and the simulated battery U1 output voltage. When the battery voltage V1> the actual required output voltage Vout, Q2 is turned on, U1 does not work, and the battery U2 directly outputs the voltage V1 to the load Rload through the P+ / P- port. Figure 1The DC / DC simulation battery output in U1 is in bypass state and does not participate in external discharge. When the battery voltage V1 < the actual required output voltage Vout, Q2 is turned off, DC / DC starts working, and the output voltage is recorded as V2. As the battery voltage continues to drop during the discharge process, the DC / DC output voltage continues to rise, and the total output voltage is Vout=V1+V2. The target voltage output reaches the load. As the battery discharge voltage drops, the V2 output voltage continues to rise to ensure that the Vout voltage is output according to the actual requirements. When the main control switch Q2 is closed, the discharge voltage between the external positive terminal P+ and the external negative terminal P- is the output voltage of the actual battery pack U2. Bypass charging: When the external charger charges the battery, Q2 is turned on, the DC / DC stops working, and the current forms a loop through "P+-Q2-battery pack-P-" to achieve the purpose of charging the battery. At the same time, the external charger can be a constant voltage power supply to control the charging voltage and current through DC / DC to achieve the purpose of charging the battery according to the specific charging and discharging curve of the battery. Power boost charging: When the external charger charges the battery, such as Figure 4 As shown, Q2 is closed, and the DC / DC simulated battery can also work in reverse. The 3 and 4 ports of the simulated battery input V2, V2 = V3-V1. The battery pack is charged through the 1 and 2 ports output V1, and the current charges the battery pack through V1. The simulated battery U1 described above can be referred to as DCDC or DC / DC.

[0019] The present invention also provides an electric vehicle, which is equipped with the charge and discharge control circuit of the present invention applied to a sodium ion battery. Reference Figures 2 to 9 To illustrate the working logic, V1 is the battery pack voltage, V2 is the battery output voltage simulated by the battery pack through DC / DC, Rload is the external load, which can be any load powered by a battery, and Vout is the voltage across the system output to the load Rload.

[0020] Discharge status: When the battery voltage V1> the actual required output voltage Vout, Q2 is turned on, U1 does not work, and the battery U2 directly outputs the voltage V1 to the load Rload through the P+ / P- port. Figure 1 The DC / DC simulated battery output in U1 is in bypass state and does not participate in external discharge.

[0021] When the battery voltage V1 is less than the actual required output voltage Vout, Q2 is turned off, and the DC / DC starts working. The output voltage is recorded as V2. As the battery voltage continues to drop during discharge, the DC / DC output voltage continues to rise. The total output voltage is Vout=V1+V2. The target voltage output reaches the load. As the battery discharge voltage drops, V1 and V2 output voltages continue to rise to ensure that the Vout voltage is output according to the actual requirements.

[0022] Charging status: Bypass charging: When the external charger is charging the battery, Q2 is turned on, DCDC stops working, and the current forms a loop through P+–Q2–battery pack–P- to achieve the purpose of charging the battery. At the same time, the external charger can be a constant voltage power supply to control the charging voltage and current through DCDC to achieve the purpose of charging the battery according to the specific charge and discharge curve of the battery.

[0023] Power charging: When the external charger charges the battery Figure 4 As shown, Q2 is closed, and the DC / DC simulated battery can also work in reverse, and the 3 and 4 ports of the simulated battery input V2, V2 = V3 - V1. The battery pack is charged through the 1 and 2 ports output V1, and the current is charged through V1.

[0024] The actual battery pack simulates a new voltage V2 through the U1 circuit, which is connected in series with the original battery V1 to form a new voltage V3 to supply power to the load to achieve the purpose of boosting the voltage. Q2 is a bypass switch. When the actual battery voltage does not need to be boosted, Q2 is turned on to reduce circuit losses.

[0025] The present application reduces the power of DC-DC, integrates the battery protection circuit and the boost circuit, simplifies the redundant circuit structure, reduces the number of power devices, improves efficiency, reduces costs, and allows energy to flow in both directions with the original charge and discharge characteristics of the battery. The technical solution of the present invention is characterized by the topological structure of the circuit and the control strategy in the corresponding mode. Among them, U1 has a DC / DC battery simulation function in the figure, which can change the output characteristics of the output end of the battery circuit through DCDC control, and can also be applied to multiple groups of battery series discharge circuits. Its DC / DC can be a variety of topologies including forward, flyback, full bridge, half bridge and other isolation topologies as well as BUCK, BOOST, BUCK-BOOST and other topologies. Among them, the DC / DC simulation battery circuit can be connected to the negative end of the battery pack or to the positive end of the battery pack. It can match sodium ion batteries with chargers and loads to increase the intelligent charging and discharging functions of the battery. Reduce the cost of boost DCDC and improve DC / DC efficiency. It can be applied to battery systems with different voltage platforms to achieve the purpose of supplementing the battery output voltage.

[0026] Although the present invention has been described in conjunction with preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can implement various changes, substitutions of equivalents and modifications to the subject matter listed here without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention shall be based on the scope defined by the claims.

Claims

1. A charge and discharge control circuit for a sodium ion battery, characterized in that: include: External positive terminal (P+) and external negative terminal (P-); and, an actual battery pack (U2) and a simulated battery (U1) disposed on an electrical connection path between the external positive terminal (P+) and the external negative terminal (P-); It also has a main control switch (Q2) that can control the simulated battery (U1) to be connected to the working state in the circuit by opening and closing.

2. The charge and discharge control circuit for sodium ion batteries according to claim 1, characterized in that: A load (Rload) is provided between the external positive terminal (P+) and the external negative terminal (P-); the main control switch (Q2) and the simulated battery (U1) are located in different branches of a parallel electrical connection.

3. The charge and discharge control circuit for sodium ion batteries according to claim 1, characterized in that: The simulated battery (U1) is a first switch filter circuit (M1) and a second switch filter circuit (M2) coupled via a transformer device (T1).

4. The charge and discharge control circuit for sodium ion batteries according to claim 3, characterized in that: The first switch filter circuit (M1) includes a first capacitor (C1) and a third switch (Q3) that form an electrical connection loop with one side of the inductor device (T1); the two ends of the first capacitor (C1) are electrically connected to the positive electrode and the negative electrode of the actual battery pack (U2) respectively; the first switch filter circuit (M1) also includes a third capacitor (C3) and a first switch (Q1) that form an electrical connection loop with the other side of the inductor device (T1); one end of the third capacitor (C3) is electrically connected to the external positive terminal (P+), and the other end of the third capacitor (C3) is electrically connected to the actual battery pack (U2).

5. The charge and discharge control circuit for sodium ion batteries according to claim 3, characterized in that: The first switch filter circuit (M1) includes a first capacitor (C1) and a third switch (Q3) that form an electrical connection loop with one side of the inductor device (T1); the two ends of the first capacitor (C1) are electrically connected to the positive electrode and the negative electrode of the actual battery pack (U2) respectively; the first switch filter circuit (M1) also includes a third capacitor (C3) and a first switch (Q1) that form an electrical connection loop with the other side of the inductor device (T1); one end of the third capacitor (C3) is electrically connected to the external negative terminal (P-), and the other end of the third capacitor (C3) is electrically connected to the actual battery pack (U2).

6. The charge and discharge control circuit for sodium ion batteries according to claim 1, characterized in that: The first switch filter circuit (M1) comprises a first inductor (L1), a third switch (Q3) and a third capacitor (C3) connected in an electrical connection loop; the node between the first inductor (L1) and the third switch (Q3) is connected to the external negative terminal (P-) via the first switch (Q1); the node between the third switch (Q3) and the third capacitor (C3) is electrically connected to the external positive terminal (P+); the node between the first inductor (L1) and the third capacitor (C3) is electrically connected to the external positive terminal (P+) via the actual battery pack (U2).

7. The charge and discharge control circuit for sodium ion batteries according to claim 1, characterized in that: The first switch filter circuit (M1) comprises a first inductor (L1), a third switch (Q3) and a third capacitor (C3) connected in an electrical connection loop; the node between the first inductor (L1) and the third switch (Q3) is connected to the external positive terminal (P+) via the first switch (Q1); the node between the third switch (Q3) and the third capacitor (C3) is electrically connected to the external negative terminal (P-); the node between the first inductor (L1) and the third capacitor (C3) is electrically connected to the external positive terminal (P+) via the actual battery pack (U2).

8. The charge and discharge control circuit for sodium ion batteries according to claim 1, characterized in that: When the main control switch (Q2) is disconnected, the discharge voltage between the external positive terminal (P+) and the external negative terminal (P-) is the sum of the output voltage of the actual battery pack (U2) and the output voltage of the simulated battery (U1).

9. The charge and discharge control circuit for sodium ion batteries according to claim 1, characterized in that: When the main control switch (Q2) is closed, the discharge voltage between the external positive terminal (P+) and the external negative terminal (P-) is the output voltage of the actual battery pack (U2).

10. An electric vehicle, characterized in that: A charge and discharge control circuit for a sodium ion battery as claimed in claims 1 to 9 is installed.

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