Direct current bus circuit and energy storage equipment

Abstract

The utility model provides a direct current bus circuit and energy storage equipment, and relates to the technical field of energy storage. Wherein the direct current bus circuit comprises N bus capacitors, the N bus capacitors are connected in series, and N is a positive integer; the N voltage-sharing resistors are connected in series, and each voltage-sharing resistor and one bus capacitor form a voltage division unit; the switch module is electrically connected with the voltage division units, and under the condition that the voltage difference between the bus capacitor and the voltage-sharing resistor in one voltage division unit is larger than the breakover voltage of the switch module electrically connected with the voltage division unit, the switch module is conducted so that the bus capacitor can be charged or discharged through the switch module. According to the invention, the voltage division of the plurality of bus capacitors in the bus circuit is equal, and the service life of the bus capacitors is ensured.

Description

Technical Field

[0001] The present application relates to the technical field of energy storage, and in particular, to a DC bus circuit and an energy storage device. Background Art

[0002] In the related art, for the DC bus of an energy storage system, in order to smooth part of the waveform of the inverter output and filter out the switching ripple current, a bus capacitor is generally selected as the energy storage and filtering device. When the energy storage converter is under high-voltage DC conditions, multiple bus capacitors need to be connected in series to improve the overall bearing capacity and withstand voltage level.

[0003] However, due to the existence of a certain leakage current in the capacitor itself, when capacitors are connected in series, the leakage currents passing through the series capacitors are equal, but the equivalent resistance of the capacitor itself will vary due to factors such as environment, process, and temperature. This results in unbalanced voltage division of the multiple series capacitors, affecting the service life of the bus capacitor. Summary of the Utility Model

[0004] The present application aims to solve at least one of the technical problems existing in the prior art or related technologies.

[0005] To this end, a first aspect of the present application provides a DC bus circuit.

[0006] A second aspect of the present application provides an energy storage device.

[0007] In view of this, a first aspect of the present application provides a DC bus circuit, the DC bus circuit including: N bus capacitors, the N bus capacitors being connected in series, where N is a positive integer; N voltage-sharing resistors, the N voltage-sharing resistors being connected in series, and each voltage-sharing resistor and a bus capacitor forming a voltage division unit; a switch module, the switch module being electrically connected to the voltage division unit, wherein when the voltage difference between the bus capacitor and the voltage-sharing resistor in a voltage division unit is greater than the conduction voltage of the switch module electrically connected to the voltage division unit, the switch module conducts to enable the bus capacitor to charge or discharge through the switch module.

[0008] In this technical solution, the DC bus circuit includes N mutually series-connected bus capacitors. By connecting multiple bus capacitors in series, the voltage that each bus capacitor needs to withstand is reduced. Exemplarily, the above bus capacitor is an electrolytic capacitor.

[0009] Limited by external factors such as production technology, working environment, and temperature, even if bus capacitors of the same specification are selected, their equivalent resistances may be different. At the same time, due to a certain leakage current in the capacitor during operation, the leakage currents flowing through N series-connected bus capacitors are equal. When the equivalent resistances of these bus capacitors are different, the voltage division across each bus capacitor will be different. Under extreme working conditions, a certain bus capacitor may have an excessive voltage division, resulting in premature aging or damage of this capacitor and causing an open circuit in the entire DC bus.

[0010] Therefore, it is necessary to ensure that the voltage divisions of multiple series-connected bus capacitors are almost the same. For this purpose, the technical solution of this application sets N voltage-sharing resistors. The N voltage-sharing resistors correspond to the N bus capacitors one by one and are connected in series to form a voltage-sharing circuit. Among them, one bus capacitor and one voltage-sharing resistor form a group, which is a voltage division unit. Since the N voltage-sharing resistors are connected in series, the voltage across each voltage-sharing resistor is the same. Therefore, in an ideal state, the voltage of the voltage-sharing resistor in a group of voltage division units is also equal to the voltage of the bus capacitor.

[0011] When the equivalent resistances of the N bus capacitors are different, for example, if the equivalent resistance value of a certain bus capacitor is greater than that of other bus capacitors, the voltage division across this bus capacitor will increase, and the voltage divisions across other bus capacitors will decrease, resulting in a voltage difference between the bus capacitor and the voltage-sharing resistor in a group of voltage division units.

[0012] This application sets a switch module electrically connected to the voltage division unit. When there is a voltage difference between the bus capacitor and the voltage-sharing resistor, the switch module conducts, enabling the line capacitor with the voltage difference to charge or discharge. For example, when the voltage of a bus capacitor is high, this bus capacitor will discharge outward, and the stored energy is consumed and reduced, causing the voltage division across this bus capacitor to decrease. When the voltage division across the bus capacitor decreases to be close to or equal to the voltage division of the voltage-sharing resistor, the switch module cuts off. At this time, the voltage values of the multiple bus capacitors in the bus circuit approach equality.

[0013] The technical solution of this application sets voltage-sharing resistors equal in number to the series-connected bus capacitors, which form voltage division units with the bus capacitors. When there is a voltage difference between the bus capacitor and the voltage-sharing resistor, it indicates that the voltage division of one or more bus capacitors has increased or decreased. At this time, by turning on the switch module, the bus capacitor with abnormal voltage division is charged or discharged, so that the voltage division of this bus capacitor approaches the voltage division of the voltage-sharing resistor, ensuring that the voltage divisions of the multiple bus capacitors in the bus circuit are equal and ensuring the service life of the bus capacitors.

[0014] In addition, the DC bus circuit in the above technical solution provided by this application may also have the following additional technical features:

[0015] In some technical solutions of the present application, optionally, the switching module includes a triode, the base of the triode is electrically connected to the voltage-sharing resistor, and the emitter and collector of the triode are respectively electrically connected to both ends of a bus capacitor.

[0016] In this technical solution, the switching module includes a triode. Exemplarily, the triode can be a PNP-type triode or an NPN-type triode. In a voltage-dividing unit, it includes a voltage-sharing resistor and a bus capacitor. The base of the triode is electrically connected to the voltage-sharing resistor, and the emitter and collector of the triode are respectively connected to both ends of the positive electrode of the bus capacitor.

[0017] When there is a voltage difference between the bus capacitor and the voltage-sharing resistor, there will also be the same voltage difference between the emitter and the base of the triode. When the voltage difference between the bus capacitor and the voltage-sharing resistor is greater than the conduction voltage of the triode, the collector and emitter of the triode conduct. At this time, the bus capacitor can discharge outward through the triode or charge through the triode, thereby realizing the dynamic adjustment of the voltage division of the bus capacitor, making the voltage division of multiple bus capacitors similar or equal.

[0018] In some technical solutions of the present application, optionally, the switching module further includes: a current-limiting resistor, the first end of the current-limiting resistor is electrically connected to the collector of the triode, and the second end of the current-limiting resistor is electrically connected to the bus capacitor.

[0019] In this technical solution, the switching module includes a current-limiting resistor, and the current-limiting resistor is connected in series with the collector of the triode. After the triode conducts, the bus capacitor performs charge and discharge operations through the current-limiting resistor. Exemplarily, assuming that the voltage division of a bus capacitor increases, after the triode conducts, the bus capacitor discharges outward, and at this time, the current released by the bus capacitor will be consumed by the voltage-limiting resistor. The present application can perform current-limiting operation on the current during the charge and discharge process of the bus capacitor by setting the current-limiting resistor, avoiding damage to the device due to excessive current.

[0020] Exemplarily, the switching module includes multiple triodes, and a voltage-dividing resistor is connected in series to the collector of each triode.

[0021] In some technical solutions of the present application, optionally, the N bus capacitors include a first bus capacitor, a second bus capacitor, a third bus capacitor, and a fourth bus capacitor connected in series in sequence. The first bus capacitor is electrically connected to the positive electrode of the DC power supply, and the fourth bus capacitor is electrically connected to the negative electrode of the DC power supply.

[0022] The N voltage-sharing resistors include a first voltage-sharing resistor, a second voltage-sharing resistor, a third voltage-sharing resistor, and a fourth voltage-sharing resistor connected in series in sequence. Among them, the first voltage-sharing resistor corresponds to the first bus capacitor, the second voltage-sharing resistor corresponds to the second bus capacitor, the third voltage-sharing resistor corresponds to the third bus capacitor, and the fourth voltage-sharing resistor corresponds to the fourth bus capacitor.

[0023] In this technical solution, 4 bus capacitors are connected in series in the bus circuit, namely the first bus capacitor, the second bus capacitor, the third bus capacitor and the fourth bus capacitor. Among them, the first bus capacitor, the second bus capacitor, the third bus capacitor and the fourth bus capacitor have the same specifications. The first bus capacitor, the second bus capacitor, the third bus capacitor and the fourth bus capacitor are connected in sequence, and the positive electrode of the first bus capacitor is electrically connected to the positive electrode of the DC power supply, and the negative electrode of the fourth bus capacitor is electrically connected to the negative electrode of the DC power supply.

[0024] Exemplarily, the positive electrode of the first bus capacitor is electrically connected to the positive electrode of the DC power supply, the negative electrode of the first bus capacitor is electrically connected to the positive electrode of the second bus capacitor, the negative electrode of the second bus capacitor is electrically connected to the positive electrode of the third bus capacitor, the negative electrode of the third bus capacitor is electrically connected to the positive electrode of the fourth bus capacitor, and the negative electrode of the fourth bus capacitor is electrically connected to the negative electrode of the DC power supply.

[0025] Exemplarily, the first bus capacitor is a BUS+ bus capacitor, the second bus capacitor is a 1 / 2BUS+ bus capacitor, the third bus capacitor is a 1 / 2BUS- bus capacitor, and the fourth bus capacitor is a BUS- bus capacitor.

[0026] Corresponding to the 4 bus capacitors, the number of voltage-sharing resistors is also 4, namely the first voltage-sharing resistor, the second voltage-sharing resistor, the third voltage-sharing resistor and the fourth voltage-sharing resistor. Among them, the first voltage-sharing resistor corresponds to the first bus capacitor, that is, the first voltage-sharing resistor and the first bus capacitor form a voltage-dividing unit, denoted as the first voltage-dividing unit. Similarly, the second voltage-sharing resistor corresponds to the second bus capacitor, that is, the second voltage-sharing resistor and the second bus capacitor form a voltage-dividing unit, denoted as the second voltage-dividing unit; the third voltage-sharing resistor corresponds to the third bus capacitor, that is, the third voltage-sharing resistor and the third bus capacitor form a voltage-dividing unit, denoted as the third voltage-dividing unit; the fourth voltage-sharing resistor corresponds to the fourth bus capacitor, that is, the fourth voltage-sharing resistor and the fourth bus capacitor form a voltage-dividing unit, denoted as the fourth voltage-dividing unit.

[0027] Exemplarily, assuming that the bus voltage of the DC bus is 1000V, then in the ideal state, the voltage divided by each bus capacitor is 250V, and the voltage divided by each voltage-sharing resistor is also 250V. At this time, there is no voltage difference between the voltage-sharing resistor and the bus capacitor. However, when the equivalent resistance of a certain bus capacitor increases, assuming that the equivalent resistance of the second bus capacitor increases, the voltage divided by the second bus capacitor will increase, and at the same time, the voltages divided by the first bus capacitor, the third bus capacitor and the fourth bus capacitor will decrease accordingly. When the voltage difference between the second bus capacitor and the second voltage-sharing resistor exceeds the conduction voltage of the corresponding triode, the triode conducts, and the second bus capacitor discharges through the triode, so that the voltage divided by the second bus capacitor decreases, so that the voltage division on the entire bus circuit can achieve dynamic adjustment balance.

[0028] In some technical solutions of the present application, optionally, the switching module includes a first triode, the first triode is an NPN type triode, the collector of the first triode is electrically connected to the positive electrode of the first bus capacitor, the emitter of the first triode is electrically connected to the negative electrode of the first bus capacitor, and the base of the first triode is electrically connected to the negative electrode of the first equalizing resistor.

[0029] In this technical solution, the switching module includes a first triode, and the first triode is used to adjust the charging and discharging of the first bus capacitor. The first bus capacitor is electrically connected to the positive electrode of the DC power supply. Among them, the first triode is specifically an NPN type triode. The collector of the first triode is electrically connected to the positive electrode of the first bus capacitor, the emitter of the first triode is electrically connected to the negative electrode of the first bus capacitor, and the base of the first triode is electrically connected to the negative electrode of the first equalizing resistor.

[0030] Under normal circumstances, the voltage division of the first bus capacitor is the same as that of the first equalizing resistor. At this time, the voltage between the collector and the emitter of the first triode is less than the conduction voltage of the first triode, and the first triode is in the cut-off state. When the equivalent resistance of the first bus capacitor increases, the voltage division of the first bus capacitor increases, which is reflected as an increase in the voltage of the collector of the first triode, while the voltage division on the first equalizing resistor remains unchanged. When the voltage division of the first bus capacitor increases to a certain extent, the voltage difference between the collector and the base of the first triode exceeds the conduction voltage of the first triode, then the first triode conducts, and at this time, the first bus capacitor discharges externally through the first triode.

[0031] Exemplarily, a first current limiting resistor is connected in series with the collector of the first triode. The energy released by the first bus capacitor will be consumed by the first current limiting resistor, thereby reducing the energy of the first bus capacitor and reducing the voltage division of the first bus capacitor. When the voltage division of the first bus capacitor decreases to a certain extent, the voltage between the collector and the base of the first triode is less than the conduction voltage of the first triode, then the first triode returns to the cut-off state.

[0032] The present application realizes the dynamic adjustment of the voltage division of the series bus capacitors on the DC bus circuit by setting the equalizing resistor and the switching module, ensuring that the voltage divisions of multiple bus capacitors approach the same and ensuring the service life of the DC bus circuit.

[0033] In some technical solutions of the present application, optionally, the switching module further includes a second triode and a third triode. The second triode is an NPN-type triode, and the third triode is a PNP-type triode; the collector of the second triode is electrically connected to the positive electrode of the second bus capacitor, the emitter of the second triode is electrically connected to the negative electrode of the second bus capacitor, and the base of the second triode is electrically connected to the negative electrode of the second voltage-sharing resistor; the emitter of the third triode is electrically connected to the emitter of the second triode, the collector of the third triode is electrically connected to the negative electrode of the third bus capacitor, and the base of the third triode is electrically connected to the positive electrode of the third voltage-sharing resistor.

[0034] In this technical solution, the switching module further includes a second triode and a third triode, and the second triode and the third triode form a pair of transistors. Among them, the second triode is specifically an NPN-type triode, and the third triode is specifically a PNP-type triode.

[0035] The bases of the second triode and the third triode are both connected to the common point of the second voltage-sharing resistor and the third voltage-sharing resistor. The collector of the second triode is connected to the positive electrode of the second bus capacitor. The emitters of the second triode and the third triode are both connected to the common point of the second bus capacitor and the third bus capacitor. The collector of the third triode is connected to the negative electrode of the third bus capacitor.

[0036] Under normal circumstances, the voltage divided by the second bus capacitor is the same as the voltage divided by the second voltage-sharing resistor, and the voltage divided by the third bus capacitor is the same as the voltage divided by the third voltage-sharing resistor. At this time, the voltages between the collectors and emitters of the second triode and the third triode are both less than their conduction voltages, and the first triode is in the cut-off state.

[0037] Exemplarily, assume that the equivalent resistance of the second bus capacitor increases, the voltage divided by the second bus capacitor increases, and the voltage divided by the third bus capacitor decreases. When the voltage of the third bus capacitor is less than the voltage of the common point of the second voltage-sharing resistor and the third voltage-sharing resistor (i.e., the midpoint voltage of the voltage-sharing circuit), the pair of transistors composed of the second triode and the third triode will work. At this time, the second triode conducts, and the second capacitor discharges through the second triode, so that the energy of the second capacitor is consumed through the second current-limiting resistor connected to the collector of the second triode, thereby reducing the voltage divided by the second capacitor. When the energy of the second bus capacitor decreases and the voltage divided by the second bus capacitor decreases to a certain extent, the second diode resumes cut-off, enabling the voltage division voltages of multiple bus capacitors in the DC bus circuit to achieve dynamic balance.

[0038] The present application balances the voltage division voltage of the bus capacitors on the DC bus circuit by setting a pair of transistors composed of a PNP triode and an NPN triode, improving the reliability of the bus circuit.

[0039] In some technical solutions of the present application, optionally, the switching module further includes a fourth triode. The fourth triode is a PNP type triode. The emitter of the fourth triode is electrically connected to the positive electrode of the fourth bus capacitor. The collector of the fourth triode is electrically connected to the negative electrode of the fourth bus capacitor. The base of the fourth triode is electrically connected to the positive electrode of the fourth equalizing resistor.

[0040] In this technical solution, the switching module further includes a fourth triode. The fourth triode is a PNP type triode. The emitter of the fourth triode is electrically connected to the positive electrode of the fourth bus capacitor. The collector of the fourth triode is electrically connected to the negative electrode of the fourth bus capacitor. The base of the fourth triode is electrically connected to the positive electrode of the fourth equalizing resistor.

[0041] In this technical solution, in this technical solution, the switching module includes a fourth triode, which is used to adjust the charge and discharge of the fourth bus capacitor. The fourth bus capacitor is electrically connected to the negative electrode of the DC power supply. Among them, the fourth triode is specifically a PNP type triode. The collector of the fourth triode is electrically connected to the positive electrode of the fourth bus capacitor. The emitter of the fourth triode is electrically connected to the negative electrode of the fourth bus capacitor. And the base of the fourth triode is electrically connected to the negative electrode of the fourth equalizing resistor.

[0042] Under normal circumstances, the voltage division voltage of the fourth bus capacitor is the same as the voltage division voltage of the fourth equalizing resistor. At this time, the voltage between the collector and emitter of the fourth triode is less than the conduction voltage of the fourth triode, and the fourth triode is in the cut-off state. When the equivalent resistance of the fourth bus capacitor increases, the voltage division voltage of the fourth bus capacitor increases, which is reflected as an increase in the voltage of the collector of the fourth triode, while the voltage division voltage on the fourth equalizing resistor remains unchanged. When the voltage division of the fourth bus capacitor increases to a certain extent, the voltage difference between the collector and base of the fourth triode exceeds the conduction voltage of the fourth triode, then the fourth triode conducts, and at this time, the fourth bus capacitor discharges externally through the fourth triode.

[0043] Exemplarily, a fourth current limiting resistor is connected in series with the collector of the fourth triode. The energy released by the fourth bus capacitor will be consumed by the fourth current limiting resistor, so that the energy of the fourth bus capacitor decreases, and the voltage division of the fourth bus capacitor decreases. When the voltage division of the fourth bus capacitor decreases to a certain extent, the voltage between the collector and base of the fourth triode is less than the conduction voltage of the fourth triode, then the fourth triode resumes cut-off.

[0044] The present application realizes the dynamic adjustment of the voltage division voltage of the series bus capacitors on the DC bus circuit by setting equalizing resistors and switching modules, ensuring that the voltage divisions of multiple bus capacitors approach the same and ensuring the service life of the DC bus circuit.

[0045] In some technical solutions of the present application, the switching module includes a fifth triode, a sixth triode, a seventh triode, an eighth triode, a ninth triode, and a thirteenth triode.

[0046] The fifth triode is an NPN-type triode. The collector of the fifth triode is electrically connected to the positive electrode of the first bus capacitor. The emitter of the fifth triode is electrically connected to the negative electrode of the first bus capacitor. The base of the fifth triode is electrically connected to the common point of the first voltage-sharing resistor and the second voltage-sharing resistor.

[0047] The sixth triode is a PNP-type triode. The emitter of the sixth triode is electrically connected to the emitter of the fifth triode. The collector of the sixth triode is electrically connected to the collector of the seventh triode. The base of the sixth triode is electrically connected to the common point of the first voltage-sharing resistor and the second voltage-sharing resistor.

[0048] The seventh triode is an NPN-type triode. The emitter of the seventh triode is electrically connected to the negative electrode of the second bus capacitor. The base of the seventh triode is electrically connected to the common point of the second voltage-sharing resistor and the third voltage-sharing resistor.

[0049] The eighth triode is a PNP-type triode. The emitter of the eighth triode is electrically connected to the emitter of the seventh triode. The collector of the eighth triode is electrically connected to the collector of the ninth triode. The base of the eighth triode is electrically connected to the common point of the second voltage-sharing resistor and the third voltage-sharing resistor.

[0050] The ninth triode is an NPN-type triode. The emitter of the ninth triode is electrically connected to the negative electrode of the third bus capacitor. The base of the ninth triode is electrically connected to the common point of the third voltage-sharing resistor and the fourth voltage-sharing resistor.

[0051] The thirteenth triode is a PNP-type triode. The emitter of the thirteenth triode is electrically connected to the emitter of the ninth triode. The collector of the thirteenth triode is electrically connected to the negative electrode of the fourth bus capacitor. The base of the thirteenth triode is electrically connected to the common point of the third voltage-sharing resistor and the fourth voltage-sharing resistor.

[0052] In this technical solution, the fifth triode and the sixth triode form a pair of transistors, the seventh triode and the eighth triode form a pair of transistors, and the ninth triode and the thirteenth triode form a pair of transistors. Among them, the fifth triode, the seventh triode, and the ninth triode are NPN-type triodes, and the sixth triode, the eighth triode, and the thirteenth triode are PNP-type triodes.

[0053] The first bus capacitor, the second bus capacitor, the third bus capacitor, and the fourth bus capacitor are connected in sequence, and the positive electrode of the first bus capacitor is electrically connected to the positive electrode of the DC power supply, and the negative electrode of the fourth bus capacitor is electrically connected to the negative electrode of the DC power supply.

[0054] The collector of the fifth triode is connected in series with a first current-limiting resistor and is connected to the positive electrode of the first bus capacitor through the first current-limiting resistor. The emitter of the fifth triode is connected to the negative electrode of the first bus capacitor. The base of the fifth triode is connected to the common point of the first voltage-sharing resistor and the second voltage-sharing resistor.

[0055] The emitter of the sixth triode is electrically connected to the emitter of the fifth triode and is connected to the negative electrode of the first bus capacitor. The collector of the sixth triode is connected in series with a second current-limiting resistor and is connected to the collector of the seventh triode through the second current-limiting resistor. The base of the sixth triode is connected to the common point of the first voltage-sharing resistor and the second voltage-sharing resistor.

[0056] The collector of the seventh triode is connected to the collector of the sixth triode through the second current-limiting resistor. The emitter of the seventh triode is connected to the common point of the second bus capacitor and the third bus capacitor and is connected to the emitter of the eighth triode. The base of the seventh triode is connected to the common point of the second voltage-sharing resistor and the third voltage-sharing resistor.

[0057] The emitter of the eighth triode is connected to the emitter of the seventh triode and is connected to the common point of the second bus capacitor and the third bus capacitor. The collector of the eighth triode is connected in series with a third current-limiting resistor and is connected to the collector of the ninth triode through the third current-limiting resistor. The base of the eighth triode is connected to the common point of the second voltage-sharing resistor and the third voltage-sharing resistor.

[0058] The collector of the ninth triode is connected to the collector of the eighth triode through the third current-limiting resistor. The emitter of the ninth triode is connected to the common point of the third bus capacitor and the fourth bus capacitor and is connected to the emitter of the thirteenth triode. The base of the ninth triode is connected to the common point of the third voltage-sharing resistor and the fourth voltage-sharing resistor.

[0059] The emitter of the thirteenth triode is connected to the emitter of the ninth triode and is connected to the common point of the third bus capacitor and the fourth bus capacitor. The collector of the thirteenth triode is connected in series with a fourth current-limiting resistor and is connected to the negative electrode of the fourth bus capacitor through the fourth current-limiting resistor. The base of the thirteenth triode is connected to the negative electrode of the fourth voltage-sharing resistor.

[0060] The technical solution of the present application can improve the reliability of the DC bus circuit by setting pairs of PNP and NPN triodes.

[0061] In some technical solutions of the present application, optionally, the resistance values of the N voltage-sharing resistors are equal.

[0062] In this technical solution, for the N bus capacitors connected in series in the DC bus circuit, N series-connected voltage-sharing resistors are correspondingly provided. The N series-connected voltage-sharing resistors form a voltage-sharing circuit, and this voltage-sharing circuit is connected in parallel with the bus after the N bus capacitors are connected in series. Therefore, the voltage across the bus is equal to the voltage across the voltage-sharing circuit.

[0063] Since the resistance values of the N voltage-sharing resistors are equal, the voltage divided by each voltage-sharing resistor is also equal. In an ideal situation, the voltage divided by each bus capacitor should also be equal, so there is no voltage difference between the voltage-sharing resistor and the bus capacitor.

[0064] When the equivalent resistance of one or more bus capacitors changes, the voltage divided by this bus capacitor also changes, and then a voltage difference is generated between the bus capacitor and the corresponding voltage-sharing resistor. When the voltage difference exceeds the conduction voltage of the switching module, the switching module conducts. At this time, the bus capacitor with the generated voltage difference charges or discharges through the switching module, causing the energy of this bus capacitor to change. Eventually, the voltage divided by the bus capacitor changes, making the voltages divided by the multiple series-connected bus capacitors in the DC bus circuit approach balance.

[0065] Exemplarily, assume that the bus voltage is 1000V, the number of bus capacitors and voltage-sharing resistors is both 4, and the resistance value of each voltage-sharing resistor is 200 kΩ. Then the voltage divided by each voltage-sharing resistor is 250V.

[0066] In this application, by setting voltage-sharing resistors with the same number as the bus capacitors and using the voltage of the voltage-sharing resistors as the reference voltage to adjust the voltage divided by the bus voltage, the dynamic adjustment of the voltage divided by the series-connected bus capacitors in the DC bus circuit is achieved, ensuring that the voltages divided by multiple bus capacitors approach the same and ensuring the service life of the DC bus circuit.

[0067] In the second aspect of this application, an energy storage device is provided. The energy storage device includes the DC bus circuit provided in any of the above technical solutions. Therefore, this energy storage device also includes all the beneficial effects of the DC bus circuit provided in any of the above technical solutions. To avoid repetition, they will not be elaborated here. BRIEF DESCRIPTION OF THE DRAWINGS

[0068] The above and / or additional aspects and advantages of this application will become obvious and easy to understand from the description of the embodiments in conjunction with the following drawings, where:

[0069] Figure 1 The circuit diagram of the DC bus circuit showing some embodiments of this application is shown;

[0070] Figure 2 The circuit diagram of the DC bus circuit showing some embodiments of this application is shown.

[0071] Reference Signs:

[0072] 100 DC bus circuit, 102 bus capacitors, 104 voltage-sharing resistors, 106 voltage-dividing unit, 108 switching module, 110 current-limiting resistor, 200 DC power supply.

[0073] C1 first bus capacitor, C2 second bus capacitor, C3 third bus capacitor, C4 fourth bus capacitor, R1 first voltage-sharing resistor, R2 second voltage-sharing resistor, R3 third voltage-sharing resistor, R3 fourth voltage-sharing resistor, R5 first current-limiting resistor, R6 second current-limiting resistor, R7 third current-limiting resistor, R8 fourth current-limiting resistor, Q1 first triode, Q2 second triode, Q3 third triode, Q4 fourth triode, Q5 fifth triode, Q6 sixth triode, Q7 seventh triode, Q8 eighth triode, Q9 ninth triode, Q10 thirteenth triode. Detailed implementation manners

[0074] In order to more clearly understand the above objects, features and advantages of the present application, the present application will be further described in detail below with reference to the accompanying drawings and specific implementation manners. It should be noted that, without conflict, the embodiments of the present application and the features in the embodiments can be combined with each other.

[0075] Many specific details are set forth in the following description in order to fully understand the present application. However, the present application may be implemented in other ways different from those described herein. Therefore, the protection scope of the present application is not limited by the specific embodiments disclosed below.

[0076] The following refers to Figure 1 and Figure 2 Describe a DC bus circuit and an energy storage device according to some embodiments of the present application.

[0077] In some embodiments of the present application, a DC bus circuit is provided. Figure 1 The circuit diagram of the DC bus circuit according to some embodiments of the present application is shown. As Figure 1 shown, the DC bus circuit 100 includes:

[0078] N bus capacitors 102, the N bus capacitors 102 are connected in series, N is a positive integer; N voltage-sharing resistors 104, the N voltage-sharing resistors 104 are connected in series, and each voltage-sharing resistor 104 and a bus capacitor 102 form a voltage-dividing unit 106; a switching module 108, the switching module 108 is electrically connected to the voltage-dividing unit 106. Wherein, when the voltage difference between the bus capacitor 102 and the voltage-sharing resistor 104 in a voltage-dividing unit 106 is greater than the conduction voltage of the switching module 108 electrically connected to the voltage-dividing unit 106, the switching module 108 conducts to enable the bus capacitor 102 to charge or discharge through the switching module 108.

[0079] In this embodiment, the DC bus circuit 100 includes N bus capacitors 102 connected in series with each other. By connecting multiple bus capacitors 102 in series, the voltage that each bus capacitor 102 needs to withstand is reduced. Exemplarily, the bus capacitor 102 is an electrolytic capacitor.

[0080] Limited by external factors such as production process, working environment, and temperature, even if bus capacitors 102 of the same specification are selected, their own equivalent resistances may be different. At the same time, since there is a certain leakage current in the capacitor during operation, the leakage currents flowing through the N series-connected bus capacitors 102 are equal. When the equivalent resistances of these bus capacitors 102 are different, the voltage division across each bus capacitor 102 will be different. In extreme working conditions, a certain bus capacitor 102 may have an excessive voltage division, resulting in premature aging or damage of this capacitor and causing an open circuit in the entire DC bus.

[0081] Therefore, it is necessary to ensure that the voltage divisions of the multiple series-connected bus capacitors 102 are almost the same. For this purpose, the embodiment of the present application provides N voltage-sharing resistors 104. The N voltage-sharing resistors 104 correspond to the N bus capacitors 102 one by one and are connected in series to form a voltage-sharing circuit. Among them, one bus capacitor 102 and one voltage-sharing resistor 104 form a group, which forms a voltage division unit 106. Since the N voltage-sharing resistors 104 are connected in series, the voltage across each voltage-sharing resistor 104 is the same. Therefore, in an ideal state, the voltage of the voltage-sharing resistor 104 in a group of voltage division units 106 is also equal to the voltage of the bus capacitor 102.

[0082] When the equivalent resistances of the N bus capacitors 102 are different, for example, if the equivalent resistance value of a certain bus capacitor 102 is greater than that of other bus capacitors 102, the voltage division across this bus capacitor 102 will increase, and the voltage divisions across other bus capacitors 102 will decrease, resulting in a voltage difference between the bus capacitor 102 and the voltage-sharing resistor 104 in a group of voltage division units 106.

[0083] The present application provides a switch module 108 electrically connected to the voltage division unit 106. When there is a voltage difference between the bus capacitor 102 and the voltage-sharing resistor 104, the switch module 108 conducts, causing the line capacitor with the voltage difference to charge or discharge. For example, when the voltage of a bus capacitor 102 is high, this bus capacitor 102 will discharge outward, and the stored energy is consumed and reduced, causing the voltage division across this bus capacitor 102 to decrease. When the voltage division across the bus capacitor 102 decreases to be close to or equal to the voltage division of the voltage-sharing resistor 104, the switch module 108 turns off. At this time, the voltage values of the multiple bus capacitors 102 in the bus circuit approach equality.

[0084] In the embodiments of the present application, by setting equalizing resistors 104 with the same number as the series bus capacitors 102, a voltage-dividing unit 106 is formed with the bus capacitors 102. When there is a voltage difference between the bus capacitors 102 and the equalizing resistors 104, it indicates that the voltage division of one or more bus capacitors 102 becomes larger or smaller. At this time, by turning on the switch module 108, the bus capacitors 102 with abnormal voltage division are charged and discharged, so that the voltage division of the bus capacitors 102 approaches the voltage division of the equalizing resistors 104, ensuring that the voltage divisions of multiple bus capacitors 102 in the bus circuit are equal and ensuring the service life of the bus capacitors 102.

[0085] In some embodiments of the present application, optionally, the switch module 108 includes a triode. The base of the triode is electrically connected to the equalizing resistor 104, and the emitter and collector of the triode are respectively electrically connected to both ends of a bus capacitor 102.

[0086] In this embodiment, the switch module 108 includes a triode. Exemplarily, the triode can be a PNP-type triode or an NPN-type triode. In a voltage-dividing unit 106, it includes an equalizing resistor 104 and a bus capacitor 102. The base of the triode is electrically connected to the equalizing resistor 104, and the emitter and collector of the triode are respectively connected to both ends of the positive electrode of the bus capacitor 102.

[0087] When there is a voltage difference between the bus capacitor 102 and the equalizing resistor 104, there will also be the same voltage difference between the emitter and the base of the triode. When the voltage difference between the bus capacitor 102 and the equalizing resistor 104 is greater than the conduction voltage of the triode, the collector and emitter of the triode conduct. At this time, the bus capacitor 102 can discharge outward through the triode or be charged through the triode, thereby realizing the dynamic adjustment of the voltage division of the bus capacitor 102 and making the voltage divisions of multiple bus capacitors 102 similar or equal.

[0088] In some embodiments of the present application, optionally, the switch module 108 further includes: a current-limiting resistor 110. The first end of the current-limiting resistor 110 is electrically connected to the collector of the triode, and the second end of the current-limiting resistor 110 is electrically connected to the bus capacitor 102.

[0089] In this embodiment, the switch module 108 includes a current-limiting resistor 110. The current-limiting resistor 110 is connected in series with the collector of the triode. After the triode conducts, the bus capacitor 102 is charged and discharged through the current-limiting resistor 110. Exemplarily, assuming that the voltage division of a bus capacitor 102 increases, after the triode conducts, the bus capacitor 102 discharges outward, and at this time, the current released by the bus capacitor 102 will be consumed by the voltage-limiting resistor. By setting the current-limiting resistor 110 in the present application, the current during the charging and discharging process of the bus capacitor 102 can be limited, avoiding damage to the device due to excessive current.

[0090] Exemplarily, the switching module 108 includes a plurality of triodes, and a voltage dividing resistor is connected in series to the collector of each triode.

[0091] In some embodiments of the present application, optionally, the N bus capacitors 102 include a first bus capacitor C1, a second bus capacitor C2, a third bus capacitor C3, and a fourth bus capacitor C4 connected in series in sequence. The first bus capacitor C1 is electrically connected to the positive electrode of the DC power supply 200, and the fourth bus capacitor C4 is electrically connected to the negative electrode of the DC power supply 200.

[0092] The N voltage equalizing resistors 104 include a first voltage equalizing resistor R1, a second voltage equalizing resistor R2, a third voltage equalizing resistor R3, and a fourth voltage equalizing resistor R4 connected in series in sequence. Among them, the first voltage equalizing resistor R1 corresponds to the first bus capacitor C1, the second voltage equalizing resistor R2 corresponds to the second bus capacitor C2, the third voltage equalizing resistor R3 corresponds to the third bus capacitor C3, and the fourth voltage equalizing resistor R4 corresponds to the fourth bus capacitor C4.

[0093] In this embodiment, 4 bus capacitors 102 are connected in series in the bus circuit, namely the first bus capacitor C1, the second bus capacitor C2, the third bus capacitor C3, and the fourth bus capacitor C4. Among them, the first bus capacitor C1, the second bus capacitor C2, the third bus capacitor C3, and the fourth bus capacitor C4 have the same specifications. The first bus capacitor C1, the second bus capacitor C2, the third bus capacitor C3, and the fourth bus capacitor C4 are connected in sequence, and the positive electrode of the first bus capacitor C1 is electrically connected to the positive electrode of the DC power supply 200, and the negative electrode of the fourth bus capacitor C4 is electrically connected to the negative electrode of the DC power supply 200.

[0094] Exemplarily, the positive electrode of the first bus capacitor C1 is electrically connected to the positive electrode of the DC power supply 200, the negative electrode of the first bus capacitor C1 is electrically connected to the positive electrode of the second bus capacitor C2, the negative electrode of the second bus capacitor C2 is electrically connected to the positive electrode of the third bus capacitor C3, the negative electrode of the third bus capacitor C3 is electrically connected to the positive electrode of the fourth bus capacitor C4, and the negative electrode of the fourth bus capacitor C4 is electrically connected to the negative electrode of the DC power supply 200.

[0095] Exemplarily, the first bus capacitor C1 is a BUS+ bus capacitor, the second bus capacitor C2 is a 1 / 2BUS+ bus capacitor, the third bus capacitor C3 is a 1 / 2BUS- bus capacitor, and the fourth bus capacitor C4 is a BUS- bus capacitor.

[0096] Corresponding to the four bus capacitors 102, the number of voltage-sharing resistors 104 is also four, namely the first voltage-sharing resistor R1, the second voltage-sharing resistor R2, the third voltage-sharing resistor R3, and the fourth voltage-sharing resistor R4. Among them, the first voltage-sharing resistor R1 corresponds to the first bus capacitor C1, that is, the first voltage-sharing resistor R1 and the first bus capacitor C1 form a voltage-dividing unit 106, denoted as the first voltage-dividing unit 106. Similarly, the second voltage-sharing resistor R2 corresponds to the second bus capacitor C2, that is, the second voltage-sharing resistor R2 and the second bus capacitor C2 form a voltage-dividing unit 106, denoted as the second voltage-dividing unit 106; the third voltage-sharing resistor R3 corresponds to the third bus capacitor C3, that is, the third voltage-sharing resistor R3 and the third bus capacitor C3 form a voltage-dividing unit 106, denoted as the third voltage-dividing unit 106; the fourth voltage-sharing resistor R4 corresponds to the fourth bus capacitor C4, that is, the fourth voltage-sharing resistor R4 and the fourth bus capacitor C4 form a voltage-dividing unit 106, denoted as the fourth voltage-dividing unit 106.

[0097] Exemplarily, assuming that the bus voltage of the DC bus is 1000V, then in the ideal state, the voltage-dividing voltage on each bus capacitor 102 is 250V, and the voltage-dividing voltage on each voltage-sharing resistor 104 is also 250V. At this time, there is no voltage difference between the voltage-sharing resistor 104 and the bus capacitor 102. However, when the equivalent resistance of a certain bus capacitor 102 increases, assuming that the equivalent resistance of the second bus capacitor C2 increases, the voltage-dividing voltage on the second bus capacitor C2 will increase, and at the same time, the voltage-dividing voltages on the first bus capacitor C1, the third bus capacitor C3, and the fourth bus capacitor C4 will decrease accordingly. When the voltage difference between the second bus capacitor C2 and the second voltage-sharing resistor R2 exceeds the conduction voltage of the corresponding triode, the triode conducts, and the second bus capacitor C2 discharges through the triode, so that the voltage-dividing voltage on the second bus capacitor C2 decreases, enabling the voltage division on the entire bus circuit to achieve dynamic adjustment and balance.

[0098] In some embodiments of the present application, optionally, the switching module 108 includes a first triode Q1. The first triode Q1 is an NPN-type triode. The collector of the first triode Q1 is electrically connected to the positive electrode of the first bus capacitor C1, the emitter of the first triode Q1 is electrically connected to the negative electrode of the first bus capacitor C1, and the base of the first triode Q1 is electrically connected to the negative electrode of the first voltage-sharing resistor R1.

[0099] In this embodiment, the switching module 108 includes a first triode Q1, which is used to adjust the charging and discharging of the first bus capacitor C1. The first bus capacitor C1 is electrically connected to the positive pole of the DC power supply 200. Among them, the first triode Q1 is specifically an NPN-type triode. The collector of the first triode Q1 is electrically connected to the positive pole of the first bus capacitor C1, the emitter of the first triode Q1 is electrically connected to the negative pole of the first bus capacitor C1, and the base of the first triode Q1 is electrically connected to the negative pole of the first equalizing resistor R1.

[0100] Under normal circumstances, the divided voltage of the first bus capacitor C1 is the same as the divided voltage of the first equalizing resistor R1. At this time, the voltage between the collector and the emitter of the first triode Q1 is less than the conduction voltage of the first triode Q1, and the first triode Q1 is in the cut-off state. When the equivalent resistance of the first bus capacitor C1 increases, the divided voltage of the first bus capacitor C1 increases, which is reflected as an increase in the voltage of the collector of the first triode Q1, while the divided voltage on the first equalizing resistor R1 remains unchanged. When the divided voltage of the first bus capacitor C1 increases to a certain extent, the voltage difference between the collector and the base of the first triode Q1 exceeds the conduction voltage of the first triode Q1, then the first triode Q1 conducts, and at this time the first bus capacitor C1 discharges externally through the first triode Q1.

[0101] Exemplarily, a first current-limiting resistor R5 is connected in series with the collector of the first triode Q1. The energy released by the first bus capacitor will be consumed by the first current-limiting resistor R5, so that the energy of the first bus capacitor C1 decreases, and the divided voltage of the first bus capacitor C1 decreases. When the divided voltage of the first bus capacitor C1 decreases to a certain extent, the voltage between the collector and the base of the first triode Q1 is less than the conduction voltage of the first triode Q1, then the first triode Q1 resumes cut-off.

[0102] In this application, by setting the equalizing resistor 104 and the switching module 108, the dynamic adjustment of the divided voltage of the series bus capacitors 102 on the DC bus circuit 100 is realized, ensuring that the divided voltages of multiple bus capacitors 102 approach the same, and ensuring the service life of the DC bus circuit 100.

[0103] In some embodiments of the present application, optionally, the switching module 108 further includes a second triode Q2 and a third triode Q3. The second triode Q2 is an NPN-type triode, and the third triode Q3 is a PNP-type triode. The collector of the second triode Q2 is electrically connected to the positive electrode of the second bus capacitor C2, the emitter of the second triode Q2 is electrically connected to the negative electrode of the second bus capacitor C2, and the base of the second triode Q2 is electrically connected to the negative electrode of the second voltage equalizing resistor R2. The emitter of the third triode Q3 is electrically connected to the emitter of the second triode Q2, the collector of the third triode Q3 is electrically connected to the negative electrode of the third bus capacitor C3, and the base of the third triode Q3 is electrically connected to the positive electrode of the third voltage equalizing resistor R3.

[0104] In this embodiment, the switching module 108 further includes a second triode Q2 and a third triode Q3, and the second triode Q2 and the third triode Q3 form a pair of transistors. Among them, the second triode Q2 is specifically an NPN-type triode, and the third triode Q3 is specifically a PNP-type triode.

[0105] The bases of the second triode Q2 and the third triode Q3 are both connected to the common point of the second voltage equalizing resistor R2 and the third voltage equalizing resistor R3. The collector of the second triode Q2 is connected to the positive electrode of the second bus capacitor C2. The emitters of the second triode Q2 and the third triode Q3 are both connected to the common point of the second bus capacitor C2 and the third bus capacitor C3. The collector of the third triode Q3 is connected to the negative electrode of the third bus capacitor C3.

[0106] Under normal circumstances, the voltage divided by the second bus capacitor C2 is the same as the voltage divided by the second voltage equalizing resistor R2, and the voltage divided by the third bus capacitor C3 is the same as the voltage divided by the third voltage equalizing resistor R3. At this time, the voltages between the collectors and emitters of the second triode Q2 and the third triode Q3 are both less than their conduction voltages, and the first triode Q1 is in the cut-off state.

[0107] Exemplarily, assume that the equivalent resistance of the second bus capacitor C2 increases, the voltage divided by the second bus capacitor C2 increases, and the voltage divided by the third bus capacitor C3 decreases. When the voltage of the third bus capacitor C3 is less than the voltage of the common point of the second voltage equalizing resistor R2 and the third voltage equalizing resistor R3 (i.e., the midpoint voltage of the voltage equalizing circuit), the pair of transistors composed of the second triode Q2 and the third triode Q3 will work. At this time, the second triode Q2 conducts, and the second capacitor discharges through the second triode Q2, so that the energy of the second capacitor is consumed through the second current limiting resistor R6 connected to the collector of the second triode Q2, thereby reducing the voltage divided by the second capacitor. When the energy of the second bus capacitor C2 decreases and the voltage divided by the second bus capacitor C2 decreases to a certain extent, the second diode resumes cut-off, so that the voltage division voltages of the multiple bus capacitors 102 in the DC bus circuit 100 achieve dynamic balance.

[0108] In this application, a method of forming a pair of transistors by setting a PNP transistor and an NPN transistor is adopted to dynamically balance the divided voltage of the bus capacitor 102 on the DC bus circuit 100, thereby improving the reliability of the bus circuit.

[0109] In some embodiments of this application, optionally, the switch module 108 further includes a fourth transistor Q4. The fourth transistor Q4 is a PNP-type transistor. The emitter of the fourth transistor Q4 is electrically connected to the positive electrode of the fourth bus capacitor C4. The collector of the fourth transistor Q4 is electrically connected to the negative electrode of the fourth bus capacitor C4. The base of the fourth transistor Q4 is electrically connected to the positive electrode of the fourth equalizing resistor R4.

[0110] In this embodiment, the switch module 108 further includes a fourth transistor Q4. The fourth transistor Q4 is a PNP-type transistor. The emitter of the fourth transistor Q4 is electrically connected to the positive electrode of the fourth bus capacitor C4. The collector of the fourth transistor Q4 is electrically connected to the negative electrode of the fourth bus capacitor C4. The base of the fourth transistor Q4 is electrically connected to the positive electrode of the fourth equalizing resistor R4.

[0111] In this embodiment, the switch module 108 includes a fourth transistor Q4. The fourth transistor Q4 is used to adjust the charge and discharge of the fourth bus capacitor C4. The fourth bus capacitor C4 is electrically connected to the negative electrode of the DC power supply 200. Among them, the fourth transistor Q4 is specifically a PNP-type transistor. The collector of the fourth transistor Q4 is electrically connected to the positive electrode of the fourth bus capacitor C4. The emitter of the fourth transistor Q4 is electrically connected to the negative electrode of the fourth bus capacitor C4. And the base of the fourth transistor Q4 is electrically connected to the negative electrode of the fourth equalizing resistor R4.

[0112] Under normal circumstances, the divided voltage of the fourth bus capacitor C4 is the same as the divided voltage of the fourth equalizing resistor R4. At this time, the voltage between the collector and emitter of the fourth transistor Q4 is less than the conduction voltage of the fourth transistor Q4, and the fourth transistor Q4 is in a cut-off state. When the equivalent resistance of the fourth bus capacitor C4 increases, the divided voltage of the fourth bus capacitor C4 increases, which is reflected as an increase in the voltage of the collector of the fourth transistor Q4, while the divided voltage on the fourth equalizing resistor R4 remains unchanged. When the divided voltage of the fourth bus capacitor C4 increases to a certain extent, the voltage difference between the collector and base of the fourth transistor Q4 exceeds the conduction voltage of the fourth transistor Q4, then the fourth transistor Q4 conducts, and at this time, the fourth bus capacitor C4 discharges externally through the fourth transistor Q4.

[0113] Exemplarily, a fourth current-limiting resistor R8 is connected in series with the collector of the fourth triode Q4. The energy released by the fourth bus capacitor will be consumed by the fourth current-limiting resistor R8, thereby reducing the energy of the fourth bus capacitor C4 and reducing the voltage division of the fourth bus capacitor C4. When the voltage division of the fourth bus capacitor C4 is reduced to a certain extent, the voltage between the collector and the base of the fourth triode Q4 is less than the conduction voltage of the fourth triode Q4, and the fourth triode Q4 resumes cutoff.

[0114] In this application, by setting the voltage-sharing resistor 104 and the switch module 108, the dynamic regulation of the voltage division of the series-connected bus capacitors 102 on the DC bus circuit 100 is realized, ensuring that the voltage divisions of multiple bus capacitors 102 approach the same, and ensuring the service life of the DC bus circuit 100.

[0115] In some embodiments of this application, Figure 2 The circuit diagram of the DC bus circuit 100 of some embodiments of this application is shown, as Figure 2 shown, the switch module 108 includes a fifth triode Q5, a sixth triode Q6, a seventh triode Q7, an eighth triode Q8, a ninth triode Q9, and a tenth triode Q10.

[0116] The fifth triode Q5 is an NPN-type triode. The collector of the fifth triode Q5 is electrically connected to the positive electrode of the first bus capacitor C1, the emitter of the fifth triode Q5 is electrically connected to the negative electrode of the first bus capacitor C1, and the base of the fifth triode Q5 is electrically connected to the common point of the first voltage-sharing resistor R1 and the second voltage-sharing resistor R2.

[0117] The sixth triode Q6 is a PNP-type triode. The emitter of the sixth triode Q6 is electrically connected to the emitter of the fifth triode Q5, the collector of the sixth triode Q6 is electrically connected to the collector of the seventh triode Q7, and the base of the sixth triode Q6 is electrically connected to the common point of the first voltage-sharing resistor R1 and the second voltage-sharing resistor R2.

[0118] The seventh triode Q7 is an NPN-type triode. The emitter of the seventh triode Q7 is electrically connected to the negative electrode of the second bus capacitor C2, and the base of the seventh triode Q7 is electrically connected to the common point of the second voltage-sharing resistor R2 and the third voltage-sharing resistor R3.

[0119] The eighth triode Q8 is a PNP-type triode. The emitter of the eighth triode Q8 is electrically connected to the emitter of the seventh triode Q7, the collector of the eighth triode Q8 is electrically connected to the collector of the ninth triode Q9, and the base of the eighth triode Q8 is electrically connected to the common point of the second voltage-sharing resistor R2 and the third voltage-sharing resistor R3.

[0120] The ninth triode Q9 is an NPN type triode. The emitter of the ninth triode Q9 is electrically connected to the negative electrode of the third bus capacitor C3, and the base of the ninth triode Q9 is electrically connected to the common point of the third voltage-sharing resistor R3 and the fourth voltage-sharing resistor R4.

[0121] The thirteenth triode Q10 is a PNP type triode. The emitter of the thirteenth triode Q10 is electrically connected to the emitter of the ninth triode Q9, the collector of the thirteenth triode Q10 is electrically connected to the negative electrode of the fourth bus capacitor, and the base of the thirteenth triode Q10 is electrically connected to the common point of the third voltage-sharing resistor R3 and the fourth voltage-sharing resistor R4.

[0122] In this embodiment, the fifth triode Q5 and the sixth triode Q6 form a pair of transistors, the seventh triode Q7 and the eighth triode Q8 form a pair of transistors, and the ninth triode Q9 and the thirteenth triode Q10 form a pair of transistors. Among them, the fifth triode Q5, the seventh triode Q7, and the ninth triode Q9 are NPN type triodes, and the sixth triode Q6, the eighth triode Q8, and the thirteenth triode Q10 are PNP type triodes.

[0123] The first bus capacitor C1, the second bus capacitor C2, the third bus capacitor C3, and the fourth bus capacitor C4 are connected in sequence, and the positive electrode of the first bus capacitor C1 is electrically connected to the positive electrode of the DC power supply 200, and the negative electrode of the fourth bus capacitor C4 is electrically connected to the negative electrode of the DC power supply 200.

[0124] The collector of the fifth triode Q5 is connected in series with the first current-limiting resistor R5 and is connected to the positive electrode of the first bus capacitor C1 through the first current-limiting resistor R5. The emitter of the fifth triode Q5 is connected to the negative electrode of the first bus capacitor C1, and the base of the fifth triode Q5 is connected to the common point of the first voltage-sharing resistor R1 and the second voltage-sharing resistor R2.

[0125] The emitter of the sixth triode Q6 is electrically connected to the emitter of the fifth triode Q5 and is connected to the negative electrode of the first bus capacitor C1. The collector of the sixth triode Q6 is connected in series with the second current-limiting resistor R6 and is connected to the collector of the seventh triode Q7 through the second current-limiting resistor R6. The base of the sixth triode Q6 is connected to the common point of the first voltage-sharing resistor R1 and the second voltage-sharing resistor R2.

[0126] The collector of the seventh triode Q7 is connected to the collector of the sixth triode Q6 through the second current-limiting resistor R6. The emitter of the seventh triode Q7 is connected to the common point of the second bus capacitor C2 and the third bus capacitor C3 and is connected to the emitter of the eighth triode Q8. The base of the seventh triode Q7 is connected to the common point of the second voltage-sharing resistor R2 and the third voltage-sharing resistor R3.

[0127] The emitter of the eighth triode Q8 is connected to the emitter of the seventh triode Q7 and to the common point of the second bus capacitor C2 and the third bus capacitor C3. The collector of the eighth triode Q8 is connected in series with the third current-limiting resistor R7 and is connected to the collector of the ninth triode Q9 through the third current-limiting resistor R7. The base of the eighth triode Q8 is connected to the common point of the second voltage-sharing resistor R2 and the third voltage-sharing resistor R3.

[0128] The collector of the ninth triode Q9 is connected to the collector of the eighth triode Q8 through the third current-limiting resistor R7. The emitter of the ninth triode Q9 is connected to the common point of the third bus capacitor C3 and the fourth bus capacitor C4 and is connected to the emitter of the tenth triode Q10. The base of the ninth triode Q9 is connected to the common point of the third voltage-sharing resistor R3 and the fourth voltage-sharing resistor R4.

[0129] The emitter of the tenth triode Q10 is connected to the emitter of the ninth triode Q9 and to the common point of the third bus capacitor C3 and the fourth bus capacitor C4. The collector of the tenth triode Q10 is connected in series with the fourth current-limiting resistor R8 and is connected to the negative electrode of the fourth bus capacitor C4 through the fourth current-limiting resistor R8. The base of the tenth triode Q10 is connected to the negative electrode of the fourth voltage-sharing resistor R4.

[0130] By setting the PNP triode and the NPN triode pair tube in the embodiment of the present application, the reliability of the DC bus circuit 100 can be improved.

[0131] In some embodiments of the present application, optionally, the resistance values of the N voltage-sharing resistors 104 are equal.

[0132] In this embodiment, for the N bus capacitors 102 connected in series in the DC bus circuit 100, N voltage-sharing resistors 104 connected in series are correspondingly provided. The N voltage-sharing resistors 104 connected in series form a voltage-sharing circuit, and this voltage-sharing circuit is connected in parallel with the bus after the N bus capacitors 102 are connected in series. Therefore, the voltage across the bus is equal to the voltage across the voltage-sharing circuit.

[0133] Since the resistance values of the N voltage-sharing resistors 104 are equal, the voltage divided by each voltage-sharing resistor 104 is also equal. In an ideal case, the voltage divided by each bus capacitor 102 should also be equal, and there is no voltage difference between the voltage-sharing resistor 104 and the bus capacitor 102.

[0134] When the equivalent resistance of one or more bus capacitors 102 changes, the voltage division voltage of the bus capacitor 102 also changes, and a voltage difference is generated between the bus capacitor 102 and the corresponding voltage equalizing resistor 104. When the voltage difference exceeds the conduction voltage of the switching module 108, the switching module 108 conducts. At this time, the bus capacitor 102 with the generated voltage difference is charged or discharged through the switching module 108, causing the energy of the bus capacitor 102 to change. Finally, the voltage division voltage of the bus capacitor 102 changes, making the voltage division voltages of multiple series-connected bus capacitors 102 in the bus DC bus circuit 100 approach balance.

[0135] Exemplarily, assume that the bus voltage is 1000V, the number of bus capacitors 102 and voltage equalizing resistors 104 is 4 each, and the resistance value of each voltage equalizing resistor 104 is 200 kΩ. Then the voltage division voltage of each voltage equalizing resistor 104 is 250V.

[0136] In this application, by setting the same number of voltage equalizing resistors 104 as the number of bus capacitors 102, and using the voltage of the voltage equalizing resistor 104 as the reference voltage to adjust the voltage division voltage of the bus voltage, the dynamic adjustment of the voltage division voltage of the series-connected bus capacitors 102 on the DC bus circuit 100 is achieved, ensuring that the voltage divisions of multiple bus capacitors 102 approach the same and guaranteeing the service life of the DC bus circuit 100.

[0137] In some embodiments of this application, an energy storage device is provided. The energy storage device includes the DC bus circuit 100 provided in any of the above embodiments. Therefore, this energy storage device also includes all the beneficial effects of the DC bus circuit 100 provided in any of the above embodiments. To avoid repetition, they will not be elaborated here.

[0138] In the description of this application, the term "multiple" refers to two or more. Unless otherwise clearly defined, the orientation or positional relationship indicated by terms such as "upper" and "lower" is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing this application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation to this application; terms such as "connection", "installation", and "fixation" should all be understood in a broad sense. For example, "connection" can be a fixed connection, a detachable connection, or an integral connection; it can be directly connected or indirectly connected through an intermediate medium. For those of ordinary skill in the art, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0139] In the description of the present application, the descriptions of terms such as "one embodiment", "some embodiments", "specific embodiments", etc. mean that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. In the present application, the schematic representations of the above terms do not necessarily refer to the same embodiment or instance. Moreover, the specific features, structures, materials or characteristics described may be combined in a suitable manner in any one or more embodiments or examples.

[0140] The foregoing is only the preferred embodiment of the present application and is not intended to limit the present application. For those skilled in the art, the present application may have various changes and modifications. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included within the protection scope of the present application.

Claims

1. A DC bus circuit, characterized in that: The DC bus circuit comprises: N bus capacitors, wherein the N bus capacitors are connected in series, and N is a positive integer; N voltage-equalizing resistors, the N voltage-equalizing resistors are connected in series, and each of the voltage-equalizing resistors and one of the bus capacitors form a voltage-dividing unit; A switch module, wherein the switch module is electrically connected to the voltage divider unit, wherein when the voltage difference between the bus capacitor and the voltage balancing resistor in one of the voltage divider units is greater than the turn-on voltage of the switch module electrically connected to the voltage divider unit, the switch module is turned on to allow the bus capacitor to be charged or discharged through the switch module.

2. The DC bus circuit according to claim 1, characterized in that: The switch module comprises a transistor, the base of the transistor is electrically connected to the voltage-equalizing resistor, and the emitter and collector of the transistor are electrically connected to two ends of a bus capacitor respectively.

3. The DC bus circuit according to claim 2, characterized in that: The switch module also includes: A current limiting resistor, wherein a first end of the current limiting resistor is electrically connected to the collector of the transistor, and a second end of the current limiting resistor is electrically connected to the bus capacitor.

4. The DC bus circuit according to any one of claims 1 to 3, characterized in that: The N bus capacitors include a first bus capacitor, a second bus capacitor, a third bus capacitor and a fourth bus capacitor connected in series in sequence, the first bus capacitor is electrically connected to the positive electrode of the DC power supply, and the fourth bus capacitor is electrically connected to the negative electrode of the DC power supply; The N equalizing resistors include a first equalizing resistor, a second equalizing resistor, a third equalizing resistor and a fourth equalizing resistor connected in series in sequence, wherein the first equalizing resistor corresponds to the first bus capacitor, the second equalizing resistor corresponds to the second bus capacitor, the third equalizing resistor corresponds to the third bus capacitor, and the fourth equalizing resistor corresponds to the fourth bus capacitor.

5. The DC bus circuit according to claim 4, characterized in that: The switch module includes a first transistor, which is an NPN transistor, wherein the collector of the first transistor is electrically connected to the positive electrode of the first bus capacitor, the emitter of the first transistor is electrically connected to the negative electrode of the first bus capacitor, and the base of the first transistor is electrically connected to the negative electrode of the first balancing resistor.

6. The DC bus circuit according to claim 4, characterized in that: The switch module further includes a second transistor and a third transistor, wherein the second transistor is an NPN transistor and the third transistor is a PNP transistor; The collector of the second triode is electrically connected to the positive electrode of the second bus capacitor, the emitter of the second triode is electrically connected to the negative electrode of the second bus capacitor, and the base of the second triode is electrically connected to the negative electrode of the second balancing resistor; The emitter of the third triode is electrically connected to the emitter of the second triode, the collector of the third triode is electrically connected to the negative electrode of the third bus capacitor, and the base of the third triode is electrically connected to the positive electrode of the third balancing resistor.

7. The DC bus circuit according to claim 4, characterized in that: The switch module also includes a fourth transistor, which is a PNP transistor. The emitter of the fourth transistor is electrically connected to the positive electrode of the fourth bus capacitor, the collector of the fourth transistor is electrically connected to the negative electrode of the fourth bus capacitor, and the base of the fourth transistor is electrically connected to the positive electrode of the fourth equalizing resistor.

8. The DC bus circuit according to claim 4, characterized in that: The switch module includes a fifth triode, a sixth triode, a seventh triode, an eighth triode, a ninth triode and a tenth triode; The fifth transistor is an NPN transistor, the collector of the fifth transistor is electrically connected to the positive electrode of the first bus capacitor, the emitter of the fifth transistor is electrically connected to the negative electrode of the first bus capacitor, and the base of the fifth transistor is electrically connected to the common point of the first balancing resistor and the second balancing resistor; The sixth transistor is a PNP transistor, the emitter of the sixth transistor is electrically connected to the emitter of the fifth transistor, the collector of the sixth transistor is electrically connected to the collector of the seventh transistor, and the base of the sixth transistor is electrically connected to a common point of the first balancing resistor and the second balancing resistor; The seventh transistor is an NPN transistor, the emitter of the seventh transistor is electrically connected to the negative electrode of the second bus capacitor, and the base of the seventh transistor is electrically connected to a common point of the second balancing resistor and the third balancing resistor; The eighth transistor is a PNP transistor, the emitter of the eighth transistor is electrically connected to the emitter of the seventh transistor, the collector of the eighth transistor is electrically connected to the collector of the ninth transistor, and the base of the eighth transistor is electrically connected to a common point of the second balancing resistor and the third balancing resistor; The ninth transistor is an NPN transistor, the emitter of the ninth transistor is electrically connected to the negative electrode of the third bus capacitor, and the base of the ninth transistor is electrically connected to a common point of the third balancing resistor and the fourth balancing resistor; The thirteenth transistor is a PNP type transistor, the emitter of the thirteenth transistor is electrically connected to the emitter of the ninth transistor, the collector of the thirteenth transistor is electrically connected to the negative electrode of the fourth bus capacitor, and the base of the thirteenth transistor is electrically connected to the common point of the third equalizing resistor and the fourth equalizing resistor.

9. The DC bus circuit according to any one of claims 1 to 3, characterized in that: The resistance values ​​of the N voltage balancing resistors are equal.

10. An energy storage device, characterized in that: The energy storage device comprises: A DC bus circuit as claimed in any one of claims 1 to 9.

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