A power supply voltage conversion circuit, battery pack and energy storage system

Abstract

This application provides a power supply voltage conversion circuit, a battery pack, and an energy storage system, including: a bidirectional DC-DC converter unit, a lithium battery pack, and a controller; the bidirectional DC-DC converter unit includes a high-voltage side and a low-voltage side; the high-voltage side and the low-voltage side of the bidirectional DC-DC converter unit are electrically connected to the controller, and the low-voltage side of the bidirectional DC-DC converter unit is electrically connected to the lithium battery pack; the bidirectional DC-DC converter unit is used to receive a first control signal issued by the controller during a preset initial stage of charging when the controller receives a charging command, and to switch to charging mode after the preset initial stage ends. This application can achieve stable battery pack charging and discharging functions, making the battery pack lighter and improving the reliability of the battery pack system.

Description

Technical Field

[0001] The present application relates to the technical field of power supply voltage conversion, and in particular to a power supply voltage conversion circuit, a battery pack and an energy storage system. Background Art

[0002] In the application of inverters, a wide range of unidirectional inverters can be connected to a DC bus between DC400V and DC800V, but a three-phase inverter can only be connected to a DC800V DC bus, that is, a DC800V DC bus can be applied to single-phase and three-phase inverters. However, most existing 800V battery packs are stacked in a stacking manner, where multiple batteries are stacked into an 800V battery pack, which is often bulky. Due to the discrete voltage of the battery cells, each battery cell in the high-voltage battery pack cannot be fully charged or discharged at the same time, resulting in low utilization of the energy storage capacity and reduced reliability for long-term stable operation. There are also cases where a DCDC DC conversion module is used to boost a low-voltage battery pack to an 800V battery pack. On the one hand, the boosting process is not stable enough, and on the other hand, when the battery pack is charged, it cannot be accurately reduced to the input voltage required by the low-voltage side, affecting the normal charging of the battery pack and low system reliability. Summary of the invention

[0003] In view of this, the embodiments of the present application provide a power supply voltage conversion circuit, a battery pack and an energy storage system, which can realize stable battery pack charging and discharging functions, make the battery pack more lightweight and improve the reliability of the battery pack system.

[0004] In a first aspect, an embodiment of the present application provides a power supply voltage conversion circuit, comprising: a bidirectional DC conversion unit, a lithium battery pack, and a controller;

[0005] The bidirectional DC conversion unit includes a high voltage side and a low voltage side; the high voltage side and the low voltage side of the bidirectional DC conversion unit are electrically connected to the controller respectively, and the low voltage side of the bidirectional DC conversion unit is electrically connected to the lithium battery pack;

[0006] The bidirectional DC conversion unit is used to receive a first control signal sent by the controller in a preset initial stage of charging when the controller receives a charging instruction, and switch to a charging mode after the preset initial stage ends.

[0007] In a possible implementation, the bidirectional DC conversion unit includes a half-bridge circuit on the high voltage side, a transformer circuit, and a full-bridge circuit on the low voltage side;

[0008] The bidirectional DC conversion unit is used to control the full-bridge circuit to be in a short-circuit state when receiving the first control signal output by the controller.

[0009] In a possible implementation manner, the transformer circuit includes a primary coil, a secondary coil, a first resonant inductor, and a second resonant inductor;

[0010] The first resonant inductor is connected in series with the primary coil, and the second resonant inductor is connected in series with the secondary coil;

[0011] The first resonant inductor is used to receive the energy storage signal output by the half-bridge circuit on the high-voltage side and store energy to form an energy storage voltage source when the first control signal output by the controller controls the full-bridge circuit to be in a short-circuit state.

[0012] In a possible implementation manner, the power supply voltage conversion circuit further includes a resonant current collection unit;

[0013] The resonant current collection unit is connected in series to the primary circuit of the transformer circuit, and the resonant current collection unit is electrically connected to the controller.

[0014] In a possible implementation, the power supply voltage conversion circuit further includes a filtering unit, a pre-charging unit and a voltage stabilizing unit, wherein a first port of the filtering unit is connected to a first port of the pre-charging unit, a second port of the pre-charging unit is connected to a first port of the voltage stabilizing unit, and a second port of the pre-charging unit is connected to a first port of the bidirectional DC conversion unit;

[0015] The second port of the filter unit is connected to the second port of the voltage stabilizing unit, and the second port of the filter unit is connected to the second port of the bidirectional direct current conversion unit.

[0016] In a possible implementation manner, the input end of the filter unit is connected to a connector, and the filter unit is connected to the 800V DC bus through the connector;

[0017] In a possible implementation manner, the positive terminal of the connector is provided with a fuse, and the fuse is used for overcurrent protection of the circuit.

[0018] In a possible implementation manner, the power supply voltage conversion circuit further includes a first auxiliary power supply and a second auxiliary power supply;

[0019] The first auxiliary power supply is connected to the high voltage side of the bidirectional DC conversion unit, the second auxiliary power supply is connected to the low voltage side of the bidirectional DC conversion unit, the output end of the first auxiliary power supply is connected to the input end of the second auxiliary power supply, and the first auxiliary power supply and the second auxiliary power supply are both connected to the controller.

[0020] In a possible implementation manner, the power supply voltage conversion circuit further includes a battery management module;

[0021] The first signal input terminal of the battery management module is connected to the lithium battery pack, and the second signal input terminal and the signal output terminal of the battery management module are both connected to the controller.

[0022] In a possible implementation manner, the power supply voltage conversion circuit further includes a communication module;

[0023] The communication module is electrically connected to the controller; the communication module is used to send a charging instruction or a discharging instruction to the controller, and is also used to realize communication between the controller and an external host computer.

[0024] In a second aspect, an embodiment of the present application further provides an 800V battery pack, comprising a power supply voltage conversion device, wherein the power supply voltage conversion circuit of the power supply voltage conversion device adopts the power supply voltage conversion circuit described in any one of the first aspects.

[0025] In the third aspect, an embodiment of the present application further provides a stacked three-phase energy storage system, including a three-phase rectifier inverter module and multiple 800V battery packs, wherein the three-phase rectifier inverter module and each 800V battery pack are respectively connected to a DC bus, and the 800V battery pack adopts the 800V battery pack described in the second aspect.

[0026] The technical solution provided by this application has the following beneficial effects:

[0027] The present application provides a power supply voltage conversion circuit, in which a DC conversion unit is applied to the power supply voltage conversion circuit described in the present application. When a charging instruction, a discharging instruction and a resonant current signal are received by a controller, the bidirectional DC conversion unit is controlled respectively, so that the leakage inductance of the high-voltage side winding of the bidirectional DC conversion unit has an energy storage function, so as to increase the output voltage on the high-voltage side and the input voltage on the low-voltage side, realize normal charging of a lithium battery pack, and ensure that the bidirectional DC conversion unit has a stable bidirectional energy transmission function, thereby realizing a stable charging and discharging function of the battery pack, and increasing the reliability of the entire battery pack system. At the same time, the lithium battery pack is converted into a battery pack with a high-voltage output port through the bidirectional DC conversion unit, replacing the traditional method of stacking multiple battery packs to provide a high-voltage output port, making the 800V energy storage module more lightweight.

[0028] In order to make the above-mentioned objects, features and advantages of the present application more obvious and easy to understand, preferred embodiments are specifically cited below and described in detail with reference to the attached drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0030] Figure 1 A circuit schematic diagram of a power supply voltage conversion circuit according to an embodiment of the present application is shown;

[0031] Figure 2 A circuit diagram of a bidirectional DC conversion unit and a controller according to an embodiment of the present application is shown;

[0032] Figure 3 A circuit diagram of a lithium battery pack and part of its loads described in an embodiment of the present application is shown;

[0033] Figure 4 A circuit diagram of the filter unit described in an embodiment of the present application is shown;

[0034] Figure 5 A circuit diagram of the pre-charging unit and the voltage stabilizing unit described in an embodiment of the present application is shown. DETAILED DESCRIPTION

[0035] To make the purpose, technical scheme and advantages of the embodiments of the present application clearer, the technical scheme in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all of the embodiments. The components of the embodiments of the present application generally described and shown in the drawings here can be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present application provided in the drawings is not intended to limit the scope of the application claimed for protection, but merely represents the selected embodiments of the present application. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without making creative work belong to the scope of protection of the present application.

[0036] In the following description, reference is made to “some embodiments”, which describe a subset of all possible embodiments, but it will be understood that “some embodiments” may be the same subset or different subsets of all possible embodiments and may be combined with each other without conflict.

[0037] In the prior art, the following problems may exist:

[0038] In the application of inverters, unidirectional inverters can be connected to DC buses between DC400V and DC800V, but three-phase inverters can only be connected to DC800V buses, that is, DC800V buses can be applied to single-phase and three-phase inverters. However, most existing 800V battery packs are stacked to stack multiple batteries into 800V battery packs, which are often bulky and have relatively low system reliability. There are also cases where DCDC DC conversion modules are used to boost low-voltage battery packs to 800V battery packs. On the one hand, the boosting process is not stable enough, and on the other hand, when the battery pack is charged, it cannot be accurately reduced to the input voltage required by the low-voltage side, affecting the normal charging of the battery pack and low system reliability.

[0039] Based on this, the present application provides a power supply voltage conversion circuit, and a DC conversion unit is applied to the power supply voltage conversion circuit described in the present application. When the controller receives charging instructions, discharging instructions and resonant current signals, the bidirectional DC conversion unit is controlled respectively, so that the high-voltage side winding of the bidirectional DC conversion unit has an energy storage function, so as to increase the output voltage on the high-voltage side and the input voltage on the low-voltage side, so as to realize normal charging of the lithium battery pack, and also ensure that the bidirectional DC conversion unit has a stable bidirectional energy transmission function, thereby realizing the stable charging and discharging function of the battery pack, and increasing the reliability of the entire battery pack system. At the same time, the lithium battery pack is converted into a battery pack with a high-voltage output port through the bidirectional DC conversion unit, replacing the traditional method of stacking multiple battery packs to provide a high-voltage output port, making the battery pack lighter.

[0040] Please refer to Figure 1 , Figure 1 A circuit schematic diagram of a power supply voltage conversion circuit according to an embodiment of the present application is shown. Specifically, the power supply voltage conversion circuit includes: a bidirectional DC conversion unit, a lithium battery pack and a controller;

[0041] The bidirectional DC conversion unit includes a high voltage side and a low voltage side; the high voltage side and the low voltage side of the bidirectional DC conversion unit are electrically connected to the controller respectively, and the low voltage side of the bidirectional DC conversion unit is electrically connected to the lithium battery pack;

[0042] The bidirectional DC conversion unit is used to receive a first control signal sent by the controller in a preset initial stage of charging when the controller receives a charging instruction, and switch to a charging mode after the preset initial stage ends.

[0043] In an embodiment of the present application, the controller is used to send a first control signal to the low-voltage side of the bidirectional DC conversion unit in a preset initial stage of charging according to a charging instruction, and at the end of the preset initial stage, control the bidirectional DC conversion unit to switch to a charging mode; and is also used to control the bidirectional DC conversion unit to switch to a discharging mode according to a discharging instruction.

[0044] In the embodiment of the present application, the power supply voltage conversion circuit further includes a resonant current collection unit;

[0045] The resonant current collection unit is connected in series in the primary circuit of the transformer circuit, and the resonant current collection unit is electrically connected to the controller;

[0046] In the embodiment of the present application, the resonant current acquisition unit is used to acquire the resonant current signal of the transformer circuit after the preset initial stage ends and output the acquisition result to the controller, so that the controller sends a second control signal to the bidirectional DC conversion unit when the bidirectional DC conversion unit is in the charging mode, and sends a third control signal to the bidirectional DC conversion unit when the bidirectional DC conversion unit is in the discharging mode. The bidirectional DC conversion unit switches to the charging mode when receiving the second control signal, and switches to the discharging mode when receiving the third control signal.

[0047] In some embodiments, the resonant current acquisition unit may be a current sensor.

[0048] In an embodiment of the present application, the bidirectional DC conversion unit is used to control the bidirectional DC conversion unit to convert the high voltage on the high voltage side into the low voltage on the low voltage side and charge the lithium battery pack when receiving a second control signal; and to control the bidirectional DC conversion unit to convert the low voltage signal on the low voltage side into the high voltage signal on the high voltage side when receiving a third control signal.

[0049] In the embodiment of the present application, the lithium battery pack is used to charge when the bidirectional DC conversion unit is in a charging mode, and to output voltage to the low voltage side of the bidirectional DC conversion unit when the bidirectional DC conversion unit is in a discharging mode.

[0050] In the embodiment of the present application, the bidirectional DC conversion unit includes a half-bridge circuit on the high voltage side, a transformer circuit and a full-bridge circuit on the low voltage side;

[0051] The bidirectional DC conversion unit is used to control the full-bridge circuit to be in a short-circuit state when receiving the first control signal output by the controller.

[0052] In an embodiment of the present application, the bidirectional DC conversion unit is used to control the full-bridge circuit to convert the AC power output by the low-voltage side of the transformer circuit into DC power when receiving the second control signal output by the controller; and is also used to control the half-bridge circuit to convert the AC power output by the high-voltage side of the transformer circuit into DC power when receiving the third control signal output by the controller.

[0053] The transformer circuit includes a primary coil, a secondary coil, a first resonant inductor and a second resonant inductor; the first resonant inductor is connected in series with the primary coil, and the second resonant inductor is connected in series with the secondary coil;

[0054] The first resonant inductor is used to receive the energy storage signal output by the half-bridge circuit on the high-voltage side and store energy to form an energy storage voltage source when the first control signal output by the controller controls the full-bridge circuit to be in a short-circuit state.

[0055] Please refer to Figure 2 and 3 , Figure 2 The circuit diagram of the bidirectional DC conversion unit and the controller described in the embodiment of the present application is shown. Figure 3A circuit diagram of the lithium battery pack and part of its load described in an embodiment of the present application is shown. The bidirectional DC conversion unit includes capacitors C8, C9, C10, a first resonant inductor Lr1, a second resonant inductor Lr2, and MOS tubes Q1~Q6, wherein MOS tubes Q1 and Q2 form a half-bridge circuit, capacitors C8, C9 and the first resonant inductor Lr1, capacitor C10 and the second resonant inductor Lr2, as well as the primary coil of the transformer and the secondary coil of the transformer form a resonant transformer circuit, and MOS tubes Q3~Q6 form a full-bridge circuit. Specifically, the drain of the MOS tube Q1 is connected to the first port of the voltage stabilizing unit, the source of the MOS tube Q1 is connected to the drain of the MOS tube Q2, the source of the MOS tube Q2 is connected to the second port of the voltage stabilizing unit, the gates of the MOS tubes Q1 and Q2 are respectively connected to the first output port and the second output port of the controller, the first port of the capacitor C8 is connected to the drain of the MOS tube Q1, the second port of the capacitor C8 is connected to the first port of the capacitor C9, the second port of the capacitor C9 is connected to the source of the MOS tube Q2, the first port of the first resonant inductor Lr1 is connected to the source of the MOS tube Q1, the second port of the first resonant inductor Lr1 is connected to the first port of the primary coil on the high-voltage side, and the second port of the primary coil on the high-voltage side is connected to the first port of the capacitor C9; the drain of the MOS tube Q3 is connected to the positive electrode of the lithium battery pack, and the source of the MOS tube Q3 is connected to the positive electrode of the MOS tube Q4 The drain of the MOS tube Q4 is connected to the first port of the resistor R3, and the second port of the resistor R3 is connected to the negative electrode of the lithium battery pack. By setting the resistor R3, the controller can obtain the current flowing through the resistor R3 according to the collected voltage of the resistor R3. The drain of the MOS tube Q5 is connected to the positive electrode of the lithium battery pack, the source of the MOS tube Q5 is connected to the drain of the MOS tube Q6, and the source of the MOS tube Q6 is connected to the first port of the resistor R3. The gates of the MOS tubes Q3-Q6 are respectively connected to the third, fourth, fifth, and sixth output ports of the controller. The first port of the second resonant inductor Lr2 is connected to the source of the MOS tube Q3, and the second port of the second resonant inductor Lr2 is connected to the first port of the capacitor C10. The second port of the capacitor C10 is connected to the first port of the secondary coil on the low-voltage side, and the second port of the secondary coil on the low-voltage side is connected to the source of the MOS tube Q5.

[0056] In some embodiments, the preset initial stage may be a period of time set in advance by the controller.

[0057] Specifically, when commanding the bidirectional DC conversion unit to enter the charging mode, the controller receives the charging instruction sent by the communication module, and while the MOS tube Q1 is turned on, in the preset initial stage of charging set by the controller, the controller sends a first control signal to the low-voltage side of the bidirectional DC conversion unit to control the MOS tube Q4 and the MOS tube Q6 to be turned on. Then, a closed loop is formed between the MOS tube Q4 and the MOS tube Q6, the secondary coil on the low-voltage side, the capacitor C10 and the second resonant inductor Lr2, that is, the secondary coil on the low-voltage side is in a short-circuit state, and the primary coil on the high-voltage side is also short-circuited. The circuit composed of the MOS tube Q1 and the capacitor C9 begins to charge and store energy for the first resonant inductor Lr1 on the high-voltage side. At the end of the preset initial stage, the MOS tube Q4 and the MOS tube Q6 exit the short circuit, the charging and energy storage of the first resonant inductor Lr1 is completed, and the first resonant inductor Lr1 forms an additional voltage source. The voltage source is superimposed on the voltage of the half-bridge circuit, and the input voltage on the high-voltage side is increased, that is, the output voltage on the low-voltage side is increased.

[0058] Specifically, at the end of the preset initial stage, the normal synchronous rectification stage is entered. At this time, the controller controls the MOS tube Q4 and the MOS tube Q6 to be disconnected, and controls the bidirectional DC conversion unit to be in the charging mode. The controller sends a second control signal to the bidirectional DC conversion unit. When receiving the second control signal, the bidirectional DC conversion unit controls the bidirectional DC conversion unit to convert the high voltage on the high voltage side into the low voltage on the low voltage side, and charge the lithium battery pack.

[0059] In some embodiments, when the bidirectional DC conversion unit is in charging mode, the controller sends a second control signal according to the input signal of the resonant current acquisition unit. The resonant current acquisition unit is used to collect the signal of the resonant current and send an IReson signal to the controller. The controller receives the signal and determines whether the signal passes through zero. When the IReson signal passes through zero, it means that the waveform of the resonant current is positive, and the high-voltage side current flows through the MOS tube Q1 and the capacitor C9. The controller controls the MOS tube Q3 and the MOS tube Q6 to be turned on to realize the synchronous rectification of the low-voltage side of the bidirectional DC conversion unit. When the IReson signal When it does not pass through zero, it means that the waveform of the resonant current is negative, and the high-voltage side current flows through the MOS tube Q2 and the capacitor C8. The controller controls the MOS tube Q4 and the MOS tube Q5 to be turned on, so as to realize the synchronous rectification of the low-voltage side of the bidirectional DC conversion unit. That is, when the bidirectional DC conversion unit is in the charging mode, the MOS tube Q1 and the MOS tube Q2 work in the active resonance mode, and the MOS tubes Q3 to Q6 work in the synchronous rectification mode. The controller reads the numerical values ​​of the battery side voltage signal VSec and the current signal ISec to perform closed-loop control, which is reflected in the control of the battery logic to maintain the CC constant current mode and the CV constant voltage mode.

[0060] In some embodiments, when the bidirectional DC conversion unit is in the discharge mode, the controller sends a third control signal according to the input signal of the resonant current acquisition unit. When the input signal, i.e., the IReson signal, passes through zero, it indicates that the waveform of the resonant current is positive, and the low-voltage side current flows through the MOS tube Q3 and the MOS tube Q6. The controller controls the MOS tube Q1 to be turned on to realize the synchronous rectification of the high-voltage side of the bidirectional DC conversion unit. When the IReson signal does not pass through zero, it indicates that the waveform of the resonant current is negative, and the low-voltage side current flows through the MOS tube Q4 and the MOS tube Q5. The controller controls the MOS tube Q2 to be turned on to realize the synchronous rectification of the high-voltage side of the bidirectional DC conversion unit. That is, when the bidirectional DC conversion unit is in the discharge mode, the MOS tubes Q3 to Q6 work in the active resonance mode, and the MOS tubes Q1 and the MOS tube Q2 work in the synchronous rectification mode. The controller performs closed-loop control by reading the high-voltage side voltage signal Vprim and the current signal Iprim.

[0061] In the embodiment of the present application, the lithium battery pack is 48V, and the input and output ports on the high-voltage side are 800VDC, so the winding ratio of the transformer circuit is set to 10:1. The specific reason is: the normal voltage of the lithium battery pack is 48V, the voltage in the empty state is 42.5V, and the voltage in the fully charged state is 52.5V. Since the high-voltage side of the bidirectional DC conversion unit is a half-bridge design, the transformer circuit is a bidirectional transformer between 400V and 48V. For the discharge mode, that is, the direction of converting 48V to 400V, it must be considered that the minimum voltage of 42.5V can also generate 400VDC, then the transformer ratio is 400 / 42.5=9.5, therefore, the winding ratio of the transformer circuit is set to 9.5:1. However, for the charging mode, that is, the direction of converting 400V to 48V, since the step-up ratio is 9.5, the maximum output voltage of the primary coil on the high-voltage side to the secondary coil on the low-voltage side will be 400 / 9.5=42.1 (V), which cannot reach the minimum voltage of the lithium battery pack of 42.5V, and cannot cover the full voltage of the battery of 52.5V, and cannot realize the charging of the lithium battery pack. Therefore, in the present application, by sending a first control signal to the low-voltage side of the bidirectional DC conversion unit in the preset initial stage of charging, the controller controls the MOS tube Q4 and the MOS tube Q6 to be turned on, and the secondary coil on the low-voltage side forms a short-circuit state, and the primary coil on the high-voltage side also has a short-circuit current. Through the short-circuit current, the first resonant inductor Lr1 on the high-voltage side forms a voltage source, and the voltage source is superimposed on the port voltage, thereby increasing the output voltage on the high-voltage side, that is, increasing the input voltage on the low-voltage side, so that in the charging mode, the lithium battery pack can be charged normally.

[0062] In some embodiments, in order to improve the voltage stabilization function of the low-voltage side circuit, an electrolytic capacitor C11 is further provided, a first port of the electrolytic capacitor C11 is connected to the positive electrode of the lithium battery pack, and a second port of the electrolytic capacitor C11 is connected to the first port of the resistor R3.

[0063] In some embodiments, the power supply voltage conversion circuit further includes a filtering unit, a pre-charging unit and a voltage stabilizing unit, wherein the first port of the filtering unit is connected to the first port of the pre-charging unit, the second port of the pre-charging unit is connected to the first port of the voltage stabilizing unit, and the second port of the pre-charging unit is connected to the first port of the bidirectional DC conversion unit;

[0064] The second port of the filter unit is connected to the second port of the voltage stabilizing unit, and the second port of the filter unit is connected to the second port of the bidirectional direct current conversion unit.

[0065] Please refer to Figure 4 , Figure 4 A circuit diagram of the filter unit described in an embodiment of the present application is shown, the filter unit includes a differential mode filter circuit and a common mode filter circuit, the differential mode filter circuit includes inductors L2, L3 and capacitors C1, C2, the common mode filter circuit includes inductors L1, capacitors C3, C4, C5, C6, the differential mode filter circuit and the common mode filter circuit are connected in series, the filter unit can use an EMI filter, the EMI filter is set at the power supply line of the device, because the power line is the main way for interference to enter and exit the device, through the power line, the interference of the power grid can be transmitted to the device, interfering with the normal operation of the device, and the interference generated by the device may also be transmitted to the power grid through the power line, interfering with the normal operation of other devices. Therefore, the present application sets an EMI filter at the output port to allow the frequency signal of the device to pass smoothly when the device is working normally, and has a suppressive effect on the interference signal with a high frequency higher than the high frequency when the device is working normally.

[0066] Please refer to Figure 5 , Figure 5A circuit diagram of the pre-charging unit and the voltage stabilizing unit described in an embodiment of the present application is shown, the pre-charging unit includes a pre-charging resistor R1 and a switch Relay, the voltage stabilizing unit includes an electrolytic capacitor C7, a first port of the pre-charging resistor R1 is connected to the output port of the inductor L2, a second port of the pre-charging resistor R1 is connected to the first port of the electrolytic capacitor C7, the second port of the pre-charging resistor R1 is connected to the drain of the MOS tube Q1, the switch Relay is connected in parallel with the pre-charging resistor R1, a controller is connected to the switch Relay and is used to control the opening and closing of the switch Relay, a first port of the inductor L3 is connected to the first port of the resistor R2, a second port of the resistor R2 is connected to the second port of the electrolytic capacitor C7, and the second port of the resistor R2 is connected to the source of the MOS tube Q2. By setting the resistor R2, the controller can obtain the current flowing through the resistor R2 according to the collected voltage of the resistor R2. The pre-charging unit is used to reduce the impact on the bus when power is on and prevent sparks when the 800V high-voltage port is energized. Specifically, when the 800V high-voltage port is energized, the contacts of the switch Relay1 are in a disconnected state, and the pre-charging unit pre-charges the electrolytic capacitor C7. Under the action of the pre-charging resistor R1, the access port will not spark, thereby reducing the impact on the bus when power is on. After the pre-charging time reaches the preset time of the controller, the controller controls the contacts of the switch Relay1 to close, short-circuiting the pre-charging resistor R1, and preparing conditions for subsequent normal operation.

[0067] In some embodiments, please refer to Figure 4 The input end of the filter unit is connected to a connector P1, and the filter unit is connected to the 800V DC bus through the connector P1.

[0068] In some embodiments, the positive terminal of the connector P1 is provided with a fuse F1, which is used for overcurrent protection of the circuit. Specifically, the first terminal of the fuse F1 is connected to the positive terminal of the connector, and the second terminal of the fuse F1 is connected to the first terminal of the capacitor C1.

[0069] In some embodiments, the power supply voltage conversion circuit further includes a first auxiliary power supply and a second auxiliary power supply;

[0070] The first auxiliary power supply is connected to the high voltage side of the bidirectional DC conversion unit, the second auxiliary power supply is connected to the low voltage side of the bidirectional DC conversion unit, the output end of the first auxiliary power supply is connected to the input end of the second auxiliary power supply, and the first auxiliary power supply and the second auxiliary power supply are both connected to the controller.

[0071] In some embodiments, the first auxiliary power supply and the second auxiliary power supply are interconnected through windings. When 800VDC is in place, the first auxiliary power supply draws power from the 800VDC side. Since the fully charged voltage of the lithium battery pack is 52.5V, the power supply voltage of the first auxiliary power supply is set to 52V. When the controller receives the power signal of the first auxiliary power supply, the drive circuit of the second auxiliary power supply is controlled to prohibit operation. At this time, the second auxiliary power supply is completely powered by the windings interconnected between the first auxiliary power supply and the second auxiliary power supply, and does not consume the power of the lithium battery pack. When 800VDC is not in place, the controller controls the drive circuit of the second auxiliary power supply to work, and the second auxiliary power supply draws power from the lithium battery pack side to generate a voltage of 52V, and supplies power to the first auxiliary power supply through the windings interconnected between the first auxiliary power supply and the second auxiliary power supply.

[0072] In addition, in some embodiments, the power supply voltage of the first auxiliary power supply may also be other values. When it is other values, the winding ratio between the first auxiliary power supply and the second auxiliary power supply needs to be adjusted accordingly so that the output voltage of the winding is 52V.

[0073] By setting up the first auxiliary power supply and the second auxiliary power supply, the second auxiliary power supply usually draws power from the first auxiliary power supply and supplies power to the controller and other peripheral circuits. When the 800VDC power is lost, the second auxiliary power supply will draw power from the lithium battery pack side, which is beneficial to saving battery power.

[0074] In some embodiments, the power supply voltage conversion circuit further includes a battery management module;

[0075] The first signal input terminal of the battery management module is connected to the lithium battery pack, and the second signal input terminal and the signal output terminal of the battery management module are both connected to the controller.

[0076] In some embodiments, the battery management module can be a BMS battery management system. Through the setting of the battery management module, it can read signals such as the voltage of a single battery cell and the temperature of the battery cell in the lithium battery pack in real time, and preliminarily calculate the real-time status parameters of the lithium battery pack, send the collected data and calculation results to the controller, and receive the output signal of the controller to control the on and off of the power supply circuit, thereby achieving coordinated work among the three.

[0077] In the embodiment of the present application, the power supply voltage conversion circuit further includes a communication module;

[0078] The communication module is electrically connected to the controller; the communication module is used to send a charging instruction or a discharging instruction to the controller, and is also used to realize communication between the controller and an external host computer.

[0079] In some embodiments, the communication module may be a CAN communication module, and the charging instruction may be a charging instruction sent to the controller through the CAN communication module when the external DC bus voltage is higher than a set value, or a charging instruction sent to the controller when the CAN communication module receives a manually triggered charging command. Before the charging instruction is sent, the system is placed in a discharge mode by default, and at the end of the charging mode, when the external DC bus voltage is lower than a set value, a discharge instruction is sent to the controller through the CAN communication module, or a discharge instruction is sent to the controller when the CAN communication module receives a manually triggered discharge command.

[0080] An embodiment of the present application also provides an 800V battery pack, including a power supply voltage conversion device, wherein the power supply voltage conversion circuit of the power supply voltage conversion device adopts the above-mentioned power supply voltage conversion circuit.

[0081] Those skilled in the art can clearly understand that, for the convenience and simplicity of description, the specific working process of the 800V battery pack described above can refer to the corresponding process in the method embodiment, and will not be repeated in this application. In the several embodiments provided in this application, it should be understood that the disclosed system and device can be implemented in other ways.

[0082] An embodiment of the present application also provides a stacked three-phase energy storage system, including a three-phase rectifier inverter module and multiple 800V battery packs, the three-phase rectifier inverter module and each 800V battery pack are respectively connected to a DC bus, and the 800V battery pack adopts the above-mentioned 800V battery pack.

[0083] Specifically, the positive port of the three-phase rectifier inverter module is connected to the positive pole of the DC bus, the negative port of the three-phase rectifier inverter module is connected to the negative pole of the DC bus, the positive port of the 800V battery pack is connected to the positive pole of the DC bus, and the negative port of the 800V battery pack is connected to the negative pole of the DC bus.

[0084] In some embodiments, the plurality of 800V battery packs may be 12 800V battery packs. Since a three-phase energy storage system with a power of not less than 30KW has a practical demand in the fields of industry, communication, medical treatment, etc. to prevent sudden power failure, under the premise of 30KW, since the power of a single battery pack is 3 kilowatts, that is, the AC-DC converter, 12 battery packs can fully ensure that the DC-AC converter operates at full power, and there is still margin.

[0085] In some embodiments, the battery packs communicate with each other, and the battery packs and the three-phase rectifier inverter module communicate with each other via a CAN bus.

[0086] In some embodiments, the controller in the three-phase rectifier inverter module calculates the power and current values ​​that each parallel battery pack should share by collecting the output power value, and transmits the evenly distributed current value to each battery pack through the interconnected CAN bus. Each parallel battery pack will also upload its own working status: battery voltage, battery current, voltage of each battery cell, battery cell temperature, radiator temperature of the bidirectional DC conversion unit in the battery pack, ambient temperature and other parameters to the controller in the three-phase rectifier inverter module.

[0087] In the embodiments provided in the present application, it should be understood that the disclosed methods and devices can be implemented in other ways. The device embodiments described above are merely schematic. For example, the division of the units is only a logical function division. There may be other division methods in actual implementation. For example, multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some communication interfaces, indirect coupling or communication connection of devices or units, which can be electrical, mechanical or other forms.

[0088] The units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed on multiple network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0089] In addition, each functional unit in the embodiments provided in the present application may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit.

[0090] It should be noted that similar numbers and letters represent similar items in the following figures. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures. In addition, the terms "first", "second", "third", etc. are only used to distinguish the description and are not to be understood as indicating or implying relative importance.

[0091] It should be noted that the term "comprising" used in the embodiments of the present application is used to indicate the existence of the features declared thereafter, but does not exclude the addition of other features.

[0092] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which this application belongs. The terms used herein are for the purpose of describing the embodiments of this application and are not intended to limit this application.

[0093] Finally, it should be noted that the above-described embodiments are only specific implementation methods of the present application, which are used to illustrate the technical solutions of the present application, rather than to limit them. The protection scope of the present application is not limited thereto. Although the present application is described in detail with reference to the above-mentioned embodiments, ordinary technicians in the field should understand that any technician familiar with the technical field can still modify the technical solutions recorded in the above-mentioned embodiments within the technical scope disclosed in the present application, or can easily think of changes, or make equivalent replacements for some of the technical features therein; and these modifications, changes or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application. They should all be included in the protection scope of the present application. Therefore, the protection scope of the present application shall be subject to the protection scope of the claims.

Claims

1. A power supply voltage conversion circuit, characterized in that: include: Bidirectional DC conversion unit, lithium battery pack and controller; The bidirectional DC conversion unit includes a high voltage side and a low voltage side; the high voltage side and the low voltage side of the bidirectional DC conversion unit are electrically connected to the controller respectively, and the low voltage side of the bidirectional DC conversion unit is electrically connected to the lithium battery pack; The bidirectional DC conversion unit is used to receive a first control signal sent by the controller in a preset initial stage of charging when the controller receives a charging instruction, and switch to a charging mode after the preset initial stage ends; The bidirectional DC conversion unit includes a transformer circuit and a resonant current collection unit; The resonant current collection unit is connected in series in the primary circuit of the transformer circuit, and the resonant current collection unit is electrically connected to the controller; The resonant current acquisition unit is used to acquire the resonant current signal of the transformer circuit after the preset initial stage ends and output the acquisition result to the controller, so that the controller sends a second control signal to the bidirectional DC conversion unit when the bidirectional DC conversion unit is in the charging mode.

2. The power supply voltage conversion circuit according to claim 1, characterized in that: The bidirectional DC conversion unit includes a half-bridge circuit on the high voltage side and a full-bridge circuit on the low voltage side; The bidirectional DC conversion unit is used to control the full-bridge circuit to be in a short-circuit state when receiving the first control signal output by the controller.

3. The power supply voltage conversion circuit according to claim 2, characterized in that: The transformer circuit includes a primary coil, a secondary coil, a first resonant inductor and a second resonant inductor; The first resonant inductor is connected in series with the primary coil, and the second resonant inductor is connected in series with the secondary coil; The first resonant inductor is used to receive the energy storage signal output by the half-bridge circuit on the high-voltage side and store energy to form an energy storage voltage source when the first control signal output by the controller controls the full-bridge circuit to be in a short-circuit state.

4. The power supply voltage conversion circuit according to claim 1, characterized in that: It also includes a filtering unit, a pre-charging unit and a voltage stabilizing unit, wherein the first port of the filtering unit is connected to the first port of the pre-charging unit, the second port of the pre-charging unit is connected to the first port of the voltage stabilizing unit, and the second port of the pre-charging unit is connected to the first port of the bidirectional DC conversion unit; The second port of the filter unit is connected to the second port of the voltage stabilizing unit, and the second port of the filter unit is connected to the second port of the bidirectional direct current conversion unit.

5. The power supply voltage conversion circuit according to claim 4, characterized in that: The input end of the filter unit is connected with a connector, and the filter unit is connected to the 800V DC bus through the connector.

6. The power supply voltage conversion circuit according to claim 5, characterized in that: The positive terminal of the connector is provided with a fuse, and the fuse is used for overcurrent fusing protection of the circuit.

7. The power supply voltage conversion circuit according to claim 1, characterized in that: Also includes a first auxiliary power supply and a second auxiliary power supply; The first auxiliary power supply is connected to the high voltage side of the bidirectional DC conversion unit, the second auxiliary power supply is connected to the low voltage side of the bidirectional DC conversion unit, the output end of the first auxiliary power supply is connected to the input end of the second auxiliary power supply, and the first auxiliary power supply and the second auxiliary power supply are both connected to the controller.

8. The power supply voltage conversion circuit according to claim 1, characterized in that: Also includes a battery management module; The first signal input terminal of the battery management module is connected to the lithium battery pack, and the second signal input terminal and the signal output terminal of the battery management module are both connected to the controller.

9. The power supply voltage conversion circuit according to claim 1, characterized in that: Also includes a communication module; The communication module is electrically connected to the controller; the communication module is used to send a charging instruction or a discharging instruction to the controller, and is also used to realize communication between the controller and an external host computer.

10. An 800V battery pack, characterized in that: It comprises a power supply voltage conversion device, wherein the power supply voltage conversion circuit of the power supply voltage conversion device adopts the power supply voltage conversion circuit according to any one of claims 1-9.

11. A stacked three-phase energy storage system, characterized in that: It comprises a three-phase rectifier inverter module and a plurality of 800V battery packs, wherein the three-phase rectifier inverter module and each 800V battery pack are respectively connected to a DC bus, and the 800V battery pack adopts the 800V battery pack described in claim 10.

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