Power supply circuit, energy storage converter and energy storage system

Abstract

The utility model provides a power supply circuit, an energy storage converter and an energy storage system. The power supply circuit comprises a direct-current power supply module, the direct-current power supply module comprises a step-down switch circuit and a transformer control circuit, the step-down switch circuit comprises a starting circuit and a transformer control circuit, and the starting circuit receives direct-current input voltage and outputs driving voltage to the transformer control circuit; the output end of the step-down switching circuit is connected to one side of the transformer, and the transformer control circuit is connected to the transformer; a DC output circuit connected to the other side of the transformer and outputting a first DC output voltage; the threshold switching circuit comprises a first threshold switching circuit connected to the starting circuit, the first threshold switching circuit changes starting resistance of the starting circuit through switching operation, and the starting circuit is connected to the circuit in the first switching state and the second switching state of the first threshold switching circuit.

Description

Technical Field

[0001] The present disclosure relates to the field of energy storage, and in particular to a power supply circuit, an energy storage converter, and an energy storage system. Background Art

[0002] Against the backdrop of the "dual carbon" goals, energy storage technology has become an indispensable component of the new power system. As a key device connecting batteries and the grid, the PCS (power storage converter) enables bidirectional energy flow, supporting various application scenarios such as grid-connected operation and frequency regulation.

[0003] To ensure stable PCS operation, an uninterruptible power supply (UPS) is crucial, especially during power grid outages to ensure continuous system operation. Currently, there are two primary PCS power supply solutions: one based on a combination of an AC grid and an uninterruptible power supply (UPS), relying on the UPS for power during a grid outage; the other using DC batteries instead of traditional UPSs, creating a model where both the AC grid and the DC battery provide power. The latter is becoming the industry's preferred solution due to its higher integration and cost-effectiveness. However, this solution also faces technical challenges in improving battery efficiency, reducing power consumption, and enhancing power supply reliability.

[0004] As energy storage systems evolve toward higher voltages, the DC bus voltage has increased from the early 600V to the now-commonly used 1500V. While this change improves overall system performance, it also introduces new challenges to the design of DC power modules.

[0005] Current technological limitations make it difficult for these modules to adapt to a wide input voltage range. In extreme cases, even if the battery still has enough power to support startup, the system may fail due to the power module not working properly. Utility Model Content

[0006] One of the objectives of the present disclosure is to provide a power supply circuit that can adapt to a wide input voltage range.

[0007] The power supply circuit disclosed herein can enable the DC power supply module to start and provide the starting voltage required by the PCS even when the voltage of the energy storage battery is low, thereby realizing low-power emergency starting of the energy storage system.

[0008] According to one aspect of the present disclosure, a power supply circuit of an energy storage system may include a DC power supply module, which includes: a step-down switching circuit, including a starting circuit and a transformer control circuit, the starting circuit receives a DC input voltage and outputs a driving voltage to the transformer control circuit; a transformer, the output end of the step-down switching circuit is connected to one side of the transformer, and the transformer control circuit is connected to the transformer; a DC output circuit, connected to the other side of the transformer and outputting a first DC output voltage; a threshold switching circuit, including a first threshold switching circuit connected to the starting circuit, the first threshold switching circuit changing the starting resistance of the starting circuit through a switching operation, wherein the starting circuit is connected to the circuit in both the on state and the off state of the first threshold switching circuit.

[0009] Optionally, the starting circuit may include: a charging capacitor connected to the transformer control circuit; and a starting resistance circuit connected in series with the charging capacitor.

[0010] Optionally, the startup resistor circuit may include a first startup resistor and a second startup resistor connected in series with each other, and the first threshold switching circuit is connected in parallel with the first startup resistor or the second startup resistor.

[0011] Optionally, the starting resistor circuit may include a first starting resistor and a second starting resistor connected in parallel with each other, and the first threshold switching circuit is connected in series with the third starting resistor and then connected in parallel with the first starting resistor or the second starting resistor.

[0012] Optionally, the step-down switching circuit may further include an input undervoltage protection circuit, which receives a DC input voltage, and the threshold switching circuit further includes a second threshold switching circuit connected to the input undervoltage protection circuit, wherein the input undervoltage protection circuit stops working in response to the DC input voltage being less than the first threshold when the second threshold switching circuit is in the first state, and stops working in response to the DC input voltage being less than the second threshold when the second threshold switching circuit is in the second state.

[0013] Optionally, the second threshold switching circuit may be connected to the voltage-dividing resistor circuit of the input undervoltage protection circuit to adjust the resistance of the voltage-dividing resistor circuit.

[0014] Alternatively, the voltage-dividing resistor circuit may include a first voltage-dividing resistor and a second voltage-dividing resistor connected in series or in parallel with each other, and the second threshold switching circuit is connected in parallel to the first voltage-dividing resistor or the second voltage-dividing resistor.

[0015] Optionally, the input undervoltage protection circuit may further include a comparator, wherein the positive input of the comparator is connected to the voltage divider resistor circuit, the reverse input of the comparator receives a reference voltage, and the output of the comparator is connected to the PWM controller in the transformer control circuit via a reverse diode.

[0016] Optionally, the first threshold switching circuit may include a controllable switch and a driver thereof, wherein the driver is used to control the closing or opening of the controllable switch.

[0017] Optionally, the power supply circuit may also include: an AC power supply module, the AC power supply module receives an AC input voltage and outputs a second DC output voltage different from the first DC output voltage, a DC-DC conversion circuit, the first DC output voltage and the second DC output voltage are respectively input into the DC-DC conversion circuit via a first forward diode and a second forward diode, and the DC-DC conversion circuit outputs a power supply voltage.

[0018] According to a second aspect of the present disclosure, an energy storage converter is provided, which includes the above-mentioned power supply circuit.

[0019] According to a third aspect of the present disclosure, an energy storage system is provided, which includes the above-mentioned energy storage converter.

[0020] The power supply circuit disclosed herein reduces the input-output voltage difference of the DC power supply module through a lower input voltage, thereby reducing battery loss, improving power efficiency, and making full use of the remaining power of the energy storage battery.

[0021] The power supply circuit disclosed in the present invention can make the PCS compatible with low-rated voltage energy storage batteries that have grid-connected charging and discharging conditions, thereby enhancing the versatility and compatibility of the PCS power supply system. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Other features, objects and advantages of the present application will become more apparent from the detailed description of non-limiting embodiments made with reference to the following drawings.

[0023] Figure 1 is a circuit diagram of a power supply circuit of an energy storage system according to an embodiment of the present disclosure;

[0024] Figure 2 is a circuit diagram of a buck switching circuit according to a first embodiment of the present disclosure;

[0025] Figure 3 is a circuit diagram of a buck switching circuit according to a second embodiment of the present disclosure;

[0026] Figure 4 is a circuit diagram of a buck switching circuit according to a third embodiment of the present disclosure;

[0027] Figure 5 is a circuit diagram of a starting resistor circuit according to a first embodiment of the present disclosure;

[0028] Figure 6 is a circuit diagram of a startup resistor circuit according to a second embodiment of the present disclosure;

[0029] Figure 7 is a circuit diagram of a startup resistor circuit according to a third embodiment of the present disclosure. DETAILED DESCRIPTION

[0030] The following detailed description is provided to assist in gaining a comprehensive understanding of the methods, apparatuses, and / or systems described herein. However, the order of operations described herein is merely exemplary and is not limited to the order set forth herein. Equivalent substitutions or variations are possible, except for operations that must occur or be performed in a specific order. Furthermore, for the sake of clarity and conciseness, descriptions of matters known in the art may be omitted or simplified.

[0031] Unless otherwise defined, all terms used herein (including technical and scientific terms) have the same meaning as commonly understood by one of ordinary skill in the art to which the present disclosure pertains after understanding the present disclosure. Unless expressly defined otherwise herein, terms (such as those defined in general dictionaries) should be interpreted as having a meaning consistent with their meaning in the context of the relevant art and the present disclosure, and should not be interpreted in an idealized or overly formal manner.

[0032] Unless otherwise specified, the same reference numerals generally refer to the same elements (e.g., parts, steps, and methods). Reference numerals described in the previous embodiment may be omitted if they appear again in the subsequent embodiment. In addition, the technical features described in different or the same embodiment may be combined in any manner, as long as the combined embodiment or technical solution is complete and can solve the technical problems of the present application or achieve the technical effects described or not described in this disclosure but can be determined based on the above complete technical solution. It should be noted that, in the absence of conflicts between the various embodiments, these embodiments and their features can be combined with each other. Those skilled in the art can clearly understand that, for the convenience and brevity of description, the specific working process and related instructions of the system described above can refer to the corresponding process in the aforementioned method embodiment, and will not be repeated here.

[0033] The present disclosure connects a threshold switching circuit (e.g., a low-voltage startup switch assembly) to the input circuit of a DC power supply module (i.e., a switching power supply) in the power supply circuit of an energy storage system. This threshold switching circuit is capable of adjusting the startup voltage of the switching power supply circuit. As an example, this threshold switching circuit can be deployed in the input voltage protection circuit and / or the startup circuit of the switching power supply. This is described in detail below in conjunction with the accompanying drawings of the present disclosure.

[0034] Figure 1 is a circuit diagram of a power supply circuit of an energy storage system according to an embodiment of the present disclosure, Figure 2 is a circuit diagram of a buck switching circuit according to a first embodiment of the present disclosure, Figure 3is a circuit diagram of a buck switching circuit according to a second embodiment of the present disclosure, Figure 4 is a circuit diagram of a step-down switching circuit according to a third embodiment of the present disclosure.

[0035] The power supply circuit of the energy storage system of the present disclosure includes a DC power supply module 10 and may further include an AC power supply module 20. Both the DC power supply module 10 and the AC power supply module 20 can supply power to electrical devices in the PCS of the energy storage system.

[0036] The DC power supply module 10 of the present disclosure may be a switching power supply circuit including a DC-DC conversion circuit. The DC power supply module 10 may receive a DC input voltage DC IN And can output DC output voltage V DC1 .

[0037] The AC power module 20 of the present disclosure can receive an AC voltage AC IN And output DC voltage V DC2 .

[0038] Although not shown, the AC power supply module 20 may include a step-down rectifier circuit, the configuration of which is not particularly limited. For example, the step-down rectifier circuit may reduce a higher input AC voltage to a lower AC voltage suitable for processing by a subsequent rectifier circuit. The lower AC voltage may then be converted to a DC voltage via a bridge rectifier circuit. For example, the step-down rectifier circuit may also include a filter circuit, etc.

[0039] The AC power module 20 and the DC power module 10 of the present disclosure can share the second DC-DC conversion circuit 30, and the output voltage V OUT May be provided to the control circuitry of the energy storage system.

[0040] As an example, the input end of the AC power module can be connected to the AC grid side of the energy storage inverter to draw power from the AC grid, and the input end of the DC power module can be connected to the DC battery side of the energy storage inverter to draw power from the energy storage battery.

[0041] Reference Figure 1 , the input voltage DC of the DC power supply module 10 IN After DC-DC switching conversion, a first DC output voltage V DC1 The input voltage AC of the AC power module 20 is IN The second DC output voltage V can be generated after the step-down rectifier circuit steps down and rectifies DC2 That is, the AC power module 20 can receive the AC input voltage AC IN And output the first DC output voltage V DC1 Different second DC output voltage V DC2, the first DC output voltage V DC1 and the second DC output voltage V DC2 The power is input to the second DC-DC conversion circuit 30 through the first forward diode D1 and the second forward diode D2 respectively, and the second DC-DC conversion circuit 30 outputs the power supply voltage V OUT .

[0042] When the grid voltage is normal, the AC power module 20 serves as a power supplier, and the DC power module serves as a backup or auxiliary power source.

[0043] When the power grid is operating normally, the AC power supply module 20 takes power from the power grid first, and converts the AC power of the power grid into DC power suitable for use by the energy storage system through a step-down rectifier circuit, and then further converts it into a suitable voltage level through a DC-DC circuit for use by the system.

[0044] Specifically, when the grid voltage is normal, the second DC output voltage V DC2 Greater than the first DC output voltage V DC1 , the second forward diode D2 is turned on, the first forward diode D1 is turned off, the AC power supply module 20 is connected to the circuit, and the system is powered by the grid-side AC power supply.

[0045] When the grid voltage fails, the second DC output voltage V DC2 Less than the first DC output voltage V DC1 , the first forward diode D1 is turned on, the second forward diode D2 is turned off, the DC power supply module is connected to the circuit, and the system is powered by the DC side energy storage battery.

[0046] When the system is powered by a DC side energy storage battery, the threshold switching circuit can be used to control the controlled components or controlled unit circuits at the power input end to short-circuit or open-circuit, thereby temporarily reducing the input startup voltage threshold of the step-down switch circuit within a certain range, so that the DC power supply module can start and output the first DC output voltage V when the input voltage is lower than the normal input voltage. DC1 , realizing low-power startup of the energy storage system.

[0047] It should be noted that the first forward diode D1 can be part of the DC power module, and the second forward diode D2 can be part of the AC power module. The second DC-DC conversion circuit 30 can be a common part of the DC power module and the AC power module, or it can be an independent part.

[0048] Reference Figure 1 The DC power supply module 10 may include a step-down switching circuit 11, a transformer 14, a DC output circuit 15, and a threshold switching circuit 12 (ie, a low-voltage starting switch component).

[0049] Reference Figure 2The input end of the step-down switch circuit 11 can receive a DC input voltage DC IN The output end of the step-down switching circuit 11 can be connected to one side (primary side) of the transformer 14 , and the step-down switching circuit 11 may include a transformer control circuit 112 , and may also include at least one of an input undervoltage protection circuit 111 and a startup circuit 113 .

[0050] The input undervoltage protection circuit 111 can receive a DC input voltage DC IN The input undervoltage protection circuit 111 is mainly used to prevent the DC power supply module in the energy storage system from starting when the input voltage is too low, thereby avoiding equipment damage or abnormal operation due to insufficient input voltage.

[0051] When the voltage of the energy storage battery is lower than the voltage threshold required for normal startup, the input undervoltage protection circuit will prevent the system from starting. This can protect the battery from being damaged by excessive discharge and ensure that the system starts only when the input voltage is sufficient to maintain normal system operation.

[0052] Reference Figure 2 The transformer control circuit 112 may be used to control the efficient operation of the transformer 14 , and the structure of the transformer control circuit 112 is not specifically limited.

[0053] The transformer control circuit 112 may include a PWM controller IC1, a switch Q1, and a bias resistor R CS The output terminal OUT of the PWM controller IC1 can be connected to the controlled terminal of the switch Q1, the COMP terminal of the PWM controller IC1 can be connected to the output terminal of the comparator IC2 through a diode, the VCC terminal of the PWM controller IC1 can be connected to the startup circuit 113, the GND terminal of the PWM controller IC1 can be grounded, the first terminal of the switch Q1 can be connected to one side (primary side) of the transformer 14, and the second terminal of the switch Q1 can be connected to the bias resistor R CS The switch Q1 may be a MOSFET, however, this is merely an example, and the switch Q1 may also be implemented by an IGBT or the like.

[0054] As an example, the output end of the step-down switching circuit 11 is connected to one side of the transformer 14, and the transformer control circuit 112 is connected to the transformer 14. The DC output circuit 15 is connected to the other side (secondary side) of the transformer 14 and outputs a first DC output voltage V DC1 The DC output circuit 15 may be part of a DC-DC conversion circuit. The DC output circuit 15 further processes the stepped-down voltage through transformer coupling to enable it to meet the standard DC voltage output required for PCS operation.

[0055] The threshold switching circuit 12 may include a first threshold switching circuit connected to the input undervoltage protection circuit. The threshold switching circuit 12 may be composed of one or more controllable switches and their drivers. The controlled component at the input end of the DC power supply module (for example, the voltage divider resistor in the input voltage protection circuit) may be composed of one or more controlled components or controlled unit circuits. The threshold switching circuit 12 can control the switch to be connected to the controlled component or controlled unit circuit, thereby causing the controlled component or controlled unit circuit to be short-circuited or open-circuited.

[0056] The controlled component or controlled unit here can be a resistor, a capacitor, an inductor or a combination thereof, and the resistor, capacitor, inductor or a combination thereof here can be part of the input voltage protection circuit and / or the startup circuit ( Figure 2 A portion of the startup circuit 113 shown.

[0057] The threshold switching circuit 12 may include a controllable switch and a driver thereof. The driver of the controllable switch may be a mechanical control method or an electronic control method. The electronic control method may be a local wired signal control method or a remote wireless signal control method. As an example, the threshold switching circuit may be a mechanical switch of a single-pole single-throw, a single-pole multiple-throw, or a multiple-pole multiple-throw type, or a relay switch. When the threshold switching circuit is implemented by electronic control, the step-down switching circuit may further include a first switch control circuit. The first switch control circuit may control the switch state in the first threshold switching circuit. For example, the first switch control circuit controls the first threshold switching circuit to switch from a first state (disconnected state) to a second state (closed state) in response to a DC input voltage being less than a second threshold. The first switch control circuit controls the first threshold switching circuit to switch from a second state (closed state) to a first state (disconnected state) in response to a DC input voltage being greater than or equal to the second threshold.

[0058] When the threshold switching circuit is in the first state (eg, the disconnected state), the input undervoltage protection circuit can respond to the DC input voltage DC IN When the DC input voltage is lower than the first threshold, the transformer control circuit stops operating. For example, the input undervoltage protection circuit can generate a protection voltage to prevent system instability or device damage caused by excessively low input voltage. When the DC input voltage is lower than the threshold voltage, the input undervoltage protection circuit can output the protection voltage, and the transformer control circuit 112 or the transformer 14, etc., stops operating in response to the protection voltage.

[0059] When the threshold switching circuit is in the second state (eg, closed state), the input undervoltage protection circuit responds to the DC input voltage DC INWhen the voltage is less than the second threshold, the transformer control circuit stops operating, wherein the second threshold is less than the first threshold. In other words, by controlling the threshold switching circuit 12 to temporarily lower the input startup voltage threshold of the step-down switching circuit within a certain range, the DC power supply module can start up at a voltage lower than the normal input voltage and output the required DC voltage, thereby achieving low-power startup of the energy storage system.

[0060] In addition, the power supply circuit disclosed in the present invention reduces the input-output voltage difference of the DC power supply module through a lower input voltage, thereby reducing the loss of the energy storage battery, improving power supply efficiency, and making full use of the remaining power of the energy storage battery.

[0061] As described above, the threshold switching circuit disclosed herein can be deployed in both the input voltage protection circuit and the startup circuit. Figure 2 As shown, the threshold switching circuit 12 is deployed in the input undervoltage protection circuit 111. The threshold switching circuit 12 can also be deployed on the starting circuit 113, so as to change the starting resistance of the starting circuit 113. The starting circuit in the switching power supply is used to provide the necessary starting current to the control chip (for example, PWM control chip) in the switching power supply at the moment the power is turned on, so that it can start working. Although not shown, the starting circuit 113 can also include other components to achieve current limiting, voltage monitoring, soft start function, etc., which will be described in detail later.

[0062] Input undervoltage protection circuit 111 may include a voltage-dividing resistor circuit, which is a resistor network, and may also include a comparator IC2. The positive input of comparator IC2 is connected to the voltage-dividing resistor circuit, the negative input of the comparator receives a reference voltage, and the output of comparator IC2 is connected to PWM controller IC1 in transformer control circuit 112 via a reverse diode. Comparator IC2 may be a hysteresis comparator.

[0063] The voltage divider resistor circuit may include a first voltage divider resistor and a second voltage divider resistor connected in series or in parallel with each other, and the first threshold switching circuit is connected in parallel to the first voltage divider resistor or the second voltage divider resistor. The first threshold switching circuit may be connected to the voltage divider resistor circuit of the input undervoltage protection circuit to adjust the resistance of the voltage divider resistor circuit. As an example, when the input voltage DC IN When the voltage becomes smaller, if there is no threshold switching circuit, the voltage received by the positive input terminal of the comparator IC2 becomes smaller, the COMP terminal of the PWM controller IC1 is forced to be pulled low, and the DC power supply module stops supplying power. However, due to the deployment of the first threshold switching circuit, the first threshold switching circuit changes from open to closed, so that the voltage received by the positive input terminal of the comparator IC2 can remain basically unchanged, and the DC power supply module can supply power normally, thereby achieving a lower starting voltage.

[0064] Reference Figure 2The voltage dividing resistor circuit may include a first voltage dividing resistor Rb, a second voltage dividing resistor Rt2 and a third voltage dividing resistor Rt1 connected in series. When the DC voltage DC IN When the voltage input to the positive input terminal of the comparator IC2 after passing through the voltage divider resistor is lower than the negative input reference voltage Vref (i.e., the reference voltage), the hysteresis comparator output is low, the level of the compensation pin COMP of the PWM controller IC1 is forced to be pulled low, the PWM controller IC1 has no output signal, the PWM controller IC1 does not work, and the entire buck switch circuit does not work; when the input DC voltage DC IN When the positive input voltage of comparator IC2, after passing through the resistor divider, exceeds the negative input reference voltage Vref, the hysteresis comparator output opens, and PWM controller IC1 operates normally. Therefore, the parameters of the voltage divider circuit determine the startup voltage threshold for normal operation of the buck switching circuit.

[0065] Reference Figure 2 , the threshold switching circuit (for example, the first threshold switching circuit) can be connected to both ends of the second voltage-dividing resistor Rt2. Therefore, the controllable switch of the first threshold switching circuit can control whether the second voltage-dividing resistor Rt2 is connected to the circuit. When the controllable switch of the first threshold switching circuit is disconnected, the second voltage-dividing resistor Rt2 is normally connected to the circuit. The input turn-on threshold voltage of the step-down switch circuit is DC IN(ON1) When the controllable switch of the threshold switching circuit is closed, the second voltage divider resistor Rt2 is short-circuited, the positive input voltage of the comparator IC2 increases, and the input turn-on threshold voltage of the step-down switching circuit will be reduced from DC IN(ON1) Reduce to DC IN(ON2) , so that the effective working voltage of the input changes from DC IN(ON1) Reduce to DC IN(ON2) , thereby, the voltage input range of the DC power module can be expanded, and a lower energy storage battery voltage can be used to drive the DC power module to normally output the PCS working voltage V OUT .

[0066] As described above, the threshold switching circuit of the present disclosure may be deployed in an input voltage protection circuit and / or a startup circuit.

[0067] Reference Figure 3 , according to the second embodiment of the present disclosure, the buck switching circuit and Figure 2 The difference of the buck switch circuit shown is that, in addition to the input undervoltage protection circuit 111 , the threshold switching circuit of the present disclosure can also be deployed in the startup circuit 113 .

[0068] Reference Figure 3 The step-down switch circuit of the second embodiment of the present disclosure may further include a startup circuit 113, which may receive a DC input voltage DC INAnd outputs the driving voltage to the transformer control circuit 112.

[0069] Reference Figure 3 The starting circuit 113 may include a charging capacitor Cvcc and a starting resistance circuit, the two ends of the charging capacitor Cvcc may be connected to the VCC terminal and the GND terminal of the transformer control circuit, and the starting resistance circuit may be connected in series with the charging capacitor Cvcc.

[0070] As an example, the startup circuit 113 may further include a diode Dz connected in parallel with the charging capacitor Cvcc. The diode Dz may be a voltage-stabilizing diode. The voltage-stabilizing diode Dz may be used for voltage clamping to prevent overvoltage from damaging the switch PWM controller IC1.

[0071] As an example, the threshold switching circuit 12 may further include a second threshold switching circuit connected to the startup resistance circuit, and the resistance of the startup resistance circuit may be changed by switching the state of the second threshold switching circuit.

[0072] As an example, the startup resistor circuit may include a first startup resistor and a second startup resistor connected in series with each other, and the second threshold switching circuit may be connected in parallel with the first startup resistor or the second startup resistor.

[0073] Reference Figure 3 The starting resistor circuit may include a first starting resistor Rstart1 and a second starting resistor Rstart2 connected in series with each other, and the second threshold switching circuit may be connected in parallel with the second starting resistor Rstart2.

[0074] As an example, the startup resistor circuit may include a first startup resistor and a second startup resistor connected in parallel with each other, and the second threshold switching circuit is connected in series with the third startup resistor and then connected in parallel with the first startup resistor or the second startup resistor.

[0075] Although not shown, the step-down switching circuit 11 may further include a second switch control circuit, which may control the state switching of the second threshold switching circuit in response to the DC input voltage being less than the second threshold. For example, the second switch control circuit may control the second threshold switching circuit to switch from an open state to a closed state in response to the DC input voltage being less than the second threshold, thereby short-circuiting the second starting resistor Rstart2. The first switch control circuit and the second switch control circuit may be part of the energy storage controller or may be circuits implemented separately. The comparison between the DC input voltage and the first threshold and the comparison between the DC input voltage and the second threshold may be performed by the energy storage controller, but this is merely an example. The first switch control circuit and the second switch control circuit may both include a PWM controller, which may be part of the energy storage controller.

[0076] Reference Figure 3, input DC voltage IN The capacitor Cvcc is charged through the first startup resistor Rstart1 and the second startup resistor Rstart2. When the voltage of the capacitor Cvcc rises to the power supply startup voltage threshold of the PWM controller IC1, the PWM controller IC1 starts to work and outputs the PWM control signal. The transformer control circuit and other circuits operate normally. The voltage regulator diode Dz is used to prevent overvoltage from damaging the PWM controller IC1. The total resistance of the series connection of the startup resistors Rstart1 and Rstart2 determines the voltage across the capacitor Cvcc.

[0077] When the second threshold switching circuit (low-voltage starting switch component) of the present invention is deployed on the starting circuit, the controllable switch of the second threshold switching circuit is connected to the two ends of the second starting resistor Rstart2 of the step-down switching circuit. The second threshold switching circuit can control whether the second starting resistor Rstart2 is connected to the step-down switching circuit. When the second threshold switching circuit is disconnected, the second starting resistor Rstart2 is normally connected to the step-down switching circuit. The input start-up threshold voltage of the step-down switching circuit is DC IN(ON1) When the second threshold switching circuit is closed, the second starting resistor Rstart2 is short-circuited, the total resistance of the first starting resistor Rstart1 and the second starting resistor Rstart2 in series decreases, the charging current of the capacitor Cvcc increases, and the input turn-on threshold voltage of the step-down switch circuit will decrease from DC IN(ON1) Reduce to DC IN(ON2) , so that the effective working voltage of the input terminal changes from DC IN(ON1) Reduce to DC IN(ON2) , the voltage input range of the DC power module is expanded, and a lower energy storage battery voltage can be used to drive the DC power module to normally output the PCS working voltage V OUT .

[0078] Reference Figure 3 The threshold switching circuit disclosed in the present invention is deployed in both the startup circuit and the input undervoltage protection circuit. The two controllable switches of the threshold switching circuit can be connected to the two ends of the second startup resistor Rstart2 and the second voltage divider resistor Rt2 respectively. The controllable switches can control whether the second startup resistor Rstart2 and the second voltage divider resistor Rt2 are connected to the step-down switch circuit. When the two controllable switches of the threshold switching circuit are both disconnected, the second startup resistor Rstart2 and the second voltage divider resistor Rt2 are normally connected to the step-down switch circuit. The input start-up threshold voltage of the step-down switch circuit is DC IN(ON1) When both controllable switches of the threshold switching circuit are closed, the second starting resistor Rstart2 and the second voltage divider resistor Rt2 are short-circuited, and the input turn-on threshold voltage of the step-down switching circuit will be DC IN(ON1) Reduce to DC IN(ON2), so that the effective working voltage of the input terminal changes from DC IN(ON1) Reduce to DC IN(ON2) , the voltage input range of the DC power module is expanded, so that a lower energy storage battery voltage can be used to drive the DC power module to normally output the PCS working voltage V OUT .

[0079] In other words, the input turn-on threshold voltage DC IN(ON1) For normal operation of PCS, there is no undervoltage at the input end, and the voltage and capacity of the energy storage battery fully meet the grid-connected charging and discharging conditions. Input turn-on threshold voltage DC IN(ON2) Used for PCS off-grid standby and low-capacity emergency black start conditions. The voltage and capacity of the energy storage battery cannot fully meet the grid-connected charging and discharging conditions, but the remaining capacity of the battery is still within the usable range. The battery voltage has not yet dropped to a high fault level undervoltage alarm value that is sufficient to cause irreversible damage to the battery. In this case, in order to urgently supply power to important loads, it is necessary to reduce the input turn-on threshold voltage to DC IN(ON2) In order to enable the PCS to start up and view historical operating status and other information, even if the grid-connected operation is not performed, it is necessary to lower the input turn-on threshold voltage to DC IN(ON2) , so that the PCS starts up and enters the off-grid standby state.

[0080] Although not shown, the threshold switching circuit of the present disclosure may be deployed only in the startup circuit, that is, the step-down switching power supply according to the embodiment of the present disclosure may only include the second threshold switching circuit (for switching the startup circuit) and its control circuit, and may not include the first threshold switching circuit (for switching the input undervoltage protection circuit) and its control circuit.

[0081] Reference Figure 4 The power supply circuit of the energy storage system according to the embodiment of the present disclosure includes a DC power supply module, which includes a step-down switching circuit 11, a transformer 14 and a DC output circuit 15 (refer to Figure 1 ):

[0082] The step-down switching circuit 11 may include a start-up circuit 113 and a transformer control circuit 112. The start-up circuit 113 receives a DC input voltage DC IN .

[0083] The startup circuit 113 may receive a DC input voltage and output a driving voltage to the transformer control circuit. The startup circuit 113 may include a charging capacitor C VCC And the starting circuit circuit. The charging capacitor can be connected to the transformer control circuit, and the starting resistance circuit can be connected in series with the charging capacitor.

[0084] The threshold switching circuit may further include a threshold switching circuit (e.g., a second threshold switching circuit) connected to the startup resistor circuit, wherein the resistance of the startup resistor circuit is changed by switching the state of the second threshold switching circuit. It should be noted that the second threshold switching circuit of the present disclosure merely changes the resistance of the startup circuit, and does not completely disconnect the startup circuit.

[0085] As an example, when the DC input voltage is less than the first threshold, the second threshold switching circuit can remain in the first state (for example, the disconnected state). When the DC input voltage further decreases to less than the second threshold, the second threshold switching circuit can be controlled (for example, manually or automatically) to be in the second state (for example, the closed state), thereby changing the size of the resistance of the startup circuit connected to the step-down switching circuit while keeping the startup circuit connected to the step-down switching circuit.

[0086] Specifically, when the second threshold switching circuit (low-voltage starting switch component) of the present invention is deployed on the starting circuit, the controllable switch of the second threshold switching circuit is connected to the two ends of the second starting resistor Rstart2 of the step-down switching circuit. The second threshold switching circuit can control whether the second starting resistor Rstart2 is connected to the step-down switching circuit. When the second threshold switching circuit is disconnected, the second starting resistor Rstart2 is normally connected to the step-down switching circuit. The input start-up threshold voltage of the step-down switching circuit is DC IN(ON1) When the second threshold switching circuit is closed, the second starting resistor Rstart2 is short-circuited, the total resistance of the first starting resistor Rstart1 and the second starting resistor Rstart2 in series decreases, the charging current of the capacitor Cvcc increases, and the input turn-on threshold voltage of the step-down switch circuit will decrease from DC IN(ON1) Reduce to DC IN(ON2) , so that the effective working voltage of the input terminal changes from DC IN(ON1) Reduce to DC IN(ON2) , the voltage input range of the DC power module is expanded, and a lower energy storage battery voltage can be used to drive the DC power module to normally output the PCS working voltage V OUT .

[0087] In one example, Figure 2 The controlled voltage-dividing resistor of the input undervoltage protection circuit connected to the threshold switching circuit may be the second voltage-dividing resistor Rt2 , or the third voltage-dividing resistor Rt1 or the first voltage-dividing resistor Rb. Figure 2 and Figure 3 The starting resistor in the starting circuit connected to the threshold switching circuit may be the second starting resistor Rstart2 or may be the first starting resistor Rstart1 .

[0088] in addition, Figure 2 and Figure 3The starting resistor and the voltage divider resistor can be one or more resistors. These resistors can be connected in series, in parallel, or in a series-parallel combination of one or more resistors in the resistor network. Figures 5 to 7 Provide a detailed description.

[0089] Figure 5 is a circuit diagram of a starting resistor circuit according to a first embodiment of the present disclosure; Figure 6 is a circuit diagram of a startup resistor circuit according to a second embodiment of the present disclosure; Figure 7 is a circuit diagram of a startup resistor circuit according to a third embodiment of the present disclosure.

[0090] Reference Figure 5 The startup resistance circuit in the startup circuit may include three resistors connected in series, namely, a first resistor Rstart2-1, a second resistor Rstart2-2, and a third resistor Rstart2-3. The threshold switching circuit of the present disclosure (e.g., the second threshold switching circuit) may be connected in series to at least one of the first resistor Rstart2-1, the second resistor Rstart2-2, and the third resistor Rstart2-3.

[0091] Reference Figure 6 The starting resistance circuit in the starting circuit may include three resistors, namely, a first resistor Rstart2-1, a second resistor Rstart2-2, and a third resistor Rstart2-3. The first resistor Rstart2-1 and the second resistor Rstart2-2 may be connected in parallel with each other, and the third resistor Rstart2-3 may be connected in series with a threshold switching circuit (for example, a second threshold switching circuit) and then connected in parallel with the second resistor Rstart2-2 and the first resistor Rstart2-1, respectively.

[0092] Reference Figure 7 The starting resistance circuit in the starting circuit may include three resistors, namely, a first resistor Rstart2-1, a second resistor Rstart2-2, and a third resistor Rstart2-3. The first resistor Rstart2-1 and the second resistor Rstart2-2 may be connected in series with each other, and the third resistor Rstart2-3 may be connected in series with a threshold switching circuit (for example, a second threshold switching circuit) and then connected in parallel with the second resistor Rstart2-2.

[0093] Although not shown, the voltage divider resistor circuit in the input undervoltage protection circuit of the present disclosure can be used in the same manner as Figures 5 to 7 The starting resistance circuit has the same circuit structure.

[0094] As shown above, the technical concept of the present disclosure is not limited to being implemented through the resistor elements in the input undervoltage protection circuit and the startup circuit, but can also be implemented through the inductive elements and capacitive elements therein.

[0095] In addition, although not described, the second DC-DC conversion circuit 30 can be implemented by a conventional DC-DC conversion circuit, and the output voltage of the second DC-DC conversion circuit 30 can be adjusted according to the required voltage level.

[0096] The energy storage converter of the present disclosure may include the above-mentioned power supply circuit. The energy storage system of the present disclosure may include the above-mentioned energy storage converter.

[0097] As an example, the power supply circuit of the energy storage system can be installed inside or outside the PCS. Preferably, the power supply circuit of the energy storage system can be installed inside the PCS to achieve higher system integration.

[0098] As described above, the DC power supply module of the energy storage system with an adjustable startup voltage threshold is connected to a threshold switching circuit at the input circuit, and the threshold switching circuit has the function of adjusting the startup voltage of the power circuit of the DC power supply module.

[0099] When the voltage of the DC side energy storage battery is lower than the normal starting voltage threshold of the DC power module, if the energy storage battery still has sufficient power to ensure that the PCS can start normally, and the battery voltage is not lower than the high fault level undervoltage alarm value that is sufficient to cause irreversible damage to the battery, the starting voltage threshold of the DC power module can be temporarily lowered by operating the threshold switching circuit, so that the lower voltage energy storage battery can also enable the DC power module to start and output the operating voltage required for PCS startup, realizing low-power emergency startup of the energy storage system.

[0100] At the same time, the DC power supply module with adjustable starting voltage threshold function can also enable the PCS to be compatible with low-rated voltage energy storage batteries with normal power and grid-connected charging and discharging conditions to be normally connected to the system for operation.

[0101] The power supply circuit according to the embodiment of the present disclosure can adapt to a wide input voltage range.

[0102] The power supply circuit according to the embodiment of the present disclosure can start the DC power supply module and provide the starting voltage required by the PCS even when the voltage of the energy storage battery is low, thereby realizing low-power emergency starting of the energy storage system.

[0103] The power supply circuit according to the embodiment of the present disclosure reduces the input-output voltage difference of the DC power supply module through a lower input voltage, thereby reducing battery loss, improving power efficiency, and making full use of the remaining power of the energy storage battery.

[0104] The power supply circuit according to the embodiment of the present disclosure can make the PCS compatible with low-rated voltage energy storage batteries that have grid-connected charging and discharging conditions, thereby enhancing the versatility and compatibility of the PCS power supply system.

[0105] It should be understood that the present disclosure is not limited to the exact structures that have been described above and shown in the drawings, and that various modifications and changes can be made without departing from the scope thereof. The scope of the present disclosure is limited only by the appended claims.

Claims

1. A power supply circuit for an energy storage system, characterized in that: The power supply circuit includes a DC power supply module, and the DC power supply module includes: A step-down switching circuit includes a start-up circuit and a transformer control circuit, wherein the start-up circuit receives a DC input voltage and outputs a driving voltage to the transformer control circuit; a transformer, an output end of the step-down switching circuit being connected to one side of the transformer, and the transformer control circuit being connected to the transformer; a DC output circuit connected to the other side of the transformer and outputting a first DC output voltage; The threshold switching circuit includes a first threshold switching circuit connected to the startup circuit, wherein the first threshold switching circuit changes the startup resistance of the startup circuit through a switching operation. The startup circuit is connected to the circuit both in the on state and the off state of the first threshold switching circuit.

2. The power supply circuit of the energy storage system according to claim 1, characterized in that: The starting circuit includes: a charging capacitor connected to the transformer control circuit; and a starting resistance circuit connected in series with the charging capacitor.

3. The power supply circuit of the energy storage system according to claim 2, characterized in that: The startup resistor circuit includes a first startup resistor and a second startup resistor connected in series, and the first threshold switching circuit is connected in parallel with the first startup resistor or the second startup resistor.

4. The power supply circuit of the energy storage system according to claim 2, characterized in that: The starting resistor circuit includes a first starting resistor and a second starting resistor connected in parallel with each other. The first threshold switching circuit is connected in series with a third starting resistor and then connected in parallel with the first starting resistor or the second starting resistor.

5. The power supply circuit of the energy storage system according to claim 1, characterized in that: The step-down switch circuit further includes an input undervoltage protection circuit, which receives a DC input voltage. The threshold switching circuit also includes a second threshold switching circuit connected to the input undervoltage protection circuit, wherein the input undervoltage protection circuit stops operating the transformer control circuit in response to the DC input voltage being less than a first threshold when the second threshold switching circuit is in a first state, and stops operating the transformer control circuit in response to the DC input voltage being less than a second threshold when the second threshold switching circuit is in a second state.

6. The power supply circuit of the energy storage system according to claim 5, characterized in that: The second threshold switching circuit is connected to the voltage-dividing resistor circuit of the input undervoltage protection circuit to adjust the resistance of the voltage-dividing resistor circuit.

7. The power supply circuit of the energy storage system according to claim 6, characterized in that: The voltage-dividing resistor circuit includes a first voltage-dividing resistor and a second voltage-dividing resistor connected in series or in parallel with each other, and the second threshold switching circuit is connected in parallel to the first voltage-dividing resistor or the second voltage-dividing resistor.

8. The power supply circuit of the energy storage system according to claim 6, characterized in that: The input undervoltage protection circuit also includes a comparator, the positive input of the comparator is connected to the voltage divider resistor circuit, the reverse input of the comparator receives a reference voltage, and the output of the comparator is connected to the PWM controller in the transformer control circuit via a reverse diode.

9. The power supply circuit of the energy storage system according to claim 1, characterized in that: The first threshold switching circuit includes a controllable switch and a driver thereof, wherein the driver is used to control the closing or opening of the controllable switch.

10. The power supply circuit of the energy storage system according to claim 1, characterized in that: The power supply circuit further includes: an AC power supply module, the AC power supply module receiving an AC input voltage and outputting a second DC output voltage different from the first DC output voltage, A DC-DC conversion circuit, wherein the first DC output voltage and the second DC output voltage are input to the DC-DC conversion circuit via a first forward diode and a second forward diode respectively, and the DC-DC conversion circuit outputs a power supply voltage.

11. An energy storage converter, characterized in that: The energy storage converter comprises the power supply circuit according to any one of claims 1 to 10.

12. An energy storage system, characterized in that: It comprises the energy storage converter according to claim 11.

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