Power converter and energy storage system

Abstract

The invention provides a power converter and an energy storage system, and belongs to the technical field of power electronics. The power converter provided by the invention comprises two boosted circuits which are connected in parallel in an interleaving manner, a power conversion circuit and a protection switch. The two boosted circuits which are connected in parallel in an interleaving mode can work in an interleaving mode so as to carry out boosting conversion on direct current provided by the direct current source, and conversion efficiency is high. And the protection switch is connected in parallel with the power switch tube included in one of the two booster circuits. As the conduction voltage drop of the protection switch is smaller than that of the body diode of the power switch tube connected in parallel, the short-circuit current generated by the reverse connection of the input polarity of the direct-current source mainly flows through the protection switch instead of the body diode of the power switch tube connected in parallel. Furthermore, the voltage drop of the body diode can be effectively reduced, and the over-temperature failure of the power switch tubes connected in parallel caused by the large heat generated by the body diode is avoided.

Description

Technical Field

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

[0002] In power converters, direct current (DC) / DC converters often use boost circuits, that is, they are often used to boost the DC power input from a DC source to an input terminal and then output it through an output terminal. The DC source is, for example, a photovoltaic (PV) string or an energy storage battery.

[0003] The boost circuit generally includes: an inductor, a freewheeling diode and a power switch tube. Among them, the inductor and the freewheeling diode are connected in series between the positive pole of the input end and the positive pole of the output end of the boost circuit. The drain of the power switch tube is connected to the series node of the inductor and the freewheeling diode, and the source of the power switch tube is connected to the negative pole of the input end and the negative pole of the output end and grounded. The power switch tube can be turned on and off periodically to control the charging and discharging of the inductor, so that the direct current received at the input end is boosted and output to the output end through the freewheeling diode to achieve the boost function. In addition, in a normal boost scenario, the positive pole of the DC source should be connected to the positive pole of the input end, and the negative pole of the DC source should be connected to the negative pole of the input end.

[0004] However, when the negative pole of the DC source is connected to the positive pole of the input terminal, and the positive pole of the DC source is connected to the negative pole of the input terminal (that is, when the input polarity of the DC source is reversed), current will flow through the body diode of the power switch tube, causing the voltage drop of the body diode to increase and generate heat, thereby causing the power switch tube to overheat and fail. Summary of the invention

[0005] Provided are a power converter and an energy storage system, which can solve the technical problem in the related art that when the input polarity of a DC source is reversed, a power switch tube is prone to over-temperature failure.

[0006] In a first aspect, a power converter is provided, the power converter comprising: a first boost circuit and a second boost circuit connected in parallel, a power conversion circuit, and a protection switch. The first boost circuit and the second boost circuit are both used to boost the direct current output by the direct current source and transmit it to the power conversion circuit, the power conversion circuit is used to convert the boosted direct current into alternating current and output it to a power grid or a load; the protection switch is connected in parallel with the power switch tube in the first boost circuit, and the conduction voltage drop of the protection switch is less than the conduction voltage drop of the body diode of the power switch tube in the first boost circuit.

[0007] Among them, the conduction voltage drop of the protection switch is smaller than the conduction voltage drop of the body diode, which can mean that: when the magnitude of the current flowing through the protection switch and the body diode is the same, the conduction voltage drop of the protection switch is smaller than the conduction voltage drop of the body diode. Because the conduction voltage drop of the protection switch is smaller than the conduction voltage drop of the body diode of the power switch tube in the first boost circuit, when the input polarity of the DC source connected to the first boost circuit is reversed, the short-circuit current mainly flows through the protection switch rather than the body diode of the power switch tube in the first boost circuit, that is, the protection switch can provide a flow path for the short-circuit current of the power converter. In this way, the voltage drop of the body diode of the power switch tube in the first boost circuit can be reduced, and the body diode can be prevented from generating a large amount of heat, which may cause the power switch tube in the first boost circuit to fail due to overtemperature, thereby achieving the purpose of reverse connection protection.

[0008] Of course, the conduction voltage drop of the protection switch can also be set to be smaller than the conduction voltage drop of the body diode of the power switch tube in the second boost circuit, so that when the input polarity of the DC source connected to the second boost circuit is reversed, the short-circuit current can also flow mainly through the protection switch rather than the body diode of the power switch tube in the second boost circuit, reducing the voltage drop of the body diode of the power switch tube in the second boost circuit, and avoiding the body diode from generating a large amount of heat and causing the power switch tube in the second boost circuit to fail due to overtemperature. On this basis, it can be known that for two boost circuits staggered in parallel, a power switch tube in one boost circuit is provided with a protection switch in parallel, which can not only reliably prevent the power switch tube in each boost circuit from failing due to overtemperature, but also simplify the number of components provided, reduce the structural complexity and cost of the power converter, and facilitate packaging layout.

[0009] Optionally, the protection switch may include: a first diode, and a conduction direction of the first diode may be the same as a conduction direction of the body diode.

[0010] By setting the protection switch as a unidirectional conducting diode, the structure of the power converter can be ensured to be relatively simple. It can be understood that the conduction direction of the body diode is generally from the negative pole of the input terminal to the positive pole of the input terminal, so as to provide a flow path for the short-circuit current generated when the input polarity of the DC source is reversed. Correspondingly, the conduction direction of the first diode can also be from the negative pole of the input terminal to the positive pole of the input terminal. In this way, the short-circuit current can reliably flow through the protection switch, thereby achieving the purpose of anti-reverse protection.

[0011] Optionally, the first diode may be a silicon diode. Using silicon material to prepare the first diode can reduce the conduction voltage drop of the first diode (ie, the protection switch).

[0012] Optionally, the power converter may further include: a bypass switch. One end of the bypass switch may be connected to the input end of the first boost circuit, the other end of the bypass switch may be connected to the output end of the first boost circuit, and the on-state voltage drop of the bypass switch may be smaller than the on-state voltage drop of the freewheeling switch in the first boost circuit; or one end of the bypass switch may be connected to the input end of the second boost circuit, the other end of the bypass switch may be connected to the output end of the second boost circuit, and the on-state voltage drop of the bypass switch may be smaller than the on-state voltage drop of the freewheeling switch in the second boost circuit.

[0013] Among them, the on-state voltage drop of the bypass switch is smaller than the on-state voltage drop of the freewheeling switch, which can mean that: when the magnitude of the current flowing through the bypass switch and the freewheeling switch is the same, the on-state voltage drop of the bypass switch is smaller than the on-state voltage drop of the freewheeling switch. Because the on-state voltage drop of the bypass switch is smaller than the on-state voltage drop of the freewheeling switch in the boost circuit to which it is connected, when the power switch tube in the boost circuit is turned off, the current of the direct current provided by the input end can mainly flow through the bypass switch and be directly output to the output end, that is, a low-impedance path can be provided for the boost circuit. In this way, the energy loss of the switching device in the boost circuit can be reduced, thereby improving the boost conversion efficiency.

[0014] Of course, the conduction voltage drop of the bypass switch connected to the first boost circuit or the second boost circuit can be less than the conduction voltage drop of the freewheeling switch included in each boost circuit, so that when the power switch tube in each boost circuit is turned off, the current of the DC power provided by the input end can mainly flow through the bypass switch and be directly output to the output end, thereby improving each boost conversion efficiency. On this basis, it can also be seen that a bypass switch is set for multiple boost circuits staggered in parallel, and a boost circuit is connected to the bypass switch. Compared with setting all boost circuits to be connected to the bypass switch, it can not only reliably improve the boost conversion efficiency of each boost circuit, but also simplify the number of components set, reduce the structural complexity and cost of the power converter, and facilitate packaging layout.

[0015] Optionally, the bypass switch may include: a second diode, an anode of the second diode may be connected to the input end, and a cathode of the second diode may be connected to the output end.

[0016] By setting the bypass switch as a unidirectional conducting diode, the structure of the power converter can be relatively simple. Moreover, based on the connection mode of the second diode, it can be known that the conducting direction of the bypass switch can be from the input end to the output end. In this way, it can be ensured that the current at the input end reliably flows to the output end through the second diode, and the current at the output end will not flow back to the input end.

[0017] Optionally, the second diode may be a silicon diode. Using silicon material to prepare the second diode can reduce the conduction voltage drop of the second diode (ie, the bypass switch).

[0018] Optionally, the protection switch and the bypass switch can be connected to the same boost circuit in the first boost circuit and the second boost circuit. That is, on the basis of the protection switch being connected in parallel with the power switch tube in the first boost circuit, the bypass switch can be connected between the input and output ends of the first boost circuit.

[0019] In the case where the power converter includes two boost circuits connected in parallel and includes a protection switch and a bypass switch at the same time, the protection switch and the bypass switch can be the same boost circuit connected in parallel to the two boost circuits. In this way, since the conduction voltage drop of the protection switch is at least smaller than the conduction voltage drop of the body diode of the power switch tube in the boost circuit, and the conduction voltage drop of the bypass switch is at least smaller than the conduction voltage drop of the freewheeling switch in the boost circuit, it is possible to reliably implement over-temperature failure protection against reverse connection and improve the boost conversion efficiency for at least one of the boost circuits, thereby ensuring the reliable operation of one of the boost circuits. In addition, it is possible to facilitate the packaging layout of each device in the same boost circuit.

[0020] Optionally, the bypass switch, the protection switch, the freewheeling switch and the power switch tube in the first boost circuit, and the freewheeling switch and the power switch tube in the second boost circuit can be packaged in one module.

[0021] That is, multiple switch devices in the power converter can be integrated. By integrating multiple switch devices, the device integration level in the power converter can be improved, thereby reducing the overall circuit size of the power converter.

[0022] Optionally, the freewheeling switch in the first boost circuit and the freewheeling switch in the second boost circuit can both be silicon carbide diodes; the power switch tube in the first boost circuit and the power switch tube in the second boost circuit can both be silicon carbide field effect tubes.

[0023] It can be understood that, compared with silicon carbide materials, the on-state voltage drop of the switch device made of silicon material can be smaller.

[0024] In a second aspect, an energy storage system is provided, which includes: a first energy storage battery, a second energy storage battery, and a power converter as provided in the first aspect; a first boost circuit in the power converter is used to boost the direct current power provided by the first energy storage battery; and a second boost circuit in the power converter is used to boost the direct current power provided by the second energy storage battery.

[0025] In summary, the present application provides a power converter and an energy storage system. In the solution provided by the present application, the power converter includes two boost circuits connected in parallel, a power conversion circuit and a protection switch. Among them, the two boost circuits connected in parallel can work in an interlaced manner to perform boost conversion processing on the DC power provided by a DC source such as a photovoltaic string or an energy storage battery, and the conversion efficiency is relatively high. The power conversion circuit can convert the boosted DC power into AC power and output it to the power grid or load to reliably supply power to the power grid or load. The protection switch is connected in parallel with the power switch tube included in one of the two boost circuits. Because the conduction voltage drop of the protection switch is less than the conduction voltage drop of the body diode of the parallel power switch tube, the short-circuit current generated by the reverse polarity of the input of the DC source can flow mainly through the body diode of the non-power switch tube connected in parallel with the protection switch. Furthermore, the voltage drop of the body diode can be effectively reduced to avoid the body diode generating a large amount of heat and causing the parallel power switch tube to fail due to overtemperature. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 is a schematic diagram of the structure of a power converter provided in an embodiment of the present application;

[0027] Figure 2 is a schematic diagram of the structure of another power converter provided in an embodiment of the present application;

[0028] Figure 3 is a schematic diagram of a circuit structure of a power converter provided in an embodiment of the present application;

[0029] Figure 4 is a working schematic diagram of a power converter provided in an embodiment of the present application;

[0030] Figure 5 is a working schematic diagram of a power converter provided in an embodiment of the present application;

[0031] Figure 6 is a working schematic diagram of a power converter provided in an embodiment of the present application;

[0032] Figure 7 It is a structural schematic diagram of an energy storage system provided in an embodiment of the present application. DETAILED DESCRIPTION

[0033] The power converter and energy storage system provided by the embodiments of the present application are described in detail below in conjunction with the accompanying drawings. First, the key terms involved in the embodiments of the present application are introduced.

[0034] DC / DC converter: A power electronic device that converts one type of direct current (DC) into another type of direct current (DC). It is a type of power converter.

[0035] Boost circuit: A type of DC / DC converter, used to boost the received DC power and output it, that is, to convert DC power from low voltage to high voltage. The low voltage and high voltage here are relative.

[0036] PV string: A unit formed by connecting multiple photovoltaic modules (also called solar cells) in series to convert solar energy into usable electrical energy.

[0037] Inverter: A power electronic device that converts direct current (DC) into alternating current (AC). It is a type of power converter and is also called a power conversion circuit in the embodiments of the present application.

[0038] Maximum power point tracking (MPPT): A technology used to optimize the output power of solar cells. It aims to continuously adjust the working point of the solar cell so that it always outputs the maximum power. The power converter used in the photovoltaic system is one of the circuits designed using MPPT technology. Accordingly, the power converter can also be called an MPPT circuit.

[0039] The embodiment of the present application provides a power converter, which can solve the technical problem of over-temperature failure of the power switch tube in the power converter when the input polarity of the DC source is reversed, that is, the power converter can achieve the purpose of reverse connection protection. In addition, the circuit structure of the power converter is simple, the number of components required is small, and the cost is low.

[0040] like Figure 1 As shown, the power converter includes: a first boost circuit 01 and a second boost circuit 02 connected in parallel (ie, two Boost circuits connected in parallel), a power conversion circuit 03 , and a protection switch 04 .

[0041] The first boost circuit 01 and the second boost circuit 02 are both used to boost the DC power output by the DC source and transmit it to the power conversion circuit 03. The power conversion circuit 03 is used to convert the boosted DC power into AC power and output it to the power grid or load.

[0042] Optionally, the DC source may be a PV string or an energy storage battery. That is, the PV string or energy storage battery may be used as a DC source to provide DC power to the power converter, and then the DC power is boosted and converted to AC power by two staggered parallel Boost circuits and the power conversion circuit 03 in turn, and finally the power conversion circuit 03 transmits the converted AC power to the power grid or load to supply power to the power grid or load. The following embodiments are all described by taking the DC source as a PV string as an example.

[0043] And, if Figure 1 As shown, the input end of the first boost circuit 01 and the input end of the second boost circuit 02 are both used to connect to a DC source, the output end of the first boost circuit 01 and the output end of the second boost circuit 02 are both connected to the input end of the power conversion circuit 03, and the output end of the power conversion circuit 03 is used to connect to a power grid or a load. And, it can be understood that the staggered parallel connection of two Boost circuits can refer to: connecting the two Boost circuits in parallel, and setting the two Boost circuits to work alternately for boost conversion. The parallel connection here can refer to the output ends of the two Boost circuits being connected in parallel to the same device (such as the power conversion circuit 03), and the input ends of the two Boost circuits can be connected to the same or different DC sources.

[0044] For example, combined Figure 1 , the DC source shown is a PV string, and the staggered parallel first boost circuit 01 and second boost circuit 02 shown can be connected to different PV strings respectively. In the embodiment of the present application, the PV string connected to the first boost circuit 01 can be called the first PV string PV1, and the PV string connected to the second boost circuit 02 can be called the second PV string PV2. And, as Figure 1 As shown, each PV string in the first PV string PV1 and the second PV string PV2 may include a plurality of photovoltaic modules connected in series. Of course, in some other embodiments, the two Boost circuits are not limited to being staggered in parallel. That is, the power converter is not limited to including Figure 1 The first boost circuit 01 and the second boost circuit 02 are shown to be interlaced in parallel. For example, the power converter may include three or more Boost circuits that are interlaced in parallel.

[0045] It can also be understood that because the two Boost circuits can alternately boost, the boost conversion efficiency can be improved. Accordingly, the staggered parallel design is mostly used in high voltage difference / large MPPT current scenarios. Among them, the high voltage difference refers to the high voltage difference of the DC power before and after the Boost circuit conversion. The large MPPT current refers to the large current of the DC power received by the Boost circuit from the DC source.

[0046] Continue to refer Figure 1It can be seen that both the first boost circuit 01 and the second boost circuit 02 include: an inductor L, a freewheeling switch K and a power switch tube T. For distinction, the inductor L included in the first boost circuit 01 is identified as L01 in the figure; the inductor L included in the second boost circuit 02 is identified as L02. The freewheeling switch K included in the first boost circuit 01 is identified as K01; the freewheeling switch K included in the second boost circuit 02 is identified as K02. The power switch tube T included in the first boost circuit 01 is identified as T01, and the body diode D of the power switch tube T01 is identified as D01; the power switch tube T included in the first boost circuit 02 is identified as T02, and the body diode D of the power switch tube T02 is identified as D02.

[0047] The protection switch 04 described in the embodiment of the present application is connected in parallel with the power switch tube T01 in the first boost circuit 01 , and the conduction voltage drop of the protection switch 04 is smaller than the conduction voltage drop of the body diode D01 of the power switch tube T01 in the first boost circuit 01 .

[0048] It can be understood that the conduction voltage drop of switch devices such as the protection switch 04 and the body diode D may refer to: the voltage drop across the switch device when a current flows through the switch device in the conduction state, also known as the forward voltage drop. Moreover, in the embodiment of the present application, the conduction voltage drop of the protection switch 04 is less than the conduction voltage drop of the body diode D of the power switch tube T, which may refer to: when the magnitude of the current flowing through the protection switch 04 and the body diode D is the same, the conduction voltage drop of the protection switch 04 is less than the conduction voltage drop of the body diode D of the power switch tube T.

[0049] It can also be understood that, for each boost circuit in the first boost circuit 01 and the second boost circuit 02, one end of the inductor L can be connected to the positive electrode of the input end of the boost circuit, the other end of the inductor L can be connected to one end of the freewheeling switch K in the boost circuit, the other end of the freewheeling switch K can be connected to the positive electrode of the output end of the boost circuit, the drain of the power switch tube T can be connected to the other end of the inductor L in the boost circuit, the source of the power switch tube T can be grounded together with the negative electrode of the input end and the negative electrode of the output end of the boost circuit, the positive electrode of the body diode D of the power switch tube T can be connected to the source of the power switch tube T, and the negative electrode of the body diode D can be connected to the drain of the power switch tube T. That is, the structures of the first boost circuit 01 and the second boost circuit 02 connected in parallel are the same, and accordingly, the working principles are also the same. It can be understood that for any diode, its positive electrode can also be called an anode, and its negative electrode can also be called a cathode. Furthermore, in some embodiments, the output end of each boost circuit may be connected to an output capacitor to achieve the purpose of smoothing the output.

[0050] For example, taking the first boost circuit 01 as an example, one end of the inductor L01 can be connected to the positive electrode of the input end of the first boost circuit 01, the other end of the inductor L01 can be connected to one end of the freewheeling switch K01 in the first boost circuit 01, the other end of the freewheeling switch K01 can be connected to the positive electrode of the output end of the first boost circuit 01, the drain of the power switch tube T01 can be connected to the other end of the inductor L01 in the first boost circuit 01 (that is, the end of the inductor L01 connected to the freewheeling switch K1), the source of the power switch tube T01 can be grounded together with the negative electrode of the input end and the negative electrode of the output end of the first boost circuit 01, the positive electrode of the body diode D01 can be connected to the source of the power switch tube T01, and the negative electrode of the body diode D01 can be connected to the drain of the power switch tube T01. On this basis, it can be known that in some embodiments, such as Figure 1 As shown, the protection switch 04 is connected in parallel with the power switch tube T01 in the first boost circuit 01, which may mean that one end of the protection switch 04 is connected to the other end of the inductor L01, and the other end is grounded. That is, the protection switch 04 can be connected in parallel with the power switch tube T01 at the same end of the inductor L01, or the protection switch 04 is connected in parallel between the source and drain of the power switch tube T01. Alternatively, in other embodiments, one end of the protection switch 04 can also be connected to one end of the inductor L01 (that is, the end of the inductor L01 connected to the input end), and the other end of the protection switch 04 can be grounded. That is, the protection switch 04 can be connected in parallel with the power switch tube T01 at different ends of the inductor L01.

[0051] Taking the first boost circuit 01 as an example, combined with Figure 1 , the working principle of each boost circuit is briefly described as follows:

[0052] (1) Energy storage stage, the power switch tube T01 is turned on and the freewheeling switch K01 is turned off. At this time, the DC current provided by the first PV string PV1 connected to the input end of the first boost circuit 01 can flow through the inductor L01 and the power switch tube T01 in sequence, so that the inductor L01 starts to store energy. (2) Energy release stage, the power switch tube T01 is turned off and the freewheeling switch K01 is turned on. At this time, because the current on the inductor L01 cannot change suddenly, it can be freewheeled through the freewheeling switch K01, that is, it can flow to the output end through the freewheeling switch K01, so that the inductor L01 releases energy. On the basis of the energy released by the inductor L01, the DC power provided by the first PV string PV1 is superimposed, that is, a higher voltage DC power can be formed. Based on this, the boost conversion can be achieved by continuously controlling the switching devices such as the power switch tube T01 and the freewheeling switch K01 to turn on and off, that is, repeatedly executing the energy storage stage and the energy release stage. It can also be seen from this that the alternating operation of the two Boost circuits recorded in the previous text can refer to the alternating conduction of the power switches in the two Boost circuits. The connection method and working principle of the components in the second boost circuit 02 are similar and will not be described in detail.

[0053] It can be understood that, for each boost circuit, the premise for performing boost conversion according to the above working principle is that the input polarity of the DC source is positively connected. That is, the positive pole of the DC source is connected to the positive pole of the input end of the boost circuit, and the negative pole of the DC source is connected to the negative pole of the input end of the boost circuit. In the case where the input polarity of the DC source is reversely connected, that is, when the positive pole of the DC source is connected to the negative pole of the input end of the boost circuit, and the negative pole of the DC source is connected to the positive pole of the input end of the boost circuit, a short-circuit current will be generated at the input end. On the basis of not setting the protection switch 04, the short-circuit current will flow from the negative pole of the input end of the boost circuit through the body diode D and the inductor L of the power switch tube T in the boost circuit in sequence, causing the body diode D to generate a large amount of heat, resulting in the power switch tube T overheating and failure. In a boost circuit, a protection switch 04 is connected in parallel to one side of the power switch tube T, and the conduction voltage drop of the protection switch 04 is set to be smaller than the conduction voltage drop of the body diode D of the power switch tube T, so that the short-circuit current can flow mainly through the protection switch 04 instead of the body diode D. In other words, most of the current in the short-circuit current can flow through the protection switch 04, and the protection switch 04 provides a flow path for the short-circuit current. In this way, the voltage drop of the body diode D of the power switch tube T can be reduced, and the body diode D can be prevented from generating a large amount of heat, thereby effectively preventing the power switch tube T from overheating and failing.

[0054] For example, Figure 1 As shown, a protection switch 04 is connected in parallel on one side of the power switch tube T01 in the first boost circuit 01, and the DC source is taken as an example of a PV string. When the input polarity of the first PV string PV1 is reversed, that is, the positive pole of the first PV string PV1 is connected to the negative pole of the input end of the first boost circuit 01, and the negative pole of the first PV string PV1 is connected to the positive pole of the input end of the first boost circuit 01, the short-circuit current can mainly flow through the protection switch 04 rather than the body diode D01 of the power switch tube T01.

[0055] It can be understood that the above embodiment is described by taking the example of the protection switch 04 being connected in parallel with the power switch tube T01 in the first boost circuit 01. Of course, in some other embodiments, the protection switch 04 can also be connected in parallel with the power switch tube T02 in the second boost circuit 02, and the conduction voltage drop of the protection switch 04 is less than the conduction voltage drop of the body diode D02 of the power switch tube T02 in the second boost circuit 02. In this way, when the input polarity of the second PV string PV2 connected to the second boost circuit 02 is reversed, that is, when the positive pole of the second PV string PV2 is connected to the negative pole of the input end of the second boost circuit 02, and the negative pole of the second PV string PV2 is connected to the positive pole of the input end of the second boost circuit 02, the short-circuit current can mainly flow through the protection switch 04 instead of the body diode D02 of the power switch tube T02. That is, a protection switch 04 can be provided in a power converter including two Boost circuits connected in parallel, so as to be connected in parallel with a power switch tube T in one of the Boost circuits, and the conduction voltage drop of the protection switch 04 is smaller than the conduction voltage drop of the body diode D of the power switch tube T connected in parallel with it.

[0056] It can also be understood that the above embodiment is described by taking the conduction voltage drop of the protection switch 04 as an example that is smaller than the conduction voltage drop of the body diode D of the power switch tube T connected in parallel. In some other embodiments, the conduction voltage drop of the protection switch 04 connected in parallel with the power switch tube T in any boost circuit can not only be smaller than the conduction voltage drop of the body diode D of the power switch tube T connected in parallel, but also smaller than the conduction voltage drop of the body diode D of the power switch tube T in other boost circuits. In this way, it can be ensured that when the input polarity of the PV string connected to any boost circuit is reversed, the short-circuit current mainly flows through the protection switch 04, thereby effectively preventing the power switch tube T in any boost circuit from over-temperature failure. On this basis, it can also be seen that a protection switch 04 is provided for the multiple boost circuits connected in parallel, and the conduction voltage drop of the protection switch 04 is set to be smaller than the conduction voltage drop of the body diode D of the power switch tube T in each boost circuit. This can not only reliably prevent the power switch tube T in each boost circuit from over-temperature failure, but also requires fewer components, has a simple structure, and is low in cost.

[0057] In addition, since the body diode D of the power switch tube T mostly presents a negative temperature coefficient, that is, within a certain temperature range (especially at high temperature), the conduction voltage drop of the body diode D will decrease as the temperature increases, it can be seen that for the staggered parallel structure, when the short-circuit current flows through the body diode D of the power switch tube T, causing the voltage drop of the body diode D to increase and generate a large amount of heat, the higher the temperature of the body diode D, the larger the current will flow, which is not conducive to the equal distribution of current in each staggered parallel Boost circuit, that is, not conducive to current sharing, and thus more likely to cause the power switch tube to fail. In the embodiment of the present application, since the protection switch 04 can provide the main flow path for the short-circuit current and avoid the body diode D from generating a large amount of heat, it can also solve the problem of being not conducive to current sharing caused by the negative temperature coefficient, and further avoid the failure of the power switch tube T.

[0058] In summary, an embodiment of the present application provides a power converter. The power converter includes two boost circuits connected in parallel, a power conversion circuit and a protection switch. Among them, the two boost circuits connected in parallel can work in an interlaced manner to perform boost conversion processing on the DC power provided by a DC source such as a PV string or an energy storage battery, and the conversion efficiency is high. The power conversion circuit can convert the boosted DC power into AC power and output it to the power grid or load to provide reliable power supply to the power grid or load. The protection switch is connected in parallel with the power switch tube included in one of the two boost circuits. Because the conduction voltage drop of the protection switch is less than the conduction voltage drop of the body diode of the parallel power switch tube, the short-circuit current generated by the reverse polarity of the input of the DC source can flow mainly through the protection switch rather than the body diode of the parallel power switch tube. Furthermore, the voltage drop of the body diode can be effectively reduced to avoid the body diode generating a large amount of heat and causing the parallel power switch tube to fail due to overtemperature.

[0059] Optionally, in some embodiments, Figure 2 As shown, the power converter may further include: a bypass switch 05 .

[0060] As a possible implementation, one end of the bypass switch 05 can be connected to the input end of the first boost circuit 01, the other end of the bypass switch 05 can be connected to the output end of the first boost circuit 01, and the on-state voltage drop of the bypass switch 05 can be smaller than the on-state voltage drop of the freewheeling switch K01 in the first boost circuit 01.

[0061] As another possible implementation, one end of the bypass switch 05 can be connected to the input end of the second boost circuit 02, the other end of the bypass switch 05 can be connected to the output end of the second boost circuit 02, and the on-state voltage drop of the bypass switch 05 can be smaller than the on-state voltage drop of the freewheeling switch K02 in the second boost circuit 02.

[0062] That is, the bypass switch 05 can be connected in parallel with the freewheeling switch K in the first boost circuit 01 or the second boost circuit 02, one end of the bypass switch 05 is connected to the end of the inductor L connected to the input end, and the other end is connected to the end of the freewheeling switch K connected to the output end. And the conduction voltage drop of the bypass switch 05 is less than the conduction voltage drop of the freewheeling switch K connected in parallel. For example, Figure 2 The bypass switch 05 shown is connected in parallel to one side of the freewheeling switch K01 in the first boost circuit 01 .

[0063] Moreover, in combination with the foregoing description, the on-state voltage drop of the bypass switch 05 being smaller than the on-state voltage drop of the freewheeling switch K connected in parallel therewith may mean that: when the magnitudes of the currents flowing through the bypass switch 05 and the freewheeling switch K are the same, the on-state voltage drop of the bypass switch 05 is smaller than the on-state voltage drop of the freewheeling switch K.

[0064] It is understandable that, combined with Figure 2 In a structure without bypass switch 05, when the power switch tubes T in any boost circuit are turned off, the DC power provided by the DC source connected to the input end of the boost circuit needs to be transmitted to the output end of the boost circuit through the inductor L and the freewheeling switch K in sequence. In a boost circuit, a bypass switch 05 is arranged in parallel on one side of the freewheeling switch K, and the bypass switch 05 is arranged to be smaller than the conduction voltage drop of the parallel freewheeling switch K, so that the DC power provided by the DC source connected to the input end of the boost circuit can flow directly through the bypass switch 05 and be output to the output end of the boost circuit, providing a low-impedance path for the boost circuit. Therefore, since the DC power is avoided from flowing through the inductor L and the freewheeling switch K in sequence, the energy loss can be reduced, thereby improving the boost conversion efficiency.

[0065] For example, Figure 2 Taking the bypass switch 05 connected in parallel on one side of the freewheeling switch K01 in the first boost circuit 01 as an example, when the power switch tube T01 in the first boost circuit 01 is turned off, since the conduction voltage drop of the bypass switch 05 is smaller than the conduction voltage drop of the freewheeling switch K01, the DC current at the input end of the first boost circuit 01 can mainly flow through the bypass switch 05 and be directly output to the output end of the first boost circuit 01, providing a low-impedance path for the first boost circuit 01.

[0066] It can be understood that the above embodiment is described by taking the conduction voltage drop of the bypass switch 05 as an example that is smaller than the conduction voltage drop of the freewheeling switch K in the boost circuit connected in parallel. In some other embodiments, the conduction voltage drop of the bypass switch 05 connected in parallel with any boost circuit can not only be smaller than the conduction voltage drop of the freewheeling switch K in the boost circuit connected in parallel, but also can be smaller than the conduction voltage drop of the freewheeling switch K in each other boost circuit. In this way, it can be ensured that when the power switch tube T in all boost circuits is turned off, the current of the direct current from the input end can mainly flow through the bypass switch 05, thereby reliably improving the boost conversion efficiency. On this basis, it can also be seen that a bypass switch 05 is set for multiple boost circuits connected in parallel, and the conduction voltage drop of the bypass switch 05 is set to be smaller than the conduction voltage drop of the freewheeling switch K in each boost circuit. Not only can the boost conversion efficiency of each boost circuit be reliably improved, but also the number of required components is small, the structure is simple, and the cost is low.

[0067] Optionally, in some embodiments, the conduction voltage drop of the bypass switch 05 may also be smaller than the conduction voltage drop of the body diode D of the power switch tube T in each boost circuit, so as to reliably ensure that when the power switch tube T is turned off, the current of the DC power from the input end mainly flows to the output end through the bypass switch 05. Similarly, the conduction voltage drop of the protection switch 04 may also be smaller than the conduction voltage drop of the freewheeling switch K in each boost circuit, so as to reliably ensure that when the input polarity of the DC source is reversed, the short-circuit current mainly flows through the protection switch 04.

[0068] Optionally, the protection switch 04 and the bypass switch 05 may be connected to the same boost circuit of the first boost circuit 01 and the second boost circuit 02 .

[0069] That is, in an embodiment of the present application, when the power converter includes a plurality of boost circuits (e.g., a first boost circuit 01 and a second boost circuit 02) connected in parallel and includes a protection switch 04 and a bypass switch 05 at the same time, the protection switch 04 and the bypass switch 05 can be the same boost circuit (e.g., the first boost circuit 01) connected in parallel with the plurality of boost circuits.

[0070] For example, reference Figure 2 , the protection switch 04 can be connected in parallel with the power switch tube in the first boost circuit 01, and the bypass switch 05 can be connected between the input end and the output end of the first boost circuit 01. Alternatively, the protection switch 04 can be connected in parallel with the power switch tube in the second boost circuit 02, and the bypass switch 05 can be connected between the input end and the output end of the second boost circuit 02. In this way, the anti-reverse connection protection and the improvement of the boost conversion efficiency can be achieved for at least one of the boost circuits at the same time, ensuring the reliable operation of one of the boost circuits.

[0071] Of course, in some other embodiments, the protection switch 04 and the bypass switch 05 may also be connected in parallel to different boost circuits in the plurality of boost circuits, or, for each boost circuit, a protection switch 04 and a bypass switch 05 may be connected in parallel.

[0072] Optionally, in Figure 2 On the basis of Figure 3 FIG. 1 shows a schematic diagram of a circuit structure of a power converter. Figure 3 As shown, the freewheeling switch K01 in the first boost circuit 01 and the freewheeling switch K02 in the second boost circuit 02 may both be silicon carbide (SiC) diodes.

[0073] That is, the freewheeling switch K in each boost circuit can be set to be a unidirectional conducting diode, also known as a freewheeling diode. And the freewheeling diode can be a diode made of silicon carbide SiC material. The boost circuit of this structure may refer to an asynchronous boost circuit. Of course, in some other embodiments, the freewheeling switch K may also be a switch tube, and the boost circuit of this structure may also be called a synchronous boost circuit. That is, the power converter recorded in the embodiment of the present application may include an asynchronous boost circuit or a synchronous boost circuit, which can be used in a wide range.

[0074] To distinguish, Figure 3 The diode included in the first boost circuit 01 is identified as D01, and the diode included in the second boost circuit 02 is identified as D02. In addition, in combination with the above description of the working principle of the boost circuit, it can be known that the conduction direction of the diode D01 in the first boost circuit 01 can be from the input end to the output end of the first boost circuit 01, that is, the positive electrode of the diode D01 in the first boost circuit 01 can be connected to the other end of the inductor L01 as one end of the freewheeling switch K01, and the negative electrode of the diode D01 in the first boost circuit 01 can be connected to the positive electrode of the output end of the first boost circuit 01 as the other end of the freewheeling switch K01. Similarly, the conduction direction of the diode D02 in the second boost circuit 02 can be from the input end to the output end of the second boost circuit 02, that is, the positive electrode of the diode D02 in the second boost circuit 02 can be connected to the other end of the inductor L02 as one end of the freewheeling switch K02, and the negative electrode of the diode D02 in the second boost circuit 02 can be connected to the positive electrode of the output end of the second boost circuit 02 as the other end of the freewheeling switch K02.

[0075] The power switch tube T01 in the first boost circuit 01 and the power switch tube T02 in the second boost circuit 02 can both be silicon carbide SiC field effect tubes. That is, the power switch tube in each boost circuit can be a switch tube made of silicon carbide SiC material. Correspondingly, it can be known that the body diode D01 of the power switch tube T01 and the body diode D02 of the power switch tube T02 are both silicon carbide SiC diodes. In addition, the silicon carbide SiC field effect tube can be an N-type field effect tube or a P-type field effect tube.

[0076] Optionally, continue to refer to Figure 3 It can be seen that the protection switch 04 may include: a first diode D1. That is, the protection switch 04 may be set as a unidirectional conducting diode. In this way, the structure of the power converter may be relatively simple.

[0077] Furthermore, the conduction direction of the first diode D1 can be the same as the conduction direction of the body diode D of the power switch tube T. In this way, when the input polarity of the DC source is reversed, the short-circuit current can reliably flow through the first diode D1, thereby achieving the purpose of reverse connection protection. Accordingly, the first diode D1 can also be called a reverse connection protection diode.

[0078] As mentioned above, the anode of the body diode D is generally connected to the grounded source of the power switch tube T, and the cathode of the body diode D is generally connected to the drain of the power switch tube T. That is, the conduction direction of the body diode D is generally from the cathode of the input terminal to the anode of the input terminal. Correspondingly, it can be known that the conduction direction of the first diode D1 can also be from the cathode of the input terminal to the anode of the input terminal. That is, the anode of the first diode D1 can be connected to the cathode of the input terminal, and the cathode of the first diode D1 can be connected to one end or the other end of the inductor L to connect to the anode of the input terminal.

[0079] For example, combined Figure 3 For the protection switch 04 connected in parallel to the first boost circuit 01, the anode of the first diode D1 is connected to the cathode of the input end of the first boost circuit 01, and the cathode of the first diode D1 is connected to the other end of the inductor L01. That is, the first diode D1 and the power switch tube T01 are connected in parallel to the same side of the inductor L01.

[0080] Of course, in some other embodiments, the protection switch 04 can also be a switch tube. And, combined with the above description, it can be known that for the power converter of this structure, the switch tube included in the protection switch 04 can be controlled to be turned off when the input polarity is positively connected to ensure normal boost conversion; the switch tube included in the protection switch 04 can be controlled to be turned on when the input polarity of the PV string is reversed, so that the short-circuit current can mainly flow through the switch tube included in the protection switch 04, thereby achieving the purpose of anti-reverse protection.

[0081] Optionally, continue to refer to Figure 3 It can be seen that the bypass switch 05 may include: a second diode D2. That is, the bypass switch 05 may be set as a unidirectional conducting diode. In this way, the structure of the power converter may be relatively simple.

[0082] Furthermore, the anode of the second diode D2 can be connected to the input end, and the cathode of the second diode D2 can be connected to the output end. In this way, it can be ensured that the direct current from the input end can reliably flow to the output end through the second diode D2, and the current at the output end will not flow back to the input end. Accordingly, the second diode D2 can also be called a bypass diode.

[0083] For example, combined Figure 3 For the bypass switch 05 connected in parallel with the first boost circuit 01, the anode of the second diode D2 included therein can be connected to the anode of the input end of the first boost circuit 01, and the cathode of the second diode D2 can be connected to the anode of the output end of the first boost circuit 01.

[0084] Of course, in some other embodiments, the bypass switch 05 may also be a switch tube. In addition, in combination with the above description, it can be known that for the power converter of this structure, when the power switch tube in the boost circuit is turned on, the switch tube included in the bypass switch 05 can be controlled to be turned off to ensure normal boost conversion; when the power switch tube in the boost circuit is turned off, the switch tube included in the bypass switch 05 can be controlled to be turned on, so that the current at the input end mainly flows to the output end through the switch tube included in the bypass switch 05, thereby improving the boost conversion efficiency.

[0085] Optionally, the first diode D1 may be a silicon (Si) diode, that is, the first diode D1 may be a diode made of silicon material.

[0086] Optionally, the second diode D2 may be a silicon Si diode, that is, the second diode D2 may also be a diode made of silicon material.

[0087] It is understandable that the diode made of silicon Si material has a relatively small conduction voltage drop compared to the diode made of silicon carbide SiC material. That is, in the embodiment of the present application, different materials can be selected to prepare diodes included in different circuits to distinguish the conduction voltage drops of different circuits. Of course, in some other embodiments, different preparation processes can also be selected to prepare diodes included in different circuits to distinguish the conduction voltage drops of different circuits. The preparation process here can include, for example: the thickness of the PN junction in the diode and / or the material doping concentration, etc.

[0088] It can also be understood that the silicon Si material and silicon carbide SiC material described in the embodiments of the present application are only for illustrative purposes. Figure 3 An output capacitor C0 connected to the output terminal is also schematically shown.

[0089] Optionally, the bypass switch 05, the protection switch 04, the freewheeling switch K01 and the power switch tube D01 in the first boost circuit 01, and the freewheeling switch K02 and the power switch tube D02 in the second boost circuit 02 can be packaged in one module. That is, the various switching devices in the power converter can be integrated. Of course, in some other embodiments, the various switching devices in the power converter can also be independent single tubes, that is, the various switching devices in the power converter can also be independently arranged.

[0090] It is understandable that in the preparation process, a wafer can be provided first, and then various switching devices can be prepared on the wafer, and then the prepared switching devices can be cut into independent individuals (also called chips), and finally the cut chips can be packaged into different packaging shells to obtain independent single tubes, or the cut chips can be packaged into the same packaging shell to form a module, that is, packaged in a module. Among them, the wafer is a disc-shaped thin sheet used in the semiconductor manufacturing process, which is often used as a substrate for preparing various semiconductor devices. For example, the material of the wafer can generally be silicon (Si), and the diameter of the wafer can generally be 6 inches, 8 inches or 12 inches. Of course, the material and diameter here are only schematic illustrations.

[0091] It can also be understood that for power converters, integrated design can ensure that the various switching devices can work better together and can use space more effectively, thereby improving the device integration in the power converter and reducing the overall circuit size of the power converter. Of course, the independent design can easily repair and replace the various switching devices, and the combination configuration between the various switching devices is more flexible.

[0092] Optionally, in some embodiments, the power converter may include multiple Figure 3 Assume that Figure 3The two Boost circuits shown in the staggered parallel connection are called a 1-way MPPT circuit. Then the power converter recorded in the embodiment of the present application may include a multi-way MPPT circuit, the output end of the multi-way MPPT circuit can be connected in parallel to the same power conversion circuit 03, and the input end of the multi-way MPPT circuit can be connected to different PV strings. On this basis, for integrated design, all switching devices in the 1-way MPPT circuit can be packaged in 1 module to reduce the stray inductance in the circuit. Of course, all switching devices in the multi-way MPPT circuit can also be packaged in 1 module.

[0093] Understandably, Figure 3 The staggered parallel topology structure (ie, one MPPT circuit) shown may also be referred to as a two-level topology. In some other embodiments, the staggered parallel topology structure may also adopt a three-level topology, which is not limited in the embodiments of the present application.

[0094] Based on the foregoing, it can be seen that the embodiment of the present application mainly provides an anti-reverse connection protection circuit suitable for an interleaved parallel topology. The circuit includes: an interleaved parallel topology structure (i.e., a first boost circuit 01 and a second boost circuit 02), a single silicon Si diode connected in parallel between the source and drain of a power switch tube in a boost circuit (i.e., a first diode D1), and a single silicon Si diode connected in parallel on the freewheeling diode side of a boost circuit (i.e., a second diode D2).

[0095] Of course, in some embodiments, as described above, a silicon Si diode may be connected in parallel between the source and drain of the power switch tube in each boost circuit, and a silicon Si diode may be connected in parallel on the freewheeling diode side of each boost circuit. Figure 3 For the structure shown, the power converter may include two first diodes D1 and two second diodes D2. However, for this embodiment, since four diodes need to be added to solve the over-temperature failure problem and improve the boost conversion efficiency, the number of devices required to be set is large, the structural complexity and cost of the power converter are significantly increased, and it is not conducive to the layout and packaging in the module.

[0096] The embodiment of the present application sets a single first diode D1 and a single second diode D2 in a boost circuit, that is, only retains the first diode D1 included in a boost circuit and the second diode D2 included in a boost circuit in the first boost circuit 01 and the second boost circuit 02. This can not only solve the over-temperature failure problem and improve the boost conversion efficiency, but also simplify the number of components, reduce the structural complexity and cost of the power converter, and facilitate the layout and packaging within the module.

[0097] For example, Figure 3Taking the structure shown in the figure, the DC source is a PV string as an example, and the working principle of the protection switch 04 in the power converter recorded in the embodiment of the present application is briefly described as follows:

[0098] Combination Figure 4 , when the input polarity of the first PV string PV1 is reversed and the input polarity of the second PV string PV2 is positively connected, that is, when the positive pole of the first PV string PV1 is connected to the negative pole of the input end of the first boost circuit 01, the negative pole of the first PV string PV1 is connected to the positive pole of the input end of the first boost circuit 01, and the positive pole of the second PV string PV2 is connected to the positive pole of the input end of the second boost circuit 02, and the negative pole of the second PV string PV2 is connected to the negative pole of the input end of the second boost circuit 02, the first PV string PV1 will generate a short-circuit current. And the short-circuit current will flow from the negative pole of the input end of the first PV string PV1 through Figure 4 The two current paths shown flow to the positive pole of the input end of the first PV string PV1: (1) the body diode D01 and the inductor L01 of the power switch tube T01 in the first boost circuit 01; (2) the first diode D1 and the inductor L01 included in the protection switch 04. That is, the short-circuit current generated by the reverse polarity of the input of the first PV string PV1 will flow through the body diode D01, the first diode D1 and the inductor L01 of the power switch tube T01. Because when the same current flows, the conduction voltage drop of the body diode D01 is greater than the conduction voltage drop of the first diode D1, it can be known that the current can mainly flow through the first diode D1 and the inductor L01, that is, mainly through path (2). In this way, it can be avoided that the body diode D01 generates a lot of heat due to the flow of a large current, which causes the power switch tube T01 to overheat and fail.

[0099] Combination Figure 5 , when the input polarity of the first PV string PV1 is positively connected and the input polarity of the second PV string PV2 is reversely connected, that is, when the positive pole of the first PV string PV1 is connected to the positive pole of the input end of the first boost circuit 01, the negative pole of the first PV string PV1 is connected to the negative pole of the input end of the first boost circuit 01, and the positive pole of the second PV string PV2 is connected to the negative pole of the input end of the second boost circuit 02, and the negative pole of the second PV string PV2 is connected to the positive pole of the input end of the second boost circuit 02, the second PV string PV2 will generate a short-circuit current. And the short-circuit current will flow from the negative pole of the input end of the second PV string PV2 through Figure 5The two current paths shown flow to the positive pole of the input end of the second PV string PV2: (1) the body diode D02 and the inductor L02 of the power switch tube T02 in the second boost circuit 02; (2) the first diode D1 and the inductor L01 included in the protection switch 04. That is, the short-circuit current generated by the reverse polarity of the input of the second PV string PV2 will flow through the body diode D02 of the power switch tube T02, the first diode D1, the inductor L01 and the inductor L02. Because when the same current flows, the conduction voltage drop of the body diode D02 is greater than the conduction voltage drop of the first diode D1, it can be known that the current can mainly flow through the first diode D1 and the inductor L01, that is, mainly through path (2). In this way, it can be avoided that the body diode D02 generates a lot of heat due to the flow of a large current, which causes the power switch tube T02 to overheat and fail. That is, when the input polarity of the first PV string PV1 is positively connected and the input polarity of the second PV string PV2 is reversely connected, the current path of the short-circuit current can be the same as the current path when the input polarity of the first PV string PV1 is reversely connected and the input polarity of the second PV string PV2 is positively connected.

[0100] exist Figure 4 and Figure 5 On this basis, it can be understood that when the input polarity of the first PV string PV1 and the input polarity of the second PV string PV2 are both reversed, the short-circuit current can also mainly flow through Figure 4 The first diode D1 and the inductor L01 in the current path (2) shown flow through. That is, the current path of the short-circuit current generated at this time is the same as the current path when the input polarity of the first PV string PV1 is reversed, and the input polarity of the second PV string PV2 is forwardly connected. In this way, not only can the body diode D01 be prevented from generating a large amount of heat due to a large current flowing through it, causing the power switch tube T01 to fail due to over-temperature, but also the body diode D02 can be prevented from generating a large amount of heat due to a large current flowing through it, causing the power switch tube T02 to fail due to over-temperature. That is, the embodiment of the present application sets a protection switch 04 in parallel in one of the two Boost circuits connected in staggered parallel, that is, when the input polarity of the PV string connected to any Boost circuit is reversed, the power switch tube T in each Boost circuit can be effectively prevented from failing due to over-temperature, and the circuit structure is simple.

[0101] For example, Figure 3 Taking the structure shown in the figure as an example, the DC source is a PV string, and the working principle of the bypass switch 05 in the power converter recorded in the embodiment of the present application is briefly described as follows:

[0102] Combination Figure 6When the first boost circuit 01 and the second boost circuit 02 connected in parallel enter the single-stage mode, that is, the power switch tube T01 in the first boost circuit 01 and the power switch tube T02 in the second boost circuit 02 are both turned off and no wave is generated (i.e., the wave is blocked), in any boost circuit, the current of the DC power provided by the input end can be discharged from the positive electrode of the input end through Figure 6 The three current paths shown flow to the positive pole of the input terminal: (1) the inductor L01 in the first boost circuit 01 and the diode D01 included in the freewheeling switch K01; (2) the inductor L02 in the second boost circuit 02 and the diode D02 included in the freewheeling switch K02; (3) the second diode D2 included in the bypass switch 05. That is, the input current will flow through the second diode D2, the inductor L01, the diode D01, the inductor L02 and the diode D02. Because when the same current flows, the conduction voltage drop of the diode D01 and the diode D02 is greater than the conduction voltage drop of the second diode D2, it can be known that the current can mainly flow through the second diode D2, that is, it mainly flows directly through the path (3). In this way, the energy loss of the first boost circuit 01 and the second boost circuit 02 can be reduced, thereby improving the boost conversion efficiency.

[0103] It is understandable that the power converter may also generally include a drive circuit, which may output a pulse width modulation (PWM) signal to the power switch tube to control the switching of the power switch tube. The PWM signal is also called a PWM wave. Accordingly, not emitting a wave or blocking a wave may mean that the drive circuit stops outputting a PWM wave, thereby controlling the power switch tube to turn off.

[0104] It can also be understood that, generally, when the input voltage provided at the input end of the boost circuit exceeds the voltage threshold, that is, when the input voltage is relatively large, the boost circuit will be controlled to enter the single-stage mode to prevent the input voltage from being too high and causing damage to the circuit. The voltage threshold may be pre-stored in the drive circuit so that the drive circuit can block the wave when detecting that the input voltage exceeds the voltage threshold, thereby controlling the boost circuit to enter the single-stage mode.

[0105] In summary, an embodiment of the present application provides a power converter. The power converter includes two boost circuits connected in parallel, a power conversion circuit and a protection switch. Among them, the two boost circuits connected in parallel can work in an interlaced manner to perform boost conversion processing on the DC power provided by a DC source such as a PV string or an energy storage battery, and the conversion efficiency is high. The power conversion circuit can convert the boosted DC power into AC power and output it to the power grid or load to provide reliable power supply to the power grid or load. The protection switch is connected in parallel with the power switch tube included in one of the two boost circuits. Because the conduction voltage drop of the protection switch is less than the conduction voltage drop of the body diode of the parallel power switch tube, the short-circuit current generated by the reverse polarity of the input of the DC source can flow mainly through the protection switch rather than the body diode of the parallel power switch tube. Furthermore, the voltage drop of the body diode can be effectively reduced to avoid the body diode generating a large amount of heat and causing the parallel power switch tube to fail due to overtemperature.

[0106] The present application also provides an energy storage system. Figure 7 As shown, the energy storage system includes: a first energy storage battery 10, a second energy storage battery 20, and a power converter 00 as described in the above embodiment.

[0107] The first boost circuit 01 in the power converter 00 is used to boost the direct current provided by the first energy storage battery 10 .

[0108] The second boost circuit 02 in the power converter 00 is used to boost the direct current provided by the second energy storage battery 20 .

[0109] In addition, combined Figure 1 and Figure 7 It can also be seen that the input end of the first boost circuit 01 in the power converter 00 can be connected to the first energy storage battery 10, and the input end of the second boost circuit 02 in the power converter 00 can be connected to the second energy storage battery 20. In addition, the output end of the first boost circuit 01 and the output end of the second boost circuit 02 in the power converter 00 can both be connected to the input end of the power conversion circuit 03, and the output end of the power conversion circuit 03 can be connected to the power grid / load. In addition, the power converter 03 can convert the direct current output by the first boost circuit 01 and the second boost circuit 02 into alternating current, and output the converted alternating current to the power grid / load to supply power to the power grid / load.

[0110] Of course, in some other embodiments, the power converter 00 is not limited to including two boost circuits connected in parallel, and accordingly, the energy storage system is not limited to including two energy storage batteries. For example, based on the above description, the power converter 00 may also include three or more boost circuits connected in parallel, and accordingly, the energy storage system may also include three or more energy storage batteries, which are connected to each boost circuit in a one-to-one correspondence.

[0111] It can be understood that since the energy storage system has basically the same implementation method and technical effects as the power converter described in the above embodiments, for the purpose of brevity, the implementation method and technical effects of the energy storage system will not be repeatedly described here.

[0112] In the embodiments of the present application, the terms "first", "second" and "third" are used for descriptive purposes only and should not be understood as indicating or implying relative importance. The term "at least one" means one or more, and "plurality" means two or more.

[0113] In the embodiments of the present application, the term "and / or" is only a description of the association relationship of the associated objects, indicating that there can be three relationships. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " in this article generally indicates that the associated objects before and after are in an "or" relationship.

[0114] The above is only an optional implementation of the present application, but the protection scope of the present application is not limited thereto. Any technician familiar with the technical field can easily think of various equivalent modifications or replacements within the technical scope disclosed in the present application, and these modifications or replacements should be included in the protection scope of the present application. Therefore, the protection scope of the present application shall be based on the protection scope of the claims.

Claims

1. A power converter, characterized in that: The power converter comprises: a first boost circuit and a second boost circuit connected in parallel, a power conversion circuit, and a protection switch; The first boost circuit and the second boost circuit are both used to boost the DC power output by the DC source and transmit it to the power conversion circuit, and the power conversion circuit is used to convert the boosted DC power into AC power and output it to the power grid or load; The protection switch is connected in parallel with the power switch tube in the first boost circuit, and a conduction voltage drop of the protection switch is smaller than a conduction voltage drop of a body diode of the power switch tube in the first boost circuit.

2. The power converter according to claim 1, characterized in that: The protection switch includes: a first diode, wherein a conduction direction of the first diode is the same as a conduction direction of the body diode.

3. The power converter according to claim 2, characterized in that: The first diode is a silicon diode.

4. The power converter according to any one of claims 1 to 3, characterized in that: The power converter further includes: a bypass switch; One end of the bypass switch is connected to the input end of the first boost circuit, the other end of the bypass switch is connected to the output end of the first boost circuit, and the on-state voltage drop of the bypass switch is smaller than the on-state voltage drop of the freewheeling switch in the first boost circuit; or, One end of the bypass switch is connected to the input end of the second boost circuit, the other end of the bypass switch is connected to the output end of the second boost circuit, and the on-state voltage drop of the bypass switch is smaller than the on-state voltage drop of the freewheeling switch in the second boost circuit.

5. The power converter according to claim 4, characterized in that: The bypass switch includes: a second diode, an anode of the second diode is connected to the input end, and a cathode of the second diode is connected to the output end.

6. The power converter according to claim 5, characterized in that: The second diode is a silicon diode.

7. The power converter according to any one of claims 4 to 6, characterized in that: The protection switch and the bypass switch are connected to the same boost circuit of the first boost circuit and the second boost circuit.

8. The power converter according to any one of claims 4 to 7, characterized in that: The bypass switch, the protection switch, the freewheeling switch and the power switch tube in the first boost circuit, and the freewheeling switch and the power switch tube in the second boost circuit are packaged in one module.

9. The power converter according to any one of claims 1 to 8, characterized in that: The freewheeling switch in the first boost circuit and the freewheeling switch in the second boost circuit are both silicon carbide diodes; The power switch tube in the first boost circuit and the power switch tube in the second boost circuit are both silicon carbide field effect tubes.

10. An energy storage system, characterized in that: The energy storage system comprises: a first energy storage battery, a second energy storage battery, and a power converter as claimed in any one of claims 1 to 9; The first boost circuit in the power converter is used to boost the DC power provided by the first energy storage battery; The second boost circuit in the power converter is used to boost the direct current provided by the second energy storage battery.

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