Power converter and photovoltaic system

Abstract

The utility model relates to the field of photovoltaic systems, in particular to a power converter and a photovoltaic system. A power converter comprising: a plurality of input terminals and output terminals; the plurality of power modules are respectively connected with the plurality of input ends in a one-to-one correspondence manner, and the outputs of the plurality of power modules are connected to the output end in series; the control module is connected with the plurality of power modules and controls the plurality of power modules; a plurality of first ends of the auxiliary power module are respectively connected with the input ends in a one-to-one correspondence manner, a second end of the auxiliary power module is connected with the control module, a third end of the auxiliary power module is connected with a reference ground, and the auxiliary power module is used for taking power from at least one input end and supplying power to the control module. The plurality of first ends of the auxiliary power module are respectively connected with the plurality of input ends in a one-to-one correspondence manner, so that power can be taken from at least one input end, redundant power supply of the multi-path power module is realized, and the reliability of the photovoltaic system is improved.

Description

Technical Field

[0001] The present application relates to the field of photovoltaic systems, and in particular to a power converter and a photovoltaic system. Background Art

[0002] Due to the renewable and clean nature of solar energy, photovoltaic power generation technology has developed rapidly. String photovoltaic systems have been widely used in the field of photovoltaic power generation due to their mature technology, high conversion efficiency, and low price. At the same time, string photovoltaic systems have poor tracking performance for photovoltaic modules in complex shadow environments, making it difficult to achieve the highest MPPT efficiency. Therefore, the existing solution is to configure component-level MPPT equipment for each photovoltaic DC power supply, such as an optimizer. Each optimizer can perform MPPT tracking on a single photovoltaic module or even a battery substring separately, greatly improving the MPPT tracking efficiency.

[0003] Existing multi-input optimizers are generally configured with two input terminals, connected to two PV panels. The auxiliary power module of the optimizer draws power from one input terminal to power its internal circuit. However, when the PV panel connected to the input terminal fails or is abnormally blocked, the auxiliary power module cannot draw power, causing the optimizer to fail to work normally. Utility Model Content

[0004] Based on this, it is necessary to provide a power converter and a photovoltaic system to address the above technical problems.

[0005] In a first aspect, an embodiment of the present utility model provides a power converter, comprising:

[0006] Multiple inputs and outputs;

[0007] A plurality of power modules are connected to the plurality of input terminals one by one, respectively, and the outputs of the plurality of power modules are connected in series to the output terminal;

[0008] A control module, connected to the multiple power modules, and controlling the multiple power modules;

[0009] The auxiliary power module has multiple first ends connected to the multiple input ends one by one, a second end connected to the control module, and a third end connected to the reference ground, and is used to draw power from at least one of the input ends and supply power to the control module.

[0010] In one embodiment, the plurality of first terminals of the auxiliary power module are respectively connected to the positive input terminals among the plurality of input terminals, and the reference ground is the lowest point of the DC voltage of the power converter;

[0011] Or, the multiple first terminals of the auxiliary power module are respectively connected to the negative input terminal of the multiple input terminals, and the reference ground is the highest point of the DC voltage of the power converter.

[0012] In one embodiment, the auxiliary power module includes:

[0013] A power selection unit, connected to the plurality of first ends, and used to select an input end for power supply;

[0014] The auxiliary power supply unit is connected to the power selection unit and supplies power to the control module according to the power provided by the power selection unit.

[0015] In one embodiment, the power selection unit includes:

[0016] A plurality of diodes have anodes connected to the plurality of first ends one by one, and cathodes connected to the auxiliary power supply units.

[0017] In one embodiment, the power selection unit further includes:

[0018] at least one switching element connected between the cathode of the corresponding diode and the auxiliary power supply unit;

[0019] A voltage detection circuit is connected to the at least one switching element and at least one input terminal, and is used to detect the input voltage of the corresponding input terminal. When the input voltage of the input terminal is greater than the corresponding threshold value, at least one switching element is controlled to be disconnected to disconnect the power supply path of at least one other input terminal, so as to draw power from the input terminal.

[0020] In one embodiment, the switch element is a normally-on switch element.

[0021] In one embodiment, the voltage detection circuit includes a voltage dividing unit, a reference voltage source and a comparator;

[0022] The voltage divider unit is connected in series between the corresponding input terminal and the reference ground, the intermediate node of the voltage divider unit is connected to the inverting input terminal of the comparator, the reference voltage source is connected between the non-inverting input terminal of the comparator and the reference ground, and the output terminal of the comparator is connected to the corresponding switching element.

[0023] In one embodiment, the power module includes any one of a buck circuit, a boost circuit, and a buck-boost circuit.

[0024] In one embodiment, the power module comprises a shutdown circuit, wherein the shutdown circuit comprises at least one switching element for shutting down an output of the power module.

[0025] In a second aspect, an embodiment of the utility model provides a photovoltaic system, comprising a plurality of photovoltaic DC power supplies and a power converter as described in the first aspect and connected to the plurality of photovoltaic DC power supplies.

[0026] Compared with the related art, the multiple first ends for drawing power of the auxiliary power module of the present application are respectively connected to the multiple input ends of the power converter in a one-to-one correspondence, so that power can be drawn from at least one input end to achieve redundant power supply, thereby improving the reliability and wiring freedom of the power converter. When the photovoltaic DC power supply connected to any input end fails or is abnormally blocked, the auxiliary power module can draw power from the photovoltaic DC power supply connected to other input ends, thereby avoiding the situation where the auxiliary power module cannot draw power and the power converter cannot work normally. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 A schematic structural diagram of a power converter according to an embodiment of the present utility model;

[0028] Figure 2 A schematic structural diagram of a power converter according to another embodiment of the present utility model;

[0029] Figure 3 A schematic circuit diagram of a power converter according to a first embodiment of the present utility model;

[0030] Figure 4 A schematic circuit structure diagram of a power module according to an embodiment of the present utility model;

[0031] Figure 5 A schematic circuit diagram of a power converter according to a second embodiment of the present utility model;

[0032] Figure 6 A schematic circuit structure diagram of a voltage detection circuit according to an embodiment of the present utility model;

[0033] Figure 7 is a schematic circuit structure diagram of a power converter according to a third embodiment of the present utility model;

[0034] Figure 8 This is a structural diagram of a photovoltaic system according to an embodiment of the present utility model. DETAILED DESCRIPTION

[0035] In order to make the purpose, technical solutions and advantages of the present application clearer, the present application is described and illustrated below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not intended to limit the present application. Based on the embodiments provided in the present application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present application. In addition, it can also be understood that although the efforts made in this development process may be complex and lengthy, for ordinary technicians in the field related to the contents disclosed in the present application, some changes such as design, manufacturing or production based on the technical contents disclosed in the present application are only conventional technical means, and should not be understood as insufficient contents disclosed in the present application.

[0036] Reference to "embodiments" in this application means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present application. The appearance of the phrase in various locations in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those of ordinary skill in the art that the embodiments described in this application may be combined with other embodiments without conflict.

[0037] Unless otherwise defined, the technical terms or scientific terms involved in this application should be understood by people with ordinary skills in the technical field to which this application belongs. The words "one", "a", "a", "the" and the like involved in this application do not indicate a quantitative limitation, and may represent the singular or plural. The terms "include", "comprise", "have" and any of their variations involved in this application are intended to cover non-exclusive inclusions; for example, a process, method, system, product or device that includes a series of steps or modules (units) is not limited to the listed steps or units, but may also include steps or units that are not listed, or may also include other steps or units inherent to these processes, methods, products or devices. The words "connect", "connected", "coupled" and the like involved in this application are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. The "multiple" involved in this application refers to greater than or equal to two. "And / or" describes the association relationship of 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. The terms "first", "second", "third" and the like involved in the present application are merely used to distinguish similar objects and do not represent a specific ordering of the objects.

[0038] The present application embodiment provides a power converter, such as Figure 1As shown, it includes: multiple input terminals and output terminals, the multiple input terminals respectively have corresponding positive and negative input terminals (PVA±, ..., PVN±), and the output terminals have positive and negative output terminals OUT±; multiple power modules (a first power module, a second power module, ..., an Nth power module), which are respectively connected to the multiple input terminals one by one, and the outputs of the multiple power modules are connected in series to the output terminals; a control module 204, which is connected to the multiple power modules and controls the multiple power modules; an auxiliary power module 203, whose multiple first terminals are respectively connected to the multiple input terminals one by one, the second terminal is connected to the control module 204, and the third terminal is connected to the reference ground, for taking power from at least one input terminal and supplying power to the control module 204.

[0039] Since the multiple first terminals for drawing power of the auxiliary power module 203 are connected to the multiple input terminals one by one, and each input terminal is connected to a photovoltaic DC power source, the auxiliary power module 203 can draw power from at least one input terminal of the power converter. When the photovoltaic DC power source connected to any input terminal fails or is abnormally blocked, the auxiliary power module 203 can draw power from the photovoltaic DC power source connected to other input terminals, thereby avoiding the situation where the auxiliary power module 203 cannot draw power and the power converter cannot work normally, and at the same time, the wiring freedom of the power converter is improved.

[0040] Among them, multiple first ends of the auxiliary power module 203 are respectively connected to the positive input terminals among the multiple input ends, and the reference ground is the lowest point of the DC voltage of the power converter; or, multiple first ends of the auxiliary power module 203 are respectively connected to the negative input terminals among the multiple input ends, and the reference ground is the highest point of the DC voltage of the power converter. Figure 1 In the example, the lowest point of the DC voltage of the power converter is used as the reference ground of the auxiliary power module 203, that is, the negative input terminal PVN- or the negative output terminal OUT- of the power converter is used as the reference ground.

[0041] It should be noted that the photovoltaic DC power source can be a single photovoltaic module, multiple photovoltaic modules connected in series and / or in parallel, or multiple photovoltaic cell substrings connected in series and / or in parallel.

[0042] In some embodiments, the power module includes any one of a buck circuit, a boost circuit, and a buck-boost circuit.

[0043] In some embodiments, the power module includes a shutdown circuit for quickly cutting off the power output of the photovoltaic DC power source.

[0044] Figure 2This is a schematic structural diagram of a power converter according to another embodiment of the present invention. In this embodiment, the power converter includes a first input terminal, a second input terminal, an output terminal, a first power module 201 , a second power module 202 , an auxiliary power module 203 and a control module 204 .

[0045] In this embodiment, the two first terminals of the auxiliary power module 203 for drawing power are respectively connected to the positive input terminal PVA+ of the first input terminal and the positive input terminal PVB+ of the second input terminal, the second terminal for power supply is connected to the control module 204, and the third terminal is connected to the reference ground (PVB-). The auxiliary power module 203 can draw power from the first input terminal and / or the second input terminal. When one of the input terminals cannot provide power to the auxiliary power module 203, power can be drawn from the other input terminal, and the photovoltaic DC power supply connected to the input terminal is used for power supply.

[0046] It should be noted that the two first ends of the auxiliary power module 203 can also be connected to the negative input terminal PVA- of the first input end and the negative input terminal PVB- of the second input end, respectively, and the high and low points of the DC voltage of the power converter are used as reference grounds, that is, the positive input terminal PVA+ of the first input end or the positive output terminal OUT+ of the power converter is used as a reference ground.

[0047] The control module 204 includes a controller 2041 and a drive unit 2042. The second end of the auxiliary power module 203 for power supply is connected to the controller 2041 and the drive unit 2042 respectively to supply power to both. The controller 2041 outputs a control signal to the drive unit 2042, and the drive unit 2042 outputs a drive signal according to the control signal to drive each power module respectively.

[0048] In specific implementation, the controller 2041 can be any one of a microcontroller unit (MCU), a central processing unit (CPU), a field programmable gate array (FPGA), and a digital signal processor (DSP). Of course, the specific form of the controller is not limited to the above examples.

[0049] In this embodiment, the first power module 201 and the second power module 202 are connected in an asymmetric structure, that is, the negative input terminal PVA- of the first input end of the first power module 201 and its negative output terminal OUTA- are directly connected or connected through a resistor with a very small resistance value; the negative input terminal PVB- of the second input end of the second power module 202 and its negative output terminal OUTB- are also directly connected or connected through a resistor with a very small resistance value.

[0050] It should be noted that the first power module 201 and the second power module 202 can also be connected in a symmetrical structure. For example, the first power module 201 and the second power module 202 have the same structure, and the negative input terminal PVA- of the first power module 201 and its negative output terminal OUTA- are directly connected or connected through a resistor with a very small resistance value; at the same time, the positive input terminal PVB+ of the second power module 202 and its positive output terminal OUTB+ are directly connected or connected through a resistor with a very small resistance value.

[0051] Figure 3 The schematic circuit structure diagram of the power converter of the first embodiment of the utility model. In this embodiment, the auxiliary power module 203 includes: a power selection unit 2031, connected to a plurality of first ends, for selecting an input end for power supply; an auxiliary power supply unit 2032, connected to the power selection unit 2031, and supplying power to the control module 204 according to the power provided by the power selection unit 2031.

[0052] The power selection unit 2031 includes: a first diode D1 and a second diode D2 , whose anodes are connected to the two first ends one by one, and whose cathodes are connected to the input anode of the auxiliary power supply unit 2032 .

[0053] The input negative pole of the auxiliary power supply unit 2032 is connected to the reference ground as the third end of the auxiliary power module 203, and the output end of the auxiliary power supply unit 2032 is used as the second end of the auxiliary power module 203 to supply power to the controller 2041 and the driving unit 2042 respectively.

[0054] The driving unit 2042 includes: a first driving circuit and a second driving circuit, which are respectively connected to the first power module 201 and the second power module 202 to drive the corresponding power modules.

[0055] The first driving circuit and the second driving circuit include a driving chip and peripheral devices thereof.

[0056] The auxiliary power supply unit 2032 includes a DC conversion circuit such as a flyback circuit, and can provide power supply voltages of different voltage levels.

[0057] The first power module 201 is a buck circuit, including switch tubes S10, S20, capacitors Cin1, Cout1 and inductor L10. The switch tube S10 and the inductor L10 are connected in sequence between the positive input terminal PVA+ of the first input end and the positive output terminal OUT+ of the power converter, the capacitor Cin1 is connected in parallel to the first input end, the capacitor Cout1 is connected in parallel to the output end of the first power module 201, and the switch tube S20 is connected between the common end of the switch tube S10 and the inductor L10 and the negative input terminal PVA- of the first input end. The control ends of the switch tubes S10 and S20 are connected to the first drive circuit.

[0058] The second power module 202 is also a buck circuit, including switches S11, S21, capacitors Cin2, Cout2 and inductor L11. Its connection is similar to that of the first power module 201, and will not be described in detail.

[0059] It should be noted that the first power module 201 and the second power module 202 may also be a boost circuit, a buck-boost circuit, etc., which can transform the power output by the photovoltaic DC power supply.

[0060] In some embodiments, the first power module 201 and the second power module 202 include a shut-down circuit for quickly cutting off the power output of the photovoltaic DC power sources PVA and PVB.

[0061] like Figure 4 As shown, the shutdown circuit includes switch tubes S40, S50, capacitors Cin4, and Cout4. The switch tube S40 is connected between the input end of the shutdown circuit (that is, the input end of the power converter) and the output end of the shutdown circuit, the capacitor Cin4 is connected in parallel to the input end of the shutdown circuit, and the switch tube S50 and the capacitor Cout4 are connected in parallel to the output end of the shutdown circuit. The control ends of the switch tubes S40 and S50 are connected to the drive unit 2042. Optionally, the switch tube S50 can be replaced by a diode.

[0062] In some implementations, the controller 2041 may control the first power module 201 and the second power module 202 to perform maximum power point tracking on the correspondingly connected photovoltaic DC power sources, respectively.

[0063] In this embodiment, the specific working process of the auxiliary power module 203 is as follows:

[0064] 1) When the photovoltaic DC power supplies PVA and PVB connected to the first input terminal and the second input terminal are both normal, the first diode D1 is turned off, the second diode D2 is turned on, and the power generated by the photovoltaic DC power supplies PVA and PVB is supplied to the auxiliary power supply unit 2032 through the second diode D2. Specifically, the power supply current starts from the positive input terminal PVA+ of the first input terminal, passes through the second diode D2, the auxiliary power supply unit 2032, and the capacitor Cout2 of the second power module 202, and returns to the negative input terminal PVA- of the first input terminal. The input voltage obtained by the auxiliary power supply unit 2032 is approximately equal to the sum of the output voltage of the photovoltaic DC power supply PVA (i.e., the input voltage Vin1 of the first input terminal) and the output voltage Vout2 of the second power module 202.

[0065] 2) When the photovoltaic DC power source PVA is not powered, the second diode D2 is turned off and the first diode D1 is turned on. The power output by the photovoltaic DC power source PVB will be supplied to the auxiliary power supply unit 2032 through the first diode D1, and the input voltage obtained by the auxiliary power supply unit 2032 is approximately equal to the output voltage of the photovoltaic DC power source PVB (i.e., the input voltage Vin2 of the second input terminal).

[0066] 3) When the photovoltaic DC power source PVB is not powered, the first diode D1 is turned off, the second diode D2 is turned on, and the power output by the photovoltaic DC power source PVA will supply power to the auxiliary power supply unit 2032 through the second diode D2. Specifically, the power supply current starts from the positive input terminal PVA+ of the first input end, passes through the second diode D2, the auxiliary power supply unit 2032, the body diode of the switch tube S21, and the inductor L11, and returns to the negative input terminal PVA- of the first input end. The input voltage obtained by the auxiliary power supply unit 2032 is approximately equal to the output voltage of the photovoltaic DC power source PVA (that is, the input voltage Vin1 of the first input end).

[0067] It should be noted that the switch tube S10 and the inductor L10 can also be connected between the negative input terminal PVA- of the first input end and the negative output terminal OUTA- of the first power module 201, and the power supply principle of the auxiliary power module 203 is similar to that of the above embodiment. The switch tube S11 and the inductor L11 can also be connected between the negative input terminal PVB- of the second input end and the negative output terminal OUTB- of the second power module 202, and the power supply principle of the auxiliary power module 203 is similar to that of the above embodiment.

[0068] In some embodiments, the power selection unit 2031 also includes: at least one switching element, connected between the cathode of the corresponding diode and the auxiliary power supply unit; a voltage detection circuit, connected to at least one switching element and at least one input terminal, for detecting the input voltage of the corresponding input terminal, and when the input voltage of the input terminal is greater than the corresponding threshold value, controlling at least one switching element to disconnect to disconnect the power supply path of at least one other input terminal, so as to draw power from the input terminal, thereby avoiding the input voltage of the auxiliary power supply unit being too high.

[0069] Figure 5 This is a schematic circuit diagram of a power converter according to the second embodiment of the utility model. In this embodiment, the power selection unit 2031 also includes a first switch element Q1, which is connected between the cathode of the second diode D2 and the auxiliary power supply unit 2032. The voltage detection circuit is used to detect the output voltage of the photovoltaic DC power supply PVB (i.e., the input voltage Vin2 of the second input terminal). When the input voltage Vin2 is greater than the corresponding threshold, the first switch element Q1 is controlled to be turned off, the power supply channel for taking power from the first input terminal is closed, and the power supply path of the first input terminal is disconnected to take power from the second input terminal.

[0070] In this embodiment, the first switch element Q1 is used to shut down the path of drawing power from the photovoltaic DC power source PVA connected to the first input terminal when both dual-input photovoltaic DC power sources are available, thereby preventing the input voltage of the auxiliary power supply unit 2032 from being too high.

[0071] The first switch element Q1 can be a normally-on switch device, such as a depletion-type transistor, including but not limited to JFET (Junction Field-Effect Transistor), depletion-type MOSFET (Metal-oxide Semiconductor Field Effect Transistor), depletion-type GaN transistor and other normally-on controllable devices.

[0072] In this embodiment, the first switching element Q1 remains on when the gate voltage is 0, and is turned off when the gate voltage is negative. It is controlled by the voltage detection circuit and is used to close the power supply path of the photovoltaic DC power supply PVA connected to the first input terminal when the photovoltaic DC power supply PVB is supplying power normally (the input voltage Vin2 is greater than the corresponding threshold).

[0073] In other embodiments, the first switch element Q1 may also be a normally-off switch device.

[0074] In this embodiment, if Figure 6 As shown, the voltage detection circuit includes a first resistor R1, a second resistor R2, a reference voltage source Vref and a comparator A. The first resistor R1 and the second resistor R2 are connected in series between the positive input terminal PVB+ of the second input terminal and the reference ground, the middle node of the first resistor R1 and the second resistor R2 is connected to the inverting input terminal of the comparator A, the reference voltage source Vref is connected between the non-inverting input terminal of the comparator A and the reference ground to provide a reference value, and the output terminal of the comparator A is connected to the first switch element Q1 to output a control signal V Q1 To control the working state of the first switching element Q1.

[0075] The first resistor R1 and the second resistor R2 form a voltage divider unit to obtain a voltage divider value representing the input voltage of the second input terminal. The comparator A compares the voltage divider value with a reference value. When the voltage divider value is greater than the reference value (that is, when the input voltage Vin2 is greater than the corresponding threshold value), the first switch element Q1 is controlled to be disconnected.

[0076] In this embodiment, the specific working process of the auxiliary power module 203 is as follows:

[0077] 1) When the photovoltaic DC power supplies PVA and PVB connected to the first input terminal and the second input terminal are both normal, the first diode D1 is turned off, the second diode D2 is turned on, and when the voltage detection circuit detects that the input voltage Vin2 of the second input terminal is greater than the corresponding threshold value, the first switch element Q1 is controlled to be disconnected. At the same time, the second diode D2 is turned off and the first diode D1 is turned on, so as to prevent the output voltage of the photovoltaic DC power supply PVA (i.e., the input voltage Vin1 of the first input terminal) and the output voltage Vout2 of the second power module 202 from being superimposed to supply power to the auxiliary power supply unit 2032, thereby preventing the input voltage of the auxiliary power supply unit 2032 from being too high. The first diode D1 is turned on to provide a power supply channel for the auxiliary power supply unit 2032, and the input voltage obtained by the auxiliary power supply unit 2032 is approximately equal to the output voltage of the photovoltaic DC power supply PVB (i.e., the input voltage Vin2 of the second input terminal).

[0078] 2) When the photovoltaic DC power source PVA is not powered, the first diode D1 is turned on and the second diode D2 is turned off. The power output by the photovoltaic DC power source PVB will supply power to the auxiliary power supply unit 2032 through the first diode D1. The input voltage of the auxiliary power supply unit 2032 is approximately equal to the output voltage of the photovoltaic DC power source PVB (i.e., the input voltage Vin2 of the second input terminal).

[0079] 3) When the photovoltaic DC power source PVB is not powered, the output power of the photovoltaic DC power source PVA will be used to power the auxiliary power supply unit 2032 through the second diode D2 and the first switch element Q1. Specifically, the power supply current starts from the positive input terminal PVA+ of the first input end, passes through the second diode D2, the first switch element Q1, the auxiliary power supply unit 2032, the body diode of the switch tube S21, and the inductor L11, and returns to the negative input terminal PVA-. The input voltage obtained by the auxiliary power supply unit 2032 is approximately equal to the output voltage of the photovoltaic DC power source PVA (i.e., the input voltage Vin1 of the first input end).

[0080] Figure 7 This is a schematic circuit structure diagram of a power converter of the third embodiment of the utility model. In this embodiment, the power converter includes a first input terminal, a second input terminal, a third input terminal, an output terminal, a first power module 201, a second power module 202, a third power module 206, an auxiliary power module 203 and a control module 204. The first input terminal has positive and negative input terminals PVA±, the second input terminal has positive and negative input terminals PVB±, and the third input terminal has positive and negative input terminals PVC±. The driving unit 2042 includes a first driving circuit, a second driving circuit and a third driving circuit, which are respectively connected to the first power module 201, the second power module 202 and the third power module 206 in a one-to-one correspondence to drive the switching elements in the correspondingly connected power modules.

[0081] The third power module 206 includes switch tubes S12 and S22, capacitors Cin3 and Cout3, and inductor L12. The connection thereof is similar to that of the first power module 201, and will not be described in detail.

[0082] In this embodiment, the auxiliary power module 203 includes a power selection unit 2031 and an auxiliary power supply unit 2032. The power selection unit 2031 includes a first diode D1, a second diode D2, a third diode D3, a first switch element Q1, a second switch element Q2 and a voltage detection circuit. The positive poles of the first diode D1, the second diode D2 and the third diode D3 are respectively connected to the positive input terminals of the input ends, and the negative pole of the third diode D3 is connected to the positive input pole of the auxiliary power supply unit 2032. The first switch element Q1 is connected between the negative pole of the second diode D2 and the auxiliary power supply unit 2032, and the second switch element Q2 is connected between the negative pole of the first diode D1 and the auxiliary power supply unit 2032.

[0083] The voltage detection circuit is used to detect the output voltage of the photovoltaic DC power supply PVB (i.e., the input voltage Vin2 of the second input terminal) and the output voltage of the photovoltaic DC power supply PVC (i.e., the input voltage Vin3 of the third input terminal). When the input voltages Vin2 and Vin3 are both greater than their respective corresponding thresholds or the input voltage Vin3 is greater than the corresponding threshold, the first switch element Q1 and the second switch element Q2 are controlled to be disconnected, the third diode D3 is turned on, and the auxiliary power supply unit 2032 draws power from the third input terminal; when the input voltage Vin2 is greater than the corresponding threshold and the input voltage Vin3 is less than the corresponding threshold, the first switch element Q1 and the second switch element Q2 are controlled to be turned on. The switching element Q1 is disconnected, the second switching element Q2 remains turned on, the second diode D2 is turned on, the third diode D3 is turned off, and the auxiliary power supply unit 2032 draws power from the second input terminal and the third input terminal; when the input voltages Vin2 and Vin3 are both less than their respective corresponding thresholds, the first switching element Q1 is turned on, the second diode D2 is turned on, the second switching element Q2 remains turned on or turned off, the third diode D3 is turned off, and the supply voltage of the auxiliary power supply unit 2032 is Vout1+Vout2+Vout3, and the auxiliary power supply unit 2032 draws power from the first input terminal, the second input terminal and the third input terminal at the same time.

[0084] In other embodiments, the power converter may have more than three input terminals, corresponding to more than three power modules, and the power supply principles are basically the same, so they will not be described in detail.

[0085] In one embodiment, if Figure 8 As shown, the present application also proposes a photovoltaic system, including a plurality of photovoltaic DC power sources PV and a power converter 10 as in the above embodiment connected to the plurality of photovoltaic DC power sources PV.

[0086] Specifically, the output ends of the power converters 10 may be connected in series and / or in parallel.

[0087] The photovoltaic DC power source PV may be a single photovoltaic module, a plurality of photovoltaic modules connected in series and / or in parallel, or a plurality of photovoltaic cell substrings connected in series and / or in parallel.

[0088] An inverter module or a subsequent device may be directly connected to the subsequent stage of each power module, and the subsequent stage may be applicable to a micro inverter, etc.

[0089] The technical features of the above embodiments may be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0090] The above embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the utility model patent. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the patent of the present application shall be subject to the attached claims.

Claims

1. A power converter, characterized in that: include: Multiple inputs and outputs; A plurality of power modules are connected to the plurality of input terminals one by one, respectively, and the outputs of the plurality of power modules are connected in series to the output terminal; A control module, connected to the multiple power modules, and controlling the multiple power modules; The auxiliary power module has multiple first ends connected to the multiple input ends one by one, a second end connected to the control module, and a third end connected to the reference ground, and is used to draw power from at least one of the input ends and supply power to the control module.

2. The power converter according to claim 1, characterized in that: The plurality of first terminals of the auxiliary power module are respectively connected to the positive input terminals among the plurality of input terminals, and the reference ground is the lowest point of the DC voltage of the power converter; Or, the multiple first terminals of the auxiliary power module are respectively connected to the negative input terminal of the multiple input terminals, and the reference ground is the highest point of the DC voltage of the power converter.

3. The power converter according to claim 1, characterized in that: The auxiliary power module comprises: A power selection unit, connected to the plurality of first ends, and used to select an input end for power supply; The auxiliary power supply unit is connected to the power selection unit and supplies power to the control module according to the power provided by the power selection unit.

4. The power converter according to claim 3, characterized in that: The power selection unit comprises: A plurality of diodes have anodes connected to the plurality of first ends one by one, and cathodes connected to the auxiliary power supply units.

5. The power converter according to claim 4, characterized in that: The power selection unit also includes: at least one switching element connected between the corresponding diode and the auxiliary power supply unit; A voltage detection circuit is connected to the at least one switching element and at least one input terminal, and is used to detect the input voltage of the corresponding input terminal. When the input voltage of the input terminal is greater than the corresponding threshold value, at least one switching element is controlled to be disconnected to disconnect the power supply path of at least one other input terminal, so as to draw power from the input terminal.

6. The power converter according to claim 5, characterized in that: The switch element is a normally-on switch element.

7. The power converter according to claim 5, characterized in that: The voltage detection circuit includes a voltage dividing unit, a reference voltage source and a comparator; The voltage divider unit is connected in series between the corresponding input terminal and the reference ground, the intermediate node of the voltage divider unit is connected to the inverting input terminal of the comparator, the reference voltage source is connected between the non-inverting input terminal of the comparator and the reference ground, and the output terminal of the comparator is connected to the corresponding switching element.

8. The power converter according to claim 1, characterized in that: The power module includes any one of a buck circuit, a boost circuit, and a buck-boost circuit.

9. The power converter according to claim 1, characterized in that: The power module includes a shutdown circuit including at least one switching element for shutting down an output of the power module.

10. A photovoltaic system, characterized in that: The invention comprises a plurality of photovoltaic direct current power sources and a power converter as claimed in any one of claims 1 to 9 connected to the plurality of photovoltaic direct current power sources.

Images