Temperature detection circuit of direct current inductor, photovoltaic inverter and method

Abstract

The invention is suitable for the photovoltaic technical field, and provides a temperature detection circuit of a direct current inductor, a photovoltaic inverter and a method, the temperature detection circuit of the direct current inductor comprises a voltage detection filter circuit and a temperature detector; the detection end of the voltage detection filter circuit is connected with the direct current inductor, the output end of the voltage detection filter circuit is connected with the voltage input end of the temperature detector, and the current input end of the temperature detector receives current flowing through the direct current inductor in a Boost circuit; the voltage detection filter circuit is used for detecting the voltage at the two ends of the direct current inductor and filtering the detected voltage; and the temperature detector is used for determining the temperature of the direct current inductor according to the current of the direct current inductor and the filtered voltage. According to the technical scheme, the temperature of the direct-current inductor can be rapidly and accurately measured, and the temperature detection cost of the direct-current inductor is effectively reduced.

Description

Technical Field

[0001] The present invention belongs to the field of photovoltaic technology, and in particular relates to a temperature detection circuit of a direct current inductor, a photovoltaic inverter and a method. Background Art

[0002] The working circuit of the photovoltaic inverter is equipped with multiple inductors. The inductor is one of the most critical components of the photovoltaic inverter, and its main functions include energy storage, voltage boost, filtering, and EMI elimination.

[0003] However, for current photovoltaic inverters, due to factors such as product cost and system complexity, the temperature of the DC inductor is generally not measured. During the research and development process, only the temperature of the DC inductor under normal working conditions is tested, as long as the temperature of the DC inductor meets the requirements. However, if the temperature of the DC inductor is unknown, once the temperature of the DC inductor is too high, the internal potting glue, casing and other materials of the DC inductor will age and fail, causing damage to the photovoltaic inverter.

[0004] If the temperature of a DC inductor is to be measured, it is necessary to embed thermocouples, thermistors and other devices to measure the temperature of the DC inductor. However, embedding thermocouples, thermistors and other devices will increase system complexity and product cost. Summary of the invention

[0005] The present invention provides a temperature detection circuit for a DC inductor, aiming to quickly and accurately measure the temperature of a DC inductor in a photovoltaic inverter and reduce the cost of temperature measurement.

[0006] The present invention is implemented as follows: a temperature detection circuit of a DC inductor is used to detect the temperature of a DC inductor in a Boost circuit, and the temperature detection circuit of the DC inductor includes a voltage detection filter circuit and a temperature detector; a detection end of the voltage detection filter circuit is connected to the DC inductor, an output end of the voltage detection filter circuit is connected to a voltage input end of the temperature detector, and a current input end of the temperature detector receives a current flowing through the DC inductor in the Boost circuit;

[0007] The voltage detection filter circuit is used to detect the voltage across the DC inductor and filter the detected voltage;

[0008] The temperature detector is used to determine the temperature of the DC inductor according to the current of the DC inductor and the voltage after filtering.

[0009] Furthermore, the voltage detection filter circuit includes a first resistor, a second resistor, a first capacitor and a second capacitor;

[0010] One end of the first resistor is connected to one end of the DC inductor, the other end of the first resistor is connected to one end of the second resistor and one end of the first capacitor, and the other end of the second resistor is connected to one end of the second capacitor and the first voltage input end of the temperature detector;

[0011] The other end of the first capacitor and the other end of the second capacitor are connected to the second voltage input terminal of the temperature detector and the other end of the DC inductor.

[0012] The present invention further provides a photovoltaic inverter, which includes a Boost circuit and a temperature detection circuit of a DC inductor as described in any one of the above items.

[0013] Furthermore, the Boost circuit includes a DC input terminal, a DC output terminal, a DC inductor, a first diode, a first switch tube, a third capacitor and a fourth capacitor;

[0014] One end of the DC inductor is connected to the DC input end and one end of the third capacitor, the other end of the DC inductor is connected to the first end of the first switch tube and the positive electrode of the first diode, and the negative electrode of the first diode is connected to one end of the fourth capacitor and the DC output end;

[0015] The other end of the third capacitor, the second end of the first switch tube and the other end of the fourth capacitor are interconnected.

[0016] Furthermore, the first switch tube includes one of MOSFET, SIC MOSFET or IGBT.

[0017] Furthermore, the Boost circuit includes a DC input terminal, a DC output terminal, a DC inductor, a second switch tube, a third switch tube, a second diode, a third diode, a fifth capacitor, a sixth capacitor and a seventh capacitor;

[0018] One end of the DC inductor is connected to the DC input end and one end of the fifth capacitor, and the other end of the DC inductor is connected to the anode of the second diode and the first end of the second switch tube;

[0019] The cathode of the second diode is connected to the anode of the third diode and one end of the sixth capacitor, and the other end of the sixth capacitor is connected to the second end of the second switch tube and the first end of the third switch tube;

[0020] The cathode of the third diode is connected to one end of the seventh capacitor and the DC output end, and the other end of the fifth capacitor, the second end of the third switch tube and the other end of the seventh capacitor are interconnected.

[0021] Furthermore, the second switch tube and the third switch tube include one of MOSFET, SIC MOSFET or IGBT.

[0022] The present invention also provides a method for detecting the temperature of a DC inductor. The method for detecting the temperature of a DC inductor is applied to a temperature detection circuit of a DC inductor. The temperature detection circuit of the DC inductor includes a voltage detection filter circuit and a temperature detector. The detection end of the voltage detection filter circuit is connected to the DC inductor, the output end of the voltage detection filter circuit is connected to the voltage input end of the temperature detector, and the current input end of the temperature detector receives the current flowing through the DC inductor in the Boost circuit. The method for detecting the temperature of the DC inductor includes:

[0023] Step S1, the voltage detection filter circuit detects the voltage across the DC inductor and performs filtering on the detected voltage;

[0024] Step S2: The temperature detector determines the temperature of the DC inductor according to the current of the DC inductor and the filtered voltage.

[0025] Furthermore, the step S2 comprises:

[0026] Step S21, the temperature detector calculates the average current of the DC inductor according to the current of the DC inductor;

[0027] Step S22, the temperature detector calculates the average voltage of the DC inductor according to the voltage after filtering;

[0028] In step S23, the temperature detector calculates the temperature of the DC inductor according to the average current and the average voltage.

[0029] Furthermore, the step 23 comprises:

[0030] Step S231, the temperature detector calculates the resistance value of the DC inductor according to the average current and the average voltage;

[0031] Step S232, the temperature detector determines the temperature corresponding to the resistance value from a preset relationship table;

[0032] Step S233: taking the determined temperature as the temperature of the DC inductor.

[0033] The technical solution of the present invention detects the voltage across the DC inductor through a voltage detection filter circuit and transmits it to a temperature detector after filtering. The temperature detector determines the temperature of the DC inductor according to the filtered voltage and the current of the DC inductor. With such an arrangement, the real-time temperature of the DC inductor can be quickly obtained when the photovoltaic inverter is stably connected to the grid, ensuring that the photovoltaic inverter can work safely and reliably. Since the temperature detection of the DC inductor does not require the embedding of devices such as thermocouples and thermistors to detect the temperature of the DC inductor, the cost of the temperature detection of the DC inductor can be effectively reduced while obtaining the real-time temperature of the DC inductor. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 1 is a circuit structure block diagram of an embodiment of a temperature detection circuit of a DC inductor according to the present invention;

[0035] Figure 2 yes Figure 1 A schematic diagram of the circuit structure of an embodiment of a medium voltage detection filter circuit;

[0036] Figure 3 Schematic diagram of the waveforms of the current and voltage of the DC inductor of the present invention;

[0037] Figure 4 yes Figure 1 A schematic diagram of the circuit structure of a Boost circuit embodiment;

[0038] Figure 5 yes Figure 1 FIG. 1 is a schematic diagram of a circuit structure of another embodiment of a Boost circuit. DETAILED DESCRIPTION

[0039] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail 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 invention and are not intended to limit the present invention.

[0040] The technical solution of the present invention detects the voltage across the DC inductor through a voltage detection filter circuit and transmits it to a temperature detector after filtering. The temperature detector determines the temperature of the DC inductor according to the filtered voltage and the current of the DC inductor. With such an arrangement, the real-time temperature of the DC inductor can be quickly obtained when the photovoltaic inverter is stably connected to the grid, ensuring that the photovoltaic inverter can work safely and reliably. There is no need to bury sensor devices such as thermocouples and thermistors to detect the temperature of the DC inductor, and the temperature detection cost of the DC inductor is effectively reduced while obtaining the real-time temperature of the DC inductor.

[0041] Embodiment 1

[0042] Reference Figure 1The present embodiment provides a temperature detection circuit of a DC inductor, which is used to detect the temperature of the DC inductor in a Boost circuit 10. The temperature detection circuit of the DC inductor includes a voltage detection filter circuit 20 and a temperature detector 30. The detection end of the voltage detection filter circuit 20 is connected to the DC inductor, the output end of the voltage detection filter circuit 20 is connected to the voltage input end of the temperature detector 30, and the current input end of the temperature detector 30 receives the current flowing through the DC inductor in the Boost circuit 10.

[0043] In this embodiment, the DC inductor can be equivalent to an inductor and a resistor in series. Figure 1 As shown in , the DC inductor can be equivalent to an inductor L and a resistor R in series, and the inductor L and the resistor R are connected in series and connected to the PCB board through terminals.

[0044] The photovoltaic inverter controls the grid connection by sampling the inductor current. Therefore, the photovoltaic inverter can be used to sample the current of the DC inductor and perform operations such as average calculation on the inductor current. That is, the current sampling and calculation of the DC inductor does not require the additional setting of corresponding hardware circuits, so as to achieve the effect of reducing costs and improving efficiency.

[0045] The voltage detection filter circuit 20 may be a second-order low-pass filter circuit, but is not limited thereto.

[0046] In a specific embodiment, the reference Figure 2 The voltage detection filter circuit 20 includes a first resistor R1, a second resistor R2, a first capacitor C1 and a second capacitor C2; wherein, one end of the first resistor R1 is connected to one end of the DC inductor, the other end of the first resistor R1 is connected to one end of the second resistor R2 and one end of the first capacitor C1, the other end of the second resistor R2 is connected to one end of the second capacitor C2 and the first voltage input end of the temperature detector 30; the other end of the first capacitor C1 and the other end of the second capacitor C2 are connected to the second voltage input end of the temperature detector 30 and the other end of the DC inductor.

[0047] In the above structure, the DC inductor can be equivalent to an inductor L and a resistor R connected in series, and the first resistor R1, the second resistor R2, the first capacitor C1 and the second capacitor C2 form a second-order low-pass filter, which is used to filter out the high-frequency AC voltage across the DC inductor when the DC inductor stores and releases energy, so as to obtain the average value of the resistance voltage drop of the DC inductor.

[0048] The temperature detector 30 may be a software calculation function module in the photovoltaic inverter controller to implement sampling and calculation of the current parameters of the DC inductor. The photovoltaic inverter controller may be a single chip microcomputer, DSP, ARM, etc.

[0049] When the photovoltaic inverter is in stable grid-connected operation, the DC inductor satisfies the volt-second balance. Specifically, when the switch in the Boost circuit is turned on, the voltage across the DC inductor is on It can be expressed as: on =Ul1+Il1*r; When the switch in the Boost circuit is turned off, the turn-off voltage Ul off It can be expressed as: off =Ul2+Il2*r, where Ul1 is the voltage drop generated when the inductor stores energy, Ul2 is the voltage drop generated when the inductor releases energy, Il1*r and Il2*r are the voltage drops generated by the DC resistance of the inductor. Based on the volt-second balance principle, Ul1*T on +Ul2*T off =0.

[0050] When the inductor stores and releases energy, the voltage across the DC inductor is a high-frequency AC voltage with a frequency equal to the switching frequency. Therefore, the high-frequency AC voltage can be filtered out by the voltage detection filter circuit 20 to obtain the average value of the resistance voltage drop of the DC inductor. Specifically, the inductor current is a unidirectional current with a waveform such as Figure 3 As shown, therefore, the voltage drop generated by the resistance of the DC inductor is a DC voltage, and the voltage across the DC inductor is filtered by the voltage detection filter circuit 20, leaving only the average value of the inductor resistance voltage drop, that is, when working in a steady state, the voltage across the DC inductor is averaged by the integer cycles of the switching cycle, and the average value of the inductor resistance voltage drop is obtained. The voltage detection filter circuit 20, such as a low-pass filter circuit, is used to filter out the high-frequency AC voltage across the DC inductor when the DC inductor stores and releases energy, and the average value of the DC inductor resistance voltage drop is obtained. Since the photovoltaic inverter is controlled by sampling the inductor current to connect to the grid, the inductor current flowing through the DC inductor can be directly obtained through the photovoltaic inverter without the need to set up a corresponding current detection circuit, so as to achieve the effect of reducing costs and improving efficiency.

[0051] A DC inductor coil is a metal coil wound around a magnetic core, usually made of copper, aluminum and other materials, and potted with silicone. The losses of a DC inductor mainly include copper loss, iron loss, eddy current loss, hysteresis loss, etc. These losses will increase the temperature of the inductor, and the heat is concentrated in the magnetic core and the coil. Therefore, the temperature of the coil is very close to the internal temperature of the inductor, and the internal temperature of the inductor can be determined by detecting the temperature of the coil. A metal resistance temperature sensor, also known as a thermistor sensor, is a sensor used to measure temperature. Its working principle is that the resistance of the material changes with temperature. Once the temperature of the wire changes, the resistance value of the wire will also change accordingly, that is, the resistance value of the DC inductor has a linear relationship with the temperature.

[0052] Therefore, the resistance value of the DC inductor can be calculated through the voltage across the DC inductor and the current of the DC inductor, and the current temperature of the DC inductor can be determined through the resistance value of the DC inductor, thereby achieving real-time detection of the DC inductor temperature.

[0053] The technical solution of the present invention detects the voltage across the DC inductor through the voltage detection filter circuit 20 and transmits the detected voltage to the temperature detector 30 after filtering. The temperature detector 30 determines the temperature of the DC inductor according to the voltage after filtering and the current of the DC inductor. With such an arrangement, the real-time temperature of the DC inductor can be quickly obtained when the photovoltaic inverter is stably connected to the grid, ensuring that the photovoltaic inverter can work safely and reliably. There is no need to embed devices such as thermocouples and thermistors to detect the temperature of the DC inductor, and the cost of DC inductor temperature detection can be effectively reduced while obtaining the real-time temperature of the DC inductor.

[0054] The present invention also provides a photovoltaic inverter, which includes a Boost circuit and a temperature detection circuit of a DC inductor as described above. Since the photovoltaic inverter adopts all the technical solutions of all the aforementioned embodiments, it at least has all the beneficial effects brought by all the technical solutions of all the aforementioned embodiments, which will not be described one by one here.

[0055] In one embodiment, referring to Figure 4 The Boost circuit is a two-level Boost topology circuit, and the Boost circuit includes a DC input terminal, a DC output terminal, a DC inductor, a first diode D1, a first switch tube Q1, a third capacitor C3 and a fourth capacitor C4; wherein one end of the DC inductor is connected to the DC input terminal, one end of the third capacitor C3 and a first detection end of a voltage detection filter circuit 20 in a temperature detection circuit of the DC inductor, the other end of the DC inductor is connected to a first end of the first switch tube Q1, a positive electrode of the first diode D1 and a second detection end of the voltage detection filter circuit 20, and a negative electrode of the first diode D1 is connected to one end of the fourth capacitor C4 and the DC output terminal; the other end of the third capacitor C3, the second end of the first switch tube Q1 and the other end of the fourth capacitor C4 are interconnected.

[0056] In this embodiment, the DC inductor can be equivalent to an inductor L and a resistor R connected in series, and the voltage detection filter circuit 20 in the temperature detection circuit of the DC inductor is used to detect the voltage across the DC inductor formed by the inductor L and the resistor R in series, and filter out the high-frequency AC voltage across the DC inductor when the DC inductor stores and releases energy, so as to obtain the average value of the resistance voltage drop of the DC inductor.

[0057] The first switch tube Q1 may be one of MOSFET, SIC MOSFET or IGBT.

[0058] In one embodiment, referring to Figure 5 The Boost circuit is a flying three-level Boost topology circuit, and the Boost circuit includes a DC input terminal, a DC output terminal, a DC inductor, a second switch tube Q2, a third switch tube Q3, a second diode D2, a third diode D3, a fifth capacitor C5, a sixth capacitor C6 and a seventh capacitor C7;

[0059] Among them, one end of the DC inductor is connected to the DC input end and one end of the fifth capacitor C5, and the other end of the DC inductor is connected to the anode of the second diode D2 and the first end of the second switch tube Q2; the cathode of the second diode D2 is connected to the anode of the third diode D3 and one end of the sixth capacitor C6, and the other end of the sixth capacitor C6 is connected to the second end of the second switch tube Q2 and the first end of the third switch tube Q3; the cathode of the third diode D3 is connected to one end of the seventh capacitor C7 and the DC output end, and the other end of the fifth capacitor C5, the second end of the third switch tube Q3 and the other end of the seventh capacitor C7 are interconnected.

[0060] In this embodiment, the DC inductor can be equivalent to an inductor L and a resistor R connected in series, and the voltage detection filter circuit 20 in the temperature detection circuit of the DC inductor is used to detect the voltage across the DC inductor formed by the inductor L and the resistor R in series, and filter out the high-frequency AC voltage across the DC inductor when the DC inductor stores and releases energy, so as to obtain the average value of the resistance voltage drop of the DC inductor.

[0061] The second switch tube Q2 can be one of MOSFET, SIC MOSFET or IGBT.

[0062] The third switch tube Q3 can be one of MOSFET, SIC MOSFET or IGBT.

[0063] The present invention also provides a temperature detection method of a DC inductor, which is applied to a temperature detection circuit of a DC inductor. The temperature detection circuit of the DC inductor includes a voltage detection filter circuit and a temperature detector. The temperature detection method of the DC inductor includes:

[0064] Step S1, the voltage detection filter circuit detects the voltage across the DC inductor and performs filtering on the detected voltage;

[0065] Step S2: The temperature detector determines the temperature of the DC inductor according to the current of the DC inductor and the filtered voltage.

[0066] In one embodiment, step S2 includes:

[0067] Step S21, the temperature detector calculates the average current of the DC inductor according to the current of the DC inductor;

[0068] Step S22, the temperature detector calculates the average voltage of the DC inductor according to the voltage after filtering;

[0069] In step S23, the temperature detector calculates the temperature of the DC inductor according to the average current and the average voltage.

[0070] In one embodiment, step S23 includes:

[0071] Step S231, the temperature detector calculates the resistance value of the DC inductor according to the average current and the average voltage;

[0072] Step S232, the temperature detector determines the temperature corresponding to the resistance value from a preset relationship table;

[0073] Step S233: taking the determined temperature as the temperature of the DC inductor.

[0074] When the photovoltaic inverter is in stable grid-connected operation, the DC inductor satisfies the volt-second balance. Specifically, when the switch in the Boost circuit is turned on, the voltage across the DC inductor is on It can be expressed as: on =Ul1+Il1*r; When the switch in the Boost circuit is turned off, the turn-off voltage Ul off It can be expressed as: off =Ul2+Il2*r, where Ul1 is the voltage drop generated when the inductor stores energy, Ul2 is the voltage drop generated when the inductor releases energy, Il1*r and Il2*r are the voltage drops generated by the DC resistance of the inductor. Based on the volt-second balance principle, Ul1*T on +Ul2*T off =0.

[0075] When the inductor stores and releases energy, the voltage across the DC inductor is a high-frequency AC voltage with a frequency equal to the switching frequency. Therefore, the high-frequency AC voltage can be filtered out by the voltage detection filter circuit 20 to obtain the average value of the resistance voltage drop of the DC inductor. Specifically, the inductor current is a unidirectional current with a waveform such as Figure 2As shown, therefore, the voltage drop generated by the resistance of the DC inductor is a DC voltage, and the voltage across the DC inductor is filtered by the voltage detection filter circuit 20, leaving only the average value of the inductor resistance voltage drop, that is, when working in a steady state, the voltage across the DC inductor is averaged by the integer cycles of the switching cycle, and the average value of the inductor resistance voltage drop is obtained. The voltage detection filter circuit 20, such as a low-pass filter circuit, is used to filter out the high-frequency AC voltage across the DC inductor when the DC inductor stores and releases energy, and the average value of the DC inductor resistance voltage drop is obtained. Since the photovoltaic inverter is controlled by sampling the inductor current to connect to the grid, the inductor current flowing through the DC inductor can be directly obtained through the photovoltaic inverter without the need to set up a corresponding current detection circuit, so as to achieve the effect of reducing costs and improving efficiency.

[0076] A DC inductor coil is a metal coil wound around a magnetic core, usually made of copper, aluminum and other materials, and potted with silicone. The losses of a DC inductor mainly include copper loss, iron loss, eddy current loss, hysteresis loss, etc. These losses will increase the temperature of the inductor, and the heat is concentrated in the magnetic core and the coil. Therefore, the temperature of the coil is very close to the internal temperature of the inductor, and the internal temperature of the inductor can be determined by detecting the temperature of the coil. A metal resistance temperature sensor, also known as a thermistor sensor, is a sensor used to measure temperature. Its working principle is that the resistance of the material changes with temperature. Once the temperature of the wire changes, the resistance value of the wire will also change accordingly, that is, the resistance value of the DC inductor has a linear relationship with the temperature.

[0077] In order to better illustrate the relationship between the resistance and temperature of a DC inductor, the coil material of the DC inductor is copper. The resistivity of copper at 20°C is ρ = 1.7*10 -8 , the resistivity of the metal coil conductor is expressed as Among them, ρ is resistivity, S is cross-sectional area, R is resistance value, and L is conductor length. It can be seen that the relationship between the resistance value and temperature of the conductor is: R(t)=R0*(1+At+B*t 2 +C*t 3 +……), where t is temperature, R0 is resistance at 0℃, R(t) is resistance at t℃, A, B, C…… are temperature coefficients, i.e. constants, and B, C…… are often very small, close to zero, and can be ignored.

[0078] Therefore, the DC resistance value of the DC inductor can be calculated through the voltage across the DC inductor and the current of the DC inductor, and the DC resistance is the resistance value of the inductor coil.

[0079] In one embodiment, after step S233, the method further includes:

[0080] Step S2331, determining whether the temperature of the DC inductor is greater than a preset temperature threshold;

[0081] Step S2332: when the temperature of the DC inductor is greater than the preset temperature threshold, start the inductor protection mechanism.

[0082] In the case where the temperature of the DC inductor can be obtained in real time, in order to ensure the normal operation of the photovoltaic inverter, a preset temperature threshold can be set. When the current temperature of the DC inductor is detected to be greater than the preset temperature threshold, the inductor protection mechanism is activated, for example, the photovoltaic inverter is derated to protect the DC inductor, and the temperature of the DC inductor is detected in real time during the derated operation of the photovoltaic inverter. When the temperature of the DC inductor drops to a certain temperature, for example, below the set temperature, the photovoltaic inverter is controlled to resume normal operation. Such a setting is conducive to further improving the reliability of the photovoltaic inverter.

[0083] The technical solution of the present invention detects the voltage across the DC inductor through a voltage detection filter circuit and transmits it to a temperature detector after filtering. The temperature detector determines the temperature of the DC inductor according to the filtered voltage and the current of the DC inductor. With such an arrangement, the real-time temperature of the DC inductor can be quickly obtained when the photovoltaic inverter is stably connected to the grid, ensuring that the photovoltaic inverter can work safely and reliably. There is no need to embed devices such as thermocouples and thermistors to detect the temperature of the DC inductor, and the temperature detection cost of the DC inductor is effectively reduced while obtaining the real-time temperature of the DC inductor.

[0084] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A DC inductor temperature detection circuit, used to detect the temperature of a DC inductor in a Boost circuit, characterized in that: The temperature detection circuit of the DC inductor includes a voltage detection filter circuit and a temperature detector; the detection end of the voltage detection filter circuit is connected to the DC inductor, the output end of the voltage detection filter circuit is connected to the voltage input end of the temperature detector, and the current input end of the temperature detector receives the current flowing through the DC inductor in the Boost circuit; The voltage detection filter circuit is used to detect the voltage across the DC inductor and filter the detected voltage; The temperature detector is used to determine the temperature of the DC inductor according to the current of the DC inductor and the voltage after filtering.

2. The temperature detection circuit of a DC inductor according to claim 1, characterized in that: The voltage detection filter circuit includes a first resistor, a second resistor, a first capacitor and a second capacitor; One end of the first resistor is connected to one end of the DC inductor, the other end of the first resistor is connected to one end of the second resistor and one end of the first capacitor, and the other end of the second resistor is connected to one end of the second capacitor and the first voltage input end of the temperature detector; The other end of the first capacitor and the other end of the second capacitor are connected to the second voltage input terminal of the temperature detector and the other end of the DC inductor.

3. A photovoltaic inverter, characterized in that: The photovoltaic inverter comprises a Boost circuit and a temperature detection circuit of a DC inductor as claimed in any one of claims 1 to 2.

4. The photovoltaic inverter according to claim 3, characterized in that: The Boost circuit includes a DC input terminal, a DC output terminal, a DC inductor, a first diode, a first switch tube, a third capacitor and a fourth capacitor; One end of the DC inductor is connected to the DC input end and one end of the third capacitor, the other end of the DC inductor is connected to the first end of the first switch tube and the positive electrode of the first diode, and the negative electrode of the first diode is connected to one end of the fourth capacitor and the DC output end; The other end of the third capacitor, the second end of the first switch tube and the other end of the fourth capacitor are interconnected.

5. The photovoltaic inverter according to claim 4, characterized in that: The first switch tube includes one of MOSFET, SICMOSFET or IGBT.

6. The photovoltaic inverter according to claim 3, characterized in that: The boost circuit includes a DC input terminal, a DC output terminal, a DC inductor, a second switch tube, a third switch tube, a second diode, a third diode, a fifth capacitor, a sixth capacitor and a seventh capacitor; One end of the DC inductor is connected to the DC input end and one end of the fifth capacitor, and the other end of the DC inductor is connected to the anode of the second diode and the first end of the second switch tube; The cathode of the second diode is connected to the anode of the third diode and one end of the sixth capacitor, and the other end of the sixth capacitor is connected to the second end of the second switch tube and the first end of the third switch tube; The cathode of the third diode is connected to one end of the seventh capacitor and the DC output end, and the other end of the fifth capacitor, the second end of the third switch tube and the other end of the seventh capacitor are interconnected.

7. The photovoltaic inverter according to claim 6, characterized in that: The second switch tube and the third switch tube include one of MOSFET, SIC MOSFET or IGBT.

8. A method for detecting the temperature of a DC inductor, characterized in that: The temperature detection method of the DC inductor is applied to the temperature detection circuit of the DC inductor, and the temperature detection circuit of the DC inductor includes a voltage detection filter circuit and a temperature detector; the detection end of the voltage detection filter circuit is connected to the DC inductor, the output end of the voltage detection filter circuit is connected to the voltage input end of the temperature detector, and the current input end of the temperature detector receives the current flowing through the DC inductor in the Boost circuit; The temperature detection method of the DC inductor comprises: Step S1, the voltage detection filter circuit detects the voltage across the DC inductor and performs filtering on the detected voltage; Step S2: The temperature detector determines the temperature of the DC inductor according to the current of the DC inductor and the filtered voltage.

9. The method for detecting the temperature of a DC inductor according to claim 8, wherein: The step S2 comprises: Step S21, the temperature detector calculates the average current of the DC inductor according to the current of the DC inductor; Step S22, the temperature detector calculates the average voltage of the DC inductor according to the voltage after filtering; In step S23, the temperature detector calculates the temperature of the DC inductor according to the average current and the average voltage.

10. The method for detecting the temperature of a DC inductor according to claim 9, wherein: The step 23 comprises: Step S231, the temperature detector calculates the resistance value of the DC inductor according to the average current and the average voltage; Step S232, the temperature detector determines the temperature corresponding to the resistance value from a preset relationship table; Step S233: taking the determined temperature as the temperature of the DC inductor.

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