Inverter structure for photovoltaic power supply system

Abstract

The utility model relates to the technical field of photovoltaic power supply, and discloses an inverter structure for a photovoltaic power supply system, a temperature detection unit is arranged beside an inverter bridge arm of an inverter or a radiator corresponding to the inverter bridge arm, and the temperature detection unit comprises a calibration module, a thermosensitive detection module and a filtering module, the thermosensitive detection module is used for detecting temperature information corresponding to an inverter bridge arm and adopts a voltage dividing structure, a voltage dividing point of the thermosensitive detection module is connected with the processor through the filtering module, and the filtering module is used for filtering an electric signal input into the processor; the calibration module is used for calibrating actual power supply voltage of the thermosensitive detection module, one end of the calibration module is connected with the processor, and the other end of the calibration module is connected with the thermosensitive detection module. According to the utility model, the power supply voltage of the thermosensitive detection module can be calibrated by means of the calibration module, and accurate power supply voltage information can be provided for temperature detection of the thermosensitive detection module, so that the accurate resistance value corresponding to the thermistor can be calculated, and the temperature detection accuracy of the inverter is further improved.

Description

TECHNICAL FIELD

[0001] The utility model belongs to the technical field of photovoltaic power supply, specifically relates to a kind of inverter structure for photovoltaic power supply system. BACKGROUND

[0002] In actual production application, temperature monitoring demand exists in many fields, for example, in photovoltaic power supply system, the temperature of ambient temperature and internal device greatly influences the normal operation of inverter, so the temperature of power device in inverter needs to be monitored. Figure 1 As shown in the figure, it is the resistance value measurement circuit of thermistor for realizing temperature monitoring, circuit uses reference power supply (positive pole is Vi, negative pole is SGND) of fixed voltage Vi, divides voltage through resistance of a fixed resistance R1 and thermistor RX, collects the voltage V at the two ends of thermistor, calculates the resistance value of thermistor through formula RX=(Vi-Vo) / (Vo / R1), and obtains corresponding temperature by looking up table. However, in actual engineering application, the voltage of input power supply cannot be guaranteed to be fixed voltage Vi in ideal state, and often exists deviation or jitter;Secondly, there is error in resistance in circuit, as well as factory error and aging error in use process;In addition, NTC resistance value and temperature are not ideal linear corresponding relationship, if directly using collected voltage value to recalculate resistance value, and looking up table to obtain temperature, there will be certain error. UTILITY MODEL CONTENTS

[0003] In order to solve the above technical problems, the utility model provides an inverter structure for photovoltaic power supply system, solves the deviation of input power supply voltage or jitter in prior art and other technical problems caused by resistance value measurement of thermistor.

[0004] In order to achieve the above object, the utility model provides the following technical scheme:

[0005] An inverter structure for photovoltaic power supply system is provided, temperature detection unit is arranged beside inverter bridge arm or radiator corresponding to inverter bridge arm of the inverter, the temperature detection unit includes calibration module, thermosensitive detection module and filter module,

[0006] The thermosensitive detection module is used to detect temperature information corresponding to inverter bridge arm, adopts voltage division structure, and the voltage division point is connected with processor through filter module, and the filter module is used to filter electrical signal input to processor;

[0007] The calibration module is used to calibrate actual power supply voltage of thermosensitive detection module, one end thereof is connected with processor, and the other end is connected with thermosensitive detection module.

[0008] Further, the calibration module adopts a controllable switch structure, an enable end of which is connected with the processor, and a switch body of which is connected between a power supply and the thermistor in the thermosensitive detection module.

[0009] Further, the calibration module includes a controllable switch, an enable end of which is connected with the processor, one end of a switch body of which is connected with the power supply, and the other end of which is connected with the thermistor.

[0010] Further, the thermosensitive detection module includes the resistance R1 and the resistance R2 connected in series, a free end of the resistance R1 is connected with the power supply, a free end of the resistance R2 is grounded, and a middle point between the two is connected with the processor through the filter module,

[0011] The two ends of the resistance R1 are also connected in parallel with the resistance R3 and the thermistor connected in series.

[0012] Further, the filter module includes a comparator, an output end of the comparator is connected with the processor, a positive phase end of the comparator is connected to the middle point between the resistance R1 and the resistance R2 through the resistance R4, and a negative phase end of the comparator is connected with the output end of the comparator,

[0013] The free end of the resistance R2 is also connected to the middle point between the resistance R4 and the comparator through the capacitor C1.

[0014] Further, the calibration module includes a relay, a switch body of the relay is connected between the power supply and the thermistor, and a control coil of the relay is connected with the processor through the controllable switch.

[0015] Further, the controllable switch is arranged as any one of MOSFET, IGBT and triode.

[0016] Compared with the prior art, the utility model has the beneficial effects that:

[0017] 1. Since the thermosensitive detection module adopts a voltage division structure for temperature detection, the accurate power supply voltage needs to be known, therefore, the calibration module can calibrate the power supply voltage of the thermosensitive detection module, accurate power supply voltage information can be provided for the temperature detection of the thermosensitive detection module, so as to calculate the accurate resistance value corresponding to the thermistor, the deviation of the thermistor resistance value measurement caused by the voltage deviation or jitter of the input power supply can be effectively avoided, and the detection accuracy of the temperature information corresponding to the inverter bridge arm is improved, thereby providing guarantee for the normal operation of the inverter.

[0018] 2. The controllable switch is used to skillfully control the access and removal of the thermistor NTC, the calibration of the power supply voltage of the thermosensitive detection module is completed, and the accuracy of the resistance value calculation of the subsequent thermistor is ensured.

[0019] 3、Although the controllable switch can control the access and removal of the thermistor NTC, the controllable switch body cannot completely cut off the current in the circuit, and a trace of current will still pass through, which may affect the accuracy of the resistance value calculation of the subsequent thermistor, therefore the utility model also provides a calibration module composed of a relay, which can realize circuit cutting from the physical layer, and helps to improve the accuracy of the resistance value calculation of the thermistor.

[0020] 4、When the thermistor NTC is in a short circuit condition, the utility model realizes a circuit structure with protection function by increasing the resistance R3, and increases the resistance R1 in the circuit, which makes up for the problem that the resistance value and temperature of the thermistor NTC are nonlinear in the low temperature area, resulting in a large temperature calculation deviation. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 It is a circuit structure schematic diagram of a temperature detection unit in the prior art;

[0022] Figure 2 It is a whole circuit schematic diagram of the inverter structure of the utility model;

[0023] Figure 3 It is a circuit structure schematic diagram corresponding to the temperature detection unit in embodiment one of the utility model;

[0024] Figure 4 It is a circuit structure schematic diagram corresponding to the temperature detection unit in embodiment two of the utility model. DETAILED DESCRIPTION

[0025] In order to make the technical means, creative features, purposes and effects realized by the utility model easy to understand, the following embodiments will make a specific description of the inverter structure of the utility model for a photovoltaic power supply system in combination with the drawings, and it should be noted that the description of these embodiments is used to help understand the utility model, but does not constitute a limitation on the utility model.

[0026] As Figure 2As shown, the utility model provides a kind of inverter structure for photovoltaic power supply system, temperature detection unit is arranged in the inverter bridge arm of inverter or the radiator corresponding to inverter bridge arm, the temperature detection unit includes calibration module, thermosensitive detection module and filter module, the thermosensitive detection module is used to detect the temperature information corresponding to inverter bridge arm, adopts voltage division structure, and its voltage division point is connected with processor by filter module, and the filter module is used to filter the electrical signal input to processor;The calibration module is used to calibrate the actual supply voltage of thermosensitive detection module, and one end is connected with processor, and the other end is connected with thermosensitive detection module.This way, since thermosensitive detection module is temperature detection using voltage division structure, accurate supply voltage needs to be known, and the supply voltage of thermosensitive detection module can be calibrated by calibration module, to provide accurate supply voltage information for the temperature detection of thermosensitive detection module, to calculate the accurate resistance value corresponding to thermistor, the deviation of thermistor resistance value measurement caused by voltage deviation or jitter of input power supply can be effectively avoided, and then the detection accuracy of the temperature information corresponding to inverter bridge arm is improved, and the normal operation of inverter is guaranteed.

[0027] Specifically as follows:

[0028] Embodiment one

[0029] As Figure 3 Shown, the calibration module adopts controllable switch structure, and its enable end is connected with processor, and its switch body is connected between power supply and thermistor in thermosensitive detection module, so that controllable switch can realize switch control according to the control instruction of processor, to effectively control the access circuit or cutout circuit of thermistor, specifically, the calibration module includes controllable switch Q1 such as MOSFET, IGBT, triode, and its enable end, i.e. base, is connected with IO1 pin of processor, and one end of its switch body is connected with power supply, and the other end is connected with thermistor, such as emitter and thermistor connection, collector and power supply connection.

[0030] The thermosensitive detection module includes series-connected resistance R1 and resistance R2, the free end of the resistance R1 is connected with power supply, the free end of the resistance R2 is grounded, and the middle point of the two is connected with IO2 pin of processor by filter module, and the two ends of the resistance R1 are also connected with series-connected resistance R3 and thermistor in parallel.

[0031] The filter module comprises a comparator, an output end of the comparator is connected with the processor, a positive end of the comparator is connected with the middle point of the resistor R1 and the resistor R2 through the resistor R4, a negative end of the comparator is connected with the output end of the comparator, and the free end of the resistor R2 is also connected with the middle point of the resistor R4 and the comparator through the capacitor C1. In the module, the comparator itself constitutes a shot circuit and does not play a comparison amplification role on the flowing voltage / current, but only a tracking role, and the resistor R4 and the capacitor C1 constitute a filter circuit and can filter the flowing voltage / current, so that the voltage fluctuation entering the processor can be removed, and accurate voltage information of the processor can be ensured. Of course, the resistor R4 and the capacitor C1 constituting the filter circuit in the module can also be replaced by a 1-n order passive filter circuit and an active filter circuit.

[0032] When the temperature of the inverter bridge arm needs to be detected, at the initial power-on of the inverter, the IO1 pin of the processor is high level enabled, the controllable switch Q1 is in an open state, the branch in which the thermistor is located is disconnected with the power supply, and the branch between the power supply, the resistor R1, the resistor R2 and the ground is still connected, at this time, the voltage information corresponding to the resistor R2 can be transmitted to the IO2 pin of the processor through the filter module, and the actual power supply voltage of the power supply can be inversely deduced, accurate voltage data for the subsequent thermistor detection module is provided, and the calibration operation is completed.

[0033] When the temperature detection is formally performed, the IO1 pin of the processor is low level enabled, the controllable switch Q1 is in a conductive state, the branch in which the thermistor and the resistor R3 are located is connected with the power supply, the branch is connected in parallel with the resistor R1 and then connected in series with the resistor R2 and then connected into the circuit, and the accurate resistance value corresponding to the thermistor at this time can be obtained by using a conventional voltage division calculation method, so that the temperature information corresponding to the inverter bridge arm is obtained by looking up a table.

[0034] Embodiment two

[0035] As shown in Figure 4 The structure of the thermistor detection module and the filter module is the same as that in the embodiment one, the calibration module comprises a relay, a switch body of the relay is connected between the power supply and the thermistor, and a control coil of the relay is connected with the processor through a controllable switch.

[0036] If the controllable switch is a transistor, its base is connected to the processor's IO1 pin, its emitter is connected to the relay's control coil, the free end of the control coil is grounded, and its collector is connected to another power supply. The normally closed contact of the relay is connected between the power supply and the thermistor. Thus, during calibration, i.e., when the inverter is first powered on, the processor's IO1 pin is low-level enabled, the controllable switch Q1 is in the on state, the relay's control coil is energized to control the normally closed contact to open, so that the branch where the thermistor is located will be disconnected from the power supply. Similarly, the branch between the power supply, resistor R1, resistor R2 and ground is still conducting. At this time, the voltage information corresponding to resistor R2 can be transmitted to the processor's IO2 pin through the filtering module, which can deduce the actual supply voltage of the power supply, providing accurate voltage data for the subsequent thermistor detection module. The subsequent formal temperature detection process is similar to that in Example 1.

[0037] It is important to note that the schemes and arrangements of this application shown in the exemplary embodiments are merely exemplary. Although only a few embodiments are described in detail in this disclosure, those who consult this disclosure will readily understand that many modifications are possible without substantially departing from the novel teachings and advantages of the subject matter described in this application (e.g., variations in various parameter values ​​(temperature, power, humidity, etc.), installation arrangements, names, colors, logical orders, etc.). Therefore, all such modifications are also included within the scope of this invention, and the order or sequence of any process or method steps may be changed or rearranged according to alternative embodiments. In the claims, any "apparatus plus function" clause is intended to cover the structure described herein that performs the function, and not only structurally equivalent but also equivalent in structure. Other substitutions, modifications, alterations, and omissions may be made in the design, operation, and arrangement of the exemplary embodiments without departing from the scope of this invention. Therefore, this invention is not limited to the particular embodiments but extends to various modifications that still fall within the scope of the appended claims.

[0038] Furthermore, in order to provide a concise description of exemplary embodiments, not all features of actual embodiments (i.e., those features that are not relevant to the best mode of carrying out the present invention as currently considered, or those features that are not relevant to implementing the present invention) may be omitted.

[0039] It should be understood that numerous specific implementation decisions can be made during the development of any practical implementation, such as in any engineering or design project. Such development efforts may be complex and time-consuming, but for those skilled in the art who benefit from this disclosure, the development effort will be a routine work of design, manufacturing, and production without requiring much experimentation.

[0040] It should be noted that the above embodiments are only used to illustrate the technical solution of this utility model and are not intended to limit it. Although this utility model has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solution of this utility model without departing from the spirit and scope of the technical solution of this utility model, and all such modifications or substitutions should be covered within the scope of the claims of this utility model.

Claims

1. An inverter structure for a photovoltaic powered system, characterized by: A temperature detection unit is arranged beside the heat sink corresponding to the inverter bridge arm or inverter bridge arm pair of the inverter, and the temperature detection unit comprises a calibration module, a thermal detection module and a filter module, The thermal detection module is used for detecting temperature information corresponding to the inverter bridge arm, adopts a voltage division structure, and a voltage division point thereof is connected to the processor through the filter module, and the filter module is used for filtering the electrical signal input to the processor; The calibration module is used for calibrating the actual power supply voltage of the thermal detection module, and one end thereof is connected to the processor and the other end is connected to the thermal detection module.

2. The inverter structure for a photovoltaic power supply system according to claim 1, characterized by: The calibration module adopts a controllable switch structure, an enable end of which is connected to the processor, and a switch body of which is connected between the power supply and the thermistor in the thermal detection module.

3. The inverter structure for a photovoltaic power supply system according to claim 2, characterized by: The calibration module comprises a controllable switch, an enable end of which is connected to the processor, and a switch body of which is connected to the power supply at one end and to the thermistor at the other end.

4. The inverter structure for a photovoltaic power supply system according to claim 3, characterized by: The thermal detection module comprises resistors R1 and R2 connected in series, a free end of the resistor R1 is connected to the power supply, a free end of the resistor R2 is grounded, and a middle point therebetween is connected to the processor through the filter module, The two ends of the resistor R1 are also connected in parallel to the resistor R3 and the thermistor connected in series.

5. The inverter structure for a photovoltaic power supply system according to claim 4, characterized by: The filter module comprises a comparator, an output end of the comparator is connected to the processor, a positive phase end of the comparator is connected to the middle point of the resistors R1 and R2 through a resistor R4, and a negative phase end of the comparator is connected to the output end of the comparator, The free end of the resistor R2 is also connected to the middle point of the resistor R4 and the comparator through a capacitor C1.

6. The inverter structure for a photovoltaic power supply system according to claim 1, characterized by: The calibration module comprises a relay, a switch body of the relay is connected between the power supply and the thermistor, and a control coil of the relay is connected to the processor through a controllable switch.

7. The inverter structure for a photovoltaic power supply system according to claim 2 or 6, characterized by: The controllable switch is arranged as any one of MOSFET, IGBT and triode.

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