Photovoltaic hot water system integrated with MPPT (maximum power point tracking) control

Abstract

The utility model relates to the field of clean new energy, in particular to an integrated MPPT (Maximum Power Point Tracking) control photovoltaic hot water system, which comprises a photovoltaic array, a combiner box and an MPPT control cabinet, the MPPT control cabinet is provided with an input anode and an input cathode, an input sensor, an IGBT (Insulated Gate Bipolar Translator) module, a controller, a contactor and an output sensor are arranged in the MPPT control cabinet, the input sensor is connected between the input anode and the IGBT module, and the controller is connected with the contactor. The input sensor collects signals and transmits the signals to the controller, the controller outputs control signals to a grid electrode of the IGBT module, a normally open contact of the contactor is connected between the IGBT module and the output sensor and is controlled by the controller, and the output sensor is connected with the shunt box and the heat storage water tank. On the basis of solving the problem of the traditional solar water heating system, the photovoltaic maximum power point tracking function is added, and the power generation efficiency of the photovoltaic water heating system can be improved to more than 98%.

Description

Technical Field

[0001] The utility model relates to the technical field of clean energy application, in particular to a photovoltaic water heating system with integrated MPPT control. Background Art

[0002] In recent years, solar thermal systems have been widely promoted in civil buildings, but the following pain points have emerged during the application process:

[0003] (1) High installation requirements: The solar water heating system has many equipment and parts, including collectors, heat storage tanks, circulating water pumps, circulating pipes and auxiliary heating equipment, etc., which requires a large roof installation area and affects the overall aesthetics of the building; the entire system is filled with circulating medium, and the system operating load is large. Pipeline welding construction is required during the construction process, which is difficult to construct.

[0004] (2) Poor system stability: The solar water heating system uses water or antifreeze as the heat transfer medium, and the equipment is connected by pipes. There are many system leaks. System overheating and poor water quality will aggravate the corrosion of pipes and equipment. At the same time, the system is prone to problems such as collector pipe explosion, overheating in summer and freezing damage in winter during operation. The system has poor stability and high operation and maintenance costs.

[0005] (3) High system cost: Based on the above pain points of traditional solar water heating systems, photovoltaic water heating systems have appeared on the market in the past two years. However, the system simply connects the photovoltaic array and the water storage tank, lacks the maximum power point tracking function of the photovoltaic system, and the photovoltaic power generation efficiency of the system is only about 70%. Utility Model Content

[0006] The technical problem to be solved by the utility model is to provide a photovoltaic water heating system with integrated MPPT control. On the basis of solving the pain points of traditional solar water heating systems, a photovoltaic maximum power point tracking function is added, which can increase the power generation efficiency of the photovoltaic water heating system to more than 98%.

[0007] In order to solve the technical problem, the technical solution adopted by the utility model is: a photovoltaic water heating system with integrated MPPT control, comprising a photovoltaic array, a junction box connected to the output end of the photovoltaic array, and an MPPT control cabinet connected to the output end of the junction box. The MPPT control cabinet is provided with an input positive pole and an input negative pole respectively connected to the output end of the junction box. An input sensor, an IGBT module, a controller, a contactor and an output sensor are arranged in the MPPT control cabinet. The input sensor is connected between the input positive pole and the collector of the IGBT module, the emitter of the IGBT module is connected to the input negative pole, the signal collected by the input sensor is transmitted to the controller, the controller adjusts the duty cycle of the PWM waveform according to the MPPT algorithm, and outputs a control signal to the gate of the IGBT module. The normally open point of the contactor is connected between the IGBT module and the output sensor, the coil of the contactor is connected to the controller, the output end of the MPPT control cabinet is followed by the output sensor, the output end of the MPPT control cabinet is connected to the shunt box, and the shunt box is connected to the hot water storage tank.

[0008] Furthermore, an RC filter circuit is provided between the input sensor and the IGBT module.

[0009] Furthermore, an LC filtering circuit is provided between the IGBT module and the contactor.

[0010] Furthermore, an anti-reverse connection diode D1 is provided after the input sensor, the anode of the anti-reverse connection diode D1 is connected to an end of the input sensor away from the input anode, and the cathode of the anti-reverse connection diode D1 is connected to the collector of the IGBT module.

[0011] Furthermore, an anti-reverse connection diode D2 is provided between the contactor and the output sensor, the positive electrode of the anti-reverse connection diode D2 is connected to the contactor, and the negative electrode of the anti-reverse connection diode D2 is connected to the output sensor.

[0012] Furthermore, the IGBT module is a full-bridge circuit composed of four IGBTs.

[0013] Furthermore, the photovoltaic array includes a plurality of photovoltaic strings, each photovoltaic string is composed of a plurality of photovoltaic panels, and each photovoltaic string is respectively connected to a junction box.

[0014] Furthermore, the input sensor and the output sensor collect the current and voltage at the input and output ends respectively.

[0015] Beneficial effects of the utility model:

[0016] (1) Compared with conventional solar thermal systems, photovoltaic panels replace solar collectors, and cables replace medium circulation pipelines. Except for the terminal water tank, the system has no liquid working fluid and will not experience overheating, freezing damage, leakage, etc., which greatly improves the stability of the hot water system and reduces the system's operation and maintenance costs.

[0017] (2) Compared with the existing photovoltaic water heating systems on the market, an MPPT (maximum power point tracking) control system has been added. Based on the MPPT algorithm, the photovoltaic power generation utilization rate can reach more than 98%, which is 20%~30% higher than the conventional photovoltaic water heating system.

[0018] (3) The photovoltaic modules are centrally installed on the roof, and the photovoltaic strings are combined in the junction box to supply power to the indoor water tank of the entire unit. Compared with the single-household single-panel system, the power generation utilization rate is high, and the entire system can be operated without additional power supply most of the time, which has high economic benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is the principle diagram of the utility model;

[0020] Figure 2 This is the electrical schematic diagram of the MPPT control cabinet;

[0021] In the figure: 1. Photovoltaic array, 2. Combiner box, 3. MPPT control cabinet, 4. Shunt box, 5. Hot water storage tank, 6. Input sensor, 7. RC filter circuit, 8. IGBT module, 9. LC filter circuit, 10. Contactor, 11. Output sensor. DETAILED DESCRIPTION

[0022] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments.

[0023] Example 1

[0024] This embodiment discloses a photovoltaic water heating system with integrated MPPT control, such as Figure 1 The system comprises a photovoltaic array 1, a junction box 2, an MPPT control cabinet 3, a shunt box 4 and a hot water storage tank 5 connected in sequence, wherein a cable is connected between the photovoltaic array 1, the junction box 2, the MPPT control cabinet 3, the shunt box 4 and the hot water storage tank 5 to transmit the electric energy generated by the photovoltaic array 1 to the hot water storage tank 5 to electrically heat the water in the hot water storage tank 5.

[0025] like Figure 2 As shown, the MPPT control cabinet 3 is provided with an input positive pole and an input negative pole respectively connected to the output end of the combiner box, and the MPPT control cabinet is provided with an input sensor 6, an anti-reverse connection diode D1, an RC filter circuit 7, an IGBT module 8, a controller, an LC filter circuit 9, a contactor 10, an anti-reverse connection diode D2 and an output sensor 11.

[0026] The input sensor 6 is connected between the input positive pole and the positive pole of the anti-reverse diode D1, the negative pole of the anti-reverse diode D1 is connected to the collector of the IGBT module 8, the emitter of the IGBT module 8 is connected to the input negative pole, and the RC filter circuit 7 is connected before the IGBT module 8, that is, between the negative pole of the anti-reverse diode D1 and the input negative pole. The signal collected by the input sensor 6 is transmitted to the controller (wireless or wired transmission is possible), the controller adjusts the duty cycle of the PWM waveform according to the MPPT algorithm, and outputs the control signal to the gate of the IGBT module 8. The normally open point of the contactor 10 is connected between the IGBT module 8 and the output sensor 11, the coil of the contactor 10 is connected to the controller, and the output sensor 11 is followed by the output end of the MPPT control cabinet. The output end of the MPPT control cabinet 3 is connected to the shunt box 4, and the shunt box 4 is connected to the hot water storage tank 5. The LC filter circuit 9 is arranged between the middle of the bridge arm of the IGBT module 8 and the output negative pole, the positive pole of the anti-reverse diode D2 is connected to the contactor, and the negative pole of the anti-reverse diode D2 is connected to the output sensor 11.

[0027] In this embodiment, the IGBT module 8 is a full-bridge circuit composed of four IGBTs. The photovoltaic array 1 includes a plurality of photovoltaic strings, each of which is composed of a plurality of photovoltaic panels, and each photovoltaic string is connected to a combiner box.

[0028] The input sensor 6 and the output sensor 11 collect the current and voltage at the input and output ends respectively.

[0029] During operation, the photovoltaic array 1 is installed on the roof of the building and is divided into the same number of photovoltaic strings according to the total number of components. Each photovoltaic string outputs a DC voltage of 300V~600V. Each photovoltaic string is connected to the junction box 2 for junction, and the output end of the junction box 2 is connected to the MPPT control cabinet 3 through a cable.

[0030] The MPPT control cabinet 3 collects the analog current and voltage values ​​at the input end through the input sensor 6, and transmits the detected analog quantity to the controller. The controller converts the analog quantity into a digital quantity, analyzes and adjusts the duty cycle of the PWM waveform according to the MPPT algorithm, and outputs a control signal to the IGBT module 8 to control the switch of the IGBT8 and the output voltage and current.

[0031] The voltage of the photovoltaic cell passes through the RC filter circuit 7 to eliminate clutter and ensure the stability of the DC input voltage. After entering the IGBT module 8, it is controlled and adjusted to the set voltage, and then passes through the LC filter circuit 9 to enter the contactor 10. Under normal conditions, the contactor 10 is disconnected. When the output voltage meets the output requirements, the controller controls the contactor 10 to close. After passing through the contactor 10, the current is output to each water heater through an anti-reverse diode D2. Ensure the normal operation of the water heater. The output sensor 11 detects the current and voltage at the output end, feeds back to the single-chip microcomputer, and assists the single-chip microcomputer in adjusting the output voltage and current.

[0032] When the solar radiation changes, the output voltage is adjusted by adjusting the on-off value of the IGBT switch through the MPPT algorithm, so that the output voltage is within the range of 0-248V, ensuring that the water heater can absorb the power generation to the greatest extent.

[0033] In this embodiment, although the MPPT algorithm is integrated in the controller, the algorithm is an existing algorithm and the MPPT algorithm will not be described in detail.

[0034] The above description is only the basic principle and preferred embodiments of the present invention. Improvements and substitutions made by those skilled in the art based on the present invention belong to the protection scope of the present invention.

Claims

1. A photovoltaic water heating system with integrated MPPT control, characterized in that: It includes a photovoltaic array, a junction box connected to the output end of the photovoltaic array, and an MPPT control cabinet connected to the output end of the junction box. The MPPT control cabinet is provided with an input positive pole and an input negative pole respectively connected to the output end of the junction box. An input sensor, an IGBT module, a controller, a contactor and an output sensor are arranged in the MPPT control cabinet. The input sensor is connected between the input positive pole and the collector of the IGBT module, the emitter of the IGBT module is connected to the input negative pole, the signal collected by the input sensor is transmitted to the controller, the controller adjusts the duty cycle of the PWM waveform according to the MPPT algorithm, and outputs a control signal to the gate of the IGBT module. The normally open point of the contactor is connected between the IGBT module and the output sensor, the coil of the contactor is connected to the controller, the output end of the MPPT control cabinet is behind the output sensor, the output end of the MPPT control cabinet is connected to the shunt box, and the shunt box is connected to the hot water storage tank.

2. The photovoltaic water heating system with integrated MPPT control according to claim 1, characterized in that: An RC filter circuit is provided between the input sensor and the IGBT module.

3. The photovoltaic water heating system with integrated MPPT control according to claim 1, characterized in that: An LC filter circuit is provided between the IGBT module and the contactor.

4. The photovoltaic water heating system with integrated MPPT control according to claim 1, characterized in that: An anti-reverse connection diode D1 is provided after the input sensor, the anode of the anti-reverse connection diode D1 is connected to an end of the input sensor away from the input anode, and the cathode of the anti-reverse connection diode D1 is connected to the collector of the IGBT module.

5. The photovoltaic water heating system with integrated MPPT control according to claim 1, characterized in that: An anti-reverse connection diode D2 is provided between the contactor and the output sensor, the positive electrode of the anti-reverse connection diode D2 is connected to the contactor, and the negative electrode of the anti-reverse connection diode D2 is connected to the output sensor.

6. The photovoltaic water heating system with integrated MPPT control according to claim 1, characterized in that: The IGBT module is a full-bridge circuit consisting of 4 IGBTs.

7. The photovoltaic water heating system with integrated MPPT control according to claim 1, characterized in that: The photovoltaic array includes multiple photovoltaic strings, each of which is composed of multiple photovoltaic panels, and each photovoltaic string is connected to a junction box respectively.

8. The photovoltaic water heating system with integrated MPPT control according to claim 1, characterized in that: The input sensor and the output sensor collect the current and voltage at the input and output ends respectively.

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