MPPT wide-range input and multi-voltage output auxiliary source circuit

Abstract

The invention relates to an MPPT wide-range input and multi-voltage output auxiliary source circuit which comprises an auxiliary source chip U31, an input and output power taking circuit, an auxiliary source chip control circuit, an isolation driving circuit, a double-tube flyback circuit, a 12V-to-+ / -5V circuit and an 8V-to-multi-voltage circuit. The auxiliary source carries out voltage sampling from input and output, when the voltage rises to threshold voltage, internal logic of a chip is triggered to output a driving signal, the driving signal passes through the isolation driving circuit and then is transmitted to a primary side MOS tube of the double-tube flyback circuit, the primary side MOS tube is turned on and turned off to transmit energy of a primary side winding of a transformer to a secondary side winding, and the secondary side winding of the transformer is turned off. After rectification, 12V voltage and 8V voltage are output, and various voltages are output after passing through corresponding flyback circuits or conversion circuits. By taking power from input and output, ensuring that the auxiliary source has output, increasing the input range of the auxiliary source and outputting various voltages, the MPPT application range is greatly widened, and the MPPT power supply is efficient and stable and can be widely applied to various photovoltaic power generation systems.

Description

Technical Field

[0001] The present invention relates to the technical field of switching power supplies for photovoltaic energy, and particularly relates to an MPPT wide-range input and multi-voltage output auxiliary source circuit. Background Art

[0002] Nowadays, the country vigorously develops the photovoltaic field. Photovoltaic power generation, energy storage, etc. all lay a large area of photovoltaic panels to improve the utilization rate of solar energy. Photovoltaic power generation utilizes the photovoltaic effect to directly convert solar radiant energy into electrical energy. The basic device for photo-electric conversion is a solar cell. A solar cell is a device that directly converts solar light energy into electrical energy due to the photovoltaic effect. It is a semiconductor photodiode. When sunlight shines on the photodiode, the photodiode will convert the solar light energy into electrical energy and generate current. When many cells are connected in series or parallel, a solar cell array with a relatively large output power can be formed. A solar cell is a promising new type of power source with three major advantages: permanence, cleanliness, and flexibility. Solar cells have a long lifespan. As long as the sun exists, solar cells can be used for a long time with a one-time investment; compared with thermal power generation and nuclear power generation, solar cells do not cause environmental pollution.

[0003] Currently, the efficiency of photovoltaic power generation depends on factors such as the material, structure, manufacturing process of the battery, as well as environmental factors such as light intensity, spectral distribution, and temperature. With the progress of technology, new materials have gradually made up for the defects of low efficiency of old materials, but it is still restricted by factors such as light intensity and temperature. Therefore, photovoltaic power generation has a dynamic output, and its maximum output power also changes dynamically with the above-mentioned influences. Therefore, the MPPT (Maximum Power Point Tracking) controller was born. The MPPT controller can detect the generated voltage of the solar panel in real time and track the highest voltage and current value (VI), so that the photovoltaic array always outputs the maximum power. The photovoltaic array equipped with the MPPT controller can charge the battery with the maximum power output of the system, with a tracking efficiency of up to 99.9%, and the power generation efficiency of the entire system is up to more than 97%, which is about 50% higher than the traditional system.

[0004] Photovoltaic power generation generally consists of a photovoltaic cell array built in series and parallel, a DC / DC converter, and an MPPT controller. Its schematic diagram is as Figure 1As shown in the figure. The MPPT system mainly includes a DC / DC converter, an MPPT controller, various communications and interfaces, etc. In the field of photovoltaic power generation, photovoltaic panels are connected in series and parallel to form a photovoltaic array with a relatively high voltage and current. The output voltage and current are regulated through a DC / DC converter in the middle, and finally the energy of the photovoltaic panels is output to the subsequent load. Among them, the MPPT controller continuously detects the changes in the current and voltage of the photovoltaic array, and adjusts the duty cycle of the PWM drive signal of the DC / DC converter according to the changes, so as to always maintain the maximum power output of the photovoltaic array.

[0005] Since there are many forms of subsequent loads, such as storage batteries, system buses, large equipment, etc., to meet the voltage and current of various loads, the MPPT system needs to have a wide range of output capabilities. Secondly, due to the size of the photovoltaic array and its dynamic output throughout the day, the MPPT system needs to meet a wide range of inputs. Both inside the MPPT and the system cover a variety of semiconductor devices and control ICs, and their reliable operation requires multiple voltages for power supply.

[0006] Under these conditions, the auxiliary power source of the MPPT system needs to be able to work normally and stably under wide range input conditions, and needs to output multiple voltages to meet the requirements. Summary of the Invention

[0007] In view of this, an MPPT wide range input and multi-voltage output auxiliary power source circuit with a wide application range, high efficiency and stability is provided. It can meet the requirement that the auxiliary power source has an output when any one of the input and output sides of the MPPT system is powered. The input range of the auxiliary power source is greatly increased, and the types of output voltages of the auxiliary power source are relatively many, which can meet the voltage power supply requirements of each part inside the MPPT, and can additionally output voltages to meet the needs of customers to connect various control boards.

[0008] An MPPT wide range input and multi-voltage output auxiliary power source circuit is mainly used in a multi-channel photovoltaic cell system, and it includes an auxiliary power source chip U31, an input / output power taking circuit, an auxiliary power source chip control circuit, an isolation drive circuit, a dual-switch flyback circuit, a 12V to ±5V circuit, and an 8V to multi-voltage circuit; The input / output power taking circuit includes an input power taking diode and an output power taking diode. The input power taking diode is connected to the input of the MPPT system, and the output power taking diode is connected to the output of the MPPT system to take power correspondingly, as the auxiliary power source bus voltage; The auxiliary source chip control circuit includes an auxiliary source chip power supply circuit and a feedback circuit. The auxiliary source chip power supply circuit includes a voltage dividing resistor and / or a current limiting resistor, and one end thereof is connected to the auxiliary source bus voltage, and the other end is connected to the power supply pin VCC of the auxiliary source chip U31. The feedback circuit includes an isolated optocoupler circuit. The secondary side of the isolated optocoupler circuit is connected to the feedback pin FB of the auxiliary source chip U31, and the anode of the primary side of the isolated optocoupler circuit is connected to a predetermined voltage output, and the cathode is connected to the primary side isolated voltage stabilizing diode U22. The dual-switch flyback circuit includes an upper MOS transistor Q57, a lower MOS transistor Q58, and a flyback transformer. The source electrode of the upper MOS transistor Q57 and the drain electrode of the lower MOS transistor Q58 are respectively connected to the different-named ends and the same-named ends of the primary side of the flyback transformer. The flyback transformer has a first flyback secondary winding T1-C and a second flyback secondary winding T1-B. The two flyback secondary windings respectively have corresponding output voltages. The second flyback secondary winding T1-B is connected to a 12V to ±5V circuit, and the first flyback secondary winding T1-C is connected to an 8V to multi-voltage circuit. The two ends of the second flyback secondary winding are connected in parallel with the anode and the cathode of the primary side of the isolated optocoupler circuit. The isolated drive circuit includes an isolated drive triode Q144, an isolated drive switch tube Q11, and an isolated drive transformer T4. The base electrode of the isolated drive triode Q144 and the gate electrode of the isolated drive switch tube Q11 are connected to the drive pin GATE of the auxiliary source chip U31. The isolated drive triode Q144 and the isolated drive switch tube Q11 are connected in series through the primary side winding of the isolated drive transformer T4, and are synchronously turned on and off under the drive of the signal of the drive pin GATE of the auxiliary source chip U31. The secondary side of the isolated drive transformer T4 has a first drive secondary winding and a second drive secondary winding. The two ends of the first drive secondary winding are connected in parallel to the gate electrode and the source electrode of the upper MOS transistor Q57, and the two ends of the second drive secondary winding are connected in parallel to the gate electrode and the source electrode of the lower MOS transistor Q58. The upper MOS transistor Q57 and the lower MOS transistor Q58 are synchronously driven to be turned on or off through the first drive secondary winding and the second drive secondary winding. The 12V to ±5V circuit is connected to a DCDC conversion circuit through a rectifier diode D55. The DCDC conversion circuit has a DCDC conversion chip U5. The switch output pin SW of the DCDC conversion chip U5 is connected to a coupled inductor L18. The primary side winding L18-A of the coupled inductor L18 outputs 5V, and the inductive secondary winding L18-B of the coupled inductor L18 outputs -5V voltage in reverse connection. The 8V to multi-voltage circuit includes a conversion transformer and a multi-channel LDO circuit. The conversion transformer has a plurality of conversion transformer secondary windings, and each conversion transformer secondary winding is correspondingly connected to a channel of the LDO circuit to output the required voltage.

[0009] Further, there are multiple input power-taking diodes, each of the input power-taking diodes is connected to a corresponding photovoltaic cell system, the output power-taking diode is connected to the output of the MPPT system, the cathodes of the respective input power-taking diodes or the output power-taking diode are commonly connected to one end of a fuse F7, the other end of the fuse F7 is connected to one end of a thermistor RNTC1, the other end of the thermistor RNTC1 is connected to the positive electrode of a first electrolytic capacitor C2, the negative electrode of the first electrolytic capacitor C2 is connected to the positive electrode of a second electrolytic capacitor C37, the negative electrode of the second electrolytic capacitor C37 is grounded, at least one resistor is connected in parallel to both the first electrolytic capacitor C2 and the second electrolytic capacitor C37 for voltage division, and an auxiliary source power supply bus voltage is obtained between the positive electrode of the first electrolytic capacitor C2 and the ground.

[0010] Further, the power supply pin VCC of the auxiliary source chip U31 is further connected to the 12V output of the auxiliary source itself. A diode D3 and a fifth current-limiting resistor R674 are connected in series between the power supply pin VCC and the 12V output of the auxiliary source itself. A third electrolytic capacitor and a filter capacitor C47 are connected in parallel between the fifth current-limiting resistor R674 and the power supply pin VCC, and the other ends of the parallel-connected third electrolytic capacitor and filter capacitor C47 are grounded.

[0011] Further, the auxiliary source chip control circuit further includes an input undervoltage circuit and an output overvoltage circuit. The input undervoltage circuit includes a sampling resistor with one end connected to the auxiliary source bus voltage and the other end connected to the undervoltage protection pin BO of the auxiliary source chip U31. A undervoltage voltage stabilization unit is further connected between the sampling resistor and the undervoltage protection pin BO of the auxiliary source chip U31. The undervoltage voltage stabilization unit includes a voltage stabilization resistor R85, an undervoltage voltage stabilization capacitor C212, and an undervoltage voltage stabilization diode Z5 connected in parallel. One end of the undervoltage voltage stabilization unit is connected to the sampling resistor and the undervoltage protection pin BO, and the other end is grounded. The output overvoltage circuit is connected to the detection pin DEMAG of the auxiliary source chip U31. The output overvoltage circuit includes two overvoltage protection resistors R297 and R282 connected in series. The midpoint of the two overvoltage protection resistors R297 and R282 is connected to the detection pin DEMAG of the auxiliary source chip U31. One of the overvoltage protection resistors R282 and an overvoltage protection capacitor C383 are connected in parallel between the midpoint and the ground terminal. The input end of the other overvoltage protection resistor R297 is connected to the auxiliary source bus voltage or the auxiliary source output.

[0012] Further, the collector of the secondary triode OT1-A of the isolation optocoupler circuit is connected to the feedback pin FB of the auxiliary source chip U31 through a series resistor R88. A capacitor C214 is connected in parallel between the series resistor R88 of the collector of the secondary triode OT1-A and the emitter, and the capacitor C214 and the emitter are grounded together; the anode of the primary light-emitting diode OT1-B of the isolation optocoupler circuit is connected to the 12V output of the auxiliary source itself after being connected in series and parallel with a resistor, the cathode of the primary light-emitting diode OT1-B is connected to the primary isolation voltage regulator U22, and the output pin of the primary isolation voltage regulator U22 is connected to the same-name end of the second flyback secondary winding T1-B; resistors are connected in series and parallel between the respective pins of the primary isolation voltage regulator U22 for shunting or voltage division.

[0013] Further, the 12V to ±5V circuit is connected to the input pin VIN of the DCDC conversion chip U5 through a rectifier diode D55. A fourth electrolytic capacitor C35 and a capacitor C17 are connected in parallel between the same-name end and the opposite-name end of the second flyback secondary winding T1-B; the same-name end of the second flyback secondary winding T1-B and the ground pin of the DCDC conversion chip U5 are grounded together; the inductor secondary winding L18-B is connected to the -5V voltage output terminal L_-5V through a reverse twelfth diode D10; the middle point between the anode of the twelfth diode D10 and the -5V voltage output terminal L_-5V is grounded through a fifth electrolytic capacitor C140, and the positive terminal of the fifth electrolytic capacitor C140 is grounded.

[0014] Further, the emitter of the isolation drive triode Q144 is connected to the opposite-name end of the primary side of the isolation drive transformer T4, the collector of the isolation drive triode Q144 is connected to the first auxiliary source output terminal VAUX1, the first auxiliary source output terminal VAUX1 is connected to the power supply pin VCC of the auxiliary source chip U31 or to the 12V output terminal of the stepped-down auxiliary source itself, the collector of the isolation drive triode Q144 is connected to the same-name end of the primary side of the isolation drive transformer T4 through a ninth voltage regulator Z9 and a reversely connected first zero-one diode D101, the drain of the isolation drive switch tube Q11 is connected to the opposite-name end of the primary side of the isolation drive transformer T4, the source of the isolation drive switch tube Q11 is connected to the same-name end of the primary side of the isolation drive transformer T4 through a first zero-two diode D102, and the anode of the first zero-two diode D102 is connected to the source of the isolation drive switch tube Q11 and is grounded.

[0015] Specifically, the source of the upper MOS transistor Q57 is connected to the non - same - name end of the primary winding T1 - A of the flyback transformer. The drain of the upper MOS transistor Q57 is connected to the auxiliary source bus voltage. The drain of the upper MOS transistor Q57 is connected to the same - name end of the primary winding T1 - A of the flyback transformer through a reverse thirteenth diode D13, and the anode of the thirteenth diode D13 is connected to the same - name end of the primary winding T1 - A. The drain of the lower MOS transistor Q58 is connected to the same - name end of the primary winding T1 - A of the flyback transformer. The source of the lower MOS transistor Q58 is connected to the same - name end of the second driving secondary winding and then grounded together through at least one shunt resistor. The non - same - name end of the primary winding T1 - A is connected to one end of the shunt resistor grounded through a reverse seventy - second diode D72, and the cathode of the seventy - second diode D72 is connected to the non - same - name end of the primary winding T1 - A. The same - name end of the second driving secondary winding and the source of the lower MOS transistor Q58 are connected to the detection pin CS of the auxiliary source chip U31 through a resistor R239.

[0016] Specifically, the 8V to multi - voltage circuit further includes an 8V to EX_5V circuit. The 8V to EX_5V circuit includes a first - path LDO circuit. The first - path LDO circuit includes a fourteenth LDO chip U14. A twenty - third capacitor C23 is connected in parallel between the input pin IN and the ground pin GND of the fourteenth LDO chip U14 and then grounded. A forty - second capacitor C42 is connected in parallel between the output pin OUT and the ground pin GND of the fourteenth LDO chip U14 and then grounded. The output pin OUT of the fourteenth LDO chip U14 is connected to the EX_5V output terminal of the auxiliary source.

[0017] Further, the 8V output of the first flyback secondary winding T1-C is respectively connected to the power supply pin VDD and the enable pins ENA and ENB of a secondary flyback circuit chip U1, and the input pin of the secondary flyback circuit chip U1 is connected to a control signal output terminal of the MPPT controller; the 8V-to-multiple voltages circuit has multiple conversion transformers, each conversion transformer includes a primary winding of the conversion transformer and at least one secondary winding of the conversion transformer, and both ends of each secondary winding of the conversion transformer are respectively connected in parallel between the input terminal and the ground terminal of the corresponding LDO circuit. A capacitor is connected in parallel between the input terminal and the ground terminal of each LDO circuit, and another capacitor is connected in parallel between the output terminal and the ground terminal. The opposite-named ends of each secondary winding of the conversion transformer are connected to the input terminal of the corresponding LDO circuit through a forward diode; the same-named ends of each primary winding of the conversion transformer are respectively connected to the output pin of the secondary flyback circuit chip U1 through a voltage conversion switch tube; the gates of the voltage conversion switch tubes are connected to the output pin of the secondary flyback circuit chip U1 through resistors, the drains are connected to the same-named ends of the corresponding primary windings of the conversion transformers, and the sources are grounded. A capacitor is connected in parallel between the drains and the sources of the voltage conversion switch tubes and then grounded, and a filtering unit is connected in parallel between the gates and the sources of the voltage conversion switch tubes and then grounded. The filtering unit includes a capacitor and a resistor connected in parallel; the opposite-named ends of each primary winding of the conversion transformer are respectively connected to the 8V output of the first flyback secondary winding T1-C.

[0018] In the above MPPT wide-range input and multi-voltage output auxiliary power supply circuit, through the input power-taking diode and the output power-taking diode, when there is power on either the MPPT input side or the output side, it can be used as the auxiliary power supply bus voltage, thereby ensuring that the auxiliary power supply has an output, thus greatly increasing the input range of the auxiliary power supply. Through the flyback transformer in the dual-switch flyback circuit corresponding to multiple flyback secondary windings to provide different voltages. For example, it provides a 12V output, a 12V-to-±5V circuit outputs ±5V, an 8V output, and an 8V-to-multiple voltages circuit, such as EX_5V, CAN1_5V, CAN2_5V, 485_1_5V, 485_2_5V, DIDO_5V; thus it can meet the voltage power supply requirements of each part inside the MPPT, and can additionally output voltages to meet the requirements of customers to connect multiple control boards, greatly broadening the application range of the MPPT, and having high-efficiency and stable performance. Therefore, the above circuit has a wide range of application prospects. Description of the Drawings

[0019] Figure 1 It is the schematic diagram of the MPPT controller in the photovoltaic power generation system.

[0020] Figure 2 It is the schematic diagram of the input and output power-taking circuit in the MPPT wide-range input and multi-voltage output auxiliary power supply circuit of the embodiment of the present invention.

[0021] Figure 3 It is the schematic diagram of the auxiliary source chip control circuit in the MPPT wide-range input and multi-voltage output auxiliary source circuit according to the embodiment of the present invention.

[0022] Figure 4 It is the primary side circuit diagram of the isolation drive circuit and the dual-switch flyback circuit in the MPPT wide-range input and multi-voltage output auxiliary source circuit according to the embodiment of the present invention.

[0023] Figure 5 It is the circuit diagram of the secondary side T1-B of the dual-switch flyback circuit and the schematic diagram of the 12V to ±5V circuit in the MPPT wide-range input and multi-voltage output auxiliary source circuit according to the embodiment of the present invention.

[0024] Figure 6 It is the schematic diagram of the 8V to EX_5V circuit in the MPPT wide-range input and multi-voltage output auxiliary source circuit according to the embodiment of the present invention.

[0025] Figure 7 It is the schematic diagram of the 8V to CAN1_5V, CAN2_5V, 485_1_5V, 485_2_5V, DIDO_5V circuits in the MPPT wide-range input and multi-voltage output auxiliary source circuit according to the embodiment of the present invention. Detailed implementation manners

[0026] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments; based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0027] Please refer to Figures 2 to 7 , which shows the various circuit structures of an MPPT wide-range input and multi-voltage output auxiliary source circuit provided by the embodiment of the present invention. It is mainly used in a multi-path photovoltaic cell system and includes an auxiliary source chip U31, an input-output power supply circuit, an auxiliary source chip control circuit, an isolation drive circuit, a dual-switch flyback circuit, a 12V to ±5V circuit, and an 8V to multi-voltage circuit.

[0028] In a specific embodiment, the photovoltaic cell system has a photovoltaic cell array, that is, it has multiple columns of photovoltaic panels. MPPT stands for maximum power point tracking. The specific principle is as follows: The input side of the MPPT system is usually connected to a series of photovoltaic panels. The photovoltaic panels convert solar energy into electrical energy through the photovoltaic effect and output voltage and current to the MPPT system. The MPPT system detects the output voltage U and output current I of the photovoltaic panels in real time. Due to the environmental changes during the day, the output voltage U and output current I of the photovoltaic panels are constantly changing dynamically. Therefore, its power P = U * I is also changing dynamically. However, there is a maximum P at every moment. Therefore, the MPPT system usually uses algorithms for real-time tracking. Nowadays, there are many types of algorithms, but the commonly used ones are the perturbation observation method and the incremental conductance method. The first perturbation observation method is adopted in the embodiment of the present invention, that is, by adjusting the MPPT controller to periodically apply positive or negative increments to the output voltage of the photovoltaic panels and observing the change of the system power to determine the next voltage adjustment direction. If the power increases, continue to apply increments in the same direction; otherwise, apply increments in the opposite direction until the output power reaches the maximum value. This algorithm is simple and direct and easy to implement. However, due to its perturbation based on a fixed step size, it may cause oscillations near the maximum power point. Therefore, the present invention also combines a variable step size strategy in practical applications to improve the tracking accuracy and stability.

[0029] The MPPT system usually needs to meet the requirements of a wide range of input voltages and output voltages. At the same time, due to the relatively complex internal system and different working voltages required for many parts, it is necessary to provide an auxiliary power supply scheme for wide-range input and multi-voltage output of the MPPT.

[0030] In this embodiment, the input-output power extraction circuit includes an input power extraction diode and an output power extraction diode. The input power extraction diode is connected to the input, and the output power extraction diode is connected to the output to extract power accordingly as the auxiliary source bus voltage. The input from which the input power extraction diode extracts power refers to the input of the MPPT system or each access point where the photovoltaic cell array is connected to the MPPT controller. The output to which the output power extraction diode is connected refers to the output side of the MPPT system to the actual battery load or the bus voltage. Therefore, the auxiliary source circuit samples the voltage from the input and output to ensure that the auxiliary source can maintain normal and stable output before and after the MPPT controller is connected.

[0031] The auxiliary source chip control circuit includes an auxiliary source chip power supply circuit and a feedback circuit. The auxiliary source chip power supply circuit includes a voltage dividing resistor and / or a current limiting resistor, and one end is connected to the auxiliary source bus voltage, and the other end is connected to the power supply pin VCC of the auxiliary source chip U31. The feedback circuit includes an isolated optocoupler circuit. The secondary side of the isolated optocoupler circuit is connected to the feedback pin FB of the auxiliary source chip U31. The anode of the primary side of the isolated optocoupler circuit is connected to the predetermined voltage output, and the cathode is connected to the primary side isolated voltage stabilizing diode U22. The primary side isolated voltage stabilizing diode U22 cooperates with the primary side and secondary side of the isolated optocoupler circuit to perform closed-loop control to stabilize the 12V voltage output.

[0032] The dual-switch flyback circuit includes an upper MOS transistor Q57, a lower MOS transistor Q58, and a flyback transformer. The source electrode of the upper MOS transistor Q57 and the drain electrode of the lower MOS transistor Q58 are respectively connected to the different-named end and the same-named end of the primary side of the flyback transformer. Specifically, as Figure 4 shown, the primary winding T1-A of the flyback transformer is divided into two segments, namely the first primary winding segment and the second primary winding segment. The first primary winding segment has the same-named end 10, the second primary winding segment has the same-named end 11, and the two primary winding segments share a different-named end 12. The source electrode of the upper MOS transistor Q57 is connected to the shared different-named end of the primary winding T1-A of the flyback transformer, and the drain electrode of the lower MOS transistor Q58 is correspondingly connected to the same-named end 10 of the first primary winding segment of the primary winding T1-A of the flyback transformer. The flyback transformer has a first flyback secondary winding T1-C and a second flyback secondary winding T1-B. The two flyback secondary windings respectively have corresponding output voltages. The second flyback secondary winding T1-B is connected to the 12V to ±5V circuit, and the first flyback secondary winding T1-C is connected to the 8V to multi-channel voltage circuit. The two ends of the second flyback secondary winding are connected in parallel with the anode and cathode of the primary side of the isolated optocoupler circuit.

[0033] The isolation drive circuit includes an isolation drive triode Q144, an isolation drive switch Q11, and an isolation drive transformer T4. The base of the isolation drive triode Q144 and the gate of the isolation drive switch Q11 are connected to the drive pin GATE of the auxiliary source chip U31. The isolation drive triode Q144 and the isolation drive switch Q11 are connected in series through the primary winding of the isolation drive transformer T4 and are synchronously turned on and off under the drive of the signal at the drive pin GATE of the auxiliary source chip U31. The secondary side of the isolation drive transformer T4 has a first drive secondary winding and a second drive secondary winding. The two ends of the first drive secondary winding are connected in parallel to the gate and source of the upper MOS transistor Q57, and the two ends of the second drive secondary winding are connected in parallel to the gate and source of the lower MOS transistor Q58. The upper MOS transistor Q57 and the lower MOS transistor Q58 are synchronously driven to be turned on or off through the first drive secondary winding and the second drive secondary winding. During the isolation drive process, when the VCC voltage of the auxiliary source chip U31 rises to the threshold voltage, it triggers the internal logic of the auxiliary source chip U31 to output a drive signal, that is, a drive signal is output from the drive pin GATE. The drive signal passes through the isolation drive circuit and transmits the drive signal to the upper and lower MOS transistors on the primary side of the flyback circuit with two switches. The conduction and cutoff of the upper and lower MOS transistors on the primary side transfer the energy of the primary winding of the transformer to the secondary winding, and the secondary winding outputs 12V voltage and 8V voltage through the rectifier diode.

[0034] The 12V to ±5V circuit is connected to a DCDC conversion circuit through a rectifier diode D55. The DCDC conversion circuit has a DCDC conversion chip U5. The switch output pin SW of the DCDC conversion chip U5 is connected to a coupled inductor L18. The primary winding L18-A of the coupled inductor L18 outputs 5V, and the inductive secondary winding L18-B of the coupled inductor L18 outputs -5V voltage in reverse connection. Therefore, after the second flyback secondary winding T1-B is connected to the primary side of the primary isolation voltage regulator U22 and the isolation optocoupler circuit to provide a stable 12V voltage, the 12V voltage passes through the DCDC converter and outputs 5V voltage to meet the power supply requirements of other ICs inside the MPPT. At the same time, -5V voltage is output through the coupled inductor to meet the negative voltage turn-off requirement of the main power MOS transistor inside the MPPT.

[0035] The 8V-to-multiple-voltage circuit includes a conversion transformer and multiple LDO circuits. The conversion transformer has multiple secondary windings, and each secondary winding of the conversion transformer is correspondingly connected to an LDO circuit to output the required voltage. Specifically, the first flyback secondary winding T1-C outputs 8V voltage. The 8V voltage passes through an LDO circuit to output EX_5V to meet the customer's power supply requirements. At the same time, the 8V voltage passes through the secondary flyback circuit and each LDO circuit to correspondingly output CAN1_5V, CAN2_5V, 485_1_5V, 485_2_5V, and DIDO_5V to meet various communication voltage requirements.

[0036] Specifically, as Figure 2 shown, there are multiple input power-taking diodes. In the figure, an example of four-way input power-taking is shown, and the four input power-taking diodes D11, D60, D53, and D62 are respectively connected to the input terminals V_PV1+, V_PV2+, V_PV3+, and V_PV4+ for one-way output power-taking. Each input power-taking diode is connected to a corresponding photovoltaic cell system, and the output power-taking diode is connected to the output of the MPPT system. In the figure example, the output power-taking diode D118 is connected to the output terminal VOUT+. The cathodes of each input power-taking diode or output power-taking diode are commonly connected to one end of the fuse F7. The other end of the fuse F7 is connected to one end of the thermistor RNTC1. The other end of the thermistor RNTC1 is connected to the positive electrode of the first electrolytic capacitor C2. The negative electrode of the first electrolytic capacitor C2 is connected to the positive electrode of the second electrolytic capacitor C37. The negative electrode of the second electrolytic capacitor C37 is grounded. At least one resistor is connected in parallel to both the first electrolytic capacitor C2 and the second electrolytic capacitor C37 for voltage division. In the figure example, three resistors are respectively connected in parallel to both ends of the first electrolytic capacitor C2 and the second electrolytic capacitor C37. The auxiliary source power supply bus voltage is obtained between the positive electrode of the first electrolytic capacitor C2 and the ground.

[0037] Specifically, as Figure 3As shown, the auxiliary source chip power supply circuit adopts multiple voltage-dividing resistors and / or current-limiting resistors connected in series and parallel. The figure shows an example of ten resistors, with 5 pairs of parallel resistors connected in series respectively. Among them, resistor R116 is in parallel with R103, resistor R119 is in parallel with R104, resistor R120 is in parallel with R105, resistor R125 is in parallel with R114, and resistor R176 is in parallel with R115. After the above resistors are connected in series and parallel, they are connected to the power supply pin VCC of the auxiliary source chip U31, and two capacitors are connected in parallel between the power supply pin VCC and the ground, namely the third electrolytic capacitor C215 and the filter capacitor C47, to ensure that the startup current of the auxiliary source chip U31 is still sufficient under wide-range input conditions. Further, the power supply pin VCC of the auxiliary source chip U31 is further connected to the 12V output of the auxiliary source itself. That is, when the auxiliary source has its own output, it can be fed back to the auxiliary source chip U31, so as to ensure that the auxiliary source output can take over the voltage of the power supply pin VCC after it becomes normal, reducing the power consumption of the system. Specifically, a series-connected diode D3 and the fifth current-limiting resistor R674 are connected between the power supply pin VCC and the 12V output terminal AUX1_12V of the auxiliary source itself. The positive electrode of the third electrolytic capacitor C215 and the first end of the filter capacitor C47 are respectively connected to the node between the power supply pin VCC and the fifth current-limiting resistor R674, and the cathode of the parallel-connected third electrolytic capacitor C215 and the second end of the filter capacitor C47 are grounded. In addition, as Figure 3 shown, the power supply pin VCC is also connected to the first auxiliary source output terminal VAUX1 of the auxiliary source to supply the collector of the isolation drive triode Q144.

[0038] Further, the auxiliary source chip control circuit further includes an input undervoltage circuit and an output overvoltage circuit. The input undervoltage circuit includes a sampling resistor, with one end connected to the auxiliary source bus voltage and the other end connected to the undervoltage protection pin BO of the auxiliary source chip U31. Specifically, as Figure 3 shown, there are multiple sampling resistors. The figure shows an example of five sampling resistors R181, R177, R161, R87, and R93 connected in series in sequence. A undervoltage voltage stabilization unit is also connected between the sampling resistor and the undervoltage protection pin BO of the auxiliary source chip U31. The undervoltage voltage stabilization unit includes a parallel-connected voltage stabilization resistor R85, an undervoltage voltage stabilization capacitor C212, and an undervoltage voltage stabilization diode Z5. One end of the undervoltage voltage stabilization unit is connected to the sampling resistor and the undervoltage protection pin BO, and the other end is grounded. That is, the output terminal of the undervoltage voltage stabilization diode Z5 is connected to the fifth sampling resistor R93 and is also connected to the undervoltage protection pin BO of the auxiliary source chip U31.

[0039] As Figure 3As shown, the output overvoltage circuit is connected to the detection pin DEMAG of the auxiliary source chip U31; the output overvoltage circuit includes two series-connected overvoltage protection resistors R297 and R282, and the midpoint of the two overvoltage protection resistors R297 and R282 is connected to the detection pin DEMAG of the auxiliary source chip U31. One of the overvoltage protection resistors R282 is connected in parallel with an overvoltage protection capacitor C383 between the midpoint and the ground terminal; the input end of the other overvoltage protection resistor R297 is connected to the auxiliary source bus voltage or the auxiliary source output. For example, as shown, the front-end overvoltage protection resistor R297 is first connected to the auxiliary source output, such as the 12V output terminal AUX1_12V. When the detection pin DEMAG detects that the voltage at the voltage division point is too high above the threshold, it sends a signal to the auxiliary source chip U31 for corresponding adjustment and control. The drive pin GATE of the auxiliary source chip U31 is connected to the base of the isolation drive triode Q144 and the gate of the isolation drive switch Q11 of the isolation drive circuit through a drive resistor R102.

[0040] Further, the collector of the secondary triode OT1-A of the isolated optocoupler circuit is connected to the feedback pin FB of the auxiliary source chip U31 through a series resistor R88. A capacitor C214 is connected in parallel between the series resistor R88 and the emitter of the secondary triode OT1-A, and the capacitor C214 and the emitter are grounded together. The anode of the primary light-emitting diode OT1-B of the isolated optocoupler circuit is connected to the 12V output of the auxiliary source itself after being connected in series and parallel with resistors, serving as the 12V output terminal of the entire auxiliary source. The cathode of the primary light-emitting diode OT1-B is connected to the primary isolation voltage regulator U22. The output pin 2 of the primary isolation voltage regulator U22 is connected to the same-name end of the second flyback secondary winding T1-B; the input pin 3 of the primary isolation voltage regulator U22 is connected to the cathode of the primary light-emitting diode OT1-B, and resistors are connected in series and parallel between the respective pins of the primary isolation voltage regulator U22 for shunting or voltage division. Specifically, a resistor R88 and a resistor R790 are connected in parallel between the adjustment pin 1 and the output pin 2 of the primary isolation voltage regulator U22, which play a role in current limiting, voltage division, and can also shunt. Among them, the resistor R790 can be replaced with a variable resistor or a resistor network, so as to adjust the output voltage by changing the resistance value of the external resistor connected to the adjustment pin 1. The node between the input pin 3 of the primary isolation voltage regulator U22 and the cathode of the primary light-emitting diode OT1-B is further connected to the intermediate voltage division point of two series resistors R790 and R22. A capacitor C25 and a resistor R69 are connected in series between this node and the voltage division point. The primary light-emitting diode OT1-B and its series resistor R67 are connected in parallel with a resistor R76. One end of the resistor R76 is connected to the node between the input pin 3 of the isolation voltage regulator U22 and the cathode of the primary light-emitting diode OT1-B, and the other end is connected to the 12V output of the auxiliary source. The primary light-emitting diode OT1-B of the isolated optocoupler circuit and the primary isolation voltage regulator U22 are also connected in parallel between the same-name end and the opposite-name end of the second flyback secondary winding T1-B. Through the isolated optocoupler circuit, it can timely feedback whether the 12V output is stable. If there is an output higher or lower than 12V, it will be directly feedback to the auxiliary source chip U31 in time. The auxiliary source chip U31 will then give corresponding drive signals. For example, the duty cycle is adjusted through PWM signals to quickly respond to the regulated voltage output, so as to efficiently and stably output the required voltage.

[0041] Such as Figure 5 and 6As shown, further, the 12V to ±5V circuit is connected to the input pin VIN of the DCDC conversion chip U5 through the rectifier diode D55. It is shown that the opposite-named end of the second flyback secondary winding T1-B is connected to the rectifier diode D55, and then through a sixth current-limiting resistor R63 to the input pin VIN of the DCDC conversion chip U5. A filter circuit is further connected in parallel across both ends of the rectifier diode D55. This filter circuit includes two resistors R163 and R351 connected in parallel and a capacitor C46. The two resistors R163 and R351 are connected in parallel and then in series with the capacitor C46. A fourth electrolytic capacitor C35 and a capacitor C17 are connected in parallel between the same-named end and the opposite-named end of the second flyback secondary winding T1-B; the positive electrode of the fourth electrolytic capacitor C35 is connected to the 12V output of the auxiliary source, for example, the 12V output terminal AUX1_12V of the auxiliary source as shown in Figure 5 As shown. The same-named end of the second flyback secondary winding T1-B and the ground pin of the DCDC conversion chip U5 are grounded together; the inductor secondary winding L18-B is connected to the -5V voltage output terminal L_-5V through a reverse twelfth diode D10; the anode of the twelfth diode D10 and the midpoint of the -5V voltage output terminal L_-5V are grounded through a fifth electrolytic capacitor C140, and the positive terminal of the fifth electrolytic capacitor C140 is connected to the ground. The switching output pin SW of the DCDC conversion chip U5 is connected to a coupled inductor L18. The primary winding L18-A of the coupled inductor L18 is connected in parallel with an output capacitor C29 to provide a stable +5V output voltage, and this output serves as the +5V output terminal 5VP of the auxiliary source. A capacitor C27 and a resistor R61 are connected between the switching output pin SW and the bootstrap pin BST of the DCDC conversion chip U5 to provide a suitable operating voltage for the high-side drive circuit inside the DCDC conversion chip U5, ensuring that the high-side driver can operate normally, and thus effectively controlling functions such as power conversion. The enable pin EN of the DCDC conversion chip U5 is obtained by voltage division of a resistor R30 and another resistor R31. The resistor R30 is connected to the above-mentioned 12V output. The feedback pin FB of the DCDC conversion chip U5 is connected in series with a resistor R62 and then to the series voltage division point of a resistor R32 and a resistor R33. The resistor R32 and a capacitor 32 are connected in parallel between this series voltage division point and the +5V output terminal 5VP. The resistor R33 and another resistor R58 are connected in parallel between this series voltage division point and the ground terminal. The resistor R31 is grounded, and the capacitors C17 and C29 are also grounded.

[0042] As Figure 4As shown, further, the emitter of the isolation drive triode Q144 is connected to the opposite-named terminal of the primary side of the isolation drive transformer T4, the collector of the isolation drive triode Q144 is connected to the first auxiliary source output terminal VAUX1, the first auxiliary source output terminal VAUX1 is connected to the power supply pin VCC of the auxiliary source chip U31 or to the 12V output terminal of the stepped-down auxiliary source itself. In the initial state, the first auxiliary source output terminal VAUX1 can be connected to the stepped-down auxiliary source bus voltage, that is, take power from DC+ first. When the auxiliary source can output 12V voltage after its own operation, the first auxiliary source output terminal VAUX1 can be powered by the auxiliary source itself to cooperate with the conduction or cut-off of the isolation drive triode Q144. The collector of the isolation drive triode Q144 is connected to the same-named terminal of the primary side of the isolation drive transformer T4 through the ninth voltage regulator diode Z9 and the first zero-one-two diode D101 connected in reverse. The drain of the isolation drive switch tube Q11 is connected to the opposite-named terminal of the primary side of the isolation drive transformer T4, and the source of the isolation drive switch tube Q11 is connected to the same-named terminal of the primary side of the isolation drive transformer T4 through a first zero-two diode D102. The anode of the first zero-two diode D102 is connected to the source of the isolation drive switch tube Q11 and grounded. In addition, a diode D100 is connected in parallel between the emitter and the base of the isolation drive triode Q144, and the anode of the diode D100 is connected to the emitter of the isolation drive triode Q144 and the opposite-named terminal of the primary side of the isolation drive transformer T4. A resistor R187 is connected in parallel between the source and the gate of the isolation drive switch tube Q11, and the source of the isolation drive switch tube Q11 and the resistor R187 are connected in parallel and then grounded. The diode D100 and the resistor R187 respectively play the role of protecting the isolation drive triode Q144 and the isolation drive switch tube Q11. On the secondary side of the isolation drive transformer T4, the opposite-named terminal of the first drive secondary winding is connected to the gate of the upper MOS tube Q57 through a resistor R188, and a freewheeling diode D7 is connected in parallel at both ends of the resistor R188. The freewheeling diode D7 is connected in series with a current-limiting resistor R52 and then connected in parallel with the resistor R188; the opposite-named terminal of the second drive secondary winding is connected to the gate of the lower MOS tube Q58 through a resistor R335, and another freewheeling diode D34 is connected in parallel at both ends of the resistor R335. This freewheeling diode D34 is connected in series with another current-limiting resistor R66 and then connected in parallel with the resistor R335.

[0043] As Figure 4As shown, specifically, the source of the upper MOS transistor Q57 is connected to the opposite-named terminal of the primary winding T1-A of the flyback transformer. The drain of the upper MOS transistor Q57 is connected to the auxiliary source bus voltage. The drain of the upper MOS transistor Q57 is connected to the same-named terminal of the primary winding T1-A of the flyback transformer through a reverse thirteenth diode D13, and the anode of the thirteenth diode D13 is connected to the same-named terminal of the primary winding T1-A. The drain of the lower MOS transistor Q58 is connected to the same-named terminal of the primary winding T1-A of the flyback transformer. The source of the lower MOS transistor Q58 and the same-named terminal of the second driving secondary winding are connected together and then grounded through at least one shunt resistor. As shown in the figure, two shunt resistors R281 and R672 are connected in parallel and then grounded. The opposite-named terminal of the primary winding T1-A is connected to one end of the shunt resistor grounded through a reverse seventy-second diode D72, and the cathode of the seventy-second diode D72 is connected to the opposite-named terminal of the primary winding T1-A. The same-named terminal of the second driving secondary winding and the source of the lower MOS transistor Q58 are connected to the detection pin CS of the auxiliary source chip U31 through a resistor R239. A capacitor C91 is connected in parallel between the drain of the upper MOS transistor Q57 and the source of the lower MOS transistor Q58. The first end of the capacitor C91 is connected to the drain of the upper MOS transistor Q57 or connected to the auxiliary source bus voltage, and the second end of the capacitor C91 is connected in parallel with the two shunt resistors R281 and R672 and then grounded.

[0044] The opposite-named terminal of the first flyback secondary winding T1-C outputs an 8V voltage after being rectified by another rectifier diode D8. The first flyback secondary winding T1-C can directly output an 8V voltage after rectification, or can be further connected to various LDO circuits to output corresponding voltages. The same-named terminal of the first flyback secondary winding T1-C is grounded. A sixth electrolytic capacitor C59 is connected in parallel between the opposite-named terminal and the same-named terminal of the first flyback secondary winding T1-C at the output front end. The positive electrode of the sixth electrolytic capacitor C59 is connected to the opposite-named terminal of the first flyback secondary winding T1-C or the cathode of the rectifier diode when there is rectification, and the negative electrode of the sixth electrolytic capacitor C59 is grounded. Another filter circuit is further connected in parallel across the two ends of the rectifier diode D8. This another filter circuit includes two resistors R164 and R165 connected in parallel and a capacitor C61. The two resistors R164 and R165 are connected in parallel and then in series with the capacitor C61.

[0045] Specifically, as Figure 6As shown, the 8V to multi-channel voltage circuit further includes an 8V to EX_5V circuit; the 8V to EX_5V circuit includes a first LDO circuit, and the first LDO circuit includes a fourteenth LDO chip U14. A twenty-third capacitor C23 is connected in parallel between the input pin IN and the ground pin GND of the fourteenth LDO chip U14 and then grounded; a forty-second capacitor C42 is connected in parallel between the output pin OUT and the ground pin GND of the fourteenth LDO chip U14 and then grounded; the output pin OUT of the fourteenth LDO chip U14 is connected to the EX_5V output terminal of the auxiliary power supply.

[0046] Further, as Figure 7 shown, the 8V output of the first flyback secondary winding T1-C is respectively connected to the power supply pin VDD and two enable pins ENA and ENB of a secondary flyback circuit chip U1. The input pin of the secondary flyback circuit chip U1 is connected to a control signal output terminal of the MPPT controller; the 8V to multi-channel voltage circuit has multiple conversion transformers, and each conversion transformer includes a conversion transformer primary winding and at least one conversion transformer secondary winding. The two ends of each conversion transformer secondary winding are respectively connected in parallel between the input end and the ground end of the corresponding LDO circuit. A capacitor is connected in parallel between the input end and the ground end of each LDO circuit, and another capacitor is connected in parallel between the output end and the ground end. The non-homonymous end of each conversion transformer secondary winding is connected to the input end of the corresponding LDO circuit through a forward diode; the homonymous ends of each conversion transformer primary winding are respectively connected to the output pin of the secondary flyback circuit chip U1 through a voltage conversion switch tube. Corresponding to the two enable pins ENA and ENB, the secondary flyback circuit chip U1 has two output pins OUTA and OUTB. The gates of the voltage conversion switch tubes are connected to the output pin of the secondary flyback circuit chip U1 through resistors, the drains are connected to the homonymous ends of the corresponding conversion transformer primary windings, and the sources are grounded. A capacitor is connected in parallel between the drains and the sources of the voltage conversion switch tubes and then grounded. A filtering unit is connected in parallel between the gates and the sources of the voltage conversion switch tubes and then grounded. The filtering unit includes a capacitor and a resistor connected in parallel; the non-homonymous ends of each conversion transformer primary winding are respectively connected to the 8V output of the first flyback secondary winding T1-C.

[0047] To Figure 7Taking the CAN1_5V output circuit as an example, in this circuit, there is a primary winding T5-A of a conversion transformer, a secondary winding T5-B of the first conversion transformer, and a secondary winding T5-C of the second conversion transformer. The same-name end of the primary winding T5-A of the conversion transformer is sequentially connected to an output pin OUTA of a secondary flyback circuit chip U1 through a voltage conversion switch tube Q5, a third filter circuit, and a seventh current-limiting resistor R49. A capacitor C53 is connected in parallel between the drain and source of the voltage conversion switch tube Q5 and then grounded. The third filter circuit is connected in parallel between the gate and source of the voltage conversion switch tube Q5 and then grounded. The third filter circuit includes a fifty-second filter capacitor and a forty-seventh resistor R47. The different-name end of the primary winding T5-A of the conversion transformer is connected to the 8V output of the aforementioned first flyback secondary winding T1-C. An eighth electrolytic capacitor C384 is also connected in parallel at the front end where the 8V voltage is connected to the different-name end of the primary winding T5-A of the conversion transformer. The positive electrode of the eighth electrolytic capacitor C384 is connected to the different-name end of the primary winding T5-A of the conversion transformer, and the negative electrode is grounded. The two secondary windings T5-C and T5-B of the conversion transformer are respectively connected to a path of LDO circuit, which are set as the fifth LDO circuit and the sixth LDO circuit. The fifth LDO circuit has a fifth LDO chip U35, and the sixth LDO circuit has a sixth LDO chip U6. Specifically, the different-name end of the secondary winding T5-C of the second conversion transformer is connected to the input pin IN of the fifth LDO chip U35 through a third rectifier diode D32. Two capacitors C51 and C24 are connected in parallel between the input terminal IN of the fifth LDO chip U35 and the ground terminal GND, and another capacitor C12 is connected in parallel between the output terminal OUT and the ground terminal GND. The same-name end of the secondary winding T5-C of the second conversion transformer, the other ends of the capacitors C12, C51, and C24 are respectively grounded or connected to the ground terminal GND of the fifth LDO chip U35. The connection structure between the secondary winding T5-B of the first conversion transformer and the sixth LDO chip U6 in the sixth LDO circuit is basically the same as the connection structure between the secondary winding T5-C of the second conversion transformer and the fifth LDO chip U35 in the fifth LDO circuit, and will not be elaborated here. The output terminal OUT of the sixth LDO chip U6 is filtered through a capacitor C66 and then outputs another voltage required for communication. For example, it is used as the output terminal CAN2_5V. The connection methods of the primary and secondary windings of the conversion transformer and the LDO circuit in the remaining paths are basically the same as the aforementioned connection structure, and different voltages are respectively output, namely the first 485 communication voltage output terminal 485_1_5V, the second 485 communication voltage output terminal 485_2_5V, and the digital input / output voltage terminal DIDO_5V. Figure 7The lowermost primary winding T13-C of the transfer transformer also corresponds to two secondary windings T13-B and T13-A of the conversion transformer. Among them, the secondary winding T13-A of the conversion transformer corresponds to the digital input / output voltage terminal DIDO_5V, and the secondary winding T13-B of the conversion transformer is either no-load or reserved for other voltage conversion output circuits or directly grounded safely.

[0048] It can be seen from this that the above MPPT wide-range input and multi-voltage output auxiliary power supply circuit takes power from the MPPT input and output sides respectively through the input power-taking diode and the output power-taking diode. As long as there is power on either side, it can be used as the auxiliary power supply bus voltage, thus ensuring that the auxiliary power supply has an output, and greatly increasing the input range of the auxiliary power supply. At the beginning of the circuit, the sampled voltage is connected to the VCC pin of the auxiliary power supply chip through a series of resistors. The series of resistors meet the withstand voltage requirements under the wide-range input condition and the power supply current requirements of the auxiliary power supply chip. When the VCC voltage of the auxiliary power supply chip rises to the internal threshold voltage of the chip, it triggers the internal logic output drive signal of the chip. The drive signal passes through the isolation drive circuit and is transmitted to the upper MOS transistor Q57 and the lower MOS transistor Q58 of the double-switch flyback circuit. The conduction and cutoff of the two MOS transistors transfer the energy of the primary winding of the transformer to the secondary winding. The secondary winding outputs 12V voltage and 8V voltage through the rectifier diode. The 12V voltage is closed-loop controlled with the primary auxiliary power supply chip through the optocoupler to stabilize the 12V voltage output. The 12V voltage outputs 5V voltage through the DCDC converter to meet the power supply requirements of other ICs inside the MPPT. At the same time, -5V voltage is output through the coupling inductor to meet the negative voltage turn-off requirement of the main power MOS transistor inside the MPPT. The 8V voltage outputs EX_5V through the LDO circuit to meet the customer's power supply requirements. At the same time, the 8V voltage outputs CAN1_5V, CAN2_5V, 485_1_5V, 485_2_5V, DIDO_5V through the secondary flyback circuit and each LDO circuit to meet the requirements of various communication voltages. Therefore, the above circuit greatly broadens the application range of the MPPT and has high-efficiency and stable performance, with broad application prospects.

[0049] It should be noted that the present invention is not limited to the above embodiments. According to the creative spirit of the present invention, those skilled in the art can also make other changes, and these changes made based on the creative spirit of the present invention should be included within the scope of protection required by the present invention.

Claims

1. An MPPT wide-range input and multi-voltage output auxiliary source circuit, mainly used in a multi-channel photovoltaic cell system, which includes an auxiliary source chip U31, and is characterized in that, It also includes an input / output power-taking circuit, an auxiliary source chip control circuit, an isolation drive circuit, a dual-switch flyback circuit, a 12V-to-±5V circuit, and an 8V-to-multiple-voltage circuit; The input / output power-taking circuit includes an input power-taking diode and an output power-taking diode. The input power-taking diode is connected to the input of the MPPT system, and the output power-taking diode is connected to the output of the MPPT system to take power accordingly, serving as the auxiliary source bus voltage; The auxiliary source chip control circuit includes an auxiliary source chip power supply circuit and a feedback circuit. The auxiliary source chip power supply circuit includes a series of voltage-dividing or current-limiting resistors, with one end connected to the auxiliary source bus voltage and the other end connected to the power supply pin VCC of the auxiliary source chip U31; the feedback circuit includes an isolation optocoupler circuit. The secondary side of the isolation optocoupler circuit is connected to the feedback pin FB of the auxiliary source chip U31, and the anode of the primary side of the isolation optocoupler circuit is connected to a predetermined voltage output, and the cathode is connected to the primary side isolation voltage regulator U22; The dual-switch flyback circuit includes an upper MOS transistor Q57, a lower MOS transistor Q58, and a flyback transformer. The source electrode of the upper MOS transistor Q57 and the drain electrode of the lower MOS transistor Q58 are respectively connected to the different-named end and the same-named end of the primary side of the flyback transformer. The flyback transformer has a first flyback secondary winding T1-C and a second flyback secondary winding T1-B, and the two flyback secondary windings respectively have corresponding output voltages. The second flyback secondary winding T1-B is connected to the 12V-to-±5V circuit, and the first flyback secondary winding T1-C is connected to the 8V-to-multiple-voltage circuit; the two ends of the second flyback secondary winding are connected in parallel to the anode and the cathode of the primary side of the isolation optocoupler circuit; The isolation drive circuit includes an isolation drive triode Q144, an isolation drive switch tube Q11, and an isolation drive transformer T4. The base of the isolation drive triode Q144 and the gate of the isolation drive switch tube Q11 are connected to the drive pin GATE of the auxiliary source chip U31. The isolation drive triode Q144 and the isolation drive switch tube Q11 are connected in series through the primary winding of the isolation drive transformer T4 and conduct and disconnect synchronously under the drive of the signal of the drive pin GATE of the auxiliary source chip U31; the secondary side of the isolation drive transformer T4 has a first drive secondary winding and a second drive secondary winding. The two ends of the first drive secondary winding are connected in parallel to the gate and the source electrode of the upper MOS transistor Q57, and the two ends of the second drive secondary winding are connected in parallel to the gate and the source electrode of the lower MOS transistor Q58, and the upper MOS transistor Q57 and the lower MOS transistor Q58 are synchronously driven to conduct or disconnect through the first drive secondary winding and the second drive secondary winding; The 12V-to-±5V circuit is connected to a DCDC conversion circuit through a rectifier diode D55. The DCDC conversion circuit has a DCDC conversion chip U5. The switching output pin SW of the DCDC conversion chip U5 is connected to a coupled inductor L18. The primary winding L18-A of the coupled inductor L18 outputs 5V, and the inductive secondary winding L18-B of the coupled inductor L18 outputs -5V voltage in reverse connection; The 8V-to-multiple-voltage circuit includes a conversion transformer and multiple LDO circuits. The conversion transformer has multiple secondary windings, and each secondary winding of the conversion transformer is correspondingly connected to an LDO circuit to output the required voltage.

2. The MPPT wide-range input and multi-voltage output auxiliary source circuit according to claim 1, characterized in that, There are multiple input power-taking diodes, and each input power-taking diode is connected to a corresponding photovoltaic cell system. The output power-taking diode is connected to the output of the MPPT system; the cathodes of the respective input power-taking diodes or output power-taking diodes are commonly connected to one end of a fuse F7. The other end of the fuse F7 is connected to one end of a thermistor RNTC1. The other end of the thermistor RNTC1 is connected to the positive electrode of a first electrolytic capacitor C2. The negative electrode of the first electrolytic capacitor C2 is connected to the positive electrode of a second electrolytic capacitor C37. The negative electrode of the second electrolytic capacitor C37 is grounded. At least one resistor is connected in parallel to both the first electrolytic capacitor C2 and the second electrolytic capacitor C37 for voltage division. The auxiliary source supply bus voltage is obtained between the positive electrode of the first electrolytic capacitor C2 and the ground.

3. The MPPT wide-range input and multi-voltage output auxiliary source circuit according to claim 2, characterized in that, The power supply pin VCC of the auxiliary source chip U31 is further connected to the 12V output of the auxiliary source itself; a series-connected diode D3 and a fifth current-limiting resistor R674 are connected between the power supply pin VCC and the 12V output of the auxiliary source itself. A parallel-connected third electrolytic capacitor and a filter capacitor C47 are connected between the fifth current-limiting resistor R674 and the power supply pin VCC, and the other ends of the parallel-connected third electrolytic capacitor and the filter capacitor C47 are grounded.

4. The MPPT wide-range input and multi-voltage output auxiliary source circuit according to claim 1, characterized in that, The auxiliary source chip control circuit further includes an input undervoltage circuit and an output overvoltage circuit. The input undervoltage circuit includes a sampling resistor with one end connected to the auxiliary source bus voltage and the other end connected to the undervoltage protection pin BO of the auxiliary source chip U31; a undervoltage voltage stabilization unit is also connected between the sampling resistor and the undervoltage protection pin BO of the auxiliary source chip U31; the undervoltage voltage stabilization unit includes a parallel-connected voltage stabilization resistor R85, an undervoltage voltage stabilization capacitor C212, and an undervoltage voltage stabilization diode Z5. One end of the undervoltage voltage stabilization unit is connected to the sampling resistor and the undervoltage protection pin BO, and the other end is grounded; the output overvoltage circuit is connected to the detection pin DEMAG of the auxiliary source chip U31; the output overvoltage circuit includes two series-connected overvoltage protection resistors R297 and R282. The midpoint of the two overvoltage protection resistors R297 and R282 is connected to the detection pin DEMAG of the auxiliary source chip U31. One of the overvoltage protection resistors R282 is connected in parallel with an overvoltage protection capacitor C383 between the midpoint and the ground terminal; the input end of the other overvoltage protection resistor R297 is connected to the auxiliary source bus voltage or the auxiliary source output.

5. The MPPT wide-range input and multi-voltage output auxiliary source circuit according to claim 1, characterized in that, The collector of the secondary triode OT1-A of the isolated optocoupler circuit is connected to the feedback pin FB of the auxiliary source chip U31 through a series resistor R88; a capacitor C214 is connected in parallel between the series resistor R88 of the collector of the secondary triode OT1-A and the emitter, and the capacitor C214 and the emitter are grounded together; the anode of the primary light-emitting diode OT1-B of the isolated optocoupler circuit is connected to the 12V output of the auxiliary source itself after being connected in series and parallel with a resistor, the cathode of the primary light-emitting diode OT1-B is connected to the primary isolation voltage regulator U22, and the output pin of the primary isolation voltage regulator U22 is connected to the same-name end of the second flyback secondary winding T1-B; resistors are connected in series and parallel between the respective pins of the primary isolation voltage regulator U22 for shunting or voltage division.

6. The MPPT wide-range input and multi-voltage output auxiliary source circuit according to claim 1, wherein, The 12V to ±5V circuit is connected to the input pin VIN of the DCDC conversion chip U5 through the rectifier diode D55; a fourth electrolytic capacitor C35 and a capacitor C17 are connected in parallel between the same-name end and the different-name end of the second flyback secondary winding T1-B; the same-name end of the second flyback secondary winding T1-B and the ground pin of the DCDC conversion chip U5 are grounded together; the inductor secondary winding L18-B is connected to the -5V voltage output terminal L_-5V through a reverse twelfth diode D10; the middle point between the anode of the twelfth diode D10 and the -5V voltage output terminal L_-5V is grounded through a fifth electrolytic capacitor C140, and the positive terminal of the fifth electrolytic capacitor C140 is grounded.

7. The MPPT wide-range input and multi-voltage output auxiliary source circuit according to claim 1, characterized in that, The emitter of the isolated drive triode Q144 is connected to the different-name end of the primary side of the isolated drive transformer T4, the collector of the isolated drive triode Q144 is connected to the first auxiliary source output terminal VAUX1, the first auxiliary source output terminal VAUX1 is connected to the power supply pin VCC of the auxiliary source chip U31 or to the 12V output of the stepped-down auxiliary source itself, the collector of the isolated drive triode Q144 is connected to the same-name end of the primary side of the isolated drive transformer T4 through the ninth voltage regulator Z9 and the reversely connected first zero-one diode D101, the drain of the isolated drive switch tube Q11 is connected to the different-name end of the primary side of the isolated drive transformer T4, the source of the isolated drive switch tube Q11 is connected to the same-name end of the primary side of the isolated drive transformer T4 through a first zero-two diode D102, and the anode of the first zero-two diode D102 is connected to the source of the isolated drive switch tube Q11 and grounded.

8. The MPPT wide-range input and multi-voltage output auxiliary source circuit according to claim 7, characterized in that, The source of the upper MOS transistor Q57 is connected to the non - common terminal of the primary winding T1 - A of the flyback transformer. The drain of the upper MOS transistor Q57 is connected to the auxiliary source bus voltage. The drain of the upper MOS transistor Q57 is connected to the common terminal of the primary winding T1 - A of the flyback transformer through a reverse thirteenth diode D13, and the anode of the thirteenth diode D13 is connected to the common terminal of the primary winding T1 - A. The drain of the lower MOS transistor Q58 is connected to the common terminal of the primary winding T1 - A of the flyback transformer. The source of the lower MOS transistor Q58 is connected to the common terminal of the second driving secondary winding and then grounded together through at least one shunt resistor. The non - common terminal of the primary winding T1 - A is connected to one end of the shunt resistor grounded through a reverse seventy - second diode D72, and the cathode of the seventy - second diode D72 is connected to the non - common terminal of the primary winding T1 - A. The common terminal of the second driving secondary winding and the source of the lower MOS transistor Q58 are connected to the detection pin CS of the auxiliary source chip U31 through a resistor R239.

9. The MPPT wide-range input and multi-voltage output auxiliary source circuit according to claim 1, characterized in that, The 8V to multi - voltage circuit further includes an 8V to EX_5V circuit. The 8V to EX_5V circuit includes a first - stage LDO circuit. The first - stage LDO circuit includes a fourteenth LDO chip U14. A twenty - third capacitor C23 is connected in parallel between the input pin IN and the ground pin GND of the fourteenth LDO chip U14 and then grounded. A forty - second capacitor C42 is connected in parallel between the output pin OUT and the ground pin GND of the fourteenth LDO chip U14 and then grounded. The output pin OUT of the fourteenth LDO chip U14 is connected to the EX_5V output terminal of the auxiliary source.

10. The MPPT wide-range input and multi-voltage output auxiliary source circuit according to claim 1, wherein The 8V output of the first flyback secondary winding T1-C is respectively connected to the power supply pin VDD and the enable pins ENA and ENB of a secondary flyback circuit chip U1, and the input pin of the secondary flyback circuit chip U1 is connected to a control signal output terminal of the MPPT controller; the 8V-to-multiple-voltage circuit has multiple conversion transformers, each conversion transformer includes a conversion transformer primary winding and at least one conversion transformer secondary winding, both ends of each conversion transformer secondary winding are respectively connected in parallel between the input terminal and the ground terminal of a corresponding LDO circuit, a capacitor is connected in parallel between the input terminal and the ground terminal of each LDO circuit, and another capacitor is connected in parallel between the output terminal and the ground terminal of each LDO circuit. The non-homonymous ends of each conversion transformer secondary winding are connected to the input terminal of a corresponding LDO circuit through a forward diode; the homonymous ends of each conversion transformer primary winding are respectively connected to the output pin of the secondary flyback circuit chip U1 through a transformer switching tube; the gates of each transformer switching tube are connected to the output pin of the secondary flyback circuit chip U1 through a resistor, the drains are connected to the homonymous ends of the corresponding conversion transformer primary windings, the sources are grounded, a capacitor is connected in parallel between the drains and the sources of each transformer switching tube and then grounded, a filtering unit is connected in parallel between the gates and the sources of each transformer switching tube and then grounded, and the filtering unit includes a capacitor and a resistor connected in parallel; the non-homonymous ends of each conversion transformer primary winding are respectively connected to the 8V output of the first flyback secondary winding T1-C.

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