A bidirectional charging control device based on photovoltaic charging

Abstract

The present invention discloses a bidirectional charging control device based on photovoltaic charging, which relates to the technical field of vehicle charging, and includes: a charging management unit: used to monitor the voltage and current state of the first power terminal L1 and the second power terminal L2, and automatically adjust the charging strategy according to the battery power to realize CCCV constant current charging; an energy conversion unit: used to set a buck-boost module to boost the voltage from the first power terminal L1 to the third power terminal H, and buck the photovoltaic power supply to the second power terminal L2; a photovoltaic loop unit: to maintain a signal connection between the charging management unit and the energy conversion unit, so that each energy transmission end maintains the input and output switching of the battery and the photovoltaic. Compared with the prior art, the present invention can adjust the charging strategy in real time, the system can quickly respond to voltage changes during driving, and can quickly decide whether to enable the third power terminal H or the second power terminal L2 for charging, which has the advantages of reducing energy conversion losses and improving the overall system efficiency.

Description

Technical Field

[0001] The present invention relates to the technical field of vehicle charging, and in particular to a bidirectional charging control device based on photovoltaic charging. Background Art

[0002] RV driving charging technology has made significant progress in recent years and has become an important means to support the flexibility and self-sufficiency of RVs. Modern RVs are usually equipped with battery packs and multiple charging sources, including on-board generators, external power interfaces and renewable energy sources. The integration of these systems ensures the diversity of power supply. At present, solar photovoltaic charging and discharging technology is increasingly becoming a sustainable and efficient energy solution. This technology uses solar photovoltaic panels to convert sunlight into electrical energy to provide clean energy for RVs. The existing photovoltaic systems currently rely heavily on the intensity of sunlight, and weather changes will affect the charging efficiency. In the existing RV photovoltaic charging devices, on the one hand, when encountering rainy weather or at night, the photovoltaic panels cannot provide charging. Since the accumulated photovoltaic charging energy cannot be effectively stored and utilized, the RV may face the problem of insufficient driving power when it is far away from the power source, and at the same time, it leads to high energy loss and lack of good battery balance management. On the other hand, due to the small on-board space, the existing on-board charging energy devices with high energy utilization rates are all large in size, resulting in high requirements for the on-board space of RVs or other electric vehicles, while the smaller on-board charging energy devices are currently lacking in energy utilization. Summary of the invention

[0003] The present invention provides a bidirectional charging control device based on photovoltaic charging, which solves the problems of high energy loss and low recycling rate in photovoltaic driving charging of RVs in the prior art.

[0004] The present invention is achieved through the following technical solutions:

[0005] A bidirectional charging control device based on photovoltaic charging, comprising an energy transmission terminal for being arranged on a driving circuit of a motorhome, wherein the energy transmission terminal comprises a first power terminal L1, a second power terminal L2 and a third power terminal H which are connected together, characterized in that the device further comprises:

[0006] Charging management unit: used to monitor the voltage and current status of the first power terminal L1 and the second power terminal L2, automatically adjust the charging strategy according to the battery power, realize CCCV constant current charging, and decide when to start charging and discharging of the third power terminal H;

[0007] Energy conversion unit: used to set a buck-boost module, which cooperates with the first power terminal L1, the second power terminal L2 and the third power terminal H to perform the boost MPPT and buck MPPT working processes;

[0008] Photovoltaic loop unit: maintains signal connection between the charging management unit and the energy conversion unit, and is equipped with a signal controller M1 to control the energy transmission end, so that each energy transmission end maintains the input and output switching of the battery and photovoltaic;

[0009] Among them, the charging management unit and the energy conversion unit include a number of field effect diodes, the third power terminal H is connected and arranged in the buck-boost module, and the buck-boost module is composed of a number of field effect diodes; the field effect diode includes a diode and an N-channel field effect transistor, the positive electrode of the diode is connected to the S pole of the field effect transistor and the connection point is set as the first effect point, and the negative electrode of the diode is connected to the D pole of the field effect transistor and the connection point is set as the second effect point.

[0010] At present, solar photovoltaic charging and discharging technology is increasingly becoming a sustainable and efficient energy solution. This technology uses solar photovoltaic panels to convert sunlight into electrical energy to provide clean energy for RVs. The existing photovoltaic system currently relies heavily on the intensity of sunlight, and weather changes will affect the charging efficiency. In the existing RV photovoltaic charging devices, the photovoltaic panels cannot provide charging when encountering rainy weather or at night. Since the accumulated photovoltaic charging electricity cannot be effectively stored and utilized, the RV may face the problem of insufficient driving power when far away from the power supply, and at the same time leads to high energy loss and lack of good battery balance management. Based on this, the present invention provides a bidirectional charging control device based on photovoltaic charging to solve the problems of high energy loss and low recycling rate of RV photovoltaic charging in the prior art.

[0011] Furthermore, the charging management unit includes a first current sensor F1 and a second current sensor F2, both of which can detect current in both directions, and the signal controller M1 is provided with a first IO terminal I1 and a second IO terminal I2 for transmitting control current; the first current sensor F1 is connected to the first IO terminal I1, and the second current sensor F2 is connected to the second IO terminal I2; the first power terminal L1 is connected to the buck-boost module through the first current sensor F1, and the second power terminal L2 is connected to the buck-boost module through the second current sensor F2, and the buck-boost module is connected to the first IO terminal I1 and the second IO terminal I2.

[0012] Furthermore, the connection point between the first power terminal L1 and the first current sensor F1 is set as endpoint LT, the connection point between the second power terminal L2 and the second current sensor F2 is set as endpoint LK, and a direct wire is connected between the endpoint LT and the endpoint LK; the connection point between the first current sensor F1 and the buck-boost module is set as endpoint LS, and the connection point between the second current sensor F2 and the buck-boost module is set as endpoint LF.

[0013] Furthermore, the buck-boost module includes a first field effect element Q1, a second field effect element Q2, a seventh field effect element Q7 and an eighth field effect element Q8, all of which have the same structure as a field effect diode; the second effect point on the first field effect element Q1 is connected to the same point as the second effect point on the second field effect element Q2 and the third power terminal H; the first effect point of the first field effect element Q1 and the second effect point of the seventh field effect element Q7 are both connected to the terminal LS, and the first effect point of the second field effect element Q2 and the second effect point of the eighth field effect element Q8 are connected to the terminal LF; the first effect point of the seventh field effect element Q7 is connected to the same point as the first effect point and the ground terminal of the eighth field effect element Q8; the G pole of the first field effect element Q1 and the G pole of the seventh field effect element Q7 are both connected to the first IO terminal I1, and the G pole of the second field effect element Q2 and the G pole of the eighth field effect element Q8 are both connected to the second IO terminal I2.

[0014] Furthermore, a first inductor Lm1 is connected between the first current sensor F1 and the endpoint LS, and a second inductor Lm2 is connected between the endpoint LF and the second current sensor F2; the charging management unit also includes a first capacitor C1 and a second capacitor C2; one end of the first capacitor C1 is connected between the first current sensor F1 and the first inductor Lm1, and the other end of the first capacitor C1 is grounded; one end of the second capacitor C2 is connected between the second current sensor F2 and the second inductor Lm2, and the other end of the second capacitor C2 is grounded.

[0015] Furthermore, a first switch module is provided between the first power terminal L1 and the end point LT; and a second switch module is provided in series on the direct-connection wire between the end point LT and the end point LK.

[0016] Furthermore, the first switch module includes a third field effect element Q3 and a fourth field effect element Q4, both of which have the same structure as a field effect diode; the first power terminal L1 is connected to the first effect point of the third field effect element Q3, the second effect point of the third field effect element Q3 is connected to the second effect point of the fourth field effect element Q4, and the first effect point of the fourth field effect element Q4 is connected to the terminal LT.

[0017] Furthermore, the second switch module includes a fifth field effect element Q5 and a sixth field effect element Q6, both of which have the same structure as a field effect diode, a first effect point of the fifth field effect element Q5 is connected to the terminal LT, a second effect point of the fifth field effect element Q5 is connected to the second effect point of the sixth field effect element Q6, and a first effect point of the sixth field effect element Q6 is connected to the terminal LK.

[0018] Furthermore, the charging management unit also includes a third capacitor C3, a first resistor R1 and a first voltage source VCC, the output end of the first voltage source VCC is connected to the same point as one end of the first resistor R1 and the first IO terminal I1, and the first voltage source VCC is kept grounded; the other end of the first resistor R1 is connected to the first power terminal L1; one end of the third capacitor C3 is connected to the third power terminal H, and the other end of the third capacitor C3 is grounded; the second IO terminal I2 is connected to the endpoint LK.

[0019] Furthermore, the signal controller M1 is also provided with a first control terminal A, a second control terminal B and a working state terminal; the G pole of the third field effect element Q3 is connected to the same point as the G pole of the fourth field effect element Q4 and the first control terminal A, and the G pole of the fifth field effect element Q5 is connected to the same point as the G pole of the sixth field effect element Q6 and the second control terminal B; the working state terminal is connected with a first switch C and a second switch D for switching the working mode.

[0020] Compared with the prior art, the present invention, as a vehicle-mounted battery charging control device, has the beneficial effects of efficient charging and discharging, charging of lithium batteries by starting batteries, photovoltaic charging of lithium batteries and starting batteries at a faster speed, and reverse power maintenance of lithium batteries for starting batteries. The reliability of the system and the efficiency of comprehensive utilization of energy are improved. When the starting battery is started, the excess energy can be recycled and utilized more to provide more supplementary energy for the lithium battery; similarly, when the photovoltaic energy is sufficient, it can also provide supplementary power for the lithium battery and the starting battery. This is the main advantage and beneficial effect of the vehicle-mounted battery bidirectional charging control device of this embodiment in terms of battery power supply maintenance. At the same time, due to its small size, it is more suitable as a time-sharing multiplexing power device in the vehicle body, and is more efficient than traditional charging devices. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The drawings described herein are used to provide a further understanding of the embodiments of the present invention, constitute a part of this application, and do not constitute a limitation of the embodiments of the present invention. In the drawings:

[0022] Figure 1 It is a schematic diagram of the circuit structure of the present invention;

[0023] Figure 2 This is an application schematic diagram of the implementation process of the present invention of vehicle charging, starting battery charging and photovoltaic charging;

[0024] Figure 3 It is an application schematic diagram of the step-down MPPT implementation process of the present invention;

[0025] Figure 4 It is a schematic diagram of the structure and application of an additional implementation method in the process of implementing the step-down MPPT of the present invention;

[0026] Figure 5 It is an application schematic diagram of the implementation process of the boost MPPT of the present invention;

[0027] Figure 6 This is a schematic diagram of the circuit structure of the relay used in the present invention;

[0028] Figure 7 This is a schematic diagram of the structure of the present invention being mounted on a vehicle for implementation;

[0029] Figure 8 It is a schematic diagram of the module structure of the buck-boost DC-DC of the present invention when it is working. DETAILED DESCRIPTION

[0030] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with embodiments and drawings. The exemplary embodiments of the present invention and their description are only used to explain the present invention and are not intended to limit the present invention. Example

[0031] like Figure 1 As shown, this embodiment is a bidirectional charging control device based on photovoltaic charging, including an energy transmission end for being arranged on a driving circuit of a motorhome, wherein the energy transmission end includes a first power end L1, a second power end L2 and a third power end H which are connected together, and is characterized in that the device further includes:

[0032] Charging management unit: used to monitor the voltage and current status of the first power terminal L1 and the second power terminal L2, automatically adjust the charging strategy according to the battery power, realize CCCV constant current charging, and decide when to start charging and discharging of the third power terminal H;

[0033] Energy conversion unit: used to set a buck-boost module, which cooperates with the first power terminal L1, the second power terminal L2 and the third power terminal H to perform the boost MPPT and buck MPPT working processes;

[0034] Photovoltaic loop unit: maintains signal connection between the charging management unit and the energy conversion unit, and is equipped with a signal controller M1 to control the energy transmission end, so that each energy transmission end maintains the input and output switching of the battery and photovoltaic;

[0035] Among them, the charging management unit and the energy conversion unit include a number of field effect diodes, the third power terminal H is connected and arranged in the buck-boost module, and the buck-boost module is composed of a number of field effect diodes; the field effect diode includes a diode and an N-channel field effect transistor, the positive electrode of the diode is connected to the S pole of the field effect transistor and the connection point is set as the first effect point, and the negative electrode of the diode is connected to the D pole of the field effect transistor and the connection point is set as the second effect point.

[0036] This embodiment mainly includes multiple specific implementation processes such as photovoltaic charging, driving charging, starting battery charging, boost MPPT, buck MPPT, boost DC-DC and buck DC-DC. In the process of photovoltaic charging, driving charging and starting battery charging, the first power terminal L1 and the second power terminal L2 are connected to the car starting battery and the car lithium battery respectively, and the third power terminal H is connected to the photovoltaic input terminal (i.e., PV terminal) of the solar panel. The boost DC-DC and buck DC-DC are used to output current and voltage according to a predetermined set value or an external pre-set communication signal. When performing photovoltaic charging, a voltage and current sensor is used to monitor the voltage and current state of the first power terminal L1 and the second power terminal L2 in real time, and the remaining power of the battery is calculated based on the collected data, which is usually estimated by the relationship between the battery voltage and its charging state. In the specific implementation, a power threshold value can be set, such as low power, moderate power, full power, etc., and the charging strategy to be adopted can be determined according to the current state of the battery. When the battery power is low, the third power terminal H is started first for charging; when the battery power is within a moderate range, the CCCV charging mode is maintained and the second battery terminal L2 continues to be charged; when the battery power reaches the set upper limit, charging is stopped or switched to maintenance mode. The signal controller M1 starts constant current charging and sets the charging current within a safe range. When the battery power reaches the set value, it switches to constant voltage charging to keep the voltage stable and ensure safe charging of the battery. When it is detected that the battery power is low and there is sufficient light at the third power terminal, the signal controller M1 decides to start the third power terminal H. The signal controller M1 runs the maximum power point tracking (MPPT) algorithm to adjust the duty cycle of the photovoltaic input in real time to maximize energy output. During the photovoltaic charging process, the second circuit provides a direct power transmission path, allowing the third power terminal H to charge the second power terminal L2 through the first power terminal L1, ensuring that the photovoltaic energy can be quickly and effectively transferred to the lithium battery.

[0037] Furthermore, the charging management unit includes a first current sensor F1 and a second current sensor F2, both of which can detect current in both directions, and the signal controller M1 is provided with a first IO terminal I1 and a second IO terminal I2 for transmitting control current; the first current sensor F1 is connected to the first IO terminal I1, and the second current sensor F2 is connected to the second IO terminal I2; the first power terminal L1 is connected to the buck-boost module through the first current sensor F1, and the second power terminal L2 is connected to the buck-boost module through the second current sensor F2, and the buck-boost module is connected to the first IO terminal I1 and the second IO terminal I2.

[0038] Furthermore, the connection point between the first power terminal L1 and the first current sensor F1 is set as endpoint LT, the connection point between the second power terminal L2 and the second current sensor F2 is set as endpoint LK, and a direct wire is connected between the endpoint LT and the endpoint LK; the connection point between the first current sensor F1 and the buck-boost module is set as endpoint LS, and the connection point between the second current sensor F2 and the buck-boost module is set as endpoint LF.

[0039] Furthermore, the buck-boost module includes a first field effect element Q1, a second field effect element Q2, a seventh field effect element Q7 and an eighth field effect element Q8, all of which have the same structure as a field effect diode; the second effect point on the first field effect element Q1 is connected to the same point as the second effect point on the second field effect element Q2 and the third power terminal H; the first effect point of the first field effect element Q1 and the second effect point of the seventh field effect element Q7 are both connected to the terminal LS, and the first effect point of the second field effect element Q2 and the second effect point of the eighth field effect element Q8 are connected to the terminal LF; the first effect point of the seventh field effect element Q7 is connected to the same point as the first effect point and the ground terminal of the eighth field effect element Q8; the G pole of the first field effect element Q1 and the G pole of the seventh field effect element Q7 are both connected to the first IO terminal I1, and the G pole of the second field effect element Q2 and the G pole of the eighth field effect element Q8 are both connected to the second IO terminal I2.

[0040] Furthermore, a first inductor Lm1 is connected between the first current sensor F1 and the endpoint LS, and a second inductor Lm2 is connected between the endpoint LF and the second current sensor F2; the charging management unit also includes a first capacitor C1 and a second capacitor C2; one end of the first capacitor C1 is connected between the first current sensor F1 and the first inductor Lm1, and the other end of the first capacitor C1 is grounded; one end of the second capacitor C2 is connected between the second current sensor F2 and the second inductor Lm2, and the other end of the second capacitor C2 is grounded.

[0041] Furthermore, a first switch module is provided between the first power terminal L1 and the end point LT; and a second switch module is provided in series on the direct-connection wire between the end point LT and the end point LK.

[0042] Furthermore, the first switch module includes a third field effect element Q3 and a fourth field effect element Q4, both of which have the same structure as a field effect diode; the first power terminal L1 is connected to the first effect point of the third field effect element Q3, the second effect point of the third field effect element Q3 is connected to the second effect point of the fourth field effect element Q4, and the first effect point of the fourth field effect element Q4 is connected to the terminal LT.

[0043] Furthermore, the second switch module includes a fifth field effect element Q5 and a sixth field effect element Q6, both of which have the same structure as a field effect diode, a first effect point of the fifth field effect element Q5 is connected to the terminal LT, a second effect point of the fifth field effect element Q5 is connected to the second effect point of the sixth field effect element Q6, and a first effect point of the sixth field effect element Q6 is connected to the terminal LK.

[0044] Furthermore, the charging management unit also includes a third capacitor C3, a first resistor R1 and a first voltage source VCC, the output end of the first voltage source VCC is connected to the same point as one end of the first resistor R1 and the first IO terminal I1, and the first voltage source VCC is kept grounded; the other end of the first resistor R1 is connected to the first power terminal L1; one end of the third capacitor C3 is connected to the third power terminal H, and the other end of the third capacitor C3 is grounded; the second IO terminal I2 is connected to the endpoint LK.

[0045] Furthermore, the signal controller M1 is also provided with a first control terminal A, a second control terminal B and a working state terminal; the G pole of the third field effect element Q3 is connected to the same point as the G pole of the fourth field effect element Q4 and the first control terminal A, and the G pole of the fifth field effect element Q5 is connected to the same point as the G pole of the sixth field effect element Q6 and the second control terminal B; the working state terminal is connected with a first switch C and a second switch D for switching the working mode.

[0046] Regarding the specific implementation of this embodiment, when charging while driving, the ACC enable terminal on the signal controller M1 is closed, the first switch module remains open, the vehicle engine is started, and the first power terminal L1 provides power to various systems of the vehicle. At this time, the current flows from the starting battery along the first power terminal L1 to the first current sensor F1, stores the current energy through the first inductor Lm1 and makes the seventh field effect element Q7 conductive, and then the seventh field effect element Q7 is turned off, and the electric energy stored in the first inductor Lm1 flows into the first field effect element Q1 and reaches the third power terminal H. The remaining current is transmitted to the second inductor Lm2 through the second field effect element Q2 and reaches the lithium battery terminal of the second power terminal L2. In the specific implementation of this embodiment, the current limit of the first current sensor F1 and the second current sensor F2 is 40A. If one of the first current sensor F1 and the second current sensor F2 reaches 40A current first, the current value in the entire device will no longer increase.

[0047] More, such as Figure 7As shown, the starting battery is arranged at the head of the vehicle, the lithium battery and the signal controller M1 are arranged at the rear of the vehicle, the photovoltaic input end is derived from the photovoltaic solar panel arranged on the roof, and the starting battery, the lithium battery and the photovoltaic solar panel are connected to each other by signals. Among them, the engine G is connected to the signal above the starting battery, and the engine G, the signal controller M1 and the starting battery are connected through the starting battery charging cable. The starting battery and the signal controller M1 are connected to the signal through the voltage acquisition line. The ACC enabling end power supply line on the signal controller M1 is connected to the same point as the voltage acquisition line and the starting battery charging cable, and an external start switch is arranged on the ACC enabling end power supply line. When the ACC enabling end is started, the starting signal is transmitted to the signal controller M1, and at the same time, the starting battery uses the signal connection line as the voltage acquisition line to transmit the voltage information to the signal controller M1. Similarly, at the lithium battery end, the signal connection line is used as the voltage acquisition line to transmit the voltage information to the signal controller M1. In the specific application of driving charging, when there is photovoltaic power and the vehicle is in parking power mode, when the voltage of the starting battery is higher than the preset protection voltage value, the photovoltaic energy is also used to charge the lithium battery first after the starting battery starts running, and the starting battery is charged after the lithium battery is full; when the voltage of the starting battery is lower than the preset protection voltage value, the photovoltaic power will be used to charge the starting battery first, and then the lithium battery. That is, in the case of photovoltaic power, photovoltaic energy will first ensure that the starting battery has sufficient power, and then charge the starting battery and lithium battery at the same time after the starting battery meets the demand. When the starting battery also has enough starting power (that is, it reaches the preset protection voltage value, such as set to charge to 12.5V), the starting battery has enough starting energy at this time. At this time, the power of solar energy will be introduced into the energy storage lithium battery. At this time, the two-way charging is switched to twice the speed to charge the energy storage lithium battery, which will fill it in the shortest time. When the energy storage lithium battery is full, the photovoltaic input end will put all the remaining charging power on the maintenance of the starting battery, that is, to keep it in a fully charged state, which can also be called the pre-charge state. It not only meets the starting energy demand of the starting battery, but also can quickly charge the energy storage battery to the maximum extent. When this embodiment is applied to the field of RVs, since RVs are not used frequently and are parked for a long time, this charging method can better maintain the RV energy storage battery, so that the energy storage battery can be fully charged for a long time. At the same time, it can also ensure that the starting battery is in a state of power for a long time, avoiding damage to the starting battery due to insufficient power due to long-term idleness; it can also maximize the utilization of power when driving and reduce the consumption of gasoline or other energy sources. When there is no photovoltaic input, in order to ensure that the starting battery has enough energy, when the system detects that the voltage of the first power terminal L1 is lower than the preset protection voltage value, the device will automatically start the lithium battery to replenish the starting battery until its voltage reaches the set protection voltage value.The protection voltage value can be set according to the conventional size or experience evaluation in this field. When the ACC enabling end is in the startup state and the voltage at one end of the starting battery is higher than the protection voltage value, the vehicle starts and enters the driving charging mode. At this time, the generator G end charges the vehicle's starting battery, and one end of the generator G generates a DCDC boost to the third power end H to merge with the photovoltaic energy. The power of the starting battery is connected to the signal controller M1 through the starting battery charging cable and starts to boost the system. The boosted energy is merged at the photovoltaic input end and then charged to the lithium battery through the step-down DCDC of the second power end L2. Since the working point of the photovoltaic panel is different when the working voltage is different, the output effective power under different voltage conditions is also different. Therefore, in the implementation process, the signal controller M1 system can be boosted and the boost size can be adjusted to control the output effective power. Feedback. The effective power of the first power end L1 plus the effective power of the photovoltaic input end is equal to the power value of the second power end L2. By manipulating the control point of the voltage of the signal controller M1, the voltage suspension of the first power end L1 can be adjusted, so as to indirectly control the system to find the best working point. In a specific implementation, the voltage value of the solar photovoltaic panel connected to the photovoltaic input terminal is usually controlled at about 18V, that is, when the voltage value is controlled at 15-18V, the solar photovoltaic panel is at the maximum working point. Therefore, as a preferred embodiment, two photovoltaic panels can be set in parallel in a specific implementation to set the no-load range to about 40V, so that the boost voltage value can fluctuate in the range of 20V-40V, which means that the maximum power point is limited to the range of 20V-40V. As a specific application, based on the principle of power conservation, the actual output power and the efficiency of the step-down system can be determined in advance, the product of the power and the efficiency value of the first power terminal L1 is set as the first product, the product of the photovoltaic power and the efficiency value of the third power terminal H is set as the second product, and the sum of the first product and the second product is multiplied by the step-down system efficiency to obtain the actual output power, from which the photovoltaic power value of the third power terminal H can be inversely deduced. For example, in the specific implementation, the boost efficiency of the first power terminal L1 is set to 96%, at which time it can be calculated how much energy is injected into the third power terminal H, and then the second power terminal L2 is measured externally, and the energy value of the third power terminal H is divided by 96%, which is equal to the energy value of the second power terminal L2, so the energy value of the third power terminal H can be calculated. At this time, the signal controller M1 will perform a voltage scan on the first power terminal L1 according to a fixed period. Due to the load characteristics of the photovoltaic panel, when the current reaches a certain value, its voltage value will drop. At this time, it is equivalent to letting the test photovoltaic panel perform voltage value calculations at different working points to determine at which moment the energy of the solar photovoltaic panel reaches the maximum.

[0048] When recharging the starting battery, it is usually used when the vehicle is in long-term static operation and there is no photovoltaic condition. Based on the same principle, the first power terminal L1 is charged from the second power terminal L2. The current flows from the second power terminal L2 through the second current sensor F2 along the second field effect element Q2 and the first field effect element Q1 to the first current sensor F1 until it flows into the first power terminal L1, that is, taking away part of the power from the lithium battery to provide it to the starting battery 1 for starting the engine. In this specific implementation process, the charging state of the second power terminal L2 may be monitored to ensure that its power is not over-consumed. Once the power of the first power terminal L1 is restored to the set value, the system will stop charging. If the first power terminal L1 is fully charged, the system will automatically adjust the priority to prevent unnecessary energy loss. Through the precise monitoring and control mechanism, the first power terminal L1 is effectively recharged, ensuring that its power is sufficient during the operation of the vehicle, and enhancing the reliability and operation efficiency of the system. Recharging the starting battery can only be performed when the power of the starting battery is low.

[0049] More specifically, when photovoltaic charging is performed, the signal controller M1 is used to turn off the first switch module and turn on the second switch module. At this time, the first power terminal L1 remains disconnected from the charging system. At this time, the second power terminal L2 and the third power terminal H are in a dual-circuit connection state. The third power terminal H is connected to the photovoltaic input terminal and inputs the photovoltaic solar energy into the lithium battery of the second power terminal L2. At this time, the duty cycles of the first field effect element Q1 and the second field effect element Q2 are the same; when the sum of the currents of the first current sensor F1 and the second current sensor F2 reaches the maximum, this is the tracking point of the MPPT. At this time, the system can achieve the maximum power of the dual-circuit photovoltaic solar energy step-down by stepping down the voltage, so that the amplitude of the solar energy power downloaded to the lithium battery is maximized. In specific applications, such as Figure 1 As shown, the dual circuit includes a first circuit and a second circuit. The first circuit flows into the second power terminal L2 along the second field effect element Q2 and the second current sensor F2. The second circuit flows along the first field effect element Q1, the first current sensor F1 and the second switch module along the direct wire to the endpoint LK and then to the second power terminal L2. When the second power terminal L2 is fully charged, the first switch module can be turned on and the second switch module can be turned off. The third power terminal H can also transmit power to the first power terminal L1 to charge the starting battery. The photovoltaic charging process can only be carried out under photovoltaic conditions, and photovoltaic charging of the starting battery must also be carried out when the power of the starting battery is low. In specific implementation, Figure 6 As shown, the first switch module and the second switch module can both be configured as relays. Figure 6The first switch module is set as the first relay K1, the second switch module is set as the second relay K2, the first control terminal A is connected to the enable terminal of the first relay K1, and the second control terminal B is connected to the enable terminal of the second relay K2. As a feasible application mode, the start-up mode of the first control terminal A and the second control terminal B can be set to set a voltage threshold for the first control terminal A and the second control terminal B, and when the voltage value flowing through the first switch module and the second switch module is higher than the voltage threshold, the first relay K1 and the second relay K2 are respectively started.

[0050] Further, regarding the working process of boost MPPT and buck MPPT, when performing boost maximum power point tracking (boost MPPT), the first power terminal L1 and the second power terminal L2 are connected in parallel to the photovoltaic input terminal, and the third power terminal H is connected to the lithium battery terminal. The voltage and current generated by the RV photovoltaic panel are constantly changing under lighting conditions, and the signal controller M1 monitors these changes in real time to determine the maximum power point. According to the output of the third power terminal H, the MPPT algorithm adjusts the working state of the first field effect element Q1 to optimize the output power of the photovoltaic panel. When performing buck maximum power point tracking (buck MPPT), the first power terminal L1 and the second power terminal L2 are connected in parallel to the car lithium battery, and the third power terminal H is connected to the photovoltaic input terminal. To find the best working point of the third power terminal H, that is, the maximum power point; according to the output change of the photovoltaic panel, dynamically adjust the duty cycle of the second field effect element Q2; when transmitting power, the output power of the third power terminal H is transmitted to the second power terminal L2 through the second field effect element Q2, and the second field effect element Q2 converts the photovoltaic power into a voltage and current suitable for charging the lithium battery according to the instructions of the controller.

[0051] Regarding the process of boosting and bucking MPPT, when the MPPT bucking is performed based on the buck circuit function, when the input comes from the third power terminal H, the first field effect element Q1 is in a high voltage state, that is, when the third power terminal H is input through the photovoltaic holding voltage, the first field effect element Q1 is opened in a current driving manner through the first IO terminal I1 of the signal controller M1. At this time, the current enters from the third power terminal H and flows through the first inductor Lm1 through the first current sensor F1 and then flows to the battery of the first power terminal L1. At this time, the third field effect element Q3 and the fourth field effect element Q4 as switches remain in the open state. In this process, the signal controller M1 can be operated to control the duty cycle of each field effect element (i.e., MOS tube) to control the current. At the same time, the first current sensor F1 is used to measure the size of the flowing current, and the specific current value can be adjusted as needed to adjust the duty cycle of the first field effect element Q1, so that the circuit can charge the battery with photovoltaic energy in the form of electrical energy within a certain load range. At this time, the signal controller M1 will keep monitoring the voltage value of the third power terminal H. When the circuit maintains a constant current state, the tracking voltage of the third power terminal H is adjusted and changed in real time during the implementation process. In order to utilize the power of the third power terminal H as much as possible, the third power terminal H is kept voltage scanned to find the best power point, so that the entire system can utilize more PV photovoltaic energy and use less generators. The implementation process also includes synchronous rectification, that is, when the first field effect element Q1 is turned off, the seventh field effect element Q7 is turned on after a dead time, and the freewheeling current can pass through the N channel of the field effect tube body of the seventh field effect element Q7, which can avoid passing through the diode part so that the loss can be reduced. When the MPPT boost is used based on the boost circuit function, the lithium battery transmits electric energy to the first current sensor F1 through the first power terminal L1, stores energy through the first inductor Lm1, and then short-circuits to the ground through the seventh field effect element Q7; when the seventh field effect element Q7 is turned off, the current of the first inductor Lm1 will continue to flow to the diode part of the first field effect element Q1 and then continue to flow to the third power terminal H. In a specific implementation, the switching process between the step-down MPPT and the step-up MPPT can be reflected as follows: if the signal controller M1 is used to first turn on the first field effect element Q1, the current flows from Figure 1 As shown, the current flows from the upper part to the lower part, and as a whole, it flows from the third power terminal H to the first power terminal L1, which is a step-down process; if the seventh field effect element Q7 is turned on first, the current will flow from the first power terminal L1 to the third power terminal H, which is a step-up process. In particular, when the step-up MPPT working process is in progress, after the signal controller M1 stops sending the control signal, the system charging process stops, because the input voltage of the power supply is lower than the load voltage, so it will no longer charge.

[0052] The input end of the signal controller M1 includes a first IO terminal I1 and a second IO terminal I2, and the first IO terminal I1 and the second IO terminal I2 are both used as the input terminal and the output terminal of the signal controller M1. The first IO terminal I1 mainly inputs the current of the first current controller F1 and the voltage directly obtained from the voltage source of the first power terminal L1, and the second IO terminal I2 mainly inputs the current of the second current controller F2 and the voltage directly obtained from the branch of the second power terminal L2. The voltage directly obtained by the first IO terminal I1 from the voltage source of the first power terminal L1 can avoid additional loss of current in the circuit and avoid additional loss being superimposed on the measurement error. The signal controller M1 directly drives all field effect diodes in the device, including the field effect diodes of the first switch module and the second switch module, through the first IO terminal I1 and the second IO terminal I2 in a manner of adjusting the current size. When the first switch module is driven and controlled, the purpose of the control is mainly to switch the input and output by switching the working states of the third field effect element Q3 and the fourth field effect element Q4, that is, when the current flows from the third power terminal H to the first power terminal L1 or from the first power terminal L1 to the third power terminal H, the first switch module can smoothly cooperate with the current to complete the specified flow direction. During the control process, the signal controller M1 simultaneously controls a total of six output branches, namely, the first field effect element Q1, the second field effect element Q2, the seventh field effect element Q7, the eighth field effect element Q8, the first switch module and the second switch module.

[0053] In particular, the working state end is connected with a first switch C and a second switch D for switching the working mode, and the first switch C and the second switch D are used to adjust the working state of the signal controller M1 by switching between high and low levels, that is, it includes four logical states of 00, 01, 10, and 11, which correspond to four working modes respectively. As a feasible specific application, in a specific implementation, the corresponding settings of the logical state and the working mode of the working state end include: keeping the first switch C and the first switch D closed, that is, when the logic input is 00, the signal controller M1 switches the device to the working state of driving charging; disconnecting the first switch C and closing the first switch D, that is, when the logic input is 01, the signal controller M1 switches the device to the working state of the step-down MPPT; closing the first switch C and disconnecting the first switch D, that is, when the logic input is 10, the signal controller M1 switches the device to the working state of the boost MPPT; closing the first switch C and the second switch D, that is, when the logic input is 11, as shown in FIG. Figure 8As shown, the signal controller M1 switches the device to the buck-boost DC-DC working state. In a specific implementation, the buck-boost DC-DC performs the output of current and voltage according to a predetermined setting value or an externally preset communication signal. The working mode of the device is set by communication. At this time, the first power terminal L1 and the second power terminal L2 are independently controlled, that is, the values ​​of the uplink power and the downlink power are respectively independent, and the user can independently control the current and voltage of the two sides in the uplink and downlink respectively through the external control module. In actual use, the signal controller M1 is sent a control instruction through the external control module, and the working mode or working parameter state of the first power terminal L1 and the second power terminal L2 is adjusted through the signal controller M1. When the first power terminal L1 and the second power terminal L2 are turned on for output, the voltage and current values ​​of the uplink or downlink power on both sides are preset. Since both sides are independently set, independent instructions can be issued to the first power terminal L1 and the second power terminal L2 for control, and the first power terminal L1 and the second power terminal L2 can be connected to different batteries respectively. The first power terminal L1 and the second power terminal L2 can also close both ends to set the duty cycle locking mode, which is used to control the size of the current and voltage flow. The process can also be from the first power terminal L1 to the second power terminal L2, or the first power terminal L1 and the second power terminal L2 can be set to be in the up state. This process is a bidirectional DC-DC buck-boost, which is coordinated by the signal controller M1 and turned on or off by an external switching switch. When the first power terminal L1 is up to the third power terminal H, the system performs a voltage closed loop, and when it is down from the third power terminal H to the second power terminal L2, the system performs a current closed loop. At the same time, the bidirectional DC-DC can work separately, and set the current and voltage parameters and change the uplink or downlink working mode according to the preset requirements of the external communication.

[0054] Regarding the power control of the signal controller M1 from the first power terminal L1 to the second power terminal L2 in the DC-DC process, it is mainly completed through the field effect element in the loop, and the duty cycle of each field effect element is determined by the rated voltage value of the third power terminal H. The voltage value of the target field effect element is raised to the required set value for power control. In the specific implementation, when the voltage is raised from the first power terminal L1 to the third power terminal H, it is in a voltage closed loop state; when the voltage is boosted from the second power terminal L2 to the third power terminal H, the first power terminal L1 is in a voltage reduction state, and the voltage value dropped during the voltage reduction process is a pre-set limited voltage value for the starting battery. In the entire loop, there is also a current limit value for both the first power terminal L1 and the second power terminal L2. When the current value in the loop reaches the current limit value, the current stops increasing; the setting of the current limit value is mainly used to limit the size of the current output value of the signal controller M1, and the size of the current output value is usually less than the current limit value. In the specific implementation, the current limit value can be set to 43A, and the actual current output value will be less than or equal to 40A. In order to avoid current overload in the series circuit, a current closed loop will be formed in the device, and the feedback point will be reached first. When there is no photovoltaic solar energy, the electric energy will be directly transmitted from the first power terminal L1 to the second power terminal L2. Due to the difference in efficiency value, the power value of the second power terminal L2 will be slightly lower than the power value of the first power terminal L1; after using photovoltaic solar energy, the third power terminal H connected to the photovoltaic input is introduced. During the energy transmission process, the current of the photovoltaic energy on the solar panel will be introduced. At this time, the signal controller M1 will perform MPPT scanning on the energy of the third power terminal H to find a suitable voltage stabilization value, which can ensure that the photovoltaic energy of the third power terminal can be output with the highest efficiency. At this time, it can be obtained at the same voltage operating point that the voltage value of the second power terminal L2 will be higher than the voltage value of the first power terminal L1. At this time, the second power terminal L2 obtains the maximum power. Under the support of photovoltaics, the second power terminal L2 can reach a maximum current of 40A. The signal controller M1 will continue to scan the photovoltaic energy, so that the system can use the photovoltaic energy in the most efficient state as much as possible, so as to maximize the use of photovoltaic solar energy. That is, the signal controller M1 searches for the optimal power point of photovoltaic energy based on MPPT in the system's continuous dynamic balance state, and obtains the size of the photovoltaic energy value through indirect deduction.

[0055] It should be noted that if Figure 1-Figure 7As shown, each implementation stage in this embodiment requires external power supply to keep the ACC enable end of the signal controller M1 at a high level before it can be carried out. The ACC enable end is used to start the car engine and keep it running; when the ACC enable end is in a low level state, the vehicle remains in a parking state. During driving charging, when the ACC enable end is in a working state, the vehicle is in a vehicle power supply state. At this time, the current of the signal controller M1 remains in a flow charging state from the first power end L1 to the second power end L2, that is, from the starting battery to the lithium battery. At this time, the system preferentially uses photovoltaic energy; when the ACC enable end is not working, the vehicle is in a parking state. At this time, the received photovoltaic energy is preferentially charged to the lithium battery end of the second power end L2, and the power is charged to the starting battery of the first power end L1 after the lithium battery is fully charged. When the starting battery voltage is too low (that is, lower than the set threshold), the lithium battery reversely supplies power to the starting battery.

[0056] More specifically, as a preferred feasible implementation, in the step-down MPPT process, it also includes a ninth field effect element Q9 and a tenth field effect element Q10; the first effect point of the ninth field effect element Q9 is connected to the third power terminal H, and the second effect point is connected to the photovoltaic input terminal PV; the first effect point of the tenth field effect element Q10 is connected to the terminal LK, and the second effect point is connected to the second current sensor F2; the signal controller M1 is also provided with a communication terminal and a MOS output protection terminal; when the step-up MPPT working process is performed, the system charging process stops after the signal controller M1 stops sending the control signal. When the step-down MPPT is working, if the first field effect element Q1 or the second field effect element Q2 is damaged and broken down, the high voltage current will be directly injected into the low voltage end. Therefore, in order to enhance safety, a ninth field effect element Q9 is added to the third power terminal H for photovoltaic input during the step-down process to cut off the input voltage in advance; the purpose of the tenth field effect element Q10 is the same, which is used to cut off the voltage in the low voltage output part to prevent strong current from directly entering the lithium battery through the second power terminal L2; the MOS output protection terminal is used to send a secondary protection control signal through the signal controller M1 when the field effect diode breaks down and is damaged, and the first switch module and the second switch module are disconnected to prevent strong current from being input from the first power terminal L1 to the lithium battery, so as to ensure the safety of the system. In the specific implementation of photovoltaic charging, if the first field effect element Q1 and the second field effect element Q2 are broken down, the current output of the first current sensor F1 will be blocked at the second switch module, and the current output of the second current sensor F2 will also be blocked at the tenth field effect element Q10 to protect the safety of the system circuit. When the current regulation is out of control or the input voltage of the solar photovoltaic panel is too high, the ninth field effect element Q9 will be closed to cut off the photovoltaic to protect the device.

[0057] As a vehicle-mounted battery charging control device, this embodiment has the beneficial effects of efficient charging and discharging, charging of lithium batteries by starting batteries, photovoltaic charging of lithium batteries and starting batteries at a faster speed, and reverse power maintenance of lithium batteries for starting batteries. The reliability of the system and the efficiency of comprehensive utilization of energy are improved. When the starting battery is started, the excess energy can be recycled and utilized more to provide more supplementary energy for the lithium battery; similarly, when the photovoltaic energy is sufficient, it can also provide supplementary power for the lithium battery and the starting battery. This is the main advantage and beneficial effect of the vehicle-mounted battery bidirectional charging control device of this embodiment in terms of battery power supply maintenance. At the same time, due to its small size, it is more suitable as a time-sharing multiplexing power device in the vehicle body, and is more efficient than traditional charging devices.

[0058] The specific implementation methods described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific implementation method of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A bidirectional charging control device based on photovoltaic charging, comprising an energy transmission terminal for being arranged on a driving circuit of a motorhome, wherein the energy transmission terminal comprises a first power terminal L1, a second power terminal L2 and a third power terminal H which are connected to each other, characterized in that: The device also includes: Charging management unit: used to monitor the voltage and current status of the first power terminal L1 and the second power terminal L2, automatically adjust the charging strategy according to the battery power, realize CCCV constant current charging, and decide when to start charging and discharging of the third power terminal H; Energy conversion unit: used to set a buck-boost module, which cooperates with the first power terminal L1, the second power terminal L2 and the third power terminal H to perform the boost MPPT and buck MPPT working processes; Photovoltaic loop unit: maintains signal connection between the charging management unit and the energy conversion unit, and is equipped with a signal controller M1 to control the energy transmission end, so that each energy transmission end maintains the input and output switching of the battery and photovoltaic; Wherein, the charging management unit and the energy conversion unit include a number of field effect diodes, the third power terminal H is connected to the buck-boost module, and the buck-boost module is composed of a number of field effect diodes; the field effect diode includes a diode and an N-channel field effect transistor, the positive electrode of the diode is connected to the S pole of the field effect transistor and the connection point is set as the first effect point, and the negative electrode of the diode is connected to the D pole of the field effect transistor and the connection point is set as the second effect point; The charging management unit includes a first current sensor F1 and a second current sensor F2, both of which can detect current in both directions. The signal controller M1 is provided with a first IO terminal I1 and a second IO terminal I2 for transmitting control current; the first current sensor F1 is connected to the first IO terminal I1, and the second current sensor F2 is connected to the second IO terminal I2; the first power terminal L1 is connected to the buck-boost module through the first current sensor F1, and the second power terminal L2 is connected to the buck-boost module through the second current sensor F2, and the buck-boost module is connected to the first IO terminal I1 and the second IO terminal I2.

2. A bidirectional charging control device based on photovoltaic charging according to claim 1, characterized in that: The connection point between the first power terminal L1 and the first current sensor F1 is set as the endpoint LT, the connection point between the second power terminal L2 and the second current sensor F2 is set as the endpoint LK, and a direct wire is connected between the endpoint LT and the endpoint LK; the connection point between the first current sensor F1 and the buck-boost module is set as the endpoint LS, and the connection point between the second current sensor F2 and the buck-boost module is set as the endpoint LF.

3. A bidirectional charging control device based on photovoltaic charging according to claim 2, characterized in that: The buck-boost module includes a first field effect element Q1, a second field effect element Q2, a seventh field effect element Q7 and an eighth field effect element Q8, all of which have the same structure as a field effect diode; the second effect point on the first field effect element Q1 is connected to the same point as the second effect point on the second field effect element Q2 and the third power terminal H; the first effect point of the first field effect element Q1 and the second effect point of the seventh field effect element Q7 are both connected to the end point LS, and the first effect point of the second field effect element Q2 and the second effect point of the eighth field effect element Q8 are connected to the end point LF; the first effect point of the seventh field effect element Q7 is connected to the same point as the first effect point and the ground terminal of the eighth field effect element Q8; the G pole of the first field effect element Q1 and the G pole of the seventh field effect element Q7 are both connected to the first IO terminal I1, and the G pole of the second field effect element Q2 and the G pole of the eighth field effect element Q8 are both connected to the second IO terminal I2.

4. A bidirectional charging control device based on photovoltaic charging according to claim 3, characterized in that: A first inductor Lm1 is connected between the first current sensor F1 and the endpoint LS, and a second inductor Lm2 is connected between the endpoint LF and the second current sensor F2; the charging management unit also includes a first capacitor C1 and a second capacitor C2; one end of the first capacitor C1 is connected between the first current sensor F1 and the first inductor Lm1, and the other end of the first capacitor C1 is grounded; one end of the second capacitor C2 is connected between the second current sensor F2 and the second inductor Lm2, and the other end of the second capacitor C2 is grounded.

5. A bidirectional charging control device based on photovoltaic charging according to claim 3, characterized in that: A first switch module is arranged between the first power terminal L1 and the end point LT; and a second switch module is arranged in series on the direct-connection wire between the end point LT and the end point LK.

6. A bidirectional charging control device based on photovoltaic charging according to claim 5, characterized in that: The first switch module includes a third field effect element Q3 and a fourth field effect element Q4, both of which have the same structure as a field effect diode; the first power terminal L1 is connected to the first effect point of the third field effect element Q3, the second effect point of the third field effect element Q3 is connected to the second effect point of the fourth field effect element Q4, and the first effect point of the fourth field effect element Q4 is connected to the terminal LT.

7. A bidirectional charging control device based on photovoltaic charging according to claim 6, characterized in that: The second switch module includes a fifth field effect element Q5 and a sixth field effect element Q6, both of which have the same structure as a field effect diode, a first effect point of the fifth field effect element Q5 is connected to the terminal LT, a second effect point of the fifth field effect element Q5 is connected to the second effect point of the sixth field effect element Q6, and a first effect point of the sixth field effect element Q6 is connected to the terminal LK.

8. A bidirectional charging control device based on photovoltaic charging according to claim 1, characterized in that: The charging management unit also includes a third capacitor C3, a first resistor R1 and a first voltage source VCC, wherein the output end of the first voltage source VCC is connected to the same point as one end of the first resistor R1 and the first IO terminal I1, and the first voltage source VCC is kept grounded; the other end of the first resistor R1 is connected to the first power terminal L1; one end of the third capacitor C3 is connected to the third power terminal H, and the other end of the third capacitor C3 is grounded; the second IO terminal I2 is connected to the endpoint LK.

9. A bidirectional charging control device based on photovoltaic charging according to claim 7, characterized in that: The signal controller M1 is also provided with a first control terminal A, a second control terminal B and a working state terminal; the G pole of the third field effect element Q3 is connected to the same point as the G pole of the fourth field effect element Q4 and the first control terminal A, and the G pole of the fifth field effect element Q5 is connected to the same point as the G pole of the sixth field effect element Q6 and the second control terminal B; the working state terminal is connected with a first switch C and a second switch D for switching the working mode.

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