Hybrid power supply system, control method thereof and photovoltaic air conditioner

Abstract

The invention discloses a hybrid power supply system, a photovoltaic air conditioner and a control method of the hybrid power supply system, and the device comprises an obtaining unit which obtains the photovoltaic voltage of a photovoltaic module, the energy storage voltage of an energy storage battery, the state of whether the energy storage battery needs to be charged, the state of whether a DC load needs to be powered, and the load voltage needed by the DC load; the control unit combines the photovoltaic voltage of the photovoltaic module, the energy storage voltage of the energy storage battery, the state whether the energy storage battery needs to be charged or not, the state whether the direct current load needs to be powered or not and the load voltage needed by the direct current load; the selection mode of the switch and the buck-boost mode of the buck-boost unit are selected by controlling on and off of the first switch, the second switch and the third switch. According to the scheme, the voltage conversion among the photovoltaic module, the energy storage battery and the direct current load is realized by adopting one set of buck-boost unit, the conversion power loss and the equipment cost are reduced, and the energy storage efficiency is improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of hybrid power supply systems, and specifically relates to a hybrid power supply system and a control method thereof, and a photovoltaic air conditioner having the hybrid power supply system, and more particularly to a photovoltaic energy storage DCDC converter with a hybrid BUCK circuit and BOOST circuit topology and a control method thereof, and a photovoltaic air conditioner having the photovoltaic energy storage DCDC converter. Background Art

[0002] For systems with photovoltaics, energy storage and DC loads, the relevant solution is generally that the output voltage of the photovoltaic module passes through a direct current (Direct Current-Direct Current, DCDC) converter with maximum power point tracking (Maximum Power Point Tracking, MPPT) function to convert the photovoltaic voltage into a DC bus voltage. The DC bus voltage can power the DC load or the energy storage system. When the DC bus charges the energy storage system, the DC bus voltage passes through the second DCDC converter and is converted to the battery voltage to charge the battery. When the energy storage system supplies power to the DC load, the energy storage system passes through the second DCDC converter and is converted to the DC bus voltage to charge the DC load. The relevant solution has undergone two DCDC conversions, which increases the conversion power loss, reduces the energy storage efficiency, and increases the equipment cost.

[0003] The above contents are only used to assist in understanding the technical solutions of the present invention, and do not constitute an admission that the above contents are related solutions. Summary of the invention

[0004] The purpose of the present invention is to provide a hybrid power supply system, a photovoltaic air conditioner and a control method of the hybrid power supply system thereof, so as to solve the problem that in the system with photovoltaic, energy storage and DC load, two DCDC conversions are required in the related schemes, which increases the conversion power loss and equipment cost and reduces the energy storage efficiency. By adopting a set of DCDC circuits, the photovoltaic voltage is stepped up and down to charge the energy storage battery or supply power to the DC load, and the energy storage battery is stepped up and down to supply power to the DC load, thereby reducing the conversion power loss and equipment cost and improving the energy storage efficiency.

[0005] The present invention provides a hybrid power supply system, wherein the external power sources of the hybrid power supply system are photovoltaic components and energy storage batteries, and the external loads of the hybrid power supply system are DC loads; the hybrid power supply system comprises: a buck-boost unit, a switch unit, an acquisition unit and a control unit; the buck-boost unit comprises: a BUCK circuit and a BOOST circuit that share an energy storage inductor; the switch unit comprises: a first switch, a second switch, a third switch and a selection switch; the first switch is arranged between the output end of the photovoltaic component and the input end of the buck-boost unit; the second switch is arranged between the output end of the buck-boost unit and the DC load; the third switch is arranged between the output end of the energy storage battery and the second switch; the selection switch is used to control the on-off between the output end of the energy storage battery and the input end of the buck-boost unit or the third switch; wherein the acquisition The unit is used to obtain the photovoltaic voltage of the photovoltaic component, obtain the energy storage voltage of the energy storage battery, obtain the state of whether the energy storage battery needs to be charged, obtain the state of whether the DC load needs to be powered, and obtain the load voltage required by the DC load when the DC load needs to be powered; the control unit is used to control the opening and closing of the first switch, the second switch and the third switch, the selection mode of the selection switch, and at least one of the buck-boost mode of the buck-boost unit in combination with the photovoltaic voltage of the photovoltaic component, the energy storage voltage of the energy storage battery, the state of whether the energy storage battery needs to be charged, the state of whether the DC load needs to be powered, and the load voltage required by the DC load, so as to realize at least one of the control of the photovoltaic component charging the energy storage battery or supplying power to the DC load and the control of the energy storage battery supplying power to the DC load.

[0006] In some embodiments, the buck-boost unit specifically includes: a first capacitor, a second capacitor, a first switch tube, a second switch tube, a first diode, a second diode, and the energy storage inductor; the selection switch has a first connection end, a second connection end, and a third connection end; wherein, the positive terminal of the photovoltaic component is respectively connected to the first connection end of the first capacitor, the second connection end of the selection switch, and the input end of the first switch tube after passing through the first switch; the output end of the first switch tube is respectively connected to the cathode of the first diode and the first connection end of the energy storage inductor; the second connection end of the energy storage inductor is respectively connected to the input end of the second switch tube and the anode of the second diode; The cathode of the second diode is connected to the first connection end of the second capacitor, and the cathode of the second diode is also connected to the positive terminal of the DC load through the second switch; the positive terminal of the energy storage battery is connected to the first connection end of the selection switch; the third connection end of the selection switch is connected to the positive terminal of the DC load through the third switch and the second switch; the negative terminal of the photovoltaic module, the negative terminal of the energy storage battery, the second connection end of the first capacitor, the anode of the first diode, the output end of the second switch tube, the second connection end of the second capacitor, and the negative terminal of the DC load are all connected to the P-terminal of the buck-boost unit.

[0007] Matching the above-mentioned device, the present invention further provides a photovoltaic air conditioner on the other hand, including: the hybrid power supply system described above.

[0008] Matching the above hybrid power supply system, the present invention provides a control method for a hybrid power supply system on another aspect, comprising: obtaining the photovoltaic voltage of the photovoltaic component, obtaining the energy storage voltage of the energy storage battery, obtaining the state of whether the DC load needs power supply, and obtaining the load voltage required by the DC load when the DC load needs power supply; combining the photovoltaic voltage of the photovoltaic component, the energy storage voltage of the energy storage battery, the state of whether the energy storage battery needs to be charged, the state of whether the DC load needs power supply, and the load voltage required by the DC load, controlling the opening and closing of the first switch, the second switch, and the third switch, the selection mode of the selection switch, and at least one of the buck-boost mode of the buck-boost unit, so as to realize at least one of the control of the photovoltaic component charging the energy storage battery or supplying power to the DC load and the control of the energy storage battery supplying power to the DC load.

[0009] In some embodiments, in combination with the photovoltaic voltage of the photovoltaic component, the energy storage voltage of the energy storage battery, the state of whether the energy storage battery needs to be charged, the state of whether the DC load needs to be powered, and the load voltage required by the DC load, the opening and closing of the first switch, the second switch, and the third switch, the selection method of the selection switch, and the buck-boost method of the buck-boost unit are controlled to achieve at least one of the control of the photovoltaic component charging the energy storage battery or supplying power to the DC load and the control of the energy storage battery supplying power to the DC load, including: determining whether the photovoltaic voltage of the photovoltaic component is greater than or equal to a preset voltage threshold; if it is determined that the photovoltaic voltage of the photovoltaic component is less than the preset voltage threshold, controlling the first switch, the second switch, and the third switch The switch is turned on and off, and the selection mode of the selection switch is controlled so that the buck-boost unit enters the working mode in which the energy storage battery supplies power to the DC load; if it is determined that the photovoltaic voltage of the photovoltaic component is greater than or equal to the preset voltage threshold, the third switch is controlled to be disconnected, and the first connection end of the selection switch is controlled to be disconnected from the second connection end and the third connection end, or the first connection end of the selection switch is controlled to be disconnected from the second connection end and connected to the third connection end; the first switch is controlled to be closed so that the photovoltaic component supplies power to the main circuit of the buck-boost unit; wherein the first connection end of the selection switch is connected to the output end of the energy storage battery, the second connection end of the selection switch is connected to the input end of the buck-boost unit, and the third connection end of the selection switch is connected to the second switch after the third switch.

[0010] In some embodiments, controlling the opening and closing of the first switch, the second switch, and the third switch, and the selection mode of the selection switch, so that the buck-boost unit enters a working mode in which the energy storage battery supplies power to the DC load, includes: controlling the first switch to be disconnected, and controlling the first connection terminal and the second connection terminal of the selection switch to be connected, so that the energy storage battery supplies power to the main circuit of the buck-boost unit; determining whether the DC load needs to be powered according to the state of whether the DC load needs to be powered; if it is determined that the DC load needs to be powered, controlling the second switch to be closed; and determining whether the load voltage required by the DC load is greater than or equal to the energy storage voltage of the energy storage battery: if it is determined that the load voltage required by the DC load is greater than or equal to the energy storage voltage of the energy storage battery, controlling the buck-boost mode of the buck-boost unit to enable the buck-boost unit to operate at a boost voltage; if it is determined that the load voltage required by the DC load is less than the energy storage voltage of the energy storage battery, controlling the buck-boost mode of the buck-boost unit to enable the buck-boost unit to operate at a lower voltage.

[0011] In some embodiments, in combination with the photovoltaic voltage of the photovoltaic component, the energy storage voltage of the energy storage battery, the state of whether the energy storage battery needs to be charged, the state of whether the DC load needs to be powered, and the load voltage required by the DC load, the opening and closing of the first switch, the second switch, and the third switch, the selection method of the selection switch, and at least one of the buck-boost method of the buck-boost unit are controlled to achieve at least one of the control of the photovoltaic component charging the energy storage battery or supplying power to the DC load and the control of the energy storage battery supplying power to the DC load, and also includes: when the photovoltaic component supplies power to the main circuit of the buck-boost unit, determining whether the DC load needs to be powered according to the state of whether the DC load needs to be powered; if it is determined that the DC load does not need to be powered, controlling the second switch to be disconnected; and controlling the energy storage battery to supply power according to the energy storage battery. The state of whether the energy storage battery needs to be charged is determined: if it is determined that the energy storage battery needs to be charged, the opening and closing of the first switch, the second switch and the third switch, and the selection mode of the selection switch are controlled to make the buck-boost unit enter the working mode of the photovoltaic component charging the energy storage battery; if it is determined that the DC load needs to be powered, the second switch is controlled to be closed; and it is determined whether the load voltage required by the DC load is greater than or equal to the photovoltaic voltage of the photovoltaic component: if it is determined that the load voltage required by the DC load is greater than or equal to the photovoltaic voltage of the photovoltaic component, the buck-boost mode of the buck-boost unit is controlled to make the buck-boost unit run at a boost voltage; if it is determined that the load voltage required by the DC load is less than the photovoltaic voltage of the photovoltaic component, the buck-boost mode of the buck-boost unit is controlled to make the buck-boost unit run at a lower voltage.

[0012] In some embodiments, controlling the opening and closing of the first switch, the second switch, and the third switch, and the selection mode of the selection switch so that the buck-boost unit enters the working mode in which the photovoltaic module charges the energy storage battery includes: controlling the second switch to be disconnected, controlling the third switch to be closed, and controlling the first connection end and the third connection end of the selection switch to be connected; wherein the first connection end of the selection switch is connected to the output end of the energy storage battery, the second connection end of the selection switch is connected to the input end of the buck-boost unit, and the third connection end of the selection switch is connected to the second switch after the third switch; determining whether the energy storage voltage of the energy storage battery is greater than or equal to the photovoltaic voltage of the photovoltaic module: if it is determined that the energy storage voltage of the energy storage battery is greater than or equal to the photovoltaic voltage of the photovoltaic module, controlling the buck-boost mode of the buck-boost unit so that the buck-boost unit operates at a boost voltage; if it is determined that the energy storage voltage of the energy storage battery is less than the photovoltaic voltage of the photovoltaic module, controlling the buck-boost mode of the buck-boost unit so that the buck-boost unit operates at a lower voltage.

[0013] In some embodiments, when the buck-boost unit includes a first switch tube and a second switch tube, controlling the buck-boost mode of the buck-boost unit so that the buck-boost unit operates in a boost mode includes: controlling the first switch tube to turn on so that the boost function of the buck-boost unit is turned on; and controlling at least one of the operating frequency and the duty cycle of the second switch tube so that the buck-boost unit operates in a boost mode and boosts the input voltage of the buck-boost unit to a required output voltage.

[0014] In some embodiments, when the buck-boost unit includes a first switch tube and a second switch tube, controlling the buck-boost mode of the buck-boost unit so that the buck-boost unit operates at a step-down voltage includes: controlling the first switch tube to be turned on so that the step-down function of the buck-boost unit is turned on; and controlling at least one of the operating frequency and the duty cycle of the first switch tube so that the buck-boost unit operates at a step-down voltage and steps down the input voltage of the buck-boost unit to a required output voltage.

[0015] Therefore, the scheme of the present invention is to provide a set of DCDC circuits (i.e., DCDC converters) between the common power supply end of the photovoltaic module and the energy storage battery and the DC load for a system in which the photovoltaic module and the energy storage battery jointly supply power to the DC load. The buck-boost unit (i.e., BUCK circuit and BOOST circuit) in the DCDC converter shares the energy storage inductor, and a first switch (e.g., switch K1) is provided between the input side of the photovoltaic voltage and the buck-boost unit, a second switch (e.g., switch K2) is provided between the buck-boost unit and the DC load, a third switch is provided between the energy storage battery and the second switch, and a selection switch is provided between the input side of the energy storage voltage and the buck-boost unit and the third switch. The switch (such as the bidirectional switch K4) controls the opening and closing of the first switch, the second switch, the third switch and the selection switch according to the photovoltaic voltage, the energy storage voltage and the power supply voltage required by the DC load during operation, controls the buck-boost operation of the buck-boost unit, and controls the DCDC converter to operate in different operation modes, thereby realizing the control of the photovoltaic voltage buck-boost to charge the energy storage battery or supply power to the DC load, and the energy storage battery buck-boost to supply power to the DC load; thus, by adopting a set of DCDC circuits, the photovoltaic voltage buck-boost to charge the energy storage battery or supply power to the DC load, and the energy storage battery buck-boost to supply power to the DC load is realized, thereby reducing the conversion power loss and equipment cost, and improving the energy storage efficiency.

[0016] Other features and advantages of the present invention will be set forth in the description which follows, and in part will be apparent from the description, or may be learned by practice of the present invention.

[0017] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a structural schematic diagram of an embodiment of a hybrid power supply system of the present invention;

[0019] Figure 2 It is a circuit topology schematic diagram of the photovoltaic energy storage DCDC converter of the present invention;

[0020] Figure 3 It is a flow chart of an embodiment of a control method of a hybrid power supply system of the present invention;

[0021] Figure 4 It is a flow chart of an embodiment of controlling the buck-boost unit to work according to the photovoltaic voltage of the photovoltaic module in the method of the present invention;

[0022] Figure 5 A flow chart of an embodiment of the method of the present invention that enables the buck-boost unit to enter a working mode in which the energy storage battery supplies power to the DC load;

[0023] Figure 6 It is a flow chart of an embodiment of controlling the buck-boost unit to work according to the load voltage required by the DC load in the method of the present invention;

[0024] Figure 7 A schematic flow chart of an embodiment of the method of the present invention that enables the buck-boost unit to enter a working mode in which the photovoltaic assembly charges the energy storage battery;

[0025] Figure 8 It is a flow chart of an embodiment of the method of the present invention for making the buck-boost unit perform boost operation;

[0026] Fig. 9 It is a flow chart of an embodiment of making the buck-boost unit operate at a lower pressure in the method of the present invention;

[0027] Fig.10 It is a schematic diagram of the working process of the photovoltaic energy storage DCDC converter of the present invention;

[0028] Fig.11 It is a schematic diagram of the working process of the DCDC converter of the present invention when it works in the working mode of the energy storage battery supplying power to the DC load;

[0029] Fig.12 It is a schematic diagram of the working process of the DCDC converter of the present invention when the photovoltaic module is working in the working mode of charging the energy storage battery;

[0030] Fig.13 It is a schematic diagram of the working process of the DCDC converter boost operation of the present invention;

[0031] Fig.14It is a schematic diagram of the working process of the DCDC converter step-down operation of the present invention. DETAILED DESCRIPTION

[0032] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in conjunction with the specific embodiments of the present invention and the corresponding drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0033] Considering that for systems with photovoltaics, energy storage and DC loads, the relevant solutions need to go through two DCDC conversions, which increases conversion power loss and equipment cost, and reduces energy storage efficiency. For example: in some solutions, the solar cell array passes through a DCDC converter to stabilize the photovoltaic voltage at the DC bus voltage (for example, 400VDC bus voltage), and then the bus voltage passes through a DCDC converter to convert the DC bus voltage into the energy storage battery voltage for charging the energy storage battery. This solution has undergone two DCDC conversions, which increases conversion power loss, reduces energy storage efficiency, and increases equipment cost.

[0034] In other solutions, the photovoltaic input passes through the Maximum Power Point Tracking (MPPT) controller to stabilize the photovoltaic voltage at the DC bus voltage, and then the energy storage DCDC board steps down the DC bus voltage to the battery voltage to charge the battery. However, this DCDC solution has both MPPT and a bidirectional BUCK-BOOST (i.e. buck-boost) circuit in the DCDC energy storage board, which has many circuit components and high cost. When only photovoltaic power is needed to power the load and the battery is neither charged nor powered, the energy storage DCDC board circuit is idle. When only energy storage is used to power the load and there is no photovoltaic power, the MPPT circuit is idle, resulting in equipment waste.

[0035] In other schemes, the duty cycle is adjusted by the MPPT control module to control the PWM controller, drive and adjust the BOOST circuit, track the maximum output power point of photovoltaic energy storage power generation, improve the efficiency of photovoltaic energy storage power generation, and ensure the stability of energy storage power generation; at the same time, the MPPT control module can also collect electrical signals from the input power on the DC load side, determine the power consumption value of the DC load, and adjust the buck circuit by reducing the voltage. In this invention, the BUCK circuit and the Boost circuit are separate, and only the BUCK circuit or the BOOST circuit can work alone, resulting in circuit vacancy and waste, and this scheme has no energy storage function.

[0036] In addition, the bidirectional BUCK-BOOST DCDC circuit in the related solutions can only boost or reduce voltage in one direction, such as reducing voltage from the high voltage side to the low voltage side, or boosting voltage from the low voltage side to the high voltage side. In actual applications, there are such situations: the photovoltaic power supply needs to boost the voltage when supplying power to the load, and the photovoltaic power supply needs to reduce the voltage when supplying power to the energy storage battery (using the solution of low-voltage battery energy storage). In this case, the related solutions cannot meet the requirements.

[0037] In order to solve the above problems, the solution of the present invention proposes a hybrid power supply system, specifically a photovoltaic energy storage DCDC converter with a hybrid BUCK circuit and BOOST circuit topology, which can both boost and buck, and share the circuit topology of energy storage inductance and part of the circuit; when there is no photovoltaic power supply, the DC photovoltaic power supply can be switched to the energy storage battery power supply, and the energy storage battery power supply supplies power to the DC load; a control method for automatically switching the charging state and the discharging state of the energy storage battery, the photovoltaic power only converts the voltage through the first-level DCDC converter to charge the energy storage battery, which reduces the DCDC conversion power loss, improves the energy storage efficiency, and reduces the equipment cost.

[0038] According to an embodiment of the present invention, a hybrid power supply system is provided. Figure 1 A schematic diagram of the structure of an embodiment of the device of the present invention is shown. The external power source of the hybrid power supply system is a photovoltaic module and an energy storage battery, and the external load of the hybrid power supply system is a DC load; the hybrid power supply system includes: a buck-boost unit, a switch unit, an acquisition unit and a control unit; the buck-boost unit includes: a BUCK circuit and a BOOST circuit that share an energy storage inductor; that is, the buck-boost unit includes: a BUCK circuit and a BOOST circuit, and the BUCK circuit and the BOOST circuit share an energy storage inductor; the switch unit includes: a first switch, a second switch, a third switch and a selection switch; the first switch is arranged between the output end of the photovoltaic module and the input end of the buck-boost unit; the second The switch is arranged between the output end of the buck-boost unit and the DC load; the third switch is arranged between the output end of the energy storage battery and the second switch; the selection switch is used to control the on-off between the output end of the energy storage battery and the input end of the buck-boost unit or the third switch, specifically, the first connection end of the selection switch is connected to the output end of the energy storage battery, the second connection end of the selection switch is connected to the input end of the buck-boost unit, the third connection end of the selection switch is connected to the second switch after passing through the third switch, and the first connection end of the selection switch can be selectively connected to the second connection end of the selection switch and the third connection end of the selection switch.

[0039] Among them, the acquisition unit is used to obtain the photovoltaic voltage of the photovoltaic component (such as the photovoltaic voltage Vdc1), obtain the energy storage voltage of the energy storage battery (such as the battery voltage Vdc2 of the energy storage battery), obtain the state of whether the energy storage battery needs to be charged, obtain the state of whether the DC load needs to be powered, and obtain the load voltage required by the DC load (such as the power supply voltage Vload required by the DC load) when the DC load needs to be powered.

[0040] The control unit is used to control the opening and closing of the first switch, the second switch and the third switch, the selection mode of the selection switch, and at least one of the buck-boost mode of the buck-boost unit in combination with the photovoltaic voltage of the photovoltaic component, the energy storage voltage of the energy storage battery, the state of whether the energy storage battery needs to be charged, the state of whether the DC load needs to be powered, and the load voltage required by the DC load, so as to realize at least one of the control of the photovoltaic component charging the energy storage battery or supplying power to the DC load and the control of the energy storage battery supplying power to the DC load.

[0041] The solution of the present invention proposes a circuit topology of hybrid BUCK circuit and BOOST. In this circuit topology, the BUCK circuit and the BOOST circuit share an energy storage inductor, which reduces the circuit cost and the size of the equipment. This circuit topology can boost the DC voltage to supply power to a high-voltage DC load or charge a high-voltage energy storage battery, and can also step down the photovoltaic DC voltage to supply power to a low-voltage DC load or charge a low-voltage energy storage battery. The solution of the present invention also proposes a photovoltaic energy storage DCDC converter using this circuit topology and a control method thereof. The photovoltaic electric energy is only converted into voltage by a primary DCDC converter to charge the energy storage battery, which reduces the DCDC conversion power loss, improves the energy storage efficiency, and reduces the equipment cost. In the solution of the present invention, the photovoltaic energy storage DCDC converter can switch the DC photovoltaic power supply to the energy storage battery power supply when there is no photovoltaic power supply, and the DC load is powered by the energy storage battery power supply. In the solution of the present invention, only one set of DCDC system and one set of DCDC circuit topology are needed to realize three functions: boosting or bucking the photovoltaic voltage to charge the energy storage battery, boosting or bucking the photovoltaic voltage to discharge the DC load, and boosting or bucking the energy storage battery to discharge the DC load. This broadens the user's choice of building a photovoltaic energy storage DC load system, which is conducive to promoting green and energy-saving photovoltaic energy storage DC load systems.

[0042] In some embodiments, the buck-boost unit specifically includes: a first capacitor, a second capacitor, a first switch tube, a second switch tube, a first diode, a second diode, and the energy storage inductor; the selection switch has a first connection end, a second connection end and a third connection end, a first capacitor such as capacitor C1, a second capacitor such as capacitor C2, a first switch tube such as switch tube G1, a second switch tube such as switch tube G2, a first diode such as diode D1, a second diode such as diode D2, and the energy storage inductor such as inductor L.

[0043] Wherein, the positive terminal of the photovoltaic module is connected to the first connection end of the first capacitor, the second connection end of the selection switch, and the input end of the first switch tube respectively after passing through the first switch; the output end of the first switch tube is connected to the cathode of the first diode and the first connection end of the energy storage inductor respectively; the second connection end of the energy storage inductor is connected to the input end of the second switch tube and the anode of the second diode respectively; the cathode of the second diode is connected to the first connection end of the second capacitor, and the cathode of the second diode is also connected to the positive terminal of the DC load after passing through the second switch. The positive terminal of the energy storage battery is connected to the first connection end of the selection switch; the third connection end of the selection switch is connected to the positive terminal of the DC load after passing through the third switch and the second switch. The negative terminal of the photovoltaic module, the negative terminal of the energy storage battery, the second connection end of the first capacitor, the anode of the first diode, the output end of the second switch tube, the second connection end of the second capacitor, and the negative terminal of the DC load are all connected to the P-terminal of the buck-boost unit. The first connection end of the selection switch is such as the a end of the bidirectional switch K4, the second connection end of the selection switch is such as the b end of the bidirectional switch K4, and the third connection end of the selection switch is such as the c end of the bidirectional switch K4.

[0044] The solution of the present invention is mainly applied to a photovoltaic module to supply power to a DC load and is a DCDC converter having energy storage function and energy storage battery discharge function. Figure 2 Schematic diagram of the circuit topology of the photovoltaic energy storage DCDC converter of the present invention. Figure 2 In the circuit topology of the photovoltaic energy storage DCDC converter shown in FIG, the solar photovoltaic components, energy storage batteries, and DC loads are external devices. Figure 2As shown, the photovoltaic energy storage DCDC converter includes: switch K1, capacitor C1, switch tube G1, diode D1, inductor L, switch tube G2, diode D2, capacitor C2, switch K2, switch K3, bidirectional switch K4, voltage detection circuit Vdc1, voltage detection circuit Vdc2, voltage detection circuit Vdc3, current detection circuit I1, current detection circuit I2, current detection circuit I3, main control circuit of DCDC converter, DCDC internal power supply circuit, and DCDC communication circuit.

[0045] In such Figure 2 In the example shown, the two terminals PV+ and PV- of the output voltage of the solar photovoltaic module are connected to the DCDC converter. PV+ is connected to one terminal of the switch K1 of the DCDC converter; there is a voltage detection circuit Vdc1 on the line connecting PV+ to the terminal of the switch K1, and the input voltage Vdc1 of the photovoltaic module is detected. PV- is connected to the P-terminal of the DCDC converter; there is a current detection circuit I1 on the line connecting PV- to the P-terminal of the DCDC converter, and the output voltage I1 of the photovoltaic module is detected.

[0046] The output voltage of the photovoltaic module has a positive pole and a negative pole. The photovoltaic current flows out from the positive pole and returns to the negative pole after passing through the load. The output voltage of the battery also has a positive pole and a negative pole. The P- terminal of the DCDC converter connects the negative pole of the photovoltaic module output and the negative pole of the battery together. The current of the input voltage entering the DCDC converter flows into the Vin of the DCDC converter, flows out from the P- of the DCDC converter after passing through the load, and returns to the photovoltaic module or battery.

[0047] In such Figure 2 In the example shown, the voltage terminals of the energy storage battery are BAT+ and BAT-. Among them, BAT- is connected to the P-terminal of the DCDC converter; there is a current detection circuit I2 on the line connecting BAT- to the P-terminal, which detects the charging current I2 or the discharging current I2 of the energy storage battery. BAT+ of the energy storage battery is connected to the terminal a of the bidirectional switch K4 of the DCDC converter; there is a voltage detection circuit Vdc2 on the line connecting BAT+ to the terminal a of the bidirectional switch K4, which detects the voltage Vdc2 of the energy storage battery.

[0048] In such Figure 2In the example shown, one terminal of switch K1 is connected to PV+ of the photovoltaic module, and the other terminal is connected to one end of capacitor C1, and is also connected to the input end of switch tube G1 (such as the collector of switch tube G1). The other end of capacitor C1 is connected to P-. The output end of switch tube G1 (such as the emitter of switch tube G1) is connected to the cathode of diode D1, and is also connected to one end of inductor L. The anode of diode D1 is connected to P-. The other end of inductor L is connected to the input end of switch tube G2 (such as the collector of switch tube G2), and is also connected to the anode of diode D2. The cathode of diode D2 is connected to one end of capacitor C2, and is also connected to one end of switch K2, and is also connected to one end of switch K3. The other end of capacitor C2 is connected to P-. The other end of switch K3 is connected to the c terminal of bidirectional switch K4. There is a voltage detection circuit Vdc3 on the line from the cathode of diode D2 to switch K2, which detects the output voltage Vdc3 of diode D2. The other end of switch K2 is connected to the + end of the DC load. The - end of the DC load is connected to P-. There is a current detection circuit I3 on ​​the line from the - end of the DC load to P- to detect the current I3 flowing into the DC load. The bidirectional switch K4 has three terminals, namely a, b, and c. The a terminal is connected to the BAT+ terminal of the energy storage battery, the b terminal is connected to the input terminal of the switch tube G1, and the c terminal is connected to one end of the switch K3.

[0049] The main control circuit of the DCDC converter can control the conduction of a and b of the bidirectional switch K4, or the conduction of a and c. The main control circuit of the DCDC converter can control the closing, conducting or disconnecting of switches K1, K2 and K3, can control the closing path of the bidirectional switch K4, and select whether the ab terminal is closed or the ac terminal is closed. It can control whether the switch tubes G1 and G2 are working or the frequency and duty cycle when working. The DCDC communication circuit also communicates with the energy storage battery and receives information about the energy storage battery, such as whether the energy storage battery can be charged or whether the energy storage battery can be discharged; and receives information about the voltage of the energy storage battery. The DCDC internal power supply circuit provides power to the main control circuit, voltage detection circuit and current detection circuit of the DCDC converter.

[0050] The DCDC circuit topology in the solution of the present invention only requires one inductor and two switch tubes G1-G2, and can be used for both low-voltage batteries and high-voltage batteries, and can automatically determine; it can be used in scenarios where the bus voltage is higher than the photovoltaic voltage, and it can also be used in scenarios where the bus voltage is lower than the photovoltaic voltage; it can use both photovoltaics and energy storage batteries to power DC loads; it only involves circuit topologies and control working methods for photovoltaics to charge batteries, photovoltaics to power DC loads, and batteries to power DC loads; it can both boost and buck, such as boosting the photovoltaic voltage and bucking the photovoltaic voltage.

[0051] According to the technical solution of the present invention, a set of DCDC circuits (i.e., DCDC converters) is provided between the common power supply end of the photovoltaic module and the energy storage battery and the DC load for a system in which the photovoltaic module and the energy storage battery jointly supply power to the DC load. The buck-boost unit (i.e., BUCK circuit and BOOST circuit) in the DCDC converter shares the energy storage inductor, and a first switch (e.g., switch K1) is provided between the input side of the photovoltaic voltage and the buck-boost unit, a second switch (e.g., switch K2) is provided between the buck-boost unit and the DC load, a third switch is provided between the energy storage battery and the second switch, and a selection switch is provided between the input side of the energy storage voltage and the buck-boost unit and the third switch. The switch (such as the bidirectional switch K4) controls the opening and closing of the first switch, the second switch, the third switch and the selection switch according to the photovoltaic voltage, the energy storage voltage and the power supply voltage required by the DC load during operation, controls the buck-boost operation of the buck-boost unit, and controls the DCDC converter to operate in different operation modes, thereby realizing the control of the photovoltaic voltage buck-boost to charge the energy storage battery or supply power to the DC load, and the energy storage battery buck-boost to supply power to the DC load; thus, by adopting a set of DCDC circuits, the photovoltaic voltage buck-boost to charge the energy storage battery or supply power to the DC load, and the energy storage battery buck-boost to supply power to the DC load is realized, thereby reducing the conversion power loss and equipment cost, and improving the energy storage efficiency.

[0052] According to an embodiment of the present invention, a photovoltaic air conditioner corresponding to a hybrid power supply system is also provided. The photovoltaic air conditioner may include: the hybrid power supply system described above.

[0053] Since the processing and functions implemented by the photovoltaic air conditioner of this embodiment basically correspond to the embodiments, principles and examples of the device, for the details not described in this embodiment, please refer to the relevant descriptions in the aforementioned embodiments and will not be repeated here.

[0054] According to an embodiment of the present invention, a control method for a hybrid power supply system corresponding to the hybrid power supply system is also provided. Figure 3 The flowchart of an embodiment of the method of the present invention is shown in FIG. The control method of the hybrid power supply system may include: step S110 to step S120.

[0055] At step S110, the photovoltaic voltage of the photovoltaic component (such as the photovoltaic voltage Vdc1) is obtained, the energy storage voltage of the energy storage battery (such as the battery voltage Vdc2 of the energy storage battery) is obtained, the state of whether the DC load needs power supply is obtained, and when the DC load needs power supply, the load voltage required by the DC load (such as the power supply voltage Vload required by the DC load) is obtained.

[0056] At step S120, in combination with the photovoltaic voltage of the photovoltaic component, the energy storage voltage of the energy storage battery, the state of whether the energy storage battery needs to be charged, the state of whether the DC load needs to be powered, and the load voltage required by the DC load, the opening and closing of the first switch, the second switch, and the third switch, the selection method of the selection switch, and at least one of the buck-boost method of the buck-boost unit are controlled to achieve at least one of the control of the photovoltaic component charging the energy storage battery or supplying power to the DC load, and the control of the energy storage battery supplying power to the DC load.

[0057] In the solution of the present invention, the BUCK circuit and the BOOST circuit share the energy storage inductor, which reduces the circuit cost and the size of the equipment. This circuit topology can both boost the DC voltage to supply power to the high-voltage DC load or charge the high-voltage energy storage battery, and can also step down the photovoltaic DC voltage to supply power to the low-voltage DC load or charge the low-voltage energy storage battery. The solution of the present invention also proposes a photovoltaic energy storage DCDC converter using this circuit topology and a control method thereof. The photovoltaic electric energy is only converted into voltage by a primary DCDC converter to charge the energy storage battery, which reduces the DCDC conversion power loss, improves the energy storage efficiency, and reduces the equipment cost. In the solution of the present invention, the photovoltaic energy storage DCDC converter can switch the DC photovoltaic power supply to the energy storage battery power supply when there is no photovoltaic power supply, and the DC load is powered by the energy storage battery power supply. In the solution of the present invention, only one set of DCDC system and one set of DCDC circuit topology are needed to realize three functions: boosting or bucking the photovoltaic voltage to charge the energy storage battery, boosting or bucking the photovoltaic voltage to discharge the DC load, and boosting or bucking the energy storage battery to discharge the DC load. This broadens the user's choice of building a photovoltaic energy storage DC load system, which is conducive to promoting green and energy-saving photovoltaic energy storage DC load systems.

[0058] In some embodiments, in step S120, the photovoltaic voltage of the photovoltaic component, the energy storage voltage of the energy storage battery, the state of whether the energy storage battery needs to be charged, the state of whether the DC load needs to be powered, and the load voltage required by the DC load are combined to control the opening and closing of the first switch, the second switch, and the third switch, the selection method of the selection switch, and at least one of the buck-boost method of the buck-boost unit to achieve at least one of the control of the photovoltaic component charging the energy storage battery or supplying power to the DC load and the control of the energy storage battery supplying power to the DC load, including: a process of controlling the buck-boost unit to work according to the photovoltaic voltage of the photovoltaic component.

[0059] Combine the following Figure 4The method of the present invention is a flow chart of an embodiment of controlling the buck-boost unit according to the photovoltaic voltage of the photovoltaic component, further illustrating the specific process of controlling the buck-boost unit according to the photovoltaic voltage of the photovoltaic component in step S120, including: steps S210 to S230.

[0060] Step S210, determining whether the photovoltaic voltage of the photovoltaic module is greater than or equal to a preset voltage threshold, wherein the preset voltage threshold is, for example, a set value Vpvset.

[0061] Step S220: If it is determined that the photovoltaic voltage of the photovoltaic component is less than a preset voltage threshold, the opening and closing of the first switch, the second switch and the third switch, and the selection mode of the selection switch are controlled to enable the buck-boost unit to enter a working mode in which the energy storage battery supplies power to the DC load.

[0062] Step S230, if it is determined that the photovoltaic voltage of the photovoltaic component is greater than or equal to the preset voltage threshold, the third switch is controlled to be disconnected, the first connection end of the selection switch is controlled to be disconnected from the second connection end and the third connection end, or the first connection end of the selection switch is controlled to be disconnected from the second connection end and connected to the third connection end; the first switch is controlled to be closed so that the photovoltaic component supplies power to the main circuit of the buck-boost unit; wherein the first connection end of the selection switch is connected to the output end of the energy storage battery, the second connection end of the selection switch is connected to the input end of the buck-boost unit, and the third connection end of the selection switch is connected to the second switch after the third switch.

[0063] Fig.10 Schematic diagram of the working process of the photovoltaic energy storage DCDC converter of the present invention. Fig.10 As shown in the figure, the working process of the photovoltaic energy storage DCDC converter includes:

[0064] Step 11, detect the photovoltaic voltage Vdc1, and determine whether the photovoltaic voltage Vdc1 is greater than or equal to a certain set value Vpvset: if the photovoltaic voltage Vdc1 is less than a certain set value Vpvset, execute step 12; if the photovoltaic voltage Vdc1 is greater than or equal to a certain set value Vpvset, execute step 13.

[0065] Step 12: If the photovoltaic voltage Vdc1 is less than a certain set value Vpvset, it means that the photovoltaic module is insufficient in power and cannot supply power. The energy storage battery is needed to supply power, and the energy storage battery enters the working mode of supplying power to the DC load. For details, please refer to Fig.11 Example shown.

[0066] Step 13: If the photovoltaic voltage Vdc1 is greater than or equal to a certain set value Vpvset, it means that the photovoltaic module can supply power, and then execute steps 131, 132 and 133, and then execute step 14 or step 15. In the scheme of the present invention, the photovoltaic voltage Vdc1 is first detected, and the level of the photovoltaic voltage Vdc1 is used to determine whether the power of the photovoltaic module is sufficient: when the power of the photovoltaic module is insufficient, the energy storage battery power supply working mode is entered, that is, the photovoltaic module enters the power supply mode. Fig.11 The sub-process of the example shown; when the power of the photovoltaic components is sufficient, the photovoltaic power supply working mode is entered.

[0067] Step 131, control the switch K3 to be disconnected, the bidirectional switch K4 to be disconnected or the end a is closed to the end c, so that the energy storage battery is disconnected from the DCDC main circuit, that is, the energy storage battery is disconnected from the main circuit of the DCDC converter.

[0068] Step 132, control the switch K1 to close, and the photovoltaic module supplies power to the DCDC main circuit, that is, the photovoltaic module is connected to the main circuit of the DCDC converter.

[0069] In the scheme of the present invention, photovoltaic power is converted into voltage to charge the energy storage battery only through a primary DCDC converter as a buck-boost unit, which reduces the DCDC conversion power loss, improves the energy storage efficiency, and reduces the equipment cost; and the buck-boost unit is controlled to work according to the photovoltaic voltage of the photovoltaic module. When there is no photovoltaic power supply, the DC photovoltaic power supply can be switched to the energy storage battery power supply, and the energy storage battery power supply supplies power to the DC load, which broadens the user's choice of building a photovoltaic energy storage DC load system and has a wide range of applications.

[0070] In some embodiments, the specific process of controlling the opening and closing of the first switch, the second switch, and the third switch, and the selection method of the selection switch in step S220 so that the buck-boost unit enters the working mode in which the energy storage battery supplies power to the DC load is described in the following exemplary embodiments.

[0071] Combine the following Figure 5 The flowchart of an embodiment of the method of the present invention is shown as a flowchart of an embodiment of making the buck-boost unit enter the working mode of the energy storage battery supplying power to the DC load, further illustrating the specific process of making the buck-boost unit enter the working mode of the energy storage battery supplying power to the DC load in step S220, including: steps S310 to S330.

[0072] Step S310, controlling the first switch to be disconnected, and controlling the first connection terminal and the second connection terminal of the selection switch to be connected, so that the energy storage battery supplies power to the main circuit of the buck-boost unit.

[0073] Step S320, determining whether the DC load needs to be powered according to the state of whether the DC load needs power, wherein the state of whether the DC load needs power is the state of the DC load needing power or the state of the DC load not needing power.

[0074] Step S330, if it is determined that the DC load needs to be powered, the second switch is controlled to be closed; and it is determined whether the load voltage required by the DC load is greater than or equal to the energy storage voltage of the energy storage battery: if it is determined that the load voltage required by the DC load is greater than or equal to the energy storage voltage of the energy storage battery, the buck-boost mode of the buck-boost unit is controlled to make the buck-boost unit operate at a boost voltage; if it is determined that the load voltage required by the DC load is less than the energy storage voltage of the energy storage battery, the buck-boost mode of the buck-boost unit is controlled to make the buck-boost unit operate at a lower voltage. Of course, if it is determined that the DC load does not need to be powered, the buck-boost unit does not work.

[0075] Fig.11 The schematic diagram of the working process of the DCDC converter of the present invention when the energy storage battery is working in the working mode of supplying power to the DC load. Fig.11 As shown in FIG. 1 , the working process of the DCDC converter working in the working mode of the energy storage battery supplying power to the DC load includes:

[0076] Step 21, the DCDC converter enters the energy storage battery power supply mode, the main control circuit of the DCDC converter controls the switch K1 to be disconnected, controls the a and b ends of the bidirectional switch to be closed and turned on, and the energy storage battery supplies power to the DCDC main circuit.

[0077] Step 22, the DCDC communication circuit determines whether the DC load needs to be powered according to the communication information of the DC load: if the DC load does not need to be powered, the DCDC converter does not work; if the DC load needs to be powered, the control switch K2 is closed, and the DCDC communication circuit determines the power supply voltage Vload required by the DC load according to the communication information of the DC load, compares the power supply voltage Vload required by the DC load with the battery voltage Vdc2 of the energy storage battery, and executes steps 221 and 222.

[0078] Step 221: If the power supply voltage Vload required by the DC load is less than the battery voltage Vdc2 of the energy storage battery, the power supply voltage Vload required by the DC load is lower than the battery voltage Vdc2 of the energy storage battery, and the DCDC converter needs to step down. For details, please refer to Fig.14 The example shown, that is, executing Fig.14 The sub-process shown is used to control the components in the DCDC main circuit to reduce the input DC voltage value to the required output DC voltage value.

[0079] Step 222: If the power supply voltage Vload required by the DC load is greater than the battery voltage Vdc2 of the energy storage battery, the power supply voltage Vload required by the DC load is higher than the battery voltage Vdc2 of the energy storage battery, and the DCDC converter needs to be boosted. Fig.13 The example shown, that is, executing Fig.13 The sub-process shown is used to control the components in the DCDC main circuit to increase the input DC voltage value to the required output DC voltage value.

[0080] In the scheme of the present invention, photovoltaic power is converted into voltage to charge the energy storage battery only through a primary DCDC converter as a buck-boost unit, which reduces the DCDC conversion power loss, improves the energy storage efficiency, and reduces the equipment cost; and controls the opening and closing of the first switch, the second switch, and the third switch, as well as the selection mode of the selection switch, so that the buck-boost unit enters the working mode in which the energy storage battery supplies power to the DC load. When there is no photovoltaic power supply, the DC photovoltaic power supply can be switched to the energy storage battery power supply, and the energy storage battery power supply supplies power to the DC load, which broadens the user's choice of building a photovoltaic energy storage DC load system and has a wide range of applications.

[0081] In some embodiments, step S120 controls the opening and closing of the first switch, the second switch, and the third switch, the selection method of the selection switch, and at least one of the buck-boost method of the buck-boost unit in combination with the photovoltaic voltage of the photovoltaic component, the energy storage voltage of the energy storage battery, the state of whether the energy storage battery needs to be charged, the state of whether the DC load needs to be powered, and the load voltage required by the DC load, so as to realize at least one of the control of the photovoltaic component charging the energy storage battery or supplying power to the DC load and the control of the energy storage battery supplying power to the DC load, and also includes: a process of controlling the buck-boost unit to work according to the load voltage required by the DC load.

[0082] Combine the following Figure 6 The flowchart of an embodiment of controlling the buck-boost unit to operate according to the load voltage required by the DC load in the method of the present invention further illustrates the specific process of controlling the buck-boost unit to operate according to the load voltage required by the DC load in step S120, including: steps S410 to S430.

[0083] Step S410, when the photovoltaic assembly supplies power to the main circuit of the buck-boost unit, determining whether the DC load needs to be powered according to the state of whether the DC load needs to be powered, wherein the state of whether the DC load needs to be powered is the state of the DC load needing to be powered, or the state of the DC load not needing to be powered.

[0084] Step S420: If it is determined that the DC load does not need to be powered, the second switch is controlled to be disconnected; and according to the state of whether the energy storage battery needs to be charged, it is determined whether the energy storage battery needs to be charged: if it is determined that the energy storage battery needs to be charged, the first switch, the second switch and the third switch are controlled to be turned on and off, and the selection mode of the selection switch is controlled, so that the buck-boost unit enters the working mode of the photovoltaic component charging the energy storage battery. Of course, if it is determined that the energy storage battery does not need to be charged, the buck-boost unit is controlled not to work; wherein, the state of whether the energy storage battery needs to be charged is the state of the energy storage battery needing to be charged, or the state of the energy storage battery not needing to be charged.

[0085] Step S430, if it is determined that the DC load needs to be powered, the second switch is controlled to be closed; and it is determined whether the load voltage required by the DC load is greater than or equal to the photovoltaic voltage of the photovoltaic component: if it is determined that the load voltage required by the DC load is greater than or equal to the photovoltaic voltage of the photovoltaic component, the buck-boost mode of the buck-boost unit is controlled to enable the buck-boost unit to operate at a boost voltage; if it is determined that the load voltage required by the DC load is less than the photovoltaic voltage of the photovoltaic component, the buck-boost mode of the buck-boost unit is controlled to enable the buck-boost unit to operate at a lower voltage.

[0086] like Fig.10 As shown, the working process of the photovoltaic energy storage DCDC converter also includes: in step 13, it also includes: step 133, the DCDC communication circuit determines whether it is necessary to supply power to the DC load according to the communication information of the DC load: if so, execute step 15, otherwise execute step 14. The DCDC communication circuit communicates with the DC load and receives the communication information of the DC load, such as whether it is necessary to supply power to the DC load or stop supplying power.

[0087] Step 14: If the DC load does not need to be powered, the control switch K2 is turned off. The DCDC communication circuit determines whether the energy storage battery needs to be charged based on the communication information of the energy storage battery: If the energy storage battery needs to be charged, the photovoltaic module enters the working mode of charging the energy storage battery. For details, please refer to Fig.12 The example shown in the figure; if the energy storage battery does not need to be charged, the DCDC converter does not work. Determine whether it is necessary to supply power to the DC load: If it is not necessary to supply power to the DC load, then detect and determine whether it is necessary to charge the energy storage battery. If it is necessary to charge the energy storage battery, then enter the working mode of the photovoltaic module charging the energy storage battery, that is, enter Fig.12 The subprocess shown.

[0088] Step 15: If the DC load needs to be powered, execute step 151 and step 152. Determine whether the DC load needs to be powered: If the DC load needs to be powered, compare the photovoltaic voltage and the DC load voltage, and then determine whether the DCDC inverter is working in a boost state or a buck state, so as to boost or buck the photovoltaic voltage to power the DC load.

[0089] Step 151, control switch K2 to close, and the DCDC communication circuit determines the supply voltage Vload required by the DC load according to the communication information of the DC load. The DCDC communication circuit communicates with the DC load and receives the communication information of the DC load, such as receiving the information of how high a voltage is provided to the DC load.

[0090] Step 153, compare the power supply voltage Vload required by the DC load with the photovoltaic voltage Vdc1: if the power supply voltage Vload required by the DC load ≥ the photovoltaic voltage Vdc1, the power supply voltage Vload required by the DC load is higher than the photovoltaic voltage Vdc1, and the DCDC converter needs to be boosted. For details, please refer to Fig.13 The example shown, that is, executing Fig.13 The sub-process shown is used to control the components in the DCDC main circuit to increase the input DC voltage value to the required output DC voltage value; if the power supply voltage Vload required by the DC load is less than the photovoltaic voltage Vdc1, it means that the power supply voltage Vload required by the DC load is lower than the photovoltaic voltage Vdc1, and the DCDC converter needs to step down. For details, please refer to Fig.14 The example shown, that is, executing Fig.14 The sub-process shown is used to control the components in the DCDC main circuit to reduce the input DC voltage value to the required output DC voltage value.

[0091] In the scheme of the present invention, photovoltaic power is converted into voltage to charge the energy storage battery only through a primary DCDC converter as a buck-boost unit, which reduces the DCDC conversion power loss, improves the energy storage efficiency, and reduces the equipment cost; and the buck-boost unit is controlled to work according to the load voltage required by the DC load. When there is no photovoltaic power supply, the DC photovoltaic power supply can be switched to the energy storage battery power supply, and the energy storage battery power supply supplies power to the DC load, which broadens the user's choice of building a photovoltaic energy storage DC load system and has a wide range of applications.

[0092] In some embodiments, the specific process of controlling the opening and closing of the first switch, the second switch, and the third switch, and the selection method of the selection switch in step S420 so that the buck-boost unit enters the working mode in which the photovoltaic component charges the energy storage battery is described in the following exemplary embodiments.

[0093] Combine the following Figure 7The method of the present invention is shown as a flowchart of an embodiment of making the buck-boost unit enter the working mode of the photovoltaic component charging the energy storage battery, further illustrating the specific process of making the buck-boost unit enter the working mode of the photovoltaic component charging the energy storage battery in step S420, including: step S510 to step S520.

[0094] Step S510, controlling the second switch to be opened, controlling the third switch to be closed, and controlling the first connection end and the third connection end of the selection switch to be connected; wherein the first connection end of the selection switch is connected to the output end of the energy storage battery, the second connection end of the selection switch is connected to the input end of the buck-boost unit, and the third connection end of the selection switch is connected to the second switch after passing through the third switch.

[0095] Step S520, determining whether the energy storage voltage of the energy storage battery is greater than or equal to the photovoltaic voltage of the photovoltaic module: if it is determined that the energy storage voltage of the energy storage battery is greater than or equal to the photovoltaic voltage of the photovoltaic module, controlling the buck-boost mode of the buck-boost unit to enable the buck-boost unit to operate in a boost mode; if it is determined that the energy storage voltage of the energy storage battery is less than the photovoltaic voltage of the photovoltaic module, controlling the buck-boost mode of the buck-boost unit to enable the buck-boost unit to operate in a buck mode.

[0096] Fig.12 This is a schematic diagram of the working process of the DCDC converter of the present invention when the photovoltaic module is working in the working mode of charging the energy storage battery. Fig.12 As shown in FIG. 1 , the working process of the DCDC converter working in the photovoltaic power charging energy storage battery working mode includes:

[0097] Step 31, the DCDC converter enters the mode of charging the energy storage battery with the photovoltaic module: the control switch K2 is opened, the control switch K3 is closed and turned on, the a terminal and the c terminal of the bidirectional switch K4 are turned on, and then step 32 is executed.

[0098] Step 32 , the DCDC communication circuit determines the voltage Vbat of the energy storage battery according to the communication information of the energy storage battery, compares the voltage Vbat of the energy storage battery with the photovoltaic voltage Vdc1 , and executes steps 321 and 322 .

[0099] Step 321: If the voltage Vbat of the energy battery is less than the photovoltaic voltage Vdc1, the voltage Vbat of the energy battery is lower than the photovoltaic voltage Vdc1, and the DCDC converter needs to step down to charge the battery. Fig.14 The example shown, that is, executing Fig.14 The sub-process shown is used to control the components in the DCDC main circuit to reduce the input DC voltage value to the required output DC voltage value.

[0100] Step 322: If the voltage Vbat of the energy battery is greater than the photovoltaic voltage Vdc1, the voltage Vbat of the energy battery is higher than the photovoltaic voltage Vdc1, and the DCDC converter needs to step up to charge the battery. Fig.13 The example shown, that is, executing Fig.13 The sub-process shown is used to control the components in the DCDC main circuit to increase the input DC voltage value to the required output DC voltage value.

[0101] In the scheme of the present invention, photovoltaic power is converted into voltage to charge the energy storage battery only through a primary DCDC converter as a buck-boost unit, which reduces the DCDC conversion power loss, improves the energy storage efficiency, and reduces the equipment cost; and controls the opening and closing of the first switch, the second switch, and the third switch, as well as the selection mode of the selection switch, so that the buck-boost unit enters the working mode of the photovoltaic component charging the energy storage battery. When there is no photovoltaic power supply, the DC photovoltaic power supply can be switched to the energy storage battery power supply, and the energy storage battery power supply supplies power to the DC load, which broadens the user's choice of building a photovoltaic energy storage DC load system and has a wide range of applications.

[0102] In some embodiments, when the buck-boost unit includes a first switching tube and a second switching tube, the buck-boost mode of the buck-boost unit is controlled in steps S330, S430, and S520 to enable the buck-boost unit to perform a boost operation. For details, see the following exemplary description.

[0103] Combine the following Figure 8 The flowchart of an embodiment of the method of the present invention for making the buck-boost unit operate at a boost pressure is shown, further illustrating the specific process of making the buck-boost unit operate at a boost pressure in step S330, step S430, and step S520, including: step S610 to step S620.

[0104] Step S610, controlling the first switch tube to be turned on, so that the boost function of the buck-boost unit is turned on. In step S610, the first switch tube is controlled to be turned on; because the first switch tube is first controlled to be turned on so that the first switch tube is always turned on, and then the second switch tube is controlled to work in a high-frequency on and off state, so that the voltage can be boosted.

[0105] Step S620, controlling at least one of the operating frequency and the duty cycle of the second switch tube to enable the buck-boost unit to perform a boost operation, and boosting the input voltage of the buck-boost unit to a required output voltage.

[0106] Fig.13 FIG. 1 is a schematic diagram of the DCDC converter boost operation process of the present invention. Fig.13As shown, the DCDC converter operates in the boost (voltage increase) working state process, including:

[0107] Step 41, when the input voltage Vin of the DCDC converter is lower than the voltage Vout that the DCDC converter needs to output, the DCDC converter needs to boost operation: the main control circuit of the DCDC converter controls the switch tube G1 to close and turn on, and controls the switch tube G2 to work;

[0108] Among them, first of all, it is necessary to control the switch tube G1 to be always on, so that the electric energy can be transmitted to the switch tube G2 through the inductor L. At this time, the switch tube G2 is working, and the switch tube G2 is in a high-frequency on and off state; for example: in a 25us cycle, it is on for 15us and off for 10us. The ratio of the on time and the off time in a cycle is the duty cycle, and the duty cycle changes according to the control needs. In the Boost state, the switch tube G1 is always on, and the switch tube G2 works in a high-frequency on and off state.

[0109] The switch tube G2, the inductor L, and the diode D2 form a Boost circuit, which boosts the input voltage Vin to the required output voltage Vout to power external DC devices. Among them, the input voltage Vin in this sub-process: when the photovoltaic module is powered, Vin is the photovoltaic input voltage Vdc1; when the energy storage battery is powered, Vin is the voltage Vdc2 of the energy storage battery. The voltage Vout that the DCDC converter needs to output in this sub-process: when the load of the DCDC converter is a DC load, Vout is the voltage Vload required by the DC load; when the load of the DCDC converter is an energy storage battery, Vout is the voltage Vbat of the energy storage battery.

[0110] Step 42: By controlling the operating frequency and duty cycle of the switch tube G2, the actual output voltage, current and output power of the DCDC converter are controlled, and the photovoltaic maximum output power point tracking is achieved.

[0111] Among them, in the Boost boost circuit, first the switch tube G2 is turned on, the current flows through the inductor L, the switch tube G2 increases rapidly, and the inductor L stores electrical energy. Then the switch tube G2 is turned off, so that the current passes through the inductor L and the diode D2 to supply the bus. At this time, the current decreases rapidly, and the inductor L releases electrical energy. At this time, the voltage Vout is equal to the voltage across the inductor L plus the input voltage Vin, achieving the effect of boosting. In the boost process, the larger the duty cycle or the higher the switching frequency, the larger the current passing through the inductor L, the greater the energy stored in the inductor L, and the higher the voltage raised. Monitor the voltage Vout (or Vdc3). When the voltage Vout is lower than a certain threshold, increase the duty cycle or switching frequency of the switch tube G2, increase the energy stored in the inductor L, and thus increase the voltage Vout. When the voltage Vout is higher than a certain threshold, reduce the duty cycle or switching frequency, reduce the energy stored in the inductor L, and thus reduce the voltage Vout.

[0112] In the scheme of the present invention, the boost circuit and the buck circuit share the energy storage inductor and part of the circuit, which reduces the circuit cost and the size of the equipment; it can both boost and buck, and can supply power to high-voltage DC loads or charge high-voltage energy storage batteries, and can also buck the photovoltaic DC voltage to supply power to low-voltage DC loads or charge low-voltage energy storage batteries, which broadens the scope of use. Photovoltaic power only passes through a primary DCDC converter to convert the voltage to charge the energy storage battery, which reduces the DCDC conversion power loss, improves the energy storage efficiency, and reduces the equipment cost; when there is no photovoltaic power supply, the DC photovoltaic power supply can be switched to the energy storage battery power supply, and the energy storage battery power supply supplies power to the DC load.

[0113] In some embodiments, when the buck-boost unit includes a first switching tube and a second switching tube, the specific process of controlling the buck-boost mode of the buck-boost unit in steps S330, S430, and S520 to enable the buck-boost unit to operate at a reduced voltage is described in the following exemplary description.

[0114] Combine the following Fig. 9 The flowchart of an embodiment of the method of the present invention for making the buck-boost unit operate at a boost pressure is shown, further illustrating the specific process of making the buck-boost unit operate at a lower pressure in step S330, step S430, and step S520, including: step S710 to step S720.

[0115] Step S710, controlling the first switch tube to be turned on, so that the buck function of the buck-boost unit is turned on.

[0116] Step S720, controlling at least one of the operating frequency and the duty cycle of the first switch tube to enable the buck-boost unit to operate in a buck-boost mode, and to buck the input voltage of the buck-boost unit to a required output voltage.

[0117] Fig.14 FIG. 1 is a schematic diagram of the step-down operation process of the DCDC converter of the present invention. Fig.14 As shown, the DCDC converter operates in the step-down (voltage reduction) working state process, including:

[0118] Step 51, when the input voltage Vin of the DCDC converter is higher than the voltage Vout that the DCDC converter needs to output, the DCDC converter needs to step down and operate: the main control circuit of the DCDC converter controls the switch tube G1 to work. The switch tube G1, the inductor L, and the diode D1 form a BUCK buck circuit, which steps down the input voltage Vin to the required output voltage Vout to power the external DC device. Among them, the input voltage Vin in this sub-process: when the photovoltaic component is powered, Vin is the photovoltaic input voltage Vdc1; when the energy storage battery is powered, Vin is the voltage Vdc2 of the energy storage battery. The voltage Vout that the DCDC converter needs to output in this sub-process: when the load of the DCDC converter is a DC load, Vout is the voltage Vload required by the DC load; when the load of the DCDC converter is an energy storage battery, Vout is the voltage Vbat of the energy storage battery.

[0119] Step 52: By controlling the operating frequency and duty cycle of the switch tube G1, the actual output voltage, current and output power of the DCDC converter are controlled, and the photovoltaic maximum output power point tracking is achieved.

[0120] The solution of the present invention is the most basic solution to the adaptability of DCDC used in photovoltaic, energy storage, and DC load systems under photovoltaic components with different voltages, energy storage batteries with different voltages, and DC loads with different voltages. For example: when a user builds a photovoltaic, energy storage, and DC load system, if the photovoltaic voltage is higher than the energy storage battery voltage, a step-down DCDC is needed to step down the photovoltaic voltage to charge the energy storage battery. If the photovoltaic voltage is lower than the DC load voltage, a step-up DCDC is needed to step up the photovoltaic voltage to power the DC load. If the energy storage battery voltage is lower than the DC load voltage, a step-up DCDC is needed to step up the energy storage battery voltage to power the DC load. In this way, three separate DCDC systems are required. In the solution of the present invention, only one DCDC system and one DCDC circuit topology are needed to realize the three functions of boosting or stepping down the photovoltaic voltage to charge the energy storage battery, boosting or stepping down the photovoltaic voltage to discharge the DC load, and boosting or stepping down the energy storage battery to discharge the DC load. The solution of the present invention broadens the selectivity of users in building photovoltaic energy storage DC load systems, which is conducive to promoting green and energy-saving photovoltaic energy storage DC load systems.

[0121] Since the processing and functions implemented by the method of this embodiment basically correspond to the embodiments, principles and examples of the aforementioned photovoltaic air conditioner, for the details not described in this embodiment, please refer to the relevant descriptions in the aforementioned embodiments and will not be repeated here.

[0122] In summary, it is easy for those skilled in the art to understand that, under the premise of no conflict, the above-mentioned advantageous methods can be freely combined and superimposed.

[0123] The above description is only an embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent substitution, improvement, etc. made within the spirit and principle of the present invention shall be included in the scope of the claims of the present invention.

Claims

1. A hybrid power supply system, characterized in that: The external power source of the hybrid power supply system is a photovoltaic module and an energy storage battery, and the external load of the hybrid power supply system is a DC load; The hybrid power supply system includes: a buck-boost unit, a switch unit, an acquisition unit and a control unit; the buck-boost unit includes: a BUCK circuit and a BOOST circuit that share an energy storage inductor; the switch unit includes: a first switch, a second switch, a third switch and a selection switch; the first switch is arranged between the output end of the photovoltaic component and the input end of the buck-boost unit; the second switch is arranged between the output end of the buck-boost unit and the DC load; the third switch is arranged between the output end of the energy storage battery and the second switch; the selection switch is used to control the on-off between the output end of the energy storage battery and the input end of the buck-boost unit or the third switch; wherein, The acquisition unit is used to acquire the photovoltaic voltage of the photovoltaic component, acquire the energy storage voltage of the energy storage battery, acquire the state of whether the energy storage battery needs to be charged, acquire the state of whether the DC load needs to be powered, and acquire the load voltage required by the DC load when the DC load needs to be powered; The control unit is used to control the opening and closing of the first switch, the second switch and the third switch, the selection mode of the selection switch, and at least one of the buck-boost mode of the buck-boost unit in combination with the photovoltaic voltage of the photovoltaic component, the energy storage voltage of the energy storage battery, the state of whether the energy storage battery needs to be charged, the state of whether the DC load needs to be powered, and the load voltage required by the DC load, so as to realize at least one of the control of the photovoltaic component charging the energy storage battery or supplying power to the DC load and the control of the energy storage battery supplying power to the DC load.

2. The hybrid power supply system according to claim 1, characterized in that: The buck-boost unit specifically includes: a first capacitor, a second capacitor, a first switch tube, a second switch tube, a first diode, a second diode, and the energy storage inductor; the selection switch has a first connection end, a second connection end and a third connection end; wherein, The positive terminal of the photovoltaic module is connected to the first connection end of the first capacitor, the second connection end of the selection switch, and the input end of the first switch tube respectively after passing through the first switch; the output end of the first switch tube is connected to the cathode of the first diode and the first connection end of the energy storage inductor respectively; the second connection end of the energy storage inductor is connected to the input end of the second switch tube and the anode of the second diode respectively; the cathode of the second diode is connected to the first connection end of the second capacitor, and the cathode of the second diode is also connected to the positive terminal of the DC load after passing through the second switch; The positive electrode terminal of the energy storage battery is connected to the first connection end of the selection switch; the third connection end of the selection switch is connected to the positive electrode terminal of the DC load through the third switch and the second switch; The negative terminal of the photovoltaic component, the negative terminal of the energy storage battery, the second connection end of the first capacitor, the anode of the first diode, the output end of the second switch tube, the second connection end of the second capacitor, and the negative terminal of the DC load are all connected to the P-terminal of the buck-boost unit.

3. A photovoltaic air conditioner, characterized in that: include: A hybrid power supply system according to any one of claims 1 to 2.

4. A control method for a hybrid power supply system according to any one of claims 1 to 2, characterized in that: include: Obtaining the photovoltaic voltage of the photovoltaic component, obtaining the energy storage voltage of the energy storage battery, obtaining the state of whether the DC load needs power supply, and obtaining the load voltage required by the DC load when the DC load needs power supply; In combination with the photovoltaic voltage of the photovoltaic component, the energy storage voltage of the energy storage battery, the state of whether the energy storage battery needs to be charged, the state of whether the DC load needs to be powered, and the load voltage required by the DC load, the opening and closing of the first switch, the second switch, and the third switch, the selection method of the selection switch, and at least one of the buck-boost method of the buck-boost unit are controlled to achieve at least one of the control of the photovoltaic component charging the energy storage battery or supplying power to the DC load, and the control of the energy storage battery supplying power to the DC load.

5. The control method of the hybrid power supply system according to claim 4, characterized in that: In combination with the photovoltaic voltage of the photovoltaic component, the energy storage voltage of the energy storage battery, the state of whether the energy storage battery needs to be charged, the state of whether the DC load needs to be powered, and the load voltage required by the DC load, at least one of the on / off of the first switch, the second switch, and the third switch, the selection mode of the selection switch, and the buck-boost mode of the buck-boost unit is controlled to achieve at least one of the control of the photovoltaic component charging the energy storage battery or powering the DC load, and the control of the energy storage battery powering the DC load, including: Determining whether the photovoltaic voltage of the photovoltaic assembly is greater than or equal to a preset voltage threshold; If it is determined that the photovoltaic voltage of the photovoltaic assembly is less than a preset voltage threshold, the first switch, the second switch and the third switch are turned on and off, and the selection mode of the selection switch is controlled, so that the buck-boost unit enters a working mode in which the energy storage battery supplies power to the DC load; If it is determined that the photovoltaic voltage of the photovoltaic component is greater than or equal to a preset voltage threshold, the third switch is controlled to be disconnected, the first connection end of the selection switch is controlled to be disconnected from the second connection end and the third connection end, or the first connection end of the selection switch is controlled to be disconnected from the second connection end and connected to the third connection end; the first switch is controlled to be closed so that the photovoltaic component supplies power to the main circuit of the buck-boost unit; wherein the first connection end of the selection switch is connected to the output end of the energy storage battery, the second connection end of the selection switch is connected to the input end of the buck-boost unit, and the third connection end of the selection switch is connected to the second switch after the third switch.

6. The control method of the hybrid power supply system according to claim 5, characterized in that: Controlling the on / off of the first switch, the second switch, and the third switch, and the selection mode of the selection switch, so that the buck-boost unit enters a working mode in which the energy storage battery supplies power to the DC load, includes: Control the first switch to be disconnected, and control the first connection end and the second connection end of the selection switch to be connected, so that the energy storage battery supplies power to the main circuit of the buck-boost unit; Determining whether power needs to be supplied to the DC load according to a state of whether the DC load needs power supply; If it is determined that the DC load needs to be powered, the second switch is controlled to be closed; and it is determined whether the load voltage required by the DC load is greater than or equal to the energy storage voltage of the energy storage battery: if it is determined that the load voltage required by the DC load is greater than or equal to the energy storage voltage of the energy storage battery, the buck-boost mode of the buck-boost unit is controlled to enable the buck-boost unit to operate at a boost voltage; if it is determined that the load voltage required by the DC load is less than the energy storage voltage of the energy storage battery, the buck-boost mode of the buck-boost unit is controlled to enable the buck-boost unit to operate at a lower voltage.

7. The control method of the hybrid power supply system according to any one of claims 4 to 6, characterized in that: In combination with the photovoltaic voltage of the photovoltaic component, the energy storage voltage of the energy storage battery, the state of whether the energy storage battery needs to be charged, the state of whether the DC load needs to be powered, and the load voltage required by the DC load, at least one of the on / off of the first switch, the second switch, and the third switch, the selection mode of the selection switch, and the buck-boost mode of the buck-boost unit is controlled to achieve at least one of the control of the photovoltaic component charging the energy storage battery or powering the DC load, and the control of the energy storage battery powering the DC load, and further comprising: When the photovoltaic assembly supplies power to the main circuit of the buck-boost unit, determining whether the DC load needs to be powered according to a state of whether the DC load needs power; If it is determined that the DC load does not need to be powered, the second switch is controlled to be disconnected; and according to the state of whether the energy storage battery needs to be charged, it is determined whether the energy storage battery needs to be charged: if it is determined that the energy storage battery needs to be charged, the first switch, the second switch and the third switch are controlled to be turned on and off, and the selection mode of the selection switch is controlled, so that the buck-boost unit enters the working mode of the photovoltaic assembly charging the energy storage battery; If it is determined that the DC load needs to be powered, the second switch is controlled to be closed; and it is determined whether the load voltage required by the DC load is greater than or equal to the photovoltaic voltage of the photovoltaic component: if it is determined that the load voltage required by the DC load is greater than or equal to the photovoltaic voltage of the photovoltaic component, the buck-boost mode of the buck-boost unit is controlled to enable the buck-boost unit to operate at a boost voltage; if it is determined that the load voltage required by the DC load is less than the photovoltaic voltage of the photovoltaic component, the buck-boost mode of the buck-boost unit is controlled to enable the buck-boost unit to operate at a lower voltage.

8. The control method of the hybrid power supply system according to claim 7, characterized in that: Controlling the opening and closing of the first switch, the second switch, and the third switch, and the selection mode of the selection switch, so that the buck-boost unit enters a working mode in which the photovoltaic assembly charges the energy storage battery, includes: Control the second switch to be disconnected, control the third switch to be closed, and control the first connection end and the third connection end of the selection switch to be connected; wherein the first connection end of the selection switch is connected to the output end of the energy storage battery, the second connection end of the selection switch is connected to the input end of the buck-boost unit, and the third connection end of the selection switch is connected to the second switch through the third switch; Determine whether the energy storage voltage of the energy storage battery is greater than or equal to the photovoltaic voltage of the photovoltaic module: if it is determined that the energy storage voltage of the energy storage battery is greater than or equal to the photovoltaic voltage of the photovoltaic module, control the buck-boost mode of the buck-boost unit to enable the buck-boost unit to operate at a boost voltage; if it is determined that the energy storage voltage of the energy storage battery is less than the photovoltaic voltage of the photovoltaic module, control the buck-boost mode of the buck-boost unit to enable the buck-boost unit to operate at a lower voltage.

9. The control method of the hybrid power supply system according to any one of claims 6 to 8, characterized in that: In the case where the buck-boost unit includes a first switch tube and a second switch tube, controlling the buck-boost mode of the buck-boost unit to enable the buck-boost unit to perform a boost operation includes: Controlling the first switch tube to be turned on so as to enable the boost function of the buck-boost unit; At least one of the operating frequency and the duty cycle of the second switch tube is controlled to enable the buck-boost unit to perform a boost operation, thereby boosting the input voltage of the buck-boost unit to a required output voltage.

10. The control method of the hybrid power supply system according to any one of claims 6 to 8, characterized in that: In the case where the buck-boost unit includes a first switch tube and a second switch tube, controlling the buck-boost mode of the buck-boost unit to make the buck-boost unit operate at a reduced voltage includes: Controlling the first switch tube to be turned on so that the buck function of the buck-boost unit is turned on; At least one of the operating frequency and the duty cycle of the first switch tube is controlled to enable the buck-boost unit to operate in a buck-boost mode, thereby stepping down the input voltage of the buck-boost unit to a required output voltage.

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