H5 bridge direct current three-port optical storage converter and control method thereof

Abstract

The invention discloses an H5 bridge direct-current three-port optical storage converter and a control method thereof.The H5 bridge direct-current three-port optical storage converter comprises a primary-side H5 bridge circuit, a primary-side resonant cavity, a transformer, a secondary-side resonant cavity and a secondary-side three-level half-bridge circuit, the primary-side H5 bridge circuit is used for achieving power input and regulation and control of a photovoltaic port and an energy storage port; the primary side resonant cavity, the transformer and the secondary side resonant cavity are used for power transmission matching, and the secondary side three-level half-bridge circuit is used for stabilizing the voltage of the DC power grid output port. According to the invention, energy transmission among the three ports can be realized, and the energy utilization rate and the reliability of the optical storage system are improved.

Description

Technical Field

[0001] This invention relates to the field of electronic circuit technology, and in particular to an H5 bridge DC three-port optical-storage converter and its control method. Background Technology

[0002] The output power of photovoltaic power generation is affected by factors such as light intensity and ambient temperature, and is intermittent and fluctuating. In addition, the load demand changes in real time, so it is necessary to connect energy storage devices to the photovoltaic power generation system to realize peak shaving and valley filling of photovoltaic power generation to ensure a stable power supply. A three-port converter can connect three ports: photovoltaic, energy storage and grid to realize this function.

[0003] Although existing three-port converters can achieve energy flow between three ports using only one converter, with the electrical energy flowing between ports undergoing only one-stage conversion, resulting in high efficiency and low cost, most existing three-port converters only support unidirectional or limited-direction power transmission. This leads to low energy utilization, high switching losses, and difficulties in multi-mode coordinated control, making them prone to voltage fluctuations or power distribution imbalances, which affect the reliability of photovoltaic energy storage systems. Summary of the Invention

[0004] The purpose of this invention is to provide an H5 bridge DC three-port photovoltaic-energy storage converter and its control method, which can realize energy flow between photovoltaic, energy storage and DC bus, and improve energy utilization and reliability of photovoltaic-energy storage system.

[0005] To achieve the above objectives, the present invention provides an H5 bridge DC three-port photovoltaic-storage converter, comprising a primary-side H5 bridge circuit, a primary-side resonant cavity, a transformer, a secondary-side resonant cavity, and a secondary-side three-level half-bridge circuit. The primary-side H5 bridge circuit is connected to the photovoltaic port and the energy storage port respectively. The primary-side H5 bridge circuit is connected to one end of the primary-side resonant cavity. The other end of the primary-side resonant cavity is connected to the primary side of the transformer. The secondary side of the transformer is connected to one end of the secondary-side resonant cavity. The other end of the secondary-side resonant cavity is connected to one end of the secondary-side three-level half-bridge circuit. The other end of the secondary-side three-level half-bridge circuit is connected to the DC grid output port. The primary-side H5 bridge circuit is used to realize the power input and regulation of the photovoltaic port and the energy storage port. The primary-side resonant cavity, the transformer and the secondary-side resonant cavity are used for power transmission matching. The secondary-side three-level half-bridge circuit is used to stabilize the voltage of the DC grid output port.

[0006] Optionally, the primary-side H5 bridge circuit includes three switching arms, a half-bridge, a power inductor, a first supporting capacitor, a second supporting capacitor, and a third supporting capacitor; The three-switch bridge arm includes a first switch transistor, a first switch transistor and a first switch transistor connected in series. The three-switch bridge arm is connected to the photovoltaic port. The first supporting capacitor and the second supporting capacitor are connected in parallel with the three-switch bridge arm. The half-bridge includes a fourth and a fifth switching transistor connected in series. The half-bridge is connected to the energy storage port. The third supporting capacitor is connected in parallel with the half-bridge. One end of the power inductor is connected between the fourth switch and the switch, and the other end of the power inductor is connected between the first switch and the second switch.

[0007] Optionally, the secondary-side three-level half-bridge circuit includes a sixth switch, a seventh switch, an eighth switch, a ninth switch, a second diode, and a third diode; The sixth switch is connected in series with the seventh switch, and the eighth switch is connected in series with the ninth switch. The anode of the second diode is connected to the source of the seventh switch, and the cathode of the second diode is connected to the connection point of the sixth switch and the seventh switch. The anode of the third diode is connected to the drain of the eighth switch, and the cathode of the third diode is connected to the connection point of the eighth switch and the ninth switch. The other end of the secondary-side three-level half-bridge circuit is connected to the first output capacitor and the second output capacitor, and is connected to the DC power grid output port through the first output capacitor and the second output capacitor.

[0008] Optionally, the H5 bridge DC three-port optical-storage converter is used for: When the DC grid output port is off-grid and not transmitting power, the output power of the photovoltaic port is transmitted to the energy storage port; When the photovoltaic port has no power output, the energy storage port performs forward power transfer to the DC grid output port, or the DC grid output port performs reverse power transfer to the energy storage port. When the output power of the photovoltaic port is equal to the required power of the DC grid output port, the power is transmitted from the photovoltaic port to the DC grid output port; When the output power of the photovoltaic port is less than the required power of the DC grid output port, the power is transmitted from both the photovoltaic port and the energy storage port to the DC grid output port. When the output power of the photovoltaic port is greater than the required power of the DC grid output port, the power is transmitted from the photovoltaic port to the DC grid output port and the energy storage port.

[0009] Optionally, the input voltage of the photovoltaic port and the output voltage of the energy storage port satisfy the following relationship: ; In the formula, This is the input voltage of the photovoltaic port; This refers to the output voltage of the energy storage port. The time during which the first and fifth switching transistors are both turned on; The time during which the first and fourth switching transistors are both turned on; This refers to the time during which the second, third, and fourth switches are all turned on.

[0010] Optionally, the conduction times of the first switch, the second switch, the third switch, the fourth switch, and the fifth switch satisfy the following relationship: ; In the formula, T4 is the second switching transistor. Q 2. Third switching transistor Q 3 and the fifth switching transistor Q 5. The duration of simultaneous conduction; L in This refers to the power inductance value; I x This is the minimum value of the power inductor current; I o y is the output current of the energy storage port; a The value of the power inductor current at the end of time T1; y b This represents the power inductor current value at the end of time T2; f s This is the switching frequency of the optical-storage converter.

[0011] Optionally, the power inductance value satisfies the following expression: ; ; In the formula, L in Here, represents the power inductance value; M is an intermediate variable used for simplified calculations. P out T represents the power transferred from the photovoltaic port to the energy storage port. s The switching cycle.

[0012] Optionally, the primary resonant frequency and the secondary resonant frequency of the optical-storage converter are equal.

[0013] Optionally, the primary resonant cavity includes a first resonant inductor and a first resonant capacitor; the secondary resonant cavity includes a second resonant inductor and a second resonant capacitor.

[0014] To achieve the above objectives, the present invention also provides a control method for an H5 bridge DC three-port photovoltaic-storage converter, applied to the H5 bridge DC three-port photovoltaic-storage converter as described in any of the preceding claims, comprising: The operating mode of the photovoltaic-energy storage converter is controlled based on the input voltage of the photovoltaic port, the output voltage of the energy storage port, and the voltage of the DC output port. According to the operating mode, the turn-on and turn-off times of each switch in the primary H5 bridge circuit and the secondary three-level half-bridge circuit are controlled.

[0015] Compared with existing technologies, the present invention provides an H5 bridge DC three-port photovoltaic-energy storage converter and its control method. This photovoltaic-energy storage converter can connect to three ports: photovoltaic, energy storage, and DC. Through multiple working modes, it covers scenarios such as photovoltaic energy storage, energy storage power supply, and photovoltaic and energy storage combined power supply, and can meet the energy distribution under different power requirements. In addition, the design of equal resonant frequencies on the primary and secondary sides, combined with the freewheeling current of the parasitic diode of the switching transistor to achieve soft switching, can reduce switching losses and improve transmission efficiency. It has an efficiency advantage at high frequencies and is easier to achieve high power density. Attached Figure Description

[0016] To more clearly illustrate the technical solution of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 This is a topology diagram of an H5 bridge DC three-port optical-storage converter provided in an embodiment of the present invention; Figure 2 This is a schematic diagram illustrating the classification of operating modes of an H5 bridge DC three-port optical-storage converter provided in an embodiment of the present invention; Figure 3 This is an equivalent topology diagram of an H5 bridge DC three-port optical-storage converter in reverse transmission, provided by an embodiment of the present invention. Figure 4 This is a waveform diagram of the driving signal and key nodes of the H5 bridge DC three-port optical-storage converter provided in an embodiment of the present invention; Figure 5 This is a schematic diagram of the working modes of the H5 bridge DC three-port photovoltaic-storage converter provided in an embodiment of the present invention; Figure 6 This is a schematic diagram of the steady-state operation of the H5 bridge DC three-port photovoltaic-storage converter provided in the embodiment of the present invention under working mode 1; Figure 7This is a schematic diagram illustrating another steady-state operation of the H5 bridge DC three-port photovoltaic-storage converter provided in this embodiment of the invention under operating mode 1. Figure 8 This is a schematic diagram of the steady-state operation of the H5 bridge DC three-port photovoltaic-storage converter provided in the embodiment of the present invention under working mode 2; Figure 9 This is a schematic diagram of another steady-state operation of the H5 bridge DC three-port photovoltaic-storage converter provided in the embodiment of the present invention under working mode 2; Figure 10 This is a schematic diagram of the steady-state operation of the H5 bridge DC three-port photovoltaic-storage converter provided in this embodiment of the invention under working mode 3; Figure 11 This is a schematic diagram of the steady-state operation of the H5 bridge DC three-port photovoltaic-storage converter provided in this embodiment of the invention under working mode 4; Figure 12 This is a schematic diagram of the steady-state operation of the H5 bridge DC three-port photovoltaic-storage converter provided in this embodiment of the invention under working mode 5; Figure 13 This is a schematic diagram of another steady-state operation of the H5 bridge DC three-port photovoltaic-storage converter provided in the embodiment of the present invention under working mode 5; Figure 14 This is a flowchart of a control method for an H5 bridge DC three-port photovoltaic-storage converter provided in an embodiment of the present invention. Detailed Implementation

[0018] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0019] See Figure 1 , Figure 1 This is a topology diagram of an H5 bridge DC three-port optical-storage converter provided in an embodiment of the present invention. Figure 1 As shown, the H5 bridge DC three-port optical-storage converter includes a primary-side H5 bridge circuit, a primary-side resonant cavity, a transformer T, a secondary-side resonant cavity, and a secondary-side three-level half-bridge circuit. The primary H5 bridge circuit is connected to the photovoltaic port. V PV and energy storage port V BaThe primary-side H5 bridge circuit is connected to one end of the primary-side resonant cavity, and the other end of the primary-side resonant cavity is connected to the primary side of the transformer T. The secondary side of the transformer T is connected to one end of the secondary-side resonant cavity, and the other end of the secondary-side resonant cavity is connected to one end of the secondary-side three-level half-bridge circuit. The other end of the secondary-side three-level half-bridge circuit is connected to the DC power grid output port. V DC ; The primary-side H5 bridge circuit is used to realize the power input and regulation of the photovoltaic port and the energy storage port. The primary-side resonant cavity, the transformer and the secondary-side resonant cavity are used for power transmission matching. The secondary-side three-level half-bridge circuit is used to stabilize the voltage of the DC grid output port.

[0020] like Figure 1 As shown, the primary-side H5 bridge circuit includes three switching arms, a half-bridge, and a power inductor. L in First supporting capacitor C 1. Second supporting capacitor C 2 and the third supporting capacitor C 3; The three-switch bridge arm includes a first switch transistor connected in series. Q 1. Second switching transistor Q 2 and the third switching transistor Q 3. The three-switch bridge arm is connected to the photovoltaic port. V PV The first supporting capacitor C 1 and second supporting capacitors C 2 is connected in parallel with the three-switch bridge arm; The half-bridge includes a fourth switching transistor connected in series. Q 4 and the fifth switching transistor Q 5. The half-bridge connects to the energy storage port. V Ba The third supporting capacitor C 3 is connected in parallel with the half-bridge; The power inductor L in One end is connected to the fourth switch transistor Q 4 and the aforementioned switching transistor Q Between 5, the power inductor L in The other end is connected to the first switching transistor. Q 1 and the second switching transistor Q Between 2.

[0021] like Figure 1 As shown, the primary resonant cavity includes a first resonant inductor. Lr1 and the first resonant capacitor C r1 The secondary resonant cavity includes a second resonant inductor. L r2 Second resonant capacitor C r2 .

[0022] The primary circuit is connected via a resonant inductor. L r1 Resonant capacitor C r1 The primary resonant cavity is formed and then connected to the primary side of transformer T. The secondary side of transformer T is connected to the resonant inductor. L r2 Resonant capacitor C r2 The secondary resonant cavity is formed and connected to the secondary circuit through the secondary resonant cavity.

[0023] like Figure 1 As shown, the secondary-side three-level half-bridge circuit includes a sixth switching transistor. Q 6. Seventh switching transistor Q 7. Eighth switching transistor Q 8. Ninth Switching Transistor Q 9. Second diode D2 and third diode D3; The sixth switching transistor Q 6 and the seventh switch tube Q 7. Series connection, the eighth switch transistor Q 8 and the ninth switch tube Q 9 are connected in series, with the anode of the second diode D2 connected to the source of the seventh switch, and the cathode of the second diode D2 connected to the sixth switch. Q 6 and the seventh switch tube Q The connection point of 7 is connected, and the anode of the third diode D3 is connected to the eighth switch. Q The drain connection of the third diode D3 is connected to the eighth switching transistor. Q 8 and the ninth switch tube Q 9 connection points; The other end of the secondary three-level half-bridge circuit is connected to the first output capacitor. C 4 and second output capacitor C 5, and through the first output capacitor C 4 and the second output capacitor C 5 Connect to the DC grid output port V DC .

[0024] It should be noted that, Figure 1The first diode D1 shown is connected to the photovoltaic port. V PV The connection between the primary side resonant cavity and the secondary side resonant cavity is primarily to prevent current from flowing back from the primary side circuit to the photovoltaic port under certain operating conditions, which could damage the photovoltaic equipment.

[0025] The embodiments of the present invention can realize energy transmission between three ports. Compared with the traditional scheme of using two converters to connect three ports, the optical energy storage converter performs switch multiplexing, which reduces cost and size while having fewer switching devices.

[0026] In one alternative embodiment, the input voltage of the photovoltaic port and the output voltage of the energy storage port satisfy the following relationship: ; In the formula, This is the input voltage of the photovoltaic port; This refers to the output voltage of the energy storage port. The first switching transistor Q 1 and the fifth switch Q 5. The duration of simultaneous conduction; The first switching transistor Q 1 and the fourth switching transistor Q 4. The duration of simultaneous conduction; For the second switching transistor Q 2. Third switching transistor Q 3 and the fourth switching transistor Q 4. The duration of simultaneous conduction.

[0027] It is worth noting that this expression is established to quantify the voltage relationship between the photovoltaic port and the energy storage port, and its core is based on the correlation characteristics between the conduction time of the switching transistor in the converter and the port voltage. By clearly defining... Q 1 and Q 5. Common conduction time (T1) Q 1 and Q 4. Common conduction time (T2) Q 2. Q 3 and Q The three key switching periods, including the common conduction time (T3), are crucial for establishing the photovoltaic input voltage (VPV) and the energy storage output voltage (Vs). Ba The quantitative relationship between the two ports provides a theoretical basis for the voltage regulation and operating status control of the converter, thereby ensuring that the voltage of the two ports can adapt to the energy transmission requirements under different operating modes (such as photovoltaic power transmission to energy storage, photovoltaic and energy storage combined power supply, etc.).

[0028] Among them, the primary resonant frequency of the converter f r1 With secondary resonant frequencyf r2 satisfy: ; In the formula, L r1 This is the primary resonant inductance, measured in ohms (H). C r1 This is the primary resonant capacitor, measured in F. L r2 This is the secondary resonant inductance, measured in ohms (H). C r2 This is the secondary resonant capacitor, measured in F. Switching frequency of the optical-storage converter f s Normalization is performed, and the output DC port is then used. V DC With photovoltaic port V PV The gain expression between them is as follows: ; In the formula, n The transformer turns ratio is dimensionless. V PV This refers to the input voltage at the photovoltaic port, expressed in volts (V). V DC This refers to the output voltage at the load port, in volts (V). n The normalized angular frequency is dimensionless. k This is the ratio of the magnetizing inductance to the primary resonant inductance, which is dimensionless. Q The quality factor of the resonant network is dimensionless.

[0029] The present invention adopts a control scheme combining frequency conversion and duty cycle. Frequency conversion is used to adjust the gain between the photovoltaic port and the output port, and the duty cycle is used to adjust the gain between the photovoltaic port and the energy storage port. This achieves power decoupling between the three ports, making the converter easy to control.

[0030] Furthermore, the conduction times of the first switch, the second switch, the third switch, the fourth switch, and the fifth switch satisfy the following relationship: ; In the formula, V PV This is the input voltage at the photovoltaic port, in volts (V). T4 is the output voltage of the energy storage port, in volts (V); T4 is the second switching transistor. Q 2. Third switching transistor Q 3 and the fifth switching transistor Q5. The duration of simultaneous conduction, in seconds; L in This is the power inductance value, in watts (H). I x This represents the minimum value of the power inductor current, expressed in amperes (A). I o The output current of the energy storage port is expressed in amperes (A); y a The current value of the power inductor at the end of time T1, in amperes (A); y b This is the power inductor current value at the end of time T2, in amperes (A). f s This represents the switching frequency of the photovoltaic-storage converter, measured in Hz.

[0031] It should be noted that this formula is the calculation equation for T1, T2, T3, and T4 to ensure that the switching transistor achieves full-range ZVS (zero voltage switching).

[0032] Compared to some three-port converters, the embodiments of the present invention can achieve soft switching of all switching devices across the entire range, have an efficiency advantage at high frequencies, and are more likely to achieve high power density.

[0033] In one alternative embodiment, the power inductance value must satisfy the following expression: ; ; In the formula, L in Here is the power inductance value, in watts (H); M is an intermediate variable for simplified calculations. V PV This is the input voltage at the photovoltaic port, in volts (V). V Ba This is the output voltage of the energy storage port, in volts (V). P out This represents the power transferred from the photovoltaic port to the energy storage port, measured in watts (W). I x This represents the minimum power inductor current, measured in amperes (A); T s The switching period is expressed in seconds (s).

[0034] It is worth noting that the power inductor plays a crucial role in energy storage and transfer in the converter, and its correct value is essential to the converter's performance. This formula ensures that the power inductor meets the performance requirements of the converter under specific operating conditions by considering parameters such as the photovoltaic port input voltage, the energy storage port output voltage, the power transferred from the photovoltaic port to the energy storage port, the minimum power inductor current, and the switching cycle.

[0035] In one optional embodiment, the H5 bridge DC three-port optical-storage converter is used for: When the DC grid output port is off-grid and not transmitting power, the output power of the photovoltaic port is transmitted to the energy storage port; When the photovoltaic port has no power output, the energy storage port performs forward power transfer to the DC grid output port, or the DC grid output port performs reverse power transfer to the energy storage port. When the output power of the photovoltaic port is equal to the required power of the DC grid output port, the power is transmitted from the photovoltaic port to the DC grid output port; When the output power of the photovoltaic port is less than the required power of the DC grid output port, the power is transmitted from both the photovoltaic port and the energy storage port to the DC grid output port. When the output power of the photovoltaic port is greater than the required power of the DC grid output port, the power is transmitted from the photovoltaic port to the DC grid output port and the energy storage port.

[0036] That is, the H5 bridge DC three-port photovoltaic-storage converter operates in five modes. See also Figure 2 , Figure 2 This is a schematic diagram illustrating the classification of operating modes of an H5 bridge DC three-port photovoltaic-storage converter provided in an embodiment of the present invention. For example... Figure 2 As shown, when the DC grid output port V DC When off-grid and not transmitting power, the photovoltaic-storage converter is in operating mode 1, at which time the output power of the photovoltaic port is transmitted to the energy storage port. V Ba Store it.

[0037] When there is no photovoltaic power output, the photovoltaic-storage converter is in operating mode 2. During forward transmission, it operates through the energy storage port. V Ba Output port of DC power grid V DC Provides power; in reverse transmission, it is transmitted from the DC grid output port. V DC Energy storage port V Ba Charge.

[0038] When the photovoltaic output power equals the power demand at the DC port, the photovoltaic-storage converter is in operating mode 3. In this mode, power is drawn solely from the photovoltaic port. V PV Transmitted to DC grid output port V DC .

[0039] When the photovoltaic output power is less than the power demand at the DC grid output port, the photovoltaic-storage converter is in operating mode 4. At this time, power is drawn from the photovoltaic port. V PV With energy storage port V Ba Commonly transmitted to the DC grid output port V DC .

[0040] When the photovoltaic output power exceeds the power demand at the DC grid output port, the photovoltaic-storage converter operates in mode 5. At this time, power is drawn from the photovoltaic port. V PV Transmitted to DC grid output port V DC With energy storage port V Ba And store excess photovoltaic power in a timely manner.

[0041] See Figure 3 , Figure 3 This is an equivalent topology diagram of an H5 bridge DC three-port photovoltaic-storage converter in reverse transmission, provided by an embodiment of the present invention. It should be noted that when the photovoltaic-storage converter is in operating mode 2 and in reverse transmission, the DC grid output port... V DC Energy storage port V Ba Charging, and the second switching transistor Q 2 is always on; therefore, the equivalent circuit topology is as follows: Figure 3 As shown.

[0042] To facilitate understanding by those skilled in the art, this embodiment of the invention further analyzes the periodic operating modes of the provided optical-storage converter. For example, since operating mode 5 is the most representative, this embodiment analyzes the operation of the optical-storage converter in operating mode 5.

[0043] See Figure 4 , Figure 4 This is a waveform diagram of the driving signals and key nodes of the H5 bridge DC three-port photovoltaic-storage converter provided in an embodiment of the present invention. Figure 4 As shown, five switching transistors Q 1 to Q The drive signals for 5 are respectively v gs1 ~ v gs5 The drive signal for each switch transistor indicates the time it is on (high level) and off (low level). For example, v gs1 Indicates the switching transistor Q The drive signal of 1, during the high level periodQ 1 is on, during low level period Q 1. Turn off.

[0044] exist Figure 4 middle, V PV This indicates the input voltage at the photovoltaic port. V Ba This indicates the output voltage of the energy storage port. v ab Indicates as Figure 1 The voltage between points a and b in the primary-side H5 bridge circuit shown is v cd Indicates as Figure 1 The voltage between points c and d in the secondary-side three-level half-bridge circuit is shown. The voltage waveform illustrates the changes in the voltage at each port under different switching states. Figure 4 As shown, based on the key waveforms of the optical-storage converter, one cycle of the optical-storage converter can be divided into 10 modes, with the time period marked from t1 to t2. 11 Each time period corresponds to a different combination of switching states, demonstrating the operation of the optical-storage converter within one cycle.

[0045] See Figure 5 , Figure 5 This is a schematic diagram of the working modes of the H5 bridge DC three-port photovoltaic-storage converter provided in an embodiment of the present invention.

[0046] like Figure 5 As shown in (a), the operating mode is [ t 1~ t 2]: In t At time 1, the switching transistor Q 1. When the circuit is turned on, the power inductor will be in operation for the duration of this period. L in Terminal voltage is V PV Power inductor L in It is in charging state. The resonant cavity terminal voltage is... V PV / 2, the resonant cavity is operating in the positive half-cycle, and the resonant cavity current is... i Lr1 The positive side is connected to the secondary side of the transformer via a switching transistor. Q 6. Q The parasitic diode 7 is used for rectification, and the secondary port voltage of the resonant cavity is... V DC / 2.

[0047] like Figure 5 As shown in (b), the operating mode is [ t 2~ t 3]: Int At time 2, the switching transistor Q 3. Turn off, due to the resonant cavity inductor current i Lr1 The reason why it cannot change abruptly is the resonant cavity current. i Lr1 Still positive, resonant cavity current i Lr1 After the switching transistor Q The parasitic diode of transistor 2 provides freewheeling current, and the switching process is completed during this stage. Q 2. The charging and discharging of parasitic capacitance enables the switching transistor. Q 2. Soft switching. Due to the resonant inductor current at this time. i Lr1 Equal to the magnetizing inductance current i Lm During this stage, no energy is transferred to the secondary side of the transformer.

[0048] like Figure 5 As shown in (c), the operating mode is [ t 3~ t 4]: In t At time 3, switch Q 2 is on, and the resonant cavity port voltage is - V PV / 2, the resonant cavity operates in the negative half-cycle, and the resonant cavity current... i Lr1 If negative, the transformer secondary side passes through the switching transistor. Q 8. Q The parasitic diode 9 is used for rectification, and the voltage at the secondary port of the resonant cavity is - V DC / 2. Power inductor during this period L in的 The operating mode is the same as the previous stage, and the power inductor is still in the charging state.

[0049] like Figure 5 As shown in (d), the operating mode is [ t 4~ t 5]: In t At time 4, the switching transistor Q 5. Turn off, due to the power inductor current. i Lin The current of the power inductor cannot change abruptly. i Lin After the switching transistor Q The parasitic diode at position 4 provides freewheeling current, and the switching process is completed during this stage. Q 4. The charging and discharging of parasitic capacitance enables the switching transistor. Q 4. Soft switching. During this period, the operating mode of the resonant cavity is the same as in the previous stage, and the resonant cavity terminal voltage and port voltage are - VPV / 2, the resonant cavity operates in the negative half-cycle, the primary side resonant cavity current... i Lr1 If negative, the transformer secondary side passes through the switching transistor. Q 8. Q The parasitic diode 9 is used for rectification, and the voltage at the secondary port of the resonant cavity is - V DC / 2.

[0050] like Figure 5 As shown in (e), the operating mode is [ t 5~ t 6]: In t At time 5, the switching transistor Q 4. During this period, the power inductor is turned on. Lin Terminal voltage is V PV - V Ba The input voltage is directly transmitted to the output terminal through the power inductor; this is the direct power transfer stage. During this period, the operating mode of the resonant cavity is the same as in the previous stage.

[0051] like Figure 5 As shown in (f), the operating mode is [ t 6~ t 7]: In t At time 6, the switching transistor Q 1. Turn off, due to the power inductor current i Lin And excitation inductance i Lm Mutation is not allowed at this time. i Lin and i Lm They pass through the switching transistor. Q The parasitic diode of transistor 3 provides freewheeling current, thus completing the switching process. Q 3. The charging and discharging of parasitic capacitance enables the switching transistor. Q 3. Soft switching. At this time, the resonant inductor current... i Lr1 Equal to the magnetizing inductance current i Lm Size, does not transfer energy to the secondary side of the transformer.

[0052] like Figure 5 As shown in (g), the operating mode is [ t 7~ t 8]: In t At time 7, the switching transistor Q 3 is turned on, and the voltage at the resonant cavity terminals is V PV / 2, the resonant cavity is operating in the positive half-cycle, and the resonant cavity current is...i Lr1 The positive side is connected to the transformer secondary side via the switching transistor. Q 6. Q The parasitic diode 7 is used for rectification, and the voltage at the secondary port of the resonant cavity is V DC / 2. Power Inductor Lin Terminal voltage is - V Ba Power inductor current i Lin From the output terminal through the switching transistor Q 2 and Q 3. Flow back, this stage is the reset stage.

[0053] like Figure 5 As shown in (h), the operating mode is [ t 8~ t 9]: In t At time 8, the switching transistor Q 4. Turn off, due to the power inductor current. i Lin The current of the power inductor cannot change abruptly. i Lin After the switching transistor Q The parasitic diode of transistor 5 provides freewheeling current, and the switching process is completed during this stage. Q 5. The charging and discharging of parasitic capacitance enables the switching transistor. Q 5. Soft switching. During this period, the operating mode of the resonant cavity is the same as that of the previous stage system.

[0054] like Figure 5 As shown in (i), the operating mode is [ t 9~ t 10 ]:exist t At time 9, the switching transistor Q 5. On, power inductor Lin The terminal voltage is clamped to 0, and the power inductor current... i Lin Through the switching transistor Q 2, Q 3, Q 5. Continue current flow; this is the continue current stage. During this time, the operating mode of the resonant cavity is the same as in the previous stage.

[0055] like Figure 5 As shown in (j), the operating mode is [ t 10 ~ t 11 ]:exist t 10 At any moment, the switching transistor Q 2. Turn off, due to the power inductor current iLin The current of the power inductor cannot change abruptly. i Lin After the switching transistor Q The parasitic diode of transistor 1 provides freewheeling current, and the switching process is completed during this stage. Q 1. The charging and discharging of parasitic capacitance enables the switching transistor. Q 1. Soft switching. During this period, the operating mode of the resonant cavity is the same as in the previous stage.

[0056] To further verify the performance of the optical-storage converter provided in this embodiment of the invention in five working modes, the following will introduce it through specific simulation scenarios and waveform data.

[0057] For example, see Table 1, which shows the main circuit design parameters of the optical-storage converter in one optional embodiment.

[0058] Table 1 Main Circuit Design Parameters of the Photovoltaic-Storage Converter

[0059] Taking the design parameters in Table 1 as an example, the embodiment of the present invention specifies the output voltage. V DC Simulation verification was performed on the Simulink platform under rated conditions of 1500V and 1kW.

[0060] See Figures 6-7 This is a schematic diagram of the steady-state operation of the H5 bridge DC three-port photovoltaic-storage converter provided in the embodiment of the present invention under working mode 1.

[0061] When there is no power demand at the DC grid output, the input voltage at the photovoltaic terminal is... V PV =400V, energy storage terminal output voltage V Ba When the voltage is 300V and the rated power is 1000W, the photovoltaic-storage converter is in operating mode 1. The steady-state simulation waveform of the photovoltaic-storage converter at this time is as follows: Figure 6 As shown. Among them, Q 1. Q 2. Q 4. Q 5 represents the switching transistor drive waveform. The drive signal for each switching transistor indicates the time it is on (high level) and off (low level). v Lin The voltage waveform at the power inductor terminal is rectangular and pulse-shaped, indicating the voltage change experienced by the power inductor during the switching cycle. i Lin The waveform shows the current of the power inductor, while the voltage waveform is rectangular and pulse-shaped, indicating the voltage change experienced by the power inductor during the switching cycle.

[0062] When there is no power demand at the load end, but the input voltage at the photovoltaic end is low. V PV =400V, energy storage terminal output voltage V Ba At 500V and a rated power of 1000W, the steady-state simulation waveform of the photovoltaic-storage converter is as follows: Figure 7 As shown. Among them, Q 1. Q 2. Q 4. Q 5 represents the switching transistor drive waveform. The drive signal for each switching transistor indicates the time it is on (high level) and off (low level). v Lin The voltage waveform at the power inductor terminal is rectangular and pulse-shaped, indicating the voltage change experienced by the power inductor during the switching cycle. v Lin The waveform of the power inductor is sawtooth-shaped, indicating that the power inductor is continuously charging and discharging during the switching cycle.

[0063] Depend on Figures 6-7 It can be seen that the photovoltaic-energy storage converter can operate in a steady state under different operating conditions in working mode 1. The waveforms repeat periodically without obvious transient fluctuations, and it can stably transmit photovoltaic power to the energy storage port.

[0064] See Figures 8-9 This is a schematic diagram of the steady-state operation of the H5 bridge DC three-port photovoltaic-storage converter provided in the embodiment of the present invention under working mode 2.

[0065] When there is no photovoltaic voltage input, the energy storage terminal input voltage V Ba =400V, DC output voltage V DC The steady-state simulation waveform of the photovoltaic-storage converter at 1500V and rated power of 1000W is as follows: Figure 8 As shown. Among them Q 1. Q 2 represents the switching transistor drive waveform. v Lin The voltage waveform at the power inductor terminal is rectangular and pulse-shaped, indicating the voltage change experienced by the power inductor during the switching cycle. i Lin The waveform of the power inductor is sawtooth-shaped, indicating that the power inductor is continuously charging and discharging during the switching cycle. v ab This is the voltage waveform at the input port of the resonant cavity. v cdThe output voltage waveform of the resonant cavity shows a stable DC voltage, indicating that the converter can provide a stable output voltage under this operating condition. i Lr1 The current waveform is a resonant current waveform, which is sinusoidal, indicating that the converter can provide a stable output current under this operating condition.

[0066] When the DC output terminal is connected to a power supply, the DC input voltage... V DC =1500V, energy storage terminal output voltage V Ba When the voltage is 400V and the rated power is 1000W, the steady-state simulation waveform of the photovoltaic-storage converter is as follows: Figure 9 As shown. Among them Q 1. Q 2 represents the waveform of the switching transistor drive. v Lin The voltage waveform at the power inductor terminal is rectangular and pulse-shaped, indicating the voltage change experienced by the power inductor during the switching cycle. i Lin The waveform of the power inductor is sawtooth-shaped, indicating that the power inductor is continuously charging and discharging during the switching cycle. v ab This is the voltage waveform at the input port of the resonant cavity. v cd The voltage waveform at the output port of the resonant cavity is rectangular pulse-shaped, indicating the voltage change experienced by the power inductor during the switching cycle. i Lr1 The resonant current waveform shows a sine wave in the output current waveform, indicating that the converter can provide a stable output current under this operating condition.

[0067] Depend on Figures 8-9 It can be seen that the photovoltaic-energy storage converter can operate in a steady state under different operating conditions in working mode 2. The waveforms repeat periodically without obvious transient fluctuations, indicating that the photovoltaic-energy storage converter can stably transmit photovoltaic and energy storage power to the DC port in working mode 2.

[0068] See Figure 10 , Figure 10 This is a schematic diagram of the steady-state operation of the H5 bridge DC three-port photovoltaic-storage converter provided in the embodiment of the present invention under operating mode 3.

[0069] When the energy generated by the photovoltaic terminal is exactly equal to the energy required by the load, the input voltage of the photovoltaic terminal is... V PV =400V, DC output V DC The steady-state simulation waveform of the photovoltaic-storage converter at 1500V and rated power of 1000W is as follows: Figure 10 As shown. Among them Q 1. Q 3 represents the waveform of the switching transistor drive. v ab This is the voltage waveform at the input port of the resonant cavity. v cd The output voltage waveform of the resonant cavity shows a stable DC voltage, indicating that the converter can provide a stable output voltage under this operating condition. i Lr1 The resonant current waveform shows a sinusoidal output current waveform, indicating that the converter can provide a stable output current under this operating condition. Figure 10 It can be seen that, under operating mode 3, the photovoltaic-storage converter has verified the feasibility and stability of power transfer only from the photovoltaic port to the DC port.

[0070] See Figure 11 , Figure 11 This is a schematic diagram of the steady-state operation of the H5 bridge DC three-port photovoltaic-storage converter provided in the embodiment of the present invention under operating mode 4.

[0071] When the energy generated by the photovoltaic terminal is less than the energy required by the load, the input voltage of the photovoltaic terminal... V PV =400V, energy storage terminal input voltage V Ba =400V, DC output voltage V DC With a voltage of 1500V, 500W input at both the photovoltaic and energy storage ends, and a rated power of 1000W, the steady-state simulation waveform of the photovoltaic-energy storage converter is as follows: Figure 11 As shown. Among them Q 1. Q 2 represents the switching transistor drive waveform. v Lin The voltage waveform at the power inductor terminal is rectangular and pulse-shaped, indicating the voltage change experienced by the power inductor during the switching cycle. i Lin The waveform of the power inductor is sawtooth-shaped, indicating that the power inductor is continuously charging and discharging during the switching cycle. v ab This is the voltage waveform at the input port of the resonant cavity. v cd The output voltage waveform of the resonant cavity shows a stable DC voltage, indicating that the converter can provide a stable output voltage under this operating condition. i Lr1 The resonant current waveform shows a sinusoidal output current waveform, indicating that the converter can provide a stable output current under this operating condition. Figure 11It can be verified that the photovoltaic-energy storage converter can supply power to the DC port in working mode 4 by combining photovoltaic and energy storage.

[0072] See Figures 12-13 This is a schematic diagram of the steady-state operation of the H5 bridge DC three-port photovoltaic-storage converter provided in the embodiment of the present invention under working mode 5.

[0073] When the energy generated by the photovoltaic terminal is greater than the energy required by the load, the input voltage of the photovoltaic terminal... V PV =400V, energy storage output voltage V Ba =300V, DC output V DC With a voltage of 1500V, a DC output of 500W at both the energy storage end and the DC end, and a rated power of 1000W, the steady-state simulation waveform of the photovoltaic-energy storage converter is as follows: Figure 12 As shown. Among them Q 1. Q 2 represents the switching transistor drive waveform. v Lin The voltage waveform at the power inductor terminal is rectangular and pulse-shaped, indicating the voltage change experienced by the power inductor during the switching cycle. i Lin The waveform of the power inductor is sawtooth-shaped, indicating that the power inductor is continuously charging and discharging during the switching cycle. v ab This is the voltage waveform at the input port of the resonant cavity. v cd The output voltage waveform of the resonant cavity shows a stable DC voltage, indicating that the converter can provide a stable output voltage under this operating condition. i Lr1 The output current waveform exhibits a sine wave, indicating that the converter can provide a stable output current under this operating condition.

[0074] When the energy generated by the photovoltaic terminal is greater than the energy required by the load, the input voltage of the photovoltaic terminal... V PV =400V, energy storage output voltage V Ba =500V, DC output V DC With a voltage of 1500V, a DC output of 500W at both the energy storage end and the DC end, and a rated power of 1000W, the steady-state simulation waveform of the photovoltaic-energy storage converter is as follows: Figure 13 As shown. Among them, Q 1. Q 2 represents the switching transistor drive waveform. v LinThe voltage waveform at the power inductor terminal is rectangular and pulse-shaped, indicating the voltage change experienced by the power inductor during the switching cycle. i Lin The waveform of the power inductor is sawtooth-shaped, indicating that the power inductor is continuously charging and discharging during the switching cycle. v ab This is the voltage waveform at the input port of the resonant cavity. v cd The output voltage waveform of the resonant cavity shows a stable DC voltage, indicating that the converter can provide a stable output voltage under this operating condition. i Lr1 The resonant current waveform shows a sine wave in the output current waveform, indicating that the converter can provide a stable output current under this operating condition.

[0075] Depend on Figures 12-13 It can be seen that the photovoltaic-energy storage converter can operate in a steady state under different operating conditions in working mode 5. The waveforms repeat periodically without obvious transient fluctuations, indicating that the photovoltaic-energy storage converter can stably transmit photovoltaic power to both the DC port and the energy storage port simultaneously in working mode 5.

[0076] In summary, based on the steady-state simulation waveforms, it can be seen that the H5-bridge DC three-port photovoltaic-energy storage converter provided in this embodiment of the invention can achieve energy transmission across three ports. Simulation verification shows that it exhibits stable waveforms under different operating conditions, and the simulated waveforms match the theoretical waveforms, proving its stable operation under various modes. The H5-bridge DC three-port photovoltaic-energy storage converter provided in this embodiment of the invention can connect to photovoltaic, energy storage, and DC ports, covering scenarios such as photovoltaic energy storage, energy storage power supply, and combined photovoltaic and energy storage power supply through five operating modes, thus meeting energy distribution requirements under different power demands. Furthermore, the design ensures equal resonant frequencies on the primary and secondary sides, and the combination of the parasitic diode freewheeling of the switching transistor enables soft switching, reducing switching losses and improving transmission efficiency.

[0077] Based on the above system items, the present invention provides corresponding embodiments of the method items.

[0078] See Figure 14 , Figure 14 This is a flowchart of a control method for an H5 bridge DC three-port photovoltaic-storage converter provided in an embodiment of the present invention. The H5 bridge DC three-port photovoltaic-storage converter control method, applied to the H5 bridge DC three-port photovoltaic-storage converter as described in any of the preceding embodiments, includes steps S1 to S2: S1. Control the operating mode of the photovoltaic-energy storage converter based on the input voltage of the photovoltaic port, the output voltage of the energy storage port, and the voltage of the DC output port. S2. According to the operating mode, control the turn-on and turn-off times of each switch in the primary H5 bridge converter circuit and the secondary three-level half-bridge circuit.

[0079] The H5 bridge DC three-port photovoltaic-storage converter control method provided in this invention determines the operating mode based on the photovoltaic port input voltage, the energy storage port output voltage, and the DC output port voltage. It also precisely controls the on and off times of each switch according to different operating modes. On the one hand, it can reduce switching losses by utilizing soft switching technology, and on the other hand, it can reasonably allocate the energy flow between the photovoltaic, energy storage, and DC ports, improve the overall energy transmission efficiency, and ensure the reliable operation of the photovoltaic-storage converter.

[0080] The above description represents the preferred embodiments of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications are also considered to be within the scope of protection of the present invention.

Claims

1. An H5 bridge DC three-port opto-storage converter, characterized in that, It includes a primary-side H5 bridge circuit, a primary-side resonant cavity, a transformer, a secondary-side resonant cavity, and a secondary-side three-level half-bridge circuit; The primary-side H5 bridge circuit is connected to the photovoltaic port and the energy storage port respectively. The primary-side H5 bridge circuit is connected to one end of the primary-side resonant cavity. The other end of the primary-side resonant cavity is connected to the primary side of the transformer. The secondary side of the transformer is connected to one end of the secondary-side resonant cavity. The other end of the secondary-side resonant cavity is connected to one end of the secondary-side three-level half-bridge circuit. The other end of the secondary-side three-level half-bridge circuit is connected to the DC grid output port. The primary-side H5 bridge circuit is used to realize the power input and regulation of the photovoltaic port and the energy storage port. The primary-side resonant cavity, the transformer and the secondary-side resonant cavity are used for power transmission matching. The secondary-side three-level half-bridge circuit is used to stabilize the voltage of the DC grid output port.

2. The H5 bridge DC three-port optical-storage converter as described in claim 1, characterized in that, The primary-side H5 bridge circuit includes three switching arms, a half-bridge, a power inductor, a first supporting capacitor, a second supporting capacitor, and a third supporting capacitor. The three-switch bridge arm includes a first switch transistor, a first switch transistor and a first switch transistor connected in series. The three-switch bridge arm is connected to the photovoltaic port. The first supporting capacitor and the second supporting capacitor are connected in parallel with the three-switch bridge arm. The half-bridge includes a fourth and a fifth switching transistor connected in series. The half-bridge is connected to the energy storage port. The third supporting capacitor is connected in parallel with the half-bridge. One end of the power inductor is connected between the fourth switch and the switch, and the other end of the power inductor is connected between the first switch and the second switch.

3. The H5 bridge DC three-port optical-storage converter as described in claim 1, characterized in that, The secondary-side three-level half-bridge circuit includes a sixth switch, a seventh switch, an eighth switch, a ninth switch, a second diode, and a third diode; The sixth switch is connected in series with the seventh switch, and the eighth switch is connected in series with the ninth switch. The anode of the second diode is connected to the source of the seventh switch, and the cathode of the second diode is connected to the connection point of the sixth switch and the seventh switch. The anode of the third diode is connected to the drain of the eighth switch, and the cathode of the third diode is connected to the connection point of the eighth switch and the ninth switch. The other end of the secondary-side three-level half-bridge circuit is connected to the first output capacitor and the second output capacitor, and is connected to the DC power grid output port through the first output capacitor and the second output capacitor.

4. The H5 bridge DC three-port optical-storage converter as described in claim 1, characterized in that, The H5 bridge DC three-port optical-storage converter is used for: When the DC grid output port is off-grid and not transmitting power, the output power of the photovoltaic port is transmitted to the energy storage port; When the photovoltaic port has no power output, the energy storage port performs forward power transfer to the DC grid output port, or the DC grid output port performs reverse power transfer to the energy storage port. When the output power of the photovoltaic port is equal to the required power of the DC grid output port, the power is transmitted from the photovoltaic port to the DC grid output port; When the output power of the photovoltaic port is less than the required power of the DC grid output port, the power is transmitted from both the photovoltaic port and the energy storage port to the DC grid output port. When the output power of the photovoltaic port is greater than the required power of the DC grid output port, the power is transmitted from the photovoltaic port to the DC grid output port and the energy storage port.

5. The H5 bridge DC three-port optical-storage converter as described in claim 1, characterized in that, The input voltage of the photovoltaic port and the output voltage of the energy storage port satisfy the following relationship: ； In the formula, This is the input voltage of the photovoltaic port; This refers to the output voltage of the energy storage port. The time during which the first and fifth switching transistors are both turned on; The time during which the first and fourth switching transistors are both turned on; This refers to the time during which the second, third, and fourth switches are all turned on.

6. The H5 bridge DC three-port optical-storage converter as described in claim 5, characterized in that, The conduction times of the first switch, the second switch, the third switch, the fourth switch, and the fifth switch satisfy the following relationship: ； In the formula, T4 is the second switching transistor. Q 2. Third switching transistor Q 3 and the fifth switching transistor Q 5. The duration of simultaneous conduction; L in This refers to the power inductance value. I x This is the minimum value of the power inductor current; I o y is the output current of the energy storage port; a The value of the power inductor current at the end of time T1; y b This represents the power inductor current value at the end of time T2; f s This is the switching frequency of the optical-storage converter.

7. The H5 bridge DC three-port optical-storage converter as described in claim 6, characterized in that, The power inductance value satisfies the following expression: ； ； In the formula, L in Here, represents the power inductance value; M is an intermediate variable used for simplified calculations. P out T represents the power transferred from the photovoltaic port to the energy storage port. s The switching cycle.

8. The H5 bridge DC three-port optical-storage converter as described in claim 1, characterized in that, The primary resonant frequency and the secondary resonant frequency of the optical-storage converter are equal.

9. The H5 bridge DC three-port optical-storage converter as described in claim 1, characterized in that, The primary resonant cavity includes a first resonant inductor and a first resonant capacitor; the secondary resonant cavity includes a second resonant inductor and a second resonant capacitor.

10. A control method for an H5 bridge DC three-port photovoltaic-storage converter, characterized in that, Applied to the H5 bridge DC three-port optical-storage converter as described in any one of claims 1 to 9, comprising: The operating mode of the photovoltaic-energy storage converter is controlled based on the input voltage of the photovoltaic port, the output voltage of the energy storage port, and the voltage of the DC output port. According to the operating mode, the turn-on and turn-off times of each switch in the primary H5 bridge circuit and the secondary three-level half-bridge circuit are controlled.

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