A battery-less inverter system
Patent Information
- Application Number
- CN202522245112.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2025-10-23
- Publication Date
- 2026-11-03
- Estimated Expiration
- 2035-10-23
AI Technical Summary
Traditional inverter systems rely on batteries, resulting in high manufacturing costs, heavy maintenance burdens, and environmental pollution risks, making it difficult to achieve efficient and stable power supply in areas without electricity.
Design a battery-free inverter system that employs multi-source input and intelligent switching. It generates 120V/220V AC power through an inverter unit and a step-up transformer. Combined with real-time monitoring and signal conditioning by a central processor, it achieves photovoltaic priority power supply and intelligent switching between multiple operating modes.
It simplifies the system structure, reduces costs and maintenance burden, achieves efficient direct-drive energy utilization, ensures stable power supply, improves system reliability and efficiency, adapts to the application of equipment at different voltage levels, ensures stable load operation, and enhances load adaptability by optimizing waveform quality. It is particularly suitable for applications such as solar irrigation and household power supply in areas without electricity, which is in line with the trend of green energy development.
Smart Images
Figure CN224935373U_ABST
Abstract
Description
Technical Field
[0001] This utility model belongs to the field of new energy power generation and power electronics technology, and more specifically, it relates to a battery-free inverter system. Background Technology
[0002] In the fields of new energy power generation and power electronics technology, traditional inverter systems typically rely on batteries as an energy buffer to ensure a stable power supply from intermittent new energy sources such as photovoltaics. However, the introduction of batteries not only significantly increases the system's manufacturing costs and maintenance burden but also faces problems such as limited lifespan, the need for periodic replacement, and environmental pollution risks. Especially in application scenarios such as solar irrigation and household power supply in areas without electricity, users often expect a system with a simple structure, convenient maintenance, and the ability to directly utilize solar energy to the maximum extent.
[0003] Therefore, this utility model provides a battery-free inverter system. Utility Model Content
[0004] In view of the above-mentioned problems of existing technology, the purpose of this utility model is to provide a battery-free inverter system that achieves photovoltaic priority direct drive power supply through multi-source input and intelligent switching, and can simultaneously output 120V / 220V AC power. It has a simple structure and is highly efficient and reliable.
[0005] The objective of this utility model can be achieved through the following technical solutions: A battery-free inverter system includes a multi-input unit for receiving DC or AC power, an inverter unit for converting DC power to AC power, a dual-output unit for providing 120V AC output and 220V AC output, a current detection unit for real-time detection of input and output current, a sampling unit for acquiring input and output voltage and current signals, and a control unit. The multi-input unit includes a photovoltaic input port PV+, a photovoltaic input port PV-, a mains input port IN-L, a mains input port IN-N, a generator input port GEN-L, and a generator input port GEN-N. The inverter unit is connected to the multi-input unit and outputs dual AC voltages of 120V and 220V. The dual-output unit is connected to the output terminal of the inverter unit and is connected to a 120V load and a 220V load, respectively. The current detection unit includes several current transformers disposed in the multi-input unit and the dual-output unit. The sampling unit is connected to the current detection unit and the multi-input unit. The control unit is connected to the current detection unit and the sampling unit.
[0006] As a further preferred technical solution of this utility model, the inverter unit includes a full-bridge inverter circuit composed of an insulated-gate bipolar transistor Q13, an insulated-gate bipolar transistor Q14, an insulated-gate bipolar transistor Q15 and an insulated-gate bipolar transistor Q16, and a step-up transformer TX1. The inverter unit outputs 120V and 220V dual AC voltages through the full-bridge inverter circuit and the step-up transformer TX1. The dual-output unit includes a 120V output port OUT120-L, a 120V output port OUT120-N, a 220V output port OUT220-L, and a 220V output port OUT220-N. The dual-output unit is connected to a 120V load through the 120V output port OUT120-L and the 120V output port OUT120-N. The dual-output unit is connected to a 220V load through the 220V output port OUT220-L and the 220V output port OUT220-N. The current detection unit includes shunt resistors R105 and R106 located at the photovoltaic input port PV-, a current transformer CT2 located at the mains input port IN-L, a current transformer CT1 located at the generator input port GEN-L, a current transformer CT4 located at the 120V output port OUT120-L, and a current transformer CT3 located at the 220V output port OUT220-L.
[0007] As a further preferred technical solution of this utility model, the control unit is a central processing unit (CPU), and the CPU has multiple signal acquisition pins. The sampling unit includes an AC voltage sampling circuit connected to the AC input port IN-L and the AC input port IN-N, a generator voltage sampling circuit connected to the generator input port GEN-L and the generator input port GEN-N, a photovoltaic current sampling circuit connected to the photovoltaic input port PV-, a generator current sampling circuit connected to the current transformer CT1, an AC current sampling circuit connected to the current transformer CT2, a 220V output current sampling circuit connected to the current transformer CT3, and a 120V output current sampling circuit connected to the current transformer CT4. The mains voltage sampling circuit is connected to the corresponding signal acquisition pin of the control unit through a first signal conditioning circuit composed of operational amplifier U5A; the generator voltage sampling circuit is connected to the corresponding signal acquisition pin of the control unit through a second signal conditioning circuit composed of operational amplifier U6A; the photovoltaic current sampling circuit is connected to the corresponding signal acquisition pin of the control unit through a third signal conditioning circuit composed of operational amplifier U6C; the generator current sampling circuit is connected to the corresponding signal acquisition pin of the control unit through a fourth signal conditioning circuit composed of operational amplifier U9C; the mains current sampling circuit is connected to the corresponding signal acquisition pin of the control unit through a fifth signal conditioning circuit composed of operational amplifier U8C; the 220V output current sampling circuit is connected to the corresponding signal acquisition pin of the control unit through a sixth signal conditioning circuit composed of operational amplifier U7C; and the 120V output current sampling circuit is connected to the corresponding signal acquisition pin of the control unit through a seventh signal conditioning circuit composed of operational amplifier U5C. The control unit is connected to the drive terminals of the insulated gate bipolar transistors Q13, Q14, Q15 and Q16 of the inverter unit, as well as the control terminals of the relays RY1 and RY2 in the multiple input unit.
[0008] As a further preferred technical solution of this utility model, the photovoltaic input port PV+ and the photovoltaic input port PV- are sequentially connected to a surge protection varistor MOV1, a surge suppression diode D10, a filter capacitor CE3, a filter capacitor CE1, a filter capacitor CE2, a filter capacitor C43, and a filter capacitor C42.
[0009] As a further preferred technical solution of this utility model, the mains input port IN-L is connected to the battery-free inverter system through relay RY2, and the generator input port is connected to the battery-free inverter system through relay RY1.
[0010] As a further preferred technical solution of this utility model, the insulated gate bipolar transistor Q13 and insulated gate bipolar transistor Q16 of the inverter unit form a pair of bridge arms, and the insulated gate bipolar transistor Q14 and insulated gate bipolar transistor Q15 of the inverter unit form another pair of bridge arms. The primary winding of the step-up transformer TX1 is connected between the midpoints of the two sets of bridge arms.
[0011] As a further preferred technical solution of this utility model, an output capacitor C45 is connected in parallel to the 120V output port OUT120-L and the 120V output port OUT120-N, and an output capacitor C46 is connected in parallel to the 220V output port OUT220-L and the 220V output port OUT220-N.
[0012] As a further preferred technical solution of this utility model, the operational amplifier used in the first signal conditioning circuit, the second signal conditioning circuit, the third signal conditioning circuit, the fourth signal conditioning circuit, the fifth signal conditioning circuit, the sixth signal conditioning circuit, and the seventh signal conditioning circuit is of model TL074C.
[0013] As a further preferred technical solution of this utility model, the control unit calculates and compares the relationship between the photovoltaic input power P1, the mains input power P2, the generator input power P3 and the 120V output power P4 and the 220V output power P5 through the current detection unit and the sampling unit connected to it, so as to control the closing and opening of the relays RY1 and RY2, thereby adjusting the power output of the inverter unit, and realizing the working modes including photovoltaic power supply alone, photovoltaic and mains power supply, photovoltaic and generator power supply, and three-input power supply.
[0014] As a further preferred technical solution of this utility model, the battery-free inverter system does not include a battery, and the electrical energy received by the multi-input unit is directly converted by the inverter unit and supplied to the dual-output unit.
[0015] As described above, the battery-free inverter system provided by this utility model has the following beneficial effects: 1. This utility model utilizes the aforementioned battery-free inverter system. Compared with existing technologies, this structure, through its battery-free design, eliminates the dependence of traditional inverter systems on batteries, avoiding the maintenance costs, lifespan limitations, and environmental pollution associated with battery energy storage. The multi-input unit is directly coupled to the inverter unit, and electrical energy is supplied to the dual outputs after real-time conversion. This simplifies the system structure, reduces manufacturing costs and maintenance burden, and achieves direct-drive, high-efficiency energy utilization.
[0016] 2. This utility model utilizes the aforementioned battery-free inverter system. Compared with the prior art, it uses a control unit to collect voltage and current signals from each input / output terminal in real time, calculates the difference between photovoltaic power P1, mains power P2, generator power P3 and load power P4+P5, and dynamically controls the on / off states of relays RY1 and RY2 to achieve intelligent switching of four working modes. This design significantly improves system reliability and ensures continuous and stable operation of the load under different scenarios.
[0017] 3. This utility model utilizes the aforementioned battery-free inverter system. Compared with existing technologies, the inverter unit adopts a combination structure of a full-bridge circuit and a step-up transformer TX1 to synchronously generate two AC outputs, 120V and 220V, which are connected to the load through ports OUT120-L / N and OUT220-L / N respectively, meeting the synchronous power requirements of devices with different voltage levels. Parallel capacitors C45 and C46 at the output terminal further optimize waveform quality and enhance load adaptability.
[0018] 4. This utility model utilizes the aforementioned battery-free inverter system. Compared with existing technologies, the system is equipped with multi-channel signal conditioning circuits to perform high-precision acquisition and conditioning of input / output current and voltage, ensuring that the control unit monitors power balance in real time. The current detection unit can trigger a fast protection mechanism in case of overload or short circuit, immediately shutting down the IGBT drive signal to prevent equipment damage.
[0019] 5. This utility model utilizes the aforementioned battery-free inverter system. Compared with existing technologies, by prioritizing the use of photovoltaic energy and supplementing with backup power on demand, the system maximizes the utilization of solar energy and reduces dependence on fossil fuels. It is particularly suitable for scenarios such as solar irrigation and household power supply in areas without electricity, aligning with the trend of green energy development.
[0020] Additional aspects and advantages of this invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description
[0021] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0022] Figure 1 This is a product block diagram of a battery-free inverter system according to this utility model application. Figure 2 This is a schematic diagram of the main power of a battery-free inverter system according to this utility model application; Figure 3 This is a sampling principle diagram of a battery-free inverter system according to this utility model application.
[0023] Summary of figure labels and their descriptions: 100. Multi-input unit; 200. Dual-output unit; 300. Current detection unit; 400. Sampling unit; 410. Mains voltage sampling circuit; 420. Generator voltage sampling circuit; 430. Photovoltaic current sampling circuit; 440. Generator current sampling circuit; 450. Mains current sampling circuit; 460. 220V output current sampling circuit; 470. 120V output current sampling circuit; 500. Control unit. Detailed Implementation
[0024] The following specific embodiments illustrate the implementation of this utility model. Those skilled in the art can easily understand other advantages and effects of this utility model from the content disclosed in this specification.
[0025] It should be noted that the structures, proportions, and sizes depicted in the accompanying drawings are merely for illustrative purposes and to aid those skilled in the art. They are not intended to limit the scope of this invention and therefore have no substantial technical significance. Any modifications to the structure, changes in proportions, or adjustments to size, provided they do not affect the effectiveness or purpose of this invention, should still fall within the scope of the technical content disclosed herein. Furthermore, the terms "upper," "lower," "left," "right," "middle," and "one" used in this specification are merely for clarity and not intended to limit the scope of this invention. Changes or adjustments to their relative relationships, without substantially altering the technical content, should also be considered within the scope of this invention. Specific structures can be described with reference to the accompanying drawings of the patent application.
[0026] This utility model provides a battery-free inverter system. Please refer to [link / reference]. Figures 1 to 3 As shown, the battery-free inverter system includes a multi-input unit 100 for receiving DC or AC power, an inverter unit for converting DC power to AC power, a dual-output unit 200 for providing 120V AC output and 220V AC output, a current detection unit 300 for real-time detection of input and output current, a sampling unit 400 for acquiring input and output voltage and current signals, and a control unit 500. The multi-input unit 100 includes a photovoltaic input port PV+, a photovoltaic input port PV-, a mains input port IN-L, a mains input port IN-N, a generator input port GEN-L, and a generator input port GEN-N. The inverter unit is connected to the multi-input unit 100 and outputs dual AC voltages of 120V and 220V. The dual-output unit 200 is connected to the output terminal of the inverter unit and is connected to a 120V load and a 220V load, respectively. The current detection unit 300 includes several current transformers disposed in the multi-input unit 100 and the dual-output unit 200. The sampling unit 400 is connected to the current detection unit 300 and the multi-input unit 100. The control unit 500 is connected to the current detection unit 300 and the sampling unit 400.
[0027] The inverter unit includes a full-bridge inverter circuit composed of an insulated-gate bipolar transistor (IGBT) Q13, an IGBT Q14, an IGBT Q15, and an IGBT Q16, as well as a step-up transformer TX1. The inverter unit outputs 120V and 220V dual AC voltages through the full-bridge inverter circuit and the step-up transformer TX1. The dual-output unit 200 includes a 120V output port OUT120-L, a 120V output port OUT120-N, a 220V output port OUT220-L, and a 220V output port OUT220-N. The dual-output unit 200 is connected to a 120V load through the 120V output port OUT120-L and the 120V output port OUT120-N. The dual-output unit 200 is also connected to a 220V load through the 220V output port OUT220-L and the 220V output port OUT220-N. The current detection unit 300 includes shunt resistors R105 and R106 located at the photovoltaic input port PV-, a current transformer CT2 located at the mains input port IN-L, a current transformer CT1 located at the generator input port GEN-L, a current transformer CT4 located at the 120V output port OUT120-L, and a current transformer CT3 located at the 220V output port OUT220-L.
[0028] The control unit 500 is a central processing unit (CPU), and the CPU has multiple signal acquisition pins; The sampling unit 400 includes an AC voltage sampling circuit 410 connected to the AC input port IN-L and the AC input port IN-N, a generator voltage sampling circuit 420 connected to the generator input port GEN-L and the generator input port GEN-N, a photovoltaic current sampling circuit 430 connected to the photovoltaic input port PV-, a generator current sampling circuit 440 connected to the current transformer CT1, an AC current sampling circuit 450 connected to the current transformer CT2, a 220V output current sampling circuit 460 connected to the current transformer CT3, and a 120V output current sampling circuit 470 connected to the current transformer CT4. The mains voltage sampling circuit 410 is connected to the corresponding signal acquisition pin of the control unit 500 through a first signal conditioning circuit composed of operational amplifier U5A. The generator voltage sampling circuit 420 is connected to the corresponding signal acquisition pin of the control unit 500 through a second signal conditioning circuit composed of operational amplifier U6A. The photovoltaic current sampling circuit 430 is connected to the corresponding signal acquisition pin of the control unit 500 through a third signal conditioning circuit composed of operational amplifier U6C. The generator current sampling circuit 440 is connected to the corresponding signal acquisition pin of the control unit 500 through a fourth signal conditioning circuit composed of operational amplifier U9C. The conditioning circuit is connected to the corresponding signal acquisition pin of the control unit 500. The mains current sampling circuit 450 is connected to the corresponding signal acquisition pin of the control unit 500 through a fifth signal conditioning circuit composed of operational amplifier U8C. The 220V output current sampling circuit 460 is connected to the corresponding signal acquisition pin of the control unit 500 through a sixth signal conditioning circuit composed of operational amplifier U7C. The 120V output current sampling circuit 470 is connected to the corresponding signal acquisition pin of the control unit 500 through a seventh signal conditioning circuit composed of operational amplifier U5C. The control unit 500 is connected to the driving terminals of the insulated gate bipolar transistors Q13, Q14, Q15 and Q16 of the inverter unit, as well as the control terminals of the relays RY1 and RY2 in the multiplexer unit 100.
[0029] The photovoltaic input port PV+ and the photovoltaic input port PV- are sequentially connected to a surge protection varistor MOV1, a surge suppression diode D10, a filter capacitor CE3, a filter capacitor CE1, a filter capacitor CE2, a filter capacitor C43, and a filter capacitor C42.
[0030] The mains input port IN-L is connected to the battery-free inverter system via relay RY2, and the generator input port is connected to the battery-free inverter system via relay RY1.
[0031] The insulated gate bipolar transistors Q13 and Q16 of the inverter unit form a pair of bridge arms, and the insulated gate bipolar transistors Q14 and Q15 of the inverter unit form another pair of bridge arms. The primary winding of the step-up transformer TX1 is connected between the midpoints of the two pairs of bridge arms.
[0032] An output capacitor C45 is connected in parallel to the 120V output ports OUT120-L and OUT120-N, and an output capacitor C46 is connected in parallel to the 220V output ports OUT220-L and OUT220-N.
[0033] The operational amplifiers used in the first, second, third, fourth, fifth, sixth, and seventh signal conditioning circuits are of model TL074C.
[0034] The control unit 500 calculates and compares the relationship between the photovoltaic input power P1, the mains input power P2, the generator input power P3 and the 120V output power P4 and 220V output power P5 through the current detection unit 300 and the sampling unit 400 connected thereto, so as to control the closing and opening of the relays RY1 and RY2, thereby adjusting the power output of the inverter unit and realizing the working modes including photovoltaic power supply alone, photovoltaic and mains power supply, photovoltaic and generator power supply, and three-input power supply. Photovoltaic stand-alone power supply mode: When the control unit 500 detects through the sampling unit 400 that the photovoltaic input power P1 is greater than or equal to the sum of the 120V output load power P4 and the 220V output load power P5, i.e., P1≥P4+P5, the system enters the photovoltaic stand-alone power supply mode. In this mode, the control unit 500 controls relays RY2 and RY1 to remain in the open state, cutting off the mains power input and generator input. Photovoltaic DC power is input through the photovoltaic input ports PV+ and PV-, and then passed through the surge protector. After the input filtering and protection circuit consisting of resistor MOV1, surge suppression diode D10, and filter capacitors CE1, CE2, CE3, C42, and C43, the power is directly supplied to the inverter unit. The control unit 500 generates a PWM drive signal with a specific timing to control the full-bridge inverter circuit composed of insulated-gate bipolar transistors Q13, Q14, Q15, and Q16 to conduct alternately. Specifically, during the positive half-cycle, insulated-gate bipolar transistors Q13 and Q16 are controlled to conduct, and the current path is: from the photovoltaic input port PV+ to the insulated-gate bipolar transistor. Q13 is connected to the primary winding of the step-up transformer TX1, then to the insulated-gate bipolar transistor Q16, and finally to the photovoltaic input port PV-. During the negative half-cycle, insulated-gate bipolar transistors Q14 and Q15 are turned on, with the current path as follows: photovoltaic input port PV+ to insulated-gate bipolar transistor Q14, then to the primary winding of the step-up transformer TX1, then to insulated-gate bipolar transistor Q15, and finally to the photovoltaic input port PV-. After being stepped up and isolated by the step-up transformer TX1, the required 120V and 220V dual AC voltages are generated on its secondary winding, which are then transmitted via… The inverter bridge arm is supplied with 120V or 220V loads through 120V output ports OUT120-L and OUT120-N, and 220V output ports OUT220-L and OUT220-N, respectively. The current transformers CT3 and CT4 in the current detection unit 300 monitor the output current in real time. Once an overload or short circuit occurs, the sampling unit 400 feeds the signal back to the control unit 500, which can immediately shut off the drive signal of the inverter bridge arm to achieve rapid protection. Photovoltaic and mains power combined power supply mode: When the control unit 500 detects through the sampling unit 400 that the photovoltaic input power P1 is less than or equal to the sum of the 120V output load power P4 and the 220V output load power P5, i.e., P1≤P4+P5, if the system sets the mains power as a supplementary power source, it enters the photovoltaic and mains power combined power supply mode; the control unit 500 first calculates the power difference ΔP=(P4+P5)-P1, and then controls the relay RY2 to close, connecting the mains power; the mains power is supplied through the mains input port IN-L and the mains input port IN-N. The already closed relay RY2 is connected to the system; at this time, the photovoltaic input continues to provide power P1 through the inverter unit, while the insufficient power ΔP is directly supplemented by the mains power; the control unit 500 monitors the mains input current in real time through the current transformer CT2 and the corresponding mains current sampling circuit 450, and adjusts it through the algorithm so that the power P2 provided by the mains power dynamically matches ΔP, that is, maintains the relationship of P1+P2=P4+P5, and ensures a stable supply of load power; in this mode, the inverter unit mainly handles the conversion of photovoltaic DC power, and the mains power directly supplements the difference in power as a parallel power source; Photovoltaic and generator combined power supply mode: When the control unit 500 detects through the sampling unit 400 that the photovoltaic input power P1 is less than or equal to the total load demand power, i.e., P1≤P4+P5, and the system is in a scenario without mains power or the generator is set as a supplementary power source, it enters the photovoltaic and generator combined power supply mode; after the control unit 500 calculates the power gap ΔP=(P4+P5)-P1, it outputs a control signal to the generator start switch (not shown in the figure, which is a general existing technology) to automatically start the generator and control the relay RY1 to close, connecting the generator power supply; the AC power generated by the generator is connected to the system through the generator input port GEN-L, the generator input port GEN-N, and the closed relay RY1; similar to controlling the mains power supplement, the control unit 500 monitors the generator input current in real time through the current transformer CT1 and the corresponding generator current sampling circuit 440, and accurately controls the power P3 provided by the generator to meet the power balance condition P1+P3=P4+P5; the photovoltaic inverter and generator power supply work together, with the generator undertaking the supplementation of the power gap; Three-input combined power supply mode: In applications requiring extremely high power supply reliability, the system can simultaneously connect to three inputs: photovoltaic, mains power, and generator. The control unit 500 can preset priorities, such as setting mains power priority and generator hot backup. During normal operation, the system prioritizes the "photovoltaic and mains power combined power supply" mode. When the control unit 500 detects an abnormality in the mains input, such as a power outage or low voltage, it will immediately disconnect relay RY2 and simultaneously or after a delay, start the generator and close relay RY1, switching to the "photovoltaic and generator combined power supply" mode to achieve uninterrupted power supply. Conversely, if generator priority is preset, the operating logic is reversed. In this mode, the control unit 500 continuously monitors the numerical relationship between P1, P2 (or P3), P4, and P5 to ensure that the total input power matches the total output power (P1+P2=P4+P5 or P1+P3=P4+P5). Photovoltaic power is used to the maximum extent as a priority energy source, while mains power or generators serve as reliable backup power. The two are mutually exclusive or coordinated through relays to ensure that the system can still be powered by another backup power source when a single backup power source fails. The battery-free inverter system does not contain a battery, and the electrical energy received by the multi-input unit 100 is directly converted by the inverter unit and supplied to the dual-output unit 200.
[0035] It will be apparent to those skilled in the art that this invention is not limited to the details of the exemplary embodiments described above, and that it can be implemented in other specific forms without departing from the spirit or essential characteristics of this invention. Therefore, the embodiments should be considered illustrative and non-limiting in all respects, and the scope of this invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within this invention. No reference numerals in the claims should be construed as limiting the scope of the claims.
Claims
1. A battery-free inverter system, characterized in that, The battery-free inverter system includes a multi-input unit for receiving DC or AC power, an inverter unit for converting DC power to AC power, a dual-output unit for providing 120V AC output and 220V AC output, a current detection unit for real-time detection of input and output current, a sampling unit for acquiring input and output voltage and current signals, and a control unit. The multi-input unit includes a photovoltaic input port PV+, a photovoltaic input port PV-, a mains input port IN-L, a mains input port IN-N, a generator input port GEN-L, and a generator input port GEN-N. The inverter unit is connected to the multi-input unit and outputs dual AC voltages of 120V and 220V. The dual-output unit is connected to the output terminal of the inverter unit and is connected to a 120V load and a 220V load, respectively. The current detection unit includes several current transformers disposed in the multi-input unit and the dual-output unit. The sampling unit is connected to the current detection unit and the multi-input unit. The control unit is connected to the current detection unit and the sampling unit.
2. The battery-free inverter system according to claim 1, characterized in that, The inverter unit includes a full-bridge inverter circuit composed of an insulated-gate bipolar transistor (IGBT) Q13, an IGBT Q14, an IGBT Q15, and an IGBT Q16, as well as a step-up transformer TX1. The inverter unit outputs 120V and 220V dual AC voltages through the full-bridge inverter circuit and the step-up transformer TX1. The dual-output unit includes a 120V output port OUT120-L, a 120V output port OUT120-N, a 220V output port OUT220-L, and a 220V output port OUT220-N. The dual-output unit is connected to a 120V load through the 120V output port OUT120-L and the 120V output port OUT120-N. The dual-output unit is connected to a 220V load through the 220V output port OUT220-L and the 220V output port OUT220-N. The current detection unit includes shunt resistors R105 and R106 located at the photovoltaic input port PV-, a current transformer CT2 located at the mains input port IN-L, a current transformer CT1 located at the generator input port GEN-L, a current transformer CT4 located at the 120V output port OUT120-L, and a current transformer CT3 located at the 220V output port OUT220-L.
3. The battery-free inverter system according to claim 2, characterized in that, The control unit is a central processing unit (CPU), which has multiple signal acquisition pins. The sampling unit includes an AC voltage sampling circuit connected to the AC input port IN-L and the AC input port IN-N, a generator voltage sampling circuit connected to the generator input port GEN-L and the generator input port GEN-N, a photovoltaic current sampling circuit connected to the photovoltaic input port PV-, a generator current sampling circuit connected to the current transformer CT1, an AC current sampling circuit connected to the current transformer CT2, a 220V output current sampling circuit connected to the current transformer CT3, and a 120V output current sampling circuit connected to the current transformer CT4. The mains voltage sampling circuit is connected to the corresponding signal acquisition pin of the control unit through a first signal conditioning circuit composed of operational amplifier U5A; the generator voltage sampling circuit is connected to the corresponding signal acquisition pin of the control unit through a second signal conditioning circuit composed of operational amplifier U6A; the photovoltaic current sampling circuit is connected to the corresponding signal acquisition pin of the control unit through a third signal conditioning circuit composed of operational amplifier U6C; the generator current sampling circuit is connected to the corresponding signal acquisition pin of the control unit through a fourth signal conditioning circuit composed of operational amplifier U9C; the mains current sampling circuit is connected to the corresponding signal acquisition pin of the control unit through a fifth signal conditioning circuit composed of operational amplifier U8C; the 220V output current sampling circuit is connected to the corresponding signal acquisition pin of the control unit through a sixth signal conditioning circuit composed of operational amplifier U7C; and the 120V output current sampling circuit is connected to the corresponding signal acquisition pin of the control unit through a seventh signal conditioning circuit composed of operational amplifier U5C. The control unit is connected to the drive terminals of the insulated gate bipolar transistors Q13, Q14, Q15 and Q16 of the inverter unit, as well as the control terminals of the relays RY1 and RY2 in the multiple input unit.
4. The battery-free inverter system according to claim 3, characterized in that, The photovoltaic input port PV+ and the photovoltaic input port PV- are sequentially connected to a surge protection varistor MOV1, a surge suppression diode D10, a filter capacitor CE3, a filter capacitor CE1, a filter capacitor CE2, a filter capacitor C43, and a filter capacitor C42.
5. A battery-free inverter system according to claim 3, characterized in that, The mains input port IN-L is connected to the battery-free inverter system via relay RY2, and the generator input port is connected to the battery-free inverter system via relay RY1.
6. A battery-free inverter system according to claim 3, characterized in that, The insulated gate bipolar transistors Q13 and Q16 of the inverter unit form a pair of bridge arms, and the insulated gate bipolar transistors Q14 and Q15 of the inverter unit form another pair of bridge arms. The primary winding of the step-up transformer TX1 is connected between the midpoints of the two pairs of bridge arms.
7. A battery-free inverter system according to claim 3, characterized in that, An output capacitor C45 is connected in parallel to the 120V output ports OUT120-L and OUT120-N, and an output capacitor C46 is connected in parallel to the 220V output ports OUT220-L and OUT220-N.
8. A battery-free inverter system according to claim 3, characterized in that, The operational amplifiers used in the first, second, third, fourth, fifth, sixth, and seventh signal conditioning circuits are of model TL074C.
9. A battery-free inverter system according to claim 3, characterized in that, The control unit, through its connected current detection unit and sampling unit, calculates and compares the relationship between the photovoltaic input power P1, the mains input power P2, the generator input power P3, and the 120V output power P4 and the 220V output power P5 to control the opening and closing of the relays RY1 and RY2, thereby adjusting the power output of the inverter unit and realizing working modes including photovoltaic power supply alone, photovoltaic and mains power supply combined, photovoltaic and generator power supply combined, and three-input combined power supply.
10. A battery-free inverter system according to any one of claims 1 to 9, characterized in that, The battery-free inverter system does not contain a battery, and the electrical energy received by the multi-input unit is directly converted by the inverter unit and supplied to the dual-output unit.