Llc over-current hardware protection circuit
By simplifying the llc overcurrent protection circuit of photovoltaic inverters, using DC input, llc converter circuit, driver circuit, microprocessor and CT sampling, combining hardware and software protection, it quickly detects and seals the surge current, solving the problem of traditional protection loops with many nodes and long response delays, improving the safety of photovoltaic inverters and reducing costs.
Patent Information
- Application Number
- CN202422213266.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-09-10
- Publication Date
- 2025-07-08
- Estimated Expiration
- 2034-09-10
AI Technical Summary
The llc overcurrent protection loop nodes of traditional photovoltaic inverters have many llc overcurrent protection loops, long response delay, and cannot be protected quickly, which is prone to breakdown damage caused by inrush current.
It adopts DC input, llc converter circuit, driver circuit, microprocessor, hardware overcurrent comparison circuit and CT sampling, combined with hardware and software protection, simplifies loop nodes, quickly detect and seal the surge current through CT sampling, and the microprocessor controls the driver circuit to lock.
It realizes rapid protection, avoids MOS tube breakdown, improves the safety and reliability of photovoltaic inverters, and reduces the cost of use.
Smart Images
Figure CN223079944U_ABST
Abstract
Description
Technical Field
[0001] The utility model relates to the technical field of photovoltaic inverters, in particular to an LLC overcurrent hardware protection circuit. Background Technique
[0002] With the development of power supply industry technology, various power supply devices have flooded into ordinary people's homes. Especially in some places with poor power grids or no commercial power, photovoltaic inverters have become essential devices in life. Due to people's high dependence on them, it is very important to protect the inverters from damage. When users operate improperly or the inverter appears in other abnormal states, resulting in a short circuit at the input or output end, a huge surge current will appear inside the photovoltaic inverter, thus damaging the photovoltaic inverter. The LLC overcurrent protection link of traditional photovoltaic inverters uses the cooperation of LLC resonant current, Hall sampling, proportional operational amplifier circuit, hardware overcurrent comparison circuit and drive circuit to detect and protect the current. The protection loop nodes are relatively many, and at the same time, the response delay of Hall sampling and proportional operational amplifier circuit is relatively long. The LLC overcurrent protection loop delay time reaches the microsecond level. When facing surge current, it is impossible to achieve fast protection, and it is easy for MOS tubes to be broken down and damaged due to pulse current. In order to ensure the stability and reliability of photovoltaic inverters, it is necessary to improve the LLC overcurrent hardware protection circuit. Content of the Utility Model
[0003] The purpose of the utility model is to solve the technical problems put forward in the above background technique.
[0004] The utility model adopts the following technical scheme: an LLC overcurrent hardware protection circuit, including a DC input, an LLC converter circuit, a DC output, a drive circuit, a microprocessor, a hardware overcurrent comparison circuit and a CT sampling. One end of the DC input is connected to one end of the LLC converter circuit. One end of the LLC converter circuit is connected to one end of the DC output. The other end of the LLC converter circuit is connected to one end of the drive circuit. One end of the drive circuit is connected to one end of the microprocessor. The other end of the drive circuit is connected to one end of the hardware overcurrent comparison circuit. One end of the hardware overcurrent comparison circuit is connected to the other end of the microprocessor. The other end of the hardware overcurrent comparison circuit is connected to the CT sampling. Software overcurrent protection signals are connected to one ends of the drive circuit and the microprocessor respectively. Hardware overcurrent protection signals are connected to one ends of the drive circuit and the hardware overcurrent comparison circuit respectively. An LLC resonant current is connected to one end of the CT sampling.
[0005] Preferably, the microprocessor can lock the drive signal transmitted to the drive circuit. Here, it is convenient to control the drive circuit through the microprocessor.
[0006] Preferably, the LLC converter circuit includes a full-bridge conversion circuit of the primary winding, a boost transformer TX1, a resonant cavity, a rectification circuit of the secondary winding, and a resonant current sampling circuit. One end of the full-bridge conversion circuit of the primary winding is connected to a DC power supply V1. Inside the full-bridge conversion circuit of the primary winding, MOS transistors Q5, Q6, Q7, and Q8 are connected. One ends of the MOS transistors Q5, Q6, Q7, and Q8 are connected to one end of the boost transformer TX1 through the primary winding current Ip. The other end of the boost transformer TX1 is connected to a resonant cavity composed of a resonant inductor Lr, a resonant capacitor Cr, and an exciting inductor Lm. Here, the full-bridge conversion circuit of the primary winding can convert the DC power supply V1 into a high-frequency square wave.
[0007] Preferably, one end of the resonant capacitor Cr is connected to a rectification circuit of the secondary winding composed of MOS transistors Q5, Q6, Q7, and Q8. One end of the rectification circuit is connected to a DC power supply V2. The other end of the rectification circuit is connected to one end of the CT1 sampling current through the secondary winding current Is. The other end of the CT1 sampling current is connected to a rectification circuit composed of D1, D2, D3, and D4. One end of the rectification circuit is connected to R1. One end of R1 is connected to a voltage signal V3. Here, the boost transformer TX1 and the rectification circuit of the secondary winding facilitate the rectification of the square wave boosted by the boost transformer TX1 into the DC power supply V2.
[0008] Preferably, the hardware overcurrent comparison circuit includes an adjustable voltage division circuit composed of +3.3VA, R223, R225, and R227, a follower, a comparator circuit, and an overcurrent protection signal LLC-I-LMT-DSP. One end of the voltage division circuit is connected to a follower composed of an operational amplifier U14C. One end of the follower is connected to a comparator circuit. Here, the voltage division circuit and the follower ensure the stability of the transmission of the hardware-set comparison value.
[0009] Preferably, one end of the comparator circuit is connected to R76 and R202. The other end of the comparator circuit is connected to the overcurrent protection signal LLC-I-LMT-DSP. One end of the overcurrent protection signal LLC-LIMIT-PWM is connected to one end of the microprocessor. Here, the comparator circuit facilitates the comparison of the current values.
[0010] Compared with the prior art, the advantages and positive effects of the present utility model are as follows:
[0011] 1. In the present utility model, by providing a DC input, an LLC converter circuit, a DC output, a drive circuit, a microprocessor, a hardware overcurrent comparison circuit, a CT sampling, a software overcurrent protection signal, a hardware overcurrent protection signal, an LLC resonant current, a full-bridge conversion circuit, a step-up transformer TX1, a resonant cavity, a rectification circuit of the secondary winding, and a resonant current sampling circuit, the drive circuit can be controlled by the microprocessor. The full-bridge conversion circuit of the primary winding can conveniently convert the DC power supply V1 into a high-frequency square wave, the step-up transformer TX1 can conveniently step up the square wave, and the rectification circuit of the secondary winding can conveniently rectify the square wave stepped up by the step-up transformer TX1 into a DC power supply V2. The circuit structure is simple, and the microprocessor uses a combination of hardware and software to enable the LLC overcurrent hardware protection circuit to quickly protect it, improving the safety of the LLC overcurrent hardware protection circuit.
[0012] 2. In the present utility model, by providing a DC input, an LLC converter circuit, a DC output, a drive circuit, a microprocessor, a hardware overcurrent comparison circuit, and a CT sampling, the CT sampling changes the detection method of the traditional Hall sampling and proportional operational amplifier circuit, simplifies the loop nodes of the LLC overcurrent hardware protection circuit, and reduces the usage cost of the LLC overcurrent hardware protection circuit. Description of the Drawings
[0013] Figure 1 is a schematic diagram of an LLC overcurrent hardware protection circuit proposed by the present utility model;
[0014] Figure 2 is a circuit diagram of the LLC converter circuit in an LLC overcurrent hardware protection circuit proposed by the present utility model;
[0015] Figure 3 is a circuit diagram of the hardware overcurrent comparison circuit in an LLC overcurrent hardware protection circuit proposed by the present utility model;
[0016] Figure 4 is a circuit diagram of the drive circuit in an LLC overcurrent hardware protection circuit proposed by the present utility model.
[0017] Legend Explanation:
[0018] 1. DC input; 2. LLC converter circuit; 3. DC output; 4. Drive circuit; 5. Microprocessor; 6. Hardware overcurrent comparison circuit; 7. CT sampling; 8. Software overcurrent protection signal; 9. Hardware overcurrent protection signal; 10. LLC resonant current. Detailed Embodiment
[0019] In order to more clearly understand the above-mentioned purpose, features and advantages of the utility model, the utility model is further described below in conjunction with the accompanying drawings and embodiments. It should be noted that the embodiments of the present application and the features in the embodiments can be combined with each other without conflict.
[0020] In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention may also be implemented in other ways than those described herein. Therefore, the present invention is not limited to the specific embodiments of the following disclosure.
[0021] Embodiment 1
[0022] See also Figure 1-2 The utility model provides a technical solution: an LLC overcurrent hardware protection circuit, including a DC input 1, an LLC converter circuit 2, a DC output 3, a drive circuit 4, a microprocessor 5, a hardware overcurrent comparison circuit 6 and a CT sampling 7, one end of the DC input 1 is connected to one end of the LLC converter circuit 2, one end of the LLC converter circuit 2 is connected to one end of the DC output 3, the LLC converter circuit 2 includes a full-bridge conversion circuit of a primary winding, a boost transformer TX1, a resonant cavity, a rectifier circuit of a secondary winding and a resonant current sampling circuit, one end of the full-bridge conversion circuit of the primary winding is connected to a DC power supply V1, the inside of the full-bridge conversion circuit of the primary winding is connected to MOS tubes Q5, Q6, Q7 and Q8, one end of the MOS tubes Q5, Q6, Q7, Q8 is connected to the boost transformer TX1 through the Ip primary winding current One end of the step-up transformer TX1 is connected, the other end of the step-up transformer TX1 is connected to a resonant cavity composed of a resonant inductor Lr, a resonant capacitor Cr and an excitation inductor Lm, the DC power supply V1 is conveniently converted into a high-frequency square wave through the full-bridge conversion circuit of the primary winding, one end of the resonant capacitor Cr is connected to a rectifier circuit of a secondary winding composed of MOS tubes Q5, Q6, Q7 and Q8, one end of the rectifier circuit is connected to a DC power supply V2, the other end of the rectifier circuit is connected to one end of the CT1 sampling current through the Is secondary winding current, the other end of the CT1 sampling current is connected to a rectifier circuit composed of D1, D2, D3 and D4, one end of the rectifier circuit is connected to R1, one end of R1 is connected to a voltage signal V3, and the square wave boosted by the step-up transformer TX1 can be rectified into a DC power supply V2 through the rectifier circuit of the step-up transformer TX1 and the secondary winding.
[0023] See also Figure 1-4, the other end of the LLC converter circuit 2 is connected to one end of the drive circuit 4, one end of the drive circuit 4 is connected to one end of the microprocessor 5, and the microprocessor 5 can lock the drive signal transmitted to the drive circuit 4, facilitating the control of the drive circuit 4 through the microprocessor 5. The other end of the drive circuit 4 is connected to one end of the hardware overcurrent comparison circuit 6, one end of the hardware overcurrent comparison circuit 6 is connected to the other end of the microprocessor 5, the other end of the hardware overcurrent comparison circuit 6 is connected to the CT sampling 7. The hardware overcurrent comparison circuit 6 includes an adjustable voltage dividing circuit composed of +3.3VA, R223, R225, and R227, a follower, a comparator circuit, and an overcurrent protection signal LLC-I-LMT-DSP. One end of the voltage dividing circuit is connected to a follower composed of an operational amplifier U14C, one end of the follower is connected to a comparator circuit. The stability of the hardware-set comparison value transmission can be improved through the voltage dividing circuit and the follower. One end of the comparator circuit is connected to R76 and R202, and the other end of the comparator circuit is connected to the overcurrent protection signal LLC-I-LMT-DSP. One end of the overcurrent protection signal LLC-LIMIT-PWM is connected to one end of the microprocessor 5, facilitating the comparison of the current value through the comparator circuit.
[0024] Embodiment 2
[0025] Please refer to Figure 1 , both the drive circuit 4 and one end of the microprocessor 5 are connected to a software overcurrent protection signal 8, both the drive circuit 4 and one end of the hardware overcurrent comparison circuit 6 are connected to a hardware overcurrent protection signal 9, and one end of the CT sampling 7 is connected to an LLC resonant current 10. By means of the CT sampling 7, the detection method of the traditional Hall sampling and proportional operational amplifier circuit is changed, and at the same time, the loop nodes of the LLC overcurrent hardware protection circuit are simplified, reducing the use cost of the LLC overcurrent hardware protection circuit.
[0026] Working principle: During the use of the LLC overcurrent hardware protection circuit, first, the LLC resonant current 10 passing through the LLC converter circuit 2 can be detected through the CT sampling 7. When this current exceeds the hardware protection setting value, the hardware overcurrent protection signal 9 will be triggered, thus quickly closing the drive circuit 4 of the LLC converter circuit 2 to block the surge current. Then, after the microprocessor 5 receives the software overcurrent protection signal 8, the drive circuit 4 is locked, causing the LLC converter circuit 2 to stop working. Through the combination of hardware and software, the LLC overcurrent hardware protection circuit can quickly protect it, avoiding the MOS tube from being damaged due to pulsed current and improving the safety of the LLC overcurrent hardware protection circuit.
[0027] The above are only the preferred embodiments of the present utility model, and are not intended to limit the present utility model in other forms. Any person skilled in the art may use the technical content disclosed above to make changes or modifications into equivalent embodiments with equivalent changes and apply them to other fields. However, any simple modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present utility model without departing from the technical solution content of the present utility model still fall within the protection scope of the technical solution of the present utility model.
Claims
1. An LLC overcurrent hardware protection circuit, characterized in that: It includes a DC input (1), an LLC converter circuit (2), a DC output (3), a drive circuit (4), a microprocessor (5), a hardware overcurrent comparison circuit (6) and a CT sampling (7). One end of the DC input (1) is connected to one end of the LLC converter circuit (2). One end of the LLC converter circuit (2) is connected to one end of the DC output (3). The other end of the LLC converter circuit (2) is connected to one end of the drive circuit (4). One end of the drive circuit (4) is connected to one end of the microprocessor (5). The other end of the drive circuit (4) is connected to one end of the hardware overcurrent comparison circuit (6). One end of the hardware overcurrent comparison circuit (6) is connected to the other end of the microprocessor (5). The other end of the hardware overcurrent comparison circuit (6) is connected to the CT sampling (7). Software overcurrent protection signals (8) are connected to one ends of both the drive circuit (4) and the microprocessor (5). Hardware overcurrent protection signals (9) are connected to one ends of both the drive circuit (4) and the hardware overcurrent comparison circuit (6). An LLC resonant current (10) is connected to one end of the CT sampling (7).
2. The LLC overcurrent hardware protection circuit according to claim 1, wherein: The microprocessor (5) can lock the drive signal transmitted to the drive circuit (4).
3. The LLC overcurrent hardware protection circuit according to claim 1, characterized in that: The LLC converter circuit (2) includes a full-bridge conversion circuit of the primary winding, a boost transformer TX1, a resonant cavity, a rectification circuit of the secondary winding and a resonant current sampling circuit. One end of the full-bridge conversion circuit of the primary winding is connected to a DC power supply V1. MOS transistors Q5, Q6, Q7 and Q8 are internally connected to the full-bridge conversion circuit of the primary winding. One ends of the MOS transistors Q5, Q6, Q7, Q8 are connected to one end of the boost transformer TX1 through the primary winding current Ip. The other end of the boost transformer TX1 is connected to a resonant cavity composed of a resonant inductor Lr, a resonant capacitor Cr and an exciting inductor Lm.
4. The LLC overcurrent hardware protection circuit according to claim 3, characterized in that: One end of the resonant capacitor Cr is connected to a rectification circuit composed of MOS transistors Q5, Q6, Q7, Q8. One end of the rectification circuit is connected to a DC power supply V2. The other end of the rectification circuit is connected to one end of the CT1 sampling current through the secondary winding current Is. The other end of the CT1 sampling current is connected to a rectification circuit composed of D1, D2, D3, D4. One end of the rectification circuit is connected to R1. One end of R1 is connected to a voltage signal V3.
5. The LLC overcurrent hardware protection circuit according to claim 1, characterized in that: The hardware overcurrent comparison circuit (6) includes an adjustable voltage division circuit composed of +3.3VA, R223, R225 and R227, a follower, a comparator circuit and an overcurrent protection signal LLC-I-LMT-DSP. One end of the voltage division circuit is connected to a follower composed of an operational amplifier U14C. One end of the follower is connected to the comparator circuit.
6. The LLC overcurrent hardware protection circuit according to claim 5, characterized in that: One end of the comparator circuit is connected to R76 and R202. The other end of the comparator circuit is connected to the overcurrent protection signal LLC-I-LMT-DSP. One end of the overcurrent protection signal LLC-LIMIT-PWM is connected to one end of the microprocessor (5).