Detection method for preventing and coping with MPPT single tube failure

Abstract

The invention discloses a detection method for preventing and coping with failure of MPPT (Maximum Power Point Tracking) single tubes, which comprises the following steps of: replacing a single tube in an MPPT circuit with a plurality of single tubes connected in parallel, amplifying and converting a current signal of an IGBT (Insulated Gate Bipolar Translator) into a voltage signal through a sampling circuit, and detecting current output signals of the plurality of single tubes; comparing, selecting and amplifying the plurality of single-tube current output signals in sequence to obtain a third current output signal; performing in-phase addition on the plurality of single-tube current output signals to obtain a fourth current output signal; the third current output signal and the fourth current output signal are compared, a logic signal is output to a DSP, the DSP controls the IGBT by generating a PWM signal and combining a driving circuit, and the effect of effectively preventing and coping with the failure of the parallel IGBT single tube is achieved. According to the invention, the state of the single tube is monitored through the sampling circuit, the comparator, the DSP and other devices, the MPPT operation state is adjusted according to the current state of the single tube, the benefit maximization of the multi-path MPPT circuit is realized, and the fault occurrence rate is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of circuit detection, and particularly to a detection method for preventing and coping with the failure of a single tube in an MPPT. Background Art

[0002] In an inverter circuit, due to considerations of performance or cost, it is often necessary to use single tubes in parallel to withstand a larger current. The most likely problem with parallel IGBTs is current imbalance. Due to current imbalance, there may be a problem that the current of one or more single tubes IGBT exceeds the standard, which may further lead to the damage of the single tube; for the parallel IGBTs used in the MPPT circuit, the damage of a single tube often causes the failure of this MPPT circuit, and may even cause the failure of the entire machine. For manufacturers, they hope that the machine can operate as stably and efficiently as possible in any situation, provide the maximum power generation efficiency, and reduce maintenance costs. Summary of the Invention

[0003] Based on this, in order to solve the problem of the failure of the MPPT circuit caused by the damage of a single tube in the prior art, the present invention provides a detection method for preventing and coping with the failure of a single tube in an MPPT.

[0004] The present invention provides a detection method for preventing and coping with the failure of a single tube in an MPPT, including:

[0005] Using multiple parallel single tubes to replace the single tube in the MPPT circuit, and amplifying and converting the current signal of the IGBT into a voltage signal through a sampling circuit to realize the detection of the current output signals of multiple single tubes;

[0006] Comparing, selecting, and amplifying the current output signals of the multiple single tubes in sequence to obtain a third current output signal;

[0007] Adding the current output signals of the multiple single tubes in phase to obtain a fourth current output signal;

[0008] Comparing the third current output signal and the fourth current output signal, and outputting a logic signal to the DSP. The DSP controls the IGBT by generating a PWM signal and combining with a drive circuit to effectively prevent and cope with the failure of a single tube in parallel IGBTs.

[0009] The current output signals of the multiple single tubes include a first current output signal and a second current output signal.

[0010] The operation of comparing the current output signals of the multiple single tubes includes

[0011] The signal comparison module uses a comparator to compare the first current output signal and the second current output signal. The first current output signal is the signal source of the non-inverting input terminal of the comparator, and the second current output signal is the signal source of the inverting input terminal of the comparator. If the first current output signal is greater than the second current output signal, the output terminal of the comparator outputs a high level; otherwise, the output terminal of the comparator outputs a low level.

[0012] When the signal selection module receives a high level from the signal comparison module, the signal selection module outputs the first current output signal. When the signal selection module receives a low level from the signal comparison module, the signal selection module outputs the second current output signal.

[0013] The signal selection module includes a first NOT gate, a second NOT gate, a first CMOS transmission gate, and a second CMOS transmission gate. The input terminal of the first NOT gate is electrically connected to the output terminal of the signal comparison module. The output terminal of the first NOT gate is electrically connected to the input terminal of the second NOT gate. The output terminal of the first NOT gate is also electrically connected to the complementary control signal terminal of the first CMOS transmission gate and the control signal terminal of the second CMOS transmission gate. The output terminal of the second NOT gate is electrically connected to the control signal terminal of the first CMOS transmission gate and the complementary control signal terminal of the second CMOS transmission gate. The first current output signal is the input signal source of the first CMOS transmission gate, and the second current output signal is the input signal source of the second CMOS transmission gate. The output terminals of the first CMOS transmission gate and the second CMOS transmission gate are connected to the signal amplification module;

[0014] The level signal output by the signal comparison module is inverted by the first NOT gate and inverted again by the second NOT gate;

[0015] When the complementary control signal terminal of the first CMOS transmission gate is at a low level and the control signal terminal is at a high level, the first current output signal is allowed to be transmitted from the input terminal to the output terminal of the first CMOS transmission gate. When the complementary control signal terminal of the second CMOS transmission gate is at a low level and the control signal terminal is at a high level, the second current output signal is allowed to be transmitted from the input terminal to the output terminal of the second CMOS transmission gate.

[0016] The signal amplification module amplifies the output signal of the signal selection module times, that is, the third current output signal is , where represents the feedback resistor, represents the gain resistor, represents the first current output signal, represents the second current output signal.

[0017] The fourth current output signal is 。

[0018] Comparing the third current output signal and the fourth current output signal and outputting a logic signal to the DSP specifically includes

[0019] Comparing with and outputting a logic signal to the DSP;

[0020] If then output a high level to the DSP,

[0021] If then output a low level to the DSP.

[0022] Beneficial effects: The present invention realizes the monitoring of the single-tube state through devices such as a sampling circuit, a comparator, and a DSP, adjusts the MPPT operating state according to the single-tube current state, maximizes the benefits of the multi-path MPPT circuit, and reduces the failure rate.

[0023] It should be understood that the content described in this part is not intended to identify the key or important features of the embodiments of the present invention, nor is it used to limit the scope of the present invention. Other features of the present invention will become easily understood through the following description. Description of the Drawings

[0024] The drawings are used to better understand the present solution and do not constitute a limitation to the present invention. Among them:

[0025] Figure 1 is a schematic diagram of a dual-tube parallel replacement single-tube MPPT circuit provided by the present invention;

[0026] Figure 2 is a schematic diagram of a sampling circuit provided by the present invention;

[0027] Figure 3 is a schematic diagram of an arithmetic comparison circuit provided by the present invention. Detailed Embodiments

[0028] The following makes an illustration of the exemplary embodiments of the present invention in conjunction with the drawings. Various details of the embodiments of the present invention are included to facilitate understanding, and they should be considered merely exemplary. Therefore, those of ordinary skill in the art should recognize that various changes and modifications can be made to the embodiments described herein without departing from the scope and spirit of the present invention. Similarly, for clarity and conciseness, the description of well-known functions and structures is omitted below.

[0029] The present invention provides a detection method for preventing and coping with MPPT single-tube failure, including:

[0030] S1: Replace the single transistor in the MPPT circuit with multiple parallel single transistors, and amplify and convert the current signal of the IGBT into a voltage signal through a sampling circuit to detect the current output signals of multiple single transistors (as shown in Figure 1 、 2 ). It should be noted that:

[0031] The current output signals of the multiple single transistors include a first current output signal and a second current output signal.

[0032] As shown in Figure 2 , the sampling circuit consists of components such as a sampling resistor, an input resistor, a filter capacitor, an operational amplifier, a gain resistor, and an output resistor. By adjusting the ratio of the gain resistor to the input resistor, a small current signal can be converted into an appropriate voltage signal to achieve current sampling of the power device;

[0033] S2: Compare, select, and amplify the current output signals of the multiple single transistors in sequence to obtain a third current output signal (as shown in Figure 3 ). It should be noted that:

[0034] The operation of comparing the current output signals of the multiple single transistors includes:

[0035] The signal comparison module 100 uses a comparator to compare the first current output signal and the second current output signal. The first current output signal is the signal source at the non-inverting input terminal of the comparator, and the second current output signal is the signal source at the inverting input terminal of the comparator. If the first current output signal is greater than the second current output signal, the output terminal of the comparator outputs a high level; otherwise, the output terminal of the comparator outputs a low level.

[0036] When the signal selection module 200 receives a high level from the signal comparison module 100, the signal selection module 200 outputs the first current output signal. When the signal selection module 200 receives a low level from the signal comparison module 100, the signal selection module 200 outputs the second current output signal.

[0037] The signal selection module 200 includes a first NOT gate, a second NOT gate, a first CMOS transmission gate, and a second CMOS transmission gate. The input end of the first NOT gate is electrically connected to the output end of the signal comparison module 100. The output end of the first NOT gate is electrically connected to the input end of the second NOT gate. The output end of the first NOT gate is also electrically connected to the complementary control signal end of the first CMOS transmission gate and the control signal end of the second CMOS transmission gate. The output end of the second NOT gate is electrically connected to the control signal end of the first CMOS transmission gate and the complementary control signal end of the second CMOS transmission gate. The first current output signal is the input signal source of the first CMOS transmission gate, and the second current output signal is the input signal source of the second CMOS transmission gate. The output ends of the first CMOS transmission gate and the second CMOS transmission gate are connected to the signal amplification module 300;

[0038] The level signal output by the signal comparison module 100 is inverted through the first NOT gate and inverted again through the second NOT gate;

[0039] When the complementary control signal end of the first CMOS transmission gate is at a low level and the control signal end is at a high level, the first current output signal is allowed to be transmitted from the input end to the output end of the first CMOS transmission gate; when the complementary control signal end of the second CMOS transmission gate is at a low level and the control signal end is at a high level, the second current output signal is allowed to be transmitted from the input end to the output end of the second CMOS transmission gate.

[0040] The main functions of the signal comparison module 100 and the signal selection module 200 are to select the larger signal from the first current output signal and the second current output signal , which is equivalent to an analog switch; the first current output signal is compared with the second current output signal . If the first current output signal is greater than the second current output signal signal, the comparator outputs a high level, otherwise it outputs a low level; when the signal selection module 200 receives a high level signal, it will output the first current output signal . When the signal selection module 200 receives a low level signal, it will output the second current output signal .

[0041] The signal amplification module 300 amplifies the output signal of the signal selection module 200 times, that is, the third current output signal is , where represents the feedback resistor, represents the gain resistor, represents the first current output signal, Represents the second current output signal.

[0042] S3: In-phase add the multiple single-tube current output signals to obtain a fourth current output signal. It should be noted that:

[0043] The fourth current output signal is .

[0044] S4: Compare the third current output signal and the fourth current output signal, and output a logic signal to the DSP. The DSP controls the IGBT by generating a PWM signal and combining with a drive circuit to effectively prevent and handle the failure of parallel IGBT single tubes. It should be noted that:

[0045] The operation of comparing the third current output signal and the fourth current output signal and outputting a logic signal to the DSP specifically includes,

[0046] Compare with , and output a logic signal to the DSP;

[0047] If , then output a high level to the DSP,

[0048] If , then output a low level to the DSP.

[0049] By adjusting the resistance value of , the sensitivity of the circuit to the uneven current sharing of parallel single tubes can be adjusted, so as to realize the diversification of the functions of the circuit.

[0050] Taking the actual double-tube parallel replacement of the single-tube MPPT circuit as an example, if it is desired to detect and handle the failure of the MPPT single tube, assuming that the Q1 single tube is open-circuited and fails, then is 0. At this time, all the current of this path is borne by Q2, ; adjust the resistance value of to make , then the third current output signal is , and the fourth current output signal is , , output a high level. When the DSP receives the high-level signal, the maximum current value of this path of MPPT can be limited to the preset single-tube current safety area;

[0051] If you want to prevent the failure of a single MPPT tube, it can also be achieved through this circuit. As mentioned before, the failure of parallel single tubes is mostly caused by uneven current sharing. Taking the parallel connection of two tubes as an example, the maximum current of a single MPPT circuit is designed to be 80A. Q1 and Q2 are single tubes with a voltage of 1200V and a current of 50A. When this MPPT circuit operates at the maximum current, the actual current of Q1 is 50A, and the actual current of Q2 is 30A. The sampling circuit amplifies these two current signals by the same factor of X, then

[0052] ;

[0053] ;

[0054] ;

[0055] Adjust and resistance values to make , then the third current output signal is , the fourth current output signal is , , output a high level. When the DSP receives the high-level signal, it can limit the maximum current of this MPPT circuit to the preset safe area of the single-tube current;

[0056] The number of branch circuits can be adjusted according to the number of parallel single tubes, so as to realize the function of preventing and coping with single-tube failure in the multi-tube parallel MPPT circuit. In the string inverter, this circuit can make each MPPT work at the set maximum current point as much as possible without leaving the safe area, ensuring both the stability of the equipment and the MPPT efficiency of the equipment;

[0057] By this method, the failure of parallel IGBT single tubes can be effectively prevented and coped with, improving the operation stability of the machine.

[0058] The above is only the specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions within the technical scope disclosed in the present invention should be covered by the protection scope of the present invention. Therefore, the protection scope of the present invention should be subject to the protection scope of the claims.

Claims

1. A detection method for preventing and coping with the failure of a single MPPT tube, characterized in that, Including: Using multiple parallel single transistors to replace the single transistor in the MPPT circuit, and amplifying and converting the current signal of the IGBT into a voltage signal through a sampling circuit to realize the detection of the current output signals of multiple single transistors; Comparing, selecting, and amplifying the current output signals of the multiple single transistors in sequence to obtain a third current output signal; Adding the current output signals of the multiple single transistors in phase to obtain a fourth current output signal; Comparing the third current output signal and the fourth current output signal, and outputting a logic signal to the DSP. The DSP controls the IGBT by generating a PWM signal and combining with a drive circuit to effectively prevent and handle the failure of the parallel IGBT single transistors.

2. The detection method for preventing and coping with the failure of a single MPPT tube according to claim 1, characterized in that: The current output signals of the multiple single transistors include a first current output signal and a second current output signal.

3. A detection method for preventing and coping with the failure of a single MPPT tube according to claim 2, characterized in that: The operation of comparing the current output signals of the multiple single transistors includes The signal comparison module uses a comparator to compare the first current output signal and the second current output signal. The first current output signal is the signal source of the non-inverting input terminal of the comparator, and the second current output signal is the signal source of the inverting input terminal of the comparator. If the first current output signal is greater than the second current output signal, the output terminal of the comparator outputs a high level; otherwise, the output terminal of the comparator outputs a low level.

4. The detection method for preventing and coping with the failure of a single MPPT tube according to claim 3, characterized in that: When the signal selection module receives a high level from the signal comparison module, the signal selection module outputs the first current output signal. When the signal selection module receives a low level from the signal comparison module, the signal selection module outputs the second current output signal.

5. A detection method for preventing and coping with the failure of a single tube in MPPT according to claim 4, characterized in that: The signal selection module includes a first NOT gate, a second NOT gate, a first CMOS transmission gate, and a second CMOS transmission gate. The input terminal of the first NOT gate is electrically connected to the output terminal of the signal comparison module. The output terminal of the first NOT gate is electrically connected to the input terminal of the second NOT gate. The output terminal of the first NOT gate is also electrically connected to the complementary control signal terminal of the first CMOS transmission gate and the control signal terminal of the second CMOS transmission gate. The output terminal of the second NOT gate is electrically connected to the control signal terminal of the first CMOS transmission gate and the complementary control signal terminal of the second CMOS transmission gate. The first current output signal is the input signal source of the first CMOS transmission gate, and the second current output signal is the input signal source of the second CMOS transmission gate. The output terminals of the first CMOS transmission gate and the second CMOS transmission gate are connected to the signal amplification module; The level signal output by the signal comparison module undergoes signal inversion through the first NOT gate and undergoes signal inversion again through the second NOT gate; When the complementary control signal terminal of the first CMOS transmission gate is at a low level and the control signal terminal is at a high level, it allows the first current output signal to be transmitted from the input terminal to the output terminal of the first CMOS transmission gate. When the complementary control signal terminal of the second CMOS transmission gate is at a low level and the control signal terminal is at a high level, it allows the second current output signal to be transmitted from the input terminal to the output terminal of the second CMOS transmission gate.

6. The detection method for preventing and coping with the failure of a single MPPT tube according to claim 5, characterized in that: The signal amplification module amplifies the output signal of the signal selection module by a factor of, that is, the third current output signal is , where represents the feedback resistor, represents the gain resistor, represents the first current output signal, represents the second current output signal.

7. A detection method for preventing and coping with the failure of a single MPPT tube according to claim 6, characterized in that: The fourth current output signal is .

8. A detection method for preventing and coping with the failure of a single MPPT tube according to claim 7, characterized in that: The operation of comparing the third current output signal and the fourth current output signal and outputting a logic signal to the DSP specifically includes Compare with and output a logic signal to the DSP; If , output a high level to the DSP If , then output a low level to the DSP.

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