Method and apparatus for input voltage elimination of energy conversion system, storage medium

Abstract

This application discloses a method, apparatus, and storage medium for eliminating input voltage in an energy conversion system. The energy conversion system includes a boost circuit. The method includes: determining that there is no energy input at the input terminal; obtaining the maximum leakage power of the diode in the boost circuit; and adjusting the frequency or duty cycle of the drive signal of the switching transistor in the boost circuit so that the input power at the input terminal is less than or equal to the maximum leakage power. The voltage elimination method of this application can avoid power loss and significant temperature increases in the energy-consuming resistor, reduce the size of the equipment, and improve the reliability of the system.

Description

Technical Field

[0001] This application relates to the field of energy conversion technology, and in particular to a method for eliminating input voltage in an energy conversion system, a device for eliminating input voltage in an energy conversion system, a computer-readable storage medium, and a controller. Background Technology

[0002] Energy conversion systems with photovoltaic (PV) input typically employ a boost converter circuit at the PV input terminal. When the PV voltage is sufficiently high, it is bypassed directly; when the PV voltage is insufficient, the boost converter function is activated. Therefore, this circuit can adapt to a relatively wide range of PV input voltages. This circuit contains a diode connecting the PV input terminal to the internal DC bus. When the internal DC bus has an operating voltage but the PV input terminal has no input or is floating, this diode will exhibit reverse leakage current, charging the capacitor at the PV input terminal and causing the PV input voltage to gradually increase. If this reverse leakage current is not addressed, the PV input port will become energized, causing the control system to mistakenly believe that a PV input is present, thus executing incorrect commands.

[0003] Currently, most solutions for addressing the reverse leakage current of this diode involve connecting a resistive load between the positive and negative terminals of the photovoltaic input to dissipate the diode's reverse leakage current. However, this method has some drawbacks. The diode's datasheet indicates that when the junction temperature reaches 125°C, the typical reverse leakage current is 1.2mA. Assuming the resistive load clamps the reverse leakage current of the diode with a voltage of Vx, under these conditions, if Vx is set to 36V, the resistance of the resistive load would be 36 / 1.2 = 30kΩ. Then, under normal photovoltaic input conditions, assuming a maximum input voltage of 1000V, the power dissipation across this resistive load would be 1000*1000 / 30kΩ = 33.3W. Therefore, this method, on the one hand, will impair the photovoltaic input power; on the other hand, this power dissipation will lead to significant heat generation, affecting the system's reliability. Summary of the Invention

[0004] This application aims to at least partially solve one of the technical problems in the related art. Therefore, the first objective of this application is to propose a method for eliminating input voltage in an energy conversion system. This method determines that there is no energy input at the input terminal, obtains the maximum leakage power of the diode in the boost circuit, and adjusts the frequency or duty cycle of the drive signal of the switching transistor in the boost circuit so that the input power at the input terminal is less than or equal to the maximum leakage power. This eliminates the need for a power-consuming resistor, avoiding power loss and significant temperature increases associated with power-consuming resistors, reducing the size of the equipment, and improving the reliability of the system.

[0005] The second objective of this application is to provide an input voltage elimination device for an energy conversion system.

[0006] The third objective of this application is to provide a computer-readable storage medium.

[0007] The fourth objective of this application is to propose a controller.

[0008] To achieve the above objectives, a first aspect of this application proposes a method for eliminating input voltage in an energy conversion system, the energy conversion system including a boost circuit, the method comprising: determining that there is no energy input at the input terminal; obtaining the maximum leakage power of the diode in the boost circuit; and adjusting the frequency or duty cycle of the drive signal of the switching transistor in the boost circuit so that the input power at the input terminal is less than or equal to the maximum leakage power.

[0009] According to the input voltage elimination method of the energy conversion system in this application embodiment, it is determined that there is no energy input at the input terminal. The maximum leakage power of the diode in the boost circuit is obtained, and the frequency or duty cycle of the drive signal of the switching transistor in the boost circuit is adjusted so that the input power at the input terminal is less than or equal to the maximum leakage power. Therefore, this method can avoid power loss and significant temperature increase of the energy-consuming resistor, reduce the size of the equipment, and improve the reliability of the system.

[0010] In addition, the input voltage elimination method of the energy conversion system according to the above embodiments of this application may also have the following additional technical features:

[0011] According to one embodiment of this application, adjusting the frequency of the drive signal for the switching transistor in the boost circuit includes: obtaining the peak current of the inductor in the boost circuit and the on-time of the switching transistor; obtaining the freewheeling time of the diode when the switching transistor is in the off state; determining the minimum off-time of the switching transistor based on the equality relationship between the discharge power of the capacitor in the boost circuit and the maximum leakage power, and the freewheeling time; and adjusting the frequency of the drive signal based on the on-time of the switching transistor and the minimum off-time.

[0012] According to one embodiment of this application, adjusting the duty cycle of the drive signal for the switching transistor in the boost circuit includes: obtaining the peak current of the inductor in the boost circuit and the on-time of the switching transistor; obtaining the freewheeling time of the diode when the switching transistor is in the off state; determining the maximum on-time of the switching transistor based on the equality relationship between the discharge power of the capacitor and the maximum leakage power in the boost circuit, the freewheeling time, and the pulse period of the drive signal; and adjusting the duty cycle of the drive signal based on the maximum on-time of the switching transistor and the pulse period.

[0013] According to one embodiment of this application, obtaining the freewheeling time of the diode includes: obtaining the work done by the input voltage and the work done by the output voltage at the input terminal, wherein the work done by the input voltage is used to characterize the work done by the input voltage on the inductor, and the work done by the output voltage is used to characterize the work done by the boost circuit on the load; and determining the freewheeling time of the diode based on the equality relationship between the work done by the input voltage and the work done by the output voltage.

[0014] According to one embodiment of this application, the work done by the input voltage, the work done by the output voltage, and the freewheeling time of the diode are obtained by the following formulas:

[0015] P1 = 1 / 2 * V PV *IL max *(T on +T d )

[0016] P2 = 1 / 2 * V dc *IL max *T d

[0017] P1 = P2

[0018] T d =V PV *T on / (V dc -V PV )

[0019] Wherein, P1 represents the work done by the input voltage, P2 represents the work done by the output voltage, and V PV IL represents the input voltage. max V represents the peak current of the inductor. dc T represents the DC bus voltage at the output of the boost circuit. on T represents the on-time of the switching transistor. d This indicates the freewheeling time of the diode.

[0020] According to one embodiment of this application, obtaining the maximum leakage power of the diode in the boost circuit includes: obtaining the DC bus voltage at the output terminal of the boost circuit and the maximum reverse leakage current of the diode; and determining the maximum leakage power based on the product between the DC bus voltage and the maximum reverse leakage current.

[0021] According to one embodiment of this application, the discharge power of the capacitor is obtained by the following formula:

[0022] P PV =1 / 2*IL max *(T on +Td )*V PV / (T on +T off )

[0023] Among them, P PV The discharge power of the capacitor is represented by IL. max T represents the peak current of the inductor. on T represents the on-time of the switching transistor. d V represents the freewheeling time of the diode. PV T represents the input terminal voltage. off This indicates the turn-off time of the switching transistor.

[0024] According to one embodiment of this application, determining that there is no power input at the input terminal includes: obtaining the current value of the inductor in the boost circuit and the input terminal voltage; determining the input power of the input terminal based on the current value and the input terminal voltage; and determining that there is no power input at the input terminal if the input power at the input terminal is less than a preset power threshold and continues for a preset time.

[0025] According to one embodiment of this application, the method further includes: determining that there is energy access at the input terminal when the input power at the input terminal is greater than the maximum leakage power.

[0026] To achieve the above objectives, a second aspect of this application provides an input voltage elimination device for an energy conversion system. The energy conversion system includes a boost circuit, and the device includes: a determining module for determining that there is no energy input at the input terminal; an acquiring module for acquiring the maximum leakage power of the diode in the boost circuit; and an adjusting module for adjusting the frequency or duty cycle of the drive signal of the switching transistor in the boost circuit so that the input power at the input terminal is less than or equal to the maximum leakage power.

[0027] According to the energy conversion system input voltage elimination device of this application embodiment, a determining module is used to determine that there is no energy input at the input terminal, an acquiring module is used to acquire the maximum leakage power of the diode in the boost circuit, and an adjusting module is used to adjust the frequency or duty cycle of the drive signal of the switching transistor in the boost circuit so that the input power at the input terminal is less than or equal to the maximum leakage power. Therefore, this device can avoid power loss and significant temperature increase of the energy-consuming resistor, reduce the size of the equipment, and improve the reliability of the system.

[0028] To achieve the above objectives, a third aspect of this application provides a computer-readable storage medium storing a program that, when executed by a processor, implements the above-described method for eliminating the input voltage of an energy conversion system.

[0029] The computer-readable storage medium according to the embodiments of this application implements the above-described input voltage elimination method of the energy conversion system during execution, which can avoid power loss and significant temperature rise of the energy-consuming resistor, reduce the size of the device, and improve the reliability of the system.

[0030] To achieve the above objectives, a controller is proposed in the fourth aspect of this application, including a memory, a processor, and a program stored in the memory and executable on the processor. When the processor executes the program, it implements the above-described method for eliminating the input voltage of the energy conversion system.

[0031] According to the controller in the embodiments of this application, by executing the above-described input voltage elimination method of the energy conversion system, the power loss and temperature rise of the energy-consuming resistor can be avoided, the size of the device can be reduced, and the reliability of the system can be improved.

[0032] Additional aspects and advantages of this application 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 this application. Attached Figure Description

[0033] Figure 1 This is a flowchart of an input voltage elimination method for an energy conversion system according to an embodiment of this application;

[0034] Figure 2 This is a schematic diagram of the boost circuit of the energy conversion system according to an embodiment of this application;

[0035] Figure 3 This is a waveform diagram of the switching transistor drive signal according to an embodiment of this application;

[0036] Figure 4 This is a schematic diagram of the waveform of the inductor current according to an embodiment of this application;

[0037] Figure 5 A flowchart illustrating an input voltage elimination method for an energy conversion system according to a specific example of this application;

[0038] Figure 6 This is a block diagram of the input voltage elimination device of an energy conversion system according to an embodiment of this application;

[0039] Figure 7 This is a block diagram of a controller according to an embodiment of this application. Detailed Implementation

[0040] The embodiments of this application are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain this application, and should not be construed as limiting this application.

[0041] The following description, with reference to the accompanying drawings, outlines the input voltage elimination method, input voltage elimination device, computer-readable storage medium, and controller for an energy conversion system according to embodiments of this application.

[0042] Figure 1 This is a flowchart of an input voltage elimination method for an energy conversion system according to an embodiment of this application.

[0043] like Figure 1 As shown, the input voltage elimination method of the energy conversion system in this application embodiment may include the following steps:

[0044] S1 indicates that there is no power input at the input terminal.

[0045] S2, obtain the maximum leakage power of the diode in the boost circuit.

[0046] S3 adjusts the frequency or duty cycle of the drive signal for the switching transistor in the boost circuit so that the input power at the input terminal is less than or equal to the maximum leakage power.

[0047] Specifically, the energy conversion system includes a boost circuit, which can be referenced. Figure 2 As shown, a boost circuit is a circuit that converts a low input voltage into a high output voltage; it is also called a boost circuit. The boost circuit controls the switching frequency of the switching transistor, so that the input power supply, after passing through an inductor, diode, and capacitor, ultimately obtains an output voltage higher than the input voltage. During charging, the switch is closed, causing the input voltage to flow through the inductor, which stores energy. During discharging, the switch is open, the energy stored in the inductor is released, and the energy is transferred to the output capacitor and load through the diode, thus achieving voltage boost.

[0048] First, it must be determined that there is no power input at the input terminal. In a photovoltaic system, when there is no power input or the photovoltaic input terminal is floating, the diodes in the system may experience reverse leakage current. If the system does not detect this state, it may incorrectly assume that there is photovoltaic input, causing the control system to execute incorrect instructions. To determine if there is no power input, for example, a high-precision current sampling resistor can be connected in series to the low-side of the input terminal, with its two ends connected to the current sensing sampling pin of the chip. The input current value can be obtained by reading the chip register. If the input current is below a certain threshold, it can be determined that there is no power input at the input terminal. Alternatively, the absence of power input can also be determined by obtaining the current value of the inductor in the boost circuit and the input voltage value. For example, if the product of the current and voltage values ​​is below a certain value, it can be determined that there is no power input at the input terminal.

[0049] To determine the maximum leakage power of the diode in a boost converter circuit, we need to find the maximum leakage current of the diode when it is reverse biased, which is the power dissipated due to the reverse leakage current flowing through the diode. To determine the maximum leakage power, we can consult the diode's datasheet to find the maximum reverse leakage current of a specific model at a specific temperature. Then, by combining this with the actual DC bus voltage in the boost converter circuit, we can calculate the maximum leakage power of the diode by multiplying the maximum reverse leakage current by the DC bus voltage.

[0050] After determining the maximum leakage power, the frequency or duty cycle of the drive signal for the switching transistor in the boost circuit can be adjusted to ensure that the input power at the input terminal is less than or equal to the maximum leakage power, thereby avoiding the generation of false voltage. In other words, when controlling the drive signal of the switching transistor to output a series of drive pulses (PWM (Pulse Width Modulation) signals), the PWM signal can be used to control the switching of the switching transistor in the boost circuit to regulate the power at the photovoltaic input terminal. Specifically, by adjusting the frequency (i.e., the periodically changing frequency) or duty cycle (i.e., the ratio of high-level time to total period time within one cycle) of the PWM signal, the conduction and turn-off of the switching transistor can be controlled, thereby controlling the power at the photovoltaic input terminal to ensure it does not exceed the maximum leakage power of the diode.

[0051] For example, when the judgment result is no photovoltaic input or the photovoltaic input terminal is floating, the gate drive signal of the IGBT (Insulated Gate Bipolar Transistor) in the boost circuit is controlled to output a series of drive pulses, referencing... Figure 3As shown, there are two control methods: Method 1: The output pulse high-level width Ton is basically fixed, and the pulse low-level time Toff is controlled, which is to control the PWM frequency. In this method, Ton remains unchanged, while Toff is adjusted. Since the PWM period (T = Ton + Toff) is fixed, changing Toff actually changes the PWM frequency. When Toff increases, the PWM frequency decreases; when Toff decreases, the PWM frequency increases. In this way, the current of the inductor in the boost circuit can be controlled, thereby managing the power at the photovoltaic input. Method 2: The output pulse frequency is basically fixed, and the pulse high-level time Ton is controlled, which is to control the PWM duty cycle. In this method, the PWM frequency remains unchanged, while Ton is adjusted. The duty cycle is the ratio of Ton to the PWM period T (duty cycle = Ton / T). By changing Ton, the duty cycle can be changed without affecting the PWM frequency. The higher the duty cycle, the larger the current in the inductor; the lower the duty cycle, the smaller the current in the inductor.

[0052] The frequency of the PWM signal can be changed by altering the duration Toff of the low-level (i.e., the switching transistor being off) phase in the PWM signal. Adjusting Toff changes the period of the PWM signal, thus altering its frequency. For example, increasing the duration Toff of the low-level phase reduces the PWM frequency, which decreases the diode's on-time, thereby reducing the peak inductor current and lowering the input power to keep it below the maximum leakage power. Alternatively, if the PWM signal period (the time interval between one high-level and the next high-level) is set to a fixed value, meaning the PWM signal frequency (the reciprocal of the period) is also fixed, the duration Ton of the high-level (i.e., the switching transistor being on) phase within each fixed period can be adjusted. The duration Ton is a part of the PWM signal period and determines the length of time the switching transistor is on within each period. The duty cycle is the ratio of the high-level time to the total period time within a PWM cycle. Changing Ton changes the duty cycle. For example, if a period is 100 microseconds and Ton is 50 microseconds, then the duty cycle is 50%. By changing the duty cycle, the on-time of the switching transistor can be adjusted, thereby controlling the current and power passing through the transistor. A higher duty cycle results in a longer on-time and a greater average output power; a lower duty cycle results in a shorter on-time and a smaller average output power. Thus, even when the photovoltaic input voltage is low, in order to keep the input power below the maximum leakage power, Ton can be reduced, i.e., the on-time of the switching transistor can be reduced, thereby reducing the input power at the input terminal.

[0053] Therefore, it is possible to effectively control the false voltage at the photovoltaic input terminal and improve the stability and efficiency of the energy conversion system.

[0054] According to one embodiment of this application, adjusting the frequency of the drive signal for the switching transistor in a boost circuit includes: obtaining the peak current of the inductor in the boost circuit and the on-time of the switching transistor; obtaining the freewheeling time of the diode when the switching transistor is in the off state; determining the minimum off-time of the switching transistor based on the equality between the discharge power of the capacitor and the maximum leakage power in the boost circuit and the freewheeling time; and adjusting the frequency of the drive signal based on the minimum on-time and off-time of the switching transistor.

[0055] Specifically, refer to Figure 4 As shown, by adjusting the frequency of the drive signal for the switching transistor in the boost circuit, the peak current (IL_max) of the inductor and the on-time (Ton) of the switching transistor can be obtained. In a PWM-controlled boost circuit, the peak current of the inductor and the on-time of the switching transistor can be obtained by monitoring the current on the inductor and the high-level duration of the PWM signal. The inductor current increases linearly during the on-time of the switching transistor and decreases linearly during the off-time, forming a triangular waveform. When the switching transistor is off, the current continues to flow through the diode; this period is called the diode freewheeling time (Td), which can be determined by monitoring the current on the diode, typically ending when the inductor current decreases to zero. The discharge power of the photovoltaic input capacitor can be determined based on the photovoltaic input voltage and capacitance value. The maximum leakage power can be determined based on the maximum value of the diode's reverse leakage current and the DC bus voltage. Therefore, by comparing the discharge power and the maximum leakage power, and considering the freewheeling time, the minimum turn-off time of the switching transistor can be determined. For example, the minimum turn-off time can be determined through a pre-defined relationship between the discharge power, maximum leakage power, freewheeling time, and minimum turn-off time. Once the discharge power, maximum leakage power, and freewheeling time are determined, the minimum turn-off time can be obtained by directly applying this relationship. This ensures that the input power does not exceed the maximum leakage power. In other words, if the turn-off time is too short, the energy stored in the inductor may not be fully released, causing the input power to exceed the maximum leakage power.

[0056] After determining the minimum turn-off time, the frequency of the drive signal can be adjusted based on the on-time and minimum turn-off time of the switching transistor. That is, the frequency (f) of the drive signal is related to the on-time (Ton) and turn-off time (Toff) of the switching transistor, i.e., f = 1 / Ton + Toff. The on-time of the switching transistor can be a fixed value or a variable value; the turn-off time is the minimum turn-off time. To keep the input power below the maximum leakage power, the frequency of the PWM signal needs to be adjusted, which involves adjusting Ton and Toff. For example, if a reduction in power output is needed, Toff can be increased (greater than the minimum turn-off time), thus lowering the frequency; if an increase in power output is needed, Toff can be decreased, thus increasing the frequency. Furthermore, when the photovoltaic input voltage increases and the PWM control strategy cannot further reduce the voltage, this indicates that the photovoltaic system has restored normal energy input. In this case, the power at the photovoltaic input has exceeded the maximum leakage power, therefore, the photovoltaic system can be considered to have returned to normal operation and the photovoltaic power can be reused.

[0057] According to one embodiment of this application, adjusting the duty cycle of the drive signal for the switching transistor in a boost circuit includes: obtaining the peak current of the inductor in the boost circuit and the on-time of the switching transistor; obtaining the freewheeling time of the diode when the switching transistor is in the off state; determining the maximum on-time of the switching transistor based on the equality relationship between the discharge power and the maximum leakage power of the capacitor in the boost circuit, the freewheeling time, and the pulse period of the drive signal; and adjusting the duty cycle of the drive signal based on the maximum on-time of the switching transistor and the pulse period.

[0058] Specifically, when adjusting the duty cycle of the drive signal for the switching transistor in a boost circuit, the peak current of the inductor and the on-time of the switching transistor can be obtained. In a PWM-controlled boost circuit, the peak current of the inductor and the on-time of the switching transistor can be obtained by monitoring the current through the inductor and the high-level duration of the PWM signal. The inductor current increases linearly during the on-time of the switching transistor and decreases linearly during the off-time, forming a triangular waveform. When the switching transistor is off, current continues to flow through the diode; this period is called the diode's freewheeling time, which can be determined by monitoring the current through the diode, typically ending when the inductor current decreases to zero.

[0059] Based on the equality relationship between the capacitor's discharge power and maximum leakage power in the boost circuit, the freewheeling time, and the pulse period of the drive signal, the maximum conduction time of the switching transistor is determined. In other words, the conduction time of the switching transistor determines the charging time of the inductor. Within one PWM cycle, the inductor charging power is proportional to the conduction time. Therefore, to avoid exceeding the maximum leakage power, the maximum conduction time needs to be determined based on the capacitor's discharge power, maximum leakage power, freewheeling time, and the pulse period of the drive signal. This maximum value ensures that under any circumstances, the capacitor's discharge power plus the power loss during diode freewheeling will not exceed the maximum leakage power; that is, the maximum conduction time is set. This ensures that the duty cycle of the PWM signal will not exceed the set maximum value, preventing system overheating or damage. For example, the relationship between the discharge power, maximum leakage power, freewheeling time, and the pulse period of the drive signal and the maximum conduction time can be predetermined. After determining the discharge power, maximum leakage power, freewheeling time, and pulse period, the maximum conduction time can be obtained by directly calling the corresponding relationship.

[0060] After determining the maximum on-time, the duty cycle of the drive signal can be adjusted based on the maximum on-time of the switching transistor and the pulse period. The pulse period is T, which is generally a fixed value but can also be variable. The PWM duty cycle is the ratio of the on-time to the entire PWM period (T). By adjusting the on-time, the duty cycle can be changed, thereby controlling the charging power of the inductor and the discharging power of the capacitor. To reduce output power, the on-time can be reduced, lowering the duty cycle; to increase output power, the on-time can be appropriately increased, raising the duty cycle, but not exceeding the maximum on-time limit. Furthermore, when the photovoltaic input voltage increases and the PWM control strategy cannot further reduce the voltage, this indicates that the photovoltaic system has restored normal energy input. In this case, the power at the photovoltaic input has exceeded the maximum leakage power, therefore, the photovoltaic system can be considered to have returned to normal operation and the photovoltaic power can be reused.

[0061] Therefore, by following the steps above, the conduction time of the switching transistor in the boost circuit can be precisely controlled to ensure that the input power does not exceed the maximum leakage power, while maintaining the stability of the output voltage. This method helps to optimize the performance and efficiency of the boost circuit.

[0062] According to one embodiment of this application, obtaining the freewheeling time of a diode includes: obtaining the work done by the input voltage and the work done by the output voltage at the input terminal, wherein the work done by the input voltage is used to characterize the work done by the input voltage on the inductor, and the work done by the output voltage is used to characterize the work done by the boost circuit on the load; and determining the freewheeling time of the diode based on the equality relationship between the work done by the input voltage and the work done by the output voltage.

[0063] Specifically, when determining the freewheeling time of a diode, the work done by the input voltage and the work done by the output voltage can be obtained. The input voltage work refers to the work done by the input voltage on the inductor, i.e., the energy stored in the inductor during charging. This can be characterized by the product of the voltage across the inductor and the current flowing through it. The output voltage work refers to the work done by the boost circuit on the load, i.e., the energy stored in the inductor is released to the load after being converted by the boost circuit. This can be characterized by the product of the output voltage and the current flowing through the load. After determining the input and output voltage work, the diode's freewheeling time can be determined based on the equality between the input and output voltage work.

[0064] In other words, ideally, without energy loss, the work done by the input voltage should equal the work done by the output voltage; that is, the energy stored in the inductor will eventually be converted by the boost circuit and transferred to the load. The freewheeling time of a diode refers to the time during a PWM cycle when the switching transistor is turned off and the diode continues to conduct to allow current to flow. This time is crucial for maintaining stable circuit operation. By monitoring and controlling the work done by the input and output voltages, the freewheeling time of the diode can be determined.

[0065] Furthermore, according to one embodiment of this application, the work done by the input voltage, the work done by the output voltage, and the freewheeling time of the diode are obtained by the following formulas:

[0066] P1 = 1 / 2 * V PV *IL max *(T on +T d (1)

[0067] P2 = 1 / 2 * V dc *IL max *T d (2)

[0068] P1 = P2(3)

[0069] T d =V PV *T on / (V dc -V PV (4)

[0070] Where P1 represents the work done by the input voltage, P2 represents the work done by the output voltage, and V PV Indicates the input voltage, IL max V represents the peak current of the inductor. dc T represents the DC bus voltage at the output of the boost circuit. on T represents the on-time of the switching transistor. d This indicates the freewheeling time of the diode.

[0071] Specifically, in one PWM cycle, the work done by the input voltage at the input terminal can be determined by the above formula (1), that is, by multiplying the product of the input voltage, the peak current of the inductor, the conduction time of the switching transistor, and the freewheeling time of the diode by 1 / 2. The work done by the output voltage at the input terminal can be determined by the above formula (2), that is, by multiplying the product of the DC bus voltage at the output terminal of the boost circuit, the peak current of the inductor, and the freewheeling time of the diode by 1 / 2. Thus, after determining the work done by the input voltage and the work done by the output voltage, formula (3) can be transformed to obtain formula (4), that is, V PV *(T on +T d ) = V dc *T d After transforming the formula, we can obtain T. d =V PV *T on / (V dc -V PV Therefore, the ratio between the product of the input voltage and the conduction time of the switching transistor, and the voltage difference between the DC bus voltage at the output of the boost circuit and the input voltage, can be used as the freewheeling time of the diode.

[0072] According to one embodiment of this application, obtaining the maximum leakage power of a diode in a boost circuit includes: obtaining the DC bus voltage at the output terminal of the boost circuit and the maximum reverse leakage current of the diode; and determining the maximum leakage power based on the product between the DC bus voltage and the maximum reverse leakage current.

[0073] Specifically, to obtain the maximum leakage power of the diode in a boost converter circuit, one can obtain the DC bus voltage at the output of the boost converter circuit and the maximum reverse leakage current of the diode. The DC bus voltage refers to the stable voltage at the output of the boost converter circuit, which can be directly measured using a digital multimeter or oscilloscope. The reverse leakage current of the diode refers to the tiny current flowing through the diode when it is reverse biased. Although this current is very small, it can still generate significant power consumption under high voltage. The maximum reverse leakage current of the diode can be obtained from the corresponding diode's datasheet.

[0074] After determining the DC bus voltage at the output terminal and the maximum reverse leakage current of the diode, the maximum leakage power can be determined based on the product of the DC bus voltage and the maximum reverse leakage current, which can be used to estimate the maximum power loss due to the reverse leakage current of the diode in the worst case.

[0075] According to one embodiment of this application, the discharge power of the capacitor is obtained by the following formula:

[0076] P PV =1 / 2*IL max *(T on +T d )*V PV / (T on +T off (5)

[0077] Among them, P PV IL represents the discharge power of the capacitor. max T represents the peak current of the inductor. on T represents the on-time of the switching transistor. d V represents the freewheeling time of the diode. PV T represents the input voltage. off This indicates the turn-off time of the switching transistor.

[0078] Specifically, when obtaining the discharge power of the capacitor, it can be obtained through the above formula (5), that is, based on the peak current IL of the inductor. max On-time T of the switching transistor on With the freewheeling time T of the diode d The sum of the input voltage V PV The product of these two factors, divided by the on-time T of the switching transistor, is... on With respect to the turn-off time T of the switching transistor off The sum of these values ​​is used to obtain the capacitor's discharge power P. PV .

[0079] Therefore, based on the equality between the capacitor's discharge power and the maximum leakage power, as well as the freewheeling time, the minimum turn-off time of the switching transistor can be determined, i.e., according to the maximum leakage power formula P. R =I R *V dc Formula P R =P PV and the continuous streaming time T d =V PV *T on / (V dc -V PV The minimum turn-off time T can be determined. off =IL max *T on *V PV / (2*I R *(V dc -V PV ))-T on , among which, I R V represents the maximum reverse leakage current. dc This is the DC bus voltage at the output of the boost circuit.

[0080] When determining the maximum conduction time of the switching transistor based on the equality relationship between the capacitor's discharge power and the maximum leakage power in the boost circuit, the freewheeling time, and the pulse period of the drive signal, the maximum leakage power formula P can be used. R =I R *V dc Formula P R =P PV Continuation time T d =V PV *T on / (V dc -V PV ), pulse period T = T on +T off The maximum conduction time T of the switching transistor can be determined. on 2*I R *(V dc -V PV )*T / (IL max *V PV ).

[0081] According to one embodiment of this application, determining that there is no power input at the input terminal includes: acquiring the current value of the inductor in the boost circuit and the input terminal voltage; determining the input power at the input terminal based on the current value and the input terminal voltage; and determining that there is no power input at the input terminal if the input power at the input terminal is less than a preset power threshold for a preset time. The preset power threshold and duration can be determined according to actual conditions.

[0082] Specifically, determining the absence of energy input at the photovoltaic (PV) input terminal is a crucial step, used to determine whether the PV system is in a state of no sunlight or with the input terminal unloaded. To determine this, the current value of the inductor in the PV input boost circuit and the voltage value at the PV input terminal (input voltage) are first obtained. This can be achieved, for example, through sensors or monitoring devices in the circuit. Then, using the measured current and voltage values, the input power at the PV input terminal can be calculated; that is, the input power is the product of the current value and the input voltage. A preset power threshold is set, which is the power limit at which the system considers there to be no effective input at the PV input terminal. Simultaneously, a preset time is set, which is the length of time the system needs to continuously monitor the input power below the preset power threshold. If there is effective energy input at the PV input terminal, the input power will be higher than the preset power threshold. Therefore, after comparing the input power with the preset power threshold, if the input power at the input terminal is less than the preset power threshold for the preset time, it can be determined that there is no energy input at the input terminal.

[0083] Therefore, it is possible to accurately determine whether the photovoltaic input terminal is in a state of no energy input, and thus take corresponding control measures, such as activating specific control strategies to eliminate false voltages and prevent the control system from executing incorrect instructions, thereby improving the reliability and efficiency of the system, and avoiding potential problems caused by misjudging the photovoltaic input status.

[0084] According to one embodiment of this application, the input voltage elimination method of the energy conversion system further includes: determining that there is energy connected to the input terminal when the input power at the input terminal is greater than the maximum leakage power.

[0085] Specifically, by comparing the input power at the input terminal with the maximum leakage power, it can be determined that energy is being supplied to the input terminal if the input power is greater than the maximum leakage power. In other words, when the input power exceeds the maximum leakage power, it indicates the presence of additional energy input. This is because when there is no photovoltaic input or the photovoltaic input terminal is floating, the power consumption generated by the reverse leakage current of the diode is relatively small, typically lower than the maximum leakage power. If the actual measured input power exceeds this value, it indicates that other energy sources (such as electricity generated by the photovoltaic panel under sunlight) are being input into the system. Therefore, determining that energy is being supplied to the input terminal when the input power exceeds the maximum leakage power helps the system accurately respond to changes in the input state and avoids potential problems caused by misjudging the photovoltaic input state.

[0086] The following is combined with Figure 5 This describes the control method of this application.

[0087] As a specific example, the input voltage elimination method of the energy conversion system of this application may include the following steps:

[0088] S101 obtains the current value of the inductor and the input voltage in the boost circuit.

[0089] S102 determines the input power at the input terminal based on the current value and the input terminal voltage.

[0090] S103, determine whether the input power at the input terminal is less than a preset power threshold and remains so for a preset time. If yes, proceed to step S104; if no, proceed to step S113.

[0091] S104, confirming that there is no power input at the input terminal.

[0092] S105 retrieves the DC bus voltage at the output of the boost circuit and the maximum reverse leakage current of the diode.

[0093] S106 determines the maximum leakage power based on the product of the DC bus voltage and the maximum reverse leakage current.

[0094] S107 obtains the peak current of the inductor and the on-time of the switching transistor in the boost circuit.

[0095] S108: When the switching transistor is in the off state, obtain the freewheeling time of the diode, and proceed to step S109 or step S111 respectively.

[0096] S109, based on the equal relationship between the discharge power of the capacitor and the maximum leakage power in the boost circuit and the freewheeling time, determine the minimum turn-off time of the switching transistor.

[0097] S110 adjusts the frequency of the drive signal based on the minimum on-time and off-time of the switching transistor, so that the input power at the input terminal is less than or equal to the maximum leakage power.

[0098] S111, based on the equal relationship between the discharge power and the maximum leakage power of the capacitor in the boost circuit, the freewheeling time, and the pulse period of the drive signal, determine the maximum conduction time of the switching transistor.

[0099] S112 adjusts the duty cycle of the drive signal based on the maximum on-time of the switching transistor and the pulse period, so that the input power at the input terminal is less than or equal to the maximum leakage power.

[0100] S113, confirming that there is energy access at the input terminal.

[0101] In summary, the input voltage elimination method for the energy conversion system according to the embodiments of this application determines that there is no energy input at the input terminal, obtains the maximum leakage power of the diode in the boost circuit, and adjusts the frequency or duty cycle of the drive signal of the switching transistor in the boost circuit so that the input power at the input terminal is less than or equal to the maximum leakage power. Therefore, this method can avoid power loss and significant temperature increases in the energy-consuming resistor, reduce the size of the equipment, and improve the reliability of the system.

[0102] Corresponding to the above embodiments, this application also proposes an input voltage elimination device for an energy conversion system.

[0103] like Figure 6 As shown, the input voltage elimination device 100 of the energy conversion system in this application embodiment includes: a determination module 110, an acquisition module 120, and an adjustment module 130.

[0104] The determination module 110 is used to determine that there is no power input at the input terminal. The acquisition module 120 is used to acquire the maximum leakage power of the diode in the boost circuit. The adjustment module 130 is used to adjust the frequency or duty cycle of the drive signal of the switching transistor in the boost circuit so that the input power at the input terminal is less than or equal to the maximum leakage power.

[0105] According to one embodiment of this application, the adjustment module 130 adjusts the frequency of the drive signal for the switching transistor in the boost circuit, specifically for: obtaining the peak current of the inductor in the boost circuit and the conduction time of the switching transistor; obtaining the freewheeling time of the diode when the switching transistor is in the off state; determining the minimum off-time of the switching transistor based on the equality between the discharge power of the capacitor and the maximum leakage power in the boost circuit and the freewheeling time; and adjusting the frequency of the drive signal based on the minimum conduction and off-time of the switching transistor.

[0106] According to one embodiment of this application, the adjustment module 130 adjusts the duty cycle of the drive signal for the switching transistor in the boost circuit. Specifically, it is used to: obtain the peak current of the inductor in the boost circuit and the conduction time of the switching transistor; obtain the freewheeling time of the diode when the switching transistor is in the off state; determine the maximum conduction time of the switching transistor based on the equality relationship between the discharge power of the capacitor and the maximum leakage power in the boost circuit, the freewheeling time, and the pulse period of the drive signal; and adjust the duty cycle of the drive signal based on the maximum conduction time of the switching transistor and the pulse period.

[0107] According to one embodiment of this application, the acquisition module 120 acquires the freewheeling time of the diode, specifically for: acquiring the work done by the input voltage and the work done by the output voltage at the input terminal, wherein the work done by the input voltage is used to characterize the work done by the input voltage on the inductor, and the work done by the output voltage is used to characterize the work done by the boost circuit on the load; and determining the freewheeling time of the diode based on the equal relationship between the work done by the input voltage and the work done by the output voltage.

[0108] According to one embodiment of this application, the acquisition module 120 obtains the work done by the input voltage, the work done by the output voltage, and the freewheeling time of the diode using the following formula:

[0109] P1 = 1 / 2 * V PV *IL max *(T on +T d )

[0110] P2 = 1 / 2 * V dc *IL max *T d

[0111] P1 = P2

[0112] T d =V PV *T on / (V dc -V PV )

[0113] Where P1 represents the work done by the input voltage, P2 represents the work done by the output voltage, and V PV Indicates the input voltage, ILmax V represents the peak current of the inductor. dc T represents the DC bus voltage at the output of the boost circuit. on T represents the on-time of the switching transistor. d This indicates the freewheeling time of the diode.

[0114] According to one embodiment of this application, the acquisition module 120 acquires the maximum leakage power of the diode in the boost circuit, specifically for: acquiring the DC bus voltage at the output terminal of the boost circuit and the maximum reverse leakage current of the diode; and determining the maximum leakage power based on the product between the DC bus voltage and the maximum reverse leakage current.

[0115] According to one embodiment of this application, the obtaining module 120 obtains the discharge power of the capacitor using the following formula:

[0116] P PV =1 / 2*IL max *(T on +T d )*V PV / (T on +T off )

[0117] Among them, P PV IL represents the discharge power of the capacitor. max T represents the peak current of the inductor. on T represents the on-time of the switching transistor. d V represents the freewheeling time of the diode. PV T represents the input voltage. off This indicates the turn-off time of the switching transistor.

[0118] According to one embodiment of this application, the determining module 110 determines that there is no power input at the input terminal, specifically used for: obtaining the current value of the inductor in the boost circuit and the input terminal voltage; determining the input power at the input terminal based on the current value and the input terminal voltage; and determining that there is no power input at the input terminal when the input power at the input terminal is less than a preset power threshold and continues for a preset time.

[0119] According to one embodiment of this application, the determining module 110 is further configured to: determine that there is energy access at the input terminal when the input power at the input terminal is greater than the maximum leakage power.

[0120] It should be noted that for details not disclosed in the input voltage elimination device of the energy conversion system in the embodiments of this application, please refer to the details disclosed in the input voltage elimination method of the energy conversion system in the embodiments of this application, which will not be repeated here.

[0121] According to the energy conversion system input voltage elimination device of this application embodiment, a determining module is used to determine that there is no energy input at the input terminal, an acquiring module is used to acquire the maximum leakage power of the diode in the boost circuit, and an adjusting module is used to adjust the frequency or duty cycle of the drive signal of the switching transistor in the boost circuit so that the input power at the input terminal is less than or equal to the maximum leakage power. Therefore, this device can avoid power loss and significant temperature increase of the energy-consuming resistor, reduce the size of the equipment, and improve the reliability of the system.

[0122] Corresponding to the above embodiments, this application also proposes a computer-readable storage medium.

[0123] The computer-readable storage medium of this application embodiment stores a program that, when executed by a processor, implements the above-described input voltage elimination method for an energy conversion system.

[0124] According to the computer-readable storage medium of the present application embodiment, by performing the above-described input voltage elimination method of the energy conversion system, the power loss and temperature rise of the energy-consuming resistor can be avoided, the size of the device can be reduced, and the reliability of the system can be improved.

[0125] Corresponding to the above embodiments, this application also proposes a controller.

[0126] like Figure 7 As shown, the controller 200 in this embodiment may include: a memory 210, a processor 220, and a program stored in the memory 210 and executable on the processor 220. When the processor 220 executes the program, it implements the above-described input voltage elimination method for the energy conversion system.

[0127] According to the controller in the embodiments of this application, by executing the above-described input voltage elimination method of the energy conversion system, the power loss and temperature rise of the energy-consuming resistor can be avoided, the size of the device can be reduced, and the reliability of the system can be improved.

[0128] It should be noted that the logic and / or steps represented in the flowchart or otherwise described herein, for example, can be considered as a sequenced list of executable instructions for implementing logical functions, and can be embodied in any computer-readable medium for use by, or in conjunction with, an instruction execution system, apparatus, or device (such as a computer-based system, a processor-included system, or other system that can fetch and execute instructions from, an instruction execution system, apparatus, or device). For the purposes of this specification, "computer-readable medium" can be any means that can contain, store, communicate, propagate, or transmit programs for use by, or in conjunction with, an instruction execution system, apparatus, or device. More specific examples (a non-exhaustive list) of computer-readable media include: an electrical connection having one or more wires (electronic device), a portable computer disk drive (magnetic device), random access memory (RAM), read-only memory (ROM), erasable and editable read-only memory (EPROM or flash memory), fiber optic devices, and portable optical disc read-only memory (CDROM). Alternatively, the computer-readable medium may be paper or other suitable media on which the program can be printed, since the program can be obtained electronically, for example, by optically scanning the paper or other medium, followed by editing, interpreting, or otherwise processing as necessary, and then stored in a computer memory.

[0129] It should be understood that various parts of this application can be implemented using hardware, software, firmware, or a combination thereof. In the above embodiments, multiple steps or methods can be implemented using software or firmware stored in memory and executed by a suitable instruction execution system. For example, if implemented in hardware, as in another embodiment, it can be implemented using any one or a combination of the following techniques known in the art: discrete logic circuits having logic gates for implementing logical functions on data signals, application-specific integrated circuits (ASICs) having suitable combinational logic gates, programmable gate arrays (PGAs), field-programmable gate arrays (FPGAs), etc.

[0130] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0131] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0132] In this application, unless otherwise expressly specified and limited, the terms "installation," "connection," "joining," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise expressly limited. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0133] Although embodiments of this application have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting this application. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of this application.

Claims

1. A method for eliminating input voltage in an energy conversion system, characterized in that, The energy conversion system includes a boost circuit, and the method includes: It has been determined that there is no power input at the input terminal; Obtain the maximum leakage power of the diode in the boost circuit; The frequency or duty cycle of the drive signal for the switching transistor in the boost circuit is adjusted so that the input power at the input terminal is less than or equal to the maximum leakage power.

2. The method according to claim 1, characterized in that, Adjusting the frequency of the drive signal for the switching transistor in the boost circuit includes: Obtain the peak current of the inductor in the boost circuit and the conduction time of the switching transistor; When the switching transistor is in the off state, the freewheeling time of the diode is obtained; Based on the equality relationship between the discharge power of the capacitor in the boost circuit and the maximum leakage power, as well as the freewheeling time, the minimum turn-off time of the switching transistor is determined. The frequency of the drive signal is adjusted based on the minimum value of the turn-on time and the turn-off time of the switching transistor.

3. The method according to claim 1, characterized in that, Adjusting the duty cycle of the drive signal for the switching transistor in the boost circuit includes: Obtain the peak current of the inductor in the boost circuit and the conduction time of the switching transistor; When the switching transistor is in the off state, the freewheeling time of the diode is obtained; Based on the equality relationship between the discharge power of the capacitor in the boost circuit and the maximum leakage power, the freewheeling time, and the pulse period of the drive signal, the maximum conduction time of the switching transistor is determined. The duty cycle of the drive signal is adjusted based on the maximum on-time of the switch and the pulse period.

4. The method according to claim 2 or 3, characterized in that, Obtaining the freewheeling time of the diode includes: The work done by the input voltage and the work done by the output voltage at the input terminal are obtained, wherein the work done by the input voltage is used to characterize the work done by the input voltage on the inductor, and the work done by the output voltage is used to characterize the work done by the boost circuit on the load; The freewheeling time of the diode is determined based on the equality between the work done by the input voltage and the work done by the output voltage.

5. The method according to claim 4, characterized in that, The work done by the input voltage, the work done by the output voltage, and the freewheeling time of the diode are obtained using the following formulas: P1 = 1 / 2 * VPV * ILmax * (Ton + Td) P2 = 1 / 2 * Vdc * ILmax * Td P1 = P2 Td = VPV * Ton / (Vdc - VPV) Wherein, P1 represents the work done by the input voltage, P2 represents the work done by the output voltage, VPV represents the input terminal voltage, ILmax represents the peak current of the inductor, Vdc represents the DC bus voltage at the output terminal of the boost circuit, Ton represents the conduction time of the switching transistor, and Td represents the freewheeling time of the diode.

6. The method according to claim 1, characterized in that, Obtaining the maximum leakage power of the diode in the boost circuit includes: Obtain the DC bus voltage at the output terminal of the boost circuit and the maximum reverse leakage current of the diode; The maximum leakage power is determined based on the product of the DC bus voltage and the maximum reverse leakage current.

7. The method according to claim 2 or 3, characterized in that, The discharge power of the capacitor is obtained using the following formula: PPV=1 / 2*ILmax*(Ton+Td)*VPV / (Ton+Toff) Wherein, PPV represents the discharge power of the capacitor, ILmax represents the peak current of the inductor, Ton represents the on-time of the switch, Td represents the freewheeling time of the diode, VPV represents the input voltage, and Toff represents the off-time of the switch.

8. The method according to claim 1, characterized in that, Determining that there is no power input at the input terminal includes: Obtain the current value and input voltage of the inductor in the boost circuit; The input power of the input terminal is determined based on the current value and the input terminal voltage; If the input power at the input terminal is less than a preset power threshold and remains so for a preset time, it is determined that there is no energy input at the input terminal.

9. The method according to claim 1, characterized in that, The method further includes: If the input power at the input terminal is greater than the maximum leakage power, it is determined that there is energy connected to the input terminal.

10. An input voltage elimination device for an energy conversion system, characterized in that, The energy conversion system includes a boost circuit, and the device includes: The determination module is used to determine that there is no power input at the input terminal; The acquisition module is used to acquire the maximum leakage power of the diode in the boost circuit; An adjustment module is used to adjust the frequency or duty cycle of the drive signal of the switching transistor in the boost circuit so that the input power at the input terminal is less than or equal to the maximum leakage power.

11. A computer-readable storage medium, characterized in that, It stores an input voltage elimination program for an energy conversion system, which, when executed by a processor, implements the input voltage elimination method for an energy conversion system according to any one of claims 1-9.

12. A controller, characterized in that, The system includes a memory, a processor, and an input voltage elimination program for an energy conversion system stored in the memory and executable on the processor. When the processor executes the input voltage elimination program for the energy conversion system, it implements the input voltage elimination method for the energy conversion system according to any one of claims 1-9.

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