Building intercom system and control method

Abstract

The present invention relates to the field of intercom systems, and in particular to a building intercom system and a control method. The present invention sets a first SOC and divides the working mode of a battery into a first mode and a second mode according to the actual SOC of the battery, thereby realizing charging protection of the battery and protecting the efficient and stable operation of the battery. According to customer needs, a specified power and a first voltage are set in the first mode, and the tracking and locking of the maximum voltage corresponding to the specified power that meets the customer needs are achieved by changing the step size. Furthermore, by constructing a voltage-current dual closed-loop control circuit based on constant voltage output, voltage feedforward and current feedforward, it is ensured that the output can still output a voltage with extremely high stability in the case of multiple power supplies, thereby ensuring the efficient operation of the building intercom equipment. The present invention solves the problems of mutual electromagnetic interference between different power supplies and the problem that power grid fluctuations easily affect the quality of electrical signal transmission in the current building intercom system.

Description

Technical Field

[0001] The invention relates to the field of intercom systems, and in particular to a building intercom system and a control method. Background Art

[0002] As the application of building intercom technology becomes more and more widespread, many problems have been found in the actual application process. In the traditional building intercom power supply system, due to the close parallel or cross laying of lines, it is easy to cause mutual electromagnetic interference between different power supplies, resulting in unstable fluctuations in the current or voltage in the line, affecting the signal size of the electrical signal during transmission or even causing signal loss, thereby affecting the transmission quality of the electrical signal, making it difficult to carry out efficient remote data communication, and the fluctuation of the power grid itself is also easy to affect the building intercom, and the system cannot be guaranteed to work reliably and stably. At the same time, the working efficiency of the building intercom system power supply is low, which increases the cost of system construction. Summary of the invention

[0003] In view of the deficiencies in the prior art, the present invention provides a building intercom system and a control method, which solve the problems in the current building intercom system that electromagnetic interference between different power supplies and power grid fluctuations easily affect the quality of electrical signal transmission.

[0004] To achieve the above object, the present invention provides the following technical solutions:

[0005] A building intercom system, comprising:

[0006] A photovoltaic control unit, the photovoltaic control unit is used to convert the input voltage of the direct current input by the photovoltaic panel into a specified voltage value according to the voltage storage requirement of the energy storage unit;

[0007] An energy storage unit, the energy storage unit is used to calculate the difference between the first power of the electric energy output by the photovoltaic control unit and the second power of the electric energy required by the building intercom device to obtain a third power, and when the third power is greater than or equal to 0, the electric energy of the third power is stored, and when the third power is less than 0, the multi-power supply outputs a stable voltage through a voltage-current dual closed-loop control circuit;

[0008] A power output unit, wherein the power output unit is used to output the electric energy stored in the energy storage unit to the building intercom equipment in a constant current or constant voltage manner.

[0009] Preferably, the photovoltaic control unit is a DC boost circuit.

[0010] Preferably, the power output unit is a DC step-down circuit.

[0011] A control method for a building intercom system, the control method comprising the following steps:

[0012] S1, setting a first mode and a second mode for operation of the building intercom system, and setting a first SOC to divide two SOC first threshold ranges corresponding to the first mode and the second mode;

[0013] S2. Determine whether the power supply enters the first mode according to whether the current SOC of the building intercom system power supply is less than the first SOC;

[0014] If yes, the first mode is entered and step S4 is entered;

[0015] If not, enter the second mode and proceed to step S3;

[0016] S3, obtaining the battery power of the photovoltaic cell and the maximum power of the photovoltaic panel, and calculating the input power of the photovoltaic cell according to the difference between the two so that the SOC is less than or equal to 1, and then entering step S5;

[0017] S4, setting the designated power and the first voltage, reducing the real-time voltage from the first voltage in sequence with a predetermined change step, calculating the real-time power, and marking the real-time voltage corresponding to the real-time power closest to the designated power as the maximum voltage and then locking it;

[0018] S5. Construct a voltage-current dual closed-loop control circuit based on constant voltage output, voltage feedforward and current feedforward.

[0019] Preferably, in step S3, the following steps are specifically included:

[0020] S31, setting a second SOC greater than the first SOC, and obtaining the mode of the power supply at the last moment;

[0021] S32, determining whether the current SOC is greater than the second SOC;

[0022] If yes, proceed to step S35;

[0023] If not, proceed to step S33;

[0024] S33, determining whether the current SOC is less than the first SOC;

[0025] If yes, proceed to step S4;

[0026] If not, proceed to step S34;

[0027] S34, determining whether the mode of the power supply at the last moment is the first mode;

[0028] If yes, proceed to step S4;

[0029] If not, proceed to step S35;

[0030] S35, obtaining the battery power of the photovoltaic cell and the maximum power of the photovoltaic panel, and calculating the input power of the photovoltaic cell, and then entering step S5; the calculation formula of the photovoltaic cell input power is:

[0031] P r =P mpp -P b

[0032] In the above formula, P r Represents the input power of the photovoltaic cell, P mpp Represents the battery power of the photovoltaic cell, P b Indicates the maximum power of the photovoltaic panel.

[0033] Preferably, in step S4, the following steps are specifically included:

[0034] S41, setting a specified power and a first voltage;

[0035] S42, collecting the output voltage and output current of the photovoltaic panel and calculating the real-time power at the corresponding moment; the calculation formula of the real-time power is:

[0036] P(k)=U(k)I(k)

[0037] In the above formula, P(k) represents the real-time power at the kth moment, the kth moment is the current moment, U(k) and I(k) represent the real-time voltage and real-time current at the kth moment respectively;

[0038] S43, determining whether the real-time power of the photovoltaic panel at the current moment is greater than the specified power;

[0039] If yes, proceed to step S44;

[0040] If not, proceed to step S46;

[0041] S44, setting a power difference threshold, and determining whether the difference between the real-time power and the specified power is within the power difference threshold;

[0042] If yes, the output voltage at the current moment is marked as the maximum voltage and locked, and the process goes to step S5;

[0043] If not, proceed to step S45;

[0044] S45, according to the output voltage of the photovoltaic panel at the current moment and the output voltage at the previous moment, calculate the transition voltage whose value is between the two, and adjust the real-time voltage of the photovoltaic panel at the next moment to the transition voltage, and then return to step S42; the calculation formula of the transition voltage is:

[0045]

[0046] In the above formula, U0 represents the transition voltage, U(k) represents the output voltage of the photovoltaic panel at the current moment, U(k-1) represents the output voltage of the photovoltaic panel at the previous moment, and τ represents the step adjustment coefficient;

[0047] S46, calculating a first voltage change according to the output voltage of the photovoltaic panel at the current moment and the output voltage at the previous moment; the calculation formula of the first voltage change is:

[0048] ΔU(1)=|U(k)-U(k-1)|

[0049] In the above formula, ΔU(1) represents the first voltage change, U(k) and U(k-1) represent the output voltage of the photovoltaic panel at the current moment and the output voltage at the previous moment respectively;

[0050] S47, judging whether the real-time power at the current moment is greater than the real-time power at the previous moment, and whether the real-time power at the previous moment is greater than the real-time power at two moments from the current moment;

[0051] If yes, proceed to step S48;

[0052] If not, the first adjustment voltage is calculated according to the output voltage of the photovoltaic panel at the current moment and the first voltage change, and is used as the output voltage of the photovoltaic panel at the next moment, and then returns to step S43; the calculation formula of the first adjustment voltage is:

[0053] U ref (1) = U(k) - ΔU(1)

[0054] In the above formula, U ref (1) represents the first adjusted voltage, U(k) represents the output voltage of the photovoltaic panel at the current moment, and ΔU(1) represents the first voltage change;

[0055] S48, determining whether the first voltage change is less than a voltage difference threshold;

[0056] If yes, the output voltage at the current moment is marked as the maximum voltage and locked, and then the process ends;

[0057] If not, the second adjustment voltage is calculated according to the first voltage change and the output voltage at the current moment; the calculation formula of the second adjustment voltage is: U ref (2) = U(k) + AΔU(1)

[0058] In the above formula, U ref (2) represents the second adjusted voltage, U(k) represents the output voltage of the photovoltaic panel at the current moment, A represents the voltage adjustment coefficient, and ΔU(1) represents the first voltage change.

[0059] Preferably, in step S5, the following steps are specifically included:

[0060] S51, constructing a voltage-current dual closed-loop control circuit based on maximum voltage constant voltage output, voltage feedforward and then current feedforward;

[0061] S52, setting the relationship between the circuit parameters in the voltage-current dual closed-loop control circuit; the circuit parameters satisfy the following relationship:

[0062]

[0063] In the above formula, Δu r is the output voltage disturbance change, u N The voltage difference between the maximum voltage corresponding to the specified power of the photovoltaic panel and the actual output voltage, K d is the droop coefficient of the controller, Δi is the output current disturbance change of the power supply, u0 is the output voltage when no load, i ref is the output current of the photovoltaic panel corresponding to the specified power, i L is the actual value of the inductor current, du0 is the voltage change, G PIu (s) is the voltage loop controller, G PIi (s) is the current loop controller;

[0064] S53, setting a transfer function between the voltage disturbance and the current disturbance; the transfer function between the voltage disturbance and the current disturbance is:

[0065]

[0066] In the above formula, ΔU0 is the disturbance change of output voltage when no-load, K d is the droop coefficient of the controller, Δi L is the disturbance change of the inductor current, du0 is the voltage change, R is the resistance value of the inductor, sL represents the wire resistance of the loop, K d (s) represents the control function of the droop coefficient, G PIu (s) is the voltage loop controller, G PIi (s) is the current loop controller.

[0067] Compared with the prior art, the present invention provides a building intercom system and control method, which have the following beneficial effects:

[0068] 1. The present invention sets a first SOC and divides the working mode of the battery into a first mode and a second mode according to the actual SOC of the battery, thereby realizing charging protection of the battery and protecting the efficient and stable operation of the battery. According to customer needs, a specified power and a first voltage are set in the first mode, and the tracking and locking of the maximum voltage corresponding to the specified power that meets customer needs are achieved by changing the step size. Furthermore, by constructing a voltage-current dual closed-loop control circuit based on constant voltage output, voltage feedforward and current feedforward, it is ensured that the output can still output a highly stable voltage in the case of multiple power supplies, thereby ensuring the efficient operation of the building intercom equipment.

[0069] 2. By setting the variation step size, the present invention can track and identify the maximum voltage point under the specified power more quickly with a larger step size when the output voltage differs greatly from the maximum voltage. At the same time, when approaching the maximum voltage, the variation step size can be automatically reduced, thereby accurately tracking the maximum voltage and ensuring the stability of the output.

[0070] 3. The present invention further improves the circuit based on constant voltage output, voltage feedforward and current feedforward on the basis of the voltage-current dual closed-loop control circuit, thereby being able to reduce mutual interference between different power supplies when multiple power supplies are output, improve the stability of each power supply output, and ensure the stable operation of the building intercom equipment. BRIEF DESCRIPTION OF THE DRAWINGS

[0071] The drawings described herein are used to provide a further understanding of the present application and constitute a part of the present application. The illustrative embodiments of the present application and their descriptions are used to explain the present application and do not constitute an improper limitation on the present application. In the drawings:

[0072] Figure 1 It is a schematic diagram of the circuit structure of the building intercom system of the present invention;

[0073] Figure 2 It is a flow chart of the building intercom system control method of the present invention;

[0074] Figure 3 is the output characteristic curve of the photovoltaic panel of the present invention;

[0075] Figure 4 It is the control block diagram of voltage-current dual closed-loop controller;

[0076] Figure 5 This is the control block diagram after the voltage feedforward is introduced;

[0077] Figure 6 It is a block diagram of the droop control strategy of the present invention;

[0078] Figure 7 This is a block diagram of the droop control transfer function of the present invention.

[0079] 1. Photovoltaic control unit; 2. Energy storage unit; 3. Power output unit. DETAILED DESCRIPTION

[0080] In order to make the above-mentioned purposes, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific implementation methods, so that the implementation process of how the present application uses technical means to solve technical problems and achieve technical effects can be fully understood and implemented accordingly.

[0081] Those skilled in the art can understand that all or part of the steps in the following embodiments can be completed by instructing the relevant hardware through a program, so the present application can be in the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Moreover, the present application can be in the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program codes.

[0082] Housing is a product that humans have long relied on for living, production, and entertainment. With the rapid development of culture and economy, housing not only has its original basic functions, but has now become a measure of people's assets and the soul of the financial world. As people have higher requirements for the safety, efficiency, and comfort of their living environment, housing, as our physical and mental residence, has made great progress in functionality. Residential intelligence and intelligent housing have become our most desired needs.

[0083] As the application of building intercom technology becomes more and more widespread, many problems have been found in the actual application process. Among them, improving the installation of building intercom systems in remote areas that are not suitable for access to the power grid is one of the problems that need to be solved. In traditional building intercom systems, building intercom power supply failure and unstable power supply often occur. Due to unstable power supply, the building intercom system requires frequent operation and maintenance. In the building intercom system, the power supplies are parallel or cross-layout in close proximity, which can easily cause mutual interference between different power supplies. In summary, the existing building intercom system battery application methods are limited and operation and maintenance are inconvenient. Therefore, it is necessary to study the power supply in the building intercom system.

[0084] In order to solve the problem that the electromagnetic interference between different power supplies and the power grid fluctuations in the current building intercom system easily affect the quality of electrical signal transmission, the present invention provides a building intercom system, such as Figure 1 As shown, in order to reduce the loss of the switching device during operation, the circuit adopts a synchronous rectification structure, and the entire circuit can be equivalent to two half-bridge circuits and a filter circuit composed of inductors and capacitors. The system includes:

[0085] A photovoltaic control unit 1 is used to convert the input voltage of the direct current input by the photovoltaic panel into a specified voltage value according to the voltage storage requirement of the energy storage unit. The photovoltaic control unit 1 is generally a DC boost circuit, which realizes the conversion of the current with a certain voltage output by the photovoltaic panel into a current with a corresponding voltage for storage by the energy storage unit 2; it is used to calculate the difference between the first power of the electric energy output by the photovoltaic control unit 1 and the second power of the electric energy required by the building intercom equipment to obtain a third power. When the third power is greater than or equal to 0, the electric energy of the third power is stored. When the third power is less than 0, the energy storage unit 2 outputs a stable voltage for multiple power sources through a voltage-current dual closed-loop control circuit. The energy storage unit 2 can realize bidirectional flow of energy and is mainly used for energy management of energy storage batteries and control of charging and discharging. When the input power of the front stage is greater than the output power of the rear stage, the electric energy The battery is charged, and vice versa, the battery is discharged. During this process, the bus voltage is always maintained in a fixed range. At the same time, when multiple power sources coexist, the output stability is guaranteed by the voltage-current dual closed-loop control circuit, which greatly reduces the mutual interference between the multiple power sources and ensures the stable use of the building intercom equipment; it is used to output the electric energy stored in the energy storage unit 2 to the power output unit 3 of the building intercom equipment in a constant current or constant voltage manner. In order to ensure that the output voltage can be used by the building intercom equipment, the power output unit 3 is generally a DC step-down circuit, which converts the voltage with a certain voltage output by the energy storage unit 2 into a voltage that can be used by the building intercom equipment. It generally has two control modes of constant voltage and constant current. The output can be controlled by instructions. When multiple devices are connected in parallel, the load power can be distributed according to the actual situation based on the output of the upper layer.

[0086] The power supply of the intelligent building intercom system is photovoltaic-powered, so it is necessary to analyze the working mode of the photovoltaic control part, which is mainly divided into three situations: 1) When the light conditions are sufficient, the photovoltaic panels can supply energy to the output end and the battery at the same time. At this time, the output power point of the photovoltaic panel works at the instruction working point that meets the load demand and the maximum charge of the battery; 2) When the light conditions are poor, the photovoltaic panels cannot simultaneously meet the power output and provide energy to the battery. The output power point of the photovoltaic panel works at the maximum power point; 3) When there is no light, the photovoltaic panels stop working and the system only supplies power to the load by the battery.

[0087] After analyzing the possible conditions of photovoltaic operation, it can be determined that the photovoltaic controller includes two working modes, and these two working states are mainly related to the light intensity received by the photovoltaic cell. The output voltage of the photovoltaic cell is used as the basis for judging the light intensity. When the voltage is greater than a certain value, it is considered that the light is sufficient, otherwise it is considered that the light is insufficient. For this reason, the present invention also provides a control method for a building intercom system. When the building intercom system has multiple power supplies, it is ensured that each power supply can output a constant voltage or a constant current, and the charging protection of the power supply is also realized to prevent overcharging, such as Figure 2 As shown, the control method includes the following steps:

[0088] S1, setting a first mode and a second mode for operation of the building intercom system, and setting a first SOC to divide two SOC first threshold ranges corresponding to the first mode and the second mode;

[0089] S2. Determine whether the power supply enters the first mode according to whether the current SOC of the building intercom system power supply is less than the first SOC;

[0090] If yes, the first mode is entered and step S4 is entered;

[0091] If not, enter the second mode and proceed to step S3;

[0092] S3, obtaining the battery power of the photovoltaic cell and the maximum power of the photovoltaic panel, and calculating the input power of the photovoltaic cell according to the difference between the two so that the SOC is less than or equal to 1, and then entering step S5;

[0093] Normally, in order to protect the battery from overcharging, it is necessary to control the battery charging. When the detected battery SOC is low, the photovoltaic power works at the maximum power output point. When the battery SOC reaches a certain range, the photovoltaic output will be set. The power at this time is the difference between the maximum photovoltaic output power at the current moment and the battery charging power. At this time, it can be equivalent to the photovoltaic cell only supplying power to the output load. At the same time, if the overall battery charge drops significantly, the maximum power point will be tracked again, so that the energy can be maximized. The entire control method can fully manage the photovoltaic and energy storage batteries, and at the same time combine the hardware protection circuit to ensure the stability of the equipment operation. In step S3, it specifically includes the following steps:

[0094] S31, setting a second SOC greater than the first SOC, and obtaining the mode of the power supply at the last moment;

[0095] S32, determining whether the current SOC is greater than a second SOC. In practice, the second SOC is generally set to 0.9;

[0096] If yes, proceed to step S35;

[0097] If not, proceed to step S33;

[0098] S33, determining whether the current SOC is less than a first SOC. In practice, the first SOC is generally set to 0.8;

[0099] If yes, proceed to step S4;

[0100] If not, proceed to step S34;

[0101] S34, determining whether the mode of the power supply at the last moment is the first mode;

[0102] If yes, proceed to step S4;

[0103] If not, proceed to step S35;

[0104] S35, obtaining the battery power of the photovoltaic cell and the maximum power of the photovoltaic panel, and calculating the input power of the photovoltaic cell, and then entering step S5; the calculation formula of the photovoltaic cell input power is:

[0105] P r =P mpp -P b

[0106] In the above formula, P r Represents the input power of the photovoltaic cell, P mpp Represents the battery power of the photovoltaic cell, P b Indicates the maximum power of the photovoltaic panel.

[0107] S4, setting the designated power and the first voltage, reducing the real-time voltage from the first voltage in sequence with a predetermined change step, calculating the real-time power, and marking the real-time voltage corresponding to the real-time power closest to the designated power as the maximum voltage and then locking it;

[0108] If the change step is fixed, it may be difficult to accurately track the corresponding maximum voltage. For example, when the maximum voltage is exactly in the middle of the change step, the error is the largest. At the same time, if the value of the change step is small, it may cause the process of tracking the maximum voltage to take a long time, which is troublesome. Therefore, it is necessary to make the change step variable. When it is closer to the maximum voltage, the change step is made smaller, so that the maximum voltage corresponding to the specified power can be accurately tracked. When the distance from the maximum voltage is far, the value of the change step is made larger to speed up the search for the maximum voltage. In step S4, the following steps are specifically included:

[0109] S41, setting a specified power and a first voltage; Figure 3The output characteristic curve of the photovoltaic panel is shown in the figure. According to the IU curve, the power on the left side of the maximum power point is constantly increasing with the increase of voltage, and the power on the right side of the maximum power point is constantly decreasing with the increase of voltage. At the same time, the rate of change is faster than that on the left side. When the photovoltaic works on the right side, the stability is better. According to this feature, the power tracking is designed to work from the open circuit state of the photovoltaic cell, that is, the P(0) working point in the figure above, so the first voltage is generally the voltage value corresponding to the vicinity of P(0);

[0110] S42, collecting the output voltage and output current of the photovoltaic panel and calculating the real-time power at the corresponding moment; the calculation formula of the real-time power is:

[0111] P(k)=U(k)I(k)

[0112] In the above formula, P(k) represents the real-time power at the kth moment, the kth moment is the current moment, U(k) and I(k) represent the real-time voltage and real-time current at the kth moment respectively;

[0113] S43, determining whether the real-time power of the photovoltaic panel at the current moment is greater than the specified power;

[0114] If yes, proceed to step S44;

[0115] If not, proceed to step S46;

[0116] S44, setting a power difference threshold, and determining whether the difference between the real-time power and the specified power is within the power difference threshold;

[0117] If yes, the output voltage at the current moment is marked as the maximum voltage and locked, and the process goes to step S5;

[0118] If not, proceed to step S45;

[0119] S45, according to the output voltage of the photovoltaic panel at the current moment and the output voltage at the previous moment, calculate the transition voltage whose value is between the two, and adjust the real-time voltage of the photovoltaic panel at the next moment to the transition voltage, and then return to step S42; the calculation formula of the transition voltage is:

[0120]

[0121] In the above formula, U 0 represents the transition voltage, U(k) represents the output voltage of the photovoltaic panel at the current moment, U(k-1) represents the output voltage of the photovoltaic panel at the previous moment, and τ represents the step adjustment coefficient;

[0122] S46, calculating a first voltage change according to the output voltage of the photovoltaic panel at the current moment and the output voltage at the previous moment; the calculation formula of the first voltage change is:

[0123] ΔU(1)=|U(k)-U(k-1)|

[0124] In the above formula, ΔU(1) represents the first voltage change, U(k) and U(k-1) represent the output voltage of the photovoltaic panel at the current moment and the output voltage at the previous moment respectively;

[0125] S47, judging whether the real-time power at the current moment is greater than the real-time power at the previous moment, and whether the real-time power at the previous moment is greater than the real-time power at two moments from the current moment;

[0126] If yes, proceed to step S48;

[0127] If not, the first adjustment voltage is calculated according to the output voltage of the photovoltaic panel at the current moment and the first voltage change, and is used as the output voltage of the photovoltaic panel at the next moment, and then returns to step S43; the calculation formula of the first adjustment voltage is:

[0128] U ref (1) = U(k) - ΔU(1)

[0129] In the above formula, U ref (1) represents the first adjusted voltage, U(k) represents the output voltage of the photovoltaic panel at the current moment, and ΔU(1) represents the first voltage change;

[0130] S48, determining whether the first voltage change is less than a voltage difference threshold;

[0131] If yes, the output voltage at the current moment is marked as the maximum voltage and locked, and then the process ends;

[0132] If not, the second adjustment voltage is calculated according to the first voltage change and the output voltage at the current moment; the calculation formula of the second adjustment voltage is: U ref (2) = U(k) + AΔU(1)

[0133] In the above formula, U ref (2) represents the second adjusted voltage, U(k) represents the output voltage of the photovoltaic panel at the current moment, A represents the voltage adjustment coefficient, and ΔU(1) represents the first voltage change.

[0134] S5. Construct a voltage-current dual closed-loop control circuit based on constant voltage output, voltage feedforward and current feedforward.

[0135] like Figure 4As shown in the figure, the basic principle of the voltage-current dual closed-loop controller is to compare the command voltage with the actual output voltage sampling value, send the calculated difference to the PI regulator for calculation, and finally get the current command value. Then, the difference between the calculated current command and the actual current is calculated by the PI regulator to get the duty cycle of the switch, and achieve stable voltage output through continuous adjustment. According to the control block diagram of the voltage loop and the current loop, in the adjustment process of the voltage loop, the current command is calculated by calculating the error and the feedback value of the inductor current. The current loop also uses the same method to finally get the duty cycle value. When the voltage feedforward is introduced, the adjustment process of the current loop is only determined by the PI control of the voltage loop. If the converter works stably for a period of time, if the external environment suddenly changes, the adjustment speed of the system will slow down. However, if u0 is superimposed on the output of the current inner loop, the useless adjustment process of PI can be avoided and the adjustment speed can be improved. In other words, it is necessary to introduce output voltage feedforward to improve the adjustment performance of the system. By superimposing the feedforward voltage and the inductor current value i L The control of the output command is jointly determined. Compared with the controller without feedforward, the system has a faster response speed and improves the dynamic performance of the entire system. The control block diagram after the introduction of voltage feedforward is as follows: Figure 5 shown.

[0136] Furthermore, when multiple power supplies are used in parallel, the power supply of the intelligent building intercom system adopts droop control. The droop control strategy block diagram of the power supply of the intelligent building intercom system is as follows: Figure 6 As shown, the droop control transfer function block diagram is as follows Figure 7 As shown in the figure, K d represents the droop coefficient of the controller, Δi and Δu are the output current and no-load output voltage of the power supply respectively, G i (s) is the calculated current transfer function, G u (s) is the transfer function for calculating voltage, G PIi (s) is the current loop controller, G PIu (s) is a voltage loop controller. The control method is to introduce a current feedback instruction on the basis of a voltage-current double closed loop to work. The load power distribution method is obtained through the deviation between the actual voltage and the reference voltage, and then the control instruction of the current loop is calculated by the instruction. The current instruction finally obtains the actual duty cycle according to the deviation of the actual output current to realize the control of the power supply device. Because it is necessary to ensure that the closed-loop controller works stably, in step S5, the following steps are specifically included:

[0137] S51, constructing a voltage-current dual closed-loop control circuit based on maximum voltage constant voltage output, voltage feedforward and then current feedforward;

[0138] S52, setting the relationship between the circuit parameters in the voltage-current dual closed-loop control circuit; the circuit parameters satisfy the following relationship:

[0139]

[0140] In the above formula, Δu r is the output voltage disturbance change, u N The voltage difference between the maximum voltage corresponding to the specified power of the photovoltaic panel and the actual output voltage, K d is the droop coefficient of the controller, Δi is the output current disturbance change of the power supply, u0 is the output voltage when no load, i ref is the output current of the photovoltaic panel corresponding to the specified power, i L is the actual value of the inductor current, du0 is the voltage change, G PIu (s) is the voltage loop controller, G PIi (s) is the current loop controller;

[0141] S53, setting a transfer function between the voltage disturbance and the current disturbance; the transfer function between the voltage disturbance and the current disturbance is:

[0142]

[0143] In the above formula, Δu0 is the disturbance change of output voltage when no-load, K d is the droop coefficient of the controller, Δi L is the disturbance change of the inductor current, du0 is the voltage change, R is the resistance value of the inductor, sL represents the wire resistance of the loop, K d (s) represents the control function of the droop coefficient, G PIu (s) is the voltage loop controller, G PIi (s) is the current loop controller.

[0144] The above implementation methods have been described in detail. Specific examples are used herein to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the method of the present invention and its core idea. At the same time, for those skilled in the art, according to the idea of ​​the present invention, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as a limitation on the present invention.

Claims

1. A control method for a building intercom system, comprising: A photovoltaic control unit (1), the photovoltaic control unit (1) being used to convert the input voltage of the direct current input by the photovoltaic panel into a specified voltage value according to the voltage storage requirement of the energy storage unit (2); An energy storage unit (2), the energy storage unit (2) being used to calculate the difference between a first power of electric energy output by the photovoltaic control unit (1) and a second power of electric energy required by the building intercom device to obtain a third power, and when the third power is greater than or equal to 0, storing the electric energy of the third power, and when the third power is less than 0, the multi-power source outputs a stable voltage through a voltage-current dual closed-loop control circuit; A power output unit (3), the power output unit (3) being used to output the electric energy stored in the energy storage unit (2) to the building intercom device in a constant current or constant voltage manner; Characterized in that the control method comprises the following steps: S1, setting a first mode and a second mode for operation of the building intercom system, and setting a first SOC to divide two SOC first threshold ranges corresponding to the first mode and the second mode; S2. Determine whether the power supply enters the first mode according to whether the current SOC of the building intercom system power supply is less than the first SOC; If yes, the first mode is entered and step S4 is entered; If not, enter the second mode and proceed to step S3; S3, obtaining the battery power of the photovoltaic cell and the maximum power of the photovoltaic panel, and calculating the input power of the photovoltaic cell according to the difference between the two so that the SOC is less than or equal to 1, and then entering step S5; S4. Set the specified power and the first voltage, reduce the real-time voltage from the first voltage in a predetermined step size, calculate the real-time power, and mark the real-time voltage corresponding to the real-time power closest to the specified power as the maximum voltage and then lock it. The first voltage is the voltage of the photovoltaic cell in the open circuit state, that is, the voltage value at the intersection of the IU characteristic curve of the photovoltaic panel and the x-axis. S5. Construct a voltage-current dual closed-loop control circuit based on constant voltage output, voltage feedforward and current feedforward.

2. The control method according to claim 1, characterized in that: The photovoltaic control unit (1) is a direct current boost circuit.

3. The control method according to claim 1, characterized in that: The power output unit (3) is a direct current step-down circuit.

4. The control method according to claim 1, characterized in that: In step S3, the following steps are specifically included: S31, setting a second SOC greater than the first SOC, and obtaining the mode of the power supply at the last moment; S32, determining whether the current SOC is greater than the second SOC; If yes, proceed to step S35; If not, proceed to step S33; S33, determining whether the current SOC is less than the first SOC; If yes, proceed to step S4; If not, proceed to step S34; S34, determining whether the mode of the power supply at the last moment is the first mode; If yes, proceed to step S4; If not, proceed to step S35; S35, obtaining the battery power of the photovoltaic cell and the maximum power of the photovoltaic panel, and calculating the input power of the photovoltaic cell, and then entering step S5; the calculation formula of the photovoltaic cell input power is: P r =P mpp -P b In the above formula, P r Represents the input power of the photovoltaic cell, P mpp Represents the battery power of the photovoltaic cell, P b Indicates the maximum power of the photovoltaic panel.

5. The control method according to claim 1, characterized in that: In step S4, the following steps are specifically included: S41, setting a specified power and a first voltage; S42, collecting the output voltage and output current of the photovoltaic panel and calculating the real-time power at the corresponding moment; the calculation formula of the real-time power is: P(k)=U(k)I(k) In the above formula, P(k) represents the real-time power at the kth moment, the kth moment is the current moment, U(k) and I(k) represent the real-time voltage and real-time current at the kth moment respectively; S43, determining whether the real-time power of the photovoltaic panel at the current moment is greater than the specified power; If yes, proceed to step S44; If not, proceed to step S46; S44, setting a power difference threshold, and determining whether the difference between the real-time power and the specified power is within the power difference threshold; If yes, the output voltage at the current moment is marked as the maximum voltage and locked, and the process goes to step S5; If not, proceed to step S45; S45, according to the output voltage of the photovoltaic panel at the current moment and the output voltage at the previous moment, calculate the transition voltage whose value is between the two, and adjust the real-time voltage of the photovoltaic panel at the next moment to the transition voltage, and then return to step S42; the calculation formula of the transition voltage is: In the above formula, U 0 represents the transition voltage, U(k) represents the output voltage of the photovoltaic panel at the current moment, U(k-1) represents the output voltage of the photovoltaic panel at the previous moment, and τ represents the step adjustment coefficient; S46, calculating a first voltage change according to the output voltage of the photovoltaic panel at the current moment and the output voltage at the previous moment; the calculation formula of the first voltage change is: ΔU(1)=|U(k)-U(k-1)| In the above formula, ΔU(1) represents the first voltage change, U(k) and U(k-1) represent the output voltage of the photovoltaic panel at the current moment and the output voltage at the previous moment respectively; S47, judging whether the real-time power at the current moment is greater than the real-time power at the previous moment, and whether the real-time power at the previous moment is greater than the real-time power at two moments from the current moment; If yes, proceed to step S48; If not, the first adjustment voltage is calculated according to the output voltage of the photovoltaic panel at the current moment and the first voltage variation, and is used as the output voltage of the photovoltaic panel at the next moment, and then returns to step S43; the calculation formula of the first adjustment voltage is: U ref (1)=U(k)-ΔU(1) In the above formula, U ref (1) represents the first adjusted voltage, U(k) represents the output voltage of the photovoltaic panel at the current moment, and ΔU(1) represents the first voltage change; S48, determining whether the first voltage change is less than a voltage difference threshold; If yes, the output voltage at the current moment is marked as the maximum voltage and locked, and then the process ends; If not, the second adjustment voltage is calculated according to the first voltage change and the output voltage at the current moment; the calculation formula of the second adjustment voltage is: U ref (2) = U(k) + AΔU(1) In the above formula, U ref (2) represents the second adjusted voltage, U(k) represents the output voltage of the photovoltaic panel at the current moment, A represents the voltage adjustment coefficient, and ΔU(1) represents the first voltage change.

6. The control method according to claim 1, characterized in that: In step S5, the following steps are specifically included: S51, constructing a voltage-current dual closed-loop control circuit based on maximum voltage constant voltage output, voltage feedforward and then current feedforward; S52, setting the relationship between the circuit parameters in the voltage-current dual closed-loop control circuit; the circuit parameters satisfy the following relationship: In the above formula, Δu r is the output voltage disturbance change, u N The voltage difference between the maximum voltage corresponding to the specified power of the photovoltaic panel and the actual output voltage, K d is the droop coefficient of the controller, Δi is the output current disturbance change of the power supply, u0 is the output voltage when no load, i ref is the output current of the photovoltaic panel corresponding to the specified power, i L is the actual value of the inductor current, du0 is the voltage change, G PIu (s) is the voltage loop controller, G PIi (s) is the current loop controller; S53, setting a transfer function between the voltage disturbance and the current disturbance; the transfer function between the voltage disturbance and the current disturbance is: In the above formula, ΔU0 is the disturbance change of output voltage when no-load, K d is the droop coefficient of the controller, Δi L is the disturbance change of the inductor current, R is the resistance value of the inductor, sL represents the wire resistance of the loop, K d (s) represents the control function of the droop coefficient, G PIu (s) is the voltage loop controller, G PIi (s) is the current loop controller.

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