Converter start-up control method, apparatus and system, and converter and air-conditioning system

Abstract

The present disclosure relates to a converter start-up control method, apparatus and system, and a converter and an air-conditioning system. The inverter start-up control method comprises: on the basis of whether at least one of a photovoltaic system and an energy storage system is connected to a converter, determining an operating mode of the converter; in the operating mode, charging a bus capacitor of the converter by means of a resistor, so as to establish a bus voltage; on the basis of the value of the bus voltage, and the amplitude, phase and frequency of a power grid voltage, determining an angle compensation amount and a voltage compensation amount for the operating mode; and on the basis of the angle compensation amount and the voltage compensation amount for the operating mode, performing compensation on the current angle and the current voltage for start-up of the converter, and starting up the converter according to a compensated angle and a compensated angle voltage.

Description

Methods, devices and systems for inverter start-up control; inverters and air conditioning systems

[0001] Cross-references to related applications

[0002] This application is based on and claims priority to CN application number CN202411688029.3, filed on November 25, 2024, the disclosure of which is incorporated herein by reference in its entirety. Technical Field

[0003] This disclosure relates to the field of inverters, and in particular to a converter start-up control method, apparatus and system, converter and air conditioning system. Background Technology

[0004] With the technological advancements in photovoltaic air conditioners and energy routers, their core controllers, such as converters, need to establish a controllable DC bus voltage during startup. However, due to the lag in the control timing when detecting the grid voltage and frequency, there are still discrepancies between these readings and the actual grid voltage and frequency. Starting grid connection under these discrepancies can easily lead to current spikes, affecting grid stability. Summary of the Invention

[0005] According to one aspect of this disclosure, a converter startup control method is provided, comprising:

[0006] Determine the operating mode of the converter based on whether at least one of the photovoltaic system and energy storage system is connected to the converter.

[0007] In the aforementioned operating mode, the bus capacitor of the converter is charged through a resistor to establish the bus voltage;

[0008] Based on the value of the bus voltage, the amplitude, phase, and frequency of the grid voltage, determine the angle compensation amount and voltage compensation amount of the operating mode;

[0009] Based on the angle compensation and voltage compensation amounts of the operating mode, the current angle and voltage of the converter are compensated for, and the converter is started according to the compensated angle and voltage.

[0010] In some embodiments of this disclosure, determining the operating mode of the converter based on whether at least one of the photovoltaic system and the energy storage system is connected to the converter includes at least one of the following steps:

[0011] When a photovoltaic system is connected to a converter, the converter's operating mode is determined to be the first operating mode.

[0012] When the photovoltaic system is not connected to the converter but the energy storage system is connected to the converter, the converter's operating mode is determined to be the second operating mode.

[0013] When neither the photovoltaic system nor the energy storage system is connected to the converter, the converter's operating mode is determined to be the third operating mode.

[0014] In some embodiments of this disclosure, the step of charging the bus capacitor of the converter through a resistor to establish the bus voltage in the operating mode includes at least one of the following steps:

[0015] In the first operating mode, a photovoltaic system is used to charge the bus capacitor of the converter through a resistor to establish the bus voltage.

[0016] In the second operating mode, the energy storage system charges the bus capacitor of the converter through a resistor to establish the bus voltage;

[0017] In the third operating mode, the mains voltage is used to charge the converter's bus capacitor through a resistor to establish the bus voltage.

[0018] In some embodiments of this disclosure, the step of using a photovoltaic system to charge the bus capacitor of the converter through a resistor to establish the bus voltage includes:

[0019] Determine whether the current photovoltaic voltage is within the predetermined photovoltaic voltage range;

[0020] When the current photovoltaic voltage is within the predetermined photovoltaic voltage range, close the first charging switch and use the photovoltaic system to charge the bus capacitor of the converter through a resistor.

[0021] Check if the bus voltage has been established;

[0022] Once the bus voltage is established, close the first operating switch, and the converter outputs inverter voltage.

[0023] In some embodiments of this disclosure, the step of using an energy storage system to charge the bus capacitor of the converter through a resistor to establish the bus voltage includes:

[0024] Determine whether the energy storage state of charge is within a predetermined range;

[0025] When the energy storage state of charge is within a predetermined range, the second charging switch is closed, and the energy storage system charges the bus capacitor of the converter through a resistor.

[0026] Check if the bus voltage has been established;

[0027] Once the bus voltage is established, close the second operating switch, and the converter outputs inverter voltage.

[0028] In some embodiments of this disclosure, the step of charging the bus capacitor of the converter with grid voltage through a resistor to establish the bus voltage includes:

[0029] Determine whether the AC voltage is within the predetermined voltage range;

[0030] When the AC voltage is within the predetermined voltage range, close the third charging switch and use the grid voltage to charge the bus capacitor of the converter through a resistor.

[0031] Check if the bus voltage has been established;

[0032] Once the bus voltage is established, close the third operating switch, and the converter outputs inverter voltage.

[0033] In some embodiments of this disclosure, the step of compensating the current angle and current voltage of the converter for startup based on the angle compensation amount and voltage compensation amount of the operating mode, and starting the converter according to the compensated angle and compensated voltage, includes:

[0034] When the angle compensation is zero and the voltage compensation is zero, the converter is started according to the current angle and voltage at which the converter is started.

[0035] When the angle compensation amount is not zero and the voltage compensation amount is not zero, the starting angle of the converter is compensated according to the angle compensation amount of the working mode, and the starting voltage of the converter is compensated according to the voltage compensation amount of the working mode, and the converter is started according to the compensated angle and voltage.

[0036] In some embodiments of this disclosure, the step of compensating the current angle and current voltage of the converter for startup based on the angle compensation amount and voltage compensation amount of the operating mode, and starting the converter according to the compensated angle and compensated voltage, includes:

[0037] When the angle compensation is zero and the voltage compensation is not zero, the voltage at which the converter starts is compensated according to the voltage compensation of the working mode, and the converter is started according to the current angle at which the converter starts and the compensated voltage.

[0038] When the angle compensation is not zero and the voltage compensation is zero, the starting angle of the converter is compensated according to the angle compensation of the working mode, and the converter is started according to the current starting voltage and the compensated angle.

[0039] In some embodiments of this disclosure, determining the angle compensation and voltage compensation amounts for the operating mode based on the value of the bus voltage and the amplitude, phase, and frequency of the grid voltage includes:

[0040] Obtain the amplitude, phase, and frequency of the grid voltage;

[0041] The amplitude, phase, and frequency of the grid voltage are used as the target amplitude, target phase, and target frequency of the inverter voltage;

[0042] The inverter voltage is generated based on the bus voltage, the target amplitude, target phase, and target frequency of the inverter voltage.

[0043] Obtain the actual amplitude and actual phase of the inverter voltage;

[0044] The angle compensation amount and voltage compensation amount are determined based on the actual amplitude and phase of the inverter voltage and the amplitude and phase of the grid voltage.

[0045] In some embodiments of this disclosure, generating the inverter voltage based on the bus voltage and the target amplitude, target phase, and target frequency of the inverter voltage includes:

[0046] Based on the bus voltage, the target amplitude, target phase, and target frequency of the inverter voltage, determine the inverter modulation wave required to generate the inverter voltage;

[0047] The inverter voltage is generated based on the bus voltage and the inverter modulation wave.

[0048] According to another aspect of this disclosure, a control device is provided, comprising:

[0049] The operating mode determination module is configured to determine the operating mode of the converter based on whether at least one of the photovoltaic system and the energy storage system is connected to the converter.

[0050] The bus voltage establishment module is configured to establish the bus voltage by charging the bus capacitor of the converter through a resistor in the operating mode.

[0051] The compensation amount determination module is configured to determine the angle compensation amount and voltage compensation amount of the operating mode based on the value of the bus voltage and the amplitude, phase and frequency of the grid voltage.

[0052] The start-up control module is configured to compensate the current angle and voltage of the converter based on the angle compensation and voltage compensation amount of the operating mode, and start the converter according to the compensated angle and voltage.

[0053] According to another aspect of this disclosure, a control device is provided, comprising:

[0054] The memory is configured to store instructions; and

[0055] The processor is configured to execute the instructions, causing the control device to implement the converter start-up control method as described in any of the above embodiments.

[0056] According to another aspect of this disclosure, a converter start-up control system is provided, including the control device as described in any of the above embodiments.

[0057] In some embodiments of this disclosure, the converter start-up control system further includes:

[0058] A photovoltaic system access control circuit is provided, wherein the photovoltaic system access control circuit includes a first charging switch, a first resistor, and a first operating switch. The first charging switch and the first resistor are connected in series and then in parallel with the first operating switch. The first charging switch is configured to charge the bus capacitor of the inverter through the first resistor when it is closed. The first operating switch is configured to close when the bus voltage is established, so that the inverter outputs the inverter voltage.

[0059] In some embodiments of this disclosure, the converter start-up control system further includes:

[0060] The energy storage system is connected to a control circuit, which includes a second charging switch, a second resistor, and a second operating switch. The second charging switch and the second resistor are connected in series and then in parallel with the second operating switch. The second charging switch is configured to charge the bus capacitor of the converter through the second resistor when it is closed. The second operating switch is configured to close when the bus voltage is established, so that the converter outputs the inverter voltage.

[0061] In some embodiments of this disclosure, the converter start-up control system further includes:

[0062] A grid access control circuit includes a first rectifier, a third charging switch, a third resistor, and a third operating switch. The first rectifier is configured to convert AC grid voltage into DC voltage. The third charging switch and the third resistor are connected in series and then in parallel with the third operating switch. The third charging switch is configured to, when closed, allow the grid voltage to charge the bus capacitor of the converter through the first rectifier and the third resistor. The third operating switch is configured to close when the bus voltage is established, allowing the converter to output an inverter voltage.

[0063] In some embodiments of this disclosure, the converter start-up control system further includes:

[0064] The first acquisition module is configured to acquire bus voltage;

[0065] The second acquisition module is configured to acquire the amplitude, phase, and frequency of the grid voltage;

[0066] The third acquisition module is configured to acquire the actual amplitude, actual phase, and actual frequency of the inverter voltage.

[0067] In some embodiments of this disclosure, the converter start-up control system further includes:

[0068] An AC switch is provided, wherein the AC switch is located between the power grid and the converter; a second acquisition module is configured to acquire the amplitude, phase, and frequency of the power grid voltage between the power grid and the AC switch; and a third acquisition module is configured to acquire the actual amplitude, actual phase, and actual frequency of the inverter voltage between the AC switch and the converter.

[0069] According to another aspect of this disclosure, a converter system is provided, including a converter start-up control system as described in any of the above embodiments.

[0070] According to another aspect of this disclosure, an air conditioning system is provided, including a converter system as described in any of the above embodiments.

[0071] According to another aspect of this disclosure, a computer-readable storage medium is provided, wherein the computer-readable storage medium stores computer instructions that, when executed by a processor, implement the converter start-up control method as described in any of the above embodiments.

[0072] According to another aspect of this disclosure, a computer program product is provided, comprising a computer program, wherein when the computer program is executed by a processor, it implements the converter start-up control method as described in any of the above embodiments. Attached Figure Description

[0073] To more clearly illustrate the technical solutions in the embodiments of this disclosure or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this disclosure. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0074] Figure 1 is a schematic diagram of the multi-mode converter system.

[0075] Figure 2 is a schematic diagram of some embodiments of the converter start-up control method disclosed herein.

[0076] Figure 3 is a schematic diagram of some embodiments of the converter start-up control system of this disclosure.

[0077] Figure 4 is a schematic diagram of some other embodiments of the converter start-up control method disclosed herein.

[0078] Figure 5 is a schematic diagram of the structure of some embodiments of the control device of this disclosure.

[0079] Figure 6 is a schematic diagram of the structure of some other embodiments of the control device of this disclosure.

[0080] Figure 7 is a schematic diagram of some other embodiments of the converter start-up control system of this disclosure. Detailed Implementation

[0081] The technical solutions of the embodiments of this disclosure will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this disclosure, and not all embodiments. The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit this disclosure or its application or use. All other embodiments obtained by those skilled in the art based on the embodiments of this disclosure without creative effort are within the scope of protection of this disclosure.

[0082] Unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps set forth in these embodiments do not limit the scope of this disclosure.

[0083] At the same time, it should be understood that, for ease of description, the dimensions of the various parts shown in the accompanying drawings are not drawn according to actual scale.

[0084] Techniques, methods, and equipment known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and equipment should be considered part of the specification.

[0085] In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values.

[0086] It should be noted that similar labels and letters in the following figures indicate similar items; therefore, once an item is defined in one figure, it does not need to be discussed further in subsequent figures.

[0087] The inventors discovered through research that related technologies compensate for deviations manually, determining voltage and frequency discrepancies by hand and then providing compensation. However, these methods require calculation and compensation for each unit, wasting manpower and time. Figure 1 shows a schematic diagram of a multi-mode converter system. As shown in Figure 1, the interfaces of related converters may be connected to photovoltaics and energy storage, or they may not be connected to either. Engineering applications are complex and unpredictable, and related technologies lack bus setup and start-up control methods for converter application systems under different conditions.

[0088] In view of at least one of the above technical problems, this disclosure provides a converter start-up control method, device and system, converter and air conditioning system, which can correct the voltage angle and amplitude according to different operating modes of the converter, thereby reducing the start-up peak and reducing the start-up current impact.

[0089] This disclosure proposes a unified busbar establishment method and a grid voltage and frequency compensation system for converter application systems under different conditions. The following specific embodiments illustrate this disclosure.

[0090] Figure 2 is a schematic diagram of some embodiments of the converter start-up control method of this disclosure. The embodiments of Figure 2 can be executed by the converter start-up control device, the converter start-up control system, the converter system, or the air conditioning system of this disclosure. As shown in Figure 2, the method of the embodiments of Figure 2 may include at least one of steps 1 to 4.

[0091] Step 1: Determine the operating mode of the converter based on whether at least one of the photovoltaic system and the energy storage system is connected to the converter.

[0092] In some embodiments of this disclosure, step 1 may include at least one of steps 11 to 13, and the order of steps 11 to 13 may be adjusted.

[0093] Step 11: When the photovoltaic system is connected to the converter, determine the converter's operating mode as the first operating mode.

[0094] The embodiments disclosed above give higher priority to photovoltaics. When both photovoltaics and energy storage are connected, the photovoltaic system charges the bus capacitor of the converter through a resistor to establish the bus voltage. This allows for full utilization of photovoltaic power generation, better achieving energy conservation and energy storage in the energy storage system.

[0095] Step 12: When the photovoltaic system is not connected to the converter and the energy storage system is connected to the converter, determine the converter's operating mode as the second operating mode.

[0096] Step 13: If the photovoltaic system is not connected to the converter and the energy storage system is not connected to the converter, determine the converter's operating mode as the third operating mode.

[0097] The embodiments of this disclosure distinguish different operating modes based on whether photovoltaic and energy storage are connected. Therefore, this disclosure can use different power sources (photovoltaic system, energy storage system, and AC power) to charge the bus capacitor according to different operating modes, thereby improving the system's adaptability and enhancing energy-saving performance.

[0098] Step 2: In the operating mode, the bus capacitor of the converter is charged by a resistor to establish the bus voltage.

[0099] In some embodiments of this disclosure, step 2 may include at least one of steps 21 to 23, and the order of steps 21 to 23 may be adjusted.

[0100] Step 21: In the first operating mode, the photovoltaic system charges the bus capacitor of the converter through a resistor to establish the bus voltage.

[0101] The embodiments disclosed above give higher priority to photovoltaics. When both photovoltaics and energy storage are connected, the photovoltaic system charges the bus capacitor of the converter through a resistor to establish the bus voltage. This allows for full utilization of photovoltaic power generation, better achieving energy conservation and energy storage in the energy storage system.

[0102] In some embodiments of this disclosure, step 21 may include at least one of steps 211 to 214, and the order of steps 211 to 214 may be adjusted.

[0103] Step 211: Determine whether the current photovoltaic voltage is within the predetermined photovoltaic voltage range.

[0104] Step 212: When the current photovoltaic voltage is within the predetermined photovoltaic voltage range, close the first charging switch K6 as shown in Figure 3, and use the photovoltaic system to charge the bus capacitor of the converter through the resistor.

[0105] Figure 3 is a schematic diagram of some embodiments of the converter start-up control system of this disclosure. The converter start-up control system of this disclosure includes the control device and photovoltaic system access control circuit in any of the above embodiments of this disclosure.

[0106] In some embodiments of this disclosure, as shown in FIG3, the photovoltaic system access control circuit may include a first charging switch K6, a first resistor R1, and a first operating switch K1. The first charging switch K6 and the first resistor R1 are connected in series and then connected in parallel with the first operating switch K1. The first charging switch K6 is configured to charge the bus capacitor of the inverter through the first resistor R1 when it is closed. The first operating switch K1 is configured to close when the bus voltage is established, so that the inverter outputs the inverter voltage.

[0107] Step 213: Check whether the bus voltage has been established.

[0108] Step 214: With the bus voltage established, close the first operating switch K1, and the converter outputs the inverter voltage.

[0109] In the embodiments of this disclosure, regardless of whether energy storage is connected, the first operating mode is used when photovoltaic (PV) is connected. In this mode, DC power can be established by charging the bus via PV. The embodiments of this disclosure preferentially use a PV system for bus capacitor charging, thereby achieving energy savings.

[0110] In the embodiments described above, after the bus voltage is established, an inverter voltage is output. By comparing the inverter voltage with the grid voltage, the angle compensation amount and voltage compensation amount can be determined to compensate for the starting angle and voltage of the converter, thereby reducing the starting current surge and achieving stable starting of the converter.

[0111] The embodiments described above use a resistor to connect to the bus capacitor of the converter to reduce the charging current and protect the bus capacitor from damage; simultaneously, it reduces voltage spikes and maintains the stability of the bus voltage. Once the bus voltage is established, the short-circuit resistor is directly connected to the photovoltaic voltage to provide a large current, which is to more effectively utilize the energy output by the photovoltaic system and achieve energy savings.

[0112] Step 22: In the second operating mode, the energy storage system charges the bus capacitor of the converter through a resistor to establish the bus voltage.

[0113] The embodiments of this disclosure, when energy storage is connected but photovoltaic (PV) power is not, operate in a second mode. In the absence of PV power, the energy storage system is preferentially used to charge the bus capacitor. DC charging can charge the bus capacitor faster than AC charging and eliminates the need for AC-to-DC conversion, thus achieving energy savings. The energy stored in the energy storage system in these embodiments may be from previously generated PV power; therefore, prioritizing the use of the energy storage system for charging compared to the grid also saves grid energy.

[0114] In some embodiments of this disclosure, step 22 may include at least one of steps 221 to 224, and the order of steps 221 to 224 may be adjusted.

[0115] Step 221: Determine whether the energy storage state of charge is within the predetermined range.

[0116] Step 222: When the energy storage charge state is within the predetermined range, close the second charging switch K7 as shown in Figure 3, and use the energy storage system to charge the bus capacitor of the converter through a resistor.

[0117] In some embodiments of this disclosure, the converter start-up control system shown in FIG3 may further include: an energy storage system access control circuit, wherein the energy storage system access control circuit includes a second charging switch K7, a second resistor R2, and a second operating switch K2. The second charging switch K7 and the second resistor R2 are connected in series and then in parallel with the second operating switch K2. The second charging switch K7 is configured to charge the bus capacitor of the converter through the second resistor R2 when it is closed. The second operating switch K2 is configured to close when the bus voltage is established, so that the converter outputs an inverter voltage.

[0118] Step 223: Check if the bus voltage has been established.

[0119] Step 224: With the bus voltage established, close the second working switch K2 as shown in Figure 3, and the converter outputs the inverter voltage.

[0120] In the above embodiments of this disclosure, when photovoltaic power is not connected, the energy storage system is preferentially used to charge the bus capacitor compared with the AC power supply of the grid. DC charging can charge the bus capacitor faster than AC charging, and there is no need for the AC to DC conversion process in AC charging, thereby achieving energy saving.

[0121] In the embodiments described above, after the bus voltage is established, an inverter voltage is output. By comparing the inverter voltage with the grid voltage, the angle compensation amount and voltage compensation amount can be determined to compensate for the starting angle and voltage of the converter, thereby reducing the starting current surge and achieving stable starting of the converter.

[0122] The embodiments described above use a resistor to connect to the bus capacitor of the converter to reduce the charging current and protect the bus capacitor from damage. After the bus voltage is established, the short-circuit resistor is directly connected to the energy storage voltage to provide a large current, which is to more effectively utilize the energy output from the energy storage system and achieve energy savings.

[0123] Step 23: In the third operating mode, the mains voltage is used to charge the bus capacitor of the converter through a resistor to establish the bus voltage.

[0124] The above embodiments of this disclosure represent a third operating mode when neither photovoltaic (PV) nor energy storage is connected. In this mode, neither PV nor energy storage can establish a charging voltage on the bus; voltage can only be established by charging the bus via the AC side.

[0125] The embodiments disclosed above can use different power sources (photovoltaic system, energy storage system and AC power) to charge the bus capacitor according to different working modes, thereby improving the system's adaptability and energy-saving effect.

[0126] In some embodiments of this disclosure, step 23 may include at least one of steps 231 to 234, and the order of steps 231 to 234 may be adjusted.

[0127] Step 231: Determine whether the AC voltage is within the predetermined voltage range.

[0128] Step 232: When the AC voltage is within the predetermined voltage range, close the third charging switch K4 as shown in Figure 3, and use the grid voltage to charge the bus capacitor of the converter through the resistor.

[0129] The above embodiments of this disclosure have range requirements for the access voltage of photovoltaic and energy storage, as well as for the AC voltage operation. Therefore, the above embodiments of this disclosure require determination of the voltage range of photovoltaic, energy storage, and AC power sources.

[0130] Based on relevant technologies, the voltage is first established from the grid side. In the case of technical problems caused by connecting photovoltaic or energy storage, the above embodiments of this disclosure select the establishment of bus voltage according to the situation by automatically judging the voltage of photovoltaic, energy storage and grid side.

[0131] In some embodiments of this disclosure, the converter start-up control system shown in FIG3 may further include: a grid access control circuit, wherein the grid access control circuit includes a first rectifier 31, a third charging switch K4, a third resistor R3, and a third operating switch K5. The first rectifier is configured to convert the grid AC voltage into DC voltage. The third charging switch K4 and the third resistor are connected in series and then in parallel with the third operating switch K5. The third charging switch K4 is configured to, when closed, allow the grid voltage to charge the converter's bus capacitor through the first rectifier 31 and the third resistor R3. The third operating switch K5 is configured to close when the bus voltage is established, causing the converter to output an inverter voltage.

[0132] Step 233: Check if the bus voltage has been established.

[0133] Step 234: With the bus voltage established, close the third working switch K5 as shown in Figure 3, and the converter outputs the inverter voltage.

[0134] In the embodiments described above, after the bus voltage is established, an inverter voltage is output. By comparing the inverter voltage with the grid voltage, the angle compensation amount and voltage compensation amount can be determined to compensate for the starting angle and voltage of the converter, thereby reducing the starting current surge and achieving stable starting of the converter.

[0135] The above embodiments of this disclosure mainly use K4 and a resistor to charge the intermediate capacitor. After charging is complete, K5 is closed to bypass the resistor. Without a resistor after K5 is closed, directly energizing the bus capacitor would cause problems and damage it. K5 is a bypass switch; after charging is complete, the resistor needs to be bypassed. If it is not bypassed, the subsequent large current flowing through the circuit will result in significant losses.

[0136] The embodiments described above use a resistor to connect the converter's bus capacitor to reduce the charging current and protect the bus capacitor from damage. After the bus voltage is established, the short-circuit resistor, through a rectifier, directly connects to the grid voltage, providing a large current to more effectively utilize the energy output from the grid and achieve energy savings.

[0137] Step 3: Based on the value of the bus voltage and the amplitude, phase and frequency of the grid voltage, determine the angle compensation amount and voltage compensation amount of the operating mode.

[0138] In some embodiments of this disclosure, step 3 may include at least one of steps 31 to 35, and the order of steps 31 to 35 may be adjusted.

[0139] Step 31: Obtain the bus voltage; obtain the amplitude, phase, and frequency of the grid voltage.

[0140] Step 32: Use the amplitude, phase, and frequency of the grid voltage as the target amplitude, target phase, and target frequency of the inverter voltage.

[0141] Step 33: Generate the inverter voltage based on the bus voltage, the target amplitude, target phase, and target frequency of the inverter voltage.

[0142] In some embodiments of this disclosure, step 33 may include at least one of steps 331 and 332, and the order of steps 331 and 332 may be adjusted.

[0143] Step 331: Determine the inverter modulation wave required to generate the inverter voltage based on the bus voltage, the target amplitude, target phase, and target frequency of the inverter voltage.

[0144] In some embodiments of this disclosure, step 331 may include: determining, based on the amplitude, phase, and frequency of the bus voltage and the grid voltage, the inverter modulation wave required to generate an inverter voltage that is synchronized with the amplitude, phase, and frequency of the grid voltage.

[0145] In some embodiments of this disclosure, step 331 may include: determining the inverter modulation wave required to generate the inverter voltage according to formulas (1) and (2). Vinv=M sin(wt+θ) (1) w=2πf (2)

[0146] In formulas (1) and (2), Vinv is the inverter modulation wave; M is the target amplitude of the inverter modulation wave; f is the frequency of the grid voltage; and θ is the angle that keeps in phase with the grid voltage.

[0147] In some embodiments of this disclosure, when the magnitude of the DC voltage and the magnitude of the grid voltage are known according to formulas (1) and (2), the target amplitude M of the modulation wave can be determined, and the resulting inverter modulation wave Vinv, after being driven and controlled by high-frequency PWM modulation, produces an inverter voltage that is consistent with the magnitude, frequency, and phase of the grid voltage. Step 332: The inverter voltage is generated based on the bus voltage and the inverter modulation wave.

[0148] The embodiments of this disclosure can determine the inverter modulation wave required to generate the inverter voltage by using the bus voltage, the target amplitude, target phase, and target frequency of the inverter voltage, thereby enabling the modulation and generation of the inverter voltage. Therefore, the embodiments of this disclosure can conveniently generate the inverter voltage, and can accurately determine the angle compensation and voltage compensation amounts based on the actual amplitude and phase of the inverter voltage and the amplitude and phase of the grid voltage. Thus, the embodiments of this disclosure can further reduce startup spikes, decrease startup current inrushes, and improve the stability of converter startup.

[0149] Step 34: Obtain the actual amplitude and actual phase of the inverter voltage.

[0150] Step 35: Determine the angle compensation amount and voltage compensation amount based on the actual amplitude and phase of the inverter voltage and the amplitude and phase of the grid voltage.

[0151] In some embodiments of this disclosure, step 35 may include: generating a sine wave with the same frequency as the power grid through a DC inverter unit, filtering it through a reactor, and then comparing the voltage on the right side (point B) of AC switch K3 with the power grid voltage on the left side (point A).

[0152] In some embodiments of this disclosure, as shown in FIG3, the sine wave generated to the right of K3 (point B) is a sine wave generated by detecting the voltage angle to the left of K3. The generated sine wave will have a certain phase deviation from the sine wave of the power grid due to program processing and calculation.

[0153] In some embodiments of this disclosure, the deviation range is within the angular interval [0, 2*pi]. This angular deviation is obtained by calculating the zero-crossing points of the two waveforms and is used to compensate for the delay in the generation of a sine wave after the program samples and filters the output.

[0154] In some embodiments of this disclosure, step 35 may include: by acquiring the voltages at points A and B as shown in Figure 3, the program calculates the angle and angle deviation.

[0155] In some embodiments of this disclosure, step 35 may include: if you want to generate a sine wave on the right side of K3 that is the same as the power grid, you need to collect the amplitude, phase and frequency of the power grid. There will be a deviation between the generated sine wave and the sampled data, which is the compensation amount.

[0156] The embodiments of this disclosure use the amplitude, phase, and frequency of the grid voltage as the target amplitude, target phase, and target frequency of the inverter voltage. The inverter voltage can be generated based on the bus voltage and the target amplitude, target phase, and target frequency of the inverter voltage. Therefore, the angle compensation and voltage compensation amounts can be determined based on the actual amplitude and phase of the inverter voltage and the amplitude and phase of the grid voltage. Thus, the embodiments of this disclosure can accurately determine the angle compensation and voltage compensation amounts, thereby further reducing startup spikes, minimizing startup current impact, and improving the stability of converter startup.

[0157] Step 4: Based on the angle compensation amount and voltage compensation amount of the operating mode, compensate the current angle and current voltage of the converter for startup, and start the converter according to the compensated angle and compensated voltage.

[0158] This disclosure allows for voltage angle and amplitude correction based on different operating modes of the converter, thereby reducing startup spikes, minimizing startup current surges, and ultimately achieving stable startup of the converter.

[0159] The embodiments disclosed above can automatically select a scheme to establish the bus voltage for various situations, including those with and without photovoltaic or energy storage, thereby enabling correction of voltage amplitude and angle based on the converter mode.

[0160] The embodiments of this disclosure can automatically correct the voltage amplitude and angle according to various modes with or without photovoltaics and energy storage, thereby reducing the startup current surge. This reduces startup spikes and achieves stable startup of the converter. The embodiments of this disclosure eliminate the need for manual correction of the grid-side voltage frequency.

[0161] In some embodiments of this disclosure, step 4 may include at least one of steps 41 to 44, and the order of steps 41 to 44 may be adjusted.

[0162] Step 41: When the angle compensation is zero and the voltage compensation is zero, start the converter according to the current angle and current voltage at which the converter is started.

[0163] Step 42: When the angle compensation amount is not zero and the voltage compensation amount is not zero, the current angle of the converter startup is compensated according to the angle compensation amount of the working mode, and the current voltage of the converter startup is compensated according to the voltage compensation amount of the working mode. The converter is then started according to the compensated angle and the compensated voltage.

[0164] In the above embodiments of this disclosure, if both the angle compensation amount and the voltage compensation amount are zero, then the current values ​​are used for both the angle and the voltage; if both the angle compensation amount and the voltage compensation amount are not zero, then both the angle and the voltage are compensated.

[0165] The embodiments disclosed above achieve, for the first time, the comparison and compensation of angle and phase, thereby greatly reducing startup spikes, reducing startup current surges, and improving the stability of converter startup.

[0166] Step 43: When the angle compensation is zero and the voltage compensation is not zero, the current voltage of the converter is compensated according to the voltage compensation of the working mode, and the converter is started according to the current angle of the converter start and the compensated voltage.

[0167] Step 44: When the angle compensation amount is not zero and the voltage compensation amount is zero, compensate the current angle of the converter startup according to the angle compensation amount of the working mode, and start the converter according to the current voltage of the converter startup and the compensated angle.

[0168] In the embodiments of this disclosure, if either the angle compensation amount or the voltage compensation amount is not zero, then compensation is performed on that amount. The embodiments of this disclosure can compensate for either the angle or the voltage, thereby further reducing startup spikes, minimizing startup current surges, and improving the stability of converter startup.

[0169] Figure 4 is a schematic diagram of some other embodiments of the converter start-up control method of this disclosure. The embodiments of Figure 4 can be executed by the converter start-up control device, the converter start-up control system, the converter system, or the air conditioning system of this disclosure. As shown in Figure 4, the method of the embodiments of Figure 4 may include at least one step from steps 400 to 429, and the order of steps 400 to 429 may be adjusted.

[0170] Step 400: The system is powered on and connected to the power grid.

[0171] Step 401: Check if the photovoltaic system is connected to the converter. If the photovoltaic system is connected to the converter, proceed to step 402; otherwise, if the photovoltaic system is not connected to the converter, proceed to step 411.

[0172] Step 402: When the photovoltaic system is connected to the converter, determine the converter's operating mode as the first operating mode.

[0173] Step 403: Determine whether the current photovoltaic voltage is within the predetermined photovoltaic voltage range. If the photovoltaic voltage is within the predetermined photovoltaic voltage range, proceed to step 404; otherwise, if the photovoltaic voltage is not within the predetermined photovoltaic voltage range, continue to execute step 403 within a predetermined time, that is, continue to determine whether the current photovoltaic voltage is within the predetermined photovoltaic voltage range within the predetermined time; if the determination continues within the predetermined time and the current photovoltaic voltage is still not within the predetermined photovoltaic voltage range, proceed to step 411.

[0174] In some embodiments of this disclosure, the predetermined photovoltaic voltage range may be a predetermined voltage range for starting up the photovoltaic system.

[0175] In some embodiments of this disclosure, the predetermined photovoltaic voltage range can be the range from the minimum value of MPPT (Maximum Power Point Tracking) to the maximum value of MPPT, i.e., [mppt_min, mppt_max].

[0176] Step 404: If the current photovoltaic voltage is within the predetermined photovoltaic voltage range, close the first charging switch K6 as shown in Figure 3, and use the photovoltaic system to charge the bus capacitor of the converter through a resistor; and detect whether the bus voltage is established. If the bus voltage is established, proceed to step 406; otherwise, if the bus voltage is not established, proceed to step 405.

[0177] Step 405: Determine if there is a charging fault and clear the fault. Then proceed to step 402.

[0178] Step 406: Determine that charging is complete, close the first working switch K1 as shown in Figure 3, and output the inverter voltage.

[0179] Step 407: Determine whether there is a deviation between the actual amplitude and phase of the inverter voltage and the amplitude and phase of the grid voltage. If there is no deviation between the actual amplitude of the inverter voltage and the amplitude of the grid voltage, and also no deviation between the actual phase of the inverter voltage and the phase of the grid voltage, proceed to step 410; if there is a deviation between at least one of the actual amplitude of the inverter voltage and the amplitude of the grid voltage, and between the actual phase of the inverter voltage and the grid voltage, proceed to step 408.

[0180] Step 408: Calculate the voltage and phase deviation (compensation amount).

[0181] In some embodiments of this disclosure, step 408 may include: determining the angle compensation amount and the voltage compensation amount based on the actual amplitude and actual phase of the inverter voltage and the amplitude and phase of the grid voltage.

[0182] Step 409: Power on the device according to the value after adding the compensation amount.

[0183] In some embodiments of this disclosure, step 409 may include: when the angle compensation amount is not zero and the voltage compensation amount is not zero, compensating the current starting angle of the converter according to the angle compensation amount of the operating mode, compensating the current starting voltage of the converter according to the voltage compensation amount of the operating mode, and starting the converter according to the compensated angle and the compensated voltage; when the angle compensation amount is zero and the voltage compensation amount is not zero, compensating the current starting voltage of the converter according to the voltage compensation amount of the operating mode, and starting the converter according to the current starting angle and the compensated voltage; when the angle compensation amount is not zero and the voltage compensation amount is zero, compensating the current starting angle of the converter according to the angle compensation amount of the operating mode, and starting the converter according to the current starting voltage and the compensated angle.

[0184] Step 410: Power on the machine at the current angle.

[0185] In some embodiments of this disclosure, step 410 may include: starting the converter according to the current angle and current voltage at which the converter is started, when the angle compensation amount is zero and the voltage compensation amount is zero.

[0186] Step 411: Check if the energy storage system is connected. If the energy storage system is connected to the converter, proceed to step 412; otherwise, if the energy storage system is not connected to the converter, proceed to step 421.

[0187] Step 412: When the photovoltaic system is not connected to the converter but the energy storage system is connected to the converter, determine the converter's operating mode as the second operating mode.

[0188] Step 413: Determine whether the energy storage state of charge (SOC) is within a predetermined range. If the energy storage SOC is within the predetermined range, proceed to step 414; otherwise, if the energy storage SOC is not within the predetermined range, continue to execute step 413 within a predetermined time, that is, continuously determine whether the energy storage SOC is within the predetermined range within the predetermined time; if the energy storage SOC is still not within the predetermined range within the predetermined time, proceed to step 421.

[0189] In some embodiments of this disclosure, the predetermined interval range can be a range of [20%, 100%].

[0190] Step 414: If the energy storage state of charge is within a predetermined range, close the second charging switch K7 as shown in Figure 3, and use the energy storage system to charge the converter's bus capacitor through a resistor; and check whether the bus voltage is established. If the bus voltage is established, proceed to step 416; otherwise, if the bus voltage is not established, proceed to step 415.

[0191] Step 415: Determine if there is a charging fault and clear the fault. Then proceed to step 402.

[0192] Step 416: With the bus voltage established, close the second working switch K2 as shown in Figure 3, and the converter outputs the inverter voltage.

[0193] Step 417: Determine whether there is a deviation between the actual amplitude and phase of the inverter voltage and the amplitude and phase of the grid voltage. If there is no deviation between the actual amplitude of the inverter voltage and the amplitude of the grid voltage, and also no deviation between the actual phase of the inverter voltage and the phase of the grid voltage, proceed to step 420; if there is a deviation between at least one of the actual amplitude of the inverter voltage and the amplitude of the grid voltage, and between the actual phase of the inverter voltage and the grid voltage, proceed to step 418.

[0194] Step 418: Calculate the voltage and phase deviation (compensation amount).

[0195] In some embodiments of this disclosure, step 418 may include: determining the angle compensation amount and the voltage compensation amount based on the actual amplitude and actual phase of the inverter voltage and the amplitude and phase of the grid voltage.

[0196] Step 419: Power on the device according to the value after adding the compensation amount.

[0197] In some embodiments of this disclosure, step 419 may include: when the angle compensation amount is not zero and the voltage compensation amount is not zero, compensating the current starting angle of the converter according to the angle compensation amount of the operating mode, compensating the current starting voltage of the converter according to the voltage compensation amount of the operating mode, and starting the converter according to the compensated angle and the compensated voltage; when the angle compensation amount is zero and the voltage compensation amount is not zero, compensating the current starting voltage of the converter according to the voltage compensation amount of the operating mode, and starting the converter according to the current starting angle and the compensated voltage; when the angle compensation amount is not zero and the voltage compensation amount is zero, compensating the current starting angle of the converter according to the angle compensation amount of the operating mode, and starting the converter according to the current starting voltage and the compensated angle.

[0198] Step 420: Power on the machine at the current angle.

[0199] In some embodiments of this disclosure, step 420 may include: starting the converter according to the current angle and current voltage at which the converter is started, when the angle compensation amount is zero and the voltage compensation amount is zero.

[0200] Step 421: When the photovoltaic system is not connected to the converter and the energy storage system is not connected to the converter, determine the working mode of the converter as the third working mode, and establish voltage by charging the bus on the AC side.

[0201] Step 422: Determine whether the AC voltage is within the predetermined voltage range. If the AC voltage is within the predetermined voltage range, proceed to step 423; otherwise, if the AC voltage is not within the predetermined voltage range, continue to execute step 422 within a predetermined time, that is, continuously determine whether the AC voltage is within the predetermined voltage range within the predetermined time; if the AC voltage is still not within the predetermined voltage range within the predetermined time, report an error, clear the fault, and continue executing step 422.

[0202] In some embodiments of this disclosure, the predetermined voltage range can be between [90%, 110%].

[0203] Step 423: If the AC voltage is within the predetermined voltage range, close the third charging switch K4 as shown in Figure 3, and use the grid voltage to charge the converter's bus capacitor through a resistor; and check whether the bus voltage is established. If the bus voltage is established, proceed to step 425; otherwise, if the bus voltage is not established, proceed to step 424.

[0204] Step 424: Determine if there is a charging fault and clear the fault. Then proceed to step 421.

[0205] Step 425: Determine that charging is complete, close the third working switch K5 as shown in Figure 3, and output the inverter voltage.

[0206] Step 426: Determine whether there is a deviation between the actual amplitude and phase of the inverter voltage and the amplitude and phase of the grid voltage. If there is no deviation between the actual amplitude of the inverter voltage and the amplitude of the grid voltage, and also no deviation between the actual phase of the inverter voltage and the phase of the grid voltage, proceed to step 429; if there is a deviation between at least one of the actual amplitude of the inverter voltage and the amplitude of the grid voltage, and between the actual phase of the inverter voltage and the grid voltage, proceed to step 427.

[0207] Step 427: Calculate the voltage and phase deviation (compensation amount).

[0208] In some embodiments of this disclosure, step 427 may include: determining the angle compensation amount and the voltage compensation amount based on the actual amplitude and actual phase of the inverter voltage and the amplitude and phase of the grid voltage.

[0209] Step 428: Power on the device according to the value after adding the compensation amount.

[0210] In some embodiments of this disclosure, step 428 may include: when the angle compensation amount is not zero and the voltage compensation amount is not zero, compensating the current starting angle of the converter according to the angle compensation amount of the operating mode, compensating the current starting voltage of the converter according to the voltage compensation amount of the operating mode, and starting the converter according to the compensated angle and the compensated voltage; when the angle compensation amount is zero and the voltage compensation amount is not zero, compensating the current starting voltage of the converter according to the voltage compensation amount of the operating mode, and starting the converter according to the current starting angle and the compensated voltage; when the angle compensation amount is not zero and the voltage compensation amount is zero, compensating the current starting angle of the converter according to the angle compensation amount of the operating mode, and starting the converter according to the current starting voltage and the compensated angle.

[0211] Step 429: Power on the machine at the current angle.

[0212] In some embodiments of this disclosure, step 429 may include: starting the converter according to the current angle and current voltage at which the converter is started, when the angle compensation is zero and the voltage compensation is zero.

[0213] The above embodiments of this disclosure propose a compensation method based on various modes to reduce the starting current surge.

[0214] The embodiments described above do not require manual correction of the grid-side voltage frequency.

[0215] The embodiments described above provide a suitable correction method regardless of whether photovoltaic power is connected.

[0216] The above embodiments of this disclosure propose a converter start-up control method. For various situations with or without photovoltaic or energy storage, it automatically selects a scheme to establish the bus voltage. After the bus is established, the voltage can replace related technical solutions to automatically correct the grid voltage and frequency. According to the converter mode, it realizes the correction of voltage amplitude, angle and phase, thereby reducing the start-up peak.

[0217] Figure 5 is a schematic diagram of the structure of some embodiments of the control device of this disclosure. As shown in Figure 5, the control device of this disclosure may include an operating mode determination module 51, a bus voltage establishment module 52, a compensation amount determination module 53, and a start control module 54.

[0218] The operating mode determination module 51 is configured to determine the operating mode of the converter based on whether at least one of the photovoltaic system and the energy storage system is connected to the converter.

[0219] In some embodiments of this disclosure, the operating mode determination module 51 may be configured to perform at least one of the following operations: when the photovoltaic system is connected to the converter, determine the operating mode of the converter as a first operating mode; when the photovoltaic system is not connected to the converter but the energy storage system is connected to the converter, determine the operating mode of the converter as a second operating mode; when the photovoltaic system is not connected to the converter and the energy storage system is not connected to the converter, determine the operating mode of the converter as a third operating mode.

[0220] The bus voltage establishment module 52 is configured to establish the bus voltage by charging the bus capacitor of the converter through a resistor in the operating mode.

[0221] In some embodiments of this disclosure, the bus voltage establishment module 52 can be configured to perform at least one of the following operations: in the first operating mode, using a photovoltaic system to charge the bus capacitor of the converter through a resistor to establish the bus voltage; in the second operating mode, using an energy storage system to charge the bus capacitor of the converter through a resistor to establish the bus voltage; and in the third operating mode, using grid voltage to charge the bus capacitor of the converter through a resistor to establish the bus voltage.

[0222] In some embodiments of this disclosure, when the bus voltage establishment module 52 establishes the bus voltage by charging the bus capacitor of the converter through a resistor using a photovoltaic system, it can be configured to determine whether the current photovoltaic voltage is within a predetermined photovoltaic voltage range; if the current photovoltaic voltage is within the predetermined photovoltaic voltage range, close the first charging switch and charge the bus capacitor of the converter through a resistor using a photovoltaic system; detect whether the bus voltage is established; if the bus voltage is established, close the first operating switch and the converter outputs the inverter voltage.

[0223] In some embodiments of this disclosure, when the bus voltage establishment module 52 establishes the bus voltage by charging the bus capacitor of the converter through a resistor using an energy storage system, it can be configured to determine whether the energy storage state of charge is within a predetermined range; if the energy storage state of charge is within the predetermined range, close the second charging switch and charge the bus capacitor of the converter through a resistor using an energy storage system; detect whether the bus voltage is established; if the bus voltage is established, close the second operating switch and the converter outputs inverter voltage.

[0224] In some embodiments of this disclosure, when the bus voltage establishment module 52 uses the grid voltage to charge the bus capacitor of the converter through a resistor to establish the bus voltage, it can be configured to determine whether the AC voltage is within a predetermined voltage range; if the AC voltage is within the predetermined voltage range, close the third charging switch and use the grid voltage to charge the bus capacitor of the converter through a resistor; detect whether the bus voltage is established; if the bus voltage is established, close the third operating switch and the converter outputs inverter voltage.

[0225] The compensation amount determination module 53 is configured to determine the angle compensation amount and voltage compensation amount of the operating mode based on the value of the bus voltage and the amplitude, phase and frequency of the grid voltage.

[0226] In some embodiments of this disclosure, the compensation amount determination module 53 may be configured to: acquire the amplitude, phase, and frequency of the grid voltage; use the amplitude, phase, and frequency of the grid voltage as the target amplitude, target phase, and target frequency of the inverter voltage; generate the inverter voltage based on the bus voltage and the target amplitude, target phase, and target frequency of the inverter voltage; acquire the actual amplitude and actual phase of the inverter voltage; and determine the angle compensation amount and voltage compensation amount based on the actual amplitude and actual phase of the inverter voltage and the amplitude and phase of the grid voltage.

[0227] In some embodiments of this disclosure, when the compensation amount determination module 53 generates the inverter voltage based on the bus voltage and the target amplitude, target phase and target frequency of the inverter voltage, it can be configured to determine the inverter modulation wave required to generate the inverter voltage based on the bus voltage, the target amplitude, target phase and target frequency of the inverter voltage; and generate the inverter voltage based on the bus voltage and the inverter modulation wave.

[0228] The start control module 54 is configured to compensate the current angle and current voltage of the converter based on the angle compensation amount and voltage compensation amount of the operating mode, and start the converter according to the compensated angle and compensated voltage.

[0229] In some embodiments of this disclosure, the start-up control module 54 can be configured to start the converter according to the current start-up angle and current voltage when the angle compensation amount is zero and the voltage compensation amount is zero; and when the angle compensation amount is not zero and the voltage compensation amount is not zero, to compensate the current start-up angle of the converter according to the angle compensation amount of the operating mode, to compensate the current start-up voltage of the converter according to the voltage compensation amount of the operating mode, and to start the converter according to the compensated angle and compensated voltage.

[0230] In some embodiments of this disclosure, the start-up control module 54 can be configured to, when the angle compensation amount is zero and the voltage compensation amount is not zero, compensate the current voltage of the converter start-up according to the voltage compensation amount of the operating mode, and start the converter according to the current start-up angle and the compensated voltage; when the angle compensation amount is not zero and the voltage compensation amount is zero, compensate the current angle of the converter start-up according to the angle compensation amount of the operating mode, and start the converter according to the current start-up voltage and the compensated angle.

[0231] Figure 6 is a schematic diagram of the structure of some other embodiments of the control device of this disclosure. As shown in Figure 6, the control device of this disclosure may include a memory 61 and a processor 62.

[0232] The memory 61 is used to store instructions, and the processor 62 is coupled to the memory 61. The processor 62 is configured to execute instructions stored in the memory to implement the converter start-up control method involved in the above embodiments.

[0233] As shown in Figure 6, the control device also includes a communication interface 63 for exchanging information with other devices. Additionally, the control device includes a bus 64, through which the processor 62, communication interface 63, and memory 61 communicate with each other.

[0234] Memory 61 may include high-speed RAM, and may also include non-volatile memory, such as at least one disk storage device. Memory 61 may also be a memory array. Memory 61 may also be divided into blocks, and the blocks may be combined into virtual volumes according to certain rules.

[0235] Furthermore, processor 62 may be a central processing unit (CPU), an application-specific integrated circuit (ASIC), or one or more integrated circuits configured to implement embodiments of the present disclosure.

[0236] Figure 7 is a schematic diagram of some other embodiments of the converter start-up control system of this disclosure. As shown in Figure 7, the converter start-up control system of this disclosure includes a control device 71 and a photovoltaic system access control circuit 72.

[0237] The control device 71 can be the control device in any of the above embodiments of this disclosure (e.g., FIG5 or FIG6).

[0238] In some embodiments of this disclosure, as shown in FIG3, the photovoltaic system access control circuit of FIG7 embodiment may include a first charging switch K6, a first resistor R1 and a first operating switch K1. The first charging switch K6 and the first resistor R1 are connected in series and then connected in parallel with the first operating switch K1. The first charging switch K6 is configured to charge the bus capacitor of the inverter through the first resistor R1 when it is closed. The first operating switch K1 is configured to close when the bus voltage is established, so that the inverter outputs the inverter voltage.

[0239] In some embodiments of this disclosure, as shown in FIG7, the converter start-up control system may further include an energy storage system access control circuit 73.

[0240] In some embodiments of this disclosure, as shown in FIG3, the energy storage system access control circuit 73 of FIG7 embodiment may include a second charging switch K7, a second resistor R2, and a second operating switch K2. The second charging switch K7 and the second resistor R2 are connected in series and then connected in parallel with the second operating switch K2. The second charging switch K7 is configured to charge the bus capacitor of the converter through the second resistor R2 when it is closed. The second operating switch K2 is configured to close when the bus voltage is established, so that the converter outputs the inverter voltage.

[0241] In some embodiments of this disclosure, as shown in FIG7, the converter start-up control system may further include a grid access control circuit 74.

[0242] In some embodiments of this disclosure, as shown in FIG3, the grid access control circuit of FIG7 may include a first rectifier 31, a third charging switch K4, a third resistor R3, and a third operating switch K5. The first rectifier is configured to convert the grid AC voltage into DC voltage. The third charging switch K4 and the third resistor are connected in series and then in parallel with the third operating switch K5. The third charging switch K4 is configured to charge the converter bus capacitor through the first rectifier 31 and the third resistor R3 when it is closed. The third operating switch K5 is configured to close when the bus voltage is established, so that the converter outputs an inverter voltage.

[0243] The embodiments disclosed above are equivalent to adding a charging control unit to each power source, which can realize automatic charging and detection logic.

[0244] In some embodiments of this disclosure, as shown in FIG7, the converter start-up control system may further include a first acquisition module 75, a second acquisition module 76, and a third acquisition module 77.

[0245] The first acquisition module 75 is configured to acquire bus voltage and send the acquired bus voltage to the control device 71.

[0246] The second acquisition module 76 is configured to acquire the amplitude, phase and frequency of the grid voltage and send the acquired amplitude, phase and frequency of the grid voltage to the control device 71.

[0247] The third acquisition module 77 is configured to acquire the actual amplitude, actual phase and actual frequency of the inverter voltage, and send the acquired actual amplitude, actual phase and actual frequency of the inverter voltage to the control device 71.

[0248] In some embodiments of this disclosure, as shown in Figures 3 and 7, the converter start-up control system may further include an AC switch K3.

[0249] In some embodiments of this disclosure, as shown in Figures 3 and 7, AC switch K3 is disposed between the power grid and the converter; a second acquisition module 76 is configured to acquire the amplitude, phase, and frequency of the power grid voltage at point A between the power grid and AC switch K3; and a third acquisition module 77 is configured to acquire the actual amplitude, actual phase, and actual frequency of the inverter voltage at point B between AC switch K3 and the converter.

[0250] In some embodiments of this disclosure, as shown in Figure 3, the capacitor and inductor between point B and the converter serve to perform LC filtering to remove harmonics in the current. The waveform on the right side of the inductor contains significant harmonics, which need to be filtered by a reactor. The voltage after LC filtering is compared with the grid voltage.

[0251] The above embodiments of this disclosure propose a unified bus establishment method and a grid voltage and frequency compensation system for converter application systems under different conditions.

[0252] The above embodiments of this disclosure are equivalent to adding a charging control unit to each power source, which can realize automatic charging and detection of the converter.

[0253] The embodiments disclosed above first determine the operating mode of the converter. After determining the operating mode, the bus capacitor is charged through a resistor to establish the standby bus voltage. After the bus charging is established, the DC voltage established by the DC bus is used to generate an off-grid sine wave output to the right side of K3 by setting the voltage and frequency of the AC acquisition. K3 is not closed initially. The angle of the sine wave generated by K3 is compared with the angle of the grid sine wave to the left of K3 to calculate the angle compensation and voltage compensation. After obtaining the angle compensation, the starting angle of the converter is increased by this compensation and calculated according to the compensated angle. After obtaining the voltage compensation, the starting voltage of the converter is increased by this compensation and calculated according to the compensated voltage. Through adaptive judgment of charging in different modes and angle compensation, the peak suppression of the converter system during startup is achieved.

[0254] According to another aspect of this disclosure, as shown in FIG3, a converter system is provided, including a photovoltaic system, an energy storage system, a converter, and a converter start-up control system as described in any of the above embodiments.

[0255] In some embodiments of this disclosure, the converter system may be an energy storage converter system.

[0256] According to another aspect of this disclosure, as shown in FIG3, an air conditioning system is provided, including an air conditioner and a converter system as described in any of the above embodiments.

[0257] In some embodiments of this disclosure, the air conditioning system may be a photovoltaic air conditioning system.

[0258] In some embodiments of this disclosure, the air conditioning system may be a photovoltaic-storage air conditioning system.

[0259] In some embodiments of this disclosure, as shown in FIG3, the air conditioner may include an air conditioner inverter motor.

[0260] The converter start-up control method, apparatus and system of the above embodiments disclosed herein can be applied to a standalone converter system or to an air conditioning system.

[0261] According to another aspect of this disclosure, a computer program product is provided, comprising a computer program, wherein when the computer program is executed by a processor, it implements the converter start-up control method as described in any of the above embodiments.

[0262] According to another aspect of this disclosure, a computer-readable storage medium is provided, wherein the computer-readable storage medium stores computer instructions that, when executed by a processor, implement the converter start-up control method as described in any of the above embodiments.

[0263] The computer-readable storage medium disclosed herein can be implemented as a non-transitory computer-readable storage medium.

[0264] Those skilled in the art will understand that embodiments of this disclosure can be provided as methods, apparatus, or computer program products. Therefore, this disclosure can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, this disclosure can take the form of a computer program product embodied on one or more computer-usable non-transitory storage media (including, but not limited to, disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0265] This disclosure is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of this disclosure. It will be understood that each block of the flowchart illustrations and / or block diagrams, as well as combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions specified in one or more flowchart illustrations and / or one or more block diagrams.

[0266] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means that implement the functions specified in one or more flowcharts and / or one or more block diagrams.

[0267] These computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer-implemented process, such that the instructions, which execute on the computer or other programmable apparatus, provide steps for implementing the functions specified in one or more flowcharts and / or one or more block diagrams.

[0268] The control device, operating mode determination module, bus voltage establishment module, compensation amount determination module, and start-up control module described above can be implemented as a general-purpose processor, programmable logic controller, digital signal processor (DSP), application-specific integrated circuit (ASIC), field-programmable gate array (FPGA), or other programmable logic device, discrete gate or transistor logic device, discrete hardware component, or any suitable combination thereof for performing the functions described in this disclosure.

[0269] Those skilled in the art will understand that all or part of the steps of the methods in the above embodiments of this disclosure can be implemented in hardware. The hardware can be implemented as a general-purpose processor, programmable logic controller, digital signal processor, application-specific integrated circuit, field-programmable gate array or other programmable logic device, discrete gate or transistor logic device, discrete hardware component or any suitable combination thereof for executing the methods of this disclosure.

[0270] This concludes the detailed description of the present disclosure. To avoid obscuring the concept of the disclosure, some details known in the art have not been described. Those skilled in the art will fully understand how to implement the technical solutions disclosed herein based on the above description.

[0271] Those skilled in the art will understand that all or part of the steps of the above embodiments can be implemented by hardware, or by a program instructing the relevant hardware to implement them. The program can be stored in a non-transitory computer-readable storage medium, such as a read-only memory, a disk, or an optical disk.

[0272] The description in this disclosure is provided for illustrative and descriptive purposes only and is not intended to be exhaustive or to limit the disclosure to its forms. Many modifications and variations will be apparent to those skilled in the art. The embodiments were chosen and described in order to better illustrate the principles and practical application of this disclosure and to enable those skilled in the art to understand this disclosure and to design various embodiments with various modifications suitable for a particular purpose.

Claims

1. A converter start-up control method, comprising: Determine the operating mode of the converter based on whether at least one of the photovoltaic system and energy storage system is connected to the converter. In the aforementioned operating mode, the bus capacitor of the converter is charged through a resistor to establish the bus voltage; Based on the value of the bus voltage, the amplitude, phase, and frequency of the grid voltage, determine the angle compensation amount and voltage compensation amount of the operating mode; Based on the angle compensation and voltage compensation amounts of the operating mode, the current angle and voltage of the converter are compensated for, and the converter is started according to the compensated angle and voltage.

2. The converter start-up control method according to claim 1, wherein, Determining the operating mode of the converter based on whether at least one of the photovoltaic system and the energy storage system is connected to the converter includes at least one of the following steps: When a photovoltaic system is connected to a converter, the converter's operating mode is determined to be the first operating mode. When the photovoltaic system is not connected to the converter but the energy storage system is connected to the converter, the converter's operating mode is determined to be the second operating mode. When neither the photovoltaic system nor the energy storage system is connected to the converter, the converter's operating mode is determined to be the third operating mode.

3. The converter start-up control method according to claim 2, wherein, In the operating mode, establishing the bus voltage by charging the bus capacitor of the converter through a resistor includes at least one of the following steps: In the first operating mode, a photovoltaic system is used to charge the bus capacitor of the converter through a resistor to establish the bus voltage. In the second operating mode, the energy storage system charges the bus capacitor of the converter through a resistor to establish the bus voltage; In the third operating mode, the mains voltage is used to charge the converter's bus capacitor through a resistor to establish the bus voltage.

4. The converter start-up control method according to claim 3, wherein, The method of using a photovoltaic system to charge the bus capacitor of the converter through a resistor to establish the bus voltage includes: Determine whether the current photovoltaic voltage is within the predetermined photovoltaic voltage range; When the current photovoltaic voltage is within the predetermined photovoltaic voltage range, close the first charging switch and use the photovoltaic system to charge the bus capacitor of the converter through a resistor. Check if the bus voltage has been established; Once the bus voltage is established, close the first operating switch, and the converter outputs inverter voltage.

5. The converter start-up control method according to claim 3 or 4, wherein, The method of establishing bus voltage by charging the bus capacitor of the converter through a resistor using an energy storage system includes: Determine whether the energy storage state of charge is within a predetermined range; When the energy storage state of charge is within a predetermined range, the second charging switch is closed, and the energy storage system charges the bus capacitor of the converter through a resistor. Check if the bus voltage has been established; Once the bus voltage is established, close the second operating switch, and the converter outputs inverter voltage.

6. The converter start-up control method according to any one of claims 3 to 5, wherein, The process of charging the converter's bus capacitor using grid voltage through a resistor to establish the bus voltage includes: Determine whether the AC voltage is within the predetermined voltage range; When the AC voltage is within the predetermined voltage range, close the third charging switch and use the grid voltage to charge the bus capacitor of the converter through a resistor. Check if the bus voltage has been established; Once the bus voltage is established, close the third operating switch, and the converter outputs inverter voltage.

7. The converter start-up control method according to any one of claims 1 to 6, wherein, The step of compensating the current angle and current voltage of the converter based on the angle compensation amount and voltage compensation amount of the operating mode, and starting the converter according to the compensated angle and compensated voltage includes: When the angle compensation is zero and the voltage compensation is zero, the converter is started according to the current angle and current voltage at which the converter is started. When the angle compensation amount is not zero and the voltage compensation amount is not zero, the current angle of the converter startup is compensated according to the angle compensation amount of the working mode, and the current voltage of the converter startup is compensated according to the voltage compensation amount of the working mode, and the converter is started according to the compensated angle and the compensated voltage.

8. The converter start-up control method according to any one of claims 1 to 7, wherein, The step of compensating the current angle and current voltage of the converter based on the angle compensation amount and voltage compensation amount of the operating mode, and starting the converter according to the compensated angle and compensated voltage includes: When the angle compensation is zero and the voltage compensation is not zero, the current voltage at which the converter starts is compensated according to the voltage compensation of the working mode, and the converter is started according to the current angle at which the converter starts and the compensated voltage. When the angle compensation is not zero and the voltage compensation is zero, the current angle of the converter startup is compensated according to the angle compensation of the working mode, and the converter is started according to the current voltage of the converter startup and the compensated angle.

9. The converter start-up control method according to any one of claims 1 to 8, wherein, The step of determining the angle compensation and voltage compensation amounts for the operating mode based on the value of the bus voltage and the amplitude, phase, and frequency of the grid voltage includes: Obtain the amplitude, phase, and frequency of the grid voltage; The amplitude, phase, and frequency of the grid voltage are used as the target amplitude, target phase, and target frequency of the inverter voltage; The inverter voltage is generated based on the bus voltage, the target amplitude, target phase, and target frequency of the inverter voltage. Obtain the actual amplitude and actual phase of the inverter voltage; The angle compensation amount and voltage compensation amount are determined based on the actual amplitude and phase of the inverter voltage and the amplitude and phase of the grid voltage.

10. The converter start-up control method according to claim 9, wherein, The step of generating the inverter voltage based on the bus voltage, and the target amplitude, target phase, and target frequency of the inverter voltage includes: Based on the bus voltage, the target amplitude, target phase, and target frequency of the inverter voltage, determine the inverter modulation wave required to generate the inverter voltage; The inverter voltage is generated based on the bus voltage and the inverter modulation wave.

11. A control device, comprising: The operating mode determination module is configured to determine the operating mode of the converter based on whether at least one of the photovoltaic system and the energy storage system is connected to the converter. The bus voltage establishment module is configured to establish the bus voltage by charging the bus capacitor of the converter through a resistor in the operating mode. The compensation amount determination module is configured to determine the angle compensation amount and voltage compensation amount of the operating mode based on the value of the bus voltage and the amplitude, phase and frequency of the grid voltage. The start-up control module is configured to compensate the current angle and voltage of the converter based on the angle compensation and voltage compensation amount of the operating mode, and start the converter according to the compensated angle and voltage.

12. A control device, comprising: The memory is configured to store instructions; and The processor is configured to execute the instructions, causing the control device to implement the converter start-up control method as described in any one of claims 1-10.

13. A converter start-up control system, comprising the control device as described in claim 11 or 12.

14. The converter start-up control system according to claim 13, further comprising: A photovoltaic system access control circuit is provided, wherein the photovoltaic system access control circuit includes a first charging switch, a first resistor, and a first operating switch. The first charging switch and the first resistor are connected in series and then in parallel with the first operating switch. The first charging switch is configured to charge the bus capacitor of the inverter through the first resistor when it is closed. The first operating switch is configured to close when the bus voltage is established, so that the inverter outputs the inverter voltage.

15. The converter start-up control system according to claim 13 or 14, further comprising: The energy storage system is connected to a control circuit, which includes a second charging switch, a second resistor, and a second operating switch. The second charging switch and the second resistor are connected in series and then in parallel with the second operating switch. The second charging switch is configured to charge the bus capacitor of the converter through the second resistor when it is closed. The second operating switch is configured to close when the bus voltage is established, so that the converter outputs the inverter voltage.

16. The converter start-up control system according to any one of claims 13 to 15, further comprising: A grid access control circuit includes a first rectifier, a third charging switch, a third resistor, and a third operating switch. The first rectifier is configured to convert AC grid voltage into DC voltage. The third charging switch and the third resistor are connected in series and then in parallel with the third operating switch. The third charging switch is configured to, when closed, allow the grid voltage to charge the bus capacitor of the converter through the first rectifier and the third resistor. The third operating switch is configured to close when the bus voltage is established, allowing the converter to output an inverter voltage.

17. The converter start-up control system according to any one of claims 13 to 16, further comprising: The first acquisition module is configured to acquire bus voltage; The second acquisition module is configured to acquire the amplitude, phase, and frequency of the grid voltage; The third acquisition module is configured to acquire the actual amplitude, actual phase, and actual frequency of the inverter voltage.

18. The converter start-up control system according to any one of claims 13 to 17, further comprising: An AC switch is provided, wherein the AC switch is located between the power grid and the converter; a second acquisition module is configured to acquire the amplitude, phase, and frequency of the power grid voltage between the power grid and the AC switch; and a third acquisition module is configured to acquire the actual amplitude, actual phase, and actual frequency of the inverter voltage between the AC switch and the converter.

19. A converter system comprising a converter start-up control system as claimed in any one of claims 13 to 18.

20. An air conditioning system comprising the inverter system as described in claim 19.

21. A computer-readable storage medium, wherein, The computer-readable storage medium stores computer instructions that, when executed by a processor, implement the converter start-up control method as described in any one of claims 1-10.

22. A computer program product comprising a computer program, wherein, When the computer program is executed by the processor, it implements the converter start-up control method as described in any one of claims 1-10.

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