Power supply control method and power supply system of three-phase inverter

Abstract

The invention discloses a power supply control method of a three-phase inverter and a power supply system, and belongs to the technical field of inverter power supply. The invention provides a power supply control method of a three-phase inverter, a direct current side of the three-phase inverter is electrically connected with a photovoltaic module, an alternating current side of the three-phase inverter is electrically connected with a construction electric appliance, the power supply control method comprises the following steps: when the three-phase inverter is in an off-grid working condition, obtaining a working voltage, a working frequency and a power supply phase number of the construction electric appliance; generating a driving signal according to the working voltage, the working frequency and the power phase number; and controlling the three-phase inverter to supply power to the construction electric appliance according to the driving signal. According to the power supply control method of the three-phase inverter, the power supply voltage is used for supplying power to the electric appliances on the construction site, the three-phase load and the single-phase load on the construction site can be supplied with power without additionally introducing power supply equipment, the construction cost is reduced, and the three-phase inverter on the construction site is used for supplying power and taking power conveniently.

Description

Technical Field

[0001] The present application belongs to the technical field of inverter power supply, and in particular, relates to a power supply control method and a power supply system of a three-phase inverter. Background Art

[0002] The construction site of the grid-connected inverter is usually remote, such as on rooftops, outdoors, etc. The construction site usually requires various electrical appliances to assist the construction, including three-phase loads and single-phase loads. The traditional solution is to temporarily connect the construction power supply from the distribution box to the construction site. For projects in remote locations, it may be necessary to use equipment such as diesel generators for power supply, which adds additional construction costs and is very inconvenient to obtain electricity. Summary of the invention

[0003] The present application aims to solve at least one of the technical problems existing in the prior art. To this end, the present application proposes an on-site power supply control method and power supply system of a three-phase inverter, which can supply power to three-phase loads and single-phase loads at the construction site without the need for additional power supply equipment, thereby reducing construction costs, and using the three-phase inverter at the construction site for power supply, making it convenient to obtain power.

[0004] In a first aspect, the present application provides a power supply control method for a three-phase inverter, wherein the DC side of the three-phase inverter is electrically connected to a photovoltaic module, and the AC side of the three-phase inverter is electrically connected to a construction electrical appliance, and the power supply control method comprises:

[0005] When the three-phase inverter is in off-grid condition, obtain the working voltage, working frequency and power phase number of the construction electrical appliances;

[0006] Generate a drive signal according to the operating voltage, operating frequency and the number of power phases;

[0007] The three-phase inverter is controlled according to the driving signal to supply power to the construction electrical appliances.

[0008] According to the power supply control method of the three-phase inverter of the present application, the number of power phases of the single-phase load is two, and the number of power phases of the three-phase load is three. A drive signal is generated according to the working voltage, working frequency and number of power phases of the construction electrical appliances. The drive signal drives the three-phase inverter to output a corresponding single-phase power supply voltage or a three-phase power supply voltage. The power supply voltage is used to power the electrical appliances at the construction site. There is no need to introduce additional power supply equipment to power the three-phase loads and single-phase loads at the construction site, thereby reducing construction costs. Moreover, the three-phase inverter at the construction site is used for power supply, which makes it convenient to obtain power.

[0009] According to one embodiment of the present application, generating a driving signal according to an operating voltage, an operating frequency and a power phase number includes:

[0010] When the number of phases of the power supply is two phases, a first-phase voltage modulation wave and a second-phase voltage modulation wave are generated, the amplitude and frequency of the first-phase voltage modulation wave and the second-phase voltage modulation wave are the same as the amplitude and frequency of the working voltage, and the first-phase voltage modulation wave and the second-phase voltage modulation wave are 180° out of phase with each other;

[0011] Generate a first drive signal according to the first phase voltage modulation wave;

[0012] A second driving signal is generated according to the second phase voltage modulation wave.

[0013] According to an embodiment of the present application, when the number of phases of the power supply is two, generating a first-phase voltage modulation wave and a second-phase voltage modulation wave includes:

[0014] Obtain the feedback amplitude and feedback frequency of the input voltage of the construction electrical appliances;

[0015] Determine the voltage reference Ud1 of the d-axis and the voltage reference Uq1 of the q-axis according to the amplitude of the working voltage and the feedback amplitude of the input voltage of the construction electrical appliance;

[0016] Determine the reference phase θ1 according to the operating frequency and the feedback frequency of the input voltage of the construction electrical appliance;

[0017] Determine that the d-axis voltage reference quantity Ud1, the q-axis voltage reference quantity Uq1 and the α component of the reference phase θ1 after dq / αβ conversion are the first phase voltage modulation wave;

[0018] A second phase voltage modulation wave is generated according to the first phase voltage modulation wave.

[0019] According to one embodiment of the present application, controlling a three-phase inverter to supply power to construction electrical appliances according to a driving signal includes:

[0020] According to the first drive signal, a switch circuit in the three-phase inverter corresponding to the output electrically connected to the live wire end of the construction electrical appliance is driven to operate;

[0021] The switch circuit corresponding to the output electrically connected to the neutral terminal of the construction electrical appliance in the three-phase inverter is driven to operate according to the second drive signal.

[0022] According to one embodiment of the present application, generating a driving signal according to an operating voltage, an operating frequency and a power phase number includes:

[0023] When the power supply has three phases, a three-phase modulation wave is generated, the amplitude and frequency of the three-phase modulation wave are the same as the amplitude and frequency of the working voltage, and the phases of the modulation waves of each phase in the three-phase modulation wave differ by 120°;

[0024] A first drive signal, a second drive signal and a third drive signal are respectively generated according to the three-phase modulation wave.

[0025] According to one embodiment of the present application, when the number of phases of the power supply is three-phase, generating a three-phase modulation wave includes:

[0026] Obtain the feedback amplitude and feedback frequency of the input voltage of the construction electrical appliances;

[0027] Determine the voltage reference Ud2 of the d-axis and the voltage reference Uq2 of the q-axis according to the amplitude of the working voltage and the feedback amplitude of the input voltage of the construction electrical appliance;

[0028] Determine the reference phase θ2 according to the operating frequency and the feedback frequency of the input voltage of the construction electrical appliance;

[0029] The three-phase modulation wave of the d-axis voltage reference Ud2, the q-axis voltage reference Uq2 and the reference phase θ2 after dq / αβ conversion and αβ / abc conversion is obtained.

[0030] In a second aspect, the present application provides a power supply system, characterized in that it includes:

[0031] A three-phase inverter unit, the three-phase inverter unit includes at least one three-phase inverter, the DC side of the three-phase inverter unit is connected to a DC source, and the AC side of the three-phase inverter unit is used to be electrically connected to a load;

[0032] The three-phase inverter unit includes a control circuit configured to execute the aforementioned power supply method.

[0033] According to the power supply system of the present application, the number of power phases for a single-phase load is two, and the number of power phases for a three-phase load is three. The control circuit generates a drive signal based on the working voltage, working frequency and number of power phases of the construction electrical appliances. The drive signal drives the three-phase inverter to output a corresponding single-phase power supply voltage or a three-phase power supply voltage. The power supply voltage is used to power the electrical appliances at the construction site. There is no need to introduce additional power supply equipment to power the three-phase loads and single-phase loads at the construction site, thereby reducing construction costs. The three-phase inverter at the construction site is used for power supply, making it convenient to obtain power.

[0034] According to one embodiment of the present application, the load includes at least one single-phase load, the live wire terminal and the neutral wire terminal of the single-phase load are respectively electrically connected to the output terminals of any two phases of the three-phase output terminals of the three-phase inverter unit, and the third phase output terminal of the three-phase output terminal is suspended.

[0035] According to one embodiment of the present application, the load includes at least one single-phase load, any two of the three-phase output ends of the three-phase inverter unit are connected in parallel to form a first output end, the other phase output end of the three-phase inverter unit serves as the second output end, the live wire end of the single-phase load is electrically connected to the first output end, and the neutral wire end of the single-phase load is electrically connected to the second output end.

[0036] According to one embodiment of the present application, the three-phase inverter unit includes a three-phase inverter, any two phase output ends of the three-phase output ends of the three-phase inverter are connected in parallel to form a first output end, and the other phase output end of the three-phase inverter unit serves as a second output end.

[0037] According to one embodiment of the present application, the three-phase inverter unit includes multiple three-phase inverters, the first phases of the three-phase output ends of each three-phase inverter are connected in parallel to form a first phase output end, the second phases of the three-phase output ends of each three-phase inverter are connected in parallel to form a second phase output end, and the third phase output end of the AC side of each three-phase inverter is suspended.

[0038] According to one embodiment of the present application, the three-phase inverter unit includes multiple three-phase inverters, the first phase and the second phase of each three-phase inverter are connected in parallel to form a first phase output end, and the third phase of the three-phase output ends of each three-phase inverter are connected in parallel to form a second phase output end.

[0039] Additional aspects and advantages of the present application will be given in part in the description below, and in part will become apparent from the description below, or will be learned through the practice of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] The above and / or additional aspects and advantages of the present application will become apparent and easily understood from the description of the embodiments in conjunction with the following drawings, in which:

[0041] Figure 1 is a flow chart of a power supply control method for a three-phase inverter provided in an embodiment of the present application;

[0042] Figure 2 is a waveform diagram of a first phase voltage modulation wave and a second phase voltage modulation wave provided in an embodiment of the present application;

[0043] Figure 3 is a control block diagram for generating a first phase voltage modulation wave and a second phase voltage modulation wave provided by an embodiment of the present application;

[0044] Figure 4 is a waveform diagram of a three-phase voltage modulation wave provided in an embodiment of the present application;

[0045] Figure 5 is a control block diagram for generating a three-phase voltage modulation wave provided in an embodiment of the present application;

[0046] Figure 6 It is one of the structural schematic diagrams of the power supply system provided in the embodiment of the present application;

[0047] Figure 7 This is the second structural diagram of the power supply system provided in the embodiment of the present application;

[0048] Figure 8This is the third structural diagram of the power supply system provided in the embodiment of the present application;

[0049] Fig. 9 This is the fourth structural diagram of the power supply system provided in the embodiment of the present application.

[0050] Reference numerals:

[0051] Three-phase inverter 10, single-phase load 20, controller 30, photovoltaic module 40. DETAILED DESCRIPTION

[0052] The embodiments of the present application are described in detail below, and examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present application, and cannot be understood as limiting the present application.

[0053] In the following description, "circuit" refers to a conductive loop composed of at least one element or subcircuit through electrical connection or electromagnetic connection. When an element or circuit is said to be "coupled to" or "connected to" another element or an element / circuit is said to be "coupled to" or "connected to" two nodes, it can be directly coupled or connected to another element or there can be an intermediate element, and the connection between the elements can be physical, logical, or a combination thereof. On the contrary, when an element is said to be "directly coupled to" or "directly connected to" another element, it means that there is no intermediate element between the two.

[0054] In the description, the terms "first", "second", etc. are used to distinguish similar objects, and are not used to describe a specific order or sequence. It should be understood that the numerical descriptors used in this way are interchangeable where appropriate, so that the embodiments of the present application can be implemented in an order other than those illustrated or described herein, and the objects distinguished by "first", "second", etc. are generally of the same type, and the number of objects is not limited. For example, the first object can be one or more. In addition, "and / or" in the specification and claims represents at least one of the connected objects, and the character " / " generally indicates that the objects associated with each other are in an "or" relationship.

[0055] In addition, descriptions with reference to the terms "one embodiment", "some embodiments", "illustrative embodiments", "examples", "specific examples", or "some examples" etc. mean that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0056] As an important component of the solar power generation system, the construction site of the grid-connected inverter is often located in remote areas. In order to ensure the smooth progress of the grid-connected inverter installation project, the construction site is usually equipped with a series of electrical equipment to assist the operation. These construction equipment include single-phase loads and three-phase loads.

[0057] In the face of remote construction sites, the relevant technology temporarily pulls cables from nearby distribution boxes to the construction site to provide necessary power support. However, in projects with extremely remote locations, this power supply method that relies on the public power grid may not be realistic, and it may be necessary to use diesel generators as temporary power sources. The stability of power supply is difficult to guarantee, which adds additional construction costs, and it is very inconvenient to obtain electricity.

[0058] Reference Figure 1 An embodiment of the present application proposes a power supply control method for a three-phase inverter 10, wherein the DC side of the three-phase inverter 10 is electrically connected to a photovoltaic module, and the AC side of the three-phase inverter is electrically connected to a construction electrical appliance. The power supply control method includes: step 10, step 20 and step 30.

[0059] Step 10: When the three-phase inverter is in an off-grid condition, obtain the working voltage, working frequency and power phase number of the construction electrical appliance;

[0060] Step 20: Generate a drive signal according to the operating voltage, operating frequency and power phase number;

[0061] Step 30: Control the three-phase inverter 10 to supply power to the construction electrical appliances according to the driving signal.

[0062] The three-phase inverter 10 may include a sensor and a controller 30. The sensor may collect the working voltage, working frequency and power phase number of the construction electrical appliances, and transmit the collected data to the controller 30.

[0063] An embodiment of the present application provides a power supply control method for a three-phase inverter 10. The execution subject of the control method may be the aforementioned controller 30 or a functional module or functional entity in the controller 30 that can implement the control method. The control method provided in the embodiment of the present application is described below using the controller 30 as an example of the execution subject.

[0064] Construction electrical appliances can be three-phase loads or single-phase loads. The number of power phases for single-phase loads is two, and the number of power phases for three-phase loads is three. Loads with different numbers of power phases have different requirements for the supply voltage.

[0065] When the power phase number of the construction electrical appliance is two-phase, the amplitude and frequency of the two-phase power supply output voltage can be determined according to the working voltage and working frequency of the construction electrical appliance, thereby determining the waveform of the two-phase power supply output voltage. By superimposing the waveform of the two-phase power supply output voltage and the carrier, the corresponding drive signal can be generated.

[0066] Similarly, when the power phase number of the construction electrical appliance is three-phase, the amplitude and frequency of the three-phase power supply output voltage can be determined according to the working voltage and working frequency of the construction electrical appliance, thereby determining the waveform of the three-phase power supply output voltage. The amplitude and frequency of each phase of the three-phase power supply output voltage are the same. By superimposing the waveform of the three-phase power supply output voltage and the carrier, the corresponding drive signal can be generated.

[0067] The type of the driving signal can be selected according to the actual application scenario and is not limited here. For example, the driving signal can be a PWM (Pulse Width Modulation) signal.

[0068] The three-phase inverter 10 includes a three-phase inverter circuit. Each phase inverter circuit is provided with a corresponding switch tube. The specific structure of the three-phase inverter circuit has relatively mature related technologies and will not be described in detail here.

[0069] When the three-phase inverter is in an off-grid condition, the DC side of the three-phase inverter is connected to the photovoltaic string, and the controller 30 can generate a drive signal according to the operating voltage, operating frequency and number of power phases and apply it to the drive end of the corresponding switch tube in the three-phase inverter circuit, so that the three-phase inverter 10 outputs a single-phase power supply voltage to power the single-phase load in the construction electrical appliance, or the three-phase inverter 10 outputs a three-phase power supply voltage to power the three-phase load in the construction electrical appliance.

[0070] According to the power supply control method of the three-phase inverter 10 of the present application, the number of power phases of the single-phase load is two-phase, and the number of power phases of the three-phase load is three-phase. A drive signal is generated according to the working voltage, working frequency and number of power phases of the construction electrical appliances. The drive signal drives the three-phase inverter 10 to output a corresponding single-phase power supply voltage or a three-phase power supply voltage. The power supply voltage is used to power the construction electrical appliances. There is no need to introduce additional power supply equipment to power the three-phase load and single-phase load of the construction, thereby reducing construction costs. Moreover, the three-phase inverter 10 of the construction is used for power supply, which makes it convenient to obtain power.

[0071] Reference Figure 2In some embodiments, a drive signal is generated according to an operating voltage, an operating frequency and the number of power phases, including: when the number of power phases is two-phase, a first-phase voltage modulation wave and a second-phase voltage modulation wave are generated, the amplitude and frequency of the first-phase voltage modulation wave and the second-phase voltage modulation wave are the same as the amplitude and the operating frequency of the operating voltage, and the first-phase voltage modulation wave and the second-phase voltage modulation wave are 180° out of phase with each other; a first drive signal is generated according to the first-phase voltage modulation wave; and a second drive signal is generated according to the second-phase voltage modulation wave.

[0072] When the power supply has two phases, the controller 30 can generate a first phase voltage modulation wave Va according to the working voltage and the working frequency, the amplitude of the first phase voltage modulation wave is the same as the amplitude of the working voltage, and the frequency of the first phase voltage modulation wave is the same as the working frequency. After determining the waveform of the first phase voltage modulation wave, the first phase voltage modulation wave is inverted to obtain a second phase voltage modulation wave Vb that is 180° out of phase with the first phase voltage modulation wave.

[0073] The first phase voltage modulation wave Va and the second phase voltage modulation wave Vb are superimposed on the carrier. When the modulation wave is higher than the carrier, a high level is output; when the modulation wave is lower than the carrier, a low level is output, thereby generating a series of pulse signals with variable width, namely, PWM signals. The PWM signal generated according to the first phase voltage modulation wave Va, the second phase voltage modulation wave Vb and the carrier can be used as a driving signal to drive the three-phase inverter 10 to output a power supply voltage to power the construction electrical appliances.

[0074] According to the combination of the first phase voltage modulation wave Va and the second phase voltage modulation wave Vb with the carrier, a driving signal with stronger anti-interference ability can be generated, so that the driving signal can better resist external interference during transmission.

[0075] Reference Figure 3 In some embodiments, when the number of phases of the power supply is two, a first-phase voltage modulation wave Va and a second-phase voltage modulation wave Vb are generated, including: obtaining the feedback amplitude and feedback frequency of the input voltage of the construction electrical appliance; determining the d-axis voltage reference Ud1 and the q-axis voltage reference Uq1 according to the amplitude of the working voltage and the feedback amplitude of the input voltage of the construction electrical appliance; determining the reference phase θ1 according to the working frequency and the feedback frequency of the input voltage of the construction electrical appliance; determining the d-axis voltage reference Ud1, the q-axis voltage reference Uq1 and the α component of the reference phase θ1 after dq / αβ conversion as the first-phase voltage modulation wave Va; generating the second-phase voltage modulation wave Vb according to the first-phase voltage modulation wave Va.

[0076] The feedback amplitude of the input voltage of the construction electrical appliance refers to the feedback amplitude of the output voltage of the three-phase inverter 10 , and the feedback frequency of the input voltage of the construction electrical appliance refers to the feedback frequency of the output voltage of the three-phase inverter 10 .

[0077] The difference between the amplitude of the working voltage and the feedback amplitude of the input voltage of the construction electrical appliance can be converted by the controller 30 to generate the voltage reference Ud1 of the d axis, and the voltage reference Uq1 of the q axis can be zero voltage. The difference between the working frequency and the feedback frequency of the input voltage of the construction electrical appliance can be converted by the frequency controller to generate the output frequency w1 of the three-phase inverter 10. The output frequency w1 can be converted by the integrator to obtain the reference phase θ1 of the three-phase inverter 10.

[0078] The α component of the d-axis voltage reference Ud1, the q-axis voltage reference Uq1 and the reference phase θ of the three-phase inverter 10 after dq / αβ conversion is the first-phase voltage modulation wave Va. By inverting the first-phase voltage modulation wave Va, a second-phase voltage modulation wave Vb with a phase difference of 180° with the first-phase voltage modulation wave Va can be obtained.

[0079] By obtaining the feedback amplitude and frequency of the input voltage of the construction electrical appliances in real time, the amplitude and phase of the output voltage can be adjusted in time to ensure that the output voltage closely follows the working voltage requirements, effectively improving the stability and accuracy of the output voltage.

[0080] In some embodiments, the three-phase inverter 10 is controlled according to a drive signal to supply power to the construction electrical appliances, including: driving the switch circuit corresponding to the output electrically connected to the live wire end of the construction electrical appliances in the three-phase inverter 10 according to a first drive signal; driving the switch circuit corresponding to the output electrically connected to the neutral wire end of the construction electrical appliances in the three-phase inverter 10 according to a second drive signal.

[0081] When the construction appliance is a single-phase load, the live wire end of the construction appliance can be electrically connected to the first phase output end of the three-phase inverter 10, and the first drive signal is used to drive the switch tube corresponding to the first phase output end. The neutral wire end of the construction appliance can be electrically connected to the second phase output end of the three-phase inverter 10, and the second drive signal is used to drive the switch tube corresponding to the second phase output end.

[0082] As an example, the output terminals of the three-phase inverter 10 are respectively the A-phase output terminal, the B-phase output terminal and the C-phase output terminal. The live wire terminal of the construction electrical appliance is electrically connected to the A-phase output terminal, the neutral wire terminal of the construction electrical appliance is electrically connected to the B-phase output terminal, and the C-phase output terminal is suspended. The first drive signal is used to drive the switch tube corresponding to the A-phase output terminal, and the second drive signal is used to drive the switch tube corresponding to the B-phase output terminal.

[0083] In other embodiments, the output ends of the three-phase inverter 10 are respectively an A-phase output end, a B-phase output end and a C-phase output end, wherein the A-phase output end and the B-phase output end are connected in parallel, the live wire end of the construction electrical appliance is electrically connected to the output end of the A-phase output end and the B-phase output end in parallel, and the live wire end of the construction electrical appliance is electrically connected to the C-phase output end. Then, the first drive signal is used to drive the switch tubes corresponding to the A-phase and B-phase output ends, and the second drive signal is used to drive the switch tube corresponding to the C-phase output end.

[0084] Reference Figure 4 In some embodiments, a drive signal is generated according to an operating voltage, an operating frequency and a power phase number, including: when the power phase number is three-phase, a three-phase modulation wave is generated, the amplitude and frequency of the three-phase modulation wave are the same as the amplitude and operating frequency of the operating voltage, and the phases of the modulation waves of each phase in the three-phase modulation wave differ by 120°; and a first drive signal, a second drive signal and a third drive signal are respectively generated according to the three-phase modulation wave.

[0085] When the power supply phase number is three-phase, the controller 30 can generate a three-phase voltage modulation wave according to the working voltage and the working frequency, the amplitude of each phase of the three-phase voltage modulation wave is the same as the amplitude of the working voltage, and the frequency of each phase of the three-phase voltage modulation wave is the same as the working frequency.

[0086] The three-phase voltage modulation wave is superimposed on the carrier. When the modulation wave is higher than the carrier, a high level is output; when the modulation wave is lower than the carrier, a low level is output, thereby generating a series of pulse signals with variable width, namely, PWM signals. The PWM signal generated according to the three-phase voltage modulation wave and the carrier can be used as a driving signal to drive the three-phase inverter 10 to output a power supply voltage to power the construction electrical appliances.

[0087] According to the combination of the three-phase voltage modulation wave and the carrier wave, a driving signal with stronger anti-interference ability can be generated, so that the driving signal can better resist external interference during the transmission process.

[0088] Reference Figure 5 In some embodiments, when the number of phases of the power supply is three-phase, a three-phase modulation wave is generated, including: obtaining the feedback amplitude and feedback frequency of the input voltage of the construction appliance; determining the d-axis voltage reference Ud2 and the q-axis voltage reference Uq2 according to the amplitude of the working voltage and the feedback amplitude of the input voltage of the construction appliance; determining the reference phase θ2 according to the working frequency and the feedback frequency of the input voltage of the construction appliance; obtaining the d-axis voltage reference Ud2, the q-axis voltage reference Uq2 and the reference phase θ2 after dq / αβ conversion and αβ / abc conversion to form a three-phase modulation wave.

[0089] The feedback amplitude of the input voltage of the construction electrical appliance refers to the feedback amplitude of the output voltage of the three-phase inverter 10 , and the feedback frequency of the input voltage of the construction electrical appliance refers to the feedback frequency of the output voltage of the three-phase inverter 10 .

[0090] The difference between the amplitude of the working voltage and the feedback amplitude of the input voltage of the construction electrical appliance can be converted by the voltage controller to generate the voltage reference Ud2 of the d axis, and the voltage reference Uq2 of the q axis can be zero voltage. The difference between the working frequency and the feedback frequency of the input voltage of the construction electrical appliance can be converted by the frequency controller to generate the output frequency w2 of the three-phase inverter 10. The output frequency w2 can be converted by the integrator to obtain the reference phase θ2 of the three-phase inverter 10.

[0091] The d-axis voltage reference Ud2, the q-axis voltage reference Uq2 and the reference phase θ2 of the three-phase inverter 10 can be converted into a three-phase modulation wave through dq / αβ and αβ / abc conversion.

[0092] By obtaining the feedback amplitude and frequency of the input voltage of the construction electrical appliances in real time, the amplitude and phase of the output voltage can be adjusted in time to ensure that the output voltage closely follows the working voltage requirements, effectively improving the stability and accuracy of the output voltage.

[0093] An embodiment of the present application provides a power supply system, including a three-phase inverter unit. The three-phase inverter unit includes at least one three-phase inverter 10, the DC side of the three-phase inverter unit is connected to a DC source, and the AC side of the three-phase inverter unit is used to be electrically connected to a load; the three-phase inverter unit includes a control circuit, and the control circuit is configured to execute the above-mentioned power supply method.

[0094] The specific type of the DC source can be selected according to the actual application scenario and is not limited here. For example, the DC source can be a photovoltaic module 40.

[0095] The three-phase inverter unit may include one three-phase inverter 10 or a plurality of three-phase inverters 10 connected in parallel, and the output end of the three-phase inverter unit is electrically connected to the construction electrical appliance.

[0096] When the load rated power is small or the number of loads is small, the three-phase inverter unit may include one three-phase inverter 10. When the load rated power is large or the number of loads is large, the three-phase inverter unit may include three or four parallel three-phase inverters 10. The three-phase inverter 10 included in the three-phase inverter unit can be selected according to the actual application scenario, which is not limited here.

[0097] When the construction electrical appliance is a three-phase load, the power supply end of the load is electrically connected to the three-phase output end of the three-phase inverter unit respectively, so that the three-phase inverter unit can supply power to the three-phase load.

[0098] When the construction electrical appliance is a single-phase load, the live wire end of the construction electrical appliance can be electrically connected to any two-phase output ends of the three-phase inverter unit, and the three-phase inverter unit outputs a single-phase power supply voltage to power the construction electrical appliance.

[0099] In other embodiments, the construction electrical appliance is a single-phase load, and any two of the three-phase output terminals of the three-phase inverter 10 in the three-phase inverter unit are connected in parallel. The live wire terminal of the construction electrical appliance can be electrically connected to the parallel output terminals, and the neutral wire terminal of the construction electrical appliance can be electrically connected to the third phase of the three-phase inverter 10. The three-phase inverter unit outputs a single-phase power supply voltage to power the construction electrical appliance.

[0100] According to the power supply system of the present application, the number of power phases for a single-phase load is two, and the number of power phases for a three-phase load is three. The control circuit generates a drive signal according to the working voltage, working frequency and number of power phases of the construction electrical appliances. The drive signal drives the three-phase inverter 10 to output a corresponding single-phase power supply voltage or a three-phase power supply voltage. The power supply voltage is used to power the construction electrical appliances. There is no need to introduce additional power supply equipment to power the three-phase loads and single-phase loads under construction, thereby reducing construction costs. Moreover, the three-phase inverter 10 used for construction is used for power supply, which makes it convenient to obtain power.

[0101] Reference Figure 6 In some embodiments, the load includes at least one single-phase load, the live wire terminal and the neutral wire terminal of the single-phase load are respectively electrically connected to the output terminals of any two phases of the three-phase output terminals of the three-phase inverter unit, and the third phase output terminal of the three-phase output terminal is suspended.

[0102] The connection relationship between the single-phase load and each output terminal can be selected according to the actual application scenario and is not limited here.

[0103] As an example, the three-phase inverter unit includes an A-phase output terminal, a B-phase output terminal and a C-phase output terminal. The live wire terminal of the single-phase load is electrically connected to the A-phase output terminal, the neutral wire terminal of the single-phase load is connected to the B-phase output terminal, and the C-phase output terminal of the three-phase inverter unit is suspended.

[0104] The controller 30 applies a first drive signal to the switch circuit corresponding to the A-phase output terminal and applies a second drive signal to the switch circuit corresponding to the B-phase output terminal, so that the three-phase inverter unit can supply power to the single-phase load, which is convenient to obtain power and low in cost.

[0105] Reference Figure 7 In some embodiments, the load includes at least one single-phase load, any two of the three-phase output ends of the three-phase inverter unit are connected in parallel to form a first output end, the other phase output end of the three-phase inverter unit serves as the second output end, the live wire end of the single-phase load is electrically connected to the first output end, and the neutral wire end of the single-phase load is electrically connected to the second output end.

[0106] As an example, the three-phase inverter unit includes a three-phase inverter 10, and the three-phase inverter 10 has an A-phase output terminal, a B-phase output terminal, and a C-phase output terminal. The A-phase output terminal and the B-phase output terminal are connected in parallel to form a first output terminal, and the first output terminal is electrically connected to the live wire terminal of the single-phase load, and the C-phase output terminal is electrically connected to the neutral wire terminal of the single-phase load as a second output terminal.

[0107] The controller 30 applies a first drive signal to the switch circuits corresponding to the A-phase output terminal and the B-phase output terminal, and applies a second drive signal to the switch circuit corresponding to the C-phase output terminal, so that the three-phase inverter unit can supply power to the single-phase load, which is convenient to obtain power and low in cost.

[0108] In some embodiments, the three-phase inverter unit includes a three-phase inverter, any two phase output ends of the three-phase inverter are connected in parallel to form a first output end, and the other phase output end of the three-phase inverter unit serves as a second output end.

[0109] Any two of the three-phase output ends of the three-phase inverter are connected in parallel to form a first output end, and the first output end can be used to be electrically connected to the live wire end of a single-phase load. The second output end of the three-phase inverter unit can be used to be electrically connected to the neutral wire end of the single-phase load, so that the three-phase inverter can supply power to the single-phase load, which is convenient to obtain electricity and low in cost.

[0110] Reference Figure 8 In some embodiments, the three-phase inverter unit includes multiple three-phase inverters 10, the first phases of the three-phase output ends of each three-phase inverter 10 are connected in parallel to form a first phase output end, the second phases of the three-phase output ends of each three-phase inverter 10 are connected in parallel to form a second phase output end, and the third phase output end of each three-phase inverter 10 on the AC side is suspended.

[0111] As an example, each three-phase inverter 10 has an A-phase output terminal, a B-phase output terminal, and a C-phase output terminal. The A-phase output terminals of each three-phase inverter 10 are connected in parallel to form a first-phase output terminal, the B-phase output terminals of each three-phase inverter 10 are connected in parallel to form a second-phase output terminal, the C-phase output terminal of each three-phase inverter 10 is suspended, the live wire terminal of a single-phase load can be electrically connected to the first-phase output terminal, and the neutral wire terminal of a single-phase load can be electrically connected to the second-phase output terminal.

[0112] The three-phase inverter unit includes a plurality of three-phase inverters 10, which can increase the output power of the three-phase inverter unit and facilitate power supply for a large number of single-phase loads or loads with a large rated power.

[0113] Reference Fig. 9In some embodiments, the three-phase inverter unit includes a plurality of three-phase inverters 10, wherein the first phase and the second phase of each three-phase inverter 10 are connected in parallel to form a first phase output end, and the third phase of the three-phase output ends of each three-phase inverter 10 are connected in parallel to form a second phase output end.

[0114] As an example, each three-phase inverter 10 has an A-phase output terminal, a B-phase output terminal, and a C-phase output terminal. The A-phase output terminal and the B-phase output terminal of each three-phase inverter 10 are connected in parallel to form a first-phase output terminal, and the C-phase output terminal of each three-phase inverter 10 is connected in parallel to form a second-phase output terminal. The live wire terminal of the single-phase load can be electrically connected to the first-phase output terminal, and the neutral wire terminal of the single-phase load can be electrically connected to the second-phase output terminal.

[0115] The three-phase inverter unit includes a plurality of three-phase inverters 10, which can increase the output power of the three-phase inverter unit and facilitate power supply for a large number of single-phase loads or loads with a large rated power.

[0116] Although the embodiments of the present application have been shown and described, those skilled in the art will appreciate that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present application, and that the scope of the present application is defined by the claims and their equivalents.

Claims

1. A power supply control method for a three-phase inverter, characterized in that: The DC side of the three-phase inverter is electrically connected to the photovoltaic module, and the AC side of the three-phase inverter is electrically connected to the construction electrical appliance. The power supply control method includes: When the three-phase inverter is in an off-grid condition, obtaining the operating voltage, operating frequency and power phase number of the construction electrical appliance; Generate a driving signal according to the operating voltage, the operating frequency and the number of power phases; The three-phase inverter is controlled according to the driving signal to supply power to the construction electrical appliances.

2. The power supply control method of the three-phase inverter according to claim 1, characterized in that: The generating of the driving signal according to the operating voltage, the operating frequency and the number of power supply phases comprises: When the number of phases of the power supply is two phases, a first phase voltage modulation wave and a second phase voltage modulation wave are generated, the amplitude and frequency of the first phase voltage modulation wave and the second phase voltage modulation wave are the same as the amplitude and the operating frequency of the working voltage, and the first phase voltage modulation wave and the second phase voltage modulation wave are 180° out of phase with each other; generating a first driving signal according to the first phase voltage modulation wave; A second driving signal is generated according to the second phase voltage modulation wave.

3. The power supply control method of the three-phase inverter according to claim 2, characterized in that: When the power supply has two phases, generating a first phase voltage modulation wave and a second phase voltage modulation wave comprises: Obtaining the feedback amplitude and feedback frequency of the input voltage of the construction electrical appliance; Determine the voltage reference Ud1 of the d-axis and the voltage reference Uq1 of the q-axis according to the amplitude of the working voltage and the feedback amplitude of the input voltage of the construction electrical appliance; Determining a reference phase θ1 according to the operating frequency and the feedback frequency of the input voltage of the construction electrical appliance; Determine the d-axis voltage reference Ud1, the q-axis voltage reference Uq1, and the α component of the reference phase θ1 after dq / αβ conversion as a first phase voltage modulation wave; The second phase voltage modulation wave is generated according to the first phase voltage modulation wave.

4. The power supply control method of the three-phase inverter according to claim 2, characterized in that: The controlling the three-phase inverter to supply power to the construction electrical appliance according to the driving signal comprises: According to the first driving signal, a switch circuit in the three-phase inverter corresponding to an output electrically connected to the live wire end of the construction electrical appliance is driven to operate; The switching circuit corresponding to the output electrically connected to the neutral terminal of the construction electrical appliance in the three-phase inverter is driven to operate according to the second driving signal.

5. The power supply control method of the three-phase inverter according to claim 1, characterized in that: The generating of the driving signal according to the operating voltage, the operating frequency and the number of power supply phases comprises: When the power supply has three phases, a three-phase modulation wave is generated, the amplitude and frequency of the three-phase modulation wave are the same as the amplitude and frequency of the working voltage, and the phases of the modulation waves of each phase in the three-phase modulation wave differ from each other by 120°; A first drive signal, a second drive signal and a third drive signal are generated respectively according to the three-phase modulation wave.

6. The power supply control method of the three-phase inverter according to claim 5, characterized in that: When the power supply has three phases, generating a three-phase modulation wave comprises: Obtaining the feedback amplitude and feedback frequency of the input voltage of the construction electrical appliance; Determine the voltage reference Ud2 of the d-axis and the voltage reference Uq2 of the q-axis according to the amplitude of the working voltage and the feedback amplitude of the input voltage of the construction electrical appliance; Determining a reference phase θ2 according to the operating frequency and the feedback frequency of the input voltage of the construction electrical appliance; The three-phase modulation wave of the d-axis voltage reference Ud2, the q-axis voltage reference Uq2 and the reference phase θ2 after dq / αβ conversion and αβ / abc conversion is obtained.

7. A power supply system, characterized in that: include: A three-phase inverter unit, wherein the three-phase inverter unit includes at least one three-phase inverter, a DC side of the three-phase inverter unit is connected to a DC source, and an AC side of the three-phase inverter unit is used to be electrically connected to a load; The three-phase inverter unit comprises a control circuit configured to execute the power supply method according to any one of claims 1-6.

8. The power supply system according to claim 7, characterized in that: The load includes at least one single-phase load, the live wire terminal and the neutral wire terminal of the single-phase load are respectively electrically connected to the output terminals of any two phases among the three-phase output terminals of the three-phase inverter unit, and the third phase output terminal among the three-phase output terminals is suspended.

9. The power supply system according to claim 7, characterized in that: The load includes at least one single-phase load, any two of the three-phase output ends of the three-phase inverter unit are connected in parallel to form a first output end, the other phase output end of the three-phase inverter unit serves as a second output end, the live wire end of the single-phase load is electrically connected to the first output end, and the neutral wire end of the single-phase load is electrically connected to the second output end.

10. The power supply system according to any one of claims 7 to 9, characterized in that: The three-phase inverter unit includes a three-phase inverter, any two phase output ends of the three-phase output ends of the three-phase inverter are connected in parallel to form a first output end, and the other phase output end of the three-phase inverter unit serves as a second output end.

11. The power supply system according to any one of claims 7 to 9, characterized in that: The three-phase inverter unit includes multiple three-phase inverters, the first phases of the three-phase output ends of each three-phase inverter are connected in parallel to form a first phase output end, the second phases of the three-phase output ends of each three-phase inverter are connected in parallel to form a second phase output end, and the third phase output end of the AC side of each three-phase inverter is suspended.

12. The power supply system according to any one of claims 7 to 9, characterized in that: The three-phase inverter unit includes a plurality of three-phase inverters, wherein the first phase and the second phase of each of the three-phase inverters are connected in parallel to form a first phase output end, and the third phase of the three-phase output ends of each of the three-phase inverters are connected in parallel to form a second phase output end.

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