Power supply circuit and electrical equipment

Abstract

The invention discloses a power supply circuit and electrical equipment. The power supply circuit comprises a three-phase power supply and three rectification and inversion modules, wherein each rectification and inversion module comprises a first input end, a second input end and an output end; the first input ends of the three rectification inversion modules are respectively connected to three phase lines in a three-phase power supply in a one-to-one correspondence manner; second input ends of the three rectification inversion modules are connected to a neutral line in the three-phase power supply; the output ends of the three rectification inversion modules are respectively connected to three loads in a one-to-one correspondence manner; and the rectifying and inverting module is used for sequentially rectifying and inverting the input voltage and then supplying power to corresponding loads. According to the invention, the three-phase power supply is divided into three independent single-phase power supply paths for three loads, single-phase rectification is carried out on each phase independently, the voltage level is reduced, a low-voltage-level device can be selected, and the cost is reduced; the three-phase load is balanced, the harmonic dispersion is realized, and the harmonic pollution is reduced; fault area isolation is realized, and maintenance difficulty and maintenance cost are reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of power supply, and in particular to a power supply circuit and electrical equipment. Background Art

[0002] At present, with the widespread application of air-conditioning equipment, the market demand for three-phase electric air conditioners is increasing, but it also faces three core challenges.

[0003] (1) Cost pressure: The prices of core components such as three-phase compressors and high-power IPM modules (Intelligent Power Modules) are higher than those of single-phase systems, and the heat dissipation design is more complex.

[0004] (2) After-sales maintenance is complicated: inter-phase short circuit or phase loss faults require professional instruments for diagnosis, which increases the maintenance time. The three-phase module is highly integrated, and local damage often requires overall replacement, which increases the cost of spare parts.

[0005] (3) Harmonic pollution: The 5th and 7th harmonics cause cable overheating and grid voltage distortion. Although active PFC (Power Factor Correction) is effective, it increases costs. The passive filtering solution uses a three-phase power filter, which is large in size and difficult to arrange in a compact external unit due to limited space.

[0006] With respect to the problems of high cost and large harmonics in the power supply mode of three-phase electric air conditioners in the prior art, no effective solution has been proposed so far. Summary of the Invention

[0007] The embodiments of the present invention provide a power supply circuit and an electrical device to at least solve the problems of high cost and large harmonics in the power supply mode of a three-phase electric air conditioner in the prior art.

[0008] To solve the above technical problems, an embodiment of the present invention provides a power supply circuit, comprising: a three-phase power supply and three rectifier-inverter modules, each of the rectifier-inverter modules comprising a first input terminal, a second input terminal and an output terminal; The first input ends of the three rectifier and inverter modules are connected to the three phase lines of the three-phase power supply in a one-to-one correspondence; The second input terminals of the three rectifier and inverter modules are all connected to the neutral line of the three-phase power supply; The output ends of the three rectifier and inverter modules are connected to three loads in a one-to-one correspondence; The rectifier and inverter modules are used to rectify and invert the input voltage in sequence and then supply power to the corresponding loads. Three independent single-phase power supply paths are realized through the three rectifier and inverter modules, and power can be supplied to the three loads at the same time.

[0009] Optionally, the rectifier and inverter module includes: a rectifier circuit and an inverter circuit; The first input end of the rectifier circuit is connected to the corresponding phase line, the second input end of the rectifier circuit is connected to the neutral line, and the rectifier circuit is used to convert alternating current into direct current; The input end of the inverter circuit is connected to the output end of the rectifier circuit, and the output end of the inverter circuit is connected to a corresponding load. The inverter circuit is used to convert direct current into alternating current to drive the corresponding load to operate.

[0010] Optionally, the DC voltage output by the rectifier circuit is a preset voltage value less than 540V.

[0011] Optionally, the rectifier circuit is a single-phase rectifier circuit.

[0012] Optionally, the inverter circuit is a three-phase inverter circuit.

[0013] Optionally, each of the rectifier and inverter modules is correspondingly provided with: a current sampling circuit connected to the output end of the inverter circuit, for collecting the phase current output by the inverter circuit in real time; A controller is connected to the current sampling circuit and the inverter circuit, and is used to adjust the PWM duty cycle according to the phase current so that the amplitudes of the three-phase currents output by the inverter circuit are equal and the phase difference is 120 degrees.

[0014] Optionally, the load is a compressor or a fan.

[0015] An embodiment of the present invention further provides an electrical device, including: the power supply circuit described in the embodiment of the present invention.

[0016] Optionally, the electrical equipment includes at least three loads.

[0017] Optionally, the electrical equipment is a three-phase electric air conditioner.

[0018] By applying the technical solution of the present invention, a three-phase power supply is split into three independent single-phase power supply paths through a three-phase four-wire system (L1, L2, L3, N) to supply three loads. Single-phase rectification is performed separately on each phase. The voltage output by the single-phase rectification (310V) is lower than the voltage output by the three-phase rectification (540V), which reduces the voltage level. Low-voltage level devices (such as low-voltage withstand rectifier circuits, inverter circuits, loads, etc.) can be selected to reduce costs. Three-phase independent rectification power supply balances the three-phase loads and eliminates the risk of neutral line overcurrent caused by load imbalance. At the same time, the rectification harmonics are also dispersed to the three phases to achieve harmonic dispersion. The phase difference of the three-phase harmonics cancels each other, the harmonic spectrum is diluted, the harmonic amplitude is reduced, and harmonic pollution is reduced. Fault area isolation is achieved. If a single-phase fault only affects the corresponding power supply path, other power supply paths can still operate normally, reducing the difficulty and cost of maintenance and improving maintenance efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is a schematic diagram of a three-phase electric air conditioner power supply in the prior art; Figure 2 This is a schematic diagram of a power supply circuit provided by an embodiment of the present invention. Figure 1 ; Figure 3 This is a schematic diagram of a power supply circuit provided by an embodiment of the present invention. Figure 2 ; Figure 4 It is a specific schematic diagram of the power supply circuit provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0020] To make the objectives, technical solutions, and advantages of the present invention more apparent, the present invention will be further described in detail below with reference to the accompanying drawings. It is apparent that the embodiments described are only some, not all, of the present invention. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without creative effort are intended to fall within the scope of protection of the present invention.

[0021] It should be noted that the terms "first", "second", etc. in the description, claims, and drawings of the present invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that the numbers used in this way are interchangeable where appropriate so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions. For example, a process, method, system, product, or apparatus that includes a series of steps or units is not necessarily limited to those steps or units that are clearly listed, but may include other steps or units that are not clearly listed or that are inherent to these processes, methods, products, or apparatus.

[0022] It should be understood that the term "and / or" as used herein is merely a description of the relationship between associated objects, indicating that three possible relationships exist. For example, "A and / or B" can represent: A exists alone, A and B exist simultaneously, or B exists alone. Furthermore, the character " / " in this document generally indicates that the associated objects are in an "or" relationship.

[0023] The optional embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0024] like Figure 1 Figure 2 shows a schematic diagram of a conventional three-phase air conditioner power supply, comprising a three-phase AC power source 1, a rectifier 2, an inverter 3, and a load 30. The three-phase AC power source 1 includes three phase lines, L1, L2, and L3. Rectifier 2 is a three-phase bridge rectifier circuit, with its input connected to the three phase lines and its output connected to the input of inverter 3. The output of inverter 3 is connected to load 30. Rectifier 2 converts the input AC power into DC power, while inverter 3 converts the DC power into AC power for supply to load 30. The three-phase AC power is input, rectified by rectifier 2, and outputs a DC bus voltage of 540V. This is then converted to AC power by inverter 3, driving load 30 (such as a compressor) to operate normally.

[0025] Figure 1 The power supply method shown has the problems of high cost, large harmonics, and complex fault maintenance.

[0026] This embodiment provides a power supply circuit that can be applied to electrical equipment, such as a three-phase air conditioner. Figure 2 As shown, the power supply circuit includes: a three-phase power supply 10 and three rectifier inverter modules 20, each of the rectifier inverter modules 20 includes a first input end, a second input end and an output end.

[0027] The first input terminals of the three rectifier-inverter modules 20 are connected to the three phase lines (L1, L2, and L3) of the three-phase power supply. The second input terminals of the three rectifier-inverter modules 20 are connected to the neutral line (N) of the three-phase power supply. The output terminals of the three rectifier-inverter modules 20 are connected to the three loads 30.

[0028] The rectifier and inverter modules 20 are used to rectify and invert the input voltage in sequence and then supply power to the corresponding load 30. Three independent single-phase power supply paths are realized through the three rectifier and inverter modules, and power can be supplied to the three loads at the same time.

[0029] This embodiment splits the three-phase power supply into three independent single-phase power supply paths through a three-phase four-wire system (L1, L2, L3, N) to supply three loads. Each phase undergoes independent single-phase rectification. The output voltage of the single-phase rectification (310V) is lower than the output voltage of the three-phase rectification (540V), reducing the voltage level. This allows the use of low-voltage components (such as low-voltage rectifier circuits, inverter circuits, and loads), thereby reducing costs. The three-phase independent rectification power supply balances the three-phase loads and eliminates the risk of neutral line overcurrent caused by load imbalance. It also disperses the rectification harmonics to the three phases, achieving harmonic dispersion. The phase difference (120°) of the three-phase harmonics cancels each other, diluting the harmonic spectrum and reducing harmonic amplitude, thereby reducing harmonic pollution. Fault area isolation is achieved. If a single-phase fault only affects the corresponding power supply path, the other power supply paths can still operate normally, reducing maintenance difficulty and cost, and improving maintenance efficiency. The problem of high cost and high harmonics in the existing three-phase electric air conditioner power supply method is solved.

[0030] In this embodiment, the three harmonic sources work independently, that is, each of the three phases generates harmonics, and the phase difference between the three phase harmonics is 120°. After synthesis, the amplitude is reduced, that is, the harmonics cancel each other out. For example, for the 5th harmonic, taking the A phase current as the reference, the phase of the A phase harmonic is 0°, the phase of the B phase harmonic is -120°, and the phase of the C phase harmonic is -240°. The vector sum of the three phase harmonic currents after synthesis is: I5_total = I5 × (1 + e -j120° + e -j240° ) = 0, where I5_total represents the sum of the three-phase harmonic current vectors, I5 represents the harmonic current vector of phase A, and I5 × e -j120° Represents the B-phase harmonic current vector, I5 × e -j240° represents the harmonic current vector of phase C. In other words, due to the phase cancellation of the three-phase harmonics, the harmonics in the circuit are almost zero, which greatly reduces the total harmonic content, the total THDi, and the EMI spectrum peak, thereby reducing harmonic pollution.

[0031] THDi stands for Total Harmonic Current Distortion, which refers to the total harmonic distortion of current. It's a measure of the distortion of the current waveform in power systems, representing the ratio of the sum of the harmonic components to the fundamental component. EMI stands for Electromagnetic Interference, which refers to electromagnetic interference.

[0032] The three rectifier and inverter modules 20 have the same structure. Figure 3 As shown, the rectifier and inverter module 20 includes a rectifier circuit 21 and an inverter circuit 22 .

[0033] A first input terminal of the rectifier circuit 21 is connected to a corresponding phase line ( L1 , L2 or L3 ), and a second input terminal of the rectifier circuit 21 is connected to the neutral line (N). The rectifier circuit 21 is used to convert alternating current into direct current.

[0034] The input end of the inverter circuit 22 is connected to the output end of the rectifier circuit 21 , and the output end of the inverter circuit 22 is connected to the corresponding load 30 . The inverter circuit 22 is used to convert direct current into alternating current to drive the corresponding load 30 to operate.

[0035] The rectifier-inverter module of this embodiment includes a rectifier circuit and an inverter circuit, which can convert the input voltage and output the required voltage to drive the load. Each phase performs single-phase rectification separately, which can reduce the voltage level, reduce costs, balance the three-phase load, achieve harmonic dispersion, reduce harmonic pollution, achieve fault area isolation, and reduce maintenance difficulty and cost.

[0036] The rectifier circuit 21 is a single-phase rectifier circuit that converts single-phase AC power into DC power. This embodiment does not limit the specific structure of the rectifier circuit, as long as it can convert single-phase AC power into DC power. Specifically, half-wave rectification, full-wave rectification, or bridge rectification can be used. This embodiment uses a single-phase rectifier circuit, which can reduce voltage levels and costs, disperse harmonics, reduce harmonic pollution, isolate fault areas, reduce maintenance difficulty and costs, and has a simple structure and is easy to implement.

[0037] The inverter circuit 22 is a three-phase inverter circuit that converts DC power into three-phase AC power. This embodiment does not limit the specific structure of the inverter circuit, as long as it can convert DC power into three-phase AC power. This embodiment uses a three-phase inverter circuit that can meet the power requirements of the load, has a simple structure, and is easy to implement.

[0038] The DC voltage output by the rectifier circuit 21 is a preset voltage value less than 540 V, specifically, 310 V. In this embodiment, each phase performs single-phase rectification. The voltage output by the single-phase rectification (310 V) is lower than the voltage output by the three-phase rectification (540 V), thus reducing the voltage level. Low-voltage components (e.g., low-voltage withstand rectifier circuits, inverter circuits, loads, etc.) can be used, thereby reducing costs.

[0039] In one embodiment, each rectifier and inverter module 20 is provided with a current sampling circuit and a controller. For each rectifier and inverter module, the current sampling circuit is connected to the output of the inverter circuit 22 and is used to collect the phase current output by the inverter circuit 22 in real time. A controller is connected to the current sampling circuit and the inverter circuit 22 and is used to adjust the PWM duty cycle based on the phase current so that the amplitudes of the three-phase currents output by the inverter circuit 22 are equal and the phase difference is 120°.

[0040] In this embodiment, each single-phase power supply path is equipped with a current-type PWM controller (for example, based on the SVPWM control algorithm), which monitors the phase current in real time and adjusts the PWM duty cycle to make the output current waveform close to sinusoidal. Through the synchronous control of the three-phase current phase, it ensures that the three-phase current amplitudes are equal and the phase difference is 120°, meeting the power supply requirements and reducing the harmonic content.

[0041] The load may be a compressor or a fan, thereby being able to independently power multiple loads in a three-phase electric air conditioner in separate phases, thereby reducing costs, achieving load self-balancing, harmonic dispersion, and reducing harmonic pollution.

[0042] This embodiment also provides an electrical device, including the power supply circuit described in the above embodiment. This embodiment splits a three-phase power supply into three independent single-phase power supply paths through a three-phase four-wire system (L1, L2, L3, N), supplying three loads. Each phase undergoes independent single-phase rectification. The voltage output by the single-phase rectification (310V) is lower than the voltage output by the three-phase rectification (540V), reducing the voltage level. This allows the use of low-voltage components (such as low-voltage rectifier circuits, inverter circuits, and loads), thereby reducing costs. The three-phase independent rectification power supply balances the three-phase loads, eliminating the risk of neutral line overcurrent caused by load imbalance. It also disperses the rectification harmonics across the three phases, achieving harmonic dispersion. The phase difference (120°) of the three-phase harmonics cancels each other out, diluting the harmonic spectrum and reducing harmonic amplitude, thereby reducing harmonic pollution. The fault area is isolated. If a single-phase fault only affects the corresponding power supply path, the other power supply paths can still operate normally, reducing maintenance difficulty and cost, and improving maintenance efficiency. The problem of high cost and high harmonics in existing power supply methods is solved.

[0043] The electrical equipment includes at least three loads, which can be powered by the three independent single-phase power supply paths.

[0044] The electrical equipment may be a three-phase electric air conditioner.

[0045] The power supply circuit described above is described below with reference to a specific example. However, it should be noted that this specific example is only for the purpose of better illustrating the present application and does not constitute an improper limitation on the present application. Explanations of terms that are the same or corresponding to those in the above examples will not be repeated in this example.

[0046] like Figure 4 As shown, taking a three-phase electric air conditioner as an example, the load 30 can be a compressor, a first fan, and a second fan. The three phase lines (L1, L2, L3) in the three-phase power supply correspond one-to-one with the three loads. There is no restriction on which phase line corresponds to which load, as long as there is a one-to-one correspondence. For example, L1-N, L2-N, and L3-N of the three-phase power correspond to the power supply circuits of the first fan, the second fan, and the compressor, respectively.

[0047] Rectifier circuit 21 utilizes a single-phase, full-wave bridge rectifier circuit, comprising four diodes. Inverter circuit 22 utilizes a three-phase, PWM bridge inverter circuit, comprising six switching devices (e.g., IGBTs, MOSFETs, etc.), organized into three groups (i.e., three bridge arms), with two switching devices in each group. By adjusting the duty cycle of the PWM signal, the switching devices in the three bridge arms are turned on and off, ensuring that the three-phase output currents have equal amplitudes and a phase difference of 120°, thereby controlling the output current or voltage.

[0048] This embodiment uses three-phase power input as its core power supply, utilizing rectifier and inverter circuits to efficiently drive loads (such as compressors and fans). The three-phase AC power supply consists of three phase lines (L1, L2, and L3) and a neutral line (N). Physically splitting the phases allows L1, L2, and L3 to be independently connected to the load. Phase-by-phase rectification is performed, with each phase converted to DC power via its corresponding rectifier circuit. The output of the rectifier circuit is connected to the input of the inverter circuit, which includes IGBT switches V1 through V6. This inverter circuit uses PWM modulation technology to convert DC power to AC, driving the compressor and fan.

[0049] In the prior art, a three-phase rectifier circuit is used, and the bus voltage output after rectification is 540V DC. This embodiment separates the three-phase circuit into separate phases for independent rectification and drive, i.e., each phase L1-N, L2-N, and L3-N is independently rectified, and the bus voltage output after rectification of each phase is 310V DC. This embodiment reduces the bus voltage (540V DC) of the traditional three-phase electrical level to the bus voltage (310V DC) of the single-phase electrical level. Compared with the traditional solution, the bus voltage after rectification in this embodiment is lower. By reducing the supply voltage, low-voltage rectifier circuits, inverter circuits, and loads can be selected, significantly reducing system costs. For example, in the traditional solution, a three-phase rectifier circuit with a withstand voltage rating of 1700V is used, while this embodiment uses a single-phase rectifier circuit with a withstand voltage rating of 800V, reducing costs.

[0050] In this embodiment, L1-N, L2-N, and L3-N correspond to different loads respectively, achieving balanced distribution of three-phase loads, which not only optimizes the power balance of the power grid, but also effectively disperses the concentration of harmonic currents and reduces harmonic pollution to the power grid.

[0051] In terms of technical implementation, after the three-phase power passes through its own rectifier circuit, the output DC voltage is 310V. Specifically, this 310V output voltage can be achieved using a DC-DC step-down module or directly through the topology design of the rectifier circuit. Three-phase rectifier circuits (especially uncontrolled rectifiers, such as three-phase bridge diode rectifier circuits) generate a large amount of harmonic current during operation, which can cause grid voltage waveform distortion and potentially lead to problems such as equipment overheating and communication interference. This embodiment splits the three-phase power supply into three independent single-phase power supply paths (each connected to a single-phase rectifier circuit) using a three-phase four-wire system (L1, L2, L3, N). This utilizes the phase cancellation characteristics of three-phase harmonics to reduce harmonic pollution. By splitting the three-phase power supply into single-phase power supply paths, this embodiment retains the high power characteristics of three-phase power while avoiding the harmonic problems of traditional three-phase rectifiers, achieving the dual goals of high efficiency and environmental protection.

[0052] The load balancing design of this embodiment further improves the stability of the system. By connecting different loads to the L1-N, L2-N, and L3-N circuits respectively, and independently supplying power to the three phases, the phase difference of the three-phase system is utilized to evenly distribute the load to the three phases L1, L2, and L3, avoiding single-phase overload and voltage fluctuations or line losses caused by excessive single-phase loads. At the same time, the balanced distribution of three-phase loads helps to balance the phase currents of the power grid, forcing the three-phase currents to meet the vector cancellation conditions, and the neutral current approaches 0, reducing the problem of excessive neutral current caused by load imbalance, thereby extending the life of the equipment and improving overall energy efficiency. This design is widely applicable in scenarios such as industrial equipment, air-conditioning systems, and power tools, and is particularly suitable for application environments with high requirements for power quality.

[0053] The power supply circuit of this embodiment also has fault tolerance. When a single-phase circuit fails, only the corresponding power supply path is affected, and the remaining power supply paths can still operate normally. The system's degraded operation capability is improved, avoiding the risk of a complete system shutdown due to a local failure. For example, L1-N, L2-N, and L3-N of the three-phase electricity correspond to the power supply circuits of the first fan, the second fan, and the compressor respectively. If the L2 line is abnormal, only the second fan is affected. The first fan and the compressor can still operate normally, avoiding the risk of a complete system shutdown due to a failure of the second fan. This redundant design significantly improves the user experience while reducing maintenance costs and downtime losses.

[0054] This embodiment provides a low-cost design circuit for a three-phase electric air conditioner, which independently rectifies and drives the three-phase electricity, thereby reducing costs, self-balancing the three-phase load, dispersing harmonics, isolating fault areas, and improving reliability.

[0055] The technical solution of the embodiment of the present invention achieves multi-dimensional optimization in terms of cost control, operational reliability, grid compatibility, and fault tolerance through the coordinated operation of three-phase power input, single-phase rectification circuit, and inverter circuit, combined with voltage step-down, load balancing, and harmonic dispersion strategies, providing an efficient, stable, and reliable technical solution for modern power electronic systems.

[0056] The embodiments described above are merely illustrative. The units described as separate components may or may not be physically separate, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed across multiple network units. Some or all of the modules may be selected to achieve the objectives of the present embodiment as needed.

[0057] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A power supply circuit, characterized in that: include: A three-phase power supply and three rectifier-inverter modules, each of which includes a first input terminal, a second input terminal, and an output terminal; The first input ends of the three rectifier and inverter modules are connected to the three phase lines of the three-phase power supply in a one-to-one correspondence; The second input terminals of the three rectifier and inverter modules are all connected to the neutral line of the three-phase power supply; The output ends of the three rectifier and inverter modules are connected to three loads in a one-to-one correspondence; The rectifier and inverter modules are used to rectify and invert the input voltage in sequence and then supply power to the corresponding loads. Three independent single-phase power supply paths are realized through the three rectifier and inverter modules, and power can be supplied to the three loads at the same time.

2. The power supply circuit according to claim 1, wherein: The rectifier and inverter module includes: a rectifier circuit and an inverter circuit; The first input end of the rectifier circuit is connected to the corresponding phase line, the second input end of the rectifier circuit is connected to the neutral line, and the rectifier circuit is used to convert alternating current into direct current; The input end of the inverter circuit is connected to the output end of the rectifier circuit, and the output end of the inverter circuit is connected to a corresponding load. The inverter circuit is used to convert direct current into alternating current to drive the corresponding load to operate.

3. The power supply circuit according to claim 2, wherein: The DC voltage output by the rectifier circuit is a preset voltage value less than 540V.

4. The power supply circuit according to claim 2, characterized in that: The rectifier circuit is a single-phase rectifier circuit.

5. The power supply circuit according to claim 2, characterized in that: The inverter circuit is a three-phase inverter circuit.

6. The power supply circuit according to claim 2, characterized in that: Each of the rectifier and inverter modules is correspondingly provided with: a current sampling circuit connected to the output end of the inverter circuit, for collecting the phase current output by the inverter circuit in real time; A controller is connected to the current sampling circuit and the inverter circuit, and is used to adjust the PWM duty cycle according to the phase current so that the amplitudes of the three-phase currents output by the inverter circuit are equal and the phase difference is 120 degrees.

7. The power supply circuit according to any one of claims 1 to 5, characterized in that: The load is a compressor or a fan.

8. An electrical device, characterized in that: include: The power supply circuit according to any one of claims 1 to 7.

9. The electrical equipment according to claim 8, characterized in that: The electrical equipment includes at least three loads.

10. The electrical equipment according to claim 8, characterized in that: The electrical equipment is a three-phase electric air conditioner.

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