CN207304385U - A kind of single-phase X-type misplacement three-level AC stream regulating circuit - Google Patents

Abstract

A kind of single-phase X-type misplacement three-level AC stream regulating circuit, including main circuit part and switching tube protection part are the utility model is related to, wherein main circuit part includes power supply U_i, inductance L_i, inductance L_o, capacitance C₁, capacitance C₂, capacitance C, IGBT switching tube S₁, IGBT switching tubes S₂, IGBT switching tubes S₃, IGBT switching tubes S₄, IGBT switching tubes S₅, IGBT switching tubes S₆, diode D₁~D₄, diode D₀₁~D₀₈, resistance R.Switching tube protection portion point includes inductance L_r, capacitance C_r, capacitance C_S.Involved component number is less, cost is low, and pressure regulation translation circuit is simple in structure, it is possible to achieve the antiphase voltage of input and output is adjusted, and has the advantages that single stage shift, harmonic wave of output voltage are few, voltage stress is small and output voltage adjustable range is big.

Description

A single-phase X-type interleaved three-level AC voltage regulation circuit

technical field

The utility model relates to the technical field of power electronic voltage regulation, in particular to a single-phase X-type interleaved three-level AC voltage regulation circuit including the reverse phase output of a switch tube protection circuit.

Background technique

The AC voltage regulating circuit is a circuit that converts the AC input voltage into an AC power with adjustable voltage within a certain range through a conversion circuit. With the rapid development of power electronics technology, all walks of life have higher requirements for the performance of electrical equipment, and higher and higher requirements for voltage performance. The electrical equipment in many industries does not directly use the AC power provided by the grid as a power source, but transforms the AC power of the grid through various voltage regulating circuits, so as to obtain the required electrical energy form.

CN101039078A discloses a non-isolated direct voltage regulation circuit. CN102185481B and CN102882389A describe a circuit structure for converting from AC to DC, which can only be applied to LED lighting circuits. So far, the research of power electronics researchers at home and abroad has mainly focused on the indirect conversion of AC-DC-AC and the form of DC-DC conversion, and the research on AC-AC voltage regulation has mostly focused on the same-phase conversion circuit. structure; the research on multi-level voltage regulation conversion circuit is less than that of two-level voltage regulation circuit, and the research on multi-level circuit is mainly concentrated in multi-level inverter. For multi-level AC-AC direct conversion regulation Piezoelectric research is also limited. Most of the voltage regulation circuits studied have defects such as complex circuit structure, low output voltage waveform quality, and slow voltage regulation process.

When implementing the utility model, the inventor found that the double-tube bidirectional switching tube in the circuit can realize soft turn-off without adding a buffer circuit, but the single-tube bidirectional switching tube has a large number of high peaks voltage, and the existing RCD and other switching tube snubber circuits still have many peak voltages during the breaking process of the single-tube bidirectional switching tube, which cannot realize soft breaking well, which will undoubtedly increase the switching loss and reduce the regulation of the circuit. pressure efficiency.

Utility model content

The technical problem to be solved by the utility model is to provide a single-phase X-type interleaving three-level AC voltage regulating circuit, which can realize AC/AC chopping and direct inverse phase conversion, based on the structure of the DC conversion circuit , using the structure of the X-type interleaved switching tube to output three levels, so that the voltage regulating circuit has the advantages of a three-level voltage regulating conversion circuit, with simple circuit structure, single-stage conversion, less output voltage harmonics, small voltage stress, And the advantages of fast output voltage regulation. At the same time, the switch tube protection part in the circuit can realize the soft turn-off of the single-tube bidirectional switch tube and reduce the switching loss.

The technical solution adopted by the utility model to solve the technical problem is: a single-phase X-type interleaved three-level AC voltage regulating circuit, including a main circuit part and a switch tube protection part, wherein the main circuit part includes a power supply U _i , Inductor L _i , inductor L _o , capacitor C ₁ , capacitor C ₂ , capacitor C, IGBT switch S ₁ , IGBT switch S ₂ , IGBT switch S ₃ , IGBT switch S ₄ , IGBT switch S ₅ , IGBT switch tube S ₆ , diodes D ₁ -D ₄ , diodes D ₀₁ -D ₀₈ , and resistor R. The switch tube protection part includes L _r1 (L _r2 ), capacitor C _r1 (C _r2 ), and capacitor C _S1 (C _S2 ). IGBT switch tube S ₁ , IGBT switch tube S ₂ , D ₁ , and D ₂ form a double-tube bidirectional switch tube; IGBT switch tube S ₃ , IGBT switch tube S ₄ , D ₃ , and D ₄ form another double-tube bidirectional switch tube; The IGBT switch tubes S ₅ , D ₀₁ -D ₀₄ form a single-tube bidirectional switch tube; the IGBT switch tubes S ₆ , D ₀₅ -D ₀₈ form another single-tube bidirectional switch tube. The connection method of the above devices is: one end of the power supply U _i is connected to one end of L _i , the other end of L _i is connected to one end of C ₁ , C _S1 , L _r1 , and at the same time connected to the drain of S ₁ and the cathode of D ₁ , the source of S ₁ is connected to the source of S ₂ and the anode of D ₂ , the drain of S ₂ is connected to the cathode of D ₂ , and at the same time connected to the other end of U _i , C _S2 , L _r2 , and one end of C ₂ , the other end of L _r1 is connected to the anode of D ₀₁ and the cathode of D ₀₃ , the cathode of D ₀₁ is connected to the cathode of D ₀₂ , the drain of S ₅ , and one end of C _r1 , the source of S ₅ is connected to the anode of D ₀₃ , The anode of D ₀₄ is connected to the other end of C _r1 , the other end of L _r2 is connected to the anode of D ₀₅ , the cathode of D ₀₇ , the cathode of D ₀₅ is connected to the cathode of D ₀₆ , the drain of S ₆ , and one end of C _r2 , The source of S ₆ is connected to the anode of D ₀₇ , the anode of D ₀₈ , and the other end of C _r2 , the other end of C ₁ is connected to the anode of D ₀₆ , the cathode of D ₀₈ , and the other end of C _S2 , and at the same time it is connected to S ₃ The drain of C2 is connected, one end of L _o is connected, the other end of _C2 is connected to the anode of _D02 , the cathode of _D04 , the other end of C _S2 is connected to the drain of _S4 at the same time, the drain of _S3 is connected to D The cathode of ₃ is connected, the source of S ₃ is connected to the anode of D ₃ , the source of S ₄ is connected, the source of S ₄ is connected to the anode of D ₄ , the drain of S ₄ is connected to the cathode of D ₄ , _the The other end is connected to one end of C and R, and the other ends of C and R are connected to the drain of _S4 .

The above-mentioned single-phase X-type interleaved three-level AC voltage regulation circuit, the working principle of the main circuit voltage regulation conversion is: according to the polarity division of the input voltage U _i of the single-phase three-level AC-AC conversion circuit, the regulation The voltage conversion circuit is divided into two modes (I) and (II), and each mode is further divided into four switching modes.

Among them, the (I) mode is when U _i > 0, the switching tubes S ₂ and S ₄ are in the half-period cut-off state, and the four switching modes are:

Switching mode 1: S ₅ is turned on and the rest are turned off. The power supply U _i charges the capacitor C ₂ through the loop formed by U _i , L _i , D ₀₁ , S ₅ , D ₀₄ , and C ₂ . The right _end of the capacitor C ₂ is positive and stores energy for the inductor L _i at the same time. The loop formed by C ₁ , D ₀₁ , S ₅ , D ₀₄ , R, and L _o supplies power to the inductor L _o and the load R. At this time, the output level at both ends of ab is -U _C , where U _C is the voltage at both ends of C ₁ ;

Switching mode 2: S ₁ is turned on and the rest are turned off. The circuit formed by the power supply U _i through U _i , L _i , S ₁ and D ₂ stores energy for the inductance L _i , while the capacitors C ₁ and C ₂ are formed by C ₁ , S ₁ , D ₂ , C ₂ , R and L _o The loop of the inductor L _o and the load R supplies power. At this time, the output level at both ends of ab is -2U _C , where 2U _C is the voltage at both ends of C ₁ and C ₂ ;

Switching mode 3: S ₆ is turned on, and the rest are turned off. Power supply U _i and inductor L _i charge capacitor C ₁ through the loop formed by U _i , L _i , C ₁ , D ₀₆ , S ₆ , and D ₀₇ , the left end of capacitor C ₁ is positive, and capacitor C ₂ passes through R, L _o , D ₀₆ , S ₆ , and D ₀₇ form a loop to supply power to the inductor L _o and the load R. At this time, the output level at both ends of ab is -U _C , where U _C is the voltage at both ends of C ₂ ;

Switching mode 4: S ₃ is turned on and the rest are turned off. The power supply U _i and the inductor L _i charge the capacitors C 1 and C 2 through the loop formed by U _i , L _i , C ₁ , S ₃ , D ₄ , and C ₂ , while the inductor L _o charges the capacitors C ₁ and C ₂ through L _o , S ₃ , and D ₄ , R constitutes the loop for the load R freewheeling. At this time, the output level at both ends of ab is zero.

(II) The mode is that when U _i <0, the switch tubes S ₁ and S ₃ are in the half-period cut-off state, and the four switch modes are:

Switching mode 1: S ₆ is turned on and the rest are turned off. The power supply U _i charges the capacitor C ₁ through _the loop formed by U _i , D ₀₅ , S ₆ , D ₀₈ , C ₁ , and L _i . The right end of the capacitor C ₁ is positive and stores energy for the inductor L _i at the same time. The loop formed by C ₂ , D ₀₅ , S ₆ , D ₀₈ , L _o , and R supplies power to the inductor L _o and the load R. At this time, the output level at both ends of ab is U _C , where U _C is the voltage at both ends of C ₂ ;

Switching mode 2: S ₂ is turned on and the rest are turned off. The circuit formed by the power supply U _i through U _{i ,} S ₂ , D ₁ , and L _i stores energy for the inductance L i, and the capacitors C ₁ and C ₂ are formed by C ₁ , L _o , R, C ₂ , S ₂ , and D ₁ The loop of the inductor L _o and the load R supplies power. At this time, the output level at both ends of ab is 2U _C , where 2U _C is the voltage at both ends of C ₁ and C ₂ ;

Switching mode 3: S ₅ is turned on and the rest are turned off. Power supply U _i and inductor L _i charge capacitor C ₂ through the loop formed by U _i , C ₂ , D ₀₂ , S ₅ , D ₀₃ , and L _i. The left end of capacitor C ₂ is positive, and capacitor C ₁ passes through C ₁ , L The loop formed by _o , R, D ₀₂ , S ₅ , and D ₀₃ supplies power to the inductor L _o and the load R. At this time, the output level at both ends of ab is U _C , where U _C is the voltage at both ends of C ₁ ;

Switching mode 4: S ₄ is turned on and the rest are turned off. The power supply U _i and the inductor L _i charge the capacitors C 1 and C 2 through the loop formed by U _i , C ₂ , S ₄ , D ₃ , C ₁ , and L _i , while the inductor L _o charges the capacitors C ₁ and C ₂ through L _o , R, S ₄ , The loop formed by D ₃ is the freewheeling flow of the load R. At this time, the output level at both ends of ab is zero.

In the above-mentioned single-phase X-type interleaved three-level AC voltage regulating circuit, the output voltage and the input voltage realize reverse phase conversion.

The above-mentioned single-phase X-type interleaving three-level AC voltage regulation circuit, as long as the conduction time of the three levels of 0, U _C and 2 U _C at the ab output terminal is adjusted, the input and output voltages can be adjusted freely. Voltage function, and the voltage output of the ab terminal is a three-level form, which belongs to the multi-level conversion technology. Compared with the two-level circuit, it has the advantages of high output voltage sine degree, small voltage stress, less voltage harmonics, and low distortion rate.

The above-mentioned single-phase X-type interleaved three-level AC voltage regulation circuit, in order to avoid the breakdown of the switch tube in practical applications, the switch tube protection circuit used, that is, the CLC snubber circuit, is a new type of topology circuit. _r , capacitor C _r , and C _S , CLC is combined with the freewheeling diode of the single-tube bidirectional switch, which can realize the soft turn-off of the single-tube bidirectional switch in the conversion circuit, which can reduce the peak voltage and voltage stress, and slow down the switching The tube voltage rises rapidly.

The above-mentioned single-phase X-type interleaved three-level AC voltage regulation circuit uses a switch tube protection circuit, namely a CLC buffer circuit, which is mainly used to protect the single-tube bidirectional switch tube in the main circuit. For other Buck, Boost, Buck- The circuit applied to the single-tube bidirectional switch tube in the AC direct conversion circuit such as boost is also applicable.

The working principle of the CLC snubber circuit used in the above-mentioned single-phase X-type interleaved three-level AC voltage regulating circuit is: it can be divided into the process analysis of the switch tube _S5 and the switch tube _S6 , which is further divided into the switch tube Analysis of the turn-on process and turn-off process, the process analysis of the switch tube _S5 is as follows: 1) When the switch tube _S5 is turned on, due to the effect of the snubber inductance L _r and the turn-on effect of the diode D ₀₁ in the circuit, the switch tube _S5 realizes zero current conduction. After S ₅ is turned on, the voltage V _Cr at both ends of the capacitor C _r decreases first, and V _Cr < V _CS , at this time, the power supply and C _s together store energy for L _r , and the inductor current i _Lr gradually rises, due to the capacitance C _S exists, i _Lr is greater than the current in the circuit, and then V _Cr and V _CS continue to drop, and the current in the inductor and switch tube gradually recovers to the circuit current. Finally, V _Cr =V _CS =0, i _Lr =i _S1 =I _L , The activation process is over. The converter enters the normal working state. 2) The switch tube S ₅ is turned off, because the voltage of the snubber capacitor C _r does not change abruptly, the voltage V _Cr at both ends of the capacitor is still 0, and the switch tube realizes zero-voltage turn-off. The current i _S1 in the switch tube _S5 drops rapidly, but the inductor current i _Lr does not drop rapidly. At this time, i _Lr forms a loop through D ₀₁ , C _r , and D ₀₃ , and V _Cr and V _CS rise synchronously. When the switch tube _S5 is completely cut off, the voltage of C _r is still increasing under the action of the discharge of the power supply and snubber inductor until it rises to U _C . Finally, V _Cr =V _CS = _UC , i _Lr =i _S1 =0, and the turn-off process ends. The converter enters the normal working state. The turn-on and turn-off process of the switch _S6 is similar to that of _S5 .

The above-mentioned single-phase X-type interleaved three-level AC voltage regulating circuit, the components involved are all well-known to those skilled in the art and can be purchased commercially, and the connection and installation methods of the components involved It is within the grasp of those skilled in the art.

The remarkable progress of the utility model is that, compared with the prior art, the outstanding substantive features and remarkable progress of the utility model are as follows:

1) The utility model is a single-phase X-type interleaving three-level AC voltage regulating circuit, which is a new type of three-level AC-AC voltage regulating circuit, which can realize the reverse phase conversion of input and output voltages.

2) The utility model is a single-phase X-type interleaved three-level AC voltage regulating circuit, which has the advantages of simple topology, small voltage stress, and single-stage conversion. It not only realizes three-level conversion and wide output voltage The range adjustment improves the power density and efficiency of the circuit, and also reduces the distortion rate of the voltage waveform and the conduction loss of the IGBT switch tube.

3) The utility model is a single-phase X-type interleaved three-level AC voltage regulation circuit. In the mode switching of the voltage regulation conversion circuit, only two switching tubes are converted each time. Compared with other multi-voltage The switch between the conduction modes of the flat AC voltage regulating circuit is relatively simple. In each mode, only one switch tube is in the conduction state, which reduces the loss and improves the conversion efficiency. In the positive and negative cycles of the input voltage, Two pairs of switch tubes with symmetrical structure and symmetrical conduction time provide convenient conditions for the control and drive circuit of the voltage regulation conversion circuit.

4) The utility model is a single-phase X-type interleaved three-level AC voltage regulation circuit, which uses a new type of switch tube protection circuit CLC buffer circuit, which reduces the risk of breakdown of the IGBT switch tube due to overvoltage. In the working process of the main circuit, there is no need to set a dead time for each working mode, and the soft turn-off of the IGBT switching tube is realized.

Description of drawings

Below in conjunction with accompanying drawing and embodiment the utility model is further described.

Fig. 1 is a general circuit topology diagram of a single-phase X-type interleaved three-level AC voltage regulating circuit of the present invention.

Fig. 2 is a schematic diagram of the working process of the main circuit of a single-phase X-type interleaved three-level AC voltage regulating circuit of the present invention.

Fig. 3 is a topological diagram of a switching tube protection circuit of a single-phase X-type interleaved three-level AC voltage regulating circuit of the present invention.

Detailed ways

The embodiment shown in Figure 1 shows that the total circuit topology of a single-phase X-type interleaved three-level AC voltage regulating circuit of the present invention includes an AC power supply U _i , seven capacitors C ₁ , C ₂ , C, C _r1 , C _r2 , C _S1 , C _S2 , four inductors L _i , L _o , L _r1 , L _r2 , six IGBT switch tubes S ₁ , S ₂ , S ₃ , S ₄ , S 5 , _{S 6} , twelve fast recovery diodes D ₁ -D ₄ , D ₀₁ -D ₀₈ , and one resistor R. Among them, S ₁ , S ₂ , D ₁ , and D ₂ form a double-tube bidirectional switch tube, S ₃ , S ₄ , D ₃ , and D ₄ form another double-tube bidirectional switch tube, and S ₅ , D ₀₁ ~ D ₀₄ form a single-tube bidirectional switch tube. Bi-directional switching tubes, S ₆ , D ₀₅ -D ₀₈ form another single-tube bi-directional switching tube. The connection method of the above devices is: one end of the input power U _i is connected to one end of L _i , the other end of L _i is connected to one end of C ₁ , C _S1 , L _r1 , and at the same time connected to the drain of S ₁ and the cathode of D ₁ Connection, the source of S ₁ is connected to the source of S ₂ and the anode of D ₂ , the drain of S ₂ is connected to the cathode of D ₂ , and at the same time connected to the other end of U _i , C _S2 , L _r2 , and one end of C ₂ The other end of L _r1 is connected to the anode of D ₀₁ and the cathode of D ₀₃ , the cathode of D ₀₁ is connected to the cathode of D ₀₂ , the drain of S ₅ , and one end of C _r1 is connected, and the source of S ₅ is connected to that of D ₀₃ The anode, the anode of D ₀₄ , the other end of C _r1 are connected, the other end of L _r2 is connected with the anode of D ₀₅ , the cathode of D ₀₇ , the cathode of D ₀₅ is connected with the cathode of D ₀₆ , the drain of S ₆ , the drain of C _r2 One end is connected, the source of S ₆ is connected to the anode of D ₀₇ , the anode of D ₀₈ , and the other end of C _r2 , the other end of C ₁ is connected to the anode of D ₀₆ , the cathode of D ₀₈ , and the other end of C _S2 , and at the same time Connect to the drain of S ₃ , one end of L _o , the other end of C ₂ to the anode of D ₀₂ , the cathode of D ₀₄ , the other end of C _S2 , and at the same time connect to the drain of S ₄ , the drain of S ₃ The pole is connected to the cathode of _D3 , the source of _S3 is connected to the anode of _D3 , the source of _S4 is connected, the source of _S4 is connected to the anode of _D4 , the drain of _S4 is connected to the cathode of _D4 , The other end of L _o is connected to one end of C and R, and the other ends of C and R are connected to the drain of _S4 . The example in the figure shows that the circuit structure of this three-level circuit satisfies the basic _structure of _the Cuk type circuit. It is simple and has a symmetrical structure, which can realize symmetrical control in the positive and negative half cycles of the input power supply, and the control method is simple.

The embodiment shown in Fig. 2 shows, a kind of single-phase X-type interleaved three-level AC voltage regulating circuit of the utility model main circuit voltage regulating conversion working process schematic diagram, wherein figure (I) is when mode (I) The four switch mode diagrams, in this mode, the left end of capacitor _C1 is positive, and the right end of capacitor _C2 is positive. Figure (a) is switching mode 1: S ₅ is turned on, and the rest are turned off. The circuit formed by power supply U _i , L _i , D ₀₁ , S ₅ , D ₀₄ , and C ₂ , and the circuit formed by capacitor C ₁ , D ₀₁ , S ₅ , D ₀₄ , R, and L _o . Figure (b) is switch mode 2: S ₁ is turned on, and the rest are turned off. The loop formed by power supply U _i , L _i , S ₁ , D ₂ and the loop formed by capacitor C ₁ , S ₁ , D ₂ , C ₂ , R, L _o . Figure (c) is switch mode 3: S ₆ is turned on, and the rest are turned off. The loop formed by power supply U _i , L _i , C ₁ , D ₀₆ , S ₆ , D ₀₇ , and the loop formed by capacitor C ₂ , R, L _o , D ₀₆ , S ₆ , D ₀₇ . Figure (d) is switch mode 4: S ₃ is turned on, and the rest are turned off. The loop formed by the power supply U _i , L _i , C ₁ , S ₃ , D ₄ , and C ₂ , and the loop formed by the inductance L _o , S ₃ , D ₄ , and R. Figure (II) shows four switching modes in mode (II). In this mode, the right terminal of capacitor C ₁ is positive, and the left terminal of capacitor C ₂ is positive. Figure (e) is switching mode 1: S ₆ is turned on, and the rest are turned off. The circuit formed by power supply U _i , D ₀₅ , S ₆ , D ₀₈ , C ₁ , L _i , and the circuit formed by capacitor C ₂ , D ₀₅ , S ₆ , D ₀₈ , L _o , R. Figure (f) is switch mode 2: S ₂ is turned on, and the rest are turned off. The loop formed by the power supply U _i , S ₂ , D ₁ , and L _i , and the capacitors C ₁ , C ₂ pass through the loop formed by C ₁ , L _o , R, C ₂ , S ₂ , and D ₁ . Figure (g) is switch mode 3: S ₅ is turned on, and the rest are turned off. The circuit formed by power supply U _i , C ₂ , D ₀₂ , S ₅ , D ₀₃ , L _i , and the circuit formed by capacitor C ₁ , L _o , R, D ₀₂ , S ₅ , D ₀₃ . Figure (h) is switch mode 4: S ₄ is turned on, and the rest are turned off. The loop formed by power supply U _i , C ₂ , S ₄ , D ₃ , C ₁ , L _i , and the loop formed by inductance L _o , R, S ₄ , D ₃ .

The embodiment shown in Fig. 3 shows that the CLC buffer protection circuit of the switch tubes S ₅ and S ₆ of a single-phase X-type interleaved three-level AC voltage regulating circuit of the present invention includes an inductor L _r and two capacitors C _S , C _r . One end of the capacitor C _S in the circuit is connected to one end of the inductor L _r , the other end of the inductor L _r is connected to the anode of D ₀₁ (D ₀₅ ) and the cathode of D ₀₃ (D ₀₇ ), and the cathode of D ₀₁ (D ₀₅ ) is connected to the switch tube Drain of S ₅ (S ₆ ), cathode of D ₀₂ (D ₀₆ ), one end of capacitor C _r , source of S ₅ (S ₆ ) connected to anode of D ₀₃ (D ₀₇ ), D ₀₄ (D ₀₈ ) The anode of D ₀₄ (D ₀₈ ) is connected to the anode of D ₀₂ (D ₀₆ ), the other end of capacitor C _r is the other end of capacitor C _r . The CLC circuit is combined with the diode in the single-tube bidirectional switch tube to realize zero breaking of the switch tube in the conversion circuit. It is also applicable to circuits applied to single-tube bidirectional switch tubes in other AC direct conversion circuits such as Buck, Boost, and Buck-boost.

Claims (5)

1. A single-phase X-type interleaved three-level AC voltage regulating circuit, characterized in that it includes a main circuit part and a switch tube protection part, wherein the main circuit part includes a power supply U _i , an inductor L _i , an inductor L _o , Capacitor C ₁ , capacitor C ₂ , capacitor C, IGBT switch S ₁ , IGBT switch S ₂ , IGBT switch S ₃ , IGBT switch S ₄ , IGBT switch S ₅ , IGBT switch S ₆ , diode D ₁ ～D ₄ , diodes D ₀₁ ～D ₀₈ ; the switch tube protection part includes inductance L _r1 , inductance L _r2 , capacitance C _r1 , capacitance C _r2 , capacitance C _S1 , and capacitance C _S2 ; the connection method of the above devices is: power supply U _i One end of _Li is connected to one end of Li, the other end of _Li is connected to one end of C ₁ , C _S1 , L _r1 , and at the same time is connected to the drain of S ₁ and the cathode of D ₁ , the source of S ₁ is connected to that of S ₂ The source and the anode of D ₂ are connected, the drain of S ₂ is connected to the cathode of D ₂ , and at the same time connected to the other end of U _i , C _S2 , L _r2 , and one end of C ₂ , and the other end of L _r1 is connected to D ₀₁ The anode, the cathode of D ₀₃ , the cathode of D ₀₁ is connected to the cathode of D ₀₂ , the drain of S ₅ , and one end of C _r1 , the source of S ₅ is connected to the anode of D ₀₃ , the anode of D ₀₄ , and the other end of C _r1 Connect, the other end of L _r2 is connected to the anode of D ₀₅ , the cathode of D ₀₇ , the cathode of D ₀₅ is connected to the cathode of D ₀₆ , the drain of S ₆ , and one end of C _r2 is connected, the source of S ₆ is connected to the anode of D ₀₇ , the anode of D ₀₈ , the other end of C _r2 is connected, the other end of C ₁ is connected with the anode of D ₀₆ , the cathode of D ₀₈ , the other end of C _S2 , and the drain of S ₃ is connected, and one end of L _o is connected , the other end of _C2 is connected to the anode of _D02 , the cathode of _D04 , the other end of C _S2 , and at the same time connected to the drain of _S4 , the drain of _S3 is connected to the cathode of _D3 , and the source of _S3 Connect to the anode of D ₃ and the source of S ₄ , the source of S ₄ is connected to the anode of D ₄ , the drain of S ₄ is connected to the cathode of D ₄ , the other end of L _o is connected to one end of C and R, The other ends of C and R are connected to the drain of S ₄ ; two single-tube bidirectional switch tubes X-type are interleaved in the circuit between C ₁ and C ₂ two capacitors to form a circuit structure. 2. A single-phase X-type interleaved three-level AC voltage regulating circuit according to claim 1, characterized in that: the capacitors C ₁ and C ₂ have the same capacitance. 3. A single-phase X-type interleaved three-level AC voltage regulating circuit according to claim 1, the CLC snubber circuit of the switching tube protection part is characterized in that: an inductor L _r , two capacitors C _S , C _r ; One end of the capacitor C _S in the circuit is connected to one end of the inductor L _r , the other end of the inductor L _r is connected to the anode of D ₀₁ (D ₀₅ ) and the cathode of D ₀₃ (D ₀₇ ), and the cathode of D ₀₁ (D ₀₅ ) is connected to the switch Drain of tube S ₅ (S ₆ ), cathode of D ₀₂ (D ₀₆ ), one end of capacitor C _r , source of S ₅ (S ₆ ) connected to anode of D ₀₃ (D ₀₇ ), D ₀₄ (D ₀₈ ) anode, the other end of the capacitor C _r , the cathode of D ₀₄ (D ₀₈ ) is connected to the anode of D ₀₂ (D ₀₆ ), the other end of the capacitor C _S ; the CLC snubber circuit is combined with the diode in the single-tube bidirectional switch , to achieve zero breaking of the switching tube in the conversion circuit. 4. A single-phase X-type interleaved three-level AC voltage regulating circuit according to claim 1, characterized in that: the switch tube drive circuit adopts Infineon 1ED020I12-F drive chip, and the control chip adopts dsPIC30f6014A. 5. a kind of single-phase X-type interleaved three-level AC voltage regulating circuit according to claim 1, is characterized in that: be divided into (I), (II) two modes, divide again under each mode There are four switching modes; Among them, the (I) mode is when U _i > 0, the switching tubes S ₂ and S ₄ are in the half-period cut-off state, and the four switching modes are: Switching mode 1: S ₅ is turned on, and the rest are turned off; the power supply U _i charges the capacitor C ₂ through the loop formed by U _i , L _i , D ₀₁ , S ₅ , D ₀₄ , and C ₂ , and the right end of the capacitor C ₂ is positive. At the same time, it stores energy for the inductor L _i , and the capacitor C ₁ supplies power to the inductor L _o and the load R through the loop formed by C ₁ , D ₀₁ , S ₅ , D ₀₄ , R, and L _o ; is -U _C , where U _C is the voltage across C ₁ ; Switching mode 2: S ₁ is turned on, and the rest are turned off; the circuit formed by the power supply U _i through U _i , L _i , S ₁ , and D ₂ stores energy for the inductance L _i , and the capacitors C ₁ and C ₂ pass through C ₁ , S _1. The loop formed by D ₂ , C ₂ , R, and L _o supplies power to the inductor L _o and the load R; at this time, the output level at both ends of ab is -2U _C , where 2U _C is the voltage at both ends of C ₁ and C ₂ ; Switching mode 3: S ₆ is turned on, and the rest are turned off; power supply U _i and inductor L _i charge capacitor _C 1 through a loop formed by U _i , L _i , C ₁ , D ₀₆ , S ₆ , and D ₀₇ , and capacitor C ₁ The left end is positive, and the capacitor C ₂ supplies power to the inductor L _o and the load R through the loop formed by R, L _o , D ₀₆ , S ₆ , and D ₀₇ ; at this time, the output level at both ends of ab is -U _C , where U _C is the voltage across _C2 ; Switching mode 4: S ₃ is turned on, and the rest are turned off; the power supply U _i and the inductor L _i charge the capacitors C ₁ and _C 2 through the loop formed by U _i , L _i , C ₁ , S ₃ , D ₄ , and C ₂ , The loop formed by the inductance L _o through L _o , S ₃ , D ₄ , and R continues to flow for the load R; at this time, the output level at both ends of ab is zero; (II) The mode is that when U _i <0, the switch tubes S ₁ and S ₃ are in the half-period cut-off state, and the four switch modes are: Switching mode 1: S ₆ is turned on, and the rest are turned off; the power supply U _i charges the capacitor C ₁ through the loop formed by U _i , D ₀₅ , S ₆ , D ₀₈ , C ₁ , and L _i , and the right end of the capacitor C ₁ is positive. At the same time, it stores energy for the inductor L _i , and the capacitor C ₂ supplies power to the inductor L _o and the load R through the loop formed by C ₂ , D ₀₅ , S ₆ , D ₀₈ , L _o , and R; at this time, the output level of both ends of ab is U _C , where U _C is the voltage across C ₂ ; Switching mode 2: S ₂ is turned on, and the rest are turned off; the circuit formed by the power supply U _i through U _i , S ₂ , D ₁ , and L _i stores energy for the inductor L _i , and the capacitors C ₁ and C ₂ pass through C ₁ , L The loop formed by _o , R, C ₂ , S ₂ , and D ₁ supplies power to the inductor L _o and the load R; at this time, the output level at both ends of ab is 2U _C , where 2U _C is the voltage at both ends of C ₁ and C ₂ ; Switching mode 3: S ₅ is turned on, and the rest are turned off; power supply U _i and inductor L _i charge capacitor _C 2 through a loop formed by U _i , C ₂ , D ₀₂ , S ₅ , D ₀₃ , and L _i , and capacitor C ₂ The left end is positive, and the capacitor C ₁ supplies power to the inductance L _o and the load R through the loop formed by C ₁ , L _o , R, D ₀₂ , S ₅ , and D ₀₃ ; at this time, the output level at both ends of ab is U _C , where _UC is the voltage across _C1 ; Switching mode 4: S ₄ is turned on, and the rest are turned off; power supply U _i and inductor L _i charge capacitors C 1 _and C 2 _through a loop formed by U _i , C ₂ , S ₄ , D ₃ , C ₁ , and L _i , The loop formed by the inductance L _o through L _o , R, S ₄ , and D ₃ continues to flow for the load R; at this time, the output level at both ends of ab is zero; The single-phase X-type interleaved three-level AC voltage regulation circuit realizes the reverse voltage regulation transformation of the input and output voltages, and adjusts the conduction time of the three levels of 0, U _C and 2 U _C at the ab output terminal , can freely realize the buck-boost function of the input and output voltages.