Multi-input bipolar output voltage self-balancing Buck-Boost DC-DC converter

Abstract

The invention discloses a multi-input bipolar output voltage self-balancing Buck-Boost DC-DC (Direct Current-Direct Current) converter. The converter comprises a basic Buck-Boost converter, i reverse conversion units and j forward expansion units, the reverse conversion unit is composed of a direct current source, a switching tube, two inductors, two capacitors and a diode. The forward expansion unit is composed of an inductor, two capacitors and a diode. Voltage self-balancing is achieved through an auxiliary capacitor Cj3 in the forward expansion unit, the auxiliary capacitor Cj3 is connected with different output side capacitors in parallel in different modes, positive output capacitor voltage and negative output capacitor voltage are clamped to be approximately equal, and the problem that large deviation exists in output voltage when loads of the bipolar output circuit are unbalanced is well solved. The input and output gains of the converter and the voltage stress of the switching device can be adjusted by adjusting the number of the forward expansion units and the number of the reverse conversion units.

Description

Technical Field

[0001] The invention relates to a Buck-Boost DC-DC converter, in particular to a multi-input bipolar output voltage self-balancing Buck-Boost DC-DC converter. Background Art

[0002] The three-wire bipolar power supply system has three buses with different voltage levels, N, Z, and P, with more voltage levels, higher flexibility and reliability. Therefore, it has shown good advantages in the fields of new energy, commercial data centers, residential electricity, consumer electronics, etc. The traditional bipolar power supply system has unbalanced bus voltages at both poles due to the unbalanced power generated by the two poles. In theory, this problem can be solved by adding additional voltage balancers or using additional three-level converters with neutral point clamping, but these methods will cause more power loss. On this basis, it becomes necessary to study the inter-pole voltage self-balancing circuit. While providing the bus voltage, the voltage between the two poles is self-balanced, reducing the impact on the DC microgrid and improving the stability and robustness of the system. Traditional bipolar converters mostly use forward and flyback converters. For example, the patent application publication number CN116155106A mentions "an isolated bipolar output self-equalizing DC-DC converter", but this method uses multiple output windings to build multiple outputs, which will cause cross-regulation problems, and requires an auxiliary clamp circuit to absorb leakage inductance energy and eliminate voltage spikes. In some bipolar power supply situations, non-isolated converter solutions are often used to eliminate the impact of cross-regulation and improve converter efficiency. Summary of the invention

[0003] In order to solve the problem of inter-pole voltage balancing of existing non-isolated bipolar multi-output DC-DC converters, the present invention provides a multi-input bipolar output voltage self-balancing Buck-Boost DC-DC converter, which consists of a basic Buck-Boost converter, a plurality of reverse conversion units and a plurality of forward expansion units, has highly symmetrical positive and negative output voltages with a common ground, and does not need to add a complex control loop to achieve voltage balancing capability.

[0004] The technical solution adopted by the present invention is:

[0005] A multi-input bipolar output voltage self-balancing Buck-Boost DC-DC converter includes a basic Buck-Boost converter, i reverse conversion units, and j forward expansion units, wherein:

[0006] The basic Buck-Boost converter consists of an inductor L 11 , a capacitor C 11, an active switch tube S1, a diode D 11 , a DC input source u in1 The connection form is as follows: the source of the active switch tube S1 is connected to the inductor L 11 One end of the diode D 11 The cathode, drain of active switch tube S1 is connected to the DC input source u in1 One end of the diode D 11 The anode connection capacitance C 11 One end of the capacitor C 11 The other end of the inductor L 11 The other end, DC input source u in1 The other end is grounded;

[0007] The first reverse conversion unit includes two inductors L 21 , L 22 , two capacitors C 21 , C 24 , an active switch tube S2, a diode D 21 , a DC input source u in2 The connection form is as follows: the source of the active switch tube S2 is connected to the inductor L 21 One end of the capacitor C 24 The drain of the active switch tube S2 is connected to the DC input source u in2 One end of the DC input source u in2 The other end of the inductor L 21 The other end of the capacitor C 24 The other end of the inductor L 22 One end of the diode D 21 The cathode of diode D 21 The anode connection capacitance C 21 One end of the capacitor C 21 The other end of the inductor L 22 The other end of

[0008] The second reverse conversion unit includes two inductors L 31 , L 32 , two capacitors C 31 , C 34 , an active switch tube S3, a diode D 31 , a DC input source u in3 The connection form is as follows: the source of the active switch tube S3 is connected to the inductor L 31 One end of the capacitor C 34 The drain of the active switch tube S3 is connected to the DC input source u in3 One end of the DC input source u in3The other end of the inductor L 31 The other end of the capacitor C 34 The other end of the inductor L 32 One end of the diode D 31 The cathode of diode D 31 The anode connection capacitance C 31 One end of the capacitor C 31 The other end of the inductor L 32 The other end of

[0009] ... and so on, i ≥ 3;

[0010] The i-th reverse conversion unit includes two inductors L (i+1)1 , L (i+1)2 , two capacitors C (i+1)1 , C (i+1)4 , an active switch tube S (i+1) , a diode D (i+1)1 , a DC input source u in(i+1) ; Its connection form is as follows: Active switch tube S (i+1) The source of (i+1)1 One end of the capacitor C (i+1)4 One end of the active switch tube S (i+1) The drains are connected to the DC input source u in(i+1) One end of the DC input source u in(i+1) The other end of the inductor L (i+1)1 The other end of the capacitor C (i+1)4 The other end of the inductor L (i+1)2 One end of the diode D (i+1)1 The cathode of diode D (i+1)1 The anode connection capacitance C (i+1)1 One end of the capacitor C (i+1)1 The other end of the inductor L (i+1)2 The other end of

[0011] The basic Buck-Boost converter has a DC input source u in1 The other end is connected to the DC input source u of the first reverse conversion unit. in2 The other end of the second reverse conversion unit is the DC input source u in3 The other end of the ith reverse conversion unit is u in(i+1) The other end of

[0012] The basic Buck-Boost converter capacitor C 11 One end of the capacitor C is connected to the first reverse conversion unit 21The other end of the first reverse conversion unit capacitor C 21 One end of the capacitor C is connected to the second reverse conversion unit 31 The other end of the second reverse conversion unit capacitor C 31 One end of the capacitor C is connected to the third reverse conversion unit 41 The other end of the capacitor C of the i-1th reverse conversion unit i1 One end of the capacitor C of the i-th reverse conversion unit is connected (i+1)1 The other end of

[0013] Capacitor C (i+1)1 One end is connected to the negative load R N One end, negative load R N The other end is connected to the DC input source u of the basic Buck-Boost converter in1 the other end.

[0014] The first forward expansion unit includes an inductor L 12 , a diode D 12 , two capacitors C 12 , C 13 ; Among them, the inductance L 12 One end of each capacitor is connected to 13 The other end of the diode D 12 The cathode of the inductor L 12 The other end of the capacitor C 12 The other end of the capacitor C 12 One end of the diode D 12 Anode;

[0015] The second forward expansion unit includes an inductor L 23 , a diode D 22 , two capacitors C 22 , C 23 ; Among them, the inductance L 23 One end of each capacitor is connected to 23 The other end of the diode D 22 The cathode of the inductor L 23 The other end of the capacitor C 22 The other end of the capacitor C 22 One end of the diode D 22 Anode;

[0016] ...and so on, j≥2;

[0017] The jth forward expansion unit includes an inductor L j3 , a diode D j2 , two capacitors Cj2 , C j3 ; Among them, the inductor L j3 One end of each capacitor is connected to j3 The other end of the diode D j2 The cathode of the inductor L j3 The other end of the capacitor C j2 The other end of the capacitor C j2 One end of the diode D j2 Anode;

[0018] The capacitor C in the first forward expansion unit 13 One end of the basic Buck-Boost converter is connected to the diode D 11 Cathode; Capacitor C in the second forward expansion unit 23 One end of the diode D is connected to the first reverse conversion unit 21 The cathode of the third forward expansion unit is capacitor C 33 One end of the diode D is connected to the second reverse conversion unit 31 The cathode of the jth forward expansion unit is j3 One end of the diode D in the i-th reverse conversion unit is connected (i+1)1 cathode; wherein: j = i + 1;

[0019] The basic Buck-Boost converter capacitor C 11 The other end is connected to the capacitor C in the first forward expansion unit. 12 One end of the first forward expansion unit capacitor C 12 The other end is connected to the capacitor C in the second forward expansion unit 22 One end of the capacitor C in the second forward expansion unit 22 The other end is connected to the capacitor C in the third forward expansion unit. 32 One end of the capacitor C in the j-1th forward expansion unit (j-1)2 The other end is connected to the capacitor C in the jth forward expansion unit j2 one end of

[0020] Capacitor C j2 The other end is connected to the positive load R P The other end of the positive load R P One end is connected to the DC input source u in1 the other end.

[0021] In this converter,

[0022] When using 1 basic Buck-Boost converter, i reverse conversion units, j forward expansion units, and a total of i+1 input power supplies, the maximum output voltages of the positive and negative polarities are:

[0023]

[0024] In the formula, u N Indicates the negative output voltage of the converter, u P Indicates the positive output voltage of the converter, D1 indicates the duty cycle of the switch S1 in the basic Buck-Boost converter, D (i+1) represents the switch tube S in the i-th reverse conversion unit (i+1) The duty cycle, u in1 Indicates the input voltage in the basic Buck-Boost converter, u in(i+1) Represents the input voltage in the i-th reverse conversion unit.

[0025] The voltage stress of switch S1 in the basic Buck-Boost converter is: Capacitor C 11 The voltage stress on is:

[0026] The switch tube S in the i-th reverse conversion unit (i+1) The voltage stress is: Capacitor C (i+1)1 The voltage stress on is: Capacitor C (i+1)4 The voltage stress on is: Where k is the independent variable, k∈[1,i];

[0027] In the above formula, j=i+1 is true, D1 represents the duty cycle of the switch S1 in the basic Buck-Boost converter, D (i+1) represents the switch tube S in the i-th reverse conversion unit (i+1) The duty cycle, u in1 Indicates the input voltage in the basic Buck-Boost converter, u in(i+1) Represents the input voltage in the i-th reverse conversion unit.

[0028] The capacitor C in the jth forward expansion unit j2 The upper voltage stress is: In this formula, j=i+1 holds; the capacitance C j3 The upper voltage stress is: Among them, k is an independent variable, k∈[1,j].

[0029] For example, C 13 ,C 23,…,C j3 The voltage stresses on are:

[0030] In this converter, the circuit contains a basic Buck-Boost converter, a reverse conversion unit, two forward expansion units, and the inductor L 11 , L 12 , L 21 , L 22 , L 23 The current is continuously conducted. According to the different states of the active switch tube, the circuit can be divided into 6 working states;

[0031] (1) Mode 1: Active switches S1 and S2 are turned on, diode D 11 , D 12 , D 21 , D 22 are all turned off, at this time the inductor L 11 , L 12 , L 21 , L 22 , L 23 and capacitor C 12 , C 24 Charging, capacitor C 11 , C 13 , C 21 , C 22 , C 23 Discharge; Inductance L 11 , L 12 , L 21 , L 22 , L 23 The terminal voltage is shown as follows:

[0032]

[0033] In the formula, u N Indicates the negative output voltage of the converter, u P Indicates the positive polarity output voltage of the converter, u in1 Indicates the input voltage in the basic Buck-Boost converter, u in2 Indicates the input voltage in the first reverse conversion unit.

[0034] (2) Mode 2: Active switch S1 is turned off, active switch S2 is turned on, and diode D 11 , D 21 , D 22 Both are turned off, diode D 12 is turned on, at this time the inductor L 21 , L 22 , L 23and capacitor C 12 , C 13 , C 22 , C 24 Charging, inductance L 11 , L 12 and capacitor C 11 , C 21 , C 23 Discharge; Inductance L 11 , L 12 , L 21 , L 22 , L 23 The terminal voltage is shown as follows:

[0035]

[0036] (3) Mode 3: Active switch S1 is turned off, active switch S2 is turned on, and diode D 21 , D 22 Both are turned off, diode D 11 , D 12 is turned on, at this time the inductor L 21 , L 22 , L 23 and capacitor C 11 , C 12 , C 22 , C 24 Charging, inductance L 11 , L 12 and capacitor C 13 , C 21 , C 23 Discharge; Inductance L 11 , L 12 , L 21 , L 22 , L 23 The terminal voltage is shown as follows:

[0037]

[0038] (4) Mode 4: Active switches S1 and S2 are turned off, diode D 22 Turn off, diode D 11 , D 12 , D 21 The capacitor C 11 , C 12 , C 13 , C 21 , C 22 Charging, inductance L 11 , L 12 , L 21 , L 22 , L 23 and capacitor C 23, C 24 Discharge; Inductance L 11 , L 12 , L 21 , L 22 , L 23 The terminal voltage is shown as follows:

[0039]

[0040] (5) Mode 5: Active switches S1 and S2 are turned off, diode D 11 , D 12 , D 21 , D 22 The capacitor C 11 , C 13 , C 21 , C 22 , C 23 Charging, inductance L 11 , L 12 , L 21 , L 22 , L 23 and capacitor C 12 , C 24 Discharge; Inductance L 11 , L 12 , L 21 , L 22 , L 23 The terminal voltage is shown as follows:

[0041]

[0042] (6) Mode 6: Active switch tube S2 is turned off, active switch tube S1 is turned on, and diode D 11 , D 12 Turn off, diode D 21 , D 22 The capacitor C 11 , C 13 , C 21 , C 24 Charging, inductance L 11 , L 12 , L 21 , L 22 , L 23 and capacitor C 12 , C 22 , C 23 Discharge; Inductance L 11 , L 12 , L 21 , L 22 , L 23 The terminal voltage is shown as follows:

[0043]

[0044] Using the above inductor voltage expression, the voltage stress on each capacitor can be obtained as follows:

[0045]

[0046] The present invention provides a multi-input bipolar output voltage self-balancing Buck-Boost DC-DC converter, and the technical effects are as follows:

[0047] 1) The voltage self-balancing of the converter is achieved through the auxiliary capacitor C in the forward expansion unit j3 Since the capacitor voltage cannot change suddenly, the positive output voltage u C11 +u C21 +……+u C(i+1)1 And the negative output voltage u C12 +u C22 +……+u Cj2 Both are clamped to u C13 +u C23 +……+u Cj3 .

[0048] 2) The converter can be continuously expanded until it contains i reverse conversion units and j forward expansion units.

[0049] 3) When part of the switch tube is damaged, the rest of the circuit can work normally. In addition, when part of the power supply is damaged, the rest of the circuit can work normally, which reflects its high reliability. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] The present invention will be further described below in conjunction with the accompanying drawings and examples:

[0051] Figure 1 This is a circuit topology diagram when the number of basic Buck-Boost converters of the present invention is 1, the number of reverse conversion units is 1, and the number of forward expansion units is 2.

[0052] Figure 2 This is the circuit topology structure when the number of reverse conversion units of the present invention is expanded to i and the number of forward expansion units is expanded to j. Figure 3 This is a simulation diagram of the output voltage waveform of the circuit under equal load when the number of basic Buck-Boost converters of the present invention is 1, the number of reverse conversion units is 1, and the number of forward expansion units is 2. At this time, the input voltage is 48V, and D=0.675. Figure 4 This is a simulation diagram of the output voltage waveform of the circuit under unequal loads when the number of basic Buck-Boost converters of the present invention is 1, the number of reverse conversion units is 1, and the number of forward expansion units is 2. At this time, the input voltage is 48V, and D=0.675. Figure 5 It is the connection diagram between the bipolar DC bus and the bipolar converter, and is also the basic circuit for the self-balancing analysis of the bipolar inter-pole voltage.

[0053] Figure 6 It is a comparison diagram of the difference between the output voltage of the two poles of the converter and the voltage difference between the two poles of the bus when the present invention is connected to a bipolar DC microgrid with a bus voltage deviation.

[0054] Figure 7 A comparison diagram showing the difference in output power between the two poles of the converter when the present invention is connected to a bipolar DC microgrid with a bus voltage deviation. DETAILED DESCRIPTION

[0055] like Figure 2 As shown, a multi-input bipolar output voltage self-balancing Buck-Boost DC-DC converter includes a basic Buck-Boost converter, i reverse conversion units, and j forward expansion units, wherein:

[0056] The basic Buck-Boost converter consists of an inductor L 11 , a capacitor C 11 , an active switch tube S1, a diode D 11 , a DC input source u in1 The connection form is as follows: the source of the active switch tube S1 is connected to the inductor L 11 One end of the diode D 11 The cathode, drain of active switch tube S1 is connected to the DC input source u in1 One end of the diode D 11 The anode connection capacitance C 11 One end of the capacitor C 11 The other end of the inductor L 11 The other end, DC input source u in1 The other end is grounded;

[0057] The first reverse conversion unit includes two inductors L 21 , L 22 , two capacitors C 21 , C 24 , an active switch tube S2, a diode D 21 , a DC input source u in2 The connection form is as follows: the source of the active switch tube S2 is connected to the inductor L 21 One end of the capacitor C 24 The drain of the active switch tube S2 is connected to the DC input source u in2 One end of the DC input source u in2 The other end of the inductor L21 The other end of the capacitor C 24 The other end of the inductor L 22 One end of the diode D 21 The cathode of diode D 21 The anode connection capacitance C 21 One end of the capacitor C 21 The other end of the inductor L 22 The other end of

[0058] The second reverse conversion unit includes two inductors L 31 , L 32 , two capacitors C 31 , C 34 , an active switch tube S3, a diode D 31 , a DC input source u in3 The connection form is as follows: the source of the active switch tube S3 is connected to the inductor L 31 One end of the capacitor C 34 The drain of the active switch tube S3 is connected to the DC input source u in3 One end of the DC input source u in3 The other end of the inductor L 31 The other end of the capacitor C 34 The other end of the inductor L 32 One end of the diode D 31 The cathode of diode D 31 The anode connection capacitance C 31 One end of the capacitor C 31 The other end of the inductor L 32 The other end of

[0059] ... and so on, i ≥ 3;

[0060] The i-th reverse conversion unit includes two inductors L (i+1)1 , L (i+1)2 , two capacitors C (i+1)1 , C (i+1)4 , an active switch tube S (i+1) , a diode D (i+1)1 , a DC input source u in(i+1) ; Its connection form is as follows: Active switch tube S (i+1) The source of (i+1)1 One end of the capacitor C (i+1)4 One end of the active switch tube S (i+1) The drain terminal is connected to the DC input source u in(i+1) One end of the DC input source u in(i+1) The other end of the inductor L (i+1)1The other end of the capacitor C (i+1)4 The other end of the inductor L (i+1)2 One end of the diode D (i+1)1 The cathode of diode D (i+1)1 The anode connection capacitance C (i+1)1 One end of the capacitor C (i+1)1 The other end of the inductor L (i+1)2 The other end of

[0061] The basic Buck-Boost converter has a DC input source u in1 The other end is connected to the DC input source u of the first reverse conversion unit. in2 The other end of the second reverse conversion unit is the DC input source u in3 The other end of the ith reverse conversion unit is u in(i+1) The other end of

[0062] The basic Buck-Boost converter capacitor C 11 One end of the capacitor C is connected to the first reverse conversion unit 21 The other end of the first reverse conversion unit capacitor C 21 One end of the capacitor C is connected to the second reverse conversion unit 31 The other end of the second reverse conversion unit capacitor C 31 One end of the capacitor C is connected to the third reverse conversion unit 41 The other end of the capacitor C of the i-1th reverse conversion unit i1 One end of the capacitor C of the i-th reverse conversion unit is connected (i+1)1 The other end of

[0063] Capacitor C (i+1)1 One end is connected to the negative load R N One end, negative load R N The other end is connected to the DC input source u of the basic Buck-Boost converter in1 the other end.

[0064] The basic Buck-Boost converter and the first reverse conversion unit are connected in parallel input and series output. The connection is as follows: From the input port, the two DC input sources u in1 ,u in2 Common ground. From the output port, the capacitor C in the basic Buck-Boost converter 11 and diode D 11 The first reverse conversion unit is superimposed on the anode connection of the diode D 21 , capacitor C21 With inductance L 22 The output loop of the first reverse conversion unit is superimposed on the output loop of D 11 , C 11 The output port of the basic Buck-Boost converter is constructed.

[0065] The output load of the converter of the present invention is connected to a common point and a capacitor C 21 At this time, the negative output voltage of the converter is the sum of the output voltages of the basic Buck-Boost converter and the first reverse conversion unit.

[0066] ... and so on, the i-th reverse conversion unit can still be superimposed on the i-1-th reverse conversion unit. Therefore, the negative polarity output voltage of the converter is i times that of the basic Buck-Boost converter.

[0067] The first forward expansion unit includes an inductor L 12 , a diode D 12 , two capacitors C 12 , C 13 ; Among them, the inductor L 12 One end of each capacitor is connected to 13 The other end of the diode D 12 The cathode of the inductor L 12 The other end of the capacitor C 12 The other end of the capacitor C 12 One end of the diode D 12 Anode;

[0068] The second forward expansion unit includes an inductor L 23 , a diode D 22 , two capacitors C 22 , C 23 ; Among them, the inductor L 23 One end of each capacitor is connected to 23 The other end of the diode D 22 The cathode of the inductor L 23 The other end of the capacitor C 22 The other end of the capacitor C 22 One end of the diode D 22 Anode;

[0069] ...and so on, j≥2;

[0070] The jth forward expansion unit includes an inductor L j3 , a diode D j2 , two capacitors C j2 , Cj3 ; Among them, the inductor L j3 One end of each capacitor is connected to j3 The other end of the diode D j2 The cathode of the inductor L j3 The other end of the capacitor C j2 The other end of the capacitor C j2 One end of the diode D j2 Anode;

[0071] The capacitor C in the first forward expansion unit 13 One end of the basic Buck-Boost converter is connected to the diode D 11 Cathode; Capacitor C in the second forward expansion unit 23 One end of the diode D is connected to the first reverse conversion unit 21 The cathode of the third forward expansion unit is capacitor C 33 One end of the diode D is connected to the second reverse conversion unit 31 The cathode of the jth forward expansion unit is j3 One end of the diode D in the i-th reverse conversion unit is connected (i+1)1 cathode; wherein: j = i + 1;

[0072] The basic Buck-Boost converter capacitor C 11 The other end is connected to the capacitor C in the first forward expansion unit. 12 One end of the first forward expansion unit capacitor C 12 The other end is connected to the capacitor C in the second forward expansion unit 22 One end of the capacitor C in the second forward expansion unit 22 The other end is connected to the capacitor C in the third forward expansion unit. 32 One end of the capacitor C in the j-1th forward expansion unit (i - 1)2 The other end is connected to the capacitor C in the jth forward expansion unit j2 one end of

[0073] Capacitor C j2 The other end is connected to the positive load R P The other end of the positive load R P One end is connected to the DC input source u in1 the other end.

[0074] In this converter, when one basic Buck-Boost converter, i reverse conversion units, j forward expansion units, and a total of i+1 input power sources are used, the maximum output voltages of the positive and negative polarities are respectively:

[0075]

[0076] In the formula, u N Indicates the negative output voltage of the converter, u P Indicates the positive output voltage of the converter, D1 indicates the duty cycle of the switch S1 in the basic Buck-Boost converter, D (i+1) represents the switch tube S in the i-th reverse conversion unit (i+1) The duty cycle, u in1 Indicates the input voltage in the basic Buck-Boost converter, u in(i+1) Represents the input voltage in the i-th reverse conversion unit.

[0077] The voltage stress of switch S1 in the basic Buck-Boost converter is: Capacitor C 11 The voltage stress on is:

[0078] The switch tube S in the i-th reverse conversion unit (i+1) The voltage stress is: Capacitor C (i+1)1 The voltage stress on is: Capacitor C (i+1)4 The voltage stress on is: Where k is the independent variable, k∈[1,i];

[0079] In the above formula, j=i+1 is true, D1 represents the duty cycle of the switch S1 in the basic Buck-Boost converter, D (i+1) represents the switch tube S in the i-th reverse conversion unit (i+1) The duty cycle, u in1 Indicates the input voltage in the basic Buck-Boost converter, u in(i+1) Represents the input voltage in the i-th reverse conversion unit.

[0080] The capacitor C in the jth forward expansion unit j2 The upper voltage stress is: In this formula, j=i+1 holds; the capacitance C j3 The upper voltage stress is: Where k is the independent variable, k∈[1,j].

[0081] For example, C 13 ,C23 ,…,C j3 The voltage stress on

[0082] In this converter, the circuit contains a basic Buck-Boost converter, a reverse conversion unit, two forward expansion units, and the inductor L 11 , L 12 , L 21 , L 22 , L 23 The current is continuously conducted. According to the different states of the active switch tube, the circuit can be divided into 6 working states;

[0083] (1) Mode 1: Active switches S1 and S2 are turned on, diode D 11 , D 12 , D 21 , D 22 are all turned off, at this time the inductor L 11 , L 12 , L 21 , L 22 , L 23 and capacitor C 12 , C 24 Charging, capacitor C 11 , C 13 , C 21 , C 22 , C 23 Discharge; Inductance L 11 , L 12 , L 21 , L 22 , L 23 The terminal voltage is shown as follows:

[0084]

[0085] (2) Mode 2: Active switch S1 is turned off, active switch S2 is turned on, and diode D 11 , D 21 , D 22 Both are turned off, diode D 12 is turned on, at this time the inductor L 21 , L 22 , L 23 and capacitor C 12 , C 13 , C 22 , C 24 Charging, inductance L 11 , L 12 and capacitor C 11 , C 21 , C 23 Discharge; Inductance L11 , L 12 , L 21 , L 22 , L 23 The terminal voltage is shown as follows:

[0086]

[0087] (3) Mode 3: Active switch S1 is turned off, active switch S2 is turned on, and diode D 21 , D 22 Both are turned off, diode D 11 , D 12 is turned on, at this time the inductor L 21 , L 22 , L 23 and capacitor C 11 , C 12 , C 22 , C 24 Charging, inductance L 11 , L 12 and capacitor C 13 , C 21 , C 23 Discharge; Inductance L 11 , L 12 , L 21 , L 22 , L 23 The terminal voltage is shown as follows:

[0088]

[0089] (4) Mode 4: Active switches S1 and S2 are turned off, diode D 22 Turn off, diode D 11 , D 12 , D 21 The capacitor C 11 , C 12 , C 13 , C 21 , C 22 Charging, inductance L 11 , L 12 , L 21 , L 22 , L 23 and capacitor C 23 , C 24 Discharge; Inductance L 11 , L 12 , L 21 , L 22 , L 23 The terminal voltage is shown as follows:

[0090]

[0091] (5) Mode 5: Active switches S1 and S2 are turned off, diode D 11 , D 12 , D 21 , D 22 The capacitor C 11 , C 13 , C 21 , C 22 , C 23 Charging, inductance L 11 , L 12 , L 21 , L 22 , L 23 and capacitor C 12 , C 24 Discharge; Inductance L 11 , L 12 , L 21 , L 22 , L 23 The terminal voltage is shown as follows:

[0092]

[0093] (6) Mode 6: Active switch tube S2 is turned off, active switch tube S1 is turned on, and diode D 11 , D 12 Turn off, diode D 21 , D 22 The capacitor C 11 , C 13 , C 21 , C 24 Charging, inductance L 11 , L 12 , L 21 , L 22 , L 23 and capacitor C 12 , C 22 , C 23 Discharge; Inductance L 11 , L 12 , L 21 , L 22 , L 23 The terminal voltage is shown as follows:

[0094]

[0095] Using the above inductor voltage expression, the voltage stress on each capacitor can be obtained as follows:

[0096]

[0097] By analyzing the mutual influence relationship between the converter voltage and the bus voltage, the following conclusion can be drawn: when the converter is connected to the bus of the DC microgrid, the converter has a certain ability to automatically balance the voltage.

[0098] refer to Figure 5 The specific analysis is as follows: (1) When the bus voltage u NZ ,u ZP As a known external factor, the converter voltage u' o1 ,u' o2 When the unbalanced power is taken as the dependent variable, the converter output port voltage u' can be listed according to the loop power conservation law: o1 ,u' o2 , and the uncertain bus current i' P ,i' N ,i' Z The formula is:

[0099]

[0100] Where r N , r P , r Z Represent the line resistance on N, P, and Z respectively.

[0101] (2) When the bus voltage u' NZ ,u' ZP As a dependent variable, its size is affected by the converter output port voltage and power, and the converter u' is listed o1 ,u' o2 The expression of output voltage is:

[0102]

[0103] In the formula, u in represents the input voltage of the proposed converter, i in represents the input current of the proposed converter; D1 represents the duty cycle of the switch tube S1 in the proposed converter; u C11 ,u C14 Represents the output side capacitance C 11 , C 14 The voltage size; i in ,i N ,i P represents the output current of the proposed converter, the negative output current of the converter, and the positive output current of the converter; P in , P N , P P Represents the converter input power, converter negative output power, and converter positive output power.

[0104] Combining the above formulas, we can get the exact function expression of the converter output voltage:

[0105]

[0106] The above expression clearly shows the functional relationship between known quantities such as converter output side voltage, converter input side power, duty cycle, bus voltage deviation, etc.

[0107] The following results can be obtained in the specific implementation: (1) When there is a power deviation between the positive and negative poles of the bus, resulting in a low voltage at one pole, the output voltage of the converter at this pole will increase to support the lower voltage of the bus at this pole.

[0108] (2) When there is a 5% deviation between the two bus voltages, the converter input power will be completely output to the lower side of the bus voltage, and the ability to support the two bus voltages will reach its limit.

[0109] A multi-input bipolar output voltage self-balancing Buck-Boost DC-DC converter. After expansion, the converter includes i+1 DC input sources, 1 basic Buck-Boost converter, i reverse conversion units, and j forward expansion units. The reverse conversion unit is composed of a DC source, a switch tube, two inductors, two capacitors and a diode. The forward expansion unit is composed of an inductor, two capacitors and a diode. Voltage self-balancing is achieved through the auxiliary capacitor C in the forward expansion unit. j3 It is realized by connecting different output side capacitors in parallel in different modes, clamping the positive and negative output capacitor voltages to approximately equal, which better solves the problem of large deviation of bipolar output voltage when the load is unbalanced. By adjusting the number of forward expansion units and reverse conversion units, the input and output gain of the converter and the voltage stress of the switching device can be adjusted. By analyzing the mutual influence relationship between the converter voltage and the bus voltage, it can be obtained that the output power of the two poles of the converter will correspondingly supplement the deviation of the power consumption of the two poles of the bus. Until the bus voltage deviation reaches 5%, the converter input power will be fully output to the lower side of the bus voltage, and the ability to support the voltage of the two poles of the bus reaches its limit.

[0110] Example:

[0111] like Figure 1 The figure shows a circuit topology diagram of a multi-input bipolar output voltage self-balancing Buck-Boost DC-DC converter of the present invention, when the number of basic Buck-Boost converters is 1, the number of reverse conversion units is 1, and the number of forward expansion units is 2. The specific circuit connection is as follows:

[0112] The converter includes a basic Buck-Boost converter, a reverse conversion unit, and two forward expansion units, among which:

[0113] The basic Buck-Boost converter consists of an inductor L 11 , a capacitor C 11 , an active switch tube S1, a diode D 11 , a DC input source u in1 The connection form is as follows: the source of the active switch tube S1 is connected to the inductor L 11 One end of the diode D 11 The cathode, drain of active switch tube S1 is connected to the DC input source u in1 One end of the diode D 11 The anode connection capacitance C 11 One end of the capacitor C 11 The other end of the inductor L 11 The other end, DC input source u in1 The other end is grounded;

[0114] The first reverse conversion unit includes two inductors L 21 , L 22 , two capacitors C 21 , C 24 , an active switch tube S2, a diode D 21 , a DC input source u in2 The connection form is as follows: the source of the active switch tube S2 is connected to the inductor L 21 One end of the capacitor C 24 The drain of the active switch tube S2 is connected to the DC input source u in2 One end of the DC input source u in2 The other end of the inductor L 21 The other end of the capacitor C 24 The other end of the inductor L 22 One end of the diode D 21 The cathode of diode D 21 The anode connection capacitance C 21 One end of the capacitor C 21 The other end of the inductor L 22 The other end of

[0115] The basic Buck-Boost converter has a DC input source u in1 The other end is connected to the DC input source u of the first reverse conversion unit. in2 The other end of

[0116] The basic Buck-Boost converter capacitor C 11 One end of the capacitor C is connected to the first reverse conversion unit 21The other end of the capacitor C 21 One end is connected to the negative load R N One end, negative load R N The other end is connected to the DC input source u of the basic Buck-Boost converter in1 the other end.

[0117] The first forward expansion unit includes an inductor L 12 , a diode D 12 , two capacitors C 12 , C 13 ; Among them, the inductor L 12 One end of each capacitor is connected to 13 The other end of the diode D 12 The cathode of the inductor L 12 The other end of the capacitor C 12 The other end of the capacitor C 12 One end of the diode D 12 Anode;

[0118] The second forward expansion unit includes an inductor L 23 , a diode D 22 , two capacitors C 22 , C 23 ; Among them, the inductor L 23 One end of each capacitor is connected to 23 The other end of the diode D 22 The cathode of the inductor L 23 The other end of the capacitor C 22 The other end of the capacitor C 22 One end of the diode D 22 Anode;

[0119] The capacitor C in the first forward expansion unit 13 One end of the basic Buck-Boost converter is connected to the diode D 11 Cathode; Capacitor C in the second forward expansion unit 23 One end of the diode D is connected to the first reverse conversion unit 21 The cathode;

[0120] The basic Buck-Boost converter capacitor C 11 The other end is connected to the capacitor C in the first forward expansion unit. 12 One end of the first forward expansion unit capacitor C 12 The other end is connected to the capacitor C in the second forward expansion unit 22 one end of

[0121] Capacitor C22 The other end is connected to the positive load R P The other end of the positive load R P One end is connected to the DC input source u in1 the other end.

[0122] The connection between the first forward expansion unit and the second forward expansion unit is as follows:

[0123] From the output port, the diode D 22 , capacitor C 22 、Inductance L 23 The output loop of the second forward expansion unit is superimposed on the diode D 12 , capacitor C 12 、Inductance L 12 On the output circuit of the first forward expansion unit.

[0124] The connection relationship between the first forward expansion unit and the basic Buck-Boost converter is as follows:

[0125] From the input side, the capacitor C in the first forward expansion unit 13 The upper end of the diode D is connected to the basic Buck-Boost converter 11 The cathode and inductance L 11 From the output side, the capacitor C in the first forward expansion unit 12 With diode D 12 The intersection of the anodes is connected to the common point of the basic Buck-Boost converter.

[0126] The connection relationship between the second forward expansion unit and the first reverse transformation unit is as follows:

[0127] From the input side, the capacitor C in the second forward expansion unit 23 The upper end is connected to the capacitor C in the first reverse conversion unit. 24 、Diode D 21 The cathode and inductance L 22 From the output side, the diode D 22 , capacitor C 22 、Inductance L 23 The output loop of the second forward expansion unit is superimposed on the diode D 12 , capacitor C 12 、Inductance L 12 On the output circuit of the first forward expansion unit.

[0128] Negative load R N One end of the capacitor C in the first reverse conversion unit 21and diode D 21 The anode is connected to the negative load R N The other end of the capacitor C in the basic Buck-Boost converter 11 , inductance L 11 , DC input source u in1 connected to the public places.

[0129] Positive load R P One end of the capacitor C in the second forward expansion unit 22 and inductor L 23 The intersection of the positive load R P The other end is connected to the negative load R N connected to the public places.

[0130] Figure 3 This is a simulation diagram of the output voltage waveform of the circuit under equal load when the number of basic Buck-Boost converters of the present invention is 1, the number of reverse conversion units is 1, and the number of forward expansion units is 2. At this time, the input voltage is 48V, and D=0.675.

[0131] Figure 4 This is a simulation diagram of the output voltage waveform of the circuit under unequal loads when the number of basic Buck-Boost converters of the present invention is 1, the number of reverse conversion units is 1, and the number of forward expansion units is 2. At this time, the input voltage is 48V, and D=0.675. Figure 5 It is the connection diagram between the bipolar DC bus and the bipolar converter, and is also the basic circuit for the self-balancing analysis of the bipolar inter-pole voltage.

[0132] Figure 6 This is a comparison diagram of the difference between the output voltage of the two poles of the converter and the voltage of the two poles of the bus when the present invention is connected to a bipolar DC microgrid with a bus voltage deviation. It can be seen that even if the converter is connected to a grid with an unbalanced bus voltage, the balance of the converter is still good.

[0133] Figure 7 The present invention is connected to a bipolar DC microgrid with a bus voltage deviation, and the difference in output power between the two poles of the converter is shown. At this time, the converter input power is 300W, and the difference in converter output power between the two poles has reached 300W, which means that all the input power is output from one pole. The difference in output power between the two poles of the converter is to compensate for the deviation of the connected bus, effectively alleviating the imbalance of the two poles of the bus.

Claims

1. A multi-input bipolar output voltage self-balancing Buck-Boost DC-DC converter, characterized in that: The converter includes a basic Buck-Boost converter, i reverse conversion units, and j forward expansion units, where: The basic Buck-Boost converter consists of an inductor L 11 , a capacitor C 11 , an active switch tube S1, a diode D 11 , a DC input source u in1 The connection form is as follows: the source of the active switch tube S1 is connected to the inductor L 11 One end of the diode D 11 The cathode, drain of active switch tube S1 is connected to the DC input source u in1 One end of the diode D 11 The anode connection capacitance C 11 One end of the capacitor C 11 The other end of the inductor L 11 The other end, DC input source u in1 The other end is grounded; The first reverse conversion unit includes two inductors L 21 , L 22 , two capacitors C 21 , C 24 , an active switch tube S2, a diode D 21 , a DC input source u in2 The connection form is as follows: the source of the active switch tube S2 is connected to the inductor L 21 One end of the capacitor C 24 The drain of the active switch tube S2 is connected to the DC input source u in2 One end of the DC input source u in2 The other end of the inductor L 21 The other end of the capacitor C 24 The other end of the inductor L 22 One end of the diode D 21 The cathode of diode D 21 The anode connection capacitance C 21 One end of the capacitor C 21 The other end of the inductor L 22 The other end of The second reverse conversion unit includes two inductors L 31 , L 32 , two capacitors C 31 , C 34 , an active switch tube S3, a diode D 31 , a DC input source u in3 The connection form is as follows: the source of the active switch tube S3 is connected to the inductor L 31 One end of the capacitor C 34 The drain of the active switch tube S3 is connected to the DC input source u in3 One end of the DC input source u in3 The other end of the inductor L 31 The other end of the capacitor C 34 The other end of the inductor L 32 One end of the diode D 31 The cathode of diode D 31 The anode connection capacitance C 31 One end of the capacitor C 31 The other end of the inductor L 32 The other end of ... and so on, i ≥ 3; The i-th reverse conversion unit includes two inductors L (i+1)1 , L (i+1)2 , two capacitors C (i+1)1 , C (i+1)4 , an active switch tube S (i+1) , a diode D (i+1)1 , a DC input source u in(i+1) ; Its connection form is as follows: Active switch tube S (i+1) The source of (i+1)1 One end of the capacitor C (i+1)4 One end of the active switch tube S (i+1) The drains are connected to the DC input source u in(i+1) One end of the DC input source u in(i+1) The other end of the inductor L (i+1)1 The other end of the capacitor C (i+1)4 The other end of the inductor L (i+1)2 One end of the diode D (i+1)1 The cathode of diode D (i+1)1 The anode connection capacitance C (i+1)1 One end of the capacitor C (i+1)1 The other end of the inductor L (i+1)2 The other end of The basic Buck-Boost converter has a DC input source u in1 The other end is connected to the DC input source u of the first reverse conversion unit. in2 The other end of the second reverse conversion unit is the DC input source u in3 The other end of the ith reverse conversion unit is u in(i+1) The other end of The basic Buck-Boost converter capacitor C 11 One end of the capacitor C is connected to the first reverse conversion unit 21 The other end of the first reverse conversion unit capacitor C 21 One end of the capacitor C is connected to the second reverse conversion unit 31 The other end of the second reverse conversion unit capacitor C 31 One end of the capacitor C is connected to the third reverse conversion unit 41 The other end of the capacitor C of the i-1th reverse conversion unit i1 One end of the capacitor C of the i-th reverse conversion unit is connected (i+1)1 The other end of Capacitor C (i+1)1 One end is connected to the negative load R N One end, negative polarity load R N The other end is connected to the DC input source u of the basic Buck-Boost converter in1 The other end of The first forward expansion unit includes an inductor L 12 , a diode D 12 , two capacitors C 12 , C 13 ; Among them, the inductance L 12 One end of each capacitor is connected to 13 The other end of the diode D 12 The cathode of the inductor L 12 The other end of the capacitor C 12 The other end of the capacitor C 12 One end of the diode D 12 Anode; The second forward expansion unit includes an inductor L 23 , a diode D 22 , two capacitors C 22 , C 23 ; Among them, the inductance L 23 One end of each capacitor is connected to 23 The other end of the diode D 22 The cathode of the inductor L 23 The other end of the capacitor C 22 The other end of the capacitor C 22 One end of the diode D 22 Anode; ...and so on, j≥2; The jth forward expansion unit includes an inductor L j3 , a diode D j2 , two capacitors C j2 , C j3 ; Among them, the inductance L j3 One end of each capacitor is connected to j3 The other end of the diode D j2 The cathode of the inductor L j3 The other end of the capacitor C j2 The other end of the capacitor C j2 One end of the diode D j2 Anode; The capacitor C in the first forward expansion unit 13 One end of the basic Buck-Boost converter is connected to the diode D 11 Cathode; Capacitor C in the second forward expansion unit 23 One end of the diode D is connected to the first reverse conversion unit 21 The cathode of the third forward expansion unit is capacitor C 33 One end of the diode D is connected to the second reverse conversion unit 31 The cathode of the jth forward expansion unit is j3 One end of the diode D in the i-th reverse conversion unit is connected (i+1)1 cathode; wherein: j = i + 1; The basic Buck-Boost converter capacitor C 11 The other end is connected to the capacitor C in the first forward expansion unit. 12 One end of the first forward expansion unit capacitor C 12 The other end is connected to the capacitor C in the second forward expansion unit 22 One end of the capacitor C in the second forward expansion unit 22 The other end is connected to the capacitor C in the third forward expansion unit. 32 One end of the capacitor C in the j-1th forward expansion unit (j-1)2 The other end is connected to the capacitor C in the jth forward expansion unit j2 one end of Capacitor C j2 The other end is connected to the positive load R P The other end of the positive load R P One end is connected to the DC input source u in1 the other end.

2. A multi-input bipolar output voltage self-balancing Buck-Boost DC-DC converter according to claim 1, characterized in that: In this converter, when one basic Buck-Boost converter, i reverse conversion units, j forward expansion units, and a total of i+1 input power sources are used, the maximum output voltages of the positive and negative polarities are respectively: In the formula, u N Indicates the negative output voltage of the converter, u P Indicates the positive output voltage of the converter, D1 indicates the duty cycle of the switch S1 in the basic Buck-Boost converter, D (i+1) represents the switch tube S in the i-th reverse conversion unit (i+1) The duty cycle, u in1 Indicates the input voltage in the basic Buck-Boost converter, u in(i+1) represents the input voltage in the i-th reverse conversion unit; The voltage stress of switch S1 in the basic Buck-Boost converter is: Capacitor C 11 The voltage stress on is: The switch tube S in the i-th reverse conversion unit (i+1) The voltage stress is: Capacitor C (i+1)1 The voltage stress on is: Capacitor C (i+1)4 The voltage stress on is: Where k is the independent variable, k∈[1,i]; In the above formula, j=i+1 is true, D1 represents the duty cycle of the switch S1 in the basic Buck-Boost converter, D (i+1) represents the switch tube S in the i-th reverse conversion unit (i+1) The duty cycle, u in1 Indicates the input voltage in the basic Buck-Boost converter, u in(i+1) represents the input voltage in the i-th reverse conversion unit; The capacitor C in the jth forward expansion unit j2 The upper voltage stress is: In this formula, j=i+1 holds; the capacitance C j3 The upper voltage stress is: Among them; k is the independent variable, k∈[1,j].

3. The multi-input bipolar output voltage self-balanced Buck-Boost DC-DC converter according to claim 1, characterized in that: In this converter, the circuit contains a basic Buck-Boost converter, a reverse conversion unit, two forward expansion units, and the inductor L 11 , L 12 , L 21 , L 22 , L 23 The current is continuously conducted; according to the different states of the active switch tube, the circuit can be divided into 6 working states; (1) Mode 1: Active switches S1 and S2 are turned on, diode D 11 , D 12 , D 21 , D 22 are all turned off, at this time the inductor L 11 , L 12 , L 21 , L 22 , L 23 and capacitor C 12 , C 24 Charging, capacitor C 11 , C 13 , C 21 , C 22 , C 23 Discharge; Inductance L 11 , L 12 , L 21 , L 22 , L 23 The terminal voltage is shown as follows: In the formula, u N Indicates the negative output voltage of the converter, u P Indicates the positive polarity output voltage of the converter, u in1 Indicates the input voltage in the basic Buck-Boost converter, u in2 Indicates the input voltage in the first reverse conversion unit; (2) Mode 2: Active switch S1 is turned off, active switch S2 is turned on, and diode D 11 , D 21 , D 22 Both are turned off, diode D 12 is turned on, at this time the inductor L 21 , L 22 , L 23 and capacitor C 12 , C 13 , C 22 , C 24 Charging, inductance L 11 , L 12 and capacitor C 11 , C 21 , C 23 Discharge; Inductance L 11 , L 12 , L 21 , L 22 , L 23 The terminal voltage is shown as follows: (3) Mode 3: Active switch S1 is turned off, active switch S2 is turned on, and diode D 21 , D 22 Both are turned off, diode D 11 , D 12 is turned on, at this time the inductor L 21 , L 22 , L 23 and capacitor C 11 , C 12 , C 22 , C 24 Charging, inductance L 11 , L 12 and capacitor C 13 , C 21 , C 23 Discharge; Inductance L 11 , L 12 , L 21 , L 22 , L 23 The terminal voltage is shown as follows: (4) Mode 4: Active switches S1 and S2 are turned off, diode D 22 Turn off, diode D 11 , D 12 , D 21 The capacitor C 11 , C 12 , C 13 , C 21 , C 22 Charging, inductance L 11 , L 12 , L 21 , L 22 , L 23 and capacitor C 23 , C 24 Discharge; Inductance L 11 , L 12 , L 21 , L 22 , L 23 The terminal voltage is shown as follows: (5) Mode 5: Active switches S1 and S2 are turned off, diode D 11 , D 12 , D 21 , D 22 The capacitor C 11 , C 13 , C 21 , C 22 , C 23 Charging, inductance L 11 , L 12 , L 21 , L 22 , L 23 and capacitor C 12 , C 24 Discharge; Inductance L 11 , L 12 , L 21 , L 22 , L 23 The terminal voltage is shown as follows: (6) Mode 6: Active switch tube S2 is turned off, active switch tube S1 is turned on, and diode D 11 , D 12 Turn off, diode D 21 , D 22 The capacitor C 11 , C 13 , C 21 , C 24 Charging, inductance L 11 , L 12 , L 21 , L 22 , L 23 and capacitor C 12 , C 22 , C 23 Discharge; Inductance L 11 , L 12 , L 21 , L 22 , L 23 The terminal voltage is shown as follows: Using the above inductor voltage expression, the voltage stress on each capacitor can be obtained as follows:

4. A multi-input bipolar output voltage self-balancing Buck-Boost DC-DC converter, characterized in that: The converter includes a basic Buck-Boost converter, a reverse conversion unit, and two forward expansion units, among which: The basic Buck-Boost converter consists of an inductor L 11 , a capacitor C 11 , an active switch tube S1, a diode D 11 , a DC input source u in1 The connection form is as follows: the source of the active switch tube S1 is connected to the inductor L 11 One end of the diode D 11 The cathode, drain of active switch tube S1 is connected to the DC input source u in1 One end of the diode D 11 The anode connection capacitance C 11 One end of the capacitor C 11 The other end of the inductor L 11 The other end, DC input source u in1 The other end is grounded; The first reverse conversion unit includes two inductors L 21 , L 22 , two capacitors C 21 , C 24 , an active switch tube S2, a diode D 21 , a DC input source u in2 The connection form is as follows: the source of the active switch tube S2 is connected to the inductor L 21 One end of the capacitor C 24 The drain of the active switch tube S2 is connected to the DC input source u in2 One end of the DC input source u in2 The other end of the inductor L 21 The other end of the capacitor C 24 The other end of the inductor L 22 One end of the diode D 21 The cathode of diode D 21 The anode connection capacitance C 21 One end of the capacitor C 21 The other end of the inductor L 22 The other end of The basic Buck-Boost converter has a DC input source u in1 The other end is connected to the DC input source u of the first reverse conversion unit. in2 The other end of The basic Buck-Boost converter capacitor C 11 One end of the capacitor C is connected to the first reverse conversion unit 21 The other end of the capacitor C 21 One end is connected to the negative load R N One end, negative polarity load R N The other end is connected to the DC input source u of the basic Buck-Boost converter in1 The other end of The first forward expansion unit includes an inductor L 12 , a diode D 12 , two capacitors C 12 , C 13 ; Among them, the inductance L 12 One end of each capacitor is connected to 13 The other end of the diode D 12 The cathode of the inductor L 12 The other end of the capacitor C 12 The other end of the capacitor C 12 One end of the diode D 12 Anode; The second forward expansion unit includes an inductor L 23 , a diode D 22 , two capacitors C 22 , C 23 ; Among them, the inductance L 23 One end of each capacitor is connected to 23 The other end of the diode D 22 The cathode of the inductor L 23 The other end of the capacitor C 22 The other end of the capacitor C 22 One end of the diode D 22 Anode; The capacitor C in the first forward expansion unit 13 One end of the basic Buck-Boost converter is connected to the diode D 11 Cathode; Capacitor C in the second forward expansion unit 23 One end of the diode D is connected to the first reverse conversion unit 21 The cathode; The basic Buck-Boost converter capacitor C 11 The other end is connected to the capacitor C in the first forward expansion unit. 12 One end of the first forward expansion unit capacitor C 12 The other end is connected to the capacitor C in the second forward expansion unit 22 one end of Capacitor C 22 The other end is connected to the positive load R P The other end of the positive load R P One end is connected to the DC input source u in1 the other end.

Images