Single-phase voltage-multiplying interleaving DC charging circuit

Abstract

The invention discloses a single-phase voltage-multiplying interleaving direct-current charging circuit. The circuit comprises an alternating-current power supply Ug, an inductor L1, an inductor L2, diodes D1 to D8, switching tubes S1 to S2, a capacitor C1, a capacitor C2, a capacitor C3 and a load RL. According to the single-phase voltage-multiplying type interleaving parallel direct current charging circuit, the advantages of a single-phase interleaving parallel technology and the advantages of the voltage-multiplying module are combined, the multiple power converter units operate in an interleaving parallel mode, and voltage multiplication is achieved through the voltage-multiplying module. Compared with a traditional direct current charging circuit, the direct current charging circuit can effectively reduce the voltage stress of a power device, the input current THD and the size of an EMI filter through staggered parallel operation of a plurality of power converter units, thereby improving the overall performance and reliability of a system.

Description

Technical Field

[0001] The present invention relates to a single-phase DC charging circuit, in particular to a single-phase voltage-doubling interleaved parallel DC charging circuit. Background Art

[0002] With the transformation of the global energy structure towards cleaner and electrified forms, DC charging circuits, as the core modules of power electronic systems, have seen an explosive growth in application demands in fields such as electric vehicles, data centers, and renewable energy energy storage. Their performance and application scope are also continuously improving and expanding. Although traditional DC charging circuits are widely used in power conversion, they have problems such as low working efficiency and large output voltage fluctuations. For example, in electric vehicle charging infrastructure and data center power systems, DC charging circuits impose strict requirements on the high efficiency, high power density, and wide input adaptability of the front-end rectifier circuit. Traditional solutions mainly use interleaved parallel PFC and cascaded voltage-doubling topologies, but there are still significant defects in terms of high voltage gain, device stress, and system integration. The specific analysis is as follows:

[0003] 1) Traditional interleaved parallel PFC reduces the input current ripple through multi-phase parallel connection, but its voltage gain is the same as that of the traditional Boost topology. For example, when the input is 220V AC (peak value 311V), if an 800V DC output is required, a relatively high duty cycle is needed. A high duty cycle results in the voltage borne by the MOSFET when it is turned off being the DC load output voltage. For an 800V output, SiC devices with a breakdown voltage of 1200V are required. Moreover, the reverse recovery current of the body diode of the MOSFET causes a significant increase in switching losses at high frequencies.

[0004] 2) To achieve a high voltage output, traditional solutions often adopt a rectifier circuit + DC / DC cascaded structure, which requires an additional DC / DC unit to be introduced. Although a wide range of outputs can be achieved after the introduction of the DC / DC unit, the overall efficiency is significantly reduced after the two-stage efficiency is superimposed. In addition, the introduction of the DC / DC unit increases the volume of the circuit. Taking an 800V output as an example, at least 5 diodes and 1 high-voltage capacitor are required, resulting in a significant increase in the PCB area.

[0005] 3) To improve the power density, traditional solutions tend to adopt a high-frequency design, such as above 150KHz. However, high-frequency operation exacerbates the problems of switching losses and EMI. The charge and discharge losses of the output capacitance of the MOSFET are proportional to the efficiency. As the switching frequency increases, the losses also increase. Moreover, high-frequency harmonics require a larger volume of common-mode inductors, resulting in an increase in the volume of the DC charging circuit and being unable to meet the high power density of the circuit. Summary of the Invention

[0006] The present invention provides a single-phase voltage-doubling interleaved parallel DC charging circuit, which can enable the DC charging circuit to have a low voltage stress on the switches, thereby reducing costs and switching losses. Compared with traditional boost converters, it cannot provide a high voltage gain due to parasitic resistances in the circuit. This DC charging circuit combines the advantages of single-phase interleaved parallel technology and voltage-doubling DC charging circuits. It operates with multiple power converter units in interleaved parallel and uses a voltage-doubling module to achieve voltage multiplication.

[0007] The technical solution adopted by the present invention is as follows:

[0008] A single-phase voltage-doubling interleaved parallel DC charging circuit, the circuit comprising:

[0009] AC power supply U g 、inductor L1, inductor L2, diodes D1 - D8, switching tubes S1 - S2, capacitors C1, C2, C3, load R L ;

[0010] One end of the AC power supply U g is respectively connected to the anode of diode D1 and the cathode of diode D3, and commonly connected to node a; the other end of the AC power supply U g is respectively connected to the anode of diode D2 and the cathode of diode D4, and commonly connected to node b; the cathode of diode D1 is respectively connected to the cathode of diode D2, one end of inductor L1, and one end of inductor L2, and commonly connected to node c;

[0011] The anode of diode D3 is respectively connected to the anode of diode D4, the source of switching tube S1, the source of switching tube S2, the negative electrode of capacitor C2, and the other end of the load R L and commonly connected to node d;

[0012] The other end of inductor L1 is respectively connected to the drain of switching tube S1, the anode of diode D5, and the negative electrode of capacitor C3, and commonly connected to node h;

[0013] The other end of inductor L2 is respectively connected to the drain of switching tube S2 and the anode of diode D6, and commonly connected to node g, and node g is connected to node h;

[0014] The cathode of diode D5 is respectively connected to the cathode of diode D6, the anode of diode D8, the negative electrode of capacitor C1, and the positive electrode of capacitor C2, and commonly connected to node o;

[0015] The positive electrode of capacitor C3 is respectively connected to the anode of diode D7 and the cathode of diode D8, and commonly connected to node e;

[0016] The cathode of diode D7 is respectively connected to the positive electrode of capacitor C1 and the load R LOne end is connected to the other end, and they are jointly connected to node p.

[0017] The capacitor C3, capacitor C1, diode D7, and diode D8 form a voltage multiplier module.

[0018] This DC charging circuit includes six working modes:

[0019] Mode 1: The switching transistor S2 is turned off, S1 is turned on, and the current flows through the inductor L1, then returns to the AC power supply U after the switching transistor S1. g ; At this time, the AC power supply U g charges the inductor L1; the inductor L2 charges the capacitor C2 and the load R simultaneously through the diode D6. L The capacitor C3 charges the capacitor C1 through the diode D7; the current in the inductor L1 starts to linearly increase from zero, and the current in the inductor L2 continues to decrease.

[0020] Mode 2: The switching transistor S2 remains off, S1 remains on, and the current flows through the inductor L1, then returns to the AC power supply U after the switching transistor S1. g ; At this time, the AC power supply U g continues to charge the inductor L1; the capacitor C2 charges the capacitor C3 through the diode D8; the current in the inductor L2 has decreased to 0, and the current in the inductor L1 continues to increase.

[0021] Mode 3: The switching transistors S1 and S2 are all turned off, and the inductor L1 discharges to the load R L and the capacitor C2 through the diode D5; the inductor L2 discharges to zero; the capacitor C3 charges the capacitor C1 through the diode D7; the current in the inductor L1 starts to linearly decrease, and the current in the inductor L2 continues to be 0.

[0022] Mode 4: The switching transistor S1 is turned off, S2 is turned on, and the current flows through the inductor L2, then returns to the AC power supply U after the switching transistor S2. g ; At this time, the AC power supply U g charges the inductor L2; the inductor L1 charges the load R L and the capacitor C2 through the diode D5; the capacitor C3 charges the capacitor C1 through the diode D7; the current in the inductor L1 continues to linearly decrease, and the current in the inductor L2 starts to linearly increase.

[0023] Mode 5: The switching transistor S1 remains off, S2 remains on, and the current flows through the inductor L2, then returns to the AC power supply U after the switching transistor S2. g ; At this time, the AC power supply U g continues to charge the inductor L2; the capacitor C2 charges the capacitor C3 through the diode D8; the current in the inductor L1 decreases to 0, and the current in the inductor L2 continues to increase.

[0024] Mode 6: Both switching tubes S1 and S2 are turned off. Inductor L2 charges the load R and capacitor C2 simultaneously through diode D6. Capacitor C3 charges capacitor C1 through diode D7. The current in inductor L1 remains 0, and the current in inductor L2 starts to decrease linearly. L The current in inductor L2 charges the load R and capacitor C2 simultaneously through diode D6. Capacitor C3 charges capacitor C1 through diode D7. The current in inductor L1 remains 0, and the current in inductor L2 starts to decrease linearly.

[0025] Among the six operating modes, the capacitor voltages U1 = U2 = 1 / 2U dc , where U1 represents the voltage of capacitor C1; U2 represents the voltage of capacitor C2; U dc represents the DC load output voltage.

[0026] A single-phase voltage-doubling interleaved DC charging circuit according to the present invention has the following beneficial effects:

[0027] 1) The DC charging circuit of the present invention itself has a boosting and DC function. By integrating a voltage-doubling module and an interleaved parallel framework, this single-phase voltage-doubling interleaved DC charging circuit can boost the input single-phase AC voltage several times, and the peak voltage borne by the switching tubes is reduced to 50% (400V) of the traditional scheme. Low-cost 600V SiMOSFETs can be selected to replace 1200V SiC devices.

[0028] 2) The present invention uses a switched-capacitor circuit to form a voltage-doubling module, replacing the traditional cascaded DC / DC unit, eliminating multi-stage energy conversion losses, doubling the voltage while reducing the number of components and shrinking the PCB area. At the same time, this single-phase voltage-doubling interleaved DC charging circuit can also be designed and adjusted according to needs to adapt to different input and output voltage requirements.

[0029] 3) The present invention adopts an interleaved parallel design, enabling each DC unit to work alternately, effectively dispersing the current load and reducing the current stress of a single DC unit. This not only improves the overall working efficiency of the DC charging circuit but also extends the service life of the DC unit. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] The present invention will be further described below in conjunction with the drawings and examples;

[0031] Figure 1 is a schematic diagram of the principle of a single-phase voltage-doubling interleaved DC charging circuit according to the present invention.

[0032] Figure 2 is a schematic diagram of the current path of the single-phase voltage-doubling interleaved DC charging circuit in operating mode 1;

[0033] Figure 3 is a schematic diagram of the current path of the single-phase voltage-doubling interleaved DC charging circuit in operating mode 2;

[0034] Figure 4Schematic diagram of the current path in operating mode 3 of a single-phase voltage-doubling interleaved parallel DC charging circuit;

[0035] Figure 5 Schematic diagram of the current path in operating mode 4 of a single-phase voltage-doubling interleaved parallel DC charging circuit;

[0036] Figure 6 Schematic diagram of the current path in operating mode 5 of a single-phase voltage-doubling interleaved parallel DC charging circuit;

[0037] Figure 7 Schematic diagram of the current path in operating mode 6 of a single-phase voltage-doubling interleaved parallel DC charging circuit;

[0038] Figure 8 Input voltage U g and current i g waveform diagram of a single-phase voltage-doubling interleaved parallel DC charging circuit.

[0039] Figure 9 Output DC voltage U dc waveform diagram of a single-phase voltage-doubling interleaved parallel DC charging circuit.

[0040] Figure 10 Output DC voltage U dc waveform diagram when the load of a single-phase voltage-doubling interleaved parallel DC charging circuit is halved. Specific implementation mode

[0041] As Figure 1 shown, a single-phase voltage-doubling interleaved parallel DC charging circuit includes:

[0042] AC power supply U g , inductor L1, inductor L2, diodes D1 - D8, switching tubes S1 - S2, capacitors C1, C2, C3, load R L ;

[0043] One end of the AC power supply U g is respectively connected to the anode of diode D1 and the cathode of diode D3, and commonly connected to node a; the other end of the AC power supply U g is respectively connected to the anode of diode D2 and the cathode of diode D4, and commonly connected to node b; the cathode of diode D1 is respectively connected to the cathode of diode D2, one end of inductor L1, and one end of inductor L2, and commonly connected to node c;

[0044] The anode of diode D3 is respectively connected to the anode of diode D4, the source of switching tube S1, the source of switching tube S2, the negative electrode of capacitor C2, and the other end of the load R L , and commonly connected to node d;

[0045] The other end of the inductor L1 is respectively connected to the drain of the switching transistor S1, the anode of the diode D5, and the negative electrode of the capacitor C3, and they are commonly connected to the node h;

[0046] The other end of the inductor L2 is respectively connected to the drain of the switching transistor S2 and the anode of the diode D6, and they are commonly connected to the node g, and the node g is connected to the node h;

[0047] The cathode of the diode D5 is respectively connected to the cathode of the diode D6, the anode of the diode D8, the negative electrode of the capacitor C1, and the positive electrode of the capacitor C2, and they are commonly connected to the node o;

[0048] The positive electrode of the capacitor C3 is respectively connected to the anode of the diode D7 and the cathode of the diode D8, and they are commonly connected to the node e;

[0049] The cathode of the diode D7 is respectively connected to the positive electrode of the capacitor C1 and one end of the load R L and they are commonly connected to the node p.

[0050] The capacitor C3, the capacitor C1, the diode D7, and the diode D8 constitute a voltage multiplier module.

[0051] The following describes the DC charging circuit of the present invention, the specific working principle of a single-phase voltage multiplier interleaved parallel DC charging circuit. The single-phase voltage multiplier interleaved parallel DC charging circuit has a total of 6 working modes, and the specific analysis process is as follows:

[0052] Figure 2 It is a schematic diagram of the current path in Mode 1: The switching transistor S2 is turned off, S1 is turned on, the current flows through the inductor L1, and then returns to the AC power supply U through the switching transistor S1 g ; At this time, the AC power supply U g charges the inductor L1; the inductor L2 charges the load R L and the capacitor C2 through the diode D6 at the same time; the capacitor C3 charges the capacitor C1 through the diode D7; the current in the inductor L1 starts to rise linearly from zero, and the current in the inductor L2 continues to decline;

[0053] Figure 3 It is a schematic diagram of the current path in Mode 2: The switching transistor S2 remains turned off, S1 remains turned on, the current flows through the inductor L1, and then returns to the AC power supply U through the switching transistor S1 g ; At this time, the AC power supply U g continues to charge the inductor L1; the capacitor C2 charges the capacitor C3 through the diode D8; the current in the inductor L2 has dropped to 0, and the current in the inductor L1 continues to rise.

[0054] Figure 4 It is a schematic diagram of the current path in Mode 3: The switching transistors S1 and S2 are all turned off, and the inductor L1 supplies power to the load R through the diode D5 L, the capacitor C2 discharges; the inductor L2 discharges to zero; the capacitor C3 charges the capacitor C1 through the diode D7; the current in the inductor L1 starts to linearly decrease, and the current in the inductor L2 continues to be 0.

[0055] Figure 5 It is a schematic diagram of the current path in Mode 4: The switch tube S1 is turned off, S2 is turned on, the current flows through the inductor L2, and returns to the AC power supply U after the switch tube S2. g ; At this time, the power supply U g charges the inductor L2; the inductor L1 charges the load R L and the capacitor C2; the capacitor C3 charges the capacitor C1 through the diode D7; the current in the inductor L1 continues to linearly decrease, and the current in the inductor L2 starts to linearly increase;

[0056] Figure 6 It is a schematic diagram of the current path in Mode 5: The switch tube S1 remains off, S2 remains on, the current flows through the inductor L2, and returns to the AC power supply U after the switch tube S2. g ; At this time, the AC power supply U g continues to charge the inductor L2; the capacitor C2 charges the capacitor C3 through the diode D8; the current in the inductor L1 drops to 0, and the current in the inductor L2 continues to increase.

[0057] Figure 7 It is a schematic diagram of the current path in Mode 6: The switch tubes S1 and S2 are all turned off, and the inductor L2 charges the load R L and the capacitor C2 simultaneously through the diode D6; the capacitor C3 charges the capacitor C1 through the diode D7; the current in the inductor L1 continues to be 0, and the current in the inductor L2 starts to linearly decrease.

[0058] Table 1 is a corresponding relationship table of the pulse distribution mode of the switch tube in the DC charging circuit, the working states of the DC-side inductor and capacitor, where the conduction and turn-off of the switch tube are represented by "1" and "0" respectively, and the zero discharge of the inductor is represented by "0".

[0059] Table 1 Corresponding Relationship Table of Pulse Distribution Mode of Switch Tube in DC Charging Circuit, Working States of DC-Side Inductor and Capacitor

[0060]

[0061] To verify that a single-phase voltage-doubling interleaved parallel DC charging circuit of the present invention can achieve the voltage-doubling function, under the PR control strategy, experimental verification is carried out. Experimental parameters: effective input voltage 220V, working frequency 50Hz, two equal-value inductors 8.5mH, switching capacitor 400uF, two output capacitors 4000uF, switching frequency 20kHz, load 160Ω.

[0062] Figure 8For the input voltage U of the single-phase voltage-doubling interleaved parallel DC charging circuit g and current i g waveform diagram, the present invention controls the conduction and turn-off of the switch converter to make the input current waveform as close to a sine wave as possible, which can further reduce the harmonic content of the grid-side current. As shown in Figure 8 the waveform, the voltage and current are in the same phase, that is, the power factor correction function is realized.

[0063] Figure 9 For the output DC voltage U of the single-phase voltage-doubling interleaved parallel DC charging circuit dc waveform diagram, the present invention designs a single-phase voltage-doubling interleaved parallel DC charging circuit with an input of 220V and an output of 800V. As can be seen from Figure 9 the waveform, the voltage U dc is doubled.

[0064] Figure 10 For the output DC voltage U of the single-phase voltage-doubling interleaved parallel DC charging circuit when the load is halved dc waveform diagram, the output DC voltage U dc waveform is slightly adjusted from 0.4s to 0.5s and quickly returns to the stable state, indicating that the single-phase voltage-doubling interleaved parallel DC charging circuit has strong system dynamic regulation ability and good anti-disturbance performance.

[0065] The present invention relates to a single-phase voltage-doubling interleaved parallel DC charging circuit, which combines the advantages of single-phase interleaved parallel technology and voltage-doubling modules. Multiple power converter units operate in interleaved parallel, and a voltage-doubling module is used to achieve voltage doubling. Compared with traditional DC charging circuits, this DC charging circuit can effectively reduce the voltage stress of power devices, the input current THD, and the size of the EMI filter by operating multiple power converter units in interleaved parallel, thereby improving the overall performance and reliability of the system. At the same time, the single-phase voltage-doubling interleaved parallel DC charging circuit can also be designed and adjusted according to needs to adapt to different input and output voltage requirements.

Claims

1. A single-phase voltage-doubling interleaved parallel DC charging circuit, characterized in that The circuit includes: AC power supply U g , inductors L1, L2, diodes D1 to D8, switching transistors S1 to S2, capacitors C1, C2, C3, load R L ; AC power supply U g One end of which is respectively connected to the anode of diode D1 and the cathode of diode D3, and they are commonly connected to node a; AC power supply U g The other end is respectively connected to the anode of diode D2 and the cathode of diode D4, and they are commonly connected to node b; The cathode of diode D1 is respectively connected to the cathode of diode D2, one end of inductor L1, and one end of inductor L2, and they are commonly connected to node c; The anode of diode D3 is respectively connected to the anode of diode D4, the source of switching transistor S1, the source of switching transistor S2, the negative electrode of capacitor C2, and the other end of load R L and they are commonly connected to node d; The other end of inductor L1 is respectively connected to the drain of switch tube S1, the anode of diode D5, and the negative electrode of capacitor C3, and they are commonly connected to node h; The other end of inductor L2 is respectively connected to the drain of switch tube S2 and the anode of diode D6, and they are commonly connected to node g, and node g is connected to node h; The cathode of diode D5 is respectively connected to the cathode of diode D6, the anode of diode D8, the negative electrode of capacitor C1, and the positive electrode of capacitor C2, and they are commonly connected to node o; The positive electrode of capacitor C3 is respectively connected to the anode of diode D7 and the cathode of diode D8, and they are commonly connected to node e; The cathode of diode D7 is respectively connected to the positive electrode of capacitor C1 and one end of load R L and they are commonly connected to node p.

2. The single-phase voltage-doubling interleaved parallel DC charging circuit according to claim 1, wherein: The capacitor C3, capacitor C1, diode D7, and diode D8 constitute a voltage multiplier module.

3. The single-phase voltage-doubling interleaved parallel DC charging circuit according to claim 1, wherein: The DC charging circuit includes operating mode 1: the switching transistor S2 is turned off, S1 is turned on, the current flows through the inductor L1, and returns to the AC power supply U after the switching transistor S1. g ; At this time, the AC power supply U g charges the inductor L1; the inductor L2 charges the capacitor C2 and the load R L simultaneously through the diode D6; the capacitor C3 charges the capacitor C1 through the diode D7; the current in the inductor L1 starts to rise linearly from zero, and the current in the inductor L2 continues to decrease.

4. The single-phase voltage-doubling interleaved parallel DC charging circuit according to claim 3, characterized in that: This DC charging circuit includes operating mode 2: The switching transistor S2 remains off, S1 remains on, the current flows through the inductor L1, and returns to the AC power supply U after passing through the switching transistor S1. g ; At this time, the AC power supply U g continues to charge the inductor L1; the capacitor C2 charges the capacitor C3 through the diode D8; the current in the inductor L2 has dropped to 0, and the current in the inductor L1 continues to rise.

5. The single-phase voltage-doubling interleaved parallel DC charging circuit according to claim 4, characterized in that: This DC charging circuit includes operating mode 3: switches S1 and S2 are both turned off, and inductor L1 discharges through diode D5 to load R L , and capacitor C2; the current in inductor L2 discharges to zero; capacitor C3 charges capacitor C1 through diode D7; the current in inductor L1 starts to linearly decrease, and the current in inductor L2 remains 0.

6. The single-phase voltage-doubling interleaved parallel DC charging circuit according to claim 5, wherein: The DC charging circuit includes operating mode 4: The switch S1 is turned off, S2 is turned on, the current flows through the inductor L2, and returns to the AC power supply U after the switch S2 g ; At this time, the AC power supply U g charges the inductor L2; the inductor L1 charges the load R L and the capacitor C2 through the diode D5; the capacitor C3 charges the capacitor C1 through the diode D7; the current in the inductor L1 continues to linearly decrease, and the current in the inductor L2 begins to linearly increase.

7. The single-phase voltage-doubling interleaved parallel DC charging circuit according to claim 6, wherein: This DC charging circuit includes operating mode 5: The switching transistor S1 remains off, S2 remains on, the current flows through the inductor L2, and returns to the AC power supply U after passing through the switching transistor S2. g At this time, the AC power supply U g continues to charge the inductor L2; the capacitor C2 charges the capacitor C3 through the diode D8; the current in the inductor L1 drops to 0, and the current in the inductor L2 continues to rise.

8. The single-phase voltage-doubling interleaved parallel DC charging circuit according to claim 7, wherein: This DC charging circuit includes operating mode 6: switches S1 and S2 are all turned off, and inductor L2 charges load R and capacitor C2 simultaneously through diode D6. L Capacitor C3 charges capacitor C1 through diode D7. The current in inductor L1 remains 0, and the current in inductor L2 starts to linearly decrease.

9. The single-phase voltage-doubling interleaved parallel DC charging circuit according to claim 8, wherein: Among the six working modes, the capacitor voltages U1 = U2 = 1 / 2U dc , where U1 represents the voltage of capacitor C1; U2 represents the voltage of capacitor C2; U dc represents the DC load output voltage.

10. The single-phase voltage-doubling interleaved parallel DC charging circuit according to claim 2, wherein: Through the interleaved parallel operation of multiple power converter units, a voltage multiplier is realized by using the voltage multiplier module.

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