Single-phase voltage-multiplying pseudo totem pole rectifying circuit for direct current charging pile

Abstract

The invention discloses a single-phase voltage-multiplying pseudo totem pole rectifying circuit for a direct-current charging pile. The circuit comprises an alternating-current power supply Ug, an inductor L1, an inductor L2, diodes D1 to D6, switching tubes S1 to S2, a capacitor C1, a capacitor C2, a capacitor C3 and a load RL, and the switched capacitor C2, the capacitor C3, the diode D5 and the inductor L3 are respectively connected to form a voltage-multiplying unit. The advantages of a single-phase pseudo totem-pole circuit and a voltage doubling rectifying circuit are combined, the loss of a rectifying bridge is saved by utilizing a totem-pole bridgeless structure, the space can be better utilized through the double-inductor design, and the size of the whole circuit is reduced. And voltage multiplication is realized by adopting a voltage doubling rectifying circuit. Compared with a traditional rectifying circuit, the circuit can effectively reduce voltage stress of a power device, harmonic wave distortion of input current and electromagnetic interference of a filter, and therefore the overall performance and reliability of a system are improved. Meanwhile, the voltage doubling rectifying circuit can be designed and adjusted according to requirements so as to adapt to different input and output voltage requirements.

Description

Technical Field

[0001] The invention relates to a single-phase rectifier circuit, in particular to a single-phase voltage-doubling pseudo-totem pole rectifier circuit for a DC charging pile. Background Art

[0002] Although traditional rectifier circuits are widely used in power conversion, they have problems such as low working efficiency and large output voltage fluctuations. As the core equipment for electric vehicle energy replenishment, the front-end rectifier circuit of the DC charging pile must meet stringent requirements such as high power density, wide voltage adaptability, high efficiency and low harmonics. The traditional solution is mainly based on totem pole rectifier circuits and cascaded Boost topology, but it has significant deficiencies in high voltage gain, device stress and system reliability. The specific defects are as follows:

[0003] 1. The traditional totem pole rectifier circuit reduces conduction loss by virtue of its bridgeless structure, but its voltage boost capability is limited by the Boost principle. For example, when the input voltage is 220V AC (peak value 311V), if 800V DC is required to be output, a higher duty cycle is required. The high duty cycle causes the voltage stress on the MOSFET when it is turned off to be the DC load output voltage, and the body diode reverse recovery current of the totem pole rectifier circuit will significantly increase the switching loss at high frequencies.

[0004] 2. To achieve high voltage output, traditional solutions often use a rectifier circuit + DC / DC cascade structure, which requires an additional DC / DC stage. Although the introduction of the DC / DC unit can achieve a wide range of output, the efficiency of the two stages will be significantly reduced after superposition. In addition, the introduction of the DC / DC unit leads to an increase in the volume of the circuit. Taking 800V output as an example, at least 5 diodes and 1 high-voltage capacitor are required, and the PCB area is significantly increased.

[0005] 3. To improve power density, traditional solutions tend to prefer high-frequency designs, such as above 150KHz, but high frequency will aggravate switching losses and EMI problems. The charge and discharge losses of MOSFET output capacitors are proportional to efficiency. As the switching frequency increases, the losses also increase. In addition, high-frequency harmonics require larger common-mode inductors, which increases the low-level of the charging pile and cannot meet the high power density of the circuit. Summary of the invention

[0006] In order to solve the above technical problems, the present invention provides a single-phase voltage-doubling pseudo-totem pole rectifier circuit for a DC charging pile. The rectifier circuit combines the advantages of a pseudo-totem pole circuit and a voltage-doubling rectifier circuit. The bridgeless structure of the pseudo-totem pole circuit saves the loss of the rectifier bridge, can withstand higher power, and can meet the needs of high-power application scenarios. The circuit adopts a voltage-doubling rectifier circuit structure to achieve voltage doubling. The new rectifier circuit of the present invention not only has the characteristics of high efficiency, stability, and flexibility, but also the voltage-doubling rectifier circuit can be designed and adjusted as needed to adapt to different input and output voltage requirements. The technical solution adopted by the present invention is:

[0007] A single-phase voltage-doubling pseudo-totem pole rectifier circuit for a DC charging pile, comprising:

[0008] AC power supply U g 、Inductance L 1 、Inductance L 2 、Inductance L 3 、Diode D 1 ~D 6 , switch tube S 1 ~S 2 , capacitor C 1 , capacitor C 2 , capacitor C 3 、Load R L ;

[0009] Power supply g One end of the inductor L 1 One end of the inductor L 2 One end of is connected to the node e;

[0010] Power supply g The other end of the diode D 1 The anode of diode D 2 The cathodes of are connected together and connected to the node o;

[0011] Inductance L 1 The other end of the diode D 3 The anode of the diode D 4 The cathodes of are connected together and connected to node a;

[0012] Inductance L 2 The other end is connected to the switch tube S 1 The source of the switch tube S 2 The drains of are connected to each other and are commonly connected to node b;

[0013] Diode D 2 The anode of diode D 4 Anode of the switch tube S 2 The source of the capacitor C 2The negative electrode of capacitor C 1 The negative electrode, load R L The other end of is connected to the node d;

[0014] Diode D 5 The anode of the capacitor C 3 The cathode of diode D 1 The cathode of diode D 3 The cathode of the switch tube S 1 The drains of are connected to each other and are commonly connected to a node c;

[0015] Diode D 5 The cathode of the capacitor C 2 The positive electrode, inductor L 3 One end of is connected to the node g;

[0016] Diode D 6 The anode of the capacitor C 3 The positive electrode, inductor L 3 The other end of is connected to the node h;

[0017] Diode D 6 The cathode of the capacitor C 1 The positive electrode, load R L One end of is connected to each other and are connected to the node p.

[0018] The capacitor C 2 , capacitor C 3 、Diode D 5 、Inductance L 3 Connect to form a voltage doubling unit.

[0019] In the rectifier circuit, six diodes D 1 ~D 6 They can all be replaced with MOSFET, IGBT or IGCT switch tubes containing anti-parallel diodes, which can improve rectification efficiency, reduce power consumption and voltage loss, and at the same time have better controllability, reverse blocking capability and heat dissipation performance.

[0020] The circuit includes 4 working modes:

[0021] Mode 1: Switching tube S 2 Disconnect, S 1 The current flows through the inductor L 1 , diode D 3 , and through the inductor L 2 , switch tube S 1 After merging, and then passing through the diode D 5 , inductance L 3 , diode D 6 , load RL After that, through the diode D 2 Return to the power supply Ug; at this time, the inductance L 1 , L 1 To load R L Charging; Inductance L 3 To capacitor C 3 Charging; Capacitor C 2 Through the inductor L 3 , diode D 6 To capacitor C 1 Charging; Inductance L 1 The current in the linear decreases, and the voltage U ao =U bo =U 1 -U 3 , where U ao Indicates the bridge arm voltage from node a to node o, U bo Indicates the bridge arm voltage from node b to node o, U 1 Represents capacitance C 1 Voltage, U 3 Represents capacitance C 3 Voltage;

[0022] Mode 2: Switching tube S 1 ,S 2 The current flows through the inductor L 1 , diode D 3 , switch tube S 1 , and through the inductor L 2 After merging, and then through the switch tube S 2 , diode D 2 After returning to power supply U g ; At this time, the power supply U g To inductor L 1 , L 2 Charging; Capacitor C 3 Through the inductor L 3 To capacitor C 2 Charging, capacitor C 1 To load R L Charging, inductance L 1 The current in the linear rise, the voltage U ao =U bo =0;

[0023] Mode 3: Switching tube S 1 ,S 2 is turned on, current flows through diode D 1 , switch tube S 1 After the current is split, it passes through the inductor L 2 , and through the switch tube S 2 , diode D 4 , inductance L1 After the confluence, return to the power supply U g ; At this time, the power supply is to the inductor L 1 , L 2 Charging; Capacitor C 3 Through the inductor L 3 To capacitor C 2 Charging, capacitor C 1 To load R L Charging, inductance L 2 The current in the linear rise, the voltage U ao =U bo =0;

[0024] Mode 4: Switching tube S 1 Disconnect, S 2 is turned on, current flows through diode D 1 , diode D 5 , inductance L 3 , diode D 6 , load R L After the split, respectively through the switch tube S 2 , inductance L 2 , and through the diode D 4 , inductance L 1 Then they merge and return to the power supply Ug; at this time, the inductor L 1 , L 2 To load R L Charging; Capacitor C 2 Through the inductor L 3 , diode D 6 To capacitor C 1 Charging; Inductance L 2 The current in the circuit begins to decrease linearly, and the voltage U ao =U bo =U 3 -U 1 .

[0025] In the 6 working modes, the capacitor voltage U 1 =U 2 +U 3 =U dc , where U 2 Represents capacitance C 2 Voltage, U dc Indicates the DC load output voltage.

[0026] The present invention provides a single-phase voltage-doubling pseudo-totem pole rectifier circuit for a DC charging pile, and has the following beneficial effects:

[0027] 1) The rectifier circuit of the present invention itself has the functions of boosting and rectifying. The voltage stress and current stress borne by the switching tube and some diodes are relatively low. By combining with the voltage multiplier unit, this single-phase voltage multiplier type pseudo totem-pole rectifier circuit can boost the input single-phase AC voltage several times.

[0028] 2) The present invention adopts a quasi-Z-source network to form a voltage multiplier unit structure, realizing voltage multiplication, and has the advantages of high efficiency, stability and flexibility, etc. At the same time, this single-phase voltage multiplier type pseudo totem-pole rectifier circuit can also be designed and adjusted according to needs to adapt to different input and output voltage requirements.

[0029] 3) This rectifier circuit uses a totem-pole PFC bridge-less structure, saving the loss of the rectifier bridge. And the design of the dual inductors can make better use of space, reducing the volume of the entire circuit. This new type of rectifier circuit reduces the system loss and cost, improves the conversion efficiency, and also extends the service life of the rectifier unit. Brief Description of the Drawings

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

[0031] Figure 1 is the schematic diagram of the principle of a single-phase voltage multiplier type pseudo totem-pole rectifier circuit for a DC charging pile of the present invention.

[0032] Figure 2 is the schematic diagram of the current path of the working mode 1 of the single-phase voltage multiplier type pseudo totem-pole rectifier circuit.

[0033] Figure 3 is the schematic diagram of the current path of the working mode 2 of the single-phase voltage multiplier type pseudo totem-pole rectifier circuit.

[0034] Figure 4 is the schematic diagram of the current path of the working mode 3 of the single-phase voltage multiplier type pseudo totem-pole rectifier circuit.

[0035] Figure 5 is the schematic diagram of the current path of the working mode 4 of the single-phase voltage multiplier type pseudo totem-pole rectifier circuit.

[0036] Figure 6 is the schematic diagram of the carrier modulation strategy of the single-phase voltage multiplier type pseudo totem-pole rectifier circuit.

[0037] Figure 7 is the input voltage U g and current i g waveform diagram.

[0038] Figure 8 is the bridge arm voltage U ao 、U bo waveform diagram.

[0039] Figure 9 The output DC voltage U is a single-phase voltage doubler pseudo-totem pole rectifier circuit. dc Waveform graph.

[0040] Figure 10 The bridge arm voltage U is when the load of the single-phase voltage-doubling pseudo-totem pole rectifier circuit is halved ao , U bo Waveform graph.

[0041] Figure 11 The output DC voltage U of the single-phase voltage-doubling pseudo-totem pole rectifier circuit when the load is halved dc Waveform graph. DETAILED DESCRIPTION

[0042] like Figure 1 As shown, a single-phase voltage-doubling pseudo-totem pole rectifier circuit for a DC charging pile includes:

[0043] AC power supply U g 、Inductance L 1 、Inductance L 2 、Inductance L 3 、Diode D 1 ~D 6 , switch tube S 1 ~S 2 , capacitor C 1 , capacitor C 2 , capacitor C 3 、Load R L ;

[0044] Power supply g One end of the inductor L 1 One end of the inductor L 2 One end of is connected to the node e;

[0045] Power supply g The other end of the diode D 1 The anode of diode D 2 The cathodes of are connected together and connected to the node o;

[0046] Inductance L 1 The other end of the diode D 3 The anode of the diode D 4 The cathodes of are connected together and connected to node a;

[0047] Inductance L 2 The other end is connected to the switch tube S 1 The source of the switch tube S 2 The drains of are connected to each other and are commonly connected to node b;

[0048] Diode D 2The anode of diode D 4 Anode of the switch tube S 2 The source of the capacitor C 2 The negative electrode of capacitor C 1 The negative electrode, load R L The other end of is connected to the node d;

[0049] Diode D 5 The anode of the capacitor C 3 The cathode of diode D 1 The cathode of diode D 3 The cathode of the switch tube S 1 The drains of are connected to each other and are commonly connected to a node c;

[0050] Diode D 5 The cathode of the capacitor C 2 The positive electrode, inductor L 3 One end of is connected to the node g;

[0051] Diode D 6 The anode of the capacitor C 3 The positive electrode, inductor L 3 The other end of is connected to the node h;

[0052] Diode D 6 The cathode of the capacitor C 1 The positive electrode, load R L One end of is connected to each other and are connected to the node p.

[0053] The capacitor C 2 , capacitor C 3 、Diode D 5 、Inductance L 3 Connect to form a voltage doubling unit.

[0054] The following describes the specific working principle of the rectifier circuit of the present invention, a single-phase voltage-doubling pseudo-totem pole rectifier circuit for a DC charging pile. The single-phase voltage-doubling pseudo-totem pole rectifier circuit has four working modes. The specific analysis process is as follows:

[0055] Figure 2 Schematic diagram of the current path in mode 1: switch tube S 2 Disconnect, S 1 The current flows through the inductor L 1 , diode D 3 , and through the inductor L 2 , switch tube S 1 After merging, and then passing through the diode D 5 , inductance L 3 , diode D 6 , load RL After that, through the diode D 2 Return to the power supply Ug; at this time, the inductance L 1 , L 1 To load R L Charging; Inductance L 3 To capacitor C 3 Charging; Capacitor C 2 Through the inductor L 3 , diode D 6 To capacitor C 1 Charging; Inductance L 1 The current in the linear decreases, and the voltage U ao =U bo =U 1 -U 3 ;

[0056] Figure 3 Schematic diagram of the current path in mode 2: switch tube S 1 ,S 2 The current flows through the inductor L 1 , diode D 3 , switch tube S 1 , and through the inductor L 2 After merging, and then through the switch tube S 2 , diode D 2 After returning to power supply U g ; At this time, the power supply U g To inductor L 1 , L 2 Charging; Capacitor C 3 Through the inductor L 3 To capacitor C 2 Charging, capacitor C 1 To load R L Charging, inductance L 1 The current in the linear rise, the voltage U ab =0;

[0057] Figure 4 Schematic diagram of the current path in mode 3: switch tube S 1 ,S 2 is turned on, current flows through diode D 1 , switch tube S 1 After the current is split, it passes through the inductor L 2 , and through the switch tube S 2 , diode D 4 , inductance L 1 After the confluence, return to the power supply U g ; At this time, the power supply is to the inductor L 1 , L 2 Charging; Capacitor C 3 Through the inductor L 3To capacitor C 2 Charging, capacitor C 1 To load R L Charging, inductance L 2 The current in the linear rise, the voltage U ab =0;

[0058] Figure 5 Schematic diagram of mode 4 current path: switch tube S 1 Disconnect, S 2 is turned on, current flows through diode D 1 , diode D 5 , inductance L 3 , diode D 6 , load R L After the split, respectively through the switch tube S 2 , inductance L 2 , and through the diode D 4 , inductance L 1 After merging, return to the power supply Ug; at this time, the inductance L 1 , L 2 To load R L Charging; Capacitor C 2 Through the inductor L 3 , diode D 6 To capacitor C 1 Charging; Inductance L 2 The current in the circuit begins to decrease linearly, and the voltage U ao =U bo =U 3 -U 1 ;

[0059] Table 1 is a table showing the correspondence between the pulse distribution mode of the switch tube of the rectifier circuit, the working state of the DC side inductor and capacitor, where the on and off of the switch tube are represented by "1" and "0" respectively.

[0060] Table 1 Relationship between the pulse distribution mode of the rectifier circuit switch tube, the working state of the DC side inductor and capacitor

[0061]

[0062] Figure 6 Schematic diagram of the multi-carrier modulation strategy of the pseudo-totem pole rectifier circuit in the present invention. Figure 10 As shown, the modulation signal U ref is a sine wave, which is related to the triangular carrier signal V i (i=1,2) for comparison, when U ref >V i When the switch tube in the corresponding working mode is turned on, otherwise it is turned off, and then the modulated output is close to the sinusoidal voltage U ao , U boWaveform, according to the four working modes of the pseudo totem pole rectifier circuit, the voltage U ao , U bo Divided into two voltage intervals, namely interval 1 (0, U 1 -U 3 ), interval 2 (U 3 -U 1 , 0), voltage U ao , U bo There are three level states: 0, U 1 -U 3 , U 1 -U 3 .

[0063] In order to verify that the single-phase voltage doubling pseudo-totem pole rectifier circuit for DC charging piles of the present invention can realize the voltage doubling function, an experimental verification is carried out under the dual-loop control strategy. The experimental parameters are: input voltage effective value 220V, operating frequency 50Hz, inductance L 1 , L 2 is 2.5mH, inductance L 3 is 2.5mH, capacitor C 1 is 3500uF, capacitor C 2 is 250uF, capacitor C 3 The resistor is 160uF, the switching frequency is 20kHz, and the load is 80Ω.

[0064] Figure 7 The input voltage U is the single-phase voltage doubler pseudo-totem pole rectifier circuit g and current i g Waveform diagram, the present invention controls the on and off of the switching 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, such as Figure 7 As shown in the waveform, the voltage and current are in phase, which means that the power factor correction function is achieved.

[0065] Figure 8 is the voltage U of the pseudo totem pole rectifier circuit ab Waveform diagram, such as Figure 8 As shown, the pseudo-totem pole rectifier circuit of the present invention distributes pulses to the switch tubes in each mode and adopts a multi-carrier modulation strategy to output a two-level voltage waveform U ao , U bo , the experimental verification and theoretical analysis results are consistent.

[0066] Figure 9 The output DC voltage U is a single-phase voltage doubler pseudo-totem pole rectifier circuit. dc Waveform diagram, the present invention designs a single-phase voltage-doubling pseudo-totem pole rectifier circuit with an input of 220V and an output of 800V. Figure 9 The waveform shows that the voltage U dcDouble.

[0067] Figure 10 The bridge arm voltage U is when the load of the pseudo-totem pole rectifier circuit is halved ao , U bo Waveform diagram, when the load suddenly decreases from 80Ω to 40Ω at 0.35s, and recovers to 40Ω at 0.4s, it can be seen from the waveform that the voltage U ao , U bo No obvious fluctuation.

[0068] Figure 11 The output DC voltage U of the single-phase voltage-doubling pseudo-totem pole rectifier circuit when the load is halved dc Waveform, output DC voltage U dc The waveform is slightly adjusted at 0.35s to 0.4s and quickly returns to a stable state, indicating that the single-phase voltage-doubler rectifier circuit has strong system dynamic adjustment capability and good anti-disturbance performance.

[0069] The present invention discloses a single-phase voltage-doubling pseudo-totem pole rectifier circuit for a DC charging pile. The single-phase voltage-doubling pseudo-totem pole rectifier circuit can make the rectifier circuit have low voltage stress on the switch, thereby reducing cost and switching loss. Compared with the traditional boost converter, it cannot provide high voltage gain due to the parasitic resistance in the circuit. The circuit adopts a pseudo-totem pole PFC bridgeless structure, saves the loss of the rectifier bridge, can effectively improve the conversion efficiency of the power supply, and the dual inductor design can better utilize the space, so that the volume of the entire circuit is reduced.

Claims

1. A single-phase voltage-doubling pseudo-totem pole rectifier circuit for a DC charging pile, characterized in that include: AC power supply U g , inductor L1, inductor L2, inductor L3, diodes D1~D6, switch tubes S1~S2, capacitors C1, capacitors C2, capacitors C3, load R L ; Power supply g One end of is respectively connected to one end of the inductor L1 and one end of the inductor L2, and are connected together to a node e; Power supply g The other end of the inductor L1 is connected to the anode of the diode D1 and the cathode of the diode D2, and they are connected to the node o; the other end of the inductor L1 is connected to the anode of the diode D3 and the cathode of the diode D4, and they are connected to the node a; the other end of the inductor L2 is connected to the source of the switch tube S1 and the drain of the switch tube S2, and they are connected to the node b; The anode of diode D2 is connected to the anode of diode D4, the source of switch S2, the cathode of capacitor C2, the cathode of capacitor C1, and the load R L The other end of is connected to the node d; The anode of the diode D5 is respectively connected to the negative electrode of the capacitor C3, the cathode of the diode D1, the cathode of the diode D3, and the drain of the switch tube S1, and are commonly connected to the node c; The cathode of the diode D5 is connected to the positive electrode of the capacitor C2 and one end of the inductor L3 respectively, and they are connected to the node g together; The anode of the diode D6 is connected to the positive electrode of the capacitor C3 and the other end of the inductor L3 respectively, and they are connected together to the node h; The cathode of diode D6 is connected to the positive electrode of capacitor C1 and the load R L One end of is connected to each other and are connected to the node p.

2. According to claim 1, a single-phase voltage-doubling pseudo-totem pole rectifier circuit for a DC charging pile is characterized in that: The capacitor C2, the capacitor C3, the diode D5, and the inductor L3 are connected to form a voltage doubling unit.

3. According to claim 1, a single-phase voltage-doubling pseudo-totem pole rectifier circuit for a DC charging pile is characterized in that: In the rectifier circuit, the six diodes D1 to D6 can be replaced by switch tubes such as MOSFET, IGBT or IGCT containing anti-parallel diodes.

4. According to claim 1, a single-phase voltage-doubling pseudo-totem pole rectifier circuit for a DC charging pile is characterized in that: The circuit includes 4 working modes: Mode 1: Switch S2 is off, S1 is on, the current passes through the inductor L1, the diode D3, and the inductor L2, and then the switch S1 is combined, and then passes through the diode D5, the inductor L3, the diode D6, and the load R L After that, it returns to the power supply Ug through the diode D2; at this time, the inductor L1 and L1 are connected to the load R L Charging; Inductor L3 charges capacitor C3; Capacitor C2 charges capacitor C1 through inductor L3 and diode D6; The current in inductor L1 decreases linearly, and the voltage U ao =U bo =U1-U3, where U ao Indicates the bridge arm voltage from node a to node o, U bo represents the bridge arm voltage from node b to node o, U1 represents the voltage of capacitor C1, and U3 represents the voltage of capacitor C3; Mode 2: Switches S1 and S2 are turned on. The current passes through the inductor L1, the diode D3, the switch S1, and the inductor L2 before merging. Then, the current passes through the switch S2 and the diode D2 before returning to the power supply U. g ; At this time, the power supply U g Charges inductors L1 and L2; capacitor C3 charges capacitor C2 through inductor L3, and capacitor C1 charges load R L Charging, the current in the inductor L1 rises linearly, and the voltage U ao =U bo =0; Mode 3: Switches S1 and S2 are turned on, the current flows through diode D1, and then is split after switch S1, and then passes through inductor L2, and then passes through switch S2, diode D4, and inductor L1, and then merges and returns to power supply U g ; At this time, the power supply charges the inductors L1 and L2; the capacitor C3 charges the capacitor C2 through the inductor L3, and the capacitor C1 charges the load R L Charging, the current in the inductor L2 rises linearly, and the voltage U ao =U bo =0; Mode 4: Switch S1 is off, S2 is on, current flows through diode D1, diode D5, inductor L3, diode D6, load R L After the current is split, it passes through the switch tube S2, the inductor L2, and the diode D4, and then merges with the inductor L1 and returns to the power supply Ug; at this time, the inductors L1 and L2 are connected to the load R L Charging; capacitor C2 charges capacitor C1 through inductor L3 and diode D6; the current in inductor L2 begins to decrease linearly, and voltage U ao =U bo =U3-U1.

5. A single-phase voltage-doubling pseudo-totem pole rectifier circuit for a DC charging pile according to claim 4, characterized in that: In the 6 working modes, the capacitor voltage U1=U2+U3=U dc , where U2 represents the voltage of capacitor C2, U dc Indicates the DC load output voltage.

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