A single-switch scalable DC-DC converter

Abstract

The present invention discloses a single-switch expandable DC-DC converter, which belongs to the field of converters. in One end is connected to the positive electrode of the power supply and the load, and the other end is connected to the drain of the switch tube, the anode of the diode D0, and the capacitor C 1,1 The source of the switch tube is connected to the negative electrode of the power supply and the cathode of the diode D1; the capacitor C 1,1 The cathode of the capacitor C0 is connected to the anode of the diode D1 and the load respectively; the anode of the capacitor C1 is connected to the cathode of the diode D0 and the load respectively; the capacitor C 1,2 The cathode of the diode D1 is connected to the inductor L1 and the load; the anode of the diode D1 is connected to the capacitor C 1,1 The cathode of the capacitor is connected to the inductor L1, and the cathode is connected to the capacitor C0 and the capacitor C 1,2 The midpoints are connected; multiple extended LC 2 The D network is connected in parallel at both ends of the inductor L1. Through the topology structure, the topology can be flexibly set according to the range of boost requirements, and the voltage stress of the switch tube and the diode is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of power electronic converters, and in particular to a single-switch expandable DC-DC converter. Background Art

[0002] As the cost of sustainable energy systems decreases and global research on reducing carbon dioxide emissions deepens, energy transition is becoming a major challenge facing humanity. Electrification plays a crucial role in this transformation. By utilizing renewable energy or electricity as the primary energy source, it can significantly reduce the demand for limited fossil fuels. For example, the widespread adoption of battery electric vehicles (BEVs) and hybrid electric vehicles (HEVs) has gradually replaced internal combustion engine (ICE) vehicles in the automotive industry. To increase the inverter's input bus voltage and improve power system efficiency, step-up DC-DC converters play a crucial role in energy conversion in electric vehicles and are therefore of great research significance.

[0003] DC-DC converters used in vehicles must have a wide voltage gain range to accommodate different battery voltage levels. DC-DC converters also need to be properly designed for electromagnetic compatibility (EMC) to minimize electromagnetic interference (EMI) and its impact on on-board equipment. In addition, a stable DC power supply is crucial for low-voltage auxiliary systems within the vehicle. As a bridge between the high-voltage battery system and auxiliary equipment, the DC-DC converter also needs to exhibit low output voltage ripple. In addition, to extend device life and save energy, the DC-DC converter also requires low voltage stress. Reducing the number of semiconductor devices in the converter can also minimize losses and improve overall conversion efficiency. Therefore, the development of efficient and reliable DC-DC converters is crucial for the successful energy transition of new energy vehicles, especially electric vehicles.

[0004] In electric vehicle design, a boost DC-DC converter is often used to increase the inverter's input bus voltage, thereby improving powertrain efficiency. Since the voltage levels of electronic devices and engines differ, a DC-DC converter can address both. Summary of the Invention

[0005] In response to the main defects of existing boost DC-DC converters, the present invention provides a single-switch scalable DC-DC converter, which reduces switching losses while having a simple control circuit, meets voltage level output requirements of different requirements, reduces device size, improves the power density of the converter, and effectively reduces input current ripple by designing the inductance value.

[0006] In order to achieve the above object, the technical solution provided by the present invention is:

[0007] A single-switch expandable DC-DC converter, the DC-DC converter includes a switch tube S, an inductor L in , power supply V in , capacitor C0, capacitor C 1,1 , capacitor C 1,2 , diode D0, diode D1, and inductor L1; inductor L in One end of the power supply V in The positive electrode is connected to the load R, and the other end is connected to the drain of the switch tube S, the anode of the diode D0, and the capacitor C 1,1 The source of the switch tube S is connected to the power supply V in The negative electrode of the diode D1 is connected to the cathode of the capacitor C 1,1 The cathode of the diode D1 and the inductor L1 are connected respectively; the anode of the capacitor C0 is connected respectively to the cathode of the diode D0 and the load R; the capacitor C 1,2 The cathode of the diode D1 is connected to the inductor L1 and the load R; the anode of the diode D1 is connected to the capacitor C 1,1 The cathode of the capacitor is connected to the capacitor C0 and the inductor L1. 1,2 The DC-DC converter also includes an extended LC 2 D network, the expanded LC 2 The D network is connected in parallel across the inductor L1.

[0008] In the above single switch expandable DC-DC converter, the DC-DC converter includes a plurality of the expanded LC 2 D network, multiple extended LC 2 D networks are connected in series with each other.

[0009] In the above single switch expandable DC-DC converter, a single expanded LC 2 The D network includes capacitor C 2,1 , capacitor C 2,2 , diode D2, and inductor L2; capacitor C 2,1 The anode of the capacitor is connected to one end of the inductor L1, and the cathode is connected to the anode of the diode D1; the capacitor C 2,2 The anode of the inductor L1 is connected to the other end of the inductor L1 and the cathode of the diode D1; the inductor L2 is connected to the capacitor C 2,2 and diode D2.

[0010] In the above single switch expandable DC-DC converter, the nth expanded LC 2 The D network includes capacitor C n,1 , capacitor C n,2 , diode D n , and inductor L n; When \(t_0\leq t\lt t_1\), control the switch tube \(S\) to conduct, and the diodes \(D_0 - D\) n are reverse-biased, and the power supply \(V\) in charges the inductor \(L\) in , and its current rises linearly. The capacitors \(C_0\) and capacitor \(C\) 1,1 -C n,1 discharge through the switch tube \(S\) to the inductors \(L_1 - L\) n and capacitor \(C\) 1,2 -C n,2 . The load is powered by the series structure of the capacitors \(C_0\) and capacitor \(C\) 1,2 -C n,2 . When \(t_1\leq t\lt t_2\), control the switch tube \(S\) to disconnect, and the diodes \(D_0 - D\) n are forward-biased. The inductor \(L\) in , inductors \(L_1 - L\) n supply power to the capacitor \(C\) 1,2 -C n,2 respectively. The capacitors \(C_0\) and capacitor \(C\) 1,1 -C n,1 are charged through the diodes \(D_0 - D\) n .

[0011] In the above single-switch expandable DC-DC converter, within the entire duty cycle range of \(0\lt d\lt1\), the current ripple of all inductors is controlled by setting the inductor value.

[0012] In the above single-switch expandable DC-DC converter, within the entire duty cycle range of \(0\lt d\lt1\), the switch tube \(S\) and all diodes have low voltage stress and current stress.

[0013] In the above single-switch expandable DC-DC converter, the gain range of the DC-DC converter increases with the increase in the number of the expanded LC2D networks.

[0014] In the above single-switch expandable DC-DC converter, the switch tube \(S\) is a MOSFET, IGBT or SIC.

[0015] Adopting the technical solution provided by the present invention, compared with the existing well-known technologies, it has the following remarkable effects:

[0016] (1) For a single-switch expandable DC-DC converter of the present invention, the gain range of the DC-DC converter can be flexibly set according to the number of the expanded LC [[ID=QQQ]] 2 D networks, and it can meet various voltage level occasions.

[0017] (2) The single-switch expandable DC-DC converter of the present invention adopts a non-isolated type, and will not have the phenomenon of DC-DC converter efficiency reduction due to transformer leakage inductance problems, nor will it generate spike voltage.

[0018] (3) A single-switch expandable DC-DC converter of the present invention reduces electromagnetic interference problems because a constant capacitor voltage is provided between the input and output grounds of the DC-DC converter.

[0019] (4) The single-switch expandable DC-DC converter of the present invention adopts a single-switch structure and has only two working modes, which reduces the control difficulty and reduces the loss of the switch tube.

[0020] (5) Compared with the traditional boost DC-DC converter, the single-switch expandable DC-DC converter of the present invention adds two capacitors, a diode, and an inductor, and designs an expanded LC 2 D network structure. While maintaining a simple control circuit, the voltage gain is also improved.

[0021] (6) The present invention provides a single-switch expandable DC-DC converter with low voltage stress on the switch tube and diode, both of which are less than the output voltage. High-performance switching devices with low withstand voltage ratings and low on-resistance can be used, reducing device size and improving DC-DC converter efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is a circuit diagram of the single-switch expandable DC-DC converter of the present invention.

[0023] Figure 2 Schematic diagram of the key waveforms of the single-switch expandable DC-DC converter of the present invention.

[0024] Figure 3 This is the equivalent circuit diagram of the working mode I of the single-switch expandable DC-DC converter of the present invention.

[0025] Figure 4 This is the equivalent circuit diagram of the working mode II of the single-switch expandable DC-DC converter of the present invention.

[0026] Figure 5 FIG. 4 is a voltage diagram showing the gain of the present invention versus the number of networks n and the duty cycle d. DETAILED DESCRIPTION

[0027] It should be noted that, in order to facilitate the description of the present invention, only the parts related to the invention are shown in the accompanying drawings; at the same time, the words such as one end and the other end described in the present invention are only set to facilitate the description of the technical solution of the present invention and have no special limiting effect. In addition, it should be understood that the type of DC power supply on the input side of the converter described in the present invention can be determined according to the specific application method, scenario or field; the power switch tube is also not limited to MOSFET, and IGBT, SIC, etc. can also be selected according to actual application requirements. The specific embodiments described below are only used to explain the relevant inventions and are not intended to limit the selection of the present invention. In the absence of conflict, the embodiments in this application and the features described in the embodiments can be combined with each other. The present application will be described in detail with reference to the accompanying drawings and in combination with the embodiments.

[0028] Figure 1 This is a circuit diagram of a single-switch expandable DC-DC converter according to the present invention, as shown in FIG. Figure 1 As shown, the present invention proposes a single switch scalable DC-DC converter. The DC-DC converter can be LC-switched according to the needs of the boost range. 2 D network number expansion. When expanding LC 2 When the number of D networks is 1, the inductor L of the DC-DC converter in One end of the power supply V in The positive electrode is connected to the load R, and the other end is connected to the drain of the switch tube S, the anode of the diode D0, and the capacitor C 1,1 The source of the switch tube S is connected to the power supply V in The negative electrode of the diode D1 is connected to the cathode of the capacitor C 1,1 The cathode of the diode D1 and the inductor L1 are connected respectively; the anode of the capacitor C0 is connected respectively to the cathode of the diode D0 and the load R; the capacitor C 1,2 The cathode of the diode D1 is connected to the inductor L1 and the load R; the anode of the diode D1 is connected to the capacitor C 1,1 The cathode of the capacitor is connected to the capacitor C0 and the inductor L1. 1,2 When the LC is extended 2 When the number of D networks is 2, the capacitor C 2,1 The anode of the capacitor is connected to one end of the inductor L1, and the cathode is connected to the anode of the diode D2; the capacitor C 2,2 The anode of the inductor L1 is connected to the other end of the inductor L1 and the cathode of the diode D2; the inductor L2 is connected to the capacitor C 2,2 and diode D2. When the LC 2 When the number of D networks is n, the connection method is similar.

[0029] With this topology, the topology can be flexibly set according to the requirements of the boost range, while having lower voltage stress on the switch tube and diode.

[0030] The single switch expandable DC-DC converter in the present invention is a non-isolated DC-DC converter. 2 The D network can flexibly control the voltage gain range. Figure 2 This is a schematic diagram of the key waveforms of the single-switch expandable DC-DC converter of the present invention. The main operating waveforms of the DC-DC converter are as follows: Figure 2 As shown. There are two working modes in one switching cycle. Figure 3 This is the equivalent circuit diagram of the working mode 1 of the single-switch expandable DC-DC converter of the present invention. Figure 4 This is the equivalent circuit diagram of the second operating mode of the single-switch expandable DC-DC converter of the present invention.

[0031] Mode I (t0≤t<t1)

[0032] like Figure 3 As shown, in this mode, at t = 0, the control switch S is turned on, and the diode D0-D n is reverse biased; the power supply V in For inductance L in Charge the inductor L in The current increases linearly, and the capacitance C0 and capacitance C 1,1 -C n,1 Through the switch tube S to the inductor L1-L n Capacitor C 1,2 -C n,2 Discharge. The load R consists of capacitor C0, capacitor C 1,2 -C n,2 The series structure of the power supply. The expression of its period is dT S , where d is the duty cycle, T S is the periodic switching time.

[0033] Mode II (t1≤t<t2)

[0034] like Figure 4 As shown, in this mode, the control switch tube S is disconnected and the diode D0-D n is forward biased, the inductor L in 、Inductor L1-L n To capacitor C0 and capacitor C respectively 1,2 -C n,2 Power supply; capacitor C 1,1 -C n,1 Through diode D0-D nWhen charging, all diodes are in forward conduction state. The expression of its period is (1-d)T S , where d is the duty cycle, T S is the periodic switching time.

[0035] To simplify the analysis, based on the single-switch scalable DC-DC converter structure and control process described above, the following analysis assumes ideal conditions and does not consider the effects of losses. Only the two normal modes of the main switch, on and off, are considered in the calculation, ignoring the effects of transients. Applying Kirchhoff's laws to the modal analysis and the volt-second balance principle to the inductor, the DC-DC converter gain expression can be obtained as:

[0036]

[0037] Among them, M n is the DC-DC converter gain, d is the duty cycle, and n is the number of networks. Figure 5 FIG. 4 is a voltage diagram showing the gain of the present invention versus the number of networks n and the duty cycle d.

[0038] From the gain expression of formula (1), it can be seen that the converter is expanded by adding LC 2 The gain range can be increased arbitrarily by adjusting the number of D networks. Figure 5 FIG. 4 is a voltage diagram showing the gain of the present invention versus the number of networks n and the duty cycle d.

[0039] Based on the above example analysis, the voltage stress of the semiconductor device of the converter in the present invention can be deduced as follows:

[0040]

[0041] Among them, V S is the voltage stress of the switch tube S, d is the duty cycle, V O is the output voltage, V D0 is the voltage stress of diode D0, V D1 is the voltage stress of diode D1, V Dn is the diode D n voltage stress.

[0042] It can be seen from formula (2) that no matter how many networks are expanded, the semiconductor device has a lower voltage stress.

[0043] One thing to note is that in the case of Mode I and Mode II, the capacitor C 1,2 (n=1) or capacitance C n,2 There are charging and discharging processes, and the time is the same, so the average current flowing is 0. Assume that the input power is equal to the output power lossless operation (i.e. V in ×ILin =V O ×I O ), from the two-mode Kirchhoff current law, according to the ampere-second balance, the current stress on the semiconductor device can be obtained as:

[0044]

[0045] Among them, i s is the current stress of the switch tube S, I L1 is the average current of inductor L1, I Lin is the inductance L in The average current, d is the duty cycle, I O is the output current, i D0 is the current stress of diode D0, i D1 is the current stress of diode D1, i Dn is the diode D n current stress.

[0046] It can be seen from formula (3) that the semiconductor device also has lower current stress.

[0047] In the case of Mode I and Mode II, the calculation formula of the inductor current ripple is:

[0048]

[0049] Among them, Δi Lin is the inductance L in The current ripple, d is the duty cycle, V in is the input voltage, Δi L1 is the current ripple of inductor L1, Δi Ln is the inductance L n Current ripple, f S is the switching frequency of the switch tube S.

[0050] The topology of this converter can be LC-based according to the needs of the boost range. 2 The number of D networks can be expanded. This topology allows for flexible configuration based on the voltage boost range. It also reduces the voltage stress on the switch and diode.

[0051] The above is a schematic description of the present invention and its embodiments, which is not restrictive. The drawings show only one embodiment of the present invention, and the actual structure is not limited thereto. Therefore, if a person skilled in the art is inspired by this and, without departing from the purpose of the present invention, designs a structure and embodiment similar to this technical solution without inventiveness, they shall fall within the scope of protection of the present invention.

Claims

1. A single-switch scalable DC-DC converter, characterized in that: The DC-DC converter includes a switching tube S ,inductance L in ,power supply V in ,capacitance C 0. Capacitor C 1,1 ,capacitance C 1,2 ,diode D 0. Diode D 1. And inductor L 1; inductance L in One end of the power supply V in The positive electrode is connected to the other end of the switch tube S Drain, diode D 0 anode, and capacitor C 1,1 Anode connection of the switch tube S The source of the power supply V in The negative electrode of the diode D 1's cathode is connected; capacitor C 1,1 The cathode of the diode D 1 anode, and inductor L 1 connection; capacitor C 0 and the anode of the diode D 0 cathode, and load R connected; capacitor C 1,2 The cathode of the inductor is connected to L 1 and load R diode D 1's anode and capacitor C 1,1 cathode, and inductor L 1 is connected, and the cathode is connected to the capacitor C 0 and capacitor C 1,2 The midpoints of The DC-DC converter also includes an extended LC 2 D network, the expanded LC 2 The parallel connection of the D network in the inductor L Both ends of 1; The expanded LC 2 D network includes capacitors C 2,1 ,capacitance C 2,2 ,diode D 2. And inductor L 2. Capacitor C 2,1 Anode and inductance L 1 one end is connected, the cathode is connected to the diode D 2 anodes are connected; capacitor C 2,2 Anode and inductance L 1The other end and the diode D 2 cathodes are connected; inductor L 2. Connect one end of the capacitor C 2,2 cathode, inductor L 2The other end is connected to the diode D 2 anode.

2. The single-switch scalable DC-DC converter according to claim 1, characterized in that: The DC-DC converter includes a plurality of the extended LC 2 D network, multiple extended LC 2 D networks are connected in series with each other.

3. The single-switch scalable DC-DC converter according to claim 2, characterized in that: The nth expanded LC 2 D network includes capacitors C n,1 ,capacitance C n,2 ,diode D n , and inductors L n ; when t 0≤ t < t 1, control switch tube S Conductivity, diode D 0- D n is reverse biased, the power supply V in For inductance L in Charging, the current rises linearly, the capacitor C 0 and capacitor C 1,1 -C n,1 Through the switch tube S Directional Inductance L 1- L n and capacitors C 1,2 -C n,2 Discharge, the load is made of capacitor C 0. Capacitor C 1,2 - C n,2 The series structure of power supply; when t 1≤ t < t 2, control switch tube S Disconnect, diode D 0- D n is forward biased, the inductor L in ,inductance L 1- L n To the capacitor C 1,2 -C n,2 Power supply, capacitor C 0 and capacitor C 1,1 -C n,1 Through the diode D 0- D n Charge.

4. The single-switch scalable DC-DC converter according to claim 3, characterized in that: The DC-DC converter has a duty cycle of 0< d Within the range of <1 change cycle, the current ripple of all inductors is controlled by setting the inductance value.

5. The single-switch scalable DC-DC converter according to claim 4, characterized in that: The DC-DC converter has a duty cycle of 0< d <1 change cycle range, the switch tube S And all diodes have low voltage stress and current stress.

6. The single-switch scalable DC-DC converter according to claim 2, characterized in that: The gain range of the DC-DC converter is expanded with the LC 2 D increases with the number of networks.

7. The single-switch scalable DC-DC converter according to claim 1, characterized in that: The switch tube S It is MOSFET, IGBT or SIC.

Images