Bidirectional DC voltage converter

Abstract

The present invention relates to a bidirectional DC voltage converter comprising: a plurality of port pairs, each port pair comprising two symmetrical ports for receiving or outputting the same voltage signal; a conversion device including a first conversion circuit disposed between a first port of a respective one of the plurality of port pairs and a first end of the energy storage element, and a second conversion circuit disposed between a second end of the energy storage element and a second port of the respective one of the port pairs; the energy storage element is configured to periodically store and release electric energy in response to on-off of each control switch in the first conversion circuit and the second conversion circuit; and a controller configured to control on-off of each control switch in the first conversion circuit and the second conversion circuit so as to perform step-up or step-down operation on an input voltage from an external input power supply, thereby enabling the bidirectional DC voltage converter to provide an output voltage required by a load.

Description

Technical Field

[0001] This invention relates to the field of power conversion, and more specifically, to a bidirectional DC-DC voltage converter. Background Technology

[0002] With the rapid development of new energy vehicle technology, vehicle power systems are becoming increasingly complex. To meet the power demands of different electronic devices inside the vehicle, the vehicle's power network needs to effectively convert and distribute energy between multiple voltage levels. This conversion not only requires high efficiency and high stability, but also the ability to adapt to various operating conditions and load changes.

[0003] To enable energy conversion between different power networks within a vehicle, multi-port DC-DC converters have become a key component of the vehicle's power system. These converters are responsible for providing different voltage levels to various loads to meet the power requirements of different electronic devices.

[0004] However, as the power management requirements of electronic devices continue to increase, the limitations of existing multi-port DC-DC converters are becoming increasingly apparent. For example, while traditional DC-DC converters can provide stable voltage output, they typically only offer buck conversion and cannot perform boost conversion. This limits their application in diverse scenarios. Furthermore, existing converters lack adequate protection against inductor open-circuit conditions, which can lead to damage to the switching transistor or failure of the entire converter. Summary of the Invention

[0005] The present invention aims to overcome the defects of existing multi-port DC-DC converters and develop a bidirectional DC-DC converter that can simultaneously realize boost and buck functions, eliminate the risk of short circuit on the output side and the overvoltage phenomenon of the switching transistor, and realize bidirectional voltage conversion between any ports.

[0006] Specifically, the present invention proposes a bidirectional DC-DC voltage converter, the bidirectional DC-DC voltage converter comprising:

[0007] Multiple port pairs, each port pair containing two symmetrical ports for receiving or outputting the same voltage signal, the two symmetrical ports being shorted to each other;

[0008] A conversion device for performing a boost or buck operation between at least two asymmetrical ports in a plurality of port pairs, the conversion device comprising a first conversion circuit disposed between a first port of a corresponding port pair in the plurality of port pairs and a first end of an energy storage element, and a second conversion circuit disposed between a second end of the energy storage element and a second port of the corresponding port pair, the first conversion circuit and the second conversion circuit being each composed of a plurality of control switches;

[0009] The energy storage element is configured to periodically store and release electrical energy in response to the on / off states of respective control switches in the first and second conversion circuits; and

[0010] The controller is configured to control the on / off state of each control switch in the first and second conversion circuits to perform a boost or buck operation on the input voltage from an external input power source, thereby enabling the bidirectional DC-DC voltage converter to provide the output voltage required by the load.

[0011] According to an optional embodiment, the controller is further configured to electrically connect the first port of at least one of the plurality of port pairs to a first end of the energy storage element each time, and to electrically connect the second port of at least one additional port pair of the plurality of port pairs to a second end of the energy storage element.

[0012] According to an optional embodiment, a plurality of control switches in the first conversion circuit form a first bridge topology, the first bridge topology including a first lower bridge arm and at least one first upper bridge arm, each first upper bridge arm being connected between a first port of a corresponding port pair in the plurality of port pairs and a first end of an energy storage element, and the first lower bridge arm being connected between the first end of the energy storage element and a ground terminal.

[0013] According to an optional embodiment, the first conversion circuit further includes at least one first capacitor, each first capacitor being disposed between a first port of the respective port pair and a ground terminal.

[0014] According to an optional embodiment, a plurality of control switches in the second conversion circuit form a second bridge topology, the second bridge topology including a second lower bridge arm and at least one second upper bridge arm, each second upper bridge arm being between a second port of a corresponding port pair and a second end of the energy storage element, and the second lower bridge arm being connected between the second end of the energy storage element and a ground terminal.

[0015] According to an optional embodiment, the second conversion circuit further includes at least one second capacitor, each second capacitor being disposed between the second port of the corresponding port pair and the ground terminal.

[0016] According to an optional embodiment, the first lower bridge arm and the second lower bridge arm are each composed of a single switching transistor.

[0017] According to an optional embodiment, the at least one first upper bridge arm and the at least one second upper bridge arm are each composed of a single switch transistor, or are composed of two switch transistors connected in series.

[0018] According to an alternative embodiment, the switching transistor is selected from the group consisting of bipolar transistors, field-effect transistors, junction field-effect transistors, and insulated-gate bipolar transistors.

[0019] According to an alternative embodiment, the two switching transistors are formed as field-effect transistors, and the sources of the two field-effect transistors are interconnected.

[0020] The novel single-inductor multi-port DC-DC converter of this invention has the following advantages: First, it realizes the boost function of a multi-port DC-DC converter, allowing the output voltage to be higher than the input voltage. Second, by adopting a new topology and control strategy, it eliminates the risk of short circuit on the output side and the overvoltage phenomenon when the inductor is open. Furthermore, this invention can achieve bidirectional switching between any two or more ports, increasing the converter's flexibility and applicability. Finally, since switching operating states in continuous mode does not require changing the direction of the inductor current, it improves the flexibility of output voltage control and the converter's response speed. Attached Figure Description

[0021] By incorporating the figures in this article and subsequently the appendix Figure 1 The specific embodiments used to illustrate certain principles of the invention will make other features and advantages of the method of the invention clearer or more specifically explained.

[0022] Figure 1 The circuit diagram of a conventional single-inductor multiport DC-DC converter is shown.

[0023] Figure 2 A circuit diagram of a bidirectional DC-DC voltage converter according to an exemplary embodiment of the present invention is shown.

[0024] Figure 3 It shows Figure 2 A schematic diagram of the bidirectional DC-DC voltage converter operating in single-input-multiple-output buck mode.

[0025] Figure 4 It shows Figure 2 A schematic diagram of the bidirectional DC-DC voltage converter operating in single-input-multiple-output boost mode.

[0026] Figure 5 It shows Figure 2 Simulation waveform of the bidirectional DC-DC voltage converter in buck mode. Detailed Implementation

[0027] The bidirectional DC-DC voltage converter according to the present invention will now be described with reference to the accompanying drawings and embodiments. In the following description, numerous specific details are set forth to enable those skilled in the art to gain a more complete understanding of the invention. However, it will be apparent to those skilled in the art that implementation of the invention may not include some of these specific details. Instead, the invention may be conceived to be practiced with any combination of the following features and elements, regardless of whether they relate to different embodiments. Therefore, the following aspects, features, embodiments, and advantages are illustrative only and should not be construed as elements or limitations of the claims.

[0028] In vehicle electrical systems, multi-port DC-DC converters are typically used to supply different voltage levels to loads for energy conversion between different power networks. In the design of multi-port DC-DC converters, single-inductor multi-port converters are favored due to their simple structure and low cost. These converters typically utilize a single inductor as an energy storage element and control the voltage of multiple output ports through multiple switching transistors.

[0029] Figure 1 The circuit diagram of a conventional single-inductor multi-port DC-DC converter is shown. (Example) Figure 1 As shown, the mainstream circuit structure currently uses a half-bridge topology, where switching transistors Q1 and Q2 form the half-bridge on the input side, and multiple switching transistors such as Q3, Q4, and Q5 act as multi-port output voltage control units to achieve different voltage outputs. Each output port is connected to different loads RL1, RL2, and RL3. These switching transistors cooperate to turn on and off to control the energy storage and discharge process of inductor L1.

[0030] Capacitors C1, C2, C3, and C4 are connected in parallel on the input and output sides of the converter to store electrical energy. In this converter circuit structure, the switching transistors Q1 to Q5 are controlled by pulse width modulation (PWM) to control the on and off of the energy storage element—inductor L1—and the time for storing and releasing energy can be controlled, thereby adjusting the output voltage to the desired value.

[0031] However, the topology of this conventional DC-DC converter has certain limitations. First, these solutions typically only achieve buck output and cannot perform boost control, meaning the output voltage cannot exceed the input voltage. Second, if the output switching transistors are MOSFETs, GaN transistors, or IGBTs with reverse diodes, there is a risk of short circuits in multiple outputs. Furthermore, there is a risk of overvoltage in the switching transistors when the inductor is open. Finally, existing converter topologies cannot achieve voltage conversion between any two or more ports, further limiting the converter's application range and flexibility.

[0032] This invention aims to overcome the shortcomings of existing single-inductor multi-port DC-DC converters, specifically including: how to realize the boost function of multi-port DC-DC converters; how to eliminate the risk of short circuit on the output side; how to solve the overvoltage phenomenon of the switching transistor when the inductor is open; and how to realize bidirectional conversion between any two or more ports.

[0033] To address this, this invention develops a bidirectional DC-DC converter capable of simultaneously performing boost and buck functions. Based on a traditional single-inductor multi-port converter, this converter employs a novel topology with N ports symmetrically distributed on both sides of a single inductor, with each symmetrical port pair short-circuited to the others. Depending on the application requirements, some ports on one side can be eliminated. At the port Vn with the highest voltage, a single-transistor control method is used, with a parallel reverse diode of the power device providing clamping functionality, eliminating overvoltage across the power transistor when the inductor is open-circuited. Furthermore, when the inductor current is in continuous mode, multi-port state switching can be achieved without changing the inductor current direction, improving the converter's response speed.

[0034] Figure 2 A circuit diagram of a bidirectional DC-DC voltage converter according to an exemplary embodiment of the present invention is shown. This bidirectional DC-DC voltage converter can efficiently perform boost or buck operations between multiple port pairs to meet the voltage requirements of different loads. The following will refer to... Figure 2 Describe in detail the circuit structure and working principle of the converter.

[0035] like Figure 2 As shown, the bidirectional DC-DC voltage converter includes multiple port pairs V1 to Vn and a conversion device. Each port pair contains two symmetrical ports for receiving or outputting the same voltage signal, and the two symmetrical ports in each port pair are shorted to each other. The conversion device is used to perform boost or buck operations between at least two asymmetrical ports in the multiple port pairs, and includes a first conversion circuit CONV1 and a second conversion circuit CONV2, respectively disposed across the energy storage element (i.e., inductor L). Specifically, CONV1 is disposed between the first port of a corresponding port pair in the multiple port pairs and the first end of the energy storage element L, and CONV2 is disposed between the second end of the energy storage element L and the second port of the corresponding port pair.

[0036] The first conversion circuit CONV1 and the second conversion circuit CONV2 are each composed of multiple control switches Q1 to Qn+1, which form a bridge topology. The multiple control switches in the first conversion circuit form a first bridge topology. The second bridge topology is composed of a first lower bridge arm Q1 and at least one first upper bridge arm. The upper bridge arm includes: an upper bridge arm composed of Q3 and Q4 connected in series; an upper bridge arm composed of Q7 and Q8 connected in series; an upper bridge arm composed of Q11 and Q12 connected in series; and an upper bridge arm composed of Qn.

[0037] The multiple control switches in the second conversion circuit form a second bridge topology, which consists of a second lower bridge arm Q2 and at least one second upper bridge arm. The upper bridge arm includes an upper bridge arm formed by Q5 and Q6 connected in series; an upper bridge arm formed by Q9 and Q10 connected in series; an upper bridge arm formed by Q13 and Q14 connected in series; and an upper bridge arm formed by Qn+1. Each upper bridge arm is connected between the first port of the corresponding port pair and the energy storage element L, while the lower bridge arm is connected between the energy storage element L and the ground terminal.

[0038] In addition, each conversion circuit includes at least one capacitor C1, C2, C3, Cn and C5, C6, C7, Cn+1, which are respectively disposed between the first or second port of the corresponding port pair and the ground terminal.

[0039] In the switching circuits CONV1 and CONV2 here, the lower bridge arms are each composed of a single switching transistor, while the upper bridge arms are each composed of a single switching transistor or two switching transistors connected in series. The switching transistors are selected from a group including bipolar junction transistors (BJTs), field-effect transistors (MOSFETs), junction field-effect transistors (JFETs), and insulated-gate bipolar transistors (IGBTs). Figure 2 In the example, the two switching transistors forming a series circuit are implemented as field-effect transistors, and the sources of the two field-effect transistors are connected to each other.

[0040] To control the switching on and off of each bridge arm in the conversion circuit and the charging and discharging operation of the inductor, the converter may also include a controller. Figure 2 (Not shown in the diagram), which controls the on / off state of each control switch in the first conversion circuit CONV1 and the second conversion circuit CONV2 to perform boost or buck operation on the input voltage from the external input power supply, thereby enabling the bidirectional DC voltage converter to provide the single or multiple output voltages required by the load.

[0041] In specific implementation, the controller electrically connects the first port of at least one of the multiple port pairs to the first terminal of the energy storage element L, and electrically connects the second port of at least one other port pair to the second terminal of the energy storage element L. Specifically, during boost operation, the controller turns on the upper bridge arm switch and turns off the lower bridge arm switch in the first conversion circuit CONV1, allowing the energy storage element L to begin storing energy. Subsequently, the controller switches to the second conversion circuit CONV2, turning on the upper bridge arm switch and turning off the lower bridge arm switch in CONV2, allowing the energy storage element L to release energy, thereby achieving boost output. The buck operation is the opposite: the controller first controls the second conversion circuit CONV2 to store energy, and then switches to the first conversion circuit CONV1 to release energy.

[0042] Through the above embodiments, the bidirectional DC-DC voltage converter of the present invention can flexibly perform boost or buck operations between multiple port pairs to meet the voltage requirements of different loads. The controller precisely regulates the input voltage by controlling the on / off states of each control switch, thereby providing a stable output voltage. This converter has a simple circuit structure, is easy to control, and has good dynamic response performance, making it suitable for applications requiring complex power management systems, such as new energy vehicles.

[0043] Figure 3 It shows Figure 2 A schematic diagram of the bidirectional DC-DC voltage converter operating in single-input-multiple-output buck mode. (See diagram below.) Figure 3 As shown in the diagram, assuming the input is the highest voltage Vn and the output is low voltages V1, V2, and V3, the converter needs to perform a step-down operation. The controller first uses PWM control to turn on the upper bridge arm switch and turn off the lower bridge arm switch in the first conversion circuit CONV1, allowing the energy storage element L to begin storing energy. Subsequently, the controller switches to the second conversion circuit CONV2, causing the upper bridge arm switches in CONV2 to turn on sequentially and the lower bridge arm switches to turn off, releasing energy from the energy storage element L, thus achieving step-down. The output voltage is then output via V1, V2, and V3.

[0044] Figure 4 It shows Figure 2 A schematic diagram of the bidirectional DC-DC voltage converter operating in single-input-multiple-output boost mode. (See diagram below.) Figure 4As shown in the diagram, assuming the input is the lowest voltage V1 and the output is a high voltage V2, V3, Vn, the converter needs to perform a boost operation. The controller also turns on the upper arm switch in the first conversion circuit CONV1 and the lower arm switch in the second conversion circuit CONV2, while the lower arm switch turns off, allowing the energy storage element L to begin storing energy. Subsequently, the controller switches to the upper arm of the second conversion circuit CONV2, causing the upper arm switch in CONV2 to turn on sequentially and the lower arm switch to turn off, releasing energy from the energy storage element L, thus achieving a boost operation. The output voltage is then output via V2, V3, Vn.

[0045] Figure 5 It shows Figure 2 The simulation waveform of the bidirectional DC-DC voltage converter in buck mode is shown. Figure 5 In the waveform diagram, the horizontal axis represents time, and the vertical axis represents the voltage and current values ​​at each port. Let's assume CH3 represents input V3 (e.g., 48V), CH2 represents output V2 (e.g., 24V), CH1 represents another input V1 (e.g., 12V), and CH4 represents the inductor current.

[0046] from Figure 5 As can be seen from the simulation waveform, the bidirectional buck-boost DC voltage converter of the present invention can realize direct bidirectional conversion between any two or more ports. It eliminates the inductor overvoltage phenomenon when the inductor is open and avoids the risk of short circuit between multiple outputs. In continuous mode, switching the working state does not require changing the inductor current in reverse, which improves the flexibility of output voltage control.

[0047] Specifically, the novel single-inductor multi-port DC-DC converter of the present invention has the following advantages: First, it realizes the boost function of a multi-port DC-DC converter, allowing the output voltage to be higher than the input voltage. Second, by adopting a new topology and control strategy, it eliminates the risk of short circuit on the output side and the overvoltage phenomenon when the inductor is open. Furthermore, the present invention can achieve bidirectional conversion between any two or more ports, increasing the converter's flexibility and applicability. Finally, since switching operating states in continuous mode does not require changing the direction of the inductor current, it improves the flexibility of output voltage control and the converter's response speed.

[0048] Those skilled in the art will understand that the steps of the method according to the present invention are not limited to being performed in the order listed above. Furthermore, in this invention, terms such as "comprising" and "including" indicate that, in addition to the steps directly and explicitly stated in the specification and claims, the technical solution of this application does not exclude the presence of other steps not directly or explicitly stated.

[0049] While the present invention has been disclosed above with reference to preferred embodiments, it is not limited thereto. Any modifications and alterations made by those skilled in the art without departing from the spirit and scope of the invention should be included within the scope of protection of the invention. Therefore, the scope of protection of the invention should be determined by the scope defined in the claims.

Claims

1. A bidirectional DC-DC voltage converter, characterized in that, The bidirectional DC-DC voltage converter includes: Multiple port pairs (V1~Vn), each port pair includes two symmetrical ports for receiving or outputting the same voltage signal, the two symmetrical ports being shorted to each other; A conversion device for performing a boost or buck operation between at least two asymmetrical ports in a plurality of port pairs, the conversion device comprising a first conversion circuit (CONV1) disposed between a first port of a corresponding port pair in the plurality of port pairs and a first end of an energy storage element (L), and a second conversion circuit (CONV2) disposed between a second end of the energy storage element (L) and a second port of the corresponding port pair, the first conversion circuit and the second conversion circuit being each composed of a plurality of control switches; The energy storage element (L) is configured to periodically store and release electrical energy in response to the on / off states of respective control switches in the first and second conversion circuits; and The controller is configured to control the on / off state of each control switch in the first and second conversion circuits to perform a boost or buck operation on the input voltage from an external input power source, thereby enabling the bidirectional DC-DC voltage converter to provide the output voltage required by the load.

2. The bidirectional DC-DC voltage converter according to claim 1, characterized in that, The controller is further configured to electrically connect the first port of at least one of the plurality of port pairs to the first terminal of the energy storage element (L) each time, and to electrically connect the second port of at least one additional port pair of the plurality of port pairs to the second terminal of the energy storage element (L).

3. The bidirectional DC-DC voltage converter according to claim 1 or 2, characterized in that, The multiple control switches in the first conversion circuit (CONV1) form a first bridge topology, which includes a first lower bridge arm (Q1) and at least one first upper bridge arm (Q3, Q4; Q7, Q8; Q11, Q12; Qn). Each first upper bridge arm is connected between the first port of a corresponding port pair in the plurality of port pairs and the first end of the energy storage element (L). The first lower bridge arm (Q1) is connected between the first end of the energy storage element (L) and the ground terminal.

4. The bidirectional DC-DC voltage converter according to claim 3, characterized in that, The first conversion circuit (CONV1) further includes at least one first capacitor (C1, C2, C3, Cn), each first capacitor being disposed between the first port of the corresponding port pair and the ground terminal.

5. The bidirectional DC-DC voltage converter according to claim 3, characterized in that, The second control switch in the second conversion circuit (CONV2) forms a second bridge topology, which includes a second lower bridge arm (Q2) and at least one second upper bridge arm (Q5, Q6; Q9, Q10; Q13, Q14; Qn+1). Each second upper bridge arm is between the second port of the corresponding port pair and the second end of the energy storage element (L). The second lower bridge arm (Q2) is connected between the second end of the energy storage element (L) and the ground terminal.

6. The bidirectional DC-DC voltage converter according to claim 5, characterized in that, The second conversion circuit (CONV2) also includes at least one second capacitor (C5, C6, C7, Cn+1), each second capacitor being disposed between the second port of the corresponding port pair and the ground terminal.

7. The bidirectional DC-DC voltage converter according to claim 5, characterized in that, The first lower bridge arm (Q1) and the second lower bridge arm (Q2) are each composed of a single switching transistor.

8. The bidirectional DC-DC voltage converter according to claim 7, characterized in that, The at least one first upper bridge arm and the at least one second upper bridge arm are each composed of a single switch transistor, or are composed of two switch transistors connected in series.

9. The bidirectional DC-DC voltage converter according to claim 7 or 8, characterized in that, The switching transistor is selected from the group including bipolar transistors, field-effect transistors, junction field-effect transistors and insulated-gate bipolar transistors.

10. The bidirectional DC-DC voltage converter according to claim 8, characterized in that, The two switching transistors are formed as field-effect transistors, and the sources of the two field-effect transistors are connected to each other.

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