Bidirectional DC voltage converter

Abstract

The present invention relates to a bidirectional DC voltage converter, comprising: multiple port pairs, each port pair containing two symmetric ports for receiving or outputting the same voltage signal; a conversion apparatus, comprising a first conversion circuit arranged between a first port of a corresponding port pair in the multiple port pairs and a first end of an energy storage element, and a second conversion circuit arranged between a second end of the energy storage element and a second port of the corresponding port pair; the energy storage element, the energy storage element being configured to periodically store and release electrical energy in response to on / off switching of each control switch in the first and second conversion circuits; and a controller, the controller being configured to control the on / off switching of each control switch in the first and second conversion circuits to perform a voltage raising or voltage lowering operation on an input voltage from an external input power supply, so that the bidirectional DC voltage converter provides an output voltage required by a load.

Description

[0001] Bidirectional DC voltage converter

[0002] Technical Field

[0003] The present invention relates to the field of power conversion, and more specifically to a bidirectional DC voltage converter.

[0004] Background Art

[0005] With the rapid development of new energy vehicle technology, vehicle power supply systems are becoming increasingly complex. In order to meet power supply requirements of different electronic devices inside a vehicle, a power supply network inside the vehicle requires effective energy conversion and distribution between multiple voltage levels. This conversion requires not only high efficiency and high stability, but also the ability to adapt to different operating conditions and load variations.

[0006] To achieve energy conversion between different power supply networks inside a vehicle, a multi-port DC-DC converter is a key component in a vehicle power supply system. These converters are responsible for supplying different levels of voltage to various loads to meet the power supply requirements of different electronic devices.

[0007] However, the limitations of existing multi-port DC-DC converters are gradually becoming apparent as power supply management requirements for electronic devices continue to increase. For example, although conventional DC-DC converters can provide a stable voltage output, they typically can only realize a voltage lowering function and are not capable of performing a voltage raising operation. This limits their use in diverse application scenarios. In addition, existing converters have insufficient protection in the event of an inductor open circuit, which may result in damage to a transistor switch or failure of the entire converter.

[0008] Summary of the Invention An objective of the present invention is to overcome the flaws in the existing multi-port DC-DC converter, develop a bidirectional DC voltage converter that is capable of simultaneously realizing voltage raising and voltage lowering functions, eliminates the risk of short circuit on the output side and transistor switch overvoltage, and enables bidirectional voltage conversion between any ports.

[0009] Specifically, the present invention proposes a bidirectional DC voltage converter, the bidirectional DC voltage converter comprising:

[0010] multiple port pairs, each port pair containing two symmetric ports for receiving or outputting the same voltage signal, the two symmetric ports being shorted to each other;

[0011] a conversion apparatus for performing a voltage raising or voltage lowering operation between at least two asymmetric ports in the multiple port pairs, the conversion apparatus comprising a first conversion circuit arranged between a first port of a corresponding port pair in the multiple port pairs and a first end of an energy storage element, and a second conversion circuit arranged 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 formed by multiple control switches, respectively;

[0012] the energy storage element, the energy storage element being configured to periodically store and discharge electrical energy in response to on / off switching of each control switch in the first and second conversion circuits; and

[0013] a controller, the controller being configured to control the on / off switching of each control switch in the first and second conversion circuits to perform a voltage raising or voltage lowering operation on an input voltage from an external input power supply, so that the bidirectional DC voltage converter provides an output voltage required by a load.

[0014] According to an optional embodiment, the controller is further configured to, each time, electrically connect a first port of at least one of the multiple port pairs to a first end of an energy storage element, and electrically connect a second port of at least another one of the multiple port pairs to a second end of the energy storage element. According to an optional embodiment, multiple control switches in the first conversion circuit form a first bridge topology, the first bridge topology comprising 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 multiple port pairs and the first end of the energy storage element, and the first lower bridge arm being connected between the first end of the energy storage element and a ground.

[0015] According to an optional embodiment, the first conversion circuit further comprises at least one first capacitator, and each first capacitor is arranged between the first port of the corresponding port pair and the ground.

[0016] According to an optional embodiment, multiple control switches in the second conversion circuit form a second bridge topology, the second bridge topology comprising a second lower bridge arm and at least one second upper bridge arm, each second upper bridge arm being connected between a second port of the corresponding port pair and the 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 the ground.

[0017] According to an optional embodiment, the second conversion circuit further comprises at least one second capacitator, and each second capacitor is arranged between the second port of the corresponding port pair and the ground.

[0018] According to an optional embodiment, the first lower bridge arm and the second lower bridge arm are formed by a single transistor switch, respectively.

[0019] According to an optional embodiment, the at least one first upper bridge arm and the at least one second upper bridge arm are respectively formed by a single transistor switch, or by two transistor switches connected in series.

[0020] According to an optional embodiment, the transistor switch is selected from a group comprising a bipolar transistor, a field-effect transistor, a junction field-effect transistor and an insulated-gate bipolar transistor. According to an optional embodiment, the two transistor switches form field-effect transistors, and source electrodes of this two field-effect transistors are connected to each other.

[0021] The new single-inductor multi-port DC-DC converter of the present invention has the following advantages: first, it realizes a voltage raising function of a multi-port DC-DC converter, so that the output voltage can be higher than the input voltage. Second, the risk of short circuit on the output side and overvoltage when the inductor is open-circuited are eliminated by using a new topology and control strategy. In addition, the present invention enables bidirectional switching between any two or more ports, increasing the flexibility and applicability of the converter. Finally, the flexibility of output voltage control and the responsive speed of the converter are improved by switching operating states in the continuous mode without needing to change the direction of the inductive current.

[0022] Brief Description of the Drawings

[0023] Through the incorporation of the attached drawings hereof and the following specific embodiments which, together with the drawings, are used to illustrate certain principles of the present invention, other features and advantages of the method of the present invention will become clear or illustrated more specifically.

[0024] Fig. 1 shows a circuit structure diagram of a conventional single-inductor multi-port DC-DC converter.

[0025] Fig. 2 shows a circuit structure diagram of a bidirectional DC voltage converter according to an exemplary embodiment of the present invention.

[0026] Fig. 3 shows an operating schematic diagram of the bidirectional DC voltage converter in Fig. 2 in a single-input multi-output voltage lowering mode.

[0027] Fig. 4 shows an operating schematic diagram of the bidirectional DC voltage converter in Fig. 2 in a single-input multi-output voltage raising mode. Fig. 5 shows a simulated waveform diagram of the bidirectional DC voltage converter in Fig. 2 in a voltage lowering mode.

[0028] Detailed Description of the Invention

[0029] The bidirectional DC voltage converter according to the present invention is described below through embodiments with reference to the drawings. Many specific details are expounded in the description below, to give those skilled in the art a more comprehensive understanding of the present invention. However, it will be obvious to those skilled in the art that the invention can be realized without some of these specific details. On the contrary, one may consider using any combination of the features and key elements below to implement the present invention, regardless of whether they relate to different embodiments. Therefore, the various aspects, features, embodiments and advantages below merely serve an illustrative purpose, and should not be regarded as key elements or definitions of the claims.

[0030] In a vehicle electrical system, for energy conversion between different power supply networks, a multi-port DC-DC converter is usually provided in the vehicle to supply different levels of voltage to a load. In the design of multi-port DC-DC converters, a single-inductor multi-port converter is favored for its structural simplicity and low cost. This converter typically uses a single inductor as an energy storage element and controls voltage across multiple output ports through multiple transistor switches.

[0031] Fig. 1 shows a circuit structure diagram of a conventional single-inductor multi-port DC-DC converter. As shown in Fig. 1 , current mainstream circuit structures use a half-bridge topology, wherein transistor switches Q1, Q2 form a half-bridge on an input side, and multiple transistor switches, such as Q3, Q4, Q5, act as a multi-port output voltage control unit, to achieve the purpose of different voltage outputs, and each output port is connected to a different load RL1 , RL2, RL3. These transistor switches turn on and off in cooperation with each other, to control the energy storage and discharge process of an inductor L1.

[0032] Capacitors C1 and C2, C3, C4 are connected in parallel to the input and output sides, respectively, of the converter for storing electrical energy. In this conversion circuit structure, switching the transistor switches Q1-Q5 on and off is controlled by pulse width modulation (PWM), which can control the time of energy storage and energy release of an energy storage element - the inductor L1 , thus regulating the output voltage to the desired value.

[0033] However, there are certain limitations to the topology of this conventional DC-DC converter. First, these schemes typically can only achieve a lowered voltage output and are unable to perform voltage raising control, which means that the output voltage cannot be higher than the input voltage. Second, if the output transistor switches are MOSFETs, GaN, or IGBTs with reverse diodes, there is a risk of short circuit in multiple outputs. In addition, there is a risk of overvoltage in the transistor switches when the inductor is open-circuited. Finally, the existing converter topology does not allow for voltage conversion between any two or more ports, further limiting the scope of application and flexibility of the converter.

[0034] An object of the present invention is to overcome flaws in existing single-inductor multi-port DC-DC converters, specifically comprising: how to realize a voltage raising function of a multi-port DC-DC converter; how to eliminate the risk of short circuit on the output side; how to address the transistor switch overvoltage that occurs when the inductor is open-circuited; and how to realize bidirectional conversions between any two or more ports.

[0035] For this purpose, the present invention has developed a bidirectional DC voltage (DC-DC) converter capable of simultaneously realizing voltage raising and voltage lowering functions. The converter is designed with a new topology on the basis of a conventional single-inductor multi-port converter, and has N ports that are symmetrically distributed on two sides of a single inductor, each symmetric pair of ports being shorted to each other. Depending on the application requirements, some ports on one side can be removed. In the highest-voltage port Vn, single-transistor control is used, and a reverse diode connected in parallel to a power device provides a clamping function, eliminating the generation of overvoltage at both ends of the power transistor when the inductor is open-circuited. In addition, when inductive current is in continuous mode, multi-port state switching can be achieved without changing the direction of inductive current, increasing the response speed of the converter.

[0036] Fig. 2 shows a circuit structure diagram of a bidirectional DC voltage converter according to an exemplary embodiment of the present invention. This bidirectional DC voltage converter is able to effectively perform a voltage raising operation or voltage lowering operation between multiple port pairs to meet the voltage requirements of different loads. The circuit structure of the converter and its operating principles are described in detail below with reference to Fig. 2.

[0037] As shown in Fig. 2, this bidirectional DC voltage converter comprises multiple port pairs V1-Vn and a conversion apparatus, wherein each port pair contains two symmetric ports for receiving or outputting the same voltage signal, and the two symmetric ports in each pair are shorted to each other. The conversion apparatus is used to perform a voltage raising or voltage lowering operation between at least two asymmetric ports in the multiple port pairs, and comprises a first conversion circuit C0NV1 and a second conversion circuit C0NV2, which are respectively arranged at two ends of an energy storage element (i.e. an inductor L). Specifically, C0NV1 is arranged between a first port of a corresponding port pair in the multiple port pairs and a first end of the energy storage element L, and C0NV2 is arranged between a second end of the energy storage element L and a second port of the corresponding port pair.

[0038] The first conversion circuit C0NV1 and the second conversion circuit C0NV2 are formed by multiple control switches Q1-Qn+1, respectively, and these control switches form a bridge topology. Multiple control switches in the first conversion circuit form a first bridge topology, and this second bridge topology is formed by a first lower bridge arm Q1 and at least one first upper bridge arm, this upper bridge arm comprising: an upper bridge arm formed by Q3, Q4 connected in series; an upper bridge arm formed by Q7, Q8 connected in series; an upper bridge arm formed by Q11, Q12 connected in series; and an upper bridge arm formed by Qn.

[0039] Multiple control switches in the second conversion circuit form a second bridge topology, and this second bridge topology is formed by a second lower bridge arm Q2 and at least one second upper bridge arm, this upper bridge arm comprising: an upper bridge arm formed by Q5, Q6 connected in series; an upper bridge arm formed by Q9, Q10 connected in series; an upper bridge arm formed by Q13, 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, whereas the lower bridge arm is connected between the energy storage element L and the ground.

[0040] In addition, each conversion circuit further comprises at least one capacitor C1 , C2, C3, Cn and C5, C6, C7, Cn+1; these capacitors are respectively arranged between the first or second port of the corresponding port pair and the ground.

[0041] The lower bridge arms in the conversion circuits C0NV1 and C0NV2 are respectively formed by a single transistor switch, and the upper bridge arms are respectively formed by a single transistor switch or two transistor switches connected in series. The transistor switch is selected from a group comprising a bipolar transistor BJT, a field-effect transistor MOSFET, a junction field-effect transistor JEFT and an insulated-gate bipolar transistor IGBT. In the example in Fig.

[0042] 2, two transistor switches that form a series circuit are implemented as field-effect transistors, and source electrodes of these two field-effect transistors are connected to each other.

[0043] In order to control on / off switching of each bridge arm in the conversion circuit and a charge / discharge operation of the inductor, the converter may further comprise a controller (not shown in Fig. 2) that controls the on / off switching of each control switch in the first conversion circuit C0NV1 and the second conversion circuit C0NV2, to perform a voltage raising or voltage lowering operation on an input voltage from an external input power supply, which allows the bidirectional DC voltage converter to provide a single or multiple output voltages required by a load.

[0044] In a particular embodiment, a controller is further configured to, each time, electrically connect a first port of at least one of the multiple port pairs to a first end of an energy storage element L, and electrically connect a second port of at least another one of the multiple port pairs to a second end of the energy storage element L. Specifically, when a voltage raising operation is performed, the controller switches on an upper bridge arm switch in the first conversion circuit CONV1 , and switches off a lower bridge arm switch, and the energy storage element L starts to store energy. The controller then switches to the second conversion circuit C0NV2, and switches on an upper bridge arm switch in the second conversion circuit CONV2, and switches off a lower bridge arm switch, and the energy storage element L releases energy, thus achieving a raised voltage output. A voltage lowering operation is the reverse; the controller first controls the second conversion circuit C0NV2 to store energy, and then switches to the first conversion circuit C0NV1 to release energy.

[0045] By means of the above embodiment, the bidirectional DC voltage converter of the present invention is able to flexibly perform a voltage raising operation or voltage lowering operation between multiple port pairs to meet the voltage requirements of different loads. The controller precisely regulates the input voltage by precisely controlling the switching on / off of each control switch, thus providing a stable output voltage. The converter has a simple circuit structure, is easy to control, has a good dynamic response performance, and is suitable for scenarios requiring complex power supply management systems such as new energy vehicles.

[0046] Fig. 3 shows an operating schematic diagram of the bidirectional DC voltage converter in Fig. 2 in a single-input multi-output voltage lowering mode. As shown in Fig. 3, with the input as the highest voltage Vn and the output as a low voltage V1 , V2, V3, here the converter needs to perform a voltage lowering operation. By means of PWM control, the controller first switches on an upper bridge arm switch in the first conversion circuit C0NV1 , and switches off a lower bridge arm switch, and the energy storage element L starts to store energy. The controller then switches to the second conversion circuit C0NV2, and sequentially switches on upper bridge arm switches in the second conversion circuit C0NV2, and switches off a lower bridge arm switch, and the energy storage element L releases energy, thus achieving a lowered voltage, and the output voltage is output through V1, V2, V3.

[0047] Fig. 4 shows an operating schematic diagram of the bidirectional DC voltage converter in Fig. 2 in a single-input multi-output voltage raising mode. As shown in Fig. 4, with the input as the lowest voltage V1 and the output as a high voltage V2, V3, Vn, here the converter needs to perform a voltage raising operation. The controller likewise switches on an upper bridge arm switch in the first conversion circuit CONV1 and switches on a lower bridge arm switch in the second conversion circuit CONV2, and switches off a lower bridge arm switch, and the energy storage element L starts to store energy. The controller then switches to the second conversion circuit CONV2 upper bridge arm, and sequentially switches on upper bridge arm switches in the second conversion circuit CONV2, and switches off a lower bridge arm switch, and the energy storage element L releases energy, thus achieving a raised voltage, and the output voltage is output through V2, V3, Vn.

[0048] Fig. 5 shows a simulated waveform diagram of the bidirectional DC voltage converter in Fig. 2 in a voltage lowering mode. In Fig. 5, the horizontal axis of the waveform diagram represents time, and the vertical axis represents the voltage and current values of respective ports. CH3 represents input V3 (which is 48 V for example), CH2 represents output V2 (which is 24 V for example), CH1 represents another input V1 (which is 12 V for example), and CH4 represents inductive current.

[0049] As can be seen from the simulated waveform diagram in Fig. 5, the bidirectional voltage raising and lowering DC voltage converter of the present invention enables direct bidirectional conversions of any two or more ports, which eliminates inductive overvoltage when the inductor is open-circuited, and avoids the risk of short circuit between multiple outputs, and the operating state is switched in a continuous mode without needing to change the inductive current to reverse, increasing the flexibility of output voltage control.

[0050] Specifically, the new single-inductor multi-port DC-DC converter of the present invention has the following advantages: first, it realizes a voltage raising function of a multi-port DC-DC converter, so that the output voltage can be higher than the input voltage. Second, the risk of short circuit on the output side and overvoltage when the inductor is open-circuited are eliminated by using a new topology and control strategy. In addition, the present invention enables bidirectional conversions between any two or more ports, increasing the flexibility and applicability of the converter. Finally, the flexibility of output voltage control and the responsive speed of the converter are improved by switching operating states in the continuous mode without needing to change the direction of the inductive current.

[0051] Those skilled in the art will understand that the steps of the method according to the invention are not limited to execution in the sequence set out above. In addition, in the present invention, terms such as "include" and "comprise" mean that besides having steps that are directly and explicitly stated in the description and claims, the technical solution of the present application does not rule out having other steps which are not directly or explicitly stated.

[0052] Although the present invention has been disclosed above with preferred embodiments, the present invention is not limited to this. Various changes and modifications made by a person skilled in the art without departing from the spirit and scope of the present invention should be included in the scope of protection thereof. Thus, the scope of protection of the present invention shall be the scope defined by the claims.

Claims

Claims1. A bidirectional DC voltage converter, wherein the bidirectional DC voltage converter comprises:multiple port pairs (V1-Vn), each port pair containing two symmetric ports for receiving or outputting the same voltage signal, the two symmetric ports being shorted to each other;a conversion apparatus for performing a voltage raising or voltage lowering operation between at least two asymmetric ports in the multiple port pairs, the conversion apparatus comprising a first conversion circuit (C0NV1) arranged between a first port of a corresponding port pair in the multiple port pairs and a first end of an energy storage element (L), and a second conversion circuit (C0NV2) arranged 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 formed by multiple control switches, respectively;the energy storage element (L), the energy storage element being configured to periodically store and release electrical energy in response to on / off switching of each control switch in the first and second conversion circuits; anda controller, the controller being configured to control the on / off switching of each control switch in the first and second conversion circuits to perform a voltage raising or voltage lowering operation on an input voltage from an external input power supply, so that the bidirectional DC voltage converter provides an output voltage required by a load.

2. A bidirectional DC voltage converter as claimed in claim 1, wherein the controller is further configured to, each time, electrically connect a first port of at least one of the multiple port pairs to the first end of the energy storage element (L), and electrically connect a second port of at least another one of the multiple port pairs to the second end of the energy storage element (L).

3. The bidirectional DC voltage converter as claimed in claim 1 or 2, wherein multiple control switches in the first conversion circuit (C0NV1) form a first bridgetopology, the first bridge topology comprising 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 being connected between a first port of a corresponding port pair in the multiple port pairs and the first end of the energy storage element (L), and the first lower bridge arm (Q1) being connected between the first end of the energy storage element (L) and a ground.

4. The bidirectional DC voltage converter as claimed in claim 3, wherein the first conversion circuit (C0NV1) further comprises at least one first capacitator (C1 , C2, C3, Cn), and each first capacitor is arranged between the first port of the corresponding port pair and the ground.

5. The bidirectional DC voltage converter as claimed in claim 3, wherein multiple control switches in the second conversion circuit (C0NV2) form a second bridge topology, the second bridge topology comprising 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 being connected between a second port of the corresponding port pair and the second end of the energy storage element (L), and the second lower bridge arm (Q2) being connected between the second end of the energy storage element (L) and the ground.

6. The bidirectional DC voltage converter as claimed in claim 5, wherein the second conversion circuit (C0NV2) further comprises at least one second capacitator (C5, C6, C7, Cn+1 ), and each second capacitor is arranged between the second port of the corresponding port pair and the ground.

7. The bidirectional DC voltage converter as claimed in claim 5, wherein the first lower bridge arm (Q1 ) and the second lower bridge arm (Q2) are formed by a single transistor switch, respectively.

8. The bidirectional DC voltage converter as claimed in claim 7, wherein the at least one first upper bridge arm and the at least one second upper bridge arm are respectively formed by a single transistor switch, or by two transistor switchesconnected in series.

9. The bidirectional DC voltage converter as claimed in claim 7 or 8, wherein the transistor switch is selected from a group comprising a bipolar transistor, a field-effect transistor, a junction field-effect transistor and an insulated-gate bipolar transistor.

10. The bidirectional DC voltage converter as claimed in claim 8, wherein the two transistor switches form field-effect transistors, and source electrodes of this two field-effect transistors are connected to each other.

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