A charging circuit, a charging control method and a bidirectional DC / DC converter

Abstract

The present invention discloses a charging circuit, a charging control method, and a bidirectional DC / DC converter. The charging circuit is applied to a bidirectional DC / DC converter and includes: a charging module, a first end of which is connected to the positive electrode of a first bus capacitor on the first side of the bidirectional DC / DC converter, a second end of which is connected to the positive electrode of a second bus capacitor on the second side of the bidirectional DC / DC converter, and a third end of which is connected to the positive terminal of the DC bus on the second side of the bidirectional DC / DC converter; the charging module is used to charge the first bus capacitor and the second bus capacitor. The present invention enables bidirectional soft starting of a bidirectional DC / DC converter, solving the problem that bidirectional DC / DC converters cannot complete soft starting when there is no power on the low-voltage side.

Description

Technical Field

[0001] The present invention relates to the field of electronic power technology, and in particular to a charging circuit, a charging control method, and a bidirectional DC / DC converter. Background Art

[0002] Before the bidirectional DC / DC converter is powered on, a charging circuit is required to charge the bus capacitor to prevent voltage surges from damaging power devices. The bidirectional DC / DC converter consists of a high-voltage side and a low-voltage side, both of which are equipped with bus capacitors. Figure 1 The structure diagram of the charging circuit of the existing bidirectional DC / DC converter is as follows: Figure 1 As shown in the figure, due to the directional constraints of the diodes in the inverter of a bidirectional DC / DC converter, current can only flow from the low-voltage side to the high-voltage side. Therefore, the high-voltage side cannot charge the bus capacitors on both ends. A charging circuit is generally connected in parallel across the main circuit breaker on the low-voltage side. Before the main circuit breaker is opened, the charging circuit is activated to charge the bus capacitors on both sides. Due to the limitations of this charging circuit structure, soft starting can only be completed from the low-voltage side. If there is no power on the low-voltage side, soft starting cannot be completed.

[0003] With respect to the problem in the prior art that a bidirectional DC / DC converter cannot complete soft start when there is no power on the low-voltage side, no effective solution has been proposed. Summary of the Invention

[0004] Embodiments of the present invention provide a charging circuit, a charging control method, and a bidirectional DC / DC converter to solve the problem in the prior art that the bidirectional DC / DC converter cannot complete soft start when there is no power on the low-voltage side.

[0005] To solve the above technical problems, the present invention provides a charging circuit applied to a bidirectional DC / DC converter, the charging circuit comprising:

[0006] a charging module, a first end of which is connected to the positive electrode of the first bus capacitor on the first side of the bidirectional DC / DC converter, a second end of which is connected to the positive electrode of the second bus capacitor on the second side of the bidirectional DC / DC converter, and a third end of which is connected to the positive terminal of the DC bus on the second side of the bidirectional DC / DC converter;

[0007] The charging module is used to charge the first bus capacitor and the second bus capacitor.

[0008] Furthermore, the charging module includes:

[0009] a first switch, a first end of which is connected to the positive electrode of the first bus capacitor, and a second end of which is connected to the first end of the charging resistor;

[0010] The charging resistor has a second end connected to the positive electrode of the second bus capacitor;

[0011] A second switch has a first end connected between the first switch and the charging resistor, and a second end connected to the positive terminal of the DC bus on the second side of the bidirectional DC / DC converter.

[0012] Furthermore, the first side of the bidirectional DC / DC converter is a high-voltage side, and the second side of the bidirectional DC / DC converter is a low-voltage side.

[0013] The present invention also provides a bidirectional DC / DC converter, comprising the above charging circuit.

[0014] The present invention also provides a charging control method applied to a bidirectional DC / DC converter, the method comprising:

[0015] detecting a power-on state of a first side and a second side of the bidirectional DC / DC converter;

[0016] Controlling a charging module to charge a first bus capacitor on the first side of the bidirectional DC / DC converter and a second bus capacitor on the second side of the bidirectional DC / DC converter according to power-on states of the first side and the second side of the bidirectional DC / DC converter;

[0017] The first end of the charging module is connected to the positive electrode of the first bus capacitor, the second end is connected to the positive electrode of the second bus capacitor, and the third end is connected to the positive terminal of the DC bus on the second side of the bidirectional DC / DC converter.

[0018] Furthermore, controlling a charging module to charge a first bus capacitor on the first side of the bidirectional DC / DC converter and a second bus capacitor on the second side of the bidirectional DC / DC converter according to power-on states of the first side and the second side of the bidirectional DC / DC converter includes:

[0019] If the power-on state of the first side of the bidirectional DC / DC converter is energized and the power-on state of the second side of the bidirectional DC / DC converter is not energized, controlling the charging module to charge the first bus capacitor and the second bus capacitor simultaneously from the first side;

[0020] If the power-on state of the second side of the bidirectional DC / DC converter is energized and the power-on state of the first side of the bidirectional DC / DC converter is not energized, control the charging module to charge the first bus capacitor and the second bus capacitor simultaneously from the second side.

[0021] Furthermore, controlling the charging module to charge the first bus capacitor and the second bus capacitor simultaneously from the first side includes:

[0022] controlling a first switch in the charging module to be turned on, and controlling a second switch in the charging module to be turned off;

[0023] The first end of the first switch is connected to the positive electrode of the first bus capacitor, and the second end thereof is connected to the first end of the charging resistor; the second end of the charging resistor is connected to the positive electrode of the second bus capacitor; the first end of the second switch is connected between the first switch and the charging resistor, and the second end is connected to the positive terminal of the DC bus on the second side of the bidirectional DC / DC converter.

[0024] Furthermore, controlling the charging module to charge the first bus capacitor and the second bus capacitor simultaneously from the second side includes:

[0025] The first switch in the charging module is controlled to be disconnected, and the second switch in the charging module is controlled to be connected.

[0026] Furthermore, controlling the charging module to charge the first bus capacitor on the first side of the bidirectional DC / DC converter and the second bus capacitor on the second side of the bidirectional DC / DC converter according to the power-on states of the first side and the second side of the bidirectional DC / DC converter further includes:

[0027] If the power-on state of the first side of the bidirectional DC / DC converter is energized and the power-on state of the second side of the bidirectional DC / DC converter is also energized, the charging module is controlled to charge the first bus capacitor and the second bus capacitor simultaneously from the low-voltage side.

[0028] The present invention also provides a computer-readable storage medium having a computer program stored thereon, wherein the program implements the above-mentioned charging control method when executed by a processor.

[0029] By applying the technical solution of the present invention, a charging module is provided, which is respectively connected to the high-voltage side, the low-voltage side, and the positive terminal of the DC bus on the low-voltage side of the bidirectional DC / DC converter. Through the above-mentioned charging module, the high-voltage side and the low-voltage side of the bidirectional DC / DC converter are charged, and bidirectional soft starting of the bidirectional DC / DC converter is achieved, thereby solving the problem that the current bidirectional DC / DC converter cannot complete soft starting when there is no power on the low-voltage side. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 A structural diagram of a charging circuit of an existing bidirectional DC / DC converter;

[0031] Figure 2 is a diagram showing the connection relationship between a charging circuit and a bidirectional DC / DC converter according to an embodiment of the present invention;

[0032] Figure 3FIG. 4 is a flow chart of a charging control method according to an embodiment of the present invention. DETAILED DESCRIPTION

[0033] To make the objectives, technical solutions, and advantages of the present invention more apparent, the present invention will be further described in detail below with reference to the accompanying drawings. It is apparent that the embodiments described are only some, not all, of the present invention. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without creative effort are intended to fall within the scope of protection of the present invention.

[0034] The terms used in the embodiments of the present invention are for the purpose of describing specific embodiments only and are not intended to limit the present invention. The singular forms "a," "an," "the," and "the" used in the embodiments of the present invention and the appended claims are also intended to include plural forms, and unless the context clearly indicates otherwise, "a plurality" generally includes at least two.

[0035] It should be understood that the term "and" as used herein simply describes an association between related objects, indicating that three possible relationships exist. For example, A and B can represent: A exists alone, A and B exist simultaneously, and B exists alone. Furthermore, the character " / " in this document generally indicates that the related objects are in an "or" relationship.

[0036] It should be understood that although the terms "first," "second," etc. may be used to describe switches in embodiments of the present invention, these switches should not be limited to these terms. These terms are merely used to distinguish switches disposed in different locations. For example, a first switch could also be referred to as a second switch, and similarly, a second switch could also be referred to as a first switch without departing from the scope of the present invention.

[0037] As used herein, the words "if" and "if" may be interpreted as "at the time of" or "when" or "in response to determining" or "in response to detecting," depending on the context. Similarly, the phrases "if it is determined" or "if (stated condition or event) is detected" may be interpreted as "when it is determined" or "in response to the determination" or "when detecting (stated condition or event)" or "in response to detecting (stated condition or event)," depending on the context.

[0038] It should also be noted that the terms "include," "comprises," or any other variations thereof are intended to encompass non-exclusive inclusion, such that a product or device comprising a series of elements includes not only those elements but also other elements not explicitly listed, or elements inherent to such product or device. In the absence of further limitations, an element defined by the phrase "comprises a..." does not exclude the presence of other identical elements in the product or device comprising the element.

[0039] The optional embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0040] Example 1

[0041] This embodiment provides a charging circuit for use in a bidirectional DC / DC converter. Figure 2 FIG. 1 is a diagram showing the connection relationship between a charging circuit and a bidirectional DC / DC converter according to an embodiment of the present invention. Figure 2 As shown, the bidirectional DC / DC converter includes a first side and a second side, wherein the first side is a high-voltage side and the second side is a low-voltage side, wherein the high-voltage side and the low-voltage side are opposite to each other, and when electric energy is transferred from the low-voltage side to the high-voltage side, the voltage increases, and when electric energy is transferred from the high-voltage side to the low-voltage side, the voltage decreases. The above-mentioned bidirectional DC / DC converter is a three-phase parallel interleaved bidirectional DC / DC converter, wherein the high-voltage side includes a DC bus, and the DC bus includes a positive terminal and a negative terminal. A first bus capacitor C1 is provided between the positive terminal and the negative terminal of the DC bus on the high-voltage side. An inverter circuit is also connected between the positive terminal and the negative terminal of the DC bus on the high-voltage side. The inverter circuit includes a three-phase parallel inverter bridge, each inverter bridge includes two IGBT power switches connected in series, and each IGBT power switch includes a switch tube (i.e., VS1~VS6) and a freewheeling diode (i.e., VD1~VD6) connected in reverse parallel thereto. The above-mentioned bidirectional DC / DC converter also includes a first inductor L1, a second inductor L2, and a second inductor L3. 2 and a third inductor L3. The first end of the first inductor L1 is connected between the two IGBT power switches in the first-phase inverter bridge, the first end of the second inductor L2 is connected between the two IGBT power switches in the second-phase inverter bridge, and the first end of the third inductor L3 is connected between the two IGBT power switches in the third-phase inverter bridge. The second end of the first inductor L1, the second end of the second inductor L2, and the second end of the third inductor L3 are connected to the positive terminal of the DC bus on the low-voltage side of the bidirectional DC / DC converter after intersection. The DC bus on the low-voltage side of the bidirectional DC / DC converter includes a positive terminal and a negative terminal. A second bus capacitor C2 is provided between the positive terminal and the negative terminal of the DC bus on the low-voltage side.

[0042] A first breaker QF1 is provided on the DC busbar on the high-voltage side of the bidirectional DC / DC converter, and a second breaker QF2 is provided on the DC busbar on the low-voltage side of the bidirectional DC / DC converter.

[0043] The charging circuit includes: a charging module 10, a first end of which is connected to the positive electrode of a first bus capacitor C1 on the high-voltage side of the bidirectional DC / DC converter, a second end of which is connected to the positive electrode of a second bus capacitor C2 on the low-voltage side of the bidirectional DC / DC converter, and a third end of which is connected to the positive terminal of the DC bus on the low-voltage side of the bidirectional DC / DC converter. The charging module 10 is configured to control the charging module to simultaneously charge the first bus capacitor C1 and the second bus capacitor C2 from the first side when the first side of the bidirectional DC / DC converter is powered and the second side of the bidirectional DC / DC converter is not powered; control the charging module to charge the first bus capacitor C1 and the second bus capacitor C2 from the second side when the second side of the bidirectional DC / DC converter is powered and the first side of the bidirectional DC / DC converter is not powered; and control the charging module to simultaneously charge the first bus capacitor C1 and the second bus capacitor C2 from the low-voltage side when the first side of the bidirectional DC / DC converter is powered and the second side of the bidirectional DC / DC converter is also powered.

[0044] The charging circuit of this embodiment is provided with a charging module that is respectively connected to the high-voltage side, the low-voltage side, and the positive terminal of the DC bus on the low-voltage side of the bidirectional DC / DC converter. Through the charging module, the high-voltage side and the low-voltage side of the bidirectional DC / DC converter are charged, thereby achieving bidirectional soft starting of the bidirectional DC / DC converter. This solves the problem that the bidirectional DC / DC converter cannot complete soft starting when there is no power on the low-voltage side.

[0045] Example 2

[0046] This embodiment provides another charging circuit, such as Figure 2 As shown, in order to realize powering the first bus capacitor and the second bus capacitor separately or simultaneously, the charging module includes: a first switch S1, a first end of which is connected to the positive electrode of the first bus capacitor, and a second end of which is connected to the first end of the charging resistor R; the charging resistor R, a second end of which is connected to the positive electrode of the second bus capacitor C2; a second switch S2, a first end of which is connected between the first switch S1 and the charging resistor R, and a second end of which is connected to the positive terminal of the DC bus on the second side of the bidirectional DC / DC converter.

[0047] In this embodiment, the T-shaped circuit consisting of the first switch S1, the charging resistor R, and the second switch S2 is the charging module. The front end of the first switch S1 in the charging module is connected to the front end of the first circuit breaker QF1, the front end of the second switch S2 is connected to the front end of the second circuit breaker QF2, and the rear ends of the first and second switches S1 and S2 are both connected to the front end of the charging resistor R, which is then connected to the rear end of the second circuit breaker QF2. This is used to pre-charge the first and second bus capacitors C1 and C2 before power is applied. The startup control process is as follows: a three-phase staggered parallel DC / DC bidirectional converter is connected to the system. When the voltage sensor detects that there is power at the front end of the first circuit breaker QF1 and there is no power at the front end of the second circuit breaker QF2, it indicates that it is necessary to start from the high-voltage side. The first switch S1 is controlled to be closed, and the first bus capacitor C1 and the second bus capacitor C2 are charged simultaneously from the high-voltage side. When charging is completed, the tube is opened first, and then the first circuit breaker QF1 and the second circuit breaker QF2 are opened to complete the system soft-start from the high-voltage side. When the voltage sensor detects that there is no power at the front end of the first circuit breaker QF1 and there is power at the front end of the second circuit breaker QF2, it indicates that it is necessary to start from the low-voltage side. The second switch S2 is controlled to be closed, and the first bus capacitor C1 and the second bus capacitor C2 are charged simultaneously from the low-voltage side. When charging is completed, the tube is opened first, and then the first circuit breaker QF1 and the second circuit breaker QF2 are opened to complete the system soft-start from the low-voltage side. When the voltage sensor detects that both the first circuit breaker QF1 and the second circuit breaker QF2 have voltage, they are also started according to the low-voltage side soft start mode. The charging process designed according to this invention covers the bus capacitor pre-charging of all starting modes of the bidirectional DC / DC bidirectional converter.

[0048] Example 3

[0049] This embodiment provides a bidirectional DC / DC converter, including the charging circuit of the above embodiment, for implementing bidirectional soft starting of the bidirectional DC / DC converter, thereby solving the problem that the current bidirectional DC / DC converter cannot complete soft starting when there is no power on the low-voltage side.

[0050] Example 4

[0051] This embodiment provides a charging control method, which is applied to the above-mentioned bidirectional DC / DC converter. Figure 3 FIG. 1 is a flow chart of a charging control method according to an embodiment of the present invention. Figure 3 As shown, the method includes:

[0052] S101 , detecting power-on states of a first side and a second side of a bidirectional DC / DC converter.

[0053] Among them, the first side is the high-voltage side and the second side is the low-voltage side. In a specific implementation, the voltage at the front end of the first circuit breaker QF1 and the second circuit breaker QF2 can be detected by a voltage sensor to determine the power-on status of the high-voltage side and the low-voltage side of the bidirectional DC / DC converter.

[0054] S102 : Control a charging module to charge a first bus capacitor on the first side and a second bus capacitor on the second side of the bidirectional DC / DC converter according to power-on states of the first side and the second side of the bidirectional DC / DC converter.

[0055] The first end of the charging module is connected to the positive electrode of the first bus capacitor, the second end is connected to the positive electrode of the second bus capacitor, and the third end is connected to the positive terminal of the DC bus on the second side of the bidirectional DC / DC converter.

[0056] The charging control method of this embodiment controls a charging module to charge a first bus capacitor on the first side and a second bus capacitor on the second side of the bidirectional DC / DC converter based on the power-on status of the first side and the second side of the bidirectional DC / DC converter. This method can achieve bidirectional soft-start of the bidirectional DC / DC converter, solving the problem that the bidirectional DC / DC converter cannot complete soft-start when there is no power on the low-voltage side.

[0057] Example 5

[0058] This embodiment provides another charging control method. In order to adjust the conduction state of internal components of a charging module according to the power supply status of the high-voltage side and the low-voltage side of a bidirectional DC / DC converter to complete charging, the above-mentioned step S102 includes: if the power supply status of the first side of the bidirectional DC / DC converter is energized and the power supply status of the second side of the bidirectional DC / DC converter is not energized, controlling the charging module to simultaneously charge the first bus capacitor and the second bus capacitor from the first side; if the power supply status of the second side of the bidirectional DC / DC converter is energized and the power supply status of the first side of the bidirectional DC / DC converter is not energized, controlling the charging module to charge the first bus capacitor and the second bus capacitor from the second side. Specifically, controlling the charging module to simultaneously charge the first bus capacitor and the second bus capacitor from the first side includes: controlling the first switch in the charging module to be turned on, and controlling the second switch in the charging module to be turned off; wherein the first end of the first switch is connected to the positive electrode of the first bus capacitor, and the second end thereof is connected to the first end of the charging resistor; the second end of the charging resistor is connected to the positive electrode of the second bus capacitor; the first end of the second switch is connected between the first switch and the charging resistor, and the second end is connected to the positive terminal of the DC bus on the second side of the bidirectional DC / DC converter. Controlling the charging module to simultaneously charge the first bus capacitor and the second bus capacitor from the second side includes: controlling the first switch in the charging module to be turned off, and controlling the second switch in the charging module to be turned on.

[0059] Since the charging resistor of the above-mentioned charging module is set on the low-voltage side, when both the high-voltage side and the low-voltage side have power, the first bus capacitor and the second bus capacitor also need to be charged from the low-voltage side. Therefore, the above-mentioned step S102 also includes: if the power-on state of the first side of the bidirectional DC / DC converter is energized, and the power-on state of the second side of the bidirectional DC / DC converter is also energized, then controlling the charging module to charge the first bus capacitor and the second bus capacitor from the low-voltage side at the same time.

[0060] Example 6

[0061] This embodiment provides a computer-readable storage medium having a computer program stored thereon. When the program is executed by a processor, the above-mentioned charging control method is implemented.

[0062] The device embodiments described above are merely illustrative. The units described as separate components may or may not be physically separate, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed across multiple network units. Some or all of the modules may be selected based on actual needs to achieve the objectives of this embodiment.

[0063] Through the description of the above embodiments, those skilled in the art can clearly understand that each embodiment can be implemented by means of software plus a necessary general hardware platform, or of course, by hardware. Based on this understanding, the essence of the above technical solution or the part that contributes to the existing technology can be embodied in the form of a software product. The computer software product can be stored in a computer-readable storage medium, such as ROM / RAM, a magnetic disk, an optical disk, etc., and includes a number of instructions for enabling a computer device (which can be a personal computer, a server, or a network device, etc.) to execute the methods described in each embodiment or certain parts of the embodiments.

[0064] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A charging circuit, applied to a bidirectional DC / DC converter, characterized in that: The circuit comprises: a charging module, having a first end connected to the positive electrode of the first bus capacitor on the first side of the bidirectional DC / DC converter, a second end connected to the positive electrode of the second bus capacitor on the second side of the bidirectional DC / DC converter, and a third end connected to the positive terminal of the DC bus on the second side of the bidirectional DC / DC converter; the charging module comprising: a first switch, having a first end connected to the positive electrode of the first bus capacitor and a second end connected to the first end of a charging resistor; the charging resistor, having a second end connected to the positive electrode of the second bus capacitor; and a second switch, having a first end connected between the first switch and the charging resistor and a second end connected to the positive terminal of the DC bus on the second side of the bidirectional DC / DC converter; The charging module is used to charge the first bus capacitor and the second bus capacitor.

2. The circuit according to claim 1, wherein: The first side of the bidirectional DC / DC converter is a high-voltage side, and the second side of the bidirectional DC / DC converter is a low-voltage side.

3. A bidirectional DC / DC converter, characterized in that: The charging circuit comprises the charging circuit according to claim 1 or 2.

4. A charging control method, applied to a bidirectional DC / DC converter, characterized in that: The method comprises: detecting a power-on state of a first side and a second side of the bidirectional DC / DC converter; Controlling a charging module to charge a first bus capacitor on the first side of the bidirectional DC / DC converter and a second bus capacitor on the second side of the bidirectional DC / DC converter according to power-on states of the first side and the second side of the bidirectional DC / DC converter; The first end of the charging module is connected to the positive electrode of the first bus capacitor, the second end is connected to the positive electrode of the second bus capacitor, and the third end is connected to the positive terminal of the DC bus on the second side of the bidirectional DC / DC converter.

5. The method according to claim 4, characterized in that Controlling a charging module to charge a first bus capacitor on the first side of the bidirectional DC / DC converter and a second bus capacitor on the second side of the bidirectional DC / DC converter according to power-on states of the first side and the second side of the bidirectional DC / DC converter, comprising: If the power-on state of the first side of the bidirectional DC / DC converter is energized and the power-on state of the second side of the bidirectional DC / DC converter is not energized, controlling the charging module to charge the first bus capacitor and the second bus capacitor simultaneously from the first side; If the power-on state of the second side of the bidirectional DC / DC converter is energized and the power-on state of the first side of the bidirectional DC / DC converter is not energized, control the charging module to charge the first bus capacitor and the second bus capacitor simultaneously from the second side.

6. The method according to claim 5, characterized in that Controlling the charging module to charge the first bus capacitor and the second bus capacitor simultaneously from the first side includes: controlling a first switch in the charging module to be turned on, and controlling a second switch in the charging module to be turned off; The first end of the first switch is connected to the positive electrode of the first bus capacitor, and the second end thereof is connected to the first end of the charging resistor; the second end of the charging resistor is connected to the positive electrode of the second bus capacitor; the first end of the second switch is connected between the first switch and the charging resistor, and the second end is connected to the positive terminal of the DC bus on the second side of the bidirectional DC / DC converter.

7. The method according to claim 5, characterized in that Controlling the charging module to charge the first bus capacitor and the second bus capacitor simultaneously from the second side includes: The first switch in the charging module is controlled to be disconnected, and the second switch in the charging module is controlled to be connected.

8. The method according to claim 4, characterized in that Controlling a charging module to charge a first bus capacitor on the first side of the bidirectional DC / DC converter and a second bus capacitor on the second side of the bidirectional DC / DC converter according to power-on states of the first side and the second side of the bidirectional DC / DC converter, further comprising: If the power-on state of the first side of the bidirectional DC / DC converter is energized and the power-on state of the second side of the bidirectional DC / DC converter is also energized, the charging module is controlled to charge the first bus capacitor and the second bus capacitor simultaneously from the low-voltage side.

9. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the program is executed by a processor, the method according to any one of claims 4 to 8 is implemented.

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