Voltage conversion circuit, voltage conversion method, and storage medium

Abstract

The present application relates to a voltage conversion circuit, a voltage conversion method, and a storage medium. The conversion circuit comprises: a voltage converter, the voltage converter comprising: a first inverter resonance circuit, which is configured to perform conversion between a direct-current bus voltage and a first alternating-current voltage; a second inverter resonance circuit, which is configured to perform conversion between a direct-current battery voltage on a battery side and a second alternating-current voltage; and a transformer, wherein the ratio of the number of turns of a primary-side coil of the transformer to the number of turns of a secondary-side coil of the transformer is a positive rational number N, and the primary-side coil is connected to the first alternating-current voltage and the secondary-side coil is connected to the second alternating-current voltage; and a voltage control module, which is configured to fix the ratio of the bus voltage to the battery voltage near N.

Description

Voltage conversion circuit, voltage conversion method, and storage medium Technical Field

[0001] The present application relates to the field of converters, and in particular to a voltage conversion circuit, a voltage conversion method, and a storage medium. Background Art

[0002] In recent years, bidirectional isolated DC-to-DC converters (DC-DC converters) have become increasingly common in applications such as industrial energy storage, high-power DC charging stations, battery swap stations, and solid-state transformers. Currently, bidirectional isolated DC-to-DC converters in the industry primarily utilize bidirectional isolation circuit topologies such as CLLC, CLLLC, and DAB (Dual Active Bridge).

[0003] How to improve the DCDC converter has become an urgent problem to be solved. In view of this, it is necessary to propose an improved voltage conversion circuit.

[0004] Summary of the Invention

[0005] Embodiments of the present application provide a voltage conversion circuit, a voltage conversion method, and a storage medium for improving the efficiency of a vehicle in a forward charging mode from a vehicle bus to a vehicle battery and a reverse discharging mode from a vehicle battery to a vehicle bus.

[0006] According to one aspect of the present application, a voltage conversion circuit is provided, comprising: a voltage converter, comprising: a first inverter resonant circuit, configured to convert between a DC bus voltage and a first AC voltage; a second inverter resonant circuit, configured to convert between a DC battery voltage on the battery side and a second AC voltage; and a transformer, wherein the turns ratio of the primary coil and the secondary coil is a positive rational number N, and the primary coil is connected to the first AC voltage, and the secondary coil is connected to the second AC voltage; and a voltage control module, configured to fix the ratio of the bus voltage to the battery voltage to be near N.

[0007] In some embodiments of the present application, optionally, the bus voltage comes from an external AC-DC converter, and during the charging process in which the conversion circuit converts the bus voltage into the battery voltage, the voltage control module instructs the AC-DC converter to adjust the output bus voltage and fixes the ratio of the bus voltage to the battery voltage to be around N.

[0008] In some embodiments of the present application, optionally, during the discharge process in which the conversion circuit converts the battery voltage into the bus voltage, the voltage control module instructs the first inverter resonant circuit to adjust its parameters to fix the ratio of the bus voltage to the battery voltage to be around N.

[0009] In some embodiments of the present application, optionally, the first inverter resonant circuit and the second inverter resonant circuit respectively include a full-bridge inverter circuit for realizing conversion between DC voltage and square wave voltage, and a resonant circuit for realizing conversion between square wave voltage and sinusoidal voltage.

[0010] In some embodiments of the present application, optionally, the voltage converter is an LLC converter, a CLLC converter, or a CLLLC converter.

[0011] According to another aspect of the present application, a voltage conversion method is provided, which includes the following steps: providing a voltage converter, the voltage converter including: a first inverter resonant circuit configured to convert between a DC bus voltage and a first AC voltage; a second inverter resonant circuit configured to convert between a DC battery voltage on the battery side and a second AC voltage; and a transformer having a turns ratio of a primary coil and a secondary coil being a positive rational number N; connecting the primary coil to the first AC voltage and connecting the secondary coil to the second AC voltage; and fixing the ratio of the bus voltage to the battery voltage to be around N.

[0012] In some embodiments of the present application, optionally, the bus voltage comes from an external AC-DC converter, and during the charging process in which the conversion circuit converts the bus voltage into the battery voltage, the AC-DC converter is instructed to adjust the output bus voltage and fix the ratio of the bus voltage to the battery voltage to be around N.

[0013] In some embodiments of the present application, optionally, during the discharge process in which the conversion circuit converts the battery voltage into the bus voltage, an instruction is given to adjust the parameters of the first inverter resonant circuit to fix the ratio of the bus voltage to the battery voltage to be around N.

[0014] In some embodiments of the present application, optionally, the first inverter resonant circuit and the second inverter resonant circuit respectively include a full-bridge inverter circuit for converting between a DC voltage and a square wave voltage, and a resonant circuit for converting between a square wave voltage and a sinusoidal voltage.

[0015] In some embodiments of the present application, optionally, the voltage converter is an LLC converter, a CLLC converter, or a CLLLC converter.

[0016] According to another aspect of the present application, a voltage conversion circuit is provided, comprising: a memory configured to store instructions; and a processor configured to execute the instructions to perform any one of the methods described above.

[0017] According to another aspect of the present application, a computer-readable storage medium is provided, wherein instructions are stored in the computer-readable storage medium, and wherein when the instructions are executed by a processor, the processor is caused to execute any one of the methods described above. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The above and other objects and advantages of the present application will become more fully apparent from the following detailed description taken in conjunction with the accompanying drawings, wherein the same or similar elements are denoted by the same reference numerals.

[0019] FIG1 shows a voltage conversion circuit according to an embodiment of the present application;

[0020] FIG2 shows a voltage conversion circuit according to an embodiment of the present application;

[0021] FIG3 shows a voltage conversion circuit according to an embodiment of the present application;

[0022] FIG4 shows a voltage relationship diagram according to an embodiment of the present application;

[0023] FIG5 shows a forward gain equivalent circuit according to one embodiment of the present application;

[0024] FIG6 shows a forward gain curve according to one embodiment of the present application;

[0025] FIG7 shows a reverse gain equivalent circuit according to an embodiment of the present application;

[0026] FIG8 shows a reverse gain curve diagram according to one embodiment of the present application. DETAILED DESCRIPTION

[0027] For purposes of brevity and illustration, the principles of the present application are described herein primarily with reference to exemplary embodiments thereof. However, those skilled in the art will readily recognize that the same principles are equally applicable to all types of voltage conversion circuits, voltage conversion methods, and storage media, and that the same or similar principles may be implemented therein, without departing from the true spirit and scope of the present application.

[0028] According to one aspect of the present application, a voltage conversion circuit is provided. As shown in FIG1 , the voltage conversion circuit 10 (hereinafter referred to as circuit 10) includes a voltage converter 101 and a voltage control module 102. The voltage conversion circuit 10 can be used to realize the conversion of direct current to direct current. Specifically, the voltage conversion circuit 10 can convert direct current into alternating current through its voltage converter 101 during the conversion process, then perform voltage conversion on the alternating current through a transformer, and finally process the converted alternating current into direct current. For this reason, the voltage converter 101 of the present application is also called a DCDC converter in the industry. Its working principle can refer to the prior art and will not be described in detail herein. The working process of the voltage converter 101 is controlled by the voltage control module 102, thereby achieving different voltage conversion effects. The specific composition structure of the voltage converter 101 will be described in detail below.

[0029] According to one aspect of the present application, a voltage conversion circuit is provided. As shown in FIG1 , the voltage conversion circuit 10 includes a voltage converter 101 and a voltage control module 102. The voltage conversion circuit 10 can achieve DC to DC conversion and maintain high efficiency.

[0030] The voltage converter 101 includes a first inverter resonant circuit, a second inverter resonant circuit, and a transformer 110. The first inverter resonant circuit of the voltage converter 101 is capable of converting between the DC bus voltage (the DC voltage carried between Bus+ and Bus- as shown in FIG1 ) and a first AC voltage, while the second inverter resonant circuit is capable of converting between the DC battery voltage on the battery side (the DC voltage carried between Bat+ and Bat- as shown in FIG1 ) and a second AC voltage. The first and second AC voltages herein are intermediate products of the voltage conversion and are applied / generated on both sides of the transformer 110, as described in detail below.

[0031] Continuing with Figure 1 , the turns ratio of the primary coil Tp (left coil in the figure) and the secondary coil Ts (right coil in the figure) of the transformer 110 is a positive rational number N. The primary coil Tp is connected to the first AC voltage, and the secondary coil Ts is connected to the second AC voltage. Generally speaking, the second AC voltage carried by the battery side of the transformer 110 used in the automotive field (the side where the secondary coil Ts is located) is lower than the first AC voltage, so N can be a rational number such as 3:1 or 5:3.

[0032] As will be appreciated, the transformer 110 can convert an input voltage on the primary winding Tp to an output voltage on the secondary winding Ts, and can also convert an input voltage on the secondary winding Ts to an output voltage on the primary winding Tp. Generally, the turns ratio N between the primary winding Tp and the secondary winding Ts can be greater than 1, thereby achieving a voltage step-down from the primary to the secondary, or a voltage step-up from the secondary to the primary.

[0033] The voltage control module 102 of the voltage conversion circuit 10 can set the ratio of the bus voltage to the battery voltage to be fixed at approximately N. Specifically, in the forward charging mode or the reverse discharging mode, the voltage control module 102 controls the bus voltage to always be N times the battery voltage, that is, V BUS =N*V BAT , so that the bus voltage dynamically follows the battery voltage. BUS The DC voltage between the Bus+ and Bus- busbars shown in Figure 1 is V BAT It carries the DC voltage between the Bat+ and Bat- battery electrodes shown in Figure 1. This will enable the voltage converter 101 to always operate at the forward resonant frequency point, thereby achieving the voltage converter 101 always operating at the forward high efficiency point.

[0034] It should be understood that due to limitations in the actual environment or industrial precision, it is sometimes difficult to fix the ratio of the bus voltage to the battery voltage to N. Therefore, the ratio of the bus voltage to the battery voltage can be fixed to be near N (for example, within a range of a fixed value or percentage different from N). These situations should be regarded as voltage control with N value as the target, and the scope of protection of this application also extends to such situations.

[0035] In some embodiments of the present application, as shown in FIG1 , the voltage converter 101 is an LLC converter. In other examples, the voltage converter 101 may also be a CLLC converter as shown in FIG2 or a CLLLC converter as shown in FIG3 . In some embodiments of the present application, the first inverter resonant circuit and the second inverter resonant circuit respectively include a full-bridge inverter circuit for converting between a DC voltage and a square wave voltage, and a resonant circuit for converting between a square wave voltage and a sinusoidal voltage. As shown in FIG1 , the first inverter resonant circuit of the LLC converter 101 is composed of a full-bridge inverter circuit 111 and a resonant circuit (113, 114, 115). The full-bridge inverter circuit 111 includes four switching transistors as shown, and the resonant circuit includes a capacitor 113, a capacitor 114, and an inductor 115. The second inverter resonant circuit of the LLC converter 101 is composed of a full-bridge inverter circuit 112 and a resonant circuit 116. The full-bridge inverter circuit 112 includes four switching transistors as shown, and the resonant circuit 116 includes a capacitor 116.

[0036] Turning to Figure 2 , compared to the LLC converter shown in Figure 1 , the resonant circuit in the second inverter resonant circuit of the CLLC converter 101 in Figure 2 has an additional capacitor 201. Continuing to refer to Figure 3 , the CLLLC converter 101 shown in Figure 3 has an additional inductor 301 in the resonant circuit of its second inverter resonant circuit, based on the configuration shown in Figure 2 .

[0037] The advantage of using an LLC converter is that it eliminates the secondary-side resonant device, thereby reducing costs compared to CLLC and CLLLC converters. The general operating principles of LLC, CLLC, and CLLLC converters can be referenced in the prior art and will not be detailed here.

[0038] In some embodiments of the present application, the bus voltage comes from an external AC-DC converter (not shown in the figure), and during the charging process in which the conversion circuit 10 converts the bus voltage into the battery voltage, the voltage control module 102 instructs the AC-DC converter to adjust the output bus voltage and fix the ratio of the bus voltage to the battery voltage to be around N.

[0039] During the charging process, the battery voltage lower limit is set to V BAT -L, the upper limit of battery voltage is V BAT -H, bus voltage lower limit is V BUS -L, the bus voltage upper limit is V BUS -H, the primary turns of the transformer 110 of the LLC converter 101 is Tp, and the secondary turns of the transformer 110 is Ts. At this time, the primary-to-secondary turns ratio of the LLC transformer can be designed as N = Tp / Ts = V BUS -L / V BAT -L.

[0040] Specifically, in the forward charging mode, the voltage control module 102 can send an instruction to the AC / DC converter to instruct the AC / DC converter to adjust the output bus voltage, so as to control the bus voltage to always be N times the battery voltage, that is, V BUS =N*V BAT , so that the bus voltage follows the battery voltage in dynamic linkage. At this time, the bus side closed-loop control module 121 works in the battery side voltage or current closed-loop mode, and the battery side closed-loop control module 122 works in the synchronous rectification mode. Through the above configuration, the battery voltage V BAT (between the maximum V BAT -H and minimum V BAT -L) and bus voltage V BUS (between the maximum V BUS -H and minimum V BUS -L) satisfies the linear relationship shown in Figure 4.

[0041] FIG5 shows a forward resonant equivalent circuit of the LLC converter 101, whose forward resonant gain function satisfies:

[0042] Where: M = V BAT / V BUS , is the forward DC voltage gain of the LLC converter 101;

[0043] n=Tp / Ts, which is the ratio of the primary and secondary turns of transformer 110

[0044] λ = Lr / Lm, which is the ratio of the resonant inductance Lr to the excitation inductance Lm;

[0045] fn=f / fr, which is the normalized frequency, that is, the ratio of the current operating frequency to the resonant frequency fr;

[0046] is the quality factor;

[0047] Rac=n 2 *R L , is the equivalent load;

[0048] Lr, is the forward resonant inductance;

[0049] Cr is the forward resonant capacitance;

[0050] Lm, is the forward excitation inductance;

[0051] is the forward resonant frequency.

[0052] In addition, FIG6 shows a forward resonance gain curve of the LLC converter 101 .

[0053] In some embodiments of the present application, during the discharge process in which the conversion circuit 10 converts the battery voltage into the bus voltage, the voltage control module 102 instructs the first inverter resonant circuit to adjust its parameters to fix the ratio of the bus voltage to the battery voltage to be around N.

[0054] Specifically, in the reverse discharge mode, the bus voltage is always controlled to be N times the battery voltage by the voltage control module 102, that is, V BUS =N*V BAT , so that the bus voltage dynamically follows the battery voltage. At this time, the battery side closed-loop control module 122 operates in the bus side voltage or current closed-loop mode, and the bus side closed-loop control module 121 operates in the synchronous rectification mode.

[0055] FIG7 shows a reverse resonance equivalent circuit of the LLC converter 101, whose reverse resonance gain function satisfies:

[0056] Where: M = V BUS / V BAT , is the reverse DC voltage gain of the LLC converter 101;

[0057] fn=f / fr', which is the normalized frequency, that is, the ratio of the current operating frequency to the reverse resonant frequency fr';

[0058] is the reverse quality factor;

[0059] R'ac=R L ' / n 2 , is the reverse equivalent load;

[0060] L'r=Lr / n 2 , is the reverse resonant inductance;

[0061] C'r=Cr / n 2 , is the reverse resonant capacitance;

[0062] L'm=Lm / n 2 , is the reverse excitation inductance;

[0063] is the reverse resonant frequency.

[0064] In addition, FIG8 shows a reverse resonance gain curve of the LLC converter 101 .

[0065] Another aspect of the present application provides a voltage conversion method, which includes the following steps: providing a voltage converter, the voltage converter including: a first inverter resonant circuit configured to convert between a DC bus voltage and a first AC voltage; a second inverter resonant circuit configured to convert between a DC battery voltage on the battery side and a second AC voltage; and a transformer having a turns ratio of a primary coil and a secondary coil that is a positive rational number N; connecting the primary coil to the first AC voltage and connecting the secondary coil to the second AC voltage; and fixing the ratio of the bus voltage to the battery voltage to be around N. The voltage conversion method according to the present application can achieve DC to DC conversion and maintain the conversion at a high efficiency. The specific process of the voltage conversion method can be carried out according to the voltage conversion circuit 10, and the above content is cited here. Due to space limitations, this article will not elaborate on it here.

[0066] In some embodiments of the present application, the bus voltage comes from an external AC-DC converter, and during the charging process in which the conversion circuit converts the bus voltage into the battery voltage, the AC-DC converter is instructed to adjust the output bus voltage and fix the ratio of the bus voltage to the battery voltage to be around N.

[0067] In some embodiments of the present application, during the discharge process in which the conversion circuit converts the battery voltage into the bus voltage, an instruction is given to adjust the parameters of the first inverter resonant circuit to fix the ratio of the bus voltage to the battery voltage to be around N.

[0068] In some embodiments of the present application, the first inverter resonant circuit and the second inverter resonant circuit respectively include a full-bridge inverter circuit for realizing conversion between DC voltage and square wave voltage, and a resonant circuit for realizing conversion between square wave voltage and sinusoidal voltage.

[0069] In some embodiments of the present application, the voltage converter is an LLC converter, a CLLC converter, or a CLLLC converter.

[0070] According to another aspect of the present application, a voltage conversion circuit is provided, comprising: a memory configured to store instructions; and a processor configured to execute the instructions to perform any one of the methods described above.

[0071] According to another aspect of the present application, a computer-readable storage medium is provided, wherein instructions are stored. When the instructions are executed by a processor, the processor is caused to perform any of the voltage conversion methods described above. The computer-readable medium referred to in the present application includes various types of computer storage media, and can be any available medium that can be accessed by a general-purpose or special-purpose computer. For example, the computer-readable medium can include RAM, ROM, EPROM, E 2 PROM, register, hard disk, removable disk, CD-ROM or other optical disk storage, magnetic disk storage or other magnetic storage device, or any other temporary or non-temporary medium that can be used to carry or store desired program code units in the form of instructions or data structures and can be accessed by a general or special-purpose computer, or a general or special-purpose processor. As used herein, disks usually copy data magnetically, while dishes use lasers to optically copy data. The above combinations should also be included in the scope of protection of computer-readable media. An exemplary storage medium is coupled to a processor so that the processor can read and write information from / to the storage medium. In an alternative solution, the storage medium can be integrated into the processor. The processor and storage medium can reside in an ASIC. The ASIC can reside in a user terminal. In an alternative solution, the processor and storage medium can reside in a user terminal as discrete components.

[0072] The bidirectional isolated DCDC converter proposed in the above embodiments of the present application can be used in high-power DC charging piles, bidirectional battery swap stations and other occasions, so as to achieve cost reduction and efficiency improvement, and therefore has high economic value. The above is only a specific implementation method of the present application, but the scope of protection of the present application is not limited to this. Those skilled in the art can think of other feasible changes or replacements based on the technical scope disclosed in this application, and such changes or replacements are all included in the scope of protection of this application. In the absence of conflict, the implementation methods of the present application and the features in the implementation methods can also be combined with each other. The scope of protection of the present application shall be based on the records of the claims.

Claims

1. A DC voltage conversion circuit, characterized in that: The conversion circuit comprises: A voltage converter comprising: A first inverter resonant circuit configured to convert between a DC bus voltage and a first AC voltage; a second inverter resonant circuit configured to convert between a battery voltage of a battery-side direct current and a second alternating voltage; and A transformer, wherein the turns ratio of a primary coil to a secondary coil is a positive rational number N, and the primary coil is connected to the first AC voltage, and the secondary coil is connected to the second AC voltage; and The voltage control module is configured to set the ratio of the bus voltage to the battery voltage to be fixed at approximately N.

2. The conversion circuit according to claim 1, wherein: The bus voltage comes from an external AC / DC converter, and during the charging process in which the conversion circuit converts the bus voltage into the battery voltage, the voltage control module instructs the AC / DC converter to adjust the output bus voltage and fixes the ratio of the bus voltage to the battery voltage to be around N.

3. The conversion circuit according to claim 1, wherein: During the discharge process in which the conversion circuit converts the battery voltage into the bus voltage, the voltage control module instructs the first inverter resonant circuit to adjust its parameters to fix the ratio of the bus voltage to the battery voltage to be around N.

4. The conversion circuit according to claim 1, wherein: The first inverter resonant circuit and the second inverter resonant circuit respectively include a full-bridge inverter circuit for realizing conversion between a DC voltage and a square wave voltage, and a resonant circuit for realizing conversion between a square wave voltage and a sinusoidal voltage.

5. The conversion circuit according to claim 4, wherein: The voltage converter is an LLC converter, a CLLC converter or a CLLLC converter.

6. A DC voltage conversion method, characterized in that: The method comprises: A voltage converter is provided, comprising: a first inverter resonant circuit configured to convert between a DC bus voltage and a first AC voltage; a second inverter resonant circuit configured to convert between a DC battery voltage on a battery side and a second AC voltage; and a transformer having a turns ratio of a primary coil to a secondary coil that is a positive rational number N; Connecting the primary coil to the first AC voltage, and connecting the secondary coil to the second AC voltage; and The ratio of the bus voltage to the battery voltage is fixedly set to be near N.

7. The method according to claim 6, wherein: The bus voltage comes from an external AC / DC converter, and during the charging process in which the conversion circuit converts the bus voltage into the battery voltage, the AC / DC converter is instructed to adjust the output bus voltage, and the ratio of the bus voltage to the battery voltage is fixedly set to be around N.

8. The method according to claim 6, wherein: During the discharging process in which the conversion circuit converts the battery voltage into the bus voltage, an instruction is given to adjust the parameters of the first inverter resonant circuit so as to fix the ratio of the bus voltage to the battery voltage to be around N.

9. The method according to claim 6, wherein: The first inverter resonant circuit and the second inverter resonant circuit respectively include a full-bridge inverter circuit for realizing conversion between a DC voltage and a square wave voltage, and a resonant circuit for realizing conversion between a square wave voltage and a sinusoidal voltage.

10. The method according to claim 9, wherein: The voltage converter is an LLC converter, a CLLC converter or a CLLLC converter.

11. A voltage conversion circuit, characterized in that: The conversion circuit comprises: a memory configured to store instructions; and A processor configured to execute the instructions to perform the method according to any one of claims 6 to 10.

12. A computer-readable storage medium, wherein instructions are stored in the computer-readable storage medium, characterized in that: When the instructions are executed by a processor, the processor is caused to perform the method according to any one of claims 6 to 10.

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