CLLC topology-based cross phase shift control method and system

Abstract

The present application provides a CLLC topology-based cross phase shift control method and system. The CLLC topology-based cross phase shift control method comprises: constructing an LLC topology circuit; performing loop adjustment on the basis of the LLC topology circuit, and determining whether a frequency modulation condition is satisfied; if the frequency modulation condition is satisfied, performing frequency modulation control; and if the frequency modulation condition is not satisfied, performing phase shift control on the basis of a time change.

Description

A cross-phase shift control method and system based on CLLC topology

[0001] Related applications

[0002] This application claims priority to Chinese patent application No. 202311780135.X filed on December 21, 2023, the entire contents of which are incorporated by reference into this application. Technical Field

[0003] The present application relates to the field of automobile charging technology, and in particular to a cross-phase shift control method and system based on CLLC topology. Background Art

[0004] With the sharp increase in sales of new energy electric vehicles and the continuous increase in the number of new energy electric vehicles in use, the market has put forward higher requirements on the performance of on-board chargers (OBCs). The CLLC topology circuit has the characteristics of bidirectional transmission, high energy density, and high efficiency, and is widely used in the DC / DC converter of on-board chargers.

[0005] However, the existing technology often adopts a unilateral phase-shift control method under light load conditions, resulting in a phenomenon in which one pair of bridge arms is always in a soft switching state and the other pair of bridge arms is always in a hard switching state. The two pairs of bridge arms are heated unevenly, resulting in reduced efficiency and service life. Summary of the Invention

[0006] In order to solve at least one problem in the background technology, the present application proposes a cross-phase shift control method and system based on CLLC topology.

[0007] In order to achieve the above objectives, this application adopts the following technical solutions:

[0008] The present application provides a cross-phase shift control method based on a CLLC topology, the control method comprising the following steps:

[0009] Construct LLC topology circuit;

[0010] Perform loop adjustment based on LLC topology circuit and determine whether frequency modulation conditions are met;

[0011] If the frequency modulation conditions are met, frequency modulation control is performed;

[0012] If the frequency modulation conditions are not met, phase shift control is performed according to time changes.

[0013] In one embodiment, performing loop regulation and determining whether a frequency modulation condition is met includes the following steps:

[0014] Determine the target output voltage;

[0015] Run the PI algorithm to determine the switching frequency corresponding to the target output voltage;

[0016] It is determined whether the switching frequency is within the range of the frequency modulation condition. If the switching frequency is outside the range of the frequency modulation condition, phase shift control is performed according to time variation; otherwise, frequency modulation control is performed.

[0017] In one embodiment, the frequency corresponding to the frequency modulation condition is 47KHz to 110KHz.

[0018] In one embodiment, if the frequency modulation condition is met, frequency modulation control is performed, including the following steps:

[0019] Adjust the voltage cycle of the MOS tube to meet the switching frequency corresponding to the target output voltage.

[0020] In one embodiment, if the frequency modulation condition is not met, phase shift control is performed according to time variation, including the following steps:

[0021] When the charging time is an odd number of minutes, the PWM1 bridge arm is fixed and the PWM2 bridge arm changes phase relative to the PWM1 bridge arm through software control;

[0022] When the charging time is an even number of minutes, the PWM2 bridge arm is fixed and the phase of the PWM1 bridge arm relative to the PWM2 bridge arm is changed through software control;

[0023] Alternatively, when the charging time is an even number of minutes, the PWM1 bridge arm is fixed and the PWM2 bridge arm changes phase relative to the PWM1 bridge arm through software control;

[0024] When the charging time is an odd number of minutes, the PWM2 bridge arm is fixed and the phase of the PWM1 bridge arm relative to the PWM2 bridge arm is changed through software control.

[0025] In one embodiment, both the PWM1 bridge arm and the PWM2 bridge arm are MOS transistors.

[0026] The present application also provides a cross-phase shift control system based on CLLC topology, comprising a calculation unit, a frequency modulation unit and a phase shift unit;

[0027] The calculation unit is used to perform loop adjustment and determine whether the frequency modulation conditions are met;

[0028] The frequency modulation unit is used to perform frequency modulation control when the frequency modulation conditions are met;

[0029] The phase shift unit is used to perform phase shift control according to time changes when the frequency modulation condition is not met.

[0030] In one embodiment, the calculation unit includes:

[0031] A setting module for determining a target output voltage;

[0032] A calculation module is used to run a PI algorithm to determine the switching frequency corresponding to the target output voltage;

[0033] The judging module is used to judge whether the switching frequency is within the range of the frequency modulation condition. If the switching frequency is outside the range of the frequency modulation condition, phase shift control is performed according to time variation; otherwise, frequency modulation control is performed.

[0034] In one embodiment, the frequency modulation unit includes:

[0035] The frequency modulation module is used to adjust the voltage cycle of the MOS tube so that it meets the switching frequency corresponding to the target output voltage.

[0036] In one embodiment, the phase shifting unit includes:

[0037] a first phase-shifting module, configured to, when the charging time is an odd number of minutes, keep the PWM1 bridge arm fixed and change the phase of the PWM2 bridge arm relative to the PWM1 bridge arm through software control;

[0038] A second phase-shifting module, when the charging time is an even number of minutes, is used to keep the PWM2 bridge arm fixed and change the phase of the PWM1 bridge arm relative to the PWM2 bridge arm through software control;

[0039] Alternatively, when the charging time is an even number of minutes, the first phase shift module is used to keep the PWM1 bridge arm fixed and change the phase of the PWM2 bridge arm relative to the PWM1 bridge arm through software control;

[0040] When the charging time is an odd number of minutes, the second phase shift module is used to keep the PWM2 bridge arm fixed and change the phase of the PWM1 bridge arm relative to the PWM2 bridge arm through software control.

[0041] Beneficial effects of this application:

[0042] 1. This application adopts loop regulation, frequency modulation control and phase shift control. During operation, the target voltage can be obtained through loop regulation, and then the switching frequency is obtained according to the target voltage. Frequency modulation control or phase shift control is selected according to the size of the switching frequency, thereby solving the problem of uneven heating of the two pairs of bridge arms in the LLC topology.

[0043] 2. This application adopts a cross-phase shift control method, and the two pairs of bridge arms are dynamically in a hard switching or software switching state, so that the two pairs of bridge arms are heated evenly, the conversion efficiency and service life are improved, and the shortcomings of the existing technology can be effectively solved.

[0044] Other features and advantages of the present application will be described in the following description, and in part will become apparent from the description, or will be understood by practicing the present application. The purpose and other advantages of the present application can be realized and obtained by the structures indicated in the description and the drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying any creative work.

[0046] FIG1 shows a flow chart of a cross-phase shift control method based on CLLC topology of the present application;

[0047] FIG2 shows a topological circuit diagram of LLC of the present application;

[0048] FIG3 shows a phase shift control timing diagram of the present application;

[0049] FIG4 shows a cross-phase shift control system diagram based on CLLC topology of the present application.

[0050] The realization of the objectives, functional features and advantages of this application will be further explained in conjunction with embodiments and with reference to the accompanying drawings. Modes for Carrying Out the Invention

[0051] To make the purpose, technical solutions, and advantages of the embodiments of this application more clear, the technical solutions in the embodiments of this application will be clearly and completely described below in conjunction with the drawings in the embodiments of this application. Obviously, the described embodiments are part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0052] The present application provides a cross-phase shift control method based on the CLLC topology. As shown in Figure 1, the above-mentioned control method includes the following steps: S1: constructing an LLC topology circuit; S2: performing loop adjustment based on the LLC topology circuit and judging whether the frequency modulation conditions are met; S3a: if the frequency modulation conditions are met, performing frequency modulation control; S3b: if the frequency modulation conditions are not met, performing phase shift control according to time changes.

[0053] As shown in Figure 2, Figure 2 is a circuit diagram of the LLC topology of the present application, wherein the bus voltage of the left circuit is Vin and the bus voltage of the right circuit is Vo. In addition, four groups of bridge arms are provided in the circuit of Figure 2. In the two groups of bridge arms of the left circuit, MOS tube Q24 and MOS tube Q26 form a group and are controlled by PWM1A and PWM1B respectively, referred to as PWMA bridge arm; MOS tube Q23 and MOS tube Q25 form a group and are controlled by PWM2A and PWM2B respectively, referred to as PWMB bridge arm. PWM1A, PWM1B, PWM2A and PWM2B are all pulse width modulators. In the right circuit, MOS tubes Q27 and Q29 form a group, and MOS tubes Q28 and Q30 form a group. The left bridge arm circuit and the right bridge arm circuit are voltage-converted and controlled by a linear transformer. At the same time, capacitors and inductors and other devices can be provided on the line connected to the linear transformer, such as inductor L19, capacitor C252 and capacitor C17 in the figure.

[0054] It should be noted that, in conjunction with Figures 1 and 2, the crossover control method of this application continuously phase-shifts the PWMA and PWMB bridge arms, achieving alternating "soft switching" and "hard switching" operation via the LLC principle, thereby reducing heat loss in the MOS tube. Q23-Q30 are field-effect transistors (MOSFETs), specifically: N-channel 80A / 650V Rdson = 38mR TO-247.

[0055] The cross-phase shift control method of the present application is described below with reference to steps S1 to S2b.

[0056] In one embodiment, loop adjustment is performed in S1, and it is determined whether the frequency modulation condition is met. Specifically, the following steps are included: first, the target output voltage needs to be determined, then the PI algorithm is run to determine the switching frequency corresponding to the target output voltage, and finally, it is determined whether the switching frequency is within the range of the frequency modulation condition. If the switching frequency is outside the range of the frequency modulation condition, phase shift control is performed according to time variation, otherwise frequency modulation control is performed.

[0057] It should be noted that CLLC has the characteristic that the higher the switching frequency, the lower the output voltage when frequency modulation; however, due to the influence of electronic components, the switching frequency cannot be increased indefinitely. The range of frequency modulation conditions in this application is (47KHZ ~ 110KHZ). When the highest output frequency cannot meet the output voltage range, phase modulation control is performed. For example, when the lowest frequency modulation frequency is 47KHZ, the output voltage is 465V, and when the highest frequency frequency is 110KHZ, the output voltage is 300V. If a voltage of 200V is to be output, phase shift control is required at a switching frequency of 110KHZ. In addition, CLLC is an extension of LLC. LLC can only transmit energy in one direction (Vin is converted into Vo), while CLLC is a bidirectional energy transmission (Vin can be converted into Vo output through Q23 / Q24 / Q25 / Q26, and Vo can also be converted into Vin output through Q27 / Q28 / Q29 / Q30).

[0058] It should be further explained that, taking the frequency modulation condition of 47 kHz to 110 kHz as an example, in actual operation, the switching frequency will not fall below 47 kHz. Therefore, it is only necessary to determine whether the switching frequency is greater than 110 kHz. If it is, phase shift control is required; otherwise, frequency modulation control is performed. Frequency modulation control is performed by adjusting the switching frequency period. Therefore, in S2a, if the frequency modulation condition is met, frequency modulation control is performed, including the following steps: adjusting the voltage period of the MOS tube to meet the switching frequency corresponding to the target output voltage.

[0059] In one embodiment, in S2b, if the frequency modulation condition is not met, phase shift control is performed according to time variation, including the following steps:

[0060] As shown in Figure 3, when the charging time is odd minutes, the PWM1 bridge arm is fixed and the phase of the PWM2 bridge arm relative to the PWM1 bridge arm is changed through software control; when the charging time is even minutes, the PWM2 bridge arm is fixed and the phase of the PWM1 bridge arm relative to the PWM2 bridge arm is changed through software control.

[0061] It should be noted that, in the actual phase shift process, control can also be performed according to the following steps: when the charging time is an even number of minutes, the PWM1 bridge arm is fixed through software control, and the phase of the PWM2 bridge arm relative to the PWM1 bridge arm is changed; when the charging time is an odd number of minutes, the PWM2 bridge arm is fixed through software control, and the phase of the PWM1 bridge arm relative to the PWM2 bridge arm is changed.

[0062] It's important to further explain that, as shown in Figure 3, each PWM waveform generated by PWM1 has the same shape (called the leading arm). PWM2 is phase-shifted relative to PWM1 (the PWM2 waveform has a variable time lag relative to PWM1, called the trailing arm). Hardware characteristics dictate that when PWM1 is on, MOSFETs Q24 / Q26 are turned on at zero voltage (soft switching), while when PWM2 is on, MOSFETs Q23 / Q25 are turned on at non-zero voltage (hard switching). Therefore, in Figure 3, the MOSFETs (Q24, Q26) controlled by PWM1 are turned on at non-zero voltage, resulting in high conduction losses. The MOSFETs (Q25, Q23) of PWM2 are turned on at zero voltage (ZVS), resulting in low conduction losses. Figure 3 also shows the MOSFET PWM waveforms for phase modulation control, where the gray blocks represent the phase shifts of PWM2B and PWM1B relative to PWM2A, respectively. Through the method in Figure 3, the PWMA bridge arm and the PWMB bridge arm can be heated alternately to avoid overheating of a single bridge arm, while effectively balancing the heat loss of the two bridge arms.

[0063] To sum up, the present application can avoid the MOS tube of PWM1 or PWM2 being in a non-zero voltage turn-on state (large turn-on loss) through the cross-phase shift control method, so that the two pairs of bridge arms are heated evenly, thereby improving the conversion efficiency (the higher the temperature of the MOS tube, the lower the efficiency) and service life.

[0064] The present application also provides a cross-phase shift control system based on the CLLC topology, as shown in Figure 4, the above-mentioned control system includes a calculation unit, a frequency modulation unit and a phase shift unit; the calculation unit is used to perform loop adjustment and determine whether the frequency modulation conditions are met; the frequency modulation unit is used to perform frequency modulation control when the frequency modulation conditions are met; the phase shift unit is used to perform phase shift control according to time changes when the frequency modulation conditions are not met.

[0065] In one embodiment, the calculation unit includes a setting module, a calculation module, and a judgment module. The setting module is used to determine a target output voltage; the calculation module is used to run a PI algorithm to determine a switching frequency corresponding to the target output voltage; and the judgment module is used to determine whether the switching frequency is within a frequency modulation range. If the switching frequency is outside the frequency modulation range, phase shift control is performed based on time variation; otherwise, frequency modulation control is performed.

[0066] In one embodiment, the frequency modulation unit includes a frequency modulation module, which is used to adjust the voltage cycle of the MOS tube so as to meet the switching frequency corresponding to the target output voltage.

[0067] In one embodiment, the phase shift unit includes a first phase shift module and a second phase shift module. When the charging time is an odd number of minutes, the first phase shift module is used to, through software control, keep the PWM1 bridge arm fixed and change the phase of the PWM2 bridge arm relative to the PWM1 bridge arm; when the charging time is an even number of minutes, the second phase shift module is used to, through software control, keep the PWM2 bridge arm fixed and change the phase of the PWM1 bridge arm relative to the PWM2 bridge arm; or, when the charging time is an even number of minutes, the first phase shift module is used to, through software control, keep the PWM1 bridge arm fixed and change the phase of the PWM2 bridge arm relative to the PWM1 bridge arm; when the charging time is an odd number of minutes, the second phase shift module is used to, through software control, keep the PWM2 bridge arm fixed and change the phase of the PWM1 bridge arm relative to the PWM2 bridge arm.

[0068] It should be noted that, for the system embodiments, since they basically correspond to the method embodiments, the relevant parts can be referred to the partial description of the method embodiments. The various units and modules of the cross-phase shift control system based on the CLLC topology are only divided according to functional logic, but are not limited to the above divisions, as long as they can achieve the corresponding functions; in addition, the specific names of the various units are only for the convenience of distinguishing each other and are not used to limit the scope of protection of this application.

[0069] Although the present application 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; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A cross-phase control method based on CLLC topology, wherein: The cross-phase shift control method based on CLLC topology comprises the following steps: Construct LLC topology circuit; Perform loop adjustment based on LLC topology circuit and determine whether the frequency modulation conditions are met; If the frequency modulation conditions are met, frequency modulation control is performed; If the frequency modulation conditions are not met, phase shift control is performed according to time changes.

2. The cross-phase control method based on CLLC topology according to claim 1, wherein: Perform loop adjustment and determine whether the frequency modulation conditions are met, including the following steps: Determine the target output voltage; Run the PI algorithm to determine the switching frequency corresponding to the target output voltage; It is determined whether the switching frequency is within the range of the frequency modulation condition. If the switching frequency is outside the range of the frequency modulation condition, phase shift control is performed according to time variation, otherwise frequency modulation control is performed.

3. The cross-phase control method based on CLLC topology according to claim 2, wherein: The frequency corresponding to the frequency modulation condition is 47KHz to 110KHz.

4. The cross-phase control method based on CLLC topology according to claim 1, wherein: If the frequency modulation conditions are met, frequency modulation control is performed, including the following steps: Adjust the voltage cycle of the MOS tube to meet the switching frequency corresponding to the target output voltage.

5. The cross-phase control method based on CLLC topology according to claim 1, wherein: If the frequency modulation condition is not met, phase shift control is performed according to time changes, including the following steps: When the charging time is an odd number of minutes, the PWM1 bridge arm is fixed and the PWM2 bridge arm changes phase relative to the PWM1 bridge arm through software control; When the charging time is an even number of minutes, the PWM2 bridge arm is fixed and the phase of the PWM1 bridge arm relative to the PWM2 bridge arm is changed through software control; Or, when the charging time is an even number of minutes, the PWM1 bridge arm is fixed and the PWM2 bridge arm changes phase relative to the PWM1 bridge arm through software control; When the charging time is an odd number of minutes, the PWM2 bridge arm is fixed and the phase of the PWM1 bridge arm relative to the PWM2 bridge arm is changed through software control.

6. The cross-phase control method based on CLLC topology according to claim 5, wherein: The PWM1 bridge arm and the PWM2 bridge arm both use MOS tubes.

7. A cross-phase shift control system based on CLLC topology, wherein: The cross-phase shift control system based on CLLC topology includes a calculation unit, a frequency modulation unit and a phase shift unit; The calculation unit is used to perform loop adjustment and determine whether the frequency modulation condition is met; The frequency modulation unit is used to perform frequency modulation control when the frequency modulation conditions are met; The phase shift unit is used to perform phase shift control according to time changes when the frequency modulation condition is not met.

8. The cross-phase shift control system based on CLLC topology according to claim 7, wherein: The computing unit comprises: A setting module, used for determining a target output voltage; A calculation module, used for running a PI algorithm to determine a switching frequency corresponding to a target output voltage; The judging module is used to judge whether the switching frequency is within the range of the frequency modulation condition. If the switching frequency is outside the range of the frequency modulation condition, phase shift control is performed according to time variation, otherwise frequency modulation control is performed.

9. The cross-phase shift control system based on CLLC topology according to claim 7, wherein: The frequency modulation unit comprises: The frequency modulation module is used to adjust the voltage cycle of the MOS tube so that it meets the switching frequency corresponding to the target output voltage.

10. The cross-phase shift control system based on CLLC topology according to claim 7, wherein: The phase shifting unit comprises: A first phase shift module, when the charging time is an odd number of minutes, the first phase shift module is used to make the PWM1 bridge arm fixed and the PWM2 bridge arm change phase relative to the PWM1 bridge arm through software control; A second phase shift module, when the charging time is an even number of minutes, the second phase shift module is used to make the PWM2 bridge arm fixed and the PWM1 bridge arm relative to the PWM2 bridge arm change phase through software control; Or, when the charging time is an even number of minutes, the first phase shift module is used to make the PWM1 bridge arm fixed and the PWM2 bridge arm change phase relative to the PWM1 bridge arm through software control; When the charging time is an odd number of minutes, the second phase shift module is used to keep the PWM2 bridge arm fixed and change the phase of the PWM1 bridge arm relative to the PWM2 bridge arm through software control.

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