Bidirectional LLC converter control method and device and bidirectional LLC converter

Abstract

The invention relates to a bidirectional LLC converter control method and device and a bidirectional LLC converter. The bidirectional LLC converter comprises a transformer, an LLC resonant circuit, a primary side half-bridge circuit and a secondary side bridge circuit; the secondary-side bridge circuit comprises a first power tube, a second power tube, a third power tube and a fourth power tube, the primary-side half-bridge circuit comprises a fifth power tube and a sixth power tube, and the method comprises the following steps: when the secondary-side bridge circuit is connected with a power supply input, obtaining a target gain of the converter, and generating a first driving signal, a second driving signal, a third driving signal, a fourth driving signal, a fifth driving signal and a sixth driving signal according to the target gain; a first power tube, a fourth power tube, a fifth power tube, a second power tube, a third power tube and a sixth power tube are respectively driven by a first driving signal, a fourth driving signal, a fifth driving signal, a second driving signal, a third driving signal and a sixth driving signal; the first driving signal and the second driving signal are opposite in phase, and the third driving signal and the fourth driving signal are opposite. According to the invention, the converter can meet the requirements of various different application scenes.

Description

Technical Field

[0001] The present invention relates to the technical field of converters, and more specifically, to a bidirectional LLC converter control method and device, and a bidirectional LLC converter. Background Art

[0002] In traditional bidirectional LLC converters, the switching frequency of each power tube is usually adjusted to adjust the gain of the system, and the ultimate goal is to make the conversion gain as large as possible. However, in practical applications, there are different requirements for conversion gain, so how to set the working state of the converter so that the converter gain meets the actual requirements has become increasingly important. Summary of the invention

[0003] The technical problem to be solved by the present invention is to provide a bidirectional LLC converter control method, device and bidirectional LLC converter in view of the above-mentioned technical defects of the prior art.

[0004] The technical solution adopted by the present invention to solve the technical problem is: constructing a bidirectional LLC converter control method, wherein the bidirectional LLC converter includes a transformer, an LLC resonant circuit connected to the primary side of the transformer, a primary half-bridge circuit connected to the LLC resonant circuit, and a secondary bridge circuit connected to the secondary side of the transformer;

[0005] The secondary bridge circuit includes a first power tube, a second power tube, a third power tube and a fourth power tube, the first power tube is connected in series with the third power tube, the second power tube is connected in series with the fourth power tube, and the first power tube and the second power tube are upper bridge arms of the secondary bridge circuit, and the third power tube and the fourth power tube are lower bridge arms of the secondary bridge circuit;

[0006] The primary half-bridge circuit includes a fifth power tube and a sixth power tube, the fifth power tube is connected in series with the sixth power tube, and the fifth power tube is an upper bridge arm of the primary half-bridge circuit, and the sixth power tube is an upper bridge arm of the primary half-bridge circuit;

[0007] The control method comprises:

[0008] When the secondary bridge circuit is connected to a power input, obtaining a target gain of the converter, and generating a first drive signal, a second drive signal, a third drive signal, a fourth drive signal, a fifth drive signal and a sixth drive signal according to the target gain;

[0009] driving the first power tube by the first driving signal, driving the fourth power tube by the fourth driving signal, and driving the fifth power tube by the fifth driving signal;

[0010] Drive the second power tube by the second driving signal, drive the third power tube by the third driving signal, and drive the sixth power tube by the sixth driving signal;

[0011] The first driving signal and the second driving signal have opposite phases, and the third driving signal and the fourth driving signal have opposite phases.

[0012] Preferably, in the bidirectional LLC converter control method of the present invention, when the target gain is equal to 1,

[0013] The first drive signal has the same phase as the fourth drive signal and the fifth drive signal;

[0014] The second driving signal has the same phase as the third driving signal and the sixth driving signal.

[0015] Preferably, in the bidirectional LLC converter control method of the present invention, the method further comprises:

[0016] The resonant frequency of the LLC converter is obtained, and the driving frequencies of the first driving signal and the second driving signal are set to the resonant frequency.

[0017] Preferably, in the bidirectional LLC converter control method of the present invention, when the target gain is less than 1,

[0018] The fourth driving signal is delayed by a first preset phase angle relative to the first driving signal, and the fifth driving signal is turned on when the fourth driving signal is turned on, and is turned off when the first driving signal is turned off;

[0019] The third driving signal is delayed by the first preset phase angle relative to the second driving signal. The sixth driving signal is turned on when the third driving signal is turned on, and is turned off when the second driving signal is turned off.

[0020] Preferably, in the bidirectional LLC converter control method of the present invention, when the target gain is greater than 1,

[0021] The fourth driving signal has the same phase as the first driving signal, and the fifth driving signal is delayed by a second preset phase angle relative to the first driving signal;

[0022] The third driving signal has the same phase as the second driving signal, and the sixth driving signal is delayed by the second preset phase angle relative to the second driving signal.

[0023] Preferably, in the bidirectional LLC converter control method described in the present invention, the duty cycle of the first drive signal is equal to 50%, the duty cycle of the fifth drive signal is less than or equal to 50%, and the dead zone of the fifth drive signal is greater than the dead zone of the first drive signal.

[0024] Preferably, in the bidirectional LLC converter control method of the present invention, the method further comprises:

[0025] The resonant frequency of the LLC converter is obtained, and the driving frequencies of the first driving signal and the second driving signal are set to n times the resonant frequency, where n is a constant greater than 1.

[0026] Preferably, in the bidirectional LLC converter control method described in the present invention, the value range of n is greater than 1.3 and less than 1.7.

[0027] The present invention also constructs a bidirectional LLC converter control device for a bidirectional LLC converter, wherein the bidirectional LLC converter comprises a transformer, an LLC resonant circuit connected to the primary side of the transformer, a primary half-bridge circuit connected to the LLC resonant circuit, and a secondary bridge circuit connected to the secondary side of the transformer;

[0028] The secondary bridge circuit includes a first power tube, a second power tube, a third power tube and a fourth power tube, the first power tube is connected in series with the third power tube, the second power tube is connected in series with the fourth power tube, and the first power tube and the second power tube are upper bridge arms of the secondary bridge circuit, and the third power tube and the fourth power tube are lower bridge arms of the secondary bridge circuit;

[0029] The primary half-bridge circuit includes a fifth power tube and a sixth power tube, the fifth power tube is connected in series with the sixth power tube, and the fifth power tube is an upper bridge arm of the primary half-bridge circuit, and the sixth power tube is an upper bridge arm of the primary half-bridge circuit;

[0030] The control device is used to execute the bidirectional LLC converter control method as described above.

[0031] The present invention also constructs a bidirectional LLC converter, comprising: a controller and a transformer, an LLC resonant circuit connected to the primary side of the transformer, a primary half-bridge circuit connected to the LLC resonant circuit, and a secondary bridge circuit connected to the secondary side of the transformer;

[0032] The secondary bridge circuit includes a first power tube, a second power tube, a third power tube and a fourth power tube, the first power tube is connected in series with the third power tube, the second power tube is connected in series with the fourth power tube, and the first power tube and the second power tube are upper bridge arms of the secondary bridge circuit, and the third power tube and the fourth power tube are lower bridge arms of the secondary bridge circuit;

[0033] The primary half-bridge circuit includes a fifth power tube and a sixth power tube, the fifth power tube is connected in series with the sixth power tube, and the fifth power tube is an upper bridge arm of the primary half-bridge circuit, and the sixth power tube is an upper bridge arm of the primary half-bridge circuit;

[0034] The controller is used to execute the bidirectional LLC converter control method as described above.

[0035] A bidirectional LLC converter control method, device and bidirectional LLC converter implementing the present invention have the following beneficial effects: the converter can meet the requirements of various application scenarios. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] The present invention will be further described below with reference to the accompanying drawings and embodiments, in which:

[0037] Figure 1 1 is a schematic structural diagram of an embodiment of a bidirectional LLC converter in a bidirectional LLC converter control method of the present invention;

[0038] Figure 2 is a program flow chart of an embodiment of a bidirectional LLC converter control method of the present invention;

[0039] Figure 3 1 is a schematic diagram of working waveforms of an embodiment of a bidirectional LLC converter control method of the present invention;

[0040] Figure 4 1 is a schematic diagram of working waveforms of an embodiment of a bidirectional LLC converter control method of the present invention;

[0041] Figure 5 It is a schematic diagram of working waveforms of an embodiment of a bidirectional LLC converter control method of the present invention. DETAILED DESCRIPTION

[0042] In order to have a clearer understanding of the technical features, purposes and effects of the present invention, specific embodiments of the present invention are now described in detail with reference to the accompanying drawings.

[0043] like Figure 1 , shows an embodiment of a bidirectional LLC converter in a bidirectional LLC converter control method of the present invention, Figure 2An embodiment of the bidirectional LLC converter control method of the present invention is shown. Figure 2 In the embodiment of the bidirectional LLC converter control method of the present invention shown in FIG. Figure 1 As shown, it includes a transformer, an LLC resonant circuit connected to the primary side of the transformer, a primary half-bridge circuit connected to the LLC resonant circuit and a secondary bridge circuit connected to the secondary side of the transformer; the secondary bridge circuit includes a first power tube, a second power tube, a third power tube and a fourth power tube, the first power tube is connected in series with the third power tube, the second power tube is connected in series with the fourth power tube, and the first power tube and the second power tube are the upper bridge arms of the secondary bridge circuit, and the third power tube and the fourth power tube are the lower bridge arms of the secondary bridge circuit; the primary half-bridge circuit includes a fifth power tube and a sixth power tube, the fifth power tube is connected in series with the sixth power tube, and the fifth power tube is the upper bridge arm of the primary half-bridge circuit, and the sixth power tube is the upper bridge arm of the primary half-bridge circuit. The control method includes: S1, when the secondary bridge circuit is connected to the power input, obtaining the target gain of the converter, and generating a first drive signal, a second drive signal, a third drive signal, a fourth drive signal, a fifth drive signal and a sixth drive signal according to the target gain; S2, driving the first power tube by the first drive signal, driving the fourth power tube by the fourth drive signal, and driving the fifth power tube by the fifth drive signal; S3, driving the second power tube by the second drive signal and the third power tube by the third drive signal, and driving the sixth power tube by the sixth drive signal; wherein the first drive signal is opposite to the second drive signal in phase, and the third drive signal is opposite to the fourth drive signal in phase.

[0044] Specifically, in the bidirectional LLC converter, the secondary side of the transformer T is connected to the secondary side bridge circuit, and the secondary side bridge circuit is a full-bridge circuit composed of a first power tube, namely, a power tube Q1, a second power tube, namely, a power tube Q2, a third power tube, namely, a power tube Q3, and a fourth power tube, namely, a power tube Q4. The primary side of the transformer is connected to the primary side half-bridge circuit through an LLC resonant circuit. The LLC resonant circuit may include a capacitor C1, a capacitor C2, and an inductor L, wherein the capacitor C1 and the capacitor C2 work together to form a resonant capacitor Cr of the resonant circuit, and the capacitor L is a resonant inductor Lr of the resonant circuit, and together with the self-contained excitation inductor Lm of the transformer T, forms an LLC resonant circuit. The primary side half-bridge circuit is a half-bridge circuit composed of a fifth power tube, namely, a power tube Q5, and a sixth power tube, namely, a power tube Q6. It is defined that when the power input is input from the primary side half-bridge circuit to the converter, the converter is in a forward working state, and at this time, after the power input passes through the primary side half-bridge circuit, the LLC resonant circuit and the transformer, the corresponding voltage output is obtained through the secondary side bridge circuit. When the power input is input from the secondary bridge circuit to the converter, the converter is in reverse working state. At this time, the power input passes through the secondary bridge circuit, transformer and LLC resonant circuit, and obtains the corresponding voltage output through the primary half-bridge circuit.

[0045] In the specific control process, when there is power input in the secondary bridge circuit, it can be determined that the converter is in the reverse working state at this time, and the specific working control process needs to be implemented according to the target gain of the converter. That is, the target gain corresponding to the converter is obtained. The relationship between the target gain and 1 is determined, for example, whether the target gain is greater than 1, less than 1 or equal to 1. Then the corresponding first drive signal, second drive signal, third drive signal, fourth drive signal, fifth drive signal and sixth drive signal are generated. Among them, the power tube Q1 is driven by the first drive signal, the power tube Q4 is driven by the fourth drive signal, and the power tube Q5 is driven by the fifth drive signal, and then the required voltage output is obtained in the primary half-bridge circuit of the converter. In the other half cycle, the power tube Q2 is driven by the second drive signal, the power tube Q3 is driven by the third drive signal, and the power tube Q6 is driven by the sixth drive signal. The second drive signal is opposite to the first drive signal in phase. By adjusting each drive signal, the voltage output of the primary half-bridge circuit can be greater than, equal to or less than the power input of the secondary bridge circuit, and finally different gain adjustments are achieved so that the actual gain meets the target gain.

[0046] In one embodiment, when the target gain is equal to 1, the first drive signal has the same phase as the fourth drive signal and the fifth drive signal; and the second drive signal has the same phase as the third drive signal and the sixth drive signal. Figure 3As shown. The first drive signal S1 has the same phase as the fourth drive signal S4, the first drive signal S1 has the same phase as the fifth drive signal S5, and similarly, in the other half of the cycle, the second drive signal has the same phase as the third drive signal and the sixth drive signal S6. When LLC operates at the resonant frequency and the duty cycle is 50%, the ideal value of the voltage gain is 1. Figure 3 The waveform has a gain of 1. The first drive signal S1 and the fourth drive signal S4 are exactly the same in phase, which is equivalent to a square wave with a 50% duty cycle as the excitation source of the secondary full bridge. The fifth drive signal S5 works in the synchronous rectification mode at this time, that is, in the overlapping area of ​​the first drive signal S1 and the fourth drive signal S4, the conduction loss is reduced, and finally the gain of the primary output relative to the secondary input is 1. Among them, ILr is used to indicate the current flowing through the resonant inductor Lr, and the change of this current can be used to indicate the output state of the primary side.

[0047] Further, when the target gain is equal to 1, the control method of this embodiment also includes: obtaining the resonant frequency of the LLC converter, and setting the driving frequency of the first drive signal and the second drive signal to the resonant frequency. That is, the LLC converter is set to work in the resonant working area, that is, the switching frequency of the switch tube Q1 and the switch tube Q2 is set to be the same as the resonant frequency of the LLC resonant circuit. It can be understood that because the driving signals of the switch tube Q1, the switch tube Q4 and the switch tube Q5 are the same, the corresponding switching frequencies of the switch tube Q1, the switch tube Q4 and the switch tube Q5 are also the same. Similarly, because the driving signals of the switch tube Q2, the switch tube Q3 and the switch tube Q6 are the same, the corresponding switching frequencies of the switch tube Q2, the switch tube Q3 and the switch tube Q6 are also the same.

[0048] In one embodiment, when the target gain is less than 1, the fourth drive signal is delayed by a first preset phase angle relative to the first drive signal, the fifth drive signal is turned on when the fourth drive signal is turned on, and is turned off when the first drive signal is turned off; the third drive signal is delayed by the first preset phase angle relative to the second drive signal, the sixth drive signal is turned on when the third drive signal is turned on, and is turned off when the second drive signal is turned off. Figure 4As shown, the fourth drive signal S4 has a certain delay in phase relative to the first drive signal S1, and the fifth drive signal S5 also has the same delay as the first drive signal S1, and the fifth drive signal S5 is turned off when the first drive signal S1 is turned off. Similarly, in the other half of the cycle, the third drive signal has the same phase delay relative to the second drive signal, and the sixth drive signal also has the same phase delay relative to the second drive signal, and is turned off when the second drive signal is turned off. When the phases of the first drive signal S1 and the fourth drive signal S4 overlap, they are equivalent to a square wave with a duty cycle of less than 50%. When the excitation source has a duty cycle of 50%, the gain is 1, so the gain is less than 1 at this time. The conduction time of the fifth drive signal S5 is the overlapping area of ​​the first drive signal S1 and the fourth drive signal S4. The conduction of the sixth drive signal S6 is the overlapping area of ​​the second drive signal and the third drive signal.

[0049] Furthermore, when the target gain is less than 1, the control method of this embodiment further includes: obtaining the resonant frequency of the LLC converter, and setting the driving frequency of the first drive signal and the second drive signal to n times the resonant frequency, where n is a constant greater than 1. That is, the LLC converter is set to work in the buck working area, that is, the switching frequency of the switch tube Q1 and the switch tube Q2 is set to be greater than the resonant frequency of the LLC resonant circuit. Similarly, the switching frequency of the switch tube Q2 and the switch tube Q3 is greater than the resonant frequency of the LLC resonant circuit.

[0050] In a specific embodiment, considering the reduction of switching loss and transformer circulating current, n can be selected as 1.3-1.7.

[0051] In one embodiment, when the target gain is greater than 1, the fourth drive signal has the same phase as the first drive signal, and the fifth drive signal is delayed by a second preset phase angle relative to the first drive signal; the third drive signal has the same phase as the second drive signal, and the sixth drive signal is delayed by the second preset phase angle relative to the second drive signal. Figure 5 As shown, the fourth drive signal S4 has the same phase as the first drive signal S1, and the fifth drive signal S5 has a certain phase delay with the first drive signal S1. Similarly, in the other half of the cycle, the third drive signal has the same phase as the second drive signal, and the sixth drive signal has the same phase delay relative to the second drive signal. Figure 5 The waveform is in boost mode. When the gain is greater than 1, the first drive signal S1 and the fourth drive signal S4 have the same phase, which is equivalent to a square wave with a 50% duty cycle as the excitation source of the secondary full bridge. The fifth drive signal S5 has a lag delay relative to the fourth drive signal S1, that is, in boost mode. The greater the lag delay, the greater the gain. Based on Figure 5, in the overlapping region of the first driving signal S1 and the fourth driving signal S4, there are two working states: when the fifth driving signal S5 is turned on, the sixth driving signal S6 is turned off, which is equivalent to the state of a gain of 1 mode. When the fifth driving signal S5 is turned off, the sixth driving signal S6 is turned on, and the voltage of the primary side of the transformer is commutated relative to the secondary side input, and the obtained output voltage value is Vout. At this time, the voltage across the transformer: (Vin * N) > Vout, and the energy flows from the secondary side to the primary side, realizing the step-up operation. At the same time, when the switching frequency of the switching tube is greater than the resonance point, the LLC operates in the inductive region, and the peak value of the current in the resonance cavity will be smaller than that at the resonance frequency. Operating at 1.3 - 1.7 times the resonance frequency is to reduce the peak current and reduce the loss. When (N * Vin) < Vout, the fifth driving signal S5 in the secondary half-bridge overlaps with the first driving signal S1, and there is a situation where energy flows back from the output to the input, that is, transformer circulating current. When the frequency is relatively high, since the control amount of the step-up is determined, the overlapping time of the fifth driving signal S5 and the first driving signal S1 becomes less, and the return power decreases. Among them, ILr is used to indicate the current flowing through the resonance inductor Lr, and the change of this current can be used to indicate the output state of the primary side.

[0052] Furthermore, the duty cycle of the first driving signal is equal to 50%, the duty cycle of the fifth driving signal is less than or equal to 50%, and the dead zone of the fifth driving signal is greater than the dead zone of the first driving signal. That is, the conduction time of the fifth driving signal S5 should be less than or equal to the conduction time of the first driving signal S1.

[0053] Furthermore, when the target gain is greater than 1, the control method of this embodiment further includes: obtaining the resonance frequency of the LLC converter, and setting the driving frequencies of the first driving signal and the second driving signal to n times the resonance frequency, where n is a constant greater than 1. That is, setting the LLC converter to operate in the step-up working area, that is, setting the switching frequencies of the switching tube Q1 and the switching tube Q2 to be greater than the resonance frequency of the LLC resonance circuit. Similarly, the switching frequencies of the switching tube Q2 and the switching tube Q3 are greater than the resonance frequency of the LLC resonance circuit. In a specific embodiment, considering reducing the switching loss and transformer circulating current, n can be selected as 1.3 - 1.7. When the switching frequency is greater than the resonance frequency of the resonance point, the LLC resonance circuit operates in the inductive region, and the peak value of the current in the resonance cavity of the LLC resonance circuit will be smaller than that at the resonance frequency. Setting the switching frequency to operate at 1.3 - 1.7 times the resonance frequency can reduce the peak current and further reduce the conversion loss.

[0054] In addition, in an embodiment of a bidirectional LLC converter control device of the present invention, the control device is used for a bidirectional LLC converter, the bidirectional LLC converter includes a transformer, an LLC resonant circuit connected to the primary side of the transformer, a primary half-bridge circuit connected to the LLC resonant circuit, and a secondary bridge circuit connected to the secondary side of the transformer; the secondary bridge circuit includes a first power tube, a second power tube, a third power tube, and a fourth power tube, the first power tube is connected in series with the third power tube, the second power tube is connected in series with the fourth power tube, and the first power tube and the second power tube are the upper bridge arm of the secondary bridge circuit, and the third power tube and the fourth power tube are the lower bridge arm of the secondary bridge circuit; the primary half-bridge circuit includes a fifth power tube and a sixth power tube, the fifth power tube is connected in series with the sixth power tube, and the fifth power tube is the upper bridge arm of the primary half-bridge circuit, and the sixth power tube is the upper bridge arm of the primary half-bridge circuit. The control device is used to execute the above bidirectional LLC converter control method.

[0055] Specifically, Figure 1 As shown, in the bidirectional LLC converter, the secondary side of the transformer T is connected to the secondary side bridge circuit, and the secondary side bridge circuit is a full-bridge circuit composed of a first power tube, i.e., power tube Q1, a second power tube, i.e., power tube Q2, a third power tube, i.e., power tube Q3, and a fourth power tube, i.e., power tube Q4. The primary side of the transformer is connected to the primary side half-bridge circuit through an LLC resonant circuit. The LLC resonant circuit may include that the primary side half-bridge circuit is a half-bridge circuit composed of a fifth power tube, i.e., power tube Q5, and a sixth power tube, i.e., power tube Q6. It is defined that when the power input is input from the primary side half-bridge circuit to the converter, the converter is in a forward working state, and at this time, the power input passes through the primary side half-bridge circuit, the LLC resonant circuit, and the transformer, and obtains a corresponding voltage output through the secondary side bridge circuit. When the power input is input from the secondary side bridge circuit to the converter, the converter is in a reverse working state, and at this time, the power input passes through the secondary side bridge circuit, the transformer, and the LLC resonant circuit, and obtains a corresponding voltage output through the primary side half-bridge circuit.

[0056] The control device is used to control the working process of each power tube in the bidirectional LLC converter. For example, the control device drives the working state of the corresponding power tube through a driving signal to achieve the required working voltage output. The specific control process can refer to the specific steps of the control method above, which will not be repeated here.

[0057] In addition, in an embodiment of a bidirectional LLC converter of the present invention, it includes: a controller and a transformer, an LLC resonant circuit connected to the primary side of the transformer, a primary half-bridge circuit connected to the LLC resonant circuit, and a secondary bridge circuit connected to the secondary side of the transformer; the secondary bridge circuit includes a first power tube, a second power tube, a third power tube and a fourth power tube, the first power tube is connected in series with the third power tube, the second power tube is connected in series with the fourth power tube, and the first power tube and the second power tube are the upper bridge arms of the secondary bridge circuit, and the third power tube and the fourth power tube are the lower bridge arms of the secondary bridge circuit; the primary half-bridge circuit includes a fifth power tube and a sixth power tube, the fifth power tube is connected in series with the sixth power tube, and the fifth power tube is the upper bridge arm of the primary half-bridge circuit, and the sixth power tube is the upper bridge arm of the primary half-bridge circuit; the controller is used to execute the above bidirectional LLC converter control method.

[0058] Specifically, Figure 1 As shown, in the bidirectional LLC converter, the secondary side of the transformer T is connected to the secondary side bridge circuit, and the secondary side bridge circuit is a full-bridge circuit composed of a first power tube, i.e., power tube Q1, a second power tube, i.e., power tube Q2, a third power tube, i.e., power tube Q3, and a fourth power tube, i.e., power tube Q4. The primary side of the transformer is connected to the primary side half-bridge circuit through an LLC resonant circuit. The LLC resonant circuit may include that the primary side half-bridge circuit is a half-bridge circuit composed of a fifth power tube, i.e., power tube Q5, and a sixth power tube, i.e., power tube Q6. It is defined that when the power input is input from the primary side half-bridge circuit to the converter, the converter is in a forward working state, and at this time, the power input passes through the primary side half-bridge circuit, the LLC resonant circuit, and the transformer, and obtains a corresponding voltage output through the secondary side bridge circuit. When the power input is input from the secondary side bridge circuit to the converter, the converter is in a reverse working state, and at this time, the power input passes through the secondary side bridge circuit, the transformer, and the LLC resonant circuit, and obtains a corresponding voltage output through the primary side half-bridge circuit.

[0059] The controller is used to control the working process of each power tube in the bidirectional LLC converter. For example, the controller drives the working state of the corresponding power tube through a driving signal to achieve the required working voltage output. The specific control process can refer to the specific steps of the control method above, which will not be repeated here.

[0060] It can be understood that the above embodiments only express the preferred implementation modes of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the patent scope of the present invention. It should be pointed out that, for ordinary technicians in this field, the above technical features can be freely combined without departing from the concept of the present invention, and several deformations and improvements can be made, which all belong to the protection scope of the present invention. Therefore, all equivalent changes and modifications made to the scope of the claims of the present invention should belong to the coverage of the claims of the present invention.

Claims

1. A bidirectional LLC converter control method, characterized in that: The bidirectional LLC converter comprises a transformer, an LLC resonant circuit connected to the primary side of the transformer, a primary half-bridge circuit connected to the LLC resonant circuit, and a secondary bridge circuit connected to the secondary side of the transformer; The secondary bridge circuit includes a first power tube, a second power tube, a third power tube and a fourth power tube, the first power tube is connected in series with the third power tube, the second power tube is connected in series with the fourth power tube, and the first power tube and the second power tube are upper bridge arms of the secondary bridge circuit, and the third power tube and the fourth power tube are lower bridge arms of the secondary bridge circuit; The primary half-bridge circuit includes a fifth power tube and a sixth power tube, the fifth power tube is connected in series with the sixth power tube, and the fifth power tube is an upper bridge arm of the primary half-bridge circuit, and the sixth power tube is an upper bridge arm of the primary half-bridge circuit; The control method comprises: When the secondary bridge circuit is connected to a power input, obtaining a target gain of the converter, and generating a first drive signal, a second drive signal, a third drive signal, a fourth drive signal, a fifth drive signal and a sixth drive signal according to the target gain; driving the first power tube by the first driving signal, driving the fourth power tube by the fourth driving signal, and driving the fifth power tube by the fifth driving signal; Drive the second power tube by the second driving signal, drive the third power tube by the third driving signal, and drive the sixth power tube by the sixth driving signal; The first driving signal and the second driving signal have opposite phases, and the third driving signal and the fourth driving signal have opposite phases.

2. The bidirectional LLC converter control method according to claim 1, characterized in that: When the target gain is equal to 1, The first drive signal has the same phase as the fourth drive signal and the fifth drive signal; The second driving signal has the same phase as the third driving signal and the sixth driving signal.

3. The bidirectional LLC converter control method according to claim 2, characterized in that: The method further comprises: The resonant frequency of the LLC converter is obtained, and the driving frequencies of the first driving signal and the second driving signal are set to the resonant frequency.

4. The bidirectional LLC converter control method according to claim 1, characterized in that: When the target gain is less than 1, The fourth driving signal is delayed by a first preset phase angle relative to the first driving signal, and the fifth driving signal is turned on when the fourth driving signal is turned on, and is turned off when the first driving signal is turned off; The third driving signal is delayed by the first preset phase angle relative to the second driving signal. The sixth driving signal is turned on when the third driving signal is turned on, and is turned off when the second driving signal is turned off.

5. The bidirectional LLC converter control method according to claim 1, characterized in that: When the target gain is greater than 1, The fourth driving signal has the same phase as the first driving signal, and the fifth driving signal is delayed by a second preset phase angle relative to the first driving signal; The third driving signal has the same phase as the second driving signal, and the sixth driving signal is delayed by the second preset phase angle relative to the second driving signal.

6. The bidirectional LLC converter control method according to claim 5, characterized in that: The duty cycle of the first driving signal is equal to 50%, the duty cycle of the fifth driving signal is less than or equal to 50%, and the dead zone of the fifth driving signal is greater than the dead zone of the first driving signal.

7. The bidirectional LLC converter control method according to claim 4 or 5, characterized in that: The method further comprises: The resonant frequency of the LLC converter is obtained, and the driving frequencies of the first driving signal and the second driving signal are set to n times the resonant frequency, where n is a constant greater than 1.

8. The bidirectional LLC converter control method according to claim 7, characterized in that: The value range of n is greater than 1.3 and less than 1.

7.

9. A bidirectional LLC converter control device, characterized in that: For a bidirectional LLC converter, the bidirectional LLC converter comprises a transformer, an LLC resonant circuit connected to the primary side of the transformer, a primary half-bridge circuit connected to the LLC resonant circuit, and a secondary bridge circuit connected to the secondary side of the transformer; The secondary bridge circuit includes a first power tube, a second power tube, a third power tube and a fourth power tube, the first power tube is connected in series with the third power tube, the second power tube is connected in series with the fourth power tube, and the first power tube and the second power tube are upper bridge arms of the secondary bridge circuit, and the third power tube and the fourth power tube are lower bridge arms of the secondary bridge circuit; The primary half-bridge circuit includes a fifth power tube and a sixth power tube, the fifth power tube is connected in series with the sixth power tube, and the fifth power tube is an upper bridge arm of the primary half-bridge circuit, and the sixth power tube is an upper bridge arm of the primary half-bridge circuit; The control device is used to execute the bidirectional LLC converter control method according to any one of claims 1 to 8.

10. A bidirectional LLC converter, characterized in that: include: A controller and a transformer, an LLC resonant circuit connected to the primary side of the transformer, a primary half-bridge circuit connected to the LLC resonant circuit, and a secondary bridge circuit connected to the secondary side of the transformer; The secondary bridge circuit includes a first power tube, a second power tube, a third power tube and a fourth power tube, the first power tube is connected in series with the third power tube, the second power tube is connected in series with the fourth power tube, and the first power tube and the second power tube are upper bridge arms of the secondary bridge circuit, and the third power tube and the fourth power tube are lower bridge arms of the secondary bridge circuit; The primary half-bridge circuit includes a fifth power tube and a sixth power tube, the fifth power tube is connected in series with the sixth power tube, and the fifth power tube is an upper bridge arm of the primary half-bridge circuit, and the sixth power tube is an upper bridge arm of the primary half-bridge circuit; The controller is used to execute the bidirectional LLC converter control method according to any one of claims 1 to 8.

Images