Bidirectional LLC converter control method and device and bidirectional LLC converter

Abstract

The application 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 half-bridge circuit and a secondary bridge circuit; the secondary bridge circuit comprises first, second, third and fourth power tubes, and the primary half-bridge circuit comprises fifth and sixth power tubes; the method comprises the following steps: when the secondary bridge circuit is connected with a power input, the target gain of the converter is obtained, and the first, second, third, fourth, fifth and sixth driving signals are generated according to the target gain; the first, fourth, fifth, second, third and sixth power tubes are driven by the first, fourth, fifth, second, third and sixth driving signals respectively; the phase of the first driving signal is opposite to that of the second driving signal, and the phase of the third driving signal is opposite to that of the fourth driving signal. The application can meet the requirements of various application scenarios.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of converter, more particularly, to a bidirectional LLC converter control method, device and bidirectional LLC converter. BACKGROUND

[0002] In the traditional bidirectional LLC converter, the gain of the system is usually adjusted by adjusting the switching frequency of each power tube, and the ultimate goal is to make the conversion gain as large as possible. However, in actual application, there are different requirements for the conversion gain, so how to set the working state of the converter to make the gain of the converter meet the actual demand has become increasingly important. SUMMARY

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

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

[0005] The secondary side bridge circuit includes a first power tube, a second power tube, a third power tube and a fourth power tube, the first power tube and the third power tube are connected in series, the second power tube and the fourth power tube are connected in series, and the first power tube and the second power tube are the upper bridge arm of the secondary side bridge circuit, and the third power tube and the fourth power tube are the lower bridge arm of the secondary side bridge circuit.

[0006] The primary side half-bridge circuit includes a fifth power tube and a sixth power tube, the fifth power tube and the sixth power tube are connected in series, and the fifth power tube is the upper bridge arm of the primary side half-bridge circuit, and the sixth power tube is the lower bridge arm of the primary side half-bridge circuit.

[0007] The control method includes:

[0008] When the secondary side bridge circuit is connected to the power input, the target gain of the converter is obtained, and the first driving signal, the second driving signal, the third driving signal, the fourth driving signal, the fifth driving signal and the sixth driving signal are generated according to the target gain;

[0009] The first power tube is driven by the first driving signal, the fourth power tube is driven by the fourth driving signal, and the fifth power tube is driven by the fifth driving signal.

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

[0011] wherein the phase of the first driving signal is opposite to the phase of the second driving signal, and the phase of the third driving signal is opposite to the phase of the fourth driving signal.

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

[0013] the phase of the first driving signal is the same as the phase of the fourth driving signal and the phase of the fifth driving signal;

[0014] the phase of the second driving signal is the same as the phase of the third driving signal and the phase of the sixth driving signal.

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

[0016] obtaining a resonant frequency of the LLC converter, and setting the driving frequency of the first driving signal and the second driving signal as the resonant frequency.

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

[0018] the fourth driving signal is delayed by a first preset phase angle with respect 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 with respect to the second driving signal, and 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, when the target gain is greater than 1,

[0021] the fourth driving signal is the same as the first driving signal in phase, and the fifth driving signal is delayed by a second preset phase angle with respect to the first driving signal;

[0022] the third driving signal is the same as the second driving signal in phase, and the sixth driving signal is delayed by the second preset phase angle with respect to the second driving signal.

[0023] Preferably, in the bidirectional LLC converter control method, 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 time of the fifth driving signal is greater than the dead time of the first driving signal.

[0024] Preferably, in the bidirectional LLC converter control method, 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 of the resonant frequency, where n is a constant greater than 1.

[0026] Preferably, in the bidirectional LLC converter control method, the value of n ranges from greater than 1.3 to less than 1.7.

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

[0028] The secondary side bridge circuit comprises a first power tube, a second power tube, a third power tube, and a fourth power tube, the first power tube and the third power tube are connected in series, the second power tube and the fourth power tube are connected in series, and the first power tube and the second power tube are the upper bridge arm of the secondary side bridge circuit, and the third power tube and the fourth power tube are the lower bridge arm of the secondary side bridge circuit.

[0029] The primary side half-bridge circuit comprises a fifth power tube and a sixth power tube, the fifth power tube and the sixth power tube are connected in series, and the fifth power tube is the upper bridge arm of the primary side half-bridge circuit, and the sixth power tube is the lower bridge arm of the primary side half-bridge circuit.

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

[0031] The application also constructs a bidirectional LLC converter, which comprises a controller and a transformer, an LLC resonant circuit connected to the primary side of the transformer, a primary side half-bridge circuit connected to the LLC resonant circuit, and a secondary side bridge circuit connected to the secondary side of the transformer.

[0032] The auxiliary side bridge circuit comprises a first power tube, a second power tube, a third power tube and a fourth power tube, the first power tube and the third power tube are connected in series, the second power tube and the fourth power tube are connected in series, and the first power tube and the second power tube are upper bridge arms of the auxiliary side bridge circuit, and the third power tube and the fourth power tube are lower bridge arms of the auxiliary side bridge circuit;

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

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

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

[0036] The present application will be further described below in conjunction with the drawings and embodiments, wherein:

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

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

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

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

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

[0042] In order to have a clearer understanding of the technical features, objectives and effects of the present application, the specific embodiments of the present application will be described in detail with reference to the drawings.

[0043] As Figure 1 , an embodiment of the bidirectional LLC converter in the bidirectional LLC converter control method of the present application is shown, 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, the bidirectional LLC converter is as follows: Figure 1 As shown, the circuit includes a transformer, an LLC resonant circuit connected to the primary side of the transformer, a primary-side half-bridge circuit connected to the LLC resonant circuit, and a secondary-side bridge circuit connected to the secondary side of the transformer. The secondary-side bridge circuit includes a first power transistor, a second power transistor, a third power transistor, and a fourth power transistor. The first power transistor and the third power transistor are connected in series, and the second power transistor and the fourth power transistor are connected in series. The first power transistor and the second power transistor form the upper arm of the secondary-side bridge circuit, and the third power transistor and the fourth power transistor form the lower arm of the secondary-side bridge circuit. The primary-side half-bridge circuit includes a fifth power transistor and a sixth power transistor. The fifth power transistor and the sixth power transistor are connected in series. The fifth power transistor forms the upper arm of the primary-side half-bridge circuit, and the sixth power transistor forms the lower arm of the primary-side 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 transistor with the first drive signal, driving the fourth power transistor with the fourth drive signal, and driving the fifth power transistor with the fifth drive signal; S3, driving the second power transistor with the second drive signal, driving the third power transistor with the third drive signal, and driving the sixth power transistor with the sixth drive signal; wherein the first drive signal and the second drive signal are out of phase, and the third drive signal and the fourth drive signal are out of 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, 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 the LLC resonant circuit. The LLC resonant circuit can include a capacitor C1, a capacitor C2, and an inductor L, wherein the capacitor C1 and the capacitor C2 jointly form a resonant capacitor Cr of the resonant circuit, and the capacitor L is a resonant inductor Lr of the resonant circuit, which, together with the self-excitation inductor Lm of the transformer T, forms the LLC resonant circuit. 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 then the corresponding voltage output is obtained 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 then the corresponding voltage output is obtained through the primary side half-bridge circuit.

[0045] In the specific control process, when there is a power input in the secondary side bridge circuit, it can be judged that the converter is in a reverse working state at this time, and the specific working control process needs to be realized 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 judged, 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 side 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 phase of the second drive signal is opposite to that of the first drive signal. By adjusting each drive signal, the voltage output of the primary side half-bridge circuit can be greater than, equal to, or less than the power input of the secondary side bridge circuit, and finally different gain adjustments are realized, so that the actual gain meets the target gain.

[0046] In an embodiment, when the target gain is equal to 1, the phase of the first drive signal is the same as that of the fourth drive signal and the fifth drive signal; and the phase of the second drive signal is the same as that of the third drive signal and the sixth drive signal. Figure 3The first driving signal S1 is the same as the fourth driving signal S4, and the first driving signal S1 is the same as the fifth driving signal S5. In the other half of the period, the second driving signal is the same as the third driving signal and the sixth driving signal S6. When the LLC operates at the resonant frequency and the duty cycle is 50%, the ideal value of the voltage gain is 1. Figure 3 The first driving signal S1 and the fourth driving signal S4 are completely the same in phase, and the excitation source of the secondary side full-bridge is equivalent to a square wave with a duty cycle of 50%. The fifth driving signal S5 operates in the synchronous rectification mode at this time, that is, in the overlapping area of the first driving signal S1 and the fourth driving signal S4, the on-state loss is reduced, and finally the gain of the primary side output relative to the secondary side input is 1. Wherein ILr is used to indicate the current flowing through the resonant inductor Lr, and the change of the 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 the embodiment further comprises: obtaining the resonant frequency of the LLC converter, and setting the driving frequency of the first driving signal and the second driving signal as the resonant frequency. That is, the LLC converter is set to operate in the resonant operating area, that is, the switching frequency of the switch tube Q1 and the switch tube Q2 is 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 switching frequencies of the corresponding 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 switching frequencies of the corresponding switch tube Q2, the switch tube Q3 and the switch tube Q6 are also the same.

[0048] In an embodiment, 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, and 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. As Figure 4As shown, the fourth driving signal S4 has a certain phase delay relative to the first driving signal S1, and the fifth driving signal S5 also has the same phase delay relative to the first driving signal S1, and the fifth driving signal S5 is turned off when the first driving signal S1 is turned off. Similarly, in the other half of the period, the third driving signal has the same phase delay relative to the second driving signal, and the sixth driving signal also has the same phase delay relative to the second driving signal and is turned off when the second driving signal is turned off. When the phase of the first driving signal S1 and the fourth driving signal S4 overlaps, it is equivalent to a square wave with a duty cycle of less than 50%, and the gain is 1 when the excitation source is 50% duty cycle. Therefore, the gain is less than 1 at this time. The on time of the fifth driving signal S5 is the overlapping area of the first driving signal S1 and the fourth driving signal S4. The on time of the sixth driving signal S6 is the overlapping area of the second driving signal and the third driving signal.

[0049] Further, when the target gain is less than 1, the control method of the embodiment further comprises: obtaining the resonant frequency of the LLC converter, and setting the driving frequencies of the first driving signal and the second driving signal to be n times of the resonant frequency, where n is a constant greater than 1. That is, the LLC converter is set to operate in the step-down operating region, that is, the switching frequencies of the switch Q1 and the switch Q2 are set to be greater than the resonant frequency of the LLC resonant circuit. Similarly, the switching frequencies of the switch Q2 and the switch Q3 are greater than the resonant frequency of the LLC resonant circuit.

[0050] In a specific embodiment, n can be selected to be 1.3-1.7 in consideration of reducing switching loss and transformer circulating current.

[0051] In an embodiment, 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. As Figure 5 As shown, the fourth driving signal S4 has the same phase as the first driving signal S1, and the fifth driving signal S5 has a certain phase delay relative to the first driving signal S1. Similarly, in the other half of the period, the third driving signal has the same phase as the second driving signal, and the sixth driving signal has the same phase delay relative to the second driving signal. Figure 5 For the boost mode waveform. When the gain is greater than 1, the first driving signal S1 and the fourth driving signal S4 have the same phase, and the excitation source of the secondary side full-bridge is a square wave with a duty cycle of 50%. The fifth driving signal S5 has a lag delay relative to the fourth driving signal S1, that is, the boost operating mode, and the larger the lag delay, the greater the gain. Based on Figure 5In the region where the first driving signal S1 and the fourth driving signal S4 overlap, there are two working states: when the fifth driving signal S5 is on and the sixth driving signal S6 is off, it is equivalent to the state of the gain being 1 mode. When the fifth driving signal S5 is off and the sixth driving signal S6 is on, the primary side voltage of the transformer is reversed relative to the input of the secondary side, and the output voltage value obtained is Vout. At this time, the voltage across the transformer is (Vin*N)>Vout, and energy flows from the secondary side to the primary side, realizing step-up operation. At the same time, when the switching frequency of the switch tube is greater than the resonance point, the LLC works in the inductive interval, and the current peak value of the resonance cavity of the LLC is smaller than that at the resonance frequency. Working at 1.3-1.7 times the resonance frequency can reduce the current peak value and reduce the loss. When (N*Vin)<Vout, the fifth driving signal S5 in the secondary side half-bridge overlaps with the first driving signal S1, and there is a case of energy flowing back from the output to the input, i.e. transformer circulation. When the frequency is higher, the control amount of the step-up is determined, so the overlap time of the fifth driving signal S5 and the first driving signal S1 decreases, and the backflow power decreases. Wherein ILr is used to indicate the current flowing through the resonance inductor Lr, and the output state of the primary side can be indicated by the change of the current.

[0052] Further, 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 on time of the fifth driving signal S5 should be less than or equal to the on time of the first driving signal S1.

[0053] Further, when the target gain is greater than 1, the control method of the embodiment further comprises: obtaining the resonance frequency of the LLC converter, and setting the driving frequency of the first driving signal and the second driving signal to be n times of the resonance frequency, wherein n is a constant greater than 1. That is, the LLC converter is set to work in the step-up working area, that is, the switching frequency of the switch tube Q1 and the switch tube Q2 is greater than the resonance frequency of the LLC resonance circuit. Similarly, the switching frequency of the switch tube Q2 and the switch tube Q3 is greater than the resonance frequency of the LLC resonance circuit. In a specific embodiment, considering reducing switching loss and transformer circulation, n can be selected to be 1.3-1.7. When the switching frequency is greater than the resonance frequency of the resonance point, the LLC resonance circuit works in the inductive interval, and the current peak value of the resonance cavity of the LLC resonance circuit is smaller than that at the resonance frequency. Setting the switching frequency to work at 1.3-1.7 times the resonance frequency can reduce the current peak value and further reduce the conversion loss.

[0054] In another embodiment of the 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-side half-bridge circuit connected to the LLC resonant circuit, and a secondary-side bridge circuit connected to the secondary side of the transformer. The secondary-side bridge circuit includes a first power transistor, a second power transistor, a third power transistor, and a fourth power transistor. The first power transistor and the third power transistor are connected in series, and the second power transistor and the fourth power transistor are connected in series. The first power transistor and the second power transistor form the upper arm of the secondary-side bridge circuit, and the third power transistor and the fourth power transistor form the lower arm of the secondary-side bridge circuit. The primary-side half-bridge circuit includes a fifth power transistor and a sixth power transistor. The fifth power transistor and the sixth power transistor are connected in series. The fifth power transistor forms the upper arm of the primary-side half-bridge circuit, and the sixth power transistor forms the lower arm of the primary-side half-bridge circuit. The control device is used to execute the above-described bidirectional LLC converter control method.

[0055] Specifically, such as Figure 1 As shown, in the bidirectional LLC converter, the secondary side of transformer T is connected to a secondary bridge circuit, which is a full-bridge circuit composed of power transistors Q1, Q2, Q3, and Q4. The primary side of the transformer is connected to a primary half-bridge circuit via an LLC resonant circuit. The LLC resonant circuit may include a primary half-bridge circuit composed of power transistors Q5 and Q6. It is defined that when the power input is input from the primary half-bridge circuit to the converter, the converter operates in the forward direction. In this case, the power input passes through the primary half-bridge circuit, the LLC resonant circuit, and the transformer, and then through the secondary bridge circuit to obtain the corresponding voltage output. When the power input is input from the secondary bridge circuit to the converter, the converter operates in the reverse direction. In this case, the power input passes through the secondary bridge circuit, the transformer, and the LLC resonant circuit, and then through the primary half-bridge circuit to obtain the corresponding voltage output.

[0056] The control unit is used to control the operation of each power transistor in the bidirectional LLC converter. For example, the control unit drives the corresponding power transistor's operating state through drive signals to achieve the required operating voltage output. The specific control process can be found in the steps of the control method described above, and will not be repeated here.

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

[0058] Specifically, such as Figure 1 As shown, in the bidirectional LLC converter, the secondary side of transformer T is connected to a secondary bridge circuit, which is a full-bridge circuit composed of power transistors Q1, Q2, Q3, and Q4. The primary side of the transformer is connected to a primary half-bridge circuit via an LLC resonant circuit. The LLC resonant circuit may include a primary half-bridge circuit composed of power transistors Q5 and Q6. It is defined that when the power input is input from the primary half-bridge circuit to the converter, the converter operates in the forward direction. In this case, the power input passes through the primary half-bridge circuit, the LLC resonant circuit, and the transformer, and then through the secondary bridge circuit to obtain the corresponding voltage output. When the power input is input from the secondary bridge circuit to the converter, the converter operates in the reverse direction. In this case, the power input passes through the secondary bridge circuit, the transformer, and the LLC resonant circuit, and then through the primary half-bridge circuit to obtain the corresponding voltage output.

[0059] The controller is used to control the operation of each power transistor in the bidirectional LLC converter. For example, the controller drives the corresponding power transistor's operating state through drive signals to achieve the required operating voltage output. The specific control process can be found in the steps of the control method described above, and will not be repeated here.

[0060] It can be understood that the above embodiments only express the preferred embodiments of the present application, the description is more specific and detailed, but it cannot be understood as the limitation of the patent scope of the present application; it should be pointed out that for ordinary skilled in the art, the above technical features can be freely combined without departing from the concept of the present application, and several modifications and improvements can be made, which belong to the protection scope of the present application; therefore, any equivalent transformation and modification made with the patent claim scope of the present application shall belong to the coverage of the patent claim of the present application.

Claims

1. A bidirectional LLC converter control method, characterized by, The bidirectional LLC converter comprises a transformer, an LLC resonant circuit connected to a primary side of the transformer, a primary side half-bridge circuit connected to the LLC resonant circuit, and a secondary side bridge circuit connected to a secondary side of the transformer; The secondary side bridge circuit comprises a first power tube, a second power tube, a third power tube and a fourth power tube, the first power tube and the third power tube are connected in series, the second power tube and the fourth power tube are connected in series, and the first power tube and the second power tube are an upper bridge arm of the secondary side bridge circuit, and the third power tube and the fourth power tube are a lower bridge arm of the secondary side bridge circuit; The primary side half-bridge circuit comprises a fifth power tube and a sixth power tube, the fifth power tube and the sixth power tube are connected in series, and the fifth power tube is an upper bridge arm of the primary side half-bridge circuit, and the sixth power tube is a lower bridge arm of the primary side half-bridge circuit; The control method comprises: When the secondary side bridge circuit is connected to a power supply input, a target gain of the converter is obtained, and first, second, third, fourth, fifth and sixth drive signals are generated according to the target gain; The first drive signal is used to drive the first power tube, the fourth drive signal is used to drive the fourth power tube, and the fifth drive signal is used to drive the fifth power tube; The second drive signal is used to drive the second power tube, the third drive signal is used to drive the third power tube, and the sixth drive signal is used to drive the sixth power tube; The phase of the first drive signal is opposite to that of the second drive signal, and the phase of the third drive signal is opposite to that of the fourth drive signal; 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, and 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, and 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.

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

3. The bidirectional LLC converter control method of claim 2, wherein, The method further comprises: a resonant frequency of the LLC converter is obtained, and the driving frequency of the first drive signal and the second drive signal is set as the resonant frequency.

4. The bidirectional LLC converter control method of claim 1, wherein, When the target gain is greater than 1, the phase of the fourth drive signal is the same as that of the first drive signal, and the fifth drive signal is delayed by a second preset phase angle relative to the first drive signal; the phase of the third drive signal is the same as that of the second drive signal, and the sixth drive signal is delayed by the second preset phase angle relative to the second drive signal.

5. The bidirectional LLC converter control method of claim 4, wherein, 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.

6. The bidirectional LLC converter control method of claim 1, wherein, 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 of the resonant frequency, wherein n is a constant greater than 1.

7. The bidirectional LLC converter control method of claim 6, wherein, The value of n ranges from greater than 1.3 to less than 1.

7.

8. A bidirectional LLC converter control device, characterized by, A bidirectional LLC converter comprises a transformer, an LLC resonant circuit connected to the primary side of the transformer, a primary side half-bridge circuit connected to the LLC resonant circuit, and a secondary side bridge circuit connected to the secondary side of the transformer. The secondary side bridge circuit comprises a first power tube, a second power tube, a third power tube, and a fourth power tube, the first power tube and the third power tube are connected in series, the second power tube and the fourth power tube are connected in series, and the first power tube and the second power tube are the upper bridge arm of the secondary side bridge circuit, and the third power tube and the fourth power tube are the lower bridge arm of the secondary side bridge circuit. The primary side half-bridge circuit comprises a fifth power tube and a sixth power tube, the fifth power tube and the sixth power tube are connected in series, and the fifth power tube is the upper bridge arm of the primary side half-bridge circuit, and the sixth power tube is the lower bridge arm of the primary side half-bridge circuit. The control device is used to perform the bidirectional LLC converter control method according to any one of claims 1 to 7.

9. A bidirectional LLC converter characterized by, Comprise: A controller and a transformer, an LLC resonant circuit connected to the primary side of the transformer, a primary side half-bridge circuit connected to the LLC resonant circuit, and a secondary side bridge circuit connected to the secondary side of the transformer. The secondary side bridge circuit comprises a first power tube, a second power tube, a third power tube, and a fourth power tube, the first power tube and the third power tube are connected in series, the second power tube and the fourth power tube are connected in series, and the first power tube and the second power tube are the upper bridge arm of the secondary side bridge circuit, and the third power tube and the fourth power tube are the lower bridge arm of the secondary side bridge circuit. The primary side half-bridge circuit comprises a fifth power tube and a sixth power tube, the fifth power tube and the sixth power tube are connected in series, and the fifth power tube is the upper bridge arm of the primary side half-bridge circuit, and the sixth power tube is the lower bridge arm of the primary side half-bridge circuit. The controller is used to perform the bidirectional LLC converter control method according to any one of claims 1 to 7.

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