LLC current sharing control method and charging device

Abstract

The invention provides an LLC current sharing control method and charging equipment. The control method comprises the following steps: acquiring a working current of a first LLC as a first current, acquiring a working current of a second LLC as a second current, and determining a current sharing control quantity according to the first current and the second current; modulating the current-sharing control quantity to obtain a current-sharing modulation quantity; adjusting the original PWM wave of at least one switch tube in the first LLC and the second LLC according to the current-sharing modulation quantity to obtain a target PWM wave of the corresponding switch tube; and adopting the target PWM wave to drive the corresponding switch tube to act, so that the first LLC and the second LLC are current-sharing. The current-sharing modulation quantity is generated according to the working current of the two LLC circuits and directly acts on the original PWM waves, the adjusting speed is high, and the current-sharing effect is good.

Description

Technical Field

[0001] The present invention relates to the field of power supply technology, and in particular to an LLC current sharing control method and charging equipment. Background Art

[0002] LLC resonant converter has the advantages of high power density and easy soft switching, and is widely used in power supplies. Usually, two LLC resonant converters are connected in parallel or in series to form a dual LLC circuit to meet different needs.

[0003] Affected by factors such as manufacturing process and natural environment, it is difficult for the resonant device parameters of the two LLC circuits to remain consistent, which in turn leads to inconsistent load currents of the two LLC circuits, seriously affecting the reliability and life of the LLC resonant converter.

[0004] In the prior art, current balancing can be performed through virtual impedance, but the current balancing effect is not good and the adjustment speed is slow. Summary of the invention

[0005] The embodiment of the present invention provides an LLC current sharing control method and a charging device to solve the problems of slow adjustment speed and poor current sharing effect of the current sharing method in the prior art.

[0006] In a first aspect, an embodiment of the present invention provides an LLC current sharing control method, which is applied to a dual-channel LLC circuit; the dual-channel LLC circuit includes: a first LLC and a second LLC; the output end of the first LLC is connected in parallel or in series with the output end of the second LLC; the control method includes: Acquire the working current of the first LLC as the first current, acquire the working current of the second LLC as the second current, and determine the current sharing control amount according to the first current and the second current; Modulating the current sharing control amount to obtain the current sharing modulation amount; After adjusting the original PWM wave of at least one switch tube in the first LLC and the second LLC according to the current sharing modulation amount, a target PWM wave of the corresponding switch tube is obtained; The target PWM wave is used to drive the corresponding switch tube to operate, so that the first LLC and the second LLC have equal current.

[0007] Optionally, after adjusting the original PWM wave of at least one switch tube in the first LLC and the second LLC according to the current sharing modulation amount, obtaining a target PWM wave of the corresponding switch tube includes: Generate a current sharing PWM wave of each switch tube in the first LLC and a current sharing PWM wave of each switch tube in the second LLC according to the current sharing modulation amount; For any switch tube in the first LLC and the second LLC, the original PWM wave of the switch tube is superimposed with the current-sharing PWM wave of the switch tube to obtain the target PWM wave of the switch tube.

[0008] Optionally, determining the current sharing control amount according to the first current and the second current may include: Subtracting the second current from the first current to obtain a first current difference; The first current difference is input into the first PI controller and limited to obtain the current sharing control amount.

[0009] Optionally, the first LLC is a full-bridge LLC, including: a first front bridge arm and a first rear bridge arm connected in parallel; the second LLC is a full-bridge LLC, including: a second front bridge arm and a second rear bridge arm connected in parallel; generating a current-sharing PWM wave of each switch tube in the first LLC and a current-sharing PWM wave of each switch tube in the second LLC according to the current-sharing modulation amount, including: Generate a first reference PWM wave according to the current sharing modulation amount; The first reference PWM wave is inverted as the current-sharing PWM wave of the upper tube and the lower tube of the first front bridge arm; the current-sharing PWM wave of the upper tube and the lower tube of the first rear bridge arm are both set to 0; The first reference PWM wave is used as the current-sharing PWM wave of the upper tube and the lower tube of the second front bridge arm; the current-sharing PWM waves of the upper tube and the lower tube of the second rear bridge arm are both set to 0.

[0010] Optionally, the current sharing control amount includes: a first current sharing control amount and a second current sharing control amount; the current sharing modulation amount includes: a first current sharing modulation amount and a second current sharing modulation amount; and determining the current sharing control amount according to the first current and the second current includes: Calculating a current average of the first current and the second current; Subtract the current mean from the first current to obtain a second current difference; Inputting the second current difference into the second PI controller and limiting the amplitude to obtain a first current sharing control amount; Subtract the current mean from the second current to obtain a third current difference; Inputting the third current difference into a third PI controller and limiting the amplitude thereof to obtain a second current sharing control amount; The current sharing control amount is modulated to obtain the current sharing modulation amount, including: Modulating the first current sharing control amount to obtain a first current sharing modulation amount; The second current sharing control amount is modulated to obtain a second current sharing modulation amount.

[0011] Optionally, the first LLC is a full-bridge LLC, including: a first front bridge arm and a first rear bridge arm connected in parallel; the second LLC is a full-bridge LLC, including: a second front bridge arm and a second rear bridge arm connected in parallel; generating a current-sharing PWM wave of each switch tube in the first LLC and a current-sharing PWM wave of each switch tube in the second LLC according to the current-sharing modulation amount, including: Generate a second reference PWM wave according to the first current sharing modulation amount; The second reference PWM wave is inverted as the current-sharing PWM wave of the upper tube and the lower tube of the first front bridge arm; the current-sharing PWM wave of the upper tube and the lower tube of the first rear bridge arm are both set to 0; Generate a third reference PWM wave according to the second current sharing modulation amount; The third reference PWM wave is inverted as the current-sharing PWM wave of the upper tube and the lower tube of the second front bridge arm; the current-sharing PWM waves of the upper tube and the lower tube of the second rear bridge arm are both set to 0.

[0012] Optionally, the above method further includes: Obtain the time corresponding to the rising edge of the upper tube of the first front bridge arm in the current cycle, recorded as the first time; Obtain a moment corresponding to a falling edge of the lower tube of the first front bridge arm that is closest to the first moment and before the first moment, and record it as a second moment; If the difference between the second moment and the first moment is greater than the dead zone duration, the rising edge of the upper tube of the first front bridge arm and the rising edge of the lower tube of the first front bridge arm are both moved forward by a first preset time duration; wherein the first preset time duration is equal to the first moment minus the second moment minus the dead zone duration.

[0013] Optionally, before obtaining the working current of the first LLC as the first current, obtaining the working current of the second LLC as the second current, and determining the current sharing control amount according to the first current and the second current, the method further includes: Obtain the output power of the dual-channel LLC circuit in real time; When it is detected that the output power of the dual-channel LLC circuit is greater than the first preset power, the operating current of the first LLC is obtained as the first current, the operating current of the second LLC is obtained as the second current, and the current sharing control amount is determined according to the first current and the second current, and the target PWM wave is used to drive the corresponding switch tube to operate, so that the first LLC and the second LLC share the current.

[0014] Optionally, the above method further includes: When it is detected that the output power of the dual-channel LLC circuit is less than the second preset power, the current sharing modulation amount is set to 0; Among them, the first preset power is greater than the second preset power; when the current sharing modulation amount is 0, the target PWM wave is the same as the original PWM wave.

[0015] In a second aspect, an embodiment of the present invention provides a charging device, comprising: at least two dual-path LLC circuits as provided in the first aspect of the embodiment of the present invention; output ends of each dual-path LLC circuit are connected in series or in parallel.

[0016] The embodiment of the present invention provides an LLC current sharing control method and a charging device. The LLC current sharing control method is applied to a dual-channel LLC circuit; the dual-channel LLC circuit includes: a first LLC and a second LLC; the output end of the first LLC is connected in parallel or in series with the output end of the second LLC; the control method includes: obtaining the working current of the first LLC as the first current, obtaining the working current of the second LLC as the second current, and determining the current sharing control amount according to the first current and the second current; modulating the current sharing control amount to obtain the current sharing modulation amount; adjusting the original PWM wave of at least one switch tube in the first LLC and the second LLC according to the current sharing modulation amount, and obtaining the target PWM wave of the corresponding switch tube; using the target PWM wave to drive the corresponding switch tube to act, so that the first LLC and the second LLC share the current.

[0017] The technical effects of the embodiments of the present invention include: (1) The working currents of the two LLC circuits are sampled to determine the current sharing control amount and generate the current sharing modulation amount, and the current sharing modulation amount is directly used to adjust the PWM wave of the switch tubes in the two LLC circuits. Compared with the technical solution in the prior art that acts on the front-end loop for adjustment, the embodiment of the present invention directly adjusts the PWM wave, which has a direct effect, a fast current sharing speed, and a good current sharing effect.

[0018] (2) Only the front bridge arm is superimposed with the current-sharing PWM wave, while the rear bridge arm is not superimposed. This effectively reduces circuit losses while ensuring the current-sharing effect.

[0019] (3) In the embodiment of the present invention, a power limit is set for starting the current sharing. When the power is relatively low, the current sharing is not started, thereby further reducing the circuit loss without affecting the normal operation of the circuit.

[0020] (4) The upper tube and the lower tube of the first front bridge arm or the second front bridge arm are phase-shifted so that only the dead time is retained between the upper tube and the lower tube, which can effectively reduce circuit loss. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0022] Figure 1is a circuit schematic diagram of a dual-path LLC circuit provided by an embodiment of the present invention; Figure 2 is a flow chart of an implementation of an LLC current sharing control method provided by an embodiment of the present invention; Figure 3 is a PWM waveform diagram of each switch tube in the full-bridge LLC before adjustment provided by an embodiment of the present invention; Figure 4 is a PWM waveform diagram of each switch tube in the adjusted full-bridge LLC provided by an embodiment of the present invention; Figure 5 is a structural schematic diagram of an LLC current sharing control device provided by an embodiment of the present invention; Figure 6 is a schematic diagram of a control terminal provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0023] In the following description, specific details such as specific system structures, technologies, etc. are provided for the purpose of illustration rather than limitation, so as to provide a thorough understanding of the embodiments of the present invention. However, it should be clear to those skilled in the art that the present invention may be implemented in other embodiments without these specific details. In other cases, detailed descriptions of well-known systems, devices, circuits, and methods are omitted to prevent unnecessary details from obstructing the description of the present invention.

[0024] In order to make the purpose, technical solutions and advantages of the present invention more clear, specific embodiments will be described below in conjunction with the accompanying drawings.

[0025] See also Figure 1 , which shows a dual-path LLC circuit; the dual-path LLC circuit includes: a first LLC and a second LLC; the output end of the first LLC is connected in parallel or in series with the output end of the second LLC; Figure 1 When the first switch K1 and the third switch K3 are closed and the second switch K2 is opened, the output end of the first LLC is connected in parallel with the output end of the second LLC; when the first switch K1 and the third switch K3 are opened and the second switch K2 is closed, the output end of the first LLC is connected in series with the output end of the second LLC; the input end of the first LLC is connected in parallel with the input end of the second LLC and is powered by the same power supply.

[0026] Since the outputs of the two LLCs are relatively independent, it is necessary to set the current balance. Otherwise, when the uneven current is too high, it will easily lead to different losses and lifespans of the two LLCs. In severe cases, it may even cause one of the LLCs to have an output that exceeds its own carrying capacity and cause the machine to explode.

[0027] Based on the above dual-path LLC circuit, an embodiment of the present invention provides an LLC current sharing control method, which is applied to the above dual-path LLC circuit. Figure 2The following is a flowchart of the LLC current sharing control method according to an embodiment of the present invention, which is described in detail as follows: The LLC current sharing control method includes: S101: obtaining a working current of a first LLC as a first current, obtaining a working current of a second LLC as a second current, and determining a current sharing control amount according to the first current and the second current; S102: modulating the current sharing control amount to obtain a current sharing modulation amount; The working currents of the two LLCs can reflect the current sharing of the two LLCs, so in the embodiment of the present invention, the working currents of the two LLCs are obtained to determine the current sharing control amount. Exemplarily, the working current can be the primary current of the LLC.

[0028] Specifically, the primary currents of the two LLCs can be sampled by CT (current transformer) respectively, and then filtered (for example, RC filtering) to obtain the first current and the second current. The sampling circuit is a conventional circuit, and the details are not repeated here.

[0029] S103: After adjusting the original PWM wave of at least one switch tube in the first LLC and the second LLC according to the current sharing modulation amount, a target PWM wave of the corresponding switch tube is obtained.

[0030] S104: Use the target PWM wave to drive the corresponding switch tube to operate, so that the first LLC and the second LLC have equal current.

[0031] The embodiment of the present invention modulates the current sharing control amount to obtain the current sharing modulation amount, and uses the current sharing adjustment amount to directly adjust the original PWM wave (for example, adjust the duty cycle, limit, etc. of the PWM wave), directly acts on the PWM wave, and adjusts the PWM waves of the switching tubes in the two LLCs to achieve current sharing. The effect is direct, the current sharing speed is fast, and the adjustment effect is good.

[0032] It should be noted that when the first LLC and the second LLC are connected in parallel (ie, the first switch and the third switch are closed), the above method achieves current balancing in both paths; when the first LLC and the second LLC are connected in series (the second switch is closed), the above method can achieve voltage balancing in both paths.

[0033] In a possible implementation, S103 may include: S1031: Generate a current sharing PWM wave for each switch tube in the first LLC and a current sharing PWM wave for each switch tube in the second LLC according to the current sharing modulation amount; S1032: For any switch tube in the first LLC and the second LLC, superimpose the original PWM wave of the switch tube with the current-sharing PWM wave of the switch tube to obtain a target PWM wave of the switch tube.

[0034] In the embodiment of the present invention, a current-sharing PWM wave of each switch tube is generated according to the current-sharing modulation amount, and is directly superimposed on the original PWM wave, so that the regulation effect is more direct.

[0035] In a possible implementation, S101 may include: S1011: Subtract the second current from the first current to obtain a first current difference; S1012: Input the first current difference into the first PI controller and limit the current to obtain a current sharing control value.

[0036] In the embodiment of the present invention, the difference between the first current and the second current is calculated, and the current sharing control amount is generated according to the difference. For example, when the current is not shared, the first current difference is not 0, and the current sharing control amount is obtained after passing through the first PI controller.

[0037] It should be noted that the limiter is used to limit the adjustment range of the duty cycle to avoid over-modulation and affect the normal operation of the circuit.

[0038] In one possible implementation, reference Figure 1 , the first LLC is a full-bridge LLC, including: a first front bridge arm 11 (leading bridge arm) and a first rear bridge arm 12 (lagging bridge arm) connected in parallel; the second LLC is also a full-bridge LLC, including: a second front bridge arm 21 (leading bridge arm) and a second rear bridge arm 22 (lagging bridge arm) connected in parallel; S1031 may include: 1. Generate a first reference PWM wave according to the current sharing modulation amount; 2. Invert the first reference PWM wave as the current-sharing PWM wave of the upper tube and the lower tube of the first front bridge arm 11; the current-sharing PWM waves of the upper tube and the lower tube of the first rear bridge arm 12 are both set to 0; 3. The first reference PWM wave is used as the current-sharing PWM wave of the upper tube and the lower tube of the second front bridge arm 21; the current-sharing PWM waves of the upper tube and the lower tube of the second rear bridge arm 22 are both set to 0.

[0039] refer to Figure 1 The first LLC includes a first front bridge arm 11 and a first rear bridge arm 12 connected in parallel. Specifically, the first front bridge arm 11 includes a first switch tube Q1 (upper tube of the first front bridge arm 11) and a second switch tube Q2 (lower tube of the first front bridge arm 11) connected in series, and the first rear bridge arm 12 includes a third switch tube Q3 (upper tube of the first rear bridge arm 12) and a fourth switch tube Q4 (lower tube of the first rear bridge arm 12) connected in series. The second front bridge arm 21 includes a fifth switch tube Q5 and a sixth switch tube Q6 connected in series, and the second rear bridge arm 22 includes a seventh switch tube Q7 and an eighth switch tube Q8 connected in series.

[0040] For example, if the first current is greater than the second current, the current sharing modulation amount is positive. At this time, it is necessary to reduce the first current and increase the second current. Therefore, the first reference PWM wave is inverted and added to the first switch tube Q1 and the second switch tube Q2, and the first reference PWM wave is directly added to the fifth switch tube Q5 and the sixth switch tube Q6.

[0041] At the same time, since the first switch tube Q1 and the fourth switch tube Q4 are turned on and off at the same time, and the second switch tube Q2 and the third switch tube Q3 are turned on and off at the same time, if the first switch tube Q1 is turned off and the fourth switch tube Q4 is turned on, it does not affect the normal operation of the circuit. Therefore, in the embodiment of the present invention, a current-sharing PWM wave can be applied only to the first front bridge arm 11 and the second front bridge arm 21, and the first rear bridge arm 12 and the second rear bridge arm 22 are not applied with a current-sharing PWM wave, that is, the current-sharing PWM wave is set to 0, which reduces the control difficulty without affecting the control effect, and has a small loss.

[0042] Exemplarily, when the first current is greater than the second current, the current sharing modulation amount is positive, the first reference PWM wave is inverted and added to the first front bridge arm 11, the duty cycle of the PWM wave of the first front bridge arm 11 is reduced, and the first current is reduced; the first reference PWM wave is directly added to the second front bridge arm 21, the duty cycle of the PWM of the second front bridge arm 21 is increased, and the second current is increased to achieve current sharing.

[0043] When the first current is less than the second current, the current sharing control amount is negative, and the first reference PWM wave is inverted and added to the first front bridge arm 11. Negative times negative equals positive, and the duty cycle of the PWM wave of the first front bridge arm 11 increases, thereby increasing the first current; the first reference PWM wave is directly added to the second front bridge arm 21, and the duty cycle of the PWM of the second front bridge arm 21 decreases, thereby reducing the second current and achieving current sharing.

[0044] In a possible implementation, the current sharing control amount may include: a first current sharing control amount and a second current sharing control amount; the current sharing modulation amount includes: a first current sharing modulation amount and a second current sharing modulation amount; S101 may include: S1013: Calculate the current average of the first current and the second current; S1014: Subtract the current mean from the first current to obtain a second current difference; S1015: inputting the second current difference into a second PI controller and limiting the amplitude to obtain a first current sharing control value; S1016: Subtract the current mean from the second current to obtain a third current difference; S1017: Input the third current difference into a third PI controller and limit the current to obtain a second current sharing control value; S102 may specifically include: S1021: modulating the first current sharing control amount to obtain a first current sharing modulation amount; S1022: Modulate the second current sharing control amount to obtain a second current sharing modulation amount.

[0045] In an embodiment of the present invention, the average of the first current and the second current can also be calculated, and a first current control amount can be generated based on the difference between the first current and the current average, which is used to balance the current of the first LLC; and a second current control amount can be generated based on the difference between the second current and the current average, which is used to balance the current of the second LLC.

[0046] In one possible implementation, reference Figure 1 The first LLC is a full-bridge LLC, which may include: a first front bridge arm 11 and a first rear bridge arm 12 connected in parallel; the second LLC may also be a full-bridge LLC, which may include: a second front bridge arm 21 and a second rear bridge arm 22 connected in parallel; S1031 may include: 4. Generate a second reference PWM wave according to the first current sharing modulation amount; 5. Invert the second reference PWM wave as the current-sharing PWM wave of the upper tube and the lower tube of the first front bridge arm 11; the current-sharing PWM waves of the upper tube and the lower tube of the first rear bridge arm 12 are both set to 0; 6. Generate a third reference PWM wave according to the second current sharing modulation amount; 7. The third reference PWM wave is inverted as the current-sharing PWM wave of the upper tube and the lower tube of the second front bridge arm 21; the current-sharing PWM wave of the upper tube and the lower tube of the second rear bridge arm 22 are both set to 0.

[0047] Similarly, if the first current is greater than the mean current and the first current balancing modulation amount is positive, it will act in reverse on the first front bridge arm 11 to reduce the first current; at this time, the second current must be less than the mean current, and the second current balancing modulation amount is negative, and it will also act in reverse on the second front bridge arm 21, and negative times negative equals positive, increasing the second current.

[0048] Otherwise, the details will not be elaborated here.

[0049] Furthermore, in a possible implementation manner, the above method may further include: S105: Obtaining operating parameters of the first LLC and operating parameters of the second LLC; S106: Inputting the operating parameters of the first LLC and the operating parameters of the second LLC into the control loop to obtain a loop control variable; S107: Obtaining original PWM waves of each switch tube in the first LLC according to the loop control amount; S108: Shift the phase of the original PWM wave of each switch tube in the first LLC by 90° to obtain the corresponding original PWM wave of each switch tube in the second LLC.

[0050] The first LLC and the second LLC are phase-shifted controlled, and the original PWM wave of each switch tube in the first LLC is phase-shifted by 90° and acts on the second LLC.

[0051] Specifically, the switches at corresponding positions of the two full-bridge LLCs are phase-shifted one by one. For example, the original PWM wave of the first switch tube Q1 is shifted by 90° to obtain the original PWM wave on the fifth switch tube Q5; the original PWM wave of the second switch tube Q2 is shifted by 90° to obtain the original PWM wave on the sixth switch tube Q6; the original PWM wave of the third switch tube Q3 is shifted by 90° to obtain the original PWM wave on the seventh switch tube Q7; the original PWM wave of the fourth switch tube Q4 is shifted by 90° to obtain the original PWM wave on the eighth switch tube Q8.

[0052] refer to Figure 3 , the first channel to the fourth channel correspond to the PWM waveforms of the first switch tube Q1 to the fourth switch tube Q4 respectively. Based on the original waveform obtained in the above steps, when the first current is greater than the second current, the current sharing modulation amount is positive, the first reference PWM wave is inverted and added to the first front bridge arm 11, the duty cycle of the PWM wave of the first front bridge arm 11 (the first switch tube Q1 and the second switch tube Q2) is reduced, and the duty cycle of the PWM wave of the first rear bridge arm 12 (the third switch tube Q3 and the fourth switch tube Q4) remains unchanged, refer to Figure 3 .

[0053] Depend on Figure 3 It can be seen that the first reference PWM wave is inverted and added to the first front bridge arm 11, and the duty cycle of the PWM wave of the first front bridge arm 11 (the first switch tube Q1 and the second switch tube Q2) is reduced. When the first switch tube Q1 is turned off, the second switch tube Q2 is not turned on yet. At this time, the energy in the resonant cavity can only be continued through the body diode of the second switch tube Q2, and the loss is very large.

[0054] Based on this, in a further implementation, corresponding to the first LLC, the above method may further include: S109: Obtain the time corresponding to the rising edge of the upper tube of the first front bridge arm 11 in the current cycle, recorded as the first time (t1); S1010: Obtaining a moment corresponding to a falling edge of the lower tube of the first front bridge arm 11 that is before the first moment and closest to the first moment, and recording it as a second moment (t2); S1011: If the difference between the second moment and the first moment is greater than the dead zone duration, the rising edge of the upper tube of the first front bridge arm 11 and the rising edge of the lower tube of the first front bridge arm 11 are both moved forward by a first preset duration; wherein the first preset duration is equal to the first moment minus the second moment minus the dead zone duration.

[0055] In the embodiment of the present invention, the rising edge of the first switch tube Q1 and the rising edge of the second switch tube Q2 are both shifted to the left, so that only the dead time is retained between the rising edge of the first switch tube Q1 and the falling edge of the second switch tube Q2, and between the falling edge of the first switch tube Q1 and the rising edge of the second switch tube Q2. Figure 4 When the first switch tube Q1 is turned off, the second switch tube Q2 is turned on after the dead time, which greatly reduces the loss.

[0056] Similarly, corresponding to the second LLC, the above method may further include: S1012: Obtain the time corresponding to the rising edge of the upper tube of the second front bridge arm 21 in the current cycle, recorded as the third time; S1013: Obtaining a moment corresponding to a falling edge of the lower tube of the second front bridge arm 21 that is before the third moment and closest to the third moment, and recording it as a fourth moment; S1014: If the difference between the fourth moment and the third moment is greater than the dead zone duration, the rising edge of the upper tube of the second front bridge arm 21 and the rising edge of the lower tube of the second front bridge arm 21 are both moved forward by a second preset time duration; wherein the second preset time duration is equal to the third moment minus the fourth moment minus the dead zone duration.

[0057] As above, the rising edge of the fifth switch tube Q5 and the rising edge of the sixth switch tube Q6 are shifted to the left, thereby reducing the loss and improving the efficiency of the circuit.

[0058] In a possible implementation, before S101, the method may further include: S1015: obtaining the output power of the dual-channel LLC circuit in real time; S1016: When it is detected that the output power of the dual-path LLC circuit is greater than the first preset power, execute steps S101 to S104.

[0059] When the circuit is lightly loaded or unloaded, the first current and the second current are very small, which can easily affect the output of the loop, thereby affecting the normal modulation of the circuit. Based on this, the output power of the dual-channel LLC circuit is monitored in real time in the embodiment of the present invention, and current sharing is turned on only when the output power is greater than the first preset power, so as to avoid interference of current sharing control on the normal modulation of the circuit.

[0060] In a possible implementation, the above method may further include: S1017: When it is detected that the output power of the dual-channel LLC circuit is less than the second preset power, the current sharing modulation amount is set to 0; Among them, the first preset power is greater than the second preset power; when the current sharing modulation amount is 0, the target PWM wave is the same as the original PWM wave.

[0061] Based on the above, when it is detected that the circuit output power is less than the second preset power, the current sharing is turned off to avoid the current sharing control interfering with the normal modulation. Among them, the first preset power is greater than the second preset power, forming a hysteresis to avoid the circuit output power at the critical time. The current sharing control frequently changes between closing and opening, affecting the normal operation of the circuit.

[0062] For example, the first preset power may be 5KW, and the second preset power may be 4KW. The first preset power and the second preset power are set according to actual application requirements, and are not specifically limited here.

[0063] The above control method is simulated and illustrated in conjunction with specific embodiments below.

[0064] 1. In the dual LLC circuit parallel mode, the low voltage 300V full load 40KW, no device error and 5% device error simulation results refer to Table 1.

[0065] Table 1 Low voltage 300V-40KW simulation table

[0066] 2. In the dual LLC circuit parallel mode, the low voltage 520V full load 40KW, no device error and 5% device error simulation results refer to Table 2.

[0067] Table 2 Low voltage 520V-40KW simulation table

[0068] 3. In the dual-channel LLC circuit series mode, the high voltage 600V full load 40KW, no device error and 5% device error simulation results refer to Table 3.

[0069] Table 3 High voltage 600V-40KW simulation table

[0070] 4. In the dual LLC circuit series mode, the high voltage is 1000V and the full load is 40KW. The simulation results of no device error and 5% device error are shown in Table 4.

[0071] Table 4 High voltage 1000V-40KW simulation table

[0072] From the simulation results of the above working conditions, it can be seen that under general working conditions where there are device deviations in the circuit, the above current sharing control method can effectively achieve parallel current sharing and series voltage sharing of two full-bridge LLCs, and the current sharing effect is good.

[0073] It should be understood that the order of execution of the steps in the above embodiment does not necessarily mean the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiment of the present invention.

[0074] The following is an embodiment of the device of the present invention. For details not described in detail therein, reference may be made to the corresponding method embodiment described above.

[0075] Figure 5 The structure diagram of the LLC current sharing control device provided by the embodiment of the present invention is shown. For the convenience of explanation, only the part related to the embodiment of the present invention is shown, which is described in detail as follows: like Figure 5 As shown, the LLC current sharing control device is applied to a dual-path LLC circuit; Figure 1 The dual-path LLC circuit includes: a first LLC and a second LLC; the output end of the first LLC is connected in parallel or in series with the output end of the second LLC; the LLC current sharing control device includes: The current sharing control quantity output module 31 is used to obtain the working current of the first LLC as the first current, obtain the working current of the second LLC as the second current, and determine the current sharing control quantity according to the first current and the second current; The modulation module 32 is used to modulate the current sharing control amount to obtain the current sharing modulation amount; The PWM wave adjustment module 33 is used to adjust the original PWM wave of at least one switch tube in the first LLC and the second LLC according to the current sharing modulation amount to obtain a target PWM wave of the corresponding switch tube; The driving module 34 is used to drive the corresponding switch tube to operate by using the target PWM wave, so that the first LLC and the second LLC have equal current.

[0076] In a possible implementation, the PWM wave adjustment module 33 may include: A current-sharing wave generating unit, used to generate a current-sharing PWM wave of each switch tube in the first LLC and a current-sharing PWM wave of each switch tube in the second LLC according to the current-sharing modulation amount; The waveform superposition unit is used to superimpose the original PWM wave of any one switch tube in the first LLC and the second LLC with the current-sharing PWM wave of the switch tube to obtain the target PWM wave of the switch tube.

[0077] In a possible implementation, the current sharing control amount output module 31 may include: A first current difference calculation unit, configured to obtain a first current difference by subtracting the second current from the first current; The first PI control unit is used to input the first current difference into the first PI controller and limit the current difference to obtain the current sharing control amount.

[0078] In a possible implementation, the first LLC is a full-bridge LLC, including: a first front bridge arm 11 and a first rear bridge arm 12 connected in parallel; the second LLC is a full-bridge LLC, including: a second front bridge arm 21 and a second rear bridge arm 22 connected in parallel; the current wave generating unit may include: A first reference wave generating subunit, used for generating a first reference PWM wave according to the current sharing modulation amount; The first driving wave generating subunit is used to invert the first reference PWM wave as the current-sharing PWM wave of the upper tube and the lower tube of the first front bridge arm 11; the current-sharing PWM waves of the upper tube and the lower tube of the first rear bridge arm 12 are both set to 0; The second driving wave generating subunit is used to use the first reference PWM wave as the current-sharing PWM wave of the upper tube and the lower tube of the second front bridge arm 21; the current-sharing PWM waves of the upper tube and the lower tube of the second rear bridge arm 22 are both set to 0.

[0079] In a possible implementation, the current sharing control amount may include: a first current sharing control amount and a second current sharing control amount; the current sharing modulation amount includes: a first current sharing modulation amount and a second current sharing modulation amount; the current sharing control amount output module 31 may include: A mean value calculation unit, used for calculating the current mean value of the first current and the second current; A second current difference calculation unit, configured to subtract the current mean from the first current to obtain a second current difference; A second PI control unit is used to input the second current difference into a second PI controller and limit the current difference to obtain a first current sharing control amount; A third current difference calculation unit, configured to subtract the current mean from the second current to obtain a third current difference; A third PI control unit, used for inputting the third current difference into a third PI controller and limiting the third current difference to obtain a second current sharing control amount; The modulation module 32 can be specifically used to: modulate the first current sharing control amount to obtain a first current sharing modulation amount; and modulate the second current sharing control amount to obtain a second current sharing modulation amount.

[0080] In a possible implementation, the first LLC is a full-bridge LLC, which may include: a first front bridge arm 11 and a first rear bridge arm 12 connected in parallel; the second LLC is a full-bridge LLC, which may include: a second front bridge arm 21 and a second rear bridge arm 22 connected in parallel; the current wave generating unit may include: A second reference wave generating subunit, used for generating a second reference PWM wave according to the first current sharing modulation amount; The third driving wave generating subunit is used to invert the second reference PWM wave as the current-sharing PWM wave of the upper tube and the lower tube of the first front bridge arm 11; the current-sharing PWM wave of the upper tube and the lower tube of the first rear bridge arm 12 are both set to 0; A third reference wave generating unit, used for generating a third reference PWM wave according to the second current sharing modulation amount; The fourth driving wave generating subunit is used to invert the third reference PWM wave as the current-sharing PWM wave of the upper tube and the lower tube of the second front bridge arm 21; the current-sharing PWM waves of the upper tube and the lower tube of the second rear bridge arm 22 are both set to 0.

[0081] In a possible implementation manner, the above device may further include: A rising edge extraction module is used to obtain the time corresponding to the rising edge of the upper tube of the first front bridge arm in the current cycle, which is recorded as the first time; A falling edge extraction module, used to obtain a moment corresponding to a falling edge of the lower tube of the first front bridge arm before the first moment and closest to the first moment, recorded as a second moment; A waveform adjustment module is used to move the rising edge of the upper tube of the first front bridge arm and the rising edge of the lower tube of the first front bridge arm forward by a first preset time length if the difference between the second moment and the first moment is greater than the dead zone duration; wherein the first preset time length is equal to the first moment minus the second moment minus the dead zone duration.

[0082] In a possible implementation manner, the above device may further include: Power detection module, used to obtain the output power of the dual-channel LLC circuit in real time; The current balancing trigger module is used to execute the steps of obtaining the working current of the first LLC as the first current, obtaining the working current of the second LLC as the second current, and determining the current balancing control amount according to the first current and the second current, and using the target PWM wave to drive the corresponding switch tube to operate, so that the first LLC and the second LLC balance the current when it is detected that the output power of the dual-channel LLC circuit is greater than the first preset power.

[0083] In a possible implementation manner, the above device may further include: A current sharing exit module, configured to set the current sharing modulation amount to 0 when it is detected that the output power of the dual-channel LLC circuit is less than a second preset power; Among them, the first preset power is greater than the second preset power; when the current sharing modulation amount is 0, the target PWM wave is the same as the original PWM wave.

[0084] Figure 6 Schematic diagram of the control terminal 4 provided in the embodiment of the present invention. Figure 6 As shown, the control terminal 4 of this embodiment includes: a processor 40 and a memory 41. The memory 41 is used to store a computer program 42, and the processor 40 is used to call and run the computer program 42 stored in the memory 41 to perform the steps in the above-mentioned various LLC current sharing control method embodiments, such as Figure 2Alternatively, the processor 40 is used to call and run the computer program 42 stored in the memory 41 to implement the functions of each module / unit in the above-mentioned device embodiments, such as Figure 5 The functions of the modules 31 to 33 are shown.

[0085] Exemplarily, the computer program 42 may be divided into one or more modules / units, one or more modules / units are stored in the memory 41 and executed by the processor 40 to implement the present invention. One or more modules / units may be a series of computer program instruction segments capable of implementing specific functions, and the instruction segments are used to describe the execution process of the computer program 42 in the control terminal 4. For example, the computer program 42 may be divided into Figure 5 Modules / units 31 to 33 are shown.

[0086] The control terminal 4 may be a computing device such as a desktop computer, a notebook, a PDA, or a cloud server. The control terminal 4 may include, but is not limited to, a processor 40 and a memory 41. Those skilled in the art will appreciate that Figure 6 It is only an example of the control terminal 4 and does not constitute a limitation on the control terminal 4. It may include more or fewer components than shown in the figure, or a combination of certain components, or different components. For example, the terminal may also include input and output devices, network access devices, buses, etc.

[0087] The processor 40 may be a central processing unit (CPU), or other general-purpose processors, digital signal processors (DSP), application-specific integrated circuits (ASIC), field-programmable gate arrays (FPGA), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. A general-purpose processor may be a microprocessor or any conventional processor, etc.

[0088] The memory 41 may be an internal storage unit of the control terminal 4, such as a hard disk or memory of the control terminal 4. The memory 41 may also be an external storage device of the control terminal 4, such as a plug-in hard disk, a smart media card (SMC), a secure digital (SD) card, a flash card, etc. equipped on the control terminal 4. Further, the memory 41 may also include both an internal storage unit of the control terminal 4 and an external storage device. The memory 41 is used to store computer programs and other programs and data required by the terminal. The memory 41 may also be used to temporarily store data that has been output or is to be output.

[0089] The technicians in the relevant field can clearly understand that for the convenience and simplicity of description, only the division of the above-mentioned functional units and modules is used as an example for illustration. In practical applications, the above-mentioned function allocation can be completed by different functional units and modules as needed, that is, the internal structure of the device can be divided into different functional units or modules to complete all or part of the functions described above. The functional units and modules in the embodiment can be integrated in a processing unit, or each unit can exist physically separately, or two or more units can be integrated in one unit. The above-mentioned integrated unit can be implemented in the form of hardware or in the form of software functional units. In addition, the specific names of the functional units and modules are only for the convenience of distinguishing each other, and are not used to limit the scope of protection of this application. The specific working process of the units and modules in the above-mentioned system can refer to the corresponding process in the aforementioned method embodiment, which will not be repeated here.

[0090] In the above embodiments, the description of each embodiment has its own emphasis. For parts that are not described or recorded in detail in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0091] Those skilled in the art will appreciate that the units and algorithm steps of each example described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professional and technical personnel can use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of the present invention.

[0092] In the embodiments provided by the present invention, it should be understood that the disclosed devices / terminals and methods can be implemented in other ways. For example, the device / terminal embodiments described above are only schematic, for example, the division of modules or units is only a logical function division, and there may be other division methods in actual implementation, such as multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some interfaces, indirect coupling or communication connection of devices or units, which can be electrical, mechanical or other forms.

[0093] The units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed on multiple network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0094] In addition, each functional unit in each embodiment of the present invention may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit. The above-mentioned integrated unit may be implemented in the form of hardware or in the form of software functional units.

[0095] If the integrated module / unit is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the present invention implements all or part of the processes in the above-mentioned embodiment method, and can also be completed by instructing the relevant hardware through a computer program. The computer program can be stored in a computer-readable storage medium, and the computer program can implement the steps of the above-mentioned various method embodiments when executed by the processor. Among them, the computer program includes computer program code, and the computer program code can be in source code form, object code form, executable file or some intermediate form. Computer-readable media can include: any entity or device that can carry computer program code, recording medium, U disk, mobile hard disk, disk, optical disk, computer memory, read-only memory (ROM), random access memory (RAM), electrical carrier signal, telecommunication signal and software distribution medium, etc.

[0096] Corresponding to the above embodiment, a charging device is further provided in an embodiment of the present invention, comprising at least two dual-path LLC circuits as provided in the above embodiment; the output ends of each dual-path LLC circuit are connected in series or in parallel.

[0097] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. Such modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention, and should be included in the protection scope of the present invention.

Claims

1. An LLC current sharing control method, characterized in that: Applied to dual-channel LLC circuit; The dual-path LLC circuit includes: a first LLC and a second LLC; the output end of the first LLC is connected in parallel or in series with the output end of the second LLC; the control method includes: Acquire the working current of the first LLC as a first current, acquire the working current of the second LLC as a second current, and determine a current sharing control amount according to the first current and the second current; Modulating the current sharing control amount to obtain a current sharing modulation amount; After adjusting the original PWM wave of at least one switch tube in the first LLC and the second LLC according to the current sharing modulation amount, a target PWM wave of the corresponding switch tube is obtained; The target PWM wave is used to drive the corresponding switch tube to operate, so that the first LLC and the second LLC share the current.

2. The LLC current sharing control method according to claim 1, characterized in that: The step of adjusting the original PWM wave of at least one switch tube in the first LLC and the second LLC according to the current sharing modulation amount to obtain a target PWM wave of the corresponding switch tube includes: Generate a current sharing PWM wave of each switch tube in the first LLC and a current sharing PWM wave of each switch tube in the second LLC according to the current sharing modulation amount; For any one switch tube in the first LLC and the second LLC, the original PWM wave of the switch tube is superimposed with the current-sharing PWM wave of the switch tube to obtain the target PWM wave of the switch tube.

3. The LLC current sharing control method according to claim 2, characterized in that: The determining the current sharing control amount according to the first current and the second current includes: Subtracting the second current from the first current to obtain a first current difference; The first current difference is input into a first PI controller and limited to obtain the current sharing control amount.

4. The LLC current sharing control method according to claim 3, characterized in that: The first LLC is a full-bridge LLC, including: a first front bridge arm and a first rear bridge arm connected in parallel; the second LLC is a full-bridge LLC, including: a second front bridge arm and a second rear bridge arm connected in parallel; the generating of the current-sharing PWM wave of each switch tube in the first LLC and the current-sharing PWM wave of each switch tube in the second LLC according to the current-sharing modulation amount includes: Generate a first reference PWM wave according to the current sharing modulation amount; Inverting the first reference PWM wave as the current-sharing PWM wave of the upper tube and the lower tube of the first front bridge arm; setting the current-sharing PWM waves of the upper tube and the lower tube of the first rear bridge arm to 0; The first reference PWM wave is used as the current-sharing PWM wave of the upper tube and the lower tube of the second front bridge arm; the current-sharing PWM waves of the upper tube and the lower tube of the second rear bridge arm are both set to 0.

5. The LLC current sharing control method according to claim 2, characterized in that: The current sharing control amount includes: a first current sharing control amount and a second current sharing control amount; the current sharing modulation amount includes: a first current sharing modulation amount and a second current sharing modulation amount; the current sharing control amount is determined according to the first current and the second current, including: calculating a current average of the first current and the second current; Subtract the current mean from the first current to obtain a second current difference; Inputting the second current difference into a second PI controller and limiting the amplitude thereof to obtain the first current sharing control amount; Subtract the current mean from the second current to obtain a third current difference; Inputting the third current difference into a third PI controller and limiting the amplitude thereof to obtain the second current sharing control amount; The step of modulating the current sharing control amount to obtain the current sharing modulation amount includes: Modulating the first current sharing control amount to obtain the first current sharing modulation amount; The second current sharing control amount is modulated to obtain the second current sharing modulation amount.

6. The LLC current sharing control method according to claim 5, characterized in that: The first LLC is a full-bridge LLC, including: a first front bridge arm and a first rear bridge arm connected in parallel; the second LLC is a full-bridge LLC, including: a second front bridge arm and a second rear bridge arm connected in parallel; the generating of the current-sharing PWM wave of each switch tube in the first LLC and the current-sharing PWM wave of each switch tube in the second LLC according to the current-sharing modulation amount includes: Generate a second reference PWM wave according to the first current sharing modulation amount; Invert the second reference PWM wave as the current-sharing PWM wave of the upper tube and the lower tube of the first front bridge arm; set the current-sharing PWM wave of the upper tube and the lower tube of the first rear bridge arm to 0; Generate a third reference PWM wave according to the second current sharing modulation amount; The third reference PWM wave is inverted as the current-sharing PWM wave of the upper tube and the lower tube of the second front bridge arm; the current-sharing PWM wave of the upper tube and the lower tube of the second rear bridge arm are both set to 0.

7. The LLC current sharing control method according to claim 4 or 6, characterized in that: The method further comprises: Obtaining the time corresponding to the rising edge of the upper tube of the first front bridge arm in the current cycle, recorded as the first time; Obtaining a moment corresponding to a falling edge of the lower tube of the first front bridge arm that is before the first moment and closest to the first moment, and recording it as a second moment; If the difference between the second moment and the first moment is greater than the dead zone duration, the rising edge of the upper tube of the first front bridge arm and the rising edge of the lower tube of the first front bridge arm are both moved forward by a first preset time duration; wherein the first preset time duration is equal to the first moment minus the second moment minus the dead zone duration.

8. The LLC current sharing control method according to any one of claims 1 to 6, characterized in that: Before obtaining the working current of the first LLC as the first current, obtaining the working current of the second LLC as the second current, and determining the current sharing control amount according to the first current and the second current, the method further includes: Acquire the output power of the dual-path LLC circuit in real time; When it is detected that the output power of the dual-channel LLC circuit is greater than the first preset power, the step of obtaining the working current of the first LLC as the first current, obtaining the working current of the second LLC as the second current, and determining the current sharing control amount according to the first current and the second current is performed, until the step of using the target PWM wave to drive the corresponding switch tube to act, so that the first LLC and the second LLC share the current.

9. The LLC current sharing control method according to claim 8, characterized in that: The method further comprises: When it is detected that the output power of the dual-channel LLC circuit is less than a second preset power, setting the current sharing modulation amount to 0; Among them, the first preset power is greater than the second preset power; when the current sharing modulation amount is 0, the target PWM wave is the same as the original PWM wave.

10. A charging device, characterized in that: include: At least two dual-path LLC circuits provided as claimed in any one of claims 1 to 9; the output ends of the respective dual-path LLC circuits are connected in series or in parallel.

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