LLC current sharing control method and charging equipment

Abstract

The present invention provides an LLC current sharing control method and charging device. The control method includes: obtaining the operating current of a first LLC as a first current, obtaining the operating current of a second LLC as a second current, and determining a current sharing control amount based on the first and second currents; modulating the current sharing control amount to obtain a current sharing modulation amount; adjusting the original PWM wave of at least one switching tube in the first LLC and the second LLC based on the current sharing modulation amount to obtain a target PWM wave for the corresponding switching tube; and using the target PWM wave to drive the corresponding switching tube to operate, so that the first LLC and the second LLC share the current. The present invention generates a current sharing modulation amount based on the operating currents of the two LLCs, directly acting on the original PWM wave, with fast adjustment speed and good current sharing effect.

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 converters are widely used in power supplies due to their high power density and ease of soft switching. Typically, two LLC resonant converters are connected in parallel or series to form a dual LLC circuit to meet different requirements.

[0003] Affected by factors such as manufacturing process and natural environment, it is difficult to maintain consistency in the parameters of the resonant devices of the two LLC circuits, which 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 sharing can be achieved through virtual impedance, but the current sharing effect is poor and the adjustment speed is slow. Summary of the Invention

[0005] The embodiments of the present invention provide an LLC current sharing control method and a charging device to solve the problems of slow adjustment speed and poor current sharing effect in 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 LLC circuit; the dual 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:

[0007] Obtaining the operating current of the first LLC as a first current, obtaining the operating current of the second LLC as a second current, and determining a current sharing control amount according to the first current and the second current;

[0008] Modulating the current sharing control amount to obtain the current sharing modulation amount;

[0009] 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;

[0010] 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.

[0011] Optionally, 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:

[0012] 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;

[0013] For any one switch tube in the first LLC and the second LLC, the original PWM wave of the switch tube and the current-sharing PWM wave of the switch tube are superimposed to obtain the target PWM wave of the switch tube.

[0014] Optionally, determining the current sharing control amount according to the first current and the second current may include:

[0015] Subtracting the second current from the first current to obtain a first current difference;

[0016] The first current difference is input into the first PI controller and limited to obtain a current sharing control value.

[0017] 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 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 includes:

[0018] Generate a first reference PWM wave according to the current sharing modulation amount;

[0019] 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;

[0020] 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.

[0021] 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:

[0022] calculating a current average of the first current and the second current;

[0023] Subtracting the current mean from the first current to obtain a second current difference;

[0024] Inputting the second current difference into the second PI controller and limiting the current difference to obtain a first current sharing control value;

[0025] Subtracting the current mean from the second current to obtain a third current difference;

[0026] Inputting the third current difference into a third PI controller and limiting the current difference to obtain a second current sharing control variable;

[0027] The current sharing control amount is modulated to obtain the current sharing modulation amount, including:

[0028] Modulating the first current sharing control amount to obtain a first current sharing modulation amount;

[0029] The second current sharing control amount is modulated to obtain a second current sharing modulation amount.

[0030] 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 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 includes:

[0031] Generate a second reference PWM wave according to the first current sharing modulation amount;

[0032] 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;

[0033] Generate a third reference PWM wave according to the second current sharing modulation amount;

[0034] 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.

[0035] Optionally, the above method further includes:

[0036] Obtain the time corresponding to the rising edge of the upper tube of the first front bridge arm in the current cycle, and record it as the first time;

[0037] Obtain the moment corresponding to the 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 the second moment;

[0038] 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 duration; wherein the first preset duration is equal to the first moment minus the second moment minus the dead zone duration.

[0039] Optionally, before obtaining the operating current of the first LLC as the first current, obtaining the operating 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:

[0040] Obtain the output power of the dual-channel LLC circuit in real time;

[0041] When it is detected that the output power of the dual LLC circuit is greater than the first preset power, the steps of obtaining the operating current of the first LLC as the first current, obtaining the operating current of the second LLC as the second current, and determining the current sharing control amount based on 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 share the current.

[0042] Optionally, the above method further includes:

[0043] 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;

[0044] 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.

[0045] 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 the respective dual-path LLC circuits are connected in series or in parallel.

[0046] An embodiment of the present invention provides an LLC current sharing control method and charging device. The LLC current sharing control method is applied to 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; the control method includes: obtaining the operating current of the first LLC as a first current, obtaining the operating current of the second LLC as a second current, and determining a current sharing control amount based on the first current and the second current; modulating the current sharing control amount to obtain a 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 to obtain a target PWM wave for the corresponding switch tube; and using the target PWM wave to drive the corresponding switch tube to operate, so that the first LLC and the second LLC share the current.

[0047] The technical effects of the embodiments of the present invention include:

[0048] (1) The working currents of the two LLC circuits are sampled to determine the current sharing control quantity and generate the current sharing modulation quantity. The current sharing modulation quantity is directly used to adjust the PWM waves 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.

[0049] (2) Only the front bridge arm is superimposed with the current-sharing PWM wave, and the rear bridge arm is not superimposed. Under the premise of ensuring the current-sharing effect, the circuit loss is effectively reduced.

[0050] (3) The embodiment of the present invention sets a power limit for starting the current sharing, and does not start the current sharing when the power is low, thereby further reducing the circuit loss without affecting the normal operation of the circuit.

[0051] (4) The phase of the upper tube and the lower tube of the first front bridge arm or the second front bridge arm is 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

[0052] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0053] Figure 1 This is a circuit schematic diagram of a dual-path LLC circuit provided by an embodiment of the present invention;

[0054] Figure 2 This is a flow chart of an implementation of an LLC current sharing control method provided by an embodiment of the present invention;

[0055] Figure 3 1 is a PWM waveform diagram of each switch tube in the full-bridge LLC before adjustment provided by an embodiment of the present invention;

[0056] Figure 4 PWM waveform diagram of each switch tube in the adjusted full-bridge LLC provided by an embodiment of the present invention;

[0057] Figure 5 Schematic diagram of the structure of the LLC current sharing control device provided by an embodiment of the present invention;

[0058] Figure 6 is a schematic diagram of a control terminal provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0059] In the following description, specific details such as particular system structures and techniques are provided for purposes of illustration, not limitation, to facilitate a thorough understanding of the embodiments of the present invention. However, it will be apparent to those skilled in the art that the present invention may be practiced in other embodiments without these specific details. In other cases, detailed descriptions of well-known systems, devices, circuits, and methods are omitted so as not to obscure the description of the present invention with unnecessary detail.

[0060] In order to make the purpose, technical solutions and advantages of the present invention more clear, specific embodiments will be described below with reference to the accompanying drawings.

[0061] See also Figure 1, which shows a dual LLC circuit; the dual 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 open, 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 open 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.

[0062] Since the outputs of the two LLCs are relatively independent, current sharing needs to be set. 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 output too high, exceeding its own carrying capacity, and causing the machine to explode.

[0063] 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 2 The following is a flowchart of an implementation of the LLC current sharing control method provided by an embodiment of the present invention, which is described in detail as follows:

[0064] The LLC current sharing control method includes:

[0065] S101: Acquire a working current of a first LLC as a first current, acquire a working current of a second LLC as a second current, and determine a current sharing control amount according to the first current and the second current;

[0066] S102: Modulate the current sharing control amount to obtain a current sharing modulation amount;

[0067] The operating currents of the two LLCs can reflect the current sharing of the two LLCs. Therefore, in the embodiment of the present invention, the operating currents of the two LLCs are obtained to determine the current sharing control amount. For example, the operating current can be the primary current of the LLC.

[0068] Specifically, the primary currents of the two LLCs can be sampled using CTs (current transformers), and then filtered (e.g., RC filtering) to obtain the first and second currents. The sampling circuit is conventional and will not be described in detail here.

[0069] 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.

[0070] 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.

[0071] 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, limiter, etc. of the PWM wave), directly acting on the PWM wave, and adjusting 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.

[0072] It should be noted that when the first LLC and the second LLC are connected in parallel (i.e., 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.

[0073] In a possible implementation, S103 may include:

[0074] 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;

[0075] S1032: For any one 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.

[0076] 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.

[0077] In a possible implementation, S101 may include:

[0078] S1011: Subtract the second current from the first current to obtain a first current difference;

[0079] S1012: Input the first current difference into the first PI controller and limit the current to obtain a current sharing control value.

[0080] In the embodiment of the present invention, the difference between the first current and the second current is calculated, and the current sharing control variable is generated based on the difference. For example, when the current is not shared, the first current difference is not zero, and the current sharing control variable is obtained after passing through the first PI controller.

[0081] It should be noted that the limiter is used to restrict the adjustment range of the duty cycle to avoid over-modulation and affect the normal operation of the circuit.

[0082] In one possible implementation, reference Figure 1The 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:

[0083] 1. Generate a first reference PWM wave according to the current sharing modulation amount;

[0084] 2. Invert the first reference PWM wave and use it as the current-sharing PWM wave for the upper and lower tubes of the first front bridge arm 11; set the current-sharing PWM waves for the upper and lower tubes of the first rear bridge arm 12 to 0;

[0085] 3. The first reference PWM wave is used as the current-sharing PWM wave for the upper and lower tubes of the second front bridge arm 21 ; the current-sharing PWM waves for the upper and lower tubes of the second rear bridge arm 22 are both set to 0.

[0086] 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 switching transistor Q1 (the upper transistor of the first front bridge arm 11) and a second switching transistor Q2 (the lower transistor of the first front bridge arm 11) connected in series. The first rear bridge arm 12 includes a third switching transistor Q3 (the upper transistor of the first rear bridge arm 12) and a fourth switching transistor Q4 (the lower transistor of the first rear bridge arm 12) connected in series. The second front bridge arm 21 includes a fifth switching transistor Q5 and a sixth switching transistor Q6 connected in series. The second rear bridge arm 22 includes a seventh switching transistor Q7 and an eighth switching transistor Q8 connected in series.

[0087] For example, if the first current is greater than the second current, the current sharing modulation amount is positive. In this case, the first current needs to be reduced and the second current needs to be increased. 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.

[0088] 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, the current-sharing PWM wave can be applied only to the first front bridge arm 11 and the second front bridge arm 21, and the current-sharing PWM wave is not applied to the first rear bridge arm 12 and the second rear bridge arm 22, that is, the current-sharing PWM wave is set to 0, which reduces the control difficulty without affecting the control effect and reduces the loss.

[0089] For example, when the first current is greater than the second current, the current sharing modulation amount is positive, the first reference PWM wave is added inversely 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.

[0090] 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.

[0091] 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:

[0092] S1013: Calculating a current average of the first current and the second current;

[0093] S1014: Subtract the current mean from the first current to obtain a second current difference;

[0094] S1015: Inputting the second current difference into a second PI controller and limiting the current difference to obtain a first current sharing control value;

[0095] S1016: Subtract the current mean from the second current to obtain a third current difference;

[0096] S1017: Input the third current difference into a third PI controller and limit the current difference to obtain a second current sharing control value;

[0097] S102 may specifically include:

[0098] S1021: Modulate the first current sharing control value to obtain a first current sharing modulation value;

[0099] S1022: Modulate the second current sharing control amount to obtain a second current sharing modulation amount.

[0100] 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 equalize 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 equalize the current of the second LLC.

[0101] In one possible implementation, reference Figure 1The 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:

[0102] 4. Generate a second reference PWM wave according to the first current sharing modulation amount;

[0103] 5. Invert the second reference PWM wave and use it as the current-sharing PWM wave for the upper and lower tubes of the first front bridge arm 11; set the current-sharing PWM waves for the upper and lower tubes of the first rear bridge arm 12 to 0;

[0104] 6. Generate a third reference PWM wave according to the second current sharing modulation amount;

[0105] 7. The third reference PWM wave is inverted as the current-sharing PWM wave of the upper and lower switches of the second front bridge arm 21; the current-sharing PWM waves of the upper and lower switches of the second rear bridge arm 22 are both set to 0.

[0106] Similarly, if the first current is greater than the mean current and the first current sharing modulation amount is positive, then the reverse phase action is applied to the first front bridge arm 11, reducing the first current; at this time, the second current must be less than the mean current, and the second current sharing modulation amount is negative, and the reverse phase action is also applied to the second front bridge arm 21, and negative times negative equals positive, increasing the second current.

[0107] Otherwise, the details will not be elaborated here.

[0108] Furthermore, in a possible implementation, the above method may further include:

[0109] S105: Obtaining operating parameters of the first LLC and the second LLC;

[0110] S106: Inputting the operating parameters of the first LLC and the second LLC into the control loop to obtain a loop control variable;

[0111] S107: Obtaining original PWM waves of each switch tube in the first LLC according to the loop control variable;

[0112] S108: Shift the phase of the original PWM wave of each switch tube in the first LLC by 90 degrees to obtain the corresponding original PWM wave of each switch tube in the second LLC.

[0113] The first LLC and the second LLC are phase-shift 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.

[0114] Specifically, the switches at corresponding positions in the two full-bridge LLC circuits are phase-shifted one by one. For example, the original PWM wave of the first switch Q1 is shifted 90° to produce the original PWM wave of the fifth switch Q5; the original PWM wave of the second switch Q2 is shifted 90° to produce the original PWM wave of the sixth switch Q6; the original PWM wave of the third switch Q3 is shifted 90° to produce the original PWM wave of the seventh switch Q7; and the original PWM wave of the fourth switch Q4 is shifted 90° to produce the original PWM wave of the eighth switch Q8.

[0115] refer to Figure 3 , the first to fourth channels 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. Figure 3 .

[0116] 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 flow through the body diode of the second switch tube Q2, resulting in large losses.

[0117] Based on this, in a further embodiment, corresponding to the first LLC, the above method may further include:

[0118] 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);

[0119] S1010: Obtain the time corresponding to the falling edge of the lower tube of the first front bridge arm 11 that is closest to the first time and before the first time, and record it as the second time (t2);

[0120] 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.

[0121] 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 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.

[0122] Similarly, corresponding to the second LLC, the above method may further include:

[0123] 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;

[0124] S1013: Obtain the moment corresponding to the falling edge of the lower tube of the second front bridge arm 21 that is closest to the third moment and before the third moment, and record it as the fourth moment;

[0125] 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 duration; wherein the second preset duration is equal to the third moment minus the fourth moment minus the dead zone duration.

[0126] 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 loss and improving circuit efficiency.

[0127] In a possible implementation, before S101, the method may further include:

[0128] S1015: obtaining the output power of the dual-channel LLC circuit in real time;

[0129] 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.

[0130] When the circuit is lightly loaded or unloaded, the first and second currents are very small, easily affecting the loop output and, consequently, the normal modulation of the circuit. To address this, the present invention monitors the output power of the dual LLC circuit in real time and only enables current sharing when the output power exceeds a first preset power, thus preventing current sharing from interfering with the normal modulation of the circuit.

[0131] In a possible implementation, the above method may further include:

[0132] 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;

[0133] 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.

[0134] Based on the above, when the circuit output power is detected to be less than the second preset power, current sharing is disabled to prevent current sharing control from interfering with normal modulation. The first preset power is greater than the second preset power, creating hysteresis to prevent the circuit output power from frequently fluctuating between off and on, potentially affecting normal circuit operation.

[0135] For example, the first preset power may be 5 kW, and the second preset power may be 4 kW. The first preset power and the second preset power are set according to actual application requirements and are not specifically limited here.

[0136] The above control method is simulated and illustrated below with reference to specific embodiments.

[0137] 1. In the dual LLC circuit parallel mode, the low voltage is 300V and the full load is 40kW. The simulation results of no device error and 5% device error are shown in Table 1.

[0138] Table 1 Low voltage 300V-40KW simulation table

[0139]

[0140] 2. In the dual LLC circuit parallel mode, the low voltage 520V is fully loaded at 40kW, and the simulation results with no device error and 5% device error are shown in Table 2.

[0141] Table 2 Low voltage 520V-40KW simulation table

[0142]

[0143] 3. In the dual-LLC circuit series mode, the high voltage 600V full load 40kW, no device error and 5% device error simulation results are shown in Table 3.

[0144] Table 3 High voltage 600V-40KW simulation table

[0145]

[0146] 4. In the dual-circuit LLC series mode, the high voltage 1000V full load 40kW, no device error and 5% device error simulation results are shown in Table 4.

[0147] Table 4 High voltage 1000V-40KW simulation table

[0148]

[0149] 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 the two full-bridge LLCs, with good current sharing effect.

[0150] It should be understood that the size of the serial numbers of the steps in the above embodiments does not 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 embodiments of the present invention.

[0151] The following are device embodiments of the present invention. For details not fully described therein, reference may be made to the corresponding method embodiments described above.

[0152] Figure 5 The following is a schematic diagram showing the structure of an LLC current sharing control device provided by an embodiment of the present invention. For ease of explanation, only the parts related to the embodiment of the present invention are shown, which are described in detail as follows:

[0153] like Figure 5 As shown, the LLC current sharing control device is applied to a dual-path LLC circuit; Figure 1 The dual 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:

[0154] a current sharing control value output module 31, configured to obtain the operating current of the first LLC as a first current, obtain the operating current of the second LLC as a second current, and determine the current sharing control value according to the first current and the second current;

[0155] A modulation module 32 is used to modulate the current sharing control amount to obtain a current sharing modulation amount;

[0156] The PWM wave adjustment module 33 is configured 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;

[0157] The driving module 34 is used to drive the corresponding switch tube to operate using the target PWM wave so that the first LLC and the second LLC have equal current.

[0158] In a possible implementation, the PWM wave adjustment module 33 may include:

[0159] A current sharing wave generating unit, configured to 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;

[0160] The waveform superposition unit is used to superimpose the original PWM wave of any one switching tube in the first LLC and the second LLC with the current-sharing PWM wave of the switching tube to obtain the target PWM wave of the switching tube.

[0161] In a possible implementation, the current sharing control value output module 31 may include:

[0162] a first current difference calculation unit, configured to subtract the second current from the first current to obtain a first current difference;

[0163] 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.

[0164] In one 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:

[0165] A first reference wave generating subunit, configured to generate a first reference PWM wave according to the current sharing modulation amount;

[0166] 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 wave of the upper tube and the lower tube of the first rear bridge arm 12 are both set to 0;

[0167] 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.

[0168] 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:

[0169] a mean value calculation unit, configured to calculate a current mean value of the first current and the second current;

[0170] a second current difference calculation unit, configured to subtract the current mean from the first current to obtain a second current difference;

[0171] A second PI control unit is configured to input the second current difference into a second PI controller and limit the current difference to obtain a first current sharing control value;

[0172] a third current difference calculation unit, configured to subtract the current mean from the second current to obtain a third current difference;

[0173] a third PI control unit, configured to input the third current difference into a third PI controller and limit the current difference to obtain a second current sharing control value;

[0174] 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.

[0175] In one 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; and the current wave generating unit may include:

[0176] A second reference wave generating subunit, configured to generate a second reference PWM wave according to the first current sharing modulation amount;

[0177] 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;

[0178] A third reference wave generating unit is used to generate a third reference PWM wave according to the second current sharing modulation amount;

[0179] 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.

[0180] In a possible implementation, the above device may further include:

[0181] A rising edge extraction module is used to obtain the moment 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 moment;

[0182] a falling edge extraction module, configured to 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 is before the first moment, and record the moment as a second moment;

[0183] The 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 length; wherein the first preset time length is equal to the first moment minus the second moment minus the dead zone length.

[0184] In a possible implementation, the above device may further include:

[0185] Power detection module, used to obtain the output power of the dual-channel LLC circuit in real time;

[0186] The current sharing trigger module is used to execute the steps of obtaining the operating current of the first LLC as the first current and the operating current of the second LLC as the second current when it is detected that the output power of the dual LLC circuit is greater than the first preset power, and determining the current sharing control amount based on the first current and the second current, and then using the target PWM wave to drive the corresponding switch tube to operate, so that the first LLC and the second LLC share the current.

[0187] In a possible implementation, the above device may further include:

[0188] a current sharing exit module, configured to set the current sharing modulation amount to 0 when detecting that the output power of the dual-channel LLC circuit is less than a second preset power;

[0189] 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.

[0190] Figure 6 Schematic diagram of the control terminal 4 provided by 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 2 Alternatively, 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 modules 31 to 33 are shown.

[0191] For example, the computer program 42 may be divided into one or more modules / units, one or more modules / units being 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.

[0192] The control terminal 4 can be a computing device such as a desktop computer, a notebook, a palmtop computer, or a cloud server. The control terminal 4 can include, but is not limited to, a processor 40 and a memory 41. It will be understood by those skilled in the art that Figure 6It 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.

[0193] The processor 40 may be a central processing unit (CPU), other general-purpose processors, digital signal processors (DSP), application-specific integrated circuits (ASIC), field-programmable gate arrays (FPGA), other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. The general-purpose processor may be a microprocessor or any conventional processor.

[0194] Memory 41 can be an internal storage unit of control terminal 4, such as the hard drive or memory of control terminal 4. Memory 41 can also be an external storage device of control terminal 4, such as a plug-in hard drive, a Smart Media Card (SMC), a Secure Digital (SD) card, a flash memory card, etc. Furthermore, memory 41 can include both the internal storage unit of control terminal 4 and an external storage device. Memory 41 is used to store computer programs and other programs and data required by the terminal. Memory 41 can also be used to temporarily store data that has been output or is about to be output.

[0195] Those skilled in the art can clearly understand that, for the convenience and brevity of description, only the division of the above-mentioned functional units and modules is used as an example for illustration. In actual applications, the above-mentioned functions can be distributed and 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 into one processing unit, or each unit can exist physically alone, or two or more units can be integrated into 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, and will not be repeated here.

[0196] In the above embodiments, the description of each embodiment has its own focus. For parts that are not described or recorded in detail in a certain embodiment, reference can be made to the relevant description of other embodiments.

[0197] 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. Professionals and technicians can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of the present invention.

[0198] In the embodiments provided herein, 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 merely illustrative. For example, the division of modules or units is merely a logical functional division. In actual implementation, other division methods may be used, such as multiple units or components being combined or integrated into another system, or some features being ignored or not implemented. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be through some interface, or the indirect coupling or communication connection of devices or units may be electrical, mechanical, or other forms.

[0199] Units described as separate components may or may not be physically separate, and components shown as units may or may not be physical units, that is, they may be located in one place or distributed across multiple network units. Some or all of these units may be selected to achieve the purpose of this embodiment according to actual needs.

[0200] In addition, the functional units in the various embodiments of the present invention may be integrated into a single processing unit, each unit may exist physically separately, or two or more units may be integrated into a single unit. The aforementioned integrated units may be implemented in the form of hardware or software functional units.

[0201] If the integrated module / unit is implemented as a software functional unit and sold or used as a standalone product, it can be stored in a computer-readable storage medium. Based on this understanding, the present invention can implement all or part of the process steps in the above-mentioned method embodiments by using a computer program to instruct the relevant hardware. The computer program can be stored in a computer-readable storage medium. When executed by a processor, the computer program can implement the steps of each of the above-mentioned method embodiments. The computer program includes computer program code, which can be in source code form, object code form, executable file, or some intermediate form. Computer-readable media can include: any entity or device capable of carrying computer program code, recording media, USB flash drives, mobile hard drives, magnetic disks, optical disks, computer memory, read-only memory (ROM), random access memory (RAM), electrical carrier signals, telecommunications signals, and software distribution media.

[0202] Corresponding to the above embodiment, an embodiment of the present invention further provides a charging device, 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.

[0203] 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 they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present invention, and should all be included in the scope of protection of the present invention.

Claims

1. An LLC current sharing control method, characterized in that: Applied to dual-channel LLC circuit; The dual 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; and the control method includes: Acquire the operating current of the first LLC as a first current, acquire the operating 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; Using the target PWM wave to drive the corresponding switch tube to operate, so that the first LLC and the second LLC have equal current; 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: generating 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; For any one switching tube in the first LLC and the second LLC, superimpose the original PWM wave of the switching tube and the current-sharing PWM wave of the switching tube to obtain a target PWM wave of the switching tube; 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 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 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 for the upper tube and the lower tube of the first front bridge arm; setting the current-sharing PWM wave for 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; The method further comprises: Obtaining the moment corresponding to the rising edge of the upper tube of the first front bridge arm in the current cycle, recorded as the first moment; Obtaining 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 recording the moment 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 duration; wherein the first preset duration is equal to the first moment minus the second moment minus the dead zone duration.

2. The LLC current sharing control method according to claim 1, characterized in that: The determining of 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 value.

3. The LLC current sharing control method according to claim 1, 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; 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; subtracting 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 current difference to obtain the first current sharing control value; subtracting 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 current difference to obtain the second current sharing control value; The 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.

4. The LLC current sharing control method according to claim 3, characterized in that: 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 further includes: Generate a second reference PWM wave according to the first current sharing modulation amount; Inverting the second reference PWM wave as the current-sharing PWM wave for the upper tube and the lower tube of the first front bridge arm; Generate a third reference PWM wave according to the second current sharing modulation amount; The third reference PWM wave is inverted and used as the current-sharing PWM wave of the upper switch and the lower switch of the second front bridge arm.

5. The LLC current sharing control method according to any one of claims 1 to 4, characterized in that: Before acquiring the operating current of the first LLC as the first current, acquiring the operating 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: Obtaining the output power of the dual-path LLC circuit in real time; When it is detected that the output power of the dual LLC circuit is greater than a first preset power, the steps of obtaining the operating current of the first LLC as the first current, obtaining the operating current of the second LLC as the second current, and determining the current sharing control amount based on the first current and the second current are performed, and then the step of using the target PWM wave to drive the corresponding switch tube to operate so that the first LLC and the second LLC share the current is performed.

6. The LLC current sharing control method according to claim 5, 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.

7. A charging device, characterized in that: include: At least two dual-path LLC circuits according to any one of claims 1 to 6; the output terminals of the respective dual-path LLC circuits are connected in series or in parallel.

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