Charging device, current sharing control module and current sharing control method thereof

Abstract

The invention discloses a charging device, a current sharing control module and a current sharing control method thereof, and the method comprises the steps: obtaining the internal currents of two DC / DC units, and calculating the internal current deviation value of the two DC / DC units; judging whether the internal current deviation value is greater than a first preset value or not; and when the internal current deviation value is greater than a first preset value, adjusting the internal current of the corresponding DC / DC unit by adjusting the control parameter of at least one DC / DC unit, and / or adjusting the internal current of the two DC / DC units by adjusting the control parameter of the AC / DC module. According to the technical scheme, the cost of the charging device is reduced, the size of the charging device is reduced, and the reliability of current sharing control is improved.

Description

Technical Field

[0001] The present application relates to the field of power supply technology, and in particular to a charging device, a current balancing control module and a current balancing control method thereof. Background Art

[0002] In the field of new energy charging, the charging device is the core technology and also the part with the largest cost share among the charging pile components. Generally speaking, the charging device consists of a front-end AC / DC module and a rear-end DC / DC module. In view of the requirements of high voltage, high current and cost, the charging device usually adopts a three-level AC / DC module at the front end. Figure 1 As shown, the output voltage of the AC / DC module is V i , where V i =V i1 +V i2 , V i1 =V i2 The rear stage DC / DC module uses two DC / DC units, whose inputs are respectively V i1 、V i2 , the output voltage is V o1 、V o2 When low voltage and high current are required, output capacitors Co1 and Co2 are connected in parallel. o =V o1 =V o2 ; When high voltage and low current are required, output capacitors Co1 and Co2 are connected in series.

[0003] V o =V o1 +V o2 .

[0004] The mainstream DC / DC unit is the LLC converter, such as Figure 2 As shown in FIG. 1 , the LLC converter includes a switch network, a resonant cavity, a transformer, and a rectifier network connected in sequence. In engineering applications, the resonance parameters of the resonant cavity will have certain engineering tolerances, and will also have certain impedance deviations due to the influence of layout and wiring. These deviations are manifested as: at the same operating frequency and the same output voltage, the internal current of the LLC converter (for example, the resonant current i p1 、i p2 , the secondary current i of the transformer s1 、i s2 There will be a phenomenon of uneven current, especially when two DC / DC unit outputs are connected in parallel. When this deviation is large, it may affect the stability of the system and even cause product damage in severe cases.

[0005] At present, the method of adding a current-sharing circuit is usually used to reduce the deviation of the internal current, but this method has the following problems:

[0006] 1. The cost is high and some additional devices are needed, which will bring cost pressure;

[0007] 2. Adding more devices will take up some space or plane area, affecting the power density;

[0008] 3. Poor reliability. When one of the components fails, the entire function will fail. Summary of the invention

[0009] The technical problem to be solved by the present invention is to provide a charging device, a current balancing control module and a current balancing control method thereof in view of the above-mentioned technical defects in the prior art.

[0010] The technical solution adopted by the present invention to solve the technical problem is: construct a current sharing control method for a charging device, the charging device includes an AC / DC module and a DC / DC module connected to each other, the DC / DC module includes two DC / DC units, including:

[0011] Acquisition step: acquiring internal currents of two DC / DC units, and calculating internal current deviations of the two DC / DC units;

[0012] Determining step: determining whether the internal current deviation is greater than a first preset value;

[0013] Control step: when the internal current deviation is greater than a first preset value, the internal current of the corresponding DC / DC unit is adjusted by adjusting the control parameters of at least one DC / DC unit, and / or the internal current of the two DC / DC units is adjusted by adjusting the control parameters of the AC / DC module.

[0014] Preferably, the DC / DC unit is an LLC converter, and the internal current is a current of a resonant cavity in the LLC converter or a secondary current of a transformer in the LLC converter.

[0015] Preferably, adjusting the internal current of the corresponding DC / DC unit by adjusting the control parameter of at least one DC / DC unit comprises:

[0016] adjusting the internal current of the corresponding LLC converter by adjusting the conduction angle of the inverter circuit in at least one LLC converter; and / or,

[0017] The internal currents of the two LLC converters are adjusted by adjusting the output power of the DC / DC module.

[0018] Preferably, the DC / DC unit with a larger internal current among the two DC / DC units is used as the first DC / DC unit, and the DC / DC unit with a smaller internal current among the two DC / DC units is used as the second DC / DC unit;

[0019] The control step comprises:

[0020] Step S311, determining whether the first DC / DC unit meets the phase shift condition, if yes, executing step S312; if no, executing step S313;

[0021] Step S312, reducing the conduction angle of the inverter circuit of the first DC / DC unit, and then executing step S317;

[0022] Step S313, obtaining the current input voltages of the first DC / DC unit and the second DC / DC unit, calculating the input voltage deviation of the two DC / DC units, and determining whether the input voltage deviation is less than a second preset value, if so, executing step S314; if not, executing step S315;

[0023] Step S314, adjusting the control parameters of the AC / DC module to reduce the input voltage of the first DC / DC unit and / or increase the input voltage of the second DC / DC unit, and then executing step S317;

[0024] Step S315, obtaining the current output power of the DC / DC module, and determining whether the current output power is greater than a third preset value, if so, executing step S316; if not, executing step S319;

[0025] Step S316, reducing the current output power;

[0026] Step S317, obtaining the current internal current of the first DC / DC unit and the second DC / DC unit, calculating the current internal current deviation of the two DC / DC units, and determining whether the current internal current deviation is less than a first preset value, if so, executing step S318; if not, executing step S311;

[0027] Step S318, maintaining control parameters of the two DC / DC units and the AC / DC module;

[0028] Step S319: Shut down.

[0029] Preferably, the controlling step further comprises:

[0030] Determining whether the internal current of the first DC / DC unit is greater than the maximum bearing current;

[0031] When the current is greater than the maximum bearing current, the internal current of the first DC / DC unit is jointly adjusted by the AC / DC module and the DC / DC module.

[0032] Preferably, the controlling step comprises:

[0033] Step S321, determining whether the first DC / DC unit meets the phase shift condition, if yes, executing step S322; if no, executing step S323;

[0034] Step S322, reducing the conduction angle of the inverter circuit of the first DC / DC unit, and then executing step S321;

[0035] Step S323, determining whether the first DC / DC unit has a current greater than a maximum withstand current, if so, executing step S324;

[0036] Step S324, determining the minimum input voltage and the maximum input voltage of each DC / DC unit, and determining the maximum withstand bias voltage of the AC / DC module according to the maximum input voltage and the minimum input voltage;

[0037] Step S325, determining the optimal input voltage of each DC / DC unit;

[0038] Step S326, determining a target input voltage of each DC / DC unit according to the maximum withstand bias voltage of the AC / DC module, the optimal input voltage, the minimum input voltage, and the maximum input voltage of each DC / DC unit;

[0039] Step S327: adjusting the control parameters of the AC / DC module according to the target input voltage of each DC / DC unit.

[0040] Preferably, the step S325 includes:

[0041] Step S3251, determining the optimal input voltage of the DC / DC module according to the following formula:

[0042]

[0043] Among them, V i_opt is the optimal input voltage of the DC / DC module, Vo _ref is the output voltage requirement of the DC / DC module, N p is the number of primary turns of the transformer in the DC / DC unit, and Ns is the number of secondary turns of the transformer in the DC / DC unit;

[0044] Step S3252: Divide the optimal input voltage of the DC / DC module by 2 to obtain the optimal input voltage of each DC / DC unit.

[0045] Preferably, the step S326 includes:

[0046] If the optimal input voltage of the DC / DC unit is between the minimum input voltage and the maximum input voltage, the target input voltage of each DC / DC unit is determined based on the maximum bias voltage of the AC / DC module and taking the optimal input voltage as the center;

[0047] If the optimal input voltage of the DC / DC unit is less than the minimum input voltage, the target input voltage of the first DC / DC unit is determined to be the minimum input voltage, and the target input voltage of the second DC / DC unit is determined to be the sum of the minimum input voltage and the maximum withstand bias voltage;

[0048] If the optimal input voltage of the DC / DC unit is greater than the maximum input voltage, the target input voltage of the second DC / DC unit is determined as the maximum input voltage, and the target input voltage of the first DC / DC unit is determined as the difference between the maximum input voltage and the maximum withstand bias voltage.

[0049] The present invention also constructs a current sharing control module, including a processor and a memory storing a computer program, wherein the processor implements the steps of the current sharing control method described above when executing the computer program.

[0050] The present invention also constructs a charging device, including an AC / DC module and a DC / DC module connected to each other, wherein the DC / DC module includes two DC / DC units and also includes the above-mentioned current sharing control module.

[0051] Through the technical solution of the present application, when the internal current deviation of the two DC / DC units is large (the internal current deviation is greater than the first preset value), a unique software algorithm is used to adjust the internal current of the DC / DC unit by controlling the control parameters of at least one DC / DC unit and / or the control parameters of the AC / DC module, thereby reducing the internal current deviation of the two DC / DC units. This software-based current balancing control method not only reduces the cost and volume of the charging device, but also improves the reliability of current balancing control. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0053] Figure 1It is a circuit diagram of an existing charging device;

[0054] Figure 2 is a circuit diagram of a DC / DC module of a charging device in one embodiment of the present invention;

[0055] Figure 3 is a flow chart of a current sharing control method for a charging device in one embodiment of the present invention;

[0056] Figure 4A is a circuit diagram of an inverter circuit in a DC / DC converter in one embodiment of the present invention;

[0057] Figure 4B yes Figure 4A Schematic diagram of the midpoint voltage of the inverter circuit before phase shift;

[0058] Figure 4C yes Figure 4A Schematic diagram of the midpoint voltage of the inverter circuit after phase shift;

[0059] Figure 5 is a flow chart of control steps in a current sharing control method for a charging device in one embodiment of the present invention;

[0060] Fig. 6A is a relationship diagram of the minimum input voltage, the maximum input voltage, and the optimal input voltage of a DC / DC unit in one embodiment of the present invention;

[0061] Figure 6B is a relationship diagram of a minimum input voltage, a maximum input voltage, and an optimal input voltage of a DC / DC unit in another embodiment of the present invention;

[0062] Figure 6C This is a relationship diagram of the minimum input voltage, maximum input voltage, and optimal input voltage of a DC / DC unit in another embodiment of the present invention. DETAILED DESCRIPTION

[0063] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0064] Figure 3 is a flow chart of a current sharing control method for a charging device in one embodiment of the present invention. The current sharing control method in this embodiment is applied to a control module of the charging device. Figure 1The charging device also includes an AC / DC module and a DC / DC module connected to each other, and the DC / DC module includes two DC / DC units.

[0065] like Figure 3 As shown, the current sharing control method of this embodiment includes:

[0066] Acquisition step S10: acquiring internal currents of two DC / DC units, and calculating internal current deviations of the two DC / DC units;

[0067] Determining step S20: determining whether the internal current deviation is greater than a first preset value;

[0068] Control step S30: When the internal current deviation is greater than a first preset value, the internal current of the corresponding DC / DC unit is adjusted by adjusting the control parameters of at least one DC / DC unit, and / or the internal current of the two DC / DC units is adjusted by adjusting the control parameters of the AC / DC module.

[0069] Through the technical solution of this embodiment, when the internal current deviation of the two DC / DC units is large (the internal current deviation is greater than the first preset value), a unique software algorithm is used to adjust the internal current of the DC / DC unit by controlling the control parameters of at least one DC / DC unit and / or the control parameters of the AC / DC module, thereby reducing the internal current deviation of the two DC / DC units. This software-based current balancing control method not only reduces the cost and volume of the charging device, but also improves the reliability of current balancing control.

[0070] Further, in an optional embodiment, the DC / DC unit is an LLC converter, such as Figure 2 As shown, each LLC converter includes an inverter circuit (such as a full-bridge inverter circuit), a resonant cavity, a transformer, and a rectifier circuit connected to each other. Moreover, the internal current is the current of the resonant cavity in the LLC converter, for example, i p1 、i p2 , or, the secondary current i of the transformer in the LLC converter s1 、i s2 .

[0071] Further, in an optional embodiment, adjusting the internal current of the corresponding DC / DC unit by adjusting the control parameter of at least one DC / DC unit in step S30 includes:

[0072] adjusting the internal current of the corresponding LLC converter by adjusting the conduction angle of the inverter circuit in at least one LLC converter; and / or,

[0073] The internal currents of the two LLC converters are adjusted by adjusting the output power of the DC / DC module.

[0074] In a specific embodiment, when adjusting the internal current of the LLC converter by adjusting the conduction angle of the inverter circuit in the LLC converter, a conduction angle adjustment loop can be established in the control logic, with the conduction angle as the adjustment object and the internal current as the feedback object, so as to achieve the purpose of adjusting the internal current by adjusting the conduction angle of the inverter circuit. The adjustment principle of the conduction angle is described below:

[0075] Combination Figure 4A , 4B , 4C, the inverter circuit in the LLC converter is an inverter full-bridge circuit. In a switching cycle, when there is no phase shift, the two diagonal switch tubes of the inverter circuit are turned on and off at the same time. At this time, the conduction angle α is 180°, and the output voltage (midpoint voltage) of the inverter full-bridge circuit is V in , as shown in formula 1; when the phase is shifted, the two sets of diagonal switch tubes of the inverter circuit are no longer turned on and off at the same time. At this time, the conduction angle α is less than 180°, and the lagging bridge arm delays the leading bridge arm by 180°-α, that is, the phase shift angle is 180°-α, and the midpoint voltage of the inverter full-bridge circuit is V′ in , as shown in Formula 2. Regarding the conduction angle α, it should be noted that since the sum of the conduction angle α and the phase shift angle is half a switching cycle, that is, 180°, the larger the phase shift angle, the smaller the conduction angle; and vice versa.

[0076]

[0077] Among them, V i is the input voltage of the DC / DC unit, is also the output voltage of the AC / DC module, and α is the conduction angle. Figure 4A , 4B As shown, based on the midpoint voltage of the inverter full-bridge circuit before phase shifting, the midpoint voltage after phase shifting needs to be multiplied by a coefficient less than 1, that is, sin(α / 2). Therefore, by controlling the conduction angle, the midpoint voltage, that is, the output voltage of the inverter circuit, can be adjusted. Of course, the adjustment of the conduction angle α will also have certain constraints. The basis for judging whether phase shifting can be performed includes but is not limited to: device current stress (mainly primary inverter devices), device temperature rise, working mode (soft switching), etc.

[0078] In a specific embodiment, when adjusting the internal current of two LLC converters by adjusting the output power of the DC / DC module, an output power regulation loop can be established in the control logic, with the internal current as the feedback object and the output power as the adjustment object, wherein the output power Po is calculated by the output voltage Vo and the output current Io / output load Ro, and can also be measured by a power metering device. The following example illustrates the principle of output power adjustment: Assuming that the design value of the internal current of the DC / DC unit is 60A, and when the output power is 1000W, the internal currents of the two DC / DC units are 70A and 50A respectively, and the internal current deviation (20A) of the two DC / DC units is too large. At this time, the output power can be adjusted to reduce the output power to 800W, and the internal currents of the two DC / DC units are 60A and 45A respectively. In this way, on the one hand, the internal current value is less than the design maximum value, and on the other hand, the deviation of the internal current is reduced.

[0079] Regarding the above embodiment, it should be noted that when the internal current deviation is too large, three adjustments can be made: phase shift, input voltage adjustment, and output power adjustment. In specific applications, one or more of these adjustment methods can be selected, and when multiple adjustment methods are selected, different combinations can be made.

[0080] Figure 5 This is a flow chart of the control steps in the current sharing control method of a charging device in one embodiment of the present invention. First, it is explained that when it is judged that the internal current deviation of the two DC / DC units is too large, the DC / DC unit with the larger internal current of the two DC / DC units is used as the first DC / DC unit, and the DC / DC unit with the smaller internal current of the two DC / DC units is used as the second DC / DC unit. At this time, the control step S30 of this embodiment includes:

[0081] Step S311, determining whether the first DC / DC unit meets the phase shift condition, if yes, executing step S312; if no, executing step S313;

[0082] Step S312, reducing the conduction angle of the inverter circuit of the first DC / DC unit, and then executing step S317;

[0083] Step S313, obtaining the current input voltages of the first DC / DC unit and the second DC / DC unit, calculating the input voltage deviation of the two DC / DC units, and determining whether the input voltage deviation is less than a second preset value, if so, executing step S314; if not, executing step S315;

[0084] Step S314, adjusting the control parameters of the AC / DC module to reduce the input voltage of the first DC / DC unit and / or increase the input voltage of the second DC / DC unit, and then executing step S317;

[0085] Step S315, obtaining the current output power of the DC / DC module, and determining whether the current output power is greater than a third preset value, if so, executing step S316; if not, executing step S319;

[0086] Step S316, reducing the current output power;

[0087] Step S317, obtaining the current internal current of the first DC / DC unit and the second DC / DC unit, calculating the current internal current deviation of the two DC / DC units, and determining whether the current internal current deviation is less than a first preset value, if so, executing step S318; if not, executing step S311;

[0088] Step S318, maintaining control parameters of the two DC / DC units and the AC / DC module;

[0089] Step S319: Shut down.

[0090] In this embodiment, it is first explained that the internal current (for example, the resonant current i p1 、i p2 ) current detection and the detection of the conduction angle α of the inverter circuit. In addition, the input voltage V of the two DC / DC units i1 、V i2 The detection is already available.

[0091] When the internal current deviation is detected to be too large, that is, |i p1 -i p2 |=ΔI p ≥I ref_p_max , the current sharing control loop can be started, where ΔI p is the resonant current i of the two groups of DC / DC units p1 、i p2 The absolute value of the difference, I ref_p_max is the first preset value, that is, the maximum bias current of the two groups of DC / DC units. Its value can be a fixed value or vary with the output power. For example, as the output power increases, the deviation becomes smaller (from the perspective of device current resistance). It can also be measured by the current balance, for example

[0092] Assume that at this time i p1 >i p2First, determine whether the conduction angle α of the inverter circuit of the larger part of the resonant current (the first DC / DC unit) meets the phase shift condition, wherein the determination basis includes but is not limited to: device current stress (mainly primary inverter device), device temperature rise, working mode (soft switch), etc. If the phase shift condition is met, adjust the conduction angle α of the first DC / DC unit to reduce the input voltage of its resonant cavity and reduce the internal resonant current i p1 and the secondary current i s1 , and realize the adjustment of the two groups of average flow.

[0093] When the phase shift condition is not met, it is detected whether the input voltage deviation of the two DC / DC units is too large, that is, whether it meets: ΔV i <V ref_in_max , where ΔV i =|V i1 -V i2 | is the input voltage deviation, V ref_in_max The maximum deviation allowed can be a fixed value or can vary with the output voltage. For example, as the output voltage increases, the deviation decreases (from the perspective of device withstand voltage). If the input voltage adjustment condition is met, the input voltage V of the first DC / DC unit is reduced. i1 , increase the input voltage V of the second DC / DC unit i2 , but need to maintain V i1 +V i2 =Vi, meets system requirements.

[0094] When the input voltage adjustment condition is not met, it is determined whether the output power is greater than a third preset value, that is, whether: P o >P o_ref , where P o By the output voltage V o and output current I o / Output load R o Calculated or measured by power metering equipment, P o_ref is the third preset value, i.e., the preset threshold of the output power. If it is satisfied, the output power P is reduced. o , thereby synchronously reducing the internal current i p1 、i p2 If not satisfied, the system output needs to be shut down.

[0095] After completing a conduction angle adjustment, input voltage adjustment or output power adjustment, check again whether the internal current deviation of the two DC / DC units meets the following conditions: ΔI p <V ref_p_maxIf it is satisfied, the adjustment is ended and the control parameter is maintained; if it is not satisfied, the process jumps to the conduction angle judgment step again and performs a new round of adjustment.

[0096] In this embodiment, the three adjustment modes are combined and applied by setting the entry conditions of the three adjustment modes. Specifically, the phase shift adjustment is performed first, followed by the input voltage adjustment, and finally the output power adjustment. Moreover, during the adjustment, the control parameters of the front-stage AC / DC module and the rear-stage DC / DC module are adjusted together, thereby increasing the adjustable range of the bias current.

[0097] Furthermore, in an optional embodiment, the control step S30 further includes:

[0098] Determining whether the internal current of the first DC / DC unit is greater than the maximum bearing current;

[0099] When the current is greater than the maximum bearing current, the internal current of the first DC / DC unit is jointly adjusted by the AC / DC module and the DC / DC module.

[0100] In this embodiment, when the internal current deviation cannot be completely eliminated and exceeds the tolerance range of the DC / DC module, the AC / DC module and the DC / DC module can be adjusted together to further expand the tolerance range of the bias current. If it is within the tolerance range of the DC / DC module, the DC / DC module is preferentially adjusted, and the AC / DC module is not adjusted.

[0101] Further, in a specific embodiment, the control step S30 includes:

[0102] Step S321, determining whether the first DC / DC unit meets the phase shift condition, if yes, executing step S322; if no, executing step S323;

[0103] Step S322, reducing the conduction angle of the inverter circuit of the first DC / DC unit, and then executing step S321;

[0104] Step S323, determining whether the first DC / DC unit has a current greater than a maximum withstand current, if so, executing step S324;

[0105] Step S324, determining the minimum input voltage and the maximum input voltage of each DC / DC unit, and determining the maximum withstand bias voltage of the AC / DC module according to the maximum input voltage and the minimum input voltage;

[0106] Step S325, determining the optimal input voltage of each DC / DC unit;

[0107] Step S326, determining a target input voltage of each DC / DC unit according to the maximum withstand bias voltage of the AC / DC module, the optimal input voltage, the minimum input voltage, and the maximum input voltage of each DC / DC unit;

[0108] Step S327: adjusting the control parameters of the AC / DC module according to the target input voltage of each DC / DC unit.

[0109] In this embodiment, it is first determined whether the first DC / DC unit (the DC / DC unit with a larger internal current) can be phase-shifted. If it is possible to shift the phase, the conduction angle of the inverter circuit of the first DC / DC unit is reduced; if it is not possible to shift the phase, it is determined whether the DC / DC module can withstand uneven current, that is, whether the I p_x_max >I p_max , where I p_max The maximum current that can be sustained is mainly determined by the device stress. Usually I p1_max =I p2_max , the default is a known quantity; I p_x_max is the resonant current of the largest group in the current resonant current. If so, it means that the uneven current has exceeded the tolerance range of the DC / DC module. The minimum input voltage, maximum input voltage, and optimal input voltage of the DC / DC unit can be determined in the following ways:

[0110] When determining the minimum input voltage of a DC / DC unit, first obtain V o 、V o_ref 、V grid , ΔI p 、V i , P o , P o_ref The value of V o is the current output voltage, V o_ref is the output voltage requirement, V grid Current input grid voltage, P o is the current output power, P o_ref is the output power requirement. Then, according to V grid Determine V i_min1 (PFC is a boost circuit), and then according to V o 、V o_ref Determine V i_min2 (Too low V i Meaning a higher voltage gain, which may cause the system to enter hard switching), finally, the minimum input voltage V of the DC / DC module is determined according to the following formula i_min :V i_min =max(V i_min1 ,V i_min2), and the minimum input voltage of each DC / DC unit is: V i_min / 2.

[0111] When determining the maximum input voltage of a DC / DC unit, usually V i1_max =V i2_max , while V i1_max 、V i2_max Determined by device stress, such as C i1 and C i2 The maximum input voltage of the DC / DC module is determined by the withstand voltage, etc. i_max , where V i_max =V i1_max +V i2_max , this value is usually determined during design and can be assumed to be known. The maximum input voltage of each DC / DC unit is: V i_max / 2.

[0112] When determining the optimal input voltage of the DC / DC unit, since the optimal input voltage can make the DC / DC unit work at the resonance point, the optimal input voltage V of the DC / DC module can be determined according to Formula 3. i_opt , and the optimal input voltage of each DC / DC unit is: V i_opt / 2.

[0113]

[0114] Among them, N p is the number of turns of the primary side of the transformer, and Ns is the number of turns of the secondary side of the transformer.

[0115] After the minimum input voltage, maximum input voltage, and optimal input voltage of the DC / DC unit are determined, the maximum bias voltage ΔV that the AC / DC module can withstand can be determined according to Formula 4. i_max :

[0116]

[0117] Finally, according to V i_opt and V i_min 、V i_max Relationship, determine V i The direction is adjusted to determine the target input voltage of each DC / DC unit in the DC / DC module, and then the control parameters of the AC / DC module are adjusted according to the target input voltage of each DC / DC unit.

[0118] Further, step S326 includes:

[0119] If the optimal input voltage of the DC / DC unit is between the minimum input voltage and the maximum input voltage, the target input voltage of each DC / DC unit is determined based on the maximum bias voltage of the AC / DC module and taking the optimal input voltage as the center;

[0120] If the optimal input voltage of the DC / DC unit is less than the minimum input voltage, the target input voltage of the first DC / DC unit is determined to be the minimum input voltage, and the target input voltage of the second DC / DC unit is determined to be the sum of the minimum input voltage and the maximum withstand bias voltage;

[0121] If the optimal input voltage of the DC / DC unit is greater than the maximum input voltage, the target input voltage of the second DC / DC unit is determined as the maximum input voltage, and the target input voltage of the first DC / DC unit is determined as the difference between the maximum input voltage and the maximum withstand bias voltage.

[0122] In this embodiment, according to V i_opt and V i_min 、V i_max Relationship determination V i When adjusting the direction, if the optimal input voltage is between the minimum input voltage and the maximum input voltage, such as Fig. 6A As shown, V i1 and V i2 V i_opt / 2 as the center for regulation; if the optimal input voltage is less than the minimum input voltage, such as Figure 6B As shown, the input voltage of the first DC / DC unit (the part with the smaller input voltage required) is fixed at V i_min / 2, and the second DC / DC unit (the part with the larger input voltage required) is switched from V i_min / 2 upward adjustment; if the optimal input voltage is greater than the maximum input voltage, such as Figure 6C As shown, the input voltage of the second DC / DC unit (the part with the larger input voltage) is fixed at V i_max / 2, while the first DC / DC unit (the part with the smaller input voltage required) is from V i_max / 2 adjust downward.

[0123] The present invention also constructs a current sharing control module, which includes a processor and a memory storing a computer program. The processor implements the steps of the current sharing control method described above when executing the computer program.

[0124] The present invention also constructs a charging device, which includes an AC / DC module and a DC / DC module connected to each other, wherein the DC / DC module includes two DC / DC units, and the charging device also includes the above-mentioned current sharing control module.

[0125] The above are only preferred embodiments of the present application and are not intended to limit the present application. For those skilled in the art, the present application may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the scope of the claims of the present application.

Claims

1. A current sharing control method for a charging device, wherein the charging device comprises an AC / DC module and a DC / DC module connected to each other, wherein the DC / DC module comprises two DC / DC units, wherein: include: Acquisition step: acquiring internal currents of two DC / DC units, and calculating internal current deviations of the two DC / DC units; Determining step: determining whether the internal current deviation is greater than a first preset value; Control step: when the internal current deviation is greater than a first preset value, the internal current of the corresponding DC / DC unit is adjusted by adjusting the control parameters of at least one DC / DC unit, and / or the internal current of the two DC / DC units is adjusted by adjusting the control parameters of the AC / DC module.

2. The current sharing control method according to claim 1, characterized in that: The DC / DC unit is an LLC converter, and the internal current is the current of the resonant cavity in the LLC converter or the secondary current of the transformer in the LLC converter.

3. The current sharing control method according to claim 2, characterized in that: Adjusting the internal current of the corresponding DC / DC unit by adjusting the control parameter of at least one DC / DC unit includes: adjusting the internal current of the corresponding LLC converter by adjusting the conduction angle of the inverter circuit in at least one LLC converter; and / or, The internal currents of the two LLC converters are adjusted by adjusting the output power of the DC / DC module.

4. The current sharing control method according to claim 3, characterized in that: The DC / DC unit with a larger internal current among the two DC / DC units is used as a first DC / DC unit, and the DC / DC unit with a smaller internal current among the two DC / DC units is used as a second DC / DC unit; The control step comprises: Step S311, determine whether the first DC / DC unit meets the phase shift condition, if so, execute Step S312; if not, execute step S313; Step S312, reducing the conduction angle of the inverter circuit of the first DC / DC unit, and then executing step S317; Step S313, obtaining the current input voltages of the first DC / DC unit and the second DC / DC unit, calculating the input voltage deviation of the two DC / DC units, and determining whether the input voltage deviation is less than a second preset value, if so, executing step S314; if not, executing step S315; Step S314, adjusting the control parameters of the AC / DC module to reduce the input voltage of the first DC / DC unit and / or increase the input voltage of the second DC / DC unit, and then executing step S317; Step S315, obtaining the current output power of the DC / DC module, and determining whether the current output power is greater than a third preset value, if so, executing step S316; if not, executing step S319; Step S316, reducing the current output power; Step S317, obtaining the current internal current of the first DC / DC unit and the second DC / DC unit, calculating the current internal current deviation of the two DC / DC units, and determining whether the current internal current deviation is less than a first preset value, if so, executing step S318; if not, executing step S311; Step S318, maintaining control parameters of the two DC / DC units and the AC / DC module; Step S319: Shut down.

5. The current sharing control method according to claim 4, characterized in that: The control step also includes: Determining whether the internal current of the first DC / DC unit is greater than the maximum bearing current; When the current is greater than the maximum bearing current, the internal current of the first DC / DC unit is jointly adjusted by the AC / DC module and the DC / DC module.

6. The current sharing control method according to claim 5, characterized in that: The control step comprises: Step S321, determining whether the first DC / DC unit meets the phase shift condition, if yes, executing step S322; if no, executing step S323; Step S322, reducing the conduction angle of the inverter circuit of the first DC / DC unit, and then executing step S321; Step S323, determining whether the first DC / DC unit has a current greater than a maximum withstand current, if so, executing step S324; Step S324, determining the minimum input voltage and the maximum input voltage of each DC / DC unit, and determining the maximum withstand bias voltage of the AC / DC module according to the maximum input voltage and the minimum input voltage; Step S325, determining the optimal input voltage of each DC / DC unit; Step S326, determining a target input voltage of each DC / DC unit according to the maximum withstand bias voltage of the AC / DC module, the optimal input voltage, the minimum input voltage, and the maximum input voltage of each DC / DC unit; Step S327: adjusting the control parameters of the AC / DC module according to the target input voltage of each DC / DC unit.

7. The current sharing control method according to claim 6, characterized in that: The step S325 includes: Step S3251, determining the optimal input voltage of the DC / DC module according to the following formula: Among them, V i_opt is the optimal input voltage of the DC / DC module, Vo _ref is the output voltage requirement of the DC / DC module, N p is the number of primary turns of the transformer in the DC / DC unit, and Ns is the number of secondary turns of the transformer in the DC / DC unit; Step S3252: Divide the optimal input voltage of the DC / DC module by 2 to obtain the optimal input voltage of each DC / DC unit.

8. The current sharing control method according to claim 7, characterized in that: The step S326 includes: If the optimal input voltage of the DC / DC unit is between the minimum input voltage and the maximum input voltage, the target input voltage of each DC / DC unit is determined based on the maximum bias voltage of the AC / DC module and taking the optimal input voltage as the center; If the optimal input voltage of the DC / DC unit is less than the minimum input voltage, the target input voltage of the first DC / DC unit is determined to be the minimum input voltage, and the target input voltage of the second DC / DC unit is determined to be the sum of the minimum input voltage and the maximum withstand bias voltage; If the optimal input voltage of the DC / DC unit is greater than the maximum input voltage, the target input voltage of the second DC / DC unit is determined as the maximum input voltage, and the target input voltage of the first DC / DC unit is determined as the difference between the maximum input voltage and the maximum withstand bias voltage.

9. A current sharing control module, comprising a processor and a memory storing a computer program, characterized in that: The processor implements the steps of the current sharing control method described in any one of claims 1 to 8 when executing the computer program.

10. A charging device, comprising an AC / DC module and a DC / DC module connected to each other, wherein the DC / DC module comprises two DC / DC units, characterized in that: It also includes the current sharing control module as described in claim 9.

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