Charging device and charging control method thereof

Abstract

The invention discloses a charging device and a charging control method thereof. The charging control method comprises the following steps: respectively acquiring output voltages and internal currents of two DC / DC units; judging whether a voltage-sharing fault occurs or not according to the output voltages of the two DC / DC units, and judging whether a current-sharing fault occurs or not according to the internal currents of the two DC / DC units; when a voltage-sharing fault occurs, the output voltage of the corresponding DC / DC unit is adjusted by adjusting the control parameter of at least one DC / DC unit, and / or the output voltage of the two DC / DC units is adjusted by adjusting the control parameter of the AC / DC module; when a current sharing fault occurs, the internal current of the corresponding DC / DC unit is adjusted by adjusting the control parameter of at least one DC / DC unit, and / or the internal current of the two DC / DC units is adjusted 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 charging 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 and a charging 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 , 2 As shown, the output voltage of the AC / DC module is V i , where V i =V i1 +V i2 ,

[0003] 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 high voltage and low current are required, output capacitors Co1 and Co2 are connected in series, such as Figure 1 As shown, at this time, V o =V o1 +V o2 ; When low voltage and high current are required, output capacitors Co1 and Co2 are connected in parallel, such as Figure 2 As shown, at this time, V o =V o1 =V o2 .

[0004] The mainstream DC / DC unit is, for example, an LLC converter, such as Figure 3 As shown in the figure, 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 a certain engineering tolerance, and at the same time, due to the influence of layout and wiring, there will be a certain impedance deviation. These deviations are manifested as follows: under parallel operation, the output voltage is the same, and the internal currents of the two DC / DC units (such as the resonant current i p1 、i p2 , transformer secondary current i s1 、i s2 There is uneven current; under the series working condition, when the operating frequency and input voltage are the same, there is uneven voltage in the output voltage. o1 ≠V o2; When these deviations are large, they may affect the stability of the system, and in serious cases may cause product damage.

[0005] At present, hardware solutions are usually used to solve the above problems, but this method has the following defects:

[0006] 1. High cost, requiring additional components, which will bring cost pressure;

[0007] 2. Adding more devices will occupy some space or plane area, increase the volume of the product, and affect 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 and a charging 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 charging control method for a charging device, wherein the charging device includes an AC / DC module and a DC / DC module connected to each other, and the DC / DC module includes two DC / DC units, including:

[0011] Acquisition steps: respectively acquiring the output voltage and internal current of the two DC / DC units;

[0012] Determining step: determining whether a voltage sharing fault occurs according to the output voltages of the two DC / DC units, and determining whether a current sharing fault occurs according to the internal currents of the two DC / DC units;

[0013] First control step: when a voltage balancing fault occurs, adjusting the output voltage of the corresponding DC / DC unit by adjusting the control parameters of at least one DC / DC unit, and / or adjusting the output voltages of the two DC / DC units by adjusting the control parameters of the AC / DC module;

[0014] Second control step: when a current sharing fault occurs, 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.

[0015] 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.

[0016] Preferably, adjusting the output voltage of the corresponding DC / DC unit by adjusting the control parameters of at least one DC / DC unit comprises:

[0017] adjusting the output voltage of the corresponding DC / DC unit by adjusting the conduction angle of the inverter circuit in at least one DC / DC unit; and / or,

[0018] The output voltage of the corresponding DC / DC unit is adjusted by adjusting the driving density of the inverter circuit in at least one DC / DC unit.

[0019] Preferably, the DC / DC unit with a larger output voltage among the two DC / DC units is used as the first DC / DC unit, and the DC / DC unit with a smaller output voltage among the two DC / DC units is used as the second DC / DC unit;

[0020] The first control step comprises:

[0021] Step S311, determining whether the first DC / DC unit meets the phase shift condition, if yes, executing step S312; if no, executing step S313;

[0022] Step S312, reducing the conduction angle of the inverter circuit of the first DC / DC unit, and then executing step S316;

[0023] Step S313, obtaining the current input voltages of the two DC / DC units, and determining whether the input voltage adjustment condition is met according to the current input voltages, if so, executing step S314; if not, executing step S315;

[0024] 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 S316;

[0025] Step S315, reducing the driving density of the inverter circuit of the first DC / DC unit;

[0026] Step S316, obtaining the current output voltages of the two DC / DC units, calculating the current output voltage deviation of the two DC / DC units, and determining whether the current output voltage deviation is less than a first reference threshold value, if so, executing step S317; if not, executing step S311;

[0027] Step S317, maintaining control parameters of the two DC / DC units and the AC / DC module.

[0028] Preferably, the DC / DC unit with a larger output voltage among the two DC / DC units is used as the first DC / DC unit, and the DC / DC unit with a smaller output voltage among the two DC / DC units is used as the second DC / DC unit;

[0029] The first control step comprises:

[0030] Step S321, determining whether the first DC / DC unit meets the phase shift condition, if yes, executing step S322; if no, executing step S323;

[0031] Step S322, reducing the conduction angle of the inverter circuit of the first DC / DC unit, and then executing step S321;

[0032] Step S323, calculating the output voltage deviation of the two DC / DC units according to the output voltages of the two DC / DC units, and determining whether the output voltage deviation is greater than the maximum withstand bias voltage of the DC / DC module, and if so, executing step S324;

[0033] Step S324, determining the minimum input voltage, the maximum input voltage, and the optimal 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;

[0034] Step S325, calculating an output voltage deviation according to the output voltages of the two DC / DC units, and calculating a difference between the output voltage deviation and a maximum bias voltage of the DC / DC module to obtain a bias voltage difference;

[0035] Step S326, determining whether the bias voltage difference is less than or equal to the maximum bias voltage of the AC / DC module, if so, executing step S327; if not, shutting down;

[0036] Step S327, determining a target input voltage of each DC / DC unit according to the bias voltage difference, and the optimal input voltage, the minimum input voltage, and the maximum input voltage of each DC / DC unit;

[0037] Step S328: adjusting the control parameters of the AC / DC module according to the target input voltage of each DC / DC unit.

[0038] Preferably, adjusting the internal current of the corresponding DC / DC unit by adjusting the control parameter of at least one DC / DC unit comprises:

[0039] Adjusting the internal current of the corresponding DC / DC unit by adjusting the conduction angle of the inverter circuit in at least one DC / DC unit; and / or,

[0040] The internal currents of the two DC / DC units are adjusted by adjusting the output power of the DC / DC module.

[0041] 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;

[0042] The second control step comprises:

[0043] Step S411, determining whether the first DC / DC unit meets the phase shift condition, if yes, executing step S412; if no, executing step S413;

[0044] Step S412, reducing the conduction angle of the inverter circuit of the first DC / DC unit, and then executing step S417;

[0045] Step S413, obtaining the current input voltages of the two DC / DC units, and determining whether the input voltage adjustment condition is met according to the current input voltages, if so, executing step S414; if not, executing step S415;

[0046] Step S414, 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;

[0047] Step S415, obtaining the current output power of the DC / DC module, and determining whether the current output power is greater than the output power adjustment condition, if so, executing step S416; if not, shutting down;

[0048] Step S416, reducing the current output power;

[0049] Step S417, obtaining the current internal currents of the two DC / DC units, calculating the current internal current deviation of the two DC / DC units, and determining whether the current internal current deviation is less than a second reference threshold value, if so, executing step S418; if not, executing step S411;

[0050] Step S418, maintaining control parameters of the two DC / DC units and the AC / DC module.

[0051] 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;

[0052] The second control step comprises:

[0053] Step S421, determining whether the first DC / DC unit meets the phase shift condition, if yes, executing step S422; if no, executing step S423;

[0054] Step S422, reducing the conduction angle of the inverter circuit of the first DC / DC unit, and then executing step S421;

[0055] Step S423, determining whether the first DC / DC unit has a current greater than a maximum withstand current, if so, executing step S424;

[0056] Step S424, 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;

[0057] Step S425, determining the optimal input voltage of each DC / DC unit;

[0058] Step S426, 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;

[0059] Step S427: adjusting the control parameters of the AC / DC module according to the target input voltage of each DC / DC unit.

[0060] Preferably, the target input voltage of each DC / DC unit is determined 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, including:

[0061] 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;

[0062] 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;

[0063] 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.

[0064] The present invention also constructs a charging device, including a control module, 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 control module includes a processor and a memory storing a computer program, and the processor block implements the steps of the charging control method described above when executing the computer program.

[0065] Through the technical solution of the present application, it is determined whether a voltage equalization fault or a current equalization fault occurs by detecting the output voltage and internal current of the two DC / DC units. When a voltage equalization fault occurs, a unique software algorithm is used to adjust the output voltage 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; when a current equalization fault occurs, 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. This software-based voltage and current equalization control method not only reduces the cost and size of the charging device, but also improves the reliability of charging control. BRIEF DESCRIPTION OF THE DRAWINGS

[0066] 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:

[0067] Figure 1 It is a circuit diagram of an existing charging device;

[0068] Figure 2 It is a circuit diagram of an existing charging device;

[0069] Figure 3 is a circuit diagram of a DC / DC module of a charging device in one embodiment of the present invention;

[0070] Figure 4 is a flow chart of a charging control method in one embodiment of the present invention;

[0071] Figure 5A is a circuit diagram of an inverter circuit in an LLC converter according to an embodiment of the present invention;

[0072] Figure 5B yes Figure 5A Schematic diagram of the midpoint voltage of the inverter circuit before phase shift;

[0073] Figure 5C yes Figure 5A Schematic diagram of the midpoint voltage of the inverter circuit after phase shift;

[0074] Figure 6 is a flow chart of a first control step in a charging control method in one embodiment of the present invention;

[0075] Figure 7 is a flow chart of the second control step in the charging control method in one embodiment of the present invention;

[0076] Fig. 8A 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;

[0077] Figure 8B 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;

[0078] Figure 8C 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

[0079] 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.

[0080] Figure 4 FIG. 1 is a flow chart of a charging control method according to an embodiment of the present invention. The charging control method according to the embodiment is applied to a control module of a charging device. Figure 1 , 2 The 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.

[0081] like Figure 4 As shown, the charging control method of this embodiment includes:

[0082] Acquisition step S10: acquiring the output voltage and internal current of the two DC / DC units respectively;

[0083] Determining step S20: determining whether a voltage balancing fault occurs according to the output voltages of the two DC / DC units, and determining whether a current balancing fault occurs according to the internal currents of the two DC / DC units. When a voltage balancing fault occurs, executing the first control step S30; when a current balancing fault occurs, executing the second control step S40;

[0084] First control step S30: adjusting the output voltage of the corresponding DC / DC unit by adjusting the control parameters of at least one DC / DC unit, and / or adjusting the output voltage of the two DC / DC units by adjusting the control parameters of the AC / DC module;

[0085] Second control step S40: adjusting the internal current of the corresponding DC / DC unit by adjusting the control parameters of at least one DC / DC unit, and / or adjusting the internal current of the two DC / DC units by adjusting the control parameters of the AC / DC module.

[0086] Through the technical solution of this embodiment, it is determined whether a voltage equalization fault or a current equalization fault occurs by detecting the output voltage and internal current of the two DC / DC units. When a voltage equalization fault occurs, a unique software algorithm is used to adjust the output voltage 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; when a current equalization fault occurs, 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. This software-based voltage and current equalization control method not only reduces the cost and size of the charging device, but also improves the reliability of charging control.

[0087] Further, in an optional embodiment, the DC / DC unit is an LLC converter, such as Figure 3 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 .

[0088] Further, in an optional embodiment, in the first control step S30, adjusting the output voltage of the corresponding DC / DC unit by adjusting the control parameters of at least one DC / DC unit includes:

[0089] adjusting the output voltage of the corresponding DC / DC unit by adjusting the conduction angle of the inverter circuit in at least one DC / DC unit; and / or,

[0090] The output voltage of the corresponding DC / DC unit is adjusted by adjusting the driving density of the inverter circuit in at least one DC / DC unit.

[0091] In a specific embodiment, when adjusting the output voltage of the DC / DC unit by adjusting the conduction angle of the inverter circuit in the DC / DC unit (LLC converter), a conduction angle adjustment loop can be established in the control logic, with the conduction angle as the adjustment object and the output voltage as the feedback object, and the purpose of adjusting the output voltage is achieved by adjusting the conduction angle of the inverter circuit. The adjustment principle of the conduction angle is described below:

[0092] Combination Figure 5A , 5B , 5C, 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.

[0093]

[0094] 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 5B , 5C 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 can be adjusted, that is, the input voltage of the resonant cavity can be adjusted, and the output voltage can be adjusted at the same operating frequency. 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.

[0095] In a specific embodiment, when adjusting the output voltage of the DC / DC unit, it can be achieved by adjusting the driving density of the inverter circuit in the DC / DC unit, and the driving density is related to the wave-generating working time and the wave-generating stopping time. Therefore, the output voltage of the DC / DC unit can be adjusted by adjusting the wave-generating working time and / or the wave-generating stopping time. For example, when the wave-generating working time of the DC / DC unit is reduced, the output voltage of the DC / DC unit can be reduced; when the wave-generating stopping time of the DC / DC unit is increased, the output voltage of the DC / DC unit can be reduced.

[0096] Regarding the above embodiment, it should be noted that when the output voltage deviation is too large, three adjustments can be made: phase shift, input voltage adjustment, and drive density 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.

[0097] Figure 6 This is a flow chart of the first control step in the charging control method in one embodiment of the present invention. First, it is explained that the DC / DC unit with a larger output voltage among the two DC / DC units is used as the first DC / DC unit, and the DC / DC unit with a smaller output voltage among the two DC / DC units is used as the second DC / DC unit. In this embodiment, the first control step:

[0098] Step S311, determining whether the first DC / DC unit meets the phase shift condition, if yes, executing step S312; if no, executing step S313;

[0099] Step S312, reducing the conduction angle of the inverter circuit of the first DC / DC unit, and then executing step S316;

[0100] Step S313, obtaining the current input voltages of the two DC / DC units, and determining whether the input voltage adjustment condition is met according to the current input voltages, if so, executing step S314; if not, executing step S315;

[0101] 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 S316;

[0102] Step S315, reducing the driving density of the inverter circuit of the first DC / DC unit;

[0103] Step S316, obtaining the current output voltages of the two DC / DC units, calculating the current output voltage deviation of the two DC / DC units, and determining whether the current output voltage deviation is less than a first reference threshold value, if so, executing step S317; if not, executing step S311;

[0104] Step S317, maintaining control parameters of the two DC / DC units and the AC / DC module.

[0105] In this embodiment, combined Figure 3 , due to V o1 >V o2 , and satisfy |V o1 -V o2 |=ΔV o ≥V ref_out_max , that is, it is determined that a voltage-sharing fault occurs. When it is determined that a voltage-sharing fault occurs, it is determined whether the conduction angle α of the inverter circuit of the first DC / DC unit satisfies the phase-shift condition. If the phase-shift condition is satisfied, the conduction angle α corresponding to the first DC / DC unit is adjusted to reduce the input voltage of the resonant cavity in the first DC / DC unit and adjust the output voltage of the first DC / DC unit. If the phase-shift condition is not satisfied, it is determined whether the input voltage adjustment condition is satisfied, for example, whether the input voltage deviation satisfies: ΔV i <V ref_in_max , where ΔV i =|V i1 -V i2 | is the input voltage deviation of the two DC / DC units, V ref_in_max The maximum deviation allowed can be a fixed value or can vary with the output voltage. For example, from the perspective of device withstand voltage, as the output voltage increases, the second voltage value decreases. When the input voltage adjustment condition is met, the control parameters of the AC / DC module are adjusted to reduce the input voltage V of the first DC / DC unit. i1 , increase the input voltage V of the second DC / DC unit i2 , but it is necessary to maintain V i1 +V i2 =V i , to meet the system requirements. When the input voltage adjustment condition is not met, the drive density is adjusted to reduce the drive density of the first DC / DC unit. Regardless of the adjustment method, after adjustment, it is determined again whether the output voltage deviation is less than the first reference threshold, that is, whether it satisfies: ΔV o <V ref_out_min If it is satisfied, the adjustment is ended and the control parameters are maintained; if it is not satisfied, a new round of adjustment is started again.

[0106] 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 drive density 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 voltage.

[0107] Furthermore, when the bias voltage cannot be completely eliminated, the bias voltage can be shared by the front and rear stages of the power supply device to expand the tolerance range of the bias voltage. Based on this, in an optional embodiment, the DC / DC unit with a larger output voltage of the two DC / DC units is used as the first DC / DC unit, and the DC / DC unit with a smaller output voltage of the two DC / DC units is used as the second DC / DC unit;

[0108] The first control step comprises:

[0109] Step S321, determining whether the first DC / DC unit meets the phase shift condition, if yes, executing step S322; if no, executing step S323;

[0110] Step S322, reducing the conduction angle of the inverter circuit of the first DC / DC unit, and then executing step S321;

[0111] Step S323, calculating the output voltage deviation of the two DC / DC units according to the output voltages of the two DC / DC units, and determining whether the output voltage deviation is greater than the maximum withstand bias voltage of the DC / DC module, and if so, executing step S324;

[0112] Step S324, determining the minimum input voltage, the maximum input voltage, and the optimal 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;

[0113] Step S325, calculating an output voltage deviation according to the output voltages of the two DC / DC units, and calculating a difference between the output voltage deviation and a maximum bias voltage of the DC / DC module to obtain a bias voltage difference;

[0114] Step S326, determining whether the bias voltage difference is less than or equal to the maximum bias voltage of the AC / DC module, if so, executing step S327; if not, shutting down;

[0115] Step S327, determining a target input voltage of each DC / DC unit according to the bias voltage difference, and the optimal input voltage, the minimum input voltage, and the maximum input voltage of each DC / DC unit;

[0116] Step S328: adjusting the control parameters of the AC / DC module according to the target input voltage of each DC / DC unit.

[0117] In this embodiment, if the output voltage bias amount ΔV o If the output voltage bias ΔVo exceeds the tolerance range of the DC / DC module, the AC / DC module will bear the excess. Specifically:

[0118] First, determine whether the first DC / DC unit can shift phase. If yes, perform phase shift according to step S322. If no, determine whether the DC / DC module can withstand the voltage deviation. If: ΔV o >ΔV o_max =2V o1_max -V o When the output voltage deviation exceeds the tolerance range of the DC / DC module, V o1_max is the maximum voltage that the output capacitor Co1 can withstand. This value is a known quantity and is mainly determined by the device stress. It is usually V o1_max =V o2_max ; V o_max (V o1_max +V o2_max ) is the current output voltage V o The maximum offset voltage that the DC / DC module can withstand under certain conditions.

[0119] When the output voltage deviation exceeds the tolerance range of the DC / DC module, the difference between the output voltage deviation and the maximum tolerance bias voltage, that is, the bias voltage difference, is calculated, and the difference can be tolerated by the AC / DC module. Then, the minimum input voltage, maximum input voltage, and optimal input voltage of each DC / DC unit are determined in the following manner:

[0120] 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.

[0121] 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 (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.

[0122] 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.

[0123]

[0124] 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.

[0125] After the minimum input voltage, maximum input voltage, and optimal input voltage of the DC / DC unit are determined, the maximum bias voltage ΔV of the AC / DC module can be determined according to Formula 4: i_max :

[0126]

[0127] Then, the difference between the output voltage deviation and the maximum bias voltage of the DC / DC module is calculated to obtain the bias voltage difference, and it is determined whether the bias voltage difference is less than or equal to the maximum bias voltage of the AC / DC module, that is, whether the following is satisfied: ΔVo -(2V o1_max -V o )≤ΔV i_max , if so, then 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.

[0128] Further, in an optional embodiment, in step S327, the target input voltage of each DC / DC unit may be determined according to the following method:

[0129] If the optimal input voltage of the DC / DC unit is between the minimum input voltage and the maximum input voltage, determining the target input voltage of each DC / DC unit based on the bias voltage difference and taking the optimal input voltage as the center;

[0130] 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 bias voltage difference;

[0131] 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 bias voltage difference.

[0132] 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, V i1 and V i2 V i_opt / 2 as the center; if the optimal input voltage is less than the minimum input voltage, the input voltage of the first DC / DC unit (the part with the required smaller input voltage) 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, the input voltage of the second DC / DC unit (the part with the required 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.

[0133] Further, in an optional embodiment, in the second control step S40, adjusting the internal current of the corresponding DC / DC unit by adjusting the control parameters of at least one DC / DC unit includes:

[0134] Adjusting the internal current of the corresponding DC / DC unit by adjusting the conduction angle of the inverter circuit in at least one DC / DC unit; and / or,

[0135] The internal currents of the two DC / DC units are adjusted by adjusting the output power of the DC / DC module.

[0136] In this embodiment, the internal current of the LLC converter can be adjusted by adjusting the conduction angle of the inverter circuit in the LLC converter. The adjustment principle is similar to the adjustment principle in the voltage-balanced control loop, and will not be described in detail here. In addition, when adjusting the internal current of the two LLC converters by adjusting the output power of the DC / DC module, an output power adjustment loop can be established in the control logic, with the internal current as the adjustment target and the output power as the feedback 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. At this time, 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.

[0137] 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.

[0138] Figure 7 This is a flow chart of the second control step in the charging control method in one embodiment of the present invention. First, one of the two DC / DC units with a larger internal current is used as the first DC / DC unit, and one of the two DC / DC units with a smaller internal current is used as the second DC / DC unit. The second control step S40 includes:

[0139] Step S411, determining whether the first DC / DC unit meets the phase shift condition, if yes, executing step S412; if no, executing step S413;

[0140] Step S412, reducing the conduction angle of the inverter circuit of the first DC / DC unit, and then executing step S417;

[0141] Step S413, obtaining the current input voltages of the two DC / DC units, and determining whether the input voltage adjustment condition is met according to the current input voltages, if so, executing step S414; if not, executing step S415;

[0142] Step S414, 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;

[0143] Step S415, obtaining the current output power of the DC / DC module, and determining whether the current output power is greater than the output power adjustment condition, if so, executing step S416; if not, shutting down;

[0144] Step S416, reducing the current output power;

[0145] Step S417, obtaining the current internal currents of the two DC / DC units, calculating the current internal current deviation of the two DC / DC units, and determining whether the current internal current deviation is less than a second reference threshold value, if so, executing step S418; if not, executing step S411;

[0146] Step S418, maintaining control parameters of the two DC / DC units and the AC / DC module.

[0147] 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 i1 、V i2 The detection is already available.

[0148] When a current sharing fault occurs, for example, when an excessive internal current deviation is detected, 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 、ip2 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

[0149] Assume that at this time i p1 >i p2 First, determine whether the conduction angle α of the larger part of the resonant current (the first DC / DC unit) meets the phase shift condition, where the judgment 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.

[0150] When the phase shift condition is not met, it is determined whether the input voltage adjustment condition is met, for example, whether the input voltage deviation of the two DC / DC units is too large, that is, whether: 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.

[0151] When the input voltage adjustment condition is not met, it is determined whether the output power adjustment condition is met, for example, it is determined whether the output power is greater than a third preset value, that is, it is determined 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.

[0152] After completing one conduction angle adjustment, input voltage adjustment or output power adjustment, it is detected again whether the internal current deviation of the two groups of DC / DC units is less than the second reference threshold, that is, whether the following is satisfied: ΔI p <V ref_p_max If 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.

[0153] 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.

[0154] Further, in an optional embodiment, the DC / DC unit with a larger internal current of the two DC / DC units is used as the first DC / DC unit, and the DC / DC unit with a smaller internal current of the two DC / DC units is used as the second DC / DC unit. The second control step S40 includes:

[0155] Step S421, determining whether the first DC / DC unit meets the phase shift condition, if yes, executing step S422; if no, executing step S423;

[0156] Step S422, reducing the conduction angle of the inverter circuit of the first DC / DC unit, and then executing step S421;

[0157] Step S423, determining whether the first DC / DC unit has a current greater than a maximum withstand current, if so, executing step S424;

[0158] Step S424, 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;

[0159] Step S425, determining the optimal input voltage of each DC / DC unit;

[0160] Step S426, 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;

[0161] Step S427: adjusting the control parameters of the AC / DC module according to the target input voltage of each DC / DC unit.

[0162] 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, optimal input voltage of the DC / DC unit and the maximum tolerance bias voltage of the AC / DC module can be determined. It should be noted that the determination method of the minimum input voltage, maximum input voltage, optimal input voltage of the DC / DC unit and the maximum tolerance bias voltage of the AC / DC module is the same as that in the voltage balancing control loop, which will not be repeated here. 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.

[0163] Further, in an optional embodiment, in step S426, the target input voltage of each DC / DC unit may be determined according to the following method:

[0164] 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;

[0165] 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;

[0166] 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.

[0167] 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. 8A 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 8B 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 8C 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.

[0168] The present invention also constructs a charging device, which includes a control module, an AC / DC module and a DC / DC module connected to each other, the DC / DC module includes two DC / DC units, the control module includes a processor and a memory storing a computer program, and the processor implements the steps of the charging control method described above when executing the computer program.

[0169] 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 charging 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 steps: respectively acquiring the output voltage and internal current of the two DC / DC units; Determining step: determining whether a voltage sharing fault occurs according to the output voltages of the two DC / DC units, and determining whether a current sharing fault occurs according to the internal currents of the two DC / DC units; First control step: when a voltage balancing fault occurs, adjusting the output voltage of the corresponding DC / DC unit by adjusting the control parameters of at least one DC / DC unit, and / or adjusting the output voltages of the two DC / DC units by adjusting the control parameters of the AC / DC module; Second control step: when a current sharing fault occurs, 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 charging 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 charging control method according to claim 2, characterized in that: The method adjusts the output voltage of the corresponding DC / DC unit by adjusting the control parameter of at least one DC / DC unit, comprising: adjusting the output voltage of the corresponding DC / DC unit by adjusting the conduction angle of the inverter circuit in at least one DC / DC unit; and / or, The output voltage of the corresponding DC / DC unit is adjusted by adjusting the driving density of the inverter circuit in at least one DC / DC unit.

4. The charging control method according to claim 3, characterized in that: The DC / DC unit with a larger output voltage among the two DC / DC units is used as a first DC / DC unit, and the DC / DC unit with a smaller output voltage among the two DC / DC units is used as a second DC / DC unit; The first control step comprises: Step S311, determining whether the first DC / DC unit meets the phase shift condition, if yes, executing step S312; if no, executing step S313; Step S312, reducing the conduction angle of the inverter circuit of the first DC / DC unit, and then executing step S316; Step S313, obtaining the current input voltages of the two DC / DC units, and determining whether the input voltage adjustment condition is met according to the current input voltages, 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 S316; Step S315, reducing the driving density of the inverter circuit of the first DC / DC unit; Step S316, obtaining the current output voltages of the two DC / DC units, calculating the current output voltage deviation of the two DC / DC units, and determining whether the current output voltage deviation is less than a first reference threshold value, if so, executing step S317; if not, executing step S311; Step S317, maintaining control parameters of the two DC / DC units and the AC / DC module.

5. The charging control method according to claim 3, characterized in that: The DC / DC unit with a larger output voltage among the two DC / DC units is used as a first DC / DC unit, and the DC / DC unit with a smaller output voltage among the two DC / DC units is used as a second DC / DC unit; The first 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, calculating the output voltage deviation of the two DC / DC units according to the output voltages of the two DC / DC units, and determining whether the output voltage deviation is greater than the maximum withstand bias voltage of the DC / DC module, and if so, executing step S324; Step S324, determining the minimum input voltage, the maximum input voltage, and the optimal 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, calculating an output voltage deviation according to the output voltages of the two DC / DC units, and calculating a difference between the output voltage deviation and a maximum bias voltage of the DC / DC module to obtain a bias voltage difference; Step S326, determining whether the bias voltage difference is less than or equal to the maximum bias voltage of the AC / DC module, if so, executing step S327; if not, shutting down; Step S327, determining a target input voltage of each DC / DC unit according to the bias voltage difference, and the optimal input voltage, the minimum input voltage, and the maximum input voltage of each DC / DC unit; Step S328: adjusting the control parameters of the AC / DC module according to the target input voltage of each DC / DC unit.

6. The charging 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 DC / DC unit by adjusting the conduction angle of the inverter circuit in at least one DC / DC unit; and / or, The internal currents of the two DC / DC units are adjusted by adjusting the output power of the DC / DC module.

7. The charging control method according to claim 6, 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 second control step comprises: Step S411, determining whether the first DC / DC unit meets the phase shift condition, if yes, executing step S412; if no, executing step S413; Step S412, reducing the conduction angle of the inverter circuit of the first DC / DC unit, and then executing step S417; Step S413, obtaining the current input voltages of the two DC / DC units, and determining whether the input voltage adjustment condition is met according to the current input voltages, if so, executing step S414; if not, executing step S415; Step S414, 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 S415, obtaining the current output power of the DC / DC module, and determining whether the current output power is greater than the output power adjustment condition, if so, executing step S416; if not, shutting down; Step S416, reducing the current output power; Step S417, obtaining the current internal currents of the two DC / DC units, calculating the current internal current deviation of the two DC / DC units, and determining whether the current internal current deviation is less than a second reference threshold value, if so, executing step S418; if not, executing step S411; Step S418, maintaining control parameters of the two DC / DC units and the AC / DC module.

8. The charging control method according to claim 6, 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 second control step comprises: Step S421, determining whether the first DC / DC unit meets the phase shift condition, if yes, executing step S422; if no, executing step S423; Step S422, reducing the conduction angle of the inverter circuit of the first DC / DC unit, and then executing step S421; Step S423, determining whether the first DC / DC unit has a current greater than a maximum withstand current, if so, executing step S424; Step S424, 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 S425, determining the optimal input voltage of each DC / DC unit; Step S426, 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 S427: adjusting the control parameters of the AC / DC module according to the target input voltage of each DC / DC unit.

9. The charging control method according to claim 8, characterized in that: According to the maximum bias voltage of the AC / DC module, the optimal input voltage, minimum input voltage, and maximum input voltage of each DC / DC unit, the target input voltage of each DC / DC unit is determined, including: 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.

10. A charging device, comprising a control module, an AC / DC module and a DC / DC module connected thereto, wherein the DC / DC module comprises two DC / DC units, and the control module comprises a processor and a memory storing a computer program, wherein: The processor block implements the steps of the charging control method according to any one of claims 1 to 9 when executing the computer program.

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