Direct current charging control method, controller, direct current charging system and vehicle

Abstract

The invention relates to a direct-current charging control method, a controller, a direct-current charging system and a vehicle, and the direct-current charging control method comprises the following steps executed by the controller: determining the initial voltage of a charging capacitor according to the electrical parameters of a direct-current charging pile before the electric energy output by the direct-current charging pile is accessed; performing power control on a voltage regulation power module based on the initial voltage and the voltage of the bus capacitor so as to adjust the voltage of the charging capacitor to the initial voltage; and after the electric energy output by the direct-current charging pile is accessed, power control is performed on the voltage regulation power module based on the voltage of the charging capacitor and the voltage of the bus capacitor, so that the battery pack is charged through the electric energy output by the direct-current charging pile. As the adopted initial voltage corresponds to the electrical parameters of the direct current charging pile, the voltage of the charging capacitor is prevented from being set as a relatively low fixed value all the time, so that the voltage regulation time of the voltage regulation power module is shortened, and the charging efficiency of the battery pack is further improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of new energy, in particular to a direct current charging control method, a controller, a direct current charging system and a vehicle. BACKGROUND

[0002] In modern electric vehicles and energy storage systems, battery packs usually have high voltage requirements to support their efficient operation and energy storage. However, the voltage provided by an external direct current charging pile may not match the voltage required by the battery pack. Therefore, it is necessary to set a voltage regulating power module to regulate the voltage of the power output by the direct current charging pile.

[0003] The voltage regulating power module ensures efficient use of energy by boosting a lower input voltage to a level suitable for battery pack charging; of course, the voltage regulating power module can also reduce a higher input voltage to a level suitable for battery pack charging. Typically, a charging capacitor and a bus capacitor are provided on the input side and the output side of the voltage regulating power module, respectively, so that the voltage regulating power module controls the voltage difference between the charging capacitor and the bus capacitor to achieve the purpose of voltage regulation.

[0004] However, regardless of the specification of the direct current charging pile connected, the existing scheme sets the voltage of the charging capacitor to a lower fixed value during the charging preparation phase, which results in a longer voltage regulating time of the voltage regulating power module and reduces the charging efficiency of the battery pack. SUMMARY

[0005] The embodiments of the present application provide a direct current charging control method, a controller, a direct current charging system and a vehicle, which can determine the starting voltage of the charging capacitor according to the electrical parameters of the direct current charging pile before the direct current charging pile outputs power, so as to control the power of the voltage regulating power module based on the determined starting voltage and the voltage of the bus capacitor, so that the voltage of the charging capacitor is adjusted to the starting voltage, and then the battery pack can be charged based on the voltage regulation of the starting voltage after the direct current charging pile outputs power. Since the starting voltage corresponds to the electrical parameters of the direct current charging pile, the voltage of the charging capacitor is not always set to a lower fixed value, thereby at least partially solving the above technical problems.

[0006] In order to achieve the above-mentioned purpose, according to the first aspect of the present application, a direct current charging control method is provided, which is applied to a direct current charging system, the direct current charging system includes a charging capacitor, a voltage regulating power module, a bus capacitor which are connected in sequence, and a controller which is electrically connected with the charging capacitor, the voltage regulating power module and the bus capacitor respectively, the charging capacitor is used to be electrically connected with a direct current charging pile, and the bus capacitor is used to be electrically connected with a battery pack; the direct current charging control method includes the following steps performed by the controller:

[0007] Before accessing the electric energy output by the direct-current charging pile, a starting voltage of the charging capacitor is determined according to an electrical parameter of the direct-current charging pile;

[0008] The voltage of the charging capacitor is adjusted to the starting voltage by performing power control on the voltage-regulating power module based on the starting voltage and the voltage of the bus capacitor.

[0009] After accessing the electric energy output by the direct-current charging pile, the voltage of the charging capacitor and the voltage of the bus capacitor are used to perform power control on the voltage-regulating power module to charge the battery pack by using the electric energy output by the direct-current charging pile.

[0010] Optionally, the starting voltage of the charging capacitor is determined according to the electrical parameter of the direct-current charging pile, including:

[0011] The direct-current charging pile is subjected to insulation resistance detection to obtain an insulation resistance detection result; and the electrical parameter includes the insulation resistance detection result.

[0012] The starting voltage is determined according to the insulation resistance detection result.

[0013] Optionally, the starting voltage is determined according to the insulation resistance detection result, including:

[0014] If the insulation resistance detection result indicates that the insulation resistance of the direct-current charging pile can be detected, an initial platform voltage of the direct-current charging pile is determined according to the detected insulation resistance of the direct-current charging pile.

[0015] The starting voltage is determined according to the initial platform voltage.

[0016] Optionally, the starting voltage is determined according to the insulation resistance detection result, including:

[0017] If the insulation resistance detection result indicates that the insulation resistance of the direct-current charging pile cannot be detected, an initial platform voltage of the direct-current charging pile is determined as a preset voltage.

[0018] The starting voltage is determined according to the initial platform voltage.

[0019] Optionally, after the step of performing power control on the voltage-regulating power module based on the voltage of the charging capacitor and the voltage of the bus capacitor, the direct-current charging control method further includes the following steps performed by the controller:

[0020] A target platform voltage sent by the direct-current charging pile is obtained.

[0021] If the target platform voltage is inconsistent with the initial platform voltage, a target voltage of the charging capacitor in a charging process is determined according to the target platform voltage.

[0022] The voltage-regulating power module is subjected to power control based on the target voltage and the voltage of the bus capacitor, so that the voltage of the charging capacitor is adjusted to the target voltage.

[0023] Optionally, the target voltage is greater than the starting voltage; and the power control of the voltage regulating power module is performed based on the target voltage and the voltage of the bus capacitor, so that the voltage of the charging capacitor is adjusted to the target voltage, including:

[0024] The current duty cycle of the voltage regulating power module is gradually reduced based on the target voltage and the voltage of the bus capacitor, so that the voltage of the charging capacitor is gradually increased;

[0025] If the voltage of the charging capacitor is less than the target voltage and it is detected that the DC charging pile has no current output, the current duty cycle of the voltage regulating power module is gradually increased, so that the voltage of the charging capacitor is gradually reduced;

[0026] When it is detected that the DC charging pile resumes current output, the current duty cycle of the voltage regulating power module is maintained unchanged, so that the voltage of the charging capacitor is maintained unchanged.

[0027] Optionally, after the step of performing power control of the voltage regulating power module based on the voltage of the charging capacitor and the voltage of the bus capacitor, the DC charging control method further includes the following steps performed by the controller:

[0028] In response to a heating control instruction for the battery pack, the current duty cycle of the voltage regulating power module is increased, so that the voltage of the charging capacitor is reduced and the heat generated by the voltage regulating power module is increased;

[0029] The heat generated by the voltage regulating power module is used to heat the battery pack through a heat transfer system.

[0030] Optionally, in response to the heating control instruction for the battery, the current duty cycle of the voltage regulating power module is increased, including:

[0031] According to the heating control instruction, a heating level of the battery pack is determined;

[0032] According to the heating level, a target duty cycle of the voltage regulating power module is determined;

[0033] Based on the target duty cycle, the current duty cycle of the voltage regulating power module is increased, so that the current duty cycle of the voltage regulating power module is adjusted to the target duty cycle.

[0034] Optionally, after the step of performing power control of the voltage regulating power module based on the voltage of the charging capacitor and the voltage of the bus capacitor, the DC charging control method further includes the following steps performed by the controller:

[0035] If it is detected that the current output by the DC charging pile is abnormal, the voltage regulating power module is controlled to switch from a three-phase control mode to a single-phase control mode.

[0036] Optionally, after the step of controlling the voltage-regulating power module to switch from the three-phase control mode to the single-phase control mode, the direct current charging control method further comprises the following steps performed by the controller:

[0037] If it is detected that the current output by the direct current charging pile returns to normal, the voltage-regulating power module is controlled to switch from the single-phase control mode to the three-phase control mode.

[0038] According to a second aspect of the present application, a controller is provided, which has stored thereon a computer program that, when executed by a processor, implements the steps of the direct current charging control method in any of the above embodiments.

[0039] According to a third aspect of the present application, a direct current charging system is provided, which comprises the controller in any of the above embodiments and a charging capacitor, a voltage-regulating power module and a bus capacitor connected in sequence.

[0040] The controller is electrically connected to the charging capacitor, the voltage-regulating power module and the bus capacitor respectively.

[0041] According to a fourth aspect of the present application, a vehicle is provided, which comprises the controller in any of the above embodiments or the direct current charging system in any of the above embodiments.

[0042] The direct current charging control method in the present application can determine the starting voltage of the charging capacitor according to the electrical parameters of the direct current charging pile before the direct current charging pile outputs electric energy, so as to control the voltage-regulating power module based on the determined starting voltage and the voltage of the bus capacitor to adjust the voltage of the charging capacitor to the starting voltage, and then charge the battery pack based on the voltage regulation of the starting voltage after the direct current charging pile outputs electric energy. Since the starting voltage corresponds to the electrical parameters of the direct current charging pile, the voltage of the charging capacitor is not always set to a low fixed value, thereby reducing the voltage regulation time of the voltage-regulating power module and improving the charging efficiency of the battery pack.

[0043] Other features and advantages of the present application will be described in detail in the following detailed description. BRIEF DESCRIPTION OF DRAWINGS

[0044] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed in the embodiment description will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0045] In order to more completely understand the present application and its beneficial effects, the following will be described in conjunction with the drawings, wherein the same reference numerals in the following description represent the same parts.

[0046] Figure 1 is a structural schematic diagram of a direct current charging system to which a direct current charging control method provided in an exemplary embodiment of the present application is applied;

[0047] Figure 2 is a specific circuit schematic diagram of a direct current charging system provided in an exemplary embodiment of the present application;

[0048] Figure 3 is a current schematic diagram of an energy storage stage in a voltage regulation process of a direct current charging system provided in an exemplary embodiment of the present application;

[0049] Figure 4 is a current schematic diagram of an energy release stage in a voltage regulation process of a direct current charging system provided in an exemplary embodiment of the present application;

[0050] Figure 5 is a flow schematic diagram of a direct current charging control method provided in an exemplary embodiment of the present application. DETAILED DESCRIPTION

[0051] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the protection scope of the present application.

[0052] According to a first aspect of the present application, a direct current charging control method is provided, which is applied to a direct current charging system, such as Figure 1 as shown, the direct current charging system includes a charging capacitor C1, a voltage regulation power module, a bus capacitor C2 which are electrically connected in sequence, and a controller which is electrically connected with the charging capacitor C1, the voltage regulation power module and the bus capacitor C2 respectively (in Figure 1 , the connection relationship between the controller and the charging capacitor C1 and the bus capacitor C2 is not shown for simplifying the drawings), the charging capacitor C1 is used to be electrically connected with a direct current charging pile, and the bus capacitor C2 is used to be electrically connected with a battery pack.

[0053] Wherein, the voltage of the charging capacitor C1 is V1, the voltage on the bus capacitor C2 is V2, and the voltage regulation power module is used to realize the conversion from the voltage V1 to the voltage V2. Specifically, when the voltage V1 is less than the voltage V2, the voltage regulation power module plays a role of voltage boosting; when the voltage V1 is greater than the voltage V2, the voltage regulation power module plays a role of voltage reducing. The controller, after receiving a charging confirmation signal, performs corresponding power control on the voltage regulation power module based on the size relationship between the voltage V1 and the voltage V2.

[0054] The controller can be a vehicle-mounted controller integrated with a direct current charging function, and specifically can be one or more controllers. The controller can include a direct current charging control guide circuit, which interacts with a direct current charging pile through a charging sub-network (such as through a CAN bus) to control each stage of the direct current charging process (mainly power control of a voltage regulating power module).

[0055] The controller can be a battery manager (BMS) or other independent controller. If the controller is an independent controller, the controller can interact with the battery manager, such as a gun connection signal of a direct current charging pile, a direct current charging confirmation signal, a high-voltage main loop power-on and power-off request signal, and an insulation monitoring command request signal.

[0056] If the controller is an independent controller, the battery manager monitors the cell state (such as single-cell voltage, temperature, maximum allowable charging current, etc.) of the battery pack during direct current charging and calculates the state of charge. When the battery pack does not meet the charging conditions, the controller requests the controller to terminate the direct current charging control. The controller interacts with the voltage regulating power module, such as a voltage regulating power module working command signal and a voltage regulating power module voltage adjustment signal. After receiving the working command signal and the voltage adjustment signal, the voltage regulating power module controls the related power components to adjust the voltage V1 to the voltage V2, and simultaneously feeds back the corresponding voltage, current, temperature, operating state, and fault state, etc. The controller adjusts the subsequent voltage adjustment in real time according to the feedback of the voltage regulating power module and the feedback of the battery manager.

[0057] Figure 2 The specific circuit schematic diagram of the direct current charging system is shown. The voltage regulating power module includes a three-phase winding unit composed of a first winding L1, a second winding L2, and a third winding L3, and a three-phase power bridge unit composed of a switch tube VT1, a switch tube VT2, a switch tube VT3, a switch tube VT4, a switch tube VT5, and a switch tube VT6.

[0058] Wherein, the first winding L1, the second winding L2 and the third winding L3 are electrically connected to a common terminal, and the common terminal is electrically connected to the first end of the charging capacitor C1 through the current sensor A1 and the relay K4, the other end of the first winding L1 is electrically connected to the switch tube VT1 and the switch tube VT2 respectively, the other end of the second winding L2 is electrically connected to the switch tube VT3 and the switch tube VT4 respectively, and the other end of the third winding L3 is electrically connected to the switch tube VT5 and the switch tube VT6 respectively. The first end of the charging capacitor C1 is electrically connected to the positive electrode of the DC charging pile, and the second end of the charging capacitor C1 is electrically connected to the negative electrode of the DC charging pile through the relay K5. The first end of the bus capacitor C2 is electrically connected to the positive electrode of the battery pack through the relay K2, and the second end of the bus capacitor C2 is electrically connected to the negative electrode of the battery pack through the relay K3. The contactor K1 is connected in series with the resistor R1 and then connected in parallel across the contactor K2.

[0059] Wherein, the current sensor A1 is not fixed at the position in Figure 2 , but can also be located at any position in the charging circuit respectively. During the charging process, the controller collects the input current of the charging circuit through the current sensor A1, thereby preventing the battery pack from overcharging.

[0060] Wherein, the voltage V1 of the charging capacitor C1 and the voltage V2 of the bus capacitor C2 can be detected by the corresponding voltage sensor. Based on the principle of constant current charging of the DC charging pile itself, the voltage V3 output by the DC charging pile will be synchronized with the voltage V1 of the charging capacitor C1, that is, when the voltage V1 of the charging capacitor C1 changes, within the voltage range of the DC charging pile, the DC charging pile will adjust the voltage V3 output by it to be consistent with the voltage V1.

[0061] Wherein, the three-phase winding unit can reuse the motor winding in the vehicle, and similarly, the three-phase power bridge unit can also reuse the motor inverter in the vehicle, thereby effectively reducing the hardware cost of the whole vehicle.

[0062] The voltage regulating power module mainly realizes the energy storage and release of the three-phase winding unit by controlling the on-off of the three-phase power bridge unit, thereby achieving the purpose of voltage regulation, and further realizing the conversion of the voltage V1 to the voltage V2.

[0063] As shown in Figure 3As shown, under the premise of turning on contactor K2, contactor K3, contactor K4 and contactor K5, the controller can control the switch tubes VT2, VT4 and VT6 in the three-phase power bridge unit to be turned on, so that the current output from the positive electrode of the DC charging pile passes through the first winding L1, the second winding L2 and the third winding L3 in the three-phase winding unit and the switch tubes VT2, VT4 and VT6 corresponding to the first winding L1, the second winding L2 and the third winding L3 respectively, and then returns to the negative electrode of the DC charging pile, at this time the first winding L1, the second winding L2 and the third winding L3 store energy respectively.

[0064] As shown in Figure 4 After the energy storage is completed, the controller can control the switch tubes VT2, VT4 and VT6 in the three-phase power bridge unit to be turned off and control the switch tubes VT5, VT3 and VT1 to be turned on, so that the electrical energy stored in the first winding L1, the second winding L2 and the third winding L3 can be superimposed with the electrical energy output by the DC charging pile, and finally applied to the battery pack. Compared with the voltage V3 directly output by the DC charging pile, the voltage V2 output to the battery pack through the bus capacitor C2 after the voltage regulation of the voltage regulation power module is improved. According to the periodic control of the conduction and turn-off of the three-phase power bridge unit at a certain duty cycle, the above energy storage and energy release processes can be repeated, so as to realize the stable improvement of the voltage V1 of the charging capacitor C1 to the voltage V2 of the bus capacitor C2.

[0065] It can be understood that before entering the charging process, the pre-charging of the capacitor, especially the pre-charging of the bus capacitor C2, needs to be realized through the contactor K1 and the resistor R1, so as to ensure the reliability of the charging process.

[0066] As shown in Figure 1 and Figure 5 The DC charging control method includes the following steps executed by the controller:

[0067] Step 101, before accessing the electrical energy output by the DC charging pile, according to the electrical parameters of the DC charging pile, the starting voltage of the charging capacitor C1 is determined.

[0068] Among them, the starting voltage and the voltage of the bus capacitor C2 represent the pressure difference required to be adjusted by the voltage regulation power module. The smaller the pressure difference, the shorter the time required for adjustment, so in the boost scenario, the larger the starting voltage is the better.

[0069] The electrical parameter refers to a parameter related to the performance of the direct current charging pile, which can directly or indirectly represent the voltage output capability of the direct current charging pile. The starting voltage determined according to the electrical parameter can exert the voltage output capability of the direct current charging pile as much as possible. For example, if the electrical parameter indicates that the maximum output voltage of the direct current charging pile is 420V, the starting voltage can be set to 420V. Therefore, the starting voltage determined based on the electrical parameter of the direct current charging pile can exert the voltage output capability of the direct current charging pile as much as possible on the one hand, and can reduce the voltage difference between the charging capacitor C1 and the bus capacitor C2 on the other hand.

[0070] In step 102, the voltage V1 of the charging capacitor C1 is adjusted to the starting voltage by performing power control on the voltage regulating power module based on the starting voltage and the voltage V2 of the bus capacitor C2.

[0071] As mentioned above, the voltage regulating power module is used to adjust the voltage difference between the charging capacitor C1 and the bus capacitor C2, and the voltage V2 of the bus capacitor C2 is consistent with the voltage of the battery pack. Therefore, the voltage regulating power module can adjust the voltage difference between the input side and the output side based on the power control of the controller, thereby adjusting the voltage V1 of the charging capacitor C1.

[0072] In step 103, after accessing the electrical energy output by the direct current charging pile, the battery pack is charged by the electrical energy output by the direct current charging pile by performing power control on the voltage regulating power module based on the voltage V1 of the charging capacitor C1 and the voltage V2 of the bus capacitor C2.

[0073] In the above steps, the voltage regulating power module can adjust the voltage difference between the charging capacitor C1 and the bus capacitor C2 to a target value. After the adjustment is completed, not only can the voltage V1 of the charging capacitor C1 be adjusted to the starting voltage, but also the voltage regulating power module can realize the conversion from the voltage V1 to the voltage V2. Since the voltage V3 output by the direct current charging pile can be synchronized with the voltage V1, after accessing the electrical energy output by the direct current charging pile, the voltage regulating power module still converts the voltage V1 to the voltage V2, so that the voltage regulating power module can remain unchanged after completing the adjustment of the voltage V1, and finally realize the charging of the battery pack.

[0074] The direct-current charging control method in the application can determine the starting voltage of the charging capacitor according to the electrical parameters of the direct-current charging pile before the direct-current charging pile outputs electric energy, so as to control the power of the voltage regulating power module based on the determined starting voltage and the voltage of the bus capacitor, so that the voltage of the charging capacitor is adjusted to the starting voltage, and then the battery pack can be charged based on the voltage regulation of the starting voltage after the direct-current charging pile outputs electric energy. Since the starting voltage adopted corresponds to the electrical parameters of the direct-current charging pile, the voltage of the charging capacitor is not always set to a low fixed value, thereby reducing the voltage regulating time of the voltage regulating power module, and thereby improving the charging efficiency of the battery pack.

[0075] Optionally, the starting voltage of the charging capacitor is determined according to the electrical parameters of the direct-current charging pile, comprising:

[0076] The insulation resistance of the direct-current charging pile is detected to obtain an insulation resistance detection result; the electrical parameters include the insulation resistance detection result; and the starting voltage is determined according to the insulation resistance detection result.

[0077] In this embodiment, the starting voltage can be determined based on the insulation resistance detection result.

[0078] Optionally, the starting voltage is determined according to the insulation resistance detection result, comprising:

[0079] If the insulation resistance detection result indicates that the insulation resistance of the direct-current charging pile can be detected, the initial platform voltage of the direct-current charging pile is determined according to the detected insulation resistance of the direct-current charging pile.

[0080] Among them, based on the different hardware and software configurations of different direct-current charging piles, some direct-current charging piles can be detected to correspond to the insulation resistance, and some direct-current charging piles cannot be detected to correspond to the insulation resistance.

[0081] Among them, when the insulation resistance can be detected, the platform voltage to the direct-current charging pile can be determined based on the related analysis strategy. Specifically, the specifications of the direct-current charging piles on the market are usually several, such as 500V or 750V, so the more matched one can be determined according to the insulation resistance, and it is determined as the platform voltage.

[0082] Since the above-mentioned platform voltage is analyzed by the vehicle side based on the insulation resistance detection, and is not directly sent by the direct-current charging pile side, it can be understood as the initial platform voltage.

[0083] If the insulation resistance detection result represents that the insulation resistance of the DC charging pile cannot be detected, the initial platform voltage of the DC charging pile is determined as the preset voltage.

[0084] When the insulation resistance cannot be detected, the actual platform voltage cannot be determined on the vehicle side, and in order to ensure the execution of the subsequent process, the initial platform voltage of the DC charging pile can be set as the preset voltage.

[0085] It should be noted that since the actual platform voltage cannot be determined at present, and the initial platform voltage is used to determine the starting voltage, in order to avoid the starting voltage being higher than the maximum output voltage of the DC charging pile after the charging starts, the preset voltage can be set as a smaller value, such as the platform voltage of the smallest specification of the DC charging pile on the market.

[0086] According to the initial platform voltage, the starting voltage is determined.

[0087] After the initial platform voltage is determined, since the maximum output voltage of the DC charging pile is usually less than its platform voltage due to related loss problems, the starting voltage in this embodiment can be less than the initial platform voltage.

[0088] Optionally, after the step of controlling the power of the voltage regulating power module based on the voltage of the charging capacitor and the voltage of the bus capacitor, the DC charging control method further includes the following steps performed by the controller:

[0089] The target platform voltage sent by the DC charging pile is obtained.

[0090] The DC charging pile performs signal interaction with the controller after the charging starts, so as to send the corresponding platform voltage, and since the platform voltage is directly sent by the DC charging pile, it can be understood as the target platform voltage.

[0091] If the target platform voltage and the initial platform voltage are inconsistent, the target voltage of the charging capacitor in the charging process is determined according to the target platform voltage.

[0092] There are two cases that can cause the target platform voltage and the initial platform voltage to be inconsistent.

[0093] The first case: the initial platform voltage is obtained based on the preset voltage, at this time the initial platform voltage is hypothetical, if the actual platform voltage is higher than the preset voltage, when the DC charging pile sends the target platform voltage, it will cause the target platform voltage and the initial platform voltage to be inconsistent.

[0094] The second case: the initial platform voltage is obtained based on the insulation resistance, at this time the initial platform voltage is real, when the DC charging pile sends a false target platform voltage due to related factors, it will cause the target platform voltage and the initial platform voltage to be inconsistent.

[0095] When the target platform voltage and the initial platform voltage are inconsistent, generally, the target platform voltage sent by the direct-current charging pile has higher priority, and thus the target voltage of the charging capacitor in the charging process can be re-determined based on the target platform voltage.

[0096] The power control is performed on the voltage regulating power module based on the target voltage and the voltage of the bus capacitor, so that the voltage of the charging capacitor is adjusted to the target voltage.

[0097] The target voltage is similar to the initial voltage, and the specific determination manner can be referred to the above embodiment, which will not be described here.

[0098] Optionally, the target voltage is greater than the initial voltage, and the power control is performed on the voltage regulating power module based on the target voltage and the voltage of the bus capacitor, so that the voltage of the charging capacitor is adjusted to the target voltage, including:

[0099] The current duty cycle of the voltage regulating power module is gradually reduced based on the target voltage and the voltage of the bus capacitor, so that the voltage of the charging capacitor is gradually increased.

[0100] When the target platform voltage is greater than the initial platform voltage, the target voltage determined is also greater than the initial voltage, and at this time, the voltage of the charging capacitor needs to be increased. Specifically, since the voltage of the bus capacitor is basically unchanged, the essence of controlling the voltage of the charging capacitor to increase is to control the voltage difference between the charging capacitor and the bus capacitor to be smaller, so that the current duty cycle of the voltage regulating power module is gradually reduced.

[0101] It should be noted that since the target platform voltage is also not completely reliable, the voltage adjustment of the charging capacitor needs to be gradually performed to ensure that the adjustment strategy can be changed in time when the adjustment fails.

[0102] If the voltage of the charging capacitor is less than the target voltage and it is detected that the direct-current charging pile has no current output, the current duty cycle of the voltage regulating power module is gradually increased, so that the voltage of the charging capacitor is gradually reduced.

[0103] When the target platform voltage sent by the direct-current charging pile is false, the target voltage determined will be greater than the maximum output voltage of the direct-current charging pile, and thus the voltage of the charging capacitor is likely to be greater than the maximum output voltage of the direct-current charging pile during the adjustment of the voltage of the charging capacitor based on the target voltage, which causes the direct-current charging pile to be unable to synchronize with the voltage of the charging capacitor, and further causes the direct-current charging pile to be unable to output current.

[0104] At this time, the adjustment strategy needs to be changed to reduce the voltage of the charging capacitor. Specifically, since the voltage of the bus capacitor is basically unchanged, the essence of controlling the voltage reduction of the charging capacitor is to control the voltage difference between the charging capacitor and the bus capacitor to become larger, so that the current duty cycle of the voltage regulating power module can be gradually increased.

[0105] When the direct current charging pile resumes current output, the current duty cycle of the voltage regulating power module is maintained unchanged to maintain the voltage of the charging capacitor unchanged.

[0106] Wherein, when the current resumes, it means that the voltage of the charging capacitor has not been greater than the maximum output voltage of the direct current charging pile, so that the voltage adjustment of the charging capacitor can be ended.

[0107] In order to make the above embodiment more clear, the above embodiment will be illustrated by taking Figure 2 .

[0108] If the platform voltage to the direct current charging pile can be determined to be 500V before charging starts or the platform voltage cannot be determined, and 500V is the minimum platform voltage of the existing direct current charging pile on the market, then the initial platform voltage can be directly determined as 500V for both cases.

[0109] In the charging preparation stage, the starting voltage of the charging capacitor C1 is set as 420V. The controller first controls the contactors K2, K3, K4 and K5 to be turned on, and then controls the duty cycle of the three-phase power bridge unit, so as to adjust the voltage V1 of the charging capacitor C1 to 420V. Based on the principle of constant current charging, the direct current charging pile will synchronize the output voltage V3 to 420V.

[0110] In the charging stage, if the target platform voltage sent by the direct current charging pile is greater than 500V, such as 750V, the controller controls the duty cycle of the three-phase power bridge unit to decrease to increase the voltage V1 of the charging capacitor C1. If the voltage V1 of the charging capacitor C1 is increased to 610V, the direct current charging pile has no current output, at this time, it means that the maximum output voltage of the direct current charging pile is less than 610V, the controller controls the duty cycle of the three-phase power bridge unit to increase to reduce the voltage V1 of the charging capacitor C1 until the direct current charging pile resumes current output. If the voltage V1 of the charging capacitor C1 is 600V when the current output resumes, the controller controls the duty cycle of the three-phase power bridge unit to remain unchanged to maintain the voltage V1 of the charging capacitor C1 as 600V.

[0111] If the platform voltage to the direct current charging pile can be determined to be 750V before charging starts.

[0112] In the charging preparation phase, if the highest voltage of the battery pack is less than 750V, such as 720V, the initial voltage of the charging capacitor C1 can be set to 720V. The controller first controls the contactors K2, K3, K4 and K5 to be turned on, and then controls the duty ratio of the three-phase power bridge unit, so as to adjust the voltage V1 of the charging capacitor C1 to 720V. Based on the principle of constant current charging, the output voltage V3 of the DC charging pile is synchronized to 720V.

[0113] In the charging process phase, since the voltage V1 of the charging capacitor C1 is equal to the voltage V2 of the bus capacitor C2, the voltage regulating power module does not need to be boosted or stepped down, and the DC charging pile output power can be directly transmitted to the battery pack through the body diode in the switching tube VT1, the body diode in the switching tube VT3 and the body diode in the switching tube VT5.

[0114] If the highest voltage of the battery pack is greater than 750V, the charging control is performed according to the steps of the 500V DC charging pile described above, which will not be repeated here.

[0115] Optionally, after the step of controlling the power of the voltage regulating power module based on the voltage of the charging capacitor and the voltage of the bus capacitor, the DC charging control method further comprises the following steps performed by the controller:

[0116] In response to the heating control instruction of the battery pack, the current duty ratio of the voltage regulating power module is increased to reduce the voltage of the charging capacitor and increase the heat generated by the voltage regulating power module.

[0117] The heating control instruction can be generated by the controller detecting the temperature of the battery pack, for example, when the controller detects the temperature of the battery pack, if the temperature of the battery pack is lower than the preset temperature threshold, the heating control instruction is generated. Of course, in other embodiments, the heating control instruction can also be input by the user or other controller.

[0118] The voltage regulating power module generates corresponding heat in power control, and the more the duty ratio, the more the corresponding heat. Therefore, when there is a heating control instruction, the controller controls the increase of the duty ratio of the voltage regulating power module to increase the heat generated by the voltage regulating power module to meet the heating demand of the battery pack.

[0119] It should be noted that the heat generated by the voltage regulating power module can also be used for battery pack heating without increasing the duty ratio of the voltage regulating power module. The embodiment increases the heat generated by the voltage regulating power module to meet the new heating demand of the battery pack.

[0120] The heat generated by the voltage regulating power module is used to heat the battery pack through the heat transfer system.

[0121] The heat transfer system includes, but is not limited to, a heat exchanger, a fan, a compressor, and a refrigerant.

[0122] In addition, although the input side voltage of the voltage regulation power module (i.e., the voltage of the charging capacitor) is reduced, due to the constant power characteristic of the direct current charging pile, when the output voltage is low, the output current can be increased. At this time, only the input side voltage of the voltage regulation power module needs to be dynamically adjusted according to the thermal management target of the battery pack and the charging power, so as to keep a relatively balanced state, which can ensure the charging power and at the same time, as much as possible, utilize the working heat of the voltage regulation power module to improve the efficiency of thermal management.

[0123] Optionally, in response to the heating control instruction of the battery, the current duty cycle of the voltage regulation power module is increased, including:

[0124] According to the heating control instruction, the heating level of the battery pack is determined.

[0125] The heating level is included in the heating control instruction, and the heating control instruction is different at different battery pack temperatures, and the included heating level is also different.

[0126] According to the heating level, the target duty cycle of the voltage regulation power module is determined.

[0127] In this embodiment, the heating level and the required heat can be positively correlated, and the higher the heating level, the more heat required, and therefore the larger the target duty cycle determined.

[0128] Based on the target duty cycle, the current duty cycle of the voltage regulation power module is increased, so that the current duty cycle of the voltage regulation power module is adjusted to the target duty cycle.

[0129] For the duty cycle adjustment of the voltage regulation power module, in order to ensure the stability of the system, the adjustment can be gradually adjusted.

[0130] Optionally, after the step of controlling the power of the voltage regulation power module based on the voltage of the charging capacitor and the voltage of the bus capacitor, the direct current charging control method further includes the following steps performed by the controller:

[0131] If it is detected that the current output by the direct current charging pile is abnormal, the voltage regulation power module is controlled to switch from the three-phase control mode to the single-phase control mode.

[0132] In this embodiment, since the voltage regulation power module needs to switch from the three-phase control mode to the single-phase control mode, the voltage regulation power module needs to be a three-phase structure. When the voltage regulation power module is a single-phase structure, the steps of this embodiment do not need to be performed.

[0133] Wherein, due to some uncontrollable factors, the output current of the direct current charging pile may abnormally decrease or continuously maintain a small current output level. At this time, in the case that the charging power is originally low, the three-phase control in the voltage regulating power module will bring relatively large loss due to the complexity of its structure, which seriously affects the charging efficiency of the entire direct current charging system. Therefore, in the embodiment, the controller can perform scene recognition, and after recognizing the scene, switch the three-phase control of the voltage regulating power module to single-phase control, simplify the control system, and reduce the working components, so as to achieve efficiency improvement under specific working scenes.

[0134] Optionally, after the step of controlling the voltage regulating power module to switch from the three-phase control mode to the single-phase control mode, the direct current charging control method further includes the following steps performed by the controller:

[0135] If it is detected that the output current of the direct current charging pile returns to normal, the voltage regulating power module is controlled to switch from the single-phase control mode to the three-phase control mode.

[0136] Wherein, when it is recognized that the output current of the direct current charging pile returns to normal, the three-phase control is switched back from the single-phase control, avoiding single-phase overload caused by long-time maintenance of single-phase control, thereby improving the stability and reliability of the system.

[0137] According to a second aspect of the present application, a controller is provided, which has a computer program stored thereon, and the computer program is executed by a processor to implement the steps of the direct current charging control method in any of the above embodiments.

[0138] The direct current charging control method performed by the controller in the present application can determine the starting voltage of the charging capacitor before the direct current charging pile outputs electric energy according to the electrical parameters of the direct current charging pile, so as to control the voltage regulating power module based on the determined starting voltage and the voltage of the bus capacitor, so as to adjust the voltage of the charging capacitor to the starting voltage, and then charge the battery pack based on the voltage regulation of the starting voltage after the direct current charging pile outputs electric energy. Since the starting voltage corresponds to the electrical parameters of the direct current charging pile, the voltage of the charging capacitor is not always set to a low fixed value, thereby reducing the voltage regulating time of the voltage regulating power module, and thereby improving the charging efficiency of the battery pack.

[0139] According to a third aspect of the present application, as Figure 1 shown, a direct current charging system is provided, which includes the controller in any of the above embodiments and the charging capacitor C1, the voltage regulating power module and the bus capacitor C2 connected in sequence;

[0140] The controller is electrically connected with the charging capacitor C1, the voltage regulating power module and the bus capacitor C2 respectively.

[0141] According to a fourth aspect of the present application, a vehicle is provided, which comprises the controller of any of the above embodiments, or which comprises the direct current charging system of any of the above embodiments.

[0142] In the description of the present application, the terms "first", "second", etc. are used only for the purpose of description, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the technical features indicated. Therefore, the features defined with "first", "second" can explicitly or implicitly include one or more features. In the description of the present application, the meaning of "multiple" is two or more, unless otherwise specifically limited.

[0143] In the above embodiments, the description of each embodiment is focused on, and the parts not described in detail in a certain embodiment can be referred to the related description of other embodiments.

[0144] The embodiments, implementation manners and related technical features of the present application can be combined or replaced with each other without conflict.

[0145] The above is only the preferred embodiment of the present application, and does not limit the present application in any form. In the embodiments of the present application, the description of each embodiment is focused on, and the parts not described in detail in a certain embodiment can be referred to the related content of other embodiments. Any brief modification, equivalent change and modification made according to the technical essence of the present application to the above embodiments, as long as it does not deviate from the technical solution content of the present application, still belongs to the scope of the technical solution of the present application.

Claims

1. A DC charging control method, characterized in that: Applicable to a DC charging system, the DC charging system includes a charging capacitor, a voltage regulating power module, a bus capacitor electrically connected in sequence, and a controller electrically connected to the charging capacitor, the voltage regulating power module, and the bus capacitor, respectively. The charging capacitor is used to electrically connect to a DC charging pile, and the bus capacitor is used to electrically connect to a battery pack. The DC charging control method includes the following steps performed by the controller: Before connecting to the electric energy output by the DC charging pile, determining the starting voltage of the charging capacitor according to the electrical parameters of the DC charging pile; Based on the starting voltage and the voltage of the bus capacitor, power control is performed on the voltage regulating power module so that the voltage of the charging capacitor is adjusted to the starting voltage; After receiving the electric energy output by the DC charging pile, the voltage regulating power module is power controlled based on the voltage of the charging capacitor and the voltage of the bus capacitor to charge the battery pack through the electric energy output by the DC charging pile.

2. The DC charging control method according to claim 1, wherein: The step of determining the starting voltage of the charging capacitor according to the electrical parameters of the DC charging pile includes: Performing insulation resistance testing on the DC charging pile to obtain an insulation resistance test result; the electrical parameter includes the insulation resistance test result; The starting voltage is determined according to the insulation resistance detection result.

3. The DC charging control method according to claim 2, wherein: The determining the starting voltage according to the insulation resistance detection result includes: If the insulation resistance detection result indicates that the insulation resistance of the DC charging pile can be detected, determining the initial platform voltage of the DC charging pile according to the detected insulation resistance of the DC charging pile; The starting voltage is determined according to the initial platform voltage.

4. The DC charging control method according to claim 2, wherein: The determining the starting voltage according to the insulation resistance detection result includes: If the insulation resistance detection result indicates that the insulation resistance of the DC charging pile cannot be detected, determining that the initial platform voltage of the DC charging pile is a preset voltage; The starting voltage is determined according to the initial platform voltage.

5. The DC charging control method according to claim 3 or 4, characterized in that: After the step of controlling the power of the voltage regulating power module based on the voltage of the charging capacitor and the voltage of the bus capacitor, the DC charging control method further includes the following steps performed by the controller: Obtaining the target platform voltage sent by the DC charging pile; If the target platform voltage is inconsistent with the initial platform voltage, determining the target voltage of the charging capacitor during the charging process according to the target platform voltage; Based on the target voltage and the voltage of the bus capacitor, power control is performed on the voltage regulating power module to adjust the voltage of the charging capacitor to the target voltage.

6. The DC charging control method according to claim 5, characterized in that: The target voltage is greater than the starting voltage; and the power control of the voltage regulating power module based on the target voltage and the voltage of the bus capacitor so as to adjust the voltage of the charging capacitor toward the target voltage includes: Based on the target voltage and the voltage of the bus capacitor, controlling the current duty cycle of the voltage regulating power module to gradually decrease so that the voltage of the charging capacitor gradually increases; If the voltage of the charging capacitor is less than the target voltage and it is detected that the DC charging pile has no current output, controlling the current duty cycle of the voltage regulating power module to gradually increase so that the voltage of the charging capacitor gradually decreases; When it is detected that the DC charging pile resumes current output, the current duty cycle of the voltage regulating power module is controlled to remain unchanged, so that the voltage of the charging capacitor remains unchanged.

7. The DC charging control method according to claim 1, wherein: After the step of controlling the power of the voltage regulating power module based on the voltage of the charging capacitor and the voltage of the bus capacitor, the DC charging control method further includes the following steps performed by the controller: In response to a heating control instruction for the battery pack, controlling the current duty cycle of the voltage regulating power module to increase, so that the voltage of the charging capacitor decreases and the heat generated by the voltage regulating power module increases; The heat generated by the voltage regulating power module is used to heat the battery pack through a heat transfer system.

8. The DC charging control method according to claim 7, characterized in that: In response to the heating control instruction for the battery, controlling the current duty cycle of the voltage regulating power module to increase includes: determining a heating level of the battery pack according to the heating control instruction; determining a target duty cycle of the voltage regulating power module according to the heating level; Based on the target duty cycle, the current duty cycle of the voltage regulating power module is controlled to increase, so that the current duty cycle of the voltage regulating power module is adjusted to the target duty cycle.

9. The DC charging control method according to claim 1, wherein: After the step of controlling the power of the voltage regulating power module based on the voltage of the charging capacitor and the voltage of the bus capacitor, the DC charging control method further includes the following steps performed by the controller: If it is detected that the current output by the DC charging pile is abnormal, the voltage regulating power module is controlled to switch from the three-phase control mode to the single-phase control mode.

10. The DC charging control method according to claim 9, characterized in that: After the step of controlling the voltage regulating power module to switch from the three-phase control mode to the single-phase control mode, the DC charging control method further includes the following steps performed by the controller: If it is detected that the current output by the DC charging pile returns to normal, the voltage regulating power module is controlled to switch from the single-phase control mode to the three-phase control mode.

11. A controller having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps of the DC charging control method according to any one of claims 1 to 10 are implemented.

12. A DC charging system, characterized in that: The controller comprises the controller according to claim 11 and a charging capacitor, a voltage regulating power module and a bus capacitor electrically connected in sequence; The controller is electrically connected to the charging capacitor, the voltage regulating power module and the bus capacitor respectively.

13. A vehicle, characterized in that: Includes the controller according to claim 11, or includes the DC charging system according to claim 12.

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