A hierarchical control method and system for a three-phase on-board charger based on battery state.

Abstract

This invention discloses a hierarchical control method and system for a three-phase on-board charger based on battery state. The method includes: acquiring battery state data of the on-board power battery, the battery state data including at least battery voltage and battery state of charge; determining a charging mode based on the battery voltage and / or battery state of charge; controlling the PFC converter to operate in a constant voltage output mode when the charging mode is a first charging mode, while simultaneously performing voltage following control on the bidirectional DC-DC converter based on the battery voltage; and performing voltage following control on the PFC converter based on the battery voltage when the charging mode is a second charging mode, while simultaneously controlling the bidirectional DC-DC converter to operate in a constant frequency or constant phase output mode. This invention adaptively adjusts the output voltage of the PFC converter by setting hierarchical control strategies under different operating conditions, optimizes the voltage regulation ratio under different operating conditions, improves the overall circuit structure, and enhances the charging efficiency of the on-board charger across the entire operating range.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of vehicle-mounted charging control, and particularly relates to a three-phase vehicle-mounted charger grading control method and system based on a battery state. BACKGROUND

[0002] With the popularization of electric vehicles, the performance and efficiency of the vehicle-mounted charger (OBC) as a key component connecting the AC power grid and the vehicle power battery are crucial. Currently, the mainstream high-power vehicle-mounted charger usually adopts a two-stage structure of a front-stage power factor correction (PFC) and a rear-stage DC-DC converter (such as an LLC resonant converter or a dual active bridge DAB converter).

[0003] During the charging process, the voltage of the power battery changes with the state of charge (SOC). The existing charging control strategy usually controls the bus voltage output by the front-stage PFC to remain constant (for example, to remain at 400 V or 800 V), and then adjusts the output voltage through the rear-stage DC-DC converter to make the output voltage follow the change of the battery voltage.

[0004] The existing charging control method has the following problems: the conversion ratio of the rear-stage DC-DC converter needs to consider the entire battery charging range, when the battery voltage is high, the voltage conversion ratio required by the rear-stage DC-DC converter is small. In order to maintain the bus voltage higher than the voltage after the grid rectification, the front-stage PFC needs to continuously perform Boost operation, resulting in unnecessary switching loss and conduction loss, and low energy conversion efficiency. When the battery voltage is low, the voltage conversion ratio required by the rear-stage DC-DC converter is large, and the volume of the voltage regulating element (such as a transformer) needs to be large and the conversion ratio needs to be high, resulting in a large space occupied by the vehicle-mounted charger and high cost. SUMMARY

[0005] The present application provides a three-phase vehicle-mounted charger grading control method and system based on a battery state, which sets grading control strategies under different working conditions, and adaptively adjusts the output voltage of the PFC converter, to solve the problems of low energy conversion efficiency and large voltage conversion ratio of the existing charging control method.

[0006] According to an aspect of the present application, there is provided a battery state-based three-phase vehicle charger grading control method, the three-phase vehicle charger comprising a PFC converter and a bidirectional DC-DC converter, a primary side of the bidirectional DC-DC converter being connected to the PFC converter, a secondary side of the bidirectional DC-DC converter being connected to a vehicle-mounted power battery, the method comprising: obtaining battery state data of the vehicle-mounted power battery; wherein the battery state data at least comprises battery voltage and battery state of charge; determining a charging mode according to the battery voltage and / or the battery state of charge; when the charging mode is a first charging mode, controlling the PFC converter to operate in a constant voltage output mode, and simultaneously performing voltage follow-up control on the bidirectional DC-DC converter based on the battery voltage; when the charging mode is a second charging mode, performing voltage follow-up control on the PFC converter based on the battery voltage, and simultaneously controlling the bidirectional DC-DC converter to operate in a constant frequency or constant phase output mode; the battery voltage value in the first charging mode is less than the battery voltage value in the second charging mode; and / or, the battery remaining capacity in the first charging mode is less than the battery remaining capacity in the second charging mode.

[0007] Optionally, the determining of the charging mode according to the battery voltage and / or the battery state of charge comprises: when the battery voltage is less than a preset voltage threshold, and / or the battery state of charge is less than a preset state of charge threshold, determining the charging mode as the first charging mode; when the battery voltage is greater than or equal to the preset voltage threshold, and / or the battery state of charge is greater than or equal to the preset state of charge threshold, determining the charging mode as the second charging mode.

[0008] Optionally, the preset voltage threshold is any value greater than or equal to 15%*V bat-max and less than or equal to 25%*V bat-max ; wherein the V bat-max represents a maximum voltage value of the battery voltage; and the preset state of charge threshold is any value greater than or equal to 15% and less than or equal to 25%.

[0009] Optionally, the controlling the PFC converter to operate in the constant-voltage output mode and performing voltage following control on the bidirectional DC-DC converter based on the battery voltage when the charging mode is the first charging mode comprises: obtaining a first target voltage in the constant-voltage output mode; wherein the first target voltage is a constant value; adjusting duty cycles of driving signals of each switch tube in the PFC converter so that the output voltage of the PFC converter is equal to the first target voltage; adjusting a switching frequency of a primary side switch tube of the bidirectional DC-DC converter and / or adjusting a phase of the primary side / secondary side of the bidirectional DC-DC converter so that the output voltage of the bidirectional DC-DC converter follows the battery voltage.

[0010] Optionally, the first target voltage is any value greater than or equal to 0.8*V bat and less than or equal to 1.0*V bat ; wherein V bat represents a rated voltage of the vehicle-mounted power battery.

[0011] Optionally, the controlling the PFC converter to operate in the constant-voltage output mode and performing voltage following control on the bidirectional DC-DC converter based on the battery voltage when the charging mode is the first charging mode comprises: obtaining a first target voltage in the constant-voltage output mode; wherein the first target voltage is a constant value; adjusting duty cycles of driving signals of each switch tube in the PFC converter so that the output voltage of the PFC converter is equal to the first target voltage; adjusting a switching frequency of a primary side switch tube of the bidirectional DC-DC converter and / or adjusting a phase of the primary side / secondary side of the bidirectional DC-DC converter so that the output voltage of the bidirectional DC-DC converter follows the battery voltage.

[0012] Optionally, the gain of the bidirectional DC-DC converter satisfies: greater than or equal to 1:1.1 and less than or equal to 1.

[0013] Optionally, the bidirectional DC-DC converter adopts a resonant dual active bridge topology structure.

[0014] Optionally, the PFC converter adopts a three-phase totem-pole bridgeless PFC topology structure.

[0015] According to another aspect of the present application, there is provided a battery state-based three-phase on-board charger hierarchical control system for implementing the above-mentioned battery state-based three-phase on-board charger hierarchical control method, the three-phase on-board charger comprising a PFC converter and a bidirectional DC-DC converter, the primary side of the bidirectional DC-DC converter being connected with the PFC converter, the secondary side of the bidirectional DC-DC converter being connected with an on-board power battery, the system comprising: a data acquisition module for acquiring battery state data of the on-board power battery; wherein the battery state data at least comprises battery voltage and battery state of charge; a hierarchical decision module for determining a charging mode according to the battery voltage and / or the battery state of charge; a drive control module for, when the charging mode is a first charging mode, controlling the PFC converter to operate in a constant voltage output mode, while performing voltage following control on the bidirectional DC-DC converter based on the battery voltage; the drive control module is further configured to, when the charging mode is a second charging mode, perform voltage following control on the PFC converter based on the battery voltage, while controlling the bidirectional DC-DC converter to operate in a constant frequency or constant phase output mode; the battery voltage value in the first charging mode is less than the battery voltage value in the second charging mode; and / or the remaining battery capacity in the first charging mode is less than the remaining battery capacity in the second charging mode.

[0016] Compared with the prior art, the technical scheme of the present application has the following advantages:

[0017] Firstly, global efficiency optimization: when the charging voltage required by the on-board power battery charging is high (i.e. the second charging mode), the output voltage of the PFC converter is controlled to follow the battery voltage floating, and the bidirectional DC-DC converter is allowed to work at the optimal constant frequency / constant phase point, greatly reducing the switching loss and conduction loss of the PFC stage, while the latter stage converter also works in the high efficiency area, thereby significantly improving the overall efficiency of the entire charging system;

[0018] Secondly, high charging reliability: when the charging voltage required by the on-board power battery charging is low (i.e. the first charging mode), the PFC converter is switched back to the bus voltage constant voltage output mode, avoiding the bus voltage being maintained at a high value, ensuring the reliability and stability of the charging process, while reducing the variable ratio of the voltage regulation module, optimizing the circuit structure of the charging system, and reducing the floor area and production cost;

[0019] Thirdly, stress and loss reduction: in both charging modes, the bus voltage is controlled at a level slightly higher than the battery voltage, rather than a fixed high voltage, thereby reducing the overall voltage stress of the charging system, which helps to reduce switching loss and EMI, and improve the reliability of the charging system.

[0020] It is to be understood that the embodiments described herein are merely exemplary of the application and that a person skilled in the art can devise other embodiments without departing from the scope of the present application. It is also to be understood that not all of the benefits described herein need necessarily be realized in any particular embodiment of the application and that various embodiments of the present application can be directed to one or more particular benefits or be directed to no benefits at all. BRIEF DESCRIPTION OF DRAWINGS

[0021] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed in the embodiments will be briefly introduced in the following. 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 any creative effort.

[0022] Figure 1 A flow chart of a three-phase vehicle-mounted charger grading control method based on a battery state provided by the embodiment of the present application;

[0023] Figure 2 A schematic diagram of a topology of a three-phase vehicle-mounted charger provided by the embodiment of the present application;

[0024] Figure 3 A structural schematic diagram of a three-phase vehicle-mounted charger grading control system based on a battery state provided by the embodiment of the present application. DETAILED DESCRIPTION

[0025] In order to make the technical personnel in the art better understand the present application, the technical solutions in the embodiments of the present application will be described clearly and completely in the following with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, but not all. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without any creative effort should be within the scope of protection of the present application.

[0026] It should be noted that the terms "first", "second", and the like in the description and claims of the present application and the above drawings are used to distinguish similar objects, and do not necessarily indicate a specific order or sequence. It should be understood that the data used in this way can be interchanged under appropriate circumstances, so that the embodiments of the present application described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "include" and "have" and any variations thereof are intended to cover non-exclusive inclusion, for example, a process, method, system, product or device including a series of steps or units does not necessarily limit to those steps or units clearly listed, but can include other steps or units not clearly listed or inherent to these processes, methods, products or devices.

[0027] Figure 1A flow chart of a three-phase vehicle-mounted charger grading control method based on a battery state is provided for an embodiment of the present application, and the control method provided by the embodiment can be applied to the application scenario of a three-phase and high-power vehicle-mounted charger.

[0028] Figure 2 A schematic diagram of a topology of a three-phase vehicle-mounted charger is provided for an embodiment of the present application, as shown in Figure 2 The three-phase vehicle-mounted charger of the present application includes a PFC converter and a bidirectional DC-DC converter, the primary side of the bidirectional DC-DC converter is connected with the PFC converter, and the secondary side of the bidirectional DC-DC converter is connected with a vehicle-mounted power battery. The input side of the PFC converter is connected with an AC power grid through a filter circuit, the output side of the PFC converter is connected with the primary side of the bidirectional DC-DC converter, the phase relationship between the input voltage and the input current is adjusted through the combination of a power switch tube (such as a MOS tube) and a freewheeling diode, so that the input current waveform is synchronized with the input voltage waveform, the harmonic pollution is reduced, and the system efficiency is improved. The output voltage of the PFC converter is a bus voltage, denoted as V-BUS; and the output voltage of the secondary side of the bidirectional DC-DC converter is a charging voltage of the vehicle-mounted power battery, denoted as V-out.

[0029] In some optional embodiments, the PFC converter of the present application adopts a three-phase totem pole bridgeless PFC topology structure. Specifically, as shown in Figure 2 The PFC converter of the present application is provided with a high-frequency arm and a low-frequency arm, wherein the high-frequency arm includes a first power switch tube Q1, a second power switch tube Q2, a third power switch tube Q3, a fourth power switch tube Q4, a fifth power switch tube Q5 and a sixth power switch tube Q6, and the low-frequency arm includes a seventh power switch tube Q7 and an eighth power switch tube Q8.

[0030] In some optional embodiments, the bidirectional DC-DC converter of the present application adopts a resonant dual active bridge topology structure. Specifically, as shown in Figure 2As shown, the resonant dual active bridge topology includes a resonant circuit and a dual active bridge circuit (DAB). The resonant circuit includes a first inductor L1, a first capacitor C1, a transformer T1, a second inductor L2 and a second capacitor C2, and constitutes a CLLL resonant circuit structure. In this embodiment, the operating state of the resonant circuit can be adjusted by adjusting the operating frequency. The dual active bridge circuit includes a primary side H-bridge and a secondary side H-bridge. The primary side H-bridge includes a ninth power switch Q9, a tenth power switch Q10, an eleventh power switch Q11 and a twelfth power switch Q12. The secondary side H-bridge includes a thirteenth power switch Q13, a fourteenth power switch Q14, a fifteenth power switch Q15 and a sixteenth power switch Q16. In this embodiment, the operating state of the dual active bridge circuit can be adjusted by using a multiple phase-shift control strategy.

[0031] Referring to Figure 1 and Figure 2 As shown, the battery state-based three-phase vehicle-mounted charger grading control method of the present application includes the following steps:

[0032] S1: obtaining battery state data of a vehicle-mounted power battery;

[0033] The battery state data can be understood as a parameter representing the battery energy storage state. In this embodiment, the battery state data at least includes battery voltage and battery state of charge (SOC). The battery state of charge is a parameter for measuring the ratio of the remaining available capacity of the battery to the fully charged state capacity.

[0034] S2: determining a charging mode according to the battery voltage and / or the battery state of charge;

[0035] The charging mode can be understood as a charging control strategy for adjusting the operating state of the PFC converter and the bidirectional DC-DC converter.

[0036] In this embodiment, determining the charging mode according to the battery voltage and / or the battery state of charge means identifying the charging voltage required for charging the vehicle-mounted power battery according to the battery voltage and / or the battery state of charge, and automatically switching the charging mode according to the charging voltage required for charging the vehicle-mounted power battery. Specifically, when the charging voltage required for charging the vehicle-mounted power battery is low (for example, the battery voltage is lower than a voltage set value or the remaining battery capacity is lower than an SOC set value), the charging mode is set to a first charging mode; when the charging voltage required for charging the vehicle-mounted power battery is high (for example, the battery voltage is higher than the voltage set value or the remaining battery capacity is higher than the SOC set value), the charging mode is set to a second charging mode.

[0037] S3: when the charging mode is the first charging mode, the PFC converter is controlled to operate in the constant voltage output mode, and the voltage follow-up control is performed on the bidirectional DC-DC converter based on the battery voltage.

[0038] S4: when the charging mode is the second charging mode, the voltage follow-up control is performed on the PFC converter based on the battery voltage, and the bidirectional DC-DC converter is controlled to operate in the constant frequency or constant phase output mode.

[0039] In the embodiment, the battery voltage value in the first charging mode is less than the battery voltage value in the second charging mode; and / or, the remaining battery capacity in the first charging mode is less than the remaining battery capacity in the second charging mode.

[0040] Specifically, in the first charging mode, the charging voltage required for charging the vehicle-mounted power battery is low, and the control target of the charger is to keep the bus voltage V-BUS output by the PFC converter stable, and to make the output voltage V-out of the bidirectional DC-DC converter follow the battery voltage of the vehicle-mounted power battery by adjusting the switching frequency of the resonant circuit or the phase of the DAB.

[0041] In the second charging mode, the charging voltage required for charging the vehicle-mounted power battery is high, and the control target of the charger is to make the bus voltage V-BUS output by the PFC converter follow the battery voltage, and to control the resonant circuit to maintain a constant frequency or the DAB to maintain a constant phase.

[0042] Therefore, the technical scheme of the application can switch to the second charging mode when the charging voltage required for charging the vehicle-mounted power battery is high, control the output voltage of the PFC converter to follow the battery voltage, and make the bidirectional DC-DC converter work at an optimal constant frequency / constant phase point, thereby greatly reducing the switching loss and conduction loss of the PFC stage, and making the rear-stage converter work in a high-efficiency region, so as to significantly improve the overall efficiency of the entire charging system; when the charging voltage required for charging the vehicle-mounted power battery is low, the first charging mode is switched to, the PFC converter is switched back to the constant voltage output mode of the bus voltage, the bus voltage is prevented from being continuously maintained at a high value, the reliability and stability of the charging process are ensured, the voltage regulation ratio is reduced, the circuit structure of the charging system is optimized, the floor area and production cost are reduced, the output voltage of the PFC converter is adaptively adjusted by setting the hierarchical control strategy under different working conditions, the voltage regulation ratio under different working conditions is optimized, the overall circuit structure is improved, and the charging efficiency of the vehicle-mounted charger in the full working condition range is improved.

[0043] In some optional embodiments, the determination of the charging mode according to the battery voltage and / or the battery state of charge comprises: determining the charging mode as the first charging mode when the battery voltage is less than a preset voltage threshold, and / or, the battery state of charge is less than a preset state of charge threshold; determining the charging mode as the second charging mode when the battery voltage is greater than or equal to the preset voltage threshold, and / or, the battery state of charge is greater than or equal to the preset state of charge threshold.

[0044] The preset voltage threshold and the preset state of charge threshold can be understood as critical thresholds for grading the charging voltage required for charging the vehicle-mounted power battery.

[0045] Preferably, the preset voltage threshold is any value greater than or equal to 15%*Vbat-max and less than or equal to 25%*Vbat-max; wherein Vbat-max represents the maximum voltage value of the battery voltage; and the preset state of charge threshold is any value greater than or equal to 15% and less than or equal to 25%.

[0046] Exemplarily, taking the single parameter preset state of charge threshold as the grading standard and setting the preset state of charge threshold as 20% as an example, when the battery state of charge is detected to be less than 20%, the charging mode of the current vehicle-mounted charger is determined as the first charging mode; and when the battery state of charge is detected to be greater than or equal to 20%, the charging mode of the current vehicle-mounted charger is determined as the second charging mode.

[0047] Therefore, by reasonably setting the voltage threshold and the SOC threshold, smooth and undisturbed switching between the two working modes can be achieved, and impact on the alternating current power grid side and the vehicle-mounted power battery can be avoided.

[0048] In some optional embodiments, when the charging mode is the first charging mode, the PFC converter is controlled to operate in the constant voltage output mode, and voltage follow-up control is performed on the bidirectional DC-DC converter based on the battery voltage, comprising: obtaining a first target voltage in the constant voltage output mode; wherein the first target voltage is a constant value; adjusting the duty cycle of the driving signal of each switch tube in the PFC converter, so that the output voltage of the PFC converter is equal to the first target voltage; adjusting the switching frequency of the primary side switch tube of the bidirectional DC-DC converter, and / or adjusting the phase of the primary side / secondary side of the bidirectional DC-DC converter, so that the output voltage of the bidirectional DC-DC converter follows the battery voltage.

[0049] Optionally, the first target voltage is any value greater than or equal to 0.8*V bat and less than or equal to 1.0*V bat ; wherein V bat represents the rated voltage of the vehicle-mounted power battery.

[0050] Preferably, the first target voltage is any value greater than or equal to 680V and less than or equal to 750V.

[0051] For example, taking the single parameter preset state of charge threshold as the grading standard, and taking the preset state of charge threshold of 20% as an example, referring to Fig. 2, when the SOC is detected to be lower than 20%, it is determined that the charging voltage required for charging the vehicle-mounted power battery is low, and the output voltage V-BUS of the PFC converter is controlled as follows: by adjusting the duty cycles of the switching tubes Q1 to Q6, the output voltage V-BUS of the PFC converter is maintained at a first target voltage (for example, 750V), while the switching frequency of the primary side switching tubes Q9 to Q12 of the DAB is adjusted, and / or the switching time of the secondary side switching tubes Q13 to Q16 of the DAB is adjusted to change the phase difference between the primary side and the secondary side to control the output voltage V-out, so that the output voltage V-out follows the battery voltage. Figure 2 As shown in Fig. 2, the resonant dual active bridge topology includes a resonant circuit and a dual active bridge circuit DAB, when it is detected that the SOC is lower than 20%, it is determined that the charging voltage required for charging the current vehicle-mounted power battery is low, the output voltage V-BUS of the PFC converter is controlled as follows: by adjusting the duty cycles of the switching tubes Q1 to Q6, the output voltage V-BUS of the PFC converter is maintained at a first target voltage (for example, 750V), while the switching frequency of the primary side switching tubes Q9 to Q12 of the DAB is adjusted, and / or the switching time of the secondary side switching tubes Q13 to Q16 of the DAB is adjusted to change the phase difference between the primary side and the secondary side to control the output voltage V-out, so that the output voltage V-out follows the battery voltage.

[0052] Therefore, the technical scheme of the present application, in the application scenario where the charging voltage required for charging the vehicle-mounted power battery is low, by switching the PFC converter back to the bus voltage constant voltage output mode, and switching the PFC converter back to the bus voltage constant voltage output mode, avoids maintaining the bus voltage at a high value, ensures the reliability and stability of the charging process, reduces the variable ratio of the voltage regulating module, optimizes the circuit structure of the charging system, and reduces the floor area and production cost.

[0053] In some optional embodiments, when the charging mode is the second charging mode, voltage following control is performed on the PFC converter based on the battery voltage, and the bidirectional DC-DC converter is controlled to operate in a constant frequency or constant phase output mode, including: determining a second target voltage according to the battery voltage; wherein the second target voltage follows the fluctuation of the battery voltage; adjusting the duty cycle of the driving signal of each switching tube in the PFC converter, so that the output voltage of the PFC converter is equal to the second target voltage; controlling the primary side switching tube of the bidirectional DC-DC converter to be turned on or turned off based on a preset switching frequency; and adjusting the phase of the secondary side switching tube of the bidirectional DC-DC converter based on a multiple phase shift control strategy, so that the phase difference between the primary side and the secondary side remains constant.

[0054] Preferably, the gain of the bidirectional DC-DC converter of the present application satisfies: greater than or equal to 1:1.1 and less than or equal to 1.

[0055] Optionally, the preset switching frequency can be set to any value greater than or equal to 10KHz and less than or equal to 1MHz.

[0056] Exemplarily, taking the single parameter preset state of charge threshold as the grading standard, and the preset state of charge threshold is set to 20% as an example, referring to Figure 2 As shown in the figure, the resonant dual active bridge topology includes a resonant circuit and a dual active bridge circuit DAB. When it is detected that the SOC is greater than or equal to 20%, it is determined that the charging voltage required for charging the current vehicle-mounted power battery is high. At this time, by adjusting the duty cycle of the PFC switch tube Q1 to Q6, the output voltage V-BUS of the PFC converter is controlled to follow the battery voltage, and the DAB is controlled to keep the primary side switch tube Q9 to Q12 at a constant frequency switch, and then the phase of the secondary side switch tube of the bidirectional DC-DC converter is adjusted by a multiple phase shift control strategy, so that the secondary side H bridge and the primary side H bridge keep a constant phase difference (phase shift angle). When the constant phase charging, the phase shift angle keeps a fixed value, and the output power is proportional to the phase shift angle. By controlling the phase difference between the fundamental wave of the primary side H bridge output voltage and the fundamental wave of the secondary side H bridge output voltage, the charging power from the primary side to the secondary side is adjusted, so that the gain is kept between 1:1.1 and 1:1. The vehicle-mounted power battery is charged.

[0057] Therefore, the technical scheme of the present application, in the application scenario where the charging voltage required for charging the vehicle-mounted power battery is high, by controlling the output voltage of the PFC converter to follow the battery voltage, and making the bidirectional DC-DC converter work at the optimal constant frequency or constant phase point, greatly reduces the switching loss and conduction loss of the PFC stage, and the rear stage converter also works in the high efficiency area, thereby significantly improving the overall efficiency of the whole charging system.

[0058] Based on any of the above embodiments, the present application also provides a three-phase vehicle-mounted charger grading control system based on battery state, Figure 3 A structure diagram of a three-phase vehicle-mounted charger grading control system based on battery state provided by the embodiment of the present application. Referring to Figure 3As shown, the battery state-based three-phase on-board charger hierarchical control system comprises: a data acquisition module 101 configured to acquire battery state data of an on-board power battery; wherein the battery state data at least includes battery voltage and battery state of charge; a hierarchical decision module 102 configured to determine a charging mode according to the battery voltage and / or the battery state of charge; a drive control module 103 configured to, when the charging mode is a first charging mode, control the PFC converter to operate in a constant voltage output mode, and simultaneously perform voltage follow-up control on the bidirectional DC-DC converter based on the battery voltage; the drive control module 103 is further configured to, when the charging mode is a second charging mode, perform voltage follow-up control on the PFC converter based on the battery voltage, and simultaneously control the bidirectional DC-DC converter to operate in a constant frequency or constant phase output mode; the battery voltage value in the first charging mode is less than the battery voltage value in the second charging mode; and / or, the battery remaining capacity in the first charging mode is less than the battery remaining capacity in the second charging mode.

[0059] Therefore, the battery state-based three-phase on-board charger hierarchical control system provided by the embodiments of the present application is used to perform the battery state-based three-phase on-board charger hierarchical control method provided by any of the above embodiments, has the corresponding function modules and beneficial effects of the performing method, and the same parts will not be described herein.

[0060] It should be understood that the above-mentioned various forms of flow can be reordered, added or deleted. For example, each step described in the present application can be executed in parallel, sequentially or in different order, as long as the desired results of the technical solutions of the present application can be achieved, which is not limited herein.

[0061] The above specific embodiments do not constitute a limitation on the protection scope of the present application. Those skilled in the art should understand that various modifications, combinations, sub-combinations and substitutions can be made according to design requirements and other factors. Any modifications, equivalent replacements and improvements made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A battery state-based three-phase on-board charger staging control method, characterized by, The three-phase on-board charger comprises a PFC converter and a bidirectional DC-DC converter, the primary side of the bidirectional DC-DC converter is connected with the PFC converter, the secondary side of the bidirectional DC-DC converter is connected with the on-board power battery, and the method comprises: acquiring battery state data of the on-board power battery; wherein the battery state data at least comprises battery voltage and battery state of charge; determining a charging mode according to the battery voltage and / or the battery state of charge; when the charging mode is a first charging mode, controlling the PFC converter to operate in a constant voltage output mode, and simultaneously performing voltage following control on the bidirectional DC-DC converter based on the battery voltage; when the charging mode is a second charging mode, performing voltage following control on the PFC converter based on the battery voltage, and simultaneously controlling the bidirectional DC-DC converter to operate in a constant frequency or constant phase output mode; the battery voltage value in the first charging mode is less than the battery voltage value in the second charging mode; and / or, the remaining battery capacity in the first charging mode is less than the remaining battery capacity in the second charging mode.

2. The battery state-based three-phase on-board charger staging control method of claim 1, wherein, The determination of the charging mode according to the battery voltage and / or the battery state of charge comprises: when the battery voltage is less than a preset voltage threshold, and / or the battery state of charge is less than a preset state of charge threshold, the charging mode is determined as the first charging mode; when the battery voltage is greater than or equal to the preset voltage threshold, and / or the battery state of charge is greater than or equal to the preset state of charge threshold, the charging mode is determined as the second charging mode.

3. The battery state-based three-phase on-board charger staging control method of claim 2, wherein, The preset voltage threshold is any value greater than or equal to 15%*V bat-max and less than or equal to 25%*V bat-max ; wherein V bat-max represents the maximum voltage value of the battery voltage; The preset state of charge threshold is any value greater than or equal to 15% and less than or equal to 25%.

4. The battery state-based three-phase on-board charger staging control method of claim 1, wherein, The control of the PFC converter to operate in the constant voltage output mode when the charging mode is the first charging mode, and the voltage following control on the bidirectional DC-DC converter based on the battery voltage comprises: acquiring a first target voltage in the constant voltage output mode; wherein the first target voltage is a constant value; adjusting the duty cycle of the driving signal of each switch tube in the PFC converter, so that the output voltage of the PFC converter is equal to the first target voltage; adjusting the switching frequency of the primary side switch tube of the bidirectional DC-DC converter, and / or adjusting the phase of the primary side / secondary side of the bidirectional DC-DC converter, so that the output voltage of the bidirectional DC-DC converter follows the battery voltage.

5. The battery state-based three-phase on-board charger staging control method of claim 4, wherein, the first target voltage is any value greater than or equal to 0.8*V bat and less than 1.0*V bat . wherein V bat represents the rated voltage of the vehicle-mounted power battery.

6. The battery state based three-phase on-board charger staging control method of claim 1, wherein, The voltage following control on the PFC converter based on the battery voltage when the charging mode is the second charging mode, and the control of the bidirectional DC-DC converter to operate in the constant frequency or constant phase output mode comprises: determining a second target voltage according to the battery voltage; wherein the second target voltage follows the fluctuation of the battery voltage; adjusting the duty cycle of the driving signal of each switch tube in the PFC converter, so that the output voltage of the PFC converter is equal to the second target voltage; The primary side switch of the bidirectional DC-DC converter is turned on or turned off based on a preset switching frequency. The phase of the secondary side switch of the bidirectional DC-DC converter is adjusted based on a multiple phase-shift control strategy, so that the phase difference between the primary side and the secondary side is kept constant.

7. The battery state-based three-phase on-board charger staging control method of claim 6, wherein, The gain of the bidirectional DC-DC converter satisfies: greater than or equal to 1:1.1 and less than or equal to 1.

8. The battery state based three-phase on-board charger staging control method of any one of claims 1-7, wherein, The bidirectional DC-DC converter adopts a resonant dual active bridge topology structure.

9. The battery state based three-phase on-board charger staging control method of any one of claims 1-7, wherein, The PFC converter adopts a three-phase totem pole bridgeless PFC topology structure.

10. A battery state based three-phase on-board charger staging control system, comprising: The system is used for performing the battery state-based three-phase on-board charger grading control method in any one of claims 1-9, the three-phase on-board charger comprising a PFC converter and a bidirectional DC-DC converter, the primary side of the bidirectional DC-DC converter being connected with the PFC converter, the secondary side of the bidirectional DC-DC converter being connected with an on-board power battery, and the system comprising: a data acquisition module configured to acquire battery state data of the on-board power battery, wherein the battery state data at least comprises battery voltage and battery state of charge; a grading decision module configured to determine a charging mode according to the battery voltage and / or the battery state of charge; a drive control module configured to, when the charging mode is a first charging mode, control the PFC converter to operate in a constant voltage output mode, and simultaneously perform voltage follow-up control on the bidirectional DC-DC converter based on the battery voltage; the drive control module is further configured to, when the charging mode is a second charging mode, perform voltage follow-up control on the PFC converter based on the battery voltage, and simultaneously control the bidirectional DC-DC converter to operate in a constant frequency or constant phase output mode; the battery voltage value in the first charging mode is less than the battery voltage value in the second charging mode; and / or, the remaining battery capacity in the first charging mode is less than the remaining battery capacity in the second charging mode.

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