Vehicle-mounted bidirectional DCDC converter and vehicle

Abstract

The application relates to the technical field of vehicles and discloses a vehicle-mounted bidirectional DCDC converter and a vehicle. The vehicle-mounted bidirectional DCDC converter at least comprises a power conversion unit and a control unit; the power conversion unit at least adopts a three-phase interleaved parallel topology, and three-phase driving phases are sequentially staggered by a preset phase angle; the control unit is connected with the power conversion unit and is at least used for outputting three-phase driving signals according to a battery load to control on or off of switching devices in the power conversion unit. The application can at least solve the problem that the existing bidirectional DCDC is not accurate in battery charging and discharging control due to the fixed energy bidirectional logic, can control on or off of switching devices for power conversion according to the battery load, and is beneficial to improving the accuracy of battery charging and discharging control.

Description

Technical Field

[0001] This invention relates to the field of vehicle technology, and in particular to an on-board bidirectional DC-DC converter and vehicle. Background Technology

[0002] Currently, commercially available 48V / 12V bidirectional DC-DC converters generally use silicon MOS and two-phase Buck / Boost discrete topologies, which at least have the problem of fixed bidirectional energy logic, that is, only the duty cycle is fixed for voltage regulation, resulting in inaccurate battery charging and discharging control. Summary of the Invention

[0003] The purpose of this invention is to provide an on-board bidirectional DC-DC converter and vehicle, which can at least solve the problem of inaccurate battery charging and discharging control caused by the fixed bidirectional energy logic in existing bidirectional DC-DC converters. It can control the on / off of the power conversion switching device according to the battery load, which helps to improve the accuracy of battery charging and discharging control.

[0004] To address the aforementioned technical problems, in a first aspect, the present invention provides an on-board bidirectional DC-DC converter, comprising at least: The power conversion unit adopts at least a three-phase interleaved parallel topology, with the three-phase drive phases staggered by a preset phase angle in sequence; The control unit, connected to the power conversion unit, is at least used to output a three-phase drive signal according to the battery load to control the switching devices in the power conversion unit to turn on or off.

[0005] Optionally, the power conversion unit includes at least a first switching device, a second switching device, a third switching device, a fourth switching device, a fifth switching device, a sixth switching device, a seventh switching device, an eighth switching device, a ninth switching device, a tenth switching device, a first capacitor, a second capacitor, a third capacitor, a fourth capacitor, a fifth capacitor, a sixth capacitor, a seventh capacitor, a first inductor, a second inductor, a third inductor, a first resistor, a second resistor, and a third resistor; The first terminal of the first switching device serves as the input terminal of the power conversion unit, and the second terminal of the first switching device is connected to the first terminal of the second switching device. The second terminal of the second switching device is connected to the first terminal of the third switching device; The second terminal of the third switching device is connected to the first terminal of the first inductor; The second end of the first inductor is connected to the first end of the first resistor; The second end of the first resistor is connected to the first end of the ninth switching device; The second terminal of the ninth switching device is connected to the first terminal of the tenth switching device; The second terminal of the tenth switching device serves as the output terminal of the power conversion unit. The first terminal of the first capacitor is connected to the second terminal of the second switching device, and the second terminal of the first capacitor is connected to the first terminal of the second capacitor. The second terminal of the second capacitor is connected to the first terminal of the third capacitor; The second terminal of the third capacitor is grounded; The first terminal of the fourth switching device is connected to the second terminal of the third switching device, and the second terminal of the fourth switching device is connected to the second terminal of the first capacitor. The first terminal of the sixth capacitor is connected to the second terminal of the first resistor, and the second terminal of the sixth capacitor is connected to the second terminal of the fourth switching device and grounded. The first terminal of the seventh capacitor is connected to the second terminal of the tenth switching device, and the second terminal of the seventh capacitor is grounded. The first terminal of the fifth switching device is connected to the first terminal of the second capacitor, and the second terminal of the fifth switching device is connected to the first terminal of the second inductor; The second terminal of the second inductor is connected to the first terminal of the second resistor; The second terminal of the second resistor is connected to the first terminal of the sixth capacitor; The first terminal of the sixth switching device is connected to the second terminal of the fifth switching device, and the second terminal of the sixth switching device is connected to the second terminal of the second capacitor; The first terminal of the fifth capacitor is connected to the second terminal of the second resistor, and the second terminal of the fifth capacitor is connected to the second terminal of the sixth switching device and grounded. The first terminal of the seventh switching device is connected to the first terminal of the third capacitor, and the second terminal of the seventh switching device is connected to the first terminal of the third inductor; The second terminal of the third inductor is connected to the first terminal of the third resistor; The second end of the third resistor is connected to the second end of the second resistor; The first terminal of the eighth switching device is connected to the second terminal of the seventh switching device, and the second terminal of the eighth switching device is connected to the second terminal of the third capacitor; The first terminal of the fourth capacitor is connected to the second terminal of the third resistor, and the second terminal of the fourth capacitor is connected to the second terminal of the eighth switching device.

[0006] Optionally, the power conversion unit includes at least a boost mode; When the power conversion unit is in the boost mode, the first, second, ninth, and tenth switching devices are continuously turned on, the fourth, sixth, and eighth switching devices are turned on in an alternating manner, and the third, fifth, and seventh switching devices are synchronously complementary in rectification.

[0007] Optionally, the power conversion unit includes at least a buck mode; When the power conversion unit is in the buck mode, the first switching device, the second switching device, the ninth switching device, and the tenth switching device are continuously turned on; The third, fifth, and seventh switching devices are interleaved in conduction. The fourth, sixth, and eighth switching devices perform synchronous complementary rectification.

[0008] Optionally, the three-phase drive signal is output in at least the following ways: When the battery load is within the first load range, the three-phase drive signal is subjected to Burst intermittent modulation, and the switching frequency is reduced to a preset frequency range. When the battery load is within the second load range, the three-phase drive signal adopts interleaved PWM at a set frequency, operates in soft-switching mode, and achieves full-phase soft switching based at least on the resonance of the topological inductance and the switching junction capacitance. When the battery load is in the third load range, the three-phase drive signal adopts ZVS zero-voltage turn-on phase shift control, and the zero-voltage turn-on range is widened by bridge arm phase shift.

[0009] Optionally, it may also include at least an input filtering unit and an output filtering unit; The input filtering unit is connected to the input terminal of the power conversion unit and is used at least to filter the input preset level voltage to obtain the converted input voltage to be input to the power conversion unit. The output filtering unit is connected to the output terminal of the power conversion unit and is used at least to filter the voltage output by the power conversion unit to obtain a converted output voltage of a set voltage level.

[0010] Optionally, it may also include at least an electrical signal sampling unit, a temperature sampling feedback unit, a graded protection unit, and a vehicle communication unit; The control unit establishes connections with the electrical signal sampling unit, the temperature sampling feedback unit, the graded protection unit, and the vehicle communication unit, respectively. The electrical signal sampling unit is used to collect at least the transformation input voltage, bus voltage, transformation output voltage, inductor current, transformation input current, and transformation output current; The temperature sampling feedback unit is used at least to collect the temperature of the switching devices and the inductor in the power conversion unit; The graded protection unit includes at least a fast-blow fuse connected in series at the input terminal of the power conversion unit, a TVS transient suppression tube connected in parallel on the high and low voltage sides, and a reverse anti-current diode added in the converter to isolate the power circuit from the battery. The vehicle communication unit is at least connected to the vehicle's CAN bus to upload DC-DC status, temperature, and power parameters in real time, and to receive VCU power commands.

[0011] Optionally, the control unit is also configured to perform multi-level protection procedures based at least on three-phase analog quantities; The three-phase analog quantities include at least the transformation input voltage, the bus voltage, the transformation output voltage, the inductor current, the transformation input current, the transformation output current, the switching device temperature, and the inductor temperature; The multi-level protection process includes at least the following steps: S1. In response to the power-on of the vehicle system, the control unit starts the cycle timer interrupt and synchronously acquires the three-phase analog quantity; S2. After the control unit performs sampling filtering on the three-phase analog quantity, it reads the preset threshold table to determine at least the first-level warning threshold parameter group, the second-level protection threshold parameter group and the third-level protection threshold parameter group, and then determines whether the three-phase analog quantity meets the first-level warning condition. S3. When the three-phase analog quantity meets the first-level early warning condition, the control unit performs the first-level early warning action, marks the early warning flag and uploads the alarm to the host computer, and then determines whether the duration of the first-level early warning exceeds the limit. S4. When the duration of the first-level warning exceeds the limit, the control unit determines whether the three-phase analog quantity meets the second-level protection conditions. S5. When the three-phase analog quantity meets the secondary protection condition, the control unit performs the secondary protection action, increases the alarm level and reduces the output limit, and then determines whether the duration of the secondary protection exceeds the limit. S6. When the duration of the secondary protection exceeds the limit, the control unit determines whether the three-phase analog quantity meets the conditions for the tertiary protection. S7. When the three-phase analog quantity meets the three-level protection conditions, the control unit performs the three-level protection action, latches the fault flag, saves the fault type and fault time, and alarms after reporting the fault, and then judges in real time whether the three-phase analog quantity meets the fault recovery conditions. S8. In response to the converter reset after the three-phase analog quantity meets the fault recovery condition, the control unit returns to step S1.

[0012] Optionally, after step S2, the multi-level protection process further includes at least: When the three-phase analog quantity does not meet the first-level early warning condition, the control unit maintains the current three-phase drive signal operation and then returns to step S1. After step S3, the multi-level protection process shall at least include: When the duration of the first-level warning does not exceed the limit, the control unit maintains the current operation of the three-phase drive signal and then returns to step S1. After step S4, the multi-level protection process further includes at least: When the three-phase analog quantity does not meet the secondary protection conditions, the control unit returns to step S3, executes the first-level early warning action, marks the early warning flag and uploads the alarm to the host computer, and then determines whether the duration of the first-level early warning exceeds the limit. After step S5, the multi-level protection process further includes at least: When the duration of the secondary protection does not exceed the limit, the control unit executes the secondary protection action, increases the alarm level and reduces the output limit, thereby determining whether the duration of the secondary protection exceeds the limit. After step S6, the multi-level protection process further includes at least: When the three-phase analog quantity does not meet the three-level protection conditions, the control unit performs a two-level protection action, increases the alarm level and reduces the output upper limit, and then determines whether the duration of the two-level protection exceeds the limit.

[0013] Based on the same concept, in a second aspect, the present invention also provides a vehicle that integrates at least the on-board bidirectional DC-DC converter described in any one of the first aspects.

[0014] The vehicle-mounted bidirectional DC-DC converter provided by this invention includes at least a power conversion unit and a control unit. The power conversion unit adopts at least a three-phase interleaved parallel topology, with the three-phase drive phases sequentially staggered by a preset phase angle. The control unit is connected to the power conversion unit and is used at least to output three-phase drive signals according to the battery load to control the switching devices in the power conversion unit to turn on or off. Therefore, this invention can at least solve the problem of inaccurate battery charging and discharging control caused by the fixed bidirectional energy logic in existing bidirectional DC-DC converters, and can control the on / off of the power conversion switching devices according to the battery load, thus improving the accuracy of battery charging and discharging control. Attached Figure Description

[0015] Figure 1This is a schematic diagram of the structure of an on-board bidirectional DC-DC converter provided in an embodiment of the present invention; Figure 2 This is a schematic diagram of the structure of a power conversion unit provided in an embodiment of the present invention; Figure 3 This is a schematic diagram of another vehicle-mounted bidirectional DC-DC converter provided in an embodiment of the present invention; Figure 4 This is a schematic diagram of a multi-level protection process provided by an embodiment of the present invention. Detailed Implementation

[0016] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0017] It should be noted that any symbols and / or numbers present in the specification that are not marked in the accompanying drawings are not reference numerals.

[0018] Figure 1 This is a schematic diagram of a vehicle-mounted bidirectional DC-DC converter provided in an embodiment of the present invention. This embodiment is applicable to control optimization scenarios for vehicle-mounted bidirectional DC-DC converters in at least any vehicle equipped with a bidirectional DC-DC converter. The vehicle-mounted bidirectional DC-DC converter can be implemented using software and / or hardware. Figure 1 As shown, the on-board bidirectional DC-DC converter includes at least: The power conversion unit adopts at least a three-phase interleaved parallel topology, with the three-phase drive phases staggered by a preset phase angle in sequence; The control unit, connected to the power conversion unit, is used at least to output a three-phase drive signal according to the battery load to control the switching devices in the power conversion unit to turn on or off.

[0019] The power conversion unit can be composed of multiple electronic devices, with the A / B / C phases being completely symmetrical. For example, the preset phase angle can be, for instance, 120°.

[0020] Figure 2 This is a schematic diagram of the structure of a power conversion unit provided in an embodiment of the present invention. See also: Figure 2In one specific embodiment, optionally, the power conversion unit includes at least a first switching device D1, a second switching device D2, a third switching device D3, a fourth switching device D4, a fifth switching device D5, a sixth switching device D6, a seventh switching device D7, an eighth switching device D8, a ninth switching device D9, a tenth switching device D10, a first capacitor C1, a second capacitor C2, a third capacitor C3, a fourth capacitor C4, a fifth capacitor C5, a sixth capacitor C6, a seventh capacitor C7, a first inductor L1, a second inductor L2, a third inductor L3, a first resistor R1, a second resistor R2, and a third resistor R3; The first terminal of the first switching device D1 serves as the input terminal of the power conversion unit, and the second terminal of the first switching device D1 is connected to the first terminal of the second switching device D2. The second terminal of the second switching device D2 is connected to the first terminal of the third switching device D3; The second terminal of the third switching device D3 is connected to the first terminal of the first inductor L1; The second terminal of the first inductor L1 is connected to the first terminal of the first resistor R1; The second terminal of the first resistor R1 is connected to the first terminal of the ninth switching device D9; The second terminal of the ninth switching device D9 is connected to the first terminal of the tenth switching device D10; The second terminal of the tenth switching device D10 serves as the output terminal of the power conversion unit. The first terminal of the first capacitor C1 is connected to the second terminal of the second switching device D2, and the second terminal of the first capacitor C1 is connected to the first terminal of the second capacitor C2. The second terminal of the second capacitor C2 is connected to the first terminal of the third capacitor C3; The second terminal of the third capacitor C3 is grounded; The first terminal of the fourth switching device D4 is connected to the second terminal of the third switching device D3, and the second terminal of the fourth switching device D4 is connected to the second terminal of the first capacitor C1. The first terminal of the sixth capacitor C6 is connected to the second terminal of the first resistor R1, and the second terminal of the sixth capacitor C6 is connected to the second terminal of the fourth switching device D4 and grounded. The first terminal of the seventh capacitor C7 is connected to the second terminal of the tenth switching device D10, and the second terminal of the seventh capacitor C7 is grounded. The first terminal of the fifth switching device D5 is connected to the first terminal of the second capacitor C2, and the second terminal of the fifth switching device D5 is connected to the first terminal of the second inductor L2. The second terminal of the second inductor L2 is connected to the first terminal of the second resistor R2; The second terminal of the second resistor R2 is connected to the first terminal of the sixth capacitor C6; The first terminal of the sixth switching device D6 is connected to the second terminal of the fifth switching device D5, and the second terminal of the sixth switching device D6 is connected to the second terminal of the second capacitor C2. The first terminal of the fifth capacitor C5 is connected to the second terminal of the second resistor R2, and the second terminal of the fifth capacitor C5 is connected to the second terminal of the sixth switching device D6 and grounded. The first terminal of the seventh switching device D7 is connected to the first terminal of the third capacitor C3, and the second terminal of the seventh switching device D7 is connected to the first terminal of the third inductor L3. The second terminal of the third inductor L3 is connected to the first terminal of the third resistor R3; The second terminal of the third resistor R3 is connected to the second terminal of the second resistor R2; The first terminal of the eighth switching device D8 is connected to the second terminal of the seventh switching device D7, and the second terminal of the eighth switching device D8 is connected to the second terminal of the third capacitor C3. The first terminal of the fourth capacitor C4 is connected to the second terminal of the third resistor R3, and the second terminal of the fourth capacitor C4 is connected to the second terminal of the eighth switching device D8.

[0021] It is understood that the selection and parameters of the above electronic components can be configured according to the actual adaptability of automotive applications, and this invention does not limit them. For example, the inductor can be a high-frequency iron-silicon-aluminum magnetic ring inductor with a single inductance value of 2.2μH, etc.

[0022] In another specific implementation, the power conversion unit may optionally include at least a boost mode (e.g., 12V→48V, cold start 12V battery feeds back to 48V, lower bridge conduction, upper bridge freewheeling, three-phase interleaved boost). When the power conversion unit is in boost mode, the first, second, ninth, and tenth switching devices are continuously turned on (at this time, the first, second, ninth, and tenth switching devices are common bus switches), the fourth, sixth, and eighth switching devices are interleaved (at this time, the fourth, sixth, and eighth switching devices are low-voltage side switches), and the third, fifth, and seventh switching devices are synchronously complementary rectifiers (at this time, the third, fifth, and seventh switching devices are high-voltage side switches, and are complementary PWM controls with the corresponding low-voltage side switches).

[0023] In another specific implementation, the power conversion unit may optionally include at least a buck mode (e.g., 48V→12V, BSG power generation / 48V power supply, upper bridge conduction, lower bridge freewheeling, three-phase interleaved buck). When the power conversion unit is in buck mode, the first, second, ninth, and tenth switching devices are continuously turned on (at this time, the first, second, ninth, and tenth switching devices are common bus switches). The third, fifth, and seventh switching devices are interleaved in conduction (at this time, the third, fifth, and seventh switching devices are high-voltage side switches). The fourth, sixth, and eighth switching devices are synchronously complementary rectifiers (at this time, the fourth, sixth, and eighth switching devices are low-voltage side switches, which are complementary PWM controls with the corresponding high-voltage side switches).

[0024] In yet another specific implementation, the three-phase drive signal may optionally be output in at least the following manner: When the battery load is within the first load range, the three-phase drive signal adopts Burst intermittent modulation and reduces the switching frequency to the preset frequency range. When the battery load is in the second load range, the three-phase drive signal adopts interleaved PWM at a set frequency, soft switching operation, and full-phase soft switching is achieved at least based on the resonance of the topology inductance and the switching junction capacitance. When the battery load is in the third load range, the three-phase drive signal adopts the phase shift control of ZVS zero voltage turn-on, and the zero voltage turn-on range is widened by the phase shift of the bridge arm.

[0025] More specifically, the control unit can use an automotive-grade 32-bit MCU with built-in ADC, PWM, and CAN peripherals; the MCU can also incorporate a three-stage control algorithm. (1) Load <360W (or 30% of rated value): Burst intermittent modulation, switching frequency reduced to 50kHz ~100kHz (i.e. the aforementioned preset frequency range) to reduce light load drive loss; (2) 360W~900W: 320kHz (i.e. the aforementioned set frequency) fixed interleaved PWM, soft switching operation, relying on the resonance of topology inductance and switching junction capacitance to achieve full-phase soft switching, simple control logic, optimal ripple, suitable for medium load stable working conditions; (3) Load > 900W: Phase shift control to achieve ZVS zero voltage turn-on. By actively widening the zero voltage turn-on range through bridge arm phase shift, the problem of increased current and narrowing of natural soft switching range under heavy load is solved, and the heavy load switching loss is reduced to the extreme.

[0026] In the actual development of vehicles, the inventors also discovered that, apart from the problem of fixed bidirectional energy logic, the currently mass-produced 48V / 12V bidirectional DC-DC converters on the market still have at least the following problems: 1. Low conversion efficiency: The efficiency is 91%~93% across the full load range, but drops to below 85% under light load (e.g., <10% of rated power), resulting in significant energy recovery losses during vehicle coasting and limited fuel consumption optimization. 2. Low power density: Silicon devices have a switching frequency of ≤150kHz, resulting in large inductors and capacitors, and an overall volume of ≥1.8L, which makes engine compartment layout difficult and is not conducive to vehicle lightweighting. 3. Poor wide temperature adaptability: The internal resistance spikes and the load-carrying capacity decreases when starting at -40℃. The 12V instantaneous large load (starter, electric brake) transiently drops by more than 1V, which can easily cause the instrument panel to go black and the ECU to lose power. 4. Limited protection: Only hardware overcurrent / overvoltage protection is provided, lacking hardware and software graded redundancy protection. Power devices are easily damaged by 48V side peak voltage and reverse battery connection, resulting in a high failure rate.

[0027] In view of this, Figure 3 This is a schematic diagram of another vehicle-mounted bidirectional DC-DC converter provided in an embodiment of the present invention. See also... Figure 3 The switching devices can be automotive-grade GaN FETs (e.g., withstand voltage of 100V), and multiple switching devices can be combined to form a GaN power bridge.

[0028] In yet another specific implementation, it may optionally include at least an input filtering unit and an output filtering unit; The input filtering unit (which can be composed of a common-mode inductor and X / Y safety capacitors forming an LC filter, with X capacitors being, for example, 2×2.2μF and Y capacitors being, for example, 2×1nF, to suppress high-frequency spikes and common-mode interference on the 48V battery side) is connected to the input terminal of the power conversion unit and is used to filter the input preset level voltage (for example, 48V) to obtain the converted input voltage to be input to the power conversion unit (i.e., the voltage input to the power conversion unit). The output filtering unit (e.g., a combination of film capacitors and electrolytic capacitors can be used for filtering to reduce output ripple, with ripple ≤ 50mVpp) is connected to the output terminal of the power conversion unit and is used at least to filter the voltage output by the power conversion unit to obtain a converted output voltage (i.e., the voltage output by the power conversion unit) of a set voltage level (e.g., 12V).

[0029] In yet another specific implementation, it may optionally include at least an electrical signal sampling unit, a temperature sampling feedback unit, a graded protection unit, and a vehicle communication unit. The control unit establishes connections with the electrical signal sampling unit, temperature sampling feedback unit, graded protection unit, and vehicle communication unit, respectively. The electrical signal sampling unit is used to acquire at least the input voltage, bus voltage, output voltage, inductor current, input current, and output current of the transformer. The temperature sampling feedback unit is used to collect at least the temperatures of the switching devices and inductors in the power conversion unit; The graded protection unit includes at least a fast-blow fuse (e.g., 30A) connected in series at the input of the power conversion unit, a TVS transient suppression diode (e.g., a 100V / 40V automotive-grade TVS transient suppression diode connected in parallel on the high and low voltage sides), and a reverse current suppression diode added inside the converter to isolate the power circuit from the reverse connection of the battery (in addition to the hardware level, it may also include the software level, such as the MCU collecting the input voltage, output current, and three NTC temperatures every 10μs—power transistor, inductor, and PCB substrate; overcurrent of 1.25 times the rated current—current limiting; 1.5 times—power reduction of 50%; 2 times—latch shutdown). The vehicle communication unit must at least interface with the vehicle's CAN bus to upload DC-DC status, temperature, and power parameters in real time, and receive VCU power commands.

[0030] For example, three NTC surface mount thermistors are mounted on the surface of power devices, inductors, etc., with a temperature measurement range of -55℃ to +150℃.

[0031] In yet another specific implementation, the control unit is optionally also configured to perform a multi-level protection process based at least on the three-phase analog quantities; Three-phase analog quantities include at least the input voltage, bus voltage, output voltage, inductor current, input current, output current, switching device temperature, and inductor temperature.

[0032] Figure 4 This is a schematic diagram of a multi-level protection process provided by an embodiment of the present invention. See also... Figure 4 A multi-level protection process includes at least the following steps: S1. In response to the power-on of the vehicle system, the control unit starts the cycle timer interrupt and synchronously acquires three-phase analog signals; S2. After the control unit performs sampling filtering on the three-phase analog quantities (for example, AD sampling filtering and mean filtering to remove glitches), it reads the preset threshold table to determine at least the first-level warning threshold parameter group, the second-level protection threshold parameter group and the third-level protection threshold parameter group, and then determines whether the three-phase analog quantities meet the first-level warning conditions. S3. When the three-phase analog quantity meets the first-level warning condition, the control unit executes the first-level warning action (such as hardware current limiting, limiting maximum output), marks the warning flag bit and uploads the alarm to the host computer, and then determines whether the duration of the first-level warning exceeds the limit (such as determining whether the duration of the first-level warning is longer than the first-level warning duration threshold). S4. When the duration of the first-level warning exceeds the limit, the control unit determines whether the three-phase analog quantity meets the conditions for the second-level protection. S5. When the three-phase analog quantity meets the secondary protection conditions, the control unit executes the secondary protection action (e.g., reducing the PWM duty cycle and reducing the output), increases the alarm level and reduces the output limit (e.g., 50%~70%), and then determines whether the duration of the secondary protection exceeds the limit. S6. When the duration of the secondary protection exceeds the limit, the control unit determines whether the three-phase analog quantity meets the conditions for the tertiary protection. S7. When the three-phase analog quantity meets the three-level protection conditions, the control unit executes the three-level protection action (e.g., blocking the PWM output), latches the fault flag, saves the fault type and fault time, and alarms after reporting the fault, thereby judging in real time whether the three-phase analog quantity meets the fault recovery conditions. S8. In response to the converter reset (e.g., manual reset or automatic reset) after the three-phase analog quantities meet the fault recovery conditions (e.g., all parameters fall back to the safe range, the fault continuous cooling delay is completed), the control unit returns to step S1 (of course, if the fault is still not eliminated, the control unit returns to step S7 and executes the three-level protection action).

[0033] In yet another specific implementation, optionally, after step S2, the multi-level protection process further includes at least: When the three-phase analog signal does not meet the first-level warning condition, the control unit maintains the current three-phase drive signal operation (e.g., full power operation) and then returns to step S1. Following step S3, the multi-level protection process shall at least include: When the duration of the Level 1 warning does not exceed the limit, the control unit maintains the current three-phase drive signal operation and then returns to step S1. Following step S4, the multi-level protection process includes at least the following: When the three-phase analog quantity does not meet the secondary protection conditions, the control unit returns to step S3, executes the first-level warning action, marks the warning flag and uploads the alarm to the host computer, and then determines whether the duration of the first-level warning exceeds the limit. Following step S5, the multi-level protection process shall include at least the following: When the duration of the secondary protection does not exceed the limit, the control unit executes the secondary protection action, increases the alarm level and reduces the output limit, and then determines whether the duration of the secondary protection exceeds the limit. Following step S6, the multi-level protection process includes at least the following: When the three-phase analog quantity does not meet the conditions for level three protection, the control unit executes level two protection action, increases the alarm level and reduces the output upper limit, and then determines whether the duration of level two protection exceeds the limit.

[0034] It is understood that the aforementioned threshold parameter groups may include corresponding input voltage threshold, bus voltage threshold, output voltage threshold, inductor current threshold, input current threshold, output current threshold, switching device temperature threshold, inductor temperature threshold, and primary warning duration threshold or secondary protection duration.

[0035] Adaptively, for a three-phase analog quantity to meet the Level 1 warning condition, it can mean that the input voltage, bus voltage, output voltage, inductor current, input current, output current, switching device temperature, and / or inductor temperature are not less than the corresponding Level 1 warning parameter threshold. For example, the inductor current may be greater than the Level 1 warning inductor current threshold, or the input voltage may be equal to the Level 1 warning input voltage threshold. It is understood that meeting the Level 2 and Level 3 protection conditions for three-phase analog quantities is similar to the above situations and will not be elaborated further.

[0036] The vehicle-mounted bidirectional DC-DC converter provided by this invention includes at least a power conversion unit and a control unit. The power conversion unit adopts at least a three-phase interleaved parallel topology, with the three-phase drive phases sequentially staggered by a preset phase angle. The control unit is connected to the power conversion unit and is used at least to output three-phase drive signals according to the battery load to control the switching devices in the power conversion unit to turn on or off. Therefore, this invention can at least solve the problem of inaccurate battery charging and discharging control caused by the fixed bidirectional energy logic in existing bidirectional DC-DC converters, and can control the on / off of the power conversion switching devices according to the battery load, thus improving the accuracy of battery charging and discharging control.

[0037] It should be noted that, compared with the prior art, the present invention includes at least the following technical improvements: Improvement 1 (Power Stage): "Three-phase interleaved parallel topology + gallium nitride (GaN) switches", each phase consists of a bidirectional half-bridge composed of upper and lower bridge GaNFETs, replacing the traditional silicon MOS two-phase topology, and the switching frequency can be increased to 320kHz. Improvement Point 2 (Control Algorithm): MCU segmented adaptive PWM control, with three control logic segments based on load power: Light load <30% of rated load: frequency-reduced Burst intermittent modulation; Medium load 30%~75% of rated load: fixed 320kHz interleaved PWM; Heavy load >75% of rated load: phase-shift soft-switching control, soft-start across the entire range to reduce switching losses; Improvement Point 3 (Protection): Two-level redundant protection of hardware and software: Hardware level: transient TVS + power circuit fast fuse; Software level: MCU real-time acquisition of voltage / current / temperature, over-threshold graded current limiting → power reduction → shutdown; added 48V / 12V bidirectional reverse connection protection circuit. Improvement Point 4 (Temperature Control Linkage): NTC multi-point temperature measurement + temperature closed-loop compensation, automatic increase of drive voltage to compensate for device internal resistance in low temperature range, active derating output in high temperature range, and widening of operating temperature range.

[0038] Based on this, the present invention can achieve: 1. Efficiency Improvement: Full load range conversion efficiency of 95%~96.8%, light load efficiency ≥92%, coasting energy recovery rate improved by 5%~7%, optimizing overall vehicle fuel consumption; 2. Miniaturization: High-frequency GaN reduces the size of magnetic components and capacitors, resulting in an overall volume of ≤0.7L and a power density of 3.42kW / L, saving space in the engine compartment. 3. Wide temperature range and reliable: Full power start-up at -40℃, no derating at +125℃, and voltage drop of less than 0.3V under sudden load of 6 times peak value on the 12V side, eliminating power loss of vehicle electrical components; 4. Enhanced safety: Hierarchical redundancy protection protects against reverse connection, overvoltage and overcurrent, and high-temperature damage, reducing device failure rate by 60%; 5. Vehicle compatibility: CAN communication interface with BCM / VCU, which can dynamically adjust the charging and discharging power according to the 48V battery SOC to optimize the life of 48V lithium batteries.

[0039] Through actual testing by the inventors, the technical solution provided by this invention can overcome the shortcomings of existing 48V / 12V bidirectional DC-DC converters, such as low efficiency, large size, poor low-temperature performance, and weak transient shock resistance. It provides a vehicle-mounted bidirectional DC-DC converter with "GaN gallium nitride + three-phase interleaved parallel + segmented digital control + hierarchical redundancy protection", with an efficiency of ≥95% under all operating conditions, a power density of ≥3.3kW / L, and meets the automotive-grade environmental requirements of -40℃ to +125℃.

[0040] The present invention also provides a vehicle that integrates at least the on-board bidirectional DC-DC converter described in any of the foregoing embodiments or implementations.

[0041] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A vehicle-mounted bidirectional DC-DC converter, characterized in that, At least including: The power conversion unit adopts at least a three-phase interleaved parallel topology, with the three-phase drive phases staggered by a preset phase angle in sequence; The control unit, connected to the power conversion unit, is at least used to output a three-phase drive signal according to the battery load to control the switching devices in the power conversion unit to turn on or off.

2. The on-board bidirectional DC-DC converter according to claim 1, characterized in that, The power conversion unit includes at least a first switching device, a second switching device, a third switching device, a fourth switching device, a fifth switching device, a sixth switching device, a seventh switching device, an eighth switching device, a ninth switching device, a tenth switching device, a first capacitor, a second capacitor, a third capacitor, a fourth capacitor, a fifth capacitor, a sixth capacitor, a seventh capacitor, a first inductor, a second inductor, a third inductor, a first resistor, a second resistor, and a third resistor; The first terminal of the first switching device serves as the input terminal of the power conversion unit, and the second terminal of the first switching device is connected to the first terminal of the second switching device. The second terminal of the second switching device is connected to the first terminal of the third switching device; The second terminal of the third switching device is connected to the first terminal of the first inductor; The second end of the first inductor is connected to the first end of the first resistor; The second end of the first resistor is connected to the first end of the ninth switching device; The second terminal of the ninth switching device is connected to the first terminal of the tenth switching device; The second terminal of the tenth switching device serves as the output terminal of the power conversion unit. The first terminal of the first capacitor is connected to the second terminal of the second switching device, and the second terminal of the first capacitor is connected to the first terminal of the second capacitor. The second terminal of the second capacitor is connected to the first terminal of the third capacitor; The second terminal of the third capacitor is grounded; The first terminal of the fourth switching device is connected to the second terminal of the third switching device, and the second terminal of the fourth switching device is connected to the second terminal of the first capacitor. The first terminal of the sixth capacitor is connected to the second terminal of the first resistor, and the second terminal of the sixth capacitor is connected to the second terminal of the fourth switching device and grounded. The first terminal of the seventh capacitor is connected to the second terminal of the tenth switching device, and the second terminal of the seventh capacitor is grounded. The first terminal of the fifth switching device is connected to the first terminal of the second capacitor, and the second terminal of the fifth switching device is connected to the first terminal of the second inductor; The second terminal of the second inductor is connected to the first terminal of the second resistor; The second terminal of the second resistor is connected to the first terminal of the sixth capacitor; The first terminal of the sixth switching device is connected to the second terminal of the fifth switching device, and the second terminal of the sixth switching device is connected to the second terminal of the second capacitor; The first terminal of the fifth capacitor is connected to the second terminal of the second resistor, and the second terminal of the fifth capacitor is connected to the second terminal of the sixth switching device and grounded. The first terminal of the seventh switching device is connected to the first terminal of the third capacitor, and the second terminal of the seventh switching device is connected to the first terminal of the third inductor; The second terminal of the third inductor is connected to the first terminal of the third resistor; The second end of the third resistor is connected to the second end of the second resistor; The first terminal of the eighth switching device is connected to the second terminal of the seventh switching device, and the second terminal of the eighth switching device is connected to the second terminal of the third capacitor; The first terminal of the fourth capacitor is connected to the second terminal of the third resistor, and the second terminal of the fourth capacitor is connected to the second terminal of the eighth switching device.

3. The on-board bidirectional DC-DC converter according to claim 2, characterized in that, The power conversion unit includes at least a boost mode; When the power conversion unit is in the boost mode, the first, second, ninth, and tenth switching devices are continuously turned on, the fourth, sixth, and eighth switching devices are turned on in an alternating manner, and the third, fifth, and seventh switching devices are synchronously complementary in rectification.

4. The vehicle-mounted bidirectional DC-DC converter according to claim 2, characterized in that, The power conversion unit includes at least a buck mode; When the power conversion unit is in the buck mode, the first switching device, the second switching device, the ninth switching device, and the tenth switching device are continuously turned on; The third, fifth, and seventh switching devices are interleaved in conduction. The fourth, sixth, and eighth switching devices perform synchronous complementary rectification.

5. The on-board bidirectional DC-DC converter according to claim 1, characterized in that, The three-phase drive signal is output in at least the following ways: When the battery load is within the first load range, the three-phase drive signal is subjected to Burst intermittent modulation, and the switching frequency is reduced to a preset frequency range. When the battery load is within the second load range, the three-phase drive signal adopts interleaved PWM at a set frequency, operates in soft-switching mode, and achieves full-phase soft switching based at least on the resonance of the topological inductance and the switching junction capacitance. When the battery load is in the third load range, the three-phase drive signal adopts ZVS zero-voltage turn-on phase shift control, and the zero-voltage turn-on range is widened by bridge arm phase shift.

6. The vehicle-mounted bidirectional DC-DC converter according to claim 1, characterized in that, It should also include at least an input filtering unit and an output filtering unit; The input filtering unit is connected to the input terminal of the power conversion unit and is used at least to filter the input preset level voltage to obtain the converted input voltage to be input to the power conversion unit. The output filtering unit is connected to the output terminal of the power conversion unit and is used at least to filter the voltage output by the power conversion unit to obtain a converted output voltage of a set voltage level.

7. The on-board bidirectional DC-DC converter according to claim 1, characterized in that, It also includes at least an electrical signal sampling unit, a temperature sampling feedback unit, a graded protection unit, and a vehicle communication unit; The control unit establishes connections with the electrical signal sampling unit, the temperature sampling feedback unit, the graded protection unit, and the vehicle communication unit, respectively. The electrical signal sampling unit is used to collect at least the transformation input voltage, bus voltage, transformation output voltage, inductor current, transformation input current, and transformation output current; The temperature sampling feedback unit is used at least to collect the temperature of the switching devices and the inductor in the power conversion unit; The graded protection unit includes at least a fast-blow fuse connected in series at the input terminal of the power conversion unit, a TVS transient suppression tube connected in parallel on the high and low voltage sides, and a reverse anti-current diode added in the converter to isolate the power circuit from the battery. The vehicle communication unit is at least connected to the vehicle's CAN bus to upload DC-DC status, temperature, and power parameters in real time, and to receive VCU power commands.

8. The on-board bidirectional DC-DC converter according to claim 7, characterized in that, The control unit is also used to execute multi-level protection procedures based on at least three-phase analog quantities; The three-phase analog quantities include at least the transformation input voltage, the bus voltage, the transformation output voltage, the inductor current, the transformation input current, the transformation output current, the switching device temperature, and the inductor temperature; The multi-level protection process includes at least the following steps: S1. In response to the power-on of the vehicle system, the control unit starts the cycle timer interrupt and synchronously acquires the three-phase analog quantity; S2. After the control unit performs sampling filtering on the three-phase analog quantity, it reads the preset threshold table to determine at least the first-level warning threshold parameter group, the second-level protection threshold parameter group and the third-level protection threshold parameter group, and then determines whether the three-phase analog quantity meets the first-level warning condition. S3. When the three-phase analog quantity meets the first-level early warning condition, the control unit performs the first-level early warning action, marks the early warning flag and uploads the alarm to the host computer, and then determines whether the duration of the first-level early warning exceeds the limit. S4. When the duration of the first-level warning exceeds the limit, the control unit determines whether the three-phase analog quantity meets the second-level protection conditions. S5. When the three-phase analog quantity meets the secondary protection condition, the control unit performs the secondary protection action, increases the alarm level and reduces the output limit, and then determines whether the duration of the secondary protection exceeds the limit. S6. When the duration of the secondary protection exceeds the limit, the control unit determines whether the three-phase analog quantity meets the conditions for the tertiary protection. S7. When the three-phase analog quantity meets the three-level protection conditions, the control unit performs the three-level protection action, latches the fault flag, saves the fault type and fault time, and alarms after reporting the fault, and then judges in real time whether the three-phase analog quantity meets the fault recovery conditions. S8. In response to the converter reset after the three-phase analog quantity meets the fault recovery condition, the control unit returns to step S1.

9. The on-board bidirectional DC-DC converter according to claim 8, characterized in that, After step S2, the multi-level protection process shall at least include: When the three-phase analog quantity does not meet the first-level early warning condition, the control unit maintains the current three-phase drive signal operation and then returns to step S1. After step S3, the multi-level protection process shall at least include: When the duration of the first-level warning does not exceed the limit, the control unit maintains the current operation of the three-phase drive signal and then returns to step S1. After step S4, the multi-level protection process further includes at least: When the three-phase analog quantity does not meet the secondary protection conditions, the control unit returns to step S3, executes the first-level early warning action, marks the early warning flag and uploads the alarm to the host computer, and then determines whether the duration of the first-level early warning exceeds the limit. After step S5, the multi-level protection process further includes at least: When the duration of the secondary protection does not exceed the limit, the control unit executes the secondary protection action, increases the alarm level and reduces the output limit, thereby determining whether the duration of the secondary protection exceeds the limit. After step S6, the multi-level protection process further includes at least: When the three-phase analog quantity does not meet the three-level protection conditions, the control unit performs a two-level protection action, increases the alarm level and reduces the output upper limit, and then determines whether the duration of the two-level protection exceeds the limit.

10. A vehicle, characterized in that, It integrates at least the vehicle-mounted bidirectional DC-DC converter as described in any one of claims 1-9.

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