Vehicle-mounted backup power supply system, power supply control method, controller, and vehicle

Abstract

The application provides a vehicle-mounted backup power supply system, a power supply control method, a vehicle-mounted controller and a vehicle, and can solve the problems of reducing power-on surge, isolating energy storage failure, realizing online diagnosis without interfering with the main system, improving the utilization efficiency of backup energy, and the like. A primary low-voltage conversion unit is connected with a power input end, an input voltage is converted into a low-voltage power supply, a high-voltage boosting unit is connected with the power input end, a medium-voltage step-down unit is connected with a high-voltage bus, a first input end of a power supply switching unit is connected with the power input end, a second input end is connected with a medium-voltage bus, and the power supply switching unit is used for switching the power supply source from the power input end to the medium-voltage bus after the voltage of the medium-voltage bus is established; an energy storage module comprises a charging switch tube and an energy storage capacitor, and a control unit. When the power input end is powered off to cause the voltage of the high-voltage bus to drop, the energy storage capacitor reversely feeds power to the high-voltage bus through the charging switch tube to maintain the voltage of the high-voltage bus.

Description

Technical Field

[0001] This invention relates to the field of automotive electronic power management technology, specifically to an on-board backup power system, a power supply control method, an on-board controller, and a vehicle. Background Technology

[0002] In vehicle safety systems, to prevent the 12V battery from being depleted or detached due to a severe collision, which could lead to system failure, using large-capacity energy storage capacitors or supercapacitors as backup power is a well-known and widely adopted technical approach in the industry.

[0003] Typical implementation schemes for on-board backup power supplies in existing technologies include the following categories: The first type is the direct connection of the energy storage capacitor to the bus. This method connects a large-capacity energy storage capacitor directly in parallel to the system's main power bus, such as the 12V VBAT terminal or the high-voltage terminal after boosting. Since the large capacitor is approximately short-circuited at power-on, it generates a very large inrush current, severely impacting system power-on. To mitigate this problem, some solutions incorporate a simple current-limiting resistor or PTC resistor in series in the charging circuit to limit the inrush current to an acceptable range.

[0004] The second type is the low-voltage side single-circuit backup power solution. This solution only connects the energy storage capacitor to the low-voltage digital circuit side, such as 5V or 3.3V, to ensure that the MCU can be maintained briefly when the power is lost. Although the energy storage capacitor has a low voltage level and relatively low cost, the backup energy can only cover the low-voltage digital load and cannot provide power loss support for high-voltage, high-current loads such as airbag ignition drive, which severely limits its application scope.

[0005] The third type is a backup power solution with conventional diagnostic functions. This solution monitors the voltage across the capacitor through the MCU's ADC (analog-to-digital converter) sampling port to determine whether the capacitor is open-circuited or has an abnormal voltage. However, due to the topology where the capacitor is directly connected to the bus, the diagnostic function is mostly executed only once at the moment of system startup, making it difficult to perform periodic online testing during vehicle operation.

[0006] The aforementioned prior art has at least the following drawbacks: The risk of power-on surge impact has not been completely eliminated: Although some solutions have added current limiting devices, the energy storage capacitor is still electrically connected to the main circuit at the moment of system power-on. During cold start or when the battery voltage is unstable, the huge surge current can easily cause the front fuse to blow, the MOSFET to be damaged by overcurrent or the power management chip to fail to start soft, resulting in the entire controller being unable to power on normally. The energy storage components are not isolated from the main power circuit, which poses a risk of single-point failure: In the existing scheme, most energy storage capacitors are directly connected in parallel to important power buses. Once the capacitor body is short-circuited and breaks down or the lead solder collapses, the voltage of the bus will be instantly pulled down to zero, causing the entire power network to fail. Online diagnostics and normal system operation interfere with each other: Due to the topology of capacitors being directly connected to the bus, existing technologies must inject disturbance signals into the bus or cut off the main circuit current to detect capacitor capacity decay. This will interfere with the normal operation of the system. Therefore, most existing solutions only perform a simple voltage test at the moment of system startup and cannot achieve periodic self-testing during vehicle operation.

[0007] The energy architecture is simple and the power loss maintenance efficiency is low: the low-voltage backup power solution requires additional voltage boost when driving high-voltage ignition loads, resulting in large energy conversion losses; while the solution connected to the high-voltage side lacks the ability to hierarchically allocate power to the downstream medium and low voltage analog circuits, and cannot achieve both high efficiency and high quality power supply. Summary of the Invention

[0008] To address the aforementioned problems, this invention provides an on-board backup power system, a power supply control method, an on-board controller, and a vehicle, which can reduce power-on surges, isolate energy storage faults, enable online diagnostics without interfering with the main system, and improve the utilization efficiency of backup energy.

[0009] The technical solution is as follows: an on-board backup power system, comprising: A primary low-voltage conversion unit, the input terminal of which is connected to the power input terminal, is capable of converting the input voltage provided by the power input terminal into a low-voltage power supply, which is used to power the subsequent load. A high-voltage boost unit, the input terminal of which is connected to the power input terminal, is started after the primary low-voltage conversion unit establishes a low-voltage power supply, and boosts the input voltage before outputting it to the high-voltage bus. A medium-voltage step-down unit, the input terminal of which is connected to the high-voltage bus, is used to start after the voltage of the high-voltage bus is established, and to step down the voltage input from the high-voltage bus and output it to the medium-voltage bus; A power supply switching unit, wherein the first input terminal of the power supply switching unit is connected to the power input terminal and the second input terminal of the power supply switching unit is connected to the medium voltage bus, is used to switch the power supply source of the downstream load from the power input terminal to the medium voltage bus after the voltage of the medium voltage bus is established; An energy storage module includes: a charging switch transistor connected between the high-voltage bus and the energy storage port, wherein the conduction direction of the body diode of the charging switch transistor is from the energy storage port to the high-voltage bus; and an energy storage capacitor connected to the energy storage port. The control unit is used to control the charging switch tube to turn on after the power supply switching unit completes the switching, so that the high voltage bus can charge the energy storage capacitor. When the power input terminal loses power, causing the voltage of the high-voltage bus to drop, and the body diode of the charging switch transistor to conduct, the energy storage capacitor feeds back to the high-voltage bus through the charging switch transistor to maintain the voltage of the high-voltage bus.

[0010] Furthermore, the primary low-voltage conversion unit is provided with a low-voltage conversion status signal output terminal, which is connected to the enable terminal of the high-voltage boost unit. After the low-voltage power supply stabilizes, the primary low-voltage conversion unit outputs a first power good signal from the low-voltage conversion status signal output terminal to enable the high-voltage boost unit to start. The high-voltage boost unit is provided with a high-voltage boost status signal output terminal, which is connected to the enable terminal of the medium-voltage buck unit. After the voltage of the high-voltage bus stabilizes, the high-voltage boost unit outputs a second power good signal from the high-voltage boost status signal output terminal to enable the medium-voltage buck unit to start. The medium-voltage step-down unit is equipped with a medium-voltage step-down status signal output terminal. After the voltage of the medium-voltage bus is established and reaches the threshold, it outputs a third power supply good signal. The third power supply good signal serves as the switching judgment condition for the power supply switching unit.

[0011] Furthermore, it also includes a reset determination unit; the multiple input terminals of the reset determination unit respectively receive the first power good signal, the second power good signal and the third power good signal, and the output terminal of the reset determination unit is connected to the reset terminal of the control unit, and is used to output a power ready signal when all power good signals are valid, thereby releasing the reset state of the control unit.

[0012] Furthermore, the power supply switching unit includes a first switching transistor, a second switching transistor, and a third switching transistor; The first and second switching transistors are disposed between the power input terminal and the input terminal of the primary low-voltage conversion unit. The drain of the first switching transistor is connected to the drain of the second switching transistor, and the source of the first switching transistor is connected to the power input terminal. The source of the second switching transistor is connected to the source of the third switching transistor, and the drain of the third switching transistor is connected to the medium-voltage bus. The gates of the first and second switching transistors are connected and connected to the medium-voltage buck state signal output terminal of the medium-voltage buck unit. The gate of the third switching transistor is connected to an inverter and then connected to the gates of both the first and second switching transistors. When the third power supply good signal output from the medium-voltage step-down status signal output terminal is invalid, the first switch and the second switch are turned on, and the third switch is turned off; when the third power supply good signal output from the medium-voltage step-down status signal output terminal is valid, the first switch and the second switch are turned off, and the third switch is turned on.

[0013] Furthermore, when the voltage at the power input terminal is too low and the gate drive of the third switch has not yet been established, the medium-voltage bus supplies power to the primary low-voltage conversion unit through the body diode of the third switch to maintain uninterrupted power supply to the downstream load.

[0014] Furthermore, the energy storage module also includes a sampling resistor and a constant current control loop; The charging switch is a P-channel MOSFET. The source of the charging switch is connected to the high-voltage bus via the sampling resistor, and the drain of the charging switch is connected to the energy storage port. The feedback input terminal of the constant current control loop is connected to the sampling resistor. The constant current control loop adjusts the gate voltage of the charging switch transistor in a closed loop according to the current feedback signal on the sampling resistor, so as to set the current to charge the energy storage capacitor with constant current. The set current is set by the control unit.

[0015] Furthermore, during the constant current charging process of the energy storage capacitor, the charging switch operates in the saturation region; when the voltage of the energy storage port is close to the voltage of the high-voltage bus and the voltage drop across the sampling resistor approaches zero, it is determined that the energy storage capacitor is fully charged; after being fully charged, the charging switch remains in the conducting state to compensate for the leakage loss of the energy storage capacitor, so that the voltage of the energy storage port is maintained at the voltage level of the high-voltage bus.

[0016] Furthermore, the energy storage module also includes an energy storage diagnostic circuit; the energy storage diagnostic circuit is connected to the energy storage port and is used to perform status detection on the energy storage capacitor before the control unit enables charging, and to report the energy storage status of the energy storage capacitor to the control unit after the detection is passed. The status detection includes at least one of short circuit detection, open circuit detection and capacity abnormality detection; the energy storage diagnostic circuit is also used to independently perform periodic online detection on the energy storage capacitor during system operation.

[0017] Furthermore, it also includes a hardware comparator circuit; the hardware comparator circuit is used to detect the voltage at the power input terminal, and when the voltage at the power input terminal is lower than a set threshold, it forces the charging switch to be turned on to form a discharge path from the energy storage port to the high-voltage bus, as a redundant backup mechanism for the automatic conduction of the body diode.

[0018] A power supply control method for an on-board backup power system, applied to the on-board backup power system as described above, includes: Step S1: Low-voltage power supply setup: After the power input terminal is powered on, the primary low-voltage conversion unit converts the input voltage into a low-voltage power supply; Step S2: High voltage and medium voltage are established step by step: After the low voltage power supply is stabilized, the high voltage boost unit is enabled to boost the input voltage to establish the voltage of the high voltage bus; after the voltage of the high voltage bus is stabilized, the medium voltage buck unit is enabled to buck the voltage of the high voltage bus to establish the voltage of the medium voltage bus. Step S3: Low-voltage power supply switching: After the voltage of the medium-voltage bus is established, the power supply switching unit switches the power supply source of the downstream load from the power input terminal to the medium-voltage bus. Step S4: Post-installed energy storage access: After the power supply switching unit completes the switching, the control unit controls the charging switch tube to turn on, and charges the energy storage capacitor through the high-voltage bus until the voltage of the energy storage capacitor reaches the voltage of the high-voltage bus.

[0019] Furthermore, step S4 includes: Step S401: Perform status detection on the energy storage capacitor. The status detection includes judging at least one fault among short circuit, open circuit and capacity abnormality. After the detection is passed, report the normal energy storage status. Step S402: The control unit sends a charging enable command and a charging current setting command through the command bus. The constant current control loop adjusts the gate voltage of the charging switch transistor in a closed loop according to the current feedback signal on the sampling resistor to set the current for constant current charging of the energy storage capacitor. During constant current charging, the charging switch transistor operates in the saturation region. When the voltage of the energy storage port is close to the voltage of the high voltage bus and the voltage drop across the sampling resistor approaches zero, it is determined that the energy storage capacitor is fully charged. After being fully charged, the charging switch transistor remains in the conducting state to compensate for the leakage loss of the energy storage capacitor.

[0020] Furthermore, it also includes step S5: backup power supply step: When a circuit breaks or the voltage drops below the power supply threshold at the power input terminal, the high-voltage boost unit stops working, and the voltage of the high-voltage bus gradually decreases with the support of the load capacitor connected to its output terminal. The medium-voltage buck unit continues to work while the voltage of the high-voltage bus is higher than the voltage setting value of the medium-voltage bus, maintaining the voltage output of the medium-voltage bus. When the voltage of the high-voltage bus drops to the condition VUP < VER - VF, the body diode of the charging switch automatically turns on, and the electrical energy stored in the energy storage capacitor is injected into the high-voltage bus in reverse through the body diode of the charging switch to maintain the voltage of the high-voltage bus; where VUP is the voltage of the high-voltage bus, VER is the voltage of the energy storage port, and VF is the forward conduction voltage drop of the body diode. The high-voltage bus maintains the input of the medium-voltage step-down unit, and the medium-voltage step-down unit continuously outputs to maintain the voltage of the medium-voltage bus. The medium-voltage bus continuously supplies power to the downstream load through the power supply switching unit until the energy storage capacitor releases energy until the medium-voltage step-down unit stops working due to insufficient input voltage.

[0021] Furthermore, it also includes: periodically online monitoring of the energy storage capacitor during system operation; the periodic online monitoring uses the voltage change rate of the energy storage capacitor to estimate the capacitance, and applies a small-signal AC disturbance of fixed frequency to measure the complex impedance of the energy storage capacitor to assess the capacitance value and the health status of the equivalent series resistance.

[0022] An on-board controller includes an on-board backup power system as described above.

[0023] A vehicle including the aforementioned on-board controller.

[0024] The present invention has the following advantages: This invention employs a tiered power-on strategy to avoid the current superposition impact caused by the simultaneous startup of multiple converters, thereby reducing the instantaneous power demand at the power input terminal. Furthermore, the connection of the large-capacity energy storage capacitor is postponed until the system is fully established and operating stably, ensuring that no large capacitive loads are connected to the high-voltage bus and medium-voltage bus during the entire cold start process. This can suppress the generation of surge current and significantly improve the success rate of the first power-on under harsh on-board power supply environments. The energy storage port set in this invention is independent of the high-voltage bus, and the two are only controlled to be coupled through the charging switch tube. When the external energy storage capacitor is short-circuited and breaks down, the fault can be limited to the energy storage port side, the high-voltage bus voltage is not affected, and the system can still rely on the power input terminal to maintain the operation of the high-voltage bus. This cuts off the failure path of a single point failure in energy storage leading to global paralysis, realizes physical isolation of energy storage faults, reduces the risk of single point failure, and helps to improve the functional safety level of the system. In this invention, the energy storage capacitor is isolated from the main power bus by a charging switch tube. The state detection of the energy storage capacitor can be performed independently on the energy storage port side without injecting disturbances into the bus or cutting off the main circuit current. The diagnostic process does not affect the normal operation of the system, realizing online independent diagnosis of the energy storage unit and supporting periodic online detection during vehicle operation. This can overcome the limitation of existing technologies that can only perform voltage detection once at the moment of power-on.

[0025] This invention uses a constant current control loop to perform closed-loop regulation of the charging switch, which can achieve precise and smooth constant current charging. This avoids the problem of excessively long charging time caused by the charging current continuously decreasing as the capacitor terminal voltage increases in the RC current limiting scheme, and also avoids the problem of excessive inrush current when the capacitor is directly connected. The stable and controlled charging current reduces the electrochemical stress inside the capacitor, which helps to extend the service life of the energy storage capacitor and maintain stable capacity.

[0026] This invention utilizes the inherent body diode of the charging switch as a reverse discharge path from the energy storage port to the high-voltage bus, eliminating the need for additional discharge switches and control logic. It automatically turns on when power is lost, with a response time in the microsecond range, faster than the millisecond-level response of software interrupts. This makes it suitable for loads with stringent response time requirements, such as airbags. At the same time, the configuration of the first and second switches can block the backflow path of backup energy to the de-energized battery, allowing the stored energy to be fully used to maintain downstream loads and improve energy utilization efficiency.

[0027] This invention uses a high-voltage bus as an energy storage voltage platform, which can store and release more energy with the same capacitance and can sustain power loss for a longer period of time. The voltages of both the high-voltage bus and the medium-voltage bus can be set within a wide range, making it compatible with various vehicle controller platforms such as airbag controllers, intelligent driving domain controllers, and drive-by-wire chassis, and has strong platform versatility. Attached Figure Description

[0028] Figure 1 This is a structural block diagram of an on-board backup power system provided in an embodiment of the present invention; Figure 2 A circuit diagram of a power supply switching unit provided in an embodiment of the present invention; Figure 3 This is a structural block diagram of an energy storage module provided in an embodiment of the present invention; Figure 4 This is a flowchart illustrating steps S1 to S4 provided in the method of this embodiment of the invention; Figure 5 This is a flowchart illustrating the backup power supply process in step S5 of the method provided in the embodiment of the present invention. Detailed Implementation

[0029] See Figure 1 An on-board backup power system, comprising: Primary low-voltage conversion unit 1, the input terminal of primary low-voltage conversion unit 1 is connected to power input terminal 2, primary low-voltage conversion unit 1 can convert the input voltage provided by power input terminal 2 into low-voltage power supply, the low-voltage power supply is used to power the subsequent load; High voltage boost unit 3, the input terminal of high voltage boost unit 3 is connected to power input terminal 2. High voltage boost unit 3 starts after the primary low voltage conversion unit 1 establishes low voltage power supply, boosts the input voltage and outputs it to high voltage bus 4. Medium voltage step-down unit 5, the input terminal of medium voltage step-down unit 5 is connected to high voltage bus 4, and is used to start after the voltage of high voltage bus 4 is established, and output the voltage input from high voltage bus 4 to medium voltage bus 6 after stepping down the voltage. The power supply switching unit 7 has a first input terminal connected to the power input terminal 2 and a second input terminal connected to the medium voltage bus 6. It is used to switch the power supply source of the downstream load from the power input terminal to the medium voltage bus after the voltage of the medium voltage bus 6 is established. The energy storage module 8 includes: a charging switch Q_CH, which is connected between the high-voltage bus 4 and the energy storage port VER, and the conduction direction of the body diode of the charging switch Q_CH is from the energy storage port to the high-voltage bus; and an energy storage capacitor C_ER, which is connected to the energy storage port VER. The control unit 9 is used to control the charging switch Q_CH to turn on after the power supply switching unit 7 completes the switching, so that the high voltage bus 4 can charge the energy storage capacitor. When the power input terminal 2 loses power, causing the voltage of the high-voltage bus to drop below the difference between the voltage of the energy storage port and the forward conduction voltage drop of the body diode, the body diode of the charging switch Q_CH will turn on. The energy storage capacitor C_ER will then feed back to the high-voltage bus 4 through the charging switch Q_CH to maintain the voltage of the high-voltage bus.

[0030] In one embodiment of the present invention, an on-board backup power system is provided, which can be applied to on-board controllers such as airbag controllers, and its overall structure is as follows: Figure 1 As shown, it includes: a power input terminal 2, a primary low-voltage conversion unit 1, a high-voltage boost unit 3, a medium-voltage buck unit 5, a power supply switching unit 7, a reset determination unit 10, a control unit 9, and an energy storage module 8. The energy storage module includes an external large-capacity energy storage capacitor C_ER. The control unit 9 is implemented using a microcontroller. Except for the energy storage capacitor C_ER, all other units can be integrated into a single automotive-grade power management chip, with the energy storage capacitor C_ER used as an external component.

[0031] In this embodiment, the power input terminal 2 is connected to a typical 12V vehicle battery, and is also connected to the input terminal of the primary low-voltage conversion unit 1 and the first input terminal of the power supply switching unit 7. The primary low-voltage conversion unit 1 is composed of an LDO (low dropout linear regulator) or a pre-buck converter, and is automatically started by hardware logic without MCU intervention. The output terminal of the primary low-voltage conversion unit 1 outputs low-voltage power, including providing digital power such as 1.3V / 3.3V to power the control unit 9, and analog power such as 5V to power the analog front end. The low-voltage power is also used to power the low-voltage modules inside each stage of the power conversion unit. The low-voltage conversion status signal output terminal of the primary low-voltage conversion unit 1 is connected to the enable terminal of the high-voltage boost unit 3, and outputs a first power good signal PG1 after the low-voltage power is stabilized.

[0032] In this embodiment, the high-voltage boost unit 3 is composed of a BOOST circuit. Its input terminal is connected to the power input terminal 2, and its output terminal serves as the high-voltage bus. The typical voltage VUP of the high-voltage bus is 33V, and its settable range is 24V to 48V, which can be extended to 18V to 60V for a wider range implementation. The high-voltage boost status signal output terminal of the high-voltage boost unit 3 is connected to the enable terminal of the medium-voltage buck unit 5. After the voltage of the high-voltage bus stabilizes, it outputs a second power good signal PG2. The medium-voltage buck unit 5 is composed of a BUCK circuit. Its input terminal is connected to the high-voltage bus, and its output terminal serves as the medium-voltage bus. The typical voltage VAS of the medium-voltage bus is 6.7V, and its settable range is 3.3V to 12V. The medium-voltage buck status signal output terminal of the medium-voltage buck unit 5 outputs a third power good signal PG3 after the voltage of the medium-voltage bus is established and reaches a threshold. As an example, the effective threshold of each power good signal can be set to 90% of the corresponding nominal output voltage value. That is, when the output voltage reaches more than 90% of the nominal value, the corresponding PG signal is set to effective.

[0033] The primary low-voltage conversion unit 1, the high-voltage boost unit 3, and the medium-voltage buck unit 5 are cascaded and enabled by PG1 and PG2 to form a hierarchical power-on link for low voltage, high voltage, and medium voltage: the next stage power supply is automatically enabled by hardware only after the previous stage power supply is established and stabilized. The hierarchical power-on in this embodiment avoids the current superposition impact caused by the simultaneous start-up of multiple converters, which can reduce the instantaneous power demand on the power input terminal and improve the first power-on success rate under harsh power supply environments such as startup.

[0034] In this embodiment, the first input terminal of the power supply switching unit 7 is connected to the power input terminal 2, the second input terminal is connected to the medium-voltage bus, and the output terminal is the load terminal V_load. The load terminal V_load is connected to the primary low-voltage conversion unit 1 to provide power to the downstream load, including the MCU main power supply and the driver chip power supply. The power supply switching unit 7 uses the third power good signal PG3 as the switching determination condition: when the third power good signal PG3 is invalid, V_load is powered by the power input terminal 2; when the third power good signal PG3 is valid, the power source of V_load is switched to the medium-voltage bus.

[0035] See Figure 2 The power supply switching unit 7 includes a first switch Q1, a second switch Q2, and a third switch Q3. The power input terminal outputs a voltage VBAT. Two P-channel MOSFETs, namely the first switch Q1 and the second switch Q2, are positioned back-to-back along the path from the power input terminal to the load terminal V_load. The drain of the first switch Q1 is connected to the drain of the second switch Q2, and the source of the first switch Q1 is connected to the power input terminal. The source of the second switch Q2 is connected to the source of the third switch Q3, and the drain of the third switch Q3 is connected to the medium-voltage bus 6. The gate of the first switch Q1 is connected to the gate of the second switch Q2 and is also connected to the medium-voltage buck state signal output terminal of the medium-voltage buck unit 5. The gate of the third switch Q3 is connected to an inverter and then connected to the gates of the first switch Q1 and the second switch Q2. The first switch Q1 and the second switch Q2 are connected back-to-back so that the conduction directions of the two body diodes are opposite in the off state, which can block leakage current in either direction on the VBAT path. On the path from the medium voltage bus to the load terminal V_load, a P-channel MOSFET, namely Q3, is set as a switching switch. The conduction direction of the body diode of the third switch Q3 is from the medium voltage bus to the load terminal V_load. The gate control signals of the first switch Q1 and the second switch Q2 are out of phase with the gate control signal of the third switch Q3, and the switching condition is determined by the third power good signal PG3: when the third power good signal PG3 is invalid, the first switch Q1 and the second switch Q2 are turned on, the third switch Q3 is turned off, and the load terminal V_load is powered by VBAT; when the third power good signal PG3 is valid, the first switch Q1 and the second switch Q2 are turned off, the third switch Q3 is turned on, and the load terminal V_load is powered by the medium voltage bus, realizing seamless switching of the power supply body; after the switching is completed, the first switch Q1 and the second switch Q2 are in the off state, and their reverse series body diodes physically block the path of reverse current from the medium voltage bus to the power input terminal. Even if the vehicle battery loses power or is disconnected, the energy of the backup energy storage will not be discharged through the power input terminal, but will be used to maintain the downstream load.

[0036] When the voltage at the power input terminal is too low and the gate drive of the third switch Q3 has not yet been established, the medium voltage bus can directly supply power to the load terminal V_load through the body diode of the third switch Q3 to maintain uninterrupted system operation, ensure the continuity of power supply to the load terminal V_load during the switching process, and avoid power interruption at the moment of switching.

[0037] The embodiment also includes a reset determination unit 10. Multiple inputs of the reset determination unit 10 receive a first power good signal PG1, a second power good signal PG2, and a third power good signal PG3, respectively. The output is connected to the reset terminal of the control unit 9. When all power good signals are valid, the reset determination unit outputs a power ready signal PG_on, releasing the control unit from its reset state. As an example, the reset determination unit can be implemented using AND logic circuitry, where PG_on is the logical AND of PG1, PG2, and PG3. After the control unit is reset, a series of self-test diagnostic commands are sent to the control logic inside the power management chip via the command bus. If the diagnostics are successful, a charging enable command and a charging current setting command are sent to initiate the energy storage access process.

[0038] The energy storage module is connected between the high-voltage bus and the energy storage port VER. The energy storage port VER is an independent pin of the power management chip. A large-capacity energy storage capacitor C_ER is externally connected between the energy storage port VER and ground. In this embodiment, a large-capacity energy storage capacitor with a capacity of 4700μF is used. The energy storage port VER achieves controllable coupling through the charging switch Q_CH. See Figure 3The energy storage module includes a charging switch Q_CH, a sampling resistor R1, a constant current control loop 801, and an energy storage diagnostic circuit 802. In this embodiment, the charging switch Q_CH is a P-channel MOSFET. The source of the charging switch Q_CH is connected to the high-voltage bus via the sampling resistor R1, the drain of the charging switch Q_CH is connected to the energy storage port VER, and the gate of the charging switch Q_CH is connected to the constant current control loop 801. The feedback input terminal of the constant current control loop 801 is connected to the sampling resistor R1. The current feedback signal is obtained from the sampling resistor R1, and the gate voltage of the charging switch Q_CH is adjusted in a closed loop to achieve precise constant current charging control. The set value of the charging current is configured by the control unit. The conduction direction of the body diode of Q_CH is from the energy storage port VER to the high voltage bus, providing a unidirectional conduction path from the energy storage port VER to the high voltage bus. It can automatically conduct without additional control logic during standby discharge. The energy storage diagnostic circuit 802 is connected to the energy storage port VER and is used to detect the status of the energy storage capacitor C_ER and report the detection results to the control unit through the internal logic of the chip.

[0039] The energy storage port VER is controllably coupled to the high-voltage bus only through the charging switch Q_CH. When the external energy storage capacitor C_ER experiences a short circuit breakdown or lead solder collapse, the impact of the fault is limited to the energy storage port VER side. The fault circuit can be cut off by turning off Q_CH or the internal fuse, and the voltage of the high-voltage bus remains unaffected, allowing the high-voltage bus to continue operating via the power input. Compared to the existing solution where the energy storage capacitor is directly connected in parallel to the power bus, this embodiment cuts off the failure path from a single point fault in the energy storage capacitor that could paralyze the entire power network, thus improving the functional safety level of the system. The energy storage diagnostic circuit detects the energy storage capacitor C_ER independently on the energy storage port VER side. The detection process does not pass through the main power circuit of the high-voltage bus and will not interfere with the normal operation of the system, making periodic online detection during operation possible and overcoming the limitation of existing technologies that can only perform a voltage detection once at the moment of power-on.

[0040] Based on the aforementioned on-board backup power system, this embodiment provides a power supply control method that adopts a step-by-step timing management strategy of first powering on the system and then connecting the energy storage. The power-on and energy storage connection processes are as follows: Figure 4 As shown, it includes the following steps.

[0041] Step S1: Low-voltage power supply setup: The system is powered on, and the power input terminal is connected to the primary low-voltage conversion unit. The primary low-voltage conversion unit is started automatically by hardware logic without MCU intervention, and outputs low-voltage power to power the low-voltage modules of each stage of power conversion unit, as well as the control unit and analog front end.

[0042] Step S2: High and medium voltage are established step by step: After the low voltage power supply is stable, the primary low voltage conversion unit sends the first power good signal PG1 signal, which automatically enables the high voltage boost unit to boost the 12V voltage VBAT at the power input terminal to the 33V voltage VUP of the high voltage bus; after VUP is stable, the second power good signal PG2 signal enables the medium voltage buck unit to buck the VUP to the 6.7V voltage VAS of the medium voltage bus.

[0043] Step S3: Low-voltage power supply switching: After the VAS voltage is established and reaches the threshold, the medium-voltage step-down unit outputs the third power supply good signal PG3. The third power supply good signal PG3 serves as the switching judgment condition, causing the control signal of the power supply switching unit to flip: the gate drive signals of the first switch Q1 and the second switch Q2 become invalid, shutting off the power supply path at the power input terminal; the gate drive signal of the third switch Q3 becomes valid, turning on the medium-voltage bus power supply path. The power supply source for the downstream load is switched from 12V voltage VBAT to the medium-voltage bus, and the load is no longer directly powered by 12V voltage VBAT; the settings of the first switch Q1 and the second switch Q2 ensure that leakage current in the VBAT path is blocked in the off state, and the energy of the medium-voltage bus will not flow back to the battery terminal.

[0044] Step S4: Post-installed energy storage diagnostics and safe charging: After the medium-voltage bus replaces the 12V voltage VBAT, the power supply switch is completed, and the entire system is operating stably, the control unit initiates the energy storage access process, which specifically includes: Step S401, Status Self-Check: The energy storage diagnostic circuit integrated inside the power management chip performs status detection on the energy storage capacitor C_ER connected to the energy storage port VER, including but not limited to fault judgment such as capacitor short circuit, open circuit, and abnormal capacity; after the diagnosis is successful, the chip reports the normal energy storage status to the control unit.

[0045] Step S402: Constant Current Post-Charge: After confirming no abnormalities, the control unit sends a charging enable command and a current setting command. The constant current control loop uses the current feedback on the sampling resistor as input to adjust the gate voltage of the charging switch Q_CH in a closed loop, charging the external energy storage capacitor C_ER with the set current. During this process, Q_CH operates in the saturation region. As the voltage of the energy storage port VER gradually increases, the source-drain voltage VDS of Q_CH gradually decreases. Under the condition that the gate-source voltage VGS remains basically unchanged and the constant current output is maintained, Q_CH is in the saturation region, and the charging current remains constant. When the terminal voltage of the energy storage capacitor C_ER approaches the VUP voltage, the voltage drop across the sampling resistor approaches zero, leaving only a very small leakage current. Based on this, the chip determines that the capacitor is fully charged. After being fully charged, Q_CH remains in its current on-state to continuously replenish the leakage loss of the energy storage capacitor C_ER itself, keeping its voltage at the VUP level and ensuring that the backup energy is always in a fully ready state.

[0046] In steps S1 to S3, no large capacitive loads are connected to either the high-voltage bus or the medium-voltage bus. The connection of the large-capacity energy storage capacitor is postponed until the system is fully established and operating stably, suppressing the generation of surge current. Combined with the tiered power-on process, this significantly improves the success rate of the first power-on under harsh on-board power supply conditions. The constant current charging mechanism achieves a precise and smooth charging process, avoiding the problem of excessively long charging time caused by the charging current continuously decreasing as the capacitor terminal voltage increases in traditional RC current limiting schemes. It also avoids the problem of excessive inrush current when the capacitor is directly connected. Precise current control can reduce the electrochemical stress inside the capacitor, which helps to extend the service life of the energy storage capacitor and maintain capacity stability. In addition, the order of diagnosis before charging ensures that only energy storage capacitors in normal condition are connected, preventing secondary faults caused by blindly charging failed capacitors.

[0047] During system operation, the energy storage diagnostic circuit can also perform periodic online monitoring of the energy storage capacitor C_ER. Monitoring methods can include estimating capacitance by detecting the rate of voltage change, or applying a small-signal AC disturbance at a fixed frequency and measuring the capacitor's complex impedance (EIS, electrochemical impedance spectroscopy) to simultaneously assess the capacitance value and the health of the equivalent series resistance (ESR). Since all monitoring is performed on the VER side of the energy storage port, there is no need to inject disturbances into the high-voltage bus or interrupt the main circuit current; therefore, the diagnostic process does not affect normal system operation.

[0048] See Figure 5 In one embodiment, the method further includes step S5: backup power supply, comprising the following processes: After the system is powered on and energy is stored, if a vehicle experiences a severe collision, causing a circuit break at the power input or a sudden voltage drop below the power supply threshold, the high-voltage boost unit will stop working due to the loss or sudden drop in its input power. The voltage VUP of the high-voltage bus will begin to decrease. Since both the high-voltage boost unit and the medium-voltage buck unit have external load capacitors on the order of tens of μF at their output terminals, the drop in VUP is slow and will not instantly return to zero. At the same time, the voltage VAS of the medium-voltage bus is still maintained by VUP: as long as VUP is higher than the set value of VAS, the medium-voltage buck unit can continue to output, and the system load continues to draw current from the high-voltage bus. When VUP drops below the difference between the voltage at the energy storage port VER and the forward voltage drop of the body diode of the charging switch Q_CH, i.e., when VUP < VER - VF (where VF is the forward voltage drop of the body diode of Q_CH, typically around 0.7V), the body diode of Q_CH automatically turns on. The turn-on process is entirely driven by the hardware's physical characteristics and is independent of the gate drive state of Q_CH, with a response time in the microsecond range. The high-voltage energy stored in the energy storage capacitor C_ER is then injected back into the high-voltage bus via the body diode, preventing VUP from dropping further.

[0049] The high-voltage bus maintains the input of the medium-voltage step-down unit, which continuously outputs VAS. VAS is continuously supplied to the downstream load via the conducting Q3. During the discharge maintenance process, the energy of the energy storage capacitor C_ER is gradually released until the medium-voltage step-down unit stops outputting due to insufficient input voltage, the control unit resets, and the system stops working. Within this maintenance time window, critical loads such as the airbag ignition drive can complete the predetermined safety actions after a power failure.

[0050] In this embodiment, the inherent body diode of the charging switch Q_CH is used as the reverse discharge path from the energy storage port VER to the high-voltage bus. No additional discharge switch or complex logic control circuit is required. The microsecond-level automatic response speed is faster than the millisecond-level speed of the MCU software interrupt response, which is of great value for loads such as airbags that have strict requirements for response time.

[0051] Based on the above embodiments, this embodiment provides several alternative implementation methods. These alternative implementation methods can be used alone or in combination with the foregoing embodiments, and none of them depart from the inventive concept of the present invention.

[0052] In the aforementioned embodiment, constant current charging is completed by the control unit sending instructions to control the internal constant current source of the chip; alternatively, a discrete linear constant current circuit composed of an operational amplifier and a MOSFET can be connected in series outside the energy storage port VER, and the control unit only outputs a charging enable signal, which can also achieve the effect of post-slow start charging.

[0053] The voltage VUP of the high-voltage bus is not limited to 33V and can be set within a wide range from 18V to 60V according to the actual system withstand voltage and efficiency requirements. The voltage VAS of the medium-voltage bus is not limited to 6.7V and can be equivalently replaced by adjusting the feedback network of the medium-voltage step-down unit according to the downstream load requirements (such as 3.3V, 5V, 9V, 12V). For example, 5V can be used for analog front-end power supply, 1.3V can be used for digital circuit power supply, and 12V can be used for motor drive loads.

[0054] The load switch that enables the VBAT to switch power supply to the medium-voltage bus can be replaced with a back-to-back dual P-channel MOSFET and a corresponding level shifting circuit, or a dedicated power path management chip, as long as it can realize the logic of prioritizing the conduction of the medium-voltage bus path after the medium-voltage bus is established and preventing backflow.

[0055] The protection mechanism that triggers reverse discharge of the energy storage port VER when VBAT loses power can rely on the automatic conduction of the body diode and the interrupt response of the MCU, or it can add a pure hardware comparator circuit: when the voltage of VBAT is detected to be lower than the set threshold, the hardware comparator directly forces the charging switch Q_CH to be turned on, forming a discharge path from the energy storage port VER to the high-voltage bus, as a safe redundancy backup mechanism in case of MCU failure.

[0056] This invention also provides an on-board controller, including the on-board backup power system of any of the foregoing embodiments. The on-board controller can be an airbag controller, an automatic emergency braking controller, an intelligent driving domain controller, or a drive-by-wire chassis controller, etc. Taking an airbag controller as an example: high-voltage, high-current loads such as the ignition drive circuit can be powered by a high-voltage bus, analog front-ends such as acceleration sensors are powered by a low-noise 5V analog power supply, and digital circuits such as the MCU are powered by a 1.3V / 3.3V digital power supply. This constitutes a hierarchical energy link of high-voltage energy storage, medium-voltage transmission, and low-voltage use, balancing power failure sustainment time, energy conversion efficiency, and power quality. Thanks to the wide settable range of VUP (18V~60V) and VAS (3.3V~12V), this power architecture can adapt to the power supply requirements of different vehicle platforms and different controllers without changing the topology, exhibiting strong platform versatility.

[0057] The present invention also provides a vehicle including the aforementioned vehicle controller. In the event of a collision that causes the battery to lose power or become detached, the vehicle controller can continue to operate for a period of time after the power loss, relying on the reserve energy of the energy storage capacitor C_ER, to complete critical safety actions such as airbag ignition, thereby improving the passive safety reliability of the entire vehicle.

[0058] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended 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 of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A vehicle-mounted backup power system, characterized in that, include: A primary low-voltage conversion unit, the input terminal of which is connected to a power input terminal, is capable of converting the input voltage provided by the power input terminal into a low-voltage power supply, which is used to power the subsequent load connected to the primary low-voltage conversion unit. A high-voltage boost unit, the input terminal of which is connected to the power input terminal, is started after the primary low-voltage conversion unit establishes a low-voltage power supply, and boosts the input voltage before outputting it to the high-voltage bus. A medium-voltage step-down unit, the input terminal of which is connected to the high-voltage bus, is used to start after the voltage of the high-voltage bus is established, and to step down the voltage input from the high-voltage bus and output it to the medium-voltage bus; A power supply switching unit, wherein the first input terminal of the power supply switching unit is connected to the power input terminal and the second input terminal of the power supply switching unit is connected to the medium voltage bus, is used to switch the power supply source of the downstream load from the power input terminal to the medium voltage bus after the voltage of the medium voltage bus is established; An energy storage module includes: a charging switch transistor connected between the high-voltage bus and the energy storage port, wherein the conduction direction of the body diode of the charging switch transistor is from the energy storage port to the high-voltage bus; and an energy storage capacitor connected to the energy storage port. The control unit is used to control the charging switch tube to turn on after the power supply switching unit completes the switching, so that the high voltage bus can charge the energy storage capacitor. When the power input terminal loses power, causing the voltage of the high-voltage bus to drop, and the body diode of the charging switch transistor to conduct, the energy storage capacitor feeds back to the high-voltage bus through the charging switch transistor to maintain the voltage of the high-voltage bus.

2. The vehicle-mounted backup power system according to claim 1, characterized in that: The primary low-voltage conversion unit is provided with a low-voltage conversion status signal output terminal, which is connected to the enable terminal of the high-voltage boost unit. After the low-voltage power supply stabilizes, the primary low-voltage conversion unit outputs a first power good signal from the low-voltage conversion status signal output terminal to enable the high-voltage boost unit to start. The high-voltage boost unit is provided with a high-voltage boost status signal output terminal, which is connected to the enable terminal of the medium-voltage buck unit. After the voltage of the high-voltage bus stabilizes, the high-voltage boost unit outputs a second power good signal from the high-voltage boost status signal output terminal to enable the medium-voltage buck unit to start. The medium-voltage step-down unit is equipped with a medium-voltage step-down status signal output terminal. After the voltage of the medium-voltage bus is established and reaches the threshold, it outputs a third power supply good signal. The third power supply good signal serves as the switching judgment condition for the power supply switching unit.

3. The vehicle-mounted backup power system according to claim 2, characterized in that, It also includes a reset determination unit; the multiple input terminals of the reset determination unit receive the first power good signal, the second power good signal and the third power good signal respectively, and the output terminal of the reset determination unit is connected to the reset terminal of the control unit, and is used to output a power ready signal when all power good signals are valid, thereby releasing the reset state of the control unit.

4. The on-board backup power system according to claim 2, characterized in that, The power supply switching unit includes a first switch, a second switch, and a third switch; The first and second switching transistors are disposed between the power input terminal and the input terminal of the primary low-voltage conversion unit. The drain of the first switching transistor is connected to the drain of the second switching transistor, and the source of the first switching transistor is connected to the power input terminal. The source of the second switching transistor is connected to the source of the third switching transistor, and the drain of the third switching transistor is connected to the medium-voltage bus. The gates of the first and second switching transistors are connected and connected to the medium-voltage buck state signal output terminal of the medium-voltage buck unit. The gate of the third switching transistor is connected to an inverter and then connected to the gates of both the first and second switching transistors. When the third power supply good signal output from the medium-voltage step-down status signal output terminal is invalid, the first switch and the second switch are turned on, and the third switch is turned off; when the third power supply good signal output from the medium-voltage step-down status signal output terminal is valid, the first switch and the second switch are turned off, and the third switch is turned on.

5. The on-board backup power system according to claim 4, characterized in that, When the voltage at the power input terminal is too low and the gate drive of the third switch has not yet been established, the medium voltage bus supplies power to the primary low voltage conversion unit through the body diode of the third switch to maintain uninterrupted power supply to the downstream load.

6. The vehicle-mounted backup power system according to claim 1, characterized in that, The energy storage module also includes a sampling resistor and a constant current control loop; The charging switch is a P-channel MOSFET. The source of the charging switch is connected to the high-voltage bus via the sampling resistor, and the drain of the charging switch is connected to the energy storage port. The feedback input terminal of the constant current control loop is connected to the sampling resistor. The constant current control loop adjusts the gate voltage of the charging switch transistor in a closed loop according to the current feedback signal on the sampling resistor, so as to set the current to charge the energy storage capacitor with constant current. The set current is set by the control unit.

7. The on-board backup power system according to claim 6, characterized in that, During the constant current charging process of the energy storage capacitor, the charging switch operates in the saturation region. When the voltage of the energy storage port is close to the voltage of the high-voltage bus and the voltage drop across the sampling resistor approaches zero, the energy storage capacitor is determined to be fully charged. After being fully charged, the charging switch remains in the conducting state to compensate for the leakage loss of the energy storage capacitor, so that the voltage of the energy storage port is maintained at the voltage level of the high-voltage bus.

8. The vehicle-mounted backup power system according to claim 1, characterized in that, The energy storage module also includes an energy storage diagnostic circuit; the energy storage diagnostic circuit is connected to the energy storage port and is used to perform status detection on the energy storage capacitor before the control unit enables charging, and to report the energy storage status of the energy storage capacitor to the control unit after the detection is passed. The status detection includes at least one of short circuit detection, open circuit detection and capacity abnormality detection; the energy storage diagnostic circuit is also used to independently perform periodic online detection on the energy storage capacitor during system operation.

9. The vehicle-mounted backup power system according to claim 1, characterized in that, It also includes a hardware comparator circuit; the hardware comparator circuit is used to detect the voltage at the power input terminal, and when the voltage at the power input terminal is lower than a set threshold, it forces the charging switch to be turned on to form a discharge path from the energy storage port to the high-voltage bus, as a redundant backup mechanism for the automatic conduction of the body diode.

10. A power supply control method for an on-board backup power system, applied to the on-board backup power system as described in any one of claims 1 to 9, characterized in that, include: Step S1: Low-voltage power supply setup: After the power input terminal is powered on, the primary low-voltage conversion unit converts the input voltage into a low-voltage power supply; Step S2: High voltage and medium voltage are established step by step: After the low voltage power supply is stabilized, the high voltage boost unit is enabled to boost the input voltage to establish the voltage of the high voltage bus; after the voltage of the high voltage bus is stabilized, the medium voltage buck unit is enabled to buck the voltage of the high voltage bus to establish the voltage of the medium voltage bus. Step S3: Low-voltage power supply switching: After the voltage of the medium-voltage bus is established, the power supply switching unit switches the power supply source of the downstream load from the power input terminal to the medium-voltage bus. Step S4: Post-installed energy storage access: After the power supply switching unit completes the switching, the control unit controls the charging switch tube to turn on, and charges the energy storage capacitor through the high-voltage bus until the voltage of the energy storage capacitor reaches the voltage of the high-voltage bus.

11. The power supply control method according to claim 10, characterized in that, Step S4 includes: Step S401: Perform status detection on the energy storage capacitor. The status detection includes judging at least one fault among short circuit, open circuit and capacity abnormality. After the detection is passed, report the normal energy storage status. Step S402: The control unit sends a charging enable command and a charging current setting command through the command bus. The constant current control loop adjusts the gate voltage of the charging switch transistor in a closed loop according to the current feedback signal on the sampling resistor to set the current for constant current charging of the energy storage capacitor. During constant current charging, the charging switch transistor operates in the saturation region. When the voltage of the energy storage port is close to the voltage of the high voltage bus and the voltage drop across the sampling resistor approaches zero, it is determined that the energy storage capacitor is fully charged. After being fully charged, the charging switch transistor remains in the conducting state to compensate for the leakage loss of the energy storage capacitor.

12. The power supply control method according to claim 10, characterized in that, It also includes step S5: backup power supply: When a circuit breaks or the voltage drops below the power supply threshold at the power input terminal, the high-voltage boost unit stops working, and the voltage of the high-voltage bus gradually decreases with the support of the load capacitor connected to its output terminal. The medium-voltage buck unit continues to work while the voltage of the high-voltage bus is higher than the voltage setting value of the medium-voltage bus, maintaining the voltage output of the medium-voltage bus. When the voltage of the high-voltage bus drops to the condition VUP < VER - VF, the body diode of the charging switch automatically turns on, and the electrical energy stored in the energy storage capacitor is injected into the high-voltage bus in reverse through the body diode of the charging switch to maintain the voltage of the high-voltage bus; where VUP is the voltage of the high-voltage bus, VER is the voltage of the energy storage port, and VF is the forward conduction voltage drop of the body diode. The high-voltage bus maintains the input of the medium-voltage step-down unit, and the medium-voltage step-down unit continuously outputs to maintain the voltage of the medium-voltage bus. The medium-voltage bus continuously supplies power to the downstream load through the power supply switching unit until the energy storage capacitor releases energy until the medium-voltage step-down unit stops working due to insufficient input voltage.

13. The power supply control method according to claim 12, characterized in that, Also includes: During system operation, the energy storage capacitor is periodically monitored online. The periodic online monitoring uses the voltage change rate of the energy storage capacitor to estimate the capacitance, and applies a small-signal AC disturbance at a fixed frequency to measure the complex impedance of the energy storage capacitor to assess the capacitance value and the health status of the equivalent series resistance.

14. A vehicle-mounted controller, characterized in that, Includes the vehicle-mounted backup power system as described in any one of claims 1 to 9.

15. A vehicle, characterized in that, Including the vehicle controller as described in claim 14.

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