Capacitive load driving circuit, capacitive load driving method, and vehicle

Abstract

The application provides a capacitive load driving circuit, a capacitive load driving method and a vehicle. The capacitive load driving circuit comprises a switch, an overcurrent detection module, a delay module and a logic control module. The switch and the capacitive load are connected in series to form a load power supply branch, and the overcurrent detection module realizes overcurrent detection of the load power supply branch. The logic control module is used for sending a trigger signal to the delay module and outputting a first control signal to the switch driving circuit when the overcurrent detection module detects overcurrent, so that the switch driving circuit turns off the switch according to the first control signal. The delay module is used for starting timing after receiving the trigger signal of the logic control module, and sending a timing completion signal to the logic control module when the timing duration reaches a preset delay threshold. The logic control module is also used for outputting a second control signal to the switch driving circuit when receiving the timing completion signal of the delay module, so that the switch driving circuit turns on the switch according to the second control signal.

Description

Technical Field

[0001] This invention relates to the field of vehicle power electronic drive control technology, and in particular to a capacitive load drive circuit, a capacitive load drive method, and a vehicle. Background Technology

[0002] In automotive systems, capacitive loads generally refer to electrical devices and circuit modules that exhibit capacitor charging characteristics upon power-up. The surge current generated by such loads can be up to ten times the steady-state operating current, making it a key performance indicator that must be carefully considered in the design of high-side switch drive circuits.

[0003] The common operating characteristics of capacitive loads in automotive applications are as follows: If the load is a large-capacity capacitive load, the circuit impedance is extremely low at the moment the switch is turned on, and the equivalent series resistance (ESR) of the capacitor is very small. The circuit is approximately short-circuited at the moment the switch is turned on, resulting in a surge current with a very large amplitude. To prevent the switching devices from being damaged by the surge current, traditional high-side switching chips are generally equipped with short-circuit protection and constant current limiting protection mechanisms. The current mainstream implementation method is to configure a dedicated capacitive load drive mode, and its working logic is as follows:

[0004] A dedicated control timing sequence is input to the chip's logic port, enabling the chip to identify the currently driven load as a capacitive load. The chip temporarily disables its short-circuit protection function, switches to current-limiting mode, and clamps the output current to a lower preset threshold to continuously charge the capacitive load. During the charging phase, the chip's output voltage gradually increases from 0V, and a large voltage difference is maintained across the switch for an extended period. This causes the switching device to continuously generate high power consumption throughout the charging cycle until the capacitive load is fully charged and the power-on startup process ends. High power consumption leads to significant temperature rise. To prevent chip overheating and failure, the chip has a built-in over-temperature protection mechanism. When the chip temperature reaches the protection threshold, it executes two processing strategies: first, it directly shuts off the switch, interrupting the charging process; second, it lowers the current-limiting threshold, reducing the output current to decrease power consumption and suppress temperature rise.

[0005] While this driving method can adapt to capacitive load power-on scenarios, it still has significant drawbacks: First, the chip generates a significant temperature rise every time it drives a capacitive load to power on. Long-term, repeated high-temperature operating conditions will greatly reduce the reliability of semiconductor devices and shorten the chip's lifespan. Second, the development and debugging of dedicated control timing is difficult. Variables such as capacitor capacity and ambient temperature will change the chip's heating rate and capacitor charging speed. The duration required to maintain the timing cannot be accurately calibrated, significantly increasing the debugging complexity of the vehicle's electronic control system. Summary of the Invention

[0006] The present invention aims to solve at least one of the technical problems existing in the prior art, and proposes a capacitive load drive circuit, a capacitive load drive method, and a vehicle.

[0007] In a first aspect, embodiments of the present invention provide a capacitive load driving circuit, including: a switch, a switch driving circuit, an overcurrent detection module, a delay module, and a logic control module. The switch is connected in series with the capacitive load to form a load power supply branch. One end of the load power supply branch is connected to the positive terminal of the power supply, and the other end of the load power supply branch is connected to the negative terminal of the power supply.

[0008] The overcurrent detection module is used to collect the current of the load power supply branch and compare the current of the load power supply branch with a preset overcurrent protection threshold to realize overcurrent detection of the load power supply branch.

[0009] The logic control module is used to send a trigger signal to the delay module when the overcurrent detection module detects an overcurrent, and to output a first control signal to the switch drive circuit, so that the switch drive circuit turns off the switch according to the first control signal.

[0010] The delay module is used to start timing after receiving the trigger signal from the logic control module, and to send a timing completion signal to the logic control module when the timing duration reaches a preset delay threshold.

[0011] The logic control module is further configured to output a second control signal to the switch driving circuit when it receives the timing completion signal from the delay module, so that the switch driving circuit turns on the switch according to the second control signal.

[0012] In some embodiments, one end of the switch is connected to the positive terminal of the power supply, the other end of the switch is connected to one end of a capacitive load, and the other end of the capacitive load is connected to the negative terminal of the power supply.

[0013] In some embodiments, the capacitive load drive circuit of the present invention further includes a temperature detection circuit, which is used to detect the temperature of the switch and transmit the detected switch temperature to a logic control module. The logic control module is used to compare the switch temperature with a preset safety warning threshold, and when the switch temperature reaches the preset safety warning threshold, to increase the delay threshold and / or decrease the overcurrent protection threshold.

[0014] In some embodiments, the capacitive load drive circuit of the present invention further includes an over-temperature detection circuit. The over-temperature detection circuit is used to collect the temperature of the switch and compare the switch temperature with a preset safety warning threshold. When the switch temperature reaches the preset safety warning threshold, an over-temperature signal is output to the logic control module. The logic control module is used to increase the delay threshold and / or decrease the overcurrent protection threshold when it receives the over-temperature signal.

[0015] In some embodiments, the over-temperature detection circuit includes a first comparator and a temperature detection circuit for detecting the switch temperature. The first input terminal of the first comparator is connected to the output terminal of the temperature detection circuit, the second input terminal of the first comparator is connected to a first reference voltage, and the output terminal of the first comparator is connected to the first input terminal of the logic control module.

[0016] In some embodiments, the capacitive load drive circuit of the present invention further includes a voltage detection circuit, which is used to detect the voltage across the switch and transmit the detected voltage across the switch to a logic control module. The logic control module is used to compare the voltage across the switch with a preset voltage threshold. When the voltage across the switch reaches the preset voltage threshold, the delay threshold is increased and / or the overcurrent protection threshold is decreased.

[0017] In some embodiments, the capacitive load drive circuit of the present invention further includes an overvoltage detection circuit. The overvoltage detection circuit is used to collect the voltage across the switch and compare the voltage across the switch with a preset voltage threshold. When the voltage across the switch reaches the preset voltage threshold, an overvoltage signal is output to the logic control module. The logic control module is used to increase the delay threshold and / or decrease the overcurrent protection threshold when it receives the overvoltage signal.

[0018] In some embodiments, the overvoltage detection circuit includes a second comparator and a voltage detection circuit for detecting the voltage across the switch. The first input terminal of the second comparator is connected to the output terminal of the voltage detection circuit, the second input terminal of the second comparator is connected to a second reference voltage, and the output terminal of the second comparator is connected to the second input terminal of the logic control module.

[0019] In some embodiments, the switch is a power switch transistor connected in series in the load power supply branch, the control terminal of the power switch transistor is connected to the output terminal of the switch drive circuit, and the input terminal of the switch drive circuit is connected to the output terminal of the logic control module.

[0020] In a second aspect, this disclosure also provides a vehicle comprising: a capacitive load and a capacitive load drive circuit as provided in the first aspect.

[0021] Thirdly, this disclosure also provides a capacitive load driving method, based on the capacitive load driving circuit provided in the first aspect, the capacitive load driving method comprising:

[0022] When an overcurrent is detected in the load power supply branch, the delay module is triggered to start timing and outputs a first control signal to the switch drive circuit, causing the switch drive circuit to turn off the switch according to the first control signal.

[0023] When the delay ends, a second control signal is output to the switch driving circuit, causing the switch driving circuit to turn on the switch according to the second control signal.

[0024] In some embodiments, the capacitive load drive circuit employs the capacitive load drive circuit described in the first aspect.

[0025] The capacitive load driving method further includes:

[0026] When the switch temperature is detected to reach the preset safety warning threshold, the delay threshold is increased or / and the overcurrent protection threshold is decreased.

[0027] In some embodiments, the capacitive load drive circuit employs the capacitive load drive circuit described in the first aspect.

[0028] The capacitive load driving method further includes:

[0029] When the voltage across the switch is detected to reach a preset voltage threshold, the delay threshold is increased or / and the overcurrent protection threshold is decreased.

[0030] The beneficial effects of this invention are as follows:

[0031] This invention employs an intermittent restart charging strategy to charge capacitive loads. When a surge equivalent to a short circuit is detected on the capacitive load, the chip immediately triggers a protection action, and after a preset delay, the switch is turned back on; moreover, the delay between two adjacent protection shutdown and restart operations has an adaptive adjustment characteristic.

[0032] The capacitive load drive circuit proposed in this disclosure eliminates the need for pre-matching the load capacitor capacity, reserving cable redundancy specifications, and controlling the heat dissipation of control devices. It also eliminates the need for higher power switches and large-diameter wiring harnesses, and the need to write custom control timing sequences for uncertain operating conditions, effectively reducing the hardware cost and software development and debugging difficulty of the entire vehicle system. Furthermore, this invention optimizes the driving performance of large-capacity capacitive loads by matching the output current limiting parameters and restart interval through an adaptive dynamic adjustment mechanism. Attached Figure Description

[0033] Figure 1 A schematic diagram of a capacitive load drive circuit provided for related technologies;

[0034] Figure 2 A schematic diagram of the circuit structure of another capacitive load driving circuit provided for related technologies;

[0035] Figure 3 A schematic diagram of the circuit structure of a capacitive load driving circuit provided in an embodiment of this disclosure;

[0036] Figure 4A schematic diagram of the circuit structure of another capacitive load driving circuit provided in the embodiments of this disclosure;

[0037] Figure 5 A flowchart of a capacitive load driving method provided in an embodiment of this disclosure. Detailed Implementation

[0038] To enable those skilled in the art to better understand the technical solutions of the present invention, exemplary embodiments of the present invention are described below in conjunction with the accompanying drawings, including various details of the embodiments of the present invention to aid understanding. These should be considered merely exemplary. Therefore, those skilled in the art should recognize that various changes and modifications can be made to the embodiments described herein without departing from the scope and spirit of the present invention. Similarly, for clarity and brevity, descriptions of well-known functions and structures are omitted in the following description.

[0039] Where there is no conflict, the various embodiments of the present invention and the features thereof may be combined with each other.

[0040] As used herein, the term “and / or” includes any and all combinations of one or more related enumerated entries.

[0041] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the invention. As used herein, the singular forms “a” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will also be understood that when the terms “comprising” and / or “made of” are used in this specification, the presence of the stated feature, integral, step, operation, element, and / or component is specified, but the presence or addition of one or more other features, integrals, steps, operations, elements, components, and / or groups thereof is not excluded. Terms such as “connected” or “linked” are not limited to physical or mechanical connections but can include electrical connections, whether direct or indirect.

[0042] Unless otherwise specified, all terms used herein (including technical and scientific terms) have the same meaning as commonly understood by one of ordinary skill in the art. It will also be understood that terms such as those defined in commonly used dictionaries should be interpreted as having the meaning consistent with their meaning in the context of the relevant art and the invention, and will not be interpreted as having an idealized or overly formal meaning unless expressly so defined herein.

[0043] In the technical solution of this invention, the collection, storage, use, processing, transmission, provision, and disclosure of user personal information all comply with relevant laws and regulations and do not violate public order and good morals. The use of user data in this technical solution follows relevant national laws and regulations (e.g., the "Information Security Technology - Personal Information Security Specification"). For example: appropriate measures are taken for personal information access control; restrictions are imposed on the display of personal information; the purpose of using personal information does not exceed the scope of direct or reasonable association; and explicit identity targeting is eliminated when using personal information to avoid precisely locating a specific individual.

[0044] The operating characteristics of common capacitive loads in automotive applications are as follows: If the load is a large-capacity capacitive load, the circuit impedance is extremely low at the moment the switch is turned on, and the equivalent series resistance (ESR) of the capacitor is very small. The circuit is approximately short-circuited at the moment the switch is turned on, resulting in a surge current with a very large amplitude. To prevent the switching devices from being damaged by the surge current, traditional high-side switching chips are generally equipped with short-circuit protection and constant current limiting protection mechanisms. See [link to relevant documentation]. Figure 1 The current mainstream implementation method is to configure a dedicated capacitive load driver mode, and its working logic is as follows:

[0045] A dedicated control timing sequence is input to the chip's logic port, enabling the chip to identify the currently driven load as a capacitive load. The chip temporarily disables its short-circuit protection function, switches to current-limiting mode, and clamps the output current to a lower preset threshold to continuously charge the capacitive load. During the charging phase, the chip's output voltage gradually increases from 0V, and a large voltage difference is maintained across the switch for an extended period. This causes the switching device to continuously generate high power consumption throughout the charging cycle until the capacitive load is fully charged and the power-on startup process ends. High power consumption leads to significant temperature rise. To prevent chip overheating and failure, the chip has a built-in over-temperature protection mechanism. When the chip temperature reaches the protection threshold, it executes two processing strategies: first, it directly shuts off the switch, interrupting the charging process; second, it lowers the current-limiting threshold, reducing the output current to decrease power consumption and suppress temperature rise.

[0046] While this driving method can adapt to capacitive load power-on scenarios, it still has significant drawbacks: First, the chip generates a significant temperature rise every time it drives a capacitive load to power on. Long-term, repeated high-temperature operating conditions will greatly reduce the reliability of semiconductor devices and shorten the chip's lifespan. Second, the development and debugging of dedicated control timing is difficult. Variables such as capacitor capacity and ambient temperature will change the chip's heating rate and capacitor charging speed. The duration required to maintain the timing cannot be accurately calibrated, significantly increasing the debugging complexity of the vehicle's electronic control system.

[0047] To effectively address the aforementioned problems in the above-mentioned technologies, this disclosure provides corresponding solutions.

[0048] See Figure 2The related technology also discloses a "short circuit-restart-count-latch" protection strategy. Its core principle is as follows: when the chip detects a large current (i.e., a short circuit) in the circuit, it immediately triggers the protection mechanism to quickly shut off the switch. After a preset delay, while counting the number of restarts, the switch is reopened. Each reopening triggers a short circuit, thus restarting the protection mechanism again, and this cycle repeats. When the number of restarts reaches a preset threshold, the chip enters a latching state and no longer actively restarts, thereby protecting itself.

[0049] While this strategy offers relatively reliable protection for the switching chip itself, it is poorly suited for driving large capacitive loads. It has significant drawbacks: First, each system startup requires multiple high-current short-circuit restart processes. The excessive current demand necessitates thicker wiring harnesses to withstand the current surges and also puts considerable stress on the load capacitors, affecting their lifespan. Second, the steady-state operating current is typically much lower than the inrush current during startup. Selecting a higher-specification chip solely to meet startup requirements would significantly increase the system's hardware cost.

[0050] To effectively improve or even completely solve the aforementioned problems in the above-mentioned technologies, this disclosure provides corresponding solutions.

[0051] Figure 3 This is a schematic diagram of the circuit structure of a capacitive load driving circuit provided in an embodiment of this disclosure. Figure 3 As shown, the capacitive load drive circuit includes: a switch, a switch drive circuit, an overcurrent detection module, a delay module, and a logic control module. The switch is connected in series with the capacitive load to form a load power supply branch. One end of the load power supply branch is connected to the positive terminal of the power supply, and the other end of the load power supply branch is connected to the negative terminal of the power supply.

[0052] The overcurrent detection module is used to collect the current of the load power supply branch and compare the current of the load power supply branch with a preset overcurrent protection threshold to realize overcurrent detection of the load power supply branch.

[0053] The logic control module is used to send a trigger signal to the delay module when the overcurrent detection module detects an overcurrent, and to output a first control signal to the switch drive circuit, so that the switch drive circuit turns off the switch according to the first control signal.

[0054] The delay module is used to start timing after receiving the trigger signal from the logic control module, and to send a timing completion signal to the logic control module when the timing duration reaches a preset delay threshold.

[0055] The logic control module is further configured to output a second control signal to the switch driving circuit when it receives the timing completion signal from the delay module, so that the switch driving circuit turns on the switch according to the second control signal.

[0056] This invention employs a continuously restarting charging method to charge capacitive loads. When a capacitive load (short circuit) is detected, the chip activates protection, and after a delay, the switch reopens. The delay between two short circuits is adaptive. The capacitive load driving circuit provided by this disclosure does not require consideration of load capacitance size, wire diameter redundancy, power consumption, or heat generation. It eliminates the need for higher-specification switches and thicker wires, and avoids the hassle of programming with uncertain patterns, reducing system cost and development difficulty. Furthermore, this invention optimizes the driving of capacitive loads by adaptively and dynamically adjusting current and restart time.

[0057] In some embodiments, one end of the switch is connected to the positive terminal of the power supply, the other end of the switch is connected to one end of a capacitive load, and the other end of the capacitive load is connected to the negative terminal of the power supply.

[0058] In some embodiments, the switch is a power switch transistor connected in series in the load power supply branch, the control terminal of the power switch transistor is connected to the output terminal of the switch drive circuit, and the input terminal of the switch drive circuit is connected to the output terminal of the logic control module.

[0059] This disclosure employs a continuously restarting charging method to charge the capacitor. When a capacitive load (short circuit) is detected, the chip activates protection, and after a delay, the switch reopens. The delay between two short circuits is adaptive. Figure 3 In this design, the power switch Q1 is the high-side switch, and the gate control module controls its on / off state. The overcurrent detection module monitors the current flowing through Q1 in real time and immediately notifies the logic control module when an overcurrent condition is detected. The logic control module receives input control signals and feedback signals from various protection circuits, comprehensively determines the appropriate action, and transmits the signal to the gate control module. The delay module generates a delay after receiving the signal from the logic control module, delaying it for a specified period before sending it to the gate control module. This forms the cyclical control strategy for power switch Q1: On—Detection / Judgment—Off—Delay—Re-On.

[0060] The on-resistance of power switch Q1 is Ron, and the output capacitive load is equivalent to Resr and CL in the dashed box. The overcurrent protection threshold is IOC, the total time from power switch Q1 turning on to triggering overcurrent and then turning off is denoted as Ton, the base delay generated by the delay unit is Td, and the power supply voltage is VBAT.

[0061] Ton and Td constitute one restart cycle. During the Ton phase, charge is added to CL, while energy is consumed by the power switch Q1. In each cycle, the charge added to CL is QC, where QC = 0.5 * IOC * Ton.

[0062] Therefore, the voltage rise of OUT in each cycle is VC, where VC = QC / CL. If the starting voltage of the capacitive load is VON_TH, then the required number of restarts N is N = VON_TH / VC. Therefore, the total startup time Tstart is: Tstart = N*(Ton + Td).

[0063] On the other hand, during the restart process, the power consumption of Q1 in each cycle is PQ1.

[0064] PQ1 = 0.5 * IOC * (VBAT - N * VC). Since Q1 only operates for the time Ton in each cycle, and is off for the remaining time Td, it does not consume power. Therefore, the average power consumption PQ1_Avg per cycle is...

[0065] PQ1_Avg = PQ1 / (Ton + Td).

[0066] Given the thermal resistance of the package as θ, the resulting temperature rise is ΔT, where ΔT = PQ1_Avg*θ;

[0067] From the above derivation, it's easy to see that the temperature rise is directly proportional to the overcurrent protection thresholds Ioc, VBAT, and Ton, and inversely proportional to the short-delay threshold Td. This means that controlling the temperature rise protection of the power switch Q1 can be achieved by changing the overcurrent protection thresholds Ioc and Td.

[0068] To optimize the startup time of capacitive loads and achieve the fastest startup speed, this invention employs an initial aggressive strategy with a high overcurrent protection threshold Ioc and a short delay threshold Td. However, the initial overcurrent protection threshold Ioc is relatively high, and the delay interval Td is short. As the number of restarts accumulates, the chip temperature gradually rises, and heat accumulates. To address this heat accumulation, in... Figure 3 Based on this, the capacitive load drive circuit of this embodiment adds a temperature detection circuit to detect the temperature of the switch (such as power switch Q1) in real time.

[0069] When the temperature of the switch (such as power switch Q1) reaches the preset safety warning threshold (preferably, the safety warning threshold is lower than the hard over-temperature shutdown threshold), the logic control module adopts a strategy of increasing the delay threshold Td and / or decreasing the overcurrent protection threshold Ioc (i.e., Td and Ioc are adjusted accordingly) to reduce power consumption.

[0070] Preferably, the logic control module adopts the following strategy: First, it prioritizes lowering the overcurrent protection threshold Ioc to reduce the peak current of a single pulse, directly reducing heat generation at the source. Second, it increases the delay threshold Td to lengthen the shutdown interval, giving the heat sink sufficient time to dissipate heat. Once the temperature drops back to a safe range, the logic control module can gradually revert to the initial aggressive strategy.

[0071] Furthermore, VBAT is constantly changing, and under certain abnormal conditions, it can rise significantly (e.g., during load damping). Since capacitors typically start charging from 0V, a higher VBAT means an increase in the source-drain voltage (Vds) of the switch (e.g., power switch Q1). This implies an increase in power dissipation across the switch (e.g., power switch Q1) with each restart. To address this increased power dissipation, in... Figure 3 Based on this, the capacitive load drive circuit in this embodiment adds a voltage detection circuit to detect the voltage across the switch (such as the voltage across the source and drain of the power switch Q1) in real time (such as the voltage across the source and drain of the power switch Q1). When the voltage across the switch (such as the voltage across the source and drain of the power switch Q1) reaches a preset voltage threshold, the logic control module adopts a strategy of increasing the delay threshold Td and / or decreasing the overcurrent protection threshold Ioc (i.e., Td and Ioc are adjusted accordingly) to reduce power consumption.

[0072] The entire process described above is adaptive. For the system application side, there is no need to consider capacitor size, wire diameter redundancy, pattern writing and adaptability for different situations, or heat generation. At the same time, there is no need to use high-specification chips to increase system costs, which greatly reduces the difficulty of system development.

[0073] After temperature detection, the temperature needs to be compared with a preset safety warning threshold. This can be achieved using a hardware comparator or a logic control module. Similarly, after voltage (Vds) detection, the voltage needs to be compared with a preset voltage threshold. This can also be achieved using a hardware comparator or a logic control module.

[0074] If both temperature and voltage comparisons are implemented using comparators, then once the temperature reaches a preset safety warning threshold or the voltage reaches a preset voltage threshold, a logic signal is output to the logic control module, which then controls Ioc and Td to make corresponding level changes.

[0075] Moreover, both the temperature detection circuit and the voltage detection circuit can send the collected data to the ADC module, which can then detect temperature and VDS changes more precisely.

[0076] In some embodiments, the present invention replaces the binary logic of "only judging whether the threshold is exceeded" with multi-level graded adjustment. For example, the logic control module can obtain or calculate a new overcurrent protection threshold Ioc or delay threshold Td in real time based on the detected temperature. One embodiment is as follows: the logic control module internally stores a temperature-current (Ioc) mapping table and / or a temperature-time (Td) mapping table. When the temperature corresponding to the ADC sampling value is in the T0~T1 range, the preset initial high threshold Ioc is maintained; when the temperature rises by ΔT (e.g., 5℃), the logic control module lowers the overcurrent protection threshold Ioc by one current level (a total of N levels); when the temperature falls back, it is gradually raised to restore the current. Simultaneously, the delay time Td also increases proportionally with the temperature increase, achieving stepless smooth heat dissipation.

[0077] Vds directly reflects the voltage stress currently borne by the power transistor, and its instantaneous absolute value is obtained through the ADC.

[0078] For example, the logic module reads the value of Vds in real time via the ADC. When Vds is detected to exceed the preset voltage threshold, the logic control module can look up a table in real time based on Vds to obtain or calculate a new overcurrent protection threshold Ioc or delay threshold Td.

[0079] This invention allows for the adjustment of Ioc or Td to have more levels as needed, in order to achieve more precise control.

[0080] Only one temperature warning range can be set between the safety warning threshold and the hard over-temperature shutdown threshold. This temperature warning range corresponds to a change in Td level and an change in Ioc level.

[0081] Of course, multiple temperature warning intervals are set between the safety warning threshold and the hard over-temperature shutdown threshold. The logic control module can use a piecewise linear mapping of "temperature-level" (based on an experimentally calibrated mapping table). For different temperature warning intervals, corresponding Td level change and Ioc level change are set. The level step value can be obtained through simulation combined with actual operating conditions.

[0082] In some embodiments, Td / Ioc is only allowed to be adjusted upwards by one level after the temperature drops back to the previous temperature warning range and the hysteresis exceeds a preset hysteresis threshold and remains stable for a set time (500ms). For example, the warning threshold is 85℃. When the temperature rises to 85℃, derating is performed; however, Td / Ioc is only allowed to be adjusted upwards by one level after the temperature drops back to 82℃ (hysteresis 3℃) and remains stable for more than 500ms. Each temperature warning range in this invention can also be independently configured with a dedicated hysteresis threshold and stabilization delay to avoid jumps across ranges.

[0083] If the temperature continues to rise and reaches the hard over-temperature shutdown threshold after executing the maximum level of Ioc derating + Td increase, the logic control module must immediately bypass all derating strategies and execute hard PWM shutdown until the temperature recovers to the safe range (the safe range can be set as needed, such as 60%~70% of the safety warning threshold) before allowing software restart.

[0084] In some embodiments, see Figure 4 The capacitive load drive circuit of the present invention further includes a temperature detection circuit, which is used to detect the temperature of the switch and transmit the detected switch temperature to the logic control module. The logic control module is used to compare the switch temperature with a preset safety warning threshold. When the switch temperature reaches the preset safety warning threshold, the delay threshold is increased and / or the overcurrent protection threshold is decreased.

[0085] In some embodiments, the capacitive load drive circuit of the present invention further includes an over-temperature detection circuit. The over-temperature detection circuit is used to collect the temperature of the switch and compare the switch temperature with a preset safety warning threshold. When the switch temperature reaches the preset safety warning threshold, an over-temperature signal is output to the logic control module. The logic control module is used to increase the delay threshold and / or decrease the overcurrent protection threshold when it receives the over-temperature signal.

[0086] In some embodiments, the over-temperature detection circuit includes a first comparator and a temperature detection circuit for detecting the switch temperature. The first input terminal of the first comparator is connected to the output terminal of the temperature detection circuit, the second input terminal of the first comparator is connected to a first reference voltage, and the output terminal of the first comparator is connected to the first input terminal of the logic control module.

[0087] In some embodiments, see Figure 4 The capacitive load drive circuit of the present invention further includes a voltage detection circuit, which is used to detect the voltage across the switch and transmit the detected voltage across the switch to the logic control module. The logic control module is used to compare the voltage across the switch with a preset voltage threshold. When the voltage across the switch reaches the preset voltage threshold, the delay threshold is increased and / or the overcurrent protection threshold is decreased.

[0088] In some embodiments, the capacitive load drive circuit of the present invention further includes an overvoltage detection circuit. The overvoltage detection circuit is used to collect the voltage across the switch and compare the voltage across the switch with a preset voltage threshold. When the voltage across the switch reaches the preset voltage threshold, an overvoltage signal is output to the logic control module. The logic control module is used to increase the delay threshold and / or decrease the overcurrent protection threshold when it receives the overvoltage signal.

[0089] In some embodiments, the overvoltage detection circuit includes a second comparator and a voltage detection circuit for detecting the voltage across the switch. The first input terminal of the second comparator is connected to the output terminal of the voltage detection circuit, the second input terminal of the second comparator is connected to a second reference voltage, and the output terminal of the second comparator is connected to the second input terminal of the logic control module.

[0090] This invention avoids both the "forced restart" and "final lock-up" of related technologies, as well as the heat generation drawbacks of "long-term current limiting and high power consumption" in related technologies. The core solution of this invention is "pulse-type intermittent charging," which cleverly decouples "electrical stress" and "thermal stress."

[0091] Addressing "Electrical Stress" (Protecting the Switch from Damage by Instantaneous High Current): This invention does not resist surge current, but rather adapts to and utilizes the overcurrent protection (OCP) mechanism. Upon detecting a short circuit / overcurrent, the switch is immediately shut off within a very short time. This ensures that each conduction pulse is extremely narrow, and the current is cut off as soon as it reaches the threshold Ioc, avoiding the impact of continuous high current on the wiring harness and capacitor ESR. Therefore, there is no need to thicken the wiring harness or select a higher-specification switching chip.

[0092] Addressing "thermal stress" (preventing switch burnout due to accumulated overheating): This invention utilizes an extremely low duty cycle for heat dissipation. While the switch does generate heat during the Ton period, the current and power consumption are zero during the long off-time Td, allowing ample time for the heat to dissipate through the package's thermal resistance. As long as Td is designed to be long enough so that the temperature rise corresponding to the average power consumption is below the chip's over-temperature protection threshold, the switch is safe.

[0093] Although only a small amount of power is charged each time, through countless cycles of restarting, the charge accumulates on the capacitor like "dripping water wears away a stone," and the output voltage gradually increases step by step until it reaches the load start-up threshold, thus completing the start-up process.

[0094] The capacitive load driving circuit provided by this disclosure eliminates the need for higher-specification switches and thicker wire gauges, and avoids the hassle of programming with uncertain patterns. It employs an intelligent, continuously restarting charging method to charge the capacitor. When a capacitive load (short circuit) is detected, the chip activates protection, and after a delay, reopens the switch. The delay between two short circuits is adaptive. This invention does not require consideration of load capacitance size, wire gauge redundancy, power consumption, or heat generation, reducing system cost and development difficulty. This invention optimizes the driving of capacitive loads by adaptively and dynamically adjusting current and restart time (the restart delay Td and the current limiting Ioc are dynamically adjustable).

[0095] Based on the same inventive concept, this disclosure also provides a vehicle, which includes a capacitive load and a capacitive load drive circuit provided in any of the preceding embodiments. For a description of the capacitive load drive circuit, please refer to the content in the preceding embodiments, and it will not be repeated here.

[0096] Capacitive loads can be, but are not limited to:

[0097] Incandescent and xenon lamps in the vehicle's electrical system (the cold filament has extremely low resistance, and exhibits surge characteristics similar to capacitor charging when energized).

[0098] Various electronic control units (ECUs), such as engine controllers, transmission controllers, body domain controllers, and chassis domain controllers, generally have large-capacity electrolytic capacitors or ceramic capacitors at their internal power input terminals for filtering and voltage regulation.

[0099] Based on the same inventive concept, this disclosure also provides a capacitive load driving method. Figure 5 A flowchart illustrating a capacitive load driving method provided in an embodiment of this disclosure. Figure 5 As shown, this capacitive load driving method is based on the capacitive load driving circuit provided in the previous embodiment. For a detailed description of the capacitive load driving circuit, please refer to the content in the previous embodiment. The capacitive load driving method includes:

[0100] Step S1: When an overcurrent is detected in the load power supply branch, the delay module is triggered to start timing and outputs a first control signal to the switch drive circuit, so that the switch drive circuit turns off the switch according to the first control signal.

[0101] Step S2: When the delay ends, a second control signal is output to the switch driving circuit, so that the switch driving circuit turns on the switch according to the second control signal.

[0102] Based on the same inventive concept, this disclosure also provides a capacitive load driving method. This capacitive load driving method is based on the capacitive load driving circuit provided in the preceding embodiments. For a detailed description of the capacitive load driving circuit, please refer to the content in the preceding embodiments. The capacitive load driving method includes:

[0103] When an overcurrent is detected in the load power supply branch, the delay module is triggered to start timing and outputs a first control signal to the switch drive circuit, causing the switch drive circuit to turn off the switch according to the first control signal.

[0104] When the delay ends, a second control signal is output to the switch driving circuit, causing the switch driving circuit to turn on the switch according to the second control signal.

[0105] When the switch temperature is detected to reach the preset safety warning threshold, the delay threshold is increased or / and the overcurrent protection threshold is decreased.

[0106] Based on the same inventive concept, this disclosure also provides a capacitive load driving method. This capacitive load driving method is based on the capacitive load driving circuit provided in the preceding embodiments. For a detailed description of the capacitive load driving circuit, please refer to the content in the preceding embodiments. The capacitive load driving method includes:

[0107] When an overcurrent is detected in the load power supply branch, the delay module is triggered to start timing and outputs a first control signal to the switch drive circuit, causing the switch drive circuit to turn off the switch according to the first control signal.

[0108] When the delay ends, a second control signal is output to the switch driving circuit, causing the switch driving circuit to turn on the switch according to the second control signal.

[0109] When the voltage across the switch is detected to reach a preset voltage threshold, the delay threshold is increased or / and the overcurrent protection threshold is decreased.

[0110] Based on the same inventive concept, this disclosure also provides a capacitive load driving method. This capacitive load driving method is based on the capacitive load driving circuit provided in the preceding embodiments. For a detailed description of the capacitive load driving circuit, please refer to the content in the preceding embodiments. The capacitive load driving method includes:

[0111] When an overcurrent is detected in the load power supply branch, the delay module is triggered to start timing and outputs a first control signal to the switch drive circuit, causing the switch drive circuit to turn off the switch according to the first control signal.

[0112] When the delay ends, a second control signal is output to the switch driving circuit, causing the switch driving circuit to turn on the switch according to the second control signal.

[0113] When the switch temperature is detected to reach the preset safety warning threshold, the delay threshold is increased or / and the overcurrent protection threshold is decreased.

[0114] When the voltage across the switch is detected to reach a preset voltage threshold, the delay threshold is increased or / and the overcurrent protection threshold is decreased.

[0115] To optimize the startup time of capacitive loads and achieve the fastest startup speed, this invention employs an initial aggressive strategy with a high overcurrent protection threshold Ioc and a short delay threshold Td. However, the initial overcurrent protection threshold Ioc is relatively high, and the delay interval Td is short. As the number of restarts accumulates, the chip temperature gradually rises, and heat accumulates. To address this heat accumulation, in... Figure 3Based on this, the capacitive load drive circuit of this embodiment adds a temperature detection circuit to detect the temperature of the switch (such as power switch Q1) in real time.

[0116] When the temperature of the switch (such as power switch Q1) reaches the preset safety warning threshold (preferably, the safety warning threshold is lower than the hard over-temperature shutdown threshold), the logic control module adopts a strategy of increasing the delay threshold Td and / or decreasing the overcurrent protection threshold Ioc (i.e., making corresponding changes to Td and Ioc, the amount of change can be obtained from experimental calibration) to reduce power consumption.

[0117] Preferably, the logic control module adopts the following strategy: First, it prioritizes lowering the overcurrent protection threshold Ioc to reduce the peak current of a single pulse, directly reducing heat generation at the source. Second, it increases the delay threshold Td to lengthen the shutdown interval, giving the heat sink sufficient time to dissipate heat. Once the temperature drops back to a safe range, the logic control module can gradually revert to the initial aggressive strategy.

[0118] Furthermore, VBAT is constantly changing, and under certain abnormal conditions, it can rise significantly (e.g., during load damping). Since capacitors typically start charging from 0V, a higher VBAT means an increase in the source-drain voltage (Vds) of the switch (e.g., power switch Q1). This implies an increase in power dissipation across the switch (e.g., power switch Q1) with each restart. To address this increased power dissipation, in... Figure 3 Based on this, the capacitive load drive circuit in this embodiment adds a voltage detection circuit to detect the voltage across the switch (such as the voltage across the source and drain of the power switch Q1) in real time (such as the voltage across the source and drain of the power switch Q1). When the voltage across the switch (such as the voltage across the source and drain of the power switch Q1) reaches a preset voltage threshold, the logic control module adopts a strategy of increasing the delay threshold Td and / or decreasing the overcurrent protection threshold Ioc (i.e., making corresponding adjustments to Td and Ioc) to reduce power consumption.

[0119] The entire process described above is adaptive. For the system application side, there is no need to consider capacitor size, wire diameter redundancy, pattern writing and adaptability for different situations, or heat generation. At the same time, there is no need to use high-specification chips to increase system costs, which greatly reduces the difficulty of system development.

[0120] After temperature detection, the temperature needs to be compared with a preset safety warning threshold. This can be achieved using a hardware comparator or a logic control module. Similarly, after detecting the Vds voltage, the voltage needs to be compared with a preset voltage threshold. This can also be achieved using a hardware comparator or a logic control module.

[0121] If both temperature and voltage comparisons are implemented using comparators, then once the temperature reaches a preset safety warning threshold or the voltage reaches a preset voltage threshold, a logic signal is output to the logic control module, which then controls Ioc and Td to make corresponding level changes.

[0122] Moreover, both the temperature detection circuit and the voltage detection circuit can send the collected data to the ADC module, which can then detect temperature and VDS changes more precisely.

[0123] In some embodiments, the present invention may also change the binary logic of "only judging whether the threshold is exceeded" to multi-level graded adjustment of Ioc and Td.

[0124] In some embodiments, when the switch temperature is detected to reach a preset safety warning threshold, the delay threshold is increased and / or the overcurrent protection threshold is decreased. Specifically, when the switch temperature is detected to reach the preset safety warning threshold, a new overcurrent protection threshold Ioc or a delay threshold Td is obtained based on the detected switch temperature, wherein the new overcurrent protection threshold is less than the preset initial overcurrent protection threshold, and the new delay threshold is greater than the preset initial delay threshold.

[0125] In some embodiments, a new overcurrent protection threshold Ioc or delay threshold Td is obtained based on the detected switching temperature. Specifically, this includes: obtaining or calculating the new overcurrent protection threshold Ioc or delay threshold Td in real time by looking up a table based on the detected switching temperature. For example, in one embodiment, the logic control module internally stores a temperature-current (Ioc) mapping table and / or a temperature-time (Td) mapping table. When the temperature corresponding to the ADC sampling value is in the T0~T1 range, a preset initial high threshold Ioc is maintained; when the temperature rises by ΔT (e.g., 5°C), the logic control module lowers the overcurrent protection threshold Ioc by one current level (a total of N levels); when the temperature falls back, it is gradually raised to restore the current. Simultaneously, the delay time Td also increases proportionally with the temperature increase, achieving stepless smooth heat dissipation.

[0126] Vds directly reflects the voltage stress currently borne by the power transistor, and its instantaneous absolute value is obtained through the ADC.

[0127] In some embodiments, when the voltage across the switch is detected to reach a preset voltage threshold, the delay threshold is increased and / or the overcurrent protection threshold is decreased. Specifically, when the voltage across the switch is detected to reach a preset voltage threshold, a new overcurrent protection threshold Ioc or a delay threshold Td is obtained based on the detected voltage across the switch, wherein the new overcurrent protection threshold is less than the preset initial overcurrent protection threshold, and the new delay threshold is greater than the preset initial delay threshold.

[0128] For example, the logic module reads the value of Vds in real time via the ADC. When Vds is detected to exceed the preset voltage threshold, the logic control module can look up a table in real time based on Vds to obtain or calculate a new overcurrent protection threshold Ioc or delay threshold Td.

[0129] In some embodiments, a new overcurrent protection threshold Ioc or delay threshold Td is obtained based on the detected voltage across the switch. Specifically, this includes obtaining or calculating the new overcurrent protection threshold Ioc or delay threshold Td by looking up a table in real time based on the detected voltage across the switch.

[0130] This invention allows for the adjustment of Ioc or Td to have more levels as needed, in order to achieve more precise control.

[0131] The capacitive load driving method disclosed herein eliminates the need for higher-specification switches and thicker wire gauges, and avoids the hassle of programming with uncertain patterns. It employs an intelligent, continuously restarting charging method to charge the capacitor. When a capacitive load (short circuit) is detected, the chip activates protection, and after a delay, the switch reopens. The delay between two short circuits is adaptive. This invention does not require consideration of load capacitance size, wire gauge redundancy, power consumption, or heat generation, reducing system cost and development difficulty. This invention optimizes the driving of capacitive loads by adaptively and dynamically adjusting current and restart time (the restart delay Td and the current limiting Ioc are dynamically adjustable).

[0132] Example embodiments have been disclosed herein, and while specific terminology has been used, it is for illustrative purposes only and should be construed as such, and is not intended to be limiting. In some instances, it will be apparent to those skilled in the art that features, characteristics, and / or elements described in conjunction with particular embodiments may be used alone, or in combination with features, characteristics, and / or elements described in conjunction with other embodiments, unless otherwise expressly indicated. Therefore, those skilled in the art will understand that various changes in form and detail may be made without departing from the scope of the invention as set forth in the appended claims.

Claims

1. A capacitive load drive circuit, characterized in that, include: The system includes a switch, a switch drive circuit, an overcurrent detection module, a delay module, and a logic control module. The switch is connected in series with a capacitive load to form a load power supply branch. One end of the load power supply branch is connected to the positive terminal of the power supply, and the other end of the load power supply branch is connected to the negative terminal of the power supply. The overcurrent detection module is used to collect the current of the load power supply branch and compare the current of the load power supply branch with a preset overcurrent protection threshold to realize overcurrent detection of the load power supply branch. The logic control module is used to send a trigger signal to the delay module when the overcurrent detection module detects an overcurrent, and to output a first control signal to the switch drive circuit, so that the switch drive circuit turns off the switch according to the first control signal. The delay module is used to start timing after receiving the trigger signal from the logic control module, and to send a timing completion signal to the logic control module when the timing duration reaches a preset delay threshold. The logic control module is further configured to output a second control signal to the switch driving circuit when it receives the timing completion signal from the delay module, so that the switch driving circuit turns on the switch according to the second control signal.

2. The capacitive load drive circuit according to claim 1, characterized in that: One end of the switch is connected to the positive terminal of the power supply, and the other end of the switch is connected to one end of the capacitive load, while the other end of the capacitive load is connected to the negative terminal of the power supply.

3. The capacitive load drive circuit according to claim 1, characterized in that: It also includes a temperature detection circuit, which is used to detect the temperature of the switch and transmit the detected switch temperature to the logic control module. The logic control module is used to compare the switch temperature with a preset safety warning threshold. When the switch temperature reaches the preset safety warning threshold, the delay threshold is increased and / or the overcurrent protection threshold is decreased.

4. The capacitive load drive circuit according to claim 1, characterized in that: It also includes an over-temperature detection circuit, which is used to collect the temperature of the switch and compare the switch temperature with a preset safety warning threshold. When the switch temperature reaches the preset safety warning threshold, it outputs an over-temperature signal to the logic control module. The logic control module is used to increase the delay threshold and / or decrease the overcurrent protection threshold when it receives the over-temperature signal.

5. The capacitive load drive circuit according to claim 4, characterized in that: The over-temperature detection circuit includes a first comparator and a temperature detection circuit for detecting the switch temperature. The first input terminal of the first comparator is connected to the output terminal of the temperature detection circuit, the second input terminal of the first comparator is connected to a first reference voltage, and the output terminal of the first comparator is connected to the first input terminal of the logic control module.

6. The capacitive load drive circuit according to claim 1, characterized in that: It also includes a voltage detection circuit, which is used to detect the voltage across the switch and transmit the detected voltage across the switch to the logic control module. The logic control module is used to compare the voltage across the switch with a preset voltage threshold. When the voltage across the switch reaches the preset voltage threshold, the delay threshold is increased and / or the overcurrent protection threshold is decreased.

7. The capacitive load drive circuit according to claim 1, characterized in that: It also includes an overvoltage detection circuit, which is used to collect the voltage across the switch and compare the voltage across the switch with a preset voltage threshold. When the voltage across the switch reaches the preset voltage threshold, it outputs an overvoltage signal to the logic control module. The logic control module is used to increase the delay threshold and / or decrease the overcurrent protection threshold when it receives the overvoltage signal.

8. The capacitive load drive circuit according to claim 7, characterized in that: The overvoltage detection circuit includes a second comparator and a voltage detection circuit for detecting the voltage across the two ends of the switch. The first input terminal of the second comparator is connected to the output terminal of the voltage detection circuit, the second input terminal of the second comparator is connected to a second reference voltage, and the output terminal of the second comparator is connected to the second input terminal of the logic control module.

9. The capacitive load drive circuit according to any one of claims 1 to 8, characterized in that: The switch is a power switch transistor connected in series in the load power supply branch. The control terminal of the power switch transistor is connected to the output terminal of the switch drive circuit, and the input terminal of the switch drive circuit is connected to the output terminal of the logic control module.

10. A vehicle, characterized in that, include: A capacitive load and a capacitive load drive circuit as described in any one of claims 1 to 9.

11. A capacitive load driving method, characterized in that, Based on the capacitive load driving circuit according to any one of claims 1 to 9, the capacitive load driving method includes: When an overcurrent is detected in the load power supply branch, the delay module is triggered to start timing and outputs a first control signal to the switch drive circuit, causing the switch drive circuit to turn off the switch according to the first control signal. When the delay ends, a second control signal is output to the switch driving circuit, causing the switch driving circuit to turn on the switch according to the second control signal.

12. The capacitive load driving method according to claim 11, characterized in that, The capacitive load drive circuit adopts any one of the capacitive load drive circuits described in claims 3 to 5; The capacitive load driving method further includes: When the switch temperature is detected to reach the preset safety warning threshold, the delay threshold is increased or / and the overcurrent protection threshold is decreased.

13. The capacitive load driving method according to claim 11, characterized in that, The capacitive load drive circuit adopts any one of the capacitive load drive circuits described in claims 6 to 8; The capacitive load driving method further includes: When the voltage across the switch is detected to reach a preset voltage threshold, the delay threshold is increased or / and the overcurrent protection threshold is decreased.

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