Wide voltage input adaptive voltage regulation driving method and system for direct current contactor

Abstract

The application provides a wide voltage input adaptive voltage stabilizing driving method and system for a direct current contactor, and particularly relates to the technical field of power electronic power conversion. The method determines the real-time temperature of a coil of the direct current contactor by monitoring the load current and input voltage of the coil in real time, and calculates the upper limit of a dynamic safety voltage according to the real-time temperature; at the same time, the voltage change rate of the input voltage per unit time is calculated, and compared with a preset threshold to determine a transient pulse threat. Based on the determination result, a driving mode is selected: when the transient pulse threat exists, a voltage stabilizing current limiting mode is selected; when there is no threat and the input voltage is higher than the upper limit of the dynamic safety voltage, a step-down regulation mode is selected; and when the input voltage is lower than or equal to the upper limit of the dynamic safety voltage, a pass-through mode is selected. The selected mode is executed to generate and output a driving signal. The method solves the problem that the prior art cannot effectively distinguish and cooperatively respond to overvoltage stresses of different natures, and improves the intelligent response and protection capability of a driving circuit.

Description

Technical Field

[0001] This invention relates to the field of power electronic power conversion technology, and more specifically, to a wide voltage input adaptive voltage regulation drive method and system for DC contactors. Background Technology

[0002] In the field of industrial control, DC contactors are key actuators, and the reliability of their drive circuits directly affects the safety and stability of the entire system. With the increasing complexity of industrial applications and the diversification of power supply environments, the output of the rectifier modules powering them exhibits a wide range of fluctuations (e.g., 40V to 80V). This requires the drive circuit to have wide voltage input adaptability. However, due to their physical characteristics, DC contactor coils have strict safety window requirements for drive voltage (e.g., a rated 48V contactor allows fluctuations of 40.8V-52.8V). Exceeding this range, especially under overvoltage conditions, will directly lead to coil overheating, accelerated insulation aging, and even burnout, posing a serious safety hazard. Therefore, ensuring that the drive voltage always adapts to the contactor's safety requirements under a wide range of input voltages, which may include transient high-voltage pulses, has become a core challenge in the industry.

[0003] To address these challenges, existing technical solutions mainly fall into two categories. One category uses a driver circuit with a fixed output voltage. While simple in structure, it is completely unsuitable for wide voltage inputs, limiting its application range. The other, more advanced category, introduces a voltage judgment and regulation module. This module implements voltage reduction and regulation when the input voltage exceeds a certain fixed threshold (e.g., 52.8V), and direct output within a safe voltage range. While this type of solution addresses the fundamental issue of wide voltage adaptability to some extent, its core judgment mechanism relies on a single, static voltage threshold. This static mechanism cannot effectively distinguish between continuous, slight overvoltage and instantaneous high-voltage pulses in the input voltage. This results in a simplistic control strategy, lacking intelligent identification and differentiated response capabilities for different overvoltage stress characteristics, and creating blind spots in handling instantaneous pulse impacts and optimizing long-term thermal life management.

[0004] In summary, the technical problem of how to solve the problem that the existing DC contactor wide-voltage drive circuit, which adopts a static threshold determination mechanism, cannot effectively distinguish and coordinate the response to two different types of overvoltage stress: instantaneous high-voltage pulses and long-term mild overvoltages, is an urgent problem to be solved. Summary of the Invention

[0005] The main objective of this invention is to provide a wide-voltage input adaptive voltage regulation drive method and system for DC contactors, so as to at least solve the technical problem that existing wide-voltage drive circuits for DC contactors cannot effectively distinguish and coordinate the response to two different types of overvoltage stresses, namely instantaneous high-voltage pulses and long-term mild overvoltage, due to the use of a static threshold determination mechanism. This significantly improves the intelligent response and protection capability of the drive circuit under complex voltage stress.

[0006] To achieve the above objectives, the present invention provides a wide voltage input adaptive voltage regulation drive method and system for DC contactors.

[0007] In a first aspect, the present invention provides a wide-voltage input adaptive regulated driving method for a DC contactor, the method comprising:

[0008] The load current and input voltage of the DC contactor coil are monitored in real time, and the real-time temperature of the DC contactor coil is determined based on the load current. The dynamic safety voltage limit is calculated based on the real-time temperature and the preset maximum allowable operating temperature of the coil.

[0009] The voltage change rate per unit time is calculated based on the input voltage, and the voltage change rate is compared with a preset abrupt change threshold to determine whether there is a transient pulse threat.

[0010] The driving mode is selected based on the following judgment rules:

[0011] a) If the instantaneous pulse threat is determined to exist, select the voltage regulation and current limiting mode;

[0012] b) If no transient pulse threat is detected and the input voltage is higher than the dynamic safety voltage limit, then select the buck regulation mode;

[0013] c) If the input voltage is lower than or equal to the dynamic safety voltage limit, then select the pass-through mode;

[0014] The selected drive mode is executed to generate and output a drive signal to the DC contactor.

[0015] Specifically, the real-time monitoring of the load current and input voltage of the DC contactor coil, and the determination of the real-time temperature of the DC contactor coil based on the load current, includes:

[0016] Obtain the thermal model parameters of the DC contactor coil and the current load current;

[0017] Based on the thermal model parameters and the load current, the real-time temperature of the DC contactor coil is calculated using the thermodynamic equation of state.

[0018] Specifically, the step of calculating the dynamic safety voltage upper limit based on the real-time temperature and the preset maximum allowable operating temperature of the coil includes:

[0019] Calculate the temperature difference between the real-time temperature and the maximum allowable operating temperature of the coil;

[0020] Based on the temperature difference, the upper limit of the dynamic safety voltage is calculated using a linear compensation function.

[0021] Specifically, the step of calculating the voltage change rate per unit time based on the input voltage and comparing the voltage change rate with a preset abrupt change threshold to determine whether a transient pulse threat exists includes:

[0022] The input voltage obtained by continuous sampling is differentially calculated to obtain the rate of change of voltage per unit time;

[0023] The absolute value of the voltage change rate is compared with the abrupt change threshold;

[0024] If the absolute value is greater than the threshold for abrupt changes, then the existence of the instantaneous pulse threat is determined.

[0025] Specifically, the step of selecting the voltage regulation and current limiting mode if the instantaneous pulse threat is determined to exist includes:

[0026] A voltage regulation control signal is generated to start the DC-DC buck converter, limiting the voltage output to the DC contactor coil to a range not exceeding the dynamic safety voltage limit.

[0027] A current-limiting control signal is generated to limit the drive current of the DC contactor coil within a preset safe current threshold.

[0028] Specifically, the step of selecting buck regulation mode if no instantaneous pulse threat is determined and the input voltage is higher than the dynamic safety voltage upper limit includes:

[0029] Generate a buck enable signal to start the DC-DC buck converter;

[0030] The target output voltage of the DC-DC buck converter is set to the dynamic safety voltage upper limit.

[0031] Specifically, the step of selecting the pass-through mode if the input voltage is lower than or equal to the dynamic safety voltage upper limit includes:

[0032] Generate a direct-through control signal to control the switching device to directly couple the input voltage to the DC contactor coil;

[0033] Simultaneously, a disable signal is generated to shut down the DC-DC buck converter.

[0034] In a second aspect, the present invention provides a wide voltage input adaptive regulated drive system for a DC contactor, the drive system applying the drive method described in the first aspect, the drive system comprising:

[0035] The monitoring and calculation module is used to monitor the load current and input voltage of the DC contactor coil in real time, determine the real-time temperature of the DC contactor coil based on the load current, and calculate the dynamic safety voltage limit based on the real-time temperature and the preset maximum allowable operating temperature of the coil.

[0036] The threat determination module is connected to the monitoring and calculation module. The threat determination module is used to calculate the voltage change rate per unit time based on the input voltage and compare the voltage change rate with a preset abrupt change threshold to determine whether there is a transient pulse threat.

[0037] The mode selection module is connected to the monitoring and calculation module and the threat determination module. The mode selection module is used to select the driving mode based on the determination result: if the instantaneous pulse threat is determined to exist, the voltage regulation and current limiting mode is selected; if the instantaneous pulse threat is not determined to exist and the input voltage is higher than the dynamic safety voltage limit, the buck regulation mode is selected; if the input voltage is lower than or equal to the dynamic safety voltage limit, the pass-through mode is selected.

[0038] A drive execution module is connected to the mode selection module. The drive execution module is used to execute the selected drive mode to generate and output a drive signal to the DC contactor.

[0039] Specifically, the monitoring and calculation module includes:

[0040] The parameter acquisition unit is used to acquire the thermal model parameters of the DC contactor coil and the current load current.

[0041] A temperature calculation unit is connected to the parameter acquisition unit. The temperature calculation unit is used to calculate the real-time temperature of the DC contactor coil based on the thermal model parameters and the load current using the thermodynamic equation of state.

[0042] Specifically, the monitoring and calculation module also includes:

[0043] The difference calculation unit is used to calculate the temperature difference between the real-time temperature and the maximum allowable operating temperature of the coil.

[0044] A dynamic threshold calculation unit is connected to the difference calculation unit. The dynamic threshold calculation unit is used to calculate the dynamic safety voltage upper limit based on the temperature difference using a linear compensation function.

[0045] This application provides a wide-voltage input adaptive voltage regulation drive method and system for DC contactors. The method monitors the load current and input voltage of the DC contactor coil in real time, determines the real-time coil temperature based on the load current, and then calculates the dynamic safe voltage upper limit. Simultaneously, it calculates the rate of change of the input voltage per unit time and compares it with a preset abrupt change threshold to determine if a transient pulse threat exists. Based on the determination result, a drive mode is selected: a voltage regulation and current limiting mode is activated when a transient pulse threat exists; a buck regulation mode is used when there is no such threat and the input voltage is higher than the dynamic safe voltage upper limit; and a direct-through mode is selected when the input voltage is lower than or equal to the upper limit. After executing the selected mode, a drive signal is generated and output. This method effectively solves the problem of existing technologies' difficulty in distinguishing and coordinating responses to overvoltage stresses of different natures, improving the intelligent response and protection performance of the drive circuit. Attached Figure Description

[0046] The accompanying drawings, which form part of this application, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0047] Figure 1 A flowchart illustrating the wide voltage input adaptive regulated driving method for DC contactors provided in this application;

[0048] Figure 2 A connection diagram of a wide voltage input adaptive regulated drive system for DC contactors provided in this application.

[0049] The accompanying drawings illustrate specific embodiments of this application, which will be described in more detail below. These drawings and descriptions are not intended to limit the scope of the concept in any way, but rather to illustrate the concept of this application to those skilled in the art through reference to particular embodiments. Detailed Implementation

[0050] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0051] The terms "first," "second," "third," "fourth," etc. (if present) in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein.

[0052] In this invention, the terms "exemplary" or "for example" are used to indicate examples, illustrations, or descriptions. Any embodiment or design described as "exemplary" or "for example" in this application should not be construed as being more preferred or advantageous than other embodiments or designs. Specifically, the use of terms such as "exemplary" or "for example" is intended to present the relevant concepts in a concrete manner.

[0053] This application provides a wide-voltage input adaptive voltage regulation drive method and system for DC contactors. This drive method is designed for wide-voltage input scenarios of DC contactors, and monitors the coil load current and input voltage in real time. The real-time coil temperature is determined from the load current, and a dynamic safe voltage upper limit is calculated by combining this with a preset maximum allowable operating temperature. The rate of change of the input voltage per unit time is calculated and compared with a preset threshold to determine instantaneous pulse threats. Based on the determination result, a voltage regulation and current limiting mode is selected if a threat exists; a buck regulation mode is selected if there is no threat and the voltage is high; and a direct-through mode is selected if the voltage is low or equal to the upper limit. The execution mode generates and outputs a drive signal, improving the circuit's intelligent response and protection capabilities.

[0054] The technical solution of this application and how the technical solution of this application solves the above-mentioned technical problems are described in detail below with specific embodiments. These specific embodiments can be combined with each other, and the same or similar concepts or processes may not be described again in some embodiments. The embodiments of this application will now be described with reference to the accompanying drawings.

[0055] Figure 1 A flowchart illustrating the wide-voltage input adaptive regulated driving method for DC contactors provided in this application is shown below. Figure 1 As shown, this embodiment provides a wide voltage input adaptive regulated driving method for DC contactors, which includes:

[0056] S101: Monitor the load current and input voltage of the DC contactor coil in real time, determine the real-time temperature of the DC contactor coil based on the load current, and calculate the dynamic safety voltage limit based on the real-time temperature and the preset maximum allowable operating temperature of the coil.

[0057] Specifically, the real-time monitoring of the load current and input voltage of the DC contactor coil, and the determination of the real-time temperature of the DC contactor coil based on the load current, includes: acquiring the thermal model parameters of the DC contactor coil and the current load current; and calculating the real-time temperature of the DC contactor coil using the thermodynamic equation of state based on the thermal model parameters and the load current.

[0058] Specifically, the step of calculating the dynamic safety voltage limit based on the real-time temperature and the preset maximum allowable operating temperature of the coil includes: calculating the temperature difference between the real-time temperature and the maximum allowable operating temperature of the coil; and calculating the dynamic safety voltage limit based on the temperature difference using a linear compensation function.

[0059] The specific steps of implementation S101 include:

[0060] First, the load current signal is acquired through a precision sampling resistor (0.01 ohms, ±1% accuracy) connected in series in the DC contactor coil circuit. The voltage difference signal across the sampling resistor is then amplified 50 times by a high-impedance differential amplifier. Simultaneously, the input voltage signal is acquired through a resistor divider network (composed of precision resistors with values ​​of 100kΩ and 10kΩ, with a voltage division ratio of 11:1) connected to the input of the drive circuit. An analog-to-digital converter (ADC, such as the 12-bit ADC built into the STC32G12K128 series microcontroller) synchronously samples the amplified load current signal and the voltage-divided input voltage signal at a sampling frequency of 10kHz, and stores the sampled values ​​in the microcontroller's memory.

[0061] Next, pre-calibrated DC contactor coil thermal model parameters are read from the microcontroller's non-volatile memory. These parameters include: the coil's DC resistance R0 at 25 degrees Celsius (e.g., 0.5 ohms), the temperature coefficient of resistance α of the coil material (0.00393 / degree Celsius for copper), the coil's heat capacity C_th (e.g., 15 J / °C), and the coil's thermal resistance to the casing R_th (e.g., 2.5 °C / W). Based on these thermal model parameters and the currently sampled load current I_load, the coil's real-time temperature T_current is calculated using the following first-order thermodynamic equation of state:

[0062] T_current = T_ambient + (I_load² * R0 * (1 + α * (T_previous - 25)) *R_th) * (1 - exp(-Δt / (R_th * C_th))) + (T_previous - T_ambient) * exp(-Δt / (R_th * C_th));

[0063] Where T_ambient is the ambient temperature (in degrees Celsius) monitored in real time by a temperature sensor, T_previous is the coil temperature value obtained in the previous calculation cycle (the initial value can be set to T_ambient), and Δt is the calculation cycle (corresponding to the sampling cycle, which is 0.1 milliseconds).

[0064] Then calculate the temperature difference ΔT between the real-time temperature T_current and the preset maximum allowable operating temperature of the coil T_max (set according to the contactor specification, for example, 125 degrees Celsius): ΔT = T_max - T_current.

[0065] Finally, based on the temperature difference ΔT, the dynamic safety voltage upper limit V_dynamic_max is calculated using the following linear compensation function:

[0066] V_dynamic_max = V_base + k * ΔT.

[0067] Where V_base is the rated voltage of the DC contactor (e.g., 48V), and k is the compensation factor (set according to the coil's thermal tolerance, e.g., 0.05 V / °C). This calculation ensures that when the coil temperature is low (ΔT is large), the upper limit of the safe voltage is appropriately increased to utilize the coil's overload capacity; when the coil temperature is close to T_max (ΔT is small), the upper limit of the safe voltage approaches V_base, providing strict protection.

[0068] This step dynamically calculates the safe voltage threshold that varies with coil temperature by monitoring electrical parameters in real time and combining them with an accurate thermal model. This changes the rigid mode of traditional fixed threshold protection, enabling the protection system to adapt to the actual thermal state of the coil. While ensuring safety, it fully utilizes the coil's overload capacity at low temperatures, improving the system's adaptability and reliability under wide voltage fluctuations, and providing an accurate and adaptive benchmark threshold for subsequent intelligent mode decisions.

[0069] S102: Calculate the voltage change rate per unit time based on the input voltage, and compare the voltage change rate with a preset abrupt change threshold to determine whether there is a transient pulse threat.

[0070] Specifically, the step of calculating the voltage change rate per unit time based on the input voltage and comparing the voltage change rate with a preset abrupt change threshold to determine whether there is a transient pulse threat includes: performing differential calculation on the continuously sampled input voltage to obtain the voltage change rate per unit time; comparing the absolute value of the voltage change rate with the abrupt change threshold; and if the absolute value is greater than the abrupt change threshold, determining that there is a transient pulse threat.

[0071] The specific steps of implementation S102 include:

[0072] First, retrieve the four latest input voltage sample values ​​continuously acquired by the analog-to-digital converter at a sampling frequency of 100kHz in step S101 from the microcontroller memory, denoted as V. n (Current value), V n-1 (Previous value), V n-2 and V n-3 The sampling time interval Δt is 10 microseconds. The backward differential method is used to calculate the rate of change of the input voltage per unit time. Specifically, the rate of change of voltage dV / dt is calculated using the formula: dV / dt = (V n - V n-3 ) / (3Δt). This calculation is performed in the arithmetic logic unit of the microcontroller, and the result is stored in volts per millisecond (V / ms).

[0073] The absolute value of the calculated voltage change rate dV / dt is then taken to obtain the absolute value of the voltage change rate |dV / dt|. |dV / dt| is then compared with a preset abrupt change threshold. The abrupt change threshold is set according to the instantaneous overvoltage surge capability that the DC contactor coil can withstand, for example, 50 V / ms. The comparison operation is implemented through numerical comparison instructions on the microcontroller.

[0074] Finally, a judgment is made based on the comparison results: if the absolute value of the voltage change rate |dV / dt| is greater than the abrupt change threshold (50 V / ms), a transient pulse threat is determined to exist; if the absolute value of the voltage change rate |dV / dt| is less than or equal to the abrupt change threshold, a transient pulse threat is determined not to exist. The judgment result is stored as a Boolean value (True / False) in the microcontroller's flag register for subsequent step S103 to call.

[0075] This step precisely quantifies the rate of change of the input voltage through high-frequency sampling and differential calculation, and effectively identifies instantaneous high-voltage pulses that exceed the normal fluctuation range using an absolute value comparator. This mechanism separates the "rate of change" characteristic of voltage from the simple "voltage value," enabling the system to distinguish between two completely different threats: slow, continuous overvoltage and rapid, instantaneous pulses. This provides a crucial basis for subsequent differentiated protection strategies (S103), fundamentally solving the blind spots and hysteresis problems of traditional static voltage threshold detection methods when dealing with instantaneous pulses.

[0076] S103: Select the driving mode based on the following judgment rules: a) If the instantaneous pulse threat is determined to exist, select the voltage regulation and current limiting mode; b) If the instantaneous pulse threat is not determined to exist and the input voltage is higher than the dynamic safety voltage limit, select the buck regulation mode; c) If the input voltage is lower than or equal to the dynamic safety voltage limit, select the pass-through mode.

[0077] Specifically, if the instantaneous pulse threat is determined to exist, the step of selecting the voltage regulation and current limiting mode includes: generating a voltage regulation control signal to start the DC-DC buck converter and limiting the voltage output to the DC contactor coil to a range not exceeding the dynamic safety voltage upper limit; generating a current limiting control signal to limit the drive current of the DC contactor coil to a preset safety current threshold.

[0078] Specifically, if no instantaneous pulse threat is determined and the input voltage is higher than the dynamic safety voltage limit, then selecting the buck regulation mode includes: generating a buck enable signal to start the DC-DC buck converter; and setting the target output voltage of the DC-DC buck converter to the dynamic safety voltage limit.

[0079] Specifically, the step of selecting the pass-through mode if the input voltage is lower than or equal to the dynamic safety voltage upper limit includes: generating a pass-through control signal to control the switching device to directly couple the input voltage to the DC contactor coil; and simultaneously generating a disable signal to turn off the DC-DC buck converter.

[0080] The specific steps in step S103 during implementation include:

[0081] The microcontroller's central processing unit reads the instantaneous pulse threat determination result (Boolean value) stored in the flag register by step S102, and simultaneously reads the dynamic safety voltage upper limit V_dynamic_max calculated by step S101 and the value of the currently sampled input voltage V_in.

[0082] The microcontroller executes a priority-based three-branch decision logic. First, it checks if the instantaneous pulse threat determination result is True. If the determination result is True, the microcontroller selects the voltage regulation and current limiting mode. In this mode, the microcontroller outputs a high-level signal as a voltage regulation control signal through a specific pin of its general purpose input / output interface. This signal is sent to the enable pin of the DC-DC buck converter, starting the buck converter. Simultaneously, the microcontroller generates a PWM signal with an adjustable duty cycle through its built-in pulse width modulation module. The duty cycle of this PWM signal is adjusted in real time by a closed-loop control algorithm (such as proportional-integral control) based on V_dynamic_max, so that the output voltage of the DC-DC buck converter is limited to within the range of V_dynamic_max. In addition, the microcontroller continuously monitors the drive current flowing through the DC contactor coil through its analog-to-digital converter. When this current value exceeds a preset safe current threshold (e.g., 2 amps), the microcontroller immediately reduces the duty cycle of the PWM signal, thereby limiting the drive current within the safe current threshold.

[0083] If the instantaneous pulse threat determination result is False, the microcontroller continues to compare the input voltage V_in with the dynamic safety voltage limit V_dynamic_max. If V_in is greater than V_dynamic_max, the microcontroller selects the buck regulation mode. In this mode, the microcontroller also outputs a high-level buck enable signal to the enable pin of the DC-DC buck converter through a pin of the general purpose input / output interface, starting the converter. The microcontroller sets the target output voltage reference value of its pulse width modulation module to V_dynamic_max. The pulse width modulation module automatically adjusts the duty cycle of the output PWM wave according to this target value, driving the DC-DC buck converter to reduce the input voltage V_in to V_dynamic_max.

[0084] If the transient pulse threat determination result is False, and the input voltage V_in is less than or equal to the dynamic safety voltage limit V_dynamic_max, the microcontroller selects pass-through mode. In this mode, the microcontroller outputs a high-level pass-through control signal through a pin of its general purpose input / output interface (GPIO). This signal drives a switching device composed of an NMOS transistor to turn on, thereby directly coupling the input voltage V_in to the DC contactor coil. Simultaneously, the microcontroller outputs a low-level disable signal through the GPIO pin of the DC-DC buck converter enable pin, turning off the DC-DC buck converter to reduce power consumption.

[0085] This step introduces intelligent judgment rules with clear priorities, combining transient threat assessment based on voltage change rate with static overvoltage assessment based on dynamic safety threshold. This enables differentiated and precise responses to two different types of overvoltage stress: transient high-voltage pulses and long-term mild overvoltage. The rules ensure that the highest level of voltage regulation and current limiting protection is activated first when a transient pulse is detected. When there is no transient threat, the system intelligently selects either efficient step-down or direct-through mode based on the static voltage comparison result. This maximizes system energy efficiency and response speed while ensuring the safety of the DC contactor coil, solving the technical challenge of traditional single-threshold or simple dual-mode switching circuits failing to effectively distinguish and coordinate responses to complex voltage stresses.

[0086] S104: Execute the selected drive mode to generate and output a drive signal to the DC contactor.

[0087] The specific steps in step S104 during implementation include:

[0088] Based on the driving mode selected in step S103, the microcontroller executes the corresponding hardware driving operation. If the voltage regulation and current limiting mode is selected in step S103, the microcontroller will maintain a high-level signal output from its general-purpose input / output interface to the enable pin of the DC-DC buck converter. Simultaneously, the microcontroller's pulse width modulation module continuously runs the proportional-integral control algorithm. This algorithm uses the dynamic safety voltage limit V_dynamic_max as the voltage reference value and the actual sampled output voltage as the feedback value to calculate and adjust the duty cycle of the pulse width modulation signal in real time, thereby controlling the on and off times of the power MOSFETs in the buck converter, ensuring the output voltage remains stable within the range not exceeding V_dynamic_max. Simultaneously, the microcontroller continuously monitors the voltage drop across the current sampling resistor (0.05 ohms) connected in series in the loop through its analog-to-digital converter. When the calculated current value exceeds the preset safe current threshold (2 amps), the proportional-integral control algorithm uses the duty cycle limit as the new control target, rapidly reducing the duty cycle to limit the current.

[0089] If step S103 selects the buck regulation mode, the microcontroller also maintains the enable signal at a high level, but the pulse width modulation module adopts an open-loop control method. Its duty cycle is directly calculated and determined by the formula D = V_dynamic_max / V_in, where V_in is the current sampled input voltage. The microcontroller generates a fixed pulse width modulation signal based on this duty cycle to drive the DC-DC buck converter and reduce the voltage to V_dynamic_max.

[0090] If the pass-through mode is selected in step S103, the microcontroller maintains a high-level pass-through control signal output from its general purpose input / output interface to the gate of the NMOS switching device, ensuring that the NMOS switching device is fully turned on. Simultaneously, the microcontroller sets the signal connected to the enable pin of the DC-DC buck converter via its general purpose input / output interface to a low level, ensuring that the power switch inside the buck converter remains off. Finally, the drive signal is directly applied to both ends of the DC contactor coil through the power loop.

[0091] This step, as the final execution stage of the entire driving method, transforms the intelligent decision of step S103 into specific power control actions. By precisely controlling the pulse width modulation signal of the DC-DC buck converter or the on / off state of the direct-switch device, a driving voltage and current that meet safety requirements are ultimately generated and output to the DC contactor coil. This ensures that the electrical stress borne by the coil is within its safe operating range under any input voltage condition, thereby achieving intelligent and adaptive protection of the DC contactor and fully realizing the ultimate goal of the invention.

[0092] This embodiment provides a wide-voltage input adaptive voltage regulation drive method for DC contactors. This method monitors the load current and input voltage of the DC contactor coil in real time, determines the real-time coil temperature based on the load current, and calculates the dynamic safe voltage upper limit based on a preset maximum allowable operating temperature of the coil. Simultaneously, it calculates the rate of change of the input voltage per unit time and compares it with a preset abrupt change threshold to determine if a transient pulse threat exists. Based on the determination result, if a transient pulse threat exists, a voltage regulation and current limiting mode is selected; if not, and the input voltage is higher than the dynamic safe voltage upper limit, a buck regulation mode is selected; if the input voltage is lower than or equal to the dynamic safe voltage upper limit, a direct-through mode is used. After executing the selected drive mode, a drive signal is generated and output to the DC contactor. This method effectively solves the problem that existing technologies cannot distinguish and coordinately respond to overvoltage stresses of different natures, improving the intelligent response and protection capabilities of the drive circuit.

[0093] Figure 2 A connection diagram of the wide voltage input adaptive regulated drive system for DC contactors provided in this application is shown below. Figure 2 As shown, this embodiment provides a wide voltage input adaptive regulated drive system for DC contactors, which applies... Figure 1 The embodiment describes a wide voltage input adaptive regulated driving method for DC contactors, the driving system comprising:

[0094] The monitoring and calculation module is used to monitor the load current and input voltage of the DC contactor coil in real time, determine the real-time temperature of the DC contactor coil based on the load current, and calculate the dynamic safety voltage limit based on the real-time temperature and the preset maximum allowable operating temperature of the coil.

[0095] The threat determination module is connected to the monitoring and calculation module. The threat determination module is used to calculate the voltage change rate per unit time based on the input voltage and compare the voltage change rate with a preset abrupt change threshold to determine whether there is a transient pulse threat.

[0096] The mode selection module is connected to the monitoring and calculation module and the threat determination module. The mode selection module is used to select the driving mode based on the determination result: if the instantaneous pulse threat is determined to exist, the voltage regulation and current limiting mode is selected; if the instantaneous pulse threat is not determined to exist and the input voltage is higher than the dynamic safety voltage limit, the buck regulation mode is selected; if the input voltage is lower than or equal to the dynamic safety voltage limit, the pass-through mode is selected.

[0097] A drive execution module is connected to the mode selection module. The drive execution module is used to execute the selected drive mode to generate and output a drive signal to the DC contactor.

[0098] Specifically, the monitoring and calculation module includes:

[0099] The parameter acquisition unit is used to acquire the thermal model parameters of the DC contactor coil and the current load current.

[0100] A temperature calculation unit is connected to the parameter acquisition unit. The temperature calculation unit is used to calculate the real-time temperature of the DC contactor coil based on the thermal model parameters and the load current using the thermodynamic equation of state.

[0101] Specifically, the monitoring and calculation module includes:

[0102] The difference calculation unit is used to calculate the temperature difference between the real-time temperature and the maximum allowable operating temperature of the coil.

[0103] A dynamic threshold calculation unit is connected to the difference calculation unit. The dynamic threshold calculation unit is used to calculate the dynamic safety voltage upper limit based on the temperature difference using a linear compensation function.

[0104] This embodiment details the specific hardware configuration and connection relationships of a wide-voltage input adaptive regulated drive system for DC contactors. The drive system includes a monitoring and calculation module, a threat determination module, a mode selection module, and a drive execution module.

[0105] The monitoring and calculation module includes a parameter acquisition unit, a temperature calculation unit, a difference calculation unit, and a dynamic threshold calculation unit. The parameter acquisition unit includes a precision sampling resistor connected in series in the DC contactor coil circuit, with a resistance of 0.01 ohms and an accuracy of ±1%. The two ends of this sampling resistor are connected to the input of a high-impedance differential amplifier, whose voltage gain is set to 50. The amplifier's output is connected to the first input channel of the microcontroller's built-in 12-bit analog-to-digital converter. The input voltage is sampled through a voltage divider network consisting of 100kΩ and 10kΩ precision resistors, with the divider point connected to the second input channel of the microcontroller's analog-to-digital converter. The microcontroller's non-volatile memory stores the thermal model parameters of the DC contactor coil, including the coil's DC resistance at 25 degrees Celsius, the temperature coefficient of resistance of the coil material, the coil's thermal capacity, and the coil's thermal resistance to the casing. The temperature calculation unit is implemented internally within the microcontroller. The microcontroller reads the load current data and thermal model parameters acquired by the parameter acquisition unit and calculates the real-time temperature of the coil by executing a first-order thermodynamic equation of state calculation program stored in its program memory. The temperature difference calculation unit is implemented inside the microcontroller. It uses arithmetic logic units to calculate the temperature difference between the real-time temperature and the maximum allowable operating temperature of the coil read from non-volatile memory. The dynamic threshold calculation unit is also implemented inside the microcontroller. It calculates the dynamic safe voltage limit based on the temperature difference by executing a linear compensation function program.

[0106] The threat assessment module is integrated into the microcontroller in hardware. Its inputs are directly connected to the microcontroller's memory bus in the monitoring and calculation module to acquire continuously sampled input voltage data. Within the microcontroller, the threat assessment module implements a differential calculation routine in software. This routine calculates the voltage change rate using a backward differential method on four consecutive input voltage samples. The microcontroller's numerical comparator compares the calculated absolute value of the voltage change rate with a preset abrupt change threshold stored in the microcontroller's non-volatile memory. The comparison result is output to the microcontroller's internal status flag register. This design enables the threat assessment module to quickly identify abnormal voltage fluctuations, providing the system with critical instantaneous threat assessment signals.

[0107] The mode selection module is hardware-based, consisting of the microcontroller's central processing unit and its program logic. It shares the dynamic safety voltage upper limit and current input voltage data with the monitoring and calculation module via an internal data bus, and simultaneously obtains the instantaneous pulse threat determination result by reading the status flag register set by the threat determination module. The mode selection module executes a priority-based three-branch decision algorithm stored in program memory. The algorithm's output is directly mapped to specific pin level combinations of the microcontroller's general-purpose input / output interface, with each pin state combination corresponding to a drive mode selection signal. This hardware logic ensures the speed and determinism of mode decisions.

[0108] The drive execution module includes a DC-DC buck converter circuit, switching devices, and related signal drive circuits. The inputs of the drive execution module are directly connected to the general-purpose input / output interface pins of the mode selection module. When the voltage regulation and current limiting mode or the buck regulation mode is selected, the high-level enable signal output from the corresponding pin of the microcontroller is sent to the enable pin of the DC-DC buck converter control chip after passing through a level conversion circuit. This buck converter uses a Buck circuit topology built with the SCT2A25 chip from SCT (Single World Technology), and its power switch is a MOSFET. The pulse width modulation output pin of the microcontroller is connected to the feedback compensation network of the buck converter control chip, and the target output voltage is set to a dynamic safe voltage upper limit through an external voltage divider resistor. In voltage regulation and current limiting mode, the microcontroller monitors the voltage drop across the current sampling resistor through its built-in analog-to-digital converter and runs a proportional-integral control algorithm to dynamically adjust the duty cycle of the pulse width modulation signal, achieving the dual objectives of voltage and current limiting. When the pass-through mode is selected, the high-level signal output from another general-purpose input / output pin of the microcontroller is amplified by a gate driver chip and drives an NMOS switch with a rated current of 60A and a withstand voltage of 60V to be fully turned on, directly coupling the input voltage to the coil; at the same time, the enable signal sent to the buck converter is low to ensure that it is turned off.

[0109] The monitoring and calculation module, threat determination module, and mode selection module can be integrated into a single microcontroller with an analog-to-digital converter, pulse width modulation output, and sufficient computing power. The power components in the drive execution module are laid out on a printed circuit board and physically connected to the corresponding pins of the microcontroller and the DC contactor coil terminals via copper traces. All modules are powered and communicate via power and signal lines on the printed circuit board, together forming a complete and implementable hardware system.

[0110] Other embodiments of this application will readily occur to those skilled in the art upon consideration of the specification and practice of the invention disclosed herein. This application is intended to cover any variations, uses, or adaptations of this application that follow the general principles of this application and include common knowledge or customary techniques in the art not disclosed herein. The specification and examples are to be considered exemplary only, and the true scope and spirit of this application are indicated by the following claims.

[0111] It should be understood that this application is not limited to the precise structure described above and shown in the accompanying drawings, and various modifications and changes can be made without departing from its scope. The scope of this application is limited only by the appended claims.

Claims

1. A wide-voltage input adaptive regulated driving method for DC contactors, characterized in that, The method includes: The real-time monitoring of the load current and input voltage of a DC contactor coil, and the determination of the real-time temperature of the DC contactor coil based on the load current, specifically includes: acquiring the thermal model parameters of the DC contactor coil and the current load current; and calculating the real-time temperature of the DC contactor coil using the thermodynamic equation of state based on the thermal model parameters and the load current. The dynamic safety voltage limit is calculated based on the real-time temperature and the preset maximum allowable operating temperature of the coil; wherein, the calculation of the dynamic safety voltage limit based on the real-time temperature and the preset maximum allowable operating temperature of the coil specifically includes: calculating the temperature difference between the real-time temperature and the maximum allowable operating temperature of the coil; and calculating the dynamic safety voltage limit based on the temperature difference using a linear compensation function. The voltage change rate per unit time is calculated based on the input voltage, and the voltage change rate is compared with a preset abrupt change threshold to determine whether there is a transient pulse threat. The driving mode is selected based on the following judgment rules: a) If the instantaneous pulse threat is determined to exist, select the voltage regulation and current limiting mode; b) If no transient pulse threat is detected and the input voltage is higher than the dynamic safety voltage limit, then select the buck regulation mode; c) If the input voltage is lower than or equal to the dynamic safety voltage limit, then select the pass-through mode; The selected drive mode is executed to generate and output a drive signal to the DC contactor.

2. The wide voltage input adaptive regulated driving method for DC contactors according to claim 1, characterized in that, The step of calculating the voltage change rate per unit time based on the input voltage and comparing the voltage change rate with a preset abrupt change threshold to determine whether there is a transient pulse threat includes: The input voltage obtained by continuous sampling is differentially calculated to obtain the rate of change of voltage per unit time; The absolute value of the voltage change rate is compared with the abrupt change threshold; If the absolute value is greater than the threshold for abrupt changes, then the existence of the instantaneous pulse threat is determined.

3. The wide voltage input adaptive regulated driving method for DC contactors according to claim 1, characterized in that, If the instantaneous pulse threat is determined to exist, the voltage regulation and current limiting mode is selected, including: A voltage regulation control signal is generated to start the DC-DC buck converter, limiting the voltage output to the DC contactor coil to a range not exceeding the dynamic safety voltage limit. A current-limiting control signal is generated to limit the drive current of the DC contactor coil within a preset safe current threshold.

4. The wide voltage input adaptive regulated driving method for DC contactors according to claim 1, characterized in that, If no instantaneous pulse threat is determined and the input voltage is higher than the dynamic safety voltage limit, then selecting the buck regulation mode includes: Generate a buck enable signal to start the DC-DC buck converter; The target output voltage of the DC-DC buck converter is set to the dynamic safety voltage upper limit.

5. The wide voltage input adaptive regulated driving method for DC contactors according to claim 1, characterized in that, The step of selecting the pass-through mode if the input voltage is lower than or equal to the dynamic safety voltage upper limit includes: Generate a direct-through control signal to control the switching device to directly couple the input voltage to the DC contactor coil; Simultaneously, a disable signal is generated to shut down the DC-DC buck converter.

6. A wide voltage input adaptive regulated drive system for DC contactors, characterized in that, The driving system applies the driving method according to any one of claims 1-5, and the driving system comprises: The monitoring and calculation module is used to monitor the load current and input voltage of the DC contactor coil in real time, determine the real-time temperature of the DC contactor coil based on the load current, and calculate the dynamic safety voltage limit based on the real-time temperature and the preset maximum allowable operating temperature of the coil. The threat determination module is connected to the monitoring and calculation module. The threat determination module is used to calculate the voltage change rate per unit time based on the input voltage and compare the voltage change rate with a preset abrupt change threshold to determine whether there is a transient pulse threat. The mode selection module is connected to the monitoring and calculation module and the threat determination module. The mode selection module is used to select the driving mode based on the determination result: if the instantaneous pulse threat is determined to exist, the voltage regulation and current limiting mode is selected; if the instantaneous pulse threat is not determined to exist and the input voltage is higher than the dynamic safety voltage limit, the buck regulation mode is selected; if the input voltage is lower than or equal to the dynamic safety voltage limit, the pass-through mode is selected. A drive execution module is connected to the mode selection module. The drive execution module is used to execute the selected drive mode to generate and output a drive signal to the DC contactor.

7. The wide voltage input adaptive regulated drive system for DC contactors according to claim 6, characterized in that, The monitoring and calculation module includes: The parameter acquisition unit is used to acquire the thermal model parameters of the DC contactor coil and the current load current. A temperature calculation unit is connected to the parameter acquisition unit. The temperature calculation unit is used to calculate the real-time temperature of the DC contactor coil based on the thermal model parameters and the load current using the thermodynamic equation of state.

8. The wide voltage input adaptive regulated drive system for DC contactors according to claim 6, characterized in that, The monitoring and calculation module also includes: The difference calculation unit is used to calculate the temperature difference between the real-time temperature and the maximum allowable operating temperature of the coil. A dynamic threshold calculation unit is connected to the difference calculation unit. The dynamic threshold calculation unit is used to calculate the dynamic safety voltage upper limit based on the temperature difference using a linear compensation function.

Images