Method and system for protecting inductive voltage of inductive load in power-off state, and device

Abstract

The application relates to the technical field of electronic circuit protection, and provides an induced voltage protection method and system for an inductive load in a power-off state and equipment, which comprises the following steps: using an induced voltage generated by an inductive load under the action of external force to supply power to a control unit when a target system is in a power-off state; maintaining a power switch device in an off state in response to the power-on reset of the control unit; obtaining a voltage parameter of the induced voltage in response to the completion of initialization of the control unit and the satisfaction of preset stable working conditions; and controlling the power switch device to perform an energy discharge action to clamp the induced voltage based on the comparison result of the voltage parameter and a preset voltage threshold. The application realizes reliable overvoltage protection under the condition of no external power supply, effectively avoids the risk of power-on transient false triggering, and fills the protection blind area of the complete power-off state of the whole machine.

Description

Technical Field

[0001] This application relates to the field of electronic circuit protection, and in particular to methods, systems, and devices for protecting inductive loads from induced voltage under power failure conditions. Background Technology

[0002] In a complete system containing inductive loads such as motors, when the system is completely powered off, if the inductive load is driven to rotate by external mechanical force, its coil windings will generate an induced electromotive force (EMF). This induced EMF is fed into the power bus through the parasitic diodes or freewheeling circuits of the power devices, forming an uncontrollable induced voltage. Existing overvoltage protection circuits typically rely on the main control system power supply or an independent standby power supply to maintain operation. In scenarios where the entire system is completely powered off and there is no backup power supply, the protection circuit cannot detect voltage anomalies due to power loss, and cannot perform active discharge or braking operations. This exposes components on the power bus to the risk of overvoltage damage, resulting in a significant protection blind spot. Summary of the Invention

[0003] This application provides a method, system, and device for protecting inductive loads under power failure conditions, which solves the technical problem in the prior art of lacking effective active protection means when inductive loads are subjected to induced overvoltage by external forces under the condition of complete power failure of the whole machine.

[0004] To achieve the above objectives, this application adopts the following technical solution: In a first aspect, a method for protecting the induced voltage of an inductive load under power failure conditions is provided, comprising: when the target system is in a power failure state, using the induced voltage generated by the inductive load under the action of an external force to supply power to the control unit; In response to the power-on reset of the control unit, the power switching device is kept in the off state; In response to the control unit completing initialization and meeting preset stable operating conditions, the voltage parameters of the induced voltage are acquired; Based on the comparison result between the voltage parameter and the preset voltage threshold, the power switching device is controlled to perform an energy discharge action to clamp the induced voltage.

[0005] Based on the above technical solution, in the induced voltage protection method for inductive loads under power failure conditions provided in this application, by constructing an induced voltage self-powered circuit, the control unit can still obtain working energy when the whole machine is powered off and there is no external power supply, eliminating the dependence of traditional protection circuits on main power supply or standby power supply; at the same time, during the power-on reset phase, the power switching devices are forcibly kept off, avoiding the control unit from being falsely triggered to conduct due to unstable internal logic during the power-on transient. Voltage detection and discharge control are performed only after initialization is completed and stability is confirmed, thereby significantly improving the reliability and safety of the system startup process while ensuring the availability of the power failure protection function.

[0006] In conjunction with the first aspect above, in one possible implementation, satisfying the preset stable operating conditions includes at least one of the following: The control unit undergoes a preset delay time after power-on reset; The control unit detected that the internal status flag bit had flipped.

[0007] The criteria for determining "stable operation" are quantified by time or state dimensions. Preset delays are used to avoid voltage fluctuations and logic oscillations during the initial power-on period. Alternatively, internal flags are used to accurately characterize the hardware and software readiness status, ensuring that the control unit intervenes in the protection logic only when it has accurate sampling and decision-making capabilities. This further prevents power devices from malfunctioning due to uncertainties in the power-on process.

[0008] In conjunction with the first aspect above, in one possible implementation, the control unit undergoes a preset delay time after power-on reset, including: The control unit starts its internal timer after power-on reset; When the timing value of the internal timer reaches the preset delay threshold, it is determined that the control unit has completed initialization and the power switching device is deactivated, so as to allow control of the power switching device based on the comparison result of the voltage parameter and the preset voltage threshold.

[0009] By concretizing the abstract delay wait into an internal timer counting mechanism, a pure software implementation path that does not rely on external hardware reset signals is provided, which enhances the adaptability of the solution to different control unit models. Furthermore, by setting precise timing thresholds, the relationship between power-on safety margin and protection response speed is balanced.

[0010] In conjunction with the first aspect above, in one possible implementation, the energy dissipation action includes at least one of power dissipation and braking operation; The power discharge includes converting the induced energy into heat energy for consumption, or feeding the induced energy back to the energy storage element; The braking operation includes changing the electrical connection state of the inductive load to generate a reverse braking torque.

[0011] By decoupling the energy release action into two parallel technical paths—heat dissipation / energy recovery and mechanical braking—the former directly reduces the bus voltage amplitude, while the latter suppresses the generation of induced electromotive force from the source. Both can be used individually or in combination depending on the actual operating conditions, thereby improving the flexibility of the protection strategy and its adaptability to different types of external force driving scenarios.

[0012] In conjunction with the first aspect above, in one possible implementation, the power discharge includes at least one of the following: The induced energy is dissipated by connecting the power discharge resistors at both ends of the power bus. The induced energy is fed back to the energy storage capacitor of the power bus through modulation by the power switching device.

[0013] In conjunction with the first aspect above, in one possible implementation, the braking operation includes: By controlling the power switching device, the two ends of the winding or the three-phase winding of the inductive load are short-circuited, so that the inductive load generates the reverse braking torque when it is rotated by an external force.

[0014] By short-circuiting the windings to form a closed loop, the rotor generates an electromagnetic torque opposite to the direction of the external force when cutting the magnetic field lines. This is equivalent to applying a dynamic electromagnetic brake, which not only consumes kinetic energy but also fundamentally weakens the ability of the external force to continue driving the load to generate electricity, thus achieving a synergistic effect of electrical protection and mechanical braking.

[0015] In conjunction with the first aspect above, in one possible implementation, the preset voltage threshold includes a first threshold and a second threshold, wherein the second threshold is less than the first threshold; The step of controlling the power switching device to perform an energy discharge action based on the comparison result of the voltage parameter and the preset voltage threshold includes: When the voltage parameter rises above the first threshold, the energy discharge action is triggered; When the voltage parameter drops below the second threshold, the energy discharge action is terminated to form a hysteresis comparison interval.

[0016] Secondly, a voltage protection control system for an inductive load under power failure conditions is provided, comprising: A voltage detection circuit is installed between the power supply system of the target system and the inductive load to detect the induced voltage generated by the inductive load under the action of an external force. The control unit is electrically connected to the voltage detection circuit; A power switching device is electrically connected to the inductive load and controlled by the control unit; A step-down power supply circuit is connected between the output terminal of the induced voltage and the power input terminal of the control unit; The voltage detection circuit and the control unit are both powered by the induced voltage through the step-down power supply circuit. The control unit is configured to: after being powered on and reset by the induced voltage, keep the power switching device in the off state by default, and after initialization is completed and the preset stable operating conditions are met, control the power switching device to perform energy discharge action based on the comparison result of the voltage parameter of the induced voltage and the preset voltage threshold.

[0017] In conjunction with the first aspect above, in one possible implementation, the step-down power supply circuit includes an LDO step-down module or a DC-DC step-down module; The voltage detection circuit includes a voltage divider resistor network connected in series between the power bus and ground, and a Zener diode and a filter capacitor connected in parallel across the voltage divider resistor network.

[0018] Thirdly, this application provides an electrical device, including an inductive load and an induced voltage protection control system for the inductive load under power failure conditions as described in the first aspect, wherein the induced voltage protection control system for the inductive load under power failure conditions is disposed between the power supply system of the electrical device and the inductive load.

[0019] The present application provides a method, system, and device for protecting the induced voltage of an inductive load under power failure conditions, which has the following beneficial effects: By using the induced voltage generated by the inductive load under external force to power the control unit, the dependence of traditional protection circuits on the main power supply or standby power supply is completely eliminated. Active overvoltage detection and protection can still be achieved when the whole machine is completely powered off, filling the protection blind spot of the existing technology in the power off stage and solving the industry problem that active protection cannot be performed under passive conditions. After the control unit is powered on and reset by the induced voltage, the power switching devices are kept off by default until the initialization is completed and the stable operating conditions are met before the protection logic is activated. This mechanism effectively avoids the risk of false triggering caused by power establishment, logic reset or sampling instability during the bootstrap power-on process, and ensures that the protection action is executed only when the control unit has reliable decision-making ability, taking into account both the availability of power failure protection and the safety of the startup process. This application supports two energy discharge modes: power discharge and braking operation. It can quickly consume the bus power to clamp the voltage, and generate reverse braking torque through winding short-circuiting to suppress the generation of induced voltage from the source. Combined with the dual threshold hysteresis comparison strategy, it avoids the frequent switching of power devices at the critical voltage point. While ensuring the safety of components, it optimizes the system energy efficiency and device life, and improves the overall protection performance and robustness. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the inductive load voltage protection system architecture under power failure conditions according to an embodiment of this application; Figure 2 This is a schematic diagram of the power failure protection circuit principle and the step-down power supply module according to an embodiment of this application; Figure 3 This is a schematic diagram of the power failure induced voltage self-protection circuit according to an embodiment of this application. Detailed Implementation

[0021] In the description of this application, unless otherwise stated, " / " means "or," for example, A / B can mean A or B. The "and / or" in this document is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A alone, A and B simultaneously, and B alone. Furthermore, "at least one" means one or more, and "multiple" means two or more. The terms "first," "second," etc., do not limit the quantity or order of execution, and "first," "second," etc., do not necessarily imply differences.

[0022] It should be noted that, in this application, the terms "exemplary" or "for example" are used to indicate that something is being described as an example, illustration, or illustration. 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 design solutions. Specifically, the use of terms such as "exemplary" or "for example" is intended to present the relevant concepts in a concrete manner.

[0023] Example 1 like Figure 1 As shown, this embodiment provides a method for protecting inductive loads from induced voltage during power outages. This method is applied to complete systems containing inductive loads such as motors, aiming to solve the problem of damage to circuit components caused by induced overvoltage generated by external forces driving the inductive load when the system is completely powered off and there is no backup power supply. This method achieves active safety protection under passive conditions by constructing a collaborative control logic that integrates self-powered operation and anti-accidental contact.

[0024] Step S100: When the target system is in a power-off state, the control unit is powered by the induced voltage generated by the inductive load under the action of external force.

[0025] The power failure state of the target system refers to the physical state in which the main power input of the whole machine is cut off, but the electrical connection between the inductive load and the power bus is still maintained.

[0026] When the equipment is driven by external mechanical force during transportation, installation, or accidental power outage and coasting, the inductive load operates as a generator. The induced electromotive force generated is rectified by the parasitic diodes or freewheeling circuit of the power device and fed into the power bus to form an induced voltage.

[0027] In this embodiment, the induced voltage is not only the protected object being monitored, but also the sole energy source for the operation of the control unit and the detection circuit.

[0028] This self-powered energy mechanism enables the protection system to obtain startup energy even when there is no external mains power or battery power, fundamentally eliminating the dependence of traditional protection schemes on independent standby power supplies and filling the protection blind spot during power outages.

[0029] In step S200, in response to the power-on reset of the control unit, the power switching device is kept in the off state.

[0030] It should be noted that when the induced voltage accumulates to the control unit's minimum operating threshold, the control unit powers on and undergoes a reset process. During this stage, because the internal clock is not yet stable, the register state is not yet initialized, and the reference voltage of the analog sampling circuit has not yet been established, the control unit's output port may be in an uncertain high-impedance state or a random level state. If the control signal is directly allowed to output at this time, it is very easy to cause the power switching device to mis-turn on, which may lead to a bus short circuit or device overcurrent damage.

[0031] Therefore, in this embodiment, the drive logic of the power switching device is forcibly locked in the off state at the initial moment of power-on reset. This method ensures that the power circuit remains open until the control unit has reliable logic judgment capability, effectively avoiding the risk of false triggering during bootstrap power-on transients and ensuring the safety of the system startup process.

[0032] In step S300, in response to the control unit completing initialization and meeting the preset stable operating conditions, the voltage parameters of the induced voltage are acquired.

[0033] Among these criteria, stable operating conditions are the key distinction between the power-on transition zone and the normal operating zone. This condition indicates that the internal logic, clock system, and analog front-end of the control unit have all entered a reliable operating state. Only after confirming that this condition is met will the control unit activate the voltage sampling channel to read voltage parameters reflecting the induced voltage level of the bus.

[0034] In step S400, based on the comparison result between the voltage parameters and the preset voltage threshold, the power switching device is controlled to perform an energy discharge action to clamp the induced voltage.

[0035] It should be noted that the control unit compares the real-time voltage parameters with preset safety limits. When it is determined that the induced voltage exceeds the safety limit, the control unit releases the shutdown lock in step S200 and outputs a valid drive signal to control the power switching device to turn on or modulate, thereby performing energy discharge.

[0036] The energy discharge action can be achieved in ways including but not limited to consuming heat energy through resistors, feeding energy back to energy storage elements, or generating reverse braking torque through short-circuiting of windings. Its core purpose is to quickly reduce the induced energy on the bus and force the amplitude of the induced voltage to be clamped within the withstand voltage range of the electronic components.

[0037] Through the above closed-loop control process, this embodiment achieves accurate detection and active suppression of power failure-induced overvoltage while ensuring power-on safety, thus balancing the reliability of protection and the timeliness of response.

[0038] Example 2 Based on Example 1, this example further details the specific determination mechanism for "meeting the preset stable working conditions" in step S300.

[0039] As one implementation method, satisfying preset stable operating conditions includes at least one of the following: The control unit undergoes a preset delay after power-on reset; The control unit detected that the internal status flag bit had flipped.

[0040] By employing dual verification in either the time or state dimension, the control unit is ensured to intervene in the protection logic only when it has accurate sampling and decision-making capabilities, effectively preventing power device malfunctions caused by uncertainties in the power-on process.

[0041] In a further implementation, for the time-based determination method, the process of the control unit undergoing a preset delay after power-on reset includes: The control unit starts its internal timer after power-on reset; When the internal timer reaches the preset delay threshold, the control unit is determined to have completed initialization and the power switching device is deactivated, allowing control of the power switching device based on the comparison result between the voltage parameter and the preset voltage threshold.

[0042] In this implementation, the preset delay time is not arbitrarily set, but is based on a rigorous calculation of the system hardware characteristics.

[0043] For example, the preset delay time should be greater than the sum of the power-up time of the buck power supply circuit and the reset release time of the control unit itself. This is because during the process of the induced voltage rising from zero to the operating threshold, there may be a transient phase with voltage overshoot or large ripple at the output of the buck power supply circuit, and the oscillator frequency inside the control unit also needs a certain amount of time to reach the nominal accuracy.

[0044] If voltage detection is enabled or drive output is allowed during this unstable window period, ADC sampling errors are easily caused by reference drift, or PWM signal abnormalities are caused by clock jitter. By setting a delay threshold that covers all the above transient processes, a safety isolation zone is essentially built in the timing, forcibly shielding the logic oscillation risk in the initial power-on stage, thereby ensuring the reliability of subsequent protection actions.

[0045] As another optional implementation method, for the state-based determination method, the control unit detects that the internal state flag bit has flipped, which means monitoring the state change of a specific register inside the control unit or the execution feedback of a software process node.

[0046] The internal status flag can be a flag indicating that the analog-to-digital converter calibration is complete, a flag indicating that the watchdog timer has been fed normally for the first time, or a flag indicating that the system self-test program has passed.

[0047] When the flag bit flips from the initial reset state to the ready state, it indicates that the core functional modules of the control unit have completed self-configuration and are in a reliable working state. Compared with a pure delay scheme, the flag-based determination method can more accurately reflect the actual readiness of the hardware and software, avoiding protection response lag caused by excessively long fixed delays. It is particularly suitable for application scenarios with large power-on time dispersion or high real-time protection requirements.

[0048] Example 3 Based on Example 1, this example provides a detailed description of the specific implementation path of the energy release action in step S400.

[0049] As one implementation, the energy discharge action includes at least one of power discharge and braking operation; Power dissipation includes converting induced energy into heat energy for consumption, or feeding induced energy back to energy storage elements.

[0050] This feature decouples abstract energy processing strategies into two parallel technical branches: energy dissipation paths based on thermodynamic principles and energy transfer paths based on circuit topology transformations. This classification not only covers existing mainstream dissipation methods but also reserves space for higher-level explanations of potential new energy processing technologies in the future.

[0051] In this embodiment, we will focus on two specific topologies for power dissipation.

[0052] As the first form of power dissipation, induced energy can be dissipated by connecting the power dissipation resistors connected at both ends of the power bus.

[0053] like Figure 3 As shown, the circuit topology includes a power-consuming switch Q1 and a power bleed resistor R4. The drain of the power-consuming switch Q1 is connected to the positive power supply bus +VDD, the source is grounded to GND via the power bleed resistor R4, and the gate receives the control signal CTRL from the control unit MCU.

[0054] When the control unit determines that the induced voltage exceeds the preset threshold and power discharge needs to be performed, it outputs a valid control signal CTRL to turn on the power dissipation switch Q1. At this time, the induced voltage on the power bus is applied across the power discharge resistor R4. The induced current flows through the resistor and generates Joule heat, thereby quickly converting the electrical energy stored in the bus capacitor CE1 and the inductive load into heat energy and dissipating it.

[0055] The advantage of this approach is that the circuit structure is simple, the control logic is direct, and the response speed is extremely fast. It is particularly suitable for scenarios where external force drives sudden speed changes and generates huge induced energy impacts in a short period of time. It can quickly clamp voltage peaks and prevent overvoltage breakdown.

[0056] As a second form of power discharge, the induced energy can also be fed back to the energy storage capacitor of the power bus through modulation by power switching devices.

[0057] Unlike the aforementioned resistive energy dissipation method, this method does not directly convert energy into waste heat, but instead utilizes the existing power switching devices (such as motor drive bridge arms) in the motor drive bridge arm. Figure 1 The MOSFETs or IGBTs in the three-phase full-bridge circuit shown, together with energy storage elements such as inductors, constitute a buck-boost converter topology.

[0058] The control unit controls the periodic switching of the power switching devices by outputting a PWM modulation signal with a specific duty cycle, "pumping" the induced electromotive force generated by the inductive load into the bus energy storage capacitor CE1 for storage. From the perspective of energy conservation, this is essentially collecting and temporarily storing the electrical energy converted from mechanical energy in the system, rather than simply destroying it.

[0059] The significant advantage of this approach is its high energy efficiency, avoiding the severe heat generation problems caused by high-power bleeder resistors and reducing the requirements for system heat dissipation design. Therefore, it is particularly suitable for operating conditions where inductive loads are driven by continuous constant external forces (such as wind-driven or long-distance downhill coasting) resulting in long-term power generation, or for application scenarios with strict limitations on equipment size, weight, and heat dissipation conditions.

[0060] In summary, whether it's converting induced energy into heat energy through resistance or feeding induced energy back to the energy storage capacitor through modulation, both methods achieve the core objective of reducing the amplitude of the induced voltage on the bus and protecting the safety of circuit components.

[0061] In practical engineering applications, designers can flexibly choose one of the methods or combine two methods based on the system's heat dissipation capacity, cost budget, energy efficiency indicators, and expected external force driving characteristics.

[0062] For example, during the transient phase of a sharp voltage rise, resistor discharge is prioritized to achieve rapid suppression, while during the continuous power generation phase after voltage stabilization, the system switches to energy feedback mode to improve energy efficiency. This diversified implementation path design ensures that the technical solution of this application maintains sufficient protection effectiveness and engineering adaptability when facing complex and ever-changing real-world application environments.

[0063] Example 4 Based on Example 1, this example provides a detailed description of another specific implementation path for the energy release action in step S400.

[0064] As one implementation, the energy release action also includes a braking operation, which includes changing the electrical connection state of the inductive load to generate a reverse braking torque.

[0065] Unlike the power dissipation method described in Example 3, which uses heat dissipation or energy feedback to process generated electrical energy, braking operation focuses on intervening at the source of energy generation.

[0066] It should be noted that the braking operation is achieved by controlling the power switching device to short-circuit the two ends of the winding or the three-phase winding of the inductive load, so that the inductive load generates a reverse braking torque when it is rotated by an external force.

[0067] When the windings of an inductive load are forcibly short-circuited to form a closed loop, the induced electromotive force generated by the external force driving the rotor to cut the magnetic field lines will induce a large short-circuit current inside the windings. According to Lenz's law, the magnetic field generated by this short-circuit current always opposes the change in magnetic flux that caused it, thus creating an electromagnetic torque on the rotor that is opposite to the direction of the external force. This reverse braking torque is physically equivalent to applying a dynamic electromagnetic brake, directly counteracting the driving effect of the external mechanical force.

[0068] This braking operation has a dual advantage. On the one hand, the short-circuit current consumes some kinetic energy when flowing through the winding's internal resistance, thus playing a certain role in energy release. On the other hand, and more importantly, the reverse braking torque significantly reduces or even prevents the inductive load from increasing its speed, thereby directly weakening the conditions for the generation of induced electromotive force.

[0069] The braking operation not only handles the already generated overvoltage energy, but also actively suppresses the continuous generation of overvoltage energy through a mechanical-electrical coupling mechanism. This is fundamentally different from the passive defense mode in Example 3, which relies solely on external resistors or capacitors to absorb energy. It demonstrates the synergistic effect of electrical protection and mechanical braking, and is particularly suitable for operating conditions where the external driving source is continuous and the energy input is large.

[0070] In practice, the way the electrical connection status is changed varies depending on the type of inductive load.

[0071] For example, for dual-winding loads such as two-phase stepper motors, the control unit can control the power switching devices to independently short-circuit the two ends of each phase winding, or short-circuit all four leads of the two-phase windings together through a specific bridge arm combination. For three-winding loads such as three-phase permanent magnet synchronous motors or asynchronous motors, the control unit can control all upper or lower bridge arms in the three-phase full-bridge circuit to conduct, so that the three-phase windings form a common point short circuit on the DC bus side; or control a specific combination of switching transistors to connect the three-phase windings end to end to form a delta short-circuit circuit.

[0072] Example 5 Based on Example 1, this example further defines the specific strategy for controlling the voltage parameters based on the comparison result of the voltage parameters and the preset voltage threshold in step S400.

[0073] As one implementation, the preset voltage threshold includes a first threshold and a second threshold, wherein the second threshold is less than the first threshold; Based on the comparison between the voltage parameters and the preset voltage threshold, the power switching device is controlled to perform an energy discharge action, including: When the voltage parameter rises above the first threshold, an energy discharge action is triggered. When the voltage parameter drops below the second threshold, the energy discharge action is terminated to form a hysteresis comparison range.

[0074] The first threshold is the trigger point for overvoltage protection. Its value is usually set to a safety limit slightly lower than the rated withstand voltage of key components (such as electrolytic capacitors and power transistors) on the power bus, so as to ensure that clamping is initiated in time before the voltage reaches a dangerous level.

[0075] The second threshold is the exit point of the protection state, and its value is strictly less than the first threshold. The difference between the two is the hysteresis width.

[0076] In actual operation, when an external force drives an inductive load, causing the induced voltage on the bus to rise and exceed the first threshold, the control unit immediately outputs a drive signal to turn on the power switching device, and performs energy dissipation actions such as resistor energy consumption, energy feedback, or winding short circuit as described in the previous embodiment, forcing the voltage to drop.

[0077] However, due to the mismatch between the mechanical inertia and electrical time constant of inductive loads, the voltage drop process is often accompanied by damped oscillations or periodic rebounds. If a single threshold control is used, the device will be turned off once the voltage drops below the threshold, but may then be turned on again due to residual kinetic energy or rebound, exceeding the threshold. This frequent switching on and off at the millisecond or even microsecond level not only generates severe electromagnetic interference, but also drastically shortens the lifespan of power switching devices due to repeated surge current impacts, and may even lead to thermal breakdown.

[0078] By setting a second threshold as the exit criterion, this embodiment constructs a voltage buffer band between the trigger point and the exit point.

[0079] Only when the induced voltage is effectively suppressed and continues to drop significantly below the second threshold of the trigger point will the system determine that the overvoltage risk has been completely eliminated and allow the power switching device to turn off.

[0080] This hysteresis characteristic is equivalent to having a nonlinear filter connected in series in the control loop, which shields the switching state from the interference of voltage ripple and transient disturbances at the logic level.

[0081] In engineering implementation, the hysteresis width is usually determined by joint simulation or actual measurement based on the electromechanical time constant of the inductive load, the bus capacitance, and the thermal impedance curve of the power device. For example, it can be set to 5% to 15% of the first threshold, or set to a fixed voltage value such as 20V to 50V, to ensure the optimal balance between suppressing switching oscillations and avoiding excessive discharge.

[0082] In addition, to further improve the robustness of control, time filtering or counting filtering can be introduced as auxiliary criteria based on the above hysteresis comparison.

[0083] For example, triggering is confirmed only when the voltage parameter is higher than the first threshold for N consecutive sampling periods, or exiting only when the voltage is lower than the second threshold and the duration exceeds the preset debouncing time. This spatiotemporal dual verification mechanism can effectively filter out false signals caused by ADC sampling noise or external transient spikes, ensuring that the triggering and exiting of each energy discharge action is based on the actual bus overvoltage state. Thus, while ensuring circuit safety, it maximizes the optimization of the working stress of power devices and the overall reliability of the system.

[0084] Example 6 like Figure 2 As shown, this embodiment provides an induced voltage protection control system for inductive loads under power failure conditions. This system serves as the hardware carrier of the protection method in the aforementioned embodiment, and solidifies the self-powered and anti-accidental-touch logic into a physical entity through a specific circuit topology and connection relationship.

[0085] The system includes a voltage detection circuit, a control unit (MCU), power switching devices, and a step-down power supply circuit.

[0086] The voltage detection circuit is located between the power supply system of the target system and the inductive load to detect the induced voltage generated by the inductive load under the action of external force. The control unit MCU is electrically connected to the voltage detection circuit and is used to process the detection signal and output control commands; The power switching device is electrically connected to the inductive load and is controlled by the control unit MCU to perform on / off operations; The step-down power supply circuit is connected between the output terminal of the induced voltage and the power input terminal of the control unit MCU.

[0087] The specific implementation of the step-down power supply circuit includes LDO step-down modules or DC-DC step-down modules. For example... Figure 2 As shown in the independent box below, the input terminal of the step-down power supply circuit is connected to the positive power bus +VDD, the output terminal is connected to the control unit operating voltage +VCC, and the common terminal is grounded GND.

[0088] When selecting a specific model, if the voltage difference between the induced voltage and the operating voltage of the control unit is small and the system is sensitive to noise, an LDO step-down module can be preferred to obtain low ripple output. If the induced voltage range is wide and the system has high energy efficiency requirements, a DC-DC step-down module should be selected to reduce heat loss. Regardless of the topology used, its output +VCC directly supplies power to the control unit MCU and the subsequent stage of the voltage detection circuit, ensuring the energy self-sufficiency of the entire protection link.

[0089] The specific implementation of the voltage detection circuit includes a voltage divider resistor network connected in series between the power bus and ground, and a Zener diode and a filter capacitor connected in parallel across the voltage divider resistor network. Combined with... Figure 2 As shown, the voltage divider resistor network consists of resistors R1 and R2 connected in series, bridging the positive power supply bus +VDD and the ground terminal GND. The common connection point of the two serves as the sampling node.

[0090] The sampling node is connected to the analog input pin of the control unit MCU via a current-limiting resistor R3. The cathode of the Zener diode D1 is connected between the current-limiting resistor R3 and the MCU input pin, and the anode is grounded; the filter capacitor C11 is connected in parallel between the MCU input pin and ground.

[0091] This multi-level protection and conditioning structure design has clear parameter selection principles and technical effects: First, the resistance ratio of resistors R1 and R2 needs to be calculated based on the maximum expected amplitude of the induced voltage and the reference voltage range of the ADC inside the control unit MCU to ensure that the low voltage start-up threshold can be distinguished within the full range, and that sampling overflow will not occur at high voltage. Secondly, the clamping voltage of Zener diode D1 should be set slightly higher than the upper limit of the safe input voltage of the control unit MCU but lower than its absolute maximum rated value. When the induced voltage has a transient spike or the voltage divider network fails, D1 can force the voltage sent to the MCU to be limited within the safe area to prevent the IO port from being damaged by breakdown. Furthermore, the filter capacitor C11 and the current-limiting resistor R3 form a first-order low-pass filter, which is used to filter out high-frequency noise caused by the switching of power devices or mechanical commutation in the induced voltage, ensuring that the voltage parameters collected by the MCU truly reflect the DC level of the bus and avoiding false protection triggered by interference signals.

[0092] The control unit MCU is configured to: after power-on reset powered by the induced voltage, keep the power switching device in the off state by default, and after initialization is completed and the preset stable operating conditions are met, control the power switching device to perform energy discharge action based on the comparison result of the voltage parameter of the induced voltage and the preset voltage threshold.

[0093] In terms of hardware connectivity, the output port of the control unit MCU is connected to a power switching device (such as...) via a driver circuit or directly. Figure 3 The control electrode of the energy-consuming switch Q1 or the motor drive bridge arm.

[0094] Example 7 This embodiment provides an electrical device, which includes an inductive load and an induced voltage protection control system for the inductive load under power failure conditions as described in the previous embodiment. The induced voltage protection control system for the inductive load under power failure conditions is disposed between the power supply system of the electrical device and the inductive load.

[0095] It should be noted that the electrical equipment can be an automated logistics vehicle, a precision CNC machine tool, an industrial robot, or an electric vehicle, or other electromechanical equipment that includes a motor drive system.

[0096] During the production testing, shipping, on-site installation, or other abnormal operation phases of these devices, such as accidental power outages and coasting, the main power supply of the entire machine is usually cut off, but inductive loads (such as servo motors and stepper motors) still maintain physical connection with the control board.

[0097] If the equipment is subjected to external mechanical forces (such as transportation vibration, manual dragging, gravity sliding, etc.), the inductive load will switch to generator mode and inject uncontrollable induced energy into the power bus.

[0098] This embodiment integrates the aforementioned induced voltage protection and control system into the electrical equipment, making it an inherent safety attribute of the equipment. This automatically activates the protection mechanism in the aforementioned power outage scenario, effectively preventing faults such as drive module breakdown, bus capacitor explosion, or control chip damage caused by induced overvoltage, and significantly improving the product's environmental adaptability and full life cycle reliability.

[0099] To more clearly illustrate the dynamic protection effect of the technical solution of this application in practical applications, the following is a detailed explanation using the example of an automated logistics equipment with a rated bus voltage of 48V being driven by external vibration during power outage transportation.

[0100] In this scenario, the main power supply to the equipment is disconnected, but the motor windings remain connected to the drive board. When the transport vehicle travels over a bumpy road, forcing the motor rotor to rotate, the resulting back electromotive force is rectified by the freewheeling diode and charges the bus capacitor CE1, causing the induced voltage on the bus to rise from 0V.

[0101] When the induced voltage rises to about 7V, the step-down power supply circuit (such as an LDO or DC-DC module) starts to work, outputting a stable +3.3V or +5V voltage to power the control unit MCU.

[0102] In the initial stage after power-on reset, the control unit MCU strictly follows the anti-accidental touch mechanism described in Embodiment 2 above, forcibly keeping all power switching devices in the off state and starting an internal timer for a preset delay (e.g., 50ms). This delay window effectively shields the risk of false triggering caused by power supply ripple, unstable reference voltage, or uncertain I / O port levels at the moment of power-on, ensuring that the system only intervenes for protection after the logic is fully ready.

[0103] As the external force continues to act, the induced voltage on the bus continues to rise. Once the control unit MCU completes initialization and confirms that stable operating conditions are met, the voltage sampling channel is immediately activated.

[0104] Assuming that the induced voltage has climbed to 60V (i.e., exceeding the preset first threshold, which is set according to the bus capacitor and the power transistor withstand voltage, with a safety margin), the control unit MCU determines to trigger the energy discharge action according to the hysteresis comparison strategy described in the aforementioned embodiment 5.

[0105] The control unit MCU then outputs a PWM modulation signal or a level signal to turn on the power switching device to perform the resistor energy dissipation or winding short-circuit braking operation described in Embodiment 3 or Embodiment 4.

[0106] Since the digital processing and drive response time of the control unit MCU is usually in the microsecond range, which is much faster than the mechanical rise rate of the induced voltage, it can quickly clamp the bus voltage within a safe range and prevent the voltage from rising further to dangerous levels of 80V or even 100V.

[0107] During the energy discharge process, if the external force weakens or the braking takes effect, causing the induced voltage to drop, the control unit MCU will shut down the power switching device and exit the protection state when the voltage drops to 45V (i.e., below the preset second threshold).

[0108] This hysteresis control with hysteresis avoids frequent switching of devices when the voltage fluctuates near the 60V critical point, protecting the thermal safety of the power switching devices and maintaining the stability of the bus voltage.

[0109] Although this application has been described herein in conjunction with various embodiments, those skilled in the art, by reviewing the accompanying drawings, disclosure, and appended claims, will understand and implement other variations of the disclosed embodiments in carrying out the claimed application. In the claims, the word "comprising" does not exclude other components or steps, and "a" or "an" does not exclude multiple instances. A single processor or other unit can implement several functions listed in the claims. While different dependent claims may recite certain measures, this does not mean that these measures cannot be combined to produce good results.

[0110] Although this application has been described in conjunction with specific features and embodiments, it is obvious that various modifications and combinations can be made thereto without departing from the spirit and scope of this application. Accordingly, this specification and drawings are merely exemplary illustrations of this application as defined by the appended claims, and are considered to cover any and all modifications, variations, combinations, or equivalents within the scope of this application. Clearly, those skilled in the art can make various alterations and modifications to this application without departing from the spirit and scope of this application. Thus, if such modifications and modifications of this application fall within the scope of the claims of this application and their equivalents, this application is also intended to include such modifications and modifications.

Claims

1. A method for protecting the induced voltage of an inductive load under power failure conditions, characterized in that, include: When the target system is in a power-off state, the control unit is powered by the induced voltage generated by the inductive load under the action of external force. In response to the power-on reset of the control unit, the power switching device is kept in the off state; In response to the control unit completing initialization and meeting preset stable operating conditions, the voltage parameters of the induced voltage are acquired; Based on the comparison result between the voltage parameter and the preset voltage threshold, the power switching device is controlled to perform an energy discharge action to clamp the induced voltage.

2. The method according to claim 1, characterized in that, The preset stable operating conditions include at least one of the following: The control unit undergoes a preset delay time after power-on reset; The control unit detected that the internal status flag bit had flipped.

3. The method according to claim 2, characterized in that, The control unit undergoes a preset delay after power-on reset, including: The control unit starts its internal timer after power-on reset; When the timing value of the internal timer reaches the preset delay threshold, it is determined that the control unit has completed initialization and the power switching device is deactivated, so as to allow control of the power switching device based on the comparison result of the voltage parameter and the preset voltage threshold.

4. The method according to claim 1, characterized in that, The energy discharge action includes at least one of power discharge and braking operation; The power discharge includes converting the induced energy into heat energy for consumption, or feeding the induced energy back to the energy storage element; The braking operation includes changing the electrical connection state of the inductive load to generate a reverse braking torque.

5. The method according to claim 4, characterized in that, The power discharge includes at least one of the following: The induced energy is dissipated by connecting the power discharge resistors at both ends of the power bus. The induced energy is fed back to the energy storage capacitor of the power bus through modulation by the power switching device.

6. The method according to claim 4, characterized in that, The braking operation includes: By controlling the power switching device, the two ends of the winding or the three-phase winding of the inductive load are short-circuited, so that the inductive load generates the reverse braking torque when it is rotated by an external force.

7. The method according to claim 1, characterized in that, The preset voltage threshold includes a first threshold and a second threshold, wherein the second threshold is less than the first threshold; The step of controlling the power switching device to perform an energy discharge action based on the comparison result of the voltage parameter and the preset voltage threshold includes: When the voltage parameter rises above the first threshold, the energy discharge action is triggered; When the voltage parameter drops below the second threshold, the energy discharge action is terminated to form a hysteresis comparison interval.

8. A system for protecting the induced voltage of an inductive load under power failure conditions, applied to the method described in any one of claims 1-7, characterized in that, include: A voltage detection circuit is installed between the power supply system of the target system and the inductive load to detect the induced voltage generated by the inductive load under the action of an external force. The control unit is electrically connected to the voltage detection circuit; A power switching device is electrically connected to the inductive load and controlled by the control unit; A step-down power supply circuit is connected between the output terminal of the induced voltage and the power input terminal of the control unit; The voltage detection circuit and the control unit are both powered by the induced voltage through the step-down power supply circuit. The control unit is configured to: after being powered on and reset by the induced voltage, keep the power switching device in the off state by default, and after initialization is completed and the preset stable operating conditions are met, control the power switching device to perform energy discharge action based on the comparison result of the voltage parameter of the induced voltage and the preset voltage threshold.

9. The system according to claim 8, characterized in that: The step-down power supply circuit includes an LDO step-down module or a DC-DC step-down module; The voltage detection circuit includes a voltage divider resistor network connected in series between the power bus and ground, and a Zener diode and a filter capacitor connected in parallel across the voltage divider resistor network.

10. An electrical appliance, characterized in that, The device includes an inductive load and a voltage protection control system for the inductive load under power failure conditions as described in claim 8, wherein the voltage protection control system for the inductive load under power failure conditions is located between the power supply system of the electrical equipment and the inductive load.

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