Soft turn-off control method of direct current solid state switch and direct current solid state switch

Abstract

The application discloses a soft-off control method of a direct-current solid-state switch and relates to the field of low-voltage electrical apparatuses.The method comprises the following steps: calculating a stage index based on a load current and / or a switch drain-source voltage; after a driving signal decreases to a duty ratio and / or a gate voltage of a current soft-off stage, if it is monitored that the stage index is greater than a stage advancing threshold value, entering a next soft-off stage; and the direct-current solid-state switch comprises a signal sampling module, a control module and a driving module.The method can avoid the problems of surges and electromagnetic interference caused by the fact that a working condition is not suitable for a preset driving time sequence, can cope with more complex working conditions, realizes adaptive adjustment of a soft-off process under different working conditions, and improves the robustness of a system.

Description

Technical Field

[0001] This invention relates to the field of low-voltage electrical appliances, and more specifically to a soft-shutdown control method for a DC solid-state switch and the DC solid-state switch itself. Background Technology

[0002] In the early stages of the development of DC power electronic systems, the switching control of DC loads relied heavily on mechanical relays, which had problems such as short mechanical life, contact oxidation, and difficulty in arc breaking.

[0003] With the improvement of the performance of power devices such as MOSFETs, IGBTs, and SCRs, DC solid-state switches are gradually replacing mechanical relays and are widely used in load scenarios such as electromagnets, solenoid valves, and DC motors. However, since the DC inductor flyback energy does not have the "zero-crossing" characteristic and will not naturally pass through zero current, the DC solid-state switch will generate extremely high surges when it is disconnected.

[0004] As the main way to suppress surges in DC solid-state switches, soft turn-off generally lacks dynamic adjustment capability. Safety and system efficiency cannot be balanced. The turn-off rate is controlled by a preset fixed timing sequence, and it is usually preset according to the worst-case operating condition. Under good operating conditions, the turn-off process is unnecessarily slow, which reduces system efficiency and increases switching losses. It also has poor adaptability to different operating conditions. Summary of the Invention

[0005] The purpose of this invention is to overcome at least one defect of the prior art and provide a soft-shutdown control method for a DC solid-state switch and a DC solid-state switch.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] A soft-shutdown control method for a DC solid-state switch, characterized by comprising the following steps:

[0008] S1 receives the shutdown command and samples the load current. and switch drain-source voltage ;

[0009] S2, enter the soft shutdown process. The soft shutdown process is configured as a multi-level soft shutdown control mode, with multiple soft shutdown stages Stg[n]. Each soft shutdown stage Stg[n] corresponds to a progressively decreasing duty cycle and / or gate voltage, so that the duty cycle and / or gate voltage of the drive signal are progressively decreased to the shutdown threshold according to the preset multiple soft shutdown stages Stg[n], and then the shutdown signal is output.

[0010] In step S2, based on the load current and / or switch drain-source voltage Calculate the stage exponent S[n]. After the drive signal decreases to the duty cycle and / or gate voltage of the current soft-turn-off stage Stg[n], if the stage exponent S[n] is detected to be greater than the stage advancement threshold, then... If the current condition is met, then proceed to the next soft shutdown phase Stg[n+1].

[0011] Furthermore, the formula for calculating the stage index S[n] is as follows:

[0012] S[n]= ;

[0013] in, , , , The constant coefficients, The rate of change of current, Indicates the retrace energy. Indicates the rated current. Represents bus voltage. TH2 is a constant.

[0014] Furthermore, in the multiple soft shutdown stages Stg[n] of the soft shutdown process, different gate driving laws G[n] are used respectively, and the gate driving laws G[n] are configured as follows:

[0015] G[n] = βG[n-1] + (1-β) ;

[0016] Where β represents the smoothing / inertia coefficient, and g1, g2, gn, gn+1 represent preset multi-segment target gear coefficients.

[0017] Furthermore, in step S2, based on the load current and / or switch drain-source voltage Calculate the soft turn-off control index Z[n]. When it is detected that the soft turn-off control index Z[n] exceeds the preset adjustment threshold, adjust the multiple soft turn-off stages Stg[n], generate and enter a new soft turn-off stage Stg[ad]. The duty cycle and / or gate voltage corresponding to the soft turn-off stage Stg[ad] are less than the duty cycle and / or gate voltage corresponding to the current soft turn-off stage Stg[n].

[0018] Furthermore, the duty cycle and / or gate voltage corresponding to the soft turn-off stage Stg[ad] are greater than or equal to the duty cycle and / or gate voltage corresponding to the next soft turn-off stage Stg[n+1].

[0019] Furthermore, the soft shutdown phase The corresponding duty cycle and / or gate voltage are calculated as follows:

[0020] ;

[0021] in, Indicates the step size of the stage.

[0022] Furthermore, in step S2.2, the stage step size is adjusted according to the current change rate:

[0023] =clip( , );

[0024] clip() is a clipping function. This is the proportionality coefficient. and Used for setting The lower and upper limits.

[0025] Furthermore, the soft-shutdown control index Z[n] includes the rate of change of current. and / or energy integral ,

[0026] ,in, The time window representing the sampling frequency;

[0027] = ;or .

[0028] Furthermore, step S4 includes entering a latching state after the power switch is turned off, when a current of opposite polarity is detected within the same sampling period, causing the power switch to enter a delay protection period. During the extended protection period The power switch transistor must not be turned on again.

[0029] A DC solid-state switch includes a signal sampling module, a control module, and a drive module. The drive module is connected to a power switch transistor, and the signal sampling module is connected to the control module. The control module controls the drive module to output a drive signal, thereby controlling the power switch transistor to turn on or off. The control module executes the soft-turn-off control method for the DC solid-state switch as described above.

[0030] The soft-turn-off control method for DC solid-state switches of the present invention, compared with the control method of preset drive timing according to the worst-case operating conditions in the prior art, can advance the soft-turn-off stage more quickly when the operating conditions are good, significantly reducing switching losses and improving system efficiency. By adaptively advancing the soft-turn-off stage, it avoids surge and electromagnetic interference problems caused by the mismatch between the operating conditions and the preset drive timing. It can cope with more complex operating conditions, realize adaptive adjustment of the soft-turn-off process under different operating conditions, and improve system robustness.

[0031] In addition, by using slope closed-loop control, voltage spikes are dynamically suppressed, providing a stronger ability to cope with load changes. The current change rate is dynamically sensed and the stage step size is adjusted, enabling a more proactive and timely response to overvoltage risks and improving safety.

[0032] Furthermore, compared to the existing technology where the continuous discharge path makes it difficult to control the rate of change of current at the moment of inductive load turn-off, the soft turn-off control method of the DC solid-state switch of the present invention, through an openable energy recovery path combined with a multi-stage soft turn-off control mode, monitors the soft turn-off control index and energy index in real time, and adjusts the soft turn-off process in real time when the rate of change of current is higher than expected, so that the rate of change of current is always within a controllable range, suppressing surges while reducing electromagnetic interference, and improving the system turn-off reliability and electromagnetic compatibility. Attached Figure Description

[0033] Figure 1 This is a schematic diagram of the DC solid-state switch of the present invention;

[0034] Figure 2 This is a schematic diagram of the soft shutdown process state machine control flow of the present invention; Detailed Implementation

[0035] The specific embodiments of the present invention are further described below with reference to the accompanying drawings. The scope of protection of the present invention is not limited to the description of the following embodiments.

[0036] Existing DC solid-state switching devices typically include an isolation module, a control module, a drive module, and power switching transistors connected to the drive module. The isolation module is used to achieve complete isolation between the control side and the load side, preventing coupled noise from being transmitted to the control system. It receives DC control signals from the host controller or PLC, and electrically isolates and levels them through optocouplers or digital isolators. The module outputs a standard logic level, which is used to drive the input of the control module. The control module controls the drive module to output drive signals, thereby controlling the power switching transistors to turn on or off to achieve circuit control on the load side.

[0037] DC solid-state switching devices can be solid-state relays or solid-state circuit breakers, etc. Taking solid-state relays as an example, in the application scenarios of DC solid-state relays, there are many inductive loads, such as electromagnets, solenoid valves, DC motors, etc. Since the flyback energy of DC inductors does not have zero-crossing characteristics, unlike the naturally zero-crossing current in AC inductors, DC solid-state relays will generate extremely high inrush currents during the turn-off process. Existing technologies mainly suppress inrush currents by extending the turn-off process through soft turn-off, but this cannot adapt well to changes in operating conditions, resulting in low system efficiency, high switching losses, and / or the absorption branch absorbs and consumes the flyback energy, converting the energy into heat, which leads to problems such as large energy loss, heat concentration, and short lifespan. The absorption branch typically includes TVS diodes, RC absorption circuits, MOV varistors, etc., which are existing technologies in this field.

[0038] This invention provides a soft-shutdown control method for a DC solid-state switch and a DC solid-state switch. The soft-shutdown control method for the DC solid-state switch includes the following steps:

[0039] S1 receives the shutdown command and samples the load current. and switch drain-source voltage ;

[0040] S2, enter the soft shutdown process, control the drive signal to decrease to the shutdown threshold, and then output the shutdown signal to turn off the power switch.

[0041] like Figure 1 As shown, the DC solid-state switch of the present invention includes a signal sampling module, a control module, and a drive module. The drive module is connected to a power switching transistor. The control module executes the soft-turn-off control method of the DC solid-state switch. The signal sampling module is connected to the control module and is used to sample the load current. and switch drain-source voltage The signal is transmitted to the control module, which is connected to the drive module. The control module controls the drive module to output a drive signal, which in turn controls the power switch to turn on or off.

[0042] In step S1, when the DC solid-state switch is in saturation conduction state, the power switch is normally turned on. The turn-off command is input to the control module through the isolation module. After receiving the external turn-off command, the control module starts the subsequent turn-off control and simultaneously collects the load current in real time through the signal sampling module. Signal and switch drain-source voltage Signal.

[0043] Specifically, the collected load current and switch drain-source voltage Higher accuracy is better; preferably, the signal has undergone filtering processing, and the signal is equipped with filtering circuits, amplification circuits, and other processing circuits. Optionally, to obtain more accurate current and voltage signals, or when the signal sampling module does not have a filtering circuit, step S1.1 is executed to sample the current load current. and current switch drain-source voltage ,right and Sampling software filtering is performed to eliminate noise:

[0044] ;

[0045] ;

[0046] in, Represents the nth sampling point value, This represents the filtered sampled current (i.e., the load current signal). Represents the nth sampling point value, This represents the filtered sampled voltage (i.e., the switch drain-source voltage signal). and This represents the smoothing coefficient.

[0047] It should be noted that step S1.1 is an optional solution; any existing noise cancellation algorithm can also be used, or when setting up the filtering circuit, the control module can directly acquire the filtered sampled signal. and And use it as a parameter for subsequent algorithms.

[0048] Preferably, after the control module receives the shutdown command, it detects... > , This represents the minimum current threshold required to enable soft shutdown. The value can be selected based on the current carrying capacity of the solid-state switch. If the condition is met, proceed to S2. This indicates that the shutdown is a low-current shutdown, which can be done directly and quickly to avoid wasting system resources and improve the adaptability of solid-state switches to different usage scenarios and load types.

[0049] Step S2: Enter the soft shutdown process. After the control drive signal decreases to the shutdown threshold, the shutdown signal is output to turn off the power switch.

[0050] The soft turn-off refers to the process of gradually reducing the drive signal to the turn-off threshold during the turn-off process, thereby slowing down the rate of change of voltage and current, reducing switching losses, electromagnetic interference (EMI), and avoiding device damage caused by voltage overshoot or oscillation; after the drive signal is reduced to the turn-off threshold, a turn-off signal is output to turn off the power switch, which is the prior art in this field.

[0051] In the soft shutdown process, after the drive signal is gradually reduced to the shutdown threshold, a shutdown signal can be directly output to turn off the power switch. Alternatively, the shutdown signal can be output after other shutdown conditions are met; both are possible and fall within the scope of this application. For example, one implementation is to gradually reduce the duty cycle and / or gate voltage of the drive signal to the shutdown threshold and then directly output the shutdown signal to turn off the power switch. Another implementation is to gradually reduce the duty cycle and / or gate voltage of the drive signal to the shutdown threshold, delay for a certain period of time, and then output the shutdown signal to turn off the power switch. A preferred implementation is that after the drive signal is gradually reduced to the shutdown threshold, and the load current I... When the turn-off condition is met, a turn-off signal is output to turn off the power switch.

[0052] One embodiment of a soft shutdown process in which the drive signal is gradually reduced to a shutdown threshold is to use a fixed drive timing method to control the duty cycle of the drive signal and / or the gate voltage to decrease at a fixed rate of change until the shutdown threshold is reached, and output a shutdown signal after the threshold is reached. This is the prior art in this field and can also be called a single-stage or single-stage shutdown control method. However, this control method has the problem of poor adaptability and does not adjust to changes in load state.

[0053] Preferably, the soft shutdown process in step S2 of this embodiment is configured as a multi-level soft shutdown control method, with multiple soft shutdown stages Stg[n], or at least two soft shutdown stages Stg[n]. Each soft shutdown stage Stg[n] corresponds to a progressively decreasing duty cycle and / or gate voltage, so that the duty cycle and / or gate voltage of the drive signal are progressively decreased to a shutdown threshold according to the preset multiple soft shutdown stages Stg[n]. After reaching the shutdown threshold, a shutdown signal is output, thereby realizing multi-level shutdown control of the power switch. The multiple soft shutdown stages include Stg[1], Stg[2], ..., Stg[n], Stg[n+1], Stg[n+2], each soft shutdown stage Stg[n] corresponds to a progressively decreasing duty cycle and / or gate voltage (gate drive duty cycle and / or gate voltage), used to form a multi-level soft shutdown control method. Stg[n] represents the nth soft shutdown stage.

[0054] For example, in one embodiment, the soft turn-off stages Stg[1], Stg[2], ..., Stg[n], Stg[n+1], and Stg[n+2] correspond to progressively decreasing gate drive duty cycles. For instance, if the preset PWM gate drive duty cycle change sequence is 100%→80%→50%→20%→0%, then each soft turn-off stage Stg[n] corresponds to a gate drive duty cycle that decreases to the value of the corresponding soft turn-off stage.

[0055] One implementation involves a one-to-one correspondence between the multiple soft shutdown stages Stg[n] and multiple time lengths Tn. The control module maintains the corresponding time length Tn at the point where the control drive signal decreases to the soft shutdown stage Stg[n], then enters the next soft shutdown stage Stg[n+1] and maintains the corresponding time length Tn+1, repeating this process. For example, soft shutdown stages Stg[1], Stg[2], ..., Stg[n], Stg[n+1], and Stg[n+2] correspond to time lengths T1, T2, ..., Tn, Tn+1, and Tn+2, respectively. After the control drive signal abruptly decreases in a discrete manner to the gate drive duty cycle of the corresponding soft shutdown stage Stg[n] and outputs the corresponding time length Tn, the control module adjusts the gate drive duty cycle to the gate drive duty cycle of the next soft shutdown stage Stg[n+1] and outputs the corresponding time Tn+1 for the next soft shutdown stage. The soft shutdown process is controlled by a fixed drive timing. Specifically, upon receiving a turn-off command, the control module outputs a drive signal with a 100% duty cycle for time T1. Then, it abruptly reduces the gate drive duty cycle to 80%, maintains this position for time T2, then abruptly reduces it to 50%, maintains it for time T3, and then abruptly reduces it to 20%. This cycle repeats until the gate drive duty cycle reaches 0%, achieving soft turn-off through multiple time sequences. It should be noted that the preset PWM gate drive duty cycle change sequence can be adjusted as needed. The time length Tn corresponding to each soft turn-off stage Stg[n] can be the same or different; for example, the preset PWM gate drive duty cycle change sequence can be 80%→50%→20%→0%, or T1 can be 0. Preferably, at least two soft turn-off stages have different time lengths Tn corresponding to Stg[n].

[0056] Another implementation involves linearly decreasing the gate drive duty cycle of Stg[1], Stg[2], ..., Stg[n], Stg[n+1], and Stg[n+2] at corresponding rates to the gate drive duty cycle of the corresponding soft turn-off stage. Then, the gate drive duty cycle is linearly decreased at the rate corresponding to the next soft turn-off stage until the drive signal decreases to the turn-off threshold. For example, the first rate can be distinguished based on the different soft turn-off stages of the gate drive duty cycle change rate. Second speed …the nth rate According to the first rate Reduce the duty cycle from 100% to 80%, then proceed with the second rate. The duty cycle is reduced from 80% to 50%, and so on until the shutdown threshold is reached. It should be noted that the first rate... Second speed …the nth rate The rates can be the same or different, but preferably there are at least two different rates. Different rates of change are used in different soft turn-off phases to avoid device damage caused by voltage overshoot or oscillation.

[0057] In another embodiment, the soft turn-off stages Stg[1], Stg[2], ..., Stg[n], Stg[n+1], Stg[n+2] correspond to progressively decreasing gate voltages. The control module controls the drive module to output a drive signal to reduce the gate voltage to the corresponding soft turn-off stage gate voltage and maintain it for the corresponding duration T1, T2, ..., Tn, Tn+1, Tn+2. Then, the gate voltage is adjusted to the gate voltage value corresponding to the next soft turn-off stage and maintained for the corresponding time of the next soft turn-off stage until the drive signal decreases to the turn-off threshold.

[0058] In another embodiment, the soft turn-off stages Stg[1], Stg[2], ..., Stg[n], Stg[n+1], Stg[n+2] correspond to the progressively decreasing duty cycle and gate voltage of the drive signal. After the duty cycle and gate voltage of the drive signal are reduced to the corresponding soft turn-off stage duty cycle and gate voltage maintained for the corresponding duration T1, T2, ..., Tn, Tn+1, Tn+2, the duty cycle and gate voltage of the next soft turn-off stage are adjusted to maintain the corresponding duration of the next soft turn-off stage until the drive signal decreases to the turn-off threshold.

[0059] The multi-stage soft shutdown control method of the power switch described above has a better effect on surge suppression than single-step shutdown when applied to inductive loads, but it cannot adapt to changes in operating conditions. If the preset drive timing is not compatible with the current load conditions, there will still be problems with surges and electromagnetic interference, and the soft shutdown process cannot be adaptively adjusted under different operating conditions.

[0060] To address the aforementioned issues, one improvement of this application is that, in step S2, while employing a multi-level soft-shutdown control method, a stage index S[n] is calculated based on sampled feedback information to dynamically determine the timing for entering the next soft-shutdown stage Stg[n+1]. After the drive signal decreases to the duty cycle and / or gate voltage of the current soft-shutdown stage Stg[n], the duty cycle and / or gate voltage output is maintained. If the stage index S[n] is detected to be greater than the stage advancement threshold, further improvements are made. If the current changes within the soft turn-off phase Stg[n+1] are not adjusted, the drive signal is reduced to the duty cycle and / or gate voltage corresponding to the next soft turn-off phase Stg[n+1]. By adjusting the soft turn-off process in real time, the current change rate is kept within a controllable range, which suppresses surges, reduces electromagnetic interference, and improves the system's turn-off reliability and electromagnetic compatibility.

[0061] In this embodiment, the control module obtains the current change rate based on the sampled information. and backflash energy and based on , , and The stage index S[n] is calculated. After the drive signal decreases to the duty cycle and / or gate voltage of the current soft turn-off stage Stg[n], the stage index S[n] is used to determine whether the soft turn-off process has moved from the soft turn-off stage Stg[n] to the next soft turn-off stage Stg[n+1]. The gate drive duty cycle / gate voltage is controlled to decrease, which is used to form a multi-stage soft turn-off control mode.

[0062] The formula for calculating the stage index S[n] is as follows:

[0063] S[n]= ;

[0064] or

[0065]

[0066] in, , , , For constant coefficients, 0 , , , 1, + ; The rate of change of current, Indicates the retrace energy. TH2 is a constant, and is used for the reaction. and level; The preferred value range is 5-20 A / µs; the preferred value range for TH2 is 0.1-1 J. Indicates the rated current. Represents bus voltage; The time window representing the sampling period is determined by the sampling frequency. For example, when the sampling frequency is 100kHz... =10μs. It should be noted that the above-mentioned formula for calculating the stage index S[n] is a preferred embodiment of this application. Those skilled in the art can modify and adjust it appropriately. For example, if a certain constant coefficient is selected as 0, a reference factor can be removed, or a certain reference factor can be replaced with a reference factor with a similar meaning.

[0067] After the drive signal decreases to the duty cycle and / or gate voltage of the current soft-turn-off stage Stg[n], if the current stage exponent S[n] > stage advance threshold... If the current soft turn-off condition is met, the next soft turn-off stage Stg[n+1] is entered; otherwise, the current soft turn-off stage Stg[n] is maintained. After entering the next soft turn-off stage Stg[n+1], the drive signal is reduced to the duty cycle and / or gate voltage of the soft turn-off stage Stg[n+1], and the current stage exponent S[n+1] is sampled and calculated, satisfying S[n+1] > 0. Then, it enters the next soft-shutdown stage, Stg[n+2], reducing the gate drive duty cycle / gate voltage until the drive signal decreases to the shutdown threshold. This forms a multi-level soft-shutdown control mode that adapts to the current operating conditions. The stage advancement threshold is... The selected range is 0.8-1.2.

[0068] Specifically, in one embodiment, the gate drive duty cycles corresponding to the soft shutdown stages Stg[1], Stg[2], ..., Stg[n], Stg[n+1], and Stg[n+2] are progressively decreasing. For example, the preset PWM gate drive duty cycle change sequence is 100%→80%→50%→20%→0%. After entering the soft shutdown process, the control module adjusts the gate drive duty cycle to the duty cycle of the next soft shutdown stage (either by sudden drop or linear reduction). At the same time, it performs parameter sampling and calculates the stage index S[n] in a fixed sampling period, and compares the stage index S[n] with the stage advancement threshold. In comparison, if the stage index S[n] > the stage advancement threshold... If the gate drive duty cycle is reduced from 100% to 80%, the next soft shutdown stage Stg[n+1] will begin. For example, if the preset PWM duty cycle change sequence is 100%→80%→50%→20%→0%, and the control module reduces the gate drive duty cycle from 100% to 80%, the control module calculates the stage exponent S[n] in real time. If S[n] < The control module does not perform any further actions, maintaining the soft shutdown process at the current soft shutdown stage Stg[n]. If S[n] > The control module advances the soft shutdown process to the next soft shutdown stage Stg[n+1], outputs a drive signal to reduce the gate drive duty cycle from 80% to 50%, and samples and calculates the stage index S[n+1] in real time, repeating the above steps until the shutdown condition is met.

[0069] As another embodiment, the soft turn-off stages Stg[1], Stg[2], ..., Stg[n], Stg[n+1], and Stg[n+2] correspond to progressively decreasing gate voltages. After entering the soft turn-off process, the control module controls the drive module to output a drive signal to reduce the gate voltage to the gate voltage of the corresponding soft turn-off stage Stg[n]. At the same time, the stage index S[n] is calculated and monitored. If the stage index S[n] < the stage advancement threshold... The control module does not take any further action, maintaining the soft shutdown process at the current soft shutdown stage Stg[n]. If the stage exponent S[n] > the stage advancement threshold... If the gate voltage is reduced to the gate voltage of the corresponding soft turn-off stage Stg[n+1], the stage exponent S[n+1] is sampled and calculated in real time, and the above steps are repeated until the turn-off condition is met.

[0070] As another embodiment, the soft turn-off stages Stg[1], Stg[2], ..., Stg[n], Stg[n+1], and Stg[n+2] correspond to progressively decreasing duty cycles and gate voltages of the drive signals. After entering the soft turn-off process, the control drive module outputs drive signals to reduce the duty cycle and gate voltage of the gate drive to the corresponding duty cycle and gate voltage of the soft turn-off stage Stg[n]. At the same time, the stage index S[n] is calculated and monitored. If the stage index S[n] < the stage advancement threshold... The control module does not take any further action, maintaining the soft shutdown process at the current soft shutdown stage Stg[n]. If the stage exponent S[n] > the stage advancement threshold... If the conditions are met, the next soft turn-off stage Stg[n+1] will be entered. The output drive signal will reduce the duty cycle and gate voltage of the drive signal to the duty cycle and gate voltage of the corresponding soft turn-off stage Stg[n+1]. The stage index S[n+1] will be sampled and calculated in real time. The above steps will be repeated until the turn-off condition is met.

[0071] The soft-turn-off control method for DC solid-state switches of the present invention, compared with the control method of preset drive timing according to the worst-case operating conditions in the prior art, can advance the soft-turn-off stage more quickly when the operating conditions are good, significantly reducing switching losses and improving system efficiency. By adaptively advancing the soft-turn-off stage, it avoids surge and electromagnetic interference problems caused by the mismatch between the operating conditions and the preset drive timing. It can cope with more complex operating conditions, realize adaptive adjustment of the soft-turn-off process under different operating conditions, and improve system robustness.

[0072] Furthermore, in the multiple soft shutdown stages Stg[n] of the soft shutdown process, different gate driving laws G[n] are adopted respectively, and the gate driving laws G[n] are configured as follows:

[0073] G[n] = βG[n-1] + (1-β)

[0074] Wherein, G[n] is the gate drive law of the nth soft turn-off stage, representing the gate drive control quantity, which is mapped to the gate drive duty cycle or gate voltage level and is used to generate graded drive signals; β represents the smoothing / inertia coefficient, which preferably takes a value range of 0-1, and is used to make the gate drive control quantity update in a gradual manner to avoid the current change rate being too large due to sudden changes. The preset target gear coefficients (corresponding to 80%, 50%, and 20% duty cycle change levels) are preferred, with value ranges such as g1∈(0.6,0.9), g2∈(0.3,0.6)..., used to form a multi-level soft-shutdown control mode. Of course, as other degraded embodiments, the same gate drive law can also be used in multiple soft-shutdown stages Stg[n], which also falls within the protection scope of this application.

[0075] Preferably, after the gate drive duty cycle and / or gate voltage decrease to the turn-off threshold, i.e., after the final soft turn-off stage Stg[end], the final stage exponent S[end] is also calculated. When the final stage exponent S[end] ≥ When the turn-off condition is met, a turn-off signal is output; where Preferred selection or slightly higher For example, a value of 1.0-1.3 can be used to avoid critical fluctuations. Furthermore, the load current I can be monitored, i.e., when the gate drive duty cycle and / or gate voltage decrease to the turn-off threshold D. Th Then, when the final stage index S[end] ≥ And the load current I When the shutdown condition is met, a shutdown signal is output. The preferred value range is 0.05~0.2A.

[0076] Preferably, another improvement of this application is that, in step S2, while adopting the multi-level soft shutdown control method, current change rate monitoring and enhanced attenuation control are also performed, that is, entering the enhanced attenuation state.

[0077] In another embodiment, step S2 includes step S2.1, where the soft shutdown process is configured as a multi-level soft shutdown control method, with multiple soft shutdown stages Stg[n]. Each soft shutdown stage Stg[n] corresponds to a progressively decreasing duty cycle and / or gate voltage, causing the duty cycle and / or gate voltage of the drive signal to progressively decrease to the shutdown threshold according to the preset multiple soft shutdown stages Stg[n]. Simultaneously, the control module also considers the load current... and / or switch drain-source voltage Calculate the soft shutdown control index Z[n]. If the soft shutdown control index Z[n] exceeds the preset adjustment threshold, proceed to step S2.2. If the soft shutdown control index Z[n] does not exceed the preset adjustment threshold, continue to cycle within S2.1 until the power switch is completely turned off.

[0078] Step S2.2 includes adjusting the plurality of soft turn-off stages Stg[n] to generate and enter a new soft turn-off stage Stg[ad]. The duty cycle and / or gate voltage corresponding to the soft turn-off stage Stg[ad] is less than the duty cycle and / or gate voltage corresponding to the current soft turn-off stage Stg[n]. Further, the duty cycle and / or gate voltage corresponding to the soft turn-off stage Stg[ad] is greater than or equal to the duty cycle and / or gate voltage corresponding to the next soft turn-off stage Stg[n+1].

[0079] Compared to the previous embodiment, where multiple soft-shutdown stages Stg[n] were preset and unadjustable, the multi-level soft-shutdown control method in this embodiment further determines whether to adjust the current soft-shutdown stage Stg[n] based on the detected soft-shutdown control index Z[n]. This involves adjusting the duty cycle and / or gate voltage corresponding to the current soft-shutdown stage Stg[n] to the duty cycle and / or gate voltage corresponding to the soft-shutdown stage Stg[ad]. The duty cycle and / or gate voltage corresponding to the soft-shutdown stage Stg[ad] is less than the current soft-shutdown stage Stg[n], but greater than or equal to the next soft-shutdown stage Stg[n+1]. If the soft-shutdown stage Stg[ad] is equal to the next... The soft-shutdown phase Stg[n+1] can be understood as directly entering the soft-shutdown phase Stg[n+1] without waiting for the phase index S[n], with Stg[ad] replacing the soft-shutdown phase Stg[n+1]. If the duty cycle and / or gate voltage corresponding to Stg[ad] is greater than the duty cycle and / or gate voltage corresponding to the next soft-shutdown phase Stg[n+1], then Stg[ad] replaces the current soft-shutdown phase Stg[n], reducing the duty cycle and / or gate voltage of the drive signal to the duty cycle and / or gate voltage corresponding to Stg[ad], and then waiting for the phase index S[n] to determine whether to enter the soft-shutdown phase Stg[n+1]. This allows for dynamic adjustment of multiple soft-shutdown phases to enhance attenuation control, suppress surges, and reduce electromagnetic interference.

[0080] Preferred, soft shutdown phase The corresponding duty cycle and / or gate voltage are calculated as follows:

[0081] ;

[0082] in, The step size represents the stage size and can be a pre-set constant. Pick and The larger value in the range.

[0083] Specifically, in one embodiment, the soft turn-off stages Stg[1], Stg[2], ..., Stg[n], Stg[n+1], and Stg[n+2] correspond to progressively decreasing gate drive duty cycles. For example, if the preset PWM gate drive duty cycle change sequence is 100%→80%→50%→20%→0%, and assuming that the gate drive duty cycle corresponding to the current soft turn-off stage Stg[n] is 80%, then if the control module detects that the stage exponent S[n] < the stage advancement threshold... If the soft shutdown control index Z[n] exceeds the preset adjustment threshold, then the soft shutdown stage Stg[ad] is generated and enters the soft shutdown stage. If the gate drive duty cycle corresponding to Stg[ad] is 50%, that is, Stg[ad] = Stg[n+1], it is equivalent to Stg[ad] replacing the soft shutdown stage Stg[n+1]. After entering Stg[ad], the control module continues to sample and calculate the stage index S[n+1] in real time. If the stage index S[n+1] > the stage advancement threshold, the soft shutdown stage Stg[ad] is entered. If the gate drive duty cycle of Stg[ad] is 40%, which is less than 50% of Stg[n+1], then Stg[ad] is set to 50%, which means that Stg[ad] still replaces the soft shutdown stage Stg[n+1] and enters Stg[n+1]. If the gate drive duty cycle of Stg[ad] is 60%, which is greater than 50% of Stg[n+1], after entering Stg[ad], the control module reduces the duty cycle of the control drive signal to 60%, which can also be understood as Stg[ad] replacing the soft shutdown stage Stg[n]. The control module continues to sample and calculate the stage index S[n] in real time. If the stage index S[n] > the stage advancement threshold, then the control module will proceed to the next soft shutdown stage Stg[n+2], with a corresponding gate drive duty cycle of 20%. If the current condition is met, then proceed to the next soft shutdown phase Stg[n+1].

[0084] In another embodiment, the plurality of soft-shutdown stages Stg[n] still correspond to progressively decreasing gate drive duty cycles. The gate drive duty cycle corresponding to the current soft-shutdown stage Stg[n] is 80%. When the control module detects that the stage exponent S[n] is less than the stage advancement threshold... If the soft-shutdown control index Z[n] exceeds the preset adjustment threshold, then the soft-shutdown stage Stg[ad] is generated and entered. The current gate drive duty cycle is linearly reduced from 80%, and Z[n] and the adjustment threshold are monitored in real time. When Z[n] is detected to be less than the adjustment threshold, the reduction of the current gate drive duty cycle is stopped. At this time, the soft-shutdown stage is Stg[ad], and the corresponding gate drive duty cycle is a non-fixed value, such as being in the range of 60%-50%. After entering Stg[ad], the control module continues to sample and calculate the stage index S[n+1] in real time and execute subsequent control. Optionally, when Stg[ad] and Stg[n] are not equal, the control module can continue to sample and calculate the stage index S[n] in real time, and then reduce the gate drive duty cycle from the value in the range of 60%-50% to 50% when the judgment condition is met.

[0085] As another embodiment, Stg[1], Stg[2], ..., Stg[n], Stg[n+1], Stg[n+2] correspond to gate voltages that decrease progressively. When the control module detects that the stage exponent S[n] < the stage advancement threshold, If the soft shutdown control index Z[n] exceeds the preset adjustment threshold, then the soft shutdown stage Stg[ad] is generated and enters, and Stg[n+1]≤Stg[ad]<Stg[n]. Alternatively, the gate voltage is linearly reduced from the current soft shutdown stage until Z[n] is detected to be less than the adjustment threshold. After entering Stg[ad], subsequent control is continued.

[0086] As another embodiment, Stg[1], Stg[2], ..., Stg[n], Stg[n+1], Stg[n+2] correspond to the duty cycle and gate voltage of the driving signal that decreases step by step. When the control module detects that the stage exponent S[n] < the stage advancement threshold, If the soft shutdown control index Z[n] exceeds the preset adjustment threshold, then the soft shutdown stage Stg[ad] is generated and entered, and Stg[n+1]≤Stg[ad]<Stg[n]. Alternatively, the duty cycle of the gate drive and the gate voltage are linearly reduced from the current soft shutdown stage until Z[n] is detected to be less than the adjustment threshold. At this time, the soft shutdown stage is Stg[ad]. After entering Stg[ad], subsequent control continues to be executed.

[0087] As another embodiment, step S2.2 further includes slope closed-loop control, which adaptively adjusts the stage step size according to the current change rate. The slope closed-loop control formula is:

[0088] Stg ;

[0089] =clip( , );

[0090] Here, clip() is the clipping function. This is the proportionality coefficient. and Used for setting The lower and upper limits, and The value is determined based on system characteristics and / or the configured soft shutdown phase. Indicates the step size of the stage.

[0091] At this point, Stg[ad] is the soft shutdown stage with adaptive configuration. The soft shutdown stage is adaptively configured as Stg[n], Stg[ad], Stg[n+2]. Of course, the soft shutdown stage can also be adaptively configured as Stg[n], Stg[ad], Stg[n+1], Stg[n+2]. In this way, through slope closed-loop control, voltage spikes are dynamically suppressed, providing a stronger ability to cope with load changes. The current change rate is dynamically sensed and the stage step size is adjusted, which more proactively and timely responds to overvoltage risks and improves safety.

[0092] For example: when Stg[1], Stg[2], ..., Stg[n], Stg[n+1], Stg[n+2] correspond to gate drive duty cycles D[n] that decrease step by step:

[0093] D ;

[0094] =clip( , ).

[0095] Furthermore, the soft-shutdown control index Z[n] includes the rate of change of current. and / or energy integral :

[0096] One implementation method is the rate of change of current. The soft-shutdown control exponent Z[n] is calculated using the following formula:

[0097] ;

[0098] In another embodiment, energy integration The formula for calculating the soft-shutdown control exponent Z[n] is as follows:

[0099] = ;

[0100] or, ;

[0101] In another preferred embodiment, the reference current change rate is also considered. and energy integral As a soft-shutdown control exponent Z[n], such as:

[0102] Soft shutdown control exponent Z[n] = k4 + k5 ,

[0103] Among them, k4 and k5 are constant coefficients used to adjust the weight of each parameter. The range of k4 and k5 is usually from 0 to 1, and can also be 0 or 1. When it is 0, it means that a certain condition is omitted.

[0104] When the rate of change of current When Z[n] is the soft-shutdown control exponent, the adjustment threshold is: , The value ranges from 8A / µs to 12A / µs, with a preferred typical value of 10A / µs. In step S2.1, the control module monitors the rate of change of current in real time. When the rate of change of current is detected Adjust threshold When the current is turned off, step S2.2 is executed, and the soft turn-off process is advanced from Stg[n] to Stg[ad] to further reduce the gate drive duty cycle and / or gate voltage, forming a smoother current drop curve. The gate drive duty cycle and / or gate voltage decrease from the current stage to the next stage in a limited step size. By reducing the gate drive duty cycle and / or gate voltage, the equivalent on-resistance of the power switch increases, and the load current transfer process becomes smoother, thereby reducing the current drop. Limiting the current drop curve to near the threshold achieves a smoother current drop curve and reduces surge / EMI. Then, in step S2.2, the duty cycle and / or gate voltage are gradually reduced according to the adjusted soft turn-off stage, or the process returns to step S2.1 to gradually reduce the duty cycle and / or gate voltage according to the adjusted soft turn-off stage.

[0105] When When Z[n] is the soft-shutdown control exponent, the adjustment threshold is: Adjust the threshold The preferred value range is 0.01-0.2J, which can be calibrated according to the bus voltage and / or load current level. If... If the soft turn-off control index Z[n] exceeds the adjustment threshold, step S2.2 is executed, and the soft turn-off process is advanced from Stg[n] to Stg[ad] to further reduce the gate drive duty cycle and / or gate voltage, forming a smoother current drop curve. Then, in step S2.2, the duty cycle and / or gate voltage are gradually reduced according to the adjusted soft turn-off stage, or the process returns to step S2.1 to gradually reduce the duty cycle and / or gate voltage according to the adjusted soft turn-off stage.

[0106] Furthermore, another improvement of the DC solid-state switch of the present invention is that it also includes an energy recovery module, which is connected to the power switch tube. The control module controls the energy recovery module to open or close during the soft shutdown process to recover or stop energy recovery.

[0107] The soft-turn-off control method for the DC solid-state switch further includes step S3, during the soft-turn-off process, based on the load current... and switch drain-source voltage Calculate the energy index E[n], monitor the energy index E[n], and if the energy index E[n] exceeds the recovery threshold, activate the energy recovery path to import energy into the energy storage feedback unit.

[0108] Compared to existing technologies that use parallel, indiscriminate discharge paths (such as parallel TVS diodes) to protect the circuit, the soft-shutdown control method of the DC solid-state switch of this invention triggers energy discharge whenever a shutdown action occurs, leading to significant heat generation and heat loss in the components within the discharge path. This application sets up a controllable energy recovery path, continuously monitoring the energy index E[n] during the shutdown process. When the energy index E[n] exceeds the recovery threshold, placing the system in a high-risk area, energy recovery is triggered, and energy is introduced into the energy storage feedback unit. This not only avoids unnecessary heat generation but also recovers energy and reduces losses. In high-frequency shutdown scenarios such as low current or motor control via PWM, when the energy index E[n] is below the recovery threshold, the energy recovery path remains off, improving the system efficiency and reliability of the DC solid-state switch.

[0109] The calculated energy index E[n] includes the flyback energy. and / or switch drain-source voltage The energy will be swept back. As the energy index E[n], or the switching drain-source voltage It can be used as the energy index E[n], or a combination of the two can be used as the energy index E[n].

[0110] Calculate the backflush energy The methods include:

[0111] According to the formula = Calculate; or according to the formula Calculate; or use a discrete estimation form model;

[0112] The discrete estimation form model can be pre-stored with "equivalent inductance" "Look up the table: based on the start-up current of the shutdown function." With the rate of change of current The index is divided into sections to find the corresponding equivalent inductance. Then, the backflush energy is estimated according to the formula:

[0113] ;

[0114] For example, The range is divided into 1A / 3A / 5A / 10A. The gradations are 2 / 5 / 10 / 20, with units of A / µs, as shown in the table. (Values ​​are 10mH, 30mH, 50mH, and 80mH), the control module operates according to the sampled values ​​( , Select the most recent gear or the median value to obtain the result. .

[0115] In one implementation, the backflush energy is used. As the energy index E[n], the recovery threshold is TH2, and TH2 is used for the reaction. The energy recovery path is in a closed state during the initial stage of circuit conduction and soft shutdown, and the control module monitors it in real time during the soft shutdown process. When detected At TH2, the energy recovery path is activated, directing energy into the energy storage feedback unit. Furthermore, the control module continuously monitors the current during the energy recovery process. When detected < When the energy recovery path is closed, the The recycling shutdown threshold represents the low current threshold, which is preferred. The value range is 0.05-0.2A.

[0116] In another implementation, with As an energy index E[n], it is generally only used in simple systems as a simplified trigger indicator, and the recovery threshold is... During soft shutdown, if Then the energy recovery path is activated, in which, This is a constant coefficient, with a value range of 1.1-1.3. This represents the bus voltage. Furthermore, the control module continuously monitors the current during the energy recovery process. When detected < The energy recovery path is closed at that time.

[0117] In another preferred embodiment, As the main condition for obtaining the energy index E[n] and As an auxiliary condition, the energy index E[n] is used to balance energy risk and voltage risk.

[0118] ;

[0119] ;

[0120] Among them, k1, k2, and k3 are constant coefficients used to adjust the weight of each parameter. The range of k1, k2, and k3 is usually from 0 to 1, or it can be 0 or 1. When it is 0, it means that a certain condition is omitted.

[0121] The recovery threshold is determined by a weighted average of the calculation formula for the energy index E[n], that is, k1, k2, and k3 are increased by a certain value and then compared with TH2, ... , The product is multiplied and then added together to determine the result. TH2 and TH2 are used for the reaction respectively and level, The preferred value range is 5-20 A / µs. When the detected energy index E[n] exceeds the recovery threshold, the energy recovery path is activated, and energy is introduced into the energy storage feedback unit. Furthermore, the control module continuously monitors the current during the energy recovery process. When detected < The energy recovery path is closed at that time.

[0122] In another embodiment, the energy index E[n] can also be compared to determine if it exceeds a recycling threshold, for example, if it meets the following conditions. >TH2, and The energy recovery path is activated at the appropriate time, or, >TH2, and , The energy recovery path is activated when one of them is established.

[0123] Furthermore, to address risks in the energy recovery path such as "reverse backfeed / abnormal rise in bus voltage", in step S3, during the activation of the energy recovery path, the current polarity and bus voltage level are monitored in real time. If an abnormal reverse current or an abnormal rise in bus voltage is detected, the energy recovery path is cut off, the absorption branch is activated, and the power switch is locked in the off state.

[0124] In this embodiment, if I < the first reverse current threshold (-) is detected at least three times consecutively, That is, at least three consecutive detections of I < - This is considered to indicate the generation of an abnormal reverse current; the first reverse current threshold is... It is a constant, calibrated according to the rated current, such as Of course, as another embodiment, it is also possible to detect I <- once or twice consecutively. It is assumed that abnormal reverse current is also within the scope of protection of this application, but this setting is prone to false alarms.

[0125] If detected First bus abnormal threshold, or If the second busbar abnormal threshold is reached, the busbar voltage is considered to have risen abnormally. The first busbar abnormal threshold is a constant, based on the rated busbar voltage. Calibration, for example, the abnormal threshold of the first bus is + , Rated bus voltage, Second busbar abnormal threshold It can be calibrated according to the sampling frequency.

[0126] After activating the energy recovery path, the control module will monitor the current switching drain-source voltage of the main circuit in real time. And current polarity, when reverse current and / or abnormal rise in bus voltage are detected, leading to A rapid increase in voltage indicates an overvoltage caused by energy backflow, with the flyback energy exceeding the capacity of the energy recovery path. In this case, the control module immediately shuts down the energy recovery path and activates the absorption branch, which absorbs and dissipates the flyback energy. Furthermore, the power switch can be locked in the off state to prevent re-triggering. The absorption branch can be a TVS diode, an RC absorption circuit, an MOV varistor, etc., and is existing technology in this field. Thus, a safety protection mechanism is applied to the soft turn-off process and energy recovery process of the DC solid-state switch. In the event of a fault, a protection mode is entered, cutting off the energy recovery path, turning off and locking the power switch, and reliably absorbing the surge current through the absorption branch, ensuring the safety and reliability of the turn-off process.

[0127] Preferably, the energy storage feedback unit is a capacitor or a battery. In this embodiment, the energy storage feedback unit is a capacitor, and the capacitance value is preferably 1-50F. When the energy storage feedback unit includes a capacitor, to prevent the capacitor of the energy storage feedback unit from being damaged by overvoltage during the energy recovery process, the control module raises the short-circuit voltage threshold while activating the energy recovery path. :

[0128] ;

[0129] in, Represents system efficiency. Represents surge current. Represents the effective capacitance; Represents a time window. Used to indicate the rise in capacitor voltage during energy recovery.

[0130] When predicting capacitor voltage When the capacitor voltage exceeds the protection threshold, the capacitor is deemed to be at risk of damage. The capacitor voltage protection threshold can be the upper limit of the capacitor voltage. or more than 0.9 ;in:

[0131]

[0132] If the capacitor is determined to be at risk of damage: immediately reduce the energy recovery ratio, or directly cut off the energy recovery path and start the absorption branch to consume the remaining flyback energy, while turning off the power switch; furthermore, it can enter the protection latch state to lock the power switch in the off state to prevent the power switch from being retriggered.

[0133] The energy recovery path includes an energy recovery switch, which can be used to open or close the energy recovery path. At the same time, by adjusting the duty cycle of the drive signal of the energy recovery switch, the energy flowing to the branch of the energy recovery path can be adjusted, thereby reducing or increasing the energy recovery ratio.

[0134] Furthermore, the soft-turn-off control method for the DC solid-state switch in this embodiment also includes step S4, which involves entering a protection latching state after turning off the power switch, i.e., the power switch enters a time-delay protection period. During the extended protection period The power switch is locked in the off state, preventing it from being triggered again within the current control cycle. Preferably, the... The optimal time interval is selected based on the time interval between the current control cycle and the next control cycle. That is, the power switch is prohibited from being triggered again within the current control cycle until the next control cycle. This is to deal with problems such as "current polarity reversal / re-triggering in the same sampling cycle" or system jitter that cause the power switch to be falsely triggered.

[0135] Preferably, in step S4, after turning off the power switch, within the time window Internal detection Only then is the protection latch triggered, entering the protection latch state, causing the power switch to enter the delay protection period. During the extended protection period The power switch transistor must not be turned on again. This indicates the presence of opposite polarity currents within the same sampling period. Preferably, the energy recovery path is shut down simultaneously with the power switch entering the protection latch state.

[0136] The soft turn-off control method for DC solid-state switches of the present invention, compared with the existing technology where the rate of change of current at the turn-off moment of inductive load is difficult to control due to the continuous discharge path, uses an openable energy recovery path in conjunction with a multi-stage soft turn-off control mode to monitor the soft turn-off control index Z[n] and energy index E[n] in real time. When the rate of change of current is higher than expected, the soft turn-off process is adjusted in real time to keep the rate of change of current within a controllable range, suppressing surges while reducing electromagnetic interference, and improving the system turn-off reliability and electromagnetic compatibility.

[0137] like Figure 1 As shown, in this embodiment, the DC solid-state switch comprises an isolation module, a control module, a drive module, a power switch, and a load module connected in sequence. The control module is connected to the energy recovery module, which in turn is connected to the power switch. During the soft-shutdown process, the control module controls the energy recovery module to open or close to recover or stop energy recovery. Preferably, the DC solid-state switch further includes an absorption branch connected to the power switch for absorbing consumed flyback energy.

[0138] The control module is used to execute the soft shutdown control method of the DC solid-state switch. The control module is equipped with a main controller, which can be a control unit such as an MCU, FPGA or DSP.

[0139] The power switching transistors in this embodiment include two parallel MOSFETs. Their gates are controlled by the main controller's PWM through isolation and amplification via a driver chip (IR2101, TC4420, etc.) within the driver module. The MOSFETs are N-channel MOSFETs (such as IPB180N10S4 or CSD19536KTT). Of course, the power switching transistors can also be IGBTs or other switching devices. When the system operating frequency is high or lower losses are required, other components such as SiC or GaN FETs can also be used. All of the above components are existing technologies.

[0140] The signal sampling module is connected to the control module and is used to sample the switch drain-source voltage in real time. and load current ,form , The sampling information includes current sampling, which can be achieved through a Hall sensor, current transformer, or a combination of shunt resistor and operational amplifier. Voltage sampling can be achieved through resistor voltage division, optical voltage detection, or differential amplification. This application does not impose any limitations on these methods. Preferably, the sampling frequency of the signal sampling module is 100kHz, adjustable within the range of 50-250kHz, to ensure the accuracy of capturing the turn-off transient waveform. The sampling information is sent to the control module after AD conversion, and the resolution is preferably set to 10-12 bits.

[0141] The energy recovery module is connected to the power switch and is driven and controlled by the control module. The control module controls the energy recovery module to open or close during the soft shutdown process, which is used to provide a dynamically enabled energy recovery path. When a high energy backfetch trend is detected during the soft shutdown process, that is, when the energy index E[n] exceeds the recovery threshold, the control module opens the energy recovery path and transfers the backfetched energy to the energy storage feedback unit.

[0142] The energy recovery module includes an energy recovery switch, an energy detection circuit, and an energy storage feedback unit. The energy recovery switch is controlled by the control module, and the energy storage feedback unit is used to transfer flyback energy. The energy recovery switch is an independent switching element that can open or close the energy recovery path. It can be turned on or off independently by the control module based on the energy index E[n]. This makes the energy recovery module, drive module, and power switch not directly connected in parallel. The module has a controllable connection with the drive module and power switch, rather than a permanently closed fixed connection. Unlike traditional TVS and RC absorption schemes, energy recovery is only triggered when the flyback energy exceeds a threshold and puts the system at high risk. When the flyback energy is within the system's tolerance range, the energy recovery path remains off to avoid unnecessary heat generation and energy loss.

[0143] In this embodiment, the energy recovery switch is a MOSFET. By adjusting the duty cycle of the drive signal of the energy recovery switch, the proportion of energy flowing to the branch of the energy recovery path can be adjusted. The energy storage feedback unit can be adjusted and replaced according to different application scenarios, and this application does not impose any restrictions. For example, when the solid-state switch is applied to a short-time high-current scenario, an energy storage inductor can be selected as the energy storage feedback unit. The flyback energy is first transferred to the inductor and then introduced to the bus through DC-DC conversion. When the load needs to be frequently switched on and off, a small lithium battery or battery pack can be selected as the energy storage feedback unit. The energy release time is extended at the control algorithm to achieve slow charging and slow discharging. Alternatively, a separate synchronous boost DC-DC structure can be used to boost the energy and feed it back to the bus, or a parallel energy storage bus structure can be used to set up multiple solid-state switch modules to share the recovery bus.

[0144] Optionally, multiple solid-state switch modules can be connected in parallel to share a set of energy recovery modules and their controllers. Each solid-state switch module independently executes a soft shutdown process to achieve centralized energy management and multi-channel protection. Alternatively, in a multi-channel control system, the energy recovery module and the control module can be arranged separately and coordinated for control through bus communication.

[0145] Preferred, such as Figure 2As shown, the control module has a built-in state machine control logic that dynamically adjusts the gate control output PWM waveform based on the sampled signal. The soft shutdown control method of this invention is implemented through the soft shutdown process state machine built into the control module. The soft shutdown process state machine includes Stage 1: shutdown control state, Stage 2: enhancement attenuation state, Stage 3: energy recovery control state, Stage 4: shutdown state, and Stage 5: protection latching state. The workflow is as follows:

[0146] The control module detects the shutdown command issued by the host computer, enters the soft shutdown process state machine, collects current and voltage information, and enters the shutdown control state.

[0147] When the soft shutdown process state machine enters the shutdown control state, it enters the soft shutdown process, adopts multi-level soft shutdown control, and controls the drive signal to decrease, so that the gate drive duty cycle and / or gate voltage decrease to the shutdown threshold.

[0148] Continuously calculate and monitor the soft-shutdown control exponent Z[n] and energy exponent E[n];

[0149] If the soft turn-off control index Z[n] is detected to exceed the adjustment threshold, it enters the enhanced decay state, reduces the current gate drive duty cycle and / or gate voltage, and forms a smoother current drop curve;

[0150] If the energy index E[n] exceeds the recovery threshold, the system enters energy recovery mode, turns on the energy recovery switch, and initiates the energy recovery path to direct energy into the energy storage feedback unit. When the current drops to I< Turn off the energy recovery switch and shut down the energy recovery path;

[0151] If the gate drive duty cycle and / or gate voltage drop to the turn-off threshold, the transistor enters the turn-off state, outputs a turn-off signal, and completely turns off the power switch. The voltage rises steadily to the bus voltage and enters a protection latch state. The control module is prohibited from turning on again until the next control cycle.

[0152] It should be noted that in the description of this invention, the terms "upper," "lower," "left," "right," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship conventionally placed during use. They are used only for ease of description and do not indicate that the device or element referred to must have a specific orientation, and therefore should not be construed as a limitation of this invention. Furthermore, the terms "first," "second," and "third," etc., are used only to distinguish descriptions and should not be construed as indicating relative importance.

[0153] The above description, in conjunction with specific preferred embodiments, provides a further detailed explanation of the present invention. It should not be construed that the specific implementation of the present invention is limited to these descriptions. For those skilled in the art, various simple deductions or substitutions can be made without departing from the concept of the present invention, and all such modifications and substitutions should be considered within the scope of protection of the present invention.

Claims

1. A soft-turn-off control method for a DC solid-state switch, characterized in that, Including the following steps: S1 receives the shutdown command and samples the load current. and switch drain-source voltage ; S2, enter the soft shutdown process. The soft shutdown process is configured as a multi-level soft shutdown control mode, with multiple soft shutdown stages Stg[n]. Each soft shutdown stage Stg[n] corresponds to a progressively decreasing duty cycle and / or gate voltage, so that the duty cycle and / or gate voltage of the drive signal are progressively decreased to the shutdown threshold according to the preset multiple soft shutdown stages Stg[n], and then the shutdown signal is output. In step S2, based on the load current and / or switch drain-source voltage Calculate the stage exponent S[n]. After the drive signal decreases to the duty cycle and / or gate voltage of the current soft-turn-off stage Stg[n], if the stage exponent S[n] is detected to be greater than the stage advancement threshold, then... If the condition is met, then proceed to the next soft shutdown phase Stg[n+1]; The formula for calculating the stage index S[n] is as follows: S[n]= ; or in, , , , The constant coefficients, The rate of change of current, Indicates the retrace energy. Indicates the rated current. Represents bus voltage. And TH2 is a constant. The time window that represents the sampling period.

2. The soft-turn-off control method for a DC solid-state switch according to claim 1, characterized in that, In the multiple soft shutdown stages Stg[n] of the soft shutdown process, different gate driving laws G[n] are used respectively, and the gate driving laws G[n] are configured as follows: G[n]=βG[n-1]+(1-β) ; Wherein, G[n] represents the gate drive control quantity, which is mapped to the gate drive duty cycle or gate voltage level and is used to generate graded drive signals. β represents the smoothing / inertia coefficient, and g1, g2, gn, gn+1 represent preset multi-segment target level coefficients.

3. The soft-turn-off control method for a DC solid-state switch according to claim 1, characterized in that, In step S2, based on the load current and / or switch drain-source voltage Calculate the soft turn-off control index Z[n]. When it is detected that the soft turn-off control index Z[n] exceeds the preset adjustment threshold, adjust the multiple soft turn-off stages Stg[n], generate and enter a new soft turn-off stage Stg[ad]. The duty cycle and / or gate voltage corresponding to the soft turn-off stage Stg[ad] are less than the duty cycle and / or gate voltage corresponding to the current soft turn-off stage Stg[n]. The soft-shutdown control index Z[n] includes the rate of change of current. and / or energy integral The calculation formula is: ； or, = ; or, ; Or, Z[n] = k4 + k5 ; Among them, k4 and k5 are constant coefficients.

4. The soft-turn-off control method for a DC solid-state switch according to claim 3, characterized in that, The duty cycle and / or gate voltage corresponding to the soft turn-off stage Stg[ad] are greater than or equal to the duty cycle and / or gate voltage corresponding to the next soft turn-off stage Stg[n+1].

5. The soft-turn-off control method for a DC solid-state switch according to claim 4, characterized in that, soft shutdown phase The corresponding duty cycle and / or gate voltage are calculated as follows: ； in, Indicates the step size of the stage.

6. The soft-turn-off control method for a DC solid-state switch according to claim 5, characterized in that, In step S2.2, the stage step size is adjusted according to the current change rate: =clip( , ); clip() is a clipping function. This is the proportionality coefficient. and Used for setting The lower and upper limits, the To adjust the threshold.

7. The soft-turn-off control method for a DC solid-state switch according to claim 3, characterized in that, The soft-shutdown control index Z[n] includes the rate of change of current. and / or energy integral , ,in, The time window representing the sampling period; = ;or .

8. The soft-turn-off control method for a DC solid-state switch according to claim 1, characterized in that, The process also includes step S4, where, after turning off the power switch, when a current of opposite polarity is detected within the same sampling period, the device enters a latching state, causing the power switch to enter a time-delay protection period. During the extended protection period The power switch transistor must not be turned on again.

9. A DC solid-state switch, comprising a signal sampling module, a control module, and a drive module, wherein the drive module is connected to a power switching transistor, the signal sampling module is connected to the control module, and the control module controls the drive module to output a drive signal, thereby controlling the power switching transistor to turn on or off, characterized in that, The control module executes the soft-shutdown control method for the DC solid-state switch as described in any one of claims 1-8.

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