Active pulse discharge energy recovery and energy bleeding system and method

Abstract

This invention relates to the field of microsecond pulse discharge technology, and more particularly to an active pulse discharge energy recovery and energy release system and method. The technical solution includes an energy storage element, a charging module, a first switching valve group, a second switching valve group, a third switching valve group and a recovery inductor, a fourth switching valve group and a discharge resistor. The energy storage element stores and releases electrical energy; the charging module injects electrical energy into the energy storage element; the first switching valve group is connected in series between the charging module and the energy storage element to control the on / off state of the charging circuit. This invention, through a hybrid switching architecture and active timing control, achieves pulse discharge energy recovery while eliminating the constraint of current-limiting resistor heat loss on recovery efficiency. It also utilizes the self-conduction characteristic of normally open devices under power failure to solve the problem of high-voltage energy release under fault conditions, enabling the system to balance energy recovery efficiency and fault safety protection performance, making it suitable for high-power high-repetition-rate pulse power supply systems.

Description

Technical Field

[0001] This invention relates to the field of microsecond pulse discharge technology, and in particular to an active pulse discharge energy recovery and energy release system and method. Background Technology

[0002] With the rapid development of cutting-edge technologies such as free-electron lasers, nuclear fusion devices, and novel energy storage systems, high-power pulse technology has become a core cornerstone supporting the operation of these major scientific facilities. This necessitates that the system not only operate efficiently and repeatedly for extended periods under these extreme high-voltage, high-current conditions, but also consider safety in case of system failure. To address the high energy consumption of the system, efficient energy recovery technology can be used to promote repetitive operation, as the recovered energy can partially support the next pulse output, reducing the system's continuous power demand on external power sources and alleviating the power supply burden, thereby ensuring stable operation under repetitive conditions. However, existing energy recovery technologies often suffer from unidirectional design limitations in their topologies, making it impossible to effectively recover and dissipate energy from positive voltages appearing in negative voltage systems. Therefore, reliably, safely, and cost-effectively achieving energy recovery from microsecond pulse width high-current pulse power supplies plays a crucial role in improving the overall efficiency and safety of pulse power systems.

[0003] An existing pulse power generation system uses a current-limiting resistor for slow charging and a T-type protection circuit to isolate the discharging and charging networks. After the pulse discharge ends, the freewheeling effect of the load parasitic inductance reverses the voltage polarity of the energy storage capacitor. An uncontrolled diode connected in parallel across the capacitor and an inductor form an LC recovery branch. The negative voltage energy is then converted back to positive voltage for recovery through LC oscillation. The circuit topology is as follows: Figure 1 As shown. The main drawback of this scheme is that the diode is a passively conducting device during recycling. In microsecond-level pulse width scenarios, a certain recovery time is required after the main circuit switch is turned off. The automatic conduction of the diode does not take into account the actual recovery state of the main switch, which can easily cause system timing interference. At the same time, the charging process and energy recovery process of the system are always connected in series with a current-limiting resistor. This resistor participates in energy transfer throughout the process, resulting in continuous ohmic heat loss, which directly leads to a significant reduction in the system's charging efficiency and energy recovery efficiency.

[0004] Another existing energy recovery scheme uses thyristors combined with precise control of switching timing to recover residual energy from capacitors, and uses silicon carbide MOSFET circuit breakers to isolate the charging and discharging circuits. Its circuit topology is as follows: Figure 2 As shown. The workflow of this solution is as follows: First, the charging module passes through a current-limiting resistor and S... A The solid-state switching valve assembly charges the energy storage capacitor to its rated operating voltage; then it shuts off S. AThe valve assembly isolates the charging and discharging circuits, maintaining the capacitor in a high-voltage energy storage state; then, S is turned on. B The main circuit switching valve group discharges to the resistive-inductive load, utilizing the underdamped oscillation characteristics of the circuit. After the discharge is complete, the capacitor is reverse-charged by the freewheeling effect of the load stray inductance. Subsequently, the capacitor's reverse-voltage state must be maintained until the main circuit switching valve group fully recovers its forward blocking capability. Finally, S is turned on. C The valve assembly and the energy storage capacitor form an LC resonant circuit, causing the capacitor voltage polarity to reverse, thereby completing energy recovery. After the system completes its last operating cycle, the S1 switch is turned off. A The valve assembly forms an energy discharge channel between the energy storage capacitor and the L-shaped protection circuit, safely dissipating the remaining energy to ensure equipment and personnel safety. However, this solution still has the following shortcomings: In the event of a sudden power grid failure or external power supply fault, due to the blocking characteristics of mainstream semiconductor switching devices such as MOSFETs, they will immediately enter the cut-off state after losing their control drive signal. At this time, the huge high-voltage energy remaining in the energy storage element will not be able to form a discharge circuit through the switching path, posing a serious threat to the life safety of operators. In addition, it uses a passive method of series fixed resistors in the charging and discharging circuit to achieve energy discharge. Although selecting a high-resistance resistor can control the short-circuit impact current at the moment of discharge to a small range, it will lead to a larger time constant and extremely slow charging, which cannot meet the requirements of rapid recovery and high-frequency repeated triggering of microsecond pulse devices. Although selecting a low-resistance resistor can significantly improve the discharge speed, it will generate a huge surge current at the moment of voltage release, causing irreversible damage to the circuit breaker.

[0005] In view of the many problems in the prior art, such as low energy recovery efficiency, difficulty in timing coordination, and lack of active safety discharge capability under fault conditions, this application proposes an active pulse discharge energy recovery and energy discharge system and method. Summary of the Invention

[0006] The purpose of this invention is to address the numerous problems in the prior art, such as low energy recovery efficiency, difficulty in timing coordination, and lack of active safety discharge capability under fault conditions, by proposing an active pulse discharge energy recovery and energy discharge system and method.

[0007] In a first aspect, this application provides an active pulse discharge energy recovery and energy release system, comprising:

[0008] Energy storage elements are used to store and release electrical energy;

[0009] A charging module is used to inject electrical energy into the energy storage element;

[0010] The first switching valve group is connected in series between the charging module and the energy storage element to control the on / off state of the charging circuit;

[0011] The second switching valve group is connected in series between the energy storage element and the load to control the on / off state of the discharge circuit;

[0012] The third switching valve group and the recovery inductor are connected in series to form a recovery branch. This recovery branch is connected in parallel across the two ends of the energy storage element to reverse the voltage polarity of the energy storage element through LC resonance to achieve energy recovery.

[0013] The fourth switching valve group and the discharge resistor are connected in series to form a discharge branch. This discharge branch is connected in parallel to both ends of the energy storage element. The fourth switching valve group is a normally open switching device group, which is turned off when a control signal is applied and turned on when the control signal is removed.

[0014] The first, second, third, and fourth switching valve groups constitute a hybrid switching architecture, wherein:

[0015] The first switching valve assembly uses a turn-off type semiconductor switching device;

[0016] The second and third switching valve groups each employ thyristor switching devices;

[0017] The fourth switching valve group uses normally open semiconductor switching devices.

[0018] Optionally, the turn-off semiconductor switching device is a silicon carbide MOSFET, and the normally open semiconductor switching device is a silicon carbide junction field-effect transistor.

[0019] The fourth switching valve group is composed of multiple silicon carbide junction field-effect transistors connected in series, and adopts a common-source back-to-back structure. A static voltage equalization resistor and a dynamic voltage equalization capacitor are connected in parallel between the drain and gate of each junction field-effect transistor.

[0020] Optionally, the fourth switching valve group is kept closed by the control signal during normal system operation. When the system loses power, the control signal is lost, or a sudden fault occurs, the control signal is automatically removed, and the fourth switching valve group is turned on momentarily, so that the energy storage element forms an energy discharge path through the discharge resistor.

[0021] Optionally, the first switching valve group is composed of multiple silicon carbide MOSFETs connected in series, and each MOSFET is connected in parallel with a static voltage equalization resistor, a dynamic voltage equalization branch composed of a resistor and a capacitor connected in series, and an overvoltage protection element.

[0022] The second and third switching valve groups are each composed of multiple thyristors connected in series;

[0023] The rated parameters of a single thyristor in the third switching valve group of the recovery branch meet the following requirements:

[0024]

[0025]

[0026] in, This refers to the rated repetitive peak blocking voltage of a single thyristor. This represents the maximum non-repetitive surge current peak allowed for a single thyristor. This is the rated operating voltage of the energy storage element. This represents the total number of thyristors connected in series in the third switching valve group. This refers to the reverse voltage amplitude that the energy storage element receives due to load freewheeling after the main pulse discharge ends. This refers to the capacitance value of the energy storage element. To recover the inductance value, 0.85 refers to the series voltage equalization derating factor; 2.0 refers to the overvoltage safety margin factor.

[0027] Optionally, the recovery inductance value in the recovery branch The following conditions must be met:

[0028]

[0029] in, This refers to the reverse voltage amplitude that the energy storage element receives due to load freewheeling after the main pulse discharge ends. For the maximum allowable rate of current rise, Available recycling time, This represents the capacitance value of the energy storage element.

[0030] Optionally, the number of devices connected in series in the fourth switching valve group satisfies the following:

[0031]

[0032]

[0033] in, This refers to the number of normally open switching devices connected in series. This is the highest operating voltage of the energy storage element. This is the rated blocking voltage of a single normally open switching device. This represents the maximum allowable drain current for a single normally open switching device. The value of the bleeder resistor is 0.85, which refers to the series voltage derating factor; 2.0 refers to the overvoltage safety margin factor.

[0034] The system also includes a control unit, which outputs timing control signals for each switching valve group to achieve active timing control of each stage of charging, discharging, energy recovery and energy release.

[0035] Secondly, this application provides an active pulse discharge energy recovery and energy release method, applied to the active pulse discharge energy recovery and energy release system described in the first aspect, comprising:

[0036] During the charging phase, the first switching valve group is turned on, enabling the charging module to charge the energy storage element;

[0037] During the waiting phase, the first switch valve group is shut off, while the second, third, and fourth switch valve groups remain shut off, and the energy storage element is in a high-voltage standby state.

[0038] During the discharge phase, the second switching valve group is turned on, causing the energy storage element to release pulse energy to the load. After the discharge is completed, the voltage across the energy storage element is reversed by utilizing the freewheeling effect of the load.

[0039] During the maintenance phase, the second switching valve group is kept closed, and the positive blocking capability is awaited to be restored.

[0040] During the recovery phase, the third switching valve group is turned on, so that the energy storage element and the recovery inductor form an LC resonant circuit, which converts the reverse voltage polarity of the energy storage element to the positive voltage polarity, thus completing the energy recovery.

[0041] During the discharge phase, the control signal of the fourth switching valve group is removed. Taking advantage of the characteristic of the fourth switching valve group that it automatically turns on when the control signal is lost, the energy storage element forms a discharge path through the discharge resistor to consume the residual energy.

[0042] Optionally, a pre-charging stage is included before the charging stage: before charging begins, a control signal is applied to the fourth switching valve group to keep it off, ensuring that the energy storage element is isolated from the discharge resistor.

[0043] During the maintenance phase, the third switching valve group is prohibited from being turned on until the second switching valve group fully restores its positive blocking capability.

[0044] Optionally, the timing control of each switching valve group shall meet the following conditions:

[0045]

[0046] in, The shut-off duration of the first switching valve group. The trigger pulse width for the second switching valve group. The trigger pulse width for the third switching valve group. The time delay between the shutdown of the first switching valve group and the activation of the second switching valve group. The time delay between the shut-off of the second switching valve group and the turn-on of the third switching valve group. For the system's repetitive cycle, This refers to the capacitance value of the energy storage element. This refers to the operating voltage of the energy storage element. This refers to the charging current of the charging module;

[0047]

[0048]

[0049] in, This is the time margin factor, with a value range of 1.2 to 2; It is the ratio of the forward turn-off time to the reverse recovery time under a microsecond pulse width, and its value ranges from 5 to 8; This is the reverse recovery time of the second switching valve group.

[0050] Optionally, during the discharge phase, the fourth switching valve group is always kept in the off state with a control signal applied during normal system operation, and is automatically turned on only when the last operating cycle of the system ends or when a sudden failure causes the control signal to be lost, so as to consume the remaining residual energy in the energy storage element through the discharge resistor.

[0051] Compared with the prior art, this application includes at least one of the following beneficial technical effects:

[0052] This invention employs normally open semiconductor switching devices to form a fourth switching valve group in the energy discharge branch. Utilizing the physical characteristic of these devices automatically turning on after the control signal is removed, the system can automatically dissipate the residual high-voltage energy in the energy storage element through a discharge resistor to form a discharge path when power is lost, control signal is lost, or a sudden fault occurs, without relying on any external auxiliary power supply or complex control logic. This solves the safety problem in the prior art where enhanced switching devices immediately turn off after the loss of a drive signal, resulting in the inability to actively discharge high-voltage energy.

[0053] After charging is completed, the present invention completely isolates the current-limiting resistor from the main energy storage circuit through the first switching valve group, so that the energy recovery process forms an LC resonant circuit only between the energy storage element, the third switching valve group and the recovery inductor. The current-limiting resistor does not participate in energy transmission during the energy recovery stage, eliminating the ohmic heat loss caused by the current-limiting resistor being connected in series with the recovery circuit throughout the prior art, thereby improving the energy recovery efficiency.

[0054] This invention assigns four functions—charging isolation, pulse discharge, energy recovery, and energy dissipation—to the first, second, third, and fourth switching valve groups, respectively, to operate independently at different times. Through active timing control, each valve group alternately turns on and off at different stages. After the discharge stage ends, the third switching valve group is turned on only after the second switching valve group has fully recovered its forward blocking capability. This avoids the timing uncertainty and the risk of mis-turning in the main circuit introduced by the passive conduction of diodes in the prior art. It makes the switching process between each working stage precise and controllable, ensuring the system's operational stability under microsecond-level pulse width, high voltage, and high current conditions.

[0055] In summary, this invention, through a hybrid switching architecture and active timing control, achieves pulse discharge energy recovery while eliminating the constraint of current-limiting resistor heat loss on recovery efficiency. Furthermore, it utilizes the power-off self-conduction characteristic of normally open devices to solve the problem of high-voltage energy discharge under fault conditions, enabling the system to balance energy recovery efficiency and fault safety protection performance. It is suitable for high-power high-repetition-rate pulse power supply systems. Attached Figure Description

[0056] Figure 1 This is a typical circuit topology diagram of a pulse discharge system with an uncontrollable energy recovery branch in the prior art;

[0057] Figure 2 This is a typical circuit topology diagram of an active energy recovery pulse discharge system based on silicon carbide MOSFETs and thyristor switches in the prior art.

[0058] Figure 3 The circuit topology diagram of the active pulse discharge energy recovery and energy dissipation system based on hybrid switches provided in the embodiments of the present invention is shown below.

[0059] Figure 4 This is a schematic diagram illustrating the working principle of the pulse discharge energy recovery and dissipation system in an embodiment of the present invention;

[0060] Figure 5-a This is the equivalent circuit topology of the system during the charging phase;

[0061] Figure 5-b This is the equivalent circuit topology of the system during the discharge phase;

[0062] Figure 5-c The equivalent circuit topology of the system during the energy recovery phase is shown below.

[0063] Figure 5-d The equivalent circuit topology of the system during the energy dissipation phase is shown below.

[0064] Figure 6 This is a schematic diagram of the timing control of each switching valve group in the system of this invention. Detailed Implementation

[0065] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that, unless otherwise specified, the following embodiments and features described therein can be combined with each other.

[0066] For examples, please refer to Figures 3 to 6 This embodiment provides an active pulse discharge energy recovery and energy dissipation system based on a hybrid switch. This system is designed for applications requiring high-power, high-current pulse power supplies with microsecond pulse widths. Its circuit topology is as follows: Figure 3 As shown. The system mainly consists of the following parts: a charging module, an energy storage capacitor C, and a high-voltage solid-state switching valve group S composed of silicon carbide MOSFETs connected in series. A1 -S Ai A normally open switching valve assembly S composed of silicon carbide JFETs connected in series J1 -S Jn 1. Discharge resistor R4; 2. Main circuit switching valve group S composed of thyristors connected in series. B1 -S Bj S is a regeneration branch switch valve group composed of thyristors connected in series. C1 -S Ck Recycling inductor L and loads with resistive-inductive characteristics, high-voltage solid-state switching valve assembly S A1 -S Ai Hereinafter referred to as S A The valve assembly is a normally open on / off valve assembly S composed of silicon carbide JFETs connected in series. J1 -S Jn Hereinafter referred to as S J The valve group, consisting of a main circuit switching valve group S composed of thyristors connected in series. B1 -S Bj Hereinafter referred to as S B Valve assembly, recovery branch switch valve assembly S composed of thyristors connected in series C1 -S Ck Hereinafter referred to as S C Valve assembly. The functions and specific implementation methods of each component are as follows:

[0067] The charging module uses a constant current charger, and its output is connected to an S-type charger. A The valve assembly is connected to the energy storage capacitor C and is used to inject electrical energy into the energy storage capacitor C with a constant current within a set charging time to ensure the smoothness and controllability of the charging process.

[0068] The energy storage capacitor C is the core energy storage component of this system. It is a pulse capacitor with low equivalent series resistance, which has the characteristics of high energy storage density and low dielectric loss. It can complete the rapid release of high power energy in microseconds and withstand the reverse voltage from the load freewheeling after the discharge ends.

[0069] S A The valve assembly, acting as a charging isolation switch, consists of i silicon carbide MOSFET devices connected in series to improve the overall withstand voltage level. A static voltage equalization resistor R is connected in parallel across the drain and source terminals of each MOSFET device. dThe circuit consists of a dynamic voltage equalization branch composed of a resistor Rs and a capacitor Cs connected in series, and an MOV varistor. The static voltage equalization resistor ensures uniform voltage distribution across the series-connected devices under DC conditions; the dynamic voltage equalization branch compensates for transient voltage imbalances caused by differences in junction capacitance; and the MOV varistor absorbs potential surge overvoltages in the circuit, protecting the MOSFET from transient overvoltage impacts. A The valve group is turned on during the charging phase to connect the charging module with the energy storage capacitor; it is turned off immediately after charging is completed to completely isolate the charging module from the high-voltage discharge circuit and prevent discharge pulses from feeding back to the charging module and causing damage.

[0070] S B The valve assembly, acting as the main discharge switch, consists of j thyristors connected in series. Its anode is connected to the positive terminal of the energy storage capacitor C, and its cathode is connected to one end of the load. Thyristors possess advantages such as low on-state voltage drop, strong surge current withstand capability, and high reliability, making them suitable as the main switching device for high-current pulse discharge. When S... B When the valve group receives a gate trigger pulse, all series-connected thyristors turn on synchronously, and the energy stored in the energy storage capacitor C is released through S. B The valve assembly rapidly releases power to the load, generating a high-power pulse at the microsecond level.

[0071] S C The valve assembly, acting as an energy recovery switch, has a structure similar to S. B The valve assembly is consistent and consists of k thyristors connected in series. S C The valve assembly is connected in series with the recovery inductor L, and then the entire assembly is connected in parallel across the energy storage capacitor C. When S C When the valve group is turned on, the energy storage capacitor C, the recovery inductor L, and S C The valve assembly forms a closed LC series circuit. The reverse voltage on the energy storage capacitor C serves as the circuit excitation source, driving a sinusoidal resonant current to flow in the circuit. Through the reciprocating conversion of electrical energy and magnetic energy, the voltage polarity of the energy storage capacitor C gradually changes from reverse to positive, completing one full energy recovery process.

[0072] S J The valve assembly, acting as an energy discharge switch, consists of n silicon carbide JFETs connected in series, using a symmetrical back-to-back common-source connection: the sources of the first group of series-connected JFETs are interconnected with the sources of the second group of series-connected JFETs, and both groups share a single control signal for operation. A static voltage-equalizing resistor Rj and a dynamic voltage-equalizing capacitor Cj are connected in parallel between the drain and gate of each JFET. The silicon carbide JFETs are depletion-type devices; their natural state is on, and they can be turned off by applying a negative gate-source voltage. Utilizing this normally open characteristic, S... JDuring normal system operation, the valve assembly maintains its closed state by continuously applying a control signal, isolating the bleeder resistor R4 from the main circuit. When the system loses power or the control signal is lost due to a fault, the control signal is automatically removed, and all JFETs simultaneously return to the on state. J The valve assembly closed instantly.

[0073] One end of the bleeder resistor R4 is connected to S J The valve assembly's output is connected to system ground or the negative terminal of the energy storage capacitor. In S J When the valve assembly is closed, no current flows through R4, and no power loss occurs; in S J When the valve group is turned on, R4 is connected to the discharge circuit of the energy storage capacitor C, rapidly dissipating the residual electrical energy stored in the capacitor as heat. The value of the discharge resistor R4 must balance the discharge speed and discharge current limitations; it must ensure that the high-voltage energy is discharged to a safe level within an acceptable time, while limiting the peak discharge current to S. J Within the safe operating range of the valve assembly.

[0074] The load is the terminal device of the pulsed power system, and its electrical characteristics are resistive-inductive, meaning it contains both resistive and inductive components. The inductive component, after the discharge phase ends, reverse-charges the energy storage capacitor C through the freewheeling effect, which is one of the prerequisites for energy recovery.

[0075] The following provides a detailed explanation of the operating principle and working process of the system in this embodiment. Please refer to... Figure 4 The working principle diagram shown is as follows: Figure 5-a , Figure 5-b , Figure 5-c , Figure 5-d The equivalent circuit diagrams for each stage are shown.

[0076] In a complete pulse discharge and energy recovery cycle, this system sequentially undergoes six controlled stages:

[0077] (a) Pre-charging phase t0~t1. Before the charging module starts, the control system first sends a signal to S... J The valve assembly outputs a valid turn-off drive signal, reliably putting all silicon carbide JFETs into the off state, ensuring that the electrical connection between the energy storage capacitor C and the discharge resistor R4 is completely severed. The purpose of this step is to establish a safe initial state before charging begins, preventing damage during charging due to S... J Unexpected opening of the valve assembly can cause charging energy to be wasted unnecessarily on the discharge resistor, or even cause overheating.

[0078] (ii) Charging phase t1~t2. After confirming S... J After the valve assembly has been reliably shut off, the control system sends a signal to S. AThe valve assembly issues a turn-on command, and the silicon carbide MOSFETs turn on synchronously, allowing the charging module to activate via S... A The valve assembly charges the energy storage capacitor C using a constant current method. When the voltage across the energy storage capacitor C reaches the preset rated operating voltage, the control system shuts off S. A Valve assembly, charging phase complete. During this process, S B Valve assembly, S C Valve assembly and S J All valves remain closed.

[0079] (III) Waiting phase t2~t3. A After the valve group is shut off, the connection between the energy storage capacitor C and the charging module is completely severed, and at the same time S B Valve assembly, S C Valve assembly and S J All valves remain closed, and the energy storage capacitor C is in a floating, high-voltage standby state. The duration of this phase can be flexibly adjusted according to external trigger commands to ensure that the pulse discharge timing matches the timing requirements of other parts of the system.

[0080] (iv) Discharge phase t3~t4. Upon receiving an external trigger signal, the control system sends a signal to S. B The valve assembly sends a wide-pulse trigger signal, causing all series-connected thyristors to conduct synchronously. The high-voltage energy stored in the energy storage capacitor C is transferred through S... B The valve assembly rapidly releases power to the load, forming a strong current pulse with a width on the order of microseconds. After the discharge current crosses zero, because the magnetic field energy stored in the load inductor cannot disappear instantaneously, the load inductor continues to feed energy to the energy storage capacitor C through the freewheeling effect, causing the voltage polarity across the energy storage capacitor C to reverse from the original forward voltage to the reverse voltage. At this time, S A Valve assembly, S C Valve assembly and S J The valve assembly remains closed, S B After the valve assembly completes its conduction task, its trigger signal is removed, and the thyristor automatically turns off using the natural commutation point where the current crosses zero.

[0081] (v) Maintenance phase t4~t5. After the discharge phase ends, all switching valve groups —S A S B S C S J —All are controlled to the off state. The energy storage capacitor C maintains its energy storage state with its reverse voltage polarity, and no current flows in the circuit. During this stage, S B The thyristors in the valve group require a certain amount of time to complete the reverse recovery process, that is, to clear the residual charge carriers inside the device and re-establish the depletion layer, thereby restoring their forward voltage blocking capability. During this period, S CThe valve assembly must not be turned on. This is because there is a high reverse voltage across the energy storage capacitor C. If S... C Valve assembly in S B If the valve group is turned on prematurely before it has fully recovered, the reverse voltage will pass through the turned-on S... C Valve assembly applies to S B The two ends of the valve assembly may cause S B When a valve assembly is forced to open without sufficient blocking capability, a "misdirected opening" phenomenon occurs, which can lead to a short circuit in the main circuit and damage to the equipment in severe cases.

[0082] (vi) Recovery phase t5~t6. After waiting for sufficient time, confirm S. B After the valve assembly has fully restored its positive blocking capability, the control system sends a signal to S. C The valve assembly sends a trigger pulse, and the thyristors conduct synchronously. At this time, the energy storage capacitor C, the recovery inductor L, and S... C The valve assembly forms a closed LC series resonant circuit. The reverse voltage on the energy storage capacitor C serves as the initial excitation, generating a resonant current in the circuit. This current varies sinusoidally. At one-quarter of the resonance cycle, all the energy in the energy storage capacitor C is transferred to the recovery inductor L, and the capacitor voltage crosses zero. Subsequently, energy flows back from the recovery inductor L to the energy storage capacitor C. At half the resonance cycle, the voltage of the energy storage capacitor C reaches its maximum positive value, with an amplitude equal to the initial reverse voltage amplitude. At this point, the voltage polarity of the energy storage capacitor C has completely changed from reverse to positive, and the energy of the positive voltage comes from the original reverse voltage energy after the discharge phase, thus achieving energy recovery. The recovered positive energy will continue to be stored in the energy storage capacitor C for use in the next pulse cycle. After the recovery phase ends, S is removed. C The valve assembly is triggered by a thyristor that turns off naturally when the current crosses zero.

[0083] In each of the above stages, S J The valve assembly is always kept in a controlled off state, and the discharge resistor R4 is always isolated from the main circuit, so it has no effect on the charging, discharging and recycling process.

[0084] After the system completes all preset pulse discharge tasks, or in the event of an external power outage, control system malfunction, or other abnormal situation during operation, the system enters the energy discharge phase. At this time, S J The control signal for the valve assembly is removed. For a silicon carbide JFET, the removal of the control signal means that its gate-source voltage returns to zero, and the device immediately switches from the off state to the on state. If there is still residual high-voltage energy in the energy storage capacitor C, it will be released through S. JThe valve assembly and the bleeder resistor R4 form a closed bleeder circuit, and residual energy is safely dissipated as Joule heat across the bleeder resistor R4. The entire bleedering process does not rely on any external power supply or complex control logic; it is entirely completed spontaneously by the normally-open physical characteristics of the silicon carbide JFET, thus exhibiting extremely high reliability. Even under the most severe conditions of complete system power failure, the bleedering function can still operate normally, thereby fundamentally ensuring the safety of equipment and operators.

[0085] The basis for the system topology design is explained below.

[0086] 1. Recycling branch topology selection: For the inductance value of the recycling branch The selection criteria are as follows:

[0087]

[0088] In the formula This refers to the reverse voltage amplitude that the energy storage capacitor experiences after the main pulse discharge ends, due to the freewheeling current of the load's parasitic inductance. This refers to the maximum permissible rate of current rise. Available recovery time refers to the system-set interval between adjacent pulses minus the time required for switch control and main circuit recovery; This is the capacitance value of the energy storage capacitor.

[0089] The pressure resistance of the recovery branch switch valve assembly SC1-SCk should meet the following requirements:

[0090]

[0091]

[0092] In the formula The rated repetitive peak blocking voltage of a single thyristor; This refers to the maximum non-repetitive surge current peak value allowed for a single thyristor; The rated operating voltage of the energy storage capacitor system; The total number of thyristors connected in series in the recovery branch; 0.85 refers to the series voltage derating factor; 2.0 refers to the overvoltage safety margin factor; and the absolute value of the reverse voltage generated by the energy storage capacitor at the end of the pulse discharge. The capacitance value of the energy storage capacitor; 1.2 refers to the current safety margin factor, which is used to recover the branch inductance.

[0093] 2. SiC MOS Solid State Switch Design: A high-voltage solid state switch based on silicon carbide MOSFETs. Its main feature is the use of multiple SiC MOSFET devices connected in series to improve the overall voltage withstand performance of the switch.

[0094] The main body consists of multiple MOSFETs connected in series. Each MOSFET is connected in parallel with a static resistor Rd and dynamic voltage equalization branches Rs, Cs and MOV. The design of this high-voltage solid-state switch focuses on fully isolating the discharge circuit from the charging circuit when the main circuit is discharging, so as to ensure the safety of the charger.

[0095] 3. SIC JFET switch design: adopts a common-source back-to-back structure, that is, the source of one set of series JFETs is connected to the source of another set of series JFETs, the two sets share the control signal, and a static voltage equalization resistor Rj and a dynamic voltage equalization capacitor Cj are connected in parallel between the drain of each JFET and the gate.

[0096] The discharge branch switch valve group SJ1-SJn should meet the following requirements:

[0097]

[0098]

[0099] In the formula This refers to the number of JFETs connected in series; This refers to the highest operating voltage of the energy storage capacitor; 0.85 refers to the rated drain-source blocking voltage of a single JFET; 0.85 refers to the series voltage derating factor; 2.0 refers to the overvoltage safety margin factor. The maximum allowable drain current for a single JFET; 1.2 refers to the resistance value of the bleeder resistor; 1.2 refers to the current safety margin.

[0100] 4. Timing control strategy, switch triggering timing as follows: Figure 6 As shown, the definition is: For the delay between SJ1-SJn shutdown and SA1-SAi conduction, The delay between the shutdown of SA1-SAi and the conduction of SB1-SBj is calculated. The delay between SB1-SBj being turned off and SC1-SCk being turned on is as follows: For the SIC MOS solid-state switching valve group SA1-SAi, The trigger pulse width of the main circuit switching valve group SB1-SBj To recover the trigger pulse width of the branch switch valve group SC1-SCk, the following timing sequence should be satisfied:

[0101]

[0102] in The power period of the repetitive pulse. This refers to the capacitance value of the energy storage capacitor. The charging current for the charging module; , The settings are determined by the selected thyristor switch, and are set to 200μs and 30μs respectively. The delay between SJ1-SJn shutdown and SA1-SAi conduction only needs to be started before the charger starts working and before the SA valve group is turned on.

[0103] in, and Configure it according to the following formula:

[0104]

[0105]

[0106] in This is the time margin factor, with a value of approximately 1.2 to 2; It is the ratio of forward turn-off time to reverse recovery time under a microsecond pulse width, and its value is 5~8; This is the reverse recovery time, which is the time for the reverse current to recover to 0.1. The required time is obtained from the actual pulse waveform.

[0107] 5. Energy recovery experiment verification. With the capacitor operating voltage at 11kV, the recovery inductor L was selected as 400μH. , , , , Energy recovery from microsecond-level pulse power supplies under high repetition rate conditions was successfully achieved.

[0108] It is worth noting that this invention employs a hybrid switching architecture consisting of a first switching valve group composed of turn-off semiconductor switching devices, second and third switching valve groups composed of thyristor devices, and a fourth switching valve group composed of normally open semiconductor switching devices. Through active timing control in six controlled stages, the reverse voltage energy of the energy storage element is converted into forward voltage energy through LC resonance and stored in the energy storage element for use in the next pulse cycle. Simultaneously, during energy recovery, the first switching valve group completely isolates the current-limiting resistor from the energy storage circuit, eliminating the ohmic heat loss caused by the current-limiting resistor's participation throughout charging and recovery, thus improving energy recovery efficiency. The fourth switching valve group uses normally open semiconductor switching devices, which remain off during normal system operation by relying on control signals. In the event of an emergency, the system will immediately shut off the current-limiting resistor. In the event of system power failure, loss of control signal, or sudden fault, the control signal is automatically removed, and the fourth switching valve group, due to its normally open physical characteristic, instantly conducts, allowing the residual high-voltage energy in the energy storage element to form a discharge path through the discharge resistor. This solves the safety problem in existing technologies where enhanced switching devices immediately shut off after power failure, preventing the active discharge of high-voltage energy. Fault safety protection can be achieved without relying on external auxiliary power supplies or complex control logic. Each switching valve group operates independently at different times, and the four functions of charging isolation, pulse discharge, energy recovery, and fault discharge do not interfere with each other. This avoids the timing uncertainty and main circuit mis-conduction risk caused by the passive conduction of diodes in existing technologies, enabling the system to achieve stable high-frequency pulse discharge, energy recovery, and fault safety discharge under microsecond-level pulse width, high voltage, and high current conditions.

[0109] The above specific embodiments are merely several optional embodiments of the present invention. Based on the technical solutions of the present invention and the relevant teachings of the above embodiments, those skilled in the art can make various alternative improvements and combinations to the above specific embodiments.

Claims

1. An active pulse discharge energy recovery and energy release system, characterized in that, include: Energy storage elements are used to store and release electrical energy; A charging module is used to inject electrical energy into the energy storage element; The first switching valve group is connected in series between the charging module and the energy storage element to control the on / off state of the charging circuit; The second switching valve group is connected in series between the energy storage element and the load to control the on / off state of the discharge circuit; The third switching valve group and the recovery inductor are connected in series to form a recovery branch. This recovery branch is connected in parallel across the two ends of the energy storage element to reverse the voltage polarity of the energy storage element through LC resonance to achieve energy recovery. The fourth switching valve group and the discharge resistor are connected in series to form a discharge branch. This discharge branch is connected in parallel to both ends of the energy storage element. The fourth switching valve group is a normally open switching device group, which is turned off when a control signal is applied and turned on when the control signal is removed. The first, second, third, and fourth switch valve groups constitute a hybrid switch architecture, wherein: The first switching valve assembly uses a turn-off type semiconductor switching device; The second and third switching valve groups each employ thyristor switching devices; The fourth switching valve group uses normally open semiconductor switching devices.

2. The active pulse discharge energy recovery and energy dissipation system according to claim 1, characterized in that, The turn-off type semiconductor switching device is a silicon carbide MOSFET, and the normally open type semiconductor switching device is a silicon carbide junction field-effect transistor. The fourth switching valve group is composed of multiple silicon carbide junction field-effect transistors connected in series, and adopts a common-source back-to-back structure. A static voltage equalization resistor and a dynamic voltage equalization capacitor are connected in parallel between the drain and gate of each junction field-effect transistor.

3. The active pulse discharge energy recovery and energy dissipation system according to claim 1, characterized in that, The fourth switch valve group is kept closed by the control signal during normal system operation. When the system loses power, the control signal is lost, or a sudden fault occurs, the control signal is automatically removed. The fourth switch valve group is turned on instantaneously, allowing the energy storage element to form an energy discharge path through the discharge resistor.

4. The active pulse discharge energy recovery and energy dissipation system according to claim 1, characterized in that, The first switching valve group is composed of multiple silicon carbide MOSFETs connected in series. Each MOSFET is connected in parallel with a static voltage equalization resistor, a dynamic voltage equalization branch composed of a resistor and a capacitor connected in series, and an overvoltage protection element. The second and third switching valve groups are each composed of multiple thyristors connected in series; The rated parameters of a single thyristor in the third switching valve group of the recovery branch meet the following requirements: ； ； in, This refers to the rated repetitive peak blocking voltage of a single thyristor. This represents the maximum non-repetitive surge current peak allowed for a single thyristor. This is the rated operating voltage of the energy storage element. This represents the total number of thyristors connected in series in the third switching valve group. This refers to the reverse voltage amplitude that the energy storage element receives due to load freewheeling after the main pulse discharge ends. This refers to the capacitance value of the energy storage element. To recover the inductance value, 0.85 refers to the series voltage equalization derating factor; 2.0 refers to the overvoltage safety margin factor.

5. The active pulse discharge energy recovery and energy dissipation system according to claim 4, characterized in that, The recovery inductance value in the recovery branch The following conditions must be met: ； in, This refers to the reverse voltage amplitude that the energy storage element receives due to load freewheeling after the main pulse discharge ends. For the maximum allowable rate of current rise, Available recycling time, This represents the capacitance value of the energy storage element.

6. The active pulse discharge energy recovery and energy dissipation system according to claim 1, characterized in that, The number of series-connected devices in the fourth switching valve group satisfies the following: ； ； in, This refers to the number of normally open switching devices connected in series. This is the highest operating voltage of the energy storage element. This is the rated blocking voltage of a single normally open switching device. This represents the maximum allowable drain current for a single normally open switching device. The value of the bleeder resistor is 0.85, which refers to the series voltage derating factor; 2.0 refers to the overvoltage safety margin factor. The system also includes a control unit, which outputs timing control signals for each switching valve group to achieve active timing control of each stage of charging, discharging, energy recovery and energy release.

7. An active pulse discharge energy recovery and energy dissipation method, applied to the active pulse discharge energy recovery and energy dissipation system according to any one of claims 1-6, characterized in that, include: During the charging phase, the first switching valve group is turned on, enabling the charging module to charge the energy storage element; During the waiting phase, the first switch valve group is shut off, while the second, third, and fourth switch valve groups remain shut off, and the energy storage element is in a high-voltage standby state. During the discharge phase, the second switching valve group is turned on, causing the energy storage element to release pulse energy to the load. After the discharge is completed, the voltage across the energy storage element is reversed by utilizing the freewheeling effect of the load. During the maintenance phase, the second switching valve group is kept closed, and the positive blocking capability is awaited to be restored. During the recovery phase, the third switching valve group is turned on, so that the energy storage element and the recovery inductor form an LC resonant circuit, which converts the reverse voltage polarity of the energy storage element to the positive voltage polarity, thus completing the energy recovery. During the discharge phase, the control signal of the fourth switching valve group is removed. Taking advantage of the characteristic of the fourth switching valve group that it automatically turns on when the control signal is lost, the energy storage element forms a discharge path through the discharge resistor to consume the residual energy.

8. The active pulse discharge energy recovery and energy release method according to claim 7, characterized in that, The charging phase is preceded by a pre-charging phase: before charging begins, a control signal is applied to the fourth switching valve group to keep it off, ensuring that the energy storage element is isolated from the discharge resistor. During the maintenance phase, the third switching valve group is prohibited from being turned on until the second switching valve group fully restores its positive blocking capability.

9. The active pulse discharge energy recovery and energy release method according to claim 7, characterized in that, The timing control of each switching valve group must meet the following conditions: ； in, The shut-off duration of the first switching valve group. The trigger pulse width for the second switching valve group. The trigger pulse width for the third switching valve group. The time delay between the shutdown of the first switching valve group and the activation of the second switching valve group. The time delay between the shut-off of the second switching valve group and the turn-on of the third switching valve group. For the system's repetitive cycle, This refers to the capacitance value of the energy storage element. This refers to the operating voltage of the energy storage element. This refers to the charging current of the charging module; ； ； in, This is the time margin factor, with a value range of 1.2 to 2; It is the ratio of the forward turn-off time to the reverse recovery time under a microsecond pulse width, and its value ranges from 5 to 8; This is the reverse recovery time of the second switching valve group.

10. The active pulse discharge energy recovery and energy release method according to claim 7, characterized in that, During the discharge phase, the fourth switching valve group is always in the off state with a control signal applied during normal system operation. It is only automatically turned on when the last operating cycle of the system ends or when a sudden failure causes the control signal to be lost, so as to consume the remaining residual energy in the energy storage element through the discharge resistor.

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