Self-excitation type multi-phase air core pulse generator power supply system and control method thereof

Abstract

The invention relates to the technical field of pulse generator excitation magnetic field regulation and control, and discloses a self-excitation type multiphase air core pulse generator power supply system and a control method thereof. In the system, an excitation module is connected in parallel with two ends of an excitation winding of a pulse generator; the central point of the self-excitation rectifier is connected with an armature winding of the pulse generator, and two ends of the self-excitation rectifier are connected with an excitation winding of the pulse generator; and the self-excitation forced turn-off module is connected in parallel with two ends of the excitation winding, and is used for generating reverse current through discharging after the self-excitation enable signal is removed, so that the current of the thyristor which is conducted in the last phase in the self-excitation rectifier is forced to be reduced to zero. The self-excitation forced turn-off module is additionally arranged, reverse current is generated through discharging, the current of a thyristor conducted in the last phase of the self-excitation rectifier can be forced to be rapidly reduced to zero after a self-excitation enable signal is removed, and the industrial problem that the thyristor in the multi-phase self-excitation rectification topology cannot be reliably turned off is thoroughly solved.

Description

A self-excited multiphase air-core pulse generator power supply system and its control method Technical Field

[0001] This invention relates to the field of pulse generator excitation field control technology, specifically to a self-excited multiphase air-core pulse generator power supply system and its control method. Background Technology

[0002] Improving power and energy storage density has always been a development direction for high-power pulse power supply systems. These systems slowly store electrical and mechanical energy at relatively low power levels and release it transiently as needed, achieving energy compression and power multiplication over a time scale. Reducing the size and weight of the excitation device while ensuring excitation power is key to improving the energy storage and power density of pulse generators and meeting the miniaturization requirements of pulse power supplies. Among these, self-excited air-core pulse generators, which can establish a stable and controllable strong magnetic field without large-capacity excitation capacitors, significantly reducing the demand for external energy for excitation, have become a research hotspot in this field.

[0003] Existing pulse generator excitation control systems typically employ a full-bridge rectification self-excitation method using all thyristors. The generator's self-excitation efficiency and the established magnetic field strength are adjusted by controlling the thyristor firing angle. However, multiphase generators require a large number of thyristor rectifiers, leading to increased hardware costs, complex control logic, and a tendency for signal synchronization deviations at high speeds. To address this, the industry has proposed a hybrid self-excitation magnetic topology that replaces half of the thyristors in the self-excited rectifier bridge with uncontrolled diodes. This topology achieves both current controllability and improved self-excitation efficiency. However, due to the differences in turn-off and conduction conditions between thyristors and diodes, in practical engineering applications of pulse generators, the thyristor in the last phase of the self-excitation process may fail to turn off in a single cycle, resulting in continuous conduction. This leads to excessive current stress on the switching transistors and heat loss, causing safety issues and limiting the engineering application and promotion of the hybrid self-excitation magnetic topology. Summary of the Invention

[0004] This invention provides a method and device for turning off the self-excited magnetic thyristor of a multiphase air-core pulse generator, in order to solve the problem that the thyristor of the last phase cannot be reliably turned off within a single cycle after the self-excitation of the multiphase air-core pulse generator ends.

[0005] In a first aspect, the present invention provides a self-excited multiphase air-core pulse generator power supply system, the system comprising: a prime mover, an excitation module, a self-excited forced shutdown module, a freewheeling module, a pulse generator, and a self-excited rectifier, wherein the prime mover is coupled to the pulse generator and drives the pulse generator rotor to rotate and store energy to a rated speed; the excitation module is connected in parallel across the excitation winding of the pulse generator and injects a seed current into the excitation winding to establish an initial excitation magnetic field; the center point of the self-excited rectifier is connected to the armature winding of the pulse generator. The self-excited rectifier is connected to the excitation winding of the pulse generator at both ends. It is used to trigger its own thyristors to form positive feedback between the armature winding induced voltage and the excitation current, thereby increasing the excitation current. The self-excited forced shutdown module is connected in parallel across the excitation winding. After the self-excited enable signal is removed, it generates a reverse current by discharging, forcing the thyristor current of the last phase in the self-excited rectifier to drop to zero. The freewheeling module is connected in parallel across the excitation winding. It is used to provide a freewheeling path for the excitation current after the self-excited forced shutdown module is turned off.

[0006] This invention provides a self-excited multiphase air-core pulse generator power supply system. It innovatively adds a self-excited forced turn-off module, which generates a reverse current through discharge. This forces the thyristor current in the last phase of the self-excited rectifier to rapidly drop to zero after the self-excitement enable signal is removed, completely solving the industry problem of unreliable thyristor turn-off in multiphase self-excited rectifier topologies. Combined with the unidirectional conduction characteristic of the freewheeling module, it provides a low-impedance freewheeling path for the inertial current of the excitation winding, avoiding instantaneous overvoltage damage to devices caused by sudden current changes, and significantly reducing the system failure rate.

[0007] In one optional embodiment, the self-excited forced turn-off module includes: a first capacitor, a first thyristor, a first resistor, and a first diode. One end of the first capacitor is connected to one end of the excitation winding and one end of the first resistor, respectively. The other end of the first capacitor is connected to the first end of the first thyristor. The second end of the first thyristor is connected to the cathode of the first diode and the other end of the excitation winding, respectively. The control terminal of the first thyristor receives a trigger pulse from the measurement and control system. The anode of the first diode is connected to the other end of the first resistor. The first thyristor is turned on after receiving the trigger pulse. After the first thyristor is turned on, the first capacitor releases its pre-stored charge, generating a reverse current opposite to the original conduction current of the last-phase conducting thyristor in the self-excited rectifier. This reverse current is superimposed on the original conduction current to force the total current flowing out of the self-excited rectifier to drop to zero within less than 1 / 4 of the current cycle, thus turning off the last-phase conducting thyristor.

[0008] In one optional embodiment, the system further includes a discharge rectifier connected to the armature winding, which receives a trigger pulse from the measurement and control system after the excitation current reaches a set value, converts the electrical energy of the pulse generator into pulse power, and drives the electromagnetic track load to work.

[0009] In one optional embodiment, the excitation module includes: a second capacitor and a second thyristor, wherein one end of the second capacitor is connected to one end of the excitation winding, the other end of the second capacitor is connected to the first end of the second thyristor, the second end of the second thyristor is connected to the other end of the excitation winding, and the control terminal of the second thyristor receives trigger pulses from the measurement and control system.

[0010] In one optional implementation, the freewheeling module includes a second diode, the anode of which is connected to one end of the excitation winding, and the cathode of which is connected to the other end of the excitation winding.

[0011] In one optional implementation, the system further includes a measurement and control system, which interacts with a central computer to send self-excitation enable signals, discharge commands, and trigger pulses in the self-excitation forced shutdown module that control the first thyristor to conduct.

[0012] In one optional embodiment, the system further includes: a photoelectric rotor position detection device, which is configured corresponding to the rotor of the pulse generator and is used to output a rotor position detection signal to the measurement and control system.

[0013] Secondly, the present invention provides a control method for a self-excited multiphase air-core pulse generator power supply system. The method includes: using a prime mover to drive the rotor of the pulse generator to rotate and store energy to the rated speed, triggering the excitation module to inject a seed current into the excitation winding to establish an initial excitation magnetic field; triggering the thyristor of the self-excited rectifier to conduct, so that the induced voltage of the armature winding and the excitation current form positive feedback, driving the excitation current to increase; when the excitation current increases to a set value, removing the self-excitation enable signal issued by the measurement and control system; according to the trigger pulse issued by the measurement and control system, controlling the self-excited forced shutdown module to discharge and generate a reverse current, superimposing the reverse current on the original conducting current, forcing the current flowing out of the excitation bridge of the self-excited rectifier to drop to zero.

[0014] This invention provides a self-excited multiphase air-core pulse generator power supply system, which innovatively adds a self-excited forced shutdown module. By generating reverse current through discharge, it can quickly force the thyristor current of the last phase of the self-excited rectifier to drop to zero after the self-excited enable signal is removed, thus completely solving the industry problem of the inability of thyristors to be reliably turned off in multiphase self-excited rectifier topologies.

[0015] In one optional implementation, according to the trigger pulse issued by the measurement and control system, the self-excited forced shutdown module is controlled to discharge and generate a reverse current. The reverse current is superimposed on the original conducting current, forcing the current flowing out of the excitation bridge of the self-excited rectifier to drop to zero. This includes: pre-charging the first capacitor of the self-excited forced shutdown module and the second capacitor of the excitation module in parallel, so that the first capacitor obtains an initial voltage consistent with the second capacitor and stores the discharge charge; when the current flowing through the thyristor of the remaining conducting phase of the self-excited rectifier reaches its peak value and begins to decrease, the measurement and control system issues a trigger pulse to control the first thyristor in the self-excited forced shutdown module to conduct; after the first thyristor conducts, the first capacitor releases the pre-stored charge, generating a reverse current in the opposite direction to the original conducting current of the last conducting thyristor in the self-excited rectifier. The reverse current is superimposed on the original conducting current to force the total current flowing out of the self-excited rectifier to drop to zero within less than 1 / 4 of the current cycle, causing the last conducting thyristor to turn off. Attached Figure Description

[0016] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0017] Figure 1 is a schematic diagram of the first structure of a self-excited multiphase air-core pulse generator power supply system according to an embodiment of the present invention; Figure 2 is a schematic diagram of the second structure of a self-excited multiphase air-core pulse generator power supply system according to an embodiment of the present invention; Figure 3 is a circuit diagram of the thyristor turn-off circuit at the end of self-excitation according to an embodiment of the present invention; Figure 4 is a flowchart of the control method of the self-excited multiphase air-core pulse generator power supply system according to an embodiment of the present invention. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0019] It is understood that before using the technical solutions disclosed in the various embodiments of the present invention, users should be informed of the types, scope of use, and usage scenarios of the personal information involved in the present invention and their authorization should be obtained in accordance with relevant laws and regulations through appropriate means.

[0020] This invention provides a self-excited multiphase air-core pulse generator power supply system, as shown in Figure 1, including: a prime mover 1, an excitation module 2, a self-excited forced shutdown module 3, a freewheeling module 4, a pulse generator 5, and a self-excited rectifier 6. The inductor L... f and resistance R f These are the inductance and resistance of the excitation winding of the pulse generator 5, and eight inductors L. s With eight resistors R s Each component corresponds to one of the inductance and resistance of the eight-phase armature winding of the pulse generator 5. The armature winding and excitation winding are respectively bonded to the surfaces of the stator yoke and rotor yoke, and secured using carbon fiber. The prime mover 1 is not shown in Figures 1 and 2.

[0021] The prime mover 1 operates shaft-connected to the pulse generator 5, driving the rotor of the pulse generator 5 to rotate and store energy to its rated speed. The excitation module 2 is connected in parallel across the excitation winding of the pulse generator 5, injecting a seed current into the excitation winding to establish the initial excitation magnetic field. The center point of the self-excited rectifier 6 is connected to the armature winding of the pulse generator 5, and its two ends are connected to the excitation winding of the pulse generator 5. It triggers its own thyristors to create positive feedback between the induced voltage in the armature winding and the excitation current, thus increasing the excitation current. The self-excited forced shutdown module 3 is connected in parallel across the excitation winding. After the self-excited enable signal is removed, it generates a reverse current through discharge, forcing the thyristor current in the last phase of the self-excited rectifier 6 to drop to zero. The freewheeling module 4 is connected in parallel across the excitation winding, providing a freewheeling path for the excitation current after the self-excited forced shutdown module 3 is turned off.

[0022] Specifically, the prime mover 1 starts first, driving the rotor of the pulse generator 5 to rotate via a coupling until it reaches its rated speed. At this point, the rotor stores mechanical energy in the form of kinetic energy. After the prime mover 1 reaches its rated speed, the excitation module 2 starts synchronously. Since the excitation module 2 is connected in parallel across the excitation winding of the pulse generator 5, it can directly inject a seed current into the excitation winding, establishing an initial excitation magnetic field through the principle of electromagnetic induction. After the excitation module 2 establishes the initial magnetic field, the self-excited rectifier 6 starts, forming a closed self-excited circuit. The thyristors in the self-excited rectifier 6 are triggered. At this time, the armature winding of the pulse generator 5 has generated an induced voltage due to the rotor rotation cutting the initial magnetic field. This induced voltage is applied to both ends of the excitation winding, and the armature winding current is superimposed with the seed current injected by the excitation module, further increasing the excitation current. As the excitation current in the excitation winding of the pulse generator gradually increases, the excitation magnetic field it generates will synchronously become stronger, further increasing the induced voltage in the armature winding; this cycle repeats, forming a closed-loop positive feedback, allowing the excitation current and the corresponding magnetic field strength to continuously superimpose and increase until the system's preset target value is reached. For an eight-phase air-core pulse generator, after setting a suitable self-excitation trigger angle, four phases are always conducting simultaneously during the self-excitation process, with two phases overlapping and commutating.

[0023] When the excitation current reaches the set value, the measurement and control system immediately removes the self-excitation enable signal. The thyristors of the self-excited rectifier 6 no longer receive new trigger pulses, the positive feedback loop terminates, and the self-excitation current also changes from two-phase discharge to single-phase discharge until all self-excited thyristors are finally turned off. The measurement and control system sends a trigger pulse to the self-excited forced turn-off module 3. Because the self-excited forced turn-off module 3 is connected in parallel across the excitation winding, after its internal thyristors are turned on, the pre-charged capacitor discharges rapidly, generating a reverse current opposite to the original current of the last phase thyristor in the self-excited rectifier 6. The reverse current and the original conducting current are superimposed, forming a current cancellation effect, forcing the total current flowing out of the excitation bridge of the self-excited rectifier 6 to rapidly drop to zero within <1 / 4 of the current cycle, ultimately allowing the last phase thyristor to reliably turn off. After the self-excited forced turn-off module 3 completes the thyristor turn-off, an inertial excitation current still remains in the excitation winding. If the current has no release path, it will generate instantaneous high voltage that damages the devices. Since the freewheeling module 4 is connected in parallel across the excitation winding, it automatically turns on at this time, providing a low-impedance freewheeling path for the inertial excitation current. The current flows continuously through the freewheeling module 4, and the magnetic field energy decays slowly.

[0024] The hybrid circuit structure in the self-excited rectifier 6, which uses diodes to replace half of the bridge arm thyristors, can save 50% of the thyristor devices and realize the excitation controllability of the pulse generator. It also has a significant positive effect on increasing the excitation current to improve the self-excitation efficiency and suppressing the drop in excitation current when entering the pre-discharge state after the self-excitation ends.

[0025] This invention provides a self-excited multiphase air-core pulse generator power supply system. It innovatively adds a self-excited forced turn-off module, which generates a reverse current through discharge. This forces the thyristor current in the last phase of the self-excited rectifier to rapidly drop to zero after the self-excitement enable signal is removed, completely solving the industry problem of unreliable thyristor turn-off in multiphase self-excited rectifier topologies. Combined with the unidirectional conduction characteristic of the freewheeling module, it provides a low-impedance freewheeling path for the inertial current of the excitation winding, avoiding instantaneous overvoltage damage to devices caused by sudden current changes, and significantly reducing the system failure rate.

[0026] In an optional implementation, as shown in FIG2, the system further includes a discharge rectifier 7, which is connected to the armature winding and is used to receive the trigger pulse of the measurement and control system after the excitation current reaches the set value, convert the electrical energy of the pulse generator 5 into pulse power, and drive the electromagnetic track load 8 to work.

[0027] Specifically, after the current continues to flow and the system reaches a stable state, the measurement and control system sends a discharge trigger pulse to the discharge rectifier 7. The discharge rectifier 7 is connected to the armature winding of the pulse generator 5, receives the electromagnetic energy output by the generator, and converts it into transient high-power pulse power; finally, the pulse power is output to the electromagnetic rail load 8 to complete the energy conversion.

[0028] In one optional implementation, the system further includes a measurement and control system that interacts with a central computer to send self-excitation enable signals, discharge commands, and trigger pulses in the self-excitation forced shutdown module 3 to control the conduction of the first thyristor.

[0029] Specifically, the measurement and control system is the core scheduling unit of the entire self-excited multiphase air-core pulse generator power system. Through data interaction with the central computer and the issuance of instructions to various functional modules, it realizes precise timing control and closed-loop monitoring of the entire system process.

[0030] The measurement and control system first interacts with the central computer to obtain core parameter thresholds such as the rated speed of the pulse generator rotor, the target value of the excitation current, the duration of the self-excitation enable signal, the forced shutdown trigger sequence, and the timing of the discharge pulse. Then, it sends self-test commands to the prime mover 1, excitation module 2, self-excitation forced shutdown module 3, and discharge rectifier 7 to confirm that the status of the switching devices and the circuit connections of each component are fault-free. Simultaneously, it completes the pre-charging of the first capacitor in the self-excitation forced shutdown module 3 to ensure that all components enter the standby ready state.

[0031] The measurement and control system sends a start command to the prime mover 1, driving it to rotate the rotor of the pulse generator 5 and collecting the rotor speed signal in real time. When the speed reaches the rated value, it immediately sends a trigger pulse to the excitation module 2, controlling it to inject a seed current into the excitation winding to establish the initial excitation magnetic field. After the initial magnetic field is established, the measurement and control system sends a self-excitation enable signal to the self-excited rectifier 6, triggering its internal thyristors to conduct, starting the positive feedback loop of excitation current and magnetic field strength, and continuously amplifying the magnetic field.

[0032] During the magnetic field amplification process, the measurement and control system continuously collects the excitation winding current signal and compares it with the preset target value. When the excitation current reaches the set value, the self-excitation enable signal is removed and a forced shutdown trigger pulse is sent. After the thyristor is completely turned off and the excitation current smoothly transitions to the freewheeling channel of the freewheeling module 4, the system is confirmed to have entered a stable magnetic field energy storage state.

[0033] In one optional embodiment, the system further includes: a photoelectric rotor position detection device, which is configured corresponding to the rotor of the pulse generator 5, and is used to output a rotor position detection signal to the measurement and control system.

[0034] Specifically, the photoelectric rotor position detection device is configured corresponding to the rotor of the pulse generator 5, typically installed on the stator side of the generator, directly opposite the light-blocking / reflective markings (such as slotted discs or reflective patches) on the rotor. Its operation is based on the photoelectric sensing principle: the photoelectric rotor position detection device continuously outputs a light signal; as the rotor rotates, the markings move synchronously with the rotor, periodically blocking or reflecting the light signal; the receiving end converts the mechanical position change of the rotor into a rotor position detection signal in the form of electrical pulses based on the on / off changes of the light signal, and transmits it to the measurement and control system in real time.

[0035] In one optional implementation, as shown in Figures 1 and 2, the self-excited forced shutdown module 3 includes: a first capacitor C1, a first thyristor T1, a first resistor R1, and a first diode D1. One end of the first capacitor C1 is connected to one end of the excitation winding and one end of the first resistor R1, respectively. The other end of the first capacitor C1 is connected to the first end of the first thyristor T1. The second end of the first thyristor T1 is connected to the cathode of the first diode D1 and the other end of the excitation winding, respectively. The control terminal of the first thyristor T1 receives a trigger pulse from the measurement and control system, and the anode of the first diode D1 is connected to the other end of the first resistor. The first thyristor T1 is used to turn on after receiving the trigger pulse. After the first thyristor turns on, the first capacitor C1 releases its pre-stored charge, generating a reverse current opposite to the original conduction current of the last conducting thyristor in the self-excited rectifier 6. This reverse current is superimposed on the original conduction current to force the total current flowing out of the self-excited rectifier 6 to drop to zero within less than 1 / 4 of the current cycle, thus turning off the last conducting thyristor.

[0036] Specifically, before system self-test and self-excitation start-up, the first thyristor T1 is in the off state, and the first capacitor C1 and the second capacitor C0 of the excitation module are connected in parallel for pre-charging to obtain the same initial voltage to store discharge capacity. During the period when the self-excited rectifier 6 triggers the thyristor to start positive feedback and the excitation current continues to rise, the first thyristor T1 remains off, and the first capacitor C1 remains in the pre-charged state. When the excitation current reaches the set value, the measurement and control system synchronously removes the self-excitation enable signal and sends a trigger pulse to the control terminal of the first thyristor T1. After receiving the pulse, the first thyristor T1 quickly turns on, establishing a closed discharge circuit and providing a path for the generation of reverse current. After the first thyristor T1 turns on, the pre-charged C1 quickly releases its charge through the closed circuit, generating a reverse current that is opposite to the original conduction current direction of the last phase conducting thyristor in the self-excited rectifier 6. The reverse current and the original conducting current are superimposed in the excitation winding branch, forming a current cancellation effect, which forces the total current flowing out of the excitation bridge of the self-excited rectifier 6 to drop rapidly to zero in less than 1 / 4 of the current cycle.

[0037] Figure 3 shows the phased equivalent circuit of the self-excited thyristor turn-off assisted by the first capacitor C1. When the current flowing through the remaining thyristor reaches its peak and begins to decrease, the first capacitor C1 begins to discharge, and the capacitor current rises rapidly until it reaches the excitation current. After the thyristor turns off, the capacitor current drops rapidly to zero through the second diode D2.

[0038] To reduce the number of chargers, the first capacitor C1 and the second capacitor C0 are connected in parallel for pre-charging, with the same initial voltage. When determining the critical minimum value of the parameters of the first capacitor C1, to simplify the analysis, the case where the discharge capacity requirement is maximized and the thyristor can reliably turn off for the longest time should be considered. According to... The time it takes for the current to drop in the first capacitor C1 is negligible. The required charge can be calculated by the area enclosed by the capacitor current curve and the time, thus allowing us to calculate the theoretical minimum value of the turn-off capacitor C1 that ensures reliable turn-off of the thyristor. The larger the auxiliary turn-off capacitor value, the shorter the turn-off time of the thyristor.

[0039] In one optional embodiment, as shown in Figures 1 and 2, the excitation module 2 includes a second capacitor C0 and a second thyristor T0. One end of the second capacitor C0 is connected to one end of the excitation winding, the other end of the second capacitor C0 is connected to the first end of the second thyristor T0, the second end of the second thyristor T0 is connected to the other end of the excitation winding, and the control terminal of the second thyristor T0 receives trigger pulses from the measurement and control system.

[0040] Specifically, after the prime mover 1 drives the rotor of the pulse generator 5 to reach the rated speed, the measurement and control system immediately sends a trigger pulse to the control terminal of the second thyristor T0. Upon receiving the pulse, the second thyristor T0 quickly turns on, and the second capacitor C0 releases its pre-stored charge, injecting a weak and stable seed current into the excitation winding. Once the measurement and control system detects that the initial magnetic field strength of the excitation winding has reached the target, it immediately stops sending trigger pulses to the second thyristor T0. After the second thyristor T0 loses its conduction signal, it quickly turns off, the injection circuit is disconnected, and the second capacitor C0 stops discharging.

[0041] In one optional implementation, the freewheeling module 4 includes: a second diode D2, the anode of the second diode D2 being connected to one end of the excitation winding, and the cathode of the second diode D2 being connected to the other end of the excitation winding.

[0042] Specifically, when the self-excited forced shutdown module 3 completes the turn-off of the last phase thyristor, the current path of the self-excited circuit is cut off. Due to the inductive characteristic that the current of the excitation winding cannot change abruptly, it will instantly generate a reverse electromotive force to maintain the current flow. At this time, the direction of the excitation current reverses and is consistent with the conduction direction of the second diode D2. The second diode D2 immediately conducts in the forward direction, building a closed freewheeling circuit for the inertial current, so that the current decays at a gentle slope.

[0043] This invention provides a control method for a self-excited multiphase air-core pulse generator power supply system. Based on the self-excited multiphase air-core pulse generator power supply system shown in Figures 1 and 2, as shown in Figure 4, the method includes the following steps: Step S1, using the prime mover 1 to drive the rotor of the pulse generator 5 to rotate and store energy to the rated speed, triggering the excitation module 2 to inject seed current into the excitation winding to establish the initial excitation magnetic field.

[0044] Specifically, the prime mover 1 starts, driving the rotor of the pulse generator 5 to rotate via a coupling until it reaches its rated speed. This process converts the mechanical energy of the prime mover 1 into the kinetic energy of the rotor and stores it. After the rotor reaches its rated speed, the measurement and control system triggers the excitation module 2 to inject a seed current into the excitation winding of the pulse generator 5. According to the principle of electromagnetic induction, the excitation winding generates an initial excitation magnetic field after current is applied.

[0045] Step S2 triggers the thyristor of the self-excited rectifier 6 to conduct, so that the armature winding induced voltage and the excitation current form positive feedback, driving the excitation current to increase.

[0046] Specifically, the measurement and control system sends a self-excitation enable signal to the self-excited rectifier 6, triggering the internal thyristors to conduct and establishing a closed self-excited circuit. The initial excitation magnetic field established in the armature winding cutting step S1 generates an induced voltage. The armature current flows into the excitation winding through the conducting thyristors, superimposing with the seed current to increase the excitation current. The increase in excitation current directly leads to a stronger excitation magnetic field, which in turn increases the rate of change of magnetic flux cut by the armature winding, further increasing the induced voltage. This cycle repeats, forming positive feedback. Through the positive feedback effect, the initial weak magnetic field is continuously amplified until the excitation current reaches the system's preset target value.

[0047] Step S3: When the excitation current increases to the set value, the self-excitation enable signal sent by the measurement and control system is removed.

[0048] Specifically, the measurement and control system collects the current signal of the excitation winding in real time. When the excitation current is detected to increase to the set value, it determines that the magnetic field strength meets the standard. The control system immediately removes the self-excitation enable signal, and the thyristors of the self-excited rectifier 6 no longer receive new trigger pulses. Theoretically, the positive feedback loop will gradually terminate.

[0049] Step S4: According to the trigger pulse issued by the measurement and control system, control the self-excited forced shutdown module 3 to discharge and generate reverse current. The reverse current is superimposed on the original conduction current, forcing the current flowing out of the excitation bridge of the self-excited rectifier 6 to drop to zero.

[0050] Specifically, while removing the self-excitation enable signal, the measurement and control system sends a trigger pulse to the self-excitation forced turn-off module 3 to control the conduction of its internal thyristors; the pre-charged capacitor discharges rapidly, generating a reverse current opposite to the original current of the last-phase conducting thyristor in the self-excited rectifier 6. The reverse current and the original conducting current are superimposed in the excitation winding branch, forming a current cancellation effect, forcing the total current flowing out of the excitation bridge of the self-excited rectifier 6 to drop rapidly to zero within less than 1 / 4 of the current cycle; at this time, the last-phase conducting thyristor meets the turn-off condition and achieves reliable turn-off.

[0051] This invention provides a self-excited multiphase air-core pulse generator power supply system, which innovatively adds a self-excited forced shutdown module. By generating reverse current through discharge, it can quickly force the thyristor current of the last phase of the self-excited rectifier to drop to zero after the self-excited enable signal is removed, thus completely solving the industry problem of the inability of thyristors to be reliably turned off in multiphase self-excited rectifier topologies.

[0052] In an optional implementation, step S4 includes: step S41, connecting the first capacitor C1 of the self-excited forced shutdown module 3 and the second capacitor C0 of the excitation module 2 in parallel for pre-charging, so that the first capacitor C1 obtains an initial voltage consistent with the second capacitor C0, and stores discharge capacity.

[0053] In step S42, when the current flowing through the thyristor of the remaining one phase of the self-excited rectifier reaches its peak value and begins to decrease, a trigger pulse is sent through the measurement and control system to control the first thyristor T1 in the self-excited forced shutdown module 3 to turn on.

[0054] In step S43, after the first thyristor T1 is turned on, the first capacitor C1 releases the pre-stored charge, generating a reverse current that is opposite to the original conduction current of the last phase thyristor in the self-excited rectifier 6. The reverse current is superimposed on the original conduction current to force the total current flowing out of the self-excited rectifier 6 to drop to zero in less than 1 / 4 of the current cycle, so that the last phase thyristor is turned off.

[0055] Specifically, before system self-test and self-excitation start-up, the first thyristor T1 is in the off state, and the first capacitor C1 and the second capacitor C0 of the excitation module are connected in parallel for pre-charging to obtain the same initial voltage to store discharge capacity. During the period when the self-excited rectifier 6 triggers the thyristor to start positive feedback and the excitation current continues to rise, the first thyristor T1 remains off, and the first capacitor C1 remains in the pre-charged state. When the excitation current reaches the set value, the measurement and control system synchronously removes the self-excitation enable signal and sends a trigger pulse to the control terminal of the first thyristor T1. After receiving the pulse, the first thyristor T1 quickly turns on, establishing a closed discharge circuit and providing a path for the generation of reverse current. After the first thyristor T1 turns on, the pre-charged C1 quickly releases its charge through the closed circuit, generating a reverse current that is opposite to the original conduction current direction of the last phase conducting thyristor in the self-excited rectifier 6. The reverse current and the original conducting current are superimposed in the excitation winding branch, forming a current cancellation effect, which forces the total current flowing out of the excitation bridge of the self-excited rectifier 6 to drop rapidly to zero in less than 1 / 4 of the current cycle.

[0056] Furthermore, since the self-excited rectifier 6 has a multi-phase topology, when the self-excitement enable signal is removed, due to the natural commutation characteristics of the diodes, the current in the branch where the diode is located continues to commutate normally between different phases during the conduction period of the last phase thyristor in the self-excitement process. Therefore, the required turn-off time of the thyristor increases, and the conduction time exceeds half a cycle. This phenomenon makes it difficult for the self-excited circuit to transition normally to the freewheeling stage. The continuous conduction of the winding causes the corresponding thyristor to be subjected to high current stress, which easily leads to thyristor breakdown. The node where the thyristor phase current reaches its peak and begins to decline is chosen because turning on the self-excited forced turn-off module at this time will not affect the self-excitement process, and can turn off the thyristor of the self-excited module as quickly and reliably as possible to enter the preparatory state for pulse discharge, reducing the drop loss of the excitation current. If the trigger is delayed until the end of the decay period of the thyristor current in the last phase, the complexity of the trigger signal timing control under different speeds and operating conditions is greatly increased, and the universality of parameter settings is lacking.

[0057] Although embodiments of the invention have been described in conjunction with the accompanying drawings, those skilled in the art can make various modifications and variations without departing from the spirit and scope of the invention, and all such modifications and variations fall within the scope defined by the appended claims.

Claims

1. A self-excited multiphase air-core pulse generator power supply system, characterized in that, The system includes: a prime mover, an excitation module, a self-excited forced shutdown module, a freewheeling module, a pulse generator, and a self-excited rectifier. The prime mover is coupled to the pulse generator and drives the generator rotor to rotate and store energy to its rated speed. The excitation module is connected in parallel across the excitation winding of the pulse generator to inject a seed current into the excitation winding and establish an initial excitation magnetic field. The center point of the self-excited rectifier is connected to the armature winding of the pulse generator, and its two ends are connected to the excitation winding. It triggers its own thyristors to create positive feedback between the induced voltage in the armature winding and the excitation current, thereby increasing the excitation current. The self-excited forced shutdown module is connected in parallel across the excitation winding. After the self-excitation enable signal is removed, it generates a reverse current through discharge, forcing the thyristor current in the last conducting phase of the self-excited rectifier to drop to zero. The freewheeling module is connected in parallel across the excitation winding to provide a freewheeling path for the excitation current after the self-excited forced shutdown module is turned off.

2. The self-excited multiphase air-core pulse generator power supply system according to claim 1, characterized in that, The self-excited forced turn-off module includes: a first capacitor, a first thyristor, a first resistor, and a first diode. One end of the first capacitor is connected to one end of the excitation winding and one end of the first resistor, respectively. The other end of the first capacitor is connected to the first end of the first thyristor. The second end of the first thyristor is connected to the cathode of the first diode and the other end of the excitation winding, respectively. The control terminal of the first thyristor receives a trigger pulse from the measurement and control system. The anode of the first diode is connected to the other end of the first resistor. The first thyristor is used to turn on after receiving the trigger pulse. After the first thyristor turns on, the first capacitor releases its pre-stored charge, generating a reverse current opposite to the original conduction current of the last conducting thyristor in the self-excited rectifier. The reverse current is superimposed on the original conduction current to force the total current flowing out of the self-excited rectifier to drop to zero within less than 1 / 4 of the current cycle, thereby turning off the last conducting thyristor.

3. The self-excited multiphase air-core pulse generator power supply system according to claim 1, characterized in that, The system further includes a discharge rectifier, which is connected to the armature winding and is used to receive a trigger pulse from the measurement and control system after the excitation current reaches a set value, converting the electrical energy of the pulse generator into pulse power to drive the electromagnetic track load.

4. The self-excited multiphase air-core pulse generator power supply system according to claim 1, characterized in that, The excitation module includes a second capacitor and a second thyristor, wherein one end of the second capacitor is connected to one end of the excitation winding, the other end of the second capacitor is connected to the first end of the second thyristor, the second end of the second thyristor is connected to the other end of the excitation winding, and the control terminal of the second thyristor receives the trigger pulse from the measurement and control system.

5. The self-excited multiphase air-core pulse generator power supply system according to claim 1, characterized in that, The freewheeling module includes a second diode, the anode of which is connected to one end of the excitation winding, and the cathode of which is connected to the other end of the excitation winding.

6. The self-excited multiphase air-core pulse generator power supply system according to claim 2, characterized in that, The system also includes a measurement and control system, which interacts with a central computer to send self-excitation enable signals, discharge commands, and trigger pulses that control the first thyristor to conduct in the self-excitation forced shutdown module.

7. The self-excited multiphase air-core pulse generator power supply system according to claim 6, characterized in that, The system further includes a photoelectric rotor position detection device, which is configured corresponding to the rotor of the pulse generator and is used to output a rotor position detection signal to the measurement and control system.

8. A control method for a self-excited multiphase air-core pulse generator power supply system, characterized in that, The method includes: using a prime mover to drive the rotor of a pulse generator to rotate and store energy to the rated speed, triggering the excitation module to inject a seed current into the excitation winding to establish an initial excitation magnetic field; triggering the thyristor of the self-excited rectifier to conduct, so that the induced voltage of the armature winding and the excitation current form positive feedback, driving the excitation current to increase; when the excitation current increases to a set value, removing the self-excitation enable signal issued by the measurement and control system; according to the trigger pulse issued by the measurement and control system, controlling the self-excited forced shutdown module to discharge and generate a reverse current, superimposing the reverse current on the original conducting current, forcing the current flowing out of the excitation bridge of the self-excited rectifier to drop to zero.

9. The control method for the self-excited multiphase air-core pulse generator power supply system according to claim 8, characterized in that, According to the trigger pulse issued by the measurement and control system, the self-excited forced shutdown module is controlled to discharge and generate a reverse current. The reverse current is superimposed on the original conducting current, forcing the current flowing out of the excitation bridge of the self-excited rectifier to drop to zero. This includes: pre-charging the first capacitor of the self-excited forced shutdown module in parallel with the second capacitor of the excitation module, so that the first capacitor obtains the same initial voltage as the second capacitor and stores the discharge charge; when the current flowing through the thyristor of the remaining conducting phase of the self-excited rectifier reaches its peak value and begins to decrease, the measurement and control system issues a trigger pulse to control the first thyristor in the self-excited forced shutdown module to conduct; after the first thyristor conducts, the first capacitor releases the pre-stored charge, generating a reverse current in the opposite direction to the original conducting current of the last conducting thyristor in the self-excited rectifier. The reverse current is superimposed on the original conducting current to force the total current flowing out of the self-excited rectifier to drop to zero in less than 1 / 4 of the current cycle, so that the last conducting thyristor is turned off.

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