Switched capacitor resonant large current pulse power supply and control method thereof

Abstract

The application provides a switched capacitor resonant large-current pulse power supply and a control method thereof. The switched capacitor resonant large-current pulse power supply comprises a DC input source, an inverter circuit, a resonant cavity and a transformer. The DC input source is connected with a DC end of the inverter circuit. The resonant cavity and a primary winding of the transformer are connected in series and then connected to an AC end of the inverter circuit. A secondary winding of the transformer is used for connecting a load. The transformer is a step-down transformer. The inverter circuit outputs a positive voltage square wave. The resonant cavity resonates to form a resonant current which is similar to a sine wave. The resonant current forms a large-current pulse through a load loop of the secondary winding of the transformer. When the resonant current reaches zero, the resonant current is maintained at zero. All switch tube devices can realize soft switching. By using the transformer, the current stress of semiconductor devices is reduced, and the reliability and efficiency are improved. Meanwhile, full-controlled devices are used to realize high-frequency pulse output.

Description

Technical Field

[0001] This invention relates to the field of pulse power technology, and in particular to a switched capacitor resonant high-current pulse power supply and its control method. Background Technology

[0002] Metal pulsed current treatment technology utilizes instantaneous high-energy current pulses to pass through the cross-section of metal materials, thereby improving the plasticity, ductility, and other properties of the materials. Its core lies in applying high-intensity current (peak values ​​can reach thousands to tens of thousands of amperes) within an extremely short time (usually on the order of microseconds to milliseconds). Compared with traditional heat treatment processes, this technology significantly improves material properties, has a fast processing speed, and a small heat-affected zone, making it an important processing technology for lightweight high-strength alloys such as titanium and magnesium.

[0003] like Figure 1 and Figure 2 As shown, traditional pulsed high-current power supplies typically rely on pulse capacitors as the form of pulsed power storage. The pulse capacitors discharge through thyristors or IGBTs to the load circuit, achieving high-current peak pulse output. This structure is simple and easy to implement. However, it suffers from problems such as pulse width being greatly affected by the load, large current turn-off losses and energy oscillations, and a low upper limit to the switching frequency, making it impossible to achieve highly reliable, efficient, and high-frequency pulsed high-current output. Furthermore, the pulsed current flows directly through the semiconductor device, causing extreme current stress and limiting scalability. Therefore, current pulsed high-current power supplies struggle to meet the current pulse processing requirements of lightweight, high-strength alloys. Achieving highly reliable, efficient, and scalable high-frequency high-current pulses is a current technical challenge for high-current pulse converters. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a switched capacitor resonant high-current pulse power supply and its control method, so as to improve the efficiency, reliability and scalability of high-current pulse output.

[0005] To solve the above-mentioned technical problems, the present invention adopts the following technical method: a switched capacitor resonant high-current pulse power supply, including a DC input source, an inverter circuit, a resonant cavity, and a transformer. The DC input source is connected to the DC terminal of the inverter circuit. The resonant cavity is connected in series with the primary winding of the transformer and then connected to the AC terminal of the inverter circuit. The secondary winding of the transformer is used to connect the load. The transformer is a step-down transformer.

[0006] Preferably, the resonant cavity includes a resonant inductor, a resonant capacitor, and a back-to-back switch assembly that controls the resonant capacitor to connect to a forward or reverse path. The back-to-back switch assembly is composed of a switching transistor and a diode connected in series.

[0007] Alternatively, the resonant cavity may include a resonant inductor, a resonant capacitor, and a back-to-back switch assembly that controls the connection of the resonant capacitor to the forward or reverse path, wherein the back-to-back switch assembly is composed of two switching transistors connected back-to-back.

[0008] Preferably, the switching transistor in the back-to-back switching assembly is an IGBT or a MOSFET.

[0009] In another aspect of the present invention, a control method for a switched-capacitor resonant high-current pulse power supply is provided. The inverter circuit outputs a positive square wave, and the switching transistor in the resonant cavity has the same switching frequency as the inverter circuit. The conduction time of the switching transistor in the resonant cavity is greater than or equal to twice the pulse width of the inverter circuit. When the switched-capacitor resonant high-current pulse power supply needs to output a high current with a fixed pulse width, the pulse width of the inverter circuit output voltage is made greater than half the resonant period of the resonant inductor and capacitor. When the switched-capacitor resonant high-current pulse power supply needs to output a high current with an adjustable pulse width, the pulse width of the inverter circuit output voltage is made less than half the resonant period of the resonant inductor and capacitor. The output current pulse width is adjusted by changing the pulse width of the inverter circuit.

[0010] Preferably, the expression for the resonant period of the resonant inductor and resonant capacitor is as follows:

[0011] (1)

[0012] In the formula, The resonant frequency; The resonant period; and These are the number of turns in the primary and secondary windings of the transformer, respectively. It is a resonant inductor; For load inductance; It is a resonant capacitor.

[0013] Preferably, the transformer outputs a large current pulse on the secondary side. Within one cycle, a set of back-to-back switching components of the resonant cavity are turned on. The resonant capacitor is connected to the power circuit through the diode in the turned-on back-to-back switching component. The resonant inductor and the resonant capacitor resonate to form a sinusoidal resonant current. This resonant current forms a large current pulse through the load circuit on the secondary side of the transformer. When the resonant current reaches zero, the diode is naturally turned off, and the resonant current remains at zero until the next cycle begins.

[0014] (2)

[0015] In the formula, The load current represents the large current pulse formed in the load circuit on the secondary side of the transformer. The inverter circuit output current is the resonant current. This is the primary excitation current of the transformer.

[0016] The switched-capacitor resonant high-current pulse power supply provided by this invention introduces a transformer to transfer high-current stress from semiconductor devices to metal conductors, improving the reliability of the device. A resonant cavity is introduced into the pulse circuit to allow the resonant current to naturally cross zero, reducing current stress on the semiconductor devices, turn-off losses, and energy oscillation amplitude, while also reducing the impact of load impedance on pulse width. The control method of the switched-capacitor resonant high-current pulse power supply provided by this invention, through the design of the parameters of the resonant cavity and transformer, reduces the current stress and turn-off current of the semiconductor devices in the pulse converter, achieving highly reliable and efficient sinusoidal unipolar high-current pulse output. Furthermore, this invention reduces the current stress on the semiconductor devices and can increase the upper limit of the output current amplitude by changing the transformer's turns ratio, expanding its application range. Attached Figure Description

[0017] Figure 1 This is the schematic diagram of the first type of traditional pulsed high-current power supply;

[0018] Figure 2 This is a schematic diagram of the traditional second type of pulsed high-current power supply;

[0019] Figure 3 This is a schematic diagram of the switched capacitor resonant high-current pulse power supply involved in this invention.

[0020] Figure 4 The waveform diagram of the switched capacitor resonant high-current pulse power supply in the embodiment of the present invention is shown (where (a) is the pulse width of the output voltage of the inverter circuit). Greater than the resonance period (a) Waveform at half; (b) Waveform when the inverter circuit output voltage pulse width is half. Less than the resonance period (Waveform at half the time). Detailed Implementation

[0021] To facilitate understanding by those skilled in the art, the present invention will be further described below with reference to embodiments and accompanying drawings. The content mentioned in the embodiments is not intended to limit the present invention.

[0022] like Figure 3 As shown, the switched capacitor resonant high-current pulse power supply provided by the present invention includes a DC input source (DC), an inverter circuit, a resonant cavity, and a transformer.

[0023] like Figure 3 As shown, the inverter circuit in this invention includes a DC bus capacitor. IGBT switching transistor - ,diode - , and Connected to form a bridge arm, and The two bridge arms are connected in parallel to form another bridge arm, and the DC bus capacitor is connected in series. Connected in parallel to one side of the two bridge arms, and led out from the midpoint of the two bridge arms as the output terminal of the inverter circuit, the output voltage of the inverter circuit is... The output current is .

[0024] like Figure 3 As shown, the resonant cavity in this invention includes a resonant inductor. Resonant capacitor IGBT switching transistor - ,diode - An IGBT switch and a diode connected in series form a back-to-back switching assembly. Specifically, and Series, and Series, and Series, and Each component is connected in series to form a back-to-back switch assembly. Two back-to-back switch assemblies connected in series form one bridge arm, and two more back-to-back switch assemblies connected in series form another bridge arm. The two bridge arms are connected in parallel, and the resonant capacitor... The resonant capacitor is connected in parallel on one side of the two bridge arms. The voltage across the two ends is The output terminal of the resonant cavity is drawn from the midpoint of the two bridge arms, and the resonant inductor is... Then it is connected to the output terminal. This invention controls the resonant capacitor by controlling the on / off state of four back-to-back switching assemblies in the resonant cavity. Connect forward or reverse paths.

[0025] like Figure 3 As shown, the transformer is a step-down transformer, and the primary winding of the transformer is... The secondary winding is The primary magnetizing inductance is... .

[0026] DC input source DC and DC bus capacitor of inverter circuit Connected in parallel, the voltage of the input DC source is Starting from the midpoint of one bridge arm of the resonant cavity, first connect the resonant inductor. Then connect the primary winding of the transformer to the midpoint of one bridge arm of the inverter circuit. Take a lead from the midpoint of the other bridge arm of the resonant cavity and connect it to the midpoint of the other bridge arm of the inverter circuit. The secondary winding of the transformer is connected to the load, which is equivalent to a resistor. With inductance Series connection, load current is Considering the heating scenarios for metal materials, the following settings are made: , .

[0027] Under the aforementioned connection method, the control method of the switched capacitor resonant high-current pulse power supply can convert the input DC power into a single maximum current pulse power. The core of this control method is that the inverter circuit outputs a positive voltage square wave, the IGBT switching transistor of the switched resonant capacitor has the same switching frequency as the inverter circuit, and the conduction time of the IGBT switching transistor of the switched resonant capacitor is greater than or equal to twice the pulse width of the inverter circuit. When the switched capacitor resonant high-current pulse power supply needs to output a large current with a fixed pulse width, the pulse width of the inverter circuit output voltage is made greater than half of the resonant period of the resonant inductor and resonant capacitor. When the switched capacitor resonant high-current pulse power supply needs to output a large current with an adjustable pulse width, the pulse width of the inverter circuit output voltage is made less than half of the resonant period of the resonant inductor and resonant capacitor. The output current pulse width is adjusted by changing the pulse width of the inverter circuit.

[0028] The typical operating waveform of the switched capacitor resonant high-current pulse power supply provided by this invention is as follows: Figure 4 As shown. Figure 4 (a) is the pulse width of the output voltage of the inverter circuit. Greater than the resonance period The waveform at half the pulse width corresponds to the operating condition where a large current with a fixed pulse width needs to be output. Figure 4 (b) is the pulse width of the output voltage of the inverter circuit. Less than the resonance period The waveform at half the current corresponds to the operating condition where a large current with adjustable pulse width is required.

[0029] exist Figure 4 In (a), the inverter circuit and and the resonant cavity and exist Available at all times, at this time. voltage For its peak The voltages of the resonant inductor and the primary winding of the transformer change from zero to... and .exist During the time period, , and Resonance occurs, in which through , , and Participating in resonance, voltage Descending to Inverter circuit output current exist The resonance reaches zero at any moment. During the time period, diode and Due to the reverse voltage, the current cannot flow in the reverse direction, and the resonant cavity current remains zero. Subsequently, and exist Always off, and and exist Always turn off. time, , , and When switched on, the voltages of the resonant inductor and the primary winding of the transformer change from zero to... and .at this time, through , , and Participating in resonance, voltage Increase. Subsequent waveforms and The timing is similar, so I won't go into details.

[0030] exist Figure 4 In (b), the inverter circuit and and the resonant cavity and exist Available at all times, at this time. voltage For its peak The voltages of the resonant inductor and the primary winding of the transformer change from zero to... and .exist During the time period, , and Resonance occurs, in which through , , and Participating in resonance, voltage Descending to The switching transistors of the inverter circuit are at the resonant current. It was turned off before it reached zero resonance (i.e.) (moment), at this time The current will flow through the diode and Flowing into the power supply terminal, Rapidly descending, and When the time reaches zero, the diode and Due to the reverse voltage, the resonant cavity current remains zero, and then... and exist Always turn off. time, , , and When switched on, the voltages of the resonant inductor and the primary winding of the transformer change from zero to... and .at this time, through , , and Participating in resonance, voltage Increase. Subsequent waveforms and The timing is similar, so I won't go into details.

[0031] Regardless of the operating condition described above, when the transformer secondary outputs a large current pulse, within one cycle, a set of IGBT switches in the resonant cavity are turned on. The resonant capacitor is connected to the power circuit through the diode corresponding to the turned-on IGBT switch. The resonant inductor and the resonant capacitor resonate, forming a sinusoidal resonant current. This resonant current forms a large current pulse through the load circuit on the secondary side of the transformer. When the resonant current reaches zero, the aforementioned diodes naturally turn off, and the resonant current remains zero until the start of the next cycle.

[0032] Resonant inductor Load inductance With resonant capacitor When resonance occurs, the resonant frequency is... With resonant period As shown in equation (1):

[0033] (1)

[0034] And resonant inductor Load inductance With resonant capacitor During the resonance process, the load current As shown in equation (2):

[0035] (2)

[0036] In the formula, The load current represents the large current pulse formed in the load circuit on the secondary side of the transformer. The inverter circuit output current is the resonant current. This is the primary excitation current of the transformer.

[0037] From the above two working conditions, it can be seen that: (1) When hour, The pulse width is determined by the resonant frequency, at which point all the switching transistors achieve zero-voltage turn-on and zero-current turn-off; (2) when hour, The pulse width is affected by the switching frequency, thus enabling pulse width adjustment. During this process, the switching transistors of the inverter circuit achieve zero-current turn-on, and the turn-off current is less than or equal to the peak current. All back-to-back switching components controlling the resonant capacitor connection path achieve zero-current turn-off. (3) Under both operating conditions, the participation of the resonant capacitor increases the equivalent discharge voltage amplitude, eliminating the occurrence of transformer core bias excitation. (4) Under both operating conditions, the load current exhibits a sinusoidal pattern, and the peak current in the semiconductor device is equal to the peak current in the resonant cavity. All are less than the peak load current. .

[0038] In summary, the switched-capacitor resonant high-current pulse power supply provided by this invention can achieve high-efficiency, low-device-stress high-frequency single-maximum-current pulse output. All switching devices can achieve soft switching, and by using a transformer, the current stress on the semiconductor devices is reduced, which can improve the reliability and efficiency of the converter. At the same time, compared with traditional thyristor-based high-current pulse converters, this circuit uses fully controlled devices to achieve high-frequency pulse output.

[0039] The above embodiments are preferred implementations of the present invention. In addition, the present invention can be implemented in other ways. Any obvious substitutions without departing from the concept of the present technical solution are within the protection scope of the present invention.

[0040] To facilitate understanding by those skilled in the art of the improvements of this invention over the prior art, some of the accompanying drawings and descriptions have been simplified, and for clarity, some other elements have been omitted from this application. Those skilled in the art should realize that these omitted elements may also constitute the content of this invention.

Claims

1. A control method for a switched-capacitor resonant high-current pulse power supply, characterized in that: The switched capacitor resonant high-current pulse power supply includes a DC input source, an inverter circuit, a resonant cavity, and a transformer. The DC input source is connected to the DC terminal of the inverter circuit. The resonant cavity is connected in series with the primary winding of the transformer and then connected to the AC terminal of the inverter circuit. The secondary winding of the transformer is used to connect the load. The transformer is a step-down transformer. The resonant cavity includes a resonant inductor, a resonant capacitor, and a back-to-back switch assembly that controls the connection of the resonant capacitor to the forward or reverse path. The back-to-back switch assembly is composed of a switching transistor and a diode connected in series or two switching transistors connected back-to-back. The switching transistor in the back-to-back switch assembly is an IGBT or a MOSFET. The inverter circuit outputs a positive square wave. The switching transistor in the resonant cavity has the same switching frequency as the inverter circuit, and the conduction time of the switching transistor in the resonant cavity is greater than or equal to twice the pulse width of the inverter circuit. When the switched capacitor resonant high-current pulse power supply needs to output a large current with a fixed pulse width, the pulse width of the inverter circuit output voltage is made greater than half of the resonant period of the resonant inductor and resonant capacitor. When the switched capacitor resonant high-current pulse power supply needs to output a large current with an adjustable pulse width, the pulse width of the inverter circuit output voltage is made less than half of the resonant period of the resonant inductor and resonant capacitor. The output current pulse width is adjusted by changing the pulse width of the inverter circuit.

2. The control method for a switched-capacitor resonant high-current pulse power supply according to claim 1, characterized in that: The expression for the resonant period of the resonant inductor and resonant capacitor is as follows: （1） In the formula, The resonant frequency; The resonant period; and These are the number of turns in the primary and secondary windings of the transformer, respectively. It is a resonant inductor; For load inductance; It is a resonant capacitor.

3. The control method for a switched-capacitor resonant high-current pulse power supply according to claim 2, characterized in that: The transformer outputs a large current pulse on its secondary side. Within one cycle, a set of back-to-back switching components in the resonant cavity are turned on. The resonant capacitor is connected to the power circuit through the diode in the turned-on back-to-back switching component. The resonant inductor and the resonant capacitor resonate, forming a sinusoidal resonant current. This resonant current forms a large current pulse in the load circuit on the secondary side of the transformer. When the resonant current reaches zero, the diode naturally turns off, and the resonant current remains zero until the start of the next cycle. （2） In the formula, The load current represents the large current pulse formed in the load circuit on the secondary side of the transformer. The inverter circuit output current is the resonant current. This is the primary excitation current of the transformer.

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