Power supply circuit and maglev train

Abstract

The application discloses a power supply circuit and a maglev train, and relates to the field of maglev trains, which comprises a power supply, an energy storage capacitor, a current limiting module, a charging control switch, a power supply control switch and a switch control module. After receiving an energy storage signal, the switch control module controls the charging control switch to be closed, so that the power supply charges the energy storage capacitor through the current limiting module. Since the current limiting module exists, the current impact on the power supply caused by the short circuit of the energy storage capacitor during the charging of the power supply is reduced. Moreover, the switch control module controls the power supply control switch to be closed only after the charging control switch is closed for a preset time length. Since the preset time length is not less than the time required for the energy storage capacitor to be fully charged, the impact of the power supply caused by the power-on of the energy storage capacitor can be avoided, so that the safety and reliability of the power supply circuit and the maglev train are ensured.

Description

Technical Field

[0001] This invention relates to the field of magnetic levitation trains, and in particular to a power supply circuit and a magnetic levitation train. Background Technology

[0002] In maglev trains, a power supply circuit is needed to power the equipment. Current technology typically includes a power supply and an energy storage capacitor. The power supply charges the energy storage capacitor so that it can store electrical energy and power the equipment. However, due to the inherent characteristics of the energy storage capacitor, it is essentially short-circuited the instant the power supply powers it. This causes a significant current surge to the power supply, potentially damaging it and affecting the normal operation of the maglev train. Summary of the Invention

[0003] The purpose of this invention is to provide a power supply circuit and a magnetic levitation train that can ensure the safety and reliability of the power supply circuit and the magnetic levitation train.

[0004] To solve the above-mentioned technical problems, the present invention provides a power supply circuit, including a power supply, an energy storage capacitor, a current limiting module, a charging control switch, a power supply control switch, and a switch control module;

[0005] The positive output terminal of the power supply is connected to one end of the charging control switch, and the other end of the charging control switch is connected to one end of the power supply control switch. The energy storage capacitor is disposed between the other end of the power supply control switch and the negative output terminal of the power supply. The current limiting module is disposed between the charging control switch and the energy storage capacitor. The current limiting module is used to limit the current in the circuit between the output terminal of the power supply and the energy storage capacitor.

[0006] The switch control module is used to control the charging control switch to close after receiving the energy storage signal, and to control the power supply control switch to close after the charging control switch has been closed for a preset time. The preset time is not less than the time required for the energy storage capacitor to be fully charged.

[0007] On the other hand, the energy storage capacitor includes a plurality of energy storage sub-capacitors connected in series.

[0008] On the other hand, it also includes a balancing circuit for balancing the voltage across each of the energy storage sub-capacitors.

[0009] On the other hand, the equalization circuit includes equalization resistors corresponding one-to-one with each of the energy storage sub-capacitors, each of the equalization resistors being connected in parallel across each of the energy storage sub-capacitors, and the resistance values ​​of each of the equalization resistors being equal.

[0010] On the other hand, the current limiting module is a current limiting resistor.

[0011] On the other hand, it also includes a current monitoring module, which is used to monitor the current at the output terminal of the power supply within a preset time period after the switch control module closes the charging control switch, and generate a prompt message when the current is greater than a preset inrush current threshold.

[0012] On the other hand, the switch control module includes a first relay, a second relay, a third relay, a first controllable switch, a second controllable switch, and a processing module;

[0013] The charging control switch is the first normally open contact of the first relay, and the power supply control switch is the first normally open contact of the second relay;

[0014] The positive terminal of the coil of the first relay is connected to the power supply through the second normally open contact of the third coil, and the negative terminal of the coil of the first relay is grounded.

[0015] The positive terminal of the coil of the second relay is connected to the power supply, the negative terminal of the coil of the second relay is connected to the input terminal of the second controllable switch, and the output terminal of the second controllable switch is grounded.

[0016] The positive terminal of the coil of the third relay is connected to the power supply through the first normally open contact of the third relay, the second normally closed contact of the first relay is connected in parallel with the first normally open contact of the third relay, the negative terminal of the coil of the third relay is connected to the input terminal of the first controllable switch, and the output terminal of the first controllable switch is grounded.

[0017] The processing module is used to input the energy storage signal to the control terminal of the first controllable switch and input a delayed enable signal to the control terminal of the second controllable switch, wherein the time when the delayed enable signal is input to the second controllable switch is later than the time when the energy storage signal is input to the first controllable switch by a preset time.

[0018] On the other hand, the switch control module also includes a second normally closed contact of a second relay;

[0019] The second normally closed contact of the second relay is connected in series with the second normally closed contact of the first relay, and the circuit after series connection is connected in parallel with the first normally open contact of the third relay.

[0020] On the other hand, both the first controllable switch and the second controllable switch are NMOS.

[0021] To solve the above-mentioned technical problems, this application also provides a magnetic levitation train, including any of the above-mentioned power supply circuits.

[0022] In summary, this invention discloses a power supply circuit and a maglev train, including a power supply, an energy storage capacitor, a current limiting module, a charging control switch, a power supply control switch, and a switch control module. Upon receiving an energy storage signal, the switch control module controls the charging control switch to close, allowing the power supply to charge the energy storage capacitor through the current limiting module. The presence of the current limiting module reduces the current surge to the power supply caused by a short circuit in the energy storage capacitor during charging. Furthermore, the switch control module controls the power supply control switch to close only after a preset time has elapsed since the charging control switch has closed. Because this preset time is not less than the time required for the energy storage capacitor to fully charge, the surge to the power supply caused by the energy storage capacitor's instantaneous power-on is avoided, thus ensuring the safety and reliability of the power supply circuit and the maglev train. Attached Figure Description

[0023] To more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings used in the prior art and embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0024] Figure 1 A circuit diagram of a power supply circuit provided for this invention;

[0025] Figure 2 A circuit diagram of a switch control module in a power supply circuit provided by the present invention. Detailed Implementation

[0026] The core of this invention is to provide a power supply circuit and a magnetic levitation train that can ensure the safety and reliability of the power supply circuit and the magnetic levitation train.

[0027] 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.

[0028] Please refer to Figure 1 , Figure 1 The present invention provides a circuit diagram of a power supply circuit, which includes a power supply 1, an energy storage capacitor 2, a current limiting module 3, a charging control switch 4, a power supply control switch 5, and a switch control module;

[0029] The positive output terminal of the power supply 1 is connected to one end of the charging control switch 4, and the other end of the charging control switch 4 is connected to one end of the power supply control switch 5. The energy storage capacitor 2 is located between the other end of the power supply control switch 5 and the negative output terminal of the power supply 1. The current limiting module 3 is located between the charging control switch 4 and the energy storage capacitor 2. The current limiting module 3 is used to limit the current in the circuit between the output terminal of the power supply 1 and the energy storage capacitor 2.

[0030] The switch control module is used to control the charging control switch 4 to close after receiving the energy storage signal, and to control the power supply control switch 5 to close after the charging control switch 4 has been closed for a preset time. The preset time is not less than the time required for the energy storage capacitor 2 to be fully charged.

[0031] To address the problem in the prior art where the energy storage capacitor 2 experiences a short circuit due to its inherent characteristics when the power supply 1 supplies power to the energy storage capacitor 2, thus causing a current surge to the power supply 1, this application provides a power supply circuit. In addition to the power supply 1 and the energy storage capacitor 2, the power supply circuit also includes a switch control module, a charging control switch 4, a power supply control switch 5, and a current limiting module 3. On one hand, the current limiting module 3 limits the current in the circuit between the power supply 1 and the energy storage capacitor 2, thereby reducing the surge current of the energy storage capacitor 2. On the other hand, it ensures that the energy storage capacitor 2 is fully charged before short-circuiting the current limiting module 3 and allowing the energy storage capacitor 2 to supply power to the equipment in the maglev train, further ensuring that the power supply 1 is not affected by the surge current.

[0032] Specifically, when the switch control module receives the energy storage signal, it closes the charging control switch 4. At this time, the power supply 1 charges the energy storage capacitor 2. The actual working path of the power supply circuit at this time is: power supply 1 - charging control switch 4 - current limiting module 3 - energy storage capacitor 2. Therefore, the current limiting module 3 can limit the magnitude of the current flowing through the actual working path of the power supply circuit. The inrush current brought by the energy storage capacitor 2 at the moment when the power supply 1 powers on the energy storage capacitor 2 is also affected by the current limiting module 3, thereby reducing or avoiding the impact of the inrush current on the power supply 1. In addition, the current limiting module 3 can be a current limiting resistor R1, etc. The resistance value of the current limiting resistor is not particularly limited in this application and can be selected according to the actual situation.

[0033] After the energy storage capacitor 2 is fully charged, the possibility of the power supply 1 being affected by the inrush current is reduced. Therefore, in this application, the switch control module controls the power supply control switch 5 to close after a preset time period following the closing of the charging control switch 4. The preset time period is greater than or equal to the time it takes for the energy storage capacitor 2 to fully charge. The preset time period can be determined experimentally before the actual application of the charging circuit, and this application does not limit its specific value. When the switch control module controls the power supply control switch 5 to close, the energy storage capacitor 2 is fully charged and supplies power to other equipment in the maglev train. At this time, the actual working path of the power supply circuit is: power supply 1 - charging control switch 4 - power supply control switch 5 - energy storage capacitor 2. Although the current limiting module 3 no longer plays a current limiting role at this time, since the power supply control switch 5 is turned on only after the energy storage capacitor 2 is fully charged, the impact of the inrush current from the energy storage capacitor 2 on the power supply 1 can still be avoided during this stage, thus ensuring the safety and reliability of the power supply circuit and the maglev train.

[0034] In summary, this invention discloses a power supply circuit, including a power supply 1, an energy storage capacitor 2, a current limiting module 3, a charging control switch 4, a power supply control switch 5, and a switch control module. Upon receiving an energy storage signal, the switch control module controls the charging control switch 4 to close, allowing the power supply 1 to charge the energy storage capacitor 2 through the current limiting module 3. The presence of the current limiting module 3 reduces the current surge to the power supply 1 caused by a short circuit in the energy storage capacitor 2 during charging. Furthermore, the switch control module controls the power supply control switch 5 to close only after a preset time has elapsed since the charging control switch 4 has closed. Because this preset time is not less than the time required for the energy storage capacitor 2 to fully charge, the surge to the power supply 1 caused by the instant the energy storage capacitor 2 is powered on can be avoided, thus ensuring the safety and reliability of the power supply circuit and the maglev train.

[0035] Based on the above embodiments:

[0036] In some embodiments, the energy storage capacitor 2 includes a plurality of energy storage sub-capacitors connected in series.

[0037] Considering that the capacity of the energy storage capacitor 2 is crucial to the performance of the charging circuit, and that large-capacity capacitors are typically bulky and expensive, this embodiment utilizes multiple energy storage sub-capacitors connected in series as the energy storage capacitor 2 in order to reduce the size and cost of the charging circuit while ensuring its charging performance. Please refer to... Figure 1 , Figure 1 A circuit diagram of a power supply circuit provided by the present invention. Figure 1C1 and C2 are energy storage sub-capacitors. Specifically, multiple energy storage sub-capacitors connected in series can meet higher capacitance requirements, thus reducing the capacitance requirement of each individual sub-capacitor and consequently reducing the size and cost of the charging circuit. Furthermore, the multiple energy storage sub-capacitors connected in series, serving as energy storage capacitor 2, can also improve the stability of the charging circuit and reduce voltage fluctuations.

[0038] In some embodiments, an equalization circuit is also included for balancing the voltage across each energy storage sub-capacitor.

[0039] In this embodiment, since the energy storage capacitor 2 is specifically composed of multiple energy storage sub-capacitors connected in series, in order to improve the stability of the charging circuit and avoid the situation where some energy storage sub-capacitors are prematurely fully charged or even exceed the specified voltage, while others are not fully charged, an additional balancing circuit is provided in the charging circuit to balance the voltage across each energy storage sub-capacitor. Please refer to... Figure 1 , Figure 1 A circuit diagram of a power supply circuit provided by the present invention. Figure 1 R2 and R3 are energy storage sub-capacitors. Specifically, the balancing circuit can include balancing resistors connected in parallel across each energy storage sub-capacitor. Each balancing resistor corresponds one-to-one with an energy storage sub-capacitor, and the resistance value of each balancing resistor is equal. Since the resistance value of each balancing resistor is equal, the voltage across each energy storage sub-capacitor is also equal, which not only achieves voltage balancing of the energy storage sub-capacitors but also has the advantages of simple circuit structure and low cost.

[0040] In some embodiments, the system further includes a current monitoring module, which monitors the current at the output terminal of the power supply 1 within a preset time period after the switch control module closes the charging control switch 4, and generates a prompt message when the current exceeds a preset inrush current threshold.

[0041] To further ensure the safety and reliability of the power supply circuit and the maglev train, a current monitoring module is also included in this embodiment. Considering that the current surge from the energy storage capacitor 2 to the power supply 1 mainly occurs during the initial charging period, the current monitoring module monitors the output current of the power supply 1 for a preset time after the switching control module closes the charging control switch 4 (i.e., during the period when the energy storage capacitor 2 is not fully charged). When the output current of the power supply 1 exceeds a preset surge current threshold, a warning message is generated. This embodiment further adds a current monitoring module to the current limiting module 3's protection against surge current to the power supply 1. When the current monitoring module issues a warning message, maintenance personnel can promptly check the status of the power supply circuit, ensuring its safety.

[0042] This application does not impose any special restrictions on the value of the preset inrush current threshold. It can be set according to the actual situation. For example, when the safety requirements of the power supply circuit are high, the preset inrush current threshold can be set to a smaller value.

[0043] In some embodiments, the switch control module includes a first relay, a second relay, a third relay, a first controllable switch, a second controllable switch, and a processing module;

[0044] The charging control switch 4 is the first normally open contact of the first relay, and the power supply control switch 5 is the first normally open contact of the second relay.

[0045] The positive terminal of the coil of the first relay is connected to the power supply through the second normally open contact of the third coil, and the negative terminal of the coil of the first relay is grounded.

[0046] The positive terminal of the coil of the second relay is connected to the power supply, the negative terminal of the coil of the second relay is connected to the input terminal of the second controllable switch, and the output terminal of the second controllable switch is grounded.

[0047] The positive terminal of the coil of the third relay is connected to the power supply through the first normally open contact of the third relay. The second normally closed contact of the first relay is connected in parallel with the first normally open contact of the third relay. The negative terminal of the coil of the third relay is connected to the input terminal of the first controllable switch. The output terminal of the first controllable switch is grounded.

[0048] The processing module is used to input an energy storage signal to the control terminal of the first controllable switch and a delayed enable signal to the control terminal of the second controllable switch, wherein the time when the delayed enable signal is input to the second controllable switch is later than the time when the energy storage signal is input to the first controllable switch by a preset time.

[0049] Please refer to Figure 1 , Figure 1 A circuit diagram of a power supply circuit provided by the present invention. Figure 1 In the diagram, K1_1 is the first normally open contact of the first relay, and K2_1 is the first normally open contact of the second relay. Please refer to [reference needed]. Figure 2 , Figure 2 A circuit diagram of a switch control module in a power supply circuit provided by the present invention. Figure 2In this embodiment, K1, K2, and K3 are the first, second, and third relays, respectively. K1_2 is the second normally closed contact of the first relay, K2_2 is the first normally closed contact of the second relay, and K3_2 is the second normally open contact of the third relay. EN_K1-K3 are energy storage signals, and EN_K2 is a delayed enable signal. In this embodiment, the switch control module includes the first relay, the second relay, the third relay, the first controllable switch, the second controllable switch, and a processing module. The first normally open contact of the first relay serves as the charging control switch 4, and the first normally open contact of the second relay serves as the power supply control switch 5. The working process of the switch control module is described below:

[0050] First, the processing module inputs an energy storage signal to the control terminal of the first controllable switch, causing the first controllable switch to conduct. Since the coil of the first relay is not energized at this time, the second normally closed contact of the first coil remains closed. After the first controllable switch conducts, the coil of the third relay is energized. The energization of the third relay coil causes the second normally open contact of the third relay, connected to the positive terminal of the first relay coil, to close, thereby energizing the coil of the first relay. Therefore, the first normally open contact of the first relay, i.e., the charging control switch 4, is activated. Since the coil of the second relay is not energized at this time, the first normally open contact of the second relay, i.e., the power supply control switch 5, is deactivated. In summary, the actual working path of the power supply circuit at this time is: power supply 1 - charging control switch 4 - current limiting module 3 - energy storage capacitor 2. The presence of the current limiting module 3 reduces the possibility of the charging power supply being affected by the inrush current of the energy storage capacitor 2.

[0051] After the processing module outputs an energy storage signal to the control terminal of the first controllable switch and waits for a preset time, it outputs a delayed enable signal to the control terminal of the second controllable switch, causing the second controllable switch to conduct. This energizes the coil of the second relay, causing the first normally open contact of the second relay, i.e., the power supply control switch 5, to conduct. At this time, both the charging control switch 4 and the power supply control switch 5 are conducting. The actual operating path of the power supply circuit is: power supply 1 - charging control switch 4 - power supply control switch 5 - energy storage capacitor 2. Because the power supply control switch 5 conducts after the energy storage capacitor 2 is fully charged, it avoids the impact on the power supply 1 caused by the instantaneous power-on of the energy storage capacitor 2.

[0052] It should also be noted that, Figure 2 The first and second controllable switches are both NMOS. The drain of the NMOS serves as the input terminal of the controllable switch, the gate of the NMOS serves as the control terminal of the controllable switch, and the source of the NMOS serves as the output terminal of the controllable switch.

[0053] In summary, this embodiment uses three relays, two controllable switches, and a current limiting module 3 to charge the energy storage capacitor 2 and power the subsequent circuits by controlling the two controllable switches in a time-sharing manner. The charging and discharging of the energy storage capacitor 2 is controlled by relays through a hardware circuit, which has high reliability.

[0054] In some embodiments, the switch control module further includes a second normally closed contact of a second relay;

[0055] The second normally closed contact of the second relay is connected in series with the second normally closed contact of the first relay, and the circuit after series connection is connected in parallel with the first normally open contact of the third relay.

[0056] To further improve the reliability of the power supply circuit, the switch control module in this embodiment also includes a second normally closed contact of a second relay. Please refer to... Figure 2 , Figure 2 The circuit diagram provided by this invention relates to a switch control module in a power supply circuit. The circuit formed by connecting the second normally closed contact of the second relay in series with the second normally closed contact of the first relay is then connected in parallel with the first normally open contact of the third relay. By adding the second normally closed contact of the second relay, the situation where the power supply 1 is burned out due to malfunction of the energy storage signal before the delayed enable signal controls the second controllable switch to close and thus causes the second coil to be energized can be avoided.

[0057] After the processing module outputs an energy storage signal to the control terminal of the first controllable switch, the first controllable switch closes, and the second normally closed contacts of both the first and second relays close, energizing the coil of the third relay. The energization of the third relay's coil causes its second normally open contact to close, thus energizing the coil of the first relay. At this time, the first normally open contact of the first relay, i.e., the charging control switch 4, closes. The actual operating path of the power supply circuit is: power supply 1 - charging control switch 4 - current limiting module 3 - energy storage capacitor 2. The presence of the current limiting module 3 reduces the possibility of the charging power supply being affected by the inrush current of the energy storage capacitor 2.

[0058] After the processing module outputs an energy storage signal to the control terminal of the first controllable switch and waits for a preset time, it outputs a delayed enable signal to the control terminal of the second controllable switch, causing the second controllable switch to conduct. Therefore, the coil of the second relay is energized, the second normally closed contact of the second relay opens, and the first normally open contact of the second relay closes. The actual working path of the power supply circuit is: power supply 1 - charging control switch 4 - power supply control switch 5 - energy storage capacitor 2. Since the power supply control switch 5 conducts after the energy storage capacitor 2 is fully charged, it avoids the impact on the power supply 1 caused by the instant the energy storage capacitor 2 is powered on.

[0059] This application also provides a magnetic levitation train, including any of the power supply circuits described above.

[0060] For a detailed description of the maglev train provided in this application, please refer to the above-described embodiment of the power supply circuit; further details will not be repeated here.

[0061] The various embodiments described in this specification are presented in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. It should also be noted that in this specification, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0062] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A power supply circuit, characterized in that, It includes a power supply, energy storage capacitor, current limiting module, charging control switch, power supply control switch, and switch control module; The positive output terminal of the power supply is connected to one end of the charging control switch, and the other end of the charging control switch is connected to one end of the power supply control switch. The energy storage capacitor is disposed between the other end of the power supply control switch and the negative output terminal of the power supply. The current limiting module is disposed between the charging control switch and the energy storage capacitor. The current limiting module is used to limit the current in the circuit between the output terminal of the power supply and the energy storage capacitor. The switch control module is used to control the charging control switch to close after receiving the energy storage signal, and to control the power supply control switch to close after the charging control switch has been closed for a preset time. The preset time is not less than the time required for the energy storage capacitor to be fully charged. The switch control module includes a first relay, a second relay, a third relay, a first controllable switch, a second controllable switch, and a processing module; The charging control switch is the first normally open contact of the first relay, and the power supply control switch is the first normally open contact of the second relay; The positive terminal of the coil of the first relay is connected to the power supply through the second normally open contact of the third relay, and the negative terminal of the coil of the first relay is grounded. The positive terminal of the coil of the second relay is connected to the power supply, the negative terminal of the coil of the second relay is connected to the input terminal of the second controllable switch, and the output terminal of the second controllable switch is grounded. The positive terminal of the coil of the third relay is connected to the power supply through the first normally open contact of the third relay, the second normally closed contact of the first relay is connected in parallel with the first normally open contact of the third relay, the negative terminal of the coil of the third relay is connected to the input terminal of the first controllable switch, and the output terminal of the first controllable switch is grounded. The processing module is used to input the energy storage signal to the control terminal of the first controllable switch and input a delayed enable signal to the control terminal of the second controllable switch, wherein the time when the delayed enable signal is input to the second controllable switch is later than the time when the energy storage signal is input to the first controllable switch by a preset time.

2. The power supply circuit as described in claim 1, characterized in that, The energy storage capacitor includes multiple energy storage sub-capacitors connected in series.

3. The power supply circuit as described in claim 2, characterized in that, It also includes a balancing circuit for balancing the voltage across each of the energy storage sub-capacitors.

4. The power supply circuit as described in claim 3, characterized in that, The equalization circuit includes equalization resistors corresponding to each of the energy storage sub-capacitors. Each equalization resistor is connected in parallel across the two ends of each of the energy storage sub-capacitors, and the resistance values ​​of each equalization resistor are equal.

5. The power supply circuit as described in claim 1, characterized in that, The current limiting module is a current limiting resistor.

6. The power supply circuit as described in claim 1, characterized in that, Also includes: The current monitoring module is used to monitor the current at the output terminal of the power supply within a preset time period after the switch control module closes the charging control switch, and generate a prompt message when the current exceeds a preset inrush current threshold.

7. The power supply circuit according to claim 1, characterized in that, The switch control module also includes a second normally closed contact of a second relay; The second normally closed contact of the second relay is connected in series with the second normally closed contact of the first relay, and the circuit after series connection is connected in parallel with the first normally open contact of the third relay.

8. The power supply circuit as described in claim 1, characterized in that, Both the first controllable switch and the second controllable switch are NMOS.

9. A magnetic levitation train, characterized in that, Includes the power supply circuit as described in any one of claims 1 to 8.

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