Power converter and control method therefor, and electrical device and power supply system

Abstract

The embodiments of the present application relate to the technical field of power supply. Provided are a power converter and a control method therefor, and an electrical device and a power supply system. When safety discharge requirements are met, there is no need to distinguish a power-down state of an input end of the electrical device from a normal fluctuation state of an input voltage of the electrical device. In the power converter, a primary-side switching circuit inverts a received first direct-current voltage into a first alternating-current voltage, and a transformer circuit converts the first alternating-current voltage into a second alternating-current voltage. A secondary-side switching circuit is a full-bridge circuit or a full-wave circuit, wherein a first secondary-side transistor and a second secondary-side transistor in the secondary-side switching circuit are respectively used for rectifying the second alternating-current voltage into a second direct-current voltage. The first secondary-side transistor and the second secondary-side transistor are alternately turned on, such that when the power converter is powered down, the losses of the primary-side switching circuit and the secondary-side switching circuit themselves are used to reduce, within a short time, the voltage at the input end of the power converter to within a safe voltage range.

Description

A power converter and its control method, electrical equipment, and power supply system.

[0001] This application claims priority to Chinese Patent Application No. 202510344554.1, filed on March 21, 2025, entitled "A Power Converter and its Control Method, Electrical Equipment, and Power Supply System", the entire contents of which are incorporated herein by reference. Technical Field

[0002] This application relates to the field of power supply technology, and in particular to a power converter and its control method, electrical equipment, and power supply system. Background Technology

[0003] With the continuous development of power technology, the application of electrical equipment receiving high-voltage direct current (HVDC) is becoming increasingly widespread in various fields. To meet safety discharge requirements, when the input terminal of an electrical device loses power, the voltage at the input terminal needs to be discharged to a safe voltage range within a short period to ensure the safety of maintenance or operating personnel. However, the input voltage of electrical equipment has a certain normal fluctuation range. Accurately distinguishing between the power-off state of the equipment's input terminal and the normal fluctuation state of the input voltage requires additional circuit design, thus increasing costs. Summary of the Invention

[0004] This application provides a power converter and its control method, electrical equipment, and power supply system, which, under the condition of meeting safety discharge requirements, do not require distinguishing between the power-off state of the input terminal of the electrical equipment and the normal fluctuation state of the input voltage of the electrical equipment.

[0005] To achieve the above objectives, this application adopts the following technical solution:

[0006] One aspect of this application provides a power converter, which includes a primary-side switching circuit, a secondary-side switching circuit, and a transformer circuit. The primary-side switching circuit inverts a first DC voltage received at the input terminal of the power converter into a first AC voltage. The transformer circuit converts the first AC voltage into a second AC voltage and provides the second AC voltage to the secondary-side switching circuit. Furthermore, the primary-side switching circuit is a full-bridge circuit or a full-wave circuit. The secondary-side switching circuit includes a first secondary-side transistor and a second secondary-side transistor, which are electrically connected between the secondary winding of the transformer circuit and the output terminal of the power converter. The first and second secondary-side transistors respectively rectify the second AC voltage into a second DC voltage and provide it to the load through the output terminal of the power converter. The second DC voltage is different from the first DC voltage. The first and second secondary-side transistors are alternately turned on.

[0007] In summary, the power converter, through its primary-side switching circuit, secondary-side switching circuit, and transformer circuit, converts the received first DC voltage into a second DC voltage of a different voltage. Furthermore, the first and second secondary-side transistors in the secondary-side switching circuit alternately conduct, and the magnetic field generated by the current in the secondary winding of the transformer circuit induces an electromotive force in the primary winding of the transformer circuit, generating an induced current, which can be called the reverse current. This reverse current can flow through the primary circuit. Thus, current flows through both the primary and secondary switching circuits, resulting in losses in both. These losses include transistor switching losses and coil losses in the primary and secondary windings. Under these conditions, when the power converter's input is de-energized, the losses inherent in both the primary and secondary switching circuits contribute to the overall significant losses of the power converter. This allows the voltage at the power converter's input to be discharged from high voltage to a safe voltage range (e.g., ≤60V) within a short time, meeting safety discharge requirements. Furthermore, since the first and second secondary transistors in the secondary switching circuit are always in an alternating conduction state, there is no need to distinguish between the power-down state of the power converter and the normal fluctuation state of the power converter input voltage, which helps to reduce costs.

[0008] In one optional embodiment, the power converter's output terminals include a first output terminal and a second output terminal. The secondary-side switching circuit is a full-wave circuit, and the secondary-side winding of the transformer circuit includes a first secondary-side winding and a second secondary-side winding. A first secondary-side transistor and a first secondary-side winding are connected in series between the first and second output terminals. A second secondary-side transistor and a second secondary-side winding are connected in series between the first and second output terminals. In this case, the path formed by the first secondary-side transistor and the first secondary-side winding can rectify the positive half-axis electrical signal of the second AC voltage, and the path formed by the second secondary-side transistor and the second secondary-side winding can rectify the negative half-axis electrical signal of the second AC voltage. Alternatively, the path formed by the first secondary-side transistor and the first secondary-side winding can rectify the negative half-axis electrical signal of the second AC voltage, and the path formed by the second secondary-side transistor and the second secondary-side winding can rectify the positive half-axis electrical signal of the second AC voltage, thereby enabling the power converter to output the aforementioned second DC voltage.

[0009] In one optional embodiment, the power converter's output terminals include a first output terminal and a second output terminal. The secondary-side switching circuit is a full-bridge circuit, further comprising a third secondary-side transistor and a fourth secondary-side transistor. The first secondary-side transistor, the secondary-side winding, and the fourth secondary-side transistor are connected in series between the first and second output terminals. The third secondary-side transistor, the secondary-side winding, and the second secondary-side transistor are connected in series between the first and second output terminals. The first and second secondary-side transistors form a first bridge arm, and the third and fourth secondary-side transistors form a second bridge arm, with the third and fourth secondary-side transistors alternately conducting. In this configuration, the first bridge arm can rectify the positive half-axis electrical signal of the second AC voltage, and the second bridge arm can rectify the negative half-axis electrical signal of the second AC voltage. Alternatively, the first bridge arm can rectify the negative half-axis electrical signal of the second AC voltage, and the second bridge arm can rectify the positive half-axis electrical signal of the second AC voltage, thereby enabling the power converter to output the aforementioned second DC voltage.

[0010] In one optional embodiment, the power converter further includes a startup circuit and a reverse-current protection circuit. The reverse-current protection circuit is connected in parallel with the startup circuit. The startup circuit controls the connection between the input terminal of the power converter and the primary-side switching circuit to be open or closed. When the startup circuit controls the connection between the input terminal of the power converter and the primary-side switching circuit to be closed, the reverse-current protection circuit prevents current from the primary-side switching circuit from flowing back into the input terminal of the power converter. In this case, when the startup circuit is in the on state, the input terminal of the power converter can be connected to the primary-side switching circuit through the startup circuit, and at this time, the input terminal of the power converter can transmit to the primary-side switching circuit. When the startup circuit is in the off state, the input terminal of the power converter is disconnected from the primary-side switching circuit. At this time, no signal transmission can be made between the input terminal of the power converter and the primary-side switching circuit, and the power converter cannot perform voltage conversion. In addition, the reverse-current protection circuit is connected in parallel with the startup circuit, and the reverse-current protection circuit prevents current from the primary-side switching circuit from flowing back into the input terminal of the power converter. Therefore, when the startup circuit is turned on, its resistance can be less than that of the reverse protection circuit. Consequently, the current from the input of the power converter will not, or mostly will not, pass through the reverse protection circuit, but instead flows through the startup circuit to the primary-side switching circuit. This reduces the conduction losses of the reverse protection circuit, improving the efficiency of the power converter, as almost no current flows through it or only a very small current flows through it. Furthermore, because the conduction losses of the reverse protection circuit are low, there is no need for an additional heat sink to dissipate heat from it, thus improving the space utilization of the electrical equipment and achieving cost savings.

[0011] In one optional implementation, the reverse current protection circuit includes a first diode, the anode of which is electrically connected to the input terminal of the power converter, and the cathode of which is electrically connected to the primary-side switching circuit. This utilizes the unidirectional conduction capability of a single diode to achieve reverse current protection, thereby simplifying the circuit.

[0012] In one optional implementation, the reverse current protection circuit includes a first diode and a second diode connected in series. The anodes of the first and second diodes are electrically connected to the input terminal of the power converter. The cathodes of the first and second diodes are electrically connected to the primary-side switching circuit. This utilizes the unidirectional conduction property of the diodes to achieve reverse current protection. By using two diodes connected in series as the reverse current protection circuit, when one diode fails, the other diode can still achieve the same reverse current protection function.

[0013] In one optional embodiment, the reverse current protection circuit includes a first diode, a second diode, a third diode, and a fourth diode. The anodes of the first and third diodes are electrically connected to the second input terminal. The cathodes of the second and fourth diodes are electrically connected to the first input terminal. The cathodes of the first and second diodes are also electrically connected to the first input terminal. The cathodes of the third and fourth diodes are also electrically connected to the second input terminal. The first input terminal, the second diode, the bus capacitor, the third diode, and the second input terminal can form a current loop, allowing electrical energy from both input terminals to be transferred to the bus capacitor through this loop. Furthermore, the second input terminal, the fourth diode, the bus capacitor, and the first diode can also form a current loop, allowing electrical energy from both input terminals to be transferred to the bus capacitor through this loop. In this case, the unidirectional conductivity of the first, second, third, and fourth diodes can be used to achieve reverse current protection between the input terminal of the power converter and the bus capacitor. For example, current from the first terminal of the bus capacitor cannot flow into the second input terminal through the fourth diode, nor can it flow into the first input terminal through the second transistor, thus achieving reverse current protection.

[0014] In one optional embodiment, the reverse current protection circuit includes a half-bridge circuit mainly composed of two diodes. This half-bridge reverse current protection circuit may include two diodes. The anode of one diode is electrically connected to the first input terminal, and the cathode is electrically connected to the first terminal of the bus capacitor. The cathode of the other diode is electrically connected to the second input terminal, and the anode is electrically connected to the second terminal of the bus capacitor. The reverse current protection effect of the half-bridge circuit is similar to that of the full-bridge circuit, and will not be elaborated further here.

[0015] In one optional embodiment, the anti-reverse circuit may include a thyristor with unidirectional conduction, wherein the anode of the thyristor is electrically connected to the first input terminal and the cathode is electrically connected to the first terminal of the bus capacitor, thereby achieving the effect of current anti-reverse.

[0016] In one optional embodiment, the primary-side switching circuit includes a first primary-side transistor and a second primary-side transistor forming the same bridge arm. The primary-side switching circuit alternates between a first stage and a second stage. In the first stage, the first primary-side transistor and the second primary-side transistor are alternately turned on. The turn-on time of the first primary-side transistor at least partially overlaps with the turn-on time of the second secondary-side transistor, and the turn-on time of the second primary-side transistor at least partially overlaps with the turn-on time of the first secondary-side transistor. This allows the primary-side switching circuit to output the aforementioned first AC voltage to the transformer circuit, and the secondary-side switching circuit to rectify the second AC voltage converted by the transformer circuit, ultimately enabling the power converter to convert DC voltage to DC voltage. Furthermore, in the second stage, the first primary-side transistor and the second primary-side transistor are in a cut-off state. Thus, only in the first stage do the first and second primary-side switching control signals possess primary-side pulse waves. Therefore, depending on the load conditions, for example, when the load is under heavy load, the primary-side switching circuit remains in the first stage; when the load is under light load or no load, the primary-side switching circuit alternates between the first and second stages to reduce power consumption.

[0017] In one optional embodiment, the primary-side switching circuit includes a first primary-side transistor and a second primary-side transistor forming the same bridge arm. The primary-side switching circuit alternates between a first stage and a second stage. In the first stage, the first primary-side transistor and the second primary-side transistor are alternately turned on. The turn-on time of the first primary-side transistor at least partially overlaps with the turn-on times of the second and third secondary-side transistors, and the turn-on time of the second primary-side transistor at least partially overlaps with the turn-on times of the first and fourth secondary-side transistors. This allows the primary-side switching circuit to output the aforementioned first AC voltage to the transformer circuit, and the secondary-side switching circuit to rectify the second AC voltage converted by the transformer circuit, ultimately enabling the power converter to convert DC voltage into DC voltage. In the second stage, the first primary-side transistor and the second primary-side transistor are in the off state. The technical effects of the first and second stages described above are similar and will not be repeated here.

[0018] In one optional embodiment, the power converter includes a first input terminal and a second input terminal. The power converter also includes a bus capacitor, a first resistor, and a first switching transistor. The first and second terminals of the bus capacitor are electrically connected to the first and second input terminals, respectively. The first switching transistor and the first resistor are connected in series between the first and second terminals of the bus capacitor. Therefore, if at least one of the first and second input terminals is de-energized, the first switching transistor can be turned on, electrically connecting the first resistor, which is connected in series with the first switching transistor, between the first and second terminals of the bus capacitor. At this time, the current from the bus capacitor can flow through the first resistor in the direction of the arrow. Therefore, the first resistor can form a discharge path in parallel with the bus capacitor. In this way, under the combined discharge effect of the first resistor and the bus capacitor, the voltage at the input terminal can be reduced to below 60V within 2 seconds to meet safety discharge requirements.

[0019] In one optional embodiment, the power converter includes a startup circuit and a reverse protection circuit, with the reverse protection circuit connected in parallel with the startup circuit. Furthermore, the power converter also includes a second resistor, which is connected in parallel with the startup circuit and in series with the reverse protection circuit. When the power converter is first powered on, the startup circuit is not yet conducting. At this time, the current input to the power converter can first pass through the reverse protection circuit and the second resistor to charge the bus capacitor. The second resistor can act as a current limiter to protect the components downstream of the second resistor, such as the bus capacitor, primary-side switching circuit, transformer circuit, and secondary-side switching circuit, from damage by overload current. Furthermore, the current passing through the second resistor can continue to charge the bus capacitor. As the bus capacitor continues to charge, the voltage across the bus capacitor gradually becomes equal to the voltage between the first input terminal and the second input terminal, i.e., the first voltage. At this time, the startup circuit is turned on, and the current input to the power converter can pass through the startup circuit to charge the bus capacitor. This allows the bus capacitor to slowly discharge into the primary-side switching circuit when it first starts working, thereby reducing the initial current flowing into the primary-side switching circuit and making the startup process of the primary-side switching circuit, transformer circuit, and secondary-side switching circuit more stable.

[0020] In one optional embodiment, the power converter's input terminals include a first input terminal and a second input terminal. The power converter also includes a bus capacitor, with a first terminal and a second terminal electrically connected to the first input terminal and the second input terminal, respectively. A startup circuit is electrically connected to both the first input terminal and the first terminal of the bus capacitor. Thus, by controlling the switching on and off between the first input terminal and the first terminal of the bus capacitor through the startup circuit, the connection or disconnection between the power converter's input terminal and the primary-side switching circuit can be controlled.

[0021] In one optional embodiment, the power converter further includes a first operating voltage terminal and a ground terminal. The starting circuit includes a relay, whose two main contacts are electrically connected to a first input terminal and a first terminal of a bus capacitor, respectively. Furthermore, the distance between the main contacts of the relay is greater than or equal to a preset insulation distance. In this case, the relay can be a reinforced insulation relay. Additionally, the starting circuit includes a third switching transistor and a fourth switching transistor. The third switching transistor, the fourth switching transistor, and the control terminal of the relay are connected in series between the first operating voltage terminal and the ground terminal. Thus, when one of the third and fourth switching transistors (e.g., the third switching transistor) fails and cannot conduct or cut off normally, the other transistor (e.g., the fourth switching transistor) can conduct or cut off normally as needed, allowing the relay to conduct or disconnect normally as required. In this case, since the relay in the starting circuit is a reinforced insulation relay, and the circuit controlling the relay's conduction or disconnection includes two transistors connected in series (i.e., the third and fourth switching transistors), the starting circuit can have dual safety guarantees to reduce the probability of starting circuit failure.

[0022] Another aspect of this application provides an electrical appliance. The electrical appliance includes a load and any of the power converters described above. The output terminal of the power converter is electrically connected to the load. The electrical appliance has the same technical effects as the power converters provided in the foregoing embodiments, and will not be repeated here.

[0023] In another aspect, this application provides a power supply system. The power supply system may include a DC power supply and the electrical device as described above. The DC power supply is electrically connected to a first input terminal and a second output terminal of a power converter in the electrical device. The power supply system has the same technical effects as the power converter provided in the foregoing embodiments, and will not be repeated here.

[0024] In another aspect, this application provides a control method for a power converter. The control method includes receiving a DC voltage. Next, the voltage at the input terminal of the power converter is applied to both ends of a bus capacitor, and a primary-side switching circuit connected in parallel with the bus capacitor receives a first voltage across the bus capacitor. Based on this, the primary-side switching circuit controls the reception of the first voltage across the bus capacitor. Then, in the primary-side switching circuit, a first primary-side transistor and a second primary-side transistor forming the same bridge arm are controlled to conduct alternately. Alternatively, the primary-side switching circuit alternately operates in a first stage and a second stage. In the first stage, the first primary-side transistor and the second primary-side transistor are controlled to conduct alternately. In the second stage, the first primary-side transistor and the second primary-side transistor are controlled to be in a cutoff state. The primary-side switching circuit inverts the first DC voltage received at the input terminal of the power converter into a first AC voltage. Furthermore, a transformer circuit converts the first AC voltage into a second AC voltage and provides the second AC voltage to the secondary-side switching circuit. Furthermore, in the secondary-side switching circuit, the first and second secondary-side transistors, used to rectify the second AC voltage, are alternately turned on. The secondary-side switching circuit rectifies the second AC voltage into a second DC voltage, which is then supplied to the load through the output of the power converter. The first and second DC voltages are different. Additionally, if the input of the power converter does not receive a DC voltage, the bus capacitor discharges. The control method has the same technical effects as the power converter provided in the aforementioned embodiment, and will not be repeated here.

[0025] In one optional implementation, after the bus capacitor discharges, the control method further includes: if the voltage across the bus capacitor discharges to an undervoltage level, a start-up circuit electrically connected between the input terminal of the power converter and the bus capacitor controls the disconnection between the input terminal of the power converter and the bus capacitor. Furthermore, an anti-reverse circuit connected in parallel with the start-up circuit prevents current from the bus capacitor from flowing back into the input terminal of the power converter. In summary, when the input terminal of the power converter is de-energized, the first and second secondary transistors can be alternately turned on to utilize the losses of the primary and secondary switching circuits to increase the discharge rate of the bus capacitor. This allows the input voltage to drop from a first voltage, for example, around 380V, to an undervoltage level in a short time. Based on this, the start-up circuit can be controlled to disconnect the input terminal of the power converter from the bus capacitor. At this time, the anti-reverse circuit can temporarily reduce the input voltage Vin from an undervoltage level to below 60V to meet safety discharge requirements.

[0026] In one optional implementation, the current from the bus capacitor flows in reverse through an anti-reverse circuit connected in parallel with the startup circuit into the input terminal of the power converter. After the bus capacitor discharges, the control method further includes: if the voltage across the bus capacitor discharges to an undervoltage level, controlling the first switching transistor to turn on, and electrically connecting a first resistor, which is connected in series with the first switching transistor, between the first and second terminals of the bus capacitor, allowing the current from the bus capacitor to flow through the first resistor. At this time, the first resistor can form a discharge path in parallel with the bus capacitor. In this way, under the combined discharge effect of the first resistor and the bus capacitor, the input voltage Vin can be further reduced from an undervoltage level to below 60V within a short time to meet the safety discharge requirements.

[0027] In one optional implementation, the current from the bus capacitor flows in reverse to the first input terminal through an anti-reverse circuit connected in parallel with the startup circuit. Based on this, after the bus capacitor is discharged, the control method further includes: controlling the first secondary transistor and the second secondary transistor to conduct alternately, so that the input voltage Vin can continue to decrease from an undervoltage voltage to below 60V within a short period of time to meet the safety discharge requirements.

[0028] In one optional implementation, if the output terminal of the power converter cannot output the second DC voltage, i.e., at least one of the primary-side switching circuit, transformer circuit, and secondary-side switching circuit in the power converter fails, the control method further includes: a starting circuit electrically connected between the input terminal of the power converter and the bus capacitor, controlling the disconnection between the input terminal of the power converter and the bus capacitor, so that after at least one of the primary-side switching circuit, transformer circuit, and secondary-side switching circuit fails, the anti-reverse circuit can reduce the input voltage Vin from the fault voltage to below 60V for a short time to meet the safety discharge requirements. Attached Figure Description

[0029] Figure 1 is a schematic diagram of a power supply system provided in an embodiment of this application;

[0030] Figure 2A is a schematic diagram of another power supply system provided in an embodiment of this application;

[0031] Figure 2B is a schematic diagram of another power supply system provided in an embodiment of this application;

[0032] Figure 2C is a schematic diagram of another power supply system provided in an embodiment of this application;

[0033] Figure 3 is a schematic diagram of another power supply system provided in an embodiment of this application;

[0034] Figure 4 is a detailed schematic diagram of the power converter in Figure 3;

[0035] Figure 5A is a detailed schematic diagram of the voltage conversion circuit in Figure 4;

[0036] Figure 5B is another schematic diagram that details the specific structure of the voltage conversion circuit in Figure 4;

[0037] Figure 6 is a control waveform diagram of a power converter provided in an embodiment of this application;

[0038] Figure 7 is a schematic diagram of the specific structure of a power converter provided in an embodiment of this application;

[0039] Figure 8 is a control waveform diagram of another power converter provided in an embodiment of this application;

[0040] Figure 9 is a schematic diagram of one control state of the power converter shown in Figure 7;

[0041] Figure 10 is a schematic diagram of another control state of the power converter shown in Figure 7;

[0042] Figure 11 is a schematic diagram of another control state of the power converter shown in Figure 7;

[0043] Figure 12 is a schematic diagram of another control state of the power converter shown in Figure 7;

[0044] Figure 13 is an equivalent schematic diagram of a power converter provided in an embodiment of this application;

[0045] Figure 14 is a schematic diagram of the specific structure of another power converter provided in an embodiment of this application;

[0046] Figure 15 is a schematic diagram of a power conversion circuit provided by related technologies;

[0047] Figure 16 is a schematic diagram of another power conversion circuit provided by related technologies;

[0048] Figure 17 is a schematic diagram of the specific structure of another power converter provided in an embodiment of this application;

[0049] Figure 18A is a schematic diagram of the specific structure of another power converter provided in an embodiment of this application;

[0050] Figure 18B is a flowchart of a power converter control method provided in an embodiment of this application;

[0051] Figure 19 is a schematic diagram of a discharge curve of the power converter shown in Figure 17;

[0052] Figure 20 is a schematic diagram of another discharge curve of the power converter shown in Figure 17;

[0053] Figure 21 is a schematic diagram of the specific structure of another power converter provided in an embodiment of this application;

[0054] Figure 22 is a schematic diagram of the specific structure of another power converter provided in an embodiment of this application;

[0055] Figure 23 is a schematic diagram of a discharge curve of the power converter shown in Figure 22;

[0056] Figure 24 is a schematic diagram of the specific structure of another power converter provided in an embodiment of this application;

[0057] Figure 25 is a schematic diagram of another discharge curve of the power converter shown in Figure 22;

[0058] Figure 26 is a schematic diagram of another discharge curve of the power converter shown in Figure 22;

[0059] Figure 27 is a schematic diagram of the specific structure of another power converter provided in an embodiment of this application;

[0060] Figure 28 is a schematic diagram of the specific structure of another power converter provided in an embodiment of this application;

[0061] Figure 29 is a schematic diagram of another discharge curve of the power converter shown in Figure 28;

[0062] Figure 30 is a schematic diagram of another discharge curve of the power converter shown in Figure 28;

[0063] Figure 31 is a schematic diagram of another discharge curve of the power converter shown in Figure 28.

[0064] Reference numerals: 100-Power supply system; 10-DC power supply; 20-Electrical equipment; 21-Power converter; 22-Load; 23-DC / AC voltage converter; 212-Voltage conversion circuit; Va-First terminal of DC power supply; Vb-Second terminal of DC power supply; Cbus-Bus capacitor; Vin1-First input terminal; Vin2-Second input terminal; Vout-Output terminal; 2120-Primary-side switching circuit; 2121-Secondary-side switching circuit; M1-First primary-side transistor; M2-Second primary-side transistor; SR1-First secondary-side transistor; S R2 - Second secondary transistor; 2122 - Resonant circuit; 2123 - Transformer circuit; M3 - Third primary transistor; M4 - Fourth primary transistor; 41 - First secondary winding; 42 - Second secondary winding; 40 - Secondary winding; 210 - Start-up circuit; 213 - Reverse protection circuit; 30 - Start-up switch; 31 - DC / DC converter; 32 - Full-bridge circuit; 2101 - Relay; T1 - First switching transistor; T2 - Second switching transistor; T3 - Third switching transistor; T4 - Fourth switching transistor; T0 - Switching transistor. Detailed Implementation

[0065] The technical solutions of the embodiments of this application will be described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments.

[0066] In the following description, the terms "first," "second," etc., are used for descriptive convenience only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined with "first," "second," etc., may explicitly or implicitly include one or more of that feature. In the description of this application, unless otherwise stated, "a plurality of" means two or more.

[0067] In this application, unless otherwise expressly specified and limited, the term "electrical connection" should be interpreted broadly. For example, "electrical connection" can be a direct electrical connection, such as physical contact and electrical conduction between two components; it can also be understood as the electrical connection between different components in a circuit structure through physical lines that can transmit electrical signals, such as copper foil or wires on a printed circuit board (PCB), to transmit electrical signals; or, "electrical connection" can be an indirect electrical connection between two components through an intermediate medium; or, "electrical connection" can be an electrical connection between two components in a non-contact manner, such as an electrical connection between two components using capacitive coupling to transmit electrical signals.

[0068] In the embodiments of this application, directional terms such as "left" and "right" may be defined relative to the indicated placement of components in the accompanying drawings. It should be understood that these directional terms are relative concepts, used for relative description and clarification, and may change accordingly depending on the placement of components in the accompanying drawings. In the accompanying drawings of the embodiments of this application, components are represented by arrowed guide lines; parts are represented only by guide lines.

[0069] This application provides a power supply system 100 as shown in Figure 1. The power supply system 100 can be a high-voltage direct current (HVDC) power supply system. HVDC power supply systems can be applied in the power industry, communication or network service industry, new energy industry, electric vehicle and charging station industry, medical equipment industry, or aviation industry, etc., and this application does not limit the application to these fields. Specifically, HVDC power supply systems applied in the power industry can be used for long-distance power supply. HVDC power supply systems applied in the communication or network service industry can supply power to equipment such as base stations, routers, switches, or data center servers. HVDC power supply systems applied in the new energy industry can convert new energy sources such as solar or wind energy into direct current and transmit it to the power grid or energy storage equipment.

[0070] As an example, continuing as shown in Figure 1, the power supply system 100 may include a DC power supply 10 and at least one electrical device 20. For example, the DC power supply 10 may be a high-voltage DC power supply and may be used to output a higher voltage; for example, the DC power supply 10 may be used to output a DC power supply of 200V to 400V.

[0071] For example, DC power supply 10 can convert a three-phase 380V alternating current (AC) voltage into, for example, a direct current (DC) voltage of approximately 800V. Alternatively, DC power supply 10 can convert a single-phase 220V alternating current (AC) voltage into, for example, a direct current (DC) voltage of approximately 400V. The output of DC power supply 10 can be electrically connected to the input of electrical device 20 so that electrical device 20 can receive DC power (e.g., approximately 800V or 400V) supplied by DC power supply 10.

[0072] Figure 1 illustrates an example of a DC power supply 10 and an electrical device 20 being electrically connected. In other embodiments of this application, as shown in Figure 2A, the DC power supply 10 in the power supply system 100 can be electrically connected to at least two electrical devices 20. This application does not limit the number of electrical devices 20.

[0073] Furthermore, continuing as shown in FIG2A, in some embodiments of this application, the electrical device 20 may include a power converter 21 and a load 22. The power converter 21 is coupled between the DC power supply 10 and the load 22. The power converter 21 is used to receive a DC voltage, such as a first voltage V1, provided by the DC power supply 10, and convert the received first voltage V1 into a second voltage V2 to provide to the load 22 to meet the normal power consumption needs of the load 22.

[0074] Specifically, the power converter 21 includes an input terminal Vin and an output terminal Vout. The input terminal Vin is electrically connected to the output terminal of the DC power supply 10, and the input terminal Vin of the power converter 21 is used to receive a DC voltage, such as a first voltage V1, provided by the DC power supply 10. The output terminal Vout of the power converter 21 can be electrically connected to a load 22, and the output terminal Vout of the power converter 21 can provide a converted second voltage V2 to the load 22. The power converter 21 can be a direct current to direct current (DC / DC) voltage converter.

[0075] For example, as shown in Figure 2B, the number of power converters 21 corresponding to a load 22 can be multiple, with multiple power converters 21 connected in series between the DC power supply 10 and the load 22. These multiple power converters 21 can sequentially convert the voltage at their respective input terminals, thereby progressively boosting or bucking the voltage provided by the DC power supply 10. Therefore, from the output terminal of the DC power supply 10 to the input terminal of the load 22, multiple power converters 21 connected in series can be called a single-stage power converter, a two-stage power converter, a three-stage power converter, and so on. Compared to a scheme where only one power converter 21 is connected in series between the DC power supply 10 and the load 22, connecting multiple power converters in series can reduce the power consumption of each power converter 21 and improve voltage conversion efficiency.

[0076] For example, taking the application of a high-voltage DC power supply system in the network service field, the power supply device 20 can be a server in a data center, and the load 22 shown in Figure 2B can be a chip in the data center server used for computing or control. This chip can be used in a data center or server. The operating voltage of the load 22 can be approximately 3.3V or 1.2V. Since there is a large difference between the DC voltage provided by the DC power supply 10 (e.g., approximately 380V or 220V) and the operating voltage of the load 22 (e.g., approximately 3.3V or 1.2V), in order to improve the voltage conversion efficiency and reduce power consumption, two power converters 21 can be connected in series between the DC power supply 10 and the load 22. As can be seen from the above, from the output terminal of the DC power supply 10 to the input terminal of the load 22, the two power converters 21 are respectively a first-stage power converter and a second-stage power converter. The first-stage power converter can convert the DC voltage (e.g., approximately 380V or 220V) provided by the DC power supply 10 into a DC voltage of approximately 48V or 12V. In addition, the secondary power converter can convert the DC voltage (e.g., around 48V or 12V) provided by the power converter 21 into a DC voltage of around 3.3V or 1.2V, which is the operating voltage of the load 22.

[0077] The two power converters 21 described above can be used for voltage reduction. Alternatively, in some other embodiments of this application, the two power converters 21 can be used for voltage boosting. This application does not limit the function of the power converters 21; for ease of explanation, the following examples use the power converters 21 for voltage reduction. Alternatively, in some other embodiments of this application, when the voltage output by one power converter 21 can reach the operating voltage of the load 22, as shown in Figure 2B, only one power converter 21 may be provided in the electrical device 20, provided that the power conversion efficiency and power consumption requirements are met.

[0078] Alternatively, in some other embodiments of this application, when the input voltage received by the load 22 is an AC voltage, as shown in FIG2C, a direct current to alternating current (DC / AC) voltage converter 23 can be connected in series between the power converter 21 and the load 22. This DC / AC voltage converter 23 can convert the DC voltage output by the power converter 21 into an AC voltage for driving the load 22.

[0079] This application does not limit the type of operating voltage of the load 22. For ease of explanation, the following examples use the example of the power-consuming device 20 being a data center server and the load 22 being a chip in the data center server responsible for computation or control. Furthermore, the power supply system 100 may also include power distribution equipment. The power distribution equipment can be a distribution box or distribution cabinet, etc., and can be electrically connected between the DC power supply 10 and the power-consuming device 20.

[0080] As shown in Figure 3, the output terminal of the power converter 21 may include a first input terminal Vin1 and a second input terminal Vin2. The first input terminal Vin1 and the second input terminal Vin2 can be electrically connected to the first terminal Va and the second terminal Vb of the DC power supply 10, respectively. That is, the first input terminal Vin1 of the power converter 21 can be electrically connected to the first terminal Va of the DC power supply 10, and the second input terminal Vin2 of the power converter 21 can be electrically connected to the second terminal Vb of the DC power supply 10.

[0081] For example, the first terminal Va of the DC power supply 10 can be positive, and the second terminal Vb of the DC power supply 10 can be negative. Alternatively, the first terminal Va of the DC power supply 10 can be negative, and the second terminal Vb of the DC power supply 10 can be positive; this application does not limit this.

[0082] For ease of explanation, the following examples use the first terminal Va of the DC power supply 10 as the positive terminal and the second terminal Vb of the DC power supply 10 as the negative terminal. Alternatively, the power converter 21 may also have two output terminals Vout, used for electrical connection to the positive and negative terminals of the load in Figure 2C, respectively.

[0083] In some embodiments of this application, continuing as shown in FIG3, the power converter 21 may include: a bus capacitor Cbus and a voltage conversion circuit 212. The bus capacitor Cbus and the voltage conversion circuit 212 are connected in parallel. The bus capacitor Cbus is used to charge or discharge to provide a stable input voltage to the voltage conversion circuit 212. The voltage conversion circuit 212 is used to convert the voltage across the bus capacitor Cbus, for example, a first voltage V1, into a second voltage V2 and provide it to the output terminal Vout of the power converter 21.

[0084] Specifically, the bus capacitor Cbus can have a first terminal c1 and a second terminal c2. The first terminal c1 of the bus capacitor Cbus can be electrically connected to the first input terminal Vin1 of the power converter 21, and the second terminal c2 of the bus capacitor Cbus can be electrically connected to the second input terminal Vin2 of the power converter 21. The voltage conversion circuit 212 is electrically connected between the bus capacitor Cbus and the output terminal Vout. The voltage conversion circuit 212 can be used to receive the first voltage V1 (e.g., 800V) across the bus capacitor Cbus and convert it into a second voltage V2 (e.g., 48V or 12V) to be provided to the output terminal Vout. Therefore, the voltage conversion circuit 212 can be the main component in the power converter 21 that realizes the conversion of DC voltage to DC voltage.

[0085] Continuing as shown in Figure 3, the bus capacitor Cbus can act as a filter, removing noise from the input voltage of the DC power supply 10, thus making the voltage input to the voltage conversion circuit 212 smoother and more stable. Furthermore, the bus capacitor Cbus can also serve the purposes of energy storage, decoupling, isolation, and surge current suppression. The bus can be a conductor in the power converter 21 that collects and distributes electrical energy. The bus capacitor Cbus can be a capacitor installed on the bus.

[0086] The specific structure of the voltage conversion circuit 212 is illustrated below. In some embodiments of this application, as shown in FIG4, the voltage conversion circuit 212 includes a primary-side (TPS) switching circuit 2120, a resonant circuit 2122, a transformer circuit 2123, and a secondary-side (TSS) switching circuit 2121. The primary-side switching circuit 2120 is electrically connected between the bus capacitor Cbus and the resonant circuit 2122. This primary-side switching circuit 2120 is used to invert the first DC voltage received at the input terminals of the power converter 21, such as the first input terminal Vin and the second input terminal Vin, into a first AC voltage. The resonant circuit 2122 is electrically connected to the transformer circuit 2123. This resonant circuit 2122 is used to utilize the resonant characteristics to transfer energy from the primary side to the secondary side in cooperation with the transformer circuit 2123 during the energy storage and release process. The transformer circuit 2123 is electrically connected to the secondary-side switching circuit 2121. The transformer circuit 2123 converts a first AC voltage to a second AC voltage and provides the second AC voltage to the secondary-side switching circuit 2121. For example, the transformer circuit 2123 achieves the conversion from primary to secondary voltage through the turns ratio of the primary and secondary windings. The secondary-side switching circuit 2121 rectifies the second AC voltage into a second DC voltage and provides it to the load through the output of the power converter 21. The first DC voltage, for example, a first voltage V1, is different from the second DC voltage, for example, a second voltage V2.

[0087] Current can change with voltage. When a DC voltage is converted to an AC voltage, the current in the circuit is also converted from DC current to AC current. Therefore, when the primary-side switching circuit 2120 inverts the first DC voltage to the first AC voltage, it also inverts the received first DC current to the first AC current. Similarly, when the transformer circuit 2123 converts the first AC voltage to the second AC voltage, it also converts the first AC current to the second AC current. When the secondary-side switching circuit 2121 rectifies the second AC voltage to the second DC voltage, it also rectifies the second AC current to the second DC current. Therefore, in some embodiments of this application, the primary-side switching circuit 2120, the transformer circuit 2123, and the secondary-side switching circuit 2121 can perform either voltage conversion or current conversion during the electrical signal conversion process.

[0088] For example, at least one of the primary-side switching circuit 2120, resonant circuit 2122, and transformer circuit 2123 described above can be integrated into the chip. The secondary-side switching circuit 2121 can also be integrated into the chip. Alternatively, the secondary-side switching circuit 2121 can be independent of the chip.

[0089] Specifically, as shown in Figure 4, the primary-side switching circuit 2120 can convert the DC voltage output from the DC power supply 10 (as shown in Figure 3), such as the first voltage V1, into a high-frequency square wave. The voltage across the bus capacitor Cbus is Vbus, where Vbus = V1. After the high-frequency square wave enters the resonant circuit 2122, the resonant cavity of the resonant circuit 2122 can eliminate the harmonics of the square wave and output a sine wave. The sine wave is then transmitted to the secondary-side switching circuit 2121 via the transformer circuit 2123. The transformer circuit 2123 can perform voltage conversion, stepping down the output voltage as needed. Alternatively, the transformer circuit 2123 can perform voltage conversion, stepping up the output voltage as needed to convert the first voltage V1 into the second voltage V2. Furthermore, the secondary-side switching circuit 2121 can convert the sine wave output from the transformer circuit 2123 into a stable DC voltage and transmit it to the output terminal Vout as shown in Figure 3.

[0090] To enable the primary-side switching circuit 2120 to convert the input DC voltage into a high-frequency square wave, which is an AC signal, as shown in Figure 5A, the primary-side switching circuit 2120 in the voltage conversion circuit 212 may include a first primary-side transistor M1 and a second primary-side transistor M2 forming the same bridge arm. The first primary-side transistor M1 can be the upper bridge arm, and the second primary-side transistor M2 can be the lower bridge arm. Furthermore, the first primary-side transistor M1 and the second primary-side transistor M2 can be connected in series between the first terminal c1 and the second terminal c2 of the bus capacitor Cbus. The first primary-side transistor M1 and the second primary-side transistor M2 can form a half-bridge circuit structure, which has one bridge arm. The gate (G) of the first primary-side transistor M1 can be used to receive the first primary-side switching control signal S11, and the gate of the second primary-side transistor M2 can be used to receive the second primary-side switching control signal S12.

[0091] The first primary-side switch control signal S11 and the second primary-side switch control signal S12 can control the alternating conduction of the first primary-side transistor M1 and the second primary-side transistor M2 to control the current in the circuit. When the first primary-side transistor M1 is turned on, Vbus can be applied to the resonant circuit 2122, so that energy from the DC power supply 10 (as shown in Figure 3) can be transferred to the resonant circuit 2122. Alternatively, when the second primary-side transistor M2 is turned on, Vbus can be applied to the resonant circuit 2122. Energy can establish oscillating current and voltage in the resonant cavity of the resonant circuit 2122. When the transistor is turned off (or disconnected), the energy transfer process also stops.

[0092] For example, as shown in Figure 6, when the first primary-side switch control signal S11 is high, the first primary-side transistor M1 in Figure 5A is turned on; when the first primary-side switch control signal S11 is low, the first primary-side transistor M1 in Figure 5A is turned off. Alternatively, when the first primary-side switch control signal S11 is low, the first primary-side transistor M1 in Figure 5A is turned on; when the first primary-side switch control signal S11 is high, the first primary-side transistor M1 in Figure 5A is turned off. This application does not limit this. For ease of explanation, the following examples all use the transistor being turned on when the gate is high and turned off when the gate is low.

[0093] Alternatively, when the second primary-side switch control signal S12 is high, the second primary-side transistor M2 in Figure 5A is turned on; when the second primary-side switch control signal S12 is low, the second primary-side transistor M2 is turned off. Alternatively, when the second primary-side switch control signal S12 is low, the second primary-side transistor M2 is turned on; when the second primary-side switch control signal S12 is high, the second primary-side transistor M2 is turned off.

[0094] In this case, for example, continuing as shown in Figure 6, when the frequency of the first primary-side switch control signal S11 is low, the voltage output by the voltage conversion circuit 212 is high. Conversely, when the frequency of the first primary-side switch control signal S11 is high, the voltage output by the voltage conversion circuit 212 is low. Alternatively, when the frequency of the second primary-side switch control signal S12 is low, the voltage output by the voltage conversion circuit 212 is high. Conversely, when the frequency of the second primary-side switch control signal S12 is high, the voltage output by the voltage conversion circuit 212 is low.

[0095] As another example, continuing as shown in Figure 6, when the duty cycle of the first primary-side switch control signal S11 is large, the first primary-side transistor M1 in Figure 5A is on for a longer period, resulting in greater energy transferred to the secondary side of transformer circuit 2123 and a higher output voltage from voltage conversion circuit 212. Conversely, when the duty cycle of the first primary-side switch control signal S11 is small, the first primary-side transistor M1 in Figure 5A is on for a shorter period, resulting in less energy transferred to the secondary side of transformer circuit 2123 and a lower output voltage from voltage conversion circuit 212.

[0096] Alternatively, when the duty cycle of the second primary-side switch control signal S12 is large, the second primary-side transistor M2 is on for a longer period, resulting in greater energy transferred to the secondary side of the transformer circuit 2123 and a higher output voltage from the voltage conversion circuit 212. Conversely, when the duty cycle of the second primary-side switch control signal S12 is small, the second primary-side transistor M2 is on for a shorter period, resulting in less energy transferred to the secondary side of the transformer circuit 2123 and a lower output voltage from the voltage conversion circuit 212. Furthermore, the duty cycle of the primary-side switch control signal can also affect the voltage conversion efficiency of the voltage conversion circuit 212. This application does not limit the duty cycle of the primary-side switch control signal.

[0097] This example illustrates the concept of a half-bridge circuit using the primary-side switching circuit 2120 as an example. Alternatively, for another example, the primary-side switching circuit 2120 can be a full-bridge circuit as shown in Figure 7. In this case, in addition to the first primary-side transistor M1 and the second primary-side transistor M2, the primary-side switching circuit 2120 can also include a third primary-side transistor M3 and a fourth primary-side transistor M4. The first primary-side transistor M1 and the second primary-side transistor M2 can form one bridge arm. The third primary-side transistor M3 and the fourth primary-side transistor M4 can form the other bridge arm. Therefore, the full-bridge circuit has two bridge arms. The first primary-side transistor M1 and the third primary-side transistor M3 can be simultaneously turned on or off. The second primary-side transistor M2 and the fourth primary-side transistor M4 can be simultaneously turned on and off. The first primary-side transistor M1 and the second primary-side transistor M2 can still be turned on alternately.

[0098] This application does not limit the structure of the primary-side switching circuit 2120. For ease of explanation, the following description uses a half-bridge circuit as an example. Furthermore, the transistor is a power switch, which can be a metal-oxide-semiconductor field-effect transistor (MOSFET) or an insulated-gate bipolar transistor (IGBT). This application does not limit the specific type of power switch.

[0099] Continuing with Figure 5A or Figure 7, the resonant circuit 2122 may include an inductor (L) and a capacitor (Cr). For example, the resonant circuit 2122 may include a resonant inductor Lr, a magnetizing inductor Lm, and resonant capacitors (e.g., resonant capacitors Cr1 and Cr2). In this case, the topology of the voltage conversion circuit 212 can be an LLC resonant converter. Furthermore, continuing with Figure 5A or Figure 7, the transformer circuit 2123 may include a primary winding and a secondary winding, the primary winding being referred to as the primary coil and the secondary winding as the secondary coil. The primary winding is electrically connected to the resonant circuit 2122, and the secondary winding is electrically connected to the secondary switching circuit 2121. By adjusting the turns ratio of the primary and secondary windings, the output voltage ratio of the transformer circuit 2123 can be adjusted.

[0100] Building upon this, as shown in Figure 5A or Figure 7, to enable the secondary-side switching circuit 2121 to convert the input sine wave into a DC voltage, the secondary-side switching circuit 2121 may include a first secondary-side transistor SR1 and a second secondary-side transistor SR2 connected in series. The first secondary-side transistor SR1 and the second secondary-side transistor SR2 are electrically connected between the secondary winding and the output terminal of the power converter 21. The gate of the first secondary-side transistor SR1 can be used to receive the first secondary-side switching control signal S21, and the gate of the second secondary-side transistor SR3 can be used to receive the second secondary-side switching control signal S22. The first secondary-side transistor SR1 and the second secondary-side transistor SR2 are respectively used to rectify the positive half-axis electrical signal and the negative half-axis electrical signal of the aforementioned second AC voltage.

[0101] For example, the first secondary-side transistor SR1 and the second secondary-side transistor SR2 can be synchronous rectification (SR) transistors. This allows MOSFETs with lower on-state resistance to replace rectifier diodes, reducing rectification losses. When a MOSFET is used as a synchronous rectification transistor, the gate voltage must be synchronized with the phase of the rectified voltage to complete the rectification function; hence the name synchronous rectification. SR transistors have characteristics such as low on-resistance (in the milliohm range), low forward voltage drop, high converter system efficiency, high blocking voltage, and low reverse current, making them widely used in high-power, low-output-voltage converter systems.

[0102] Continuing as shown in Figure 5A or Figure 7, the first secondary-side switch control signal S21 and the second secondary-side switch control signal S22 can control the first secondary-side transistor SR1 and the second secondary-side transistor SR2 to conduct alternately at high frequency, thereby achieving rectification. For example, as shown in Figure 6, when the first secondary-side transistor SR1 is at a high level, the first secondary-side transistor SR1 in Figure 5A is turned on; when the first secondary-side transistor SR1 is at a low level, the first secondary-side transistor SR1 in Figure 5A is turned off. Alternatively, the transistor can conduct when the gate is at a low level and be turned off when the gate is at a high level; this application does not limit this. Since the first secondary-side switch control signal S21 and the second secondary-side switch control signal S22, which serve as driving signals, are at high and low levels respectively, the driving of the first secondary-side transistor SR1 and the second secondary-side transistor SR2 is complementary, causing the first secondary-side transistor SR1 and the second secondary-side transistor SR2 to conduct alternately.

[0103] As shown in Figure 6, when the frequency of the first secondary-side switch control signal S21 or the second secondary-side switch control signal S22 is low, the voltage output by the voltage conversion circuit 212 is high. Conversely, when the frequency of the first secondary-side switch control signal S21 or the second secondary-side switch control signal S22 is high, the voltage output by the voltage conversion circuit 212 is low.

[0104] For example, when the duty cycle of the first secondary-side switch control signal S21 is large, the first secondary-side transistor SR1 in Figure 5A or Figure 7 is on for a longer period, resulting in a higher output voltage from the voltage conversion circuit 212. Conversely, when the duty cycle of the first secondary-side switch control signal S21 is small, the second secondary-side transistor SR1 is on for a shorter period, resulting in a lower output voltage from the voltage conversion circuit 212. Therefore, by controlling the duty cycle of the first secondary-side switch control signal S21, the output voltage of the voltage conversion circuit 212 can be adjusted to a stable value that meets the requirements of the load 22 (as shown in Figure 2C). This application does not limit the duty cycle of the secondary-side switch control signal.

[0105] Alternatively, when the duty cycle of the second secondary-side switch control signal S22 is large, the second secondary-side transistor SR2 is turned on for a longer period, resulting in a higher output voltage from the voltage conversion circuit 212. Conversely, when the duty cycle of the second secondary-side switch control signal S22 is small, the second secondary-side transistor SR2 is turned on for a shorter period, resulting in a lower output voltage from the voltage conversion circuit 212.

[0106] In some embodiments of this application, in order to electrically connect the first secondary transistor SR1 and the second secondary transistor SR2 between the secondary winding and the output terminal of the power converter 21, as shown in FIG5A, the output terminal of the power converter 21 includes a first output terminal Vo1 and a second output terminal Vo2. The first output terminal Vo1 and the second output terminal Vo2 can be used to connect to the positive and negative terminals of the load, respectively.

[0107] Furthermore, the secondary winding of the transformer circuit 2123 includes a first secondary winding 41 and a second secondary winding 42. The first secondary transistor SR1 and the first secondary winding 41 are connected in series between the first output terminal Vo1 and the second output terminal Vo2. The second secondary transistor SR2 and the second secondary winding 42 are connected in series between the first output terminal Vo1 and the second output terminal Vo2. In this case, the secondary switching circuit 2121 can be a full-wave circuit.

[0108] In this configuration, the path formed by the first secondary transistor SR1 and the first secondary winding 41 can rectify the positive half-axis electrical signal of the second AC voltage, and the path formed by the second secondary transistor SR2 and the second secondary winding 42 can rectify the negative half-axis electrical signal of the second AC voltage. Alternatively, the path formed by the first secondary transistor SR1 and the first secondary winding 41 can rectify the negative half-axis electrical signal of the second AC voltage, and the path formed by the second secondary transistor SR2 and the second secondary winding 42 can rectify the positive half-axis electrical signal of the second AC voltage, thereby enabling the power converter 21 to output the aforementioned second DC voltage.

[0109] Alternatively, in some embodiments of this application, to electrically connect the first secondary transistor SR1 and the second secondary transistor SR2 between the secondary winding and the output terminal of the power converter 21, as shown in FIG5B, the secondary switching circuit 2121 further includes a third secondary transistor SR3 and a fourth secondary transistor SR4. The first secondary transistor SR1, the secondary winding 40, and the fourth secondary transistor SR4 are connected in series between the first output terminal Vo1 and the second output terminal Vo2. The third secondary transistor SR3, the secondary winding 40, and the second secondary transistor SR2 are connected in series between the first output terminal Vo1 and the second output terminal Vo2. The first secondary transistor SR1 and the second secondary transistor SR2 form the first bridge arm, and the third secondary transistor SR3 and the fourth secondary transistor SR4 form the second bridge arm. The third secondary transistor SR3 and the fourth secondary transistor SR4 are alternately turned on, and the first secondary transistor SR1 can be turned on simultaneously with the fourth secondary transistor SR4, and the second secondary transistor SR2 can be turned on simultaneously with the third secondary transistor SR3. At this time, the secondary-side switching circuit 2121 can be a full-bridge circuit as shown in Figure 5B.

[0110] In this configuration, the first bridge arm can rectify the positive half-axis electrical signal of the second AC voltage, and the second bridge arm can rectify the negative half-axis electrical signal of the second AC voltage. Alternatively, the first bridge arm can rectify the negative half-axis electrical signal of the second AC voltage, and the second bridge arm can rectify the positive half-axis electrical signal of the second AC voltage, thereby enabling the power converter 21 to output the aforementioned second DC voltage.

[0111] For ease of explanation, the following description primarily uses the secondary-side switching circuit 2121 as an example of a half-bridge circuit. The main operating process of the voltage conversion circuit 212 shown in Figure 5A is illustrated below. In some embodiments of this application, the control phases of the primary-side switching circuit 2120 in the voltage conversion circuit 212 may include the first phase t1 and the second phase t2 as shown in Figure 8. For example, taking the load 22 as a chip responsible for computation, when the load 22 (as shown in Figure 2C) is under heavy load, i.e., under high-speed computation, the primary-side switching circuit 2120 can continuously operate in the first phase t1. When the load 22 (as shown in Figure 2C) is under light load, i.e., under low-speed computation, the primary-side switching circuit 2120 can alternately operate in the first phase t1 and the second phase t2. Alternatively, when the load 22 (as shown in Figure 2C) is under no-load, i.e., when the load 22 is not performing computation, the primary-side switching circuit 2120 can also alternately operate in the first phase t1 and the second phase t2.

[0112] Continuing as shown in Figure 8, in the first stage t1, both the first primary-side switch control signal S11 and the second primary-side switch control signal S12 possess primary-side pulse waves. Either the first stage t1 or the second stage t2 of the primary-side pulse wave can include at least one period T, meaning the duration of any stage can include at least one period T. In the first stage t1, both the first primary-side switch control signal S11 and the second primary-side switch control signal S12 are emitting waves, i.e., emitting pulse waves. The primary-side pulse wave can have one peak and one trough within each period T of the first stage t1. Furthermore, in the light-load, no-load, and heavy-load states of the load 22, the first secondary-side switch control signal S21 and the second secondary-side switch control signal S22 are always in the emitting state.

[0113] For example, in the first stage t1, when the first primary-side switch control signal S11 is high and the second primary-side switch control signal S12 is low, as shown in Figure 9, the first primary-side transistor M1 can be in the on state, and the second primary-side transistor M2 can be in the off or open state. At this time, the current will flow in the direction of the arrow, passing sequentially through the first primary-side transistor M1, the resonant inductor Lr, the primary winding, and the resonant capacitor Cr2 to form a loop. When the current flows in the primary winding, a magnetic field is generated. The magnetic field will induce an electromotive force in the secondary winding to generate an induced current. For ease of explanation, the on transistors are represented by solid lines and the off transistors are represented by dashed lines in the attached figures.

[0114] Furthermore, when the first secondary-side switch control signal S21 is low and the second secondary-side switch control signal S22 is high, the first secondary-side transistor SR1 shown in Figure 9 is turned off, and the second secondary-side transistor SR2 is turned on. At this time, the induced current can pass through the output capacitor Cout and the second secondary-side transistor SR2 to charge the output capacitor Cout.

[0115] For example, in the first stage t1, when the first primary-side switch control signal S11 is low and the second primary-side switch control signal S12 is high, as shown in Figure 10, the first primary-side transistor M1 is in the off state and the second primary-side transistor M2 is in the on state. At this time, the current will pass through the resonant capacitor Cr1, the primary winding, the resonant inductor Lr, and the second primary-side transistor M2 in sequence to form a loop.

[0116] When current flows in the primary winding, the resulting magnetic field induces an electromotive force in the secondary winding. In the first stage t1 (as shown in Figure 8), when the first secondary-side switch control signal S21 is high and the second secondary-side switch control signal S22 is low, the first secondary-side transistor SR1 (as shown in Figure 10) is turned on, and the second secondary-side transistor SR2 is turned off. At this time, the induced current generated by the capacitor can pass through the output capacitor Cout and the first secondary-side transistor SR1 to charge the output capacitor Cout.

[0117] In summary, during the first stage t1 as shown in Figure 8, since the first primary-side switch control signal S11 and the second primary-side switch control signal S12 alternately operate at high or low levels, the first primary-side transistor M1 and the second primary-side transistor M2 can be alternately turned on as shown in Figures 9 and 10. Furthermore, during the first stage t1 as shown in Figure 8, since the first secondary-side switch control signal S21 and the second secondary-side switch control signal S22 alternately operate at high or low levels, the first secondary-side transistor SR1 and the second secondary-side transistor SR2 can be alternately turned on as shown in Figures 9 and 10.

[0118] Specifically, when the secondary-side switching circuit 2121 is a full-wave circuit as shown in Figure 5A, in the first stage t1 as shown in Figure 8, the turn-on time of the first primary-side transistor M1 at least partially overlaps with the turn-on time of the second secondary-side transistor SR2. The turn-on time of the second primary-side transistor M2 at least partially overlaps with the turn-on time of the first secondary-side transistor SR1. Alternatively, when the secondary-side switching circuit 2121 is a full-bridge circuit as shown in Figure 5B, in the first stage t1 as shown in Figure 8, the turn-on time of the first primary-side transistor M1 at least partially overlaps with the turn-on times of the second secondary-side transistor SR2 and the third secondary-side transistor SR3. The turn-on time of the second primary-side transistor M2 at least partially overlaps with the turn-on times of the first secondary-side transistor SR1 and the fourth secondary-side transistor SR4.

[0119] In this example, the at least partial overlap of the conduction times of the two transistors means that the two transistors are conducting simultaneously. This allows the primary-side switching circuit 2120 to output the first AC voltage to the transformer circuit 2123, and the secondary-side switching circuit 2121 to rectify the second AC voltage converted by the transformer circuit 2123. Ultimately, the voltage conversion circuit 212 can convert the first voltage V1 across the bus capacitor Cbus into a second voltage V2 and provide it to the output terminal Vout.

[0120] Furthermore, continuing as shown in Figure 8, during each period T of the second stage t2, the first primary-side switch control signal S11 and the second primary-side switch control signal S12 are both in a non-pulse-generating state, i.e., without pulse waves. For example, in the second stage t2, the first primary-side switch control signal S11 and the second primary-side switch control signal S12 can remain at a low level for several consecutive periods, so that during each period of the second stage t2, the first primary-side transistor M1 and the second primary-side transistor M2 are both in the off state. Thus, only in the first stage t1 do the first primary-side switch control signal S11 and the second primary-side switch control signal S12 have primary-side pulse waves. In the second stage t2, the first primary-side switch control signal S11 and the second primary-side switch control signal S12 remain at a low level. The wave generation mode of the first primary-side switch control signal S11 and the second primary-side switch control signal S12 can be called the burst wave mode. That is, the intermittent wave transmission mode can be understood as transmitting waves at intervals of a certain period of time, such as after the second stage t2. Therefore, the first primary-side switch control signal S11 and the second primary-side switch control signal S12 are in a non-continuous wave transmission state.

[0121] Understandably, depending on the load 22, for example, when the load 22 is under heavy load, the first primary-side switch control signal S11 and the second primary-side switch control signal S12 continuously emit waves, i.e., continuously remain in the first stage t1 shown in Figure 8. When the load 22 is under light load or no load, the first primary-side switch control signal S11 and the second primary-side switch control signal S12 are in an intermittent emission mode, so that the primary-side switch circuit 2120 alternately operates in the first stage t1 and the second stage t2. At this time, the first primary-side transistor M1 and the second primary-side transistor M2 can operate continuously for several cycles in the first stage t1 and then be continuously turned off for several cycles in the second stage t2.

[0122] Furthermore, under light load, no-load, and heavy load conditions, the first secondary-side switch control signal S21 and the second secondary-side switch control signal S22 are always in a waking state. For example, when the first secondary-side switch control signal S21 is high and the second secondary-side switch control signal S22 is low, as shown in Figure 11, the first secondary-side transistor SR1 in the secondary-side switch circuit is in the on state, and the second secondary-side transistor SR2 is in the off state. At this time, current flows in the direction of the arrow, sequentially through the first secondary-side transistor SR1 and the output capacitor Cout, and then flows through the secondary winding. The magnetic field generated by the current flowing in the secondary winding induces an electromotive force in the primary winding, generating an induced current. The direction of the induced current in the primary side can be opposite to the current direction shown in Figure 10. The induced current in the primary side can be called the reverse current.

[0123] Continuing as shown in Figure 11, although both the first primary-side transistor M1 and the second primary-side transistor M2 in the primary-side switching circuit are in the off state, the direction of the reverse current can be the same as the conduction direction of the diode in the second primary-side transistor M2. This allows the reverse current to flow through the diode in the second primary-side transistor M2, and then sequentially through the resonant inductor Lr, the primary winding, and the resonant capacitor Cr1. At this time, current flows through both the primary-side switching circuit and the secondary-side switching circuit of the voltage conversion circuit 212.

[0124] Alternatively, as another example, when the first secondary-side switch control signal S21 is low and the second secondary-side switch control signal S22 is high, continuing as shown in Figure 12, the first secondary-side transistor SR1 in the secondary-side switch circuit is in the off state, and the second secondary-side transistor SR2 is in the on state. At this time, the current will flow in the direction of the arrow, passing sequentially through the second secondary-side transistor SR2 and the output capacitor Cout, and flowing through the secondary winding. The magnetic field generated by the current flowing in the secondary winding will induce an electromotive force in the primary winding, thereby generating an induced current. The direction of the induced current in the primary winding is opposite to the current direction shown in Figure 9, i.e., reverse current.

[0125] Continuing as shown in Figure 12, the direction of the reverse current can be the same as the conduction direction of the diode in the first primary transistor M1, thus flowing sequentially through the resonant capacitor Cr2, the primary winding, the resonant inductor Lr, and the diode in the first primary transistor M1. At this time, current flows through both the primary switching circuit and the secondary switching circuit of the voltage conversion circuit 212.

[0126] In summary, when load 22 is under heavy load, the primary-side switching circuit 2120 remains in the first stage t1 shown in Figure 8. When load 22 is under light load or no load, the primary-side switching circuit 2120 alternates between the first stage t1 and the second stage t2. During each cycle of the first stage t1, the first primary-side transistor M1 and the second primary-side transistor M2 are alternately turned on, and during each cycle of the second stage t2, the first primary-side transistor M1 and the second primary-side transistor M2 are in the off state. However, regardless of whether load 22 is under light load, no load, or heavy load, the first secondary-side transistor SR1 and the second secondary-side transistor SR2 remain alternately turned on. As a result, current flows through both the primary-side switching circuit 2120 and the secondary-side switching circuit 2121 of the voltage conversion circuit 212, causing losses in both circuits. These losses include transistor switching losses and coil losses in the primary and secondary windings. For example, the losses can reach approximately 15W.

[0127] In this case, when the power converter 21 is powered off, for example, when the first input terminal Vin1 of the power converter 21 is disconnected from the first terminal Va of the DC power supply 10, the overall loss of the voltage conversion circuit 212 is relatively large because both the primary-side switching circuit 2120 and the secondary-side switching circuit 2121 of the voltage conversion circuit 212 have losses. The above description refers to the power converter 21 being powered off when the first input terminal Vin1 of the power converter 21 is disconnected from the first terminal Va of the DC power supply 10. In other embodiments, the power converter 21 being powered off may also refer to the power converter 21 being powered off when the second input terminal Vin2 of the power converter 21 is disconnected from the second terminal Vb of the DC power supply 10. Alternatively, the first input terminal Vin1 of the power converter 21 is disconnected from the first terminal Va of the DC power supply 10, and the second input terminal Vin2 of the power converter 21 is disconnected from the second terminal Vb of the DC power supply 10.

[0128] For example, the sum of the bus capacitor Cbus and the output equivalent capacitor Cout' can be equivalent to capacitor C1 as shown in Figure 13, and the resistor R0 can be the total resistance of the electrical device 20. The output equivalent capacitor Cout' can be the equivalent capacitance of the output capacitor Cout at the input terminal. Capacitor C1 and resistor R0 can form a discharge circuit. When the loss of the voltage conversion circuit 212 increases, it is equivalent to increasing the number of parallel resistors in the electrical device 20, thereby reducing the resistance R0. This increases the current in the discharge circuit, thereby increasing the discharge rate of capacitor C1, i.e., increasing the rate at which the energy in the bus capacitor Cbus and the output equivalent capacitor Cout' decreases. This allows the voltage at the input terminals of the power converter 21, i.e., between the first input terminal Vin1 and the second input terminal Vin2, to be reduced from a high voltage, such as 800V, to a safe voltage range, such as ≤60V, in a short time, meeting safety discharge requirements and ensuring the personal safety of maintenance personnel or operators.

[0129] In contrast, in related technologies, the gate control signals of both the primary and secondary transistors in the power converter employ an intermittent waveform mode. During this time, with the load in an unloaded or lightly loaded state, for a period of time, such as the second stage t2 mentioned above, both the primary and secondary transistors can be in a cutoff state. This results in almost no loss, or near-zero loss, in the primary and secondary switching circuits of the power converter during the second stage t2. Consequently, when the input of the power converter is de-energized, the energy stored in the capacitors within the power converter decreases at a relatively low rate due to the low power converter losses (e.g., 5W), making it difficult to meet safety discharge requirements.

[0130] Furthermore, as can be seen from the above, in the voltage conversion circuit 212 of the power converter 21 provided in this application embodiment, the on / off states of the first primary transistor M1, the second primary transistor M2, the first secondary transistor SR1, and the second secondary transistor SR2 are related to the waveform states of the first primary switch control signal S11, the second primary switch control signal S12, the first secondary switch control signal S21, and the second secondary switch control signal S22, respectively, and are unrelated to whether the power converter 21 is in a power-off or non-power-off state.

[0131] That is, regardless of whether the power converter 21 is in a power-off state, as shown in Figure 8, when the load 22 is in a light load state, an unloaded state, or a heavy load state, the first secondary transistor SR1 and the second secondary transistor SR2 always remain alternately turned on. Therefore, the power converter 21 provided in this embodiment does not need to determine whether the input terminal of the power converter 21 is in a power-off state. When the input terminal of the power converter 21 is not in a power-off state, the power converter 21 can convert the first DC voltage V1 into the second DC voltage V2. When the input terminal of the power converter 21 is in a power-off state, the first secondary transistor SR1 and the second secondary transistor SR2 in the power converter 21 always remain alternately turned on, which can reduce the voltage at the input terminal to below 60V within the time required by the safety discharge regulations. In this way, under the condition of meeting the safety discharge requirements, there is no need to distinguish between the power-off state of the power converter 21 and the input terminal of the electrical equipment 20 and the normal fluctuation state of the input voltage of the power converter 21, which is beneficial to reducing costs.

[0132] Furthermore, in some other embodiments of this application, to control the power converter 21 to perform voltage conversion or stop voltage conversion as needed, as shown in FIG14, the power converter 21 may also include a startup circuit 210. The startup circuit 210 may be electrically connected to the input terminal of the power converter 21 and the voltage conversion circuit 212. The startup circuit 210 is used to control the connection or disconnection between the input terminal of the power converter 21 and the voltage conversion circuit 212. For example, when a bus capacitor Cbus is connected in parallel to the input terminal of the voltage conversion circuit 212, the startup circuit 210 is electrically connected between the first input terminal Vin1 of the power converter 21 and the first terminal c1 of the bus capacitor Cbus. The startup circuit 210 can be used to control the connection or disconnection between the first input terminal Vin1 and the first terminal c1 of the bus capacitor Cbus. In this way, by controlling the connection and disconnection between the first input terminal Vin1 and the first terminal c1 of the bus capacitor Cbus through the startup circuit 210, the purpose of controlling the connection or disconnection between the input terminal of the power converter 21 and the voltage conversion circuit 212 can be achieved.

[0133] For example, continuing as shown in Figure 14, when the startup circuit 210 is in the on state, the first input terminal Vin1 can be connected to the first terminal c1 of the bus capacitor Cbus through the startup circuit 210, so that an electrical signal can be transmitted between the first input terminal Vin1 and the first terminal c1 of the bus capacitor Cbus. At this time, the first input terminal Vin1, the startup circuit 210, the bus capacitor Cbus, and the second input terminal Vin2 can form a loop to charge the bus capacitor Cbus, so that the bus capacitor Cbus can provide a stable input voltage, i.e., the first voltage V1, to the voltage conversion circuit 212, thereby enabling the voltage conversion circuit 212 to convert the first voltage V1 into the second voltage V2.

[0134] In some embodiments, when the first terminal Va of the DC power supply 10 shown in FIG14 is positive and the second terminal Vb of the DC power supply 10 is negative, when the start-up circuit 210 is in the conducting state, the current can flow in the direction of the arrow from the first input terminal Vin1 electrically connected to the first terminal Va to the first terminal c1 of the bus capacitor Cbus, and then from the second terminal c2 of the bus capacitor Cbus back to the second input terminal Vin2 electrically connected to the second terminal Vb.

[0135] Furthermore, continuing as shown in Figure 14, the power converter 21 may also include a reverse protection circuit 213. The reverse protection circuit 213 can be connected in parallel with the startup circuit 210. When the startup circuit 210 controls the disconnection between the input terminal of the power converter 21 and the primary-side switching circuit 2120, the reverse protection circuit 213 can be used to prevent current from the primary-side switching circuit 2120 from flowing in reverse into the input terminal of the power converter 21. For example, when a bus capacitor Cbus is connected in parallel with the input terminal of the voltage conversion circuit 212, the reverse protection circuit 213 is used to prevent current from the bus capacitor Cbus from flowing in reverse into the first input terminal Vin1.

[0136] For example, the reverse protection circuit 213 may include at least one diode to utilize the unidirectional conduction property of the diode to achieve current reverse protection. Alternatively, the reverse protection circuit 213 may be a rectifier bridge circuit, such as a full-bridge circuit or a half-bridge circuit. Or, the reverse protection circuit 213 may include at least one thyristor. Since the reverse protection circuit 213 is connected in parallel with the startup circuit 210, when the startup circuit 210 is turned on, the resistance of the startup circuit 210 may be less than the resistance of the reverse protection circuit 213. Therefore, the current from the input terminal of the power converter 21 will not, or mostly will not, pass through the reverse protection circuit 213, but will instead flow through the startup circuit 210 to the first terminal c1 of the bus capacitor Cbus.

[0137] In this way, since almost no current flows through the anti-reverse circuit 213 or only a very small current flows through it, the conduction loss of the anti-reverse circuit 213 can be reduced, thereby improving the efficiency of the power converter 21. Furthermore, because the conduction loss of the anti-reverse circuit 213 is small, there is no need to add an additional heat sink for cooling the anti-reverse circuit 213, thus improving the space utilization of the electrical equipment 20 and achieving cost savings.

[0138] In comparison, as shown in Figure 15, two diodes for current reverse protection are connected in series between the start switch 30 and the DC / DC converter 31. In this case, when the start switch 30 is on, the current flows through the series-connected diodes in the direction of the arrow. Alternatively, as shown in Figure 16, a full-bridge circuit 32 for current reverse protection is connected in series between the start switch 30 and the DC / DC converter 31. When the start switch 30 is on, the current flows through the full-bridge circuit 32. However, the conduction losses generated by the series-connected diodes or the full-bridge circuit 32 affect the efficiency of the entire circuit and generate significant heat, thus requiring an additional heat sink and increasing the size of the device. Therefore, the reverse protection circuit 213 shown in Figure 14, connected in parallel with the start circuit 210, can alleviate the problems of conduction losses and heat generated by the reverse protection circuit 213.

[0139] Furthermore, continuing as shown in Figure 14, when the startup circuit 210 is in the off state, the first input terminal Vin1 can be disconnected from the first terminal c1 of the bus capacitor Cbus. At this time, signal transmission between the first input terminal Vin1 and the first terminal c1 of the bus capacitor Cbus is impossible, and the voltage conversion circuit 212 cannot perform voltage conversion. At this time, the anti-reverse circuit 213 can prevent the discharge current from the bus capacitor Cbus from flowing counterclockwise into the first input terminal Vin1. In this situation, when at least one of the first input terminal Vin1 and the second input terminal Vin2 is de-energized, the voltage between the first input terminal Vin1 and the second input terminal Vin2 can instantaneously drop below 60V.

[0140] The following uses the structure of the power converter 21 shown in Figure 14 as an example, and combines the specific structures of the anti-reverse circuit 213 and the start-up circuit 210, to illustrate how the voltage between the first input terminal Vin1 and the second input terminal Vin2 is reduced to below 60V when at least one of the first input terminal Vin1 and the second input terminal Vin2 is powered off.

[0141] In some embodiments of this application, as shown in FIG17, the reverse current protection circuit 213 may include a first diode D1 and a second diode D2 connected in series. The anodes of the first diode D1 and the second diode D2 are electrically connected to the input terminal of the voltage conversion circuit 212, such as the first input terminal Vin1. The cathodes of the first diode D1 and the second diode D2 can be electrically connected to the primary-side switching circuit 2120 in the voltage conversion circuit 212 through the first terminal c1 of the bus capacitor Cbus, so that the first diode D1 and the second diode D2 connected in series can be connected in parallel with the starting circuit 210. By using two diodes connected in series as the reverse current protection circuit, when one diode fails, the other diode can also achieve the function of current reverse protection.

[0142] In addition, the power converter 21 may also include a second resistor R2, which may be connected in parallel with the startup circuit 210 and in series with the anti-reverse circuit 213.

[0143] For example, in the case where the anti-reverse circuit 213 includes a first diode D1 and a second diode D2 connected in series, as shown in FIG17, the second resistor R2 can be connected in series between the second diode D2 and the first terminal c1 of the bus capacitor Cbus. Alternatively, the second resistor R2 can be connected in series between the first diode D1 and the first input terminal Vin1. Or, the second resistor R2 can be connected in series between the first diode D1 and the second diode D2; this application does not limit this to any particular type.

[0144] In this situation, continuing as shown in Figure 17, when the first input terminal Vin1 and the second input terminal Vin2 of the power converter 21 are first powered on, the startup circuit 210 is not yet turned on. At this time, the current from the DC power supply 10 (as shown in Figure 14) can first pass through the first diode D1, the second diode D2, and the second resistor R2 to charge the bus capacitor Cbus. The second resistor R2 can limit the current to protect the components downstream of the second resistor R2, such as the bus capacitor Cbus and the voltage conversion circuit 212, from being damaged by overload current.

[0145] Furthermore, continuing as shown in Figure 17, the current flowing through the second resistor R2 can charge the bus capacitor Cbus. As the bus capacitor Cbus continues to charge, the voltage across the bus capacitor Cbus gradually becomes equal to the voltage between the first input terminal Vin1 and the second input terminal Vin2, i.e., the first voltage V1. At this time, as shown in Figure 18A, the startup circuit 210 is turned on, and the current provided by the DC power supply 10 shown in Figure 14 (in the direction of the arrow) can charge the bus capacitor Cbus through the startup circuit 210. This allows the bus capacitor Cbus to slowly discharge into the voltage conversion circuit 212 when it first starts working, thereby reducing the initial current flowing into the voltage conversion circuit 212 and making the startup process of the voltage conversion circuit 212 more stable.

[0146] In some embodiments of this application, the starting circuit 210 of FIG18A may include a relay 2101. The relay 2101 can be applied to applications with high current and high voltage requirements, such as power systems and high-power equipment. For example, the relay 2101 can be a reinforced insulation relay or a non-reinforced insulation relay. This application does not limit this. When the relay 2101 is a reinforced insulation relay, the distance between the main contacts of the relay 2101, such as the main contacts a1 and a2 in FIG17 or FIG18A, can be greater than or equal to a preset insulation distance to achieve reinforced insulation requirements.

[0147] For example, when relay 2101 is a reinforced insulation relay, and the first voltage V1 is approximately 380V, and the pollution level of the environment where relay 2101 is located is Class II, the preset insulation distance can be approximately 7.6mm. In this case, the distance between the main contacts a1 and a2 of the starting circuit 210, as shown in Figure 17 or Figure 18A, can be greater than or equal to 7.6mm to meet the requirements of reinforced insulation. When the first voltage V1 and the pollution level of the environment where the starting circuit 210 is located change, the preset insulation distance will also change accordingly. This application does not limit the preset insulation distance. The environmental pollution level of the relay refers to the level classified according to factors such as the type and concentration of pollutants that may exist in the relay's operating environment and their degree of impact on relay performance.

[0148] The main contacts of relay 2101 are primarily used to connect or disconnect the main circuit, and the current flowing through the main contacts is relatively large. The main contacts are typically located within the main circuit. For example, as shown in Figure 17 or Figure 18A, the main contacts a1 and a2 of the starting circuit 210 are located between the first input terminal Vin1 and the first terminal c1 of the bus capacitor Cbus. Furthermore, relay 2101 may also include control contacts a3 and a4, which can be used to control the connection or disconnection between main contacts a1 and a2. For example, when control contacts a3 and a4 are connected, a voltage is applied to the windings of relay 2101, causing main contacts a1 and a2 to connect. Conversely, when control contacts a3 and a4 are disconnected, no voltage is applied to the windings of relay 2101, causing main contacts a1 and a2 to disconnect.

[0149] When relay 2101 is a reinforced insulation relay, the probability of relay 2101 itself failing is relatively small. In this case, to ensure that relay 2101 can normally conduct or disconnect as needed, continuing as shown in Figure 17 or Figure 18A, the starting circuit 210 may further include: a third switching transistor T3 and a fourth switching transistor T4. The third switching transistor T3, the fourth switching transistor T4, and the control terminal of relay 2101 can be connected in series between the first operating voltage terminal V0 and the ground terminal GND. The first operating voltage V0 can be provided by an auxiliary power supply. The control terminal of relay 2101 may include a coil. The working principle of relay 2101 is based on electromagnetic effects. When a certain electrical signal is applied to the control terminal of relay 2101, the coil generates a magnetic field. This magnetic field will conduct or disconnect the main contacts a1 and a2, thereby achieving on / off control.

[0150] Thus, continuing as shown in Figure 17 or Figure 18A, when one of the third switching transistors T3 and the fourth switching transistor T4 (e.g., the third switching transistor T3) fails and cannot be turned on or off normally, the other transistor (e.g., the fourth switching transistor T4) can be turned on or off normally as needed, so that the relay 2101 can be turned on or off normally as needed.

[0151] In this case, since the relay 2101 in the starting circuit 210 is a reinforced insulation relay, and the circuit that controls the relay to turn on or off includes two transistors connected in series (i.e., the third switching transistor T3 and the fourth switching transistor T4), the starting circuit 210 shown in FIG17 or FIG18A can have double safety assurance to reduce the probability of the starting circuit 210 failing.

[0152] The following describes the control method of the power converter 21 with reference to the structure of the power converter 21 in Figure 17 or Figure 18A, so that when at least one of the first input terminal Vin1 and the second input terminal Vin2 is de-energized, the voltage between the first input terminal Vin1 and the second input terminal Vin2 can be reduced to below 60V.

[0153] In some embodiments of this application, the control method of the power converter 21 may include S100 and S200 as shown in FIG18B.

[0154] S100, Start-up power converter 21.

[0155] For example, as shown in Figure 18A, the power converter 21 receives a DC voltage, such as at its first input terminal Vin1 and second input terminal Vin2. Furthermore, the voltage between the input terminals of the power converter 21, such as the first input terminal Vin1 and the second input terminal Vin2, can be applied to both ends of the bus capacitor Cbus, i.e., the first terminal c1 and the second terminal c2. The voltage conversion circuit 212 receives a first voltage V1 across the bus capacitor Cbus.

[0156] S200 controls the on / off state of the transistors in the voltage conversion circuit 212.

[0157] For example, when load 22 is under heavy load, the first primary-side transistor M1 and the second primary-side transistor M2, which form the same bridge arm, are alternately turned on in the primary-side switching circuit 2120 of the voltage conversion circuit 212 shown in Figures 9 and 10. Furthermore, the first secondary-side transistor SR1 and the second secondary-side transistor SR2, which are used to rectify the positive and negative half-axis electrical signals of the second AC voltage, are alternately turned on in the secondary-side switching circuit 2121 of the voltage conversion circuit 212. The primary-side switching circuit 2120 inverts the first DC voltage received at the input terminal of the power converter 21 into a first AC voltage. The transformer circuit converts the first AC voltage into a second AC voltage and provides the second AC voltage to the secondary-side switching circuit 2121. The secondary-side switching circuit 2121 rectifies the second AC voltage into a second DC voltage and provides it to the load through the output terminal of the power converter 21. Thus, the voltage conversion circuit 212 can convert the first voltage V1 of the first DC voltage into the second voltage V2 of the second DC voltage and provide it to the output terminal Vout of the power converter.

[0158] Furthermore, when load 22 is under light load or no load, the primary-side switching circuit 2120 alternately operates in the first stage t1 and the second stage t2 as shown in Figure 8. In the first stage t1, the first primary-side transistor M1 and the second primary-side transistor M2 are alternately turned on. In the second stage t2, the first primary-side transistor M1 and the second primary-side transistor M2, as shown in Figures 11 and 12, are turned off. Also, when load 22 is under light load or no load, the first secondary-side transistor SR1 and the second secondary-side transistor SR2 are alternately turned on to generate a reverse current on the side where the primary winding of the voltage conversion circuit 212 is located.

[0159] As described above, when at least one of the input terminals of the power converter 21, such as the first input terminal Vin1 and the second input terminal Vin2, is powered off (i.e., when at least one of the first input terminal Vin1 and the second input terminal Vin2 does not receive DC power from the DC power supply 10), both the primary-side switching circuit 2120 and the secondary-side switching circuit 2121 of the voltage conversion circuit 212 experience losses, causing the bus capacitor Cbus to discharge at an increased rate. Based on this, since the probability of failure of the startup circuit 210 shown in Figure 17 or Figure 18A is relatively small, when the startup circuit 210, the first diode D1 and the second diode D2 in the anti-reverse circuit 213, and the voltage conversion circuit 212 are all functioning correctly, as shown in Figure 19, the input voltage Vin, i.e., the voltage between the first input terminal Vin1 and the second input terminal Vin2 in Figure 17, can gradually decrease from the first voltage V1, for example, around 380V, within 2 seconds.

[0160] Based on this, after the bus capacitor Cbus discharges, the control method may further include: if the voltage across the bus capacitor Cbus discharges to the undervoltage voltage Vbus_L shown in Figure 19, then the starting circuit 210, electrically connected between the first input terminal Vin1 shown in Figure 18A and the first terminal c1 of the bus capacitor Cbus, can control the input terminal of the power converter 21 to disconnect from the bus capacitor Cbus, for example, controlling the first input terminal Vin1 to disconnect from the first terminal c1 of the bus capacitor Cbus. The undervoltage voltage Vbus_L can be less than 60V, and this application does not limit the specific value of the undervoltage voltage Vbus_L.

[0161] Therefore, since the startup circuit 210 disconnects the first input terminal Vin1 from the first terminal c1 of the bus capacitor Cbus, when at least one of the first input terminals Vin1 and Vin2 is powered off, the current from the bus capacitor Cbus will not flow back into the first input terminal Vin1 through the startup circuit 210. Furthermore, the anti-reverse circuit 213, connected in parallel with the startup circuit 210, can prevent the current from the bus capacitor Cbus from flowing back into the first input terminal Vin1.

[0162] For example, since the two series-connected diodes D1 and D2 in the anti-reverse circuit 213 are in a non-faulty state, they can prevent the current from the bus capacitor Cbus from flowing from the cathode of the first diode D1 (or the second diode D2) to the anode of the first diode D1 (i.e., from the right end to the left end). This, in turn, prevents the current from the bus capacitor Cbus from flowing in reverse into the first input terminal Vin1. At this time, the input voltage Vin between the first input terminal Vin1 and the second input terminal Vin2, as shown in Figure 19, can be reduced from the undervoltage voltage Vbus_L to below 60V within 2 seconds to meet the safety discharge requirements.

[0163] Furthermore, after the startup circuit 210 disconnects the first input terminal Vin1 from the first terminal c1 of the bus capacitor Cbus, the first secondary transistor SR1 and the second secondary transistor SR2 shown in FIG11 or FIG12 are controlled to be in the off state.

[0164] In summary, if at least one of the first input terminal Vin1 and the second input terminal Vin2 is powered down, the first secondary transistor SR1 and the second secondary transistor SR2 can be alternately turned on via S200. This utilizes the inherent losses of the primary-side switching circuit 2120 and the secondary-side switching circuit 2121 of the voltage conversion circuit 212 to increase the discharge rate of the bus capacitor Cbus, thereby shortening the rate at which the input voltage Vin drops. For example, this allows the input voltage Vin to drop from the first voltage V1, for example, around 380V, to the undervoltage voltage Vbus_L or below it in a shorter time.

[0165] When the input voltage Vin drops to the undervoltage voltage Vbus_L, that is, when the input voltage Vin is equal to the undervoltage voltage Vbus_L, the voltage conversion circuit 212 can trigger the shutdown procedure, for example, by controlling the start-up circuit 210 to disconnect the first input terminal Vin1 from the first terminal c1 of the bus capacitor Cbus.

[0166] Specifically, the larger the duty cycle of the first secondary-side switch control signal S21 (or the second secondary-side switch control signal S22) controlling the first secondary-side transistor SR1 (or the second secondary-side transistor SR2), the steeper the slope of the input voltage Vin shown in Figure 19. For example, the steeper the slope of the input voltage Vin between the first voltage V1 and the undervoltage Vbus_L, the faster the discharge speed at the input terminal of the power converter 21, and the greater the power consumption. Conversely, the smaller the duty cycle of the first secondary-side switch control signal S21 or the second secondary-side switch control signal S22, the shallower the slope of the input voltage Vin, the slower the discharge speed, and the lower the power consumption.

[0167] Based on this, the start-up circuit 210 can be controlled to disconnect the first input terminal Vin1 from the first terminal c1 of the bus capacitor Cbus. At this time, the anti-reverse circuit 213 can further reduce the input voltage Vin from the undervoltage voltage Vbus_L to below 60V within 2 seconds to meet the safety discharge requirements.

[0168] The above is an example illustrating that, under the condition that at least one of the first input terminal Vin1 and the second input terminal Vin2 is powered off, the first diode D1 and the second diode D2 in the startup circuit 210, the anti-reverse circuit 213, and the voltage conversion circuit 212 shown in FIG17 or FIG18A do not malfunction.

[0169] In other embodiments of this application, when at least one of the first input terminal Vin1 and the second input terminal Vin2 is powered off, if one of the diodes in the anti-reverse circuit 213 shown in FIG. 17 or FIG. 18A, such as the first diode D1 or the second diode D2, fails and cannot prevent the current from the bus capacitor Cbus from flowing back into the first input terminal Vin1, the other diode, such as the second diode D2 or the first diode D1, can be in normal working condition to prevent the current from the bus capacitor Cbus from flowing back into the first input terminal Vin1. Therefore, after the input terminal is powered off, the input voltage Vin, that is, the voltage between the first input terminal Vin1 and the second input terminal Vin2 in FIG. 17, can still drop to below 60V within 2s, as shown in FIG. 19.

[0170] Alternatively, in some embodiments, if neither the first diode D1 nor the second diode D2 in the startup circuit 210 and the anti-reverse circuit 213 shown in FIG. 17 fails, and at least one of the first input terminal Vin1 and the second input terminal Vin2 is de-energized, then if the voltage conversion circuit 212 fails, the voltage conversion circuit 212 will be unable to provide the converted second voltage V2 to the output terminal Vout. Based on this, after the bus capacitor Cbus is discharged, the control method may further include: as shown in FIG. 17, the startup circuit 210, electrically connected between the first input terminal Vin1 and the first terminal c1 of the bus capacitor Cbus, controls the first input terminal Vin1 to disconnect from the first terminal c1 of the bus capacitor Cbus.

[0171] For example, during the operation of the power converter 21, the output voltage of the voltage conversion circuit 212 can be detected. For instance, if the output voltage of the voltage conversion circuit 212 is a fault voltage V_F, it indicates that the voltage conversion circuit 212 has malfunctioned. The fault voltage V_F can have a certain difference from the second voltage V2 converted by the voltage conversion circuit 212, so that when the voltage conversion circuit 212 outputs the fault voltage V_F, it can be determined that the voltage conversion circuit 212 cannot output the second voltage V2.

[0172] For example, the voltage when the voltage conversion circuit 212 malfunctions can be the fault voltage V_F. Since the voltage conversion circuit 212 will trigger a shutdown procedure when it reaches the undervoltage voltage Vbus_L, there is no need to detect whether the voltage conversion circuit 212 has malfunctioned. Therefore, the fault voltage V_F can be greater than the undervoltage voltage Vbus_L. This application does not limit the magnitude of the fault voltage V_F. For example, the faults occurring in the voltage conversion circuit 212 can include undervoltage faults, overvoltage faults, short-circuit faults, or overtemperature faults.

[0173] In this situation, after at least one of the first input terminals Vin1 and Vin2 loses power, the first secondary transistor SR1 and the second secondary transistor SR2 can be alternately turned on via S200 to increase the discharge speed of the bus capacitor Cbus. As shown in Figure 20, this allows the input voltage Vin, i.e., the voltage between the first input terminals Vin1 and Vin2 as shown in Figure 17, to decrease from the first voltage V1 (e.g., around 380V) to the fault voltage V_F within 2 seconds. If the voltage conversion circuit 212 fails, the starting circuit 210 can disconnect the first input terminal Vin1 from the first terminal c1 of the bus capacitor Cbus. At this time, the anti-reverse circuit 213 can reduce the input voltage Vin from the fault voltage V_F to below 60V within 2 seconds to meet safety discharge requirements.

[0174] The above description uses the anti-reverse circuit 213 shown in Figure 17 or Figure 18A, which includes two diodes connected in series, such as the first diode D1 and the second diode D2. In other embodiments of this application, the anti-reverse circuit 213 may also include three or more diodes, and this application does not limit this.

[0175] It should be noted that in the anti-reverse circuit 213 provided in this application embodiment, the anti-reverse circuit only uses two series-connected diodes to achieve the current anti-reverse effect between the input terminal of the power converter 21 and the bus capacitor Cbus, but it does not limit the specific implementation structure of the anti-reverse circuit 213 provided in this application embodiment to this. In other embodiments of this application, the types of functional components included in the anti-reverse circuit 213, the connection method and layout position of the functional components, and the number of functional components can all be adjusted according to actual design requirements and the actual application scenario of the power converter 21, etc., and this application embodiment does not make specific limitations in this regard.

[0176] For example, as shown in Figure 21, the anti-reverse circuit 213 may include a full-bridge circuit mainly composed of four diodes. These four diodes may be a first diode D1, a second diode D2, a third diode D3, and a fourth diode D4. The anodes of the first diode D1 and the third diode D3 are electrically connected to the second input terminal Vin2. The cathodes of the second diode D2 and the fourth diode D4 are electrically connected to the first input terminal Vin. The cathodes of the first diode D1 and the anodes of the second diode D2 are electrically connected to the first input terminal Vin. The cathodes of the third diode D3 and the anodes of the fourth diode D4 are electrically connected to the second input terminal Vin2.

[0177] Specifically, the first input terminal Vin1, the second diode D2, the bus capacitor Cbus, the third diode D3, and the second input terminal Vin2 can form a current loop, allowing electrical energy from the first input terminal Vin1 and the second input terminal Vint2 to be transferred to the bus capacitor Cbus through this loop. Furthermore, the second input terminal Vin2, the fourth diode D4, the bus capacitor Cbus, and the first diode D1 can form a current loop, allowing electrical energy from the first input terminal Vin1 and the second input terminal Vint2 to be transferred to the bus capacitor Cbus through this loop.

[0178] Furthermore, the unidirectional conductivity of the first diode D1, second diode D2, third diode D3, and fourth diode D4 can be used to achieve current reverse protection between the input terminal of the power converter 21 and the bus capacitor Cbus. For example, the current from the first terminal c1 of the bus capacitor Cbus cannot flow into the second input terminal Vin2 through the fourth diode D4, and the same current cannot flow into the first input terminal Vin1 through the second diode D2, thus achieving current reverse protection.

[0179] Alternatively, the reverse current protection circuit 213 may include a half-bridge circuit mainly composed of two diodes. This half-bridge reverse current protection circuit may include two diodes. The anode of one diode is electrically connected to the first input terminal Vin1, and the cathode is electrically connected to the first terminal c1 of the bus capacitor Cbus. The cathode of the other diode is electrically connected to the second input terminal Vin2, and the anode is electrically connected to the second terminal c2 of the bus capacitor Cbus. The reverse current protection effect of the half-bridge circuit is the same as that of the full-bridge circuit, and will not be elaborated further here. Alternatively, the reverse current protection circuit 213 may also include a thyristor with unidirectional conduction. The anode of the thyristor is electrically connected to the first input terminal Vin1, and the cathode is electrically connected to the first terminal c1 of the bus capacitor Cbus, achieving the effect of reverse current protection. For ease of explanation, the following examples all assume that the reverse current protection circuit 213 includes at least one diode.

[0180] For example, as shown in FIG22, the reverse current protection circuit 213 may include a diode, namely a first diode D1. The anode of the first diode D1 is electrically connected to the input terminal of the power converter 21, such as the first input terminal Vin1, and the cathode of the first diode D1 is electrically connected to the voltage conversion circuit 212 through the first terminal c1 of the bus capacitor Cbus. In this way, the unidirectional conduction performance of a diode can be used to achieve reverse current protection, thereby simplifying the circuit. In addition, the structure of the startup circuit 210 can be the same as that shown in FIG17. Alternatively, as shown in FIG22, the startup circuit 210 may include a non-reinforced insulation relay 2101 and a switching transistor T0 for controlling the relay 2101 to turn on or off.

[0181] For example, continuing as shown in Figure 22, the power converter 21 may further include a first resistor R1 and a first switching transistor T1. The first switching transistor T1 and the first resistor R1 are connected in series between the first terminal c1 and the second terminal c2 of the bus capacitor Cbus. The control method of the power converter 21 shown in Figure 22 may include S200 and S200, which will not be described in detail here.

[0182] Based on this, continuing as shown in Figure 22, assuming no faults occur in the first diode D1 of the startup circuit 210, the anti-reverse circuit 213, or the voltage conversion circuit 212, when at least one of the first input terminal Vin1 and the second input terminal Vin2 loses power, S200 can be used to control the alternating conduction of the first secondary transistor SR1 and the second secondary transistor SR2, increasing the discharge speed across the bus capacitor Cbus. Thus, as shown in Figure 23, the input voltage Vin, i.e., the voltage between the first input terminal Vin1 and the second input terminal Vin2 in Figure 22, can be reduced from the first voltage V1 (e.g., approximately 380V) to the undervoltage voltage Vbus_L within 2 seconds.

[0183] Based on this, the starting circuit 210 can be controlled to disconnect the first input terminal Vin1 from the first terminal c1 of the bus capacitor Cbus. At this time, the anti-reverse circuit 213 can continue to reduce the input voltage Vin from the undervoltage voltage Vbus_L to below 60V within 2 seconds, as shown in Figure 23, to meet the safety discharge requirements. Since the structure of the power converter 21 shown in Figure 22 is different from that shown in Figure 17, the slope of the input voltage Vin shown in Figure 23 between the first voltage V1 and the undervoltage voltage Vbus_L may be different from the slope of the input voltage Vin shown in Figure 19. The slope is related to the duty cycle of the first secondary-side switch control signal S21 or the second secondary-side switch control signal S22.

[0184] Furthermore, in some other embodiments of this application, when at least one of the first input terminal Vin1 and the second input terminal Vin2 is powered off, if the first diode D1 in the anti-reverse circuit 213 shown in FIG22 fails and cannot prevent the current from the bus capacitor Cbus from flowing back into the first input terminal Vin1, the current from the bus capacitor Cbus shown in FIG22 can flow back into the first input terminal Vin1 through the anti-reverse circuit 213 connected in parallel with the startup circuit 210 when the startup circuit 210 is disconnected.

[0185] Based on this, after the bus capacitor Cbus discharges, the control method further includes: if the voltage across the bus capacitor Cbus discharges to the undervoltage voltage Vbus_L, then the first switching transistor T1 shown in Figure 24 is turned on, and the first resistor R1, which is connected in series with the first switching transistor T1, is electrically connected between the first terminal c1 and the second terminal c2 of the bus capacitor Cbus. At this time, the current from the bus capacitor Cbus can flow through the first resistor R1 in the direction of the arrow. Therefore, the first resistor R1 can form a discharge path in parallel with the bus capacitor Cbus. In this way, under the combined discharge action of the first resistor R1 and the bus capacitor Cbus, as shown in Figure 25, the input voltage Vin can be further reduced from the undervoltage voltage Vbus_L to below 60V within 2 seconds to meet the safety discharge requirements. In Figure 23, the slope of the input voltage Vin between the first voltage V1 and the undervoltage voltage Vbus_L is the same as the slope of the input voltage Vin shown in Figure 25, so that the input voltage Vin can continue to decrease from the undervoltage voltage Vbus_L to below 60V within 2 seconds. When the input voltage Vin decreases to the undervoltage voltage Vbus_L, the voltage conversion circuit 212 can trigger the shutdown procedure.

[0186] Alternatively, in some other embodiments, if neither the startup circuit 210 nor the anti-reverse circuit 213 shown in FIG22 malfunctions, and at least one of the first input terminal Vin1 and the second input terminal Vin2 is powered off, then similarly, S200 can be used to control the first secondary transistor SR1 and the second secondary transistor SR2 to conduct alternately, so that, as shown in FIG26, the input voltage Vin, that is, the voltage between the first input terminal Vin1 and the second input terminal Vin2 in FIG22, is gradually reduced within 2s.

[0187] Furthermore, if the voltage conversion circuit 212 malfunctions and cannot provide the converted second voltage V2 to the output terminal Vout, the input voltage Vin can be reduced from the first voltage V1, for example, around 380V, to the fault voltage V_F. Additionally, the control startup circuit 210 disconnects the first input terminal Vin1 from the first terminal c1 of the bus capacitor Cbus. At this time, the anti-reverse circuit 213 can reduce the input voltage Vin from the fault voltage V_F to below 60V within 2 seconds to meet safety discharge requirements. The slope of the input voltage Vin between the first voltage V1 and the fault voltage V_F shown in Figure 26 is the same as the slope of the input voltage Vin between the first voltage V1 and the undervoltage voltage Vbus_L shown in Figure 25.

[0188] The above example illustrates the starting circuit 210, which includes a relay 2101. In other embodiments of this application, as shown in FIG27, the starting circuit 210 may include a second switching transistor T2. Thus, by controlling the on or off state of the second transistor T2, the starting circuit 210 can be turned on or off.

[0189] As described above, Figure 17 illustrates an example where the anti-reverse circuit 213 includes two diodes connected in series, and Figure 22 illustrates an example where the anti-reverse circuit 213 includes one diode, and the power converter 21 also includes a first resistor R1 and a first switching transistor T1. Alternatively, in some embodiments of this application, as shown in Figure 28, the anti-reverse circuit 213 may include a first diode D1, and the power converter 21 may not include a first resistor R1 and a first switching transistor T1. Furthermore, the startup circuit 210 may include a relay 2101, or the startup circuit 210 may include a second switching transistor T2 (as shown in Figure 27).

[0190] Based on this, continuing as shown in Figure 28, assuming no faults occur in the first diode D1 of the startup circuit 210, the anti-reverse circuit 213, or the voltage conversion circuit 212, when at least one of the first input terminal Vin1 and the second input terminal Vin2 loses power, S200 can be used to control the alternating conduction of the first secondary transistor SR1 and the second secondary transistor SR2, increasing the discharge speed across the bus capacitor Cbus. Thus, as shown in Figure 29, the input voltage Vin, i.e., the voltage between the first input terminal Vin1 and the second input terminal Vin2 in Figure 28, can be reduced from the first voltage V1, for example, around 380V, to the undervoltage voltage Vbus_L within 2 seconds.

[0191] Based on this, the start-up circuit 210 can be controlled to disconnect the first input terminal Vin1 from the first terminal c1 of the bus capacitor Cbus. At this time, the anti-reverse circuit 213 can continue to reduce the input voltage Vin from the undervoltage voltage Vbus_L to below 60V within 2 seconds, as shown in Figure 29, to meet the safety discharge requirements. Note that since the structure of the power converter 21 shown in Figure 28 is different from that shown in Figures 17 and 22, the slope of the input voltage Vin shown in Figure 29 between the first voltage V1 and the undervoltage voltage Vbus_L may differ from the slope of the input voltage Vin shown in Figures 19 or 23.

[0192] Furthermore, if at least one of the first input terminal Vin1 and the second input terminal Vin2 is powered off, and the first diode D1 in the anti-reverse circuit 213 shown in Figure 28 fails and cannot prevent the current from the bus capacitor Cbus from flowing back into the first input terminal Vin1, then the current from the bus capacitor Cbus can flow back into the first input terminal Vin1 through the anti-reverse circuit 213 connected in parallel with the startup circuit 210. Based on this, after the bus capacitor Cbus is discharged, the control method further includes: controlling the first secondary transistor SR1 and the second secondary transistor SR2 to conduct alternately, thereby continuing to utilize the losses inherent in the primary-side switching circuit 2120 and the secondary-side switching circuit 2121 of the voltage conversion circuit 212 to increase the discharge speed of the bus capacitor Cbus, thereby shortening the voltage drop rate of the input voltage Vin. For example, as shown in Figure 30, this allows the input voltage Vin to continue to decrease from the undervoltage voltage Vbus_L to below 60V within a short time, for example, within 2 seconds, to meet the safety discharge requirements.

[0193] The slope of the input voltage Vin shown in Figure 30 between the first voltage V1 and the undervoltage voltage Vbus_L is the same as the slope of the input voltage Vin shown in Figure 29, so that the input voltage Vin can be further reduced from the undervoltage voltage Vbus_L to below 60V within 2s.

[0194] Alternatively, in some embodiments, if neither the startup circuit 210 nor the anti-reverse circuit 213 shown in FIG28 malfunctions, and at least one of the first input terminal Vin1 and the second input terminal Vin2 is powered off, the first secondary transistor SR1 and the second secondary transistor SR2 can be alternately turned on via S200, so that the input voltage Vin, i.e., the voltage between the first input terminal Vin1 and the second input terminal Vin2 in FIG22, is gradually reduced within 2 seconds, as shown in FIG31. If the voltage conversion circuit 212 malfunctions and cannot provide the converted second voltage V2 to the output terminal Vout, the input voltage Vin can be reduced from the first voltage V1, for example, around 380V, to the fault voltage V_F.

[0195] Then, the start-up circuit 210 can be controlled to disconnect the first input terminal Vin1 from the first terminal c1 of the bus capacitor Cbus. At this time, as shown in Figure 31, the anti-reverse circuit 213 can further reduce the input voltage Vin from the fault voltage V_F to below 60V within 2 seconds to meet the safety discharge requirements. The slope of the input voltage Vin between the first voltage V1 and the fault voltage V_F shown in Figure 31 is the same as the slope of the input voltage Vin between the first voltage V1 and the undervoltage voltage Vbus_L shown in Figure 30.

[0196] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any changes or substitutions within the technical scope disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A power converter, characterized in that, The power converter includes: The power converter includes a primary-side switching circuit, a secondary-side switching circuit, and a transformer circuit. The primary-side switching circuit is used to invert a first DC voltage received at the input terminal of the power converter into a first AC voltage. The transformer circuit is used to convert the first AC voltage into a second AC voltage and to provide the second AC voltage to the secondary-side switching circuit. The secondary-side switching circuit is a full-bridge circuit or a full-wave circuit. The secondary-side switching circuit includes a first secondary-side transistor and a second secondary-side transistor. The first secondary-side transistor and the second secondary-side transistor are electrically connected between the secondary winding of the transformer circuit and the output terminal of the power converter. The first secondary-side transistor and the second secondary-side transistor are respectively used to rectify the second AC voltage into a second DC voltage and provide it to the load through the output terminal of the power converter. The second DC voltage is different from the first DC voltage. The first secondary-side transistor and the second secondary-side transistor are turned on alternately.

2. The power converter according to claim 1, characterized in that, The output terminals of the power converter include a first output terminal and a second output terminal; the secondary switching circuit is a full-wave circuit; the secondary winding of the transformer circuit includes a first secondary winding and a second secondary winding. The first secondary transistor and the first secondary winding are connected in series between the first output terminal and the second output terminal; The second secondary transistor and the second secondary winding are connected in series between the first output terminal and the second output terminal.

3. The power converter according to claim 1, characterized in that, The power converter's output terminals include a first output terminal and a second output terminal; the secondary-side switching circuit is a full-bridge circuit; the secondary-side switching circuit also includes a third secondary-side transistor and a fourth secondary-side transistor; The first secondary transistor, the secondary winding, and the fourth secondary transistor are connected in series between the first output terminal and the second output terminal. The third secondary transistor, the secondary winding, and the second secondary transistor are connected in series between the first output terminal and the second output terminal. Wherein, the first secondary-side transistor and the second secondary-side transistor form the first bridge arm, and the third secondary-side transistor and the fourth secondary-side transistor form the second bridge arm; the third secondary-side transistor and the fourth secondary-side transistor are turned on alternately.

4. The power converter according to any one of claims 1-3, characterized in that, The power converter also includes a startup circuit and a reverse protection circuit. The reverse protection circuit is connected in parallel with the startup circuit. The startup circuit is used to control the connection or disconnection between the input terminal of the power converter and the primary-side switching circuit. When the startup circuit controls the disconnection between the input terminal of the power converter and the primary-side switching circuit, the anti-reverse circuit is used to prevent the current in the primary-side switching circuit from flowing back into the input terminal of the power converter.

5. The power converter according to claim 4, characterized in that, The anti-reverse circuit includes a first diode; the anode of the first diode is electrically connected to the input terminal of the power converter, and the cathode of the first diode is electrically connected to the primary-side switching circuit.

6. The power converter according to claim 4, characterized in that, The power converter has a first input terminal and a second input terminal; the anti-reverse circuit includes a first diode, a second diode, a third diode, and a fourth diode. The anodes of the first diode and the third diode are electrically connected to the second input terminal; The cathodes of the second diode and the fourth diode are electrically connected to the first input terminal; The cathode of the first diode and the anode of the second diode are electrically connected to the first input terminal; The cathode of the third diode and the anode of the fourth diode are electrically connected to the second input terminal.

7. The power converter according to any one of claims 2 or 4-6, characterized in that, The primary-side switching circuit includes a first primary-side transistor and a second primary-side transistor forming the same bridge arm; the primary-side switching circuit alternately operates in the first stage and the second stage. In the first stage, the first primary-side transistor and the second primary-side transistor are turned on alternately; the turn-on time of the first primary-side transistor and the turn-on time of the second secondary-side transistor at least partially overlap; the turn-on time of the second primary-side transistor and the turn-on time of the first secondary-side transistor at least partially overlap. In the second stage, the first primary-side transistor and the second primary-side transistor are in the off state.

8. The power converter according to any one of claims 3 or 4-6, characterized in that, The primary-side switching circuit includes a first primary-side transistor and a second primary-side transistor forming the same bridge arm; the primary-side switching circuit alternately operates in the first stage and the second stage. In the first stage, the first primary-side transistor and the second primary-side transistor are turned on alternately; the turn-on time of the first primary-side transistor overlaps at least partially with the turn-on time of the second secondary-side transistor and the third secondary-side transistor; the turn-on time of the second primary-side transistor overlaps at least partially with the turn-on time of the first secondary-side transistor and the fourth secondary-side transistor. In the second stage, the first primary-side transistor and the second primary-side transistor are in the off state.

9. The power converter according to any one of claims 1-8, characterized in that, The power converter includes a first input terminal and a second input terminal; the power converter also includes: A bus capacitor, wherein the first and second ends of the bus capacitor are electrically connected to the first input terminal and the second input terminal, respectively; First resistor; A first switching transistor; the first switching transistor and the first resistor are connected in series between the first and second terminals of the bus capacitor.

10. The power converter according to any one of claims 1-9, characterized in that, The power converter includes a startup circuit and an anti-reverse circuit, wherein the anti-reverse circuit is connected in parallel with the startup circuit. The power converter further includes: a second resistor connected in parallel with the startup circuit; the second resistor being connected in series with the anti-reverse circuit.

11. The power converter according to claim 10, characterized in that, The power converter includes a first input terminal and a second input terminal; the power converter also includes a bus capacitor, the first terminal and the second terminal of which are electrically connected to the first input terminal and the second input terminal, respectively. The startup circuit is electrically connected to the first input terminal and the first terminal of the bus capacitor.

12. The power converter according to claim 11, characterized in that, The power converter also has a first operating voltage terminal and a ground terminal; the starting circuit includes a relay, the two main contacts of which are electrically connected to the first input terminal and the first terminal of the bus capacitor, respectively. The distance between the two main contacts of the relay is greater than or equal to the preset insulation distance; The startup circuit also includes: Third switching transistor; The fourth switching transistor; the control terminal of the third switching transistor, the fourth switching transistor, and the relay are connected in series between the first operating voltage terminal and the ground terminal.

13. An electrical appliance, characterized in that, include: load; The power converter according to any one of claims 1-12, wherein the output terminal of the power converter is electrically connected to the load.

14. A power supply system, characterized in that, include: High-voltage DC power supply; The electrical equipment as described in claim 13, wherein the high-voltage DC power supply is electrically connected to the first input terminal and the second output terminal of the power converter in the electrical equipment.

15. A control method for a power converter, characterized in that, include: Receive DC voltage; The voltage at the input terminal of the power converter is applied to both ends of the bus capacitor; The primary-side switching circuit receives a first voltage across the bus capacitor; controls the first primary-side transistor and the second primary-side transistor forming the same bridge arm in the primary-side switching circuit to conduct alternately; or, the primary-side switching circuit alternately operates in a first stage and a second stage; in the first stage, controls the first primary-side transistor and the second primary-side transistor to conduct alternately. In the second stage, the first primary-side transistor and the second primary-side transistor are controlled to be in the off state; the primary-side switching circuit inverts the first DC voltage received at the input terminal of the power converter into a first AC voltage; The transformer circuit converts the first AC voltage into a second AC voltage and provides the second AC voltage to the secondary-side switching circuit; In the secondary-side switching circuit, the first secondary-side transistor and the second secondary-side transistor, which are used to rectify the second AC voltage, are alternately turned on; the secondary-side switching circuit rectifies the second AC voltage into a second DC voltage and provides it to the load through the output terminal of the power converter; the first DC voltage and the second DC voltage are different. If the input terminal of the power converter does not receive DC voltage, the two ends of the bus capacitor will discharge.

16. The control method according to claim 15, characterized in that, After the bus capacitor is discharged, the control method further includes: If the voltage across the bus capacitor discharges to an undervoltage level, a start-up circuit electrically connected between the input terminal of the power converter and the bus capacitor is activated to disconnect the input terminal of the power converter from the bus capacitor. A reverse current protection circuit connected in parallel with the startup circuit prevents current from the bus capacitor from flowing in reverse into the input terminal of the power converter.

17. The control method according to claim 15, characterized in that, The current from the bus capacitor flows in reverse through an anti-reverse circuit connected in parallel with the startup circuit into the input terminal of the power converter; after the bus capacitor is discharged, the control method further includes: If the voltage across the bus capacitor discharges to an undervoltage level, the first switching transistor is turned on, and a first resistor connected in series with the first switching transistor is electrically connected between the first and second terminals of the bus capacitor; the current from the bus capacitor flows through the first resistor.

18. The control method according to claim 15, characterized in that, The current from the bus capacitor flows in reverse through an anti-reverse circuit connected in parallel with the startup circuit into the input terminal of the power converter; after the bus capacitor is discharged, the control method further includes: The first secondary transistor and the second secondary transistor are controlled to conduct alternately.

19. The control method according to any one of claims 15-18, characterized in that, If the output terminal of the power converter cannot output the second DC voltage, after the two ends of the bus capacitor are discharged, the control method further includes: A startup circuit electrically connected between the input terminal of the power converter and the bus capacitor controls the disconnection between the input terminal of the power converter and the bus capacitor.

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