Drive circuit, switching circuit, and power conversion circuit for power device

Abstract

This application provides a driving circuit, a switching circuit, and a power conversion circuit for power devices. The driving circuit controls the switching operations of N power devices connected in parallel, where N ≥ 2 and is a positive integer. The driving circuit includes a driving input circuit and a common ferrite bead. The first terminal of the driving input circuit is electrically connected to the N first terminals of the common ferrite bead, and the N second terminals of the common ferrite bead are electrically connected to the control terminals of the N power devices. The second terminal of the driving input circuit is electrically connected to the second terminals of the N power devices. By using a common ferrite bead in the driving circuit, the parasitic inductance generated by the common ferrite bead is the same, making the impedance characteristics of the driving circuits corresponding to the parallel power devices more similar, thereby effectively reducing the switching losses and damage risks generated by the power devices during the switching process.

Description

Technical Field

[0001] This application relates to the field of power device driving technology, and in particular to a power device driving circuit, switching circuit and power conversion circuit. Background Technology

[0002] To improve the output of power conversion circuits, a common method is to connect power devices in parallel. Steady-state and dynamic current sharing are prerequisites for the safe operation of power devices. Due to differences in the parameters of the drive circuits and the switching characteristics of the power devices, the switching times of parallel-connected power devices differ. Power devices that turn on earlier bear a larger turn-on current, while those that turn off later bear a larger turn-off current. This increases the switching losses of the power devices, posing a risk of overheating or even damage.

[0003] Therefore, it is necessary to develop a driving circuit, switching circuit, and power conversion circuit for power devices to solve the problems faced by the prior art. Summary of the Invention

[0004] The purpose of this invention is to provide a driving circuit, switching circuit, and power conversion circuit for power devices, which can reduce the risk of overheating or damage to power devices.

[0005] In a first aspect, this application provides a driving circuit for power devices. The driving circuit is used to control the switching action of N power devices, where N≥2 and is a positive integer. Each power device has a first terminal, a second terminal, and a control terminal. The first terminals of the N power devices are electrically connected to a first node, and the second terminals of the N power devices are electrically connected to a second node. The driving circuit includes a driving input circuit and a common ferrite bead. The driving input circuit has a first terminal and a second terminal, and the common ferrite bead has N first terminals and N second terminals. The first terminal of the driving input circuit is electrically connected to the N first terminals of the common ferrite bead, and the N second terminals of the common ferrite bead are electrically connected to the control terminals of the N power devices in a one-to-one correspondence. The second terminal of the driving input circuit is electrically connected to the second terminals of the N power devices.

[0006] In a second aspect, this application provides a switching circuit, including the driving circuit involved in the first aspect and optional solutions and N power devices, wherein N≥2 and is a positive integer; wherein the driving circuit is used to control the switching action of the N power devices; the first ends of the N power devices are electrically connected to a first node to form the first end of the switching circuit, and the second ends of the N power devices are electrically connected to a second node to form the second end of the switching circuit.

[0007] Thirdly, this application provides a power conversion circuit, including an input capacitor, a first switching circuit, and a second switching circuit, both of which are the switching circuits involved in the second aspect; wherein, a first terminal of the first switching circuit is electrically connected to a first terminal of the input capacitor, a second terminal of the first switching circuit is electrically connected to a first terminal of the second switching circuit, and a second terminal of the second switching circuit is electrically connected to a second terminal of the input capacitor. Attached Figure Description

[0008] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0009] Figure 1 This is a schematic diagram of the structure of a driving circuit provided in an embodiment of this application;

[0010] Figure 2A This is a schematic diagram of a driving circuit provided in an embodiment of the present application, which shows a first structure of the driving input circuit;

[0011] Figure 2B This is a schematic diagram of a driving circuit provided in an embodiment of the present application, which shows a second structure of the driving input circuit;

[0012] Figure 2C This is a schematic diagram of a driving circuit provided in an embodiment of the present application, which shows a third structure of the driving input circuit;

[0013] Figure 3 This is a schematic diagram of the structure of a half-bridge circuit provided in an embodiment of this application.

[0014] The accompanying drawings have illustrated specific embodiments of this application, which will be described in more detail below. These drawings and descriptions are not intended to limit the scope of the concept in any way, but rather to illustrate the concept of this application to those skilled in the art through reference to specific embodiments. Detailed Implementation

[0015] Exemplary embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings. When the following description relates to the drawings, unless otherwise indicated, the same numbers in different drawings denote the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with this application. Rather, they are merely examples of apparatuses and methods consistent with some aspects of this application as detailed in the appended claims.

[0016] The drive circuit of a power device controls its on / off state. Connecting multiple power devices in parallel is one way to increase their output power. However, steady-state and dynamic current sharing are prerequisites for the safe operation of power devices; that is, the current difference between the power devices must be kept within a small range. Due to differences in the parameters of the drive circuit (including parasitic parameters) and the switching characteristics of the power devices, the switching times of parallel power devices differ. Power devices that turn on earlier bear a larger turn-on current, while those that turn off later bear a larger turn-off current, thus increasing switching losses and posing a risk of overheating or even damage. To achieve good current sharing characteristics, the drive circuit parameters of parallel power devices must have small tolerances, and the circuit wiring should be as symmetrical and consistent as possible, limiting the driving differences to a very small range.

[0017] Taking parallel operation of MOSFETs as an example, the control terminal of the MOSFETs is driven by a transformer, and the secondary winding of the transformer provides an isolated, negatively charged drive voltage. During the switching process of the MOSFETs, very high voltage change rate (dv / dt) stress and current change rate (di / dt) stress are generated. Furthermore, due to the parasitic capacitance of the MOSFETs and the parasitic inductance of the drive circuit, high-frequency oscillations occur at the control terminal. This oscillation may cause overvoltage or false turn-on at the control terminal, and in severe cases, damage to the power devices.

[0018] To suppress high-frequency oscillations at the control terminal, a ferrite bead is typically added to the control terminal of each MOSFET. The inductance and resistance of the ferrite bead vary with the current frequency. As the frequency increases, for example from low frequencies to tens of megahertz, the inductance of the ferrite bead decreases from hundreds of nH to a few nH. As the frequency increases further, the resistance of the ferrite bead increases from milliohms to tens of ohms, or even hundreds of ohms. When the frequency is further increased to hundreds of megahertz, the ferrite bead exhibits capacitive behavior. The characteristic curves of the resistance and inductance of the ferrite bead as a function of frequency depend on the core material, and a suitable core material can be selected according to requirements. In one embodiment, the core material is ferrite.

[0019] At high frequencies, a ferrite bead can be equivalent to a large resistor, with negligible inductance, effectively reducing the current amplitude when power devices generate high-frequency oscillations. At low frequencies, a ferrite bead is equivalent to an inductor and a very small resistor, having minimal impact on the delay of the control signal. Therefore, selecting a ferrite bead with low inductance and high resistance is beneficial for suppressing control oscillations and reducing delay.

[0020] Typically, the inductance tolerance of a ferrite bead is around 20%. Due to the difference in parasitic inductance of the ferrite beads connected to the control terminals of each MOSFET, different delays can occur between the drive signals of each control terminal. The MOSFET with the larger inductance of the ferrite bead will be delayed in turning off.

[0021] For example, when the inductance of the bead connected to the control terminal of the first MOSFET is less than the inductance of the bead connected to the control terminal of the second MOSFET, the drive signal of the control terminal of the first MOSFET is earlier than the drive signal of the control terminal of the second MOSFET when it is turned off, so the second MOSFET turns off later than the first MOSFET. Therefore, the turn-off current of the second MOSFET is greater than that of the first MOSFET.

[0022] Therefore, to suppress high-frequency oscillations in the control current of power devices, a ferrite bead is added to the control terminal of each MOSFET. However, the parasitic inductance generated by each ferrite bead is different, which makes it impossible for the switching timing of the power devices to be consistent. This prevents current sharing among the power devices, easily leading to increased switching losses and a higher risk of damage.

[0023] To address the aforementioned technical problems, this application provides a driving circuit, switching circuit, and power conversion circuit for power devices. The aim is to solve the problem of current sharing failure caused by adding a ferrite bead to the control terminal of each transistor. The technical concept of this application is to electrically connect all power devices to the same common ferrite bead. Because of this common connection, the parasitic inductance introduced by the ferrite bead is consistent across the control terminals of all power devices, eliminating the problem of different parasitic inductances introduced by using different ferrite beads at the control terminals of each power device. This ensures that the switching times of the parallel power devices are the same, thus guaranteeing current sharing among the power devices and reducing switching losses and damage risks during the switching process.

[0024] Figure 1 This is a schematic diagram of the structure of a driving circuit provided in one embodiment of this application. Figure 1 As shown. Power devices 14 have a first terminal 142, a second terminal 143, and a control terminal 141. The first terminals 142 of N power devices 14 are electrically connected to a first node D, and the second terminals 143 of N power devices 14 are electrically connected to a second node S. A drive circuit is electrically connected to the control terminals 141 and 143 of the N power devices 14, and is used to control the switching action of the N power devices 14. The drive circuit includes a drive input circuit 15 and a common magnetic bead 13.

[0025] The drive input circuit 15 has a first terminal 151 and a second terminal 152, and the common magnetic bead 13 has N first terminals 131 and N second terminals 132. The first terminal 151 of the drive input circuit 15 is electrically connected to the N first terminals 131 of the common magnetic bead 13, and the N second terminals 132 of the common magnetic bead 13 are electrically connected to the control terminals 141 of the N power devices 14 in a one-to-one correspondence. The second terminal 152 of the drive input circuit 15 is electrically connected to the second terminals of the N power devices.

[0026] The electrical connection between the first terminal 151 of the drive input circuit 15 and the N first terminals 131 of the common magnetic bead 13 means that the first terminal 151 of the drive input circuit 15 and the N first terminals 131 of the common magnetic bead 13 are directly connected via connecting wires, or the first terminal 151 of the drive input circuit 15 and the N first terminals 131 of the common magnetic bead 13 are electrically connected to each other via several impedance devices. It is worth noting that the electrical connection in this article can refer to a direct electrical connection or an indirect electrical connection via other electronic devices.

[0027] The electrical connection of the N second terminals 132 of the common magnetic bead 13 to the control terminals 141 of the N power devices 14 in a one-to-one correspondence means that the N second terminals 132 of the common magnetic bead 13 are electrically connected to the control terminals 141 of the N power devices 14 in a one-to-one correspondence via connecting wires. Specifically, one second terminal 132 of the common magnetic bead 13 is electrically connected to the control terminal 141 of a corresponding power device 14 via a connecting wire. Alternatively, the N second terminals 132 of the common magnetic bead 13 are electrically connected to the control terminals 141 of the N power devices 14 in a one-to-one correspondence via several impedance devices. Specifically, one second terminal 132 of the common magnetic bead 13 is electrically connected to the control terminal 141 of a corresponding power device 14 via several impedance devices.

[0028] The second terminal 152 of the drive input circuit 15 is electrically connected to the second terminals of the N power devices, which means that the second terminal 152 of the drive input circuit 15 is electrically connected to the second terminals of the N power devices through connecting wires, or the second terminal 152 of the drive input circuit 15 is electrically connected to the second terminals of the N power devices through several impedance devices.

[0029] The drive input circuit 15 is used to provide the drive signal. Since the common ferrite bead can be equivalent to a large resistor in the high-frequency range, its inductance can be ignored, which can effectively reduce the high-frequency oscillation current generated by the power device 14 when it switches under the drive signal. The common ferrite bead 13 can be equivalent to an inductor and a resistor with a very small resistance in the low-frequency range, and has little impact on the delay of the drive signal at the control terminal. The addition of the common ferrite bead 13 does not affect the switching operation of N power devices.

[0030] Furthermore, the control terminals 141 of each power device 14 are all electrically connected to the same common ferrite bead 13, meaning that the leads of the control terminals 141 of each power device 14 all pass through the same common ferrite bead 13. Since only one common ferrite bead 13 is used, the parasitic inductance introduced by the common ferrite bead 13 is consistent for the control terminals 141 of each power device 14. By setting it up in this way, the problem of different parasitic inductances introduced by the control terminals 141 of each power device 14 due to electrical connection with different ferrite beads can be eliminated.

[0031] In the above technical solution, the drive circuit provides drive signals to the power devices 14 operating in parallel to achieve high-power output. Specifically, the drive input circuit 15 provides the drive signal by electrically connecting the common ferrite bead 13 to the control terminals 141 of each power device 14. Utilizing the characteristic that the impedance of the common ferrite bead 13 increases with frequency, the current amplitude during high-frequency oscillations of the power devices 14 can be effectively suppressed, thereby suppressing high-frequency oscillations at the control terminals. By electrically connecting the control terminals 141 of each power device 14 to the same common ferrite bead 13, the problem of different parasitic inductances introduced by connecting different ferrite beads can be eliminated. This ensures that the switching times of the parallel power devices 14 are the same, thus ensuring current sharing among the devices, reducing switching losses and damage risks during switching, and improving the safety of the power devices 14 during operation.

[0032] In one embodiment, reference continues Figure 1 The drive circuit also includes an impedance circuit, which is electrically connected between the drive input circuit 15 and the N power devices 14. The impedance circuit includes N first impedance circuits 11 and N second impedance circuits 12. The number of first impedance circuits 11 is the same as the number of power devices 14, and the number of second impedance circuits 12 is also the same as the number of power devices 14. For example, when there are 4 power devices 14, there are also 4 first impedance circuits 11 and 4 second impedance circuits 12.

[0033] In the drive circuit, each first impedance circuit 11 has a first terminal 111 and a second terminal 112. The first terminal 151 of the drive input circuit 15 is electrically connected to the second terminals 112 of the N first impedance circuits 11. The first terminals 111 of the N first impedance circuits 11 are electrically connected to the N first terminals 131 of the common magnetic bead 13 in a one-to-one correspondence. Specifically, the first terminal 111 of one first impedance circuit 11 is electrically connected to one first terminal 131 of the corresponding common magnetic bead 13. The first impedance circuits 11 are used to regulate the current in the drive circuit to protect the control terminal 141 of the power device 14 from being damaged by the large current in the drive circuit.

[0034] Each second impedance circuit 12 has a first terminal 121 and a second terminal 122. The second terminal 152 of the drive input circuit 15 is electrically connected to the second terminals 122 of the N second impedance circuits 12, meaning that the second terminals 122 of the N second impedance circuits 12 are all electrically connected to the second terminal 152 of the drive input circuit 15. The second impedance circuits 12 are also used to regulate the current in the drive circuit to protect the control terminal 141 of the power device 14 from being damaged by the large current in the drive circuit.

[0035] The N second terminals 132 of the common magnetic bead 13 serve as the first driving terminals of the driving circuit, and are electrically connected one-to-one with the control terminals 141 of the N power devices 14. Specifically, one second terminal 13 of the common magnetic bead 13 is electrically connected to the control terminal 141 of a corresponding power device 14. The first terminals 121 of the N second impedance circuits 12 serve as the second driving terminals of the driving circuit, and are electrically connected one-to-one with the second terminals 142 of the N power devices 14. Specifically, one first terminal 121 of the second impedance circuit 12 is electrically connected to the second terminal 142 of a corresponding power device 14. This arrangement enables the driving circuit to provide driving signals to the N power devices 14, ensuring that the switching times of the N power devices 14 are the same, thus achieving current sharing among the devices.

[0036] It should also be noted that, in this embodiment, the impedance circuit includes N first impedance circuits 11 and N second impedance circuits 12. In other embodiments, the impedance circuit may include only N first impedance circuits 11 electrically connected to the control terminals of the N power devices 14, excluding the second impedance circuits 12. Alternatively, it may include only N second impedance circuits 12 electrically connected to the second terminals of the N power devices 14, excluding the first impedance circuits 11.

[0037] In this embodiment, N first impedance circuits 11 are electrically connected between the drive input circuit 15 and the common ferrite bead 13. The drive input circuit 15 is sequentially connected to the control terminals of N power devices 14 through the N first impedance circuits 11 and the common ferrite bead 13. In other embodiments, the positions of the N first impedance circuits 11 and the common ferrite bead 13 can be interchanged. The common ferrite bead 13 is electrically connected between the drive input circuit 15 and the N first impedance circuits 11. The drive input circuit 15 is sequentially connected to the control terminals of the N power devices 14 through the common ferrite bead 13 and the N first impedance circuits 11. Specifically, the first terminal 151 of the drive input circuit 15 is electrically connected to the N first terminals 131 of the common ferrite bead 13, and the N second terminals 132 of the common ferrite bead 13 are correspondingly connected to the second terminals 112 of the N first impedance circuits 11. The first terminals 111 of the N first impedance circuits 11 serve as the first driving terminals of the drive circuit, which are used to connect to the control terminals 141 of the N power devices 14 in a corresponding manner.

[0038] When the impedance circuit includes only N first impedance circuits 11, the connection method between the N first impedance circuits 11 and the common magnetic bead 13 can be the same as in the above embodiment, and will not be repeated here. In this case, the second terminal 152 of the drive input circuit 15 serves as the second drive terminal of the drive circuit.

[0039] When the impedance circuit includes only N second impedance circuits 11, the first terminal 151 of the drive input circuit 15 is electrically connected to the N first terminals 131 of the common magnetic bead 13, the N second terminals 132 of the common magnetic bead 13 serve as the first driving terminals of the drive circuit, the second terminal 152 of the drive input circuit 15 is electrically connected to the second terminals of the N second impedance circuits 12, and the first terminals 121 of the N second impedance circuits 12 are electrically connected to the second terminals 143 of the N power devices 14 in a one-to-one correspondence, thus using the first terminals 121 of the N second impedance circuits 12 as the second driving terminals of the drive circuit.

[0040] In the above technical solution, the drive circuit provides drive signals to the power devices 14 operating in parallel to achieve high-power output. Specifically, the drive input circuit 15 provides the drive signal, and the first impedance circuit 11 and the second impedance circuit 12 regulate the current in the drive circuit. By electrically connecting the common ferrite bead 13 to the control terminals 141 of each power device 14, and utilizing the characteristic that the impedance of the common ferrite bead 13 increases with frequency, the current amplitude during high-frequency oscillations of the power devices 14 can be effectively suppressed, thereby suppressing high-frequency oscillations at the control terminals. By electrically connecting the control terminals 141 of each power device 14 to the same common ferrite bead 13, the problem of different parasitic inductances introduced by electrically connecting different ferrite beads can be eliminated. This ensures that the switching times of the parallel power devices 14 are the same, that is, ensures current sharing among components, thereby reducing switching losses and damage risks during the switching process of the power devices 14, and improving the safety of the power devices 14 during operation.

[0041] In one embodiment, the common magnetic bead 13 includes a magnetic core and N coils, wherein the N coils are all wound around the magnetic core, and the first ends of the N coils serve as the N first ends 131 of the common magnetic bead 13, and the second ends of the N coils serve as the N second ends 132 of the common magnetic bead 13.

[0042] The coils are wound on the magnetic core in the following manner: N coils pass through the magnetic core from the first end to the second end in the same winding pattern, with the corresponding ends of the N coils located on the same side of the magnetic core. With this arrangement, when the drive circuit is operating, since the current direction of the N coils is the same, the magnetic field direction generated by the N coils is the same, meaning the N coils are in a positive magnetic coupling relationship. Due to the winding arrangement between the coils, the common magnetic bead 13 introduces parasitic inductance when the drive circuit is operating. This parasitic inductance is the same as that of the control terminals 141 of the N power devices 14.

[0043] Magnetic cores can be of various shapes, such as toroidal or square. Since the drive signal at the control end generates magnetic flux within the core, core saturation must be considered when designing the core's cross-sectional area. Cores with air gaps can also be used; for example, two U-shaped cores can be combined to form a toroidal core, or a U-shaped core and an I-type core can be combined to form a toroidal core.

[0044] In one embodiment, the number of coils is the same as the number of power devices 14 in the drive circuit, and the number of turns of each coil on the magnetic core is also the same. For example, the lead of the control terminal of each power device is wound once on the magnetic core.

[0045] In one embodiment, the coil is formed from wires or copper foil on a PCB.

[0046] In one embodiment, the power device 14 includes a field-effect transistor (MOSFET), a silicon carbide field-effect transistor (SiC MOSFET), or a gallium nitride transistor (GaN). When the power device 14 is a field-effect transistor, the first terminal 142 of the power device 14 is the drain of the MOSFET, the second terminal 143 of the power device 14 is the source of the MOSFET, and the control terminal 141 of the power device 14 is the gate of the MOSFET.

[0047] In some embodiments, the first impedance circuit 11 includes a control terminal resistor Rc and a control terminal diode Dc. For example... Figure 1 as well as Figures 2A to 2C As shown, each of the N first impedance circuits 11 consists of a control terminal resistor Rc and a control terminal diode Dc connected in parallel. The first terminal Rc1 of the control terminal resistor Rc and the first terminal Dc1 of the control terminal diode Dc are electrically connected to a node, forming the first terminal 111 of the first impedance circuit 11. The second terminal Rc2 of the control terminal resistor Rc and the second terminal Dc2 of the control terminal diode Dc are electrically connected to a node, forming the second terminal 112 of the first impedance circuit 11. The resistance values ​​of the N control terminal resistors Rc are equal, and the characteristic parameters of the N control terminal diodes Dc are equal. It is worth noting that the circuit structure of the first impedance circuit 11 can also be other forms. For example, the first impedance circuit 11 can contain only resistors without diodes; it can also include electronic components such as capacitors. However, it is necessary to ensure that the circuit structure and electrical parameters of the N first impedance circuits 11 are identical, thereby ensuring that the parasitic parameters introduced by the N first impedance circuits 11 to the corresponding power devices are the same. This configuration ensures that the drive signals of each power device are synchronized. It helps to achieve current sharing among power devices, thereby reducing switching losses and damage risks generated during the switching process of power devices.

[0048] In some embodiments, the second impedance circuit 12 includes a second terminal resistor Rt. (Reference) Figure 1 as well as Figures 2A to 2CN second impedance circuits 12 are all second-terminal resistors Rt. The first terminal Rt2 of the second-terminal resistor Rt serves as the first terminal 121 of the second impedance circuit 12, and the second terminal Rt1 serves as the second terminal 122. The resistance values ​​of the N second-terminal resistors Rt are equal. It is worth noting that the circuit structure of the second impedance circuit 12 can also be other forms. For example, the second impedance circuit 12 can include not only resistors but also electronic components such as diodes and capacitors. However, it is necessary to ensure that the circuit structure and electrical parameters of the N second impedance circuits 12 are the same, so as to ensure that the parasitic parameters brought by the N second impedance circuits 12 to the corresponding power devices are the same. By setting it in this way, the drive signal of each power device can be synchronized, which is beneficial to the current sharing among power devices, thereby reducing the switching losses and damage risks generated by the power devices during the switching process.

[0049] In one embodiment, the drive input circuit 15 may have one first terminal 151 and one second terminal 152. The second terminal 152 of the drive input circuit 15 is electrically connected to the second terminals 122 of N second impedance circuits 12. In another embodiment, the first terminal 151 of the drive input circuit 15 is electrically connected to the second terminals 112 of N first impedance circuits 11. In yet another embodiment, the first terminal 151 of the drive input circuit 15 is electrically connected to the N first terminals 131 of the common magnetic bead 13.

[0050] The drive input circuit 15 can be a non-isolated drive input circuit or an isolated drive input circuit.

[0051] In one embodiment, reference Figure 2A The drive input circuit 15 includes a power supply, meaning that the drive input circuit 15 is a non-isolated drive input circuit. The first terminal of the power supply serves as the first terminal 151 of the drive input circuit 15, and the second terminal of the power supply serves as the second terminal 152 of the drive input circuit 15.

[0052] In one embodiment, the drive input circuit 15 includes a power supply and an isolation unit, meaning the drive input circuit 15 is an isolated drive input circuit. The input side of the isolation unit is electrically connected to the power supply, one end of the output side of the isolation unit serves as the first terminal 151 of the drive input circuit 15, and the other end of the output side of the isolation unit serves as the second terminal 152 of the drive input circuit 15. The isolation unit can be any one of a transformer, an optocoupler isolation unit, or an optical fiber isolation unit.

[0053] When the isolation unit is a transformer, refer to Figure 2BThe primary winding 153 of the transformer is electrically connected to the power supply. The first terminal Vc of the secondary winding 154 serves as the first terminal 151 of the drive input circuit 15, and the second terminal Vd of the secondary winding 154 serves as the second terminal 152 of the drive input circuit 15. In one embodiment, at a certain moment, the voltage direction of the primary winding is the voltage difference V between the first terminal Va and the second terminal Vb of the primary winding, and the voltage of the secondary winding is the voltage difference Vs between the first terminal Vc and the second terminal Vd of the secondary winding. The voltages between the primary and secondary windings are determined by the number of turns and the direction of magnetic flux of the coils on both sides of the transformer. The primary and secondary windings of the transformer are not directly connected electrically, but rather transmit electrical energy through changes in magnetic flux between the magnetic circuits, thereby achieving electrical isolation.

[0054] In one embodiment, reference Figure 2C The drive input circuit 15 may have N first terminals 151 and N second terminals 152. When the drive input circuit 15 has N first terminals 151 and N second terminals 152, the N second terminals 152 of the drive input circuit 15 are electrically connected to the same node and then electrically connected to the second terminals 122 of the N second impedance circuits 12. As one implementation, the N first terminals 151 of the drive input circuit 15 are electrically connected one-to-one to the second terminals 112 of the N first impedance circuits 11, and the first terminals 111 of the N first impedance circuits 11 are electrically connected one-to-one to the N first terminals 131 of the common magnetic bead 13. As another implementation, the first terminals 151 of the drive input circuit 15 are electrically connected one-to-one to the N first terminals 131 of the common magnetic bead 13, and the N second terminals 132 of the common magnetic bead 13 are electrically connected one-to-one to the second terminals 112 of the N first impedance circuits 11.

[0055] In one embodiment, the drive input circuit 15 includes N power supplies, meaning the drive input circuit 15 is a non-isolated drive input circuit. The first terminals of the N power supplies serve as the N first terminals 151 of the drive input circuit 15, and the second terminals of the N power supplies serve as the N second terminals 152 of the drive input circuit 15.

[0056] In one embodiment, reference Figure 2CThere are N power supplies, all of which are AC power supplies. The output voltage amplitude and frequency of the N AC power supplies are the same. For example, the drive input circuit 15 includes four AC power supplies, labeled as the first AC power supply V1, the second AC power supply V2, the third AC power supply V3, and the fourth AC power supply V4. The negative terminals of the first AC power supply V1, the second AC power supply V2, the third AC power supply V3, and the fourth AC power supply V4 are electrically connected together, and then electrically connected to the second terminal 122 of the second impedance circuit 12. The positive terminals of the first AC power supply V1, the second AC power supply V2, the third AC power supply V3, and the fourth AC power supply V4 are correspondingly electrically connected to the second terminal 112 of the first impedance circuit 11.

[0057] In one embodiment, the drive input circuit 15 is an isolated drive input circuit 15. The drive input circuit 15 includes N power supplies and N isolation units. The input sides of the N isolation units are electrically connected to the N power supplies in a one-to-one correspondence. One end of the output side of each isolation unit serves as a first terminal 151 of the drive input circuit 15, and the other end of the output side of each isolation unit serves as a second terminal 152 of the drive input circuit 15. The isolation units include any one of transformers, optocoupler isolation units, and fiber optic isolation units.

[0058] In one embodiment, reference Figure 1 The driving circuit also includes a transient diode D. The first terminal of the transient diode D is electrically connected to the first terminal 151 of the driving input circuit 15, and the second terminal of the transient diode D is electrically connected to the second terminal 152 of the driving input circuit 15. The transient diode D is used to limit the output voltage of the driving input circuit 15, ensuring that the voltage does not exceed the preset voltage value of the transient diode D, thereby protecting the driving circuit from voltage fluctuations of the input power supply and preventing circuit damage.

[0059] In one embodiment, reference continues Figure 1 The driving circuit also includes N absorption circuits 16. The first terminals of the N absorption circuits 16 are electrically connected to the first terminals 142 of the N power devices 14, and the second terminals of the N absorption circuits 16 are electrically connected to the second terminals 143 of the N power devices 14. More specifically, the number of absorption circuits 16 is the same as the number of power devices. For example, when there are 4 power devices 14, there are 4 absorption circuits 16.

[0060] Each absorption circuit 16 includes an absorption capacitor Ca and an absorption resistor Ra. The first terminal of the absorption capacitor Ca serves as the first terminal of the absorption circuit 16, and the first terminal of the absorption resistor Ra is electrically connected to the second terminal of the absorption capacitor Ca. The second terminal of the absorption resistor Ra serves as the second terminal of the absorption circuit 16. The absorption capacitor Ca is used to ensure the stability of the voltage difference between the first terminal 142 and the second terminal 143 of the power device, preventing excessive voltage fluctuations that could damage the power device. The absorption resistor Ra is used to prevent excessive current during the discharge of the absorption capacitor Ca, which could also damage the power device.

[0061] In the above technical solution, the drive circuit limits the output voltage range of the drive input circuit by connecting a transient diode D in parallel with the power input circuit, protecting the power device 14 electrically connected to the drive circuit from the influence of voltage fluctuations. Secondly, a first impedance circuit 11 and / or a second impedance circuit 12 with the same parameters are set, and a common ferrite bead 13 is set, so that the impedance characteristics of the drive circuits corresponding to the multiple power devices 14 connected in parallel are consistent, thereby ensuring current sharing among the multiple power devices 14. In addition, each power device 14 is also connected in parallel with an absorption circuit, thereby ensuring that the voltage across the power device does not change abruptly, thus protecting the power device from damage.

[0062] In one embodiment, the power device 14 with four ports further includes a Kelvin source, which is electrically connected to the second terminal inside the power device 14. When the power device 14 is electrically connected to the drive circuit, the Kelvin sources of the N power devices are electrically connected to the N second drive terminals of the drive circuit in a one-to-one correspondence. That is, the second terminal of the drive input circuit 15 is indirectly electrically connected to the second terminals of the N power devices through the Kelvin sources. This electrical connection method can reduce electrical connection resistance and parasitic inductance.

[0063] like Figure 1 As shown, one embodiment of this application also provides a switching circuit, which includes a driving circuit and N power devices 14, where N ≥ 2 and is a positive integer, for example, N = 4 in this embodiment. The control terminals 141 of the N power devices 14 are electrically connected to the N first driving terminals of the driving circuit, and the second terminals 143 of the N power devices are electrically connected to the N second driving terminals of the driving circuit. The driving circuit of the N power devices is used to provide driving signals to the N power devices 14.

[0064] The first terminals 142 of N power devices are electrically connected to the first node D to form the first terminal of the switching circuit, and the second terminals 143 of N power devices are electrically connected to the second node S to form the second terminal of the switching circuit, so that the N power devices 14 are connected in parallel to output greater power.

[0065] Figure 3This is a schematic diagram of the power conversion circuit provided in one embodiment of this application. Figure 3 As shown, the circuit includes two switching circuits and an input capacitor C1. The two switching circuits are labeled as the first switching circuit 20 and the second switching circuit 21. The first terminal D1 of the first switching circuit 20 is electrically connected to the first terminal of the input capacitor C1, the second terminal S1 of the first switching circuit 20 is electrically connected to the first terminal D2 of the second switching circuit 21, and the second terminal S2 of the second switching circuit 21 is electrically connected to the second terminal of the input capacitor. Both the first switching circuit 20 and the second switching circuit 21 are configured as follows: Figure 1 The switching circuit shown.

[0066] The following description uses an example where both the first and second switching circuits contain four power devices 14, and these power devices are MOSFETs. In the first switching circuit, the four power devices 144 are connected in parallel to form an upper bridge arm switch. The drain of the upper bridge arm switch is the drain 1442 of the four power devices 144, and the source of the upper bridge arm switch is the source 1443 of the four power devices. In the second switching circuit, the four power devices 145 are connected in parallel to form a lower bridge arm switch. The drain of the lower bridge arm switch is the drain 1452 of the four power devices 145, and the source of the lower bridge arm switch is the source 1453 of the four power devices 145.

[0067] The drain of the upper bridge arm switch is connected to the positive terminal of the DC input, which is the first terminal of the first switching circuit electrically connected to the positive terminal of the DC input. The source of the lower bridge arm switch is connected to the negative terminal of the DC input, which is the second terminal of the second switching circuit electrically connected to the negative terminal of the DC input. The second terminal of the first switching circuit serves as the second terminal of the power conversion circuit. The MOSFET gate voltage threshold is several volts. When the MOSFET gate voltage is greater than the threshold voltage, the MOSFET is turned on; when the gate voltage is less than the threshold voltage, the MOSFET is turned off. When the upper bridge arm switch is on, the first terminal of the first switching unit is connected to the second terminal of the first switch, and the second terminal of the power conversion circuit outputs a high level. When the lower bridge arm switch is on, the first terminal of the second switching unit is connected to the second terminal of the second switch, and the second terminal of the power conversion circuit outputs a low level. When the upper and lower bridge arm switches are alternately turned on, the second terminal of the power conversion circuit outputs a square wave.

[0068] In the power conversion circuit, DC power is converted into square wave power by controlling the on and off states of two switching circuits. The stability of the drive circuit ensures the stability of the switching circuit and the power conversion circuit, thereby guaranteeing the accurate and stable operation of the external circuits connected to the switching circuit and the power conversion circuit.

[0069] Other embodiments of this application will readily occur to those skilled in the art upon consideration of the specification and practice of the invention disclosed herein. This application is intended to cover any variations, uses, or adaptations of this application that follow the general principles of this application and include common knowledge or customary techniques in the art not disclosed herein. The specification and examples are to be considered exemplary only, and the true scope and spirit of this application are indicated by the following claims.

[0070] It should be understood that this application is not limited to the precise structure described above and shown in the accompanying drawings, and various modifications and changes can be made without departing from its scope. The scope of this application is limited only by the appended claims.

Claims

1. A driving circuit for a power device, characterized in that, The driving circuit is used to control the switching action of N power devices (14), where N≥2 and is a positive integer. Each power device (14) has a first terminal (142), a second terminal (143), and a control terminal (141). The first terminals of the N power devices are electrically connected to a first node, and the second terminals of the N power devices are electrically connected to a second node. The driving circuit includes: The driving input circuit (15) is provided with a first terminal (151) and a second terminal (152); and A common magnetic bead (13) is provided with N first ends (131) and N second ends (132). Wherein, the first end (151) of the drive input circuit (15) is electrically connected to the N first ends (131) of the common magnetic bead (13), the N second ends (132) of the common magnetic bead (13) are electrically connected to the control ends (141) of the N power devices (14) in a one-to-one correspondence, and the second end (152) of the drive input circuit (15) is electrically connected to the second ends of the N power devices; The common magnetic bead (13) includes a magnetic core and N coils; The N coils are all wound around the magnetic core, and the first ends of the N coils serve as the N first ends (131) of the common magnetic bead (13), and the second ends of the N coils serve as the N second ends (132) of the common magnetic bead (13). The N coils pass through the magnetic core in the same winding manner from the first end to the second end, and the corresponding ends of the N coils are located on the same side of the magnetic core. When the driving circuit is working, the N coils form a positive magnetic coupling relationship. The parasitic inductance introduced by the common magnetic bead (13) is the same as that of the control terminal (141) of the N power devices (14).

2. The driving circuit according to claim 1, characterized in that, The driving circuit further includes an impedance circuit, which is electrically connected between the driving input circuit and the N power devices.

3. The driving circuit according to claim 2, characterized in that, The impedance circuit includes N first impedance circuits (11), each of which has a first terminal (111) and a second terminal (112). Wherein, the first end (151) of the drive input circuit (15) is electrically connected to the second end (112) of the N first impedance circuits (11), the first ends (111) of the N first impedance circuits (11) are electrically connected one-to-one with the N first ends (131) of the common magnetic bead (13), and the N second ends (132) of the common magnetic bead (13) serve as the first drive ends of the drive circuit, and are used to be electrically connected one-to-one with the control ends (141) of the N power devices (14); or The first end (151) of the drive input circuit (15) is electrically connected to the N first ends (131) of the common magnetic bead (13), and the N second ends (132) of the common magnetic bead (13) are electrically connected to the second ends (112) of the N first impedance circuits (11) in a one-to-one correspondence. The first ends (111) of the N first impedance circuits (11) serve as the first drive ends of the drive circuit and are used to be electrically connected to the control ends (141) of the N power devices (14) in a one-to-one correspondence.

4. The driving circuit according to claim 2 or 3, characterized in that, The impedance circuit includes N second impedance circuits (12), each of which has a first terminal (121) and a second terminal (122). The second end (152) of the drive input circuit (15) is electrically connected to the second end (122) of the N second impedance circuits (12), and the first end (121) of the N second impedance circuits (12) serves as the second drive end of the drive circuit, and is used to be electrically connected to the second end (143) of the N power devices (14) in a one-to-one correspondence.

5. The driving circuit according to claim 1, characterized in that, Each of the coils has the same number of turns on the magnetic core, and the coils are formed from wires or copper foil on a PCB.

6. The driving circuit according to claim 3, characterized in that, The N first impedance circuits (11) have the same circuit structure and electrical parameters.

7. The driving circuit according to claim 4, characterized in that, The circuit structure and electrical parameters of the N second impedance circuits (12) are the same.

8. The driving circuit according to claim 1, characterized in that, The power device (14) includes a field-effect transistor (MOSFET), a silicon carbide field-effect transistor (SiC MOSFET), or a gallium nitride transistor (GaN).

9. The driving circuit according to claim 1, characterized in that, The drive input circuit (15) includes a power supply; Wherein, the first end of the power supply serves as the first end (151) of the drive input circuit (15), and the second end of the power supply serves as the second end (152) of the drive input circuit (15).

10. The driving circuit according to claim 1, characterized in that, The drive input circuit (15) includes N power supplies; The first ends of the N power supplies are connected to the control terminals of the N power devices one by one as the N first ends (151) of the drive input circuit (15), and the second ends of the N power supplies are connected to the N second ends (152) of the drive input circuit (15) and then connected to the second ends of the N power devices after being connected to the same node. The N power supplies have the same output voltage amplitude and frequency.

11. The driving circuit according to claim 9 or 10, characterized in that, The drive input circuit (15) also includes an isolation unit; The input side of the isolation unit is electrically connected to the power supply, one end of the output side of the isolation unit serves as the first end (151) of the drive input circuit, and the other end of the output side of the isolation unit serves as the second end (152) of the drive input circuit (15).

12. The driving circuit according to claim 11, characterized in that, The isolation unit includes: a transformer, an optical coupler isolation unit, or an optical fiber isolation unit; The primary winding of the transformer is electrically connected to the power supply, the first end of the secondary winding of the transformer serves as the first end (151) of the drive input circuit (15), and the second end of the secondary winding of the transformer serves as the second end (152) of the drive input circuit (15).

13. The driving circuit according to claim 1, characterized in that, The driving circuit also includes a transient diode (D), the first end of which is electrically connected to the first end (151) of the driving input circuit (15), and the second end of which is electrically connected to the second end (152) of the driving input circuit (15).

14. The driving circuit according to claim 1, characterized in that, Each of the power devices (14) also includes a Kelvin source, and the second terminal of the drive input circuit is electrically connected to the second terminal of the N power devices through the Kelvin source.

15. A switching circuit, characterized in that, Includes the drive circuit as described in any one of claims 1 to 14 and N power devices (14), wherein N ≥ 2 and is a positive integer; The driving circuit is used to control the switching action of the N power devices; The first end (142) of the N power devices (14) is electrically connected to the first node to form the first end of the switching circuit, and the second end (143) of the N power devices (14) is electrically connected to the second node to form the second end of the switching circuit.

16. A power conversion circuit, characterized in that, It includes an input capacitor, a first switching circuit, and a second switching circuit, wherein both the first switching circuit and the second switching circuit are the switching circuits as described in claim 15. Wherein, the first terminal of the first switching circuit is electrically connected to the first terminal of the input capacitor, the second terminal of the first switching circuit is electrically connected to the first terminal of the second switching circuit, and the second terminal of the second switching circuit is electrically connected to the second terminal of the input capacitor.

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