A drive circuit for a three-phase system power switching device

Abstract

The application provides a driving circuit for a three-phase system power switch device, the three-phase system comprises a power switch group corresponding to each phase, the power switch group comprises an upper bridge arm power switch and a lower bridge arm power switch, the driving circuit corresponds to the upper bridge arm power switch, the driving circuit comprises a capacitor voltage division circuit, a voltage stabilizing circuit and a push-pull driving circuit, the capacitor voltage division circuit is connected with two phases except the corresponding phase, the output end of the capacitor voltage division circuit is connected with the corresponding voltage stabilizing circuit, the push-pull driving circuit and the upper bridge arm power switch of the corresponding phase in sequence, direct power is taken from the three-phase power supply, and a stable direct current voltage is generated to reliably drive the power switch device. The application realizes efficient and reliable driving of the power switch device, and overcomes the limitations of the traditional driving circuit which depends on a heavy isolation transformer or a complex switch power supply.

Description

Technical Field

[0001] This invention relates to the field of power electronics technology, and more specifically to a drive circuit for power switching devices in a three-phase system. Background Technology

[0002] Insulated-gate bipolar transistors (IGBTs) and metal-oxide-semiconductor field-effect transistors (MOSFETs) are core power switching devices in modern power electronic devices. Their reliable and efficient operation is highly dependent on the performance of the gate drive circuit. A good drive circuit needs to provide the gate of the power device with a pulse voltage of sufficient amplitude, with steep rise and fall edges, and possess the necessary isolation, protection, and voltage regulation functions.

[0003] In three-phase AC systems (such as three-phase motor frequency converters, three-phase uninterruptible power supplies, photovoltaic / wind power inverters, etc.), providing drive power to the IGBTs or MOSFETs of the upper arm is a major technical challenge. Because the reference ground (emitter or source) of the upper arm power devices is floating at a high potential, traditional single DC bus power supply drive schemes cannot be directly applied. Currently, the mainstream technical solutions to this problem are mainly the following two:

[0004] Using isolation transformers: This is a classic approach. Low-voltage power from the control board is coupled to individual floating drive points via multiple isolation transformers. The advantages of this approach are its mature technology and reliable electrical isolation. However, its disadvantages are also significant: isolation transformers are typically large and heavy, hindering the miniaturization and lightweight design of power electronic devices; furthermore, the transformer's core material and non-ideal characteristics may limit its high-frequency performance and introduce substantial electromagnetic interference (EMI).

[0005] Using dedicated switching power supplies (such as switched-capacitor charge pumps or isolated DC-DC modules): This is a more modern approach. It involves designing complex switching power supply circuits (e.g., ASIC-based charge pumps) or directly using off-the-shelf isolated DC-DC power modules to provide independent isolated power to each upper bridge arm drive circuit. While this approach offers excellent performance, it introduces significant complexity and cost. Dedicated chips or modules are inherently expensive, and the complex peripheral circuitry increases the number of components, PCB area, and overall cost of the system.

[0006] In summary, existing drive power supply solutions share a common contradiction: pursuing a simple structure and low cost makes it difficult to meet the requirements of high-performance isolated drives (such as transformer-based solutions); while pursuing high performance and high reliability often comes with complex circuits, high costs, and large size (such as switching power supply solutions). This contradiction is particularly pronounced in three-phase systems, which require multiple isolated drive power supplies. Summary of the Invention

[0007] The technical problem to be solved by this invention is to provide a driving circuit for power switching devices in a three-phase system, which can safely and efficiently obtain energy directly from the main power circuit without relying on bulky transformers and complex switching power supplies, and provide a stable and reliable driving voltage for the IGBT / MOSFET of the upper bridge arm, thereby achieving a good balance between cost, size and performance. In particular, the driving stability and anti-interference ability under high dv / dt environment are optimized.

[0008] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows:

[0009] A driving circuit for power switching devices in a three-phase system is disclosed. The three-phase system includes power switch groups corresponding to each phase. Each power switch group includes an upper bridge arm power switch and a lower bridge arm power switch. The driving circuit corresponds to the upper bridge arm power switch and includes a capacitor voltage divider circuit, a voltage regulator circuit, and a push-pull driving circuit. The capacitor voltage divider circuit is connected to the two phases other than the corresponding phase. The output terminal of the capacitor voltage divider circuit is connected to the upper bridge arm power switch of the corresponding phase in sequence through the corresponding voltage regulator circuit and the push-pull driving circuit, thereby realizing direct power intake from the three-phase power supply and generating a stable DC voltage to reliably drive the power switching devices.

[0010] Furthermore, the capacitor voltage divider circuit includes a first isolation capacitor, a second isolation capacitor, a first diode, a second diode, and a filter capacitor. The anode of the first diode is connected to one of the two phases other than the corresponding phase through the first isolation capacitor. The anode of the second diode is connected to the other of the two phases other than the corresponding phase through the second isolation capacitor. The cathodes of the first diode and the second diode are both connected to the drive reference ground of the upper bridge arm power switch of the corresponding phase through the filter capacitor. The positive and negative terminals of the filter capacitor are respectively connected to the positive and negative output terminals of the capacitor voltage divider circuit and connected to the corresponding voltage regulator circuit.

[0011] Furthermore, the upper bridge arm power switch adopts a MOSFET switch or a pair of anti-parallel IGBTs. When the upper bridge arm power switch adopts a MOSFET switch, the cathodes of the first diode and the second diode are both connected to the source of the corresponding phase MOSFET switch through a filter capacitor. When the upper bridge arm power switch adopts a pair of anti-parallel IGBTs, the driving circuit corresponds one-to-one with the IGBT, and the cathodes of the first diode and the second diode are both connected to the emitter of the corresponding phase IGBT through a filter capacitor.

[0012] Furthermore, the voltage regulator circuit includes a first current-limiting resistor, a second current-limiting resistor, a transistor, a Zener diode, a compensation capacitor, and an output capacitor. The positive output terminal of the capacitor voltage divider circuit is connected to the collector of the transistor through the first current-limiting resistor, and the positive output terminal of the capacitor voltage divider circuit is connected to the base of the transistor through the second current-limiting resistor. The emitter of the transistor is connected to the positive terminal of the output capacitor, and the base of the transistor is also connected to the cathode of the Zener diode. The compensation capacitor is connected between the base of the transistor and the positive terminal of the output capacitor. The anode of the Zener diode is connected to the drive reference ground of the upper bridge arm power switch of the corresponding phase. The positive and negative terminals of the output capacitor are respectively connected to the positive and negative output terminals of the voltage regulator circuit and connected to the corresponding push-pull drive circuit.

[0013] Furthermore, the upper bridge arm power switch adopts a MOSFET switch or a pair of anti-parallel IGBTs. When the upper bridge arm power switch adopts a MOSFET switch, the anode of the Zener diode is connected to the source of the corresponding phase MOSFET switch. When the upper bridge arm power switch adopts a pair of anti-parallel IGBTs, the driving circuit corresponds one-to-one with the IGBT, and the anode of the Zener diode is connected to the emitter of the corresponding phase IGBT.

[0014] Furthermore, the push-pull drive circuit includes a first transistor and a second transistor, as well as a base current-limiting resistor and an accelerating capacitor connected in parallel. The bases of the first transistor and the second transistor are both connected to an external drive control signal through the parallel base current-limiting resistor and the accelerating capacitor. The collector of the first transistor is connected to the positive terminal of the output of the voltage regulator circuit. The collector of the second transistor is connected to the drive reference ground of the upper bridge arm power switch of the corresponding phase. The emitters of the first transistor and the second transistor form a push-pull output terminal connected to the controlled terminal of the upper bridge arm power switch of the corresponding phase.

[0015] Furthermore, the upper bridge arm power switch adopts a MOSFET switch or a pair of anti-parallel IGBTs. When the upper bridge arm power switch adopts a MOSFET switch, the collector of the second transistor is connected to the source of the corresponding phase MOSFET switch, and the emitters of the first transistor and the second transistor form a push-pull output terminal connected to the gate of the corresponding phase MOSFET switch. When the upper bridge arm power switch adopts a pair of anti-parallel IGBTs, the driving circuit corresponds one-to-one with the IGBTs, the collector of the second transistor is connected to the emitter of the corresponding phase IGBT, and the emitters of the first transistor and the second transistor form a push-pull output terminal connected to the gate of the corresponding phase IGBT.

[0016] Compared with the prior art, the advantages of the present invention are as follows:

[0017] In the driving circuit of this invention, the capacitor voltage divider circuit is connected to the two phases other than the corresponding phase, utilizing the phase difference of the three-phase system itself. Energy is directly obtained from the main power circuit through the capacitor, resulting in a short energy conversion path and high efficiency. The output of the capacitor voltage divider circuit is connected to the upper arm power switch of the corresponding phase in sequence through the corresponding voltage regulator circuit and push-pull drive circuit. The voltage regulator circuit ensures the stability of the driving voltage and avoids drive failure caused by power fluctuations. The push-pull output circuit provides low impedance driving capability, ensuring fast switching of power devices and helping to reduce switching losses. This invention completely eliminates the bulky isolation transformer and expensive dedicated switching power supply chips or modules, using only common passive and active components such as capacitors, diodes, transistors, and Zener diodes, greatly simplifying the circuit structure and reducing material cost (BOM cost) and PCB area. Attached Figure Description

[0018] Figure 1 This is a circuit diagram of the driving circuit applied to a MOSFET switch according to an embodiment of the present invention.

[0019] Figure 2 The circuit diagram shows the driving circuit of this invention applied to an IGBT switch. Detailed Implementation

[0020] The present invention will be further described below with reference to the accompanying drawings and specific preferred embodiments, but this does not limit the scope of protection of the present invention.

[0021] This embodiment proposes a drive circuit for power switching devices in a three-phase system. The aim is to obtain energy directly from the three-phase AC system and generate a stable DC voltage through a simple and efficient circuit structure without relying on isolation transformers and complex switching power supplies. This allows for reliable driving of power switching devices (such as IGBTs or MOSFETs), thereby reducing system cost, size, simplifying design, and improving drive robustness under high-frequency and high-voltage conditions.

[0022] The driving circuit of this embodiment is applied to a specific three-phase AC system. The three-phase AC system includes power switch groups corresponding to phases A, B, and C. Each power switch group includes two power switching devices: an upper bridge arm power switch and a lower bridge arm power switch. The driving circuit corresponds to the upper bridge arm power switch, thereby setting an independent power extraction and driving unit for each upper bridge arm power switch device. It directly obtains energy from the three-phase AC system and generates a stable and reliable driving voltage through simple passive and active circuits.

[0023] In this embodiment, the driving circuit includes a capacitor voltage divider circuit, a voltage regulator circuit, and a push-pull driving circuit. The capacitor voltage divider circuit is connected to the two phases other than the corresponding phase. The output terminal of the capacitor voltage divider circuit is connected to the upper bridge arm power switch of the corresponding phase in sequence through the corresponding voltage regulator circuit and the push-pull driving circuit, so as to realize the direct power supply from the three-phase power supply and generate a stable DC voltage to reliably drive the power switching device.

[0024] When the upper bridge arm power switch uses a MOSFET switch, the drive circuit corresponds one-to-one with the MOSFET switch of the upper bridge arm power switch, such as... Figure 1 As shown, the power switch Q6 of the upper bridge arm of phase B is connected to the corresponding drive circuit. The drive circuit structure of the upper bridge arms of phases A and C is exactly the same as that of phase B, so it is omitted in the figure.

[0025] When IGBTs are used as the power switches in the upper bridge arms, due to the unidirectional conductivity of IGBTs, the power switching device in each upper bridge arm needs to be replaced with a pair of anti-parallel IGBTs. The drive circuit corresponds one-to-one with the IGBTs of the upper bridge arm power switches, such as... Figure 2 As shown, the pair of anti-parallel IGBTs (Q15 and Q16) in phase B are each connected to a corresponding drive circuit. The drive circuit structures of the upper bridge arms in phases A and C are exactly the same as those in phase B, so they are omitted in the figure.

[0026] In this embodiment, the capacitor voltage divider circuit includes a first isolation capacitor, a second isolation capacitor, a first diode, a second diode, and a filter capacitor. The anode of the first diode is connected to one of the two phases other than the corresponding phase through the first isolation capacitor. The anode of the second diode is connected to the other of the two phases other than the corresponding phase through the second isolation capacitor. The cathodes of both the first and second diodes are connected to the positive terminal of the filter capacitor. The negative terminal of the filter capacitor is connected to the drive reference ground of the upper bridge arm power switch of the corresponding phase. The positive and negative terminals of the filter capacitor serve as the positive and negative output terminals of the capacitor voltage divider circuit, respectively, and are connected to the corresponding voltage regulator circuit. This circuit uses capacitors to divide and rectify the three-phase voltage, generating a DC voltage across the filter capacitor.

[0027] Figure 1 In the circuit, the capacitor divider circuit for the upper bridge arm MOSFET (Q6) of phase B consists of a first isolation capacitor C1, a second isolation capacitor C4, a first diode D1, a second diode D3, and a filter capacitor C2. One end of C1 is connected to phase A of the three-phase system, and one end of C4 is connected to phase C of the three-phase system. The anode of D1 is connected to the other end of C1, and the anode of D3 is connected to the other end of C4. The cathodes of D1 and D3 are connected to the positive terminal of the filter capacitor C2. The negative terminal of C2 is connected to the source (S) of the upper bridge arm MOSFET Q6 of phase B. This point serves as the reference ground (GND_DRV) of this drive circuit, which is a floating reference point with a high potential relative to the system ground.

[0028] Utilizing the phase difference between the three-phase voltages (phase A, phase B, and phase C), current flows into the circuit through capacitors C1 and C4. D1 and D3 alternately conduct within different phase intervals of the three-phase voltages, charging capacitor C2. Specifically, when the phase A voltage is higher than the phase B voltage and the voltage difference is sufficient to overcome the forward voltage drop of D1 and the voltage at the C2 terminal, D1 conducts, and current flows through C1 and D1 to charge C2; ​​when the phase C voltage is higher than the phase B voltage and the corresponding conditions are met, D3 conducts, and current flows through C4 and D3 to charge C2. Because the three-phase voltages differ by 120°, D1 and D3 exhibit a specific alternating conduction pattern within each power frequency cycle. Essentially, it is a dual-source capacitor step-down half-wave rectifier circuit that utilizes the capacitive reactance characteristics of the isolation capacitor to achieve current-limited energy extraction, obtaining DC energy from the three-phase AC system without the need for a power frequency transformer. The voltage rating and capacitance value of the isolation capacitors (C1, C4) need to be selected based on the system voltage and the required drive power. By appropriately selecting the capacitance values ​​of C1 and C4 (typically high-voltage ceramic or film capacitors ranging from nanofarads to microfarads), and dividing them with C2, a pulsating DC voltage is obtained across C2. The average value of this voltage can be approximately estimated using the following formula:

[0029] in, This is the voltage across the filter capacitor. The phase voltage amplitude, The forward voltage drop of diodes D1 and D3 is... This represents the equivalent capacitance of capacitors C1 and C4 connected in series.

[0030] Figure 2 Taking Q16 in the upper arm IGBT of phase B as an example, the capacitor voltage divider circuit consists of a first isolation capacitor C5, a second isolation capacitor C8, a first diode D4, a second diode D6, and a filter capacitor C6. One end of C5 is connected to phase A of the three-phase system, and one end of C8 is connected to phase C of the three-phase system. The anode of D4 is connected to the other end of C5, and the anode of D6 is connected to the other end of C8. The cathodes of D4 and D6 are connected to the positive terminal of the filter capacitor C6. The negative terminal of C6 is connected to the emitter (E terminal) of Q16 in the upper arm IGBT of phase B. Its working principle is similar to... Figure 1 The capacitor voltage divider circuit is exactly the same as that in the previous example, so it will not be described in detail here.

[0031] In this embodiment, the voltage regulator circuit includes a first current-limiting resistor, a second current-limiting resistor, a transistor serving as the regulating transistor, a Zener diode, a compensation capacitor, and an output capacitor. The positive terminal of the capacitor voltage divider circuit is connected to the collector of the transistor through the first current-limiting resistor. The positive terminal of the capacitor voltage divider circuit is also connected to the base of the transistor through the second current-limiting resistor. The emitter of the transistor is connected to the positive terminal of the output capacitor. The base of the transistor is also connected to the cathode of the Zener diode. The anode of the Zener diode is connected to the drive reference ground of the upper bridge arm power switch of the corresponding phase. The compensation capacitor is connected between the base of the transistor and the positive terminal of the output capacitor. The positive and negative terminals of the output capacitor serve as the positive and negative output terminals of the voltage regulator circuit, respectively, and are connected to the corresponding push-pull drive circuit. When the base voltage of the transistor (stabilized by the Zener diode) is higher than its emitter voltage (Vout), the transistor conducts and charges the output capacitor; otherwise, it is cut off, thereby stabilizing the output voltage Vout.

[0032] Figure 1In the circuit diagram, the voltage regulator circuit for the upper bridge arm MOSFET (Q6) of phase B consists of a first current-limiting resistor R1, a second current-limiting resistor R2, a PNP transistor Q3 as the regulating transistor, a Zener diode D2, a compensation capacitor C15, and an output capacitor C3. One end of R1 is connected to the positive terminal of capacitor C2, and the other end is connected to the collector of Q3. The emitter of Q3 serves as the regulated output terminal (Vout) and is connected to the positive terminal of output capacitor C3. The negative terminal of C3 is connected to the source of Q6, which serves as the drive reference ground (GND_DRV). The cathode of Zener diode D2 is connected to the base of Q3, and the anode is connected to the drive reference ground. The compensation capacitor C15 is connected between the base of Q3 and Vout. The second current-limiting resistor R2 is connected between the base of Q3 and the positive terminal of capacitor C2 to provide a base current path and improve stability.

[0033] In this embodiment, the regulating transistor Q3 needs to be a PNP transistor with sufficient current gain (β value) and power handling capability to ensure that the peak current required for gate drive can be provided. The Zener diode D2's Zener voltage Vz determines the final drive voltage Vout (Vout ≈ Vz - 0.7V). Zener diode D2 clamps the base voltage of Q3 to a fixed value Vz. The emitter output voltage of Q3, Vout = Vz - Vbe, where Vbe is the base-emitter voltage drop of Q3 (typically about 0.7V). When the load lightens and Vout attempts to rise, the base-emitter voltage Vbe of Q3 decreases, the conduction of Q3 weakens, thereby limiting the charging current to C3, causing Vout to fall back. Conversely, when the load increases and Vout decreases, the conduction of Q3 deepens, increasing the charging current, causing Vout to rise again. In this way, regardless of the load changes brought about by the subsequent push-pull circuit and MOSFET gate charging, Vout can be maintained at a relatively stable value, such as 15V or 12V, specifically determined by the voltage regulation value Vz of the selected Zener diode D2.

[0034] In this embodiment, the introduction of compensation capacitor C15 constitutes a local frequency compensation network. When the load current changes abruptly due to the subsequent push-pull circuit and MOSFET gate charging, C15 can quickly absorb or release charge, smoothing the change in Q3 base voltage, thereby significantly suppressing the instantaneous fluctuation of Vout and improving the dynamic stability of the drive power supply and its responsiveness to load changes. This is particularly suitable for scenarios where power is drawn from a pulsating DC power supply.

[0035] Figure 2Taking Q16 in the upper arm IGBT of phase B as an example, the voltage regulator circuit consists of a first current-limiting resistor R3, a second current-limiting resistor R4, a transistor Q12 (PNP type) as the regulating transistor, a Zener diode D5, a compensation capacitor C17, and an output capacitor C7. One end of R3 is connected to the positive terminal of capacitor C6, and the other end is connected to the collector of Q12. One end of R4 is connected to the positive terminal of capacitor C6, and the other end is connected to the base of Q12. The emitter of Q12 serves as the regulated output terminal (Vout) and is connected to the positive terminal of output capacitor C7. The negative terminal of C7 is connected to the emitter of Q16, which serves as the drive reference ground (GND_DRV). The cathode of Zener diode D5 is connected to the base of Q12, and the anode is connected to the drive reference ground. The compensation capacitor C17 is connected between the base of Q12 and Vout. Its working principle is similar to... Figure 1 The voltage regulator circuit is exactly the same as that in the previous one, so it will not be described in detail here.

[0036] In this embodiment, the push-pull drive circuit includes complementary first and second transistors, as well as a base-limiting current resistor and an accelerating capacitor. The bases of both the first and second transistors are connected to an external drive control signal via the base-limiting current resistor. The collector of the first transistor is connected to the positive output terminal (Vout) of the voltage regulator circuit, and the collector of the second transistor is connected to the drive reference ground (GND_DRV) of the upper arm power switch of the corresponding phase. The emitters of the first and second transistors are connected together to form a push-pull output terminal connected to the controlled terminal of the upper arm power switch of the corresponding phase. The accelerating capacitor and the base-limiting current resistor are connected in parallel to form a RC composite drive network bridging the drive control signal input terminal and the base connection point of the two transistors. This circuit can provide sufficient pull-up and pull-down currents to ensure rapid turn-on and turn-off of the upper arm power switch.

[0037] Figure 1 In the circuit, the push-pull drive circuit for the upper bridge arm MOSFET (Q6) of phase B consists of an NPN transistor Q4, a PNP transistor Q5, a base current-limiting resistor R24, and an accelerating capacitor C13. The emitters of Q4 and Q5 are connected together as the output of the drive signal, which is directly connected to the gate (G) of the power MOSFET Q6 to be driven. The collector of Q4 is connected to the output of the voltage regulator circuit (Vout, i.e., the positive terminal of C3), and the collector of Q5 is connected to the drive reference ground (GND_DRV, i.e., the source of Q6). The drive control signal V_DRV generated by the external controller (typically a logic level of 0V and 5V or 3.3V) is applied to the bases of Q4 and Q5 through the parallel network of R24 and C13.

[0038] This is an enhanced totem-pole output circuit. Push-pull transistors Q4 and Q5 are selected as small-to-medium power transistors with fast switching speed and high current capability. When V_DRV is high, Q4 conducts, Q5 is cut off, and the drive current flows from Vout through Q4, rapidly charging the gate capacitor of Q6, causing Q6 to turn on quickly.

[0039] In this process, the parallel configuration of R24 and C13 significantly improves the reliability of operation in high-frequency, high-voltage three-phase systems: at the rising edge of the drive signal, C13 presents extremely low impedance, forming a transient low-impedance path, which is equivalent to injecting pulse-enhanced current (charge pump effect) into the totem pole base, enabling Q4 to quickly cross the linear region and enter the saturation state, significantly shortening the turn-on delay; as the base voltage stabilizes, C13 completes charging, and R24 automatically dominates the current path, precisely limiting the steady-state base current and preventing storage effects and additional power consumption caused by deep transistor saturation. This adaptive characteristic of "transient strong drive + steady-state current limiting" overcomes the contradiction between switching speed and drive loss in conventional direct-connection schemes.

[0040] When V_DRV is low, Q4 is off, Q5 is on, and the charge stored in the gate of Q6 is quickly discharged to the drive reference ground through Q5, causing Q6 to turn off quickly.

[0041] In particular, under the high dv / dt conditions of a high-voltage three-phase system, the parallel network of R24 and C13 exhibits excellent anti-interference performance: when the high dv / dt generated by the power device's turn-off couples interference charge to the gate through the Miller capacitance (Cgd), C13 responds immediately with its low-frequency impedance characteristics, providing a low-impedance discharge path for the charge through the base of Q5, while R24 provides the necessary damping effect to suppress LC oscillation. This synergistic mechanism of "fast bypass + oscillation suppression" effectively absorbs the Miller current attempting to raise the gate potential, preventing the power switch from being mis-turned on, and significantly improving the reliability of operation under high-frequency, high-voltage three-phase cross-interference environments. At the same time, because C13 accelerates the turn-on speed of Q5, it ensures that the gate potential is quickly clamped to a low level, further optimizing the immunity to interference during the turn-off process.

[0042] This push-pull structure, which introduces a parallel network of R24 and C13 at the base of the totem pole, provides a low-impedance drive source without increasing circuit complexity, ensuring fast switching of Q6 and reducing switching losses.

[0043] Figure 2Taking Q16 in the upper arm IGBT of phase B as an example, the push-pull drive circuit consists of an NPN transistor Q13, a PNP transistor Q14, a base current limiting resistor R21, and an accelerating capacitor C19. The emitters of Q13 and Q14 are connected together as the output of the drive signal, directly connected to the gate (G) of the Q16 to be driven. The collector of Q13 is connected to the output of the voltage regulator circuit (Vout, i.e., the positive terminal of C7), and the collector of Q14 is connected to the drive reference ground (GND_DRV, i.e., the source of Q16). The drive control signal V_DRV generated by the external controller (usually a logic level of 0V and 5V or 3.3V) is applied to the bases of Q13 and Q14 through the parallel network of R21 and C19. Its working principle is similar to... Figure 1 The push-pull drive circuit is exactly the same as that in the previous one, so it will not be described in detail here.

[0044] In summary, this invention proposes a drive circuit for power switching devices in three-phase systems, particularly suitable for insulated-gate bipolar transistors (IGBTs) or metal-oxide-semiconductor field-effect transistors (MOSFETs) in three-phase AC systems (such as three-phase motor drives, three-phase inverters, frequency converters, etc.). By directly drawing power from the three-phase power supply and generating a stable DC voltage through a capacitor voltage divider and regulator circuit, efficient and reliable driving of power switching devices (such as IGBTs or MOSFETs) is achieved. This invention overcomes the limitations of traditional drive circuits that rely on bulky isolation transformers or complex switching power supplies, and has advantages such as simple structure, low cost, and easy integration. It is suitable for applications such as industrial drives, new energy power generation, and power conversion. Compared with existing technologies, this invention has the following significant advantages:

[0045] Simplified structure and reduced cost: It completely eliminates the bulky isolation transformer and expensive dedicated switching power supply chips or modules, and only uses common passive and active components such as capacitors, diodes, transistors and Zener diodes, which greatly simplifies the circuit structure and reduces material cost (BOM cost) and PCB area.

[0046] High reliability: Due to the simple circuit structure and the use of mature and reliable conventional components, the potential failure points of the system are reduced, which helps to improve the overall reliability of the drive circuit.

[0047] High-efficiency power extraction: It cleverly utilizes the phase difference of the three-phase system itself to obtain energy directly from the main power circuit through capacitors, resulting in a short energy conversion path and high efficiency.

[0048] Excellent driving performance: By adding a voltage regulator circuit with a compensation capacitor, the driving voltage instability caused by three-phase power supply fluctuations and load changes is effectively suppressed, ensuring the reliability of the drive; by integrating a base current limiting resistor and an accelerating capacitor into a push-pull drive circuit, not only is low-impedance driving capability provided, ensuring fast switching of power devices to reduce switching losses, but also significantly enhancing the anti-interference capability and the smoothness of the switching process in high dv / dt operating environments.

[0049] Easy to implement and integrate: The solution has a clear principle and simple circuit, making it very easy to lay out and integrate on existing three-phase power boards. It is particularly suitable for application scenarios with high requirements for cost, size and reliability.

[0050] Those skilled in the art will understand that embodiments of this application can be provided as methods, systems, or computer program products. Therefore, this application can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, this application can take the form of a computer program product embodied on one or more computer-readable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code. This application is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of this application. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create a machine for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to operate in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The functions specified in one or more boxes. These computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable apparatus for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0051] The above description is merely a preferred embodiment of the present invention. The scope of protection of the present invention is not limited to the above embodiments. All technical solutions falling within the scope of the present invention's concept are within the scope of protection of the present invention. It should be noted that for those skilled in the art, any improvements and modifications made without departing from the principles of the present invention should also be considered within the scope of protection of the present invention.

Claims

1. A drive circuit for power switching devices in a three-phase system, characterized in that, The three-phase system includes power switch groups corresponding to each phase. Each power switch group includes an upper bridge arm power switch and a lower bridge arm power switch. The drive circuit corresponds to the upper bridge arm power switch and includes a capacitor voltage divider circuit, a voltage regulator circuit, and a push-pull drive circuit. The capacitor voltage divider circuit is connected to the two phases other than the corresponding phase. The output of the capacitor voltage divider circuit is connected to the upper bridge arm power switch of the corresponding phase in sequence through the corresponding voltage regulator circuit and the push-pull drive circuit, so as to directly draw power from the three-phase power supply and generate a stable DC voltage to reliably drive the power switch devices. The capacitor voltage divider circuit includes a first isolation capacitor, a second isolation capacitor, a first diode, a second diode, and a filter capacitor. The anode of the first diode is connected to one of the two phases other than the corresponding phase through the first isolation capacitor. The anode of the second diode is connected to the other phase other than the corresponding phase through the second isolation capacitor. The cathodes of the first diode and the second diode are both connected to the drive reference ground of the upper bridge arm power switch of the corresponding phase through the filter capacitor. The positive and negative terminals of the filter capacitor are respectively connected to the positive and negative terminals of the output of the capacitor voltage divider circuit and connected to the corresponding voltage regulator circuit.

2. The drive circuit for a three-phase system power switching device according to claim 1, characterized in that, The upper bridge arm power switch adopts a MOSFET switch or a pair of anti-parallel IGBTs. When the upper bridge arm power switch adopts a MOSFET switch, the cathodes of the first diode and the second diode are both connected to the source of the corresponding phase MOSFET switch through a filter capacitor. When the upper bridge arm power switch adopts a pair of anti-parallel IGBTs, the driving circuit corresponds one-to-one with the IGBT, and the cathodes of the first diode and the second diode are both connected to the emitter of the corresponding phase IGBT through a filter capacitor.

3. The drive circuit for a three-phase system power switching device according to claim 1, characterized in that, The voltage regulator circuit includes a first current-limiting resistor, a second current-limiting resistor, a transistor, a Zener diode, a compensation capacitor, and an output capacitor. The positive output terminal of the capacitor voltage divider circuit is connected to the collector of the transistor through the first current-limiting resistor. The positive output terminal of the capacitor voltage divider circuit is connected to the base of the transistor through the second current-limiting resistor. The emitter of the transistor is connected to the positive terminal of the output capacitor. The base of the transistor is also connected to the cathode of the Zener diode. The compensation capacitor is connected between the base of the transistor and the positive terminal of the output capacitor. The anode of the Zener diode is connected to the drive reference ground of the upper bridge arm power switch of the corresponding phase. The positive and negative terminals of the output capacitor are respectively connected to the positive and negative output terminals of the voltage regulator circuit and connected to the corresponding push-pull drive circuit.

4. The drive circuit for a three-phase system power switching device according to claim 3, characterized in that, The upper bridge arm power switch is a MOSFET switch or a pair of anti-parallel IGBTs. When the upper bridge arm power switch is a MOSFET switch, the anode of the Zener diode is connected to the source of the corresponding phase MOSFET switch. When the upper bridge arm power switch is a pair of anti-parallel IGBTs, the drive circuit corresponds one-to-one with the IGBT, and the anode of the Zener diode is connected to the emitter of the corresponding phase IGBT.

5. The drive circuit for a three-phase system power switching device according to claim 1, characterized in that, The push-pull drive circuit includes a first transistor and a second transistor, as well as a base current-limiting resistor and an accelerating capacitor connected in parallel. The bases of the first transistor and the second transistor are connected to an external drive control signal through the parallel base current-limiting resistor and the accelerating capacitor. The collector of the first transistor is connected to the positive terminal of the output of the voltage regulator circuit. The collector of the second transistor is connected to the drive reference ground of the upper bridge arm power switch of the corresponding phase. The emitters of the first transistor and the second transistor form a push-pull output terminal connected to the controlled terminal of the upper bridge arm power switch of the corresponding phase.

6. The drive circuit for a three-phase system power switching device according to claim 5, characterized in that, The upper bridge power switch uses a MOSFET switch or a pair of anti-parallel IGBTs. When the upper bridge power switch uses a MOSFET switch, the collector of the second transistor is connected to the source of the corresponding phase MOSFET switch, and the emitters of the first and second transistors form a push-pull output terminal connected to the gate of the corresponding phase MOSFET switch. When the upper bridge power switch uses a pair of anti-parallel IGBTs, the driving circuit corresponds one-to-one with the IGBTs, the collector of the second transistor is connected to the emitter of the corresponding phase IGBT, and the emitters of the first and second transistors form a push-pull output terminal connected to the gate of the corresponding phase IGBT.

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