Auxiliary circuit and power module

Abstract

This application discloses an auxiliary power supply circuit and a power module. The circuit includes an input power unit, an output power unit, a power supply unit, a control unit, and a transformer. The transformer includes a first primary winding, a second primary winding, a third primary winding, and a secondary winding. The first and second primary windings are electrically connected to the input power unit. The secondary winding is electrically connected to the output power unit. The third primary winding is sequentially electrically connected to the power supply unit and the control unit. The power supply unit includes an inductor component located on the connection path between the third primary winding and the control unit. By introducing an inductor component, this application optimizes the energy distribution ratio, enabling faster, more stable, and more reliable short-circuit protection response.

Description

Technical Field

[0001] This application belongs to the field of power electronics technology, specifically relating to an auxiliary power source circuit and a power module. Background Technology

[0002] In existing short-circuit protection schemes for auxiliary power transformers, power is typically supplied to the control chip via rectification and a series current-limiting resistor through the VCC winding (N4). This current-limiting resistor limits the energy entering the VCC capacitor during a short circuit, achieving a "hiccup-type" restart protection. This scheme also relies on the difference in leakage inductance between the transformer windings (N3 and N4), using a leakage inductance distribution mechanism to rapidly reduce the VCC voltage to the turn-off threshold during a short circuit. However, this scheme has two problems: first, the parameters of the current-limiting resistor are contradictory; if the resistance is too small, the protection is difficult to trigger, while if it is too large, it will affect the power supply stability of the chip under normal load; second, the winding leakage inductance consistency is poor, and fluctuations in manufacturing processes lead to uncontrollable energy distribution, resulting in unstable protection performance. Utility Model Content

[0003] To address the shortcomings of existing technologies, the main objective of this application is to provide an auxiliary power supply circuit and power module. By introducing an inductor component to optimize the energy distribution ratio, this application enables faster short-circuit protection response and more stable and reliable triggering.

[0004] To achieve the above objectives, this application provides the following technical solution:

[0005] An auxiliary power supply circuit includes: an input power unit, an output power unit, a power supply unit, a control unit, and a transformer. The transformer includes a first primary winding, a second primary winding, a third primary winding, and a secondary winding. The first and second primary windings are electrically connected to the input power unit. The secondary winding is electrically connected to the output power unit. The third primary winding is sequentially electrically connected to the power supply unit and the control unit. The power supply unit includes an inductor component located on the connection path between the third primary winding and the control unit.

[0006] Optionally, the input power unit includes: a first capacitor, a second capacitor, a first power switch, a second power switch, a first diode, a second diode, a current transformer, and a sensing resistor. The first terminal of the first capacitor is connected to the first terminal of the first primary winding of the transformer, and the second terminal of the first capacitor is connected to a first ground terminal via the second capacitor. The anode of the first diode is connected to the second terminal of the first primary winding of the transformer, and the cathode of the first diode is connected to the drain of the first power switch. The gate of the first power switch serves as the first input control terminal of the input power unit. The source of the first power switch is connected to the connection point of the first capacitor and the second capacitor via the sensing resistor. The first terminal of the current transformer is connected to the first terminal of the second primary winding of the transformer, and the second terminal of the current transformer is connected to the connection point of the first capacitor and the second capacitor. The drain of the second power switch is connected to the second terminal of the second primary winding of the transformer, the source of the second power switch is connected to the anode of the second diode, the cathode of the second diode is connected to the first ground terminal, and the gate of the second power switch serves as the second input control terminal of the input power unit.

[0007] Optionally, the output power unit includes: a third diode, a third capacitor, and an energy absorption resistor, wherein the anode of the third diode is connected to the first end of the secondary winding of the transformer, and the cathode of the third diode is connected to the first end of the energy absorption resistor; the second end of the energy absorption resistor is connected to the second end of the secondary winding of the transformer; the third capacitor is connected in parallel across the two ends of the energy absorption resistor, and one end of the third capacitor connected to the second end of the energy absorption resistor is connected to a third ground terminal.

[0008] Optionally, the power supply unit further includes: a fourth capacitor, a current-limiting resistor, and a fourth diode, wherein the first end of the inductor is connected to the first end of the third primary winding of the transformer, and the second end of the inductor is connected to the anode of the fourth diode; the cathode of the fourth diode is connected to the power input terminal of the control unit through the current-limiting resistor; the first end of the fourth capacitor is connected to the connection point between the current-limiting resistor and the power input terminal of the control unit, and the second end of the fourth capacitor is connected to the connection point between the second end of the third primary winding and the ground terminal of the control unit, and the second end of the fourth capacitor is connected to the second ground terminal.

[0009] Optionally, the first end of the third primary winding of the transformer is connected to the anode of the fourth diode, and the cathode of the fourth diode is connected to the current-limiting resistor through the inductor assembly.

[0010] Optionally, the first end of the third primary winding is connected to the first end of the inductor assembly in sequence through the fourth diode and the current-limiting resistor, and the second end of the inductor assembly is connected to the power input terminal of the control unit.

[0011] Optionally, the second end of the third primary winding is connected to the ground terminal of the control unit via the inductor assembly.

[0012] Optionally, the control unit is a control chip, wherein the drive output terminal of the control chip is connected to a drive unit.

[0013] Optionally, the driving unit uses a power MOSFET driving chip, with the first output control terminal of the power MOSFET driving chip connected to the first input control terminal of the input power unit, and the second output control terminal of the power MOSFET driving chip connected to the second input control terminal of the input power unit.

[0014] This application also provides a power module, which includes an AC-DC conversion unit, a DC-DC conversion unit, an EMC unit, and an auxiliary power circuit as described above.

[0015] Compared with the prior art, this application can bring the following beneficial effects:

[0016] This application introduces a ferrite bead into the traditional auxiliary power transformer short-circuit protection circuit, and superimposes it with the leakage inductance of the VCC winding to significantly optimize the energy distribution ratio during a short circuit, improve the sensitivity and response speed of the control chip undervoltage trigger, and thus enhance the reliability and consistency of hiccup-type protection. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the circuit structure of an auxiliary power source circuit provided in one embodiment of this application;

[0018] Figure 2 This is a schematic diagram of the circuit structure of an auxiliary power source circuit provided in another embodiment of this application;

[0019] Figure 3 This is a schematic diagram of the circuit structure of an auxiliary power source circuit provided in another embodiment of this application;

[0020] Figure 4 This is a schematic diagram of the circuit structure of an auxiliary power source circuit provided in another embodiment of this application;

[0021] Figure 5 This is a schematic diagram of the circuit structure of a power module provided in another embodiment of this application. Detailed Implementation

[0022] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0023] It should be noted that all directional indications (such as up, down, left, right, front, back, etc.) in the embodiments of the present invention are only used to explain the relative positional relationship and movement of each component in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indication will also change accordingly.

[0024] In this invention, unless otherwise explicitly specified and limited, the terms "connection," "fixed," etc., should be interpreted broadly. For example, "fixed" can mean a fixed connection, a detachable connection, or an integral part; it can mean a mechanical connection or an electrical connection; it can mean a direct connection or an indirect connection through an intermediate medium; it can mean the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0025] Furthermore, if the embodiments of this invention involve descriptions such as "first" or "second," these descriptions are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include at least one of those features. Additionally, the meaning of "and / or" throughout the text includes three parallel solutions; for example, "A and / or B" includes solution A, solution B, or a solution where both A and B are satisfied simultaneously. Furthermore, the technical solutions of the various embodiments can be combined with each other, but this must be based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or impossible to implement, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed by this invention.

[0026] Figure 1 This is a schematic diagram of the circuit structure of an auxiliary power source circuit provided in an exemplary embodiment of this application, as shown below. Figure 1The circuit includes an input power unit 1, an output power unit 2, a power supply unit 3, a control unit 4, and a transformer 6. The transformer includes a first primary winding N1, a second primary winding N2, a third primary winding N4, and a secondary winding N3. The first primary winding N1 and the second primary winding N2 are electrically connected to the input power unit 1. The secondary winding N3 is electrically connected to the output power unit 2. The third primary winding N4 is sequentially electrically connected to the power supply unit 3 and the control unit 4. The power supply unit 3 includes an inductor component L1 (e.g., a ferrite bead), which is located on the connection path between the third primary winding N4 and the control unit 4.

[0027] In this embodiment, the introduction of inductor component L1 optimizes the energy distribution and electromagnetic compatibility of the auxiliary power supply circuit. This circuit structure effectively ensures efficient energy transfer between input power unit 1 and output power unit 2 through the magnetic coupling between the primary and secondary windings of the transformer, and provides a stable DC power supply to control unit 4 via power supply unit 3. Simultaneously, the introduction of inductor component L1 effectively suppresses high-frequency interference, helps improve the response speed and stability of the short-circuit protection mechanism, thereby enhancing the overall performance and reliability of the auxiliary power supply circuit.

[0028] In another exemplary embodiment, the input power unit 1 includes a first capacitor C1, a second capacitor C2, a first power switch Q1, a second power switch Q2, a first diode D1, a second diode D2, a current transformer CT, and a sensing resistor Rsense. The first terminal of the first capacitor C1 is connected to the first terminal of the first primary winding N1 of the transformer, and the second terminal of the first capacitor C1 is connected to the first ground terminal GND1 via the second capacitor C2. The anode of the first diode D1 is connected to the second terminal of the first primary winding N1 of the transformer, and the cathode of the first diode D1 is connected to the drain of the first power switch Q1. The gate of the first power switch Q1 serves as the first control gate of the input power unit 1. In the control terminal, the source of the first power switch Q1 is connected to the connection point of the first capacitor C1 and the second capacitor C2 through the sensing resistor Rsense; the first terminal of the current transformer CT is connected to the first terminal of the second primary winding N2 of the transformer, and the second terminal of the current transformer CT is connected to the connection point of the first capacitor C1 and the second capacitor C2; the drain of the second power switch Q2 is connected to the second terminal of the second primary winding N2 of the transformer, the source of the second power switch Q2 is connected to the anode of the second diode D2, the cathode of the second diode D2 is connected to the first ground terminal GND1, and the gate of the second power switch Q2 serves as the second control terminal of the input power unit 1.

[0029] In this embodiment, the input power unit 1 controls the conduction and discontinuity of the current in the first primary winding N1 and the second primary winding N2 of the transformer through two power switches Q1 and Q2 to achieve periodic energy transfer. The first primary winding N1, together with the first capacitor C1 and the second capacitor C2, forms a resonant branch responsible for guiding the stored current into the primary winding of the transformer when the first power switch Q1 is on. After the first power switch Q1 is off, the current recovers the remaining energy through the freewheeling circuit of the first diode D1. The second primary winding N2 forms a closed loop with the current transformer CT and ground, undertaking the symmetrical conduction and freewheeling process during the conduction of the second power switch Q2, forming a full-bridge or symmetrical half-bridge excitation mode. The drive unit 5 controls the gates of the first power switch Q1 and the second power switch Q2 respectively, making them conduct in a complementary manner, thereby forming alternating magnetic flux excitation, which helps to improve the utilization rate of the transformer's magnetic flux and the efficiency of power transmission. In addition, the sensing resistor Rsense is responsible for real-time monitoring of the branch current of the first power switch Q1. By sensing changes in the branch current, Rsense provides feedback information to the control unit, helping to determine whether the current exceeds the preset safety range. When the current reaches or exceeds the overcurrent threshold, Rsense triggers the overcurrent protection mechanism to protect the circuit from damage. Furthermore, real-time current monitoring also supports precise feedback control by the control unit, ensuring stable operation of the circuit under normal working conditions and preventing equipment damage or system failure due to abnormal current.

[0030] In summary, the input power unit 1 avoids unilateral overheating through distributed dual-winding excitation, and enhances the closed-loop control accuracy of the system by combining CT current detection, thereby improving short-circuit protection and dynamic response capabilities. It has technical advantages such as symmetrical structure, high energy recovery efficiency, and reliable protection.

[0031] In another exemplary embodiment, the output power unit 2 includes a third diode D3, a third capacitor C3, and an energy absorption resistor R0. The anode of the third diode D3 is connected to the first terminal of the secondary winding N3 of the transformer, the cathode of the third diode D3 is connected to the first terminal of the energy absorption resistor R0, the second terminal of the energy absorption resistor R0 is connected to the second terminal of the secondary winding N3 of the transformer, the third capacitor C3 is connected in parallel across the two terminals of the energy absorption resistor R0, and the end of the third capacitor C3 connected to the second terminal of the energy absorption resistor R0 is connected to the third ground terminal GND3.

[0032] In this embodiment, the output power unit 2 is mainly used to rectify, filter, and absorb overvoltage from the secondary side of the transformer. The secondary winding N3, as the output winding of the transformer's secondary side, generates an induced voltage under the excitation of the primary winding. This voltage is then unidirectionally conducted through the third diode D3, thereby rectifying the electrical energy. The rectified energy then flows to a parallel branch consisting of an energy absorption resistor R0 and a third capacitor C3. The energy absorption resistor R0, as a resistive load, absorbs electrical energy and dissipates it as heat, thus preventing excessive energy from impacting subsequent circuits. Simultaneously, the third capacitor C3, connected in parallel across the energy absorption resistor R0, acts as a filter to smooth the rectified voltage, suppressing voltage spikes and improving the stability of the output voltage and electromagnetic interference (EMC) performance.

[0033] In summary, the output power unit 2 has the functions of clamping, filtering and denoising output overvoltage, and stabilizing voltage, which can provide stable and safe secondary power output for the overall power module, and help improve the reliability and anti-interference capability of the overall power module.

[0034] In another exemplary embodiment, such as Figure 1 As shown, the power supply unit 3 further includes a fourth capacitor C4, a current-limiting resistor R1, and a fourth diode D4. The first end of the inductor assembly L1 is connected to the first end of the third primary winding N4 of the transformer. The second end of the inductor assembly L1 is connected to the anode of the fourth diode D4. The cathode of the fourth diode D4 is connected to the power input terminal of the control unit 4 through the current-limiting resistor R1. The first end of the fourth capacitor C4 is connected to the connection point between the current-limiting resistor R1 and the power input terminal of the control unit 4. The second end of the fourth capacitor C4 is connected to the connection point between the second end of the third primary winding N4 and the ground terminal of the control unit 4. The second end of the fourth capacitor C4 is also connected to the second ground terminal GND2.

[0035] In this embodiment, the power supply unit 3 obtains electrical energy from the third primary winding N4 of the transformer to provide a stable and reliable DC operating voltage for the control unit 4. First, the third primary winding N4 induces AC power and connects its first terminal to the anode of the fourth diode D4 via the inductor assembly L1. The fourth diode D4 rectifies the AC induced voltage into a unidirectional pulsating DC current. Next, the rectified DC current enters the power input pin VCC of the control unit 4 through the current-limiting resistor R1. The current-limiting resistor R1 can limit the DC current flowing into the fourth capacitor C4 and the control unit during power-on or in case of abnormalities such as short circuits, thereby preventing damage to the control unit due to excessive instantaneous DC current. Subsequently, the DC current is filtered and regulated by the fourth capacitor C4 to ensure a stable power supply to the control unit. Meanwhile, by introducing inductor component L1, this application provides inductive impedance at high frequencies, effectively suppressing electromagnetic interference (EMI). Thus, by reducing the transmission of high-frequency noise, inductor component L1 mitigates uneven power distribution caused by inconsistent winding leakage inductance, ensuring a more stable and rapid triggering of the short-circuit protection mechanism. Furthermore, the inductive characteristics of inductor component L1 facilitate coordinated operation with current-limiting resistor R1, improving situations where improper parameter settings of current-limiting resistor R1 could lead to delayed protection response or unstable power supply. This reduces the impact of interference signals on the power supply system, thereby improving the purity of the supply voltage.

[0036] In summary, the power supply unit 3, through rectification, current limiting, filtering, and EMI filtering, can effectively cooperate with the control unit 5 to achieve hiccup-type protection in the event of abnormalities such as short circuits. At the same time, by introducing the inductor component L1, it can optimize power transmission and reduce high-frequency interference, thereby improving the stability and reliability of the power supply system.

[0037] In another exemplary embodiment, this application also provides a power supply unit 3, such as... Figure 2 As shown, unlike the previous embodiment, in the power supply unit 3 described in this embodiment, the inductor component L1 is located between the fourth diode D4 and the current limiting resistor R1. That is, the first end of the third primary winding N4 of the transformer is connected to the anode of the fourth diode D4, and the cathode of the fourth diode D4 is connected to the current limiting resistor R1 through the inductor component L1.

[0038] In this embodiment, the position of inductor component L1 is adjusted to be located between the fourth diode D4 and the current-limiting resistor R1, that is, it is moved from the rectification front end to the rectification back end. This structural adjustment optimizes the timeliness and effectiveness of electromagnetic interference (EMI) suppression. Specifically, since the output of the fourth diode D4 is a pulsating DC signal, which contains a large number of high-frequency components, placing inductor component L1 here can more directly suppress these high-frequency pulses, reducing the possibility of them entering the power input terminal VCC of the control unit, thereby improving the electromagnetic compatibility (EMC) performance of the overall circuit. In addition, this arrangement can improve the suppression efficiency of spike noise and high-frequency interference without changing the energy transfer characteristics of the main power supply path, and also helps to protect the current-limiting resistor R1 and the control chip from high-frequency interference, improving the stability and reliability of the overall circuit.

[0039] In another exemplary embodiment, this application also provides a power supply unit 3, such as... Figure 3 As shown, unlike the two embodiments described above, in the power supply unit 3 described in this embodiment, the inductor component L1 is located between the current limiting resistor R1 and the power input terminal of the control unit 4. That is, the first end of the third primary winding N4 is connected to the first end of the inductor component L1 in sequence through the fourth diode D4 and the current limiting resistor R1, and the second end of the inductor component L1 is connected to the power input terminal of the control unit 4.

[0040] In this embodiment, the inductor component L1 is positioned between the current-limiting resistor R1 and the power input terminal of the control unit 4 (i.e., the VCC pin of the control chip), forming the final stage of power filtering barrier. The main function of this positioning adjustment is to further suppress residual high-frequency noise and spike pulse signals after rectification and current limiting, before entering the control unit 4, ensuring a cleaner and more stable voltage supplied to the control unit 4. Compared to the aforementioned placement of the inductor component L1 before or after rectification, this arrangement uses the inductor component L1 as a local filter component close to the sensitive load (i.e., the control unit 4 chip), maximizing the isolation of radio frequency interference (RFI) and electromagnetic interference (EMI) that may enter from the power input terminal of the control unit 4, thereby significantly improving the immunity and reliability of the control unit 4 in high-frequency interference environments. Furthermore, this layout, without affecting normal power supply, can also improve the voltage judgment accuracy and trigger stability of the control unit 4 under short-circuit protection, hiccup start, and other operating states, representing a refined EMC design optimization scheme that emphasizes the purification effect of the control chip port.

[0041] In another exemplary embodiment, this application also provides a power supply unit, such as... Figure 4As shown, unlike the three embodiments described above, in the power supply unit 3 described in this embodiment, the inductor component L1 is located between the second end of the third primary winding N4 and the ground terminal GND of the control unit 4, that is, the second end of the third primary winding N4 is connected to the ground terminal of the control unit 4 via the inductor component L1.

[0042] In this embodiment, the inductor component L1 is positioned between the second end of the third primary winding N4 and the ground terminal GND of the control unit 4, acting within the grounding path of the power supply circuit. The main purpose of this arrangement is to suppress high-frequency noise and common-mode interference conducted into the control chip via the ground wire, enhancing the system's ability to suppress electromagnetic interference (EMI), particularly ground interference. In practical operation, the ground terminal of the control unit 4 serves as a reference potential, crucial for the stability of its power supply voltage and the accuracy of its control logic. High-frequency interference in the grounding path can cause reference drift or mis-triggered activation within the control unit 4. By connecting the inductor component L1 in series in the grounding circuit of the control unit 4, high-frequency interference from winding or switching transients can be effectively isolated, reducing the high-frequency coupling effect between the power ground and signal ground, and improving the anti-interference performance and accuracy of logic judgments of the control unit. Furthermore, this structure can also help improve the system's common-mode EMI performance, making it suitable for applications with high requirements for power supply stability and electromagnetic compatibility. It represents a refined electromagnetic compatibility optimization design emphasizing "ground noise isolation."

[0043] It should be noted that the different arrangements of the inductor component L1 provided in this application are optimized for different positions in the power supply path and can be flexibly selected according to specific application scenarios to improve the electromagnetic compatibility and control reliability of the overall circuit. For example, when the inductor component L1 is arranged between the third primary winding N4 of the transformer and the rectifier diode D4 (… Figure 1 When placed after rectification and before current-limiting resistor R1, it is mainly used to suppress high-frequency spikes generated at the transformer excitation end from the source, and is suitable for situations where the transformer leakage inductance is large and interference is strong; Figure 2 This effectively filters out high-frequency components in the rectified pulse, making it suitable for environments dominated by diode switching noise; when the inductor component L1 is located between the current-limiting resistor R1 and the power input terminal of the control unit 4 ( Figure 3 When this is done, the power supply port voltage can be purified to the maximum extent, ensuring stable operation of the control unit. This is particularly suitable for high-precision applications where the controller is sensitive to power supply voltage noise. Furthermore, the inductor component L1 is positioned between the auxiliary winding ground terminal and the control unit 4 ground terminal GND. Figure 4 This helps to isolate ground wire conducted interference and suppress the influence of common-mode noise, making it suitable for application environments where the ground wire is floating or ground bounce is significant.

[0044] In summary, different arrangements of the inductor component L1 have their own focuses. They can be used individually or in combination depending on the location of the interference source, the sensitive path of the system, and EMI test feedback, thereby achieving dual protection of high reliability and electromagnetic compatibility of the power supply system.

[0045] It should be further explained that, in this application, the introduction of inductor component L1 serves not only as a high-frequency EMI suppression device, but also through its own equivalent inductance Leakage inductance of VCC winding (N4) They jointly participate in the regulation and optimization of the system's energy distribution process.

[0046] In the traditional scheme, the number of turns in the transformer VCC winding is N4, and its leakage inductance is... The main power output winding has N3 turns and a leakage inductance of [value missing]. The leakage inductance values ​​of the transformer VCC winding and the main power output winding are normalized according to their respective number of turns as follows:

[0047]

[0048]

[0049] and The ratio between them determines the instantaneous distribution of input energy among the windings during a short circuit, and is usually expressed as a proportionality coefficient. This indicates that when an output short circuit occurs, if... If the voltage is too low, too much energy may be concentrated and transmitted to the VCC winding side, which may cause the protection action to be slow or the VCC power to be cut off in time.

[0050] Therefore, this application introduces an inductor component L1 in the N4 power supply path, whose equivalent inductance is Magnetic bead inductance Leakage inductance of VCC winding The sum, normalized again with respect to the number of turns N4 of the VCC winding, is expressed as:

[0051]

[0052] This results in an improved proportionality coefficient. Then we have:

[0053]

[0054] because Since it is a positive value, therefore we have This means that the energy absorption ratio of the VCC winding during a short circuit can be reduced, causing the VCC voltage to drop faster under abnormal conditions. This helps the control chip to quickly enter undervoltage protection or hiccup restart, thereby improving the response speed and reliability of short circuit protection.

[0055] In practical design, to facilitate parameter configuration and debugging, the inductance of the magnetic bead is... Leakage inductance of N4 winding can be used as a reference. The ratio is set, that is, by introducing a coefficient. , making ,in, To design an adjustable factor, any value between 20% and 300% can generally be selected. Typical values ​​are 20%, 40%, 60%, 80%, 100%, 200%, and 300%. Simultaneously, the feasibility of the components must be considered, or multiple magnetic beads may be connected in series or parallel. The specific value can be determined based on the adjustment and testing results. The values ​​are not limited to those mentioned above and can be further increased depending on the specific circumstances. In actual projects, transformers processed on a small-batch production line can be selected for short-circuit testing and verification with external ferrite beads. The number of transformers should be 10 to 30 pieces. After the short-circuit effect is determined through testing, the maximum value of the external ferrite bead inductance in each experiment should be selected. Considering the tolerance of the ferrite bead inductance, a margin of about 10% to 30% should be appropriately reserved for the selected parameters. The values ​​should not be too large.

[0056] In another exemplary embodiment, the control unit 4 employs a control chip (e.g., UC3842 or UC3843), wherein the drive output terminal DRV of the control chip is connected to the input control terminal of the drive unit 5.

[0057] In this embodiment, the control principle of the control chip is as follows: When the power supply pin VCC of the control chip obtains a stable operating voltage (usually 12V or 15V) through the power supply unit, the control chip starts up. The internal oscillator generates a PWM clock with a fixed frequency (typically 100kHz for UC3842). This clock signal works in conjunction with the error amplifier and current comparator inside the control chip. First, the error amplifier of the control chip receives external feedback voltage (such as voltage divider feedback from the output voltage) and compares it with the internal reference voltage, outputting an error signal. Second, the control chip samples the current during the conduction of the switching transistor (usually connected to the current sensing resistor Rsense) and inputs it to the current comparator, comparing it with the error signal to determine the PWM conduction time. The comparison result determines the duration of the high and low levels output by the chip's drive output pin DRV, thereby controlling the drive unit 5 to send an on or off signal to the power MOSFET (such as Q1 or Q2) to complete the switching control.

[0058] In summary, by monitoring the output voltage feedback and current information, the control chip adjusts the duty cycle of the PWM signal output by the DRV drive output pin, thereby achieving precise control and fault protection of the power switch. This not only ensures the stable drive of the transformer but also improves the voltage regulation performance and reliability of the entire power supply system.

[0059] In another exemplary embodiment, the driving unit 5 employs a power MOSFET driving chip (e.g., IR2110 or IR2113), the first output control terminal (e.g., HO pin, High-SideOutput) of the power MOSFET driving chip is connected to the first input control terminal of the input power unit 1, and the second output control terminal (e.g., LO pin, Low-Side Output) of the power MOSFET driving chip is connected to the second input control terminal of the input power unit 1.

[0060] In this embodiment, when the control chip generates a modulated PWM pulse signal through its internal oscillator and feedback control logic, the signal is output from the DRV pin and sent to the input control terminal of the driver chip. The driver chip, acting as an intermediate stage, has a stronger current-driving capability. After receiving the control signal, it amplifies it into a gate signal with high voltage swing and high current driving capability, and outputs it to the gates of the first power switch Q1 and the second power switch Q2, quickly turning them on or off.

[0061] During the conduction period of the first power switch Q1 and the second power switch Q2 (when the driver chip outputs a high level), the primary circuit of the transformer is turned on, the current rises, and energy is transferred to the secondary side. During the turn-off period of the first power switch Q1 and the second power switch Q2 (when the driver chip outputs a low level), the circuit is disconnected, the primary energy storage is released, or the system enters freewheeling mode. Through this control method, the width of the PWM pulse directly determines the MOSFET conduction time, thereby controlling the regulation of output power and voltage.

[0062] Furthermore, driver chips typically possess features such as rising / falling edge enhancement characteristics, dead-time control, and voltage clamping protection, effectively suppressing voltage ringing and cross-conduction during the switching process of the first power switch Q1 and the second power switch Q2, thereby improving switching efficiency and system stability. Therefore, this control architecture combines the modulation capability of the control chip with the high-speed, powerful driving capability of the driver chip, achieving efficient and safe driving of power devices. It is a standard control scheme for modern high-frequency switching power supplies and isolation conversion systems.

[0063] In another exemplary embodiment, this application also provides a power module, such as Figure 5 As shown, the power module includes an input EMC unit, an AC / DC conversion unit, a DC / DC conversion unit, a rectifier output unit, and an output EMC unit connected in sequence, as well as an auxiliary power supply circuit as described in any of the previous embodiments. The auxiliary power supply circuit is used to provide a specified voltage power supply to the control circuits of the AC / DC conversion unit and the DC / DC conversion unit, and the drive circuits of the switching devices.

[0064] In this embodiment, in the power module, the auxiliary power supply circuit provides a specified power supply to the control circuit of the AC / DC conversion unit, the DC / DC conversion unit, and the drive circuit of the switching devices. This not only ensures the normal startup and operation of each functional unit, but also improves the performance and reliability of the power module in terms of short-circuit protection, startup stability, and electromagnetic compatibility by optimizing energy distribution and suppressing high-frequency interference through the inductor component.

[0065] Furthermore, it should be emphasized that this application does not involve protection of the circuit structure of the input EMC unit, AC / DC conversion unit, DC / DC conversion unit, rectifier output unit, and output EMC unit. These units are all prior art. For example, the input EMC unit can use the LCSC EMC filter series, such as the MI-24-10. The AC / DC conversion unit can use the MeanWell LRS-350 series. The DC / DC conversion unit can use the Texas Instruments LM2675 series. The rectifier output unit can use the 1N5408 rectifier diode. The output EMC unit can use the Wurth Electronics 744-8400.

[0066] Furthermore, the power module, as an AC / DC power conversion module, is widely used in new energy vehicle charging equipment, undertaking the crucial task of converting alternating current (AC) to direct current (DC). During the charging process of new energy vehicles, the AC power input typically comes from the power grid, while the vehicle battery requires a stable DC power supply for charging. The power module, through an efficient conversion process, ensures that the charging equipment can convert the AC power from the power grid into DC power suitable for battery charging, while maintaining the stability of current and voltage during the charging process. The power module integrates multiple circuit units, including input EMC filtering, AC / DC conversion, DC / DC conversion, rectification, and output EMC, effectively suppressing electromagnetic interference (EMI), improving the system's power conversion efficiency, and ensuring safety and stability during the charging process. In addition, while meeting the high power and high efficiency requirements of new energy vehicle charging equipment, the power module also features a compact size and high reliability, enabling it to adapt to various complex working environments.

[0067] The above descriptions are merely optional examples of this application and are not intended to limit this application. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. An auxiliary power source circuit, characterized in that, The circuit includes: Input power unit, output power unit, power supply unit, control unit, and transformer. in, The transformer includes a first primary winding, a second primary winding, a third primary winding, and a secondary winding; The first primary winding and the second primary winding are electrically connected to the input power unit; The secondary winding is electrically connected to the output power unit; The third primary winding is electrically connected in sequence to the power supply unit and the control unit. The power supply unit includes an inductor assembly located on the connection path between the third primary winding and the control unit.

2. The circuit according to claim 1, characterized in that, The input power unit includes: First capacitor, second capacitor, first power switch, second power switch, first diode, second diode, current transformer, and sensing resistor. in, The first terminal of the first capacitor is connected to the first terminal of the first primary winding of the transformer, and the second terminal of the first capacitor is connected to the first ground terminal via the second capacitor. The anode of the first diode is connected to the second end of the first primary winding of the transformer, and the cathode of the first diode is connected to the drain of the first power switch. The gate of the first power switch is used as the first input control terminal of the input power unit; The source of the first power switch is connected to the junction of the first capacitor and the second capacitor through the detection resistor; The first end of the current transformer is connected to the first end of the second primary winding of the transformer, and the second end of the current transformer is connected to the connection point of the first capacitor and the second capacitor. The drain of the second power switch is connected to the second end of the second primary winding of the transformer, the source of the second power switch is connected to the anode of the second diode, the cathode of the second diode is connected to the first ground terminal, and the gate of the second power switch serves as the second input control terminal of the input power unit.

3. The circuit according to claim 1, characterized in that, The output power unit includes: The third diode, the third capacitor, and the energy absorption resistor. in, The anode of the third diode is connected to the first terminal of the secondary winding of the transformer, and the cathode of the third diode is connected to the first terminal of the energy absorption resistor. The second end of the energy absorption resistor is connected to the second end of the secondary winding of the transformer; The third capacitor is connected in parallel across the two ends of the energy absorption resistor, and one end of the third capacitor connected to the second end of the energy absorption resistor is connected to the third ground terminal.

4. The circuit according to claim 1, characterized in that, The power supply unit also includes: Fourth capacitor, current-limiting resistor, fourth diode, in, The first end of the inductor assembly is connected to the first end of the third primary winding of the transformer, and the second end of the inductor assembly is connected to the anode of the fourth diode. The cathode of the fourth diode is connected to the power input terminal of the control unit through the current-limiting resistor; The first end of the fourth capacitor is connected to the connection point between the current-limiting resistor and the power input terminal of the control unit, the second end of the fourth capacitor is connected to the connection point between the second end of the third primary winding and the ground terminal of the control unit, and the second end of the fourth capacitor is connected to the second ground terminal.

5. The circuit according to claim 4, characterized in that, The first end of the third primary winding of the transformer is connected to the anode of the fourth diode, and the cathode of the fourth diode is connected to the current-limiting resistor through the inductor assembly.

6. The circuit according to claim 4, characterized in that, The first end of the third primary winding is connected to the first end of the inductor assembly in sequence through the fourth diode and the current-limiting resistor, and the second end of the inductor assembly is connected to the power input terminal of the control unit.

7. The circuit according to claim 4, characterized in that, The second end of the third primary winding is connected to the ground terminal of the control unit via the inductor assembly.

8. The circuit according to claim 2, characterized in that, The control unit uses a control chip, wherein the drive output terminal of the control chip is connected to a drive unit.

9. The circuit according to claim 8, characterized in that, The driving unit uses a power MOSFET driving chip. The first output control terminal of the power MOSFET driving chip is connected to the first input control terminal of the input power unit, and the second output control terminal of the power MOSFET driving chip is connected to the second input control terminal of the input power unit.

10. A power module, characterized in that, The power module includes an AC-DC conversion unit, a DC-DC conversion unit, an EMC unit, and an auxiliary power supply circuit as described in any one of claims 1 to 9.

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