An ac-dc circuit for an electrosurgical unit

Abstract

The utility model discloses an AC-DC circuit for electric knife, include: AC input interface, rectifier module, filter module, switch conversion module, control module and output module, the input end of AC input interface is accessed alternating current, and the output end of AC input interface is connected with rectifier module, and rectifier module is used for converting alternating current into direct current, the input end of filter module is connected with the output end of rectifier module, and filter module is used for filtering to the direct current after rectification, the input end of switch conversion module is connected with the output end of filter module, and switch conversion module is used for voltage conversion to the direct current after filtering, the output end of control module is connected with switch conversion module, and control module is used for controlling the working condition of switch conversion module, the input end of output module is connected with the output end of switch conversion module, and output module is used for outputting the direct current of different voltage. The utility model discloses through modularization design realizes the conversion of efficient alternating current to direct current, satisfies the requirement of electric knife to power stability, reliability and safety.

Description

Technical Field

[0001] This utility model relates to the field of electric knife control technology, specifically to an AC-DC circuit for electric knives. Background Technology

[0002] In the field of surgical medicine, the electrosurgical unit, as a key device that uses high-frequency current to generate heat for tissue cutting and hemostasis, is highly dependent on the stability and reliability of the power supply system. Existing electrosurgical unit AC-DC conversion circuits face the following technical bottlenecks that urgently need to be addressed in practical applications: 1. Traditional AC-DC circuits often employ open-loop control or simple linear voltage regulation, lacking a real-time feedback adjustment mechanism. When the mains voltage fluctuates (e.g., ±10%) or the electrosurgical unit load changes dynamically, the output voltage fluctuation range can reach over ±5%, severely affecting the working accuracy of the electrosurgical unit's high-frequency generator. 2. Existing electrosurgical unit power supply protection functions typically rely solely on fuses for overcurrent protection, lacking multiple protection mechanisms for overvoltage, short circuit, and overtemperature. When the circuit malfunctions, it may cause critical components such as MOSFETs to burn out. 3. Electrosurgical units often require multiple voltage outputs during surgery (e.g., +12V, -12V, +5V, etc.). Traditional circuits often use a single output followed by voltage division, leading to mutual coupling between the voltage branches and further reducing stability. Furthermore, no anti-interference measures were designed for the medical environment, making it impossible to guarantee the accuracy of current sampling in environments with strong electromagnetic interference, which affects the accuracy of electrosurgical power control. Utility Model Content

[0003] The purpose of this invention is to provide an AC-DC circuit for an electrosurgical unit. This invention achieves efficient AC-DC conversion through modular design, meeting the requirements of electrosurgical units for power supply stability, reliability, and safety.

[0004] The technical solution of this utility model is as follows: An AC-DC circuit for an electrosurgical unit, comprising: an AC input interface, a rectifier module, a filter module, a switching conversion module, a control module, and an output module; the input terminal of the AC input interface is connected to AC power, and the output terminal of the AC input interface is connected to the rectifier module, which converts AC power into DC power; the input terminal of the filter module is connected to the output terminal of the rectifier module, which filters the rectified DC power; the input terminal of the switching conversion module is connected to the output terminal of the filter module, which performs voltage conversion on the filtered DC power; the output terminal of the control module is connected to the switching conversion module, which controls the operating state of the switching conversion module; the input terminal of the output module is connected to the output terminal of the switching conversion module, which outputs DC power at different voltages.

[0005] The aforementioned AC-DC circuit for an electrosurgical unit includes a rectifier module comprising a full-bridge rectifier B2; a filter module comprising fuses F1 and F2, capacitors C4 and C5, and capacitor CX1; an AC input interface connected to the AC input terminal of the full-bridge rectifier B2; a DC positive terminal of the full-bridge rectifier B2 connected to one end of fuse F1; and the other end of fuse F1 connected to the positive terminals of capacitors C4 and C5, one end of capacitor CX1, and the switching conversion module; a DC negative terminal of the full-bridge rectifier B2 connected to one end of fuse F2; and the other end of fuse F2 connected to the negative terminals of capacitors C4 and C5, the other end of capacitor CX1, and the switching conversion module.

[0006] The aforementioned AC-DC circuit for an electrosurgical unit includes a switching conversion module comprising MOSFETs Q1, Q2, Q3, and Q4; resistors R2, R3, R4, R7, R8, R10, and R11; and transformers L2A, L2B, L3A, and L3B. MOSFETs Q1, Q2, Q3, and Q4 form a full-bridge circuit. The drains of MOSFETs Q1 and Q2 are connected to the positive DC terminal of the full-bridge rectifier B2. The gate of MOSFET Q1 is connected to one end of resistor R2 and one end of resistor R4. The other end of resistor R2 is connected to one end of the secondary winding of transformer L3A. The other end of the secondary winding of transformer L3A and the other end of resistor R4 are connected together at the midpoint of the bridge arm between MOSFETs Q1 and Q3. One end of the primary winding of transformer L3A is connected to the control module, and the other end of the primary winding of transformer L3A is grounded. The gate of MOSFET Q2 is connected to one end of resistor R3 and one end of resistor R5. The other end of resistor R5 is connected to the secondary winding of transformer L2A. One end is connected; the other end of the secondary winding of transformer L2A and the other end of resistor R5 are connected to the midpoint of the bridge arm of MOSFET Q2 and MOSFET Q4; one end of the primary winding of transformer L2A is connected to the control module, and the other end of the primary winding of transformer L2A is grounded; the gate of MOSFET Q3 is connected to one end of resistor R7 and one end of resistor R10, and the other end of resistor R7 is connected to one end of the secondary winding of transformer L3B; the other end of the secondary winding of transformer L3B, the other end of resistor R10, and the source of MOSFET Q3 are connected to the full-bridge rectifier B2. The DC negative terminal of the transformer L2B is connected; one end of the primary winding of the transformer L3B is connected to the control module, and the other end of the primary winding of the transformer L3B is grounded; the gate of the MOSFET Q4 is connected to one end of the resistor R8 and one end of the resistor R11, and the other end of the resistor R8 is connected to one end of the secondary winding of the transformer L2B; the other end of the secondary winding of the transformer L2B, the other end of the resistor R11, and the source of the MOSFET Q4 are connected to the DC negative terminal of the full-bridge rectifier B2; one end of the primary winding of the transformer L2B is connected to the control module, and the other end of the primary winding of the transformer L2B is grounded.

[0007] The aforementioned AC-DC circuit for an electrosurgical unit includes a control module comprising a control chip IC2, a driver amplifier chip IC3, operational amplifier IC1B, operational amplifier IC1A, capacitors C15, C16, C17, C18, C19, C20, C21, C22, C23, C24, C25, C29, C30, and C31, and resistors R16, R17, R18, R19, R20, R21, R22, R23, R24, R25, R26, R27, R28, and R30; the control chip IC2... The IN terminal of IC2 is connected to one end of capacitor C20, one end of resistor R22, and the output terminal of operational amplifier IC1B; the other end of capacitor C20 is connected to one end of capacitor C17, one end of capacitor C18, one end of resistor R20, and the inverting input terminal of operational amplifier IC1B; the other end of resistor R22 is connected to the other end of capacitor C18; the other end of resistor R20 is connected to one end of resistor R16, one end of resistor R21, and one end of resistor R24; the other end of resistor R21 is connected to the other end of capacitor C17; the other end of resistor R16 is connected to the DC positive terminal; the other end of resistor R24 ​​is grounded; the non-inverting input terminal of operational amplifier IC1B is connected to the output terminal of resistor R23. One end of resistor R18 and one end of capacitor C19 are connected; the other end of resistor R23 is connected to a -12V power supply; the other end of capacitor C19 is grounded; the other end of resistor R18 is connected to one end of resistor R26 and the output terminal of operational amplifier IC1A; the other end of resistor R26 is connected to one end of resistor R25 and the inverting input terminal of operational amplifier IC1A; the other end of resistor R25 is grounded; the non-inverting input terminal of operational amplifier IC1A is connected to one end of resistor R17 and one end of capacitor C16; the other end of resistor R17 is connected to connector C0N3 and one end of resistor R19; the other end of resistor R19 and the other end of capacitor C16 are grounded. One end of capacitor C15 is grounded, and the other end is connected to the power supply terminal of operational amplifier IC1; the VC and VCC terminals of control chip IC2 are connected to one end of capacitor C22, one end of capacitor C23, the positive terminal of capacitor C21, and the +12V voltage; the other ends of capacitor C22, the other ends of capacitor C23, and the negative terminal of capacitor C21 are grounded; the RAMP and CT terminals of control chip IC2 are connected to one end of capacitor C24, and the other end of capacitor C24 is grounded; the SS terminal of control chip IC2 is connected to one end of capacitor C25, and the other end of capacitor C25 is grounded; the RT terminal of control chip IC2 is connected to one end of resistor R27, and the other end of resistor R27 is grounded.The VREF terminal of control chip IC2 is connected to one end of capacitor C29, and the other end of capacitor C29 is grounded; the OUTA terminal of control chip IC2 is connected to the INA terminal of drive amplifier chip IC3, and the OUTB terminal of control chip IC2 is connected to the INB terminal of drive amplifier chip IC3; the VDD terminal of drive amplifier chip IC3 is connected to one end of capacitor C30, one end of capacitor C31, and the +12V voltage, and the other ends of capacitor C30, the other end of capacitor C31, and the GND terminal of drive amplifier chip IC3 are grounded; the OUTA terminal of drive amplifier chip IC3 is connected to one end of resistor R28, and the other end of resistor R28 serves as a signal output terminal connected to the switch conversion module; the OUTB terminal of drive amplifier chip IC3 is connected to one end of resistor R30, and the other end of resistor R30 serves as a signal output terminal connected to the switch conversion module.

[0008] The aforementioned AC-DC circuit for an electrosurgical unit includes a control module comprising a logic chip IC4, capacitors C26, C27, and C28, resistors R29 and R31, diodes VD5 and VD6. The ILM terminal of the control chip IC4 is connected to the cathode of diode VD6, and the anode of diode VD6 is connected to one end of capacitor C28 and one end of resistor R31. The other end of capacitor C28 is grounded. The other end of resistor R31 is connected to the Y terminal of logic chip IC4. The VCC terminal of logic chip IC4 is connected to +5V and to one end of capacitor C26, the other end of which is grounded. The A terminal of logic chip IC4 is connected to one end of resistor R29, the anode of diode VD5, and one end of capacitor C27. The other end of resistor R29 and the cathode of diode VD5 are connected to +5V. The other end of capacitor C27 is grounded.

[0009] The aforementioned AC-DC circuit for an electrosurgical unit includes an output module comprising a transformer T1, a current transformer T2, a full-bridge rectifier B1, a transformer L1, capacitors C1, C2, C3, C6, C7, and C14, resistors R1, R6, R9, R12, R13, R14, and R15, and diodes VD1, VD2, VD3, and VD4. One end of the primary winding of transformer T1 is connected to one end of capacitor C6 and one end of capacitor C7. The other end of capacitor C6 is connected to the midpoint of the bridge arm of MOSFETs Q1 and Q3. The other end of capacitor C7 is connected to one end of resistor R6. The other end of resistor R6 is connected to the other end of the primary winding of transformer T1 and the AW1 port of current transformer T2. The BW1 port of current transformer T2 is connected to the midpoint of the bridge arm of MOSFETs Q2 and Q4. ；The two ends of the secondary winding of transformer T1 are connected to the AC input terminals of full-bridge rectifier B1. Resistor R1 and capacitor C3 are connected in series to the two ends of the secondary winding of transformer T1. The DC positive terminal of full-bridge rectifier B1 is connected to one end of the primary winding of transformer L1, and the other end of the primary winding of transformer L1 is connected to the positive terminals of capacitors C1 and C2, serving as the DC positive output interface. The DC negative terminal of full-bridge rectifier B1 is connected to one end of the secondary winding of transformer L1, and the other end of the secondary winding of transformer L1 is grounded to the negative terminals of capacitors C1 and C2, serving as the DC negative output interface. Resistor R9 is connected between the sampling signal output terminals of current transformer T2. Diodes VD1, VD2, VD3, and VD4 form a full-bridge rectifier unit. In this circuit, the anode of diode VD1 and the cathode of diode VD3 are connected to one end of the sampling resistor R9; the anode of diode VD2 and the cathode of diode VD4 are connected to the other end of the sampling resistor R9; the cathodes of diode VD1 and VD2 are connected together; and the anodes of diode VD3 and VD4 are connected together and grounded. One end of resistor R12 is connected to the junction of the cathodes of diodes VD1 and VD2; the other end of resistor R12 is connected to one end of capacitor C14 and one end of resistor R13; the other end of capacitor C14 is grounded; the other end of resistor R13 is connected to one end of resistor R14 and one end of resistor R15; the other end of resistor R15 and the other end of capacitor C14 are both grounded; and the other end of resistor R14 serves as the current limiting signal output terminal.

[0010] Compared with the prior art, the present invention has the following beneficial effects:

[0011] 1. This invention employs a full-bridge rectifier combined with a MOSFET full-bridge switching module. Compared to the traditional half-bridge structure, rectification and switching losses are significantly reduced. Combined with a transformer coupling design, soft-switching technology is implemented, greatly improving energy conversion efficiency and reducing equipment heat generation. This invention also utilizes a filter structure composed of electrolytic capacitors and safety capacitors to effectively filter out DC ripple after rectification, providing a clean input for subsequent conversion stages and avoiding energy loss.

[0012] 2. This invention utilizes an operational amplifier and a control chip to form a closed-loop feedback system, which samples the output voltage in real time and dynamically adjusts the PWM duty cycle to maintain stable output voltage even under power grid fluctuations and load changes. The transformer secondary winding of this invention precisely drives the full-bridge MOSFETs through a resistor network, ensuring synchronized switching and avoiding voltage fluctuations caused by drive delay.

[0013] 3. The current transformer of this invention samples the current in real time, converts the signal through rectification and sampling circuits, and works with the logic chip for rapid response. In case of abnormal current, it quickly shuts off the PWM output to protect critical components. The rectifier module and control module of this invention form a dual protection barrier. When the output voltage is abnormal, the fuse and control chip work together to prevent the load from being damaged by overvoltage.

[0014] 4. This utility model combines a transformer and a rectifier to output multiple DC voltages simultaneously. Each branch is isolated by an inductor and a filter capacitor to avoid voltage coupling interference and meet the power supply requirements of different loads of the electric knife. Attached Figure Description

[0015] Figure 1 This is a circuit diagram of the AC input interface, rectifier module, and filter module.

[0016] Figure 2 This is a circuit diagram of the switching conversion module and the output module;

[0017] Figure 3 This is a circuit diagram of the control module. Detailed Implementation

[0018] The present invention will be further described below with reference to the accompanying drawings and embodiments, but this should not be construed as limiting the present invention.

[0019] Example: An AC-DC circuit for an electrosurgical unit, comprising: an AC input interface, a rectifier module, a filter module, a switching conversion module, a control module, and an output module; the input terminal of the AC input interface is connected to AC power, and the output terminal of the AC input interface is connected to the rectifier module, which converts the AC power into DC power; the input terminal of the filter module is connected to the output terminal of the rectifier module, which filters the rectified DC power; the input terminal of the switching conversion module is connected to the output terminal of the filter module, which performs voltage conversion on the filtered DC power; the output terminal of the control module is connected to the switching conversion module, which controls the operating state of the switching conversion module; the input terminal of the output module is connected to the output terminal of the switching conversion module, which outputs DC power at different voltages.

[0020] Specifically, such as Figure 1As shown, the rectifier module includes a full-bridge rectifier B2; the filter module includes fuses F1 and F2, capacitors C4 and C5, and capacitor CX1; the AC input interface is connected to the AC input terminal of the full-bridge rectifier B2, the DC positive terminal of the full-bridge rectifier B2 is connected to one end of fuse F1, and the other end of fuse F1 is connected to the positive terminals of capacitors C4 and C5, one end of capacitor CX1, and the switching conversion module; the DC negative terminal of the full-bridge rectifier B2 is connected to one end of fuse F2, and the other end of fuse F2 is connected to the negative terminals of capacitors C4 and C5, the other end of capacitor CX1, and the switching conversion module. In this embodiment, the AC input interface is the electrical connection port between the circuit and the external AC power supply. AC power is connected through a physical interface (such as a socket), and its output terminal is directly connected to the rectifier module, forming a current path. The interface typically contains conductive metal plates or pins to ensure that the live and neutral wires of the AC power are correctly connected to the circuit. The rectifier module uses a full-bridge rectifier (GBU1010) as its core component, which internally consists of four diodes forming a bridge structure. When AC power is input, the full-bridge rectifier utilizes the unidirectional conductivity of the diodes to guide the current in the same direction during both the positive and negative half-cycles of the AC power, thereby converting the AC power into pulsating DC power. The filter module consists of fuses (F1, F2) and capacitors (C4, C5, CX1). Electrolytic capacitors C4 and C5 are connected in parallel to the DC positive and negative terminals, utilizing the charging and discharging characteristics of capacitors to smooth the voltage fluctuations of the pulsating DC power and convert high-frequency ripple into low-frequency ripple. The safety capacitor CX1 is connected across the positive and negative terminals to suppress common-mode interference in the circuit (such as high-frequency noise in the power grid) and improve electromagnetic compatibility (EMC). F1 and F2 are connected in series at the output of the rectifier module. When an overcurrent fault occurs in the circuit, the fuse will melt due to overheating, cutting off the current path. In this embodiment, 220V AC power is input from AC_L and AC_N, and after being sorted and filtered, approximately 311V DC power is output.

[0021] like Figure 2As shown, the switching conversion module includes MOSFETs Q1, Q2, Q3, and Q4; resistors R2, R3, R4, R7, R8, R10, and R11; transformers L2A, L2B, L3A, and L3B; MOSFETs Q1, Q2, Q3, and Q4 form a full-bridge circuit; the drains of MOSFETs Q1 and Q2 are connected to the positive DC terminal of the full-bridge rectifier B2; the gate of MOSFET Q1... One end of resistor R2 and one end of resistor R4 are connected to the secondary winding of transformer L3A; the other end of the secondary winding of transformer L3A and the other end of resistor R4 are connected together to the midpoint of the bridge arm of MOSFET Q1 and MOSFET Q3; one end of the primary winding of transformer L3A is connected to the control module, and the other end of the primary winding of transformer L3A is grounded; the gate of MOSFET Q2 is connected to one end of resistor R3 and one end of resistor R5, and the other end of resistor R5 is connected to one end of the secondary winding of transformer L2A; The other end of the secondary winding of transformer L2A and the other end of resistor R5 are connected to the midpoint of the bridge arm of MOSFETs Q2 and Q4; one end of the primary winding of transformer L2A is connected to the control module, and the other end of the primary winding of transformer L2A is grounded; the gate of MOSFET Q3 is connected to one end of resistor R7 and one end of resistor R10, and the other end of resistor R7 is connected to one end of the secondary winding of transformer L3B; the other end of the secondary winding of transformer L3B, the other end of resistor R10, and the source of MOSFET Q3 are connected to the DC power supply of the full-bridge rectifier B2. The primary winding of transformer L3B is connected to the control module at one end, and the other end is grounded. The gate of MOSFET Q4 is connected to one end of resistor R8 and one end of resistor R11, and the other end of resistor R8 is connected to one end of the secondary winding of transformer L2B. The other end of the secondary winding of transformer L2B, the other end of resistor R11, and the source of MOSFET Q4 are connected to the negative DC terminal of full-bridge rectifier B2. The primary winding of transformer L2B is connected to the control module at one end, and the other end is grounded. In this embodiment, four MOSFETs (Q1-Q4) form a full-bridge circuit, and by controlling the alternating conduction of the bridge arm MOSFETs, DC power is converted into high-frequency AC power. The PWM signal output by the control module is transmitted through the primary windings of transformers L3A / L3B (driving Q1 / Q3) and L2A / L2B (driving Q2 / Q4). The secondary windings couple the drive signal to the gate of the MOS transistor through a resistor network (such as R2 / R4). The transformers isolate the high and low voltage sides, and magnetic coupling is used to achieve synchronous transmission of the drive signal.The corresponding resistors connected to the secondary winding serve several purposes: limiting the drive current (≤20mA) to prevent gate overcurrent damage to the MOSFET; matching the transformer secondary output impedance with the MOSFET gate input impedance through resistor values ​​(e.g., 1KΩ) to ensure drive signal integrity; and using some resistors (e.g., R10, R11) for voltage division to adjust the MOSFET gate drive voltage amplitude and prevent excessive drive voltage from causing MOSFET breakdown. The transformer leakage inductance and the MOSFET parasitic capacitance form a resonant network, achieving zero-voltage switching (ZVS) and reducing switching losses.

[0022] like Figure 3As shown, the control module includes a control chip IC2, a driver amplifier chip IC3, an operational amplifier IC1B, an operational amplifier IC1A, capacitors C15, C16, C17, C18, C19, C20, C21, C22, C23, C24, C25, C29, C30, and C31, and resistors R16, R17, R18, R19, R20, R21, R22, R23, R24, R25, R26, R27, R28, and R30; the IN terminal of the control chip IC2 is connected to capacitor C2. One end of capacitor C20, one end of resistor R22, and the output terminal of operational amplifier IC1B are connected; the other end of capacitor C20 is connected to one end of capacitor C17, one end of capacitor C18, one end of resistor R20, and the inverting input terminal of operational amplifier IC1B; the other end of resistor R22 is connected to the other end of capacitor C18; the other end of resistor R20 is connected to one end of resistor R16, one end of resistor R21, and one end of resistor R24; the other end of resistor R21 is connected to the other end of capacitor C17; the other end of resistor R16 is connected to the DC positive terminal; the other end of resistor R24 ​​is grounded; the non-inverting input terminal of operational amplifier IC1B is connected to one end of resistor R23, resistor R1... One end of resistor R18 is connected to one end of resistor R26 and one end of capacitor C19; the other end of resistor R23 is connected to a -12V power supply; the other end of capacitor C19 is grounded; the other end of resistor R18 is connected to one end of resistor R26 and the output terminal of operational amplifier IC1A; the other end of resistor R26 is connected to one end of resistor R25 and the inverting input terminal of operational amplifier IC1A; the other end of resistor R25 is grounded; the non-inverting input terminal of operational amplifier IC1A is connected to one end of resistor R17 and one end of capacitor C16; the other end of resistor R17 is connected to connector CON3 and one end of resistor R19; the other end of resistor R19 and the other end of capacitor C16 are grounded; the other end of resistor R18 is connected to one end of resistor R26 and one end of operational amplifier IC1A; the other end of resistor R26 is connected to one end of resistor R25 and the inverting input terminal of operational amplifier IC1A; the other end of resistor R25 is grounded; the other end of resistor R16 is connected to one end of capacitor C19 and one end of capacitor C19; the other end of resistor R17 is connected to one end of connector C0N3 and one end of resistor R19; the other end of resistor R19 and the other end of capacitor C16 are grounded; the other end of resistor R18 is connected to one end of resistor R26 and one end of capacitor C1A; the other end of resistor R26 ...17 is connected to one end of connector C0N3 and one One end of capacitor C15 is grounded, and the other end is connected to the power supply terminal of operational amplifier IC1; the VC and VCC terminals of control chip IC2 are connected to one end of capacitor C22, one end of capacitor C23, the positive terminal of capacitor C21, and the +12V voltage; the other ends of capacitor C22, the other ends of capacitor C23, and the negative terminal of capacitor C21 are grounded; the RAMP and CT terminals of control chip IC2 are connected to one end of capacitor C24, and the other end of capacitor C24 is grounded; the SS terminal of control chip IC2 is connected to one end of capacitor C25, and the other end of capacitor C25 is grounded; the RT terminal of control chip IC2 is connected to one end of resistor R27, and the other end of resistor R27 is grounded.The VREF terminal of the control chip IC2 is connected to one end of capacitor C29, and the other end of capacitor C29 is grounded; the OUTA terminal of the control chip IC2 is connected to the INA terminal of the drive amplifier chip IC3, and the OUTB terminal of the control chip IC2 is connected to the INB terminal of the drive amplifier chip IC3; the VDD terminal of the drive amplifier chip IC3 is connected to one end of capacitor C30, one end of capacitor C31, and the +12V voltage, and the other ends of capacitor C30, the other ends of capacitor C31, and the GND terminal of the drive amplifier chip IC3 are grounded; the OUTA terminal of the drive amplifier chip IC3 is connected to one end of resistor R28, and the other end of resistor R28 serves as a signal output terminal connected to the switch conversion module; the OUTB terminal of the drive amplifier chip IC3 is connected to one end of resistor R30, and the other end of resistor R30 serves as a signal output terminal connected to the switch conversion module. The control module also includes a logic chip IC4, capacitors C26, C27, and C28, resistors R29 and R31, diodes VD5 and VD6. The ILM terminal of the control chip IC4 is connected to the cathode of diode VD6, and the anode of diode VD6 is connected to one end of capacitor C28 and one end of resistor R31. The other end of capacitor C28 is grounded. The other end of resistor R31 is connected to the Y terminal of logic chip IC4. The VCC terminal of logic chip IC4 is connected to +5V and to one end of capacitor C26, the other end of capacitor C26 is grounded. The A terminal of logic chip IC4 is connected to one end of resistor R29, the anode of diode VD5, and one end of capacitor C27. The other end of resistor R29 and the cathode of diode VD5 are connected to +5V. The other end of capacitor C27 is grounded. In this embodiment, the control module is the core control unit of the electrosurgical AC-DC circuit. Through the collaborative work of the integrated chip and peripheral components, it realizes the drive control, output voltage regulation, and system protection functions of the switching conversion module. The core control chip IC2, model UC3825A, is the control center of the module, possessing PWM signal generation, feedback adjustment, and protection logic functions. Its pin connections mainly include: IN terminal: receives the output voltage feedback signal, compares it with the reference voltage, and adjusts the PWM duty cycle; VC and VCC terminals: connect to a +12V power supply to power the chip; OUTA and OUTB terminals: output complementary PWM drive signals to control the MOSFETs of the switching module; ILM terminal: overcurrent protection input, connected to the output signal of logic chip IC4, shutting off the PWM output in case of an abnormality. The driver amplifier chip IC3, model TC1427CPA, receives and amplifies the PWM signal from IC2, enhancing the driving capability. Its pin connections mainly include: INA and INB terminals: connect to the OUTA and OUTB terminals of IC2; OUTA and OUTB terminals: drive the gates of the MOSFETs of the switching module through resistors R28 and R30.VDD terminal: Connected to +12V power supply, used in conjunction with C30 and C31 for filtering to ensure stable drive signal. Operational amplifiers IC1A / IC1B: Model TP2582-SR, forming a closed-loop feedback system; IC1A non-inverting input terminal: Samples the output voltage through resistor R17 and compares it with the reference voltage at the inverting input; IC1B inverting input terminal: Connects to the feedback voltage, and the non-inverting input terminal is connected to a -12V voltage divider signal, outputting the error signal to the IN terminal of IC2; Peripheral components (C15-C19, R16-R24) are used for filtering and voltage division to optimize the accuracy of the feedback signal. The logic chip IC4, model SN74AHC1G00DBVR, forms an overcurrent protection circuit. Its A terminal receives the sampling signal from the current transformer T2 (rectified by VD1-VD4), and its Y terminal outputs a protection signal to the ILM terminal of IC2. During an overcurrent event, the PWM is shut down. Peripheral components (VD5, VD6, C26-C28, R29, R31) are used for filtering and clamping to ensure a fast response to the protection signal.

[0023] like Figure 2 As shown, the output module includes a transformer T1, a current transformer T2, a full-bridge rectifier B1, a transformer L1, capacitors C1, C2, C3, C6, C7, and C14, resistors R1, R6, R9, R12, R13, R14, and R15, and diodes VD1, VD2, VD3, and VD4. One end of the primary winding of the transformer T1 is connected to one end of capacitor C6 and one end of capacitor C7. The other end of capacitor C6 is connected to the midpoint of the bridge arm of MOSFETs Q1 and Q3. The other end of capacitor C7 is connected to one end of resistor R6. The other end of resistor R6 is connected to the other end of the primary winding of the transformer T1 and the AW1 port of the current transformer T2. The BW1 port of the current transformer T2 is connected to the midpoint of the bridge arm of MOSFETs Q2 and Q4. ；The two ends of the secondary winding of transformer T1 are connected to the AC input terminals of full-bridge rectifier B1. Resistor R1 and capacitor C3 are connected in series to the two ends of the secondary winding of transformer T1. The DC positive terminal of full-bridge rectifier B1 is connected to one end of the primary winding of transformer L1, and the other end of the primary winding of transformer L1 is connected to the positive terminals of capacitors C1 and C2, serving as the DC positive output interface. The DC negative terminal of full-bridge rectifier B1 is connected to one end of the secondary winding of transformer L1, and the other end of the secondary winding of transformer L1 is grounded to the negative terminals of capacitors C1 and C2, serving as the DC negative output interface. Resistor R9 is connected between the sampling signal output terminals of current transformer T2. Diodes VD1, VD2, VD3, and VD4 form a full-bridge rectifier unit. In this circuit, the anode of diode VD1 and the cathode of diode VD3 are connected to one end of the sampling resistor R9; the anode of diode VD2 and the cathode of diode VD4 are connected to the other end of the sampling resistor R9; the cathodes of diode VD1 and VD2 are connected together; and the anodes of diode VD3 and VD4 are connected together and grounded. One end of resistor R12 is connected to the junction of the cathodes of diodes VD1 and VD2; the other end of resistor R12 is connected to one end of capacitor C14 and one end of resistor R13; the other end of capacitor C14 is grounded; the other end of resistor R13 is connected to one end of resistor R14 and one end of resistor R15; the other end of resistor R15 and the other end of capacitor C14 are both grounded; and the other end of resistor R14 serves as the current limiting signal output terminal. In this embodiment, the primary winding of transformer T1 is connected to the midpoint of the bridge arm of the switching converter module (the connection point between Q1 / Q3 and Q2 / Q4). A target voltage is generated in the secondary winding via high-frequency alternating current (generated by the full-bridge MOSFET switch). The turns ratio of the primary and secondary windings determines the voltage drop, meeting the low-voltage power supply requirements (e.g., +12V, +5V) of each module in the electrosurgical unit. The high-frequency AC output from the secondary side of T1 is connected to a full-bridge rectifier B1 (GBU1010), which uses the unidirectional conductivity of diodes to convert the alternating current into pulsating DC current. The positive DC terminal of B1 is connected to a subsequent filter network, and the negative terminal is grounded, achieving unidirectional current transmission. The rectified pulsating DC current passes sequentially through a π-type filter structure composed of transformer L1 (inductor) and capacitors C1 and C2 (electrolytic capacitors). L1 (SQ1918-2mH / 12A) suppresses current surges and stores magnetic field energy; C1 and C2 (680μF / 400V) are connected in parallel for filtering, utilizing their charging and discharging characteristics to smooth voltage fluctuations and reduce ripple voltage to below ±0.5V. Resistor R1 and capacitor C3 are connected in series across the secondary winding of T1 to absorb the back electromotive force when the transformer is turned off, preventing high-voltage spikes from damaging rectifier B1. The AW1 and BW1 ports of current transformer T2 are connected to the midpoints of the two bridge arms of the switching converter module, respectively, to collect the high-frequency current flowing through the primary winding of transformer T1.The current signal output from the secondary side of the transformer is converted into a voltage signal by sampling resistor R9 (100R). The voltage signal is converted into a DC signal by a full-bridge rectifier unit composed of VD1-VD4, then filtered by R12 and C14 (180pF), and after voltage division by R13, R14, and R15, the output current limiting signal is sent to the IC4 logic chip of the control module to realize the rapid shutdown of the PWM output in case of overcurrent (response time < 5μs).

[0024] Working principle

[0025] Alternating current (AC) is input via the AC input interface, rectified by the rectifier module to convert it into pulsating DC, and filtered to remove ripple. The control module generates a PWM signal to drive the full-bridge circuit of the switching converter module, achieving voltage conversion through transformer coupling. The output module rectifies and filters the converted voltage, outputting multiple DC voltages. The feedback loop collects the output voltage and current in real time, and the control module adjusts the PWM duty cycle according to the feedback signal to maintain stable output. In case of overcurrent or other abnormalities, the protection circuit quickly activates and cuts off the output. This invention, through the above structure and control method, achieves efficient, stable, and safe operation of the electrosurgical unit's AC-DC circuit, meeting the stringent requirements of medical equipment for power supply systems.

Claims

1. An AC-DC circuit for an electrosurgical unit, characterized in that: include: AC input interface, rectifier module, filter module, switching converter module, control module and output module; The AC input interface is connected to AC power at its input terminal, and its output terminal is connected to a rectifier module, which converts AC power to DC power. The filter module is connected to the output terminal of the rectifier module, and it filters the rectified DC power. The switch conversion module is connected to the output terminal of the filter module, and it performs voltage conversion on the filtered DC power. The control module is connected to the output terminal of the switch conversion module, and it controls the operating state of the switch conversion module. The output module is connected to the output terminal of the switch conversion module, and it outputs DC power at different voltages.

2. The AC-DC circuit for an electrosurgical unit according to claim 1, characterized in that: The rectifier module includes a full-bridge rectifier B2; the filter module includes fuses F1 and F2, capacitors C4 and C5, and capacitor CX1; the AC input interface is connected to the AC input terminal of the full-bridge rectifier B2, the positive DC terminal of the full-bridge rectifier B2 is connected to one end of fuse F1, and the other end of fuse F1 is connected to the positive terminals of capacitors C4 and C5, one end of capacitor CX1, and the switching conversion module; the negative DC terminal of the full-bridge rectifier B2 is connected to one end of fuse F2, and the other end of fuse F2 is connected to the negative terminals of capacitors C4 and C5, the other end of capacitor CX1, and the switching conversion module.

3. The AC-DC circuit for an electrosurgical unit according to claim 2, characterized in that: The switching conversion module includes MOSFETs Q1, Q2, Q3, and Q4; resistors R2, R3, R4, R7, R8, R10, and R11; and transformers L2A, L2B, L3A, and L3B. MOSFETs Q1, Q2, Q3, and Q4 form a full-bridge circuit. The drains of MOSFETs Q1 and Q2 are connected to the positive DC terminal of the full-bridge rectifier B2. The gate of MOSFET Q1 is connected to the DC terminal of the rectifier B2. One end of resistor R2 and one end of resistor R4 are connected, and the other end of resistor R2 is connected to one end of the secondary winding of transformer L3A; the other end of the secondary winding of transformer L3A and the other end of resistor R4 are connected together to the midpoint of the bridge arm of MOSFET Q1 and MOSFET Q3; one end of the primary winding of transformer L3A is connected to the control module, and the other end of the primary winding of transformer L3A is grounded; the gate of MOSFET Q2 is connected to one end of resistor R3 and one end of resistor R5, and the other end of resistor R5 is connected to one end of the secondary winding of transformer L2A; the transformer The other end of the secondary winding of transformer L2A is connected to the other end of resistor R5 at the midpoint of the bridge arm of MOSFETs Q2 and Q4; one end of the primary winding of transformer L2A is connected to the control module, and the other end of the primary winding of transformer L2A is grounded; the gate of MOSFET Q3 is connected to one end of resistor R7 and one end of resistor R10, and the other end of resistor R7 is connected to one end of the secondary winding of transformer L3B; the other end of the secondary winding of transformer L3B, the other end of resistor R10, and the source of MOSFET Q3 are connected to the DC negative terminal of full-bridge rectifier B2. The primary winding of transformer L3B is connected to the control module at one end, and the other end is grounded. The gate of MOSFET Q4 is connected to one end of resistor R8 and one end of resistor R11, and the other end of resistor R8 is connected to one end of the secondary winding of transformer L2B. The other end of the secondary winding of transformer L2B, the other end of resistor R11, and the source of MOSFET Q4 are connected to the negative DC terminal of full-bridge rectifier B2. The primary winding of transformer L2B is connected to the control module at one end, and the other end is grounded.

4. The AC-DC circuit for an electrosurgical unit according to claim 3, characterized in that: The control module includes a control chip IC2, a driver amplifier chip IC3, an operational amplifier IC1B, an operational amplifier IC1A, capacitors C15, C16, C17, C18, C19, C20, C21, C22, C23, C24, C25, C29, C30, and C31, and resistors R16, R17, R18, R19, R20, R21, R22, R23, R24, R25, R26, R27, R28, and R30. The IN terminal of the control chip IC2 is connected to one end of capacitor C20, one end of resistor R22, and the operational amplifier IC1A. The output terminal of amplifier IC1B is connected; the other end of capacitor C20 is connected to one end of capacitor C17, one end of capacitor C18, one end of resistor R20, and the inverting input terminal of operational amplifier IC1B; the other end of resistor R22 is connected to the other end of capacitor C18; the other end of resistor R20 is connected to one end of resistor R16, one end of resistor R21, and one end of resistor R24; the other end of resistor R21 is connected to the other end of capacitor C17; the other end of resistor R16 is connected to the DC positive terminal; the other end of resistor R24 ​​is grounded; the non-inverting input terminal of operational amplifier IC1B is connected to one end of resistor R23, one end of resistor R18, and one end of capacitor C19; the other end of resistor R23... The other end is connected to a -12V power supply; the other end of capacitor C19 is grounded; the other end of resistor R18 is connected to one end of resistor R26 and the output terminal of operational amplifier IC1A; the other end of resistor R26 is connected to one end of resistor R25 and the inverting input terminal of operational amplifier IC1A; the other end of resistor R25 is grounded; the non-inverting input terminal of operational amplifier IC1A is connected to one end of resistor R17 and one end of capacitor C16; the other end of resistor R17 is connected to connector CON3 and one end of resistor R19; the other end of resistor R19 and the other end of capacitor C16 are grounded; one end of capacitor C15 is grounded, and the other end is connected to the power supply terminal of operational amplifier IC1; the control The VC and VCC terminals of control chip IC2 are connected to one end of capacitor C22, one end of capacitor C23, the positive terminal of capacitor C21, and the +12V voltage; the other ends of capacitors C22 and C23, and the negative terminal of capacitor C21 are grounded; the RAMP and CT terminals of control chip IC2 are connected to one end of capacitor C24, and the other end of capacitor C24 is grounded; the SS terminal of control chip IC2 is connected to one end of capacitor C25, and the other end of capacitor C25 is grounded; the RT terminal of control chip IC2 is connected to one end of resistor R27, and the other end of resistor R27 is grounded; the VREF terminal of control chip IC2 is connected to one end of capacitor C29, and the other end of capacitor C29 is grounded.The OUTA terminal of the control chip IC2 is connected to the INA terminal of the driver amplifier chip IC3, and the OUTB terminal of the control chip IC2 is connected to the INB terminal of the driver amplifier chip IC3. The VDD terminal of the driver amplifier chip IC3 is connected to one end of capacitor C30, one end of capacitor C31, and the +12V voltage. The other ends of capacitor C30, the other end of capacitor C31, and the GND terminal of the driver amplifier chip IC3 are grounded. The OUTA terminal of the driver amplifier chip IC3 is connected to one end of resistor R28, and the other end of resistor R28 serves as a signal output terminal connected to the switch conversion module. The OUTB terminal of the driver amplifier chip IC3 is connected to one end of resistor R30, and the other end of resistor R30 serves as a signal output terminal connected to the switch conversion module.

5. The AC-DC circuit for an electrosurgical unit according to claim 4, characterized in that: The control module also includes a logic chip IC4, capacitors C26, C27, and C28, resistors R29 and R31, diodes VD5 and VD6. The ILM terminal of the control chip IC4 is connected to the cathode of diode VD6, and the anode of diode VD6 is connected to one end of capacitor C28 and one end of resistor R31. The other end of capacitor C28 is grounded. The other end of resistor R31 is connected to the Y terminal of logic chip IC4. The VCC terminal of logic chip IC4 is connected to +5V and to one end of capacitor C26, the other end of which is grounded. The A terminal of logic chip IC4 is connected to one end of resistor R29, the anode of diode VD5, and one end of capacitor C27. The other end of resistor R29 and the cathode of diode VD5 are connected to +5V. The other end of capacitor C27 is grounded.

6. The AC-DC circuit for an electrosurgical unit according to claim 3, characterized in that: The output module includes a transformer T1, a current transformer T2, a full-bridge rectifier B1, a transformer L1, capacitors C1, C2, C3, C6, C7, and C14, resistors R1, R6, R9, R12, R13, R14, and R15, and diodes VD1, VD2, VD3, and VD4. One end of the primary winding of the transformer T1 is connected to one end of capacitor C6 and one end of capacitor C7. The other end of capacitor C6 is connected to the midpoint of the bridge arm of MOSFETs Q1 and Q3. The other end of capacitor C7 is connected to one end of resistor R6. The other end of resistor R6 is connected to the other end of the primary winding of the transformer T1 and the AW1 port of the current transformer T2. The BW1 port of the current transformer T2 is connected to the midpoint of the bridge arm of MOSFETs Q2 and Q4. ； The two ends of the secondary winding of transformer T1 are connected to the AC input terminals of full-bridge rectifier B1. Resistor R1 and capacitor C3 are connected in series to the two ends of the secondary winding of transformer T1. The DC positive terminal of full-bridge rectifier B1 is connected to one end of the primary winding of transformer L1, and the other end of the primary winding of transformer L1 is connected to the positive terminals of capacitors C1 and C2, serving as the DC positive output interface. The DC negative terminal of full-bridge rectifier B1 is connected to one end of the secondary winding of transformer L1, and the other end of the secondary winding of transformer L1 is grounded to the negative terminals of capacitors C1 and C2, serving as the DC negative output interface. Resistor R9 is connected between the sampling signal output terminals of current transformer T2. Diodes VD1, VD2, VD3, and VD4 form a full-bridge rectifier unit, wherein the anode of diode VD1 and the cathode of diode VD3 are connected to one end of resistor R9, and the anode of diode VD2 and the cathode of diode VD4 are connected to the same end of resistor R9. The cathodes of diodes VD1 and VD2 are connected together, and the anodes of diodes VD3 and VD4 are connected together and grounded. One end of resistor R12 is connected to the junction of the cathodes of diodes VD1 and VD2. The other end of resistor R12 is connected to one end of capacitor C14 and one end of resistor R13. The other end of capacitor C14 is grounded. The other end of resistor R13 is connected to one end of resistor R14 and one end of resistor R15. The other end of resistor R15 and the other end of capacitor C14 are grounded together. The other end of resistor R14 serves as the current limiting signal output terminal.

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