Adjustable direct-current precise high-voltage reference source system for ultrahigh-resistance trimming machine

Abstract

The invention discloses an adjustable direct-current precise high-voltage reference source system for an ultrahigh-resistance trimming machine, which belongs to the field of precise electronic measurement technology and high-voltage technology, and comprises a pre-voltage-stabilizing rectification filtering and voltage doubling circuit, a low-voltage precise reference source circuit, an overvoltage protection circuit and a linear adjustment series voltage stabilizing circuit. The pre-voltage-stabilization rectification filtering and voltage doubling circuit provides adjustable direct-current voltage for the linear adjustment series voltage-stabilizing circuit, the low-voltage precision reference source circuit provides + 10V reference voltage for the linear adjustment series voltage-stabilizing circuit, and the overvoltage protection circuit is used for monitoring sampling voltage output by the linear adjustment series voltage-stabilizing circuit and providing protection signals. The precision and the stability of the system are determined by floating drive feedback control, pre-voltage stabilization and a low-voltage precision reference source, the performance of the system is far better than that of a reference source for directly stabilizing high voltage, high-voltage sampling is formed by an ultrahigh-stability resistance voltage divider and a reverse-phase amplification circuit, and the long-term stability of feedback signals is guaranteed.

Description

Technical Field

[0001] This invention belongs to the fields of precision electronic measurement technology and high voltage technology, and particularly relates to a design method and system for an adjustable DC precision high voltage reference source for an ultra-high impedance tuner. Background Technology

[0002] Ultra-high resistance trimmers are core devices used for the precise measurement and adjustment of ultra-high resistance in the G-ohm to T-ohm range. They are widely used in aerospace, military, medical (such as CT scanners), and scientific research fields. The principle of ultra-high resistance measurement typically employs the "voltage excitation-current measurement" method, which involves applying a precise, highly stable voltage to the ultra-high resistance resistor and calculating its resistance value—FVMI—by measuring the minute current flowing through the resistor.

[0003] The accuracy of this measurement system directly depends on the precision and stability of the applied voltage. The 0-1000V adjustable DC precision high-voltage reference source must meet the following stringent requirements: a. Extremely high output stability: Minimal temperature drift and time drift, typically required to be better than 10ppm / °C and tens of ppm / year; b. Extremely low output noise and ripple: Noise and ripple voltage need to be controlled in the millivolt to microvolt range to avoid interference current on the ultra-high impedance and affecting measurement accuracy.

[0004] c. High precision: The output voltage value is accurate and highly precise.

[0005] d. Good load regulation and line regulation: low sensitivity to input voltage fluctuations and load changes.

[0006] e. Safe and reliable: It has complete overvoltage, current limiting and short circuit protection functions.

[0007] Currently, common high-voltage source generation solutions mainly rely on transformer boosting or simple DC-DC module boosting, which generally suffer from problems such as high ripple noise, poor stability, and severe temperature drift, failing to meet the requirements of ultra-high resistance measurement. While linear high-voltage sources built using traditional discrete components have advantages in noise reduction, they are complex to design, consume a lot of power, have low efficiency, and are extremely difficult to select high-voltage components.

[0008] Therefore, there is an urgent need for an innovative design that can balance the requirements of high voltage output, low noise, high stability, high precision and high reliability.

[0009] It should be noted that the above content falls within the inventor's technical knowledge and does not necessarily constitute prior art. Summary of the Invention

[0010] To address the aforementioned problems, the present invention aims to provide an adjustable DC precision high-voltage reference source system for ultra-high impedance regulators, which features extremely low noise ripple, extremely high long-term stability and temperature stability, comprehensive protection functions, and easy output voltage adjustment and control.

[0011] To achieve the above objectives, this invention proposes an adjustable DC precision high-voltage reference source system for ultra-high impedance tuners. The system includes a pre-regulated rectifier filter and voltage multiplier circuit, a low-voltage precision reference source circuit, an overvoltage protection circuit, and a linear adjustment series voltage regulator circuit.

[0012] The pre-regulated rectifier filter and voltage multiplier circuit provides an adjustable DC voltage for the linearly regulated series voltage regulator circuit. The low-voltage precision reference source circuit provides a +10V reference voltage for the linearly regulated series voltage regulator circuit. The overvoltage protection circuit is used to monitor the output sampling voltage of the linearly regulated series voltage regulator circuit and provide a protection signal. The reference signals of the low-voltage precision reference source circuit and the overvoltage protection circuit are both floating ground, and the reference signals are at the same potential as the positive output terminal of the linear adjustment series voltage regulator circuit.

[0013] Furthermore, the pre-regulated rectifier filter and voltage multiplier circuit includes an adjustable power frequency transformer and three rectifier filter circuits. The secondary side of the transformer includes three sets of independently isolated windings. The three rectifier filter circuits are connected in parallel to the three sets of secondary windings respectively. A fuse is connected in series between the rectifier filter circuits and the secondary windings of the transformer. The three rectifier filter circuits are connected in series to provide approximately 1100V DC voltage to the subsequent stage.

[0014] Furthermore, the rectifier and filter circuit includes a full-bridge rectifier circuit, with the secondary winding of the transformer connected in series with a fuse and then connected in parallel to the input terminal of the corresponding full-bridge rectifier circuit. The output terminal of the full-bridge rectifier circuit is connected in parallel with a first filter capacitor and a discharge resistor.

[0015] The first filter capacitors in the three-way rectifier and filter circuit are connected in series. The positive terminal of the series connection is connected to VDC and supplies power to the subsequent stage, while the negative terminal is connected to the zero point of the output voltage, GND.

[0016] Furthermore, the low-voltage precision reference source circuit includes a reference source chip, a first adjustable potentiometer, a second filter capacitor, and a third filter capacitor.

[0017] The power input terminal and GND terminal of the reference source chip are connected to the +15V power supply and GNDS respectively, and are also connected to the two ends of the third filter capacitor. The output reference terminal of the reference source chip is connected to the +10V reference voltage measurement terminal. The two ends of the first adjustable potentiometer are connected to the output reference terminal and GND terminal of the reference source chip respectively, the intermediate adjustment terminal is connected to the TRIM adjustable terminal of the reference source chip, and the two ends of the capacitor are connected to the output reference terminal and GND terminal of the reference source chip respectively.

[0018] Furthermore, the overvoltage protection circuit includes a first voltage divider resistor, a second voltage divider resistor, a second adjustable potentiometer, a comparator, a thyristor, a first indicator light, an optocoupler, an output driver transistor, a reset switch, and an RC filter.

[0019] The first voltage divider resistor and the second voltage divider resistor are connected in series to form a first series circuit. One end of the first series circuit is connected to VOUTS and the other end is connected to GNDS. The positive terminal of the comparator input is connected between the first voltage divider resistor and the second voltage divider resistor. A fourth filter capacitor is connected in parallel with the second voltage divider resistor.

[0020] The two ends of the second adjustable potentiometer are connected to a +15V voltage source and GNDS, respectively. The middle adjustment terminal is connected to the negative input terminal of comparator N7. The negative power supply terminal of the comparator is connected to a -15V voltage source, and the power supply terminal is connected to a +15V voltage source. The output terminal is connected to the trigger circuit after passing through an RC filter.

[0021] Furthermore, the RC filter includes a first resistor and a first capacitor, which are connected in series to form a second series circuit.

[0022] One end of the first resistor is connected to the output of the comparator, and the other end is connected to one end of the first capacitor. The other end of the first capacitor is connected to GNDS. The gate of the thyristor is connected between the first resistor and the first capacitor, and the cathode of the thyristor is connected to GNDS. The anode of the thyristor is connected to the cathode of the first indicator light. The anode of the first indicator light is connected to both negative input control terminals of the optocoupler. A second resistor is connected in parallel to the first indicator light.

[0023] Furthermore, the overvoltage protection circuit also includes a third resistor, a fourth resistor, a fifth resistor, and a virtual load resistor. The two input control positive terminals of the optocoupler are connected to one end of the third resistor and the fourth resistor, respectively. The other ends of the third resistor and the fourth resistor are connected in parallel to one end of the reset switch. The other end of the reset switch is connected to the +5V power supply together with the first output positive terminal of the optocoupler.

[0024] The first negative output terminal of the optocoupler is connected to the base of the output driving transistor through the fifth resistor and drives it. The emitter of the driving transistor is connected to GNDS, and the collector is connected to the overvoltage protection terminal. One end of the virtual load resistor is connected to the first negative output terminal of the optocoupler, and the other end is connected to GNDS. The second output terminal of the optocoupler is left floating.

[0025] Furthermore, the linear adjustment series voltage regulator circuit includes a loading circuit, a sampling circuit, a feedback circuit, a linear adjustment circuit, and an output filter circuit.

[0026] Furthermore, the loading circuit includes a first switch, a dual-channel relay, a second indicator light, a third adjustable potentiometer, and a fifth filter capacitor.

[0027] One end of the first switch is connected to a +5V power supply, and the other end is connected to a first driving resistor and a second driving resistor. The second driving resistor is connected to the anode of the second indicator light, and the cathode of the second indicator light is connected to GNDS. When the first switch is closed, the second indicator light illuminates and the power supply outputs the set voltage value. When the first switch is open, the second indicator light goes out and the power supply output voltage is 0V.

[0028] The loading circuit also includes a sixth resistor and a seventh resistor, which are connected in series to form a third series circuit. One end of the third series circuit is connected to the first switch and the other end is connected between the first switch and the second driving resistor.

[0029] A PRO circuit is provided between the sixth and seventh resistors. The loading circuit also includes a first loading filter capacitor and a second loading filter capacitor. The first loading filter capacitor and the second loading filter capacitor are connected in series to form a fourth series circuit. One end of the fourth series circuit is connected between the sixth and seventh resistors, and the other end is connected to GNDS.

[0030] The negative control terminal of the first relay and the positive control terminal of the second relay of the dual-channel relay are both connected between the first loading filter capacitor and the second loading filter capacitor. The negative control terminal of the second relay of the dual-channel relay is connected to GNDS.

[0031] One end of the third adjustable potentiometer is connected to the +10V reference voltage, and the other end is connected to GNDS. The adjustable end is connected to one end of the fifth filter capacitor, and the other end of the fifth filter capacitor is connected to GNDS. The positive output terminal of the first relay of the dual-channel relay is connected to the adjustable end of the third adjustable potentiometer.

[0032] The loading circuit also includes an eighth resistor, a ninth resistor, and a Zener diode. The eighth and ninth resistors are connected in series to form a fifth series circuit. One end of the fifth series circuit is connected to the common terminal of the dual-channel relay, and the other end is connected to the cathode of the Zener diode.

[0033] Furthermore, the sampling circuit includes a first operational amplifier, a second operational amplifier, a protection diode, a fourth adjustable potentiometer, a tenth resistor, and an eleventh resistor.

[0034] The tenth and eleventh resistors are connected in series to form the sixth series circuit. One end of the tenth and eleventh resistors is connected to the non-inverting input of the first operational amplifier, and the other end is connected to OUT+.

[0035] The sampling circuit also includes a twelfth resistor and a second capacitor, which are connected in parallel to form a first parallel circuit. One end of the first parallel circuit is connected to the non-inverting input of the first operational amplifier, and the other end is grounded.

[0036] The sampling circuit also includes a thirteenth resistor, a fourteenth resistor, a fifteenth resistor, a sixteenth resistor, and a seventeenth resistor. The thirteenth resistor and the seventeenth resistor are connected in series to form a seventh series circuit. One end of the seventh series circuit is connected to the inverting input terminal of the first operational amplifier, and the other end is connected to OUT-.

[0037] The sampling circuit also includes an eighteenth resistor and a third capacitor, which are connected in parallel to form a second parallel circuit. One end of the second parallel circuit is connected to the inverting input terminal of the first operational amplifier, and the other end is connected to the output terminal of the first operational amplifier.

[0038] The anode of the protection diode is connected to a -15V power supply, and the cathode is connected to the inverting input of the first operational amplifier.

[0039] The sampling circuit also includes a nineteenth resistor and a fourth capacitor. One end of the nineteenth resistor is connected to the output terminal of the first operational amplifier, and the other end is connected to one end of the fourth adjustable potentiometer. The other end of the adjustable potentiometer is connected to GNDS. One end of the fourth capacitor is connected to the adjustable terminal of the fourth adjustable potentiometer, and the other end is connected to GNDS. The sampling circuit also includes a twentieth resistor. The inverting input terminal and the output terminal of the second operational amplifier are connected to one end of the twentieth resistor, and the other end of the twentieth resistor is connected to GNDS. The negative power supply terminal of the second operational amplifier is connected to a -15V power supply, and the positive power supply terminal is connected to a +15V power supply.

[0040] The feedback circuit includes a third operational amplifier, an input reference voltage, and an output sampling voltage.

[0041] The input reference voltage is output through the common terminal of the dual relay. The feedback circuit also includes a 21st resistor and a 5th capacitor. One end of the 21st resistor is connected between the 8th and 9th resistors, and the other end is connected to the non-inverting input terminal of the 3rd operational amplifier. The 5th capacitor is connected in parallel with the 9th resistor.

[0042] The negative power supply terminal of the third operational amplifier is connected between the Zener diode and the fifth series circuit. The anode of the Zener diode is connected to the -15V power supply, and the cathode of the Zener diode is connected to the negative power supply terminal of the third operational amplifier.

[0043] The positive power supply terminal of the third op-amp is connected to the +15V power supply.

[0044] The third operational amplifier also includes a twenty-second resistor. One end of the twenty-second resistor is connected to the inverting input terminal of the first operational amplifier, and the other end is connected to the inverting input terminal of the third operational amplifier. The output sampling voltage is fed back from the output terminal of the first operational amplifier to the inverting input terminal of the third operational amplifier through the twenty-second resistor.

[0045] The feedback circuit also includes a 23rd resistor and a 7th capacitor, which are connected in series to form an 8th series circuit.

[0046] One end of the eighth series circuit is connected to the inverting input of the third operational amplifier, and the other end is connected to the output of the third operational amplifier.

[0047] The linear adjustment series voltage regulator circuit also includes a twenty-third resistor and a twenty-second resistor.

[0048] The linear adjustment circuit includes an adjustment transistor, a current-limiting sampling resistor, a second transistor, and a twenty-fourth resistor; One end of the 22nd resistor is connected to the common output terminal of the second relay of the dual-channel relay, and the other end of the 22nd resistor is connected to the gate of the regulating transistor; the drain of the regulating transistor is connected to VDC, and the anode and cathode of the Zener diode are connected to the source stage and the gate of the regulating transistor, respectively.

[0049] The source of the regulating transistor and the base of the second transistor are both connected to one end of the current-limiting sampling resistor; the emitter of the second transistor is connected to the other end of the current-limiting sampling resistor, and the collector of the second transistor is connected to the gate of the regulating transistor VM1.

[0050] The maximum output current of the regulating transistor VM1 is limited to approximately 0.7V / R, where R is the resistance value of the current-limiting sampling resistor.

[0051] One end of the 24th resistor is connected to the gate of the regulating transistor, and the other end is connected to the source of the regulating transistor through a current-limiting sampling resistor. The emitter of the second transistor is connected to OUT+.

[0052] One end of the twenty-third resistor is connected to the normally open contact of the second relay of the dual-channel relay, and the other end is connected to the output of the third operational amplifier.

[0053] The output filter circuit includes three sets of RC filter series circuits. The RC filter series circuit includes the twenty-fourth resistor and the twenty-fifth resistor. The twenty-fourth resistor and the twenty-fifth resistor are connected in series to form the ninth series circuit. The sixth filter capacitor is connected in parallel to the ninth series circuit. The sixth filter capacitors are connected in series to form the tenth series circuit. The positive terminal of the tenth series circuit is connected to OUT+, and the negative terminal is connected to OUT-.

[0054] The linear adjustment series voltage regulator circuit also includes an output port of an adjustable reference source from 0 to 1000V. The high voltage output positive terminal of the output port is connected to OUT+, and the reference ground terminal is connected to OUT-.

[0055] The output filtering circuit also includes a first common-mode filter capacitor and a second common-mode filter capacitor. The first common-mode filter capacitor and the second common-mode filter capacitor are connected in series to form an eleventh series circuit. EARTH is connected between the first common-mode filter capacitor and the second common-mode filter capacitor. The positive terminal of the eleventh series circuit is connected to OUT+, the negative terminal is connected to OUT-, and OUT- is connected to GND.

[0056] The adjustable DC precision high-voltage reference source system for ultra-high impedance tuning machines proposed in this invention can bring the following beneficial effects: 1. The accuracy and stability of the system of the present invention are determined by the floating drive feedback control, pre-stabilization and low-voltage precision reference source. Its performance is far superior to the reference source that directly stabilizes the high voltage. The high voltage sampling is composed of an ultra-high stability resistor voltage divider and an inverting amplifier circuit, which ensures the long-term stability of the feedback signal. 2. The system of this invention adopts a hybrid architecture of "adjustable power frequency rectification + pre-regulation + linear fine-tuning mode". The pre-regulation rectification filter and voltage multiplier circuit operates at 50Hz power frequency, and the ripple noise generated by it can be suppressed to the maximum extent by the subsequent linear adjustment series voltage regulator circuit, finally obtaining an output high voltage reference source with extremely low noise; 3. The pre-regulated rectifier filter and voltage multiplier circuit in the system of the present invention supplies power to the linear adjustment series voltage regulator circuit. The pre-regulated output voltage VDC is automatically adjusted according to the output voltage value to reduce the Vds of the power devices in the linear adjustment series voltage regulator circuit (e.g., a maximum of 50V), thereby reducing its power consumption and heat generation, and improving the overall reliability of the system. 4. The overvoltage protection circuit and the current limiting protection circuit in the linear adjustment series voltage regulator circuit of the present invention effectively prevent equipment damage caused by output overvoltage and short circuit abnormalities. Attached Figure Description

[0057] The accompanying drawings, which are included to provide a further understanding of the invention and form part of this invention, illustrate exemplary embodiments of the invention and are used to explain the invention, but do not constitute an undue limitation of the invention. In the drawings: Figure 1 This is a block diagram of the 0-1000V adjustable DC precision high voltage reference source system of the present invention.

[0058] Figure 2 This is a circuit diagram of the pre-regulated rectifier filter and voltage multiplier of the present invention.

[0059] Figure 3 This is the circuit diagram of the low-voltage precision reference source of the present invention.

[0060] Figure 4 This is the overvoltage protection circuit diagram of the present invention.

[0061] Figure 5 This is a diagram of the linear adjustment series voltage regulator circuit of the present invention. Detailed Implementation

[0062] To more clearly illustrate the overall concept of the present invention, a detailed description will be provided below with reference to the accompanying drawings and examples.

[0063] Embodiments of the present invention propose an adjustable DC precision high-voltage reference source system for an ultra-high impedance tuner, such as... Figure 1 As shown, the system includes a pre-regulated rectifier filter and voltage multiplier circuit, a low-voltage precision reference source circuit, an overvoltage protection circuit, and a linear adjustment series voltage regulator circuit.

[0064] The pre-regulated rectifier filter and voltage multiplier circuit provides an adjustable DC voltage VDC for the linearly regulated series voltage regulator circuit. The low-voltage precision reference source circuit provides a +10V reference voltage for the linearly regulated series voltage regulator circuit. The overvoltage protection circuit monitors the output sampling voltage VOUTS of the linearly regulated series voltage regulator circuit and provides a protection signal PRO. The reference signal GNDS of both the low-voltage precision reference source circuit and the overvoltage protection circuit is floating. The potential of GNDS is basically the same as that of the positive terminal OUT+ of the linearly regulated series voltage regulator circuit. The floating drive control is the main feature of this invention. This drive method can enhance the accuracy and stability of the output voltage, simplify the circuit design, and increase the output voltage level.

[0065] The pre-regulated rectifier filter and voltage multiplier circuit includes an adjustable power frequency transformer X2 and a three-way rectifier filter circuit, such as... Figure 2 As shown, the secondary side of transformer X2 includes three sets of independently isolated windings. Three rectifier and filter circuits are connected in parallel to the three sets of secondary windings. A fuse F3F is connected in series between the rectifier and filter circuits and the secondary windings of transformer X2. The three rectifier and filter circuits are connected in series to provide approximately 1100V DC voltage to the subsequent stage.

[0066] The rectifier and filter circuit includes a full-bridge rectifier circuit. The secondary winding of transformer X2 is connected in series with a fuse and then in parallel to the input terminal of the corresponding full-bridge rectifier circuit. The output terminal of the full-bridge rectifier circuit is connected in parallel with a first filter capacitor C15F and a discharge resistor.

[0067] The primary winding (pins 7-8) of transformer X2 is the input terminal, connected to 220Vac AC mains power. The three windings of the secondary winding of transformer X2 (pins 1-2, 3-4, and 5-6) have the same number of turns. The maximum ratio of the number of turns on the primary winding to the number of turns on the three secondary windings of transformer X2 is 1:1.2. In actual operation, the ratio of the primary and secondary windings is automatically adjusted according to the output DC voltage setting.

[0068] The first filter capacitors in the three-way rectifier and filter circuit are connected in series. The positive terminal of the series connection is connected to VDC and supplies power to the subsequent stage, while the negative terminal is connected to the zero point of the output voltage, GND.

[0069] The low-voltage precision reference source circuit includes a reference source chip N3, a first adjustable potentiometer RV3, a second filter capacitor C37, and a third filter capacitor C38, such as... Figure 3 As shown.

[0070] The power input terminal (pin 2) and GND terminal (pin 4) of the reference source chip N3 are connected to the +15V and GND terminals respectively, and are also connected to the two ends of the third filter capacitor C38 for filtering to improve the stability of the power supply of the reference source chip N3. The output reference terminal (pin 6) of the reference source chip N3 is connected to the +10V reference voltage measurement terminal. The two ends of the first adjustable potentiometer RV3 are connected to the output reference terminal (pin 6) and GND terminal (pin 4) of the reference source chip N3 respectively, and the intermediate adjustment terminal is connected to the TRIM adjustable terminal (pin 5) of the reference source chip N3 to achieve accurate adjustment of the +10.000V reference voltage. The two ends of capacitor C37 are connected to the output reference terminal (pin 6) and GND terminal (pin 4) of the reference source chip N3 respectively to filter the output reference voltage. The floating pins (pins 1, 3, 7 and 8) of the reference source chip N3 are left floating.

[0071] The overvoltage protection circuit includes a first voltage divider resistor R35, a second voltage divider resistor R36, a second adjustable potentiometer RV4, a comparator N7, a thyristor VS1, a first indicator light VL2, an optocoupler N2, an output driver transistor VT3, a reset switch JP1, and an RC filter, such as... Figure 4 As shown.

[0072] The first voltage divider resistor R35 and the second voltage divider resistor R36 are connected in series to form a first series circuit, which is used to divide the output sampling voltage VOUTS. One end of the first series circuit is connected to VOUTS and the other end is connected to GNDS. The positive terminal (pin 3) of the input terminal of comparator N7 is connected between the first voltage divider resistor R35 and the second voltage divider resistor R36. A fourth filter capacitor C39 is connected in parallel with the second voltage divider resistor R36 to make the comparison voltage more stable.

[0073] The two ends of the second adjustable potentiometer RV4 are connected to a +15V voltage source and GNDS, respectively. The middle adjustment terminal is connected to the negative input terminal (pin 2) of comparator N7 to provide overvoltage protection value setting. The negative power supply terminal (pin 4) of comparator N7 is connected to a -15V voltage source, the power supply terminal (pin 7) is connected to a +15V voltage source, and the output terminal (pin 6) is connected to the trigger circuit after passing through an RC filter.

[0074] The RC filter includes a first resistor R37 and a first capacitor C40, which are connected in series to form a second series circuit.

[0075] One end of the first resistor R37 is connected to the output terminal (pin 6) of comparator N7, and the other end is connected to one end of the first capacitor C40. The other end of the first capacitor C40 is connected to GNDS. The gate of thyristor VS1 is connected between the first resistor R37 and the first capacitor C40, and the cathode of thyristor VS1 is connected to GNDS. The anode of thyristor VS1 is connected to the cathode of the first indicator light VL2. The anode of the first indicator light VL2 is connected to both input control negative terminals (pins 2 and 4) of optocoupler N2. A second resistor R38 is connected in parallel to the first indicator light VL2. When the power supply output is overvoltage, the first indicator light VL2 will work and light up. During overvoltage protection, R38 provides a larger freewheeling current to thyristor VS1 to keep the thyristor conducting continuously.

[0076] The overvoltage protection circuit also includes a third resistor R39, a fourth resistor R40, a fifth resistor R42, and a virtual load resistor R41. The two input control positive terminals (pin 1 and pin 3) of the optocoupler N2 are connected to one end of the third resistor R39 and the fourth resistor R40, respectively. The other ends of the third resistor R39 and the fourth resistor R40 are connected in parallel to one end of the reset switch JP1. The other end of the reset switch JP1 is connected to the +5V power supply together with the first output positive terminal (pin 8) of the optocoupler N2.

[0077] The first negative output terminal (pin 7) of optocoupler N2 is connected to the base of output driver transistor VT3 through the fifth resistor R42 and drives it. The emitter of the driver transistor VT3 is connected to GNDS, and the collector is connected to the overvoltage protection terminal PRO. One end of the virtual load resistor R41 is connected to the first negative output terminal of optocoupler N2, and the other end is connected to GNDS. The second output terminal (pins 5 and 6) of optocoupler N2 is left floating.

[0078] A linearly adjustable series voltage regulator circuit includes a loading circuit, a sampling circuit, a feedback circuit, a linear adjustment circuit, and an output filter circuit, such as... Figure 5 As shown.

[0079] The loading circuit includes a first switch JP2, a dual-channel relay N1, a second indicator light VL1, a third adjustable potentiometer RV1, and a fifth filter capacitor C28.

[0080] One end of the first switch JP2 is connected to a +5V power supply, and the other end is connected to a first driving resistor R2 and a second driving resistor R22. The second driving resistor R22 is connected to the anode of the second indicator light VL1, and the cathode of the second indicator light VL1 is connected to GNDS. When the first switch JP2 is closed, the second indicator light VL1 lights up and the power supply outputs a set voltage value. When the first switch JP2 is open, the second indicator light VL1 goes out and the power supply output voltage is 0V.

[0081] The loading circuit also includes a sixth resistor R2 and a seventh resistor R3. The sixth resistor R2 and the seventh resistor R3 are connected in series to form a third series circuit. One end of the third series circuit is connected to GNDS, and the other end is connected between the first switch JP2 and the second driving resistor R22.

[0082] A PRO (output overvoltage protection signal input terminal) is provided between the sixth resistor R2 and the seventh resistor R3. The loading circuit also includes a first loading filter capacitor C17 and a second loading filter capacitor C18. The first loading filter capacitor C17 and the second loading filter capacitor C18 are connected in series to form a fourth series circuit. One end of the fourth series circuit is connected between the sixth resistor R2 and the seventh resistor R3, and the other end is connected to GNDS.

[0083] The negative control terminal (pin 2) and the positive control terminal (pin 3) of the first relay of the dual-channel relay N1 are both connected between the first loading filter capacitor C17 and the second loading filter capacitor C18. The negative control terminal (pin 4) of the second relay of the dual-channel relay N1 is connected to GNDS.

[0084] One end of the third adjustable potentiometer RV1 is connected to the +10V reference voltage, and the other end is connected to GNDS. The adjustable end is connected to one end of the fifth filter capacitor C28, and the other end of the fifth filter capacitor C28 is connected to GNDS. The positive output terminal (pin 8) of the first relay of the dual-channel relay N1 is connected to the adjustable end of the third adjustable potentiometer RV1.

[0085] The loading circuit also includes an eighth resistor R4, a ninth resistor R5, and a Zener diode VE1. The eighth resistor R4 and the ninth resistor R5 are connected in series to form a fifth series circuit. One end of the fifth series circuit is connected to the common terminal (pin 7) of the dual-channel relay N1, and the other end is connected to the cathode of the Zener diode VE1.

[0086] The sampling circuit includes a first operational amplifier N6B, a second operational amplifier N6A, a protection diode VD25, a fourth adjustable potentiometer RV2, a tenth resistor R29, and an eleventh resistor RS1.

[0087] The tenth resistor R29 and the eleventh resistor RS1 are connected in series to form the sixth series circuit. One end of the tenth resistor R29 and the eleventh resistor RS1 is connected to the non-inverting input terminal (pin 5) of the first operational amplifier N6B, and the other end is connected to the positive output terminal OUT+.

[0088] The sampling circuit also includes a twelfth resistor R24 ​​and a second capacitor C31. The twelfth resistor R24 ​​and the second capacitor C31 are connected in parallel to form a first parallel circuit. One end of the first parallel circuit is connected to the non-inverting input terminal of the first operational amplifier N6B, and the other end is grounded.

[0089] The sampling circuit also includes a thirteenth resistor RS6, a fourteenth resistor RS7, a fifteenth resistor RS8, a sixteenth resistor RS9, and a seventeenth resistor RS10. The thirteenth resistor RS6 and the seventeenth resistor RS10 are connected in series to form a seventh series circuit. One end of the seventh series circuit is connected to the inverting input terminal (pin 6) of the first operational amplifier N6B, and the other end is connected to the negative output voltage OUT-.

[0090] The sampling circuit also includes an eighteenth resistor R43 and a third capacitor C29. The eighteenth resistor R43 and the third capacitor C29 are connected in parallel to form a second parallel circuit. One end of the second parallel circuit is connected to the inverting input terminal of the first operational amplifier N6B, and the other end is connected to the output terminal (pin 7) of the first operational amplifier N6B.

[0091] The anode of the protection diode VD25 is connected to a -15V power supply, and the cathode is connected to the inverting input terminal of the first operational amplifier N6B for voltage limiting protection at the operational amplifier input terminal.

[0092] The sampling circuit also includes a nineteenth resistor R23 and a fourth capacitor C30. One end of the nineteenth resistor R23 is connected to the output terminal of the first operational amplifier N6B, and the other end is connected to one end of the fourth adjustable potentiometer RV2. The other end of the adjustable potentiometer RV2 is connected to GNDS. One end of the fourth capacitor C30 is connected to the adjustable terminal of the fourth adjustable potentiometer RV2, and the other end is connected to GNDS.

[0093] The sampling circuit also includes a twentieth resistor R25. The inverting input (pin 2) and output (pin 1) of the second operational amplifier N6A are connected to one end of the twentieth resistor R25, and the other end of the twentieth resistor R25 is connected to VOUTS for output voltage value display and overvoltage protection circuit. The negative power supply (pin 4) of the second operational amplifier N6A is connected to the -15V power supply, and the positive power supply (pin 8) is connected to the +15V power supply.

[0094] The feedback circuit includes the third operational amplifier N5, the input reference voltage, and the output sampling voltage.

[0095] The input reference voltage is output through the common terminal of the dual relay N1. The feedback circuit also includes the twenty-first resistor R6 and the fifth capacitor C19. One end of the twenty-first resistor R6 is connected between the eighth resistor R4 and the ninth resistor R5, and the other end is connected to the non-inverting input terminal (pin 3) of the third operational amplifier N5, thereby realizing the connection between the input reference voltage and the positive input terminal of the third operational amplifier N5.

[0096] The fifth capacitor C19 is connected in parallel with the ninth resistor R5 to filter the input reference voltage.

[0097] The negative power supply terminal (pin 4) of the third operational amplifier N5 is connected between the Zener diode VE1 and the fifth series circuit. The anode of the Zener diode VE1 is connected to the -15V power supply, and the cathode of the Zener diode VE1 is connected to the negative power supply terminal of the third operational amplifier N5.

[0098] The positive power supply terminal (pin 7) of the third operational amplifier N5 is connected to a +15V power supply to ensure normal power supply for the operational amplifier.

[0099] The third operational amplifier also includes a twenty-second resistor R7. One end of the twenty-second resistor R7 is connected to the inverting input terminal (pin 2) of N5, and the other end is connected to the inverting input terminal (pin 2) of the third operational amplifier N5. The output sampling voltage is fed back from the output terminal of the first operational amplifier N6B to the inverting input terminal of the third operational amplifier N5 through the twenty-second resistor R7.

[0100] The feedback circuit also includes the twenty-third resistor R8 and the seventh capacitor C20. The twenty-third resistor R8 and the seventh capacitor C20 are connected in series to form the eighth series circuit to achieve feedback stability regulation.

[0101] One end of the eighth series circuit is connected to the inverting input terminal (pin 2) of the third operational amplifier N5, and the other end is connected to the output terminal (pin 6) of the third operational amplifier N5.

[0102] The linear adjustment series voltage regulator circuit also includes the twenty-third resistor R9 and the twenty-second resistor R12.

[0103] The linear adjustment circuit includes an adjustment transistor VM1, a current-limiting sampling resistor R13, a second transistor VT1, and a twenty-fourth resistor R11.

[0104] One end of the 22nd resistor R12 is connected to the common output terminal (pin 5) of the second relay of the dual-channel relay N1, and the other end of the 22nd resistor R12 is connected to the gate of the regulating transistor VM1 to drive it. The drain of the regulating transistor VM1 is connected to VDC for power supply. The anode and cathode of the Zener diode VE3 are connected to the source and gate of the regulating transistor VM1, respectively. The driving voltage protection of the regulating transistor VM1 is provided by the Zener diode VE3 and the 22nd resistor R12.

[0105] The source of the regulating transistor VM1 and the base of the second transistor VT1 are both connected to one end of the current-limiting sampling resistor R13; the emitter of the second transistor VT1 is connected to the other end of the current-limiting sampling resistor R13, and the collector of the second transistor VT1 is connected to the gate of the regulating transistor VM1, thus limiting the maximum output current of the regulating transistor VM1 to about 0.7V / R, where R is the resistance value of the current-limiting sampling resistor R13.

[0106] One end of the twenty-fourth resistor R11 is connected to the gate of the regulating transistor VM1, and the other end is connected to the source of the regulating transistor VM1 through the current-limiting sampling resistor R13. It is used to discharge the charge stored in the gate and source of the regulating transistor VM1. The emitter of the second transistor VT1 is connected to the positive output terminal OUT+ of the 0-1000V reference source.

[0107] One end of the 23rd resistor R9 is connected to the normally open contact (pin 6) of the second relay of the dual-channel relay N1, and the other end is connected to the output of the third operational amplifier N5. By controlling the dual-channel relay N1, the driving of the regulating transistor VM1 in the linear adjustment circuit is turned on and off, thereby realizing the output voltage control.

[0108] The output filter circuit includes three sets of RC filter series circuits. The RC filter series circuit includes the twenty-fourth resistor R15A and the twenty-fifth resistor R15B. The twenty-fourth resistor R15A and the twenty-fifth resistor R15B are connected in series to form the ninth series circuit. The sixth filter capacitor C21F is connected in parallel to the ninth series circuit. The sixth filter capacitors C21F are connected in series to form the tenth series circuit. The positive terminal of the tenth series circuit is connected to the positive output terminal OUT+, and the negative terminal is connected to the negative output terminal OUT-.

[0109] The linear adjustment series voltage regulator circuit also includes an output port X4 of an adjustable reference source from 0 to 1000V. The high voltage output positive terminal (pin 1) of the output port X4 is connected to the output positive terminal OUT+, and the reference ground terminal (pin 2) is connected to the output negative terminal OUT-.

[0110] The output filtering circuit also includes a first common-mode filter capacitor C23 and a second common-mode filter capacitor C24. The first common-mode filter capacitor C23 and the second common-mode filter capacitor C24 are connected in series to form an eleventh series circuit. EARTH is connected between the first common-mode filter capacitor C23 and the second common-mode filter capacitor C24. The positive terminal of the eleventh series circuit is connected to OUT+, and the negative terminal is connected to OUT-. The output negative terminal OUT- is connected to GND.

[0111] The reference source chip N3 is a bandgap reference source or Zener reference source chip placed in a constant temperature environment, preferably the AD587 chip.

[0112] The third operational amplifier N5 is preferably the ultra-low noise operational amplifier AD797.

[0113] The regulating transistor VM1 is preferably a high-power MOSFET IPP50R250CP with an input withstand voltage of 1200V.

[0114] The resistance values ​​of the thirteenth resistor RS6, the fourteenth resistor RS7, the fifteenth resistor RS8, the sixteenth resistor RS9, and the seventeenth resistor RS10 are preferably precision metal foil resistors with a resistance of 200kΩ, an accuracy of 0.01%, and a temperature drift of 0.5ppm / °C.

[0115] The various embodiments in this specification are described in a progressive manner. Similar or identical parts between embodiments can be referred to interchangeably. Each embodiment focuses on describing the differences from other embodiments. In particular, the system embodiments are basically similar to the method embodiments, so the description is relatively simple; relevant parts can be referred to the descriptions in the method embodiments.

[0116] The above description is merely an embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principle of the present invention should be included within the scope of the claims of the present invention.

Claims

1. An adjustable DC precision high-voltage reference source system for an ultra-high impedance regulating motor, the system comprising a pre-regulated rectifier filter and voltage multiplier circuit, a low-voltage precision reference source circuit, an overvoltage protection circuit, and a linear adjustment series voltage regulator circuit, characterized in that: The pre-regulated rectifier filter and voltage multiplier circuit provides an adjustable DC voltage for the linearly regulated series voltage regulator circuit. The low-voltage precision reference source circuit provides a +10V reference voltage for the linearly regulated series voltage regulator circuit. The overvoltage protection circuit is used to monitor the output sampling voltage of the linearly regulated series voltage regulator circuit and provide a protection signal. The reference signals of the low-voltage precision reference source circuit and the overvoltage protection circuit are both floating ground, and the reference signals are at the same potential as the positive output terminal of the linear adjustment series voltage regulator circuit.

2. The adjustable DC precision high-voltage reference source system for an ultra-high impedance tuning machine according to claim 1, characterized in that, The pre-regulated rectifier filter and voltage multiplier circuit includes an adjustable power frequency transformer and three rectifier filter circuits. The secondary side of the transformer includes three sets of independently isolated windings. The three rectifier filter circuits are connected in parallel to the three sets of secondary windings. A fuse is connected in series between the rectifier filter circuits and the secondary windings of the transformer. The three rectifier filter circuits are connected in series to provide approximately 1100V DC voltage to the subsequent stage.

3. The adjustable DC precision high-voltage reference source system for an ultra-high impedance tuning machine according to claim 2, characterized in that, The rectifier and filter circuit includes a full-bridge rectifier circuit. The secondary winding of the transformer is connected in series with a fuse and then connected in parallel to the input terminal of the corresponding full-bridge rectifier circuit. The output terminal of the full-bridge rectifier circuit is connected in parallel with a first filter capacitor and a discharge resistor. The first filter capacitors in the three-way rectifier and filter circuit are connected in series. The positive terminal of the series connection is connected to VDC and supplies power to the subsequent stage, while the negative terminal is connected to the zero point of the output voltage, GND.

4. The adjustable DC precision high-voltage reference source system for an ultra-high impedance tuning machine according to claim 3, characterized in that, The low-voltage precision reference source circuit includes a reference source chip, a first adjustable potentiometer, a second filter capacitor, and a third filter capacitor; The power input terminal and GND terminal of the reference source chip are connected to the +15V power supply and GNDS respectively, and are also connected to the two ends of the third filter capacitor. The output reference terminal of the reference source chip is connected to the +10V reference voltage measurement terminal. The two ends of the first adjustable potentiometer are connected to the output reference terminal and GND terminal of the reference source chip respectively, the intermediate adjustment terminal is connected to the TRIM adjustable terminal of the reference source chip, and the two ends of the capacitor are connected to the output reference terminal and GND terminal of the reference source chip respectively.

5. The adjustable DC precision high-voltage reference source system for an ultra-high impedance tuning machine according to claim 4, characterized in that, The overvoltage protection circuit includes a first voltage divider resistor, a second voltage divider resistor, a second adjustable potentiometer, a comparator, a thyristor, a first indicator light, an optocoupler, an output driver transistor, a reset switch, and an RC filter. The first voltage divider resistor and the second voltage divider resistor are connected in series to form a first series circuit. One end of the first series circuit is connected to VOUTS and the other end is connected to GNDS. The positive terminal of the comparator input is connected between the first voltage divider resistor and the second voltage divider resistor. A fourth filter capacitor is connected in parallel with the second voltage divider resistor. The two ends of the second adjustable potentiometer are connected to a +15V voltage source and GNDS, respectively. The middle adjustment terminal is connected to the negative input terminal of comparator N7. The negative power supply terminal of the comparator is connected to a -15V voltage source, and the power supply terminal is connected to a +15V voltage source. The output terminal is connected to the trigger circuit after passing through an RC filter.

6. The adjustable DC precision high-voltage reference source system for an ultra-high impedance tuning machine according to claim 5, characterized in that, The RC filter includes a first resistor and a first capacitor, which are connected in series to form a second series circuit. One end of the first resistor is connected to the output of the comparator, and the other end is connected to one end of the first capacitor. The other end of the first capacitor is connected to GNDS. The gate of the thyristor is connected between the first resistor and the first capacitor, and the cathode of the thyristor is connected to GNDS. The anode of the thyristor is connected to the cathode of the first indicator light. The anode of the first indicator light is connected to both negative input control terminals of the optocoupler. A second resistor is connected in parallel to the first indicator light.

7. The adjustable DC precision high-voltage reference source system for an ultra-high impedance tuning machine according to claim 6, characterized in that, The overvoltage protection circuit also includes a third resistor, a fourth resistor, a fifth resistor, and a virtual load resistor. The two input control positive terminals of the optocoupler are connected to one end of the third resistor and the fourth resistor, respectively. The other ends of the third resistor and the fourth resistor are connected in parallel to one end of the reset switch. The other end of the reset switch and the first output positive terminal of the optocoupler are connected to a +5V power supply. The first negative output terminal of the optocoupler is connected to the base of the output driving transistor through the fifth resistor and drives it. The emitter of the driving transistor is connected to GNDS, and the collector is connected to the overvoltage protection terminal. One end of the virtual load resistor is connected to the first negative output terminal of the optocoupler, and the other end is connected to GNDS. The second output terminal of the optocoupler is left floating.

8. The adjustable DC precision high-voltage reference source system for an ultra-high impedance tuning machine according to claim 7, characterized in that, The linear adjustment series voltage regulator circuit includes a loading circuit, a sampling circuit, a feedback circuit, a linear adjustment circuit, and an output filter circuit.

9. The adjustable DC precision high-voltage reference source system for an ultra-high impedance tuning machine according to claim 8, characterized in that, The loading circuit includes a first switch, a dual-channel relay, a second indicator light, a third adjustable potentiometer, and a fifth filter capacitor; One end of the first switch is connected to a +5V power supply, and the other end is connected to a first driving resistor and a second driving resistor. The second driving resistor is connected to the anode of the second indicator light, and the cathode of the second indicator light is connected to GNDS. When the first switch is closed, the second indicator light illuminates and the power supply outputs a set voltage value. When the first switch is open, the second indicator light goes out and the power supply output voltage is 0V. The loading circuit also includes a sixth resistor and a seventh resistor, which are connected in series to form a third series circuit. One end of the third series circuit is connected to the first switch and the other end is connected between the second drive resistor. PRO is provided between the sixth resistor and the seventh resistor. The loading circuit also includes a first loading filter capacitor and a second loading filter capacitor. The first loading filter capacitor and the second loading filter capacitor are connected in series to form a fourth series circuit. One end of the fourth series circuit is connected between the sixth resistor and the seventh resistor, and the other end is connected to GNDS. The negative control terminal of the first relay and the positive control terminal of the second relay of the dual-channel relay are both connected between the first loading filter capacitor and the second loading filter capacitor. The negative control terminal of the second relay of the dual-channel relay is connected to GNDS. One end of the third adjustable potentiometer is connected to the +10V reference voltage, and the other end is connected to GNDS. The adjustable end is connected to one end of the fifth filter capacitor, and the other end of the fifth filter capacitor is connected to GNDS. The positive output terminal of the first relay of the dual relay is connected to the adjustable end of the third adjustable potentiometer. The loading circuit also includes an eighth resistor, a ninth resistor, and a Zener diode. The eighth and ninth resistors are connected in series to form a fifth series circuit. One end of the fifth series circuit is connected to the common terminal of the dual-channel relay, and the other end is connected to the cathode of the Zener diode.

10. The adjustable DC precision high-voltage reference source system for an ultra-high impedance tuning machine according to claim 9, characterized in that, The sampling circuit includes a first operational amplifier, a second operational amplifier, a protection diode, a fourth adjustable potentiometer, a tenth resistor, and an eleventh resistor; The tenth and eleventh resistors are connected in series to form the sixth series circuit. One end of the tenth and eleventh resistors is connected to the non-inverting input of the first operational amplifier, and the other end is connected to OUT+. The sampling circuit also includes a twelfth resistor and a second capacitor, which are connected in parallel to form a first parallel circuit. One end of the first parallel circuit is connected to the non-inverting input of the first operational amplifier, and the other end is grounded. The sampling circuit also includes a thirteenth resistor, a fourteenth resistor, a fifteenth resistor, a sixteenth resistor, and a seventeenth resistor. The thirteenth resistor and the seventeenth resistor are connected in series to form a seventh series circuit. One end of the seventh series circuit is connected to the inverting input terminal of the first operational amplifier, and the other end is connected to OUT-. The sampling circuit also includes an eighteenth resistor and a third capacitor. The eighteenth resistor and the third capacitor are connected in parallel to form a second parallel circuit. One end of the second parallel circuit is connected to the inverting input terminal of the first operational amplifier, and the other end is connected to the output terminal of the first operational amplifier. The anode of the protection diode is connected to a -15V power supply, and the cathode is connected to the inverting input of the first operational amplifier. The sampling circuit also includes a nineteenth resistor and a fourth capacitor. One end of the nineteenth resistor is connected to the output of the first operational amplifier, and the other end is connected to one end of the fourth adjustable potentiometer. The other end of the adjustable potentiometer is connected to GNDS. One end of the fourth capacitor is connected to the adjustable end of the fourth adjustable potentiometer, and the other end is connected to GNDS. The sampling circuit also includes a twentieth resistor. The inverting input and output of the second operational amplifier are connected to one end of the twentieth resistor, and the other end of the twentieth resistor is connected to GNDS. The negative power supply terminal of the second operational amplifier is connected to a -15V power supply, and the positive power supply terminal is connected to a +15V power supply. The feedback circuit includes a third operational amplifier, an input reference voltage, and an output sampling voltage; The input reference voltage is output through the common terminal of the dual relay. The feedback circuit also includes a 21st resistor and a 5th capacitor. One end of the 21st resistor is connected between the 8th and 9th resistors, and the other end is connected to the non-inverting input terminal of the 3rd operational amplifier. The 5th capacitor is connected in parallel with the 9th resistor. The negative power supply terminal of the third operational amplifier is connected between the Zener diode and the fifth series circuit. The anode of the Zener diode is connected to the -15V power supply, and the cathode of the Zener diode is connected to the negative power supply terminal of the third operational amplifier. The positive power supply terminal of the third operational amplifier is connected to the +15V power supply; The third operational amplifier also includes a twenty-second resistor. One end of the twenty-second resistor is connected to the inverting input terminal of the first operational amplifier, and the other end is connected to the inverting input terminal of the third operational amplifier. The output sampling voltage is fed back from the output terminal of the first operational amplifier to the inverting input terminal of the third operational amplifier through the twenty-second resistor. The feedback circuit also includes the twenty-third resistor and the seventh capacitor, which are connected in series to form the eighth series circuit. One end of the eighth series circuit is connected to the inverting input of the third operational amplifier, and the other end is connected to the output of the third operational amplifier; The linear adjustment series voltage regulator circuit also includes the twenty-third resistor and the twenty-second resistor; The linear adjustment circuit includes an adjustment transistor, a current-limiting sampling resistor, a second transistor, and a twenty-fourth resistor; One end of the 22nd resistor is connected to the common output terminal of the second relay of the dual-channel relay, and the other end of the 22nd resistor is connected to the gate of the regulating transistor; the drain of the regulating transistor is connected to VDC, and the anode and cathode of the Zener diode are connected to the source stage and the gate of the regulating transistor, respectively. The source of the regulating transistor and the base of the second transistor are both connected to one end of the current-limiting sampling resistor; the emitter of the second transistor is connected to the other end of the current-limiting sampling resistor, and the collector of the second transistor is connected to the gate of the regulating transistor VM1. The maximum output current of the regulating transistor VM1 is limited to approximately 0.7V / R, where R is the resistance value of the current-limiting sampling resistor; One end of the 24th resistor is connected to the gate of the regulating transistor, and the other end is connected to the source of the regulating transistor through a current-limiting sampling resistor. The emitter of the 2nd transistor is connected to OUT+. One end of the twenty-third resistor is connected to the normally open contact of the second relay of the dual-channel relay, and the other end is connected to the output of the third operational amplifier. The output filter circuit includes three sets of RC filter series circuits. The RC filter series circuit includes the twenty-fourth resistor and the twenty-fifth resistor. The twenty-fourth resistor and the twenty-fifth resistor are connected in series to form the ninth series circuit. The sixth filter capacitor is connected in parallel on the ninth series circuit. The sixth filter capacitors are connected in series to form the tenth series circuit. The positive terminal of the tenth series circuit is connected to OUT+ and the negative terminal is connected to OUT-. The linear adjustment series voltage regulator circuit also includes an output port of an adjustable reference source of 0-1000V. The high voltage output positive terminal of the output port is connected to OUT+, and the reference ground terminal is connected to OUT-. The output filtering circuit also includes a first common-mode filter capacitor and a second common-mode filter capacitor. The first common-mode filter capacitor and the second common-mode filter capacitor are connected in series to form an eleventh series circuit. EARTH is connected between the first common-mode filter capacitor and the second common-mode filter capacitor. The positive terminal of the eleventh series circuit is connected to OUT+, the negative terminal is connected to OUT-, and OUT- is connected to GND.

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