High-voltage precise adjustable analog linear direct-current stabilized power supply

Abstract

The invention provides a high-voltage precise adjustable analog linear direct-current stabilized power supply, which comprises a signal processing unit, a rectifying and filtering unit, a control unit and a voltage stabilizing unit, and is characterized in that the signal processing unit is used for performing voltage amplification on received external signals and outputting the external signals to the control unit; the rectifying and filtering unit is used for rectifying and filtering input alternating current to obtain direct current and supplying power to the control unit; the control unit is used for sampling the output voltage of the power supply and adjusting the output voltage based on a sampling signal and an external signal so as to control the output value of the voltage stabilizing unit; and the voltage stabilizing unit is used for carrying out step-by-step current amplification based on the received output voltage so as to adjust the output voltage of the voltage stabilizing unit, filtering the output voltage and finally outputting the output voltage. According to the invention, the problems of high procurement and maintenance cost of the existing foreign imported linear adjustable power supply and large ripple, poor stability, obvious voltage drift and limited voltage regulation range of the common linear voltage-stabilizing direct-current power supply and the switching power supply in the market are solved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of direct current stabilized power supply, in particular to a high-voltage precision adjustable analog linear direct current stabilized power supply. BACKGROUND

[0002] In the instrument industry, the pressure transmitter is a very key product. In order to ensure the high performance and high quality of the pressure transmitter, a clean and smooth direct current with high stability, high reliability, precision voltage stabilization and extremely low ripple coefficient needs to be provided for power supply. Since the power supply range of the pressure transmitter is in the DC 10.5V-42V interval, under this power supply condition, the factory needs to accurately calibrate the pressure transmitter to meet the test accuracy and various experimental requirements in the manufacturing process.

[0003] At present, the power supply of the pressure transmitter has the following problems: (1) some factories use imported linear adjustable power supply for power supply of the pressure transmitter, which has high procurement and maintenance cost, thereby increasing the production cost of the factory; (2) the common linear stabilized direct current power supply on the market has large ripple and is unstable, and in the long-term use process, the voltage drift phenomenon is serious, and the adjustable range is narrow, which cannot well meet the power supply demand in the manufacturing process of the pressure transmitter; (3) although the switching power supply is also a power supply selection, the ripple is extremely large and the voltage cannot be adjusted in a large range, which is not suitable for application in the production and manufacturing process of the pressure transmitter. SUMMARY

[0004] In view of the deficiencies in the prior art, the present application provides a high-voltage precision adjustable analog linear direct current stabilized power supply, which solves the problems of high procurement and maintenance cost of imported linear adjustable power supply in the prior art, large ripple, instability, serious voltage drift and narrow adjustable range of common linear stabilized direct current power supply on the market, and large ripple and inability to adjust voltage in a large range of switching power supply.

[0005] According to an embodiment of the present application, a high-voltage precision adjustable analog linear direct current stabilized power supply comprises a signal processing unit, a rectifier filter unit, a control unit and a voltage stabilization unit, wherein: The signal processing unit is configured to receive external signal input, perform voltage amplification based on the received external signal, and output to the control unit; The rectifier filter unit is configured to rectify and filter the input alternating current to obtain direct current for power supply to the control unit; The control unit comprises a sampling circuit and a first operational amplifier, the sampling circuit is used for sampling the power output voltage and outputting a sampling signal to the first operational amplifier; the first operational amplifier is used for receiving the sampling signal and the amplified external signal, and adjusting the output voltage thereof based on the received sampling signal and external signal, so as to control the output value of the voltage stabilizing unit; The voltage stabilizing unit comprises an adjusting circuit and a first filter circuit, the adjusting circuit is used for receiving the output voltage of the first operational amplifier, and performing step-by-step amplification of the current based on the received output voltage, so as to adjust the final output voltage thereof; and the first filter circuit is used for filtering the output voltage of the adjusting circuit and outputting.

[0006] Compared with the prior art, the present application has the following beneficial effects: The input alternating current is rectified and filtered by the rectification and filtering unit, so as to obtain the direct current required for powering the control unit. After the control unit is powered on, the sampling circuit of the control unit samples the power output voltage and outputs a sampling signal to the first operational amplifier, and the signal processing unit amplifies the received external signal and outputs it to the first operational amplifier, so that the first operational amplifier adjusts its own output voltage based on the received sampling signal and the amplified external signal. Then, the adjusting circuit of the voltage stabilizing unit performs step-by-step amplification of the current based on the output voltage of the first operational amplifier, so as to adjust the final output voltage thereof. The output voltage is filtered by the first filter circuit, so that the power supply can provide clean and smooth direct current power supply for the transmitter, and the power supply range is 0-90V, so as to meet the production and manufacturing requirements of the transmitter and high-precision electrical experiments. The problems of high procurement and maintenance costs of existing imported linear adjustable power supplies, large ripple, poor stability, obvious voltage drift and limited voltage regulation range of common linear voltage stabilizing direct current power supplies and switching power supplies on the market are solved. The power supply procurement and maintenance costs can be reduced, and the output voltage ripple is small and stable, the voltage drift is low, and the adjustable range is wide. BRIEF DESCRIPTION OF DRAWINGS

[0007] Figure 1 It is a control principle diagram of a high-voltage precision adjustable analog linear direct current voltage stabilizing power supply.

[0008] Figure 2 It is a circuit schematic diagram of a high-voltage precision adjustable analog linear direct current voltage stabilizing power supply.

[0009] Figure 3 It is a control principle diagram of a high-voltage precision adjustable analog linear direct current voltage stabilizing power supply.

[0010] Figure 4A circuit schematic diagram of a high-voltage precision adjustable analog linear DC voltage stabilizing power supply for another embodiment of the present application.

[0011] Figure 5 A circuit schematic diagram of a terminal external element for another embodiment of the present application. DETAILED DESCRIPTION

[0012] The technical solutions in the present application are further described below in combination with the drawings and embodiments.

[0013] Embodiment one As shown in Figure 1 and Figure 2 OPA454 operational amplifier in the Figure 2 , the first pin of the first operational amplifier and the second operational amplifier is an enable / disable common terminal, the second pin is an inverting input terminal, the third pin is a non-inverting input terminal, the fourth pin is a negative power supply terminal, the sixth pin is an output terminal, the seventh pin is a positive power supply terminal, and the eighth pin is an enable / disable control terminal, the present embodiment proposes a high-voltage precision adjustable analog linear DC voltage stabilizing power supply, comprising a signal processing unit, a rectification filtering unit, a control unit and a voltage stabilizing unit, wherein: The signal processing unit is configured to receive external signal input, perform voltage amplification based on the received external signal, and output to the control unit; The rectification filtering unit is configured to rectify and filter the input alternating current to obtain direct current to supply power to the control unit; The control unit comprises a sampling circuit and a first operational amplifier, the sampling circuit is configured to sample the power output voltage and output a sampling signal to the first operational amplifier; the first operational amplifier is configured to receive the sampling signal and the amplified external signal, and adjust its own output voltage based on the received sampling signal and external signal to control the output value of the voltage stabilizing unit; The voltage stabilizing unit comprises an adjustment circuit and a first filtering circuit, the adjustment circuit is configured to receive the output voltage of the first operational amplifier, and perform step-by-step amplification of the current based on the received output voltage to adjust its own final output voltage; the first filtering circuit is configured to filter and output the output voltage of the adjustment circuit.

[0014] Specifically, the first operational amplifier is preferably a Texas Instruments OPA454 operational amplifier (also can use Analog Devices ADHV4702-1 operational amplifier, supply voltage 220V, the operational amplifier can also be done 0-90V adjustable, but the ADHV4702-1 price is about 65 yuan, and the price of OPA454 is about 2 yuan, in order to reduce the cost, it is recommended to choose OPA454), from the Texas Instruments OPA454 operational amplifier introduction, single power supply DC 100V, and the minimum output is 2.5V when single power supply, there is a dead zone below 2.5V which cannot be adjusted, four diodes are connected in series at the back end of the operational amplifier output pin (6 pin), which can meet the highest DC 0-100V voltage output, but considering the limit ripple, so the maximum output is controlled at 90V, therefore, the output voltage of the operational amplifier can be linearly regulated from 2.5V to 90V (without affecting the linearity).

[0015] But considering that the output current of OPA454 is too large and easy to heat and drift, which leads to unstable system, according to the output ripple voltage calculation formula: wherein, represents the ripple voltage, represents the load current, represents the capacitance value, represents the time, represents the resistance value, represents the base of natural logarithm. From the above calculation formula, the larger the load, the larger the power supply ripple voltage value, which is a great test for the transmitter test experiment, therefore, in order to reduce the output ripple value, the output current needs to be expanded, that is, the rated maximum continuous output current is designed to be 1A, and the DC 2.5-80V is linearly adjustable. The power supply is used within 100mA, and the ripple voltage is very low when the load working current is 20mA, which provides clean and smooth DC power for the transmitter to meet the production and manufacturing requirements of the transmitter and high-precision electrical experiments.

[0016] In the embodiment, the input AC power is rectified and filtered by the rectification filter unit to obtain DC power required by the control unit. After the control unit is powered on, the sampling circuit of the control unit samples the power output voltage, converts the power output voltage into a sampling signal proportional to the output voltage, and outputs the sampling signal to the first operational amplifier. The signal processing unit amplifies the received external signal and outputs the amplified signal to the first operational amplifier. The first operational amplifier compares the received sampling signal and the external input signal, and adjusts the output voltage according to the comparison result. Then, the adjustment circuit of the voltage stabilizing unit amplifies the current in stages based on the output voltage of the first operational amplifier. The first filter circuit filters the output voltage to convert the pulsating DC into smooth DC, so that the power supply can provide clean and smooth DC power to the transmitter, and the power supply range is 0-90V to meet the production and manufacturing requirements of the transmitter and high-precision electrical experiments. At the same time, the change of the filtered output voltage is fed back to the first operational amplifier through the sampling circuit to form a negative feedback loop, so as to adjust the final output voltage of the adjustment circuit, achieve the purpose of voltage stabilization, and minimize the output ripple.

[0017] Preferably, the signal processing unit comprises a terminal U13 and a second operational amplifier U16. The first pin of the terminal U13 is connected to the third pin of the second operational amplifier U16 through a resistor R9, and the second pin of the terminal U13 is grounded. One end of the resistor R9 away from the terminal U13 is connected to one end of a resistor R10, and the other end of the resistor R10 is grounded, and a capacitor C14 is connected in parallel with the resistor R10. The second pin of the second operational amplifier U16 is grounded through a resistor R17, the sixth pin of the second operational amplifier U16 is connected to the third pin of the first operational amplifier U15 through a resistor R14, the sixth pin of the second operational amplifier U16 is sequentially grounded through resistors R15, R16 and R17, and the center tap of the resistor R16 is connected to one end of the resistor R16 close to the resistor R15. One end of the resistor R14 away from the second operational amplifier U16 is connected to one end of a resistor R13, the other end of the resistor R13 is grounded, and a capacitor C15 is connected in parallel with the resistor R13. The fourth pin of the second operational amplifier U16 is grounded, the seventh pin of the second operational amplifier U16 is connected to the seventh pin of the first operational amplifier U15, the first pin and the eighth pin of the second operational amplifier U16 are connected through a capacitor C32, and the first pin of the second operational amplifier U16 is grounded.

[0018] Specifically, as Figure 2As shown, the external signal input from the terminal U13 is transmitted to the non-inverting input terminal of the second operational amplifier U16 through the RC circuit composed of the resistor R9, the resistor R10 and the capacitor C14. In the transmission process, the resistor R9 can limit the current input from the terminal U13 to the inverting input terminal of the second operational amplifier U16, so as to prevent the excessive current from damaging the second operational amplifier U16. The RC circuit composed of the resistor R10 and the capacitor C14 can filter the input signal, so as to make the signal input to the non-inverting input terminal of the second operational amplifier U16 more stable.

[0019] After the second operational amplifier U16 receives the external signal, the second operational amplifier U16 can amplify the received external signal. At this time, the amplification multiple of the second operational amplifier U16 can be adjusted by adjusting the resistance value of the resistor R16. After amplification, the voltage-amplified signal is transmitted to the non-inverting input terminal of the first operational amplifier U15 through the RC circuit composed of the resistor R14, the resistor R13 and the capacitor C15. In the transmission process, the resistor R14 can limit the current input from the second operational amplifier U16 to the first operational amplifier U15, so as to prevent the excessive current from damaging the first operational amplifier U15. The RC circuit composed of the resistor R13 and the capacitor C15 can filter the signal input to the first operational amplifier U15, so as to make the signal input to the non-inverting input terminal of the first operational amplifier U15 more stable.

[0020] Preferably, the rectifying and filtering unit comprises a rectifying circuit and a second filtering circuit, wherein: The rectifying circuit comprises a terminal U8, diodes D1, D2, D3 and D4. The terminal U8 is connected to the secondary main winding of a transformer to input alternating current. The positive electrode of the diode D1 is connected to the first pin of the terminal U8 and the negative electrode of the diode D4. The negative electrode of the diode D1 is connected to the negative electrode of the diode D2. The positive electrode of the diode D2 is connected to the second pin of the terminal U8 and the negative electrode of the diode D3. The positive electrode of the diode D3 is connected to the positive electrode of the diode D4, and the positive electrode of the diode D4 is grounded. The second filtering circuit comprises capacitors C1 and C2. One end of the capacitor C1 is connected to the negative electrode of the diode D1, and the other end of the capacitor C1 is grounded. The capacitor C2 is connected in parallel with the capacitor C1.

[0021] Specifically, the diodes D1, D2, D3 and D4 constitute a full-wave bridge rectifier circuit, the capacitors C1 and C2 constitute a capacitor filter circuit, the AC input of the transformer is introduced into the full-wave bridge rectifier circuit constituted by the diodes D1, D2, D3 and D4 through the terminal U8, the input AC is converted into pulsating DC through the full-wave bridge rectifier circuit constituted by the diodes D1, D2, D3 and D4, and then the voltage fluctuation is smoothed through the capacitor filter circuit constituted by the capacitors C1 and C2, finally the stable DC is output, and the main input power supply of the power supply circuit and the power supply of the first operational amplifier U15 are provided.

[0022] Preferably, the sampling circuit comprises resistors R11 and R12, one end of the resistor R11 is connected with the output voltage of the power supply, the other end of the resistor R11 is connected with one end of the resistor R12 and the second pin of the first operational amplifier U15, and the other end of the resistor R12 is grounded; the second pin of the first operational amplifier U15 is connected with the sixth pin of the first operational amplifier U15 through an RC circuit, the RC circuit is a parallel connection of the resistor R21 and the capacitor C36; the sixth pin of the first operational amplifier U15 is grounded through the resistor R8, the fourth pin of the first operational amplifier U15 is grounded, the first pin and the eighth pin of the first operational amplifier U15 are connected through the capacitor C33, and the first pin of the first operational amplifier U15 is grounded.

[0023] The adjusting circuit comprises at least two transistors; the at least two transistors comprise transistors Q1 and Q2, the base of the transistor Q1 is connected with the sixth pin of the first operational amplifier U15 through the resistor R7, the collector of the transistor Q1 is connected with the seventh pin of the first operational amplifier U15 and the negative electrode of the diode D1, and the emitter of the transistor Q1 is connected with the base of the transistor Q2; the collector of the transistor Q2 is connected with the collector of the transistor Q1, and the emitter of the transistor Q2 outputs the adjusted voltage.

[0024] Specifically, the resistors R11 and R12 form a voltage divider network, the output voltage of the power supply is divided by the voltage divider network formed by the resistors R11 and R12, a sampling voltage proportional to the output voltage of the power supply is obtained by the voltage division, after the voltage division, the voltage value after the voltage division is sent to the inverting input terminal of the first operational amplifier U15, and the voltage value after the voltage amplification of the second operational amplifier U16 is sent to the non-inverting input terminal of the first operational amplifier U15, so that the first operational amplifier U15 can quickly and linearly calculate the two voltage values, and adjust the output voltage of the first operational amplifier U15 according to the operation and comparison result, and then the output terminal of the first operational amplifier U15 outputs a drive signal to drive the transistor Q1 (the model of the transistor Q1 is preferably 2N5551), when the output voltage of the first operational amplifier U15 is output, the integration circuit formed by the capacitor C36 and the resistor R21 can eliminate self-oscillation, so that the output of the first operational amplifier U15 is smoother, and the resistor R7 can limit the current output from the first operational amplifier U15, so as to prevent excessive current from damaging the transistor Q1 and the transistor Q2.

[0025] After the transistor Q1 is driven, the base-emitter of the transistor Q1 is turned on, causing the emitter voltage of the transistor Q1 to be pulled up (close to the base voltage minus about 0.7V voltage drop), since the emitter of the transistor Q1 is directly connected to the base of the transistor Q2, the base voltage of the transistor Q2 is also raised synchronously, prompting the transistor Q2 to also enter the on state, when the transistor Q2 is turned on, the emitter output voltage of the transistor Q2 (i.e. the adjusted voltage) will be close to the base voltage of the transistor Q2 minus 0.7V, since the base voltage of the transistor Q2 is determined by the emitter of the transistor Q1, the final output voltage of the transistor Q2 is clamped at the seventh pin voltage of the first operational amplifier U15 minus 1.4V (considering the double voltage drop of Q1 and Q2), so that the output voltage of the transistor Q2 can be adjusted according to the output voltage of the first operational amplifier U15, achieving the purpose of stabilizing the voltage.

[0026] Preferably, the first filter circuit includes capacitors U1, U2, U23, C6 and C9, one end of the capacitors U1, U23 and C6 is connected to the emitter of the transistor Q2, the other end of the capacitor U1 is connected to one end of the capacitor U2, the other end of the capacitor C6 is connected to one end of the capacitor C9, and the other ends of the capacitors U2, U23 and C9 are grounded.

[0027] Specifically, the capacitors U1, U2, U23, C6 and C9 constitute a capacitor filter circuit, the emitter of the transistor Q2 is the input of the capacitor filter circuit, the voltage output by the emitter of the transistor Q2 is smoothed by the energy storage and charge-discharge characteristics of the capacitors in the capacitor filter circuit constituted by the capacitors U1, U2, U23, C6 and C9, high-frequency noise or ripple is filtered out, and thus a more stable DC voltage is output as the power output voltage.

[0028] The detailed working process of the embodiment is as follows: The connection terminal U8 is connected to the secondary main winding of the transformer, AC power input from the secondary main winding of the transformer is introduced into the full-wave bridge rectifier circuit constituted by the diodes D1, D2, D3 and D4 through the connection terminal U8, the input AC power is converted into pulsating DC power through the full-wave bridge rectifier circuit constituted by the diodes D1, D2, D3 and D4, and then the voltage fluctuation is smoothed through the capacitor filter circuit constituted by the capacitors C1 and C2, finally, stable DC power is output, which provides the main input power supply of the power supply circuit and the power supply of the first operational amplifier U15.

[0029] Then, the power output voltage is divided by the voltage dividing network constituted by the resistors R11 and R12 to obtain a sampling voltage proportional to the power output voltage, after voltage division, the divided voltage value is sent to the inverting input terminal of the first operational amplifier U15, at the same time, the second operational amplifier U16 receives external signals and amplifies the received external signals, and after amplification, the amplified signals are input to the non-inverting input terminal of the first operational amplifier U15 after being filtered by the RC circuit constituted by the resistor R13 and the capacitor C15, at this time, the potentiometer connected to the connection terminal U13 is not adjusted and is in a fixed state, so that the non-inverting input terminal of the first operational amplifier U15 serves as a stable adjustable reference voltage value, so that the first operational amplifier U15 can quickly and linearly calculate two voltage values, and adjust its output voltage according to the calculation and comparison result.

[0030] Then, the output end of the first operational amplifier U15 drives the transistor Q1, after the transistor Q1 is driven, the base-emitter of the transistor Q1 is turned on, causing the emitter voltage of the transistor Q1 to be pulled up, since the emitter of the transistor Q1 is directly connected to the base of the transistor Q2, the base voltage of the transistor Q2 is also raised, prompting the transistor Q2 to also enter the on state, when the transistor Q2 is turned on, the emitter output voltage of the transistor Q2 (i.e. the adjusted voltage) will be close to the base voltage of the transistor Q2 minus 0.7V, since the base voltage of the transistor Q2 is determined by the emitter of the transistor Q1, and the emitter of the transistor Q1 is controlled by the base voltage of the transistor Q1, and the base voltage of the transistor Q1 is determined by the output voltage of the first operational amplifier U15, causing the final output voltage of the transistor Q2 to be adjustable by the output voltage of the first operational amplifier U15.

[0031] Finally, through the energy storage and charge-discharge characteristics of the capacitors in the capacitor filter circuit composed of the capacitors U1, U2, U23, C6 and C9, the voltage output by the emitter of the transistor Q2 is smoothed, high-frequency noise or ripple is filtered out, and a more stable DC voltage is output as the power output voltage, so that the power supply can provide clean and smooth DC power to the transmitter, with a power supply range of 0-90V, to meet the production and manufacturing requirements of the transmitter and high-precision electrical experiments, at the same time, the filtered output voltage change is fed back to the first operational amplifier U15, forming a negative feedback loop, to adjust the output voltage of the transistor Q2 according to the output voltage of the first operational amplifier U15, achieving the purpose of voltage stabilization and minimizing output ripple.

[0032] Embodiment Two As shown in Figures 3-5 the first pin of the LM358 operational amplifier in Figure 4 is the output end, the second pin is the inverting input end, the third pin is the non-inverting input end, the fourth pin is the negative power supply end, and the eighth pin is the positive power supply end), according to another embodiment of the present application, the high-voltage precision adjustable analog linear DC voltage stabilizing power supply further comprises an overcurrent protection unit, a low-temperature drift precision voltage stabilizing unit and a power supply unit, wherein: The overcurrent protection unit is used to cut off the output of the adjustment circuit when the power output is short-circuited or overloaded, to realize overcurrent or short-circuit protection; The low-temperature drift precision voltage stabilizing unit is used to provide a high-precision, low-temperature drift stable reference voltage output for the signal processing unit, and manually adjust the output voltage based on actual needs; The power supply unit is used to rectify, filter and stabilize the input AC power, and supply power to the overcurrent protection unit and the low-temperature drift precision voltage stabilizing unit.

[0033] Specifically, the power supply unit rectifies, filters and stabilizes the input alternating current to obtain 15V direct current, and simultaneously provides the overcurrent protection unit and the low-temperature drift precision voltage stabilizing unit, so as to provide driving power for the overcurrent protection unit and auxiliary power for the low-temperature drift precision voltage stabilizing unit; the overcurrent protection unit monitors the current of the power supply output end in real time, and automatically triggers the protection circuit when detecting a short-circuit fault or an overload state (the current exceeds a threshold value), at this time, the output path of the adjustment circuit is quickly disconnected to block the propagation of the fault current, so as to prevent the equipment from being damaged due to overcurrent or short circuit, and realize overcurrent or short circuit protection; the low-temperature drift precision voltage stabilizing unit adopts a potentiometer to manually adjust the output voltage, so as to realize adjustable output of the voltage.

[0034] Preferably, the overcurrent protection unit comprises a terminal U10 and a third operational amplifier U6. The first pin of the terminal U10 is connected to the third pin of the third operational amplifier U6 through a resistor R3, and the first pin of the terminal U10 is grounded through a resistor U14; the second pin of the terminal U10 is connected to the output voltage of the power supply; one end of a capacitor C10 is connected to the end of the resistor R3 away from the resistor U14, and the other end of the capacitor C10 is grounded. The second pin of the third operational amplifier U6 is grounded through a resistor R2, the center tap of the resistor R2 is grounded, a capacitor C12 is connected to the resistor R2 in parallel, and the second pin of the third operational amplifier U6 is connected to the eighth pin of the third operational amplifier U6 through a resistor R1; the fourth pin of the third operational amplifier U6 is grounded, the first pin of the third operational amplifier U6 is connected to the third pin of the third operational amplifier U6 through a resistor R4, and the first pin of the third operational amplifier U6 is connected to the base of a triode Q3 through a resistor R6; the collector of the triode Q3 is connected to the negative electrode of a diode D9, the positive electrode of the diode D9 is connected to the base of the triode Q1, and the emitter of the triode Q3 is grounded.

[0035] Specifically, the first pin and the second pin of the terminal U10 are connected with a load, and the second pin of the terminal U10 is connected with a power output voltage. The resistor U14 converts the load current introduced by the terminal U10 into a voltage signal, and samples the voltage signal and the power output voltage. The sampled voltage signal is sent to a filter circuit composed of the resistor R3 and the capacitor C10, and is output to the non-inverting input terminal of the third operational amplifier U6 after filtering and voltage division. The resistor R2 and the capacitor C12 together constitute a filter circuit, and provide a stable reference voltage (the reference voltage can be adjusted by adjusting the center tap of the resistor R2) for the inverting input terminal of the third operational amplifier U6. The third operational amplifier U6 (the third operational amplifier U6 is a voltage comparator, and the model is preferably LM358) compares the sampled voltage and the reference voltage, and determines whether the power output is short-circuited or overloaded according to the comparison result (in the normal working state, the voltage of the non-inverting input terminal of the third operational amplifier U6 is lower than the reference voltage of the inverting input terminal; in the short-circuit or overload state, the voltage of the non-inverting input terminal of the third operational amplifier U6 is higher than the reference voltage of the inverting input terminal). If the power output is short-circuited or overloaded, the output terminal of the third operational amplifier U6 outputs a signal to drive the triode Q3 to turn on, so that the diode D9 is turned on instantaneously, the base voltage of the triode Q1 is clamped, and the triode Q1 and the triode Q2 are cut off to have no output, thereby playing a role of overcurrent or short-circuit protection for the power output terminal.

[0036] In addition, an insurance tube or a relay can be connected outside the terminal U10 to perform multiple interlocking protection. When the insurance tube is connected outside the terminal U10, if the power output is short-circuited or overloaded, the insurance tube is fused to cut off the power output. When the relay is connected outside the terminal U10, if the power output is short-circuited or overloaded, the relay is disconnected to cut off the power output.

[0037] Preferably, the overcurrent protection unit further comprises a terminal U11, the first pin and the second pin of the terminal U11 are connected with both ends of the resistor R5, and the capacitor C13 is connected in parallel with the resistor R5; the first pin of the terminal U11 is connected with the ground, and the second pin of the terminal U11 is connected with the non-inverting input terminal of the third operational amplifier U6.

[0038] Specifically, the first pin and the second pin of the terminal U11 are connected with an external reset switch. When the load returns to normal, the reset switch is manually pressed. At this time, the first pin and the second pin of the terminal U11 are turned on through the external reset switch to provide a reset signal to the circuit. After detecting the reset signal, the protection lock state in the circuit is released. The triode Q1 and the triode Q2, which are originally in the off state due to overcurrent protection, are turned on again according to the normal working condition to restore the normal power supply to the load. At the same time, the comparison state of the third operational amplifier U6 also returns to the normal working state to compare the sampling voltage and the reference voltage again to continuously monitor whether the overcurrent or short circuit condition occurs again.

[0039] Preferably, the low-temperature drift precision voltage stabilizing unit comprises a terminal U17 and a three-terminal adjustable reference source U18. The first pin of the terminal U17 is connected with the third pin of the three-terminal adjustable reference source U18 and one end of a capacitor C34, respectively. The other end of the capacitor C34 is grounded. A capacitor C35 is connected with the capacitor C34 in parallel. The second pin of the terminal U17 is grounded. The first pin and the second pin of the three-terminal adjustable reference source U18 are connected with both ends of a resistor R20, respectively. The center tap of the resistor R20 is connected with the first pin of the three-terminal adjustable reference source U18. A capacitor C30 is connected with the resistor R20 in parallel. The first pin of the three-terminal adjustable reference source U18 is connected with the third pin of the three-terminal adjustable reference source U18 through a resistor R19. The third pin of the three-terminal adjustable reference source U18 is connected with the eighth pin of the third operational amplifier U6 through a resistor R18.

[0040] Specifically, the first pin of the terminal U17 is connected to one end of an external precision potentiometer as a manual reference voltage output terminal, the other end of the external precision potentiometer is connected to the second pin of the terminal U13, and the adjusting end of the external precision potentiometer is connected to the first pin of the terminal U13 (it is worth noting that the first pin of the terminal U13 can be connected to an external D / A output control signal to directly control the terminal U13 through the D / A output of the PLC to realize the automatic control function; the first pin of the terminal U13 can also be connected to a potentiometer to realize the manual control function by manually adjusting the potentiometer). Taking the manual adjustment of the potentiometer as an example, the two ends of the potentiometer are respectively connected to the terminals U17 and U13 to provide a precise and stable voltage for the potentiometer, and the center tap of the potentiometer is connected to the first pin of the terminal U13. When the power is turned on, the potentiometer is adjusted, the voltage of the first pin of the terminal U13 is increased, which is sent to the third pin of the second operational amplifier U16, so that the voltage of the sixth pin of the second operational amplifier U16 is increased and sent to the third pin of the first operational amplifier U15, so that the voltage of the sixth pin of the first operational amplifier U15 is increased and sent to the base of the transistor Q1. Since the transistor Q1 and the transistor Q2 form a series composite transistor, the voltage output of the emitter of the transistor Q2 is increased, and the second pin of the terminal U10 connected to the resistor U14 to the ground forms a loop through the external load of the terminal U10.

[0041] The power supply is input to the three-terminal adjustable reference source U18 through the resistor R18 and the resistor R19. The resistor R18 is a current-limiting resistor that limits the current flowing into the three-terminal adjustable reference source U18. The resistor R19 and the resistor R20 together constitute a voltage dividing circuit. By adjusting the ratio of the resistor R19 and the resistor R20, the reference voltage input to the input terminal of the three-terminal adjustable reference source U18 can be changed, so that the output voltage of the three-terminal adjustable reference source U18 can be adjusted. The output voltage fluctuations are filtered out through the cooperation of the capacitor C34 and the capacitor C35, and the power supply ripple is reduced to provide a stable voltage reference source for the second operational amplifier U16. The reference source is transmitted to the terminal U13 through the terminal U17.

[0042] The three-terminal adjustable reference source U18 is preferably a TL431 produced by Texas Instruments. The TL431 adopts a TO-92 package form, and has excellent voltage stabilization characteristics and flexible voltage setting range. According to the calculation formula of the TL431 The calculation formula of the reference source output from the terminal U17 to the terminal U13 is: Since The value is very small, so the above calculation formula can be simplified as: Since the TL431 internally has a 2.495V precision voltage reference source, when the input reference terminal voltage is higher than 2.5V, the TL431 will immediately conduct to output a stabilized voltage, therefore, the TL431 stabilized output value is determined by the voltage division value of R19 and R20, and the output value of the TL431 can be changed by adjusting the resistance ratio of R19 and R20, that is, changing the voltage value of the stabilized voltage reference source input from the terminal U13 to the second operational amplifier U16.

[0043] Preferably, the power supply unit comprises a terminal U9, diodes D5, D6, D7, D8 and a voltage stabilizer U7. The terminal U9 is connected to the secondary winding of the transformer to input alternating current; the anode of the diode D5 is connected to the first pin of the terminal U9 and the cathode of the diode D8, the cathode of the diode D5 is connected to the cathode of the diode D6, the anode of the diode D6 is connected to the second pin of the terminal U9 and the cathode of the diode D7, the anode of the diode D7 is connected to the anode of the diode D8, and the anode of the diode D8 is grounded. The first pin of the voltage stabilizer U7 is connected to the cathode of the diode D5 and one end of the capacitor U3, the other end of the capacitor U3 is grounded, and the capacitor C7 is connected in parallel with the capacitor U3; the second pin of the voltage stabilizer U7 is grounded; the third pin of the voltage stabilizer U7 is connected to one end of the capacitor C4 and the eighth pin of the third operational amplifier U6, the other end of the capacitor C4 is grounded, and the capacitors C8 and C11 are connected in parallel with the capacitor C4.

[0044] Specifically, the diodes D5, D6, D7 and D8 constitute a full-wave bridge rectifier circuit, the capacitors U3 and C7 and the capacitors C4, C8 and C11 constitute different capacitor filter circuits respectively, the alternating current input from the transformer is introduced into the full-wave bridge rectifier circuit constituted by the diodes D5, D6, D7 and D8 through the terminal U9, the input alternating current is converted into pulsating direct current by the full-wave bridge rectifier circuit constituted by the diodes D5, D6, D7 and D8, and then the voltage fluctuation is smoothed by the capacitor filter circuit constituted by the capacitors U3 and C7, finally, the stable direct current is output to the voltage stabilizer U7, so that the voltage stabilizer U7 performs voltage stabilization processing on the filtered direct current to output a stable direct current voltage, and then the output voltage is further filtered by the capacitors C4, C8 and C11 to remove high-frequency noise, thereby providing a clean and stable power supply for the third operational amplifier U6 and the three-terminal adjustable reference source U18.

[0045] The detailed working process of the embodiment is as follows: The terminal U9 is connected to the secondary winding of the transformer. The AC power input from the secondary winding of the transformer is introduced into the full-wave bridge rectifier circuit composed of diodes D5, D6, D7 and D8 through the terminal U9. The input AC power is converted into pulsating DC power by the full-wave bridge rectifier circuit composed of diodes D5, D6, D7 and D8, and the voltage fluctuation is smoothed by the capacitor filter circuit composed of capacitor U3 and C7. Finally, the stable DC power is output to the voltage stabilizer U7, so that the voltage stabilizer U7 stabilizes the filtered DC power and outputs stable DC voltage. Then, the output voltage is further filtered by capacitors C4, C8 and C11 to remove high-frequency noise, and clean and stable power is provided for the third operational amplifier U6 and the three-terminal adjustable reference source U18.

[0046] After that, the first pin and the second pin of the terminal U10 are connected to the load, and the first pin and the second pin of the terminal U11 are connected to the reset switch. The resistor U14 converts the load current introduced by the terminal U10 into a voltage signal, samples the voltage signal and the power output voltage, and sends the sampled voltage signal to the filter circuit composed of resistor R3 and capacitor C10. After filtering and voltage division, the output is sent to the non-inverting input terminal of the third operational amplifier U6. The third operational amplifier U6 compares the input sampled voltage and the reference voltage, and determines whether the power output is short-circuited or overloaded according to the comparison result. If the power output is short-circuited or overloaded, the output of the third operational amplifier U6 drives the triode Q3 to turn on, so that the diode D9 is momentarily turned on, clamping the base voltage of the triode Q1, and the triode Q1 and the triode Q2 are cut off to have no output, thereby playing a role of overcurrent or short-circuit protection for the power output terminal. When the load returns to normal, the reset switch is manually pressed. At this time, the first pin and the second pin of the terminal U11 are turned on through the external reset switch to provide a reset signal to the circuit. After detecting the reset signal, the protection lock state in the circuit is released. The triode Q1 and the triode Q2, which are in the cut-off state due to overcurrent protection, are turned on again according to the normal working condition to restore the normal power supply to the load. At the same time, the comparison state of the third operational amplifier U6 also returns to the normal working state, and the sampled voltage and the reference voltage are compared again to continuously monitor whether the overcurrent or short-circuit condition occurs again.

[0047] Meanwhile, the first pin of the terminal U17 is connected to one end of an external precision potentiometer as a manual adjustment reference voltage output terminal, the other end of the external precision potentiometer is connected to the second pin of the terminal U13, and the adjustment end of the external precision potentiometer is connected to the first pin of the terminal U13 input. After the power supply is input to the three-terminal adjustable reference source U18 through the resistors R18 and R19, the three-terminal adjustable reference source U18 can generate a stable and adjustable reference voltage based on the input voltage and its own adjustment characteristics, and the reference voltage is then provided to the second operational amplifier U16 as a voltage reference source of the second operational amplifier U16, which provides an accurate voltage reference for the normal operation of the second operational amplifier U16, ensuring that it can perform accurate signal comparison, amplification and other operation operations according to the reference.

[0048] Finally, it should be pointed out that the above embodiments are only used to illustrate the technical solutions of the present application and are not limiting. Although the present application has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present application can be modified or replaced by equivalents without departing from the spirit and scope of the present application, and they should be covered in the scope of the claims of the present application.

Claims

1. A high-voltage precision adjustable analog linear DC regulated power supply, characterized in that, The signal processing unit, the rectification filter unit, the control unit and the voltage stabilizing unit are included, wherein: The signal processing unit is configured to receive external signal input, amplify voltage based on the received external signal, and output to the control unit; The rectification filter unit is configured to rectify and filter the input alternating current to obtain direct current to power the control unit; The control unit includes a sampling circuit and a first operational amplifier, the sampling circuit is configured to sample the power output voltage and output the sampling signal to the first operational amplifier; the first operational amplifier is configured to receive the sampling signal and the amplified external signal, and adjust the output voltage based on the received sampling signal and external signal to control the output value of the voltage stabilizing unit; The voltage stabilizing unit includes an adjustment circuit and a first filter circuit, the adjustment circuit is configured to receive the output voltage of the first operational amplifier, and gradually amplify the current based on the received output voltage to adjust the final output voltage of itself; the first filter circuit is configured to filter and output the output voltage of the adjustment circuit.

2. The high-voltage precision adjustable analog linear DC regulated power supply according to claim 1, characterized in that, The signal processing unit includes a terminal U13 and a second operational amplifier U16; The first pin of the terminal U13 is connected to the third pin of the second operational amplifier U16 through a resistor R9, and the second pin of the terminal U13 is grounded; one end of the resistor R9 away from the terminal U13 is connected to one end of a resistor R10, and the other end of the resistor R10 is grounded, and a capacitor C14 is connected in parallel with the resistor R10; The second pin of the second operational amplifier U16 is grounded through a resistor R17, the sixth pin of the second operational amplifier U16 is connected to the third pin of the first operational amplifier U15 through a resistor R14, the sixth pin of the second operational amplifier U16 is grounded in turn through resistors R15, R16 and R17, and the center tap of the resistor R16 is connected to one end of the resistor R16 close to the resistor R15; one end of the resistor R14 away from the second operational amplifier U16 is connected to one end of a resistor R13, the other end of the resistor R13 is grounded, and a capacitor C15 is connected in parallel with the resistor R13; the fourth pin of the second operational amplifier U16 is grounded, the seventh pin of the second operational amplifier U16 is connected to the seventh pin of the first operational amplifier U15, the first pin and the eighth pin of the second operational amplifier U16 are connected through a capacitor C32, and the first pin of the second operational amplifier U16 is grounded.

3. The high-voltage precision adjustable analog linear DC regulated power supply according to claim 1, characterized in that, The rectification filter unit includes a rectification circuit and a second filter circuit, wherein: The rectifier circuit comprises a terminal U8 connected to a secondary main winding of a transformer to input alternating current, diodes D1, D2, D3 and D4, a positive electrode of the diode D1 is connected to a first pin of the terminal U8 and a negative electrode of the diode D4, a negative electrode of the diode D1 is connected to a negative electrode of the diode D2, a positive electrode of the diode D2 is connected to a second pin of the terminal U8 and a negative electrode of the diode D3, a positive electrode of the diode D3 is connected to a positive electrode of the diode D4, and the positive electrode of the diode D4 is grounded. The second filter circuit comprises capacitors C1 and C2, one end of the capacitor C1 is connected to the negative electrode of the diode D1, the other end of the capacitor C1 is grounded, and the capacitor C2 is connected to the capacitor C1 in parallel.

4. The high-voltage precision adjustable analog linear DC regulated power supply according to claim 1, characterized in that, The sampling circuit comprises resistors R11 and R12, one end of the resistor R11 is connected to an output voltage of a power supply, the other end of the resistor R11 is connected to one end of the resistor R12 and a second pin of the first operational amplifier U15, the other end of the resistor R12 is grounded, the second pin of the first operational amplifier U15 is connected to a sixth pin of the first operational amplifier U15 through an RC circuit, the RC circuit comprises a resistor R21 and a capacitor C36 connected in parallel, the sixth pin of the first operational amplifier U15 is grounded through the resistor R8, a fourth pin of the first operational amplifier U15 is grounded, a first pin and an eighth pin of the first operational amplifier U15 are connected through a capacitor C33, and the first pin of the first operational amplifier U15 is grounded.

5. The high-voltage precision adjustable analog linear DC regulated power supply according to claim 3, characterized in that, The adjusting circuit comprises at least two transistors. The at least two transistors comprise transistors Q1 and Q2, a base of the transistor Q1 is connected to the sixth pin of the first operational amplifier U15 through the resistor R7, a collector of the transistor Q1 is connected to a seventh pin of the first operational amplifier U15 and the negative electrode of the diode D1, an emitter of the transistor Q1 is connected to a base of the transistor Q2, a collector of the transistor Q2 is connected to the collector of the transistor Q1, and an emitter of the transistor Q2 outputs an adjusted voltage.

6. The high-voltage precision adjustable analog linear DC regulated power supply according to claim 5, characterized in that, The first filter circuit comprises capacitors U1, U2, U23, C6 and C9, one end of the capacitors U1, U23 and C6 is connected to the emitter of the transistor Q2, the other end of the capacitor U1 is connected to one end of the capacitor U2, the other end of the capacitor C6 is connected to one end of the capacitor C9, and the other ends of the capacitors U2, U23 and C9 are grounded.

7. The high-voltage precision adjustable analog linear DC regulated power supply according to claim 5, characterized in that, The power supply unit comprises a power supply, a rectifier circuit, a second filter circuit, a sampling circuit, an adjusting circuit, a first filter circuit, a signal processing unit, an overcurrent protection unit, a low-temperature drift precision voltage stabilizing unit and a power supply unit. The overcurrent protection unit is configured to cut off an output of the adjusting circuit when the power supply is short-circuited or overloaded, so as to realize overcurrent or short-circuit protection. The low-temperature drift precision voltage stabilizing unit is configured to provide a high-precision, low-temperature drift stable reference voltage output for the signal processing unit, and manually adjust the output voltage based on actual needs. The power supply unit rectifies, filters and stabilizes the input AC power to supply power to the over-current protection unit and the low-temperature drift precision voltage stabilizing unit.

8. The high-voltage precision adjustable analog linear DC regulated power supply according to claim 7, characterized in that, The over-current protection unit comprises a terminal U10 and a third operational amplifier U6. The first pin of the terminal U10 is connected to the third pin of the third operational amplifier U6 through a resistor R3, and the first pin of the terminal U10 is grounded through a resistor U14; the second pin of the terminal U10 is connected to the output voltage of the power supply; one end of a capacitor C10 is connected to the resistor R3 away from the resistor U14, and the other end of the capacitor C10 is grounded. The second pin of the third operational amplifier U6 is grounded through a resistor R2, the center tap of the resistor R2 is grounded, a capacitor C12 is connected in parallel with the resistor R2, and the second pin of the third operational amplifier U6 is connected to the eighth pin of the third operational amplifier U6 through a resistor R1; the fourth pin of the third operational amplifier U6 is grounded, the first pin of the third operational amplifier U6 is connected to the third pin of the third operational amplifier U6 through a resistor R4, and the first pin of the third operational amplifier U6 is connected to the base of a transistor Q3 through a resistor R6; the collector of the transistor Q3 is connected to the negative electrode of a diode D9, the positive electrode of the diode D9 is connected to the base of the transistor Q1, and the emitter of the transistor Q3 is grounded.

9. The high-voltage precision adjustable analog linear DC regulated power supply according to claim 8, characterized in that, The low-temperature drift precision voltage stabilizing unit comprises a terminal U17 and a three-terminal adjustable reference source U18. The first pin of the terminal U17 is connected to the third pin of the three-terminal adjustable reference source U18 and one end of a capacitor C34, respectively, and the other end of the capacitor C34 is grounded; a capacitor C35 is connected in parallel with the capacitor C34, and the second pin of the terminal U17 is grounded. The first pin and the second pin of the three-terminal adjustable reference source U18 are connected to the two ends of a resistor R20, respectively, and the center tap of the resistor R20 is connected to the first pin of the three-terminal adjustable reference source U18; a capacitor C30 is connected in parallel with the resistor R20; the first pin of the three-terminal adjustable reference source U18 is connected to the third pin of the three-terminal adjustable reference source U18 through a resistor R19, and the third pin of the three-terminal adjustable reference source U18 is connected to the eighth pin of the third operational amplifier U6 through a resistor R18.

10. The high-voltage precision adjustable analog linear DC power supply of claim 9, wherein, The power supply unit comprises a terminal U9, diodes D5, D6, D7 and D8, and a voltage stabilizer U7. The terminal U9 is connected to the secondary winding of a transformer to input AC power; the positive electrode of the diode D5 is connected to the first pin of the terminal U9 and the negative electrode of the diode D8, the negative electrode of the diode D5 is connected to the negative electrode of the diode D6, the positive electrode of the diode D6 is connected to the second pin of the terminal U9 and the negative electrode of the diode D7, the positive electrode of the diode D7 is connected to the positive electrode of the diode D8, and the positive electrode of the diode D8 is grounded; The first pin of the stabilizer U7 is connected with the negative pole of the diode D5 and one end of the capacitor U3, the other end of the capacitor U3 is grounded, and the capacitor C7 is connected with the capacitor U3 in parallel; the second pin of the stabilizer U7 is grounded; the third pin of the stabilizer U7 is connected with one end of the capacitor C4 and the eighth pin of the third operational amplifier U6, the other end of the capacitor C4 is grounded, and the capacitors C8 and C11 are connected with the capacitor C4 in parallel.

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