Switching control circuit and method for sampling gain in power supply constant voltage output

Abstract

The invention provides a switching control circuit and a switching control method for sampling gain in constant voltage output of a power supply. The sampling gain switching circuit is used for sampling gain switching; the auxiliary gear-shifting circuit is used for charging a capacitor in the auxiliary gear-shifting circuit, after the capacitor is charged, switches directly connected with the capacitor in the auxiliary gear-shifting circuit are all switched off, the capacitor keeps the voltage when the switches are switched off, and the auxiliary gear-shifting circuit is connected to the loop control circuit; the voltage after capacitor charging is completed is the same as the sampling value of the power supply current at the current moment; the loop control circuit is used for being connected with an auxiliary gear shifting circuit in the constant-current loop circuit after capacitor charging is completed, disconnecting the constant-voltage loop circuit and the loop control circuit, connecting the constant-voltage loop circuit and the loop control circuit after sampling gain switching is completed, disconnecting the constant-current loop circuit and the loop control circuit, and disconnecting the constant-voltage loop circuit and the loop control circuit after sampling gain switching is completed. And the voltage sampling gain is switched in the constant voltage output process of the power supply.

Description

Technical Field

[0001] The present invention relates to the field of power supply control, and in particular to a switching control circuit and a switching control method for sampling gain in a constant voltage output of a power supply. Background Art

[0002] Power supplies with fixed voltage sampling ranges have limited output resolution for a given DA (digital-to-analog converter), resulting in a similarly limited output voltage resolution. This results in poor relative accuracy at smaller output voltages. To improve voltage output accuracy across the entire measuring range, a power supply or instrument with an output function must adjust the voltage sampling gain. Using a higher voltage sampling gain when outputting voltages of a few volts, or even millivolts or microvolts, will improve the power supply's output accuracy. When output voltage accuracy is less demanding, a lower voltage sampling gain can be used to achieve a wide voltage output range of tens or hundreds of volts.

[0003] When the power supply is in the process of constant voltage output, the voltage sampling is fed back for closed-loop control. At this time, if the gain of the voltage sampling circuit is changed, the voltage feedback signal is prone to fluctuation during the switching process, which will cause abnormal output of the power supply.

[0004] Most existing power supplies use fixed voltage sampling gears. Power supplies or instruments that can switch voltage sampling gears can only switch the voltage sampling gain when the power supply is shut down, and cannot switch the voltage sampling gain during the continuous output of the power supply.

[0005] Therefore, the present invention proposes a switching control circuit and a switching control method for sampling gain in a constant voltage output of a power supply, which can realize switching of the voltage sampling gain during the constant voltage output process of the power supply. Summary of the Invention

[0006] In order to solve the problems existing in the prior art, the present invention innovatively proposes a switching control circuit and a switching control method for the sampling gain in the constant voltage output of a power supply, which effectively solves the problem that the voltage sampling gain cannot be switched during the continuous output of the power supply due to the prior art, and effectively realizes the switching of the voltage sampling gain during the constant voltage output of the power supply.

[0007] The first aspect of the present invention provides a switching control circuit for sampling gain in a constant voltage output of a power supply, comprising: a power supply, a loop control circuit, a modulation circuit, a constant current loop circuit, and a constant voltage loop circuit connected in parallel with the constant current loop, wherein the constant current loop circuit comprises a current sampling circuit and an auxiliary shifting circuit connected in series, and the constant voltage loop circuit comprises a voltage sampling circuit and a sampling gain switching circuit connected in series, wherein the first input end of the loop control circuit is connected to the output end of the constant voltage loop circuit, the second input end of the loop control circuit is connected to the output end of the constant current loop circuit, the input end of the modulation circuit is connected to the output end of the loop control circuit, and the output end of the modulation circuit is connected to the driving input end of the power supply; the voltage sampling circuit is used to perform voltage sampling on the power supply output end of the power supply and output the sampled first voltage signal to the sampling gain switching circuit; the current sampling circuit is used to perform current sampling on the output end of the power supply and output the sampled second voltage signal to the auxiliary shifting circuit; the auxiliary shifting circuit is used to output the sampled second voltage signal to the second input end of the loop control circuit and output the sampled second voltage signal to the auxiliary shifting circuit in the constant voltage loop circuit. When the auxiliary shift circuit is connected to the loop control circuit, the capacitor C1 in the auxiliary shift circuit is charged. After the capacitor C1 is charged, all switches directly connected to the capacitor C1 in the auxiliary shift circuit are disconnected, the capacitor C1 maintains the voltage at the moment the switch is disconnected, and the auxiliary shift circuit is connected to the loop control circuit; wherein, the voltage of the capacitor C1 when charging is completed is the same as the sampled value of the power supply current at the current moment, and the voltage output by the auxiliary shift circuit is used as the given input of the loop control circuit; the sampling gain switching circuit is used to output the sampled first voltage signal to the first input end of the loop control circuit, and after the capacitor C1 in the auxiliary shift circuit is charged and disconnected from the loop control circuit, perform sampling gain switching; the loop control circuit is used to connect the auxiliary shift circuit in the constant current loop circuit after the capacitor C1 in the auxiliary shift circuit is charged, disconnect the constant voltage loop circuit from the loop control circuit, and connect the constant voltage loop circuit to the loop control circuit after the sampling gain switching is completed, and disconnect the constant current loop circuit from the loop control circuit.

[0008] Optionally, the voltage sampling circuit includes a resistor R11, a resistor R13, a resistor R14, a resistor R12 and an operational amplifier U1, wherein the non-inverting input terminal of the operational amplifier U1 is connected to the ground through the resistor R12 in one path, and is connected to the high-voltage input terminal of the power supply through the resistor R14 in the other path; the inverting input terminal of the operational amplifier U1 is connected to the low-voltage input terminal of the power supply through the resistor R13 in one path, and is connected to the output terminal of the operational amplifier U1 in the other path, and the output terminal of the operational amplifier is connected to the input terminal of the sampling gain switching circuit.

[0009] Optionally, the sampling gain switching circuit includes an operational amplifier U2, a resistor R10, and multiple parallel sampling gain circuits. The inverting input terminal of the operational amplifier U2 is connected to the output terminal of the voltage sampling circuit through the resistor R10, and is connected to the output terminal of the operational amplifier U2 through a certain sampling gain circuit. The non-inverting input terminal of the operational amplifier U2 is grounded.

[0010] Furthermore, the resistance values ​​of the resistors in each sampling gain circuit are different from each other.

[0011] Optionally, when the constant voltage loop circuit is connected to the loop control circuit, the sum of the given voltage signal VG of the loop control circuit and the first voltage signal VFB fed back by the voltage sampling circuit is 0; after the constant current loop circuit is connected to the loop control circuit, the sum of the output signal Vc of the auxiliary shift circuit and the second voltage signal IFB fed back by the current sampling circuit is 0.

[0012] Optionally, the loop control circuit includes an operational amplifier U4, a resistor R3, a resistor R4, a resistor R5, a resistor R6, a capacitor C2, and a switch K2, one end of the resistor R3 is connected to the output end of the sampling gain switching circuit, the other end of the resistor R3 is connected to one end of the switch K2, the other end of the switch K2 is connected to the resistor R4, the other end of the switch K2 is connected to the non-inverting input end of the operational amplifier U4, one path of the inverting input end of the operational amplifier U4 is grounded through the resistor R5, and the other path is connected to the output end of the operational amplifier U4 through the series-connected resistor R6 and capacitor C1, and the output end of the operational amplifier U4 is connected to the power supply, wherein the resistance value of the resistor R3 is the same as the resistance value of the resistor R4.

[0013] Optionally, the current sampling circuit includes an operational amplifier U5, a resistor R21, a resistor R22, a resistor R23, and a resistor R24. The non-inverting input terminal of the operational amplifier U5 is connected to the ground through the resistor R21 in one path, and is connected to one end of the sampling resistor R1 at the power output end through the resistor R23 in the other path; the inverting input terminal of the operational amplifier U5 is connected to the output terminal of the operational amplifier U5 in one path through the resistor R22, and is connected to the other end of the sampling resistor R1 at the power output end through the resistor R24 ​​in the other path. The output terminal of the operational amplifier U5 is connected to the input terminal of the auxiliary shift circuit.

[0014] Optionally, the auxiliary shift circuit includes an operational amplifier U6, an operational amplifier U3, a capacitor C1, a resistor R15, a resistor R16, a resistor R17, a resistor R18, a resistor R19, a resistor R20, a switch K1, a switch K6, and a switch K7. The non-inverting input terminal of the operational amplifier U6 is grounded, the inverting input terminal of the operational amplifier U6 is connected to the output terminal of the current sampling circuit through the resistor R20, and the other is connected to the output terminal of the operational amplifier U6 through the resistor R19. The output terminal of the operational amplifier U6 is connected to the non-inverting input terminal of the operational amplifier U3 through the series resistor R18 and the switch K7 in turn. The non-inverting input terminal of the operational amplifier U3 is connected to the ground through the capacitor C1, one path is connected to the ground through the series-connected switch K6 and the resistor R7, and the other path is connected to the output terminal of the operational amplifier U6 through the series-connected switch K7 and the resistor R18. The inverting input terminal of the operational amplifier U3 is connected to the output terminal of the operational amplifier U3, the output terminal of the operational amplifier U3 is connected to one end of the switch K1 through the resistor R16, one end of the resistor R15 is connected to the output terminal of the current sampling circuit, the other end of the resistor R15 is connected to one end of the switch K1, and the other end of the switch K1 is electrically connected to the second input terminal of the loop control circuit.

[0015] Furthermore, switch K6 is opened and switch K7 is closed, and capacitor C1 starts to charge; after capacitor C1 is charged, both switches K6 and K7 are opened, and capacitor C1 maintains the voltage at the time when the switches are opened; switch K6 is closed and switch K7 is opened, and capacitor C1 starts to discharge; the resistance value of resistor R19 is equal to the resistance value of resistor R20, and the resistance value of resistor R15 is equal to the resistance value of resistor R16.

[0016] A second aspect of the present invention provides a method for switching control of a sampling gain in a constant voltage output of a power supply, which is implemented based on a switching control circuit for a sampling gain in a constant voltage output of a power supply provided in the first aspect of the present invention, and includes: In the normal power output stage, the connection between the auxiliary shift circuit and the loop control circuit is disconnected, and the connection between the sampling gain switching circuit and the loop control circuit is closed, and the power supply is in constant voltage output; During the capacitor charging phase, the capacitor C1 in the auxiliary shift circuit begins to charge; During the first control loop transition phase, after the capacitor C1 in the auxiliary shift circuit is fully charged, all switches directly connected to the capacitor C1 in the auxiliary shift circuit are disconnected, and the capacitor C1 maintains the voltage at the time the switches are disconnected. The auxiliary shift circuit is then connected to the loop control circuit. The voltage of the capacitor C1 upon completion of charging is the same as the sampled value of the power supply current at the current moment, and the voltage output by the auxiliary shift circuit is used as a given input for the loop control circuit. During the power supply stable output stage, the connection between the sampling gain switching circuit and the loop control circuit is disconnected, and the power supply is controlled by the constant current loop circuit; In the sampling gain shifting stage, the voltage sampling gain is switched through the sampling gain switching circuit; In the second control loop transition phase, the connection between the sampling gain switching circuit and the loop control circuit is closed; When the power supply returns to the stable output stage, the connection between the auxiliary shift circuit and the loop control circuit is disconnected, and the power supply is controlled by the constant voltage loop circuit.

[0017] The technical solution adopted by the present invention includes the following technical effects: 1. The auxiliary shift circuit of the present invention is used to output the sampled second voltage signal to the second input terminal of the loop control circuit, and when the constant voltage loop circuit is connected to the loop control circuit, the capacitor C1 in the auxiliary shift circuit is charged. After the capacitor C1 is charged, all switches directly connected to the capacitor C1 in the auxiliary shift circuit are disconnected, and the capacitor C1 maintains the voltage at the time when the switch is disconnected, and the auxiliary shift circuit is connected to the loop control circuit; wherein, the voltage of the capacitor C1 when charging is completed is the same as the sampled value of the power supply current at the current moment, and the voltage output by the auxiliary shift circuit is used as the given input of the loop control circuit; the sampling gain switching circuit is used to output the sampled first voltage signal to The first input end of the loop control circuit, and after the capacitor C1 in the auxiliary shift circuit is charged and disconnected from the loop control circuit, the sampling gain is switched; the loop control circuit is used to connect the auxiliary shift circuit in the constant current loop circuit after the capacitor C1 in the auxiliary shift circuit is charged, disconnect the constant voltage loop circuit from the loop control circuit, and after the sampling gain is switched, connect the constant voltage loop circuit to the loop control circuit, disconnect the constant current loop circuit from the loop control circuit, effectively solve the problem that the voltage sampling gain cannot be switched during the continuous output of the power supply due to the existing technology, and realize the switching of the voltage sampling gain during the constant voltage output of the power supply.

[0018] 2. The sampling gain switching circuit in the technical solution of the present invention includes multiple parallel sampling gain circuits. The resistance values ​​of the resistors in each sampling gain circuit are different from each other, which can provide different sampling gain switching circuits and improve the flexibility of use.

[0019] 3. In the technical solution of the present invention, when the constant voltage loop circuit is connected to the loop control circuit, the sum of the given voltage signal VG of the loop control circuit and the first voltage signal VFB fed back by the voltage sampling circuit is 0; after the constant current loop circuit is connected to the loop control circuit, the sum of the output signal Vc of the auxiliary shift circuit and the second voltage signal IFB fed back by the current sampling circuit is 0, which can realize the switching of the voltage sampling gain during the constant voltage closed-loop output process of the power supply, and during the switching process, the output voltage and current remain stable without obvious fluctuations.

[0020] It should be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0022] Figure 1 Schematic diagram of the connection structure of the circuit in Example 1 of the present invention; Figure 2 This is a schematic flow chart of the method of Example 2 in the scheme of the present invention; Figure 3 This is a schematic diagram of the switch control logic timing for performing a voltage sampling gain switch according to the second embodiment of the present invention. DETAILED DESCRIPTION

[0023] In order to clearly illustrate the technical features of this solution, the present invention is described in detail below through specific implementation methods and in conjunction with the accompanying drawings. The disclosure below provides many different embodiments or examples for realizing different structures of the present invention. In order to simplify the disclosure of the present invention, the components and settings of specific examples are described below. In addition, the present invention may repeat reference numbers and / or letters in different examples. This repetition is for the purpose of simplicity and clarity and does not itself indicate the relationship between the various embodiments and / or settings discussed. It should be noted that the components illustrated in the accompanying drawings are not necessarily drawn to scale. The present invention omits descriptions of well-known components and processing technologies and processes to avoid unnecessary limitations on the present invention.

[0024] Example 1 The significance of switching the voltage sampling gain: For example, if the DA resolution is 8 bits, the power supply range is 0-100V, and the voltage sampling range is 0-100V, the power supply output resolution is 100V / (2^8)=39mV, and the adjustable step size of the power supply output is 39mV. If the voltage sampling gain is increased by 10 times, the voltage sampling range becomes 0-10V, the power supply output range becomes 0-10V, the power supply output resolution becomes 10V / (2^8)=3.9mV, and the adjustable step size of the power supply output is 3.9mV. Therefore, when outputting small voltages, increasing the sampling gain can increase the minimum output resolution and reduce the adjustable step size of the output voltage.

[0025] The main function of this invention is to ensure that the power supply continues to output during the gain switching process without powering off. For example, if the user reduces the power supply output from 100V to 1V, the power supply output can smoothly transition to 1V and complete the gain switching, without the need to: stop output → switch gain → restart output.

[0026] Specifically, if Figure 1 As shown, the present invention provides a switching control circuit for sampling gain in a constant voltage output of a power supply, comprising: a power supply, a loop control circuit, a modulation circuit, a constant current loop circuit, a constant voltage loop circuit connected in parallel with the constant current loop, the constant current loop circuit comprising a current sampling circuit and an auxiliary shifting circuit connected in series, the constant voltage loop circuit comprising a voltage sampling circuit and a sampling gain switching circuit connected in series, the first input end of the loop control circuit being connected to the output end of the constant voltage loop circuit, the second input end of the loop control circuit being connected to the output end of the constant current loop circuit, the input end of the modulation circuit being connected to the output end of the loop control circuit, and the output end of the modulation circuit being connected to the driving input end of the power supply; the voltage sampling circuit being used to perform voltage sampling on the power output end of the power supply and outputting the sampled first voltage signal to the sampling gain switching circuit; the current sampling circuit being used to perform current sampling on the output end of the power supply and outputting the sampled second voltage signal to the auxiliary shifting circuit; the auxiliary shifting circuit being used to output the sampled second voltage signal to the second input end of the loop control circuit, and connecting the loop control circuit to the constant voltage loop circuit. When the capacitor C1 in the auxiliary shift circuit is charged, after the capacitor C1 is charged, all switches directly connected to the capacitor C1 in the auxiliary shift circuit are disconnected, the capacitor C1 maintains the voltage at the moment the switch is disconnected, and the auxiliary shift circuit is connected to the loop control circuit; wherein, the voltage of the capacitor C1 when charging is completed is the same as the sampled value of the power supply current at the current moment, and the voltage output by the auxiliary shift circuit is used as the given input of the loop control circuit; the sampling gain switching circuit is used to output the sampled first voltage signal to the first input end of the loop control circuit, and after the capacitor C1 in the auxiliary shift circuit is charged and disconnected from the loop control circuit, perform sampling gain switching; the loop control circuit is used to connect the auxiliary shift circuit in the constant current loop circuit after the capacitor C1 in the auxiliary shift circuit is charged, disconnect the constant voltage loop circuit from the loop control circuit, and connect the constant voltage loop circuit to the loop control circuit after the sampling gain switching is completed, and disconnect the constant current loop circuit from the loop control circuit, wherein the power supply is a DC power supply.

[0027] The voltage sampling circuit includes resistors R11, R13, R14, and R12, as well as an operational amplifier U1. One of the non-inverting inputs of operational amplifier U1 is connected to ground via resistor R12, and another is connected to the high-voltage input of the power supply via resistor R14. One of the inverting inputs of operational amplifier U1 is connected to the low-voltage input of the power supply via resistor R13, and another is connected to the output of operational amplifier U1. The output of the operational amplifier is connected to the input of the sampling gain switching circuit. VFB is the voltage feedback signal (first voltage signal) after the voltage sampling circuit.

[0028] The sampling gain switching circuit (an inverting amplifier with adjustable gain) includes an operational amplifier U2, a resistor R10, and multiple parallel sampling gain circuits. The inverting input of operational amplifier U2 is connected to the output of the voltage sampling circuit through resistor R10 and to the output of operational amplifier U2 through a sampling gain circuit. The non-inverting input of operational amplifier U2 is grounded. The resistors in each sampling gain circuit have different values.

[0029] Specifically, the first sampling gain circuit includes a switch K3 and a resistor R7, and the second sampling gain circuit includes a switch K4 and a resistor R8. One end of the resistor K3 is connected to the output end of the operational amplifier U2, and the other end of the resistor K3 is connected to one end of the resistor R7, and the resistor R7 is connected to the inverting input end of the operational amplifier U2; one end of the resistor K4 is connected to the output end of the operational amplifier U2, and the other end of the resistor K4 is connected to one end of the resistor R8, and the resistor R8 is connected to the inverting input end of the operational amplifier U2; wherein the resistance values ​​of the resistor R7 and the resistor R8 are different.

[0030] The sampling gain switching circuit also includes a third sampling gain circuit, which includes a switch K5 and a resistor R9. One end of resistor K5 is connected to the output of operational amplifier U2, and the other end of resistor K5 is connected to one end of resistor R9, which is connected to the inverting input of operational amplifier U2. Resistors R7, R8, and R9 have different resistance values. Switching resistors K3 through K5 adjusts the amplification ratio of the inverting amplifier to adjust the voltage sampling gain. For example, the resistance values ​​of resistors R7, R8, and R9 are related to the power supply resolution and accuracy required by the power supply user. If the resolution needs to be adjusted by a factor of 10, R9 can be set to 10*R8=100*R7. Thus, when R8 is connected, the sampling gain increases by 10 times, and the minimum output resolution of the power supply increases by 10 times, compared to when R7 is connected. When R9 is connected, the sampling gain increases by 100 times, and the minimum output resolution of the power supply increases by 100 times.

[0031] The loop control circuit includes an operational amplifier U4, a resistor R3, a resistor R4, a resistor R5, a resistor R6, a capacitor C2, and a switch K2. One end of the resistor R3 is connected to the output end of the sampling gain switching circuit, the other end of the resistor R3 is connected to one end of the switch K2, the other end of the switch K2 is connected to the resistor R4, and the other end of the switch K2 is connected to the non-inverting input end of the operational amplifier U4. One path of the inverting input end of the operational amplifier U4 is grounded through the resistor R5, and the other path is connected to the output end of the operational amplifier U4 through the series-connected resistor R6 and capacitor C1. The output end of the operational amplifier U4 is connected to the power supply. The resistance value of the resistor R3 is the same as that of the resistor R4, and the other end of the resistor R4 is connected to the given DA, which is used to adjust the amplitude of the given VG by controlling the DA.

[0032] The input of the modulation circuit is connected to the output of operational amplifier U4, and the output of the modulation circuit is connected to the drive input of the power supply. The modulation wave (the output signal of the loop control circuit) is generated by the modulation circuit into a drive signal, which controls the power supply. For switching power supplies, the drive signal is typically a PWM signal. For linear power supplies, the drive signal is typically an analog signal that adjusts the operating range of discrete semiconductor devices. R1 is the current sampling resistor, R2 is the load of the power supply, point A is the high-voltage output terminal of the power supply, and point B is the low-voltage output terminal of the power supply.

[0033] The current sampling circuit includes an operational amplifier U5, a resistor R21, a resistor R22, a resistor R23, and a resistor R24. The non-inverting input terminal of the operational amplifier U5 is connected to the ground through the resistor R21, and the other terminal is connected to one end of the sampling resistor R1 at the power output end through the resistor R23; the inverting input terminal of the operational amplifier U5 is connected to the output terminal of the operational amplifier U5 through the resistor R22, and the other terminal is connected to the other end of the sampling resistor R1 at the power output end through the resistor R24. The output terminal of the operational amplifier U5 is connected to the input terminal of the auxiliary shift circuit.

[0034] The auxiliary shift circuit includes an operational amplifier U6, an operational amplifier U3, a capacitor C1, a resistor R15, a resistor R16, a resistor R17, a resistor R18, a resistor R19, a resistor R20, a switch K1, a switch K6, and a switch K7. The non-inverting input of the operational amplifier U6 is grounded, and the inverting input of the operational amplifier U6 is connected to the output of the current sampling circuit through the resistor R20 in one path and to the output of the operational amplifier U6 in the other path through the resistor R19. The output of the operational amplifier U6 is connected to the non-inverting input of the operational amplifier U3 in turn through the series-connected resistor R18 and the switch K7. The non-inverting input terminal of the operational amplifier U3 is connected to ground through the capacitor C1 in one path, is connected to ground through the switch K6 and the resistor R7 in series in one path, and is connected to the output terminal of the operational amplifier U6 in another path through the switch K7 and the resistor R18 in series in another path. The inverting input terminal of the operational amplifier U3 is connected to the output terminal of the operational amplifier U3, the output terminal of the operational amplifier U3 is connected to one end of the switch K1 through the resistor R16, one end of the resistor R15 is connected to the output terminal of the current sampling circuit, the other end of the resistor R15 is connected to one end of the switch K1, and the other end of the switch K1 is electrically connected to the second input terminal of the loop control circuit.

[0035] When switch K6 is opened and switch K7 is closed, capacitor C1 starts to charge. After capacitor C1 is fully charged, switches K6 and K7 are both opened, and capacitor C1 maintains the voltage at the time when the switches are opened. When switch K6 is closed and switch K7 is opened, capacitor C1 starts to discharge. The resistance value of resistor R19 is equal to the resistance value of resistor R20, and the resistance value of resistor R15 is equal to the resistance value of resistor R16.

[0036] The voltage of capacitor C1 upon completion of charging is identical to the current sampled value IFB (second voltage signal) of the power supply current at the current moment (when the switch directly connected to capacitor C1 is disconnected). Furthermore, the voltage Vc output by the auxiliary shift circuit serves as the given input voltage for the loop control circuit. Furthermore, the power supply current sampled value IFB serves as the current feedback signal for the loop current control circuit. Vc is the current sampled value at the moment the switches (switch K6, switch K7) are disconnected, serving as the given value for the current loop, while VG is the given voltage value. Vc and VG are not numerically equivalent, but when Vc and VG are used as the loop given value, control can ensure that the power supply output remains constant (the shifting time is very short, assuming the power supply load remains unchanged). IFB as feedback is a continuous process, and control is also a continuous process. During the time the constant current loop circuit is engaged, IFB is always feedback, and Vc is always given, but the value of Vc is based on the value at the moment the switch is disconnected.

[0037] Specifically, the output of the loop control circuit is a modulated wave. VG is the loop reference (reference DA), VFB is the loop feedback, and resistor R4 is equal to feedback resistor R3. U4 is the loop control op amp. When switch K2 is closed and switch K1 is open, the power supply is in a constant voltage output state. Resistor R1 is the current sampling resistor; op amp U5, resistors R21, R22, R23, and R24 form the current sampling circuit; IFB is the current feedback signal after current sampling. Op amps U6 and U3, capacitor C1, resistors R15, R16, R17, R18, R19, and R20, and switches K1, K6, and K7 together form the auxiliary shift circuit. The resistance of R19 is equal to that of R20, and the resistance of R15 is equal to that of R16. Together with op amp U6, they form an inverter to produce -VFB. C1 is a holding capacitor. The follower formed by op amp U3 outputs the voltage across the capacitor as Vc. R17 and R18 act as current limiters. When K7 is closed and K6 is open, Vc = -IFB (the output current is converted into a voltage signal after passing through the current sampling circuit; IFB in the figure shows the converted voltage signal). When K6 is closed and K7 is open, capacitor C1 is discharged. After K6 is opened, K7 closes for a period of time until the voltage across C1 rises to -VFB, and then K7 is opened. This maintains the inverse of the current sampling value at that moment, -VFB, on the capacitor. This controls the output current during the shift process to the current at the moment K7 is opened, preventing the power supply output from changing and ensuring output stability. R16 is the reference resistor for the auxiliary shift loop, and R15 is the feedback resistor for the auxiliary shift loop. When K1 is closed and K2 is open, the voltage Vc provided by the auxiliary shift loop serves as the loop reference, and the current feedback signal IFB serves as the current feedback. The power supply output is controlled by Vc and is independent of the voltage reference and feedback.

[0038] When the constant voltage loop circuit is connected to the loop control circuit, the sum of the given voltage signal VG of the loop control circuit and the first voltage signal VFB fed back by the voltage sampling circuit is 0; after the constant current loop circuit is connected to the loop control circuit, the sum of the output voltage signal Vc of the auxiliary shift circuit and the second voltage signal IFB fed back by the current sampling circuit is 0.

[0039] During the constant voltage output process of the power supply, when the output voltage needs to be changed and the voltage sampling circuit gain needs to be switched, the auxiliary shift circuit is first connected to the loop control circuit, and then the constant voltage loop circuit is disconnected from the loop control circuit, and then the gain of the voltage sampling circuit is switched. Figure 1K3-K5 in the middle change the amplification ratio of the reverse amplifier circuit to switch the voltage sampling gain. The given amplitude VG is adjusted by adjusting the output of DA. After the switching is completed, the voltage feedback and given value are connected, and then the auxiliary shift circuit is disconnected. The control circuit will adjust the output of the power supply to the new set value. The principle of the auxiliary shift circuit is to maintain the output current value before the shift occurs through a capacitor. The output voltage signal of the auxiliary shift circuit corresponding to the current value IFB at the moment before the shift is used as the given Vc for the loop control, and the current sampling signal IFB is used as the feedback of the control loop. In this way, during the process of switching the voltage sampling gain, the loop that maintains the output current unchanged is used to control the power supply, ensuring the stability of the output current during this process. Because the shift process lasts very short, the load of the power supply generally does not change significantly, thus ensuring the stability of the output voltage.

[0040] The control method for switching the voltage sampling gain during constant-voltage output of a power supply, proposed in the present invention, can achieve switching the voltage sampling gain during the constant-voltage closed-loop output process of the power supply, and during the switching process, the output voltage and current remain stable without significant fluctuations. The present invention is primarily applicable to DC power supplies and is not applicable to AC power supplies whose output is constantly changing. Non-stop shifting is accomplished by switching between a constant-voltage control loop and an auxiliary shifting loop. The auxiliary shifting circuit uses a capacitor and a switch to take the inverse of the current sampling value before the shift as the loop reference, with the current sampling used as feedback. During the shifting process, the output state of the control power supply remains unchanged, and switching the voltage sampling gain does not affect the output.

[0041] The auxiliary shift circuit of the present invention is used to output the sampled second voltage signal to the second input end of the loop control circuit, and when the constant voltage loop circuit is connected to the loop control circuit, the capacitor C1 in the auxiliary shift circuit is charged. After the capacitor C1 is charged, all switches directly connected to the capacitor C1 in the auxiliary shift circuit are disconnected, and the capacitor C1 maintains the voltage at the time when the switch is disconnected, and the auxiliary shift circuit is connected to the loop control circuit; wherein, the voltage of the capacitor C1 when charging is completed is the same as the sampled value of the power supply current at the current moment, and the voltage output by the auxiliary shift circuit is used as the given input of the loop control circuit; the sampling gain switching circuit is used to output the sampled first voltage signal to the loop The first input end of the control circuit is connected to the auxiliary shift circuit after the capacitor C1 in the auxiliary shift circuit is charged and the connection with the loop control circuit is disconnected, and the sampling gain is switched; the loop control circuit is used to connect the auxiliary shift circuit in the constant current loop circuit after the capacitor C1 in the auxiliary shift circuit is charged, disconnect the constant voltage loop circuit from the loop control circuit, and connect the constant voltage loop circuit to the loop control circuit after the sampling gain is switched, and disconnect the constant current loop circuit from the loop control circuit, effectively solving the problem that the voltage sampling gain cannot be switched during the continuous output of the power supply due to the existing technology, and realizing the switching of the voltage sampling gain during the constant voltage output of the power supply.

[0042] The sampling gain switching circuit in the technical solution of the present invention includes a plurality of sampling gain circuits connected in parallel. The resistance values ​​of the resistors in each sampling gain circuit are different from each other, so different sampling gain switching circuits can be provided, thereby improving the flexibility of use.

[0043] In the technical solution of the present invention, when the constant voltage loop circuit is connected to the loop control circuit, the sum of the given voltage signal VG of the loop control circuit and the first voltage signal VFB fed back by the voltage sampling circuit is 0; after the constant current loop circuit is connected to the loop control circuit, the sum of the output signal Vc of the auxiliary shift circuit and the second voltage signal IFB fed back by the current sampling circuit is 0, which can realize the switching of the voltage sampling gain during the constant voltage closed-loop output process of the power supply, and during the switching process, the output voltage and current remain stable without obvious fluctuations.

[0044] Example 2 like Figure 2 As shown, the technical solution of the present invention further provides a method for switching control of sampling gain in constant voltage output of a power supply, which is implemented based on a switching control circuit for sampling gain in constant voltage output of a power supply described in embodiment 1, and includes: During the normal power supply output phase (t0-t1, excluding t1), the connection between the auxiliary shift circuit and the loop control circuit is disconnected, and the connection between the sampling gain switching circuit and the loop control circuit is closed. The power supply is in constant voltage output. During the capacitor charging phase (t1-t2, excluding t2), the capacitor C1 in the auxiliary shift circuit begins to charge; During the first control loop transition phase (t2-t3, excluding t3), after the capacitor C1 in the auxiliary shift circuit is fully charged, the switches (K6, K7) directly connected to the capacitor C1 in the auxiliary shift circuit are disconnected, and the capacitor C1 maintains the voltage at the time the switches are disconnected. The auxiliary shift circuit is then connected to the loop control circuit. The voltage of the capacitor C1 upon completion of charging is the same as the sampled value of the power supply current at the current moment, and the voltage output by the auxiliary shift circuit is used as a given input to the loop control circuit. During the power supply stable output phase (t3-t4, excluding t4), the connection between the sampling gain switching circuit and the loop control circuit is disconnected, and the power supply is controlled by the constant current loop circuit. In the sampling gain shifting phase (t4-t5, excluding t5), the voltage sampling gain is switched through the sampling gain switching circuit; During the second control loop transition phase (t5-t6, excluding t6), the connection between the sampling gain switching circuit and the loop control circuit is closed; When the power supply returns to the stable output stage (t6-), the connection between the auxiliary shift circuit and the loop control circuit is disconnected, and the power supply is controlled by the constant voltage loop circuit.

[0045] Figure 3 This is a switch control logic timing diagram for switching the voltage sampling gain, such as Figure 3 As shown, in this process, the resistor that controls the voltage sampling gain is switched from R7 to R8 (for example, other switching methods are also possible), and K5 is always in the disconnected state, so Figure 2 Without K5, the detailed working principle and logic sequence are as follows: Normal output stage of the power supply (t0-t1, excluding t1): At t0, K1 is disconnected and K2 is closed. The control loop is given by VG and the feedback is VFB. The power supply is in constant voltage output. K3 is closed and K4 is disconnected. R7 is connected to the sampling gain of the control voltage. K6 is closed and K7 is disconnected. The capacitor on C1 starts to discharge and the voltage is 0V.

[0046] During the capacitor charging phase (t1-t2, excluding t2), at time t1, the voltage sampling gain switching starts, K6 is disconnected, K7 is closed, and capacitor C1 starts charging. The duration of this phase must be greater than the charging time.

[0047] In the first control loop transition phase (t2-t3, excluding t3), at time t2, K7 is disconnected, and capacitor C1 has been fully charged. After capacitor C1 is fully charged, all switches directly connected to capacitor C1 in the auxiliary shift circuit are disconnected, capacitor C1 maintains the voltage at the time of switch disconnection, and the auxiliary shift circuit is connected to the loop control circuit; wherein, the voltage of capacitor C1 when charging is completed is the same as the sampled value of the power supply current at the current moment, and the voltage Vc output by the auxiliary shift circuit is used as the given input of the loop control circuit; the Vc level is equal to -VFB at time t2; K1 is closed, and the auxiliary shift loop is connected. Since the difference between the two sets of given feedback is 0, the output will not change; the stage duration can be greater than the time for K7 and K1 to act.

[0048] In the stable power output stage (t3-t4, excluding t4), at t3, K2 is disconnected, and the power supply is completely controlled by the auxiliary shift loop. IFB is feedback, Vc is given, and the loop controls the power supply so that the power output current remains consistent with t2, and the power output is stable. The stage duration only needs to be greater than the time K2 operates.

[0049] During the sampling gain shifting phase (t4-t5, excluding t5), at time t4, K3 is disconnected and K4 is closed, completing the switching of the voltage sampling gain and the adjustment of the given VG. At this time, VFB and VG do not participate in the control and will not affect the loop control, and the power supply output is stable. The duration of this phase is greater than the action duration of K3 and K4.

[0050] In the second control loop transition phase (t5-t6, excluding t6), at t5, K2 is closed, the voltage closed-loop control loop is connected, and the power supply output begins to adjust; the duration of this phase needs to be greater than the time it takes for the power supply output to stabilize.

[0051] The power supply returns to the stable output stage (t6-). At t6, K1 is disconnected and the power supply is completely controlled by the voltage loop; K6 is closed and capacitor C1 is discharged. At this point, the gain adjustment process of the power supply sampling is completed.

[0052] During the entire voltage sampling gain adjustment process, the power supply remains in the output state. The power supply control loop switches from a constant voltage loop to a constant current loop, and then back to a constant voltage loop. Because the constant current loop's reference is the inverse of the output current sampled value at time t2, the difference in the reference feedback of the constant current loop used to assist in shifting remains zero, preventing output fluctuations during the loop switching process. Using analog switches with low leakage current for K6 and K7 in the circuit facilitates output waveform stability. K1 and K2 can be analog switches or devices such as JFETs. The control circuit's control parameters must be adapted to different voltage sampling gains and constant current output states to ensure sufficient phase margin.

[0053] The auxiliary shift circuit of the present invention is used to output the sampled second voltage signal to the second input end of the loop control circuit, and when the constant voltage loop circuit is connected to the loop control circuit, the capacitor C1 in the auxiliary shift circuit is charged. After the capacitor C1 is charged, all switches directly connected to the capacitor C1 in the auxiliary shift circuit are disconnected, and the capacitor C1 maintains the voltage at the time when the switch is disconnected, and the auxiliary shift circuit is connected to the loop control circuit; wherein, the voltage of the capacitor C1 when charging is completed is the same as the sampled value of the power supply current at the current moment, and the voltage output by the auxiliary shift circuit is used as the given input of the loop control circuit; the sampling gain switching circuit is used to output the sampled first voltage signal to the loop The first input end of the control circuit is connected to the auxiliary shift circuit after the capacitor C1 in the auxiliary shift circuit is charged and the connection with the loop control circuit is disconnected, and the sampling gain is switched; the loop control circuit is used to connect the auxiliary shift circuit in the constant current loop circuit after the capacitor C1 in the auxiliary shift circuit is charged, disconnect the constant voltage loop circuit from the loop control circuit, and connect the constant voltage loop circuit to the loop control circuit after the sampling gain is switched, and disconnect the constant current loop circuit from the loop control circuit, effectively solving the problem that the voltage sampling gain cannot be switched during the continuous output of the power supply due to the existing technology, and realizing the switching of the voltage sampling gain during the constant voltage output of the power supply.

[0054] The sampling gain switching circuit in the technical solution of the present invention includes a plurality of sampling gain circuits connected in parallel. The resistance values ​​of the resistors in each sampling gain circuit are different from each other, so different sampling gain switching circuits can be provided, thereby improving the flexibility of use.

[0055] In the technical solution of the present invention, when the constant voltage loop circuit is connected to the loop control circuit, the sum of the given voltage signal VG of the loop control circuit and the first voltage signal VFB fed back by the voltage sampling circuit is 0; after the constant current loop circuit is connected to the loop control circuit, the sum of the output signal Vc of the auxiliary shift circuit and the second voltage signal IFB fed back by the current sampling circuit is 0, which can realize the switching of the voltage sampling gain during the constant voltage closed-loop output process of the power supply, and during the switching process, the output voltage and current remain stable without obvious fluctuations.

[0056] Although the above describes the specific embodiments of the present invention in conjunction with the accompanying drawings, it is not intended to limit the scope of protection of the present invention. Those skilled in the art should understand that various modifications or variations that can be made by those skilled in the art on the basis of the technical solution of the present invention without any creative work are still within the scope of protection of the present invention.

Claims

1. A switching control circuit for sampling gain in a constant voltage output of a power supply, characterized in that: include: A power supply, a loop control circuit, a modulation circuit, a constant current loop circuit, and a constant voltage loop circuit connected in parallel with the constant current loop. The constant current loop circuit includes a current sampling circuit and an auxiliary shifting circuit connected in series. The constant voltage loop circuit includes a voltage sampling circuit and a sampling gain switching circuit connected in series. The first input end of the loop control circuit is connected to the output end of the constant voltage loop circuit, the second input end of the loop control circuit is connected to the output end of the constant current loop circuit, the input end of the modulation circuit is connected to the output end of the loop control circuit, and the output end of the modulation circuit is connected to the driving input end of the power supply; the voltage sampling circuit is used to sample the voltage of the power output end of the power supply and output the sampled first voltage signal to the sampling gain switching circuit; the current sampling circuit is used to sample the current of the output end of the power supply and output the sampled second voltage signal to the auxiliary shifting circuit; the auxiliary shifting circuit is used to output the sampled second voltage signal to the second input end of the loop control circuit, and when the constant voltage loop circuit is connected to the loop control circuit, the capacitor in the auxiliary shifting circuit is switched. C1 is charged. After the charging of the capacitor C1 is completed, all switches directly connected to the capacitor C1 in the auxiliary shift circuit are disconnected, the capacitor C1 maintains the voltage at the moment the switch is disconnected, and the auxiliary shift circuit is connected to the loop control circuit; wherein, the voltage of the capacitor C1 when charging is completed is the same as the sampled value of the power supply current at the current moment, and the voltage output by the auxiliary shift circuit is used as the given input of the loop control circuit; the sampling gain switching circuit is used to output the sampled first voltage signal to the first input end of the loop control circuit, and after the charging of the capacitor C1 in the auxiliary shift circuit is completed and the connection with the loop control circuit is disconnected, the sampling gain is switched; the loop control circuit is used to connect the auxiliary shift circuit in the constant current loop circuit after the charging of the capacitor C1 in the auxiliary shift circuit is completed, disconnect the constant voltage loop circuit from the loop control circuit, and connect the constant voltage loop circuit to the loop control circuit after the switching of the sampling gain is completed, and disconnect the constant current loop circuit from the loop control circuit, wherein the power supply is a DC power supply.

2. A switching control circuit for sampling gain in a constant voltage output of a power supply according to claim 1, characterized in that: The voltage sampling circuit includes resistors R11, R13, R14, R12, and an operational amplifier U1. One path of the non-inverting input of the operational amplifier U1 is connected to the ground through resistor R12, and the other path is connected to the high-voltage input of the power supply through resistor R14; one path of the inverting input of the operational amplifier U1 is connected to the low-voltage input of the power supply through resistor R13, and the other path is connected to the output of the operational amplifier U1. The output of the operational amplifier is connected to the input of the sampling gain switching circuit.

3. A switching control circuit for sampling gain in a constant voltage output of a power supply according to claim 1, characterized in that: The sampling gain switching circuit includes an operational amplifier U2, a resistor R10, and multiple parallel sampling gain circuits. The inverting input terminal of the operational amplifier U2 is connected to the output terminal of the voltage sampling circuit through the resistor R10, and is connected to the output terminal of the operational amplifier U2 through a certain sampling gain circuit. The non-inverting input terminal of the operational amplifier U2 is grounded.

4. A switching control circuit for sampling gain in a constant voltage output of a power supply according to claim 3, characterized in that: The resistance values ​​of the resistors in each sampling gain circuit are different from each other.

5. A switching control circuit for sampling gain in a constant voltage output of a power supply according to claim 1, characterized in that: When the constant voltage loop circuit is connected to the loop control circuit, the sum of the given voltage signal VG of the loop control circuit and the first voltage signal VFB fed back by the voltage sampling circuit is 0; after the constant current loop circuit is connected to the loop control circuit, the sum of the output signal Vc of the auxiliary shift circuit and the second voltage signal IFB fed back by the current sampling circuit is 0.

6. A switching control circuit for sampling gain in a constant voltage output of a power supply according to claim 1, characterized in that the loop The control circuit includes an operational amplifier U4, a resistor R3, a resistor R4, a resistor R5, a resistor R6, a capacitor C2, and a switch K2. One end of the resistor R3 is connected to the output end of the sampling gain switching circuit, the other end of the resistor R3 is connected to one end of the switch K2, the other end of the switch K2 is connected to the resistor R4, and the other end of the switch K2 is connected to the non-inverting input end of the operational amplifier U4. One path of the inverting input end of the operational amplifier U4 is grounded through the resistor R5, and the other path is connected to the output end of the operational amplifier U4 through the series-connected resistor R6 and capacitor C1. The output end of the operational amplifier U4 is connected to the power supply. The resistance value of the resistor R3 is the same as that of the resistor R4.

7. A switching control circuit for sampling gain in a constant voltage output of a power supply according to claim 1, characterized in that: The current sampling circuit includes an operational amplifier U5, a resistor R21, a resistor R22, a resistor R23, and a resistor R24. The non-inverting input terminal of the operational amplifier U5 is connected to the ground through the resistor R21, and the other terminal is connected to one end of the sampling resistor R1 at the power output end through the resistor R23; the inverting input terminal of the operational amplifier U5 is connected to the output terminal of the operational amplifier U5 through the resistor R22, and the other terminal is connected to the other end of the sampling resistor R1 at the power output end through the resistor R24. The output terminal of the operational amplifier U5 is connected to the input terminal of the auxiliary shift circuit.

8. A switching control circuit for sampling gain in a constant voltage output of a power supply according to claim 1, characterized in that: The auxiliary shift circuit includes an operational amplifier U6, an operational amplifier U3, a capacitor C1, a resistor R15, a resistor R16, a resistor R17, a resistor R18, a resistor R19, a resistor R20, a switch K1, a switch K6, and a switch K7. The non-inverting input of the operational amplifier U6 is grounded, and the inverting input of the operational amplifier U6 is connected to the output of the current sampling circuit through the resistor R20 in one path and to the output of the operational amplifier U6 in the other path through the resistor R19. The output of the operational amplifier U6 is connected to the non-inverting input of the operational amplifier U3 in turn through the series-connected resistor R18 and the switch K7. The non-inverting input terminal of the operational amplifier U3 is connected to ground through the capacitor C1 in one path, is connected to ground through the switch K6 and the resistor R7 in series in one path, and is connected to the output terminal of the operational amplifier U6 in another path through the switch K7 and the resistor R18 in series in another path. The inverting input terminal of the operational amplifier U3 is connected to the output terminal of the operational amplifier U3, the output terminal of the operational amplifier U3 is connected to one end of the switch K1 through the resistor R16, one end of the resistor R15 is connected to the output terminal of the current sampling circuit, the other end of the resistor R15 is connected to one end of the switch K1, and the other end of the switch K1 is electrically connected to the second input terminal of the loop control circuit.

9. A switching control circuit for sampling gain in a constant voltage output of a power supply according to claim 8, characterized in that: When switch K6 is opened and switch K7 is closed, capacitor C1 starts to charge. After capacitor C1 is fully charged, switches K6 and K7 are both opened, and capacitor C1 maintains the voltage at the time when the switches are opened. When switch K6 is closed and switch K7 is opened, capacitor C1 starts to discharge. The resistance value of resistor R19 is equal to the resistance value of resistor R20, and the resistance value of resistor R15 is equal to the resistance value of resistor R16.

10. A method for switching and controlling sampling gain in a constant voltage output of a power supply according to claim 1, characterized in that: The method is implemented based on a switching control circuit for sampling gain in a constant voltage output of a power supply according to any one of claims 1 to 9, comprising: In the normal power output stage, the connection between the auxiliary shift circuit and the loop control circuit is disconnected, and the connection between the sampling gain switching circuit and the loop control circuit is closed, and the power supply is in constant voltage output; During the capacitor charging phase, the capacitor C1 in the auxiliary shift circuit begins to charge; During the first control loop transition phase, after the capacitor C1 in the auxiliary shift circuit is fully charged, all switches directly connected to the capacitor C1 in the auxiliary shift circuit are disconnected, and the capacitor C1 maintains the voltage at the time the switches are disconnected. The auxiliary shift circuit is then connected to the loop control circuit. The voltage of the capacitor C1 upon completion of charging is the same as the sampled value of the power supply current at the current moment, and the voltage output by the auxiliary shift circuit is used as a given input for the loop control circuit. During the power supply stable output stage, the connection between the sampling gain switching circuit and the loop control circuit is disconnected, and the power supply is controlled by the constant current loop circuit; In the sampling gain shifting stage, the voltage sampling gain is switched through the sampling gain switching circuit; In the second control loop transition phase, the connection between the sampling gain switching circuit and the loop control circuit is closed; When the power supply returns to the stable output stage, the connection between the auxiliary shift circuit and the loop control circuit is disconnected, and the power supply is controlled by the constant voltage loop circuit.

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