Linear voltage amplification system applied to high voltage

Abstract

The invention discloses a linear voltage amplification system applied to high voltage, which comprises a plurality of cascade units, each cascade unit comprises a high-voltage unit, a voltage source and a voltage amplification circuit, and each voltage amplification circuit comprises a non-inverting amplifier and an inverting amplifier, the output of the voltage amplifying circuit is differential output between the non-inverting amplifier and the inverting amplifier, the voltage source supplies power to the voltage amplifying circuit, and the positive output end of the high-voltage unit is electrically connected with the input end of the non-inverting amplifier. The negative output end of the high-voltage unit is electrically connected with the input end of the inverting amplification circuit; and the plurality of cascade units are connected in series to output high voltage.

Description

Technical Field

[0001] The invention relates to the technical field of linear voltage amplifiers, in particular to a linear voltage amplification system applied to high voltage. Background Art

[0002] High voltage measurements, such as dielectric measurements and other high voltage applications, require precision high voltage instruments. Currently, high voltage measurements require linear, high voltage, high frequency bandwidth power supply, which must be accurately monitored and controlled. Existing high voltage amplifiers generally use multi-channel amplifiers, which have the main disadvantages of not having high enough output voltage and gain, and it is difficult to accurately adjust and control the total gain. Summary of the invention

[0003] The object of the present invention is to solve at least one of the technical problems existing in the prior art and to provide a linear voltage amplification system with high output voltage and gain for high voltage application.

[0004] A linear voltage amplification system applied to high voltage according to an embodiment of the present invention comprises: a plurality of cascade units, wherein the cascade units comprise a high voltage unit, a voltage source and a voltage amplification circuit, wherein the voltage amplification circuit comprises a non-inverting amplifier and an inverting amplifier, wherein the output of the voltage amplification circuit is a differential output between the non-inverting amplifier and the inverting amplifier, wherein the voltage source supplies power to the voltage amplification circuit, wherein the positive output terminal of the high voltage unit is electrically connected to the input terminal of the non-inverting amplifier circuit, and the negative output terminal of the high voltage unit is electrically connected to the input terminal of the inverting amplifier circuit; and wherein the plurality of cascade units are connected in series to output high voltage.

[0005] According to some embodiments of the present invention, the non-inverting amplifier includes an op amp A1, an op amp A2, and an op amp A3, and the op amp A1, the op amp A2, and the op amp A3 form a voltage series negative feedback circuit, wherein the op amp A1 and the op amp A3 form a voltage follower to serve as a power supply for the op amp A2.

[0006] According to some embodiments of the present invention, the non-inverting amplifier further includes: a resistor R11, a resistor R12, a resistor R13, and a resistor R14, the positive input terminal of the operational amplifier A2 is electrically connected to the positive output terminal of the high-voltage unit, one end of the resistor R11 is grounded, and the other end is electrically connected to the reverse input terminal of the operational amplifier A2 and one end of the resistor R12 respectively, the other end of the resistor R12 is electrically connected to the output terminal of the operational amplifier A2, one end of the resistor R13 is electrically connected to the output terminal of the operational amplifier A1 and a power supply terminal of the operational amplifier A2 respectively, the other end of the resistor R13 is electrically connected to the reverse input terminal of the operational amplifier A1, the positive input terminal of the operational amplifier A1 is electrically connected to the output terminal of the operational amplifier A2 via a series resistor, one end of the resistor R14 is electrically connected to another power supply terminal of the operational amplifier A2, the other end of the resistor R14 is electrically connected to the reverse input terminal of the operational amplifier A3, and the positive input terminal of the operational amplifier A3 is electrically connected to the output terminal of the operational amplifier A2 via a series resistor.

[0007] According to some embodiments of the present invention, the inverting amplifier includes an operational amplifier A4, an operational amplifier A5, and an operational amplifier A6, and the operational amplifier A4, the operational amplifier A5, and the operational amplifier A6 form a voltage parallel negative feedback circuit.

[0008] According to some embodiments of the present invention, the inverting amplifier further includes: a resistor R21, a resistor R22, a resistor R23, and a resistor R24, the positive input terminal of the operational amplifier A5 is grounded, one end of the resistor R21 is electrically connected to the negative output terminal of the high-voltage unit, and the other end is electrically connected to the reverse input terminal of the operational amplifier A5 and one end of the resistor R22, respectively, the other end of the resistor R22 is electrically connected to the output terminal of the operational amplifier A5, one end of the resistor R23 is electrically connected to the output terminal of the operational amplifier A4 and a power supply terminal of the operational amplifier A5, respectively, the other end of the resistor R23 is electrically connected to the reverse input terminal of the operational amplifier A4, the positive input terminal of the operational amplifier A4 is electrically connected to the output terminal of the operational amplifier A5 via a series resistor, one end of the resistor R24 ​​is electrically connected to another power supply terminal of the operational amplifier A5, the other end of the resistor R24 ​​is electrically connected to the reverse input terminal of the operational amplifier A6, and the positive input terminal of the operational amplifier A6 is electrically connected to the output terminal of the operational amplifier A5 via a series resistor.

[0009] According to the linear voltage amplification system applied to high voltage of the embodiment of the present invention, at least the following beneficial effects are achieved: the voltage amplification circuit adopts a non-inverting amplifier and an inverting amplifier, and the final output is the differential output between the non-inverting amplifier and the inverting amplifier, so that the total gain of the voltage amplification circuit is the sum of the gain of the non-inverting amplifier and the gain of the inverting amplifier. In addition, the output voltage range is increased by cascading high-voltage units, and multiple cascade units connected in series can provide higher gain. Compared with multi-channel amplifiers, cascade units have better flexibility and wider bandwidth, which is mainly reflected in the following aspects: 1. Flexibility of gain design. Multiple cascade units are connected in series, and the total gain is the product of the gains of each cascade unit. The designer can adjust the gain of a single voltage amplifier circuit to achieve precise control of the total gain. This step-by-step adjustment method is particularly flexible when achieving large gain requirements. 2. Flexibility of frequency response. The frequency characteristics of each voltage amplifier circuit can be adjusted independently to avoid frequency distortion or bandwidth limitation. For example, the designer can improve the frequency response of the entire system by adding a high-pass or low-pass filter at a certain level. 3. By allocating bandwidth to different amplifier levels, wideband design can be more easily achieved. 4. Modular design makes fault isolation and maintenance easy. If a certain level fails, only the circuit at that level needs to be detected and repaired. However, due to the close coupling of each channel, the fault diagnosis of multi-channel amplifiers may be more complicated. In addition, each level of voltage amplifier circuit works independently, which makes it easy to upgrade or replace a single module.

[0010] Additional aspects and advantages of the present invention will be given in part in the following description and in part will be obvious from the following description, or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] The specific embodiments of the present invention will be further described below in conjunction with the accompanying drawings;

[0012] Figure 1 It is the schematic diagram of the voltage amplifier circuit;

[0013] Figure 2 It is the waveform diagram of output voltage and load voltage;

[0014] Figure 3 It is a circuit schematic diagram of multiple cascade units connected in series;

[0015] Figure 4 It is a simplified circuit diagram of a voltage parallel negative feedback circuit;

[0016] Figure 5 It is a frequency response curve diagram;

[0017] Figure 6 It is a graph showing the change of Vo / Vs over time. DETAILED DESCRIPTION

[0018] This section will describe in detail the specific embodiments of the present invention. The preferred embodiments of the present invention are shown in the accompanying drawings. The purpose of the accompanying drawings is to supplement the description of the text part of the specification with graphics, so that people can intuitively and vividly understand each technical feature and the overall technical solution of the present invention, but it cannot be understood as a limitation on the scope of protection of the present invention.

[0019] In the description of the present invention, it should be understood that descriptions involving orientations, such as up, down, front, back, left, right, etc., and orientations or positional relationships indicated are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.

[0020] In the description of the present invention, "several" means one or more, "more" means more than two, "greater than", "less than", "exceed" etc. are understood as not including the number itself, and "above", "below", "within" etc. are understood as including the number itself. If there is a description of "first" or "second", it is only used for the purpose of distinguishing the technical features, and cannot be understood as indicating or implying the relative importance or implicitly indicating the number of the indicated technical features or implicitly indicating the order of the indicated technical features.

[0021] Reference Figures 1 to 6 The present invention discloses a linear voltage amplification system for high voltage, comprising: a plurality of cascade units 10, wherein the cascade unit 10 comprises a high voltage unit 12, a voltage source and a voltage amplification circuit 11, wherein the voltage amplification circuit 11 comprises a non-inverting amplifier 111 and an inverting amplifier 112, wherein the output of the voltage amplification circuit 11 is a differential output between the non-inverting amplifier 111 and the inverting amplifier 112, wherein the voltage source supplies power to the voltage amplification circuit 11, wherein the positive output terminal of the high voltage unit 12 is electrically connected to the input terminal of the non-inverting amplifier circuit, and the negative output terminal of the high voltage unit 12 is electrically connected to the input terminal of the inverting amplifier circuit; wherein the plurality of cascade units 10 are connected in series to output high voltage. Figure 1As shown, the non-inverting amplifier 111 is a voltage series negative feedback circuit composed of operational amplifiers A1, A2 and A3. In practice, its voltage gain is adjusted to 20 times, and the maximum withstand voltage of operational amplifiers A1, A2 and A3 is 100V. Among them, operational amplifiers A1 and A3 form a voltage follower to serve as the power supply of operational amplifier A2. The non-inverting amplifier 111 specifically includes a resistor R11, a resistor R12, a resistor R13, and a resistor R14. The positive input terminal of the operational amplifier A2 is electrically connected to the positive output terminal of the high-voltage unit 12. One end of the resistor R11 is grounded, and the other end is electrically connected to the reverse input terminal of the operational amplifier A2 and one end of the resistor R12 respectively. The other end of the resistor R12 is electrically connected to the output terminal of the operational amplifier A2. One end of the resistor R13 is electrically connected to the output terminal of the operational amplifier A1 and a power supply terminal of the operational amplifier A2 respectively. The other end of the resistor R13 is electrically connected to the reverse input terminal of the operational amplifier A1. The positive input terminal of the operational amplifier A1 is electrically connected to the output terminal of the operational amplifier A2 via a series resistor. One end of the resistor R14 is electrically connected to another power supply terminal of the operational amplifier A2. The other end of the resistor R14 is electrically connected to the reverse input terminal of the operational amplifier A3. The positive input terminal of the operational amplifier A3 is electrically connected to the output terminal of the operational amplifier A2 via a series resistor.

[0022] like Figure 2 As shown, as the input voltage changes, the positive voltage V01 and the negative voltage V02 of the operational amplifier A2 also fluctuate accordingly, and the phases of the positive voltage V01 and the negative voltage V02 are equal. Despite this, the absolute value of the power supply voltage will always remain at 100V. The output voltage can reach up to 400VPP. Similarly, the inverting amplifier 112 includes an operational amplifier A4, an operational amplifier A5, and an operational amplifier A6, and the operational amplifiers A4, A5, and A6 form a voltage parallel negative feedback circuit. The inverting amplifier 112 specifically also includes a resistor R21, a resistor R22, a resistor R23, and a resistor R24. The positive input terminal of the operational amplifier A5 is grounded, one end of the resistor R21 is electrically connected to the negative output terminal of the high-voltage unit 12, and the other end is electrically connected to the reverse input terminal of the operational amplifier A5 and one end of the resistor R22, respectively. The other end of the resistor R22 is electrically connected to the reverse input terminal of the operational amplifier A5 and one end of the resistor R22. The output end of the operational amplifier A5 is electrically connected, one end of the resistor R23 is electrically connected to the output end of the operational amplifier A4 and a power supply end of the operational amplifier A5 respectively, the other end of the resistor R23 is electrically connected to the reverse input end of the operational amplifier A4, the positive input end of the operational amplifier A4 is electrically connected to the output end of the operational amplifier A5 via a series resistor, one end of the resistor R24 ​​is electrically connected to another power supply end of the operational amplifier A5, the other end of the resistor R24 ​​is electrically connected to the reverse input end of the operational amplifier A6, and the positive input end of the operational amplifier A6 is electrically connected to the output end of the operational amplifier A5 via a series resistor. In practice, its voltage gain can be adjusted to 20 times, and the total gain of the voltage amplifier circuit 11 will eventually reach 40 times. In actual operation, considering the maximum power supply voltage limit of 100V, the maximum swing of the input voltage should be limited to a smaller value to ensure that the amplifier is within the linear operating range.

[0023] like Figure 3 The output voltage range can be increased by cascading an external high voltage unit 12. By connecting n cascade units 10 in series to form a cascade circuit, the entire cascade circuit can obtain a gain of 40n times. The signal source VS0 is an arbitrary waveform generator that provides an input signal within a signal frequency range from mHz to kHz through software programming. The voltage source from Vs1 to Vsn can use an AMPX power supply, and each voltage source includes a linear voltage regulator module.

[0024] That is, the voltage amplifier circuit 11 uses a non-inverting amplifier 111 and an inverting amplifier 112, and the final output is the differential output between the non-inverting amplifier 111 and the inverting amplifier 112, so that the total gain of the voltage amplifier circuit 11 is the sum of the gain of the non-inverting amplifier 111 and the gain of the inverting amplifier 112. In addition, the output voltage range is increased by cascading the high-voltage unit 12, and multiple cascade units 10 connected in series can provide a higher gain.

[0025] There are many differences in the characteristics of multi-channel amplifiers and cascade amplifiers. A multi-channel amplifier is composed of multiple amplifiers connected in series. In the amplitude-frequency characteristics of a multi-channel amplifier, the relationship between the total gain and the unity gain is given by the formula: 20log|A U |=20log|A U1 |+20log|A U2 |+…+20log|A Un |.. For the phase-frequency characteristic, the total phase shift is The lower frequency limit is The frequency cap is The slew rate of the multi-channel amplifier is SR = 13 (V / μs). The amplitude-frequency characteristic of the cascade amplifier is the same as that of the multi-channel amplifier. Due to the cascade connection of the circuit units, the phase-frequency characteristic is The lower frequency limit is f L ≈f L1 ≈f L2 ≈…≈f Ln The upper frequency limit is f H ≈f H1 ≈f H2 ≈…≈f Hn. The slew rate is SR = 13 × 2n (V / μs). The transmission gain and phase error mainly depend on the difference of the cascade devices. Compared with the multi-channel amplifier, the cascade circuit has better flexibility and wider bandwidth. Relying on the increase in the number of multiple cascade units 10, the total gain is greatly increased, but the total bandwidth remains unchanged. And a single cascade unit 10 or the entire cascade circuit can provide the same current. Compared with the multi-channel amplifier, the cascade unit 10 has better flexibility and wider bandwidth, which is mainly reflected in the following aspects: 1. Flexibility in gain design. Multiple cascade units 10 are connected in series, and the total gain is the product of the gains of each cascade unit 10. The designer can adjust the gain of a single voltage amplifier circuit 11 to achieve precise control of the total gain. This step-by-step adjustment method is particularly flexible when achieving large gain requirements. 2. Flexibility in frequency response. The frequency characteristics of each stage of the voltage amplifier circuit 11 can be adjusted independently to avoid frequency distortion or bandwidth limitation. For example, the designer can improve the frequency response of the entire system by adding a high-pass or low-pass filter at a certain stage. 3. By allocating bandwidth to different amplification stages, wideband design can be more easily achieved. 4. Modular design makes fault isolation and maintenance easier. If a certain stage fails, only the circuit of that stage needs to be detected and repaired. However, due to the close coupling of each path, fault diagnosis of multi-channel amplifiers may be more complicated. In addition, each stage of voltage amplifier circuit 11 works independently, making it easy to upgrade or replace a single module.

[0026] Assuming the network is a pure resistance R load, the equivalent circuit diagram of the voltage parallel negative feedback (inverting amplifier 112) is as follows: Figure 4 As shown. Assume that the circuit unit gain at the intermediate frequency is A m , the upper frequency limit is f H , the lower limit frequency is f L Therefore, the gain A in the high frequency band h for After introducing negative feedback, the expression of high-frequency band gain Ahf can be rewritten as where F is the feedback factor. Rearrange to Among them A mf is the gain of the negative feedback amplifier circuit in the mid-frequency band. Hf Because of Hf =(1+A m F) H Defined upper frequency limit. Figure 4 In the equation, v is the signal source voltage and Rs is the internal resistance of v. i It is through r i The voltage, r i is the input resistance of the basic amplifier circuit. i is the input current of the amplifier. o is the output resistance of the amplifier. The output of the basic amplifier circuit can be equivalent to a voltage source V o=A o i i The equivalent output resistance r o Series, R f is the feedback resistor. After the introduction of negative feedback, the impact of input resistance is usually expressed as feedback depth (1+AF). Considering the internal resistance of the signal source and load does not fully convey the relationship between the various components of the output circuit and the input resistance. Figure 1 The general form of the voltage parallel negative feedback amplifier circuit of the operational amplifier A5 can be as follows Figure 1 As shown. According to Thevenin's theorem, when the load resistor RL is connected to the output terminal, the drop in the output voltage Vof will cause the input and output currents to change. Therefore, we get the output voltage to be According to Kirchhoff's current law, Figure 4 We get The output voltage is because Figure 1 The op amp A2 introduces series voltage negative feedback, and the input resistance will increase by (1+AF) times. It is worth noting that Figure 1 The input resistance of op amp A2 and op amp A5 is different. When selecting appropriate input resistance and feedback resistance in the operational amplifier, the effect of input resistance on amplifier accuracy can be ignored. Figure 2 As shown. The amplifier always has an internal output resistance, which causes the amplifier to be considered as an oscillator. When it is connected to a capacitive load, an additional pole is added to the transfer function of the amplifier circuit. The Bode plot of the additional pole is steeper than the Bode plot of the main pole, resulting in a phase shift of -90°. When the open-loop gain and feedback attenuation are both greater than 1, the amplifier circuit is unstable. If the operating frequency is lower than the closed-loop bandwidth, the loop phase shift will exceed 180°. Therefore, an operational amplifier will act as an oscillator, such as Figure 5 As shown, Figure 5 This is the frequency response relationship obtained using Texas Instruments' Tina analysis software.

[0027] The phase margin of an op amp circuit is defined as the phase difference between the phase at the gain crossover frequency and the phase at -180°. To extend the additional phase margin, the additional pole from the capacitive load should be greater than 10 times the closed-loop bandwidth in the circuit. The frequency of the additional pole is given by f p =1 / 2πR o c L When analyzing the step response of the amplifier circuit, a small signal equivalent circuit can be used. The step voltage can be divided into a rising curve and a saturation curve, and the circuit can be simplified according to its exponential characteristics. In the corresponding high-frequency range, some step voltages rise faster than the steady-state voltage. Therefore, a low-pass filter circuit can be used to describe this phenomenon. Figure 6 As shown, the output voltage is Where V sis the final stable value of the step response voltage. V o / V s The relationship with time is shown in Figure 7. Since the output voltage V o Increases exponentially, reaching a final voltage V s It takes a certain amount of time, which will cause the leading edge to be distorted. r (the duration from 10% to 90% of the final voltage) is used to represent the leading edge distortion, represented by t r =t 2 -t 1 =2RCln3 is given. Figure 6 The upper limit of the medium frequency is The rise time is therefore estimated to be From the above formula, we can know that the rise time t r With the upper frequency f H Inversely proportional. The higher the upper frequency, the shorter the rise time and the smaller the edge distortion. The upper frequency depends on the depth of negative feedback, but linear amplifiers usually require higher gain. In order to ensure smaller edge distortion and higher gain, the negative feedback depth is 1+AOLβ, where AOL is the open-loop gain and β is the feedback factor.

[0028] It is easy for those skilled in the art to understand that the above preferred embodiments can be freely combined and superimposed without conflict.

[0029] The above are only preferred embodiments of the present invention, and are not intended to limit the patent scope of the present invention. All equivalent structural changes made using the contents of the present invention's specification and drawings under the inventive concept of the present invention, or directly or indirectly applied in other related technical fields, are included in the patent protection scope of the present invention.

Claims

1. A linear voltage amplification system for high voltage, characterized in that: include: A plurality of cascade units (10), the cascade units (10) comprising a high voltage unit (12), a voltage source and a voltage amplifier circuit (11), the voltage amplifier circuit (11) comprising a non-inverting amplifier (111) and an inverting amplifier (112), the output of the voltage amplifier circuit (11) being a differential output between the non-inverting amplifier (111) and the inverting amplifier (112), the voltage source supplying power to the voltage amplifier circuit (11), the positive output end of the high voltage unit (12) being electrically connected to the input end of the non-inverting amplifier circuit, and the negative output end of the high voltage unit (12) being electrically connected to the input end of the inverting amplifier circuit; the plurality of cascade units (10) being connected in series to output high voltage.

2. The linear voltage amplification system for high voltage according to claim 1, characterized in that: The voltage source is a power source of AMPx, and each of the voltage sources includes a linear voltage regulator module.

3. The linear voltage amplification system for high voltage according to claim 1, characterized in that: The non-inverting amplifier (111) comprises an operational amplifier A1, an operational amplifier A2 and an operational amplifier A3, and the operational amplifiers A1, A2 and A3 form a voltage series negative feedback circuit, wherein the operational amplifiers A1 and A3 form a voltage follower to serve as a power supply for the operational amplifier A2.

4. The linear voltage amplification system for high voltage according to claim 3, characterized in that: The non-inverting amplifier (111) further comprises: a resistor R11, a resistor R12, a resistor R13, and a resistor R14. The positive input terminal of the operational amplifier A2 is electrically connected to the positive output terminal of the high voltage unit (12). One end of the resistor R11 is grounded, and the other end is electrically connected to the reverse input terminal of the operational amplifier A2 and one end of the resistor R12 respectively. The other end of the resistor R12 is electrically connected to the output terminal of the operational amplifier A2. One end of the resistor R13 is electrically connected to the output terminal of the operational amplifier A1 and a power supply terminal of the operational amplifier A2 respectively. The other end of the resistor R13 is electrically connected to the reverse input terminal of the operational amplifier A1. The positive input terminal of the operational amplifier A1 is electrically connected to the output terminal of the operational amplifier A2 via a series resistor. One end of the resistor R14 is electrically connected to another power supply terminal of the operational amplifier A2. The other end of the resistor R14 is electrically connected to the reverse input terminal of the operational amplifier A3. The positive input terminal of the operational amplifier A3 is electrically connected to the output terminal of the operational amplifier A2 via a series resistor.

5. The linear voltage amplification system for high voltage according to claim 1, characterized in that: The inverting amplifier (112) comprises an operational amplifier A4, an operational amplifier A5 and an operational amplifier A6, and the operational amplifier A4, the operational amplifier A5 and the operational amplifier A6 form a voltage parallel negative feedback circuit.

6. The linear voltage amplification system for high voltage according to claim 5, characterized in that: The inverting amplifier (112) further comprises: a resistor R21, a resistor R22, a resistor R23, and a resistor R24. The positive input terminal of the operational amplifier A5 is grounded. One end of the resistor R21 is electrically connected to the negative output terminal of the high voltage unit (12), and the other end is electrically connected to the reverse input terminal of the operational amplifier A5 and one end of the resistor R22, respectively. The other end of the resistor R22 is electrically connected to the output terminal of the operational amplifier A5. One end of the resistor R23 is electrically connected to the output terminal of the operational amplifier A4 and a power supply terminal of the operational amplifier A5, respectively. The other end of the resistor R23 is electrically connected to the reverse input terminal of the operational amplifier A4. The positive input terminal of the operational amplifier A4 is electrically connected to the output terminal of the operational amplifier A5 via a series resistor. One end of the resistor R24 ​​is electrically connected to another power supply terminal of the operational amplifier A5. The other end of the resistor R24 ​​is electrically connected to the reverse input terminal of the operational amplifier A6. The positive input terminal of the operational amplifier A6 is electrically connected to the output terminal of the operational amplifier A5 via a series resistor.

Images