High-voltage direct-current electronic load circuit

Abstract

The utility model provides a high-voltage direct-current electronic load circuit, and relates to the technical field of electronic load circuits. The voltage equalizing circuit comprises N voltage equalizing resistors which are connected in series and are arranged between high and low voltage ends of direct-current voltage; the N power field-effect transistors are connected to the high-voltage end of the direct-current voltage, drain sources of the N power field-effect transistors are sequentially connected and work in a variable resistance area, and the source electrode of the power field-effect transistor farthest from the high-voltage end of the direct-current voltage is grounded through a sampling resistor R6; the non-grounding end of the sampling resistor R6 is connected with a current inner loop control circuit realized based on a PI control circuit; the output of the current inner loop control circuit is connected to the grid electrode of the power field effect transistor farthest from the direct current voltage high-voltage end; and the grid electrodes of the other power field effect transistors are connected to one end, far away from the direct-current voltage high-voltage end, of the voltage-sharing resistor of the corresponding level. The power field-effect tube farthest from the direct-current voltage high-voltage end is directly controlled, the resistance state of other power field-effect tubes can be indirectly controlled to change, and the resistance of a current path formed by the power field-effect tubes is effectively changed.

Description

TECHNICAL FIELD

[0001] The utility model relates to electronic load circuit technical field especially relates to a high voltage direct current electronic load circuit. BACKGROUND

[0002] Load is the equipment that can consume energy, when testing electronic equipment such as power supply, battery, transformer, load is often used to test and age these equipment. Now mostly use resistor or slide rheostat as load, the shortcoming is that load is not easy to adjust continuously accurately, and also can not maintain constant current, constant power and other working conditions.

[0003] Electronic load mostly uses power field effect tube working in variable resistance area as load, the rated voltage of electronic load of conventional circuit topology is limited by the voltage resistance of power field effect tube. When the electronic equipment that can output thousands of volts even tens of thousands of volts needs to be tested, conventional circuit topology can not meet the requirement. Designing high voltage electronic load needs power field effect tube in series, the existing high voltage electronic load topology mostly uses power field effect tube in series, each power field effect tube is driven by independent isolation module, each isolation module generally contains isolation power supply, power field effect tube driving device, digital signal isolator or linear photocoupler etc. in actual application, and the driving circuit is very complex. Each isolation module receives output signal from control circuit, if strict voltage sharing control needs to be realized, the voltage of power field effect tube in series needs to be sampled respectively, and the sampling and control circuit is also very complex. If voltage sharing control is not added, due to the difference of power field effect tube characteristics, the power field effect tube conduction degree is not the same, and overvoltage breakdown is easy to occur. Therefore, the utility model provides a high voltage direct current electronic load circuit. CONTENT OF UTILITY MODEL

[0004] In order to solve the above technical problems or at least partially solve the above technical problems, the utility model provides a high voltage direct current electronic load circuit.

[0005] The utility model provides a high voltage direct current electronic load circuit, include: setting between high low voltage end of direct current voltage N series voltage sharing resistance, the low voltage end of direct current voltage is grounded;

[0006] The drain source connected in sequence in the high voltage end of direct current voltage N power field effect tubes working in variable resistance area, wherein the source electrode of the power field effect tube farthest from the high voltage end of direct current voltage is grounded through sampling resistance R6;

[0007] The non-grounded end of sampling resistance R6 is connected through the current inner loop control circuit based on PI control circuit; The output of current inner loop control circuit is connected to the gate of the power field effect tube farthest from the high voltage end of direct current voltage; The gate of the rest power field effect tube is connected to the end of corresponding level voltage sharing resistance far from the high voltage end of direct current voltage.

[0008] Further, the N power field effect tubes are of the same type, and the N voltage equalizing resistors are of the same resistance.

[0009] Further, each voltage equalizing resistor is connected in parallel with a filter capacitor, and the N filter capacitors are of the same capacitance.

[0010] Further, the PI control circuit comprises: a driving power amplifier U1, PI control resistors R10 and PI control capacitors C6 connected in series between the inverting input and the output of the driving power amplifier U1, a constant resistor R9 connecting the inverting input of the driving power amplifier U1 to a control voltage signal Vdr, the non-inverting input of the driving power amplifier U1 being grounded, the output of the driving power amplifier U1 being connected to the gate of the power field effect tube farthest from the high voltage end of the direct current voltage through a coupling resistor R7, and the inverting input of the driving power amplifier U1 being connected to the non-grounded end of a sampling resistor R6 through a feedback resistor R8.

[0011] Further, the resistance of the voltage equalizing resistor is such that the current flowing through the voltage equalizing resistor to form a current path is lower than the current flowing through the power field effect tube to form a current path by a set order of magnitude.

[0012] The above technical solution provided by the embodiment of the utility model has the following advantages compared with the prior art:

[0013] The high-voltage direct-current electronic load circuit provided by the utility model patent adopts a plurality of power field effect tubes in series, all the power field effect tubes work in a variable resistance region, a PI control circuit directly controls the power field effect tube farthest from the high voltage end of the direct current voltage, the PI control circuit serves as an inner loop of the current of the electronic load formed by the power field effect tubes in series, the remaining power field effect tubes in series are provided with gate voltages by voltage equalizing resistors, the change of the resistance state of the low-voltage side power field effect tube drives the change of the source voltage of the high-voltage side power field effect tube, thereby changing the gate-source voltage Vgs of the high-voltage side power field effect tube, and finally the effect is that the resistance state of the remaining power field effect tubes is indirectly changed by directly controlling the power field effect tube farthest from the high voltage end of the direct current voltage. BRIEF DESCRIPTION OF DRAWINGS

[0014] The accompanying drawings, which are incorporated into and form part of the specification, illustrate embodiments consistent with the utility model and, together with the specification, serve to explain the principles of the utility model.

[0015] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or prior art description, and obviously, for those skilled in the art, other drawings can also be obtained without creative labor.

[0016] Figure 1 A schematic diagram of a high-voltage direct-current electronic load circuit provided by the present application. DETAILED DESCRIPTION

[0017] In order to make the purpose, technical solutions and advantages of the embodiments of the present application more clear, the following will combine the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application, and obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the protection scope of the present application.

[0018] It should be noted that in this paper, the term "include", "contain" or any other variant thereof is intended to cover non-exclusive inclusion, so that the process, method, article or device including a series of elements not only includes those elements, but also includes other elements not explicitly listed, or includes elements inherent to such process, method, article or device. Without more limitations, the element defined by the sentence "including a" does not exclude the presence of other identical elements in the process, method, article or device including the element.

[0019] The present application realizes a kind of high-voltage direct-current electronic load circuit, comprising:

[0020] N series voltage-sharing resistors are arranged between the high and low voltage ends of direct current voltage. The low voltage end of direct current voltage is connected to the ground of control circuit. Each voltage-sharing resistor is connected in parallel with a filter capacitor. Wherein, the resistance values of the N voltage-sharing resistors are the same, and the capacitance values of the N filter capacitors are the same. The resistance values of the voltage-sharing resistors R1 to R5 are as large as possible, and the resistance values of the voltage-sharing resistors are such that the current flowing through the voltage-sharing resistors to form a current path is lower than the current flowing through the power field effect transistor to form a current path by a set order of magnitude.

[0021] N power field effect tubes working in variable resistance region are connected in series from drain to source to a high voltage end of a direct current voltage, wherein a source of the power field effect tube farthest from the high voltage end of the direct current voltage is grounded through a sampling resistor R6. A non-grounded end of the sampling resistor R6 is connected to a current inner loop control circuit realized based on a PI control circuit; an output of the current inner loop control circuit is connected to a gate of the power field effect tube farthest from the high voltage end of the direct current voltage; and gates of the remaining power field effect tubes are connected to far ends of corresponding level equalizing resistors away from the direct current voltage.

[0022] In the specific implementation process, as shown in Figure 1 Figure 1 The high voltage direct current electronic load circuit includes five equalizing resistors connected in series, which are equalizing resistor R1, equalizing resistor R2, equalizing resistor R3, equalizing resistor R4 and equalizing resistor R5, wherein the equalizing resistor R5 is connected to the direct current voltage, and the equalizing resistor R1 is grounded; and the equalizing resistor R1, the equalizing resistor R2, the equalizing resistor R3, the equalizing resistor R4 and the equalizing resistor R5 are respectively connected in parallel with the filter capacitor C1, the filter capacitor C2, the filter capacitor C3, the filter capacitor C4 and the filter capacitor C5.

[0023] Figure 1 The high voltage direct current electronic load circuit includes five power field effect tubes working in variable resistance region and connected in series from drain to source, which are power field effect tube Q1, power field effect tube Q2, power field effect tube Q3, power field effect tube Q4 and power field effect tube Q5, wherein a drain of the power field effect tube Q5 is connected to the direct current voltage, and a source of the power field effect tube Q1 is connected to the sampling resistor R6 which is grounded.

[0024] Figure 1 In the high voltage direct current electronic load circuit, a gate of the power field effect tube Q2 is connected to a far end of the equalizing resistor R2 away from the direct current voltage, a gate of the power field effect tube Q3 is connected to a far end of the equalizing resistor R3 away from the direct current voltage, a gate of the power field effect tube Q4 is connected to a far end of the equalizing resistor R4 away from the direct current voltage, and a gate of the power field effect tube Q5 is connected to a far end of the equalizing resistor R5 away from the direct current voltage.

[0025] Figure 1 In the high voltage direct current electronic load circuit, the PI control circuit includes: a driving power amplifier U1, a PI control resistor R10 and a PI control capacitor C6 connected in series between an inverting input end and an output end of the driving power amplifier U1, a control signal Vdr connected to the inverting input end of the driving power amplifier U1 through a constant resistor R9, a ground connected to a non-inverting input end of the driving power amplifier U1, a coupling resistor R7 connected to the gate of the power field effect tube farthest from the high voltage end of the direct current voltage through the output end of the driving power amplifier U1, and a feedback resistor R8 connected to the non-grounded end of the sampling resistor R6 through the inverting input end of the driving power amplifier U1.​

[0026] The principle of the high-voltage direct-current electronic load circuit of the present application is as follows:

[0027] When the driving power amplifier U1 changes the gate-source voltage Vgs of the power field effect tube Q1, the resistance state of the power field effect tube Q1 changes because the resistance value of the field effect tube in the variable resistance region is controlled by the gate-source voltage. The drain voltage of the power field effect tube Q1, that is, the source voltage of the power field effect tube Q2, changes, the gate-source voltage Vgs of the power field effect tube Q2 changes, and the resistance state of the power field effect tube Q2 changes. The drain voltage of the power field effect tube Q2, that is, the source voltage of the power field effect tube Q3, changes, the gate-source voltage Vgs of the power field effect tube Q3 changes, and the resistance state of the power field effect tube Q3 changes. The drain voltage of the power field effect tube Q3, that is, the source voltage of the power field effect tube Q4, changes, the gate-source voltage Vgs of the power field effect tube Q4 changes, and the resistance state of the power field effect tube Q4 changes. The drain voltage of the power field effect tube Q4, that is, the source voltage of the power field effect tube Q5, changes, the gate-source voltage Vgs of the power field effect tube Q5 changes, and the resistance state of the power field effect tube Q5 changes. The final effect is that the resistance state of the power field effect tubes Q2 to Q5 is changed indirectly by directly controlling the power field effect tube Q1. Because the resistances R1 to R5 have the same resistance value, and the gate-source voltage Vgs of the power field effect tube is much smaller than the drain-source voltage Vds, the drain-source voltages Vds of the power field effect tubes Q1 to Q5 are almost the same, and voltage equalization is achieved. The filter capacitors C1 to C5 prevent the sudden influence of interference ripple on the gate-source voltage Vgs of the power field effect tubes Q2 to Q5, prevent the sudden change of the gate-source voltage Vgs, and stabilize the working state of the power field effect tube.

[0028] Let the current flowing through the power field effect tubes in series connection form a current path be I. Because of the existence of the sampling resistor R6, the source voltage of the power field effect tube Q1 is I*R6. When the control reaches a steady state, the control voltage signal Vdr, the source voltage of the power field effect tube Q1, and the output of the PI control circuit have the following relationship:

[0029]

[0030] Obviously:

[0031]

[0032] That is, the control voltage signal Vdr outputted by the control loop is actually the current flowing through the power field effect tube multiplied by a coefficient determined by the feedback resistor R8, the fixed resistor R9 and the sampling resistor R6, that is, the PI control circuit in which the power amplifier U1 is located forms a current inner loop control circuit for controlling the current.

[0033] As can be seen from the above, the high-voltage direct-current electronic load circuit provided by the utility model patent adopts a plurality of power field effect tubes in series, all the power field effect tubes work in a variable resistance region, the PI control circuit directly controls the power field effect tube far away from the direct-current voltage, the PI control circuit is an inner loop of the electronic load formed by the series-connected power field effect tubes, the remaining series-connected power field effect tubes are provided with gate voltages by the voltage-sharing resistors, the resistance state of the low-voltage side power field effect tube changes to drive the change of the source voltage of the high-voltage side power field effect tube, thereby the gate-source voltage Vgs of the high-voltage side power field effect tube changes, and finally the resistance state of the power field effect tube Q2 to the power field effect tube Q5 can be indirectly controlled by directly controlling the power field effect tube Q1. By the way of controlling the power field effect tube by the voltage-sharing resistor, the series-connected power field effect tubes can be kept in the same state, voltage sharing is ensured, and the power field effect tubes can be effectively prevented from being damaged by overvoltage. The high-voltage direct-current electronic load circuit does not need an isolating device, the driving control circuit is relatively simple, and the cost can be effectively reduced.

[0034] In the embodiments provided in the utility model, it should be understood that the disclosed structure can be realized by other ways. For example, the structural embodiments described above are only illustrative. For example, the division of the units is only a logical function division, and actual implementation can have another division mode. For example, multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. In addition, the coupling or direct coupling or communication connection between the units shown or discussed can be indirect coupling or communication connection through some interfaces, structures or units, and can be electrical, mechanical or other forms.

[0035] The units described as separate components can or can not be physically separated, and the components shown as units can or can not be physical units, that is, they can be located in one place or distributed on multiple network units. According to actual needs, part or all of the units can be selected to achieve the purpose of the embodiment scheme.

[0036] In addition, the functional units in each embodiment of the utility model can be integrated in one processing unit, or each unit can exist physically, or two or more units can be integrated in one unit. The integrated unit can be realized in the form of hardware or in the form of a software functional unit.

[0037] The foregoing merely illustrates the principles of the application and various modifications can be devised by those skilled in the art without departing from the spirit or scope of the application. The present application is thus not intended to be limited to the particular embodiments described herein, but rather only by the scope of the appended claims, and their equivalents.

Claims

1. A high voltage direct current electronic load circuit, characterized by, The application relates to a DC voltage equalizing circuit. N series-connected equalizing resistors arranged between high and low voltage ends of a DC voltage, with the low voltage end connected to ground; N power field effect tubes connected in turn to the high voltage end of the DC voltage and working in a variable resistance region, wherein the source of the power field effect tube farthest from the high voltage end of the DC voltage is connected to ground through a sampling resistor R6; The non-grounded end of the sampling resistor R6 is connected to a current inner loop control circuit based on a PI control circuit; the output of the current inner loop control circuit is connected to the gate of the power field effect tube farthest from the high voltage end of the DC voltage; and the gates of the remaining power field effect tubes are connected to the end of the corresponding level equalizing resistor far from the high voltage end of the DC voltage.

2. The HVDC electronic load circuit of claim 1, wherein, The N power field effect tubes are of the same type, and the N equalizing resistors have the same resistance.

3. The HVDC electronic load circuit of claim 1, wherein, Each equalizing resistor is connected in parallel with a filter capacitor, and the N filter capacitors have the same capacitance.

4. The HVDC electronic load circuit of claim 1, wherein, The PI control circuit comprises a driving power amplifier U1, PI control resistor R10 and PI control capacitor C6 connected in series between the inverting input end and the output end of the driving power amplifier U1, control voltage signal Vdr connected to the inverting input end of the driving power amplifier U1 through a constant resistor R9, the non-inverting input end of the driving power amplifier U1 connected to ground, the output end of the driving power amplifier U1 connected to the gate of the power field effect tube farthest from the high voltage end of the DC voltage through a coupling resistor R7, and the inverting input end of the driving power amplifier U1 connected to the non-grounded end of the sampling resistor R6 through a feedback resistor R8.

5. The HVDC electronic load circuit of claim 1, wherein, The resistance of the equalizing resistor is such that the current flowing through the equalizing resistor to form a current path is lower than the current flowing through the power field effect tube to form a current path by a set order of magnitude.

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