CN116418195A

CN116418195A - Output voltage compensation method

Info

Publication number: CN116418195A
Application number: CN202111634153.8A
Authority: CN
Inventors: 方智焕
Original assignee: Chroma ATE Suzhou Co Ltd
Current assignee: Chroma ATE Suzhou Co Ltd
Priority date: 2021-12-29
Filing date: 2021-12-29
Publication date: 2023-07-11

Abstract

The application provides an output voltage compensation method which is applicable to a direct current voltage source with a constant voltage circuit and a constant current circuit which are connected in series, wherein the direct current voltage source is used for providing output voltage to a component to be tested, and the output voltage compensation method comprises the following steps. Firstly, generating a voltage compensation value according to the pulling current and the gain parameter of the component to be tested. Then, a virtual current set point is generated according to the voltage set point and the voltage compensation value. And generating a duty cycle command according to the virtual current set value and the pull-load current measured value of the pull-load current. And generating an output voltage according with the voltage set value according to the duty cycle command. Wherein the gain parameter is related to the multiplying power parameter of the constant voltage circuit.

Description

Output voltage compensation method

Technical Field

The present disclosure relates to an output voltage compensation method, and more particularly, to an output voltage compensation method for a dc voltage source.

Background

In general, if the direct current voltage source is to be provided with a constant voltage circuit and a constant current circuit at the same time, the constant voltage circuit may be selected to be connected in series with the constant current circuit, or the constant current circuit may be selected to be connected in series with the constant voltage circuit. For safety reasons, when designing such a dc voltage source, a constant voltage circuit is connected in series to a constant current circuit, and an output voltage is provided by this series design. The reason is that under the switching of different modes, for example, when the constant current mode is switched to the constant voltage mode, the current surge is easily caused to cause the current at the output end to be excessively large instantaneously, which may cause the damage of the component to be tested and also cause the problem of safety. Therefore, the constant current circuit is used for controlling the current at the output end, so that the condition of current runaway can be avoided.

However, under the architecture that the constant voltage circuit is connected in series to the constant current circuit, when the dc voltage source is pulled by the device under test, it is found that the output voltage of the dc voltage source is not stable. For example, the current value of the pull-up current of the device under test may be a cause of unstable output voltage of the dc voltage source. Accordingly, there is a need for an output voltage compensation method that can operate a dc voltage source connected in series to a constant current circuit in the constant voltage circuit, so as to solve the problem of unstable output voltage of the dc voltage source.

Disclosure of Invention

The technical problem to be solved in the application is to provide an output voltage compensation method, which can generate a voltage compensation value to compensate the output voltage according to the measured value of the pull-load current of the component to be tested, so that the compensated output voltage can accord with a default voltage set value.

In some embodiments, the gain parameter may be further related to a line impedance between the dc voltage source and the device under test. Here, the step of generating the virtual current set point according to the voltage set point and the voltage compensation value may further include: comparing the corrected voltage set point with an output voltage measurement value of the output voltage to obtain a voltage error value. And converting the voltage error value by the constant voltage compensator to obtain a virtual current set value, and correcting the sum of the voltage set value and the voltage compensation value. In addition, the step of generating the duty cycle command according to the virtual current set point and the pull-up current measurement value of the pull-up current may further include: comparing the virtual current set value with the pull-load current measured value to obtain a current error value; and converting the current error value by the constant current compensator to obtain the working period instruction. Then, the duty cycle command is converted by pulse width modulation to generate the output voltage corresponding to the voltage set point.

In summary, the output voltage compensation method provided by the present application can generate the voltage compensation value to compensate the output voltage according to the measured value of the pull-load current of the component to be tested, so that the compensated output voltage can conform to the default voltage set value. In addition, the output voltage compensation method can also compensate the line impedance between the direct-current voltage source and the component to be tested, so that the component to be tested can receive the compensated stable voltage by using the direct-current voltage source.

Other details of the other functions and embodiments of the present application are described below with reference to the drawings.

Drawings

In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings that are required to be used in the embodiments or the description of the prior art will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments described in the present application, and other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.

FIG. 1 is a functional block diagram of a DC voltage source according to an embodiment of the present application;

FIG. 2 is a schematic diagram illustrating an output voltage compensation method according to an embodiment of the present application;

FIG. 3 is a flow chart illustrating steps of an output voltage compensation method according to an embodiment of the present application.

Symbol description

1. DC voltage source 10 constant voltage circuit

12. Constant current circuit 14 connection line

20. Constant voltage compensator 22 constant current compensator

24. Pulse width modulator DUT component to be tested

S30-S36 step flow

Detailed Description

The positional relationship described in the following embodiments includes: the upper, lower, left and right, unless otherwise indicated, are relative to the orientation of the elements shown in the drawings.

Referring to fig. 1 and fig. 2 together, fig. 1 is a functional block diagram of a dc voltage source according to an embodiment of the present application, and fig. 2 is a schematic operation diagram of an output voltage compensation method according to an embodiment of the present application. As shown in the figure, the output voltage compensation method proposed in the present application can be applied to a dc voltage source 1, where the dc voltage source 1 has a constant voltage circuit 10 and a constant current circuit 12 connected in series. The constant current circuit 12 is used as an output terminal of the dc voltage source 1 and can be electrically connected to the DUT via the connection line 14. In one example, the DUT may be considered a load and may consume power from the DC voltage source 1. In practice, when the DUT is in operation, the DUT will be pulled toward the dc voltage source 1, i.e. the current provided by the dc voltage source 1 is drawn. Generally, when the DUT is pulled toward the dc voltage source 1, the output voltage Vout of the dc voltage source 1 may drop slightly. The output voltage compensation method of the present embodiment is to compensate the output voltage Vout provided by the dc voltage source 1, so as to solve the problem of the output voltage Vout dropping.

In one example, the dc voltage source 1 is to provide a default output voltage to the DUT, the value of which is referred to as the voltage set point Vset in this embodiment. However, because of non-ideal components of the dc voltage source 1, the value of the output voltage Vout measured at the output of the dc voltage source 1 may not be equal to the voltage set point Vset. In this embodiment, the value of the output voltage Vout measured by the output terminal is referred to as an output voltage measurement value Vmea, and the voltage set value Vset is generally greater than or equal to the output voltage measurement value Vmea. In order to compensate for the problem that the voltage set value Vset is not equal to the output voltage measurement value Vmea, the voltage compensation value is added to the voltage set value Vset in this embodiment, so that the corrected voltage set value can make the value of the output voltage Vout measured by the output terminal (i.e., the output voltage measurement value Vmea) equal to the voltage set value Vset.

The present embodiment provides a way to calculate the corrected voltage set point, such as the operation shown in fig. 2, assuming a voltage error value between the voltage set point Vset and the output voltage measurement value Vmea, which can be converted into a virtual current set point by the feed-in constant voltage compensator 20 (constant voltage circuit). For convenience of explanation, in this embodiment, the mathematical expression (1) is expressed by an operation in the frequency domain as follows:

(Vset(s)-Vmea(s))×CV＝Iset’(s) (1)

in the above equation (1), vset(s) represents the voltage set value Vset in the frequency domain, vmea(s) represents the output voltage measured value Vmea in the frequency domain, and CV represents the conversion means of the constant voltage compensator 20, and the constant voltage compensator 20 corresponds to the constant voltage circuit 10. Iset'(s) represents the virtual current set point in the frequency domain. Here, the constant voltage compensator 20 is a conversion function for the constant voltage circuit 10, and is, for example, a digital control means for converting a voltage into a current. Unlike the current set value (Iset) which is directly set, the current set value converted through the constant voltage compensator 20 in the frequency domain is represented as a virtual current set value Iset'(s) in this embodiment. In one example, the voltage error value is the difference between the voltage set value Vset(s) of the equation (1) and the output voltage measurement value Vmea(s), and one of the aforementioned voltage compensation values is to compensate for the voltage error value.

Then, the present embodiment compares the virtual current set point with the pull-up current measured value to obtain a current error value. The constant current compensator 22 converts the current error value to obtain the duty cycle command. The operation expression in the frequency domain (2) is as follows:

(Iset’(s)-Imea(s))×CC＝D (2)

in the above equation (2), imea(s) represents the pulling current measurement Imea in the frequency domain. Here, the measurement value Imea of the pulling current is related to the pulling current of the DUT, i.e. the value obtained by measuring the pulling current. CC represents the conversion means of the constant current compensator 22, and the constant current compensator 22 corresponds to the constant current circuit 12 described above. Here, the constant current compensator 22 is also a conversion function for the constant current circuit 12, and is, for example, a digital control means converting a current into a duty cycle command D in Pulse Width Modulation (PWM). Next, the duty cycle command D may be converted into an output voltage Vout having an output voltage measurement Vmea(s) through pulse width modulation, expressed by the following equation (3):

D×F＝Vmea(s) (3)

where F is the default input voltage parameter of the PWM converter, and the duty cycle command D is fed to the PWM converter 24 to generate the output voltage measurement Vmeas(s). In order to determine how to compensate the voltage error value, in this embodiment, the expression (1) and the expression (2) are substituted into the expression (3), and the expression (4) is as follows:

(((Vset(s)-Vmea(s))×CV)-Imea(s))×CC×F＝Vmea(s) (4)

the expression of the output voltage measurement value Vmea(s) is sorted out by the expression (4), and the expression (5) can be obtained:

Vmea(s)＝((Vset(s)×CV)-Imea(s))×CC×F/(1+CV×CC×F) (5)

the frequency domain s is zero when the time domain t is infinite according to the final value theory, and is generally (cv×cc×f) much greater than 1, so that the mathematical expression (6) and the mathematical expression (7) can be obtained as follows:

Vmea(s)＝((Vset(s)×CV)-Imea(s))/CV (6)

Vmea(s)＝Vset(s)-Imea(s)/CV (7)

since CV can be expressed as equation (8), when s is zero, CV can be expressed as equation (9) obtained by substituting one magnification parameter K into equation (7):

CV＝K(s/ωz+1)/(s/ωp+1) (8)

Vmea＝Vset-Imea/K (9)

in practice, the multiplying factor K is known in the conversion means of the constant voltage compensator 20. The present embodiment converts the inverse of the magnification parameter K into the gain parameter G can be expressed as the mathematical formula (10):

Vmea＝Vset-Imea×G (10)

through the above calculation, the difference between the voltage set value Vset and the output voltage measurement value Vmea can be determined by the equation (10) as imea×g. That is, assuming that the present embodiment compensates imea×g to the voltage set value Vset, let the new voltage set value Vset 'be equal to the sum of imea×g and the voltage set value Vset, it means that the voltage set value Vset in equation (10) is substituted with the voltage set value Vset' in equation (11). Then the output voltage measurement Vmea should coincide with the voltage set point Vset when the dc voltage source 1 is set to the voltage set point Vset'. Here, the new voltage set value Vset' may be expressed as expression (11), and the output voltage measured value Vmea after substitution into expression (10) may be expressed as expression (12):

Vset’＝Vset+Imea×G (11)

Vmea＝(Vset+Imea×G)-Imea×G＝Vset (12)

based on the above, the present embodiment can derive the voltage compensation value related to the pull-up current (pull-up current measurement Imea) and the gain parameter G of the DUT. The gain parameter G is in ohms (V/a), and since the magnification parameter K is known, the gain parameter G, which is the inverse of the magnification parameter K, should also be known. The present embodiment demonstrates a method of compensating the voltage set point Vset according to different pulling current measurement values Imea and known gain parameters G, and the compensated voltage set point Vset' can make the output voltage of the dc voltage source 1 conform to the voltage set point Vset. However, since the connection 14 is in fact a non-ideal component in fig. 1, the output voltage Vout received by the component under test DUT may additionally be subject to errors after passing through the connection 14. To solve the above problem, the present embodiment exemplifies that the output voltage Vout received by the DUT can be corrected by further adjusting the gain parameter G.

As a practical example, the line impedance of the connection line 14 may be measured in advance, assuming 40mΩ. Further, assuming that the multiplying factor parameter K of the constant voltage compensator 20 is 80, the gain parameter G is the inverse (1/80) of the multiplying factor parameter K, that is, 12.5mΩ. If the gain parameter G is substituted with 12.5m according to the equation (11), this means that the compensated voltage set point Vset' can be set to the voltage set point Vset for the output voltage Vout of the dc voltage source 1. However, if the gain parameter G is substituted with 52.5m (12.5 m+40 m), this means that the compensated voltage set point Vset' allows the output voltage Vout received by the device under test DUT to correspond to the voltage set point Vset. The present embodiment realizes an output voltage compensation method in which the compensation position can be arbitrarily set, without considering the line impedance of the connection line 14 if only the output terminal of the direct current voltage source 1 is compensated. If the circuit impedance of the connection line 14 is compensated for the gain parameter G, the circuit impedance is compensated for at the receiving end of the DUT.

For further explanation of the output voltage compensation method of the present application, please refer to fig. 1 to 3 together, fig. 3 is a flowchart illustrating steps of the output voltage compensation method according to an embodiment of the present application. As shown in the figure, in step S30, a voltage compensation value is generated according to the pull-up current and the gain parameter G of the DUT, and the voltage compensation value is (imea×g) in the mathematical formula (11). In step S32, a virtual current set point is generated according to the voltage set point Vset and the voltage compensation value (imea×g). The compensated voltage set value Vset ' is the sum of the voltage set value Vset and the voltage compensation value (imea×g) as in equation (11), and the compensated voltage set value Vset ' is converted into the frequency domain and substituted into equation (1) to calculate the corresponding virtual current set value Iset '(s). In step S34, a duty cycle command D is generated according to the virtual current set value Iset' (S) and the pull-up current measurement value Imea of the pull-up current. Next, in step S36, an output voltage Vout according to the voltage set value Vset is generated according to the duty command D. As can be seen from the above, since the virtual current set point Iset '(s) already corresponds to the compensated voltage set point Vset', the duty cycle command D and the Pulse Width Modulation (PWM) converted output voltage Vout should have the voltage error value eliminated, so that the output voltage Vout will conform to the voltage set point Vset.

The above examples and/or embodiments are merely for illustrating the preferred examples and/or embodiments for implementing the technology of the present application, and are not limited in any way to the embodiments of the technology of the present application, and any person skilled in the art should be able to make some changes or modifications to other equivalent examples without departing from the scope of the technical means disclosed in the present application, but should still consider the technology or examples substantially identical to the present application.

Claims

1. An output voltage compensation method, suitable for a direct current voltage source of at least a series connection of certain voltage circuits, the direct current voltage source is used for providing an output voltage to a component to be tested, the output voltage compensation method comprises:

generating a voltage compensation value according to a pull-load current and a gain parameter of the component to be tested;

generating a virtual current set value according to a voltage set value and the voltage compensation value;

generating a duty cycle command according to the virtual current set point and a pull-load current measured value of the pull-load current; and

generating the output voltage according to the duty cycle command;

wherein the gain parameter is related to a multiplying factor parameter of the constant voltage circuit.

2. The method of claim 1, wherein the gain parameter is further related to a line impedance between the dc voltage source and the device under test.

3. The method of claim 1, wherein the step of generating the virtual current set point according to the voltage set point and the voltage compensation value further comprises:

comparing a corrected voltage set point with an output voltage measurement value of the output voltage to obtain the voltage error value; and

converting the voltage error value by a certain voltage compensator to obtain the virtual current set value;

wherein the corrected voltage set point is the sum of the voltage set point and the voltage compensation value.

4. The method of claim 1, wherein generating the duty cycle command according to the virtual current set point and the pull-up current measurement of the pull-up current further comprises:

comparing the virtual current set value with the pull-load current measured value to obtain a current error value; and

the duty cycle command is obtained by converting the current error value with a current compensator.

5. The method of claim 1, further comprising converting the duty cycle command by pulse width modulation to generate the output voltage corresponding to the voltage set point.